Diagnostic_and_Surgical_Arthroscopy_in_the_Horse

In 1984, Casscellsstated "Diagnostic arthroscopy and, perhaps evenmore important, arthroscopic surgery constitute what is probably the outstanding achievement in orthopedic surgery in the past decade" (Casscells1984). While the author of this statement would probably admit to being biased, it is a fair reflection on the success and acceptance of the role of arthroscopy in human orthopedics. Although generally considered a modern surgical procedure, the technique took considerable time to develop. The first endoscopic examination of a knee joint was performed in 1918 by ProfessorTakagi at the University of Tokyo (Takagi 1933). Later the technique was pioneered in the United States by Burman and colleagues (Burman 1930, Burmanet aI1934). The first practical arthroscopewas developed by Watanabe (a pupil of Takagi) in 1960 (Watanabe 1960), and he also developedsomebasic principles for arthroscopy of the knee. In 1965, his techniques were brought to North American by Robert Jackson of Toronto (Jackson1987).

In the early 1970s, the arthroscope began to achieve real clinical use (Casscells1971, Jackson& Dandy 1972), and the first course in arthroscopy of the human knee in the United States was given in 1973. The procedure of diagnostic arthroscopy initially met with considerable skepticism within circles of human orthopedic specialists until its value was demonstrated in the total evaluation of the knee (Dandy & Jackson 1975, Watanabe et a11978, Casscells1980). Thereafter, arthroscopy became firmly established as a diagnostic tool in human orthopedic practice, and these early days have been the subject of reviews by Casscells(1987) and Jackson (1987); the interested reader is referred to these sources for more information.

In the middle of the 1970s, arthroscopy moved into the second phase of its development, with the realization of the potential to perform surgery under arthroscopic visualization (O'Connor 1974, 1977, Dandy 1981, Jackson 1983). The development of appropriate techniques and suitable instrumentation followed (Johnson 1977, O'Connor 1977, Dandy 1981). It also became apparent that the therapeutic advantages of arthroscopy included not only the surgical procedures per se (which can be grouped under the heading of surgical arthroscopy or arthroscopic surgery) but also the benefits from joint lavage and lysis of adhesions (Jackson 1974, O'Connor 1974). The advantages were low morbidity, early postoperative movement and reduced hospitalization times.

Impressive advances then occurred in both technology and technique.The first arthroscopic surgery was meniscectomy in humans, followed by procedures such as patellofemoral malalignment, abrasion arthroplasty, shaving for chondromalacia, and synovectomy. The advantages of arthroscopic meniscectomy have been well documented and arthrotomy is now a rarity (Pettrone 1982, McGinty 1987). The management of conditions involving the meniscus is also a good example of how new conceptshave evolved from the increased diagnostic accuracy afforded by arthroscopy and the potential to re-examine a knee with minimal morbidity Gackson1986).

The most important of these new concepts was probably the preservation of meniscal tissue, which led to the technique of partial meniscectomy and then to initial arthroscopic repair (Keene et al 1987). The development of more complex procedures followed and cruciate repairs are now performed arthroscopically (Shrock & Jackson 1996). The use of arthroscopy in man now encompassesthe shoulder, elbow, wrist, digital, ankle, hip, and temporomandibular joints Gohnson 1986). It is the most common orthopedic procedure performed today; current estimates cite approximately 9000 orthopedic surgeons performing arthroscopy in the United States alone (McGinty 1987).

Arthroscopy in the horse has gone through a similar evolution. In 1949, the human pioneer Watanabe reported arthroscopy of the equine hock. Large animal arthroscopy was first presented in the German literature in 1973 (Knezevic pers com 1984) and appeared in the English language in 1975 and 1977 (Smith 1975, Knezevic& Wruhs 1977). Diagnostic arthroscopy of the equine carpus was first reported in 1974 (Hall & Keeran 1975), but was described more extensively by McIlwraith & Fesslerin 1978. Reports of its use in other joints followed and diagnostic arthroscopy of the equine stifle joint was reported in 1982 (Nickels & Sande 1982).

As in human orthopedics, use of the arthroscope in horses extended into surgical practice as technology and techniques of triangulation developed. Some surgical manipulations under arthroscopic visualization in the horse were mentioned

by Knezevic & Wruhs in 1977, but arthrotomy remained the acceptedmeans of completing surgery. The first description of equine arthroscopic surgery involved the carpus (Ommert 1981, Valdez et al1983) and further descriptions involved the carpal, fetlock, tarsocrural, and femoropatellar joints

198J). Uescriptions of diagnostic and surgical arthroscopic procedures in the carpal, fetlock. tarsocrural and femoropatellar joints were detailed in textbook form in 1984 (McIlwraith 1984b). At that time, the first author used arthroscopic surgery as the routine method of joint surgery for virtually all conditions, with the exception of subchondral cystic lesions of the medial condyle of the femur. some carpal slab fractures. and fractures of the proximal sesamoidbones.

Arthroscopic techniques were subsequently developed and described in the second edition of the book in 1990 (McIlwraith 1990a). The use of arthroscopic surgery in the treatment of third carpal slab fractures was reported by Richardson in 1986; its use in the treatment of subchondral cystic lesions in the medial condyle of the femur was documented originally by Lewis in 1987. Techniques for diagnostic and surgical arthroscopy of the shoulder were described in 1987 (Bertone & McIlwraith 1987. Bertone et al 1987.

Nixon 1987). At the time of the second edition, arthroscopy had also been performed in the distal interphalangeal. proximal interphalangeal, and elbow joints. Arthroscopes had also been used in the sinuses and tendon sheaths (McIlwraith 1990a).

By 1990, arthroscopy in the horse had gone from being a diagnostic technique used by a few veterinarians to the accepted way of performing joint surgery. Prospective and retrospective data substantiated the value of the technique in the treatment of carpal chip fractures (McIlwraith et al19 8 7). fragmentation of the dorsal margin of the proximal phalanx (Yovich & McIlwraith 1986). carpal slabfractures (Richardson 1986), osteochondritis dissecans of the femoropatellar joint (Martin & McIlwraith 1985a, McIlwraith & Martin 1985), osteochondritis dissecansof the shoulder (Bertone et alI987). and subchondral cystic lesions of the femur (Lewis 1987).

During this period. the use of diagnostic arthroscopy led to the recognition of previously undescribed articular lesions, many of which are now also treated using arthroscopic techniques.

Since 1990. there has been further sophistication of techniques: new ones have been developed and treatment principles have been changed based on new pathobiologic knowledge and further prospective and retrospective studies defining the success of various procedures. Many of these recent advances have been recorded in a recent publication (McIlwraith 2002a). For example. there has been further documentation of success rates following arthroscopic removal of fragments from the dorsoproximal margin of the proximal phalanx (Kawcak & McIlwraith 1994, Colon et al 2000). Advances in understanding the pathogenesis of osteochondral disease and fragmentation in the carpus and fetlock have also been reported (Kawcak et al 2000. 2001). which naturally led to progress in diagnosis and treatment.

Parameters for the surgical treatment of joint injury have been carefully defined (McIlwraith & Bramlage 1996).

Arthroscopic treatment of fractures in the previously considered inaccessible palmar aspect of the carpus has been described (Wilke et al 2001) together with arthroscopy of the palmar aspect of the distal interphalangeal joint

also led to understanding of the contribution of soft tissue lesions to joint disease. In the carpus, tearing of the medial palmar intercarpal ligament was first reported by Mcllwraith in 1992 and its implications discussed by Phillips & Wright (1994) and Whitton et al (1997a,b,c).

In the fetlock joints, successrates following arthroscopic removal of osteochondral fragments of the palmar/plantar aspect of the proximal phalanx have now been documented (Foerner et al 1987, Fortier et al 1995), and results for arthroscopic treatment of osteochondritis dissecans of the distal dorsal aspect of the third metacarpal/metatarsal bones have been reported (Mcllwraith & Vorhees 1990). Results of arthroscopic surgery to treat apical (Southwood & Mcllwraith unpublished data), abaxial (Southwood et al 1998a), and basilar (Southwood & Mcllwraith 2000) fragments of the sesamoidbones are also available in the literature.

Since the last edition, the results of arthroscopic surgery for the treatment of osteochondritis dissecans in the tarsocrural joint have been documented (Mcllwraith et al1991) and the arthroscopic approach and intra-articular anatomy of the plantar pouch of the joint have also been described (Zamos et aI1994).

Considerable advances have been made in arthroscopic surgery of the stille joints. The results of arthroscopic surgery for the treatment of osteochondritis dissecans of the femoropatellar joint have been reported by Foland et al (1992). The syndrome of fragmentation of the distal apex of the patella was recognized and its treatment reported (Mcllwraith 1992). The use of arthroscopic surgery for treating certain patellar fractures was discussed in the previous edition and has since been reported in the literature (Marble & Sullins 2000).

In the femorotibial joints, the use of arthroscopic surgery to treat subchondral cystic lesions of the medial condyle of the femur (Howard et al19 9 5) and proximal tibia (Textor et al 2001) have been reported. Cartilage lesions of the medial femoral condyle have also been described (Schneider et al 1997). Arthroscopy has allowed great advancesin the recognition and treatment of meniscal tears and cruciate injuries (Walmsley 1995, 2002; Walmsleyet al2003). It has also been used to remove fragments from the intercondylar eminence of the tibia (Mueller et al1994) and allow internal fixation of another case of intercondylar eminence fracture (Walmsley 1997). Techniqueshave also beendevelopedfor diagnostic and surgical arthroscopy of the caudal pouches of the femorotibial joints (Stick et al 1992, Hance et al 1993, Trumble et al 1994). In addition, a single cranial arthroscopic approach to all three joint compartments has been developed by Boening (1995) and further reported by Peroni & Stick (2002).

Diagnostic and surgical arthroscopy of the coxofemoral joint has been described (Nixon 1994, Honnas et al1993), lesions identified and surgical treatments performed. The use of the arthroscope is also no longer confined to the limbs, and the anatomy of the temporomandibular joint has been described recently (Weller et aI2002).

The use of arthroscopy in assisting repair with internal fixation of articular fractures has become routine. This

includes fractures of the metacarpal/metatarsal condyles and carpal slabfractures (Richardson2002, Bassage& Richardson 1998, Zekas et aI1999), Techniques have been described for evaluation and treatment of so-called small joints, such as the distal and proximal interphalangeal joints (Boening 2002, Boening et a11990, Vail & McIlwraith 1992, Schneider et al 1994), In addition, joints in which lamenessis less commonly encountered. such as the elbow can also be examined and treated arthroscopically (Nixon 1990), Arthroscopic techniques for cartilage repair have been developed and recently reviewed (McIlwraith & Nixon 1996, Nixon 2002b), In general, we have tried to developtechniques that enhance both the quantity and hyaline characteristics of cartilage repair tissue while using the well-documented advantages of arthroscopic surgery. Techniques include cartilage debridement, cartilage reattachment. chondroplasty and subchondral microfracture (micropicking) (McIlwraith & Nixon 1996, Frisbie et al1999, Nixon 2002b).

The use of the arthroscope for evaluation and treatment of tendon sheath problems has been another area of major advancement. The arthroscope has been used to assessand treat tenosynovitis of the digital flexor tendon sheath, and techniques for endoscopically assisted annular ligament releasehave beendescribed (Nixon 1990b. 2002a. Nixon et al 1993. Fortier et aI1999). Intrathecal longitudinal tears of the digital flexor tendons have also been described by Wright & McMahon (1999) and by Wilderjans et al (2003). The arthroscope has also been increasingly useful for carpal sheath conditions (McIlwraith 2002a. Nixon et a12003, Textor et al 2003); arthroscopic approaches have been described by Cauvin et al (1997) and Southwood et al (1998b). Removal of radial osteochondromas using arthroscopic visualization is a significantly improved technique to open approaches (Squire et al 1992) and has produced excellent results (Southwood et al1999, Nixon et al2003, McIlwraith 2002b).

The use of tenoscopic division of the carpal retinaculum to openthe carpal canal has been recently described (Textor et al 2003) and superior check ligament desmotomy is now done arthroscopically (Southwood et al 1997, Kretz 2001. Techniques for tenoscopy of the tarsal sheath have been described

by Cauvin et al (1999) and methods of treatment reported by Nixon (2002a).

Synovial bursae have also been examined with the arthroscope. Techniques have been described for arthroscopy for the intertubercular bursa (Adams & Turner 1999), the calcanealbursa (Ingle-Fehr & Baxter 1998). and the navicular bursa (Wright et aI1999). To date, reports in the literature have beendominated by casesof contamination and infection. but lesions which explain previously undiagnosed lameness referable to these sites have now been identified and treated endoscopically.

Specific advantages of arthroscopy as a diagnostic and surgical tool are mentioned throughout this book.

General advantages of the technique previously recognized include:

1. An individual joint canbeexaminedaccuratelythrough a small (stab)incision and with greateraccuracythan was

previously possible. With the availability of such an a traumatic technique. numerous lesions and "new" conditions that are not detected radiographically can be recognized.

2. All types of surgical manipulations can be performed through stab incisions under arthroscopic visualization.

The use of this form of surgery is less traumatic, less painful, and provides immense cosmetic and functional advantages. Surgical intervention is now possible in situations where it would not have been attempted previously. The decreasedconvalescencetime with earlier return to work and improved performance is a significant advance in the management of equine joint problems. The need for palliative therapies is decreased,as is the number of permanently compromised joints.

The initial optimism and advantages of arthroscopy in equine orthopedic practice suggestedin the first two editions of this book have been substantiated. It is now accepted that equine arthroscopic surgery has revolutionized equine orthopedics. Problems have and will continue to be encountered, but we know now that many are avoidable. Although the technique appears uncomplicated and attractive to the inexperienced surgeon, some natural dexterity, good threedimensional anatomical knowledge, and considerablepractice are required for the technique to be performed optimally.

Experience and good case selection are of paramount importance and reiterating a passagefrom the first edition of this book remains as pertinent today: In 1975. arthroscopywas underused and needlessarthrotomies were performed. The pendulum is now swinging rapidly in the other direction. The current tendency in arthroscopy is toward overuse. Some surgeons seems to be unable to distinguish between patients who are good candidates for arthroscopy and thosewho are not. and the trend istoward arthroscopy in patients in whom little likelihood existsof finding any treatable disorder.

(Casscells1984).

Threeyearslater,anotherauthor statedthat of those 9,000 North American surgeonsand the other surgeons of the world performing arthroscopy,many are ill-prepared and are therefore,not treating their patients fairly, Overuseand abuse by a few is hurting the many surgeonswho are contributing to orthopedic surgery by lowering patient's morbidity, decreasing the cost of health care, shortening the necessarytime of patients returning to gainful employment,and adding to the development of a skill that has madea profound change in the surgical care of the musculoskeletalsystem.

(McGinty 1987).

Arthroscopy remains the most sensitiveand specificdiagnostic modality for intrasynovial evaluation in the horse. This is somewhat in contrast to human orthopedics, where arthroscopy predominately is used for surgical interference and much of its diagnostic function has or is being replaced by magnetic resonance imaging (MRI). Arthroscopy has continued to be of great benefit in the horse, with increased recognition of soft tissue lesions in joints, tendons, sheaths, and bursa. However, as stated above, while there are many benefits gained from arthroscopy, it is technically demanding and the need for training remains.

l'\eTerence~ l\.oams MN. rurner lA. hndoscopy of the intertubercular bursa in horses.JAmVetMedAssoc 1999; 214; 221-225.

Bassage LH II. Richardson DW. Longitudinal fractures of the condyles of the third metacarpal and metatarsal bones in racehorses; 224 cases(1986-1995). J Am Vet Med Assoc 1998; 212: 1757-1764.

Bertone AL. Mcllwraith CW: Arthroscopic surgical approaches and intra-articular anatomy of the equine shoulder joint. Vet Surg 1987; 16: 312-317.

Bertone AL. McIlwraith CWoPowers BE. Trotter GW. Stashak TS. Arthroscopic surgery for the treatment of osteochondrosis in the equine shoulder joint. Vet Surg 1987; 16: 303-311.

Boening KJ. Die arthroscopie des kniegelenkes bein pferd uber einen zentralen zugang ou teill: Methodik Pferdehilkund 1995; 11: 247.

Boening KJ. Arthroscopic surgery of the distal and proximal interphalangeal joints. Clin Equine Pract 2002; 1: 218-225.

Boening KJ. Saldern FC. Leendertse I. Rahlenbeck F. Diagnostic and surgical arthroscopy of equine coffin joints. Proc Am Assoc Equine Pract 1990; 36: 331-317.

Brommer H. Rijkenhuizen AM. van den Belt HAM. et al. Arthroscopic removal of an osteochondral fragment at the palmaroproximal aspect of the distal interphalangeal joint. Equine VetEduc 2001; 13: 294-297.

Burman MS. Arthroscopy or the direct visualization of joints. An experimental cadaverstudy. JBone Joint Surg. 1930; 13: 669-695.

Burman MS. Finkelstein H. Meyer L. Arthroscopy of the knee joints.

J Bone Joint Surg 1934; 16: 255-268.

Casscells SW: Arthroscopy of the knee joint: a review of 150 cases.

J Bone Joint Surg (Am.) 1971; 53: 287.1971.

Casscells SW. The place of arthroscopy in the diagnosis and treatment of internal derangement of the knee: an analysis of 1.000 cases. Clin Orthop 1980; 151: 135-142.

Casscells SW. Arthroscopy: diagnostic and surgical practice.

Philadelphia: Lea and Febiger; 1984.

Casscells SW: The early days of arthroscopy in the United States.

Arthroscopy 1987; 3: 71-73.

Cauvin ERJ. Munroe GA. Boyd JS. Endoscopic exannnation of the carpal flexor tendon sheath in horses. Equine Vet J 1997; 29:

459-466.

Cauvin ER. Tappres'IJ. Monroe GA. et al. Endoscopic examination of the tarsal sheath of the lateral digital flexor tendon in horses.

Equine VetJ 1999; 31: 219-227.

Colon JL. Bramlage LR. Hance SR. Embertson RM. Qualitative and quantative documentation of the racing performance of 461 thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986-1995).

Equine Vet J 2000; 32: 475-481.

Dandy DJ. Arthroscopic surgery of the knee. Edinburgh: Churchill Livingstone; 1981.

Dandy DJ. Jackson RW. The impact of arthroscopy on the management of disorders of the knee. J Bone Joint Surg (Br) 1975; 57: 346-348.

Foerner JJ.Barclay WP. Phillips TN. et al. Osteochondral fragments of the palmar/plantar aspect of the fetlock joint. Proc Am Assoc Equine Pract 1987; 33: 739-744.

Foland JW. McIlwraith CWoTrotter GW. Arthroscopic surgery for osteochondritis dissecans of the femoropatellar joint of the horse.

Equine Vet J 1992; 24: 419-423.

Fortier LA. Foerner ll. Nixon AJ. Arthroscopic removal of axial osteochondral fragments of the plantar/palmar proximal aspect of the proximal phalanx in horses: 119 cases(1988-1992). J Am Vet Med Assoc 1995; 206: 71-74.

t!oruer Lf\. NIXon Aj. Uucharme NG. et al. Tenoscopic examinatioI and proximal annular ligament desmotomy for treatment 0 equine 'complex' digital sheath tenosynovitis. Vet Surg 1999; 28

429-435.

Frisbie DD. Trotter GW, Powers BE, et al. Arthroscopic subchondra bone plate rnicrofracture technique augments healing of larg( chondral defects in the radial carpal bone and medial femora condyle of horses. Vet Surg 1999; 28: 242-255.

Hall ME. Keeran RJ. Use of the arthroscope in the horse. Vet Me( Small Anim Clin 1975; 70: 705-706.

Hance R. Schneider RK. Embertson RM, et al. Lesions of the cauda aspect of the femoral condyles in foals: 20 cases (1980-1990) JAmVetMedAssoc 1993; 202: 637-646.

Honnas CM. Zamos DT. Ford TS. Arthroscopy of the coxofemora joint of foals. Vet Surg 1993; 22: 115-121.

Howard RD. Mcllwraith CWoTrotter. GW: Arthroscopic surgery fol subchondral cystic lesions of the medial femoral condyle iI1 horses: 41 cases (1988-1991) J Am Vet Med Assoc 1995; 206

846-850.

Ingle-Fehr IE. Baxter GM. Endoscopy of the calcaneal bursa in horse.

VetSurg 1998; 27: 561-567.

Jackson RW:The role of arthroscopy in the management of the arthritic knee. cun Orthop 1974; 101: 28-35.

Jackson RW:Current concepts review. Arthroscopic surgery. J Bone Joint Surg (Am) 1983; 65: 414-420.

Jackson RW: The scope of arthroscopy. Clin Orthop 1986; 208:

69-71.

Jackson RW. Memories of the early days of arthroscopy: 1965-1975. The formative years. Arthroscopy 1987; 3: 1-3.

--

Johnson LL. Lompl"nenslve arLnroscoplCexamination of the knee.

StLouis: Mosby; 1977.

Johnson 11. Arthroscopic surgery: principles and practice. St. Louis: Mosby; 1986.

Kawcak CE, Mcllwraith CW: Proximodorsal first phalanx osteochondral chip fragments in 320 horses. Equine Vet J 1994; 26:

392-396.

Kawcak CE, Mcllwraith CW, Norrdin RW, et al Clinical effects of exerciseon subchondral bone of carpal and metacarpophalangeal joints in horses. AmJ Vet Res2000; 61: 1252-1258.

Kawcak CE, McIlwraith CW, Norrdin RW, et al. The role of subchondral bone in joint disease:a review. Equine Vet J 2001; 33: 120-126.

Keene CCR, Paterson RS, Teague DC. Advances in arthroscopic surgery. Clin Orthop 1987; 224: 64-70.

Knezevic RF,Wruhs O. Arthroscopy in the horse, ox, pig, and dog.

VetMed. Rev 1977; 1: 54-63.

Kretz MR. Clinical evaluation of 49 tenoscopically assisted superior check ligament desmotomiesin2 7 horses. Proc Am Assoc Equine Pract 2001; 47: 484-487.

Lewis RB. Treatment of subchondral bone cysts of the medial condyle of the femur using arthroscopic surgery. Proc Am Assoc Equine Pract 1987; 33: 887-893.

Marble GP, Sullins KE. Arthroscopic removal of patellar fracture fragments in horses: 5 cases(1989-1998). J Am Vet Med Assoc 2000; 216: 1799-1801.

Martin GS, Mcllwraith CW: Arthroscopic anatomy of the equine femoropatellar joint and approaches for treatment of osteochondritisdissecans. VetSurg 1985; 14: 99-104.

Martin GS,Mcllwraith CWoArthroscopic anatomy of the intercarpal and radiocarpal joints of the horse. Equine Vet J 1985; 17: 373-376.

McGinty JB. Arthroscopy: a technique or a subspecialty?Arthroscopy 1987; 3: 292-296.

McIlwraith CWoThe use of arthroscopy. synovial fluid analysis and synovial membrane biopsy in the diagnosis of equine joint disease. In: Equine Medicine and Surgery. 3rd edn. American Veterinary Publications. Santa Barbara, 1982.

McIlwraith CWoArthroscopic surgery-atWetic and developmental lesions. Proc Am Assoc Equine Pract 1983: 29: 103-110.

McIlwraith CWoArthroscopy in Retrospect. Proc Am Assoc Equine Pract 1984a: 30: 57-66.

Mcllwraith CW Diagnostic and Surgical Arthroscopy in the Horse.

Lenexa: Veterinary Medicine Publishing Company. 1984b.

McIlwraith CWoExperiences in diagnostic and surgical arthroscopy in the horse. Equine VetJ 1984c: 16: 11-19.

McIlwraith CWoDiagnostic and surgical arthroscopy in the horse (2nd edn) Philadelphia: FA. Lea & Fibiger; 1990a.

McIlwraith CWoOsteochondral fragmentation of the distal aspect of the patella in horses. Equine Vet J 1990b; 22: 157-163.

McIlwraith CW:Tearing of the medial palmar intercarpal ligament in the equine mid-carpaljoint. Equine VetJ 1992; 24: 367-371.

McIlwraith CW (ed). Arthroscopy -An Update. Clinical Techniques in Equine Practice. Vol. 1. No.4. W.B. Saunders December: 2002a; 199-281.

McIlwraith CWoOsteochondromas and physeal remnant spikes in the carpal canal. Proc. 12th Ann Vet Symp 2002b: 168-169.

McIlwraith CWoBramlage LR. Surgical treatment of joint injury. In: McIlwraith. CWoTrotter GW (eds). Joint disease in the horse.

Philadelphia: WB Saunders. 1996: 292-317.

Mcllwraith CWoFesslerJ. Arthroscopy in the diagnosis of equine joint disease.J Am V~t Med Assoc 1978; 172: 263-268.

McIlwraith CWoFoerner }P. Davis DM. Osteochondritis dissecans of the tarsocrural joint: results of treatment with arthroscopic surgery. EqVetJ.1991; 23: 155-162.

McIlwraith CWoMartin GS. Arthroscopy and arthroscopic surgery in the horse. Comp Cont Educ 1984: 6: S46-S53.

McIlwraith CWoMartin GS. Arthroscopic surgery for the treatment of osteochondritis dissecans in the equine femoropatellar joint.

VetSurg 1985; 14: 105-116.

McIlwraith CWoNixon AJ. Joint resurfacing: attempts at repairing articular cartilage defects. In: joint disease in the horse.

McIlwraith cw: Trotter GW (eds). Philadelphia: WB Saunders; 1996: 317-334.

McIlwraith CWo Vorhees SM. Management of osteochondritis dissecans of the dorsal aspect of the distal metacarpus and metatarsus. Proceedings 36th Annual Meeting Am Assoc Equine Pract 1990; 36: 547-550.

McIlwraith cw: Yovich Jv; Martin GS. Arthroscopic surgery for the treatment of osteochondral chip fractures in the equine carpus.

J Am Vet Med Assoc 1987; 191: 531-540.

Mueller FOE. Allen D. Watson E. et al. Arthroscopic removal of a fragment from an intercondylar eminence fracture of the tibia in 2-year-old horse. J Am Vet Med Assoc 1994; 204: 1793-1795.

Nickels FA. Sande. B. Radiographic and arthroscopic findings in the equine stifle. J Am Vet Med Assoc 1982; 181: 918-922.

Nixon AJ. Diagnostic and surgical arthroscopy of the equine shoulder joint. Vet Surg 1987; 16: 44-52.

Nixon AJ. Arthroscopic approaches and intra-articular anatomy of the equine elbow. Vet Surg 1990a; 19: 93-101.

Nixon AJ. Endoscopy of the digital flexor tendon sheath in horses.

VetSurg 1990b; 19: 266-271.

Nixon AJ. Diagnostic and operative arthroscopy of the coxofemoral joint in horses. Vet Surg 1994; 23: 377-385.

Nixon AJ. Arthroscopic surgery of the carpal and digital tendon sheaths. Clin Tech in Equine Pract 2002a; 1(4): 245-256.

Nixon AJ. Arthroscopic techniques for cartilage repair. Clin Tech Equine Pract 2002b; 1(4): 257-269.

Nixon AJ. Sams AE. Duchame NG. Endoscopically assisted annular ligment release in horses. Vet Surg 1993; 22: 501-507.

Caudal radial exostosisas a cause

'1977, Equine Vet Sci 1981; 5:

177-182.

Peroni]F, Stick JA. Evaluation of a cranial arthroscopic approach to the stifle joint for the treatment of femorotibial joint disease in horses: 23 cases (1998-1999). J Am VetMed Assoc 2002: 220:

1046-1052.

Pettrone FA. Meniscectomy: arthrotomy versus arthroscopy. Am J Sports Med 1982: 10: 355-359.

Phillips TJ, Wright 1M. Observations on the anatomy and pathology of the palmar intercarpal ligaments in the middle carpal joints of Thoroughbred racehorses. Equine Vet J 1994; 26: 486-491.

Richardson DW. Technique for arthroscopic repair of third carpal bone slab fractures in horses. J Am Vet Med Assoc 1986; 188:

288-291.

Richardson DW. Arthroscopically assisted repair of articular fractures. Clin Equine Pract 2002; 1: 211-217.

Schneider RK, Ragle CA, Carter BG, et al. Arthroscopic removal of osteochondral fragments from the proximal interphalagealjoint of the pelvic limbs in three horses. J Am Vet Med Assoc 1994; 207: 79-82.

Schneider RK, Jenson p, Moore RM. Evaluation of cartilage lesions on the medial femoral condyle as a cause of lameness in horses: 11 cases (1988-1994).

J Am Vet Med Assoc 1997; 210:

1649-1652.

Selway Sf. Arthroscopic surgery: the carpal and fetlock joint. Proc Am Assoc Equine Pract 1983; 29: 95-109.

Shrock KB, Jackson DW. Arthroscopic management of the anterior cruciate ligament -deficient knee. In: McGinty JB (ed), Operative Arthroscopy, 2nd ed Philadelphia: Lippincott Raven; 1996:

511-530.

Smith M. Arthroscopy in large animals. Proceedings of the 11th Conference of the European Society of Veterinary Surgery, 1975.

Southwood 11, Mcllwraith CWoArthroscopic removal of fracture fragments involving a portion of the base of the sesamoidbone in horses. J Am Vet Med Assoc 2000; 217:2 36-240.

Southwood 11, Stashak TS, Fehr IE, et al. Lateral approach for arthroscopic removal of solitary osteochondromas from the distal radial metaphysis in three horses. J Am Vet Med Assoc 1997; 210: 1166-1168.

Southwood 11, Trotter GW, Mcllwraith CWoArthroscopic removal of abaxial fracture fragments of the proximal sesamoid bone in horses: 47 cases (1989-1997).J Am Vet Med Assoc 1998a; 213:

1016-1021.

Southwood 11, Stashak TS, Kainer RA. Tenoscopicanatomy of equine carpal flexor synovial sheath. Vet Surg 1998b; 27: 15D-157.

Southwood 11, Stashak TS, Kainer RA, et al. Desmotomy of the accessory ligament of the superficial digital flexor tendon in the horse with the use of a tenoscopic approach to the carpal sheath.

VetSurg 1999; 28: 99-105.

Squire KR, Adams SB, Widmer WR, et al. Arthroscopic removal of a palmar radial osteochondroma causing carpal canal syndrome in a horse. J Am Vet Med Assoc 1992; 201: 1216-1218.

Stick JA, Borg LA, Nickels FA, et al. Arthroscopic removal of osteochondral fragment from the caudal pouch of the lateral femorotibial joint in a colt. J Am Vet Assoc 1992; 200: 1695-1697.

Takagi, K. Practical experience using Takagi's arthroscope. Nippon SeikeigekaCakkai Zasshi, 1933; 8: 132.

Textor JA, Nixon AJ, Lumsden J, et al. Subchondral cystic lesions of the proximal extremity of the tibia in horses: 12 cases (1983-2000). J Am Vet Med Assoc 2001; 218: 408-413.

l'extor JA. Nixon AJ. Fortier LA. Tenoscopic release of the equine carpal canal. Vet Surg 2003; 32: 278-284.

Trumble TN. Stick AJ. Arnoczky SF. et al. Consideration of anatomic and radiographic features of the caudal pouches of the femorotibial joints of horses for the purpose of arthroscopy. Am J VetRes 1994; 55: 1682-1689.

VacekJR. Welch RD. Honnas CM. Arthroscopic approach and intraarticular anatomy of the palmaroproximal and plantaroproximal aspect of distal interphalangeal joints. Vet Surg 1992; 4:

257-260.

Vail TB. Mcllwraith CWoArthroscopic removal of an osteochondral fragment from the middle phalanx of a horse. Vet Surg 1992; 4:

269-272.

ValdezH. Richmond J. Wain L. Fackelman G. Operative arthroscopy in the horse. Equine Pract 1983; 5: 39-42.

Walmsley JP.Vertical tears in the cranial horn of the meniscus and its cranial ligament in the equine femorotibial joint: 7 casesand their treatment by arthroscopic surgery. Equine Vet J 1995; 27: 20-25.

Walmsley Jp. Fracture of the intercondylar eminence of the tibia treated by arthroscopic internal fixation. Equine Vet J 1997; 29:

148-150.

Walmsley JP. Arthroscopic surgery of the femorotibial joint. Clin Tech Equine Pract 2002; 1: 226-233.

cases.EquineVetJ2003; 35: 402-406.

WatanabeM. TakedaS. The 21 Tokyo:IgakuShoin.1978.

Weller RR, Maieler 1}. Bowen Whitton RC. McCarthy RoseRJ.The intercarpal ligaments of equine mid-carpal joint. Part 1: the anatomy of the palmar and

dorsomedial intercarpal ligaments of the mid-carpal joint. Vet Surg 1997a; 26: 359-366.

Whitton RC. Rose RJ.The intercarpal ligaments of the equine midcarpal joint. Part II: the role of the palmar intercarpal ligaments in the restraint of dorsal displacement of the proximal row of carpal bones. Vet Surg 1997b; 26: 367-373.

Whitton RC. Kannegieter NJ. Rose RJ.The intercarpal ligaments of the equine mid-carpal joint. Part III: clinical observations in 32 racing horses with mid-carpal joint disease.Vet Surg 1997c; 26: 374-381.

Wilderjans H. BoussawB, Madder K. Simon O. Tenosynovitis of the --~

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of instrumentation is available for human arthroscopic surgery, but much of it is unsuitable and unnecessary for equine arthroscopy. Many of the operating instruments are expensive and fragile; for equine use a limited amount of equipment is generally essential or appropriate. The descriptions and recommendations in this text are based on the authors' experiences and personal choices and numerous substitutions can be made. Obviously, the potential for variation is extreme, and it is necessary to continue to evaluate new instrumentation as it becomes available or as new arthroscopic procedures are developed.

This chapter represents the authors' current views on instrumentation.

The availablearthroscopesvary in outer diameter,working length, and in lens angle, which may be straight (0°) or angledfrom 5° to 110°. Many manufacturersmarket 4 mm diameterarthroscopeswith 0°, 30°, or 70° lens anglesand working lengths of 160-175 mm. The field of view is often 115° or more,leadingto their classificationas "wide field of view" arthroscopes. Most manufacturers produce small arthroscopes,usually 2.7 mm diameter arthroscopeswith 30° or 70° lensangles;a short 2.7 mm diameterarthroscope

with 300 or 700 lens angles; and a 1.9 mm diameter arthroscope with 300 lens angle. Generally. surgeons should choose the largest diameter arthroscope that can safely be inserted and maneuvered without causing damage. Small diameter arthroscopes with appropriate operating instrumentation have been developed for use in human carpal. metatarsophalangeal. and temporomandibular joints (Poehling 1988).

However.these are fragile. allow lessillumination. and provide a much smaller field of view (900 for 2.7-mm scope and 750 for 1.9-mm scope). Small diameter arthroscopes usually also have a shorter working length (50-60 mm) because the excessiveflexibility of a longer instrument increases the risk of breakage (Poehling 1988). More recently. a complete range of sizes has also become available in video arthroscopes. which are coupled directly to the video camera. This obviates the need for a coupler and eliminates the potential for fogging between the arthroscope eyepiece and camera Gackson & Ovadia 1985). Flexible arthroscopes have also had a period of limited use. but generally failed to provide true flexibility and optical clarity (Takahashi & Yamamoto 1997). Combined approaches.using a rigid arthroscope for most of the procedure and a flexible arthroscope to accessdifficult areas of the hip. ankle. or knee in people. have added to the more thorough evaluation of these joints (Takahashi & Yamamoto 1997).

A 4 mm diameter arthroscope with a 25 or 300 lens angle fulfills most needs of the equine surgeon (Fig. 2.1). A 4 mm 700 arthroscope can occasionally provide improved visualization of specific areas of some joints such as the tarsocrural. shoulder. and palmar/plantar aspect of the metacarpo/

Nephew -Dyonics8 (Fig. 2.3), the 300 Hopkins rod lens telescope made by Karl Storzb,and the 300 direct view and video arthroscopes made by Strykerc. Comparable-sized arthroscopes are also available from Linvatecd,Richard WoW, Zimmerl, Olympus8, Arthrexh, and other companies. The advantages of the 25-300 angled lens are: (1) it provides an increased field of vision; (2) rotating the arthroscope increases the visual field without moving the arthroscope; and (3) the end of the arthroscope can be placed at some distance from the lesions, allowing easier accessto the area with instruments and minimizing the risk of damaging the

arthroscope.

All arthroscopes are used within a protective stainless steel sleeve or cannula (Fig. 2.4). For a 4-mm arthroscope the sleevehas a 5 mm or 6 mm diameter, and is connected to the arthroscope through a self-locking system that varies between manufacturers. The sleevehas one or two stopcocksfor ingress and/or egress fluid systems. The second stopcock is useful if the surgeon uses gas and fluid distention interchangeably during arthroscopy; otherwise, a sleeve with one stopcock offers greater freedom of movement. A rotating stopcock is critical to allow the ingress fluid line to be positioned away from the limb and/or instruments as required. The space between the sleeve and arthroscope allows flow of ingress

tarsophalangeal joints. Figure 2.2 illustrates the different fields of view of a 250 arthroscope and a 700 arthroscope in the same position in a tarsocrural joint. Popular choices in an arthroscope for routine equine arthroscopy include the 300 videoarthroscope and direct view arthroscopes from Smith &

..Smlth&Nephew-Dyonlcs.150MlnutemanRoad.

Andover.MA01810.

Tel: (978) 749-1000. www.smith-nephew.com .~arIStonVeterlnaryEndoscopy.175 CremonaDrive.Goleta.CA 93117.

Tel: (800) 955-7832. www.ksvea.com .'Stryker. 5900 OpticalCourt. SanJose.CA95138. Tel: (800) 624-4422. www.strykerendo.com .dLlnvatec-Conmed Co. 11311 Concept Blvd.. Largo. FL 33773.

Tel: (800) 237-0169. www.linvatec.com .'RIchard Wolf. 353 CorporateWoodsParkway. Vernon Hills. IL 60061.

Tel: (847) 913-1113. www.richardwolfusa.com .rZlmmer. PO Box 708. 1800 West Center St.. Warsaw. IN 46581.

Tel: (800) 613-6131. www.zimmer.com .SOlympus America Inc.. 2 Corporate CenterDrive. Melville. NY 11747.

Tel: (800) 848-9024. www.olympusamerica.com .hArthrex.

2885 South Horseshoe Drive. Naples. FL 34104.

Tel: (800) 933-7001. www.arthrex.com

~

sleeveshave a wider diameter (5.8-6.0 mm Theseso-calledhigh-flow sheathsare very for insertion of the sleeve in In joints with a thick fibrous capsule

usedto penetratethe sharp trocars for insertion and blunt in the sleeveare now largely redundant. the arthroscopeis provided by a fiberoptic from a light source. The cable should be a

use of extremelylight-sensitivevideo

by Richard Wolf Medical Instru-

with these light sources using video printers; careful control of the white balance of the

A light source with a flash unit is largely -

capture. The sources may be high-intensity illumination, xenon arc lamps (100-500 W), or vapor lamps (McGinty 1984). The xenon light -the replacement cold light fountain with 175 or 300-W lamp -,--,-

2.7),

Dyonics 300XL xenon 300 W source, a Baxter-Edwards!

Reliant 300 W xenon source, and a Stryker X-6000 500 W xenon source (Fig.2.7). The bulbs last from 350 to 500 hours, which represents a recurring cost for busy practices.

Light sources that automatically adjust the light intensity are useful to minimize the need for manual adjustment of .'Baxter-Edwards, Baxter Healthcare Corp,OneBaxter Parkway,Deemeld.

IL 60015. Tel: (847) 948-2000. www.baxter.com

light intensity. Most have a feedback electrical signal from the camera control to light source for intensity adjustment. The Dyonics AutoBrite IITM Illuminator, the Stryker X-6000TM light source, the Baxter-Edwards ReliantTM xenon light source, and the Karl Storz light source all employ useful intensity feedbackcontrol. Most have the option to use this in an automatic mode or to switch to manual to override the iris control. Additionally, many video camera control systems now also compensate for variation in light intensity, which reduces the need for light source intensity changes.

Video cameras Diagnostic and surgical arthroscopy can be performed by direct visualization through the arthroscope; however, this is now rarely practical and is no longer recommended. The risks of contaminating the surgical field and instruments are obvious. In addition, depth perception and ability to perform fine movementsare severelycompromised with the monocular vision of a small image. Projection of images through a video screen corrects these deficiencies and allows simultaneous observation of the procedure by several participants Gackson & Ovadia 1985). Additionally, video documentation through still image capture, video recorders, and digital video capture systems (described later) provide sound surgical training, client satisfaction, and legal sense.Lightweight video cameras are attached directly to the eyepiece of the arthroscope (Fig. 2.8), eliminating the need for the eyeto go to the arthroscope. This also provides a more comfortable operating position since the surgeon can stand up straight, and the hands can be placed at any level. It is also possible for an assistant to hold the camera, which allows the surgeon use of both hands to manipulate instruments for fine control or accessto difficult sites.

Solid-state video cameras are now conveniently small and light and can be attached directly to videoarthroscopes, eliminating the coupler and any chance of fogging (Fig. 2.9).

The united arthroscope and camera can be cold soaked, and/or gas sterilized. The solid-state cameras currently available produce an image from either one or three chips, or more accurately, closed coupled device (CCD)chips (Whelan &Jackson 1992, Johnson2002). Thesechips produce excellent image quality. Most modern cameras use digital enhancement of the image, including motion correction algorithms, but still output as an analog signal Gohnson 2002). Fully digital cameras such as the Stryker 988TMvideo camera can write directly to a CD without capture devices,and provide a dense 950 lines per inch image that requires an upgraded monitor to derive the most benefit from its circuitry. Durable and high image-quality video cameras used by the authors are available from Karl Storz (Telecom SL camera), Smith & Nephew -Dyonics (ED-3 and D3 three-chip cameras; HD900 single-chip camera), Stryker Endoscopy (888 and 988 threechip cameras), and Arthrex. Severalmanufacturers produce autoclavable cameras: for example, the Smith & Nephew Dyonics 337 three-chip camera, which can be sterilized using

the flash autoclave cycle. in addition to more routine methods.

These cameras are well sealed. making them durable. but have previously been available only as single-chip devices. reducing the image quality. The authors' preferred method of sterilization is with ethylene oxide gas (see Sterilization of Equipment). This requires a minimal exposure/ventilation time of 12 hours and. therefore. is usually suitable only for the first surgery each day: Cameras for subsequent surgeries

sleeve.In countries where ethylene oxide is not moisture betweenthe arthroscopeand camera largely eliminated with cameraswhich have large, vents is employed.the problemcan be and also by using warm irrigating fluid. Anti-

irrigation

system

polyionic fluid is used for joint distention and ~ during surgical arthroscopic procedures. The an intravenous set connected to

to apply pressure(Fig. 2.10). This method is satisis economical and provides distention superior to feed developedby suspendingthe fluids abovethe

used in human small joint surgery are also frequently inadequate (Oretorp & Elmersson 1986). The hand pump allows the surgeon to broadly control the degree of distention as well as the irrigation flow rate. A relationship between fluid pressure and fluid extravasation into the soft tissues has been recognized in man (Morgan 1987); extravasation occurs at approximately 50 mmHg (Noyes et al 1987).

Control of fluid pressure is therefore desirable.

The most popular system for fluid delivery is now a motorized pump. Such pumps can provide both high flow rates and high intra-articular pressures.rThe simplest and favored pump for two of the authors (C.WM. and I.M.W) is an infusion pumpk, such as the one illustrated in Fig. 2.11.

Such pumps are relatively inexpensive (Table 2.1) and provide high flow rates on demand, which is particularly useful for distention of large synovial spaces (see also Chapter 3), but automatic control of the pressure is lacking (Bergstrom & Gillquist 1986, Dolk & Augustini 1989). If an outflow portal is not open, excessive intra-articular pressures may cause joint capsule rupture (Morgan 1987). Extravasation of fluid is also a complication whenever excessive pressures are generated, and compartment syndrome has occurred using mechanical pressure delivery systemsin man.

The ideal pressure and flow automated pump should be capable of delivering necessary flow rates on demand, keep pressure at adequate yet safe levels, and include safety features such as intra-articular pressure-sensitiveshutdowns and alarms (Ogilvie-Harris & Weisleder 1995). Many new pumps meet these criteria, including pumps made by Arthrex, Stryker Endoscopy,Smith & Nephew -Dyonics, Karl Storz,

Inc., Baxter Health Care Corp, One Baxter

gravity flow through

sleeves

and Linvatec (see Table 2.1; Figs 2.12-2.14). Most provide pressures from 0 to 150 mmHg and fluid flows as high as 2 L/min. All but the 3M! and Linvatec pumps sense joint pressures through the single delivery fluid line. These features facilitate visualization when large joints or motorized equipment result in a demand for high fluid flows. From a reliability perspective,the roller pump design of the Arthrex, Stryker, and Karl Storz pumps provide advantages over th( centrifugal and piston pump design of other manufacturers The significant cost of these sophisticated fluid deliver) systems can be reduced by tubing lines that do not requirt complete replacement of the entire pump assembly durin{ multiple case schedules. An example is the Arthrex pumI assembly(seeFig. 2.12) which replaces only the sterile line t< the patient between cases,providing new fluid delivery foJ less than one-third the cost of a complete roller pump an< patient line set-up. Pressure and flow automated pumps arl more expensive (seeTable 2.1) and involve a more comple; set-up procedure during preparation for surgery. Howevel equipment prices are often reduced or rolled into a minimun purchase of tubing, so the actual equipment cost can b passedon to each case. Set-up and calibration are simpler 0] some pumps than others (see Table 2.1). A nitrogen drivel flutter valve pump with no electrical parts (Davolm)is a cos1 effective intermediate-style pump that bridges betweel gravity feed and pressure-driven pumps (Fig. 2.15). Thi system has been used by one author (A.J.N.) for many year and is economical, simple to set up, pressure sensing, and ca deliver high flow rates (Smith & Trauner 1999). The di: advantages are the relatively slow recognition of pressUl drops in the joint and the noise of the flutter valve pum assembly.

The use of a balanced electrolyte solution, such as lactat( Ringer's or Hartmann's solutions, rather than saline for joil distention has beenrecommended based on studies that sho .'3M Orthopedics Pro :ts Division, 3M Cent.

1000. Tel: (888) 364.

us

No

MN

77. www.mmm.com rIossettCrossroad,PO.275. www.davol.com

31 120

N/A

No

Fair

N/A

1.0

No

69

Good

saline is not physiologic and inhibits normal synthesis of proteoglycans by the chondrocytes of the articular cartilage (Reagan et al1983). Any matrix depletion of the cartilage during normal arthroscopic procedures would be minor and certainly not permanent Gohnson et aI1983), but when the cost of each fluid is similar, the use of the most physiologic solution is logical. The results of another study evaluating the acute effects of saline and lactated Ringer's solution on cellular metabolism demonstrated an acute stress to both chondrocytes and synoviocytes immediately after irrigation with both fluids, although this was greater with saline. These stress patterns (monitored by evaluating relative ATP regeneration) are apparent after 24 hours, appear to be returning toward normal by 48 hours, and are not significantly different from control values 1 week later. Based on these results, protection from full activity during this time period was considered advisable (Straehley 1985).

Gas insufflation has been used routinely in equine arthroscopy by two of the authors G.B. and A.J.N.). Several types of gas insufflators are available. Most have a small internal

reservoir gas tank, including the Karl Storz and Richard WoU units (Fig. 2.16). Others, such as those from Unvatec, Stryker, and Directed Energy, use a direct step-down valve system from a commercial tank (Fig. 2.17). Arguments have been advanced for the use of gas insufflation of the joint rather than fluid distention during arthroscopy (Eriksson & Sebik 1982); the gaseousmedium (carbon dioxide, helium, or nitrous oxide) results in a sharper image with higher contrast. As well as being useful for photographs, some evidence exists that it may offer an increased degree of accuracy in assessing cartilage damage in some situations (Eriksson& Sebik 1982).

In addition, it can prevent synovial villi from interfering with the visual field. However, a pressure-regulating device and a special system are necessary for gas insufflation. In addition, gas escapes easily after removal of any appreciable mass

portal. Gas emphysema,pneumohave been identified as arthroscopy Gager 1980), and

better visualization when synovial bone graft and fibrin-based

but many procedures start with liquid distention and only use gas for short periodsof defined activity, which limits emphysema.

Removal of small particles by suction obviously requires a fluid medium, and fluid irrigation will also be necessaryat the end of any procedure for lavageand removal of debris.

At this stage,the authors considerthe use of fluid irrigation more convenient and experience with the use of fluid can eliminate many of the problems associated with synovial villi obstructing visualization. No additional equipment is necessary; and although the imagesobtained have somewhat lesscontrast compared with images from gas-filledjoints, superficial dalhage to the articular cartilage and other lesions are seen more readily in the form of floating strands. Nonetheless,the addition of gas may be a necessaryand convenient step in the future if bone grafting, laser surgery,or fibrin-based cell grafting become an important feature of arthroscopic surgery.

Egress cannula An egresscannula (Fig. 2.18) is a necessaryitem for most arthroscopicprocedures.It has an accompanyinglocking

~

trocar with either a sharp stylet or conical obturator. The cannula is used to flush fluid through the joint in order to clear blood and debris and optimize visibility. The outer end has a luer attachment through which fluid can be aspirated or to which a long, flexible egress tube can be attached to transmit fluid to a bucket on the floor rather than having it spillover the surgical site or equipment. The authors use a 2or 3-mmegress cannula (Fig. 2.18a) routinely at the beginning of the arthroscopic procedure to flush the joint and to probe and manipulate lesions. A larger diameter (4. 5-mm) cannula (Fig. 2 .18c) can be used at the end of the procedure for clearing debris. The 3-mm cannula usually is inserted without the use of the stylet, because a portal has been made with a blade. A conical obturator (Fig. 2.18d), however, is useful to facilitate placement of the larger 4.5-mm cannula at the end of the procedure.

Hand instruments for arthroscopic surgery As mentioned previously, a myriad of instruments are available from arthroscopic equipment manufacturers (Caspari 1987, Gross 1993, Ekman & Poehling 1994), most of which are neither suitable nor necessary for equine arthroscopic surgery. The instruments presented in this section are those used by the authors to perform the procedures described in this book. It is accepted that there are alternative, and possibly better, ways to perform any given task and techniques certainly will change. The current list is written with the philosophy of keeping arthroscopy simple and practical without compromising standards. A combination of specialized arthroscopic instruments and instruments not designed specifically for arthroscopic surgery is used.

Blunt

Probe

This standard arthroscopic instrument (Fig. 2.19) is necessary for diagnostic as well as surgical arthroscopy. Suitable probes Fig. 2.19 (A) Variety of arthroscopic probes, from large to small format, and with round. rectangular and thumb plate handles.

(B) Probe ends vary in shape and size.

areavailablefrom all arthroscopicinstrumentmanufacturers.

Probesfrom differentmanufacturersvary in length and end configuration. The probe end can be round, square or rectangularand can vary from 3 to 6 mm in length. Longer tips on the probecan hamperentry to the joint bytangling in the capsule,while smallerprobesare easyto insert but are more proneto bending.A 3-mmrectangularend probewith taperedshaftis convenientand durable(seeFig. 2.19). The handle on probescan vary from a round smoothshaft. to a rectangular shaft, which is easier to grasp, and to the additionof a thumb bar for directedapplicationof pressure.

Forceps Currently. the authors use seven different forceps for retrieving fragments and trimming lesions (Figs 2.20-2.24).

1. Routine use. The workhorse in most arthroscopy packs is the Ferris-Smith intervertebral disc rongeur. For removal of large fracture fragments and osteochondritis dissecans flaps. a pair of Ferris-Smith cup rongeurs with a 7-inch shaft and a straight 4 x 10-rom bite (Scanlan Instruments) is used. These forceps are better than other types for this purpose. Variation exists with regard to the shape of the jaws on different 4 x 10-rom Ferris-Smith rongeurs. A narrow-nosed pair made by Sontec (Scanlan) is useful for carpal and proximal phalangeal fragments. They pass through the instrument portal easily and are appropriate for small and medium-sized fragments (Fig. 2.20). Another pair of Ferris-Smith rongeurs with a 6 x l2-rom cup is used for larger fragments (Fig. 2.20). A set with the jaw angled up and with a 4 x 10-rom cup are also useful in some tight situations. Some surgeons use a pituitary rongeur for longer fragments.

2. Small fragments. Also recommended is a pair of straight ethmoid rongeurs with a 5-rom bite (Richard Wolf or Scanlan Instruments). These instruments have a pointed nose and are useful for procedures involving chip fractures off the proximal aspectsof the first phalanx (seeChapter 5).

3. Long-handled forceps. A more verSatIle and longer alternative to the Ferris-Smith rongeur is the Mcilwraith arthroscopy rongeur (Fig. 2.21), made by Sontec Instruments? Pituitary rongeurs are also used by other arthroscopic surgeons for the same purpose.

4. Tight spaces. A small angled rongeur with slightlJl pointed tip (Fig. 2.22), often referred to as a patella rongeur (Sontec or Richard Wolf), is especially useful foI retrieving small fragments from difficult places, including .nSontec (formerly Scanlan) Instruments Inc., 7248 Tucson Wa~ Englewood, CO 80112. Tel: (800) 821-7496. www.Sonte.

Instruments.com

the palmar surfaceof the metacarpalcondyleor proximal phalanx, the palmar recessesof the midcarpaljoint, and the underside of the patella. The use of sharp-edged rongeur-typeinstruments is preferredin most situations whenpiecesto beremovedare still attachedby softtissue.

5. Loose bodies. Loosebodiescanberetrievedwith custom equine loosebody forceps,since most loosebodyforceps availablein catalogsof arthroscopicinstrumentsare not strong enough. For instance,Zimmerhas takenthe basic Ferris-Smithdesignand changedthe endsof the jaws for specificpurposes.

6. Cutting forceps. Basketforcepsare used occasionally (Fig. 2.23) for removal of cartilaginous flaps of osteochondritisdissecans in the femoropatellarjoint. A narrow, modifiedbasketforceps(seeCutting Instruments section) is useful for severing soft tissue structures such as villonodular pads.

7. Broken instrument retrieval. A fragmentforcepswith a malleable shaft is also occasionally useful, but not essential.Theseforcepsare illustrated in Figure 2.24 and are madeby ScanlanInstruments(Sontec).

Elevators and osteotomes The instruments primarily used for separating fragments from parent bone include a small round-end curved periosteal elevator or a straight narrow osteotome. Examples include the small (6-mm) round-end SynthesO elevator, the 5-mm Mcllwraith-Scanlan elevato~, and the 4-mm cottle osteotome (Scanlan) (Fig. 2.25). An extra small (3-mm) curved Synthes elevator is also occasionally useful (Fig. 2.25). A markedly curved sharp-end periosteal elevator (Fig. 2.26) is useful for removing apical sesamoid fragments (Foerner elevator; Scanlan Instruments; see Chapter 5).

Cutting instruments Numerous cutting instruments are available. Their use is limited to certain situations. If sharp severance of structures is required. special arthroscopic cutting instruments should be used. The authors have used both reusable blades and disposable blade systems (Fig. 2.27), made by Karl StOrzb, ."Synthes (USA),POBox 1766, 1690 RussellRoad,Paoli, PA 19301. Tel: (800) 523-0322. www.synthes-chur.ch .nSontec (formerly Scanlan) Instruments Inc., 7248 Tucson Way, Englewood.CO80112. Tel: (800) 821-7496. www.SontecInstruments.

com .~arl Stol"lVeterinaryEndoscopy.175 CremonaDrive. Goleta,CA93117.

Tel: (800) 955-7832. www.ksvea.com

.

Wolfe, BeaverP,Dyonics, Acufex-Smith & Nephe~, ConceptLinvatec-Zimmer, and Bard-Parker. Sheathed blades are also available and eliminate the risk of inadvertent damage to other structures when introducing the blade

(Fig.2.28). .nSontec (formerly Scanlan) Instruments Inc.. 7248 Tucson Way. Englewood.CO80112. Tel: (800) 821-7496. www.SontecInstruments.

com ."Richard Wolf. 353 Corporate WoodsParkway. Vernon Hills. IL 60061.

Tel: (847) 913-1113. www.richardwolfusa.com ."Beaver SurgicalProducts.Becton-Dickinson.BDMedicalSystems.1 Becton Drive. Franklin Lakes.NJ 07417. Tel: (800) 237-2762. www.bd.com .qAcufex Microsurgical Inc.. Smith & Nephew. 150 Minuteman Road.

Andover. MA 01810. Tel: (978) 749-1000. www.smith-nephew.com

Acquisition of the commonlymarketed hook scissorsis not recommendedfor equine arthroscopy.The bestscissortype cutting instrument available currently is the very narrow basketforceps (Scanlan-Mcllwraith scissoraction rongeur)(Fig.2.29).

The authorshavefound little indicationfor the retrograde or hook knives. other than those availablefor arthroscopic annular ligament transection(seeChapter13). A meniscotome can be useful for breaking down fibrous capsule attachmentswhen freeing a chip as it makesa cleanercut than a periostealelevator.

Curettes Curettes are used for debridement of most osteochondral defects, including those remaining following removal of traumatic or developmental fragmentation, evacuation of subchondral bone cysts, and debridement of foci of infection.

Closed spoon curettes are suitable for most purposes, but open ring curettes may be preferable for the center of lesions (Figure 2.30). Straight and angled spoon curettes, either 0 or 00 in size, are generally preferred for routine applications (Fig. 2.30). A rasp is rarely necessary for smoothing debrided bone regions in joints, but may be useful for smoothing larger areas such as after radial osteochondroma removal. These instruments are available in straight, offset convex and concave designs from various manufacturers, including Stainless Manufacturing Incr.

Self-sealing cannulas The use of self-sealing sleevesor cannulae is a logical answel to the loss of fluid through instrument portals. Either devict can be used by screw insertion into the tarsocrural, shoulder or femoropatellar joints, but they are not useful in the carpu! .'Stainless Manufacturing In CO91773.

and fetlock because of the close proximity of joint capsule and lesion. Disposable self-sealing 4.5-10-mm operating cannulae are available through several manufacturers (Arthrex, Dyonics, Richard Wolf, or Acufe~). They are useful for repeatedly introducing small forceps, hand tools, and shavers,but in the horse, removal of osteochondral fragments is the most common procedure, and this can only rarely be done through such cannulae. A 10-mm (I.D.) threaded selfsealing disposable cannula with insertion obturator (Cleartrac; Dyonics -Smith & Nephew) has been useful in shoulder arthroscopy (Fig. 2.31), otherwise operating cannulae are still rarely used in equine arthroscopic surgery.

Vacuumattachments Various instruments, including forceps and curettes, are available with attachments so that suction can be applied as they are used. The S.2-mm DyoVac (Fig. 2.32) suction punch rongeur (Smith & Nephew -Dyonics) is used by one of the authors (A.J.N.) for minor synovial resection, cartilage and soft bone removal, or larger soft tissue pad or meniscus trimming. As such, this versatile rongeur gets more use than most instruments in routine arthroscopy. Further, it often prevents having to set up motorized equipment. Use of suction enables instant removal of debris as it forms during debridement within the joint. However, with the high fluid pressures used in equine arthroscopy, suction is often unnecessary as free material is often spontaneously flushed out through the suction channel. The use of suction during any procedure requires an increased rate of ingress fluid delivery.

In general, the authors prefer to perform hand debridement without suction, reserving it for use with motorized instruments or to remove debris at the end of surgical procedures.

Motorized

instrumentation

A large assortment of motorized arthroscopic instruments are available from most of the equipment manufacturers. h & Nephew. 15049-1000. www.sm

While motorized equipment should be used only with due consideration to the synovial environment and tissues. these instruments are extremely efficient and some surgical procedures can only be done effectively with such equipment.

Synovial resection. whether performed locally to improve visualization of lesions or therapeutically on a subtotal basis. can only effectively be performed with motorized apparatus.

Similarly, some large areas of osseousdebridement. such as in shoulder or stifle osteochondrosis, become impossible to complete reasonably without such equipment. The basic concept of motorized instruments is a rotating blade within a sheath to which suction can be applied. This pulls soft tissue into the mouth of the blade and removes debris (Graf and Clancy 1987). Most currently available systemsare powered electrically and consist of a control unit attached by an electrical cord to a motorized handpiece. The latter may be operated by buttons on the handpiece or via a foot pedal to the control unit (Fig. 2.33).

Cutting heads or blades for the motorized units can be divided into three broad groups: (1) blades designed to remove soft tissues such as synovium, plicae, and ligament remnants; (2) blades to trim denser soft tissues such as menisci; and (3) burrs for debriding bone. These blades are mostly available in disposable forms, although renewed interest in reusable blades has resulted from the economic downturn in medical practice. However, even disposable blades can be cleaned, sterilized and reused for a limited number of procedures (not recommended by manufacturer).

In the authors' experience, this has been a safe practice.

Generally,"fatigue" damage to the blades occurs at the plastic attachment to the handpiece or in the drive shaft of curved synovial resectors.

The authors have experience with the Smith & Nephew Dyonics Arthroplasty SystemTM,the Richard Wolf Surgical Arthro Power System, The Baxter-Edwards system, the Stryker System, and the Karl Storz meniscotome. Dyonics developed the original shaver, and the third- and fourthgeneration Dyonics systems (PS3500 and EP-1 shavers), are still very popular. However,blade availability for these models is becoming increasingly limited, and many surgeons are upgrading to the Dyonics Power Mac system, or seeking a different manufacturer. Current shavers have integrated suction with hand control of suction intensity. Some manufacturers such Smith & Nephew -Dyonics and Stryker also have speed and rotation direction controls on the handpiece. Rotation speedsup to 8000 rpm and bidirectional capabilities are useful. The hand units of the Dyonics and Stryker shavers are relatively heavy compared to Storz, Wolf, and Baxter shavers, but the heavier units are generally more powerful. All modern shaver motors can be autoclaved and most can be flash-autoclaved or cold-sterilized as necessary.

Most shavermotors recognize the blade type that the user has inserted and controls the motor speedrange accordingly. Foot control of shaver speed and direction, including oscillation mode, is standard.

Each manufacturer provides a broad range of disposable blades,which often come with 6-8 cutting tip designsand with shaft diameter sizesof 5.5,4.5, or 3.5 mm. Some of thesehave a curved shaft 2 cm from the tip to allow greater maneuverability around joints. Additionally, a miniblade range of 2.0 and 2.9-mm cutters with a variety of tip ends also are available. Three broad types of disposableblades (which can be subjected to multiple uses)are available (Fig. 2.34): 1. smooth edged resectors, e.g. Dyonics Synovator and full radius blades (in 3.5, 4.5, and 5.5 mm diameter sizes) 2. toothed edged resectors, e.g. Dyonics Orbit Incisor, Incisor Plus, RazorCut, Turbotrimmer, and Turbowhisker blades (in 3.5, 4.5, and 5.5 mm diameter sizes) 3. burrs, round or oval, e.g. Dyonics Abrader and NotchBlaster in round burrs, and Dyonics Acromionizer, Acromioblaster, and StoneCutter in oval elongated burrs (in 2.5, 3.5,4.0, and 5.5 mm sizes).

The smooth-edged resector blades are appropriate for synovectomy. The toothed-edged resector (for trimming denser soft tissue) can be used for articular cartilage debride-

ment, villonodular pad removal, and meniscus and soft bone debridement, The round or oval burrs are occasionally used in chronic degenerate joints, although other blades have some value in similar situations.

Modern synovial resector units are much more useful than previous types. Design changes including larger apertures, higher speeds,narrower diameter drive shafts (easier debris clearance), spiral flutes down the length of the drive shaft, and application of suction, have all contributed to better soft tissue resection and less clogging. The oscillating mode capability of the motor (the unit switches automatically between forward and reverse) facilitates cutting of fibrous tissues and decreases clogging between the blade and housing. The speed control is computerized, with a variable speedcapacity from 0 to 8000 rpm. High speedsare necessary when using the burr, whereas slower speedsare used with the soft tissue blades.

Stocking of all the blade types is unnecessary; most surgeons developa preference for 1 or 2 soft tissue blades,and

a burr. In the Dyonics range, the authors prefer the 5.5-mm full radius blade (#7205307) for villonodular pads and menisci, the 4.5-mm rotatable curved orbit incisor (#7205320) or Incisor Plus (#7205687) for most other soft tissue resection, and the 4.0-mm Acromionizer (oval burr; #7205326) or 4.0-mm Abrader (round burr; #7205324) for bone debridement (seeFig. 2.34). Recently, a range of dualuse combination tips (Dyonics BoneCutter) have been introduced, which resect both soft tissue and bone. These are available in synovator and full-radius styles, and minimize both inventory and the need to switch blades in surgery.

Use of suction on shavers generally improves cutting performance. However, attention to the degree of filling of the suction bottle is required to prevent the automatic suction shut-off engaging, which can then allow fluid to flow back from non-sterile tubing and couplers at the bottle through the sterile patient line and out the shaver into the joint or onto the sterile field. It has been recognized as a potential risk in the use of shavers for some time (Bacarese-Hamilton et al 1991), and it is particularly likely to happen when the fluid ingressruns out at that same moment, removing the positive pressureforcing joint fluid into the suction line. Prevention requires suction to be maintained on the tubing at all times, or at the very least ensuring the joint is pressurized during suction bottle exchange.

Electrosurgical radiofrequency

and devices

Considerableinterest and concurrent concern surrounds the use of radiofrequency (electrosurgical) devices for cartilage and synovial soft tissue procedures (Polousky et al 2000, Medveckyet al2001, Lu et al2001, Lee et al2002; Sherk et al 2002). Radiofrequency (RF) devices utilize extremely highfrequency alternating current (e.g. 330 kHz compared to the 60 Hz of regular alternating current), which passes to the tissue at the applicator tip and then through the body to exit at a wide grounding plate, essentially as for all electrosurgical units. The cutting and vaporizing capability depends on the power and waveform settings. High power settings and low voltage tends to cut, while low power settings at relatively high voltage denatures and coagulates tissues (Sherk et al 2002). Used in the liquid environment of the joint, both of these modes have found a place for excision of tissue (plica, adhesions,villonodular masses),or denaturation of cartilage (cartilage sculpting or chondroplasty). Radiofrequency devicesused in a cutting mode, at the lowest settings that will still cut plica, ligament, menisci, or masses,seemto be safe if the probe is directed away from cartilage and does not dwell on bone (Polousky et al 2000, Lee et al 2002). Similarly, thermal capsular shrinkage using low power settings has many proponents and seems relatively low risk (Medvecky et al 2001). However, RF devices used for thermal chondroplasty at recommended settings penetrate to the subchondral bone and cause chondrocyte death (Lu et al 2000, 2001).

Despite the apparent smoothness of cartilage after RF chondroplasty, the later necrosis can be devastating, and is

the subject of ongoing debate. investigation. and litigation (Lee et al 2002). Given these issues. RF for chondroplasty should be avoided until further studies define safe settings. and the use of RF probes in cutting modes for capsule. check ligament. or annular ligament transection should use the minimal power settings that still achieve the desired effect. and should absolutely avoid cartilage and underlying bone.

Lasers Lasershave beenused in arthroscopic procedures for removal of fibrillated cartilage. synovial proliferation and masses.and for transection of plical and other adhesive syndromes (Lubbers & Siebert 1997. Janecki et al 1998. Smith & Trauner 1999). They have declined in popularity in recent years due to the continued high cost of the units and concern over thermal damage to the cartilage and underlying bone (Atik&Tali 1999. Sclamberg & Vangsness2002). Lasertypes include COpNd:YAG. Ho:YAG. and excimer wavelengths. The use of CO2lasers has diminished. while Ho:YAG and excimer lasers have persisted (Roth & Nixon 1991. Smith & Trauner 1999. Doyle-Jones et al 2002). Laser capsule shrinkage for shoulder and knee disorders and laser-assisted partial meniscectomy remain the primary use in man (Lubbers & Siebert 1997. Smith & Trauner 1999). Laser chondroplasty has been controversial and. despite an excellent appearance following lasersculpting. later cartilage necrosisand mounting researchevidence suggestthe use of laser for cartilage debridement is dangerous unless extreme care in power settings and methods of application are employed Ganecki et al 1998.

Sclamberg & Vangsness2002; Atik et al2003).

Laser-assisted arthrodesis of the distal tarsal joints provides a minimally invasive method for cartilage debridement and articular desensitization (Hague & Guccione 2000). Eventual distal intertarsal and tarsometatarsal joint arthrodesis can develop;however. resolution of the symptoms of bone spavin do not necessarily require radiographically defined obliteration of these joints.

Still photography Historically,still photographicimageshave beenrecordedon 35-mm film using a camerawith a quick mount adaptorto the arthroscope. However,this is time consuming, risks contaminating the surgical field, and is extremely light sensitive.A practical alternative is to use a digital camera such as a Nikon Coolpix 4500 fitted with an endoscope adaptor,e.g. Karl Storzrapid coupling adaptor (Fig. 2.35).

Imagesare viewedon a screenon the back of the camera, storedon a memorycard,and may be downloadedlater to a computerfor imageadjustmentand archiving.

Video documentation -

Capture of video clips as analog video on a ~-inch VCR i: simple and cost-effective for case documentation. It does not

however, provide duplicate copies to provide the owner or trainer with surgical documentation, nor does it provide easy accessto an individual caseburied in the middle of a 120-min video tape. Review of a video and subsequent image capture for still printing is also very time consuming and does not lend itself well to the flow of information to the client. However, video and s-video formatted VCRs have become very cheap, and are better than no documentation. Further, simple video digitizing programs, such as Windows MoviemakerTM (Microsoft), iMovieTM (Apple), VideoStudio 6TM (ULead Systems), or Pinnacle Studio Version 7TM(Pinnacle Systems Inc), all provide a means to capture video from !-inch tapes as digital video (e.g. MPEG format) or as digital still images (e.g.

JPEGformat) that can then be stored electronically or printed out for several cents an image on a color ink-jet printer.

Additionally, digital video clips can be edited, trimmed, spliced, and assembled into an annotated presentation using these programs. Other capture systems using Hi8 video capture have been described and for a complete review of arthroscopic image documentation, the reader is directed to a recent review which provides an in-depth comparison of systems, cabling, connectors, and output devices (Frisbie 2002).

Digital ima~e capture and storage devices Arthroscopic image printing and storage has undergone significantimprovementalong with the electronicrevolution of the previous decade.The simplesttechnique for image documentationis electroniccapture and printing on a dye sublimation printer (Brown 1989. Johnson2002). Selfcontained units such as the SonyMavigraphS(Fig. 2.36). .'Sony Electronics, 1 Sony Drive, Park Ridge, NJ 07656. Tel: (201) 930-1000. www.sonystyle.com

capture the image (often by clicking a button on the video camera), and store and arrange the images during the surgery. A 3.5 x 5 or 6 x 8-inch print is produced when a preset number of images have been accumulated to memory.

The print quality (300 dpi) from a high end, digitally enhanced, 3-chip camera can be photographic quality (Brown 1989). The authors have used the Sony Mavigraph UP-5600MD, Mavigraph UP-5200MD and the Mavigraph UP2900 color video printers. The UP-5600MD provides excellent image quality at approximately $1 per page. These units sell for $4,000-$6,000. More economical storage can be provided from small devices such as the Sony MavicapTM electronic capture and storage device. This stores images on floppy disks, which can then be printed on an office computer and inexpensive color ink-jet printer.

Complete digital capture and storage devices for arthroscopic use are manufactured by Karl Storz, Stryker, and Dyonics. All three units are expensive, but store both digital still images (TIFF format-with Storz AIDA and JPEGformats with others) and digital video clips (MPEGI or 2), with the touch of a button on the camera head. The Stryker SDCPro 2TMand the Storz AIDA are the more sophisticated units in the field of digital storage devices (Figs 2.37 and 2.38). The units have touch screen patient input, and image editing for still image output. Image printing can be done in the surgery by attaching an inexpensive HP deskjet printer, while still and video images are also savedon the system's hard drive. At the completion of each case,the files are savedon CD or DVD. The software in the unit provides versatile settings that allow extensive customization of image capture and compression, image editing, output styles, text addition, and internet access. Retail prices range from $12,000 to $16,000. The Smith & Nephew -Dyonics Vision 625 Digital Capture

(Fig. 2.39) providesmany similar featuresto the be via zip disk or CD drive. and the $9,700 to $12,000.

of equipment steam autoclaving shortens the useful life of an by causing deterioration of the adhesives the major lenses. Seals and bonding between

materials may deteriorate from thermal shock; various materials expand and contract at different rates in response to the rapid temperature changes in a steam autoclave. Some manufacturers sell autoclavable arthroscopes, which provide a more durable arthroscope for steam sterilization. Gas sterilization with ethylene oxide is effective and safe, but it is not always available, is time consuming and does not allow multiple procedures in a day using a single set of instruments.

Consequently, the use of a 2% solution of activated dialdehyde (Cidex@,Surgikos Inc:) was developedas an agent for cold sterilization procedures. Cidex Plus@ has a 30-day shelf life after reconstitution, compared to the 14-day span of Cidex@,which provides cost savings for frequent users. The safety and effectiveness of Cidex has been documented in 12,505 human arthroscopic procedures (Johnson et al 1982). A 0.4% infection rate was noted in this series. The arthroscope and surgical instruments are soaked for a minimum of 10 minutes. It has been stated that more than 30 minutes of soaking can be damaging to the lens system of the arthroscope (Minkoff 1977). Glutaraldehyde polymerizes on standing. When this occurs, crystals can form and cause clouding of arthroscope lenses.

The surgeon or assistant should be double gloved and removes the instruments from the Cidex and places them in a sterile tray. The instruments are washed with sterile water or saline (Fig. 2.40) and transferred to the surgery table where they are dried after the surgeon's outer gloves are removed.

Ancillary instruments (towel clamps, scalpel handle, needle holder, and thumb forceps) can be previously autoclaved within the tray, which is then used for washing the soaked instruments. Rinsing of the equipment must be done with care to avoid damage to the camera and arthroscope from sharp-edged hand tools. .'SurgikosInc.. POBox 90130, Arlington, TX 76004. Tel: (817)465-3141

The 2% dialdehyde solution is properly classified as a disinfectant. The chemical is considered bactericidal in 10 minutes, destroying all bacteria, including Myobacterium, tuberculosis, Pseudomonas aeruginosa, and viruses. It is sporicidal in 10 hours and therefore is considered a sterilizing agent after use for 10 hours Uohnson et al1982).

A number of glutaraldehyde-based disinfecting solutions are available. Use of a solution that does not contain a surfactant is recommended (Cidex-activated dialdehyde solution does not contain a surfactant). Surfactants may leave a residue, causing stiffening of moving parts and potential electrosurgical malfunction. Because surfactants lower the surface tension of the disinfection solution, the disinfectant can penetrate small cracks and crevices. This penetration creates a rinsing problem, because high surface tension prevents water from entering the cracks and crevices and removing the disinfectant. As this disinfectant residue

accumulates, stopcocks and other moving parts cease to function smoothly. Surfactant-containing solutions can also erode epoxy and other thermal plastics. From personal experience, severe damage resulted when soaking a camera in such a solution. Another recommendation is that plastic basins be used to soak instruments (McDonald 1984). These basins reduce electrolytic corrosion, which can occur when metal instruments are soaked in metal pans.

The question of the potential for Cidexto cause a chemical reaction in joints was addressed in the literature (Harner 1988). Results of studies in rabbits showed that Cidex induced a diffuse synovial inflammation when present intraarticularly at concentrations of 10 ppm or greater. The degree of synovial inflammation is proportional to the concentration of Cidex. At 1000 ppm, chondrolysis occurs.

When using a single-rinse basin, the concentration of Cidex in the rinse basin is 100-300 ppm; if the same rinse solution is used, the concentration can be 1000 ppm by the fifth procedure. Clearly, fresh-rinse solutions should be used for each procedure. A double rinse reduces the Cidex concentration in the second rinse to the order of 1 ppm. Mter irrigation of the joint with 1 liter of saline, however, the intra-articular concentration of Cidex is less than 1 ppm, regardless of the rinse technique (Harner 1988).

Toxicity and safety issueshave reduced the use of Cidex in many practices. An effective and less toxic alternative is the peracetic acid SterisTMsystemU,which uses a liquid peracetic acid (35%), acetic acid (40%), hydrogen peroxide (6.5%), and sulfuric acid (1 %) soak,followed by a water rinse, for a total of 4 cyclesin a closed system,to provide sterile and virtually dry equipment for arthroscopy (Fig. 2.41). Each sterilizing run has a chemical indicator strip (min 1500 ppm) included to verify the sterility of the instruments. The disadvantages are the cost of the unit, and the process requires 30 minutes rather than 10 minutes to complete,so emergency sterilization for a dropped instrument still requires Cidex.

In many parts of Europe, the use of Cidex is no longer permitted. A safe alternative is MedDisTM instrument disinfectantV, which relies on halogenated tertiary amines, hexamethylene biquanide hydrochloride, ethyl alcohol, dodecyclamine, and sulfonic acid to sterilize instruments.

This solution is diluted to 5%, and is then bactericidal, fungicidal, and virucidal after a 10-minute exposure, and tuberculocidal and sporicidal within 30 minutes. Shelf life after activation is 14 days. It also has safety advantages in that it is non-irritant, non-fuming, non-corrosive, and has no reported effects on metal or glassendoscopecomponents.

Surgical assistants

Becauseof the unique instrument requirements and the need to have a smooth sequential system during the operation, scrub nurses or technicians participating in operative arthroscopy must be especially trained. It cannot be

.USteris 20. SterisCorp, 5960 ReisleyRoad.Mentor. OR44060. Tel: (800] 548-4873. www.steris.com ."Medichemlnternational. POBox 237, SevenOaks. Kent TNI 5 02J. UK

minimal or extensivedraping by vary from simple reuseablecloth the horse, severalsmall drapes for

The

sticky drapes (loban, 3M!) is a very

of liquid used in arthroscopy. Application of an adhesive drape followed by one or two surrounding impervious drapes, and finally a large disposable drape is standard (Fig. 2.42).

For simplicity, a large sticky drape provides a good sterile field to which an experienced user can then apply a large disposable drape directly, to complete the sterile set-up. It is critical that the surgeon and his assistants not drag the disposabledrape across the prepared joint (double shuffling) or the inner surface of the disposable drape that has contacted the animal will then rest over the joint to be operated.

Inexperienced users should add a quadrant of additional draping between the adhesive drape and the large arthroscopy drape, to increase the margin of safety. Large drape systemsare manufactured by Gepcowand Veterinary Surgical ResourcesX.Some arthroscopy packs also contain disposable gowns. In general, most manufacturers offer a range of pack contents, so individual preferences can be accommodated.

Clearly, the complete systems lack nothing, but can be expensive (up to $82). The arthroscopy drape pack can be ordered for unilateral or bilateral arthroscopy, the latter providing two rubber dammed areas, one per joint, with 30-38 inches between them. Thesecan be cumbersome to apply, but provide exceptional large sterile fields without the need for other body sheets.The authors also vary the type of draping to the situation; numerous drapes around the foot will limit accessfor coffin joint arthroscopy or digital sheath tenoscopy, whereas full draping systems are easy to apply around the stifle or hock, and provide ready access to all the joints comprising these articulations.

Care and maintenance

of equipment

that an assistanttotally familiar with the

Most care and maintenance issues should be covered by instructions with individual equipment items. However. repair of arthroscopes is a costly and all too frequent concern in equine arthroscopy. All arthroscope vendors repair their own telescopes.However. the cost can vary (depending on the extent of damage) from $1.000 to $2.200 (almost the cost of a new arthroscope). Third-party vendors repair arthroscopes from most manufacturers. One of the larger repair companies

and draping systems tend to be determined by the preference, cost of drapes, and the safety and

.13M Orthopedics Products Division. 3M Center. St. Paul. MN 551441000. Tel: (888) 364-3577. www.mmm.com .wGepco. GeneralEconopakInc.. 1725 North 6th Street.Philadelphia. PA 19122. Tel: (888) 871-8568. www.generaleconopak.com .'Veterinary Surgical Resources.Inc. POBox 71. Darllngion. MD 21034.

Tel: (800) 354-8501. www.vetsurgicalresources.com

is Instrument Makarr. The cost of repair generally ranges from $350 to $600. However, the repair vendor should always provide a free assessmentof damage and a quote for repair. A more informed decision for repair or replacement can then be made.

Pressure and cold bandaging Preoperativeand postoperativepressurebandaging is common practice in equine arthroscopy. but use of combination cold and pressuredeviceshas beenunderutilized. The value of cryobandaging following acute injury is well known to horse trainers and owners but largely ignored in the immediate postoperative phase by surgeons.The use of wet ice and ice slushes should obviously be avoided. given the recent incisions into the joints. However. dry cold products have a role in reducing the postoperative pain and swelling that is recognized in human arthroscopy and in the rehabilitation of athletes (Barber et al1998. Martin et al2001). Somecryo-cuff devices combine both cold and pressure massagesystems (Fig. 2.43) .'Instrument Makar. Division of Smith & NephewInc. EndoscopyDivision.

150 Minuteman Road. Andover. MA 01810. Tel: (800) 343-5717. www.endoscopy1.com

Motorized arthroscopic instruments: a -setup and equipment. Orthop Clin impressions of a new technique ..-Vet

al 1995). Thesedevices'have beenused foland the resoluparticularly periarticular swelling, has

the holmium:YAG laser cause osteonecrosis?

113.

IA. Bhamra M. Jackson AM. Arthroscopic , 'sepsis. Ann R Coil Surg McGuire DA. Click S. Continuous-flow cold therapy , anterior cruciate ligament reconstruction.

130-135. an infusion pump in arthroscopy.

Producing still imagesin arthroscopy.Arthroscopy RB. Current development of instrumentation for .Clin Sports Med 1987; 6: 619-636.

Augustini B-G. Three irrigation systems for motorized .surgery: a comparative experimental and clinical : 307-314.

Synovial regeneration in carpus after arthroscopic mechanical or carbon .Vet Surg 2002; 31; 331-343.

EF. Poehling GG. Principles of arthroscopy and wrist ..

fluid medium. Orthop Clin North Am 1982; 13: Arthroscopic documentation. Clin TechEquine Pract .1: 270-275. .'Equine Cryo-Cuff,GameReadyCoolSystems Inc., 929 CameliaSt,Berkeley, CA 94710. Tel: (866) 266-5797. www.gameready.com

.Proc 34th Ann Mtg Orthopaedic : 332.

Jackson DW. Ovadia DN. Videoarthroscopy: present and future developments. Arthroscopy 1985; 1: 108-115.

JagerR. Technical and instrumental requirements of arthroscopy of the knee joint. Endoscopy 1980; 12: 261-264.

Janecki CJ,Perry MW. Bonati AO. Bendel M. Safeparameters for laser chondroplasty of the knee. Lasers SurgMed 1998; 23: 141-150.

Johnson DH. Basic science in digital imaging: storage and retrieval.

Arthroscopy 2002; 18: 648-653.

Johnson 11. Shneider DA. Austin MD. et al. Two per cent glutaraldehyde: a disinfectant in arthroscopy and arthroscopic surgery. J Bone Joint Surg Am 1982; 64: 237-239.

Johnson RG. Herbert MA. Wright S. et al. The response of articular cartilage to the in vivo replacement of synovial fluid with saline.

Clin Orthop 1983; 285-292.

Lee EW. Paulos LE. Warren RF. Complications of thermal energy in knee surgery -Part II. Clin Sports Med 2002; 21:

753-763.

Lu Y. Edwards RH. III. Cole BJ. Markel MD. Thermal chondroplasty with radiofrequency energy. An in vitro comparison of bipolar and monopolar radiofrequency devices.Am J Sports Med 2001; 29: 42-49.

Lu Y. Hayashi K. Hecht P. The effect of monopolar radiofrequency energy on partial-thickness defects of articular cartilage.

Arthroscopy 2000; 16: 527-536.

Lubbers C, Siebert WE. Holmium:YAG-laser-assisted arthroscopy versus conventional methods for treatment of the knee. Two-year results of a prospective study. Knee Surg Sports Traumatol Arthrosc 1997; 5: 168-175.

Martin SS. Spindler KP. Tarter JW. Detwiler K. Petersen HA. Cryotherapy: an effective modality for decreasing intraarticular temperature after knee arthroscopy. Am J Sports Med 2001; 29: 288-291.

McDonald R. Rigid endoscopes. Proper care and maintenance.

AORN J 1984: 39: 1236-1242.

McGinty JR. Photography and arthroscopy. In: Casscells SW (ed.).

Arthroscopy: diagnostic and surgical practice. Philadelphia: Lea & Febiger; 1984.

Medvecky MI. Ong BC. Rokito AS. Sherman OH. Thermal capsular shrinkage: basic science and clinical applications. Arthroscopy 2001; 17: 624-635.

Minkoff J. Arthroscopy -its value and problems. Orthop Clin North Am 1977; 8: 683-706.

Morgan CD. Fluid delivery systems for arthroscopy. Arthroscopy 1987; 3: 288-291.

Noyes FR. Good ES. Hoffman SD. The effect of flexion angle on pressure-volume relationships in the human knee. Proc Ann Mtg AANA. Ogilvie-Harris DJ. WeislederL. Fluid pump systems for arthroscopy: a comparison of pressure control versus pressure and flow control.

Arthroscopy 1995; 11: 591-595.

Oretorp N. Elmersson S. Arthroscopy and irrigation control.

Arthroscopy 1986; 2: 46-50.

PoeWing GG. Instrumentation for small joints: the arthroscope.

Arthroscopy 1988; 4: 45-46.

Polousky JD. Hedman TP. Vangsness CT Jr. Electrosurgical methods for arthroscopic meniscectomy: a review of the literature.

Arthroscopy 2000; 16: 813-821.

Reagan BF. McInerny VK. Treadwell BV. Zarins B. Mankin HJ. Irrigating solutions for arthroscopy. A metabolic study. J Bone Joint Surg Am 1983: 65: 629-631.

Roth JE. Nixon AJ. Pulsed carbon dioxide laser for cartilage vaporization and subchondral bone perforation in horses: 1.

Technique. clinical results. and synovial fluid response. Vet Surg 1991: 2018: 190-199.

Sclamberg SG. Vangsness. CT Jr. Laser-assistedchondroplasty. Clin Sports Med 2002: 21: 687-691. ix.

Sherk HH. VangsnessCT. Thabit Gill. Jackson RW Electromagnetic surgical devices in orthopaedics. Lasers and ramofrequency.

J Bone Joint Surg Am 2002: 84-A: 675-681.

Smith CP.Trauner KB. Arthroscopic laser surgery: a revisitation. Am J Knee Surg 1999; 12: 192-195.

Straehley D. The effect of arthroscopic irrigating solutions on cartilageandsynovium. Trans 31stAnnMtgORS 1985; 15: 260.

Takahashi T. Yamamoto H. Development and clinical application of a flexible arthroscopy system. Arthroscopy 1997; 13: 42-50.

Whelan JM. Jackson DW:Videoarthroscopy: review and state of the art. Arthroscopy 1992; 8: 311-319.

Whitelaw GP. DeMuth KA. Demos HA. Schepsis A. JacquesE. The use of the Cryo/Cuff versus ice and elastic wrap in the postoperative care of knee arthroscopy patients. Am J Knee Surg 1995; 8: 28-30.

principles can be applied to the other joints. The maneuversin the different joints are

evaluation of the patient undergoing an arthroscopicprocedurefor a or suspectedintra-articular problem must first be These principles may be taken for granted by ,.

The hazard of avoidhas also been noted in association with

1983). the lack thereof) are discussed

preparation

-

skin incisionsso that a hair or portion of hair is not into the joint on insertion of the arthroscopeor

arthrocentesis sites. it has been concluded the skin over the midcarpal and joints can be accomplished without

and surgical scrub for the surgeon is routinely done with either povidine iodine or chlorhexidine gluconate. The authors have switched to the latter. The iodophors have several disadvantages,including diminished effectivenessin the presence of organic matter, a high incidence of dermal irritation, potentially unreliable residual activity, and toxicity (Phillips et al 1991, Rosenberg et al1976). CWorhexidine closely fulfills all the criteria of an ideal preoperative patient skin preparation: having a broad spectrum of antimicrobial activity, it reduces bacterial numbers quickly by disrupting the bacterial cell membrane and precipitating cellular contents, has excellent residual activity (even in the presence of organic material), and causes minimal skin irritation (Stubbs et al1996). However, it should be noted that in a study evaluating the effectivenessof a 5-minute surgical scrub using either a one-brush or two-brush technique in clean and dirty surgical procedures, and also comparing the efficacy of povidone iodine with cWorhexidine as surgical scrub solutions, both povidone iodine and cWorhexidine were equally effective in decreasing bacterial numbers on the skin, given a variety of contamination levels present before the scrub procedure (Wan et al1997).

The authors perform all arthroscopic surgical procedures in the carpus, dorsal fetlock, tarsus, and stifle joints, with the horse in dorsal recumbency, except in isolated instances when the facilities do not allow this positioning. Arthroscopic surgery on carpal, fetlock, and tarsocrural joints is quite feasible with the horse in lateral recumbency, but if entry sites for the arthroscope need to be switched (when chips are in both sides of the joint or in the same location bilaterally), rolling the horse during surgery often is necessary. Dorsal recumbency is mandatory for arthroscopic surgery in the femoropatellar joint.

The method of draping is the choice of the individual surgeon. Becauseof the fluid involved, an impervious draping systemis needed(Fig. 3.1). The use of adhesive barrier drapes is also recommended. Some problems have occurred with some of these products in regard to adhering to the skin satisfactorily. In this regard, Iobana drapes are superior.

.8Ioban. 3M Orthopedics Products Division. 3M Center. St. Paul. MN

55144-1000.

Arthroscope

insertion and positioning

A 6- to la-mm skin incision is made at the site of insertion of the arthroscope (Fig. 3.2). The various sites of insertion of the arthroscope and instruments for each joint are detailed in later chapters. In the carpal joints. the incision is made between the extensor carpi radialis and common digital extensor tendons for a lateral approach and medial to the extensor carpi radialis tendon for a medial approach. Also. these incisions are made before distention of the joint with fluid so that the puncture site position in relationship to these tendons and their sheaths is carefully placed. The position of

the tendon sheath can be obscured once the joint is distended. If the arthroscope is not introduced in the proper site, the maneuverability can become limited and undesirable penetration of certain structures (such as bursae or tendon sheaths) may occur.

In joints other than the carpus, distention is performed prior to making portals. as avoidance of tendon sheaths is not an issue and the distended joint aids in portal location (Fig. 3.3). This distention prevents damage to the articular cartilage when the trocar or conical obturator penetrates the joint capsule.

A No. 11 or No. 15 scalpel blade is then used to make a portal in the joint capsule. A conical obturator is placed within the arthroscopic sheath and this combination is used to insert the sheath through the fibrous joint capsule with a

gentle twisting motion (Fig. 3.4). The sheath is initially inserted perpendicularly to the skin surface. avoiding any tendency to angle toward the ultimate position of the scope.

This position is to obviate opening a subcutaneous dissection plane. Advancement of the sheath within the joint is achieved most safely by use of the blunt or conical obturator, becausethe articular cartilage is at risk for damage when the sheath containing the arthroscope is advanced. This risk has been decreased by improved congruity between the ends of the sheath in relationship to the end of the arthroscope in currently available instruments. The authors no longer use the sharp trocar for insertion of the arthroscopic sleeve in any joint.

Once the arthroscopic sheath is in place, the blunt obturator is replaced with the arthroscope, and the fiberoptic light cable and the ingress fluid system are attached to the arthroscope and the sleeve, respectively (Fig. 3.5). The ingress fluid line has been cleared of air bubbles to avoid

entry of the latter into the joint. Direct arthroscopic visualization of the joint can then be performed (extremely rare nowadays) (Fig. 3.6), or the video camera (seeChapter 2) can be attached. depending on the method used by the surgeon.

If the camera has not been soaked. the use of a sterile sleeveis necessary.If using a sleeve.it is important to ensure a watertight seal of the cover over the head of the arthroscope.

After insertion of the arthroscope. in the case of the carpus, the instrument portal through the joint capsule is made with a direct perpendicular stab with a No. 15 or No. 11 blade (Fig. 3.6). In other joints, the instrument portal is made in the same fashion. but often a needle is placed in the proposed position and visualized. and, if appropriately located, the instrument portal through skin and joint capsule is then made. The authors' prefer to create the portal and then insert the small egress cannula without using a trocar or obturator (Fig. 3.7).

Any cloudinessor hemorrhage within the joint can be cleared by opening the egresscannula and pumping fluid through the ingresssystem.Regardingthe use of the egress cannula in the carpal and fetlock joints, the holes in the cannula must not extendmorethan 6- 7 mm fromthe end of the cannula. If they do, the cannula should be shortened appropriately.Otherwise,someholes will not be within the joint but will be within the subcutaneoustissues,promoting rapid extracapsularextravasationof fluid.

Oncethe view is clear,the stopcockon the egresscannula is closedduring visualization;otherwise,villi waving within the flowing fluid obstructthe view (Fig.3.8).This pointneeds emphasizingbecauseother authors in equine arthroscopy mention the difficulties with synovial villi obstructing the visual field, and advocatethe use of adjunctive synovial membraneresection.This procedurenecessitatesthe use of motorized equipment. Alternatively, gas distention rather than liquid distentionpreventsthis problem. In diagnostic arthroscopyof the human knee,the useof both a suspended fluid sourceand constantflow of fluid through the kneehave

been recommended (Crane 1984). In the authors' opinion, this technique is unsatisfactory in the carpus and fetlock of the horse because of the smaller size of the joint and the increased amount of synovial villi. As referred to subsequently, villi interposition is not a problem in arthroscopic procedures in the human knee, but it is often a major one in the horse, necessitating the use of different techniques to handle this situation. The use of closed distention obviates the problem of villi interposition rather well in most instances.

Any fluid system capable of exerting pressure within the joint has the potential to cause its own complications (Noyes & Spievack 1982). Joint capsule rupture in the human knee at about 200 mmHg pressure has been recorded, and this rupture in turn causes severeextracapsular extravasation of fluid. Flexion of the joint markedly elevates the pressure in a given joint. Severeflexion changes during equine arthroscopy are rare, but a situation of high intra-articular pressure can developeasily.The choices of fluid systems were discussedin Chapter 2. The requirements for joint distention in equine arthroscopy are quite high; at the same time, however, it is important to be aware that excessivepressure can exacerbate the degree of fluid extravasation with or without joint capsule rupture. For these reasons, the authors do not recommend the use of constant pressure fluid administration systems, including fluid bags with pressure cuffs or bulb syringe pressure cuffs or direct gas insufflators. Two of the authors use a Cole-Parmer system where variable flow rates can be changed quickly. In this way a slow flow rate is used under the closed examination and then this flow rate can be increased as necessary when there is an open instrument portal. Pumps used in human arthroscopy have improved (see Chapter 2) and are generally now available free if sufficient delivery tubing is purchased. The system recently developed by Arthrex@ has been used in the horse and is effective.

During arthroscopic surgery, once a larger instrument or fragment passesthrough a portal in the joint capsule, some degree of constant fluid egressthrough this portal is unavoidable. Consequently, some villi interposition occurs. For this reason, the diagnostic examination must be completed before surgical removal of large fragments from the joint. For the same reason, a small (2.7-3.0 mm) egresscannula is used for an initial flush. This avoids a large instrument portal and the continuous fluid flow during the initial examination.

The arthroscopist should be continually reminded that visualization could be enhanced greatly by rotating the arthroscope. Simply by rotating the arthroscope (without changing the position of the arthroscope), the visual field of view is greatly increased. This generally obviates the need for a 700 arthroscope.

Arthroscopic surgery and the principle of triangulation Although the details of arthroscopic surgery for each joint are presented in later chapters. the principle of arthroscopic

here becausethe use of both the and they are used according to Two basic techniques have beendevelopedfor arthroscopic -

Although it orthopedic practice (Carson 1984), the technique not beenused in equine surgery and thereforeis not The secondtechnique is triangulation. which involves one or more operating instruments through -~

the instrument and the arthroscopeforming

3.9, (and alsoin Figs.4.21 to 4.23) and it is to handle all of the various surgical requirementsin --

as well as surgicalarthroscopy.To be ableto use technique effectively,the surgeon must developthe confined

space while

using

monocular

vision,

which

.,

For arthroscopic

,

surgery, instrument portals are made in .on the joint and the site of the

Cannulas or sleeves are rarely used at instrument for reasons mentioned in Chapter 2. To create an a skin incision is made followed by a stab the joint capsule with the use of a No. 11 or 15 blade. These techniques have been noted previously 3.6). In the carpus, the first author (C.WM.) makes for the instrument portal before placement whereas, in other joints, it is made after placement and the position is then dictated by

Use of the probe in diagnostic arthroscopy For effective diagnostic arthroscopy, the use of a probe through an instrument portal is important, both to evaluate defects that cannot be discerned with vision alone and to provide an index of size by comparison of the lesions with the probe (seeFig. 3.9). In the carpus, the egresscannula is often used as a probe to palpate lesions. This technique is a "short cut", often eliminating the need for another instrument insertion. On the other hand, the blunt, hooked probe is important in assessingsuspect articular cartilage in cases of osteochondritis dissecans,and its use is a routine part of the procedure. Elsworth et al (1986) noted, "arthroscopy without the use of the probe is an incomplete investigation," and that routine use of the probe is essential in training for arthroscopic surgery.

Post-arthroscopic

irrigation

and closure

When the arthroscopic procedureis completed,using an openegresscannula and pumping fluid through the joints effectivelyflushesdebrisfrom the joint. Typically,the larger, 4.5 mm cannula is usedso that all debrisis removed(in the femoropatellarjoint a larger 6 romcannula is used).

No suturesare requiredto closethe joint capsuleportals.

One or two sutures are placed in the skin incisions. One suture is usually sufficient. The authors prefer a simple interrupted pattern to a cruciate pattern, to avoidinverting the skin edge.In human arthroscopy,some authors have madea casefor not suturing skin incisions(Williamsonand Copeland1988). Cosmeticadvantageshave beenproposed and someindividuals believehematomaor stitch abscesses are less likely to occur. Suturing is consideredthe safer alternativein the horse.Specificpostoperativemanagement is discussed in the individual joint chapters.

The publicity associated with surgical arthroscopy has overshadowed the use of the arthroscope in diagnostic evaluation of the joint. It is well recognized that traditional diagnostic methods used in the evaluation of joint disease (clinical examination, plain and contrast radiography, and synovial fluid analysis) have definite limitations, particularly in evaluating articular cartilage changes. The diagnostic usefulness of arthroscopy in the evaluation of equine joint disease was documented in 1978 (Mcllwraith & Fessler1978). The use of the arthroscope as a surgical decision maker in human orthopedics is well established (Hots & Hoerbooms 1979). As mentioned previously, however, arthroscopy is an adjunctive diagnostic technique and should not replace traditional diagnostic methods. The hazards of not evaluating a joint radiographically prior to arthroscopy are documented in man Goyce& Mankin 1983). As discussedin later chapters,

obtaining both pre-and postoperative radiographs should be mandatory in equine arthroscopy.

Arthroscopy is valuable in assessingsynovial membrane. articular cartilage. intra-articular ligaments. and menisci (in the stifle). The ability to perform diagnostic arthroscopy of parts of the equine femorotibial joints has furnished considerable amounts of new information and much progress has been made in this area since the last edition of this text.

The usefulness of diagnostic arthroscopy in enabling the clinician to make a diagnosis when no other technique can do so is worthy of emphasis. These conditions include tears in the cruciate ligaments as well as the medial palmar intercarpal ligament. meniscal injuries. and radiographically "silent" osteochondral fragmentation. subchondral bone disease.and various articular cartilage lesions.

Knowledge of normal

anatomy

Before valid interpretations of changes in the joint can be made, the surgeon must know the arthroscopic anatomy.

This prerequisite, in turn, means relearning joint anatomy, which constitutes the first learning step in arthroscopy, be it diagnostic or surgical. Knowledge of dynamic as well as static anatomy is necessary. The surgeon needs to know the changes that occur with variations in joint position.

Since embarking in arthroscopy, the authors have gained a considerable amount of knowledge regarding joint anatomy, particularly with regard to the synovial membrane and other soft tissue structures (Fig. 3.10). In addition to the smooth and villous areas, specific to certain sites in the joint, a number of normal plicae (folds) are present that have not been documented in equine anatomy texts. The positions of these folds are noted in later chapters.

The tautness of the joint capsule and ligaments limits the ability to examine certain joints or areas of certain joints. including the medial aspect of the antebrachiocarpal joint. the medial aspect of the patellofemoral articulation. and much of the femorotibial joint. Pitfalls of examining articular cartilage include over-interpretation. owing to magnmcation. and failure to recognize normal variations in morphology in the joint.

Observation of debris synovial fluid

in the

Before discussing specific examination of the synovial membrane and cartilage, we should acknowledge the presence of debris that is often noted on initial observation of a joint before flushing. Usually, this debris is flushed out and is not further defined; however, some potentially valuable information may be lost. In a series of human knee arthroscopic cases reviewed by Mori (1979), debris was found in 46 of 732 joints examined. The author classified the debris into four groups: precipitation of fibrin (14 cases); degeneration and necrosis of villi (20 cases);desquamation of articular cartilage (9 cases);and metaplasia of villi (3 cases).

Necrosis of villi was considered to result from a cycle of remission and recurrence of acute inflammation, such as rheumatoid arthritis. When remission of acute inflammation began at the root of villi as a result of steroid use, it induced ischemic necrosis at the periphery. Thinner and longer villi have a greater tendency to become necrotic. These ideas appear to be subjective and were not supported by histologic data, but they may well provide an explanation for some findings in the evaluation of horses.

Evaluation of synovial and synovitis

membrane

The morphologic features of the synovial membrane and its villi can be visualized better with arthroscopy than by examination of a gross specimen or during arthrotomy (Bass 1984). When arthrotomy is performed, villi tend to cling to the synovial membrane and cannot therefore be seen distinctly. In arthroscopy, because the observation is performed in a fluid medium, the shape of the villi stands out distinctly, and transillumination allows improved visualization of the villous vascularity. The magnification of the arthroscope also facilitates definition. The degree of magnification varies, however,depending on the distance of the object from the end of arthroscope. If the end of the arthroscope is 1 mm from the object, the magnification is 10 times; at a 1 cm distance, no magnification is noted (Crane 1984).

The morphologic features of synovial villi in the horse have been classified (McIlwraith & Fessler 1978). This classification does not cover all possibilities, but some degree of nomenclature is required to document various changes with synovitis. Rather than use a simple classification system,

In

the arthroscopic surgeon needs to be able to recognize the synovial pattern for specific areas of each joint. Definition of abnormalities depends on a sound knowledge of the normal distribution and characteristics of the villi. For example, in the normal i.e. middle carpal joint, polyp-like filamentous villi are typical of the dorsomedial and dorsolateral areas of the joint (see Fig. 3.10). In the far medial portion of the joint, the synovial membrane is smooth, white, and without villi.

The presence and morphology of normal synovial plicae and the normal intra-articular ligaments need to be known (Fig. 3.11).

The surgeon needs to recognize the many variations of normal synovium that exist and the degree of change that can occur with minimal clinical compromise.

Synovitis manifests in a number of forms that have yet to be completely characterized: 1. Hyperemia is typical of acute synovitis (Fig. 3.12). It may be accompanied by some degree of edema and fibrin deposition.

2. Petechiation can be observed.

3. Development of small, hyperemic villi in abnormal locations.

4. Thickening of villi and an increase in density of villi (Figs 3.13 and 3.14).

S. Formation of new types of villi (e.g. cauliflower-like villi).

6. Atrophy of villi and total flattening of villous areas with fibrin band deposition and adhesion formation.

7. Formation of plump polypoid villi with detachment of these massesto form "rice bodies".

Note also that some areas or pieces of light-colored avascular synovium can often be mistaken for a loose body.

In a number of instances of traumatic joint disease,such as cases involving carpal chips, chronic fibrotic changes develop in the synovial membrane. In these cases, however, the clinical signs may not differ from those noted in instances

pathologic changes in the synovial memcarpal chip fractures are associated with Hemosiderosis may also be seen in the synovial membrane.

Synovial membrane biopsy can be performed conveniently by using the arthroscope. Although there are limitations in the histologic evaluation of synovial membrane (McIlwraith 1983), it is usefulin the diagnosisof septic arthritis. Diagnostic arthroscopy and a biopsy sampling constitute a standard protocol before lavage of infected joints. The degree of synovial proliferation and pannus formation and the presence of articular cartilage compromise can also be assessedduring this procedure. With biopsy of synovial membrane in any type of diseased joint, it is important to realize that normal areas of synovium appear alongside areas of inflammation.

For this reason, blind biopsy is considered to have limited value and a biopsy under arthroscopic visualization is the only worthwhile procedure. This opinion is supported by findings of a recent study in man in which macroscopic signs of inflammatory activity in the synovial membrane varied considerably within a single joint (Lindblad & Hedfors 1985).

In addition, a higWy significant correlation was found between the local macroscopic (arthroscopic) signs of inflammatory activity and microscopic findings.

Although specific vasculature changes are considered to occur in association with various arthritic entities and blood vessels can be seen easily in normal villi, the conventional arthroscope lacks the magnification for detailed observation of fine vascular structures. A magnifying arthroscope has been developed and used in Japan (Inoue et al1979). The details of the capillary network of the capsule and synovium have been better defined in this fashion (seeFig. 3.12B). The visual angle of the lens system is small and the visual field with good focus is narrow. A preliminary investigation was reported in which researchers used another microendoscope with the ability to pass from panoramic vision to contact view at four different magnifications, including microscopic observation of vitally stained cells (Fizziero et al1986). On the basis of these preliminary findings, the authors thought the capabilities of the device went some way toward bridging the gap between the conventional arthroscope, the light microscope, and the scanning electron microscope.

The changes observedin experimentally induced synovitis are good examples of the sequential changes that occur in synovitis (McIlwraith & Fessler 1978). They highlight not only the changes that can be observed but also the fact that repeated examinations provide a good dynamic understanding of the synovial membrane. In this study, in which synovitis was induced by using filipin, hyperemia was significant initially. Petechiation of the villi and abnormal development of small hyperemic villi in the medial aspect of the carpal joint were frequent findings. Membranous fan-like and cauliflower-like villi were seen in these joints, whereas they do not appear in normal joints. In more severely inflamed joints, fusion of villi across the joint and the presence of fibrinoid strands and adhesion formation were evident.

Chronic fibrotic changes were noted in the later stages,with

. ~

Fig. 3.12 (A) Hyperemic synovial villi in a case of acute synovitis of the carpus. (8) View of same area using magnifying arthroscope.

villi becoming thicker and denser as the disease the use of arthroscopy, new conditions can be Structures that are normal but have not dorsomedial intercarpal ligament in the midcarpal .This often

overlies joint

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3.15).

Arthroscopic

synovectomy

The remainder of this arthroscopic surgery to joint. One procedure that in any equine joint. and

book deals in large part with correct various conditions of the has been performed relatively little is not addressed elsewhere in this

text, is that of synovectomy; its use in man was described by Highgenboten in 1982. It is frequently used in the horse to facilitate the diagnostic process by allowing examination of an otherwise obscure region. Synovectomy is greatly facilitated by improved soft tissue blades for motorized units (see Chapter 2).

Arthroscopic synovectomy has been performed in human hemophiliac patients (Casscells1987, Limbird & Dennis 1987).

It reduced the frequency of bleeds and, with continuous passive motion, arthroscopic synovectomy resulted in good postoperative motion (Limbird & Dennis 1987), and has been shown more recently to be cost-effective in treating hemophiliac patients (Tamurian et al 2002). Results of another study in man suggest intra-articular release of adhesions is efficacious in the management of arthrofibrosis of the knee (chronic stiffnessof the knee) subsequentto previous operative procedures (Parisien 1988). Local synovectomy has been used in human knees where hypertrophy of the synovium in the anteromedial aspect of the joint following trauma has caused mild chondromalacic change on the medial femoral condyle and knee pain. Arthroscopic debridement of this pathologic tissue significantly improves symptoms (Chow et al2002). Equivalent indications may be found in the horse.

Figure 3.16 illustrates hemarthrosis and the biopsy of a piece of synovial membrane.

Potentially, clinicians could use synovectomy to treat equine conditions involving chronic synovitis. However, experimental work in the horse has questioned the beneficial effects of synovectomy: Studies by Jones et al (1993, 1994) and Theoret et al (1994) have reported that arthroscopic synovectomy in equine joint tissues has short-lived reversible changes on standard synovial fluid characteristics and clinical lameness. Both team of investigators reported that regeneration of the synovial membrane was not apparent by 30 days after arthroscopic synovectomy Gones et al1994) and incomplete by 120 days (Theoret et al 1994). These

the mechanical and laser techniques were performed. Horses were evaluated at 1. 3. and 6 months. Villous regeneration did not occur in any horses after surgical synovectomy. All synovial membranes healed with a fibrous subintima and less populated intima. The CO2laser was capable of performing a more superficial synovectomy than that achieved with mechanical synovectomy using a motorized arthroscopic synovial resector. The authors also cQncluded that mechanical or CO2laser synovectomy could be performed in the horse. but additional evaluation was needed before the physiologic significance of the lack of villous regeneration is known.

The authors of this textbook are concerned about capsular defects and fibrosis following synovectomy. We recommend localized synovial resection to improve visualization. but caution against using more generalized synovial resection as a therapeutic measure. at least in traumatic joint disease.The use of the resector for eliminating fibrin in infected joints is another issue and is discussedin Chapter 14. Hemarthrosis of the synovial membrane is seencommonly in the carpal canal in association with radial osteochondroma and may be occasionally seenin joints. Acute hemarthrosis is commonly seenin the early stage of severejoint injury as also occurs in man (Butler & Andrews 1988).

Evaluation of intra-articular and menisci

ligaments

Arthroscopyhasenabledveterinariansto diagnoseotherwise unrecognized lesions of the medial palmar intercarpal (Mcllwraith 1992) (Fig.3.17; seealso Chapter4) and cranial cruciate (Walmsley 2002), meniscal (Walmsley 2002) ligamentsand femorotibialmenisci(WalmsleyetaI2003).

studies were performed in normal equine joints whereas, obviously, many clinical applications of synovectomy occur in inflamed or infected joints, Another study was performed to determine if arthroscopic synovectomy had a beneficial or deleterious effect on articular cartilage in equine joints with an induced synovitis (Paliner et al1998). The authors concluded that synovectomy in inflamed joints could be more deleterious to the articular cartilage integrity than inflammation alone and that synoveGtomyin normal joints has later effects (between 2 and 6 weeks), which may be a response to the remodeling of the synovial membrane after resection (Palmer et aI1998).

Another study compared synovial regeneration in the equine carpus after mechanical or CO2 laser synovectomy (Doyle-Jonesetal2002). Twelve horseswere randomly divided into three groups. The antebrachiocarpal and midcarpal joints were randomly assigned to treatment so that each horse had one joint as a control (arthroscopic lavage), one in which a mechanical or CO2laser partial dorsal carpal synovectomy was performed, and one in which a combination of

of articular of diagnostic

cartilage arthroscopy

despitenormal radiographs.All the is the evalu-

cartilage (Casscells 1984). Evidence of changes in the cartilage can be recognized only when lesions extend into the subor over sufficient area to cause loss of joint Many situations of cartilage compromise are less than this, but they may still represent significant A recent study in people recorded chondral lesions in 1000 consecutive knee 2002). The lesions were classified recognized by the International Cartilage Society (ICRS). Chondral or osteochondral lesions 61 % of patients. Focal defects were found in the patients and, in these individuals, 61 % related .knee problem to a previous trauma. A conanterior cruciate injury was found in 26% of patients, respectively. Mean osteochondral 2.1 cm2 and the main defect was found 58%, patella in 11 %,lateral condyle 9%, trochlear in 6%, and tibia in 5% of patients. This study showed the pre-

of various parameters rather cartilage loss is also very common in the horse, associated with osteochondral chip fragments carpus (Figs 3.18 and 3.19). Less severe changes -in the fetlock in association with chip fracture 3.20-3-22) and in most instances of osteoarthritis to osteochondritis dissecans. In most joints, the

reported as a cause of lameness in eleven horses

et al 1997). Cartilagechange was revealedat

horses

wrinkled. and enfoldedcartilage, probe could be inserted into the addition to focal lesions,4 of the 11 horseshad generalizeddamageto cartilage on the medial femoralcondyle.Thesefocal cartilagelesionson the femoral condyleweredebrided.In 2 of 4 cases,debridementwas not possible;6 of 7 horseswith focal cartilagelesionstreatedby debridementrecoveredcompletelyand resumed previous activities.

The arthroscope allows better detection of articular cartilage damage than gross visual inspection at postmortem. Evensuperficialfibrillation can be recognizedwith and,

the arthroscope because of the combined effects of fluid suspension of the fibrillated collagen fibers. magnification. and transillumination (see Figs 3.18 and 3.20). Partial thickness and full thickness erosions represent more severe changes in the articular cartilage (Fig. 3.20-3.27). Disease involving the subchondral bone can also be recognized (Fig. 3.27 and 3.28). Other entities of cartilage damage. such as wear lines. are also recognized with the use of diagnostic arthroscopy (Fig&3.29 and 3.30). The significance of these changes is discussedin later chapters. The use of instruments to define the size of the lesion is also important. Methods of debriding cartilage defects are dealt with in Chapter 17.

Before the advent of arthroscopic S\lfgery. the first author (C. W.M.) performed diagnostic arthroscopy on joints to ascertain further the potential value of surgery (such as

instrumentation, care must be made to avoid contact with the cartilage.

Thermal chondroplasty with radiofrequency energy (RFE) has garnered widespread interest over recent years. There are two systemsavailable for clinical application: monopolar RFE and bipolar RFE (Lu et al 2002). Evaluation of both types of instrument on fresh osteochondral sections derived from patients undergoing partial or total knee replacement revealed that the depth of chondrocyte death in the monopolar RFE treatment group was significantly less than in the bipolar group. The authors pointed out that there could be significant chondrocyte death. The study also showed that it took at least 15 seconds for both bipolar and monopolar RFEto contour a 1 cm2 chondromalacic cartilage defect to a relatively smooth surface as shown by scanning electron microscopy (Lu et al2002). The investigators concluded that when thermal chondroplasty was applied clinically, it could result in various degrees of cartilage smoothness and potentially significant chondrocyte death.

The case for the use of lasers has also been made in joints (Palmer 1996). However, evaluation in clinical cases has revealed unwanted subchondral bone necrosis when an articular cartilage lesion is debrided.

Arthroscopic lavage and debridement Electrosurgery using high-frequency (HF) equipment (described in Chapter 2) has been used in both human and equine arthroscopy. One of the authors G.B.)has used it quite extensively in the horse. In humans. in addition to surgery on the synovial membrane and joint capsules,most arthroscopic meniscal surgeries are routinely done with the electroknife by at least one group (Kramer et al1992). When using such

The usefulnessof lavage in traumatic arthritis had been claimed prior to arthroscopic surgery becoming routine (Norrie 1975). The adjunctive lavage that goes with arthroscopicsurgeryhas alwaysbeenconsideredbeneficial. althoughthereis no clear documentationof this effect.However,the benefit of partial thickness chondrectomywhere there is cartilage fibrillation or minor exfoliation is more

3.31). The use of such debridement along , C C but controlled

of the rabbit patella with no evidence of in either the superficially or deeply shaved areas --& Shephard 1987). Ultrastructural studies after cartilage shavings question knee regeneration Schmid 1987). A

trial of arthroscopic surgery for osteoarthritis knee in humans caused considerablecontroversy 2002). The authors concludedthat the out-

lavage and debridement of osteoarthritic based on the severity of degeneration, continues to

books, attending seminars, and viewing video recordings.

"Hands on" training and practice, however, is essential.

Instruction and practice on cadavers is the most common way veterinary clinicians have improved their skills before embarking on clinical cases.Animal cadavers have also been used in the training for arthroscopy in humans (Voto et al 1986); however, artificial models have also been used successfully.More recently, there has been some development of equine artificial bones with joint capsules, but at present, cadaver material is inexpensive and readily available.

An interesting prospect for the future is the development of computer-based simulations of arthroscopic surgery for training and testing of arthroscopic skills (Medical Simulations. Inc.. Williamstown. MA). Use of simulators will increase particularly in learning human arthroscopic techniques. There will probably be lessuse in the horse where cadaver material is still more available.

horse.the authors feel that lavageis an important part of arthroscopic procedures by reducing

cartilage. A useful rule is that if articular is attached to subchondral bone it should be left Second look arthroscopies provide an opportunity to the amount of healing that has occurred in

References

3.32).

Bass AL. Lesions of the synovium. In: Casscells SW (ed.).

Arthroscopy. diagnostic and surgical practice. Philadelphia: Lea & Febiger: 1984.

Bots RAA. Boerbooms AMT. Indications for arthroscopy and monoand polyarticular arthritis. Am RheumDis 1979; 38: 337-340.

Butler JC. Andrews JR. The role of arthroscopic surgery in the evaluation of acute traumatic hemoarthrosis in the knee. Clin Orthop 1988; 228: 150-152.

Carson RW. Meniscectomy and other surgical techniques using the operating arthroscope. In: Casscells SW (ed.) Arthroscopy. diagnostic and surgical practice. Philadelphia: Lea & Febiger; 1984.

CasscellsSW:Lesions of the articular cartilage. In: CasscellsSW (ed.)

Arthroscopy. diagnostic and surgical practice. Philadelphia: Lea & Febiger; 1984.

Casscells SW. Commentary; the argument for early arthroscopic synovectomy in patients with severe hemophilia. Arthroscopy 1987; 3: 78-79.

Chow JC. Hantes M. Houle JB. Hypertrophy of the synovium in the anteromedial aspect of the knee joint following trauma: an unusual cause of knee pain. Arthroscopy 2002; 18: 735-740.

Crane J. Technique of diagnostic arthroscopy. In: CasscellsSW (ed.).

Arthroscopy. diagnostic and surgical practice. Philadelphia: Lea & Febiger; 1984.

Doyle-Jones PS. Sullins KE. Saunders GK. Synovial regeneration in the equine carpus after arthroscopic mechanical or carbon dioxide laser synovectomy. Vet Surg 2002; 31: 331-343.

Elsworth CP.Drabu K. Hodson J. Noble J. To probe or not to probe. In: Proceedings and Reports of Universities. Colleges. Councils.

Associations and Societies. J Bone Joint Surg (Br) 1986; 68: 842.

FizzieroL. ZizziF.Leyhissa R. Ferruzzi A. New methods in arthroscopy.

Preliminary investigation. Ann Rheum Dis. 1986; 45: 529-533.

Hague BA. Honnas CM. Simpson RB. Peloso JG. Evaluation of skin bacterial flora before and after aseptic preparation of clipped and non-clipped arthrocentesis sites in horses. Vet. Surg. 1997; 26:

121-125.

Highgenboten CL. Arthroscopic synovectomy Orthop Clin North Am 1982; 13: 399-405.

Hjelle K. Solheime Strand T. Muri R. Brittberg M. Articular cartilage defects in 1000 knee arthroscopies. Arthroscopy 2002; 18:

730-734.

Inoue K. Yoshio O. Nishioka K Satoh Y. Mikanagi K. Examination of the vascular network in the knee synovium and capsule with the magnifying arthroscope. Orthop. Clin. North Am. 1979; 10: 549-557.

JacksonRW. Arthroscopic surgery (current concepts review). J Bone Joint Surg (Am) 1983; 65: 416-420.

Jackson RW. Dietreichs C. The results of arthroscopic lavage and debridement of osteoarthritic knees based on the severity of degeneration: a 4 to 6 year symptomatic follow-up. Arthroscopy 2003; 19: 13-20.

Johnson 11. Letter to the editor. Arthroscopy 2002; 18: 683-687.

Jones D. Barber S. Doige C. Synovial fluid and clinical changes after arthroscopic partial synovectomy of the equine middle carpal joint. Vet. Surg. 1993; 22: 524-530.

JonesD. Barber S. Jack S. et aI. Morphological effects of arthroscopic partial synovectomy in horses. Vet. Surg. 1994; 23: 231-240.

Joyce KJ. Mankin HI. Caveatarthroscopes. Extra-articular lesions of bone simulating intra-articular pathology in the knee. J. Bone Joint Surg. (Am.) 1983;65: 289-292.

Kramer J. Rosenthal A. Moraldo M. Mueller KM. Electrosurgery in arthroscopy. Arthroscopy 1992; 8: 125-129.

Kinnard P. Levesque RY. The plica syndrome. A syndrome of controversy. Clin. Orthop. 1984; 183: 141-147.

Knezevic PF. Wruhs O. Arthroscopy in the horse. ox. pig. and dog.

Vet Med Rev 1977; 1: 53-63.

Limbird TJ. Dennis SC. Synovectomy and continuous passive motion (CPM)in hemophiliac patients. Arthroscopy 1987; 3: 74-77.

Lindblad S. Hedfors E. Intra-articular variation in synovitis. Local macroscopic and microscopic signs of inflammatory activity are significantly correlated. Arthritis Rheum. 1985; 2: 977-986.

Lu Y. Edwards RB. Nho S. et al. Thermal chondroplasty with bipolar and monopolar radiofrequency energy: effect of treatment time on chondrocyte death and surface contouring. Arthroscopy 2002; 18: 779-788.

Mcllwraith CWoThe use of arthroscopy. synovial fluid analysis and synovial membrane biopsy in the diagnosis of equine joint disease.In: Equine medicine and surgery. 3rd edn. Santa Barbara: American Veterinary Publications; 1983.

Mcllwraith CW:Tearing of the medial palmar intercarpal ligament in the equine midcarpal joint. Equine Vet J 1992; 24: 547-550.

Mcllwraith CW; FesslerJF. Arthroscopy in the diagnosis of equine joint disease.J Am Vet Med Assoc 1978; 172: 263-268.

May, Lees. Non-steroidal anti-inflammatory drugs. In: McIlwraith CW, Trotter GW (eds) Joint disease in the Horse. Philadelphia: WB. Saunders; 1996: 223-237.

Mitchell N, Shephard N. Effective patellar sharing in the rabbit.

J Orthop Res 1987; 5: 388-392.

Mori Y. Debris observed by arthroscopy of the knee. Orthop Clin NorthAm. 1979; 16: 579-593.

Moseley JB, O'Malley K, Petersen NJ, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engi J Med 2002; 347: 81-88.

Norrie RD. The treatment of joint disease by saline lavage.

Proceedings 21st Annual Meeting of the American Association of Equine Practitioners, Boston, MA, 1975; 91-94.

Nottage WM, Sprague NF, Auerbach BJ, Shahriarce H. The medial patellar plica syndrome. AmJ Sports Med 1983; 11: 211-214.

Noyes FR, Spievack ES. Extra-articular fluid dissection in tissues during arthroscopy. A report of clinical cases and a study of intra-articular and thigh pressures in cadavers. Am J Sports Med

1982;10:346-351.

O'Connor RL. Arthroscopy. Philadelphia: JBLippincott; 1977.

Palmer SE.Instrumentation and techniques for carbon dioxide lasers in equine general surgery. Vet Clin North Am Equine Pract 1996; 12: 397-414.

Palmer JL, Bertone AL, Malemud CJ, Mansour J. Changes in third carpal bone articular cartilage after synovectomy in normal and inflamed joints. Vet Surg 1998; 27: 321-330.

Parisien JS.The role of arthroscopy in the treatment of postoperative fibroarthrosis of the knee joint. Clin Orthop 1988; 229: 185-192.

Phillips MF, Vasseur PB, Gregory CR. Chlorhexidine diacetate versus povidone-iodine for pre-operative preparation of the skin: a prospective randomized comparison in dogs and cats. J Am Anim HospAssoc 1991; 27: 105-108.

PoeWing GG. Degenerative arthritis. Arthroscopy and research (editorial). Arthroscopy 2002; 18: 683-687.

Rosenberg A, Alatatry SD, Peterson AF. Safety and efficacy of the antiseptic cWorhexidine giuconate. Surg. Gynecol. Obstet. 1976; 143: 789-792.

Richmond JC, McGinty JB. Segmental arthroscopic resection of the hypertrophic mediopatellar plica Clin Orthop 1983; 178:

185-189.

Schmid A, Schmid F. Ultrastructural studies after arthroscopical cartilage shaving (abstract). J Arthroscopy 1987; 3: 137.

Schneider RK, Jenson p, Moore RM. Evaluation of cartilage lesions on the medial femoral condyle as a cause of lameness in horses: 11 cases(1988-1994). JAVMA 1997; 210: 1649-1652.

Stubbs WP, Bellah JR, Vermaas-Hekman D, Purich B, Kuplis PS. Chlorhexidine giuconate versus cWoroxylenol for pre-operative skin preparation in dogs. VetSurg 1996; 25: 487-494.

Tamurian RM, Spencer BE, Wojtys EM. The role of arthroscopic synovectomyin the management of hemarthrosis and hemophilia patients: Financial prospective. Arthroscopy 2002; 18: 789-794.

Theoret C, Barber S,Moyana T, et al. Repair and function of synovium after total arthroscopic synovectomy of the equine antebrachiocarpal joint. Vet Surg 1994; 23: 418.

Voto SJ,Clark RN, Zuelzer WA. ArthrQscopic training using pig knee joints, Clin. Orthop 1988; 226: 134-137.

Walmsley Jp. Arthroscopic surgery of the femorotibial joint. Clin TechEquine Pract 2002; 1: 226-233 Walmsley JP,Phillips TJ and Townsend HCG Meniscal tears in horses; an evaluation of clinical signs and arthroscope treatment of 80 cases.Equine Vet J 2003; 35: 402-406.

Wan Py, Blackford JT,Bemis DA, et aI. Evaluation of surgical scrub methods for large animal surgeons. Vet Surg 1997; 26: 382-385.

Williamson DM, Copeland SA. Suturing arthroscopy wounds: brief report. J Bone Joint Surg (Br) 1988; 70: 146.

middle carpal (intercarpal) or antesurgical procedures and initially served portal for eachjoint. Using two dorsal of movement because of reduced soft tissue tension around the arthroscope and a reduced tendency to slip out of the joint when examining areas close to the arthroscopic portal surgery and the earlier return to exercise, (Martin & McIlwraith 1985). Two portals are also useful if surgery is going to be performed on both sides of a joint. In addition, villi in the area of arthroscopic entry will rather than continuing training sometimes compromise visualization in that area of the joint. medication to the detriment of joints and Examination through one portal has been greatly facilitated by the development of the angled-view arthroscope. It is important always to evaluate the whole joint before was the commencing surgical manipulation. For example, if the presurgical diagnosis is that there is fragmentation of the distal radial carpal bone, the arthroscope is placed dorsolaterally arthroscopy in the carpal joints as well as a and once a clear view is obtained, a quick examination of all of case selection,adjunctive management,and the potential areas for injury can be made. If the only can be anticipated. In most instances, the arthroscopic finding is the chip on the distal radial carpal are common to all joints, but they are bone, then this is removed through a dorsomedial instrument of arthroscopic surgery.The key to successful portal. On the other hand, if the examination also reveals a fragment on the distal intermediate carpal bone, then after is attention to detail and authors will removal of the radial carpal chip, the arthroscope and throughout the small featuresthat are instrument are swapped as the fragment on the intermediate carpal bone can be more conveniently visualized and

1983. 1984. Mcilwraith et al

removed using a dorsomedial arthroscope portal and a

and prognostic procedure (Mcllwraith & ~.. Mcllwraith 1991) as well as for the surgical of articular injuries. The general role of the arthroscopic anatomy of the carpal joints is

dorsolateral instrument portal.

It is also possible to insert the arthroscope into the lateral palmar outpouchings of both middle carpal and antebrachiocarpal joints as well as medial outpouching of the antebrachiocarpal joint. The most common indication for surgery is removal of fragments from the palmar aspect of the joints, but this approach has been used to retrieve a broken piece of instrument (McIlwraith 1990, Dabareiner et al 1993, Wilke et aI2001).

Due to the anatomic differences, examination and surgery of the middle carpal joint is easier than the antebrachiocarpal joint: whereas the middle carpal joint tends to open as a hinge, the antebrachiocarpal joint is shaped so that its movement is both rotational and gliding. The gliding movement of the joint tends to tuck the dorsal edge of the

radius beneath the joint capsule and the joint capsule attaches closely to the proximal marginal edge of the inter-

mediate and radial carpal bones. In addition, the convex curvature of the distal medial and lateral aspectsof the radius make access to the medial and lateral joint angles slightly more difficult. The narrow angle between the radius and the proximal radial carpal bone in the medial aspect of the joint can also make instrument manipulation more difficult in this area.

The general technique for introducing the arthroscope into the joint was described in Chapter 3. Two arthroscopic portals are useful for either the middle carpal or antebrachiocarpal joint: dorsolateral and dorsomedial. The lateral approach is better for visualizing the medial aspect of the joint and the medial entry is better for seeing the lateral aspect. For example, when the operation involves a lesion on the medial half of the joint, the instrument is introduced through the medial portal and the arthroscope enters through the lateral portal and vice versa. Thorough exploration of the carpal joints is therefore possible by using both lateral and medial entries.

Although arthroscopy in the carpal joints can be performed with the animal in lateral or dorsal recumbency, the latter has greater versatility. When switching sides with the arthroscope (as is usually necessary if lesions are on both sides of the joint), rolling of the horse or doing surgery "upside down" is necessary if it has been placed in lateral recumbency. Some surgeons have suggested that the dorsal recumbency position causes tightening of the joint capsule over the dorsal face of the carpus, and that a loose fragment can be located more predictably in the lateral or medial cul-de-sac of the joint when the animal is in lateral recumbency. However,the authors have not found these to be limiting factors and in reviewing arthroscopic surgical procedures performed on 1000 carpal joints in 591 horses by the first author (C.W.M.) 45% were operated bilaterally. For this reason, all descriptions of both diagnostic and surgical arthroscopy in the carpal joints are presented as in dorsal recumbency, i.e. proximal is below and distal is above. This position is also taught in the authors' laboratory classes.

Learning arthroscopic anatomy in this manner is an important prerequisite to performing arthroscopic surgery. Positioning and preparation of the carpus are illustrated in Chapter 3.

Initially, the most important aspect is to learn the specific landmarks that allow orientation within the carpal joints and these are described in the examination techniques below.

Arthroscopic examination middle carpal (intercarpal)

of the joint

The choice of arthroscopic portal depends on the primary area the surgeon wishes to examine. The lateral portal is halfway between the extensor carpi radialis tendon and the common digital extensor tendon and midway between the two rows of carpal bones with the joint flexed at approximately 70째. The medial arthroscopic portal is made sufficiently medial to the extensor carpi radialis tendon to avoid its tendon sheath. The skin incision for these portals is made before distention of the joint to avoid damage to the tendon

sheaths. By contrast, the periarticular anatomy of fetlock, tarsocrural, and femoropatellar joints allows r liberties with placement of the portals, and prior j distention is an assetto localization of the correct portal After joint distention, the arthroscope is inserted int( joint as described in Chapter 3. Examination with arthroscope inserted through the lateral portal comme with the visual field in the medial aspect of the middle c~ joint (Fig. 4.1). The dorsomedial intercarpal ligaIJ extending from the dorsal medial aspect of the radial c~ bone to the medial joint capsule is commonly obse (Fig. 4.1C). This dorsomedialligament has been previc describedas a synovial plica (Mcllwraith 1990). Withdral the arthroscope and angling the lens proximad aU inspection of the articular surface and dorsal margin oj radial carpal bone (Fig. 4.2). Continued withdrawal of arthroscope allows visualization of the junction betweer radial and intermediate carpal bones (Fig. 4.3). Rotati( the arthroscope allows inspection of the palmar aspect 0 joint and the articulation between the radial, intermed and third carpal bones (Fig. 4.3C). Also in this view i! synovial fossain the medial palmar aspect of the third c~ bone and the medial palmar intercarpal ligament (MP This fossa is normal; it is a site of communication witt palmar pouch of the middle carpal joint, and may be a sit lodgment of small particles that break free during art scopic surgery. During examination of the articular mill of the radial and intermediate carpal bones, the joint caI attachment is some distance from the articular rim, all01 excellent visualization of the dorsal margins of these bol The arthroscope is advanced slightly and the arthros( lens is angled distad to visualize the second carpal bone the medial portion of the third carpal bone (Fig. 4.4). S withdrawal allows additional visualization of the remai dorsal margin and body of the radial facets of the third c~ bone (Fig. 4.5). If the arthroscope is then moved so tha tip sweepslaterad and the eyepiecemediad, the intermel facet of the third carpal bone and the more central aspe the joint can be visualized (Fig. 4.6). By continuing motion, the lateral aspect of the intercarpal joint ca visualized. (These areas are illustrated here, using the m arthroscopic approach.)

When the arthroscope is inserted through the d( medial portal the tip is passedto the most lateral aspect 0 joint where the angle formed by the ulnar and fourth c~ bones is visualized (Fig. 4.7). Withdrawal of the arthros permits evaluation of the articular surfaces of the ulnar intermediate carpal bones as far as the junction of the I with the radial carpal bone (Fig. 4.8). A similar mane with the lens directed distad and palmad allows examin. of the fourth carpal bone (Fig. 4.9) and the lateral half 0 third carpal bone (Fig.4.10). There is also a synovial plica the transverse dorsal intercarpal ligament at the juncti( the third and fourth carpal bones (Fig. 4.10C).

Additional maneuvers may be necessary to augmen examination. For example, for detailed examination oj dorsal synovial recessesbeyond the articular surfaces, tt of the arthroscope may be placed between the dorsal sur

,/

Diagnostic Arthroscopy of the Carpal joir

,/ ./

'"/'

R

Fig. 4.2 Distal radial carpal bone (R). (A) Diagram of arthroscope position and visual field. (8) Arthroscopic view; 2. Second carp, bone; 3,Third carpal bone L, medial palmar intercarpal ligamer 4, fourth carpal bone. I, Intermediate carpal bone; U, ulnar carpal bone; CD, common digital extensor extensor carpi radialis tendon.

tendon;

ECR,

of the carpal bones and the capsular reflections. Synovial 1 in the dorsomedial and dorsolateral aspects of the joint n obscure the view of some parts of the dorsal rims of the bol despite joint distention. In these cases,use of an instrum, to push them out of the way is appropriate.

Fig. 4.1 Medial aspect of the middle

carpal joint.

(A) Diagram of

arthroscope position. (B) Arthroscopic view. R, radial carpal bone; 2, second carpal bone; 3, third carpal bone; CD, common digital extensor tendon; ECR, extensor carpi radialis tendon. (C) Closer view of field in B. P, Normal synovial plica (dorsomedial

intercarpal

ligament).

Arthroscopic examination of the antebrachlocarpal (radiocarpal) joint ~

Arthroscopic examination of the antebrachiocarpal joint conducted in the same fashion as for the middle carpal job except that the flexion angle in the carpus is decreased(leg extended to 120-130째). The leg is straightened to facilitc maximal visualization of the dorsal aspectsof the radial aJ

,,19 Diagnostic and Surgical Arthroscopy of the Carpal joints

Fig.4.3 Junction of the radial and intermediate carpal bones.

(A) Diagram of arthroscope position and visual field. Dorsal (B) and palmar (C) arthroscopic views. R, radial carpal bone; I, intermediate carpal bone; medial palmar intercarpal ligament.

Fig.4.4

Second carpal bone (2) and the medial aspect of the third car~ bone (3). (A) Diagram of arthroscope position and visual fie (B) Arthroscopic view. (C) A more palmar view of the third carpal bone. including the fossa at the medial palmar aspect I the junction of the second (2) and third (3) carpal bones as well as the medial palmar intercarpal ligament (L). Also note the median ridge of the third carpal bone dividing radial and

intPrmprJi"tPf"rpt.

1111_i, --

joints

A'

R -

Fig.4.T

Ulnar (U) and intermediate (I) carpal bones. (A) Diagram of a~roscope Intermediate facet of the third (3) carpal bone.

Fig. 4.8 Distal articular surface of the intermediate carpal bone (I). (A) Diagram of arthroscope position and visual field. (B and C) Arthroscopic views. Note the edge of the radial carpal bone (R) and synovial plica (P) between intermediate and radial carpal bones. $, synovial membrane.

position and visual field. (8) Arthroscopic view.

A

carpal bones and distal radius (and this is As in the middle carpal joint. the dorsolateral arthroscopic Cis halfway between the common digital extensor and extensor carpal radialis tendons. and the dorsomedial portal is medial to the extensor carpi radialis tendon. The choice of portal depends on the area of primary interest with respect to visualization and (usually) surgical intervention.

The site of the medial portal is at the center of a triangle formed by the extensor carpi radialis. the distal rim of the radius. and the dorsal rim of the radial carpal bone. This portal area is in the smallest space in either of the carpal joints and because of marked narrowing of the joint. the tight nature of the capsular attachments. and the convex nature of the articulation. the surgeon has to be careful when inserting the arthroscope to avoid excoriation of the articular

cartilage.

Arthroscopic examinationof the antebrachiocarpaljoint will be described,beginning with the arthroscopeinserted through the lateral portal and visualizationof the medialside of the joint. The distalradius and the proximal radial carpal bone form the medialjoint angle.Rotationof the lensdistad allowscloseinspectionof the medialportion of the proximal articular surfaceof the articular surfaceof the radial carpal bone (Fig. 4.11). Withdrawing the arthroscopic slightly allows examinationof the entire proximalradial carpalbone to the levelof its junction with the intermediatecarpalbone (Fig.4.12).

The arthroscopeis then rotated so that the lens is angled proximadto examinethe medialaspectof the distal articular surfaceof the radius (Figs4.13 and 4.14}. As in the middle carpaljoint. the lateral aspectof the joint can be examined through the samelateral arthroscopicportal by moving the

eyepiece mediad and the tip laterad and then rotating t scope appropriately. For purposes of palpation and surge however, examination of the lateral aspect of the joint is b performed through a medial arthroscope portal.

By switching to a medial portal, the most lateral aspec the antebrachiocarpal joint is examined. The arthroscoP( rotated wit!1 the lens pointed distad to visualize the proxin articular surface of the ulnar carpal bone and the late aspect of the proximal articular surface of the intermedi: carpal bone (Fig. 4.15). Withdrawing the arthroscope allo examination of the entire proximal surface of the int mediate carpal bone (Fig. 4.16), and tilting of the arthrosco tip distad allows inspection of the junction of the intermedi and radial carpal bones (Fig. 4.17).

By returning the tip of the arthroscope to the late aspect of the joint and rotating the arthroscope so that 1

lens is directed proximad, the lateral aspect of the radius can be examined (Figs 4.18 and 4.19). On a lateral view, the articular groove between the lateral s process and the distal epiphysis of the radius (fused i adult) can be seen; in a young horse, it can be seen completely separated fissure. With withdrawal and roti the entire lateral half of the joint can be scanned. inCll the midsagittal ridge of the distal radius (Fig. 4.19C). Gr in the central portion of the radius are commonly obs and are considered normal.

As mentioned with the middle carpal joint. addil maneuvers may be necessary in some joints to fac complete examination of the dorsal articular sur including use of instruments to retract the villi and chaJ the flexion angle of the joint.

examination of the palmar middle carpal and joints

the antebrachiocarpaljoint, the swelling is proximal the perceivedjoint line. A No. 11 bladeis then usedto cre a portal and the arthroscopecan be inserted.Figures4.2 and D showarthroscopicviews of the lateral aspectinto palmar aspectof the middle carpal and antebrachioca both middle carpal and antebrachiocarpal joint. respectively. . surgery is removal of frag-

been used to retrieve a broken piece of instrument 1990. 1996, Dabareineret al1993, Wilke et al The position for placing the arthroscope in the lateral

front. swelling will be revealed.In the caseof

Maintenance

of joint distention

The arthroscopist must direct the operation to ensure 1 maintenance of joint distention. This is not usually a probl at the time of initial examination when the only patent pOI is that for the arthroscope. If an egress cannula is placed the other side,varying the closure of the cannula still ea~ controls distention. However, once there is a patent instl

ment portal and instrument manipulations have b performed. some flow of fluid from the joint is inevitable this requires an increased rate of fluid input to main! distention. Once an instrument portal is losing flui( number of aspectsare important to avoid the developmer subcutaneous fluid accumulation. Placing a finger over skin incision to stop fluid flow will only promote filling in subcutaneous plane. Similarly. pumping fluid when a ch being pulled through the subcutaneous tissue and skin may block the skin outlet and cause fluid to collect 1 cutaneously. Fluid ingress should also be minimized dill instrument manipulations because these can facilitate opening up of the subcutaneous tissue planes. again allO\l fluid extravasation.

Another problem. once an instrument portal is mad, that if the joint must be re-entered with the arthroscope; I joint distention is present to facilitate re-entry. This is D commonly encountered with biaxial fragmentation. me chips requiring a lateral arthroscope and medial instrun portals and lateral chips requiring medial arthroscope lateral instrument portals. The reinsertion of the arthros( requires experience and care to avoid iatrogenic damag the cartilage. The arthroscopic sheath and conical obtur are manipulated carefully back into the joint. the arthros( is inserted. and the joint is redistended. The use of "switcl sticks" in human arthroscopy to facilitate these maneu has been described Gohnson 1986). but the authors be! these are not necessary in the equine carpus. Removing arthroscope from one portal and placing it in another 1 consequent escape of fluid is usually associated with S bleeding and the joint will need to be flushed be visualization is satisfactory.

Arthroscopic Surgery for Removal of Osteochondral Chip Fragments Current status and advantages of arthroscopic surgery

The feasibility of returning horses to racing more quj after arthroscopic removal of carpal fragments brol arthroscopic surgery into strong demand. Some of advantages of arthroscopic surgery have been simplified overstated. but it is now universally adopted for treatmel carpal fragmentation.

On the basis of a review of 1000 arthroscopic proced for removal of carpal chip fragments (Mcllwraith et al19 and continued experiencesince then. a number ofadvant can be listed. Many of these are applicable also to other jo

1. Visualization is superior to that with arthrotom improves diagnostic accuracy and. consequently. r definite treatment.

to periarticular tissuesand the joint

only is the cosmetic result excellent but also , to overall joint function is minimized. trauma to the soft tissues is also significant to the articular cartilage, which may undergo deterioration secondary to soft tissue

the joint (with elimination of on multiple joints can occur in the same

race successfullyin the same or a higher class. A lowering in class. however.is more typical for racehorsesafterarthrotomy.

6. Horses return to training earlier and thus less fitness a musculoskeletaladaptation are lost. Thesefactors contribl to an earlier return to racing.

Problems and poor results have been encountered, and ; addressed at appropriate points throughout the chap1 Many small problems can be avoided by technique chang and one of the main purposes of this textbook is to stl the beginning arthroscopist past some of these pitfa Unfortunately, poor results can often be related to inadequ; ability, experience,or practice. To be able to operate effectiv on any carpal chip lesion using arthroscopic surgery i~ reality, but it requires skill and practice. Above all, it a requires a disciplined systematic approach. The techniql

presented in this chapter are not the sole means

performing surgery; however, whatever changes the surge makes, he or she should still use a systematic approach

every case.The approachesdescribedhave worked for the authors and also for the veterinarianswho haveundertaken the arthroscopictraining coursesthat the authorshaveconducted worldwide (Mcllwraith 2002). Modification and refinement of techniquescontinue and it is the authors' philosophyto disseminatethis information through training coursesand publications.

Presurgical

information

As with any surgical candidate, as complete a history as possible is obtained. This history is often difficult with racehorses, and duration or time that the chip fracture has been present is often not clear. Treatment history frequently is uncertain, particularly with reference to intra-articular corticosteroid medication, but the authors feellessconcerned with operating on horses soon after corticosteroid administration than was the case with arthrotomy.

In most cases, the horses exhibit mild to moderate lameness. Severe lameness is usually associated with major articular damage. Radiographs should always be taken of both legs; bilateral and/or clinically silent lesions are common and these frequently are in the same location in both limbs. There is also a lack of correlation between radiographic and arthroscopic findings, which is usually reflected in arthroscopic findings that are more severe than those suggested by radiographic examination (Mcllwraith et al 1987). The same disparity was noted in human osteoarthritic knees (Lysholm et al198 7). Specific problems in this regard with chip fractures at various sites in the carpal joint are addressedin the appropriate section.

Relevant pathobiology The carpal and fetlock joints are the most common instances where traumatically induced osteochondral chip fragmentation occurs. Although chip fragments have been frequently considered as acute injuries and present with acute clinical signs, it is now recognized that many of these fragments come from pathologic joint margins, previously altered by subchondral bone disease (Pool & Meagher 1990), and more recent work in the first author's (C.W.M.) laboratory has documented the development of microdamage in association with exercise.

The microdamage manifestedas a combination of microcracks, diffuse microdamage, cell death, and subchondral bone sclerosis (Kawcak et al 2000, 2001) and it is suggested that such changes lead to the clinical osteochondral fragmentation seenin the carpal and the fetlock joints.

It has been proposed that chip fractures of the joint margins in the carpus can arise from either fragmentation of the original tissue of the joint margin (previously altered by disease as mentioned above), or within the base of periarticular osteophytes forming in joints as part of the osteoarthritis syndrome. Experience with arthroscopic surgery of carpal fragmentation suggests that both mechanisms occur and for this reason, the authors now prefer using the term

"fragment" rather than "fracture" for the osteochol pieces that are created. Such fragments almost invar occur as a consequence of microdamage and thus cou classified as pathologic fractures. In some instances the II appears as a "fresh" fracture line through an artil surface with no visible subchondral change, but in instances subchondral disease is seen arthroscopically certainly exists at the microscopic level.

Osteochondral fragmentation has direct physical effec the joint because of the loss of the smooth articular su and indirect effects due to the release of articular car1 and bone debris, which leads in turn to synovitis. S compromise of the articular surfaces leads to instabili does tearing of fibrous joint capsule and ligaments. synovial membrane responds directly to mechanical tr. and indirectly to injury elsewhere in the joint. High i articular pressures generated by synovial effusion promises the microstability, and the normal, slightly ne~ atmospheric pressure in joints is lost. Damage to synovio also liberates matrix metalloproteinases, aggrecal prostaglandins, free radicals and cytokines (princi interleukin 1 or 11-1), which could lead to articular carl degeneration (McIlwraith 1982). Chronic articular i results in fibrosis of the joint capsule and consequent II motion. Arthrofibrosis is recognized as an important prc in humans. The cause is still unknown, but the use of s arthroscopic techniques is considered critical in minimization of arthrofibrosis in man (Finerman & ~

1992).

The primary indication for surgical treatment of c chondral fragments in the carpus is to minimize arti insult and to prevent development of osteoarthritis (McIlwraith & Bramlage 1996). It should be recognizec a joint is rarely returned to "normal" and that signiJ defectscan potentially lead to some degree of microinsta and progression to osteoarthritis. Nonetheless,relative j amount of damage, the athletic horse can come back t( level performance despite some damage.

Location of intra-articular fragments

Table 4.1 illustrates the incidence and location of ( chondral fragments in the dorsal carpal joints as report the first author (C.WM.) in a series of 1000 carpal" (Mcllwraith et al 1987). The affected joints were in horses, of which 220 were racing Thoroughbreds. 349 racing Quarter Horses. 5 were racing Appaloosas,and 6 racing Standardbreds. The others included 2 barrel-r Quarter Horses, 3 roping Quarter Horses, and 6 other I

horses.

Of the 591 horses. 278 horses were 2 years old, 196 3 years old, 52 (55%) were 4 years old, 47 were 5 ye, older, and 18 did not have their age documented. In horses, osteochondral fragments were noted in one ca whereas 265 (45%) horses had bilateral lesions. Arthro~ surgery was performed on a significantly greater numl joints per horse in Quarter Horses compared with Thor( breds. Specifically,in the Thoroughbreds, operations inv

Arthroscopic Surgery for Removal of Osteochondral Chip Fragmem 1 joint in 142 horses. 2 joint in 70 horses, 3 joints in 14 horses,and 4 joints in 1 horse. In the Quarter Horses,1 joint in 144 horses. 2 joints in 130 horses, 3 joints in 46 horses. and 4 joints in 30 horses were affected (Mcllwraith et al 1987).

Unpublisheddata from a European author (I.M. \1\7:) suggests a similar distribution of lesions, although the relative frequency of fragments from the proximal third carpal bone and distal intermediate carpal bone are reversed. Readersare also cautioned that lesion distribution may vary in other practicesin which breed/use manipulation is different.

General technique for carpal chip removal As discussed briefly in Chapter 3, surgery is performed by using the technique of triangulation (see Figs 4.21-4.23).

Specificdetails on the arthroscopic and instrument approaches for operations involving chip fractures in different locations

Distribution

540 intercarpal

of carpal chip fragments.

(midcarpal)

joints

Distal radial carpal bone Distal intermediate carpal bone Proximal third carpal bone Total

475 106

60 641

460 Radiocarpal (antebrachiocarpal) Distal lateral radius Distal medial radius Proximal radial carpal bone Proximal intermediate carpal bone Proximal ulnar carpal bone Total Source:

Mcllwraith

joints 167 96 168

273 1 705

Fig. 4.22 Removal of a carpal chip fragment from the intercarpal joint using Ferris-Smith cup rongeurs: (A) grasping of the fragment (B) removal of fragment through the skin.

et al1987

with a closed egress needle (A) and a probe

(B) to evaluate the mobility

of a carpal chip fragment

are included in subsequentsections,but the generalrule is that for a fragment on the medial side of the joint, the arthroscope passes through the lateral portal and the instrumentsenterthrough a medialportal. Forlesionson the lateral side of the joint, the arthroscopeis placedthrough a medial portal and instrumentsthrough a lateralportal.

The basicprotocolfor surgeryof all carpal fragmentation is similar. A diagnosticarthroscopicexaminationis always performedfirst. The egressis openedto flush the joint if visualizationis lessthan optimal. Whenthe view is clear,the egressis closedand can then be used to palpate areas of fragmentation(seeFig.4.21A). Alternatively,a probecanbe used (seeFig. 4.21B), but the egressworks well for preliminary palpationand savesan extra instrumentpassage.

The egresscannula is then removedand the instrument portal through the joint capsuleusually closes,at leastuntil the time that a larger instrument (which increasesthe diameterof the portal) is used.If the fragmentis freshand mobile on palpation,immediateinsertionof graspingforceps is appropriate.The fragmentis grasped,and the forcepsare rotatedto freethe chip of softtissueattachments(if theseare

sIgnmCarn), oelore II ISremovea ~seeng, ':I:.L.L.). l'ems-~ arthroscopic rongeurs are most commonly employed. j size is chosen to enclose the fragment as complete possibleto minimize loss,as this is brought through the capsule, subcutis, or skin (see Fig. 4.22). Rongeurs w jaw size of 4 x 10 mm are suitable for most fragmen1 locations. Tearing a fragment loose from its soft t attachment by twisting the forceps may not seeI aesthetically pleasing or relate well to basic sur principles, as sharp severance of the attachments, I: minimizes the risk of creating a free-floating fragment.

If attachments at the fracture line are strong all( fragment cannot be displaced with initial probing, a : Synthes or Mcllwraith-Scanlan elevator is used to sep the chip from the parent bone (seeFig. 4.23). Also, whe chip has considerable fibrous capsular insertions, as typ occurs with fragmentation of the distal lateral radius elevator or a fixed blade arthroscopy knife can also be us separate these attachments before removal of the frag with forceps.

Although rarely necessary,when a chip is long-star and bony reattachment is developing or has develope osteotome may be used to free the fragment from the p, bone. The osteotome is positioned through the instru portal and is placed in the old fracture line by the sur using arthroscopic visualization. An assistant strike: osteotome according to the surgeon's direction. A I osteotome or an elevator and hammering is preferred sharp osteotome by some surgeons as it is thought to b likely to make a new fracture line through normal bon Foerner pers comm 1984).

In many cases of chronic fragmentation, Ferris-5 rongeurs are used to remove the fragments directly wi1 prior separation. This usually works well, but attemr remove normal bone in this fashion may break the pin lir of the forcep blades. If there is extensive bone prolifer. the use of a motorized burr for debridement of lesions c: considered, but such indications are rare, and the val surgery in such casesis always questionable.

Once fragments are removed, the defect is debrided. step is discussedin detail later and is usually performed rongeurs and curettes (Fig. 4.24). Other osseous defect: may be debrided at this time. Kissing lesions are evalu but when they are of partial thickness, they usually ar debrided.

The joint is then flushed by opening the egress car and manipulating the tip in the area of the lesion (Fig. 4 The egress can also be used to rub off small tags of carl and bone. Placement of the larger, 4.5-mm egress car should follow, to remove larger fragments (Fig. 4.25). Su may be appliedto this cannula, but it is not routinely perfo in the carpus. Lavage should continue until the joi macroscopically cleared of debris. Occasionally, a frag migrates away from the fracture site and is either free flo or attached to synovial membrane (Fig. 4.26). In such ( it is removed with forceps.

At the completion of irrigation of the joint, the porta closed by using skin sutures only (Fig. 4.27). The incisior

Arthroscopic Surgery for Removal of Osteochondral Chip Fragmel

(A) external

view. (8) arthroscopic

Fig. 4.25 Arthroscopic

view of flushing debris from central area of middle carpal joint. (A) External view. (8) Arthroscopic

Fig. 4.26 Free fragment in the joint (A) and adhered to synovial membrane

(8).

view.

view.

covered with a sterile nonadhesive dressing and adhesive gauze, before an elastic or padded bandage is applied (Fig,4.28).

The size of fragments that can be removed arthroscopically has no limit. The skin incision has to be extended in some instances but additional incising of the joint capsule is not usually required. Failure to lengthen the skin incision can result in the fragment being lost or trapped in the subcutis. In exceptional cases,a single absorbable suture may be placed in the joint capsule after removal of a particularly large fragment.

Postoperative or intraoperative radiographs to ensure removal of all fragments are recommended. Although it is important that no loose fragments remain in the joint, some osseous densities in the radiographs may not be candidates for removal. In addition, osteophytes away from the articular margin and within the joint capsule (or enthesophytes)are of less concern. For any fragment or spur completely buried within the joint capsule, dissection out of the capsule is unnecessary and is excessively traumatic. The surgeon should be certain that such fragments are indeed outside the joint cavity and it is important to recognize that one should treat the patient rather than the radiograph. Veterinarians involved in obtaining follow-up radiographs of arthroscopic surgery patients should also be aware of this principle before proclaiming to the client or the trainer that "a chip has been left in the joint."

If radiographs reveal evidence of a fragment remaining in the joint, further arthroscopic examination is performed.

When a fragment has lodged subcutaneously, the area is palpated and swept with a pair of hemostats. When the fragment is located, it is brought to the skin incision, and

grasped. Any soft tissue attachments to the fragment ill severed while the fragment is held with forceps or a tOW clamp. Occasionally, insertion of the arthroscope int subcutaneous pockets. with either no or little fluid flow, ca assistin location of fragments.

Specific sites of carpal chip fragmentation and their treatment Dorsodistal radial carpal bone

The dorsodistal aspect of the radial carpal bone is the mo common site for carpal fragmentation. It is the easie operative site in the carpus, but has the greatest range I pathologic change seen at arthroscopy relative to what seen on radiographs. The arthroscope is placed through tl lateral portal with the lens-angled proximad and the instrl ments are brought through the medial portal (Fig. 4.29 Fragmentation can occur anywhere along the distal dors margin of the radial carpal bone.

and flexed lateromedialviews and dorsolaterallateromedialradiographic view has beenusedto boneloss.it is

at this site is particularly poor. In addition. chip have been found on the distal radial carpal bone not visualizedon any of the radiographicviews. thesefragmentsare on the dorsolateralcorner of projectedin As with any chip fractures, the size of distal radial carpal lesion varies widely. The smallest lesions manifest in the distal dorsal margin (Figs 4.31 and 4.32), examined arthroscopically, such lesions usually .-,,.'. '.31Band

Larger osteochondral fragments are easily identified ."(Figs 4.33 and 4.34). At arthroscopy, the 33). There is also particularly palmar to the fragmentation (Fig. 4.33). Grading degree of articular cartilage damage is discussed more fully in a subsequentsection.

Radiographs also do not often predict accurately the extent of bone fragmentation in the distal radial carpal bone. Both the amount of cartilage degeneration that extends back from the edge of the defect and the amount of subchondral bone

loss vary considerably. Loss of bone is typically related t< finding soft defective bone at surgery. which requires debride ment. Such changes in the distal radial carpal bone can bt severe when the radiographic changes appear rather mild Often the degree of clinical compromise (lameness an, synovial effusion) is a better indicator of the state of the join1 than are the radiographs. The presence of bloody or brown synovial fluid on initial entry into the joint is also usually a

(Fig. 4.37). After removal of fragmentation, detac] cartilage is removed and exposed subchondral bone debri to healthy margins (Fig. 4.38).

The prognosis is related to the amount of cartilage ani bone loss and decreases with loss of bone along the en dorsal margin of the bone. The relationship between progn. and articular cartilage loss is more difficult to pred particularly in racing Quarter Horses where the first aut.

(C.WM.) has had horses with complete loss of articl cartilage from the distal radial carpal bone that have cc back and won at Stakes level (see Fig. 4.37). Actual figu based on follow-up with these cases are presented in a s

sequentsection.

Fragmentation frequently will be found adjacent to medial plica, which has also beendescribedas the medial dol intercarpal ligament (MDIC) (Wright 1995). This origin~ on the distal dorsal medial aspect of the radial carpal bc and has an oblique course to insert on the medial joint caps (Selway 1991). On arthroscopic examination, its degret confluence with the joint capsule is quite varied and ligament cannot always be identified. The MDIC ligam may function as part of the medial collateral ligament, re carpal bone displacement during weight bearing, or assisl production of "closed-pact" position in preparation loading (Wright 1995). It has beentheorized that the ligam can act like a "leather hinge" on a box, becoming entrap] between the second and third carpal and radial carpal bol when the joint is extended. This can lead to "rocking" of carpal bones and, thus, osteochondral degeneration wit] the middle carpal joint (Selway 1991). Using this ratioru Selway (1991) recommendedremoval of the protruding MI ligament to a level of confluence with the joint capsule.1 authors believe that current evidence does not supporl primary etiological role for the MDIC ligament in fragm( tation and therefore do not practice or recommend prop} lactic desmotomy. There is no doubt that the origin of t ligament is commonly involved in degeneration and fragmt tation of the dorsodistal medial aspect of the radial car) bone, but all evidence suggests that this is not causati Removal of fragments attached to the DMIC ligament ~ result in tearing and frayed tissue that can be debrided w basket forceps or a motorized synovial resector (Fig. 4.39).

Dorsodistal intermediate carpal bone

strong indicator of severe damage within the joint. In some instances, radiographs provide an indication of marked bone loss in association with chip fractures (Fig. 4.35), but usually the bone loss is more than is anticipated (Fig. 4.36). In either case, when loss of bone is marked, there is loss of joint congruity and, potentially, instability. In instances where bone remains but there is Grade 3 articular cartilage loss, radiographs do not predict the amount of damage at all

Chip fractures of the dorsodistal aspect of the intermedi, carpal bone occur most commonly on the medial facet. L commonly. fragments are located lateral to the medi divisional ridge on the distal articular surface where they c be radiographically "silent". Osteophytosis may also be Sf at this site. The pre-surgical radiographs that most frequen demonstrate fragmentation are the flexed lateromedial (L and the dorsomedial-palmarolateral (DMPLO) projectic (Fig. 4.40).

The approach for operating on the distal intermedi. carpal bone lesions is illustrated in Figure 4.41. T arthroscope is placed through the medial portal and t instrument enters through the lateral portal. Visualizatior

usually good (Fig. 4.42), but the instrument angle is no convenient for these lesions as for those on the distal ra carpal bone. Becausethe distance from the instrument po to the lesion is often small, opening forceps inside the job sometimesdifficult. This can be aided (if fragmentation at site is predicted preoperatively) by making the lateral po closer to the distal row of carpal bones. Lesions on the n medial portion of the intermediate carpal bone can be n difficult to visualize completely because differeIJ movement between radial and intermediate carpal b( when the carpus is flexed produces a "step" in the mil

carpal joint.

Lesions of the distal intermediate carpal bone vary in : but most are small and have relatively little associ; degeneration. In these cases,the prognosis is good. Exten loss of cartilage and bone can occur but this is far common than on the distal radial carpal bone and is usu more predictable on radiographs.

During operations involving an intermediate carpal t lesion, even if it is the only fragment demonstrated ra graphically, the surgeon should evaluate the distal r.

Fig. 4.38 Arthroscopic views before (A) and after (8 and C) debridement of bone loss from distal radial carpal bone.

There is bone loss along the entire width of the radial carpal bone.

in other locations in the middle carpal joint frequently in the center of the joint and are 10 the extensor carpi radialis tendon. In additiol capsule is closer to the articular margin than is tI the radial and intermediate carpal bones. Becal factors, joint distention may not be as effective clear visualization of the fragment. Also, the cb at this site may extend beyond the attachment capsule.

In a paper published on the incidence, lo( classification of 371 third carpal bone fractures in incomplete fractures of the radial facet occurred i large proximal chip fractures of the radial facet ( 140 cases, small proximal chip fractures of the] occurred in 18 cases, medial corner fractures 0 13 cases, frontal plane slab fractures of the rad 39 cases,large frontal plane fractures involving 1 and intermediate facets occurred in 35 cases,fract intermediate facet occurred in 13 cases, and s~ fractures of the third carpal bone occurred i: (Schneider et alI988).

The most useful preoperative radiographs i (DLPMO) projections (Fig. 4.44A). ' DDiO) is also useful in further (Fig. 4.44B). Thin slab fractures arthroscopic removal. but most with screw fixation using, subsequent sections). Figure

reversed position could be

third carpal bone than is the manipulation of

fractures may be typical chip-type bone,becauseradiographicallysilent lesions on the aspect of the radial carpal bone have been enWhen these occur, surgery can be performedin using the same lateral instrument portal as medial side of the intermediate carpal bone should be -during procedures involving distal radial carpal .fragments (Fig. 4.43). In this case we use medial instrument portal that is used for distal radial of arthroscope and instruments is often required to perform the removal.

Partial slab fracture that extend distad and exit dorsad -.-,to arthroscopic surgery. Thin slab j thickness of the third carpal bone can also be ren using the arthroscopic technique although cut1 carpometacarpal joint capsule attachments with difficult. however.

The prognosis for third carpal chip fractures an( slabfractures is variable. As in other sites in the middJ joint, the prognosis is excellent with small, well fragments accompanied by minimal degenerative Postoperatively,new bone proliferation is a potential]

when the fracture line extends deep into the c

Dorsoproximal third carpal bone Fragments from the proximal third carpal bone can sometimesbe more difficult to operatethan chip fragments

attachments. Multiple fragments off the third bone may occur. When these fragments are large ant bone from the joint is significant. instability is a p problem.

Arthroscopic Surgery for Removal of Osteochondral Chip Fragment Fig. 4.41 Diagram of positioning operations

involving

of arthroscope

and instrument

a distal intermediate

during

carpal bone chip

fragment.

R

Fig. 4.42 Arthroscopic views of fragments of distal intermediate carpal bone (radiographs fragment in left carpus (C-F) Large fragment in right carpus.

of these fragments

are in Fig. 4.40). (A-B) Small continued

Fig. 4.43

Fragment on distal intermediate carpal bone found during diagnostic arthroscopy for removal of a fragment on distal rad carpal bone. The fragment is on the most-medial margin of thE distal intermediate carpal bone and in this case was removed I a medial instrument

portal.

Dorsoproximal radial carpal bone The technique for operating on fragmentation at this site is illustrated in Figure 4.49. Thesefractures are usually identified preoperatively with standing and flexed lateromedial and dorsolateral-palmaromedial oblique DLPMO radiographs. As with other sites,the size of lesions can vary widely (Figs 4.50 and 4.51). The arthroscope is placed through a lateral portal and the instrument enters through a medial portal. The fragments can usually be well visualized and often are relatively small (see Fig. 4.50), although significant loss of bone occurs occasionally (seeFig 4.51).

With the standard medial portal, instruments must approach the lesion almost end-on, and manipulation can be more difficult than on the distal aspect of the radial carpal bone. Repeated manipulation tends to cause subcutaneous extravasation and the medial aspectof the antebrachiocarpal joint is also narrower than other locations. Occasionally, a lateral arthroscopic portal can be used (Fig. 4.52).

The amount of cartilaginous damage associat these chips is variable. and the prognosis varies aCC Although marked erosion of the proximal surfacI radial carpal bone can occur there, it is a su impression that the antebrachiocarpal joint appea more forgiving than the middle carpal joint in hor similar degrees of loss from the proximal versus 11 articular surfaces of the radial carpal bone.

Proximal intermediate carpal bone

The technique for operating on chip fractures at th illustrated in Figure 4.53. Standing and flexed later (LM) and/or dorsomedial-palmarolateral oblique (: radiographs (Fig. 4.54) are most useful in ide fragmentation of the proximal intermediate carp; These fragments can be small, distinct and easily] (Fig. 4.54), but. often. they are large and extend a c

QO Diagnostic

and Surgical Arthroscopy

of the Carpal joints

Fig. 4.48 Arthroscopic views of a partial slab fragment of the third carpal bone. (A and B) Surface defect at proximal-distal fragment respectively. (C) At removal of the fragment. (D) At debridement.

length of the

Fig. 4.49 (A) Diagram of positioning of arthroscope and instrument the radial carpal bone. (B) Making instrument portal.

during operations

involving

a chip fracture

off the proximal

aspect of\

ยง;7 Diagnostic and Surgical Arthroscopy of the Carpal Joints

Fig. 4.51 Radiograph (A) and arthroscopic carpal bone.

views (8 and C) of large displaced

chronic

fragment from

the dorsoproximal

margin of the rad

Fig. 4.52 (A and B) Fragmentation of the proximal radial carpal bone encountered fragment and being removed using a lateral instrument portal.

during removal

of a proximal

intermediate

carpal bon

abledistance into the joint capsule attachments (Fig. 4.55). In such cases. prior separation of capsular attachments in addition to separation at the fracture line is recommended.

Occasionally, a chronic chip or the spur associated with it might have an intracapsular portion. In these cases, the intra-articular portion is removed with rongeurs or a burr as far as the capsular reflection only. Postoperative radiographs often do not appear as satisfactory as following fragment removal. Nonetheless, this is considered preferable to the capsular trauma necessaryto remove intracapsular fragments and/or new bone. As with fragments in other locations, a relatively small fragment may be associatedwith considerable loss of articular cartilage.

Proximal

ulnar carpal bone

Fragments at this site are rare. To perform arthroscopic surgeryfor this lesion,the arthroscopeis placedmediallyand instruments enterthrough the lateralportal.

Lateral aspect of the distal radius These fragments are usually best demonstrated on a dorsomedial-palmarolateral (DMPW)radiographicprojection (Fig.4.56A). Theycan be displaced,non-displaced, singleor multiple,and frequentlyare larger than fragmentselsewhere

in the carpal joints. Often the fragments radiodensity, loss of infrastructure, new bone formation. Occasionally, the radiographic views do not demonstrate a event, a skyline (DPrDDiO) view of the recommended (Fig. 4.56B).

The technique for operating on chip fractures of the dorsolateral margin of the distal radius is illustrated in Figure 4.57.

The arthroscope is inserted through the medial portal and instruments are passed through the lateral portal. The position of the fragments necessitates that instruments are directed distad so that their shafts lie at an angle close to the dorsal aspect of the carpus. The fragments are usually large (;?;1 cm wide), with the most proximal portion attached to the fibrous joint capsule. These fractures are also commonly comminuted with a wedge-shaped osteochondral fragment palmar to the largest dorsal fragment.

The size of the fragment can be assessed reasonably accurately from preoperative radiographs. Damage is usually limited to the defect created by the fragments. only and cartilage loss does not usually extend peripheral to the defect (Figs 4.58 and 4.59). The arthroscopic appearance depends on the age of the fragments. In many such cases the dorsal fragment appears to be acute and the palmar wedge shaped fragment appears to be longer standing. In acute fragmentation there is usually hemorrhage within the fracture. When

8ยง Diagnostic and Surgical Arthroscopy of the Carpal joints

Fig. 4.57 Diagram

(A) and external

view (B) of arthroscope

and instrument

during operations

involving

a chip fracture

off the distal lateral

radius.

Fig. 4.58 Arthroscopic view of relatively small distal lateral radius fragment of a right carpus prior to removal (A), at elevation (8), at removal with Ferris-Smith rongeurs (C), and after removal and debridement (D).

: fragments, the larger fragment is usually superficial fragments, and a deep search is in these cases. With fractures of long-standing, , Before retrieval, large fragments are elevated (Fig. 4.59) attachments severed with a periosteal elevator. cup rongeurs are used to remove fragments. usually necessary to twist the rongeurs after grasping fragment to ensure that the fragment is free of attachments before making an attempt to pull it through the joint capsule. Enlargement of the skin incision is commonly necessary to bring these fragments out through the skin.

Figure 4.60 depicts a chronic distal lateral radius fragment that was associated with osteochondral diseaseperipheral to the fracture. Damage is rarely more extensive that that noted here, unless the lesion is chronic and mobile. Removal of large fragments that extend proximally into the capsular reflection can result in penetration of the synovial sheath of the extensor carpi radialis or common digital extensor tendon.

Mter removal of the fragment, the depths of the defectare carefully explored to find any remaining fragments. Some

bony proliferation proximal to the defects within the fibrol joint capsule is common, and should be left alone. Debridl ment follows the basic principles outlined previously, but mc include areas of capsular tearing. This should be perform( carefully and in a conservative manner in order to limit tl: potential for traumatizing the adjacent tendon sheath and 1 avoid further capsulitis.

When these fractures are of long duration, the fractul line may be obscured and the fragment is usually recognize by the presence of articular erosions and irregularities.

Despite their size, the prognosis for chip fractures of th distal lateral radius is good. This is generally considered to b the result of different biomechanical influences and becaus the remaining articular surface is usually not damaged to an great degree compared to other sites of carpal fragmentatior

Medial aspect of the distal radius

Fragmentation at this site is best demonstrated in dorsolateral-palmaromedial oblique (DLPMO) radiograpl (Fig. 4.61). The technique for removing fracture fragment from the medial aspect of the distal radius is illustrated il Figure 4.62. The arthroscope is placed through the latera

portal and the instruments through the medial portal. A with distal lateral radius fragments, the instruments ar angled rather flatly against the knee and directed proximac These fragments are similar to their lateral counterparts il that the surface damage is usually localized to the area of th fragment. However. smaller fragments are more commol medially but large ones can occur (Fig. 4.63). Methods ( surgical removal are the same as those described for later~ radius fragments. but sometimes on the most medial portio] of the bone. accesswith forceps is more difficult than laterall: The surface manifestation of these fragments varies like dist~ lateral chips. and the use of the curette may be necessary fo chronic lesions (Fig. 4.64). Removal of very large dist~ medial radius fragments can potentially cause trauma to th extensor carpi radialis tendon shealth with consequeIJ synovial herniation (Fig. 4.65).

Diagnostic and Surgical Arthroscopy of the

Removal of osteophytes

it is on first, as subcutaneous fluid extravasation is more likely to occur in the antebrachiocarpal joint. The loss of irrigating fluid after creation of a large instrument portal means that the surgeon will need to switch to the opposite side of the joint to operate on a chip on the other side, and insert the arthroscope into a relatively non-distended joint. If time has , between the two entries, some blood may be in the which can be cleared by irrigation. The bleeding is from a previously debrided subchondral bone and occurs after loss of joint distention. With joint and irrigation, subchondral bleeding is usually

or spurs

The removal of spurs or osteophytes is appropriate if have fractured off or if their interposition into the joint] them likely candidates for later fracture. Figure demonstrates spurs that were removed. These spurs n removed with Ferris-Smith rongeurs. curettage, an ostec or burr.

Most spurs that are visible radiographically ar candidates for removal. In many instances the experi surgeon can predict whether an attempt at removing ( is appropriate by examining the radiographs. As a gt rule. however, the surgeon should maintain an open and examine the spur at the time of arthroscopic su This statement is not to say that every carpus with a Spl candidate for arthroscopic surgery. As experienced clini know, many small spurs noted in 2-year-old horses are I evidence of previous synovitis and capsulitis. and are current clinical importance.

Articular cartilage and bone deBeneration in association with chip fractures

carpal

The presence of articular cartilage degeneration associated with carpal chip fragments and the debridement of degenerate cartilage were mentioned previously, although this problem deserves specific attention. For convenience, four grades of articular surface damage, as evaluated arthroscopic ally, have been made (Mcllwraith et al 1987) and are illustrated in Figure 4.67: 1. Minimal fibrillation or fragmentation at the edge of the defect left by the fragment, extending no more than 5 mm from the fracture line (Fig. 4.67 A and B).

2. Articular cartilage degeneration extending more than 5 mm back from the defectand including up to 30% of the articular surface of that bone (Fig. 4.67C and D).

3. Loss of 50% or more of the articular cartilage from the affected carpal bone (Fig. 4.67E).

4. Significant loss of subchondral bone (usually distal radial carpal bone lesions) (Fig. 4.67F and G).

The amount of articular surface loss should be documente on surgical notes and may be recorded by way of a drawin (Fig. 4.68). Significant bone loss causes loss of cubodi~ congruency (Fig. 4.67F and G).

More subtle degreesof cartilage damage have been define and graded in man (Pritsch et al 1986) and the recent~ defined ICRS grading system (Cartilage Injury EvaluatioJ System 2002) is gaining acceptance. These classification should not be confused with the system just described Although a more detailed breakdown of damage may b, appropriate for guiding treatment. it may have limited ValUI in defining prognosis.

Debridement of defects after chip fracture removal A discussion of the rationale for debridement after fragmeni removal necessitates a brief review of current knowledg( regarding healing of tissues. particularly articular cartilage These considerations are also important with regard tc postoperative management and convalescent time. Tradition.

Erosion and Chips

Proximal carpal row

Right

Distal carpal row

r Partial thickness kissing lession

ally, repair of articular cartilage has been considered in two situations: (1) superficial defects that do not penetrate the full thickness of the articular cartilage, and (2) full-thickness defects, which extend to subchondral bone. Superficial defectsin equine articular cartilage do not heal, whereas fullthickness defects heal through formation of granulation tissue and its subsequent metaplasia (Riddle 1970).

In studies involving the horse, the nature of the replacement tissue in the full-thickness defect varied between investigators. In one study, the authors noted that whereas 3 mm, full-thickness defects were repaired satisfactorily at 3 months, defects of 9 mm in diameter were not completely replaced at 9 months (Convery et aI1972). The repair tissue was a variable mixture of fibrous tissue, fibrocartilage, hypercellular cartilage, and (occasionally) bone, whereas another investigator reported complete healing of both 4 mm and 8 mmdiameter, full-thickness defects (Grant 1975). In a classic study on the carpus, Riddle (1970) demonstrated that fullthickness

.

--

and debridement.

defects curetted experimentally were covered with granulation tissue 1 month later. This tissue underwentmetap change to form fibrocartilage by 2 months and imperfect hyaline cartilage by 6 months. In another carpal study, Grant (1975) noted that the defectsfilled with a deeper layer of immature hyaline cartilage and a more superficial layer of fibrocartilage. Synovial adhesions were also present.

The repair most closely resembled the adjacent normal hyaline cartilage when there were few synovial adhesions. If synovial adhesions were significant. the defects filled with a more primitive fibrocartilage and fibrous tissue. The authors therefore concluded that proximity of the lesion to the synovial membrane was potentially an advantage to healing.

Hurtig et al (1988) created large (15 mm square) and small (5 mm square) full-thickness lesions in weightbearing and nonweightbearing areas of the antebrachiocarpal, middle carpal, and femoropatellar joints. Repair had occurred in most small defects at the end of 9 months by a combination

of matrix flow and extrinsic repair mechanisms, although elaboration of matrix proteoglycans was not complete at this time. Better healing occurred in small weightbearing lesions when compared to large or nonweightbearing lesions.

Synovial and perichondrial pannus interfered with healing of osteochondral defects that were adjacent to the cranial rim of the third carpal bone. Large lesions had good repair at 2.5 months postoperatively; however, by 5 months, clefts between the reparative tissue and subchondral bone were common. Later, the clefts became undermined flaps of fibrous tissue that were disrupted by normal biomechanical forces, resulting in exposed subchondral bone.

Grant (1975) also found no correlation between increased healing time and improved tissue quality in full-thickness defects; defects at 54 and 67 weeks contained more fibrocartilage and less hyaline cartilage than defects at 42 and 47 weeks. Work in other species also has revealed hyaline cartilage at early stages of healing. There is therefore indirect evidence that, at 4 months. defects in the articular cartilage have reached the limit of healing capacity and. by 12 months. the replacement tissue has begun to degenerate.

More recent work in the first author's (C.W.M.) laboratory comparing normal healing in full-thickness defects at 4 and 12 months has demonstrated that the percentage of Type II collagen will progressively increase from 0% at 4 months to 80% at 12 months. The hexosamine level is about half the amount in normal cartilage at 4 months. and slightly less than the 4 month level at 12 months (Vachon et al 1992, Howard et aI1994). The current state of articular cartilage healing has been reviewed (Mcllwraith & Nixon 1996) and is now the subject of a separate chapter in this textbook.

The authors have also had the opportunity to operate bn a number of carpal joints for the second time after the animals have raced and have observed that the healing of defects varies (Fig. 4.69). In repair areas subjected to histologic analysis, fibrous tissue predominated. For all experimental studies in which cartilage healing in some form was demonstrated, these joints were never subjected to the continual exercise and trauma of a racehorse. Since the authors question how much functional healing occurs, debridement of partial-thickness defects is not performed. Cartilage is aneural and how much trouble many partial-thickness defects cause is questionable. Commonly, these defects are kissing lesions in association with fragments, and the best treatment is to remove the initiating cause, i.e. the fragment. Whether more than fibrous tissue will fill the defectsis unclear, and one should therefore be conservative in creating further defects or enlarging ones already present. The results of a study in man involving follow-up arthroscopy of patients treated for chondromalacia of the knee with or without cartilaginous shaving supports a conservative approach to management of partial-thickness defects. The conclusions were that only loosely hanging articular cartilage should be shaved, and that softened, non-loose, fissured articular cartilage should be spared (Friedman et aI1987).

The authors also adopt a relatively conservative approach with regard to debridement of deeper defects that remain after fragment removal. Rough edgesor adjacent undermined

or fragmented cartilage is removed. This protocol is base the belief that loose cartilage is irritating and may detach its prospects of healing onto bone are virtually nil. Par thickness erosion adjacent to a full-thickness defect is subjected to curettage if the cartilage that remarn attached solidly to the bone. Full-thickness defects debrided to the level of subchondral bone. Any soft defe bone is also removed.

In summary, based on both research evidence and ~ we have observed, the authors feel that a conser Vi approach when it comes to debridement of fibrillatiol thinning of articular cartilage should be taken. In 0 instances, when cartilage is separated and may appear thickness, the calcified cartilage layer may still be pre~ Failure to remove the calcified cartilage layer will cause healing response. With experience, one can recognize difference between the calcified cartilage and the: chondral bone (Frisbie et al 2001, unpublished data). , debridement of subchondral bone, in an adult animal, relatively straightforward to recognize defective, gran (and often necrotic) bone and distinguish it from S healthy subchondral bone. The distinction is more difficu the young animal, where the subchondral bone is quite In contrast, when the subchondral bone of a carpal defe hard and sclerotic, the use of subchondral microfracture aid accessto stem cells and growth factors in the cancel bone and has been used in clinical cases (Frisbie et al 2( unpublished data).

Deepor extensive debridement using motorized equipn is unnecessary in most cases.If debridement extends be} the level of attachment of the joint capsule, it can resu increased capsulitis and bone proliferation. In relating S of these ideasto follow-up management, if the actual matc that fills fresh, localized chip fragments is not of m concern and the area of the defect is small, then, if 0 sources of irritation have been removed, atWetic func should be limited only by soft tissue healing. For this rea horses with acute fragmentation and with minimal evid( of long-standing adaptive failure can return to training i 6-8 weeks.

When the lesions are more severe, the limitation cartilage healing are more significant. If the area ofcarti erosion is larger, then some form of healing is required, the importance of intact subchondral bone support effective articular cartilage healing is relevant. De mination of the conditions that are necessary or optir healing requires further investigation. At present, the aut! assume that extra time is required when subchondral hea is necessaryto restore a weightbearing surface. However, time requirements and physical factors for bone healinJ Grade 4 lesions have yet to be determined. In chronic, con cated cases, a minimum of 4-6 months rest is curre

recommended.

With the Chapter 14), of motorized synovectomy visualization.

possible exception of infected joints I therapeutic synovial resection with the equipment is not recommended. Locali is only performed occasionally to facili'

management

certain prognoses.The first author (C.W.M.) has had pleasiJ results with horses that have had multiple chip fragments as many as four carpal joints along with chronic chan~ However, selection should be applied with regard to bo 5 daysto decreasepain. reducesynovitis.and facilitate horses and clients. In general. a better result can be expect .Resultsof a double-blind.randomized with a horse that has proven racing ability and an owner th understands the prognosis.

Follow-up information on the first 1000 carpal joir less operated on by the first author (C.WM.) has provided objecti (;'synovitis. and less effusion postope~atively(6gilvie~Harris et information to give clients regarding prognosis (McDwraith et r al1985). They also had more rapid return of movement and 1987). Arthroscopic surgery was effective in removing' quadriceps function, and their return to work and sport was osteochondral fragments as well as treating other lesior significantly faster. The administration of antimicrobial There were no casesof intra-articular infection and fewoth drugs is a matter of individual surgeon preference. complications. The overall functional ability and cosmel Based on current knowledge of cartilage healing. it is appearance of the limbs were excellent. subjectively recommended that exercise be avoided for the Post-surgical follow-up information was obtained for 44 first week after surgery to enable the blood clot to organize racehorses. After surgery, 303 (68.1 %) raced at a level equ andto allow granulation tissueto commenceformation. Passive to or better than the pre-injury level, 49 (11.0%) hc flexion and hand walking begin after 7 days and the level of decreasedperformance or still had problems referable to tl exerciseis then progressivelyincreasedin line with the severity carpus. 23 (5.2%) were retired without returning to trainin of articular compromise. In horses with simple. fresh frag28 (6.3%) sustained another chip fracture. 32 (7.2%) develop ments (Grade 1 lesions), training may begin at 6 weeks. As other problems. and 10 (2.2%) sustained collapsing sIc the damage in the joint increases. the convalescent time fractures while racing. When horses were separated into fO should be appropriately increased. Horses with Grade 2 categories of articular damage. the performance in the t\\ cartilage loss should have a minimum of 3-months rest; with most severely affected groups was significantly inferior. Or Grade 3 and 4 lesions the horses should have 4-6-months hundred thirty-three of 187 horses with Grade 1 dama~ rest. Rehabilitation protocols including underwater treadmill (71.1 %),108 of 144 with Grade 2 damage (75.0%), 41 of 7 or swimming may be recommended if available. with Grade 3 damage (53.2%). and 20 of 37 horses wil Postoperative use of hyaluronan (HA) and polysulfated Grade 4 damage (54.1 %) returned to racing at a level equ, glycosaminoglycans (PSGAGs)is variably favored by different to or better than the pre-injury level. The successrate in casl clinicians. The authors do not consider HA a necessary or with Grade 1 and Grade 2 lesions was significantly greatc consistent part of the postoperative routine. In most cases. than that in caseswith Grade 3 and Grade 4 lesions. The dal the synovial HA levels are expectedto return to normal in the from racing Quarter Horses and racing Thoroughbreds we) convalescentperiod. If the articular damage at the time of divided. In 277 Quarter Horses, 81 of 112 (72.3%) wit surgery is of relatively low grade. then most cases resolve Grade 1 lesions, 72 of 96 (75.0%) with Grade 2 lesions. 26 c after a single treatment. PSGAG (Adequan@)is administered 46 (56.5%) with Grade 3 lesions. and 13 of 23 (56.5%) wit when there is significant articular cartilage degeneration and Grade 4 lesions returned to racing successfully. In 16 exposure of subchondral bone. Although there may be little Thoroughbreds. 51 of 73 (69.9%) with Grade-1 lesions. 3 effecton defect healing. ongoing cartilage degeneration may of 47 (76.6%) with Grade 2 lesions, 14 of 30 (46.7%) wit beinhibited (McIlwraith 1982. Yovich et al1987). Clinically.

Grade 3 lesions. and 7 of 14 (50%) with Grade 4 lesior a good response to PSGAG treatment is seen in the cases returned to racing successfully.Thesedata demonstrate a leI with severe articular cartilage damage. An initial intrafavorable prognosis for horses with severe damage but als articular injection of Adequan@ (250 mg with 0.5 ml that many horses can still come back and race successfully.

Amikacin sulfate) is recommended followed by weekly has been observed subjectively that. in more severe cases. intramuscular injections of 500 mg. Corticosteroid therapy shorter racing career can be anticipated due to recurrer after arthroscopic surgery is only recommended when there carpal problems, including refragmentation. is severe. persistent synovitis. Overall, arthroscopic surgery In five Quarter Horses used for roping, barrel racing. ( as a therapeutic procedure is best followed by rest and rodeo, all but one with a Grade 3 lesion returned to successf physical therapy (controlled exercise). performance. The pleasure and hunter horses had successf results in all six cases (one Grade 1, two Grade 2, thre Grade 3. and one Grade 4 lesions). The results of surger Case selection, prognosis, and results were also assessedin relation to the location of lesions. anI horses with a single site (or the same site bilaterally) involve Although fragments of all ages and size are amenable to were included (Table 4.2). arthroscopic surgery, not all horses are good surgical In racing Quarter Horses. the prognosis associated wit] candidates. Here, accurate communication with owners and involvement of the third carpal bone was significantly wors trainers is important to preserve the reputation of the than lesions in other sites. In Thoroughbreds, third Carpc technique before embarking on chronic cases with less and radial carpal bone lesions had the poorest prognoses. ]

I relative to the joint involved, 63.3% of Horses and 66.2% of Thoroughbreds with middle

carpal joint involvement returned to racing. For the antebrachiocarpal joint. 82.7% of Quarter Horses and 65.5% of Thoroughbreds returned to racing successfully. If both middle carpal and antebrachiocarpal joints were involved. 64.7% of Quarter Horses and 64.7% of Thoroughbreds returned to racing.

Sincethe publication of thesedata 15 years ago. ther havebeena numberof changesin clinicalpracticesthat maJ influencefuture results.Theseinclude: 1. Earlier intervention and thereforea higher percentageoj Grades1 and 2 lesionsbeingpresentedfor surgery.

2. Attemptsto enhanceosteochondralhealing (Chapter16), including subchondralmicrofracture.

3. More aggressive postoperative protocols, including medicationand physiotherapy.

Osteochondral fragments from the palmar aspects of the carpal bones have been recognized and removed (Mcllwraith 1990, Wilke et al 2001, Dabareiner et al 1993). In some instances these fragments are not surgical candidates, and when they are traumatic avulsions associated with other problems. the prognosis is typically poor (Wilke et al 2001).

Small discrete osteochondral fragmentation can involve any of the palmar surfaces of the carpal bones. with the

radial carpal bone being most frequently involved. The dorsal articular surface of the accessory carpal bone. and the palmar surfaces of the ulnar and fourth carpal bones are involved less frequently. Large partial slab fractures of the palmarolateral surface of the intermediate carpal bone also occur, and are largely inaccessible for arthroscopic removal or reattachment (Dabareiner et al19 93).

Fractures of the palmaromedial perimeter of the radial carpal bone (Fig. 4.70A) have been described in 10 horses (Wilke et al2001). These fractures are thought to result from compression injury, with the palmar perimeter of the radial carpal bone impacting on the surface of the radius, during falls onto the flexed knee. Arthroscopic removal can be done through a palmaromedial approach to the antebrachiocarpal joint (Fig. 4.70B-D), which gives ready accessto the palmar perimeter of the radial carpal bone and caudal aspect of the radius. The dorsal regions of the antebrachiocarpal joint are usually examined first, and concurrent damage to the articular surface of the radius and proximal row of carpal bones is debrided. The arthroscope portal is then made in the distended palmaromedial outpouching of the antebrachiocarpal joint. Examination of the palmar surfaces of the carpal bones commences medially, and the arthroscope can be redirected and introduced further to view the medial perimeter of the intermediate carpal bone and accessory carpal bone articulations. Most fractures are not radiographically confirmed for weeks to months after injury, and the chip fragment can initially be obscured at surgery by soft tissue proliferation (Wilke et aI2001). An instrument portal is developed adjacent to the arthroscope entity and motorized equipment used to remove synovial proliferation. The fracture of the palmar surface of the radial carpal bone can then be removed. Results in 10 horses with palmar fracture of the radial carpal bone suggested that simple fractures of the palmar perimeter should be removed as soon as they are identified (Wilke et al 2001). Salvage for riding was predominantly defined by the extent of osteoarthritis evident at the time of surgery. Caseswhere the damage was confined to only the area of the chip and where the fracture was removed soon after injury tended to have less osteoarthritis and did better after arthroscopic surgery. Concurrent injury to the medial collateral ligament or avulsion of portions of the radius substantially diminished the prognosis.

Palmar fractures of the other carpal bones are less frequently encountered. These include fractures of the fourth and ulnar carpal bone, the accessory carpal bone, and the intermediate carpal bone. The accessory carpal bone can be fractured during compression injury to the flexed knee (nutcracker effect). The most common accessorycarpal bone fractures are longitudinal frontal plane fractures that divide the accessory carpal bone into a dorsal and palmar portion.

These fractures do not involve the articular cartilage of the dorsal facets of the accessory carpal bone and are not considered candidates for an arthroscopic repair. Most of these fractures spontaneously develop a functional fibrous union. Smaller fractures of the proximal or distal articular surfaces of the accessory carpal bone can occur, disrupting the articulation of the accessory carpal bone with the

remainder of the carpus, and generally requiring removal (Fig. 4.71). The proximodorsal aspect of the accessory carpal bone can be examined using a palmarolateral approach to the antebrachiocarpal joint. A voluminous proximal palmarolateral joint pouch can be palpated after distension of the joint. The arthroscope portal is made in the proximal portion of this outpouching, leaving the region over the proximal perimeter available for instrument access(seeFig. 4.71). The fracture fragment is then identified, the soft tissue attachments and synovial proliferation debrided, and the fragment removed using rongeurs. Fractures of the distal portion of the accessorycarpal bone are less frequent, and accessto this outpouching of the antebrachiocarpal joint is limited.

The palmarolateral aspect of the midcarpal joint can be entered for removal of fractures of the ulnar and fourth carpal bone. The arthroscope portal can be made without difficulty; however, synovial tissue removal will be required to completely identify the fracture fragment during removal.

There are no case series available to provide a basis for prognosis; however, the authors' limited experience suggests these fractures are a source of lameness, which can be substantially improved by removal.

Fractures of the palmar surface of the intermediate carpal bone can involve a small wedge-shaped articular portion detached from the proximal perimeter of the intermediate carpal bone or a larger palmar slab fracture of the palmar surface, extending from the antebrachiocarpal joint to the midcarpal joint. Removal of smaller fragments through the carpal tunnel has been reported; however. arthroscopic removal has not been described. Palmaromedial and palmarolateral approaches to the antebrachiocarpal joint reveal only the medial aspectof the intermediate carpal bone.

The lateral portion of the intermediate carpal bone. where the fractures have been described. is obscured by the accessorycarpal bone attachments.

Arthroscopic Subchondral

Surgery for Bone Disease

Theselesions were initially described in the proximal aspect of the third carpal bone. A number of radiographic changes may be evident on tangential "skyline" views of the third carpal bone including sclerosis,lytic lesions. or linear defects

variously interpreted as incompletefractures or "pre-slab"

lesions. Sclerosis of the radial facet is a well-recognized change and some authors suggest that it is a primary lesion, often preceding more serious change, such as cartilage damage or gross fracture (DeHaan et al198 7). These authors also suggest that early recognition of sclerosis of the third carpal bone may help to prevent the occurrence of more serious changes (DeHaan, et aI1987). Sclerosisis considered to arise with training and racing. However, whether the sclerosisleads to articular cartilage lesions or the same forces that can cause sclerosis also cause articular cartilage lesions directly has yet to be ascertained. Arthroscopy of a small number of joints that had sclerosis as the only radiographic

sign, revealed wide variability in the gross appearance of the overlying cartilage (Richardson 1988) and this author agrees.

So-called third carpal bone diseasepresents as a persistent carpal problem that does not respond to medication and is characterized by lytic change evident on skyline radiographs of the third carpal bone (Fig. 4. 72A). Frequently, some degree of surrounding sclerosisaccompanies the lytic changes. Most lesions occur on the radial facet; they may be single or multiple and range from linear to circular in outline on skyline radiographs (Richardson 1988). The proximal subchondral bone is particularly thick and denseso that damage and lysis in this area results in dramatic radiolucency in tangential projections.

Arthroscopically, these lesions manifest as an area of defective subchondral bone, with the overlying cartilage absent,a depressionin the articular cartilage, an undermined cartilage flap, or fragmented cartilage (Fig. 4.72B and C). In some cases there is overt fragmentation of the subchondral bone, which, since it is non-displaced and cannot be imaged in profile, is not recognized radiographically. Loose tissue is removed and the lesion is debrided with a curette. The defective bone is often granular in nature. A rim of intact tissue on the dorsal margin of the third carpal bone usually

remains, although in some casesthe defective tissue exteru out through this margin. Also. if the remaining rim narrow. it is removed to the level of the defect.

It is now recognized that subchondral bone disease c~ occur at other locations and may be the precursor exercise/work-induced osteochondral fragmentation. Clinic signs associated with subchondral bone diseasesare simil to animals with osteochondral fragmentation. However. pI surgical diagnosis (at locations other than the third carp bone) is difficult; the disease is rarely demonstrable radi graphically. The best example is the distal radial carpal bolJ where lesions can consistently be found arthroscopicaJ (Fig. 4.73).

Subchondral bone diseasehas also been seen on the dist radial, proximal third, proximal radial. intermediate carp bones. and on the distal radius (lateral and medial) (Fig.4.7: Figure 4. 73H illustrates subchondral bone diseaseon the mo palmar areas of the second and radial carpal bone.

The post-surgical protocol is determined by the degree articular compromise. using criteria similar to other carp arthroscopic procedures. In one report of 13 Standardbr, casesinvolving the third carpal bone. 8 returned to racing, of these in their original class (Rosset al1989).

More recent work has investigated the relationship betweenincreasedbone densityin the third carpalboneand racing (Younget al1991). Regionalvariationsin trabecular bone density and stiffness have been implicated in the pathogenesisof third carpal bone fractures (Young et al 1991). In addition. subchondral lucency. commonly in combination with sclerosisof the third carpal bone radial fossa.has been associatedwith acute. moderateto severe lamenessreferableto the middlecarpaljoint in Standardbred racehorses(Rosset al1989). Investigatorsin Swedenhave looked at subchondralsclerosisand subchondrallucencyin the third carpalbonein Standardbredhorsesdiagnosedwith traumatic carpitis and related it to clinical appearanceand prognosis for racing. Subchondral lucency was found significantlyto influencethe degreeof lamenessand the time to start. but did not significantlyaffectthe chanceof racing

within 30 months post-examination(Uhlhorn & C 1999). However,it was alsorecognizedthat there wa number of third carpal bones with severesclerosis course,no arthroscopicintervention, and this limit canbeconcludedfrom this study.

Twenty-four cases of tearing of the medial palmar carpal ligament (unpublished data) were reported previous edition of this text. Since then there ha

cystic lesions are commonly noted in the clinically significant lesions will occur and are to intra-articular analgesia.A the proximal radial carpal bone that was symptoillustrated in Figure 4.77. The cystic lesion was arthroscopicallyand the opening found, the and the joint flushed(Fig.4.77).

Arthroscopic Surgery Treatment of Carpal Slab Fractures

for

Current status of surgery

Various forms of frontal and sagittal slab fractures occur the carpal bones. of which the most common is a fron plane slab fracture of the third carpal bone. The advanta~ offered by arthroscopy are such that repair of carpal sl fractures under arthroscopic visualization is now t

technique of choice. Arthroscopic evaluation of the entire joint and fracture reduction are superior to those obtained by radiography, fluoroscopy, or of direct observation, and surgical trauma is minimized (Richardson 2002). These features comply entirely with the AD goals of atraumatic operative technique, accurate anatomic reduction, rigid internal fixation, and early postoperative ambulation.

Recognizing concomitant damage that will detract from a successful outcome also enhances clinical success. Case selection is important and animals with poor conformation, evidence of asymmetric limb loading, or failure of osseous adaptation, and horses with poor athletic histories are unlikely to produce rewarding results.

Removal of slab fractures carpal bone

of the third

The authors' general philosophy is that whenever articular surfaces can accurately and safely be reconstructed, this should be the primary treatment goal. Thin displaced and irreducible slab fractures of the third bone can be removed arthroscopically (Fig. 4.78). Standard dorsolateral arthroscopic and dorsomedial instrument portals are employed. Removal of the fragment necessitates sharp dissection from the dorsal joint capsule and associated transverse dorsal intercarpal ligaments. This is most effectively achieved with a fixed blade knife and use of straight and curved elevators. A motorized synovial resector is useful during dissection in order to maximize visibility. Once the fragment is loose, it is manipulated proximally in order that it may be grasped with large arthroscopic rongeurs. These then are twisted in order to free the last remaining soft tissue attachments before the fragment is removed. Enlargement of the skin incision is frequently necessaryat this point. Debridement of the fracture bed follows and, in addition, limited debridement of the joint capsule and dorsal intercarpal ligaments is appropriate.

Lag screw fixation of slab fractures of the third carpal bone The most common slab fracture of the third carpal bone occurs in the frontal plane and involves the radial (medial) facet. Less commonly, there may be sagittal or parasagittal fractures in the medial one-third of the radial facet and in some animals there may be slabfractures of the radial facet in both frontal and sagittal planes. Frontal plane slab fractures can also run the full mediolateral width of the third carpal bone, including radial and intermediate facets. Occasionally, frontal plane slab fractures will involve the intermediate (lateral) facet only.

The degree of lameness varies from mild to severe.

Fractures in a frontal plane are usually accompanied by marked distention of the middle carpal joint and frequently also by pain on palpation of the third carpal bone. Fractures in the sagittal plane usually produce lesssevereclinical signs.

Frontal plane fractures are usually apparent on lateromedial

and dorsolateral palmaromedial oblique radiograpl projections. Comminution occurs most commonly at t proximal margin of the fracture and may be seen dorsolateral-palmaromedial oblique and flexed lateromed projections. Detection of comminution is important surgical planning and prognostication. Flexed dorsoproxim dorsodistal (skyline) projections define the dimensions a

the fracture (Fig. 4.79). Comminution or the

osseousinfrastructure in the fracture

but may also be identified in dorsomedial" ,-

some non-displacedfractures may heal with articular insult; consequently, the risks of fractures has also been shown to enhance healing (Mitchell & Shephard 1980). Internal of unstable or displaced slab fractures is usually to control pain and rapid development of prog.some cases, thin frontal plane stab fractures

third carpal slab recognized advantages of surgery, there was no disruption of the

but all are basedon that originally developed planning is important and the surgeon

oblique radiographic projections (see Fig. 4.79). : can be repaired with AD/ ASIF cortex screws of 3.5 mm or 4.5 mm diameter. This is determined

I recumbency. The former offers greater versatility of positioning and also permits bilateral surgical

movement between the standard position for The middle carpal joint initially is evaluated utilizing the 1 arthroscopic portal. In acute injuries there is permit visibility. This is usually performed through a -'" : portal. The dorsal compartment of and any additional lesion noted. Non-displaced fractures have variable amounts of cartilage disruption (Fig. 4.8IC).

Some fractures. which on radiographic examination appear non-displaced. are found to be unstable at arthroscopic evaluation. Displaced fractures frequently are accompanied by additional cartilage loss and there may also be comminution, which most commonly occurs as a wedge in the proximal palmar margin of the fracture. Reduction (when necessary) is effected most effectively by flexion and this should be performed progressively.Defects are debrided prior

to repair (Fig. 4.80) and any comminuted fragments tl preclude complete reduction should be removed. Surgic opinion is divided on the fate of large palmar fragments. these can be retained and stabilized in the repair, SOl. surgeons prefer this option to removal and conseque creation of a large proximal articular deficit.

The medial and lateral margins of the fracture are mark, by percutaneous insertion of 22- or 23- gauge needl (Fig. 4.81). A spinal needle is then placed midway betwe4 these two needles.close and parallel to the proximal articul surface. and directed across the midpoint of the fracture close to 900 as possible (Fig. 4.81). This needle is the mc important directional guide for implant placement. Conti uration of most slab fractures of the radial facet of the thi carpal bone is such that the tip of this needle usually lodg in the palmar fossa of the bone. It is important that med and lateral marker needlesare used to determine the positil of this needle; the eccentric position of the arthroscope aJ its inclined lens angle mean that accurate determination the midpoint of the fracture from the arthroscopic ima alone is not possible.Once the spinal needle has been placf a further 20- or 23- gauge needle is inserted into t] carpometacarpal joint directly distal to its point of entry. required, a radiograph is made to ascertain proximal-disl positioning of the screw (Fig. 4.82).

At this stage some surgeons remove the arthroscope b the authors' preference is for this to be held by a surgic assistant. A short (stab) incision is made midway between t] spinal needle and the marker needle in the carpometacarp

a No. 10 or 11 scalpel blade. This incision should which at A glide is drilled in the fragment using the spinal needle as a guide (Fig. 4.83). Once this has reached the insert sleeveis positioned in the glide hole. some displaced fractures in which a small amount of articular incongruity persists. limited fragment manipulation can be performed at this time. Leaving the arthroscope in situ permits direct visualization of the process and continuous monitoring of reduction and repair. The thread hole is then drilled to the palmar surface of the bone (Fig. 4.84). This depth is checked against the preoperative measurements. before a countersink is used to create an appropriately sized bed for the screw head. The strongly convex dorsal face of the third carpal bone means that this is important for all screw sizesto avoid point contact and maximize efficiency of compression and to avoid protrusion of the screw head into the joint capsule. dorsal intercarpal ligaments. and tendon of insertion of the extensor carpi radialis. The reduction can be

assessedarthroscopic ally and radiographs should also I taken at this point to ensure optimal implant placeme (Figs. 4.85 and 4.86).

Unstable comminuted fragments and detached cartila are removed at this time and the joint is lavaged. Skin portc only are closed in a routine manner and a padded dressiI applied for the immediate postoperative period. Follow-\ radiographs of a repaired frontal slab fracture are present! in Figure 4.87. Displaced fractures of the radial facet of tI third carpal bone are managed in the same fashion wi regard to fixation. However, one is frequently left wi' significant defects at the articular surface. There is usually defective subchondral bone wedge or multiple piecesand aft removal a large size defect remains (Fig. 4.88). In oth situations, there can be a number of comminuted fragmen that require removal, leaving a major defect on the later aspect of the fracture (Fig. 4.88D and E).

Frontal fractures also occur, involving both the radial ar intermediate facets, and are generally repaired with tv screws (Fig. 4.89). Individual fractures of the intermedia facet of the third carpal bone also occur and are wc identified on dorsomedial-palmarolateral radiographs; thl are usually repaired with a single 3.5 mm screw (Fig. 4.90 Sagittal and parasagittal fractures of the radial facet of tI third carpal bone are inherently more stable than fractures a frontal plane. They are best identified on skyline radio raphs and sometimes are also seen on dorsopalmi projections (Fig.4.91). Arthroscopic evaluation usually revec a fracture line commencing in the dorsal margin of the bO at the junction of its middle and medial one-thirds. TI fracture may then curve to exit the articulation between 11 second and third carpal bones or may extend in a straight IiI toward the palmar fossa of the third carpal bone (Fig. 4.9] Conservative management has been discussed for sagitt fractures in the third carpal bone (Fischer and Stover 1987 Half of the cases managed conservatively healed. Comm nution is rare and cartilage loss uncommon. The principles repair are similar to those described above for fractures in frontal plane. However, there is a small window for safe ar effective internal fixation, which necessitates implal placement close to the dorsal margin of the articulatic between the second and third carpal bones (Fig. 4.9] Fortunately, fragment size is such that large implants are nl required and the head of a 3.5 mm AO/ASIF cortex scre can be safely placed at this site (Fig. 4.92).

Fractures which occur in both frontal and sagittal planl can involve a number of configurations, and these will dete mine the sites for appropriate implant placement. Non theless, the principles applied individually to fractures i frontal and sagittal planes apply. In some instances it may I necessary, in order to avoid impingement of implants, 1 place these at differing proximodistallevels within the bon Frontal plane fractures that involve the radial and inte mediate facets of the third carpal bone can occur in a numb! of configurations. The basic arthroscopic approach is c described for frontal plane slab fractures involving the radi, facet only. However, it will usually be necessaryto insert t\\ screws in order to produce effective compression and stab

Diagnostic and Surgical Arthroscopy of the Carpal Joints

Fig.4.83 Diagram

(A) and external

views (B and C) of drilling

4.5 mm diameter

hole in a frontal plane slab fracture

of the third carpal bonE

,

Arthroscopic

for Treatment of Carpal

R

of frontal

plane slab fracture

of the third carpal

fixation.Thesemay involvepairs of 4.5 mm or 3.5 mm or a combination of screw sizes (Fig. 4.89). Slab fractures involvingonly the intermediatefacetof the third carpalbone should be approachedusing dorsomedialarthroscopyand dorsolateralinstrument portals. Theseusually are repaired with a single 3.5 mm screw(Fig.4.90).

also be beneficial at this point. The total convalescent pert is usually approximately 6 months.

With appropriate screw placement, complications a uncommon. A further fracture extending to the screw and/t creation of a chip fracture at this site has beenrecogniz( there is good clinical or radiological evidenceim implants in lamenesslocalizing to the middle carr joint, screws are not removed.

Postoperative management Routinely padded dressings are used in the immediate postoperative period but in horses with large unstable fractures use of a sleeve cast in recovery from general anesthesia and in the immediate postoperative period is appropriate. Most animals are confined to a stall for 2-4 weeks and this is followed by a 6-8 week period of increasing amounts of walking exercise. Flexion exercise is encouraged immediately after surgery and should continue until a full and unrestricted range of flexion consistently is obtained. At the end of the walking period. progressive increase in exercise is permitted and this may involve continued controlled exercise. such as ridden trotting exercise or free exercise in a small paddock. Swimming may

Results

In the series of 23 horses with third carpal slab fractul reported by Richardson (1986),17 had a 6-month or lon~ follow-up interval. Ten of the 17 horses returned successfu racing; 1 horse was training soundly, and trained well b retired because of other injuries. One horse was unalt return to training because of injury that had occurr simultaneously with the slab fracture, 2 did not recover w enough to train, and 1 was lost to follow-up. At the time writing, 6 horses had less than a 6-month follow-up periodw progressing well and 1 developed radiographic signso In uncomplicated cases,the cosmetic appec

111_lli~

Diagnostic and SurgicalArthroscopy of the Carpal Joints

Fig. 4.85 Diagram (A), external view of screw placement plane slab fracture of the third carpal bone.

(B) and radiograph

confirming

appropriate

screw placement

(C) in repair of fronta

Fig.4.91 Radiographs (A and B) and arthroscopic view (C) of sagittal fracture of the third carpal bone. A needle has been inserted to ascertain position of implant placement.

ance of each carpus was reported as good. with only a small swelling over the screw (Richardson 1986). Horses with displaced slab fractures have a poorer prognosis for return to racing than do those animals with undisplaced slabfractures. because the latter are associated with more severedamage to the joint surfaces (Bramlage 1983). This situation remains the same whether treatment involves arthroscopy or arthrotomy. Similarly. the prognosis worsens when loss of the wedge of cartilage and bone at the proximal articular surface leaves a large defect after fixation (Bramlage 1983).

There have been two other retrospective studies published on third carpal slab fractures and their repair. However,these did not generally involve arthroscopic surgery and care should be taken in extrapolating results. In one paper, the caserecords and radiographs of 155 horses with third carpal bone slab fractures were reviewed (72 Thoroughbreds and 61 Standardbreds) (Stephens et al 1988). Of 73 fractures in Standardbreds, 37 were repaired by screw fixation. 18 were

surgically removed. and 18 were treated conservatively. the 82 Thoroughbreds with a third carpal fractures. 46 w repaired with screws. 21 had the fragment removed. and received rest only. The effect of treatment on outcome was ] significantly different. Fracture characteristics did] significantly affect outcome. but did influence treatm, selection. In Standardbreds. 77% if the horses raced aJ injury: in Thoroughbreds. 65% raced. Earnings per st declined in each breed. but the decline was more pronoun in Thoroughbreds (Stephens et alI988).

In a second study of 31 cases of racing Thoroughbr with third carpal slab fractures. all cases were trea surgically. Twenty-one (67.6%) horses raced at Ie once after recovery from the surgery: In 11 claiming hor: the claiming value decreased from a mean of $13.900 t mean of $6.500, the mean finish position was 5.8 :t 3 before injury and 5.6 :t 3.30 after surgery (Martin e1 1988).

Treatment of Other Slab Fractures

Carpal

Slab fractures of other carpal bones are uncommon but also can be assessed.reduced, and repaired under arthroscopic guidance. Frontal plane slab fractures of the radial carpal bone are assessed arthroscopically through dorsolateral portals in both middle carpal and antebrachiocarpal joints.

Fracture margins are marked with percutaneous needlesand the trajectory of implants is determined with a spinal needle in a manner similar to that employed in corresponding fractures of the third carpal bone. The fracture configuration will determine the size and number of implants necessary.

Figure 4.93 illustrates a slab fracture of the radial carpal bone which was repaired arthroscopically. Sagittal slab fractures of the intermediate radial of third carpal bone have been found at arthroscopy; the fractures have been generally treated by removing the slab fragment. but in a recent case with internal fixation with a 2.7 -mm screw. Arthroscopy also is the technique of choice for the repair of reconstructable fractures of multiple carpal bones. These involve most commonly the radial and third carpal bones and the technique is varied to accommodate the variations of each individual fracture (Fig. 4.94). Such cases should be fitted with a sleeve cast for recovery from general anaesthesia and for the immediate post-operative period. Slab fractures of the fourth and intermediate carpal bones have been reported (Auer et al 1986). Poor results were achieved after screw fixation with arthrotomy.

Arthroscopic repair of large chip fractures can, in SO instances be an alternative to removal. This is based on tl premise that reconstruction of articular surfaces is preferal to creation of a large osseous defect (Grade 4 lesion). TI necessary caveats are that fragments should be of sufficie size and have adequate osseousinfrastructure for placeme of a screw and that the process of reconstruction should lesstraumatic than removal. Most chip fractures are repair with 2.7 mm AO/ASIF cortex screws although on occasio these may be sufficiently large for use of 3.5 mm diame1 screws. The latter may be employed in repair of frontal pIa fractures of the third carpal bone that extend from its proxin articular surface (usually the radial facet), to exit with t dorsal surface of the bone proximal to the carpometacarlj Chip fractures of the dorsodistal margin of the rad carpal bone (Fig. 4.95), dorsoproximal margin of the till carpal bone and dorsoproximal margin of the radial carl bone have been repaired using 2.7 mm diameter screv Delineation of the fracture is performed in a manner simi] to that describedfor the repair of slabfractures. Most fragmeI which are amenable to repair will exit the bone within t. capsular reflection and/or associated intercarpalligamen This point can be determined, if necessaryby radiographica guided needle placement. The position for screw placemel in most instances is within the synovial cavity and therefc the drilling process and insertion of implants can performed under direct arthroscopic visualisation. Healing repaired carpal chip fractures has been documented but, date there have been no published results.

References Auer JA. Watkins JP.White NA. et al. Slabfractures of the fourth and intermediate carpal bones in 5 horses. J Am Vet Med Assoc 1986; 188: 595-601.

Bramlage LR. Surgical diseases of the carpus. Vet Clin North Am (Large Anim Pract) 1983; 5: 261-274.

Convery FR. Akeson WHo Keown GH. The repair of large osteochondral defects -an experimental study in horses. Clin Orthop 1972; 82: 253-262.

Dabareiner RM. Sullins KE. Bradley W. Removal of a fracture fragment from the palmar aspect of the intermediate carpal bone in a horse. J Am Vet Med Assoc 1993; 203: 553-555.

DeHaan CEoO'Brien TR. Koblik PD. A radiographic investigation of third carpal bone injury in 40 racing Thoroughbreds. Vet Radiol 1987; 28: 88-92.

Finerman GAM. Noyce FR (eds): Biology and biomechanics of the traumatized synovial joint: The knee as a model. Rosemount 11: American Academy of Orthopedic Surgeons. 1992.

Firth EC.Deane. GibsonK. et al. Current studies in carpal diseaseand function in the horse. Vet Cond Educ. Massey University. New Zealand 1999; 135: 81-89.

Fischer AT. Stover SM. Sagittal fractures in the third carpal bone in horses: 12 cases(1977-1985). J Am Vet Med Assoc 1987; 191:

106-108.

Friedman MI. Gallick GS.Brna JA. et al. Chondromalacia of the knee: a comparison between those treated with and without intraarticular shaving. Arthroscopy 1987; 3: 131.

Frisbie DD. Trotter GW. Powers BE. et al. Arthroscopic subchondral plate microfracture technique augments healing of large chondral defects in the radial carpal bone and medial femoral condyle of horses. Vet Surg 1999; 28: 242-255.

Grant BD. Repair mechanisms of osteochondral defects in equidae: a comparative study of untreated and X-irradiated defects.

Proceedings of the 21st Annual Meeting of the America~ Association of Equine Practitioners. 1975. pp. 95-114.

Howard RD. McIlwraith CWoPowers BE. et al. Long-term fate and effects of atWetic exercise on sternal cartilage autografts used for repair of large osteochondral defects in horses. Am J Vet Res 1994; 55: 1158-1167.

Hurtig ME. Fretz PB. Arthroscopic landmarks of the equine carpus.

JAmVetMedAssoc 1986; 189: 1314-1321.

Hurtig ME. Fretz PB. Doige CE. Schnurr DL. Effects of lesion sizeand location on equine articular cartilage repair. Can J Vet Res 1988; 52: 137-146.

Johnson 11. Arthroscopic surgery principles and practice. St Louis: Mosby; 1986.

Kannegieter NJ. Burbidge HM. Correlation between radiographic and arthroscopic findings in the equine carpus. Aust Vet J 1990; 67: 132-133.

Kannegieter NJ. Colgan SA. The incidence and severity of intercarpal ligament damage in the equine carpus. Aust Vet J 1993; 70:

89-91.

Kawcak CEoMcIlwraith CWoNorrdin RW. Park RD. Steyn PS. Clinical effects of exercise on subchondral bone of carpal and metacarpophalangeal joints in horses. Am J Vet Res 2000; 61:

1252-1258.

Kawcak CE. McIlwraith CWoNorrdin RW. Park RD. JamesSP.The role of subchondral bone in joint disease:a review. Equine VetJ 2001; 33: 120-126.

Lysholm J. Hamberg P. Gillquist J. The correlation between osteoarthrosis as seen on radiographs and on arthroscopy.

Arthroscopy 1987; 3: 161-165.

Mcilwraith CWo Current concepts in equine degenerative joint disease.J Am Vet Med Assoc 1982; 180: 239-250.

Mcllwraith CWoArthroscopic surgery-athletic and developmental lesions. Proceedings of the 29th Annual Meeting of the American Association of Equine Practitioners. 1983.

Mcllwraith CW Experiences in diagnostic and surgical arthroscopy in the horse. EquineVetJ1984; 16: 11-19.

Mcllwraith CWoDiagnostic and surgical arthroscopy in the horse.

2nd edn. Philadelphia: Lea & Febiger; 1990: 33-84.

Mcllwraith CWoRadiographically silent injuries in joints: An overview and discussion. In Proceedings of 37th Annual Convention American Association of Equine Practitioners. SanFrancisco. CA 1991. pp. 785-792.

Mcllwraith CWoTearing of the medial palmar intercarpal ligament in the equine midcarpal joint. Equine VetJ 1992; 24: 367-371.

Mcllwraith, CWo Arthroscopic surgery for osteochondral chip fragments and other lesions not requiring internal fixation in the carpal and fetlock joints in the equine athlete: What have we learned in 20 years?Clin Techn Equine Pract 2002; 1: 200-210.

Mcllwraith CWoBramlage LR. Surgical treatment of joint disease.In: Mcllwraith CW, Trotter GW (eds). joint disease of the horse WE Saunders; Philadelphia 1996: 292-317.

Mcllwraith CW, Fessler]F. Arthroscopy in the diagnosis of equine jointdisease.JAm Vet Med Assoc 1978; 172: 263-268.

Mcllwraith CWoNixon AJ. Joint resurfacing: attempts at repairing articular cartilage defects. In: Mcllwraith, CW, Trotter GW, (eds) Joint disease in the horse. Philadelphia: WB Saunders; 1996: 317-334.

Mcllwraith CW, Yovich ]v; Martin GS. Arthroscopic surgery for the treatment of osteochondral chip fractures in the equine carpus. ] Am VetMed Assoc 1987; 191: 531-540.

Martin GS.Haynes PF,McClure JR. Effect of third carpal slabfracture and repair on racing performance in thoroughbred horses: 31 cases(1977-1984). J Am Vet Med Assoc 1988; 193: 107-110.

Martin GS. Mcllwraith CW Arthroscopic anatomy of the intercarpal and radiocarpal joints of the horse. Equine Vet 1985; J17: 373-376.

Mitchell N. Shepard N. Healing of articular cartilage in intraarticular fractures in rabbits. J Bone Joint Surg [Am] 1980; 62:

628-634.

Ogilvie-Harris DJ. Bauer M.. CoreyP. Prostaglandin inhibition and thE rate of recovery after arthroscopic meniscectomy. A randomized double blind prospective study. J Bone Joint Surg (Br) 1985; 67: 567-571.

Phillips TJ. Wright IM. Observations on the anatomy and pathology of the palmar intercarpal ligaments in the middle carpal joints 01 Thoroughbred racehorses. Equine Vet J 1994; 26: 486-491.

Pool RR. Meagher DM. Pathologic findings and pathogenesis of race. track injuries. Vet. Clin North Am Equine Pract 1990; 6: 1-30.

Pritsch M. Horoshovski H. Rarine I. Arthroscopic treatment 01 osteochondral lesions of the talus. J. Bone Joint Surg [Am] 1986 68: 862-865.

Richardson DW. Technique for arthroscopic repair of third carpa bone slab fractures in the horse. Am Vet Med Assoc 1986; 188 288-291.

Richardson DW Proximal surface lesions of the third carpal bone Proceedings of the 1st Advanced Arthroscopy Course. Coloradc State University. 1988.

Richardson DW. Arthroscopically assisted repair of articulal fractures. Clin Techn Equine Pract 2002; 1: 211-217.

Riddle WE. Healing of articular cartilage in the horse. J Am Vet Mec Assoc 1970; 157: 1471-1479.

Ross MW. Richardson DW. Beroza GA. Subchondral lucency of tht third carpal bone in Standardbreds racehorses: 13 case!

(1982-1988),J Am Vet Med Assoc 1989; 195: 789-794.

Schneider RK. Bramlage LR. GabelAA. Barone LM. Kantrowitz BM Incidence. location and classification of 371 third carpal bont fractures in 313 horses. Equine Vet J Supp11988; 6: 33-42.

SJ: Arthroscopic surgery: the carpal and fetlock joints.

-of the 29th Annual Meeting of the American Association of Equine Practitioners. 1983.

SJ: Intercarpal ligament impingement: a primary cause of pathology in the intercarpal joint. In Proceedings of the

dorsomedial intercarpal ligaments in the midcarpal joint.

Surg 1997; 26: 359-366.

Whitton RC. Rose RI. The intercarpal ligaments of the equ midcarpal joint. Part II: The role of the palmar intercar ligaments in the restraint of dorsal displacement of the proxil row of carpal bones. Vet Surg 1997; 26: 367-373.

Wilke M. Nixon AI. Malark I. Myhre. G. Fractures of the pair carpal bone in Standardbreds and Thoroughbreds: 155 cases aspect of the carpal bones in horses: 10 cases (1984-2000 (1977-1084). I Am Vet Med Assoc 1988; 193: 353-358.

Am Vet Med Assoc 2001; 219: 801-804.

H, Carlsten I. Retrospective study of subchondral sclerosis Wright IM. Ligaments associated with joints. Vet Clin N Am 19 and lucency in the third carpal bone in Standardbred trotters.

11: 249-291.

Equine Vet I 1999; 31: 500-505.

Young DR. Richardson DW. Markel MD. Numamaker [ AM, McIlwraith CW, Powers BE, et al: Morphologic and Mechanical and morphometric analysis of the third carpal bc biochemical study of sternal cartilage autografts for resurfacing of Thoroughbreds. AmI Vet Res 1991; 52: 402-409. induced osteochondral defects in horses. AmI Vet Res 1992; 53:1038-1047.

Yovich IV. Trotter GW. McIlwraith CWoNorrdin RW. Effects polysulfated glycosaminoglycans on chemical and physi , , McCarthy PH, RoseRI. The intercarpal ligaments of the defects in equine articular cartilage. Am I Vet Res 1987; . equine midcarpal joint, Part I: The anatomy of the palmar and 1414.

Arthroscopy has proven to be a most valuable technique in the metacarpophalangeal and metatarsophalangeal (fetlock) joints. Its original use was principally, in arthroscopic surgery in the dorsal aspect of the joint but then extended into the palmar/plantar aspect. Arthroscopic surgery in the dorsal aspectof the fetlock joint is probably the best equine example of what can be achieved with joint distention.

The same advantages that have been discussed in the carpus hold for arthroscopic surgery in the fetlock. The indications for arthroscopic surgery in the metacarpophalangeal and metatarsophalangeal joints include the following conditions: 1. Osteochondral fragments of the proximal dorsal aspectof the proximal (first) phalanx.

2. Erosions of articular cartilage and subchondral bone disease on the dorsal proximal aspect of the first phalanx.

3. Synovial pad fibrotic proliferation (villonodular synovitis) of the metacarpophalangeal joint.

4. Other forms of proliferative synovitis.

5. Osteochondritis dissecans of the sagittal ridge of the third metacarpal or metatarsal bones (McIIl/MtIIl).

6. Osteochondral fragments associated with the proximal palmar or proximal plantar aspect of the proximal phalanx.

7. Removal of apical fragments of the proximal sesamoid bone.

8. Removal of abaxial fragments of the proximal sesamoid bones.

9. Removal of basilar fragments of the proximal sesamoid bones.

10. Lesions of the intersesamoidean ligament.

11. Axial osteitis of the proximal sesamoidbones.

12. Avulsions of the suspensory ligament insertions.

13. Subchondral cystic lesions of McIIl. 14. Lesions of the dorsal plicae.

15. Chondral fractures.

16. Fibrous joint capsule tears.

17. Assistance in repair of condylar fractures of the McIIl/MtIIl and fractures of the proximal phalanx.

18. Other selected proximal sesamoid fractures.

Arthroscopic examination of the fetlock joint may be indicated specifically as a diagnostic procedure or as part of an arthroscopic surgical procedure (McIlwraith 198'4).

The latter situation is more common, although diagnostic arthroscopy is indicated in cases involving a lameness problem that has been localized to the fetlock but for which the radiographic signs are equivocal. The procedure is most valuable if synovial effusion is present or if the area of lamenesshas been identified as intra-articular on the basis of a response to intra-articular analgesia and when there has not been a responseto conservative treatment.

A complete arthroscopic examination of the metacarpophalangeal or metatarsophalangeal joint is not possible.Two arthroscopic approaches are required to achieve as effective an examination as possible of both the dorsal and palmar (plantar) components.

Each diagnostic examination will be described. Because the dorsal approach most commonly is performed on the metacarpophalangeal joint, it is described for that joint. The only difference in examination of the metatarsophalangeal joint is that it may be more difficult because of the decreased ability to maintain extension of the joint. The plantar (palmar) examination is facilitated by flexion and this is especially convenient in the hilid limb.

Arthroscopic examination of the dorsal metacarpophalangeal joint This arthroscopic examination ~an be performed with the horse in dorsal or lateral recumbency. If lateral recumbency is used. the horse should be positioned so that the site for arthroscopic entry is up. For the same reason of versatility mentioned in Chapter 4 with regard to the carpal joint. the use of dorsal recumbency is preferred. While the leg is being surgically prepared and draped. it is held by an assistant or is suspendedin a mechanical device (Fig. 5.1). Draping can be

completed with the fetlock resting back on the elbow or appropriatelysuspendedsothe joint remainsextended.

Insertion

of the arthroscope

The metacarpophalangeal joint is distended with fluid (Fig. 5.2) before making the arthroscopic portal. In this joint, distention facilitates the recognition of the correct place for the arthroscopic portal and minimizes the risk of iatrogenic trauma to the joint on entry of the arthroscopic sleeve. There are no tendon sheaths to avoid as in the carpus, and the surgeon does not have to be concerned with exact localization of structures before distention.

Distention is performed by using approximately 35 ml of fluid and inserting a needle across the dorsal aspect of the proximal sesamoid bone into the palmar pouch of the fetlock (see Fig. 5.2). Adequate distention can be recognized easily with bulging of the joint capsule on either side of the

common digital extensor tendon. The outpouching of the distended joint is more prominent lateral to the common digital extensor than it is medial to it, despite the insertion of the lateral digital extensor tendon, which ramifies over the joint capsule lateral to the common digital extensor tendon; this is penetrated when the lateral portal is created.

The site for the laterally placed arthroscopic portal is in the proximolateral quadrant created by distending the joint maximally (Fig. 5.2). A No. 11 blade is used to incise the skin and stab through the joint capsule (seeFig. 5.3). The arthroscopic sleevecontaining a conical obturator is then inserted through the joint capsule, initially perpendicular to the skin and then parallel to the articular surface of Mclll to avoid iatrogenic damage to this area (Fig 5.4). Entry is completed by advancing the sheath proximad to avoid iatrogenic damage to the midsagittal ridge of the distal metacarpus (see Fig. 5.4). The sheath can then be directed distad once over the sagittal ridge.

If the arthroscopic portal is made in the more proximal dorsal pouch, the sheath can be advanced across the joint in a transverse direction without causing damage to the midsagittal ridge of the metacarpus. The position described here for the arthroscopic portal is different than in the previous edition of this text (McIlwraith 1990a). It represents a modification initially suggested by Foerner (pers comm

1984), in that by taking the portal more proximad, it was possible to better visualize the proximal lateral aspect of the proximal phalanx.

When the arthroscopic sleeve is inserted so that its tip touches the medial capsule, the arthroscope is inserted and the examination can begin. It is easy to enter the subcutaneous tissue plane when inserting the arthroscopic sleeve in the dorsal aspect of the fetlock, and care is warranted during both the joint distention step as well as with insertion of the arthroscopic sleeve to avoid this problem. The authors prefer to use this proximal arthroscopic portal in the metacarpophalangeal joint to avoid iatrogenic damage to the midsagittal ridge of the metacarpus and to provide the best overall view of the dorsal aspect of this joint.

A more distal portal along the dorsal margin of the metacarpophalangeal joint immediately proximal to the proximal phalanx, however,can provide convenient visualization of the proximal border of the first phalanx.

As in the carpus, creation of an instrument portal and insertion of an egresscannula or probe are the next steps. A useful measure is to insert a needle at the proposed instrument portal location to check if such a site is appropriate (Figs 5.5 & 5.6). The use of aI needle to ascertain ideal positioning for the instrument portal represents a departure from what was previously described in the carpus. However, the carpus is unique and the skin incisions for the instrument portal are made prior to joint distention and insertion of the arthroscope merely to avoid entering an extensor tendon sheath. There are no such issues in the fetlock joint, or most other joints for that matter. The practice of inserting a needle to ascertain the ideal position for instrument insertion and

surgical maneuverabilityis commonto all joints other than the carpus.By making a skin incision with a scalpeland No. 11 blade.the surgeoncreatesthe instrument portal through the joint capsule(Fig. 5.7). The small egresscannula can then be inserted through this portal without the trocar. An arthroscopic examination can then commence. At the completionof arthroscopy,the skin incisionsonly are closed (Fig.5.8).

Diagnostic arthroscopy of the dorsal pouch of the fetlock Joint With slight retraction of the arthroscope and looking across the joint. the first area visualized is the proximal portion of the dorsal joint proximal to the articular cartilage of the distal metacarpus, where the synovial membrane forms a reflection (Fig. 5.9). At this transition zone,the synovium has a flap, or pad. that varies in size, and the surgeon must be familiar with the normal range (see Fig. 5.9). Synovial pad fibrotic proliferation (villonodular synovitis) manifests as an enlargement of this flap. Apart from the flap, the synovial membrane in the remainder of this dorsal area is non-villous.

The articular surface of the medial condyle and midsagittal ridge of McIIl can then be examined by rotating the arthroscope so that the lens is angled distad (Fig. 5.10). The tip of the arthroscope is then moved distad (eyepiece moving proximad) to inspect the dorsal articular edge of the proximal medial eminence of the proximal phalanx (Fig. 5.11). The synovial membrane of the dorsal joint capsule is also evaluated during these maneuvers. The synovial membrane is notably more villous as one progresses distad and villi can sometimes obscure the view of the proximal dorsal rim of the first phalanx. The synovial membrane attaches immediately adjacent to this rim, and use of instruments (including the egress needle) to allow improved inspection of the first phalanx is common practice during both diagnostic and surgical arthroscopy in this area.

Withdrawing the tip of the arthroscope further and moving i across the sagittal ridge laterally (eyepiecemoving medially permits inspection of the lateral condyle of the distal meta carpus as well as the proximal lateral aspect of the proxim~ phalanx (Fig. 5.12).

The examination just described enables recognitiol and characterization of synovial pad fibrotic proliferatiol (villonodular synovitis), other forms of synovitis, fragment off the proximal dorsal aspect of the proximal phalanx, wea lines and erosions on the distal articular surface of Mcll osteochondritis dissecans of the midsagittal ridge an condyles of Mclll, tears of plicae and joint capsule. articula components of fractures of Mclll and proximal phalanx. an subchondral cystic lesions of Mclll.

Arthroscopic examination of the palmar or plantar fetlock joint

This examination can be performed with the horse in dorsI or lateral recumbency, the position varying with th condition being operated. The authors preferred later! recumbency when operating on fragments associated wit the palmar/plantar aspect of the proximal phalanx in tb past, but now use dorsal recumbency for all evaluation~ conditions in the palmar/plantar compartment. While flexio from an assistant is sometimes needed, advantages includ less hemorrhage, convenient operating position for plant~ (palmar) chip fragments, as well as sesamoid fragmen1 and the ability to put instrument portals in either medial ( lateral pouch.

Insertion of the arthroscope

The joint is prepared for surgery and distended by placing th needle in the palmar pouch using the approach described b Misheff & Stover (1991). With the joint distended, a ski incision is made with a No. 11 blade in the proximal part (

the bulging capsule (Fig. 5.13). The arthroscopic sheath and conical obturator are inserted perpendicular to the skin initially, and then are directed distad (Fig. 5.14). The fetlock is in 30-450 flexion at this time to facilitate passage between the distal metacarpus/metatarsus and the proximal sesamoid bones. The degree of flexion is controlled by an assistant and the flexion angle varies depending on the area being examined (for instance, increased flexion is used to bring the proximal palmar aspect of the proximal phalanx into view).

Diagnostic arthroscopy of palmar (plantar) pouch of the fetlock joint Examination of the metacarpo- or metatarsophalangeal joint commences with the arthroscope perpendicular to the skin and the lens oriented proximad (Fig. 5.15). The unusual synovial membrane of the proximal recess of the joint can be visualized. Rotation of the arthroscopic lens palmad allows

inspection of the apices of the sesamoid bones and the intersesamoidean ligament (Figs 5.16 and 5.17).

The tip of the arthroscope is then advanced distad (this can be done safely if the joint is flexed and distention is maintained) to examine the articular surfaces of the sesamoid bones and the intersesamoidian ligament palmad and the articular surface of the distal palmar Mclll dorsad (Fig. 5.18).

Advancement of the arthroscope continues until the base of the sesamoids is visualized (Fig. 5.19) and. with increased flexion. the proximal palmar rim of the proximal phalanx can be noted (Fig. 5.20).

Diagnostic arthroscopy of the palmar or plantar pouch of the fetlock joint is now a commonly used procedure. Indications for arthroscopic surgery in the palmar or plantar pouch include palmar/plantar proximal fragments off the proximal phalanx. apical. abaxial and basilar osteochondral fractures of the proximal sesamoid bone, osteitis of the axial portion of the sesamoid bones and tearing of the intersesamoidian ligament. diagnostic arthroscopy for synovitis and capsulitis as well as adjunctive visualization for reduction of lateral condylar fracture of Mclll/MtlII and assessmentof associateddamage. For diagnostic examination of a capsulitis or a suspectedosteoarthritis problem. inspection of the dorsal compartment is performed initially. followed by palmar or plantar examination in most situations.

The indications for arthroscopic surgery have been previously listed.

Removal of osteochondral from the proximal dorsal

of the proximal

fragments aspect

phalanx

Before the advent of arthroscopy, surgical removal of these fragments was not routine, becausesome surgeons questioned the benefits of surgical invasion of this area with arthrotomy (Raker 1973, 1985, Meagher 1974). Now, a horse with problems referable to the fetlock joint and radiographically evident fragments associated with the proximal dorsal aspect of the first phalanx is a candidate for arthroscopic surgery.

Arthroscopic surgery can provide a faster return to full function and help minimize the degenerative changes that could possibly develop. All the advantages of arthroscopic surgery discussed in Chapter 4 relative to the carpus are equally applicable when discussing arthroscopic surgery in

Of probablyincreasedimportance is the need atraumatic surgery. The dorsal joint capsule proximal first phalanx tend to be less forgiving to

the dorsal joint capsule. and this may be difficult to ascertainfrom the radiographs.The neophytearthroscopistshou try initially to limit his casesto those involving freshacutechips that are both looselyattachedto the bone and accessible.

The location of thesefragments,as representedby one ofthe author's (C.WM.)publicationsreporting on 439 fetlockjoints in 336 horses,is givenin Tables5.1 and 5.2.

radiographic and arthroscopic manifestations of proximal dorsal chip fractures vary (Figs 5.21-5.27). There may be fresh fracture fragments or more chronic rounded fragments. The typical fragment involves the proximal eminence, but in some situations (more typical in the racing Quarter Horse), the fragments extend distad into fibrous joint Technique capsule attachments (see Fig 5.24). Frontal fractures appropriate for internal fixation are considered separatelybelow.

For all cases of proximal dorsal fragments of the proximal Most importantly, all fragments, if accompanied byclinical phalanx, the arthroscope is inserted through a proximallateral signs, are indications for surgery. The damage evident portal as previously described. The instrument andarthros arthroscopically will always be more extensive than what is approach for operating on chip fragments offthe seen on radiographs. Consequently, many referred casesareoften lateral and medial eminences respectively,are represented ones with persistent evidence of synovitis and capsulitisdespite diagrammatically in Figures 5.28 and 5.29. We recommendperform medical therapy and relatively minor fragmentation all arthroscopic surgery in the dorsal pouch of the or with only a radiographic defect off the proximal phalanx(Fig. fetlock joint with the same arthroscopic portal in the 5.25). Occasionally the fragment will be free withinthe proximal lateral aspectof the dorsal pouch. After a completediagno joint (Fig. 5.26). Uncommonly, the fragment is embedded arthroscopy, the osteochondral fragments are

in

Metacarpophalangeal and Metatarsophalangeal joints

Fig. 5.21 Removal of a small chip fragment (arrow) off the proximal dorsal medial eminence of the proximal phalanx. (A and B) Lateral-medial and DLPMO radiographs. C, Arthroscopic views before (C), during elevation (D), during removal with Ferris-Smith rongeurs (E), curetting defect. continued

If a fragment is present on the proximal lateral , it is removed first. A lateral instrument portal is

5.5). The needleplacementis lateral and midway down

M

incision, and the instruments are then placed. If a fragment is present, a medial instrument portal is -If a synovial pad fibrotic .it

can usually be removed through the same

the instrument portal is created, the tip of the must be located sufficientlyproximad to avoid damage to the arthroscope. By using the proximal .The lesion is initially evaluated with (or the egress cannula), as in the carpal joints. The .manifestations of the fragments vary conand cannot usually be predicted from the radioa fresh chip, the fracture line may be evident, the

lesion

Overall (%)

Fragments only Fragments + other fetlock lesions Fragment + carpal arthroscopy Fragment + carpal arthroscopy + other fetlock lesions

96 (28.6) 140 (41.7) 63 (18.7) 37 (11.0)

124 (39.9) 63 (20.3) 37(11.8)

336

311

Total TB,Thoroughbred;

QH, Quarter

Horse, RH, racehorse.

Source:from Kawcak & Mcllwraith 1994.

5.25).

RH (%) 87 (28.0)

TB RH (%)

62 (33.0) 93 (22.7) 19 (10.1) 14 (7.4) 188

QH RH (%)

Others (%)

25 27 44 23 119

9 (36.0) 16 (64.0)

(21.0) (22.7) (37.0) (19.3)

25

Sometimes the fragment can be recognized only as a roughening of the proximal phalanx. Occasionally,the chipis embedded in the joint capsule, and this situation can berec if the fragment projects into the joint; otherwise, such a density will probably not be found, and the final diagnosis of a capsular mass is based on the absence of a fragment on arthroscopic examination despite its presence on radiographs. Finally, fragments may already be totally free within the joint (Fig 5.26).

The grasping forceps commonly used to remove the

fragment can be moved easily and is attached only at the synovial membrane reflection. Displacement of the fragment facilitates identification and removal. Figure 5.21 illustrates the sequence of events in removing a fresh fragment, including elevation. removal with Ferris-Smith rongeurs, curetting of the defect. removal of small pieces with ethmoid forceps, and lavage. In other cases the cartilage over the fragment is intact and elevation is required to define the fragment. With larger fragments, the attachments of the fragment at the joint capsule may well be more extensive (Fig. 5.22). With mor~ chronic chips. the fragments tend to be more rounded (Fig. 5.23). Some fragments have deep attachments in the joint capsule and require more separation (proximal Fig. 5.24). In some cases.the dorsoproximal rim of the first phalanx may only show a defect on lateromedial radiographs. but an oblique radiograph will show a small

fragment.

fragments are Ferris-Smith intervertebral cup rongeurs (Fig. 5.21E). Low-profile 4 x 10 mm Ferris-Smith rongeurs have the ideal combination of strength and ability to access the fragment. As in the carpus, the use of forceps that can enclose the fragment minimizes the risk of leaving fragments in the joint. Twisting of the instrument to ensure breakdown of soft tissue attachments is carried out before withdrawal of the fragment.

The surgical manipulations to remove the fragment will depend on the arthroscopic features described above. A 10 x 4 mm Ferris-Smith low-profile rongeur forceps is used to remove a totally free chip. If a fragment is small, fresh, and has minor soft tissue attachments as ascertained by palpation with the egress cannula direct removal with forceps is also appropriate. For all chips with significant attachments, the fragment is initially freed by using a periosteal elevator. For chips that have a strong fibrous union, the elevator is used to pry the fragment off the bone. The elevator can also be used to break down capsular attachments to the dorsal aspect of the fragment. A curette is useful for more strongly attached fragments. Because of suspected sensitivity of the dorsoproximal area of the fetlock joint, the surgeon should limit removal when it has fibrous joint capsule attached to it (Fig. 5.30 and 5.31).

If a fracture line extends distad deep into the capsular attachment area and it is not displaced, surgical removal is not indicated. Fixation with a small fragment screw is sometimes indicated (seebelow).

After removal of the fragment, the defect remaining is inspected (see Figs 5.21, 5.22 and 5.30), as is the nearby area of dorsal capsule, to ensure that no fragments remain.

This latter inspection must involve palpation as well as visualization, as the fragments can merge into the capsule.

The defect commonly has some tags or raised edges of cartilage that can be removed with a pair of ethmoid or 2 x 10 mm Ferris-Smith rongeurs (the pointed nose enables these forceps to enter the narrow areas where the fragment was removed). Alternatively, a curette may be used. Debridement of the bone is done carefully with a small (2-0) curette with care taken not to cause damage to the fibrous joint capsule (Figs 5.31).

Variable degrees of articular cartilage damage on the distal metacarpal or metatarsal condylar surface may be noted. In many cases,no damage is apparent, but varying degrees of wearline formation are apparent in some cases (Fig. 5.31C) and full-thickness erosion may be seen in other cases (Fig. 5.3ID). When these lesions are more severe,the prognosis is not as favorable (Kawcak & McIlwraith 1994).

Unlessa capsular mass projectsinto the joint. it is not Also. it is not considerednecessaryor beneficialto arthroscopy in such a case has been to ascertain .' -of the radiographically apparent mass. If the

of the joint is in satisfactory condition. the progis still good with an osseous mass remaining in the

the sizeor numberof fragmentsthat can undergo surgery. The surgeon must consider bone being removed. the amount of exposed bone being left in the joint. and the amount of created by the arthroscope or instrument portals. rather to the amount of capsular attachment to the the joint is flushed with fluid by open egress cannula over the site of the defect. portals are sutured and the leg is bandaged. The is maintained for at least 2 weeks after surgery. walking commences after 1 week. With simple fresh the horses can be put into training after 6-8 weeks. horses with more extensive involvement, the contime is increased for a variable period up to after surgery, but some veterinar.As discussedin the section concerning the .-to the patient's recovery is

results with arthroscopic surgery for uncomplicated fractures are associated with severe capsulitis. wear lines. osteoarthritis. or extensive fragmentation of the proximal first phalanx. the progn!;)sis decreases accordingly. As with the carpus. surgical intervention can still improve the status of these patients. but communication to owner and trainer is important to ensure that no one is disappointed. Even with suchprecautions. however. some peoplehave short memories.

The results of arthroscopic surgery in 74 fetlock joints of 63 horses (35 Thoroughbreds and 28 Quarter Horses) over a 2-year period were initially reported by Yovich & Mcllwraith (1986). Larger numbers have replaced these data. The results of arthroscopic surgery were reported in 1994 in 336 horses with 572 osteochondral fragments removed from 439 fetlock joints (Kawcak & Mcllwraith 1994). Of these horses. 311 were racehorses. including 188 Thoroughbreds. 119 Quarter Horses. 2 Standardbreds. 1 Racing Arabian and 1 racing Appaloosa. There were 25 non-racehorses. A single metacarpophalangeal joint was operated on in 220 horses. and both metacarpophalangeal joints were operated on in 97 horses. a single metacarpophalangeal joint in 17 horses. both metatarsophalangeal joints in one horse and all 4 fetlock joints in one horse. Fragmentation of the proximal phalanx was the only lesion in the fetlock joints of 96 horses. Along

with fragmentation, 140 horses had other lesions in the fetlock, comprising 64 with wear lines. 11 with articular cartilage erosion. 15 with chronic proliferative synovitis. 4 with osteochondritis dissecans,and 45 with a combination of the above lesions. Carpal arthroscopy for the removal of osteochondral chips was performed concomitantly in 100 of these horses (Table 2).

Follow-up was available for 286 horses (85.1%): 208 (73%) returned to their previous use. of which 153 horses (73.6%) returned to the same level of performance and 55 (26.4%) returned to performance, but at a lower class; 18 horses (6.3%) developed another fragment and 60 (21 %) of horses did not return to their previous use. Of the 270 racehorses with follow-up. 196 (72%) returned to racing and 141 (51.7%) of these raced at the same or a higher level.

18 (6.6%) of the racehorses developed another fragment and 56 (21.0%) were in the failure category. Of the nonracehorse group, 12 of 16 (75%) returned and 4 (25%) did not return to their previous use at the same level of performance. The difference of return to previous use between racehorses and non-racehorses was not significant. The overall successrate in horses with fragments only returning to use was 85.9%; with fragments and other fetlock lesions. it was 75%; with fetlock fragments and carpal arthroscopy concomitantly. it was 68.6%; and with fragments plus carpal arthroscopy and other fetlock lesions, it was 80.6%.

In a third study done to examine the longevity of postoperative careers and quality of performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal osteochondral fragments from the proximal phalanx. 659 chip fragments were removed arthroscopically from 574 joints and 461 horses presented for lameness or decreased performance attributable to the chip fractures (Colon et al 2000). It was found that 89% of the horses (411/461) raced after surgery and 82% (377/461) did so at the same or a higher class; 68% of the horses raced in a stakes or allowance race postoperatively. This paper confirmed that the quantity and quality of performance was not diminished after arthroscopic treatment of dorsoproximal fragments, and that surgical removal of a chip fragment preserved the economic value of a racing Thoroughbred. allowing a rapid and successive return to racing at the previous level of racing performance (Colon et al 2000).

Horses that raced before and after surgery (258) had an average of 8.4 starts (median = 6) before surgery and 13 (median = 11) after surgery.The averagetime between surgery and first postoperative start was 189 days (median = 169); 87% of the horses racing before surgery (224/258) returned to race at the same or higher class. The average earnings per start after surgery was less than the average earnings before surgery in 61 % of these horses and greater in 32%.

Colon et al (2000) considered the 11 % postoperative failure rate to be pessimistic due to various factors. It was noted that horses that did not race after surgery tended to be older at the time of surgery and had raced more times preoperatively. They concluded that the lack of return to racing was not related to chip incidence. location or size,as these did not differ between the raced and unraced group. They

carefully measured fragment size and concluded that it did not affect post-surgical racing prognosis: 48% of the surveyed horses had at least one fragment larger than the mean and 87% of these raced after surgery. They concluded that the hypothesis that "the smaller the chip fragment, the better the prognosis" was rejected by these findings. However, they noted that it was not possible in their study to compare postoperative racing performance to arthroscopic visualization of articular cartilage health or associated intra-articular cartilage lesions. They did point out, appropriately, that usually the articular cartilage damage is not severe and can be managed medically.

Arthroscopic removal of dorsoproximal chip fractures of the proximal phalanx in standing

horses

This technique has been described and reported in 104 horses (Elce & Richardson 2002). Given skilled technique, it is feasible to perform arthroscopic surgery in the dorsal aspect of the fetlock in this fashion. However, we would only recommend it if, for some reason, general anesthesia is somehow not possible or inconvenient. Throughout this textbook, the authors recommend surgery under general anesthesia.

Erosions of articular

cartilage and

subchondral bone disease on proximal dorsal eminences of proximal phalanx As seen in the carpus, there is a spectrum of disease on the proximal dorsal aspect of the proximal phalanx ranging from separation of articular cartilage and loss of articular cartilage to degenerative disease of the subchondral bone. Previously discussed osteochondral fragments are considered to be pathologic fractures and are the end result of a gradation of microdam~ge, microfractures, and cellular death (Kawcak et al 2000). This range of lesions occur in the same locations as previously described for osteochondral fragments and the surgical management is the same.

The referring clinical signs are also similar, but radiographically there may only be a suspicion of disease.However, on arthroscopic examination, the various manifestations of articular cartilage separation (Fig. 5.32A), articular cartilage erosion (Fig 5.32B), and subchondral bone disease(Fig 5.32C and D) are encountered. Separated cartilage and bone is removed. Defective bone is debrided (larger pieces removed), and the area lavaged. The prognosis is comparable to completely separated osteochondral fragments in this area.

Treatment of frontal fractures of proximal dorsal aspect of the proximal phalanx using lag screw fixation Frontal fractures of the dorsal aspectof the proximal phalanx occur regularly. The clinical signs are very similar to other

osteochondral fragments on the proximal dorsal rim, an radiographs are used to make the definitive diagnosis. VI have encountered cases in the hind limbs bilaterally an. because of the consistent location of these fracturt involving both the proximal medial eminence and sagitt groove,a developmental predisposition may be present.

In the previous edition of this book, the use of rest w~ advocated, as these fractures can heal (McIlwraith 1990a However,since that time, caseshave beenencountered that ill not heal and continued to cause clinical signs. The recon mendation now is to provide compression of these fractur! with 2.7 mm AD/ ASIF cortical screws.

Arthroscopic surgery is performed with the norm. arthroscopic approach to the dorsal pouch and with tb limbs in extension. Examination of the joint will confirm tb presence of the fracture (Fig. 5.33). Needles are placed t ascertain ideal positioning of the screw and, after a sta incision is made in the appropriate location, a 2.7 mm hole drilled obliquely down through the fracture fragment. Tb hole is generallyperpendicular to the fracture line. Radiograpl are made to confirm appropriate positioning and that tb glide hole is beyond the fracture line. A 2.0 mm hole is cor tinued beyond this. After counter-sinking, a 2.7 mm diamete 36 mm long cortical bone screw is then placed to comprel the fracture. Debridement is then performed in the fractur line, if appropriate. The manifestations at the fracture lin will vary and sometimes no bone is required to be remove (see Fig. 5.33); other times, debridement in a comparabl fashion to a slab fracture is required.

Treatment of slnovial Rad fibrotic proliferation (vilionodular synovitis)

The condition initially designated as villonodular synoviti (Nickels et al19 76) and later describedas chronic proliferativ synovitis (van Veenendaal& Moffatt 1980, Kannegieter,199C is seen in the metacarpophalangeal joint. It involves proliferative response from the synovial pad in the proximc dorsal aspect of the joint and, therefore, the term synovic pad fibrotic proliferation (Dabereiner et al19 9 6) is preferre( The term pigmented villonodular synovitis was originall used to describe pedunculated growths forming in th synovial linings of tendon sheaths and joint in man Gaffe et c 1941). These fibrous masseswere polyp-like formations th. originated from the synovial membrane and were often pi~ mented with hemosiderin. Villonodular synovitis in human: therefore, should not be confused with enlargement of th synovial pads of the equine metacarpophalangeal joint.

Classically,the condition was initially demonstrated wit: contrast arthrography, and it has been treated successful with arthrotomy (Nickels et al1976, Haynes 1980). Neithe contrast arthrography nor arthrotomy is used anymorc because of the development of ultrasound examination i diagnosis (Steyn et al1989) and arthroscopic surgery as th treatment technique. The synovial pad of the metacarp( phalangeal joint is a fold (plica) of fibrous connective tissu located in the proximal recess of the dorsal compartment (

the metacarpophalangeal joint at the joint capsule attachment to Mcill. The synovial pad is normally 2-4 mm in thickness and tapers to a thin edge at its distal border (White 1990). Its function is unknown, but its structure and location suggestthat the pad acts as a contact interface or cushion betweenthe proximal dorsal rim of the proximal phalanx and the dorsal surface of distal third metacarpal bone (Mcill) during full extension of the fetlock joint (White 1990).

Repetitive trauma during fast exercise can result in irritation and enlargement of the synovial pad and development of clinical signs of lameness and chronic joint effusion that often resolves temporarily with rest and intra-articular medication. There is commonly radiographic evidence of bone remodeling, with a concavity at the distal dorsal aspect of Mcill, and this is suggestive of synovial pad proliferation (Fig. 5.34A). Ultrasound is now the method of choice to further define this proliferation (Fig. 5.34B). Although this condition is commonly seenin the racehorse, it has been seen in other horses not subjected to fast athletic exercise (loSasso & Honnas 1994), and in the previous edition of this text, a contrast-enhanced view of the disease in a mule was presented.

The medical records, radiographs, and ultrasound examinations have been reported in 63 horses with metacarpophalangeal joint synovial pad proliferation

(Dabareiner et aI1996). All the horses had lameness. joint effusion. or both of these clinical signs. associatedwith one or both metacarpophalangeal joints. Bony remodeling and concavity of the distal dorsal aspect of McIII immediately proximal to the metacarpal condyles was identified by radiography in 71 joints (93%) (Fig. 5.34); 24 joints (32%) had radiographic evidence of a chip fragment located at the proximal dorsal aspect of the proximal phalanx. Fifty-four joints (71%) were examined by ultrasound. The mean:t SD sagittal thickness of the synovial pad was 11.3 :t 2.8 mm.

(The authors also reported that the synovial pad was considered abnormal if the thickness was greater than 4 mm on the sagittal view. the distal margin was rounded. or hypoechoic regions were observed within the pad.) Seventy-nine percent of the horses had single joint involvement. with equal distribution between the right and left forelimb. In addition to pre-surgical diagnosis of this condition. it is also quite common to encounter thickened and enlarged synovial pads at arthroscopic surgery (usually when doing the surgery for removal of a proximal dorsal fragment from the proximal phalanx) (Mcllwraith 2002).

The surgical approach used when operating on horses with this condition arthroscopically is illustrated in Figure 5.35. The authors in most cases use a single instrument approach. A two-instrument approach has also beendescribed

(Mcllwraith 1990a. 2002). With the arthroscope in the lateral portal. the instrument portal is made medially. Dabareiner et al (1996) considered excision of a portion of the synovial pad to be necessary if it was enlarged and inelastic when probed during surgery or if hard nodules could be felt within the pad.

The mass can sometimesbe torn off by using grasping forceps that have a cutting edge(Fig. 5.36A and B). Alternatively, the mass can be severed at its base by using a flat knife (Fig. 5.36C and D) (see Chapter 2). Disposable scalpel blades should not be used because they may break within the joint.

After severing the base. the proliferated pad is removed with Ferris-Smith rongeurs (Fig. 5.36E) and the base trimmed with basket forceps or a motorized resector. Proliferation of the synovial pad is more common medially than laterally and. consequently. surgery often involves removal of the medial portion alone. However, examination should be made to ensure that there is not similar proliferation in the lateral portion. If there is. the arthroscope is placed medially and the instrument laterally to remove the lateral portion. In one report in the literature. complete or partial excision of both medial and lateral synovial pads was achieved in 42/68 joints (Dabareiner et al1996). The medial synovial pad only was excised or trimmed in 21 joints and 5 joints had removal limited to the lateral pad.

Once the pad is removed, there may be some full-thickness erosion with minor debris where debridement is indicated (Fig. 5.36F). More commonly. the bone is left alone. but if there are any elevated cartilage tags. these are trimmed. As has been previously noted. enlarged. thickened pads will

sometimes be noted when the indication for arthroscopic surgery was originally the removal of fragments. Conversely. fragments may be encountered off the proximal dorsal aspect of the proximal phalanx at the time of arthroscopic surgery for removal of a proliferated pad when the fragments were not visible with pre-surgical radiographs. Obviously, a complete examination of the dorsal pouch is done with any of these arthroscopic procedures and lesions appropriately dealt with.

In a report of 68 joints in 55 horses treated by arthroscopic surgery, 60 joints (88%) had debridement of chondral or osteochondral fragmentation from the dorsal surface of the distal metacarpus beneath the synovial pad (more frequently done than by us) and 30 joints (44%) had a bone fragment removed from the medial or lateral proximal dorsal eminence of the proximal phalanx (Dabareiner et alI996).

Arthroscopic laser extirpation of metacarpophalangeal synovial pad proliferation has been described in 11 horses (Murphy and Nixon 2001). Elevenclinical caseswere operated on in this fashion and followed up. All were treated by intraarticular laser extirpation using either CO2 or an Nd:YAG laser with arthroscopic guidance. Mean synovial pad thickness, measured ultrasonographically, was 9 Inm, and 7 (64%) of the horses had radiographic evidence of remodeling of the dorsal cortex of distal McIIl; 3 horses (27%) had concurrent dorsal proximal fractures of the proximal phalanx.

All 11 horses returned to training within 90 days of surgery without recurrence of the lesion. Nine horses (82%) sustained race training and apparently improved their performance following surgery based on follow-up conversation with the owners. The use of the CO2 laser requires gas distention of the joint. The authors cited advantages with the laser technique that included their ability to be used arthroscopically, better visualization of the joint, better access to lesions on both sides of the sagittal ridge, reduced convalescence time, and better cosmetic and functional results. However, with our current abilities at conventional arthroscopic surgery, it is questionable if these advantages exist anymore.

Postoperative management in casesinvolving proliferative synovitis treated arthroscopically is the same as for those involving chip fragments of the proximal phalanx. Horses that have synovial pad proliferation without articular cartilage loss or proximal phalangeal fragments can return to racing in 8 weeks, whereas horses with more extensive cartilage damage or more significant proximal dorsal fragmentation of the proximal phalanx should get 3-4 months before training is resumed.

Follow-up on 50/55 horses was obtained for the previously cited study of Dabareiner et al (1996): 43 (86%) horses that had surgery returned to racing, with 34 (68%) racing at an equivalent or better level than before surgery. Horses that returned to racing, at a similar or equal level of performance were significantly younger than horses returning at a lower level or not racing. In contrast, the same authors reported 8 horses (8 joints) with synovial pad proliferation and remodeling of the distal dorsal aspect of McIIl being treated medically at the owner's request. Intra-articular sodium hyaluronate was administered intermittently in these

Arthroscopic Surgery of the Fetlock Joints

8 horsesand systemicnonsteroidalanti-inflammatorymedications were also administeredfor variable periods.Three (38%)of the medicallytreatedhorsesreturnedto racing and only 1 horseracedbetterthan the pre-injury level.

Treatment proliferative

of other forms synovitis

of

Occasionally, forms of proliferative synovitis that are not localized to the dorsoproximal aspectof the joint are seen(see Chapter 3). Typically, these casespresent as chronic synovitis and capsulitis that is non-responsive to symptomatic intraarticular or systemic anti-inflammatory treatments. In some cases, diagnostic arthroscopy has revealed proliferated, thickened, and enlarged synovial villi in the dorsal compartment of the metacarpophalangeal joint (Fig. 5.37).

The treatment has been resection of these villi, and the overall results have been good.

Treatment of osteochondritis dissecans of the distal dorsal aspect of Mc111/Mt111 in the metacarpopharangeal and metatarsophalangeal joints There is a divergence of opinion as to what is considered osteochondritis dissecans (OCD)within the fetlock joint and also those entities that might be considered to be appropriate

to include in the term developmentalorthopedic disease (Mcllwraith 1993). It is undisputed that OCD of the dorsal aspect of the distal McIII and MtIII is a manifestation of OCD and this is the condition described below. The condition was initially described as OCD of the sagittal ridge of the third metacarpal and metatarsal bones (McIII/MtIII) (Yovich et al 1985). but this term has been modified after recognition that

the diseaseprocess commonly extends onto the condyles of MclII and MtlII (Mcilwraith & Vorhees 1990). These cases were evaluated and treated on the basis of having clinical signs; the problem was assessedin 65 horses (Mcilwraith & Vorhees 1990). In one radiographic study, OCD changes on the dorsal aspect of the sagittal ridge of MclII or MtIII was seen in 118/753 yearling Standardbred trotters with 61 forelimbs and 147 hind limbs affected (GroendahI1992).

Fragments from the proximal palmar/plantar margin of the proximal phalanx have also been reported as osteochondrosis (Foerner 1987, Nixon 1990), but it is not now generally accepted that osteochondrosis is the pathogenesis. The treatment of this condition is described later in this chapter.

The third condition described as OCD are proximal dorsal fragments of the proximal phalanx in young horses. While these fragments, at least in racehorses, have long been consideredto be traumatic in origin, there is evidence some of these fragments having an osteochondrosis basis, at least when they present in yearlings. The treatment of these conditions is also described in this chapter. Dorsal bony fragments in the metacarpo- and metatarsophalangeal joints were diagnosed in 36 (4.8%) of 753 yearling Standardbred trotters on a radiographic survey (Groendahl19 92) and were seen in 34 forelimbs and 14 hind limbs. A fourth condition initially described as OCDof the palmar metacarpus (Hornoff et a11981) is now accepted to be a traumatic entity and not a syndrome of osteochondrosis. It will not be considered further here, as it is not an arthroscopic surgical condition.

Osteochondritis dissecans of the distal dorsal aspect of the MclII/MtlII can occur in both metacarpo- and metatarso- ! phalangeal joints, but it is more common in the latter. The.' lesions vary in their radiographic manifestations, from a I subchondral defect to defects associated with fragments; (Fig. 5.38). In some cases,fragments break away completely from the primary lesion and become loose bodies. The presenting clinical signs include synovial effusion of the fetlock joint with or without lameness.The horses are usually yearlings (Yovich et al1986). In most instances, the patients are weanlings to yearlings and quite often are presented for treatment prior to sale. In some instances, training and

racing may have occurred before the symptomsdevelop.

Although the degree of lameness varies, a positive response to a fetlock flexion test is usually elicited, and radiographs i confirm the presence of lesions associated primarily with the sagittal ridge of MclII/MtIlI. ;

For purposes of treatment decision and prognosis, the j lesions have been divided into three types: .Type I is that in which a defect or flattening is the only visible radiographic lesion .Type II is that in which fragmentation is associated with the defect .Type III is that in which there is a defect or flattening with or without fragmentation plus one or more loose bodies.

Oblique radiographs should be taken as well as dorsopalmar (plantar) and lateral/medial radiographs for the purpose of discerning the medial or lateral condyles of MclII/MtlIl (Mcilwraith & Vorhees 1990). Based on an initial study

Fig. 5.38 Examples of the radiographic appearance of osteochondritis dissecans (OCD) of the fetlock joint (A) Type I OCD of the midsagittal ridge of the metatarsophalangeal joint. (B) Type II OCD. (C) Type III OCD.

Yovich et al19 85), it was felt that Type II and Type III OCDesions should be treated surgically and many Type I lesionsrvould resolve, In a second study of 15 cases with Type Iesions that were treated conservatively, 12 resolved clinicallymd 8 of these showed remodeling of the lesions with mprovement on radiographic examination (Mcilwraith &torhees 1990), In 3 casesthe clinical signs persisted: in 2 of hese, the radiographs showed no ch~nge and the horses :ventually underwent surgery, whereas, in the other case,the :linical and radiographic signs progressedand the horse was lot operated on, In 8 cases of Type II lesions where owners requested:onservative management, 2 eventually underwent surgery)ecause of the persistent clinical signs, Clinical signs)ersisted in 5 others, but surgery was not performed, The :linical signs improved in only 1 horse, In most of these casesrvhere clinical signs persisted, the fragmentation also)rogressed radiographically. It was also clear in this study :hat clinical signs of effusion may appear before definitive:adiographic changes. Progression of someType I lesions wasloted: such casesdo not develop osseous fragmentation, but:he lesions progress to become larger defects, particularly on:he condyles (seen on oblique view radiographs). Some cases Jf Type II lesions improved radiographically. These were ~enerallycaseswith small fragments that fused to the parent-Jone such that a spur resulted.

Based on the above knowledge, arthroscopic surgery is;onsidered the appropriate treatment if fragments are ~resent (Type II and III lesions). In other cases in which a lefect only is detectable radiographically, the decision for ;urgery is based on the degree of clinical signs, the size and ocation of the defect, and the planned use of the horse.

The arthroscopic approach is the same as that forragments off the proximodorsal aspect of the proximal Jhalanx or synovial pad proliferation, using a proximally or listally placed instrument portal, depending on the location Jf the fragment or loose body (seeFig. 5.39). When operating In metatarsophalangeal joints, an effort must be made tolchieve complete extension. In some cases,the OCD lesionllanifests as a defect within the sagittal ridge (Fig. 5. 40A and B),and curettage is performed. More commonly, osteochondralragments may be within the defect or have loose attach-llents to the area (Fig. 5.40C-E). In these cases,the fragment s removed and any defective articular cartilage is debrided:Fig. 5.40F). Loosefragments are located and removed (usually with Ferris-Smith rongeurs). As mentioned previously,Ilndermined (Fig. 5.43B). But in most instances. there will be a rounded cartilage may extend medial and lateral from the fragment (Fig. 5.43C and D). Rarely,extensive fragmentation ,agittal ridge of McIlI and MtlII, and it must also be debrided.JCDmay be present (Fig. 5.43E-G). can also occur on the metacarpal or metatarsal condyles:Fig. Aftercare in these casesis the same as for a chip fragment 5.41). Type III lesions are treated with fragment removalmd off the proximal dorsal aspectof the proximal phalanx. Many debridement (Fig. 5.42). of these horses are young and therefore have long periods for Diseaseand fragmentation of the proximal dorsal aspectofthe convalescencebefore being put into training. proximal phalanx typical of OCDis seenquite commonlyIn The prognosis is based on the appearance of the joint young horses. The radiographic manifestations are of a during surgery as well as on the age of the horse. If there is ,mall fragment on the proximal dorsal aspect of the proximal no other damage or only a minimally sized defect in the phalanx (Fig. 5.43). The arthroscopic manifestations can sagittal ridge, the prognosis is good. Follow-up data reveal vary, as illustrated in Figure 5.43. In some instances, there that when extensive lesions extend medial or laterad from the will be a flap with diseasedbone underneath, typical of OCD sagittal ridge or distad to involve the loaded area of the

articulation. clinical problems may arise when the horse engages in athletic activity.

In a series of 42 horses that were operated on with arthroscopic surgery. there were a few Type I lesions (usually operated on as they had not responded to conservative treatment or if an individual joint in a horse being treated for a Type II or Type ill lesion happened to have a Type I lesion).

Forty-two horses in this series reported included 20 Thoroughbreds. 8 Quarter Horses. 7 Arabians. 4 Warmbloods.

1 Standard bred. 1 Percheron. and 1 Appaloosa (McIlwraith & Vorhees 1990). Forelimbs were involved in 10 horses. hind limbs were involved in 15 and both fore and hind limbs were involved in 17 horses. One fetlock joint was operated in 10 horses. 2 fetlocks in 17 horses. 3 fetlocks in 1 horse. and 4 fetlocks in 14 horses. Forty-eight cases involved the proximal 2 cm of the sagittal ridge. where 11 extended distal to this point. In 44 instances. lesions involved the lateral and/or medial condyles of the metacarpus or metatarsus. with or without lesions of the sagittal ridge.

Of the 42 horses operated on. follow-up was obtained in 28. eight horses were convalescing and in 6 the follow-up

was unavailable. Surgery was successfulin 16 (57.1 %) of the 28 cases and 12 were unsuccessful (42.8%). Of the 12 unsuccessful cases. 7 were still considered to have a problem in the fetlock joint (25%): 3 were unsuccessful for other reasons; 1 was unsuccessful for unidentified reasons but was considered to be normal in the fetlock joint; and 1 horse died.

The successrate was also found to be related to other factors.

There was a trend for the successrate to be higher for surgery in hind limbs compared to forelimbs. On the one hand. in the forelimbs only 2 cases were successful and 6 were unsuccessful.whereas in the hind limb 7 were successfuland 3 were unsuccessful. When both fore and hind limbs were involved. there were 7 successesand 3 failures. Type III lesions had 4 successesand 4 failures. whereas Type II lesions had 10 successesand 4 failures (difference not statistically significant). Only 3/12 cases with erosions or wear lines present at arthroscopy were successful. whereas 13/16 with no erosions were successful (p = 0.0029). Probably related to that. there was a significantly inferior result when a defect was visible on the condyle on oblique radiographs. When a defect was visible. 6/13 were successful. whereas if a defect was not visible. 10/15 were successful (p = 0.0274). Osteophytes were also negative prognosticators (3/9 with osteophytes on the proximal phalanx were successful. whereas 13/19 with no osteophyteswere successful).

It was concluded that surgical management of Type II and Type III lesions will allow athletic activity in a fair number of cases. but clinical signs will persist in 25%. Whether the surgery will be successfulor not will be affected by the extent of the lesions. as evident arthroscopically (and in some instances. radiographically). as well as by the presence of osteophytes.erosions. and wear lines. Since the Mcllwraith & Vorhees (1990) paper was published. the first author feelsthe success rate has improved further because of earlier intervention and. particularly with radiographing horses at a young age to ensure clean joints at yearling sale.

I

'

Debridement of subchondral cystic lesions of the third metacarpal bone The distal Mclll is one of the less common locations for subchondral cystic lesions. but they do occur with relative

regularity (Nixon 1990, Mcllwraith 1990b). Most horses are aged 2 years old or less when clinical signs become apparent and they usually have a history of recently increased physical activity (such as entering athletic training). The diagnosis is confirmed with radiographs (Fig. 5.44A and B). As with most

subchondral cystic lesions. they occur in a location subject to maximal weightbearing during the support phase of the stride. Once a cystic lesion becomes clinically apparent. the prognosis for athletic soundness is variable and appears to be dependent on several factors. including the anatomic location of the lesion. the presence of any associated degenerative changes in the joint and the treatment regime (surgical or conservative) chosen (Bramlage 1993).

Prior to the use of arthroscopic surgery. most caseswere managed conservatively and empirically and with limited success (Mcllwraith 1982). If conservative therapy was not successful. a dorsal arthrotomy was recommended surgically to debride the lesion and this technique has been more recently replaced by arthroscopic surgery. The technique is less invasive and provides the advantage of clear visual assessmentof the articular surfaces of the joint.

The arthroscopic approach depends on the location of the cystic lesion. The majority of lesions are on the medial condyle of the distal metacarpus. in which case the arthroscopeand the instrument are both placed medially (Fig. 5.45).

In order to expose the opening of the subchondral cystic lesion. flexion is required. and so having the arthroscope on the same side obviates the potential problem that flexion creates (sagittal ridge interfering with the arthroscopic position). The arthroscope is placed laterally for a cystic lesion on the lateral condyle or the sagittal ridge. With flexion. the opening of the cystic lesion can be visualized (Fig. 5.44). A needle is used to ascertain the ideal position for debridement; this tends to be distal and axial over the cystic lesion. The cystic lesion is then debrided with a curette and pieces removed with forceps. The cartilaginous edges are trimmed and debris removed by flushing. Drilling of the cystic lesion is no longer performed.

A 4-6-month lay-up period is recommended with these cases.The initial 2 months involve stall confinement with a program of hand walking. A seriesof caseshave beenreported (Hogan et al1997) and serve as a basis for prognosis. Subchondral cystic lesions (SCLs) in the distal McIIl were surgically treated in 15 horses. The median age at presentation was 18 months (range 10 months to 12 years) with lOllS horses less than 2 years old. The SCLswere confined to the front limbs in all cases. with two horses having bilateral lesions. Lesions were isolated to the medial condyle of McIIl in 13 I 15 horses; a cystic lesion occurred in the lateral condyle in 1 horse and in the sagittal ridge in another. One horse with bilateral lesions had an additional cystic lesion located in the right medial femoral condyle. Fourteen of 15 horses had a history of moderate lameness attributable to the metacarpophalangeal joint; the lesion was an incidental finding in 1 horse. Duration of lameness ranged from 4 weeks to 8 months and was either acute in onset or occurred intermittently and was associated with exercise. Fetlock flexion significantly exacerbated the lameness in all cases. Synovial effusion was absent in 8 (53 %) of cases.

Cystic lesions were curetted arthroscopic ally in 12 horses. and through a dorsal pouch arthrotomy in 3 horses.

Concurrent osteostixis of the cystic cavity was performed in 7 of the horses. 12/15 horses (80%) were sound for intended

usefollowing surgery. 2 horses did not regain soundnessand follow-up information was unavailable in 1 horse. The total period of follow-up was 1-6 years. Follow-up radiograph examinations were available for 9 horses. Mild periarticular osteophyte formation and enthesophyte formation at the dorsal joint capsular attachments was present in 5 of the 9 horses.Bony infIlling of the cystic lesion was detectable in 8 horsesand enlargement of the cystic cavity was observed in 1 horse. Based on this study, it would appear that surgical treatment of SCLs in the distal McIlI should result in a favorableoutcome for athletic use (Hogan et al1997).

result of fracture rather than a manifestation of osteochondrosis.

The principal radiological sign is that of a fragment located between the base of the sesamoid bone and the proximal aspectof the proximal phalanx; it is usually halfway between the sagittal groove and the lateral or medial eminence of the first phalanx and is not always associated with a defined defect on the first phalanx. Although initially the condition was considered peculiar to the Standardbred (Pettersson & Ryden 1982), cases occur in Thoroughbreds and the condition is reasonably common in Warmblood breeds.

Typically, the horses will be admitted with a history of Removal of axial osteochondral lameness. Lameness at examination will be mild and. fragments of the proximal commonly, the history is that of subtle lameness reported by palmar or plantar aspect of the the trainer and manifested at high speed as a rough gait or break in stride (Fortier et al199 5). In one series of casesof 82 proximal phalanx horses receiving lameness examination at admission. 17 These fragments, described as Type 1 osteochondral frag(21 %) horses had slight to moderate positive results on hind ments of the palmar-plantar aspect of the fetlock joint limb flexion. Synovial effusion of the metatarsophalangeal or (Foerner 1987), were initially reported as chip fractures metacarpophalangeal joint was reported in 19/119 (16%) of (Birkeland 1987) and avulsion fractures (Pettersson& Ryden horses; 155/164 (95%) fragments were in the metatarso1982). Since that time, Foerner (1987) suggested that this phalangeal and 9/164 (5%) involved the metacarpophalangeal condition is another manifestation of osteochondrosis based joints. The medial plantar eminence of the proximal phalanx on its incidence and age of occurrence of the fragments. was the location of 114/164 (70%) fragments. Bilateral fragHowever,more recent publications have argued for a traumatic ments were observed in 21 (18%) horses. whereas 15 (13%) etiology.Hind limb fetlock joints with plantar osteochondral horses had concurrent medial and lateral lesions within the fragments were collected from 21 horses (17 Standardbred same joint. Standardbred racehorses represented 109 (92%) trotters, 4 Swedish Warmblood riding horses) and the of those affected (Fortier et al 1995). In another series of morphology of the osteochondral fragments in adjacent 26 cases.23 of the horses were racing Standard breds and 3 tissues studied by dissection, high-resolution radiography, were racing Thoroughbreds (Whitton & Kannegieter 1994). andhistology (DaIin et al 1993). The fragments were attachedto The most common reason for presentation in this series was the short s~samoidian ligaments and had a smoothcartilage an inability to run straight at high speeds. Only 8 horses coverin'g on the surface facing the joint cavity. presented for lameness. although on examination, 19 were Histologydid not show any evidence of osteochondrosis. Theauthors lame. A positive flexion test was recorded in 90% of affected suggested that plantar osteochondral fragments arethe fetlock joints and effusion was present in 48%. result of an outwardly rotated hind limb axis and subTo be considered a surgical candidate, the patient must sequent point loading in the medial fetlock area. Repeated have demonstrable lameness referable to the fetlock, in high tension loads in the short sesamoideanligaments maycause addition to a radiographically demonstrable fragment fragments of tissue with osteogenicproperties to avulse (Fig. 5.46). The fragment can be identified on the lateral and from the proximal phalanx into the ligament, later forming flexed lateral views. Dorsoplantar radiographs taken with the osteochondralfragments. This pathogenesisdoes not accountror fetlock flexed have also beenrecommended (Birkeland 1972), lateral fragments, which also occur occasionally. Other but the authors have not used this technique. For optimal work by the same authors had shown that plantar osteo-chondral definition of the location of the lesion. however, a special fragments most often occur in the hind limbs andare oblique view with the tube at a 300 angle distad is useful more frequently in the medial part of the joint (Sandgren (Fig. 5.46B). Both oblique views are essential as lesions can ~t al 1993). It has also been demonstrated that thesefragments be biaxial. develop early in life and are often possibleto detect Non-surgical treatment usually lowers the horse's ~yradiography before 3 months (Carlsten et aI1993). performance (Barclay et al 198 7). Arthroscopic surgery is A second study had beendone on osteochondral fragmentsrom now the standard technique. Dorsal or lateral recumbency the axial proximoplantar/proximopalmar region of the can be used. The authors prefer dorsal recumbency as the ?roximal phalanx in 38 joints in 30 horses: 28/30% of thelorses instrument portal can conveniently be made laterally or were Standardbreds and 28/30 had a low-gradeameness. medially. However. some flexion of the joint from an assistant All but one of the horses had hind limb involve-Dent.may be required. If the surgery is done in lateral recumbency, Of 143 fragments removed, 71% involved the medial the side where the fragment is located should be up and the lspect of the joint and had to be dissected from a covering of:ynovial arthroscope and instrument approaches will be made from tissue (Nixon & Pool 1995). The histologic appearthe same side. The arthroscope is placed in the plantar orpalmar Lncein these cases suggested that these fragments were a joint pouch. as previously described. after distending

\

The arthroscopeis positionedto visualizethe distal the joint; an assistantmay facilitate this step by flexion on the joint. After assuring the correct portal is made distal to the arthroscopic , .5.47). The portal is made so that the comes across transversely. Often, the fragment

can aid visualization.The fragment separatedfrom the soft tissue with a knife and is by using a Ferris-Smithcup rongeur (Fig 5.48). of this fragment leavesa defect within the joint and short-digital sesamoideanligaments,and any --

plantar defect in the normal phalanx is appropriatebut is not usually necessary.Figure and Figure 5.50 illustrates medial and lateral condition is one of the few in equine arthroscopic for which the use of sharp dissectionis essential. used,including a tenotomy

knife. a banana knife. a narrow bistoury. and an ArthroLokTMretractable blade. We prefer a broad. flat blade. The disposable No. 11 blade should not be used because of the risk of breakage. Electrocautery probes have been used more recently for this dissection (Boure et al1999).

The immediate postoperative care is the same as for other arthroscopic procedures in the fetlock joint. A period of 2-3 months rest before training resumes is recommended.

There have been two reports of treatment of these osteochondral fragments with follow-up. Whitton & Kannegieter (1994) reported on 21 horses.in which 16 horseshad returned to racing: 12 horses had improved their performance. while 3 horses showed no improvement. and 1 horse was retired for other reasons. Degenerative changes within the fetlock joint were detected at surgery in 8 horses. Four horses were treated conservatively: 1 horse returned to its previous level of performance temporarily after intra-articular medication.

1 horse showed no improvement. and 2 horses were resting at the time of the report.

A larger case series of 119 horses (109 Standardbred horses)had follow-up in 87 racehorses and 9 non-racehorses (96). In 55/87 (63%) racehorses and 100% of 9 non-

racehorses,performance returned to preoperative levels aft surgery. Fragment numbers or distribution and concurre OCD of the distal intermediate ridge of the tibia or tars osteoarthritis were not significantly associatedwith outcom Abnormal surgical findings, consisting of articular cartila: fibrillation or synovial proliferation, were significant (p <0.001) associated with adverse outcome: these findin were documented in 31 % of the 32 horses without success outcome and only 2% of the 55 horses with successfulou come (Fortier et al1995).

Arthroscopic excision of these fragments has bel describedin 23 Standardbred racehorsesusing electrocaute probes (Simon et al 2000). A 1.5% glycine solution in i

Arthropump was used to maintain joint dissectio

Transection was performed using loop probes alone ( alternatively, with hook electrocautery probes to dissect tI fragment free prior to Ferris-Smith rongeur removal. Thirt five fragments in 28 joints were removed from either the 11 or the right hind limb in 23 Standardbred racehorses. Six hi biaxial fragmentation. An ipsilateral (n = 9) or contralater (n = 26) triangulation approach was used. The autho concluded that the loops and probes can be safely used excise osteochondral fragments of the plantar proxim phalanx. They considered dissection using electrocaute probes to be more precise and easier to perform than tI previously described sharp dissection technique. No folIo, up was given. It has since been recognized that glycine is n necessary for this procedure.

Removal of fragments sesamoid bones

of the proximal

Osteochondral fractures amenable to removal occur at tl apical, abaxial, and basal margins of the proximal sesamo bones. Arthroscopic techniques for the removal of the fragments have been developed. Previous dogma had pr posed limitations of fragment removal based on the size the fragment and the degree of attachment to the suspenso and distal sesamoidian ligaments. However, current folio, up on the first author's cases that have been treated arthr scopically suggest that limitations should be redefined. i a generalization, the hypothesis that the prognosis w decrease with greater involvement of both bone and s( tissue attachments is still valid. but the actual proportions a higher than previously thought.

The diagnosisof sesamoidfractures is made radiographicaJ (Fig. 5.51) and special views are used to clearly delineate tl abaxial involvement. Arthroscopic surgery for the removal sesamoid fragments is performed with the horse in eith lateral or dorsal recumbency (the authors prefer the latteJ The technique for an apical sesamoid fragment is illustratl in Fig. 5.52. The arthroscope is placed in the most proxim portion of the palmar or plantar pouch of the fetlock joint all cases. With partial flexion of the joint, a needle is used ascertain the ideal placement for the instrument portal. T] instrument portal can be ipsilateral or contralateral, aJ both techniques are illustrated in Figures 5.53 and 5.5

Sharp dissectionis used to separatethe apical from the suspensoryligament using a flat blade. .blade (Foerner-Scanlanelevator)is used to the abaxial attachment (seeFig. 5.53). of the fragment, it is removed with Ferris(see Fig. 5.53). Soft tissue attachments are with basket forceps or a motorized resector. The debrided with a curette. Fragmentation of apical -more than 1/3 of the articular surface considered ideal candidates for surgery. Apical fragments in foals can be treated in the same 5.55). arthroscopic approach is used for surgery on fragments. Case selection can sometimes be a -~ radiographs (Fig. 5.56) do not clearly an abaxial fracture as articular. then a "skyline" '. view should be taken (Palmar 1982). approach is illustrated in Fig. 5.57. Sharp

dissection with the flat blade is limited to severing the suspensory ligament attachments (see Fig. 5.56C). It is important that the instrument portal is made appropriately distad so that the knife can sever the suspensory ligament attachments from the abaxial fragment. After removal. the bone and cartilage are debrided with a curette. A motorized resector is used to debride the suspensory ligament tags.

Fragmentation of both the apex and abaxial region of the sesamoid bone can occur concomitantly (Fig. 5.58). The arthroscopic technique for these fragments is the same as for removing them independently. Generally. the abaxial fragment is removed first. followed by the apical fragments (Fig. 5.58B-D).

Basal sesamoid fragments are candidates for arthroscopic removal when no other pathologic changes are present in the fetlock joint (at least on radiographs) (Fig. 5.59). A reasonable number of fragments are of sufficiently small size that their removal does not compromise the distal sesamoidian ligament attachments. The exact size limitations have recently been defined (Southwood et al 1998).

'hetechnique is illustrated in Figure 5.60. Both ipsilateralnd horses raced after surgery. Small fragments were classified contralateral arthroscope and instrument positions areossible. with a proximodistal length less than 10 mm or less than The arthroscope is placed in the same fashion as for 25% of the sesamoid bone, and large fragments had a llrgery on apical and abaxial fragments. The instrument is proximodistallength more than 10 mm or more than 25% of rought in below the base of the sesamoid bone. Sharp the sesamoidbone (Southwood et al2000). issectionis used to sever the fragments from the capsularnd In a series of 47 cases of arthroscopic removal of abaxial distal sesamodian ligament attachments. The defects are fragments from the proximal sesamoid bone. follow-up len debrided (bone and soft tissue) and the joints lavaged~ig. information was obtained for 41 horses (35 racehorses. 6 5.59 and 5.61). non-racehorses). Twenty-five of 35 (71%) racehorses were The resultsof apical, abaxial, and basal sesamoidfragments, able to return to racing (16 in the same class, 9 in a lower ~spectively,have been documented recently. On reviewingle class); all 6 non-racehorseswere able to return to performance results of 82 cases of apical fractures of the proximal~samoid at the same level. Horses with small fracture fragments or bone of horses, follow-up data were obtained for 54~cehorses: fractures involving the abaxial surface of the proximal 36/54 (67%) horses returned to racing, 28 sesamoidbone only had a more favorable outcome compared 52%)in the same class and 8 (15%) in a lower class; 14/18 with horses with large apical-abaxial fractures (Southwood 78%)horses with small apical fractures returned to racing,1 et aI1998). in the same class and 3 in a lower class. 11/19 (58%) withIrge There were 10 (21 %) Grade 1 fractures, 23 (49%) Grade 2 apical fractures returned to racing and all raced in thewe fractures and 14 (30%) Grade 3 fractures. All 5 horses with class; 11/17 (65%) horses with apical-abaxial fractures~turned Grade 1 fractures returned to racing (4 in the same class and to racing, 6 in the same class and 5 in a lower class.

1 in a lower class).Twelve of 18 horses with Grade 2 fractures ic the horses that had raced before surgery, 33/40 (83%) returned to racing (9 in the same class and 3 in a lower class).

Eight horses with Grade 3 fractures returned to racing (3 inthe Therehas also beena report of the use of electrocautery same class and 5 in a lower class). Four racehorses had probesin arthroscopicremoval of apicalsesamoidfracture not raced prior to surgery; 2 of these horses raced after fragmentsin 18 Standardbredhorses(Boureet al 1999). The surgery.and 2 did not race before or after surgery. Compared fracture fragmentswere approachedthrough an ipsilateral with horses with large fragments. horses with smallfragments (3) or contralateral(15) arthroscopictriangulationtechnique. returned to racing in the same class more often; Distentionof the joints was achievedusing a 1.5%glycine however.the differences were not significant. solutionand the suspensoryand intersesamoidianligament The results of arthroscopic removal of fracture fragments attachmentsto the abaxialand axial margins of the apical involving a portion of the base of the proximal sesamoidbone fragmentweretransectedusing a hook electrocauteryprobe. have also been reported (Southwood & Mcilwraith 2000).

Subsequently.the palmar (plantar) soft tissue attachments There were 24 racehorses and 2 non-racehorses. Twelve weretransectedwith a loop electrocauteryprobe.After being (50%) of the racehorses returned to racing and started in at freed of soft tissue attachments,the apical fragment was least2 races; 8/14 of horses with Grade I fractures (~ 25% of removed with Ferris-Smith intervertebral disc rongeurs. the base involved) and 4/10 with Grade n fractures (>25%.

Eighteenapical sesamoidfragmentswere removedfrom the but < 100% of the base involved) had a successfuloutcome; left (8) and right (8) hind limbs and the left (1) and right (1) 10/16 without associated articular disease had successful forelimb. Apical fragments occurred in 15 lateral and 3 outcomes compared with 2/8 with associated articular medial proximal sesamoidbones.It was proposedthat the disease.However. fragment size and presence of associated electrocauteryprobemade an easyand precisedissectionof articular disease were not significantly associated with all softtissueattachments;10/14 horsesreturned to racing outcomes (probably related to the relatively low numbers). It (7/9 horsesthat racedbefore surgeryraced again and 3/5 wasconcluded that horses with a fracture fragment involving horsesthat had not racedbeforesurgeryraced afterwards). a portion of the base of the bone removed arthroscopically Figure 5.61G illustrates the use of an ArthrexTMelectrohave a fair prognosis for return to racing. cauteryprobeto removea basalsesamoidbonefragment.

Axial osteitis of the proximal sesamoid bones and fraying ofintersesamoidean ligaments with detachment from proximal sesamoid bone Casesof this have beenrecognizedand treated arthroscopically.

Arthroscopic surgery in 5 cases (out of 8 seen) has been reported (Dabareiner et al2001). Typically. the horses present because of lameness and they mayor may not have synovial effusion (6/8 in the casesreported by Dabareiner et al2001).

Two cases had diffuse cellulitis and effusion of the digital flexor tendon synovial sheath. All horses had osteolysis of the axial border of the proximal sesamoid bone on radiographs.

In 5 horses. arthroscopy of the palmar or plantar pouch of all the metacarpophalangeal or metatarsophalangeal joint and of the digital sheath was performed. In the remaining 3 horses. only the palmar or plantar pouch of the metacarpophalangeal or metatarsophalangeal joint was examined. Damage to the intersesamoidian ligament was seen in all horses and consisted of discoloration. fraying. and detachment from the associated proximal sesamoid bone. Osteochondral fragmentation and osteomalacia involving the axial borders of the proximal sesamoid bone was also seen in all joints. After debridement, the palmar or plantar pouch of the affected joint communicated with the distal synovial sheath through the disrupted ligament. Figure 5.62 illustrates the radiographic and arthroscopic manifestations of such a case.

Follow-up information was obtained for all horses. All 5 horses without evidence of sepsisreturned to their previous use with the median recovery time of 9 months. However, one of these horsesremained Grade 1/5 lame and radiographs obtained 1 year after surgery revealed secondaryosteoarthritis of the affected metacarpophalangeal joint. Two horses were radiographed 12 months after surgery revealing remodeling of the sesamoid bones with a smooth contour to the axial margins of the sesamoidbone.

Instances of focal bone disease involving the sesamoid bones have been encountered elsewhere. The pathogenesisis unknown, but areas of focal subchondral bone diseaseoccur and have been treated with debridement of defective tissue (Fig. 5.63).

Arthroscopically assisted repair of lateral condylar fractures of the distal Mclll and Mtlll

Arthroscopy allows an optimal means of assessing and repairing lateral condylar fractures. The use of the arthroscope I allows verification of articular alignment as well as , compressionof the fracture and a completediagnostic examin- i ation of the joint. With correct technique. even displaced fractures can be accurately reduced and repaired without a ': large surgical exposure (Richardson 2002).

Arthroscopic Surgery of the Fetlock joints jยงZ

cif!!D

evaluation of the horse to detect axial

Fig. 5.64). A complete set of radiographs dorsopalmar/dorsoplantar projections to

(CWM & IMW) perform surgery with the recumbency while one (AJN) uses lateral !\ tourniquet is not used. After surgical pre:lraping. needles are placed and a radiograph ,0 ascertain the ideal positioning of the screws (Fig. 5.65). The fracture is inspected arthroscopically (Fig. 5.66). An alternative technique for ascertaining the position of the distal screw on the radiograph by bisecting an imaginary line extending from the palmar/plantar wing o the proximal phalanx to the palmar dorsal edge of the condyle has been described by Richardson (2002). A No. 10 scalpel blade is used to make a 1 cm incision over the latera] condylar fossa for the initial glide hole. A 4.5 mm glide hole is drilled to the fracture plane (Fig. 5.67). A 3.2 mm hole is drilled beyond this (Fig. 5.68) and. after light countersinking, a 52 or 54 mm4.5 mm diameter cortical bone screw is placed to compress the fracture (Fig. 5.69A). Additional screws are placed proximally as appropriate for fracture length (Fig. 5.69B & C). One author (AJN) prefers 5.5 mm diametel screws for all condylar fracture repair. with 4.5 mm screws occasionally used for the most proximal screw in a lon~ condylar fracture.

With displaced fractures it is important to not drill thf glide hole into the parent bone. Large AO/ ASIF reductiolJ forceps are used to reduce the fracture (Fig. 5.70). Thf arthroscope is then placed in the dorsal pouch and used t( monitor the reduction of the fracture. The forceps are place, at or above the level of the physeal scar. Usually a combi. nation of varus/valgus stress. dorsal flexion and sligh! internal rotation reduces the fracture (Richardson 2002) When reduction is perfect. the fracture is clamped again It is important to ensure reduction of the fracture using ~ palmar arthroscopic examination as well. The palmar/plantaJ approach is very useful in reducing displaced fractures. Th( arthroscope can be advanced into the fracture gap to visualis( and remove fragments inhibiting reduction. After reduction screws are placed in the same fashion as described for ~ nondisplaced fracture. Figure 5.70 shows a displacedcondylaJ fracture before and after reduction.

A second reason for the examination of the palmar 0] plantar aspect of the joint is that varying degrees of con comitant injury to the proximal sesamoid bones can OCCU Debridement of cartilage erosion on the sesamoidfollowed bJ microfracture may be necessary.Severedamage is considerel a negative prognosticator. It is not possible to obtain a goO examination of the distal palmar aspect of the metacarpus Fragments and debris that result from distal palma] comminution of the fracture are removed following elevatioI with a probe or small curette. Prior to reduction. ever~ attempt should be made to remove comminuted fragment from the fracture line in displaced fractures since this wi! reduce the possibility of ideal fracture apposition.

Horses with non-displaced fractures typically have a 4-month lay-up period. Screw removal varies between different surgeons but in general. only screws that cross tubular corticesneed to be removed.There have beentwo recentstudieson the prognosisfor lateralcondylarfractures (Bassage& Richardson1998. Zekaset aI1999). Horseswith non-displacedcondylarfractureshavean excellentprognosis for returning to athletic function. The prognosisfor those with displacedfracturesis poorer.

The study by Zekas et al (1999) correlated condylar fracture characteristics and type of treatment with subsequent capacity for athletic activity, as well as determining the chacteristics of healing that affect prognosis after repair of fractures of the third metacarpal/tarsal condyles; overall, 65% of horses started in a race post-injury, in a mean time of 9.7 months with a mean of 13.7 races post-injury. Having raced pre-injury did not convert to an advantage to starting post-injury, but non-starters, pre-injury tended to take longer to return to racing. In horses starting pre- and post-injury, 66% improved or maintained their race class level after surgery, whereas 64.2% decreased their race earnings postinjury; 85% of the fractures received internal fixation, of which 70% were complete fractures; 87% of horses with incomplete-nondisplaced fractures treated conservatively raced post-injury. The percentage of horses starting in a race post-injury for incomplete nondisplaced, complete nondisplaced, and complete displaced fractures treated with internal fixation were 74%, 58%, and 50%, respectively.Colts (72%) raced post-injury more frequently than fillies (53%) and it was suggested that this may represent a truer probability of starting in a race post-injury: 52% of horses with articular fragments within the condylar fracture were able to race post-injury.

Horses were more likely to start if radiographs at 2-4 months revealed no evidence of the fracture except the presence of lag screws. Based on this series of studies, the majority of horses with proper treatment were able to return to racing regardless of the fracture characteristic. Prognosis appeared to be affected by the severity of the injury to the joint, the presence of articular comminution, and the quality of surgical repair. There were 14/16 horses (87%) treated without surgery that raced after a lay-up period.

This study was particularly interesting in that 58% of complete nondisplaced fractures and 60% of horses with complete displaced fractures were able to race post-surgery.

The authors concluded that the similar number of horses racing in these two groups may indicate that a fracture being

Colon JL, Bramlage LR, Hance SR, Embertson RM. Qualitative and quantative documentation of the racing performance of 461 Thoroughbred racehorses after arthroscopic removal of dorsoproximal first phalanx osteochondral fractures (1986-1995).

Equine Vet J 2000; 32:475-481.

Dabareiner RM, Watkins JP, Carter GK, et al. Osteitis of the axial border of the proximal sesamoid bones in horses: eight case (1993-1999). J Am Vet Med Assoc 2001; 219: 82-86.

Dabareiner RM, White NA, Sullins KE. Metacarpophalangeal joint synovial pad fibrotic proliferation in 63 horses. Vet Surg 1996; 25: 199-206.

Dalin G, Sandgren B, Carlsten J. Plantar osteochondral fragments in the metatarsophalangeal joints in Standardbred trotters; result of osteochondrosis or trauma? Equine Vet J 1993; 16 (Suppl):

62-65.

complete is more of a factor in prognosis than the nondisplacement. if care is taken to reduce and fix the fracture accurately.

References Barclay VP. Foerner JJ. Phillips TN. Lameness attributable to osteochondral fragmentation of the plantar aspect of the proximal phalanx in horses: 19 cases (1981-1985). J Am Vet MedAssoc 1987: 191: 855-857.

BassageLH. Richardson DW. Longitudinal fractures of the condyles of the third metacarpal and metatarsal bones in racehorses: 224 cases(1986-1995).J Am VetMed Assoc 1998: 212: 1757-1764., Birkeland R. Chip of the Acta first phalanx in the metatarso-,. phalangeal jointfractures of the horse.

Radiol (Suppl) 1972; 29: ; 73-77. r Boure L. Marcoux M. Laverty S. Lepage OM. Use of electrocautery r.

probes in arthroscopic removal of apical sesamoid fracture fragments 226-232. in 18 Standardbred horses. Vet Surg 1999; 28:, Bramlage LR. Osteochondrosis -related bone cysts. Proc MEP 1993; 39: 83-85.

CarlstenJ. Sandgren B. Dalin G. Development of osteochondrosis in the tarsocrural joint and osteochondral fragments in the fetlock joints of Standard bred Trotters. 1. A radiological survey. Equine VetJ Supp11993; 16: 42-47.

Elce y, Richardson DW. Arthroscopic removal of dorsoproximal chip fractures of the proximal phalanx in standing horses. Vet Surg 2002; 31: 195-200.

Foerner JJ. Osteochondral fragments of the palmar and plantar aspects of the fetlock joint. Proceedings of the 33rd Annual Meeting of the American Association of Equine Practitioners, 1987: 739-744.

Fortier LA, Foerner JJ, Nixon AJ. Arthroscopic removal of axial osteochondral fragments of the plantar/palmar proximal aspect of the proximal phalanx in horses: 119 cases(1988-1992). J Am Vet MedAssoc 1995; 206: 71-74.

Groendahl AM. The incidence of bony fragments in osteochondrosis of the metacarpo- and metatarsophalangeal joints of Standard bred Trotters. A radiographic study. J Equine Vet Sci 1992; 12: 81-85.

Haynes PF. Diseases of the metacarpophalangeal joint. Vet Clin North Am (Large Anim Pract) 1980; 2: 37-49.

Hogan PM, McIlwraith CW, Honnas CM, Watkins JP,Bramlage LR. Surgical treatment of subchondral cystic lesions of the third metacarpal bone: results in 15 horses (1986-1994). Equine VetJ 1997; 29: 477-482.

Hornof WH, O'Brien TR, Poole RR. Osteochondritis dissecans of the distal metacarpus in the adult racing Thoroughbred horse. Vet Radio11981; 22: 98-106.Jaffe HL, Lichtenstein 1, Sutro CS.Pigmented villonodular synovitis, bursitis, and tenosynovitis. Arch Patho11941: 31: 731-765.

Kannegieter NJ. Chronic proliferative synovitis of the equine metacarpophalangeal joint. Vet Rec 1990; 127: 8-10.

Kawcak CE, McIlwraith CWo Proximodorsal first phalanx osteochondral chip fragmentation in 336 horses. Equine Vet J 1994; 26: 392-396.

Kawcak CE, McIlwraith CW, Norrdin RW, Park RD, Steyn PS. Clinical effects of exercise on subchondral bone of carpal and metacarpophalangeal joints in horses. Am J Vet Res 2000; 61:

1252-1258.

LoSasso MB, Honnas CM. Chronic proliferated synovitis in a horse.

Equine Pract 1994; 16: 29-32.

McIlwraith CWoSubchondral cystic lesions (osteochondrosis) in the horse. Comp Cont Educ Pract Vet 1982; 4: 2828-291S. McIlwraith CWoExperience in diagnostic and surgical arthroscoppy in the horse. Equine Vet J 1984; 16: 11-19.

McIlwraith CWoDiagnostic and surgical arthroscopy in the horse, 2nd edn. Philadelphia: Lea & Febiger; 1990a.

McIlwraith CWo Subchondral cystic lesions in the horse -the indications, methods, and results of surgery. Equine Vet Educ 1990b: 2: 75-80.

McIlwraith CW Osteochondritisdissecansof the metacarpophalangeal and metatarsophalangeal (fetlock) joints. Proceedings 39th AAEP Convention, 1993: 63-67.

McIlwraith CWo Arthroscopic surgery for osteochondral chip fragments and other lesions not requiring internal fixation in the

carpal and fetlock joints of the equine athlete: What have we learned in 20 years? Clin Tech Equine Pract 2002; 1: 200-210.

Mcllwraith CWoVorheesM. Management of osteochondritis dissecans of the dorsal aspect of the distal metacarpus and metatarsus.

Proceedings 35th AAEP Annual Convention 1990; 547-550.

Meagher DM. Joint sugery in the horse: the selection of surgical cases and consideration of the alternatives. Proceedings of the 20th Annual Meeting of the American Association of Equine Practitioners. 1974.

Misheff MM. Stover SM. A comparison of two techniques for arthrocentesis of the equine metacarpophalangeal joint. Equine VetJ 1991; 23: 273-276.

Murphy DJ. Nixon AJ. Arthroscopic laser extirpation of metacarpophalangeal synovial pad proliferation in 11 horses. Equine Vet J 2001; 33: 296~301.

Nickels FK. Grant BD. Lincoln SD. Villonodular synovitis of the equine metacarpophalangeal joint. J Am Vet Med Assoc 1976;

168:1043-1046.

Nixon AJ. Osteochondrosis and osteochondritis dissecans of the equine fetlock. Compend Cont Educ Pract Vet 1990; 12:

1463-1475.

Nixon AJ. Pool RR. Histologic appearance of axial osteochondral fragments from the proximoplantar/proximopalmar aspect of the proximal phalanx in horses. J Am Vet Med Assoc 1995; 207: 1076-1080.

Palmer SE. Radiography of the abaxial surface of the proximal sesamoid bones of the horse. J Am Vet Med Assoc 1982; 181:

264-266 Pettersson H. Ryden G. Avulsion fractures of the caudoproximal extremity of the first phalanx. Equine Vet 1982; 14: 333-335.

Raker CWoOrthopedic surgery: errors in surgical evaluation and management. Proceedings of the 19th Annual Meeting of the American Association of Equine Practitioners. 1973.

Raker CW: Calcification of the equine metacarpophalangeal joint following removal of chip fractures. Arch Am Coli Vet Surg 1985; 4: 66-68.

Richardson DW. Arthroscopically assisted repair of articular fractures. Cl~nTech Equine Pract 2002; 1: 211-217.

Sandgren B. Dalin G. Carlsten J. Osteochondrosis in the tarsocrural joint and osteochondral fragments in the fetlock joints in

Standardbred Trotters. 1. Epidemiology. Equine Vet J Suppl199 3; 16: 31-37.

Simon O. Laverty S. Boure L. Marcoux M, Scoke M. Arthroscopic excision of osteochondral fragments of the proximoplantar aspect of the proximal phalanx using electrocautery probes in 23 Standardbred horses. Vet Surg 2000: 29: 285.

Southwood 11. McIlwraith CWoArthroscopic removal of fracture fragments involving a portion of the base of the proximal sesamoid bone in horses: 26 cases (1984-1997). J Am Vet Med Assoc 2000; 217: 236-240.

Southwood 11. McIlwraith CW. Trotter GW et al. Arthroscopic removal of apical fractures of the proximal sesamoid bone in horses: 98 cases(1989-1999). Proc AAEP 2000; 46: 100-101.

Southwood 11. Trotter GW. McIlwraith CWoArthroscopic removal of abaxial fracture fragments of the proximal sesamoid bones in horses: 47 cases(1989-1997). J Am Vet Med Assoc 1998; 213:

1016-1021.

Steyn PF. Schmidt D, Watkins J et al. The sonographic diagnosis of chronic proliferative synovitis in the metacarpophalangeal joint of a horse. Vet Radio11989; 3: 125-138. van VeenendaalJC. Moffatt RE. Soft tissue massesin the fetlock joint of horses. Aust Vet J 1980; 56: 533-536.

White NA. Synovial pad proliferation in the metacarpophalangeal joint. In: White NA. Moore IN (eds). Current practice of equine surgery. Philadelphia: Lippincott; 1990: 550-558.

Whitton RC, Kannegieter J. Osteochondral fragmentation of the plantar/palmar aspect of the proximal phalanx in racing horses.

AustVetJ 1994; 71: 318-321.

Yovich JA. McIlwraith CWoArthroscopic surgery for osteochondral fractures of the proximal phalanx of the metacarpophalangeal and metatarsophalangeal (fetlock) joints in horses. J Am Vet Med Assoc 1986; 188: 273-279.

Yovich Jv; McIlwraith CW. Stashak TS. Osteochondritis dissecans of the sagittal ridge of the third metacarpal and metatarsal bones in horses.JAmVetMedAssoc 1985; 186: 1186-1191.

Zekas LJ,Bramlage LR. Embertson RM. et al. Results of treatment of 145 fractures of the third metacarpal/metatarsal condyles in 135 horses (1986-1994). Equine Vet J 1999; 31: 309-313.

.has become a most important technique diagnosis as well as for surgery in the femoropatellar femorotibial joints (Martin & McIlwraith 1985, .c 1984,Folandetal1992.Nickels&Sande , Moustafa et a11987, Lewis 1987, Walmsley 2002, al 2003). Diagnostic and surgical arthroscopy

trochlear ridge of the femur. At this location. the patella can be displaced further from the trochlear ridge. which allows the sleeveto slide proximally more easily.

When the sleeveis positioned to the hilt. the obturator is removed and is replaced with the arthroscope. The light cable and ingress fluid line are attached and the joint is distended.Figure 6.3 demonstratesthe position of the arthroscopic sheath at the completion of insertion and the diagrams in Figure 6.4 show the position of the arthroscope at the beginning of the diagnostic examination.

Normal of the arthroscope femoropatellar joint

into

If both legs are involved, each leg should remain

postoperativefemoralnerveparesisor quadriceps Alternatively,the legs may be elevatedand tied that tensionis not concentratedon the quadriceps The skin portal for the arthroscope is located between the middle and lateral patellar ligament, and halfway between the tibial crest and the distal aspect of the patella (Fig. 6.1).

This arthroscopic portal allows a complete diagnostic examination of the femoropatellar joint as well as fulfilling all needs for observation during surgical manipulations. An 8-mm stab incision is made through the skin, superficial fascia, and deep fascia into the femoropatellar fat pad (Fig. 6.1B).

The sleeve and conical obturator are manipulated through the stab incision in the skin and fascia and then angled 450 to the skin in a proximal direction (Fig. 6.2). The femoropatellar joint space is entered by gently manipulating the obturator and arthroscope sleeveunder the patella and over the femoral trocWea. This maneuver may be facilitated by elevation of the distal limb. If resistance is encountered, the sleeve and obturator are not forced but are directed more laterally to lie under the lateral part of the patella facet and over the lateral

arthroscopic

anatomy

The suprapatellar pouch is the first area of the joint visible when the arthroscopic sleeveis situated beneath the patella and rests in the intertrochlear groove (seeFig. 6.4). This area is large. but the synovial membrane lining the pouch can be visualized on all surfaces of the pouch. The proximal extent of the suprapatellar pouch may be poorly illuminated with low output light sources.

The articular surface of the patella and intertrochlear groove can be visualized by withdrawing the arthroscope from this position (Fig. 6.5). Specific examination of each area can be achieved by rotating the arthroscope. The suprapatellar pouch disappears from view as the arthroscope is withdrawn and eventually the tension of the patellar ligaments abruptly forces the arthroscope out from beneath the patella. At this stage. the distal apex of the patella is visualized resting in the intertrochlear groove (Fig. 6.6). A fringe of villous synovium usually overhangs the distal margin of the patella.

Longitudinal defects are often observed in the central part of the intertrochlear groove and apparently are normal. particularly in the more distal regions of the groove.

The medial trochlear ridge and the medial aspect of the distal patella can be visualized by rotating the arthroscope and directing the angled field of view toward the medial aspect of the joint (Fig. 6.7). Despite joint distention, thepatella and medial trochlear ridge remain in close appositionin this case, in contrast to the same area on the lateraltrochlear ridge. The medial trochlear ridge is then examined by moving the distal end of the arthroscope carefully along

the length of the ridge (the eyepiece of the arthroscope is moving proximally during this maneuver) (Figs 6.8 and 6.9).

This will visualize also the medial patellar fibrocartilage and conjoined medial patellar ligament. Advancing the arthroscope over the medial trochlear ridge and viewing caudally, one can view the synovial recessbeyond the medial trochlear ridge. In some cases,a fold of synovial membrane overlies the distal extremity of the medial trochlear ridge (Fig. 6.10B). If this fold is elevated,a communication into the medial femorotibial joint may be apparent: this communication can permit the passageof the arthroscope and visualization of the cranial aspect of the medial condyle.

The arthroscope is returned to the proximal aspect of the medial trocWear ridge and is rotated laterally and across the intertrochlear groove to the lateral trochlear ridge (Fig. 6.11).

With fluid distention, the patella is separated from the lateral trocWear ridge in this aspect of the joint. This separation facilitates examination of the proximal aspect of the lateral trochlear ridge as well as the undersurface of the patella, and also allows advancement of the arthroscope proximally into

The

Diagnostic arthroscopy clinical

of

conditions

primary indication for arthroscopy of the femoropatellar joint has been in cases of osteochondritis dissecans. Surgical intervention for this condition is discussed in a separatesection.

Arthroscopic surgery also has value in casesof distal patellar fragmentation and patellar fractures. Diagnostic arthroscopy of the femoropatellar joint is also performed incases of persistent femoropatellar effusion in which theradiograp changes are equivocal or absent. In some ofthese animals, articular cartilage lesions may be seen on the articular surface of the patella. Some appear to be cases of OCD but in others the changes are consistent with what isdescribed as chondromalacia in the human knee. Thepathogen and significance of such an entity in the horseis still uncertain. If such changes in the articular cartilage are visualized, the pathologic area is debrided (chondroplasty) and clinical improvement has occurred after such treatment in equine patients.

The use of the probe in evaluating all cartilage lesions. particularly those of osteochondritis dissecans. cannot beoveremp The portal for a probe can be made virtually anywhere in the femoropatellar joint as there are no adjacent tendon sheaths and bursae. The usual locations for instrument portals when operating on lesions atvarious positions within the femoropatellar joint arepresented subsequently. These portals are also sites forprobe entry. Surgeons can ascertain optimal sites for probe penetration by inserting an l8-gauge 1.S-inch needleinto the joint to determine if the site and angle are satisfactory.

the suprapatellar pouch without risk of damage to the articular surfaces (as mentioned previously, this is the reason why moving the arthroscope sleeve laterally facilitates initial entry of the arthroscope into the joint). The synovial membrane in the lateral aspect of the joint adjacent to the area of articulation of the lateral trochlear ridge and distal patella is smooth and non-villous (seeFig. 6.11), but if becomesquite villous distal to this point. The entire length of the lateral trochlear ridge is then explored by moving the distal end of

the arthroscope distad and advancing the arthroscope further into the joint as necessary (Figs 6.12 and 6.13). This maneuver involves moving the eyepiece of the arthroscope mediad and proximad. The synovial membrane is villous adjacent to the distal one-half of the lateral trochlear ridge (Fig 6.12B) and fluid distention is often critical to allow a clear view of this area. The trochlear ridge is examined until the synovial reflection of the distal extremity is encountered (seeFig. 6.13). In the event of the view being obscured by hypertrophied synovial villi, viewing of a specific area of the trochlear ridges can be improved with gradual flexion. As the arthroscope is moved axially from the lateral trochlear ridge.

the distal aspect of the intertrochlear groove can be examined. Irregular cartilagenous protuberances and creases are commonly seenand are considered normal (Fig. 6.14).

Insertion of the arthroscope cranial pouch of the medial femorotibial joint

into the

horse is positioned in dorsal recumbency with the leg in flexion (approximately 900 at hock and stifle). The leg is surgically prepared and draped. Three approaches have been used for diagnostic arthroscopy of the medial femorotibialjoint: cranial (Moustafa et al198 7), lateral (Lewis 1987), and craniolateral (Nickels & Sande 1982). All approaches provide an effective examination of the cranial part of the medial femorotibial joint. The authors use the first two approaches. and they are described. The cranial approach allows more consistent examination of the intercondylar (cruciate) area.

On the other hand. the lateral approach leaves a clear area cranially for instrument placement when operating on medial condylar lesions.

Cranial approach.

The medial femorotibial joint may be distended with sterile fluid through an 18-gauge needle

Diagnostic Arthroscopy of the Femorotibial joints

Femoropatellar and Femorotibial joints

Fig. 6.5 Patella (P) and trochlear groove (T), with arthroscope under the patella, at the level of the proximal trochlear groove. (A) Diagram of visual field (circle). (B) Arthroscopic view.

.,

Femoropatellar andFemorotibial Joints

inserted cranially, but the first author (C.W.M.) generally finds this unnecessary. For the cranial approach, a skin incision is made and continued through the fascia between the middle and medial patellar ligament about 2 cm proximal to the tibial crest. The arthroscopic sleevecontaining the conical obturator is then inserted through the fat pad in a slightly proximad, caudad, and axial direction until it penetrates the medial femorotibial joint capsule (Fig. 6.15). Entry into the joint is confirmed by observation of the joint features or egressof fluid on removal of the conical obturator (if joint is predistended).

The arthroscope is then inserted and the examination can begin (Fig. 6.16).

Lateral approach.

The site of the arthroscopic portal is caudal to the lateral patellar ligament, cranial to the long digital extensor tendon, and 2 cm proximal to the tibial spine (Lewis 1987) (Fig. 6.17). The arthroscopic cannula with conical obturator in place is then directed medially and slightly caudad to penetrate the synovial membrane in the lateral aspect of the medial femorotibial joint (Fig. 6.18A).

The obturator is removed and the arthroscope is inserted.

After checking that the arthroscope is in the cranial compartment (Fig. 6.18B), the joint is distended, and the examination begins (Fig. 6.19).

Approach to the cranial pouch the medial femorotibial Joint from femoropatellar joint

of

This technique was originally describedby Boening (1995) and subsequentlyreported in the United Statesby Peroni& Stick (2002). A longer arthroscope is preferred for this technique.The femoropatellarjoint is entered through the normally describedportal betweenthe lateral and middle patellar ligaments. mid-way betweenthe patellar and tibial crests.The slit-likeopeningscommunicatingwith the medial

of the axial aspectof the femorotibial joints. but examination further laterally and medially is limited.

Normal arthroscopic anatomy of the cranial compartment of the medial femorotibial joint

.in some casesthe lateral femorotibial joints

a window betweenthe respectivefemorotibialjoint

The medial intercondylar eminence of the tibia and axial side of the medial condyle of the femur can be easily located in the distal medial aspect of the joint and used as a reference point (Fig. 6.20). The cranial ligament of the medial meniscus and cranial cruciate ligament are also observed. The cranial ligament of the medial meniscus and the cranial portion of the medial meniscus are visible by moving the arthroscope medially along the distal aspect of the medial condyle of the femur (Fig. 6.21).

Medial

and Femorotibial joints

The tip of the arthroscope is retracted to the center of the joint and the arthroscope is rotated upward to visualize the central weightbearing area of the medial condyle of the femur (Fig. 6.22). Visualization of the medial and cranial aspects of the medial condyle of the femur may be facilitated by some extension of the joint (Fig. 6.23). Visualization of the medial collateral ligament. however. requires a more medial arthroscopic approach. Further retraction of the arthroscope reveals the proximal axial portion of the medial condyle and the caudal cruciate ligament running proximodistal beneath the synovial membrane (Fig. 6.24). A better view of the cruciate ligaments can be obtained with the cranial approach. but a complete examination can be done with either approach.

Insertion of the arthroscope intothe cranial compartment of the lateral femorotibial joint approaches to this joint have been described by bothNickels & Sande (1982) and Moustafa et al (1987), and arefavored over a cranial or a lateral approach. Attempts to createa direct lateral portal are inhibited by the lateral collateral ligament and the lateral patellar ligament. and by the tendon of origin of the long digital extensor. A portal between themiddle and lateral patellar ligaments can be used, butarthroscopic manipulation is limited.

For the medial approach to the lateral femorotibial joint as originally described by Moustafa et al (1987), the arthroscope (after approaching the medial femorotibial joint using the cranial approach) is returned to the intercondylar reference point in the medial femorotibial joint. The lateral femorotibial joint may be pre-distended with fluid through an 18-gauge

and Femorotibial joints

needle inserted between the lateral patellar ligament and the lateral collateral ligament, but this is not necessary. The arthroscope then views the synovial septumcranial to the intercondylar eminence of the tibia. In this position, the arthroscope is replaced with the conical obturator, and the sleeve is inserted caudolaterally behind the long digital extensor tendon, to the far side of the joint. The arthroscope is then placed in the sleeveand the arthroscopic examination commences.

Alternatively, the lateral femorotibial joint may be approached directly without prior arthroscopic examination of the medial femorotibial joint. The lateral femorotibial joint is distended as described previously, and an 8-10-mm skin incision is made medial to the middle patellar ligament. The arthroscopic sheath and trocar is then advanced caudolaterally to penetrate the joint capsule on the cranial side and advanced to the lateral side of the joint.

A

Normal arthroscopic anatomy of the cranial compartment of the lateral femorotibial joint After entry,the initial view should includethe lateral aspect of the lateral femoral condyle,as well asthe poplitealtendon within its synovial diverticulum (Fig. 6.25). Withdrawal of the arthroscoperevealsthe lateral femoralcondyleand the lateral meniscus (Fig. 6.26). Further medial, the cranial ligamentof the lateral meniscusand the lateral tibial condyle maybe visualized,as well asthe long digital extensortendon under the synovial membrane and within the sulcus muscularisof the tibia (Fig.6.27). With further withdrawal and rotation of the arthroscope,the lateral aspectof the

cranial cruciate ligament can be seen axially under median septum (Fig. 6.28). A small area of 1-, visible axial to these structures.

Insertion of the arthroscoJ?e caudal pouch of the medial femorotibial joint

into the

joints are small. The stifle is positioned in 90-1200 of flexion.

The joint is distended with a spinal needle placed

i !

IW;;, 2002).

~

.,, \ ~\~.\ I

,

\ \\

\\

Lateral condyle

.: ~, "'/

Medial

condyle

;z:: Lateral Medial

I

approach

Popliteal tendon

if/!

P i

!i

I

The arthroscopic portal can be made in the i plane as the needle.but 3 cm caudally;In consideration described the level of the portal as 2.5 cm proximal to .. distal level of the medial meniscus and 3 cm caudal the medial collateral ligament. This approach provides adequate view of the axial aspect of the joint (Fig. r Making the portal 3 cm more proximad to allow for a

instrument portal has been described by other (Hance et al ~ prior use of the spinal needle. More caudal entry of arthroscope, 6 cm caudal to the medial collateral ]

better examination of the caudal horn of the Additionally,it leavesmore room for instrumententry.

Normal arthroscopic anatomy caudal pouch of the medial femorotibial joint are initially visualized (Fig. 6.30).' medial meniscus may be ';". .

of the

of the pouch and the outline of the caudal cruciate ligament may sometimes (rarely) be noted axially beneath the joint capsule. coursing in a proximodistal direction.

Insertion of the arthroscope into the caudal compartment of the lateral femorotibial joint Theseapproachesare basedon the descriptionsof Trumble et al (1994), Hance et al (1993), and Stick et al (1992). It is important to be aware that the peroneal nerve lies 7 cm caudal to the lateral collateral ligament and so no portal should be made this far caudally. The popliteal tendon divides the caudal lateral femorotibial joint. Distention is performed with a spinal needle placed caudal to the collateral ligament. For examination proximal to the popliteal tendon, the portal is placed 2.5 cm proximal to the tibial plateau and 3 cm caudal to the collateral ligament (Fig. 6.29) (Walmsley 2001).

Structures seen through this portal are limited to the lateral

femoral condyle and the proximal border of the popliteal tendon. To view the pouch distal to the popliteal tendon. the portal is located at the level of the tibial plateau. 1.5 cm caudal to the lateral collateral ligament. and the arthroscope is placed through the popliteal tendon to allow examination of the more caudal articulation of the joint. It was noted by Trumble et al (1994) that the tendon of the popliteal tendon being contiguous with the joint capsule of the caudal pouch of the lateral femorotibial joint makes arthroscopic exploration of this pouch particularly dillicult.

Normal arthroscopic caudal compartment femorotibial joint

anatomy of the of the lateral

With the proximal arthroscopic portal. it is possible to view the proximal border of the popliteal tendon and the lateral femoral condyle (Fig. 6.31). Using the distal portal through the popliteal tendon it is possible to examine the caudal

included

meniscus, part of the caudal aspect of the lateral , the intra-articular portion of the popliteal but this examination is

arthroscopy of clinical in the femorotibial

cases of cystic lesions of the medial condyle of the .1987). Surgical intervention for this condition

1987; Turner et a11988. McIlwraith 1995 1995. 2002). Lewis described the arthroscopic in 20 cases of unilateral lameness. with a positive the medial femorobut without major radiographic abnormalities. A .was abnormality of the articular surface of distal weightbearing portion of the medial femoral abnormalities included fibrillation of the articular partial- to full-thickness erosion, sometimes and, in some cases, cartilage flaps. Abnormalities of the medial were evident in 9 cases,including mild to marked and degeneration of the proximal surface. A 3 casesand a partial avulsion/ of the cranial ligament of the medial meniscus was 1 case. Examination of the menisci was difficult in all and Lewis (1987) noted a lack of ability to adequately the caudal segments of the meniscus. Lewis also the use of surgical arthroscopy in 2 cases of tibial fractures. One of the 2 horses was completely sound could resume full function; the other was periodically mild degree when heavily used. Of the 20 casesin revealed articular cartilage

nonsteroidalanti-inflammatory agent therapy, Turner et al (1988) reported the confirmation of cranial , .injury in 5 cases by the use of femorotibial A cranial approach with the arthroscope used. Arthroscopic examination revealed the following disruption of the septum surrounding the ligaments and separating the medial and lateral joint compartments; increase in the joint space with ligamentous laxity; synovitis; and areas of a partial longitudinal tear of the cranial ligament in 1 case (the horse also had a cranial ligament at its insertion adjacent to the tibial tearing of the cranial attachment of the lateral

the

medial femoral condyle, and a complete tear of the cranial cruciate ligament in 1 case.

More recently, the use of arthroscopy to both diagnose and treat vertical tears of the cranial horn of the meniscus and the cranial ligament of the meniscus has been described (Walmsley 1995). The most recent use of arthroscopic surgery in 80 casesof meniscal tears in the horse has been described

by Walmsley et al (2 003). Schneideret al (199 7) also described the use of medial femorotibial arthroscopy to evaluatecartilage lesions on the medial femoral condyle as a cause of equine lameness in 11 cases.These conditions will be discussed in more detail separately.

As noted previously, the septum separating the lateral and medial femorotibial joint compartments is commonly disrupted in association with cruciate ligament injury; a cranial approach to the medial femorotibial joint will also allow examination of the lateral femorotibial joint in these cases. If both cranial and cruciate (and medial collateral) ligaments are disrupted, the resulting laxity will allow greater visualization of the femorotibial articulations and menisci.

Osteochondritis

dissecans

Arthroscopic surgery has emerged as the only surgical technique to treat osteochondritis dissecans (OCD)in the femoropatellar joint. It has replaced arthrotomy eliminating local problems with wound healing and reducing the need for rigid postoperative management. The techniques presented subsequently are based on the experience of the authors with clinical cases of OCD in the femoropatellar joint and the follow-up data that have been generated from these cases (Mcllwraith 1984, Mcllwraith & Martin 1984,1985; Martin & Mcllwraith 1985. Foland et al1992). Although successful results can be obtained by using arthrotomy, potential complications include seroma formation. local cellulitis and fasciitis, and wound dehiscence (Pascoe et al 1980, 1984; Trotter et aI1983).

Preoperativeconsiderations Preoperative diagnosis of OCD is based on clinical and radiographic signs. The clinical signs that initially prompt the attention of owners are lameness and/or synovial effusion of the femoropatellar joint. The diseaseis not breed-specific,but it is a diseaseof young horses. In some instances. however. no clinical problems are apparent until the horse is in training or has raced (Mcllwraith & Martin 1985). Lesions that manifest at this stage are generally less severe. Clinical examination generally reveals some degree of synovial effusion as a consistent finding. Lameness ranges from nondiscernible through subtle gait changes (shortened anterior phase of stride, low arc of flight. and unusual flight path with the stifle

rotated outward and the hock inward) to obvious lameness with a stiff gait and difficulty in getting up. Animals may have difficulty in trotting with a preference to canter or "bunnyhop" is common.

The radiographic manifestations of the disease vary.

Lesions most commonly occur on the lateral trochlear ridge but are also seen on the medial trochlear ridge of the femur and/or on the patella (Table 6.1). The lesions in turn may be localized to a small area or be distributed along the entire length of the trochlear ridge. The most common radiographic manifestation of OCDis a defect (with or without discernible fragments) on the lateral trochlear ridge of the femur (Fig.6.32). Defectscan be describedas concave (seeFig. 6.32), flattened (Fig. 6.33), cystic, or undetermined. Lesions on the medial trochlear ridge usually manifest as a concave defect (when evident radiographically), but often are not visible on radiographs (due to a normal subchondral bone contour) (Fig. 6.34). Lesions can also be observed (less frequently) in various parts of the patella and manifest as some form of subchondral defect (Fig. 6.35).

For many years the authors recommended arthroscopic surgery for all casesof osteochondritis dissecans,particularly if an athletic career is planned. However, the study by McIntosh & Mcllwraith (1993) shows that, with conservative

management (stall or pen confinement for 60 days). then a number of femoropatellar OCDcases can heal. Based on this study. if defects are less than 2 cm long and less than 5 mm deepand there is no obvious mineralization or fragmentation of the flap on radiographs. conservative therapy is a viable option. It has also been pointed out by Dik et al (1999) that up to age 8 months it is possible for radiographic lesions on the femoral trochlear ridges to resolve. In a longitudinal study of Dutch Warmblood foals, radiographed at 1 month old and subsequently at 4-week intervals, the mid-region of the lateral femoral trocWear ridge becameradiographically abnormal from 3 to 4 months old. Subsequent progression of radiographic abnormalities was usually followed by regression and resolution. with the appearance returning to normal at 8 months old in most cases. At 5 months old. 20% of the stifles were abnormal radiographically, but at 11 months old this percentage had decreasedto 3%. Normal and abnormal appearances were permanent from 8 months old (Dik 1999).

The authors currently recommend that all lesions greater than 2 cm in length or 5 mm in depth. or any lesion that contains osseous densities in the presence of synovial effusion. be treated with arthroscopic surgery. In some of the cases that can potentially heal conservatively. owner or

trainer request for the problem to be assured of correction also leads to early surgical treatment. Persistence of synovial effusion is always an indication for surgery. When the severity of the changes is too severe, surgery is not recommended. A direct comparative study was done comparing radiographic and arthroscopic findings in the femoropatellar joint (Steinheimer et al 1995). It is rare to find an arthroscopic lesion less severe than the radiographic insinuation.

On the other hand, it is common to find more pathologic change at arthroscopic surgery than predicted by radiographs.

Technique A number surgery

of different at various

instrument locations

Previously,

six different

to operate

on the various

in the femoropatellar edition

of this text. spinal

the ideal location

the

triangulation lesions

joint

needle

are used to perform femoropatellar

approaches

of osteochondritis

and were discussed

However,

do not need to be rigidly disposable

portals in

fixed.

joint. were

in the second

exact sites for instrument Rather,

is now

for an instrument

used

dissecans entry

the use of an I8-gauge

recommended portal

to ascertain

(Fig. 6.36).

In all

cases,a l-cm incision is made through the skin and superficial and deep fascia, and using a stab incision with a No. 11 blade completes entry into the joint. The various instruments are then inserted through the portal as required (Fig. 6.37).

The various surgical approaches are illustrated in Figures 6.38-6.43. In all instances, we are using the same arthroscopicportal between the lateral and middle patellar ligament although it is noted that an arthroscopic portal between the middle and medial patellar ligaments has also been used for operations involving lateral trochlear ridge lesions (Bramlage perscomm 1987).

Lesions on the proximal one-half of the lateral trochlear ridge are reached through a portal proximolateral to the arthroscopic portal (seeFig. 6.38). The instrument may pass either lateral to or (usually) through the lateral patellar ligament when using this portal. If the entry is too far lateral, the instrument cannot be manipulated up and over the lateral trochlear ridge. Passing the instrument through the lateral patellar ligament does not seem to be of any consequence. Lesions of the proximal portion of the medial trochlear ridge are reached by using a portal between the medial and middle patellar ligaments. entering the skin distal to the lesion (Fig. 6.39).

To effectively operate the underside of the patella. an instrument portal must be level with or distal to the arthroscopic portal and usually 2 cm lateral to the arthroscopic portal (seeFig. 6.40). If this portal is more proximal than the arthroscopic portal. the end of the instrument cannot make contact with the undersurface of the patella. The portal is made lateral to the middle patellar ligament. depending on the position of the lesion on the patella. To operate on lesions on the distal aspect of the lateral trochlear ridge. the same arthroscopic portal is used as that chosen for the proximal trochlear ridge. although the arthroscope is directed distad.

The instrument portal is made low over the distended femoropatellar joint through or immediately adjacent to the lateral patellar ligament (Fig. 6.41). For lesions on the distal aspect of the medial trochlear ridge. a distal portal is usually made between the middle and medial patellar ligaments (Fig. 6.42). If the lesion on the medial trochlear ridge is located on the trocWear groove (axial) side of the distal medial trochlear ridge. however. a medial portal does not always allow the instrument to reach this location. In this instance. a lateral instrument portal. allowing the instrument to pass under the middle patellar ligament. is necessary (Fig. 6.43).

fragmentation

within

chondral

bone

common on

when

preoperative

chondral

found.

Gross

or

when In

Fig

tissue

6.45).

are

flaps disk

and

successive proximal

edge.

slipping body.

In

joints

contain

a

dimple within

a

within

in

an

openly

matrix

of

the

undermined is

forceps

(see

by

Figs

of Hand

burr

can

be

subchondral loss

At

effective

tissue.

A

6.45-Fig. normal

the

completion

the

the

flap

a

loose

does

not

varies

from

of

cartilage

may flap

be

or

unattached

is

to

a

noted

a

fragments, subchondral

rongeurs

subchondral used

in

debriding

6.50)

hand 6.47). and

tissue

of

remaining

in (Fig

of

becoming

its

or

basket

6.47).

curettage

bone

of

the

at

chance

Fragments

fibrous

in

attached

lesion

Ferris-Smith

and

(see

removed

defect the

lesion.

using

6.46

Debridement performed.

subchondral

c?ftilage

removed

is it

the

removal

(see

instrument

the

of

elevated,

Ferris-Smith

flap

and

or

After

using

leaving

nature

flaps,

rongeurs

equivalent

forceps

granulation

articular

bone

an

by

reduces

eroded

defect.

and

the

the

and

or

The

of

flap,

frequently

manipulated

rongeurs.

which

distinct

to

or

grasp

commonly

radiographs.

removed

technique

the

trochlear

also

elevator

then

the

This

from

are

6.44-6.48).

with

manifest

the

fragments on

flaps

rongeurs

Figs

bites

cartilage

periosteal are

lesions

are

is

observed

examinations the

the

been

in

flaps

discernible

a

The

6.37

Figs between

not

using

intervertebral Fig

in

situation, by

the defects

sub-

situation

have

When

osteochondral

and

This

fragments

histopathologic

they

either

6.45).

subchondral

and

osseous

usually

or

radiographs.

ridge.

cartilage

and

flaps

as

confirm

articular

6.44

ossified

radiographically

even

the

(Figs

but

curette pathologic Curettage

of

subchondral

can is

defect

most

cases.

the

defects

easily

result

used

in

bone. allows

A

is

then

motorized to

in

most

healthy excessive

cases

(see

better

debridement,

tags

---

mined,unattachedarticular cartilageremains.

Manipulations of the surgical instruments vary, but a sequential protocol is generally followed. A number of cases are used to demonstrate the manipulations (Figs 6.44-6.48).

In all cases,the lesions are initially evaluated with a probe.

The probe is useful in defining the limits of an osteochondral or chondral flap as well as for assessingits mobility. The probe is also used to evaluate any cracking, wrinkling, or fibrillation in the articular cartilage. If the cartilage is cracked but firmly attached to subchondral bone, it is not removed. Normalappearing articular cartilage is also probed, particularly if radiographs have revealed lesions in the subchondral bone in that area. If intact cartilage overlies a subchondral defect,the probe breaking through the articular cartilage into the defect locates the lesions and the undermined articular cartilage is then removed.

The most common form of pathologic change encountered on arthroscopic examination of osteochondritis dissecans of the lateral trochlear ridge of the femur is flap formation or

commonly occur as raised areas of articular

trochlear ridge lesions,with the use of portal (Figs6.39, 6.42, 6.45, and 6.47). and on the axial sides of the trochlear ridges. It is common to see OCD lesions on the ~ ~c ,-- ~

is gaugedby inserting a spinalneedle.but generally ridge will not allow accessto the lesion. arthroscopeand instrument is depictedin Figure graphs indicate severe intraarticular disease and surgery contraindicated (Fig. 6.49) Primary OCD lesions of the patella are uncommon, "-they do occur (Fig. 6.51).-

",' Femoropatellar and Femorotibial joints ,~

.,

Wi

for lesions on the trochlear ridges, with removal of .In addition to primary osteochondritis of the patella. degenerative erosive lesions that

of cartilage (with bone sometimes) are seen on the in association with lateral trochlear ridge OCD 6.51B). The usual site for these patellar lesions is the -it articulates the area of osteochondritis dissecans on the lateral ridge. Histological examination of these buds of in one of the author's (A.J.N.) laboratory suggest

Lack of correlation between radiographic lesions and pathologic changes found intraoperatively are a

feature of osteochondritis dissecans of the femoropatellar joint. This lack of correlation takes a number of forms: (1) cartilaginous change more severe than expected. based on the subchondral lesions seen on the radiographs; (2) cartilaginous lesions on the trochlear ridge or patella where no subchondral bone changes were radiographically detectable; or (3) less severe cartilaginous change than expected (usually taking the form of intact articular cartilage over radiographically lucent subchondral change). The various radiographic defects observed manifest in a number of ways during arthroscopic examination. Usually some form of cartilaginous flap or islands of cartilage and a fibrous tissue stroma are present within a concave defect (seeFigs 6.44 and 6.45); other casesinvolve a dimple-type defect or an area of cartilage fibrillation or loss with or without undermined or detached articular cartilage. In some instances. intact cartilage is separated from the bone (seeFigs 6.45 and 6.47).

Osteochondral bodies that have detached from the primary trochlear ridge lesions can be a challenging surgical problem. They may be free within the joint or embedded within the synovial membrane and joint capsule. If these bodies are totally free within the joint. the surgeon must grasp the fragment carefully without pushing it away and causing it to float up into the suprapatellar pouch (Fig. 6.52).

Switching off the ingress fluids at this stage can decreasethe fluid flow and minimize movement of the loose body. Prior fixation of the loose body with a needle is also of help in this situation.

In instances of large fragments. the skin incision is enlargedto facilitate removal and occasionally the deepfascial incision is also enlarged.However.a proximal instrument portal abovethe patella into the suprapatellar pouch can be used to remove large fragments with satisfactory results. A spinal needleis used to confirm the correct position before incising a portal through the quadriceps muscle into the suprapatellar pouch. Large fragments are removed more easily through this portal because they do not have to come through the inelastic

deepfascia. as occurs with the conventional lateral or medial instrument portals. As in other joints, the skin alone is sutured and no healing problems have been observed.

It is difficult to make specific recommendations with regard to how to manage osteochondral massesembeddedin the synovial membrane or in the fibrous joint capsule. For cases in which the loose body is attached to synovial membrane but is clearly visible within the joint, removal is indicated and can be performed arthroscopically without problems. For a less-visibleor less-accessiblelesion, arthrotomy can be performed and the first author (C.W.M.) has used this technique in one instance of such a lesion (Mcllwraith & Martin 1985). It is questionable if removal of this mass was necessary and the authors favor leaving it alone when it is embedded within the joint capsule. Formation of osseous bodies in the soft tissue has occurred postoperatively, and similar lesions have been noted on radiographs obtained after arthrotomy (Pascoe et aI1984). Horses with these osseous masses can race, leading to the interpretation that these animals do not need surgery.

Contraindications for surgery include lateral luxation of the patella owing to excessive loss of the lateral trochlear ridge, and secondary remodeling changes of the patellar identified radiographically (seeFig. 6.49).

At the completion of the surgical procedures for osteochondritis dissecans, the joint is liberally lavaged and vacuumed to ensure removal of small debris released at the time of surgical debridement. A special, larger egresscannula has been developed for this purpose. It is 8 mm in diameter and is 20 cm in length. It is inserted until its tip lies within the suprapatellar pouch (Fig. 6.53A). The suction tubing can be applied directly to the end. A motorized fluid system is critical in flushing this joint. Use of this specialegresscannula at the end of the procedure is most appropriate, because the debris collects in the suprapatellar pouch and an instrument of large diameter is necessary to allow its removal. An alternative is to insert a large diameter cannula into the suprapatellar pouch through a portal proximal to the patella.

After completion of the procedure and suturing of the incisions, a sterile loban@ drape is placed over the surgery site in lieu of a bandage (Fig. 6.53B).

Pin fixation of large osteochondritis dissecans fragments has been described in man (GuhI1984). Note, however, that

such fragments have a rigid bony component, which is rarely present in the equine case. Recently, a technique for using PDSOrthosorb@pins has beendescribedby Nixon et al (2004) for fixing large OCD flaps (see Chapter 16). A very select group of OCD lesions are suitable for reattachment. The cartilage of the flap must be relatively smooth, not calcified, and have at least some residual attachment to the surrounding cartilage. The arthroscopic PDSpin kit can then be used to secure the flap in multiple locations. Reattachment, revitalization, and most, importantly, filling of the subchondral bone defect occurs within 8-12 weeks of :

the rapid return of , follow-up radiographs (Fig. 6.54). This compares with the trochlear ridge defect remaining after ment, particularly for the discerning buyer of yearlings. It should be stressed, however, that OCD flaps of the femoral trochlear ridges do not fit : guidelines established for reattachment and need to debrided.

I

some clot organization within the defect. After this time, it is theorised that exercise will facilitate modulation of the tissue within the defect toward some form of fibrocartilage. On the basis of follow-up results, the horse can return to light training 3 to 4 months postoperatively,depending of the age of the animal.

ResultsThe results of arthroscopic surgery performed in the first 40 cases of osteochondritis dissecans involving 24 horses were reported by McIlwraith & Martin (1985). More recently,we published the results of arthroscopic surgery for the treatment of OCD in 250 femoropatellar joints in 161 horses (Foland et al 1992). There were 82 Thoroughbreds, 39 Quarter Horses, 16 Arabians, Warmbloods, and 15 others of various breeds. There were 53 females and 108 males: 22 horses were less than 1 year old at the time of surgery, 68 were yearlings, 36 were 2 year olds, 21 were 3 year olds, and 14 were either 4 years old or older: 91 had bilateral involvement and 70 had unilateral disease.

Follow-up information was obtained on 134 horses, including 79 racehorses and 55 non-racehorses. Eighty-six (64%) of these 134 horses returned to their intended use, 9 (7%) were in training at the time of publication, 21 (16%) were unsuccessful, and 18 (13 %) were unsuccessful due to other defined reasons. Horses with Grade I lesions (less than 2 cm in length) had a significantly higher successrate (78%) than did horses with Grade II (2-4 cm) or Grade III (greater than 4 cm) lesions (63% and 54% successrates respectively).

A significantly higher successrate was also noted for horses operated on as 3 year olds compared with the remainder of the study population. A significantly lower successrate was noted for yearlings than for the remainder of the population.

There was no significant difference as related to gender involved, racehorse vs non-racehorse, lesion location, unilateral vs bilateral involvement, presenceor absenceof patellar or trochlear groove lesions, or presence or absence of loose bodies.

Although a permanent clinical cure would likely be anticipated with this surgery in most cases,the nature of healing within the defects is less certain. On the basis of long-term follow-up radiographs obtained in horses that are sound, it seemsirregular contours in the subchondral bone frequently persist. After debridement, defects presumably fill with fibrous tissue or fibrocartilage, but this supposition is based on minimal amounts of follow-up necropsy data (Pascoe et al 1984) or second-look arthroscopy (Fig. 6.55). Whatever the tissue that fills the defect, it seems to provide satisfactory stroma for articulation. No lateral trochlear ridge lesion is

Postoperativemanagement Horses generally receive procaine penicillin and gentamicin sulfate perioperatively and phenylbutazone before surgery and for 5 successive days. This regimen is a precaution against any development of interfacial swelling. Most cases are simple to manage. and the horse can be discharged soon after surgery. Hand walking commences after 1 week to allow

necessarilytoo big to negate surgery but more detailed follow-up evaluation of larger lesions in elite athletes would be appropriate. As mentioned previously, if lateral luxation of the patella is present, surgery is contradicted. Limitations for healing have been described in the medial condyle of the femur (Converyet al19 72), but our clinical data support some form of functional filling of these defects on the trochlear ridges.

The healing potential of horses that have undergone operations at 2-3 years of age may be less than that of younger aniJIlals. Fortunately. these older horses typically have smaller defects. complete resurfacing of which may not be as critical for athletic function. Our published data for 3 year olds supports this conclusion (Foland et alI992).

A common question from clients regarding surgery for OCD of the stifles is what is the likelihood of having more lesions develop or will the problem developin other joints? Of the 161 horses operated on for femoropatellar OCD.12 underwent concurrent surgery for other lesions as well as femoropatellar arthroscopy (Foland et aI1992). Five of these horses had OCDlesions in both metatarsophalangeal joints. 4 horses had OCD of the tarsocrural joint. 2 horses had subchondral cystic lesions of the medial femoral condyle. and 1 horse had OCDof a scapulohumeral joint. In other words. the likelihood of lesions developing elsewhere is low. Also. the more recent work by van Weeren & Barneveld (1999) shows that if a horse is operated on at 11 months of age or older. there is no likelihood of additional lesion development in the femoropatellar joint.

Fragmentation of the distal patella This condition was mentioned in the second edition of this textbook. It has now been further explained and reported in the literature (McIlwraith 1990) and its pathogenesis explained (Gibson & McIlwraith 1991).

The condition is characterized by osteochondral fragmentation of the distal aspectof the patella. In the initial report of 15 horses, the problem was unilateral in 6 horses and bilateral in 9 and occurred in 8 Quarter Horses, 3 Thoroughbreds, 2 American Saddlebreds, 1 American Paint and 1 Warmblood/Thoroughbred cross. A previous medial patellar desmotomy had been performed on 12 of the 15 horses.

The condition manifests as hind limb lameness and stiffness ranging from mild to severe. There is fibrous thickening in the stifle area in all cases associated with previous medial patellar desmotomy (the fibrosis is centered over the desmotomy site) and synovial effusion is normally present and recognizable if the fibrosis is not too extensive.

The radiographic changes include bony fragmentation, spurring (with or without an associated subchondral defect), subchondral roughening, and subchondral lysis of the distal aspect of the patella (Fig. 6.56).

The treatment is arthroscopic surgery. In the initial series the lesions at arthroscopy varied from flaking, fissuring, undermining, or fragmentation of the articular cartilage to fragmentation and/or lysis of the bone at the distal aspectof the patella (Fig. 6.57). The subchondral bone was involved in all cases that had a previous medial patellar desmotomy. Of the 12 horses that had a previous medial patellar desmotomy, 8 horses became sound for their intended use, 1 horse was sold in training without problems, 1 horse was in early training without problems at the time of publication, 1 horse never improved and 1 horse was in convalescence. Of the three cases that did not have a medial patellar desmotomy, 2 horses performed their intended use, but 1 horse was unsatisfactory. In these instances, there was no severe bone involvement. It is possible that such cases are equivalent to the chondromalacia syndrome described by Adams (1974).

Preoperativeconsiderations The

history

hind

limb

patellar for the other

and

addition

obvious

trot of the

bone

at

of the

radiographic

the

of

aspect clinical lesions

the

to

The

patella

improvement in

these

may

reveal

be present

at the either

of

the

patella

with

an

observable

(see Fig. as well cases,

6.56). as the

arthroscopic

by

gonitis

is typically

commonly

aspect

associated

indication

a

lameness

joint

of

medial

(performed

desmotomy,

is observable

of the

after

specific

effusion

fibrosis.

distal

development

usually

is unknown

femoropatellar

(usually

distal

of a lack

instances,

Femoropatellar

but

the

stifle,

Subsequent

persists.

fragmentation

involves

to the

desmotomy

to pericapsular at the

the

usually

In most

patellar

veterinarians).

Radiographs in

cases referable

desmotomy. medial

develops in

in these lameness

walk.

a defect or

bony defect)

On the

basis

presence

of

surgery

is

recommended.

Technique An arthroscopic examination of the femoropatellar joint is performed as previously described. The lesion is identified on the distal patella and any other changes in the joint are noted. A distal lateral arthroscopic portal is made to allow an

1988).

Cystic

well as damage elsewhere (seenoccasionally).The frag-ments During this period.Lewisdevelopedan arthroscopic are removedby using a medial or lateral portal asappropriate.

Instruments may include a banana blade, elevator, Ferris-Smith rongeurs, and motorized abrader. latter technique was then adoptedby the first author andrepo In occasional instances,a fracture of the medial patellarfibrocartilage in the secondedition of this text. without osseousinvolvement may be seen(Fig. 6..e0).

Preoperative considerationsThe A retrospectivestudy of five performancehorses withpatellar fracturestreatedwith arthroscopicremovalhas beenreported typical clinical sign is lamenessin one or both hind limbs (Marble & Sullins 2000). Four of five horseshadfractures at a trot. In some horses, lameness is subtle and is noticeable of the medial aspectof the patella and one horsehadonly during riding. Historically, some of these horses can bein a fracture of the lateral aspect. Arthroscopy wasperformed training for considerable periods of time, with clinical signsman in the femoropatellar joint using techniquesdescribed only after a certain amount of work has beendone previously.There were no complicationswith the Most horses swing the leg medially and the lamenessisacce joint or the arthroscopicportal incisions. Recoveryperiodsranged when trotting in a circle with the affected leginsid from 3 to 5 months. All horsesrecoveredcompletely Medial femorotibial analgesia localizes the lesion but aresp from surgeryand performedat the sameor a higher levelof can also be obtained with femoropatellar blockade. competitionasbeforearthroscopy.

Any change in the external appearance of the stifle isminim for

which

follow-up

use

in

data

these

are

cases

available

and

reported

in

67

77

(Lewis

1987).

cases.

of

Itechn

This

Mild distention of the femorotibial joint may be seenin more chronic cases.It is more common to seefemoro-pate effusion (Howard et al1995).

The lesion is apparent radiographically. Both flexed lateraland caudocranial views (Figs 6.61 and 6.62) are useful to ascertain the location and sizeof the lesion. The typical lesionis round or oval with a defect at the articular surface ofvary size (seeFig 6.61). Such lesions may be bilateral. In lesions of the medialcondyle other cases,a small flattened or concave defect (seeFig 6.62) of the femur may be present. Most commonly, the latter lesion is seen inthe stifle opposite to one manifesting lameness and exhibitinga For 8 years,the first author (C.W.M.)treated subchondralcystic large cystic lesion or as an incidental finding on pre-purchaseradio lesions of the femorotibialjoint using a femorotibial of yearlings. Although surgical debridement ofcysti arthrotomy with goodresults (Mcilwraith 1983. White et al lesions is being described here, there are a number of

evaluation period showed that healing was similar in grafted and ungrafted defectsin the equine medial femoral condyle at 6 months Uackson et al 2000). This suggested that surgical debridement alone rather than adjunctive bone grafting of cystic lesions is the treatment of choice.

The development of subchondral cystic lesions has been associatedwith osteochondrosis and trauma. Whereas osteochondrosis was initially consideredthe exclusivepathogenesis. observations of cystic enlargement after surgery prompted further investigation into the pathogenesis of these lesions and to reasons why they may potentially expand. Work in the first author's (C.W.M.) laboratory (Ray et a11996), showed that it was possible to consistently produce (5/6 cases) subchondral cystic lesions by creating a 5 mm diameter, 3 mm deep defect in the subchondral bone at the central weightbearing portion of the medial condyle of the femur.

Other work then revealed that the fibrous tissue of subchondral cystic lesions (removed surgically) released nitric oxide, PGEz,and neutral metalloproteases into culture media after in vitro culturing. It was also shown that conditioned media of the cultured tissue was capable of recruiting osteoclasts and increasing their activity (von Rechenberg et al 2000). It was therefore felt that fibrous tissue could play an active role in the pathologic processesof bone resorption occurring in the subchondral cystic lesions and may be partially responsible for the slow healing rate and expansion of these lesions. For this reason, the first author (C.W.M.) has in recent years injected corticosteroids at the time of surgical debridement. Recentreports by Sandler et al (2002) suggest that simple debridement still has a high success rate. On the other hand, reports of arthroscopic intralesional injection of corticosteroids (Vandekeybus et al 1999) have prompted evaluation of this technique and this will also be described.

Technique

other options that have beenused. Historically,cancellous bone grafting has beenused (Kold & Hickman 1984), but resultswith this techniquethrough arthrotomy at leastwere not as goodas simple debridement(White et aI1988). More recently,somecontrolledwork with cancellousbonegrafting in experimentallycreated 12.7 mm diameter and 19-mm deepdefectsin the medialfemoral condyle and a 6-month

The authors have previously used a cranial arthroscopic portal between the middle and lateral ligaments with a cranial instrument portal medial to the arthroscopic portal initially.

The technique developed by Lewis (1987) is superior, however, and is now routinely used by the author. This latter technique is described here (Figs 6.63 and 6.64).

The procedure is performed with the horse under general anesthesia in dorsal recumbency. The leg is flexed such that the stifle and hock are approximately at 900 angles. Stabilizing the leg in this position is recommended. The medial femorotibial joint can be distended with irrigating solution, but for experienced surgeons, this is generally not necessary and the arthroscope is inserted through the lateral portal between the lateral patellar ligament and the origin of the long digital extensor tendon as previously described. Examination of the medial femorotibial joint is also performed as previously described.

The characteristic dimple in the articular cartilage overlying the subchondral cystic lesion is visualized (Fig. 6.65) and the location for the instrument portal is determined by placement of a needle (seeFig. 6.64A). The instrument portal

I' ~

Femoropatellarand FemorotibialJoints

madeusing an 8 mm incision through the skin and and a stab through the joint capsulewith a No. 11 .This portal must be positionedso that site of the lesionperpendicular the articular surface to enable effective surgical maniare removed by using a curette and rongeurs (see In someinstancesa motorizedburr is usedto assist The configurations of the cystic lesions at arthroscopy and can be multi-loculated. Typically debridement of subchondral tissue continues to normal bone. Because

be a difficult decision.Cartilagethat is overhangingthe

hole is conservatively cut back to gain sufficient accessto the cystic lesion, but not more than that. More recently, one of the authors (AJN)has beenusing cancellous bone graft in the base of the cystic lesion and adding fibrin with cells on top (see Chapter 16). Although drilling of the cystic lesion has been abandoned because it appeared to be associated with enlargement of cysts (Howard et al1995), micro fracture has been perfomed in the walls of the cystic lesions and it is a subjective impression that it is quite useful.

Following debridement, the joint is lavaged liberally and suction is also applied after this procedure. The skin portals are closed with simple interrupted sutures. Care is taken during initial debridement of the contents of the cyst to remove defective tissue immediately from the joint and to

minimize debris accumulation elsewhere. Debris is released into the joint. but it generally accumulates in the intercondylar area lateral to the medial condyle. A special effort is made during lavage and suctioning of the joint to remove all debris from this area.

Postoperative management Perioperatively,the horse receivesprocaine penicillin and phenylbutazone. The patient is confined to a stall for 2 months. Hand walking commencesat the time of suture removal. A minimum of 4 more months pasture rest is recommendedbefore training resumes.Training should resumeonly if the horseis sound at a trot afterthis time. In the series of casesreported by Lewis. the postoperative convalescence in casesthat were ultimately successful varied from 4 to 18 months and averagedapproximately7t months (Lewis1987).

Results In the series reported by Lewis, complete soundness for intended use was achieved in 34 of the 67 cases based on follow-up information from the owners. In addition, 14 horses were sound enough that they were used as intended, despite occasionalmild lamenessin the affectedlimb. Of the remaining 19 horses, various degrees of residual lameness presented a problem for athletic use as intended; however, some animals were used for less stressful activities and were satisfactory in that respect. In summary, the overall satisfactory outcome for intended use was 72% (48 of the 67 cases).Of the 19 failures for intended use, 11 were from a group of 28 potential racehorses, producing a 39% failure rate. Eight were from a group of 39 horses intended for other use (cutting, reining, roping, and pleasure), representing a 21 % failure rate in these types of horses. Lewis concluded that several factors could affect the prognosis, including age (younger horses in general had a better prognosis), unilateral versus bilateral lesions (cases of bilateral involvement were somewhat less successful),significant training or use before surgery (generally decreasedthe prognosis), previous administration of intra-articular medication (subjectively, the author thought prior corticosteroid injection was detrimental to the ultimate outcome), radiographic appearance (the broader opening of the cyst at the articular surface was associated with a less favorable prognosis), pre-existing degenerative joint disease (poorer prognosis), and intended use (racehorseswere the most difficult to return to intended use).

Howard et al (1995) described the results of arthroscopic surgery for subchondral cystic lesions in the medial femoral condyle in 41 horses. There were 17 Quarter Horses, 15 Arabians, 8 Thoroughbreds, and 1 Holsteiner with 28 (68%) of the horses being 1-3 years old. For all horses, the owner's complaint was mild to moderate hind limb lameness, or an altered gait. Bilateral radiographic abnormalities of the medial femoral condyle were detected in 27 horses. Nineteen of the 27 horses had lesions identified bilaterally at arthroscopic surgery. In addition to the subchondral cystic lesion, 13 joints

in 11 horses had an osteochondritis dissecans lesion from the opening of the subchondral cystic lesion. ~ debridement performed by arthroscopy was the only ment for 37 lesions in 23 horses. drilling of the defect bed was performed in 23 lesions 18 horses. Complete follow-up information 39 horses: 22 (56%) horses had a successful result 17 (44%) horses had an unsuccessful result. results because of factors not directly attributed to subchondral cystic lesion of the medial femoral (censored analysis), 23 of 31 ' result and 8 of 31 (26%) horses had, Within this group of horses, the prognosis for a sex, size of ] lesion was drilled, the presence of with the subchondral cystic lesion, or whether the enlarged after surgery. Compared Arabians, Quarter Horses had a poorer] Follow-up radiographs were available for 14 horses. these 14 horses, the subchondral cystic lesion -significantly with drilling of the lesion bed at the time surgery.

Lesions were classified on radiographic appearance either Type I lesions (10 mm or less in depth. surface of II lesions (more than 10 mm in depth and conical or spherical) (see Fig. 6.61B), or Type ill (flattened or irregular contours of the subchondral j the distal aspect of the medial femoral condyle. 1 regression showed a significant association between types as assessedfrom preoperative radiographs and ~ types based on surgical assessment. However, '

in six joints; of the SCL that appeared to be Type I

were later determined to be Type I on the basis of scopic findings. Of the 15 joints that appeared to ~ three had a Type I SCL.six: four appearedto be norma

attachedto the subchondralbone on palpation and no surgical treatmentwas done; however. stifle of thesehorsesdid havea surgicallesion. not performedon two of the joints with a SD. Given lesional injection of 40 mg of MPA (Depo-Medrol@)to regime. The latter technique ' -

supported by more recent work demonstrating that fibroustissueof

cause

achieving

lesionwas (Howard et al amount of surface disrupted by measured at the 1 into two groups: those with lesions that involved or less cartilage surface and those with greater 15 mm of disruption. During the period between 1989 150 clinically lame Thoroughbred horses with a 214 subchondral cystic lesions had surgery. Of the 86 (58%) horses had unilateral lesions and 64 were raced, whereas 77% of the siblings whereas 71% of males raced; 61 % (79) of the horses raced as 3 year oIds, and 51%

(55) of the horses raced as 4 year olds. The number of starts and average earnings per start for the horses that had been operated on were less than their maternal siblings for their 2- and 3-year-old racing careers, but were similar to their siblings for the 4-year-old racing year. Of the 49 horses with Type I lesions, 34 (69.3%) horses started a race in their career, whereas 62 (61.3%) horses with Type II lesions started. This indicated that radiographically assessedlesion depth was of little consequencein defining the prognosis.

Additionally, there were 91 (60.6%) horses with less than or equal to 15 mm of surface debridement and 59 (39.3%) horses with greater than 15 mm of surface debridement. Of the 91 horses with 15 mm or less of surface disrupted, over 70% started at least one race, whereas only about 30% of the 59 horses with greater than 15 mm of cartilage surface involvement started a race. The amount of cartilage surface affected seemedto be a better predictor of successthan lesion depth.

Most recently, one author (C.W.M.) has treated a number of cases with intralesional injection of corticosteroid (triamcinolone acetonide) under arthroscopic visualization (Fig. 6.66). In 2-year-old Thoroughbreds, everyone at this stage has been able to go back into training at 2 months, with already some increased density in their cystic lesions. The

results are very preliminary. The technique's rationale is basedon the findings of von Rechenberget al (2000). It is possiblethat this technique offers an ability to return the athlete to racing more quickly than arthroscopicdebridementdoes.

Articular cartilage lesions on medial condyle of femur These cases will be detected during diagnostic arthroscopy of the stifle. A typical signalment will be lameness with possible synovial effusion, positive response to hind limb flexion tests and response to intra-articular local anesthesia of the stifle (Schneider et al199 7). Lameness will be localized to the stifle by analgesia and the diagnosis confirmed with arthroscopic examination. Diagnostic arthroscopy of the medial femorotibial joint is performed as previously described. Of 12 joints in 11 horses that were affected with this condition and described by Schneider et al (1997), all horses had focal areas of damage to articular cartilage on the weightbearing surface of the medial femoral condyle. Cartilage was dimpled, wrinkled, and folded and was not firmly attached to the subchondral bone (Fig. 6.67). Palpation of damaged cartilage with a blunt arthroscope probe consistently revealed an area of loose cartilage through which the probe could be easily inserted into the subchondral bone. Fibrillation and exposure of subchondral bone were also evident in some horses. The location of the lesions was at the same site as for horses with medial femoral condylar cysts. Areas of separated cartilage should be debrided. In some instances of extensive damage, what can be done surgically is limited as extensive debridement will not produce a successfulresult.

In the report of Schneider et al (1997), follow-up information was available for all horses. Six of seven horses that were treated for focal cartilage lesions recovered completely and resumed activities (successful racehorse, horse used in three-day eventing, jumper, dressagehorse, trail riding horse, and pleasure horse). One racehorse that had intermittent lameness in the affected limb did not resume activities. Only 1 of the 4 horses with generalizeddamageto articular cartilage became clinically normal (show horse that was retired and used for pleasure riding). Two of the other 3 horses were

Standardbredracehorsesand the remaining case was a Quarter Horse used for ranch work. Thesehorses were unable to resume their previous activities as a result of persistent lameness. It is therefore concluded that horses with generalized cartilage damage have a poor prognosis for becoming clinically normal and performing well after treatment.

Subchondral cystic lesions of the proximal extremity of the tibia in horses This condition is relatively uncommon. When it occurs, it is typically present at a young age. In one report of 12 cases,the mean age of these horses at presentation was 12.3 months

old, with a range of 6-24 months old (Textor et al 2001).

Horses will present with severity of lameness from 0 to 3 and in all casesthe lameness can be exacerbated by stifle flexion.!

Stifle joint effusion (with pouch undefined) was present in

~

6 of the 12 horses previously described. In 6 horses, intraarticular anesthesia improved the lameness in 4 horses and this was unchanged in 2 horses (these had extensive deep lesions of the lateral tibial condyle). In 6 horses the lesions were considered to be the result of osteochondrosis and were solitary lesions involving the lateral tibial condyle without other signs of joint disease(Fig. 6.68). In 5 out of 6 horses in which the lesions were considered to be the result of osteoarthritis (OA), there was a well-defined cystic lesion of the medial condyle of the tibia and signs of mild to marked OA, including remodeling the proximal extremity of the tibia,

osteophyte formation on the medial aspect of the tibia and femur, and subchondral bone sclerosis.

A technique for arthroscopic surgery has been reported (Textor et al 2001) and cases arthroscopically approached had lesions located in the cranial third of the tibial plateau. In horses with lesions involving the lateral tibial condyle, the lateral aspectof the femorotibial joint was arthroscoped using a medial portal, as described previously, with the arthroscope inserted between the middle and medial patellar ligaments.

Lesions would typically be identified cranial and immediately lateral to the lateral tuberosity of the intercondylar eminence

(see Fig. 6.68). The cranial ligament of the lateral meniscus usually obscured the stoma and the ligament was retracted cranially or bluntly divided with the probe to expose the stoma. Lesions were curetted to healthy bone.

If the lesion was located in the proximomedial aspect of the tibia (medial to the intercondylar eminence), the medial femorotibial joint was approached through a lateral portal and, again, lesions would be identified by probing through the fibers of the cranial ligament of the medial meniscus in a manner similar to that described for lesions lateral to the intercondylar eminence. In the paper of Textor et al (2001), arthroscopic debridement was performed in 4 horses in which the lesions were considered to be the result of osteochondrosis and in 3 horses with osteoarthritis. Three horses in which SCL were considered to be the result of osteochondrosis performed athletically after debridement.

Two horses with moderate OA returned to work after arthroscopic debridement, but at a lower level of athletic performance. One horse with SCLrelated to osteochondrosis responded to medical treatment and went on to race.

Fracture of the medial intercondylar eminence

tibial

Although these fractures have been associated with avulsion of the insertion of the cranial. cruciate ligament (Prades et al 1989. Mueller et aI1994).tt is the first authors experience,as well as that of Walmsley (2002), that this is not usually the case. It is quite common to have these fractures with minimal damage to the cranial cruciate ligament (Fig. 6.69-6.71). even when they are quite large. The injury can of coUrse be accompanied by damage to other structures. There is obvious lameness and signs localizing the problem to the femorotibial joint. The fracture can be diagnosed on radiographs. In cases of isolated fracture, the usual treatment is removal of the fractured portion through a cranial instrument portal in the medial femorotibial joint (Mueller et al 1994). One author has pointed out that if the fracture causes significant disruption to the surrounding tissues. lag screw fixation is preferred (Walmsley 1997). In the case described, fixation was performed using a cranial arthroscopic portal with an extra instrument portal in line with the angle of the implant.

The prognosis in these casesis related to absenceor presence of other injury in the joint. The authors have treated cases both by internal fixation and with arthroscopic removal.

Injuries to the cruciate ligaments Cruciate ligament injury in the horse was initially described

by Sanders-Shamis et al (1988) and Prades et al (1989).

Complete rupture of the cranial cruciate ligament in the horse is catastrophic and it is unusual to examine these cases arthroscopically (Fig. 6.72). Less severe injuries to cruciate ligaments can be regularly diagnosed with diagnostic arthroscopy. It has been pointed out that sometimes strains and partial ruptures may be diagnosed ultrasonographically

if the examiner has considerable experience (Cauvin et al 1996). However, arthroscopy is the preferred choice for a definitive diagnosis.

Diagnostic arthroscopy of the cranial pouch of the medial femorotibial joint can be done through a lateral or cranial portal. The cranial portal will give better overall visualization of the cruciate ligaments in the intercondylar notch, but both approaches can be used. A typical partial-thickness tear will involve the body of the cranial cruciate ligament, rather than the insertion. This is consistent with experimental work that has shown cranial cruciate ligaments fail in mid-body (Rich & Glisson 1994), at least in the pony. However, avulsion at both the tibial and femoral insertions of the cranial cruciate ligament has been reported (Edwards & Nixon 1996, Prades et al 1989). Caudal cruciate ligament injury has been described in the literature (Moustafa et al1987), but is uncommon. Caudal cruciate injuries observed arthroscopically generally appear as longitudinal shredding of the femoral origin, although radiographic lesions associated with the tibial insertion of the caudal cruciate can occasionally be seen. Cranial cruciate injury can vary from hemorrhage on the synovial membrane covering the cruciate ligaments or mild fiber disruption to more severe fiber disruption

.Grade III, a severetear of the meniscus and ligament that extends beneath the femoral condyle so that the limits of the tear cannot be seen.

It is less common to see tears of the meniscus in the caudal pouch of either the medial or lateral femorotibial joint, although this probably reflects the reduced frequency that surgeons successfully enter and examine the caudal pouches.

For meniscal tears in the cranial portion of the meniscus (medial femorotibial joint), the arthroscope is usually placed through the lateral portal, as visualization is satisfactory and it is out of the way of the instrument. Meniscal injuries seen in the horse can be categorized as vertical radial (transverse) vertical longitudinal, vertical flap or bucket handle, or as horizontal transverse (Fig. 6.74). True bucket handle tears, as seen in man are rare in the horse. A cranial instrument portal is made and the torn portion removed. This can be accomplished with a combination of Ferris-Smith rongeurs, biopsy suction forceps, or motorized equipment (Figs 6.75-6.77). The aim is to leave a clean edge of healthy meniscus. One of the authors (A.J.N.)has used intraarticular suturing of the meniscus in four horses. The meniscal tear should be clean, vertical, and relatively fresh. Suturing can be achieved by using flexible needles (Fig. 6.78) (Nitinol, Arthrex Corporation, Florida) to tie mattress sutures through the tear, and more complex tears can be sutured with a Bankart shoulder repair device (Fig. 6.79) (Arthrex Corporation, Florida) used in an upside-down configuration. Transverse vertical tears can be more difficult to trim or suture, since they orientated across the structure of the meniscus (Fig. 6.80). Additionally, they occur more commonly in the central (medial) to caudomedial portion of the meniscus and can be difficult to even visualize.

Similarly, tears of the lateral meniscus will be encountered on exploration of the lateral femorotibial joint using the portal that starts in the medial femorotibial joint. Access can be a little more difficult with the arthroscopic portal in this joint as the long digital tendon and popliteal tendon are both present intra-articularly. Avulsion fracture of the insertion of the cranial ligament of the lateral meniscus can cause meniscal instability (see Fig. 6.81). This site is predisposed, and in one author's opinion (A.J.N.), occurs as frequently as tears in the lateral meniscal body.

In the initial report of Walmsley (1995), there were 5 horses with a vertical tear in the cranial horn and cranial ligament of the medial meniscus and 2 horses with similar injuries in the lateral meniscus. All the lesions had similar characteristics and the tear was about 1 cm from the junction of the axial border of the meniscus and the cranial ligament of the meniscus ligament. In all but one case it was incomplete, with much of the torn tissue loosely attached to the axial part of the meniscus from where it was removed. The remaining meniscus abaxial to the tear was displaced cranially and abaxial and its torn edges were debrided. In those cases, 3 horses returned to full competition, 1 horse was useable for hacking, 2 were convalescing and 1 was lame after 1 year. Walmsley (1995) pointed out that these lesions were quite different from the vertical meniscal tears, which occurred in the cranial horn of the meniscus at least 1 cm

abaxial to the junction of the meniscus and its cranial ligament and involved separation of meniscal tissue on either side of the tear. The author was also uncertain as to whether fraying was symptomatic or associatedwith age and use. This paper served as the hallmark for making meniscal injuries a recognizable syndrome.

A later retrospective study described 80 cases of meniscal tears in horses (Walmsley et al 2003). Inclusion criteria were: 1. Lameness localized to the femorotibial joint with clinical confidence (in most cases that involved intra-articular diagnostic analgesia).

2. Diagnostic arthroscopy identifying an abnormality in one or both of the femorotibial menisci.

3. The meniscal injury was considered to be the primary lesion in the joint.

The medial meniscus was involved in 60 casesand the lateral in 20 cases.Forty-three tears were Grade I. 20 were Grade n, and 17 were Grade Ill. Distention of either or both the femoropatellar and femorotibial joint was recorded in 31 horses, but in 14 of these, distention was recorded in only the femoropatellar joint. The relative likelihood of joint distention was nine times greater among horses with Grade n and III injuries (17/20,13/17), respectively,as compared to horses with Grade I injuries (4/43). The median lameness Grade was 3 (on a scale of 5); the response to intra-articular analgesia was positive in 59/65 horses in which it was performed and, in 45/76 horses in which the information was recorded, the flexion test worsened the lameness. Radiographic abnormalities were seenin 38 horses and increased with severity of lesions. New bone formation on the medial intercondylar eminence of the tibia occurred in 23 cases and OA of the femorotibial joint was evident in 18 cases.

Mineralization of soft tissue structures was seen in six cases.

Walmsley et al (2003) used the Outerbridge (1961) human grading system for articular cartilage lesions. Lesions in the articular cartilage of the medial femoral condyle (MFC) or lateral femoral condyle (LFC)were recorded as: .circumscribed areas of prominent fibrillation less than 1.5 cm in diameter, (similar to those graded as Outerbridge Grade 2) .generalized fibrillation extending over larger areas, associated with a parent thinning of the articular cartilage (similar to Outerbridge Grade 3) .superficial, mild fibrillation (similar to mild Outerbridge Grade 3) .full-thickness lesions of variable size in which the subchondral bone could be palpated with a probe (similar to Outerbridge Grade 4) .shear lesions or chondral flaps characterized by the presence of torn flaps of articular cartilage .thickened, softened, enfolded, or fissured articular cartilage (similar to Outerbridge Grade 1, but more severeand with fissuring) .small (about 3 mm), raised plaques of firm cartilage tissues sometimes containing shiny, yellowish tissue.

Left Tibia

A

Horizontal transverse

Vertical radial (transverse)

Bucket handle

B

Vertical Flap

Vertical longitudinal

Fig.6.74 (A)

Schematic ..

diagram

of the

menisci

and associated

ligaments.

(8)

Types

of meniscal

tears:

horizontal;

vertical

radial;

vertical

abnormalities of the femoral or recorded in 61 horses. These and 12 of 17 Grade ill tears. Full-thickness generalized fibrillation of the articular 3 and 4) lesions were recorded horses and these had a median age of 10 years old 3-22). Concurrent cranial cruciate ligament injury in 12 cases. Twenty-five other horses showed

Overall,47% of affectedhorsesreturned to full use.The Gradewas 63% for GradeI tears,56% concurrent

cruciate

injury

Of

were

the

followed

horses

up

with

more

follow-up

as

compared

to

those

that

were

did

.In

to

but

the

lesions

series

of

were

suturing.

not

It

one

of

Grade

the

cases

by

Walmsley

debrided,

was

not

III

laparoscopic

lesion

but

considered

have

et

vs

al

was

sutured

a

10/34

(2003),

consideration

was

practical

extracorporeal

lame

not

75%

I

and

radiographic

in

using

knotting

most

the

technique (Sopera & Hunter 1992) with No.3 polYglactin 910 (Vicryl).

Meniscal tears, particularly the longitudinal tears described by Walmsley et al (2003) as Gradeill, can progress into the mid-portion and even the caudal horn of the meniscus. Any meniscal tear where the abaxial (medial) and caudal termination cannot be discerned needs to be explored further by examination through the caudal joint pouch of the femorotibial joint. Discrete tears of the caudal horn of the

~

medial meniscus can also occur (Fig. 6.82). The authors now always examine the caudal portion of the medial femorotibial joint. even if a tear in the cranial horn appears contained.

The medial meniscus is predominately affected; the lateral meniscus caudal horn has been involved only once in our experience.Vertical longitudinal tears of the medial meniscus have also been seen(Fig. 6.83). Mineralization of the meniscus is a late-stage development (Fig. 6.84) and frequently signals chronic meniscal tearing. Surgical aims in mineralized cases should be to trim all protruding portions that impact on the caudal surface of the femoral condyle. debride free or fibrillated soft portions of the meniscus and suture any longitudinal tears that are not disintegrated. Manipulation of instruments in the caudal compartment is tedious. particularly since the depth of the damaged meniscus from the skin surface is often 6-8 cm. Trimming of caudal horn meniscal tissue is best accomplished with a motorized resector, particularly the large-format tooth synovial resectors such as the orbit incisor or Synovator. Removal of mineralization generally requires an arthroburr.

In common with other species, macerated tears of the menisci carry a poor prognosis for return to working soundness as the loss of fibrocartilagenous meniscal tissue is usually marked. These injuries frequently also extend into the central inaccessible regions of the meniscus so that removal of torn tissue often is incomplete.

Other indications for arthroscopic surgery in caudal pouches the caudal aspectof the femoralcondylesin foals examination of the caudal pouches has been (Hance et al 1993). We have also used this approach

The caudal compartment of the medial femoral is quite voluminous and free fragments can be the instrument portal is vital in reaching the and avoiding instruments and the arthroscope

with each other as they penetrate deeper to free pieces.

The caudal portion of the caudal r medial femorotibial joint (Fig. 6.85). However, ence of authors, disruption of the insertion of (evident radiographically) may not be visible arthroscopy. Moreover, the popliteal artery is ~ this ligament and exposure of the caudal cruciate motorized resection of the covering joint capsule would hazardous. A caudal cruciate ligament avulsion in ;' has been defined with imaging (Roseet aI2001).

Vet

, Zugang.Teil 1:

11:

.BoydJS.etaI. Ultrasonographic examination and caudal aspects.Equine Vet J 1996; 28: 285-296.

Akeson WH. Keown GR. The repair of large osteochondral defects; an experimental study in horses. Clin Orthop RelRes 1972; 82: 853-862. van Weeren PRoRadiographic development of osteochondral abnormalities in the hock and stifle of Dutch Warmblood foals. from age 1 to 11 months. Equine Vet J 1999; (Suppll) 31: 9-15.

-Nixon.

AJ. Avulsion of the cranial cruciate ligament in a horse. Equine Vet J 1996; 18: 334-336. study of 14 horses. Proceedings 48th AAEP 2002; 249-254. ~- -Mcllwraith CWoTrotter GW. Arthroscopic surgery for osteochondritis dissecans of the femoropatellar joint. Equine Vet J 1992;24: 419-423. .-Arthroscopic treatment of osteochondritis dissecans. Clin Orthop 1984; 167: 65-74. et al. Lesions of the caudal aspect of the femoral condyles in foals: 20 cases(1980-1990). J Am Vet Med Assoc 1993; 202: 637-646.

Arthroscopic surgery for subchondral cystic lesions of the medial femoral condyle in horses: 41 cases(1988-1991). J Am Vet Med Assoc 1995; 206:

842-850.

WA, Stick JA, Arnoczky Sp, Nickels FA. The effect of compacted cancellous bone grafting on the healing of subchondral bone defects on the medial femoral condyle in horses.

Vet Surg 2000; 29: 8-16.

J. Results of treatment of subchondral bone cysts in the medial condyle of the equine femur with an autogenous cancellous bone graft. Equine Vet J 1984; 16: 414, c --A retrospective study of diagnostic and surgical arthroscopy of the equine femorotibial joint. Proceedings of the 23rd Annual Meeting of the American Association of Equine Practitioners, 1987.

CWoSurgery of the hock. stifle and shoulder. Vet Clin North Am 1983; 5: 333-362.

Experience in diagnostic and surgical arthroscopy in the horse. Equine Vet J 1984; 16: 11-19.

-.Treatment of osteochondritis dissecans and subchondral cystic lesions. Proceedings of Panel on Developmental Orthopedic Disease.American Quarter Horse Association, Dallas, TX, April 1986; 21-22.

Mcllwraith CWoOsteochondral fragmentation of the distal aspect of the patella in horse. Equine Vet J 1990; 22: 157-163.

Mcllwraith CW Osteochondritis dissecans of the femoropatellar joint. Proceedings 39th Annual Meeting AAEP, 1993: 73-77.

Mcllwraith CW, Martin GS. Arthroscopy and arthroscopic surgery in horse. ContEduc 1984; 6: S43-553.

Mcllwraith CW, Martin, CS. Arthroscopic surgery for the treatment of osteochondritis dissecans in the equine femoropatellar joint.

VetSurg 1985; 14: 105-116.

Marble GP, Sullins KE. Arthroscopic removal of patellar fracture fragments in horses: 5 cases(1989-1998). J Am Vet Med Assoc 2000; 216: 1799-1801.

Martin GS. Mcilwraith CWoArthroscopic anatomy of the equine femoropatellar joint and approaches for treatment of osteochondritis dissecans. Vet Surg 1985; 14: 99-104.

Moustafa MAl. Boero II. Baker GJ. Arthroscopic examination of the femorotibial joints of horses. Vet Surg 1987; 16: 352-357.

Mueller POE. Allen D. Watson E. Hay C. Arthroscopic removal of a fragment from an intercondylar eminence fracture of the tibia in a 2-year-old horse. J Am Vet Med Assoc 1994; 204: 1793-1795.

Nickels FA. SandeR. Radiographic and arthroscopic findings in the equine stifle. J Am Vet Med Assoc 1982; 181: 918-924.

Outerbridge R. The etiology of chondromalacia of the patella. JBone Joint Surg (Br) 1961; 43: 752.

Nixon AJ. Fortier LA. Goodrich LR. Ducharme NG. Arthroscopic reattachment of select OCDlesions using resorbable polydioxanone pins. Equine VetJ 200436: 376-383 Pascoe JR. Wheat }D. Jones KL. A lateral approach to the equine femoropatellar joint. Vet Surg 1980; 9: 141-144.

Pascoe JR. et al: Osteochondral defects of the lateral trocWear ridge of the distal femur of the horse. Clinical. radiographic. and pathologic examination of results of surgical treatment. Vet Surg 1984; 13: 99-110.

Prades M. Grant VD. Turner TA. Injuries of the cranial cruciate ligament and associated structures: summary of clinical. radiographic. arthroscopic and pathological findings from 10 horses.

EquineVetJ 1989; 21: 354-357.

Ray CS. Baxter GM. Mcilwraith CWoet al. Development of subchondral cystic lesions after articular cartilage and subchondral bone damage in horses. Equine Vet J 1996: 28: 225-232.

Rich RF. GlissonRR. In vitro mechanical properties and failure mode of equine (pony) cranial cruciate ligament. Vet Surg 1994; 23: 257-265.

RosePL. Graham JP.Moore I. Riley CB. Imaging diagnosis -caudal cruciate avulsion in a horse. Vet Radiol Ultrasound 2001; 42: 414-416.

Sanders-ShamisM. Bukowiecki CP.Biller DS. Cruciate and collateral ligament failure in the equine stifle: 7 cases (1975-1985). J Am Vet Med Assoc 1988; 193: 573-576.

Sandler EA. Bramlage LR. Embertson RM. Ruggles AJ. Frisbie DD. Correlation of lesion size with racing performance in Thoroughbreds after arthroscopic surgical treatment of subchondral cystic lesions of the medial femoral condyle: 150 cases (1989-2000).

Proceedings 48th AAEP. 2002; 255-256.

Schneider RK. Jenson P. Moore RM. Evaluation of cartilage lesions on the medial femoral condyle as a cause of lameness in horses: 11 cases (1988-1994). J Am Vet Med Assoc 1997; 20:

1649-1652.

Soper NJ. Hunter JG. Suturing and knot tying in laparoscopy. Surg Clin N Am 1992; 72: 1139-1152.

Steinheimer DN. Mcilwraith CWoPark RD. Steyn PF. Comparison of radiographic subchondral bone changes with arthroscopic findings in the equine femoropatellar and femorotibial joints.

A retrospective study of 72 horses. Vet Radiol 1995; 36: 478-484.

Stick JA. Borg LA. Nickels. Peloso JG. Perau DL. Arthroscopic removal of an osteochondral fragment from the caudal pouch of the lateral femoral tibial joint in a colt. J Am VetMed Assoc 1992; 200: 1695-1697.

Textor JA. Nixon AJ. Lumsden J. Ducharme NG. Subchondral cystic lesions of the proximal extremity in horses: 12 cases (1983-2000). J Am Vet Med Assoc 2001; 218: 408-413.

Trotter CW Mcilwraith CWoNorrdin RW A comparison of two surgical approaches to the equine femoropatellar joint for the treatment of osteochondritis dissecans. Vet Surg 1983; 12: 30--40.

Trumble TN. Stick JA. Arnoczky SP. RosensteinD. Consideration of anatomic and radiographic features of the caudal pouches of the femorotibial joints of horses for the purpose of arthroscopy. Am J Vet Res1994; 55: 1682-1689.

Turner TA. Nixon AJ. Brown M. Prades MA. Injuries to the anterior cruciate ligament in sevenhorses(Abstract). VetSurg 1988; 17: 38.

Vandekeybus L. Desbrosse F. Perrin R. Intralesional long acting corticosteroids as a treatment for subchondral cystic lesions in horses. A Retrospective Study of 22 Cases. Proceedings of the 8th annual scientific meeting of the European College of Veterinary Surgeons 1999 33-34. von Rechenberg B. Guenther H. McIlwraith CWoet al. Fibrous tissue of subchondral cystic lesions in horses produce local mediators and neutral metalloproteinases and cause bone resorption in horses. Vet Surg 2000; 29: 420-429.

Walmsley Jp.Vertical tears of the cranial horn of the meniscus and its cranial ligament in the equine femorotibial joint: 7 casesand their treatment by arthroscopic surgery. Equine Vet J 1995; 27: 20-25.

Walmsley JP. Fracture of the intercondylar eminence of the tibia treated by arthroscopic internal fixation. Equine Vet J 1997; 29;

148-150.

Walmsley JP. Arthroscopic surgery of the femorotibial joint. Clin Techn Equine Prac 2002; 1: 226-233.

Walmsley JP.Philips TJ.Townsend HGG. Meniscal tears in horses:an evaluation of clinical signs and arthroscopic treatment of 80 cases.Equine Vet J 2003; 35: 402-406.

White NA. Mcllwraith CWoAllen D. Curettage of subchondral bone cysts in medial femoral condyles of the horse. Equine Vet J Suppl 1988; 6: 120-124.

Wyburn RS. Degenerative joint disease in the horse. NZ Vet J 1977; 25: 321-322, 335.

.

~

tarsocrural (tibiotarsal) joint has proven highly both diagnosticand surgical arthroscopy.The the other joints, new discoveries have caused in the indications for diagnostic arthroscopy as as an increase in the spectrum of surgical conditions tarsocrural joint. For instance, before the use of surgical intervention was not considered a tarsocrural joint manifesting effusion and/ unless it had a radiographic lesion. Now we that not all cases of tarsocrural OCD, for instance, radiographically. Although this finding further the limitations of radiographs, it does, however, to define and treat cases of "idiopathic synovitis" undefined. In addition, other joints, OCD can be treated conveniently with and the same advantages exist.

The tarsocrural joints are shaved on both sides of the joint.

The draping system includes an adhesive barrier and impermeable drapes (Fig. 7.1). The joint is distended before making the skin incisions. The skin incisions for the arthroscopic and instrument approaches are located to the sides of the group of extensor tendons on the dorsal aspect of the joint (the long digital extensor, the peroneus tertius, and the cranialis tibialis tendons). These structures are collectively referred to in the remainder of the text as the extensor tendons. As a general principle, all portals are made close to (approximately 1 cm from) the extensor tendons to maximum visualization.

Arthroscopic dorsomedlal

examination approach

using a

The dorsomedial approach is used most commonly. If the arthroscopic portal is made close to the cranialis tibialis and peroneus tertius tendons. a large portion of the dorsal aspect of the joint can be seen. The approach provides excellent visualization of the cranial or dorsal compartment of the tarsocrural joint. including the trochlear ridges and trochlear diagnostic arthroscopy in the tarsocrural dorsal and plantar. The dorsal approach a dorsomedial (craniomedial) arthroscopic portal. approach involves a plantarolateral or plantaro arthroscopic portal. Most arthroscopic cases involve , ,.

In the previous

were described. However. with the exception of the lateral malleolus of the tibia. a dorsolateral .An appropriately placed areas where surgery is done. Therefore diagnostic in this text are now limited to those seen with a ..approach.

In all situations, the patient is in dorsal recumbency. This which is important for triangulation. but also the flexion of the joint is easily controlled. The leg may or hangs free. With relevance to arthroscopic also minimizes the risk

groove of the talus. Flexing and extending the joint, which brings different areas of the trochlear ridges into view, can increase the area of visualization. The corresponding area of the distal tibia from the medial malleolus to the distal intermediate ridge is also visible. Many adult horses also have an opening that allows visualization of the proximal intertarsal (talocentral) joint distally. Inspection of the synovial lining of the dorsal aspectof the tarsocrural joint can also be performed.

The joint is distended using a needle placed through the dorsomedial pouch with the leg in extension (see Fig. 7.1).

The skin portal is made slightly dorsal to the center of the distended dorsomedial outpouching and just below the palpable distal end of the medial malleolus. and the arthroscopic sleeve and conical obturator are inserted (Fig 7.2).

This position is ideal for visualization within the joint. If the arthroscope is placed more medially, it is difficult to pass the arthroscopic sheath over the trochlear ridges of the talus across the joint. The skin portal is made sufficiently large (8-10 mm) to ensure that the saphenous vein is not directly beneath the incision and to avoid its penetration. In many horses, the arthroscope portal can be made between the saphenous vein and the extensor tendons, and this location provides optimal visualization of the deeper region of the intermediate ridge. A No. 11 blade is then used to continue the portal through the fibrous capsule. The sleeveand conical obturator are then inserted until contact with the medial side of the talus is made (Fig. 7.2). The joint is then flexed, enabling the arthroscopic sleeveand obturator to pass across the joint, over the top of the trochlear ridges. and beneath the extensor tendons (this maneuver is impossible in an extended joint).

The arthroscopic portal can also be made with the joint flexed, eliminating the need to flex the joint during placement of the sheath; however. the landmarks (as well as location of the saphenous vein) are more easily identified with the limb in extension.

Examinationcommenceson the lateral and its articulation with the tibia. This view lateral malleolus (Fig. 7.3). c visualize the central lateral trochlear ridge (Fig. further distad, the distal part of the lateral comes into the visual field (Fig. 7.5). In this of the arthroscope. The view of the arthroscope

and the arthroscopeis withdrawn oriented in a plantar direction to of the trochlear groove of the talus (Fig. ' of the trochlear groove is visible further distally addition. the talocentral (proximal intertarsal) j visualized (see Fig. usually patent in very young foals. A

the talus (Fig. 7.7E).

Further withdrawal of the arthroscope rotation, so that the view is proximal and visualization of the proximal ridge and its articulation with the distal tibia (Fig. the medial malleolus is possible (Fig. 7.9). The aspects of the medial trochlear ridge can be -

allows examination of the medial side of dorsomedial pouch (Fig. 7.12).

With this approach. imposition of soft tissue sometimes makes examination of the lateral trochlear ridge and other

(Tibiotarsal) Joint

areasof the lateral part of the joint challenging.It requires the end of the arthroscopeto be closeto the lateraltrochlear ridge of the talus along with the use of the instrument to retract soft tissue. However,with practice, this becomes reasonablyeasy.

Arthroscopic examination using plantar lateral or plantar medial approaches These approaches are used far less commonly. They allow excellent visualization of the remaining (proximal) portions of the lateral and medial trochlear ridges that are not visualized by using the previously describeddorsal approaches.

Eachtrochlear ridge is bestevaluated by using an arthroscopic approach through the same side (Fig. 7.13). The principal benefit of using the plantar approaches is allowing examination of defects in the proximal portion of the trochlear ridges. the removal of loose bodies in the plantar pouch, and the treatment of sepsis and osteomyelitis. This approach sometimes also is useful to access fractures of the lateral malleolus of the tibia. Virtually all of the synovial lining of the plantar joint pouch can be inspected through use of these

approaches. Additionally, the planfar aspect of the distal tibia and the deep digital flexor tendon (DDFT) within its tendon sheath can be seen,but these observations have not provento be of major clinical relevance. Since the second edition, the approach to the plantar pouch has been reported in the refereed literature (Zamos et al 1994). Joint distention is critical for the plantar lateral approach, and is done by placing a needle in the center of the plantar pouch which usually allows adequatedistention. The skin portal is made in the center of the plantar outpouching with the tarsus flexed at 90째. The arthroscopic sheath is placed in the joint using the blunt obturator. The surgeon should be careful to avoid damaging the trochlear ridges of the talus. Viewing commences with the hock flexed (Fig. 7.13).

Introduction of the arthroscope through a plantaromedial or plantarolateral portal located in the center of the plantar pouch puts the arthroscope immediately dorsal to the tarsal synovial sheath surrounding the DDFT and plantar to the trochlear ridges of the talus. This permits evaluation of the plantar aspects of the medial and lateral trochlear ridges of the talus as well as the trochlear groove, the distal tibia (plantar aspect of intermediate ridge) and the articular portion of the tendon sheath containing the DDFT (see

~ 2.

7.13). Througha plantarolateralarthroscopicportal. the c

-

and the lateral malleolus can also be observed if .,

.,

, Withdrawing

the arthro-

If a plantaromedial arthroscopic portal is used, directing arthroscope dorsally allows observation of the dorsomalleolus cannot be seen.

spavin) is noted in the young horse, even when the radiographic signs are negative. In addition, arthroscopy is an excellent means by which to evaluate the joint in a case of severe synovitis, suspected The general aspects of discussed in Chapter 3. Septic young horse can be evaluated and

Chapter14. Arthroscopyalso permits identification of soft tissuelesionssuchastearsof the collateralligaments.within or communicating with the tarsocrural joint. As in otherjoints. arthroscopyis superiorto radiographicexaminationor synovialfluid analysisfor diagnosisin the tarsocruraljoint.

By extending the joint more (approximately 120째), the , and lateral dorsal cul-de-sacs of the joint can be enhanced examination of the proximal areas of the

arthroscopy joint

of the

The most common indication for arthroscopyin the tarsocrural joint is for the surgical treatment of OCD.In some instances. however. OCD is .and

Arthroscopic surgery has proven to be an excellent tool in the tarsocrural joint and is indicated for the following conditions; 1. Osteochondritis dissecansof the distal intermediate ridge dissecans of the lateral and medial

examination.For this

3.

4. Osteochondritisdissecansof the medial malleolus of the tibia.

5. Removalof lateralmalleolarfragments.

6. Debridementof septiclesionsof the trochlear ridges of the talus.

7. Removalof fibrin in septicarthritis.

8. Treatmentof someforms of proliferativesynovitis.

9. Traumaticlesionsand osteoarthritis.includingdiagnostic arthroscopyin casesof lamenessand hemarthrosis.

10. Intra-articular fracturesof the tarsocruraljoint.

11. Retrieval of fragments from the talocentral (proximal intertarsaljoint).

12. Tears/avulsionsof the collateralligaments.13.

Tears/avulsionof the joint capsule.

Osteochondritis the tarsocrural

dissecans joint

of

In our experience, OCD of the dorsal aspect of the distal intermediate ridge of the tibia is the most common indication for arthroscopic surgery in the equine tarsocrural (tibiotarsal) joint. A review of a series of cases of OCDof 318 tarsocrural joints treated by arthroscopic surgery (McIlwraith et al19 91) provides an indication of the location of these lesions

(Table7.1).

Lesions were seen most frequently on the intermediate ridge of the distal tibia, followed by the lateral trochlear ridge of the talus, and the medial malleolus, respectively. Lesions were also seen at multiple sites in 22 joints. Loosebodies were present in 8 joints; 5 of them had separated from intermediate ridge lesions and 3 fragments had separated from lateral trochlear ridge lesions.

These lesions occurred in 203 horses (Table 7.2).

Horses with OCD of the intermediate ridge of the tibia usually have joint effusion and/or lameness. Commonly, the clinical situation is joint effusion in the young horse of yearling age; lameness is often not evident. Careful examina-

Location Intermediate ridge of the distal tibia Lateral trochlear ridge of the talus Medial malleolus of the tibia Intermediate ridge of the tibia plus the lateral trochlear ridge (both) Intermediate ridge plus medial malleolus of the tibia (both) Intermediate ridge plus medial trochlear ridge of talus Lateral trochlear ridge of the talus and the medial malleolus of the tibia (both) Medial trochlear ridge of the talus Lateral and medial trochlear ridges of the

Number of Joints

244 37 12

talus (both) Total From Mcllwraith et a11991.

318

tion, however, often reveals a gait abnormality, which may relate solely to decreased flexion in the tarsus owing to increased synovial fluid pressure.

In the 1991 retrospective study of 303 joints in which synovial effusion was recorded, it was the presenting clinical sign in 261 (86.1%). In racehorses, effusion was present in 166 joints (81 %) and absent in 39 joints. In non-racehorses, effusion was present in 95 joints (96.9%) and absent in 3 joints. The degree of lameness was not recorded consistently, but usually was designated as mild. The exception was when a severelesion was present on the lateral trochlear

.,

Tarsocrural (Tibiotarsal) joint

Once the fragment is elevated. an appropriately sized pair of grasping forceps is introduced and the fragment is grasped (Fig. 7.17). The grasping forceps are then rotated to break down any remaining soft tissue attachments and withdrawn.

As discussed in Chapter 4. the forceps should enclose the fragment. In many instances in the tarsocrural joint. however. due to the large size of fragments this is not always possible.as in the caseillustrated in Fig. 7.18. As the fragment is pulled through the joint capsule. fluid flow is again stopped to minimize the development of subcutaneous fluid extravasation. As in other joints. larger fragments may necessitate enlargement of the skin incision. Otherwise. the surgeon runs the risk of losing the fragment subcutaneously.

The defect from which the fragment was removed is then evaluated (Figs 7.16 and 7.17) and any additional fragments are removed. Light curettage elevates any tags of tissue within the defect or at the edge of the defect. which are removed with forceps or rongeurs. The surgeon must pay particular attention to the most plantar portion of the defect, where fragments may remain but cannot be visualized.

Reduced flexion and careful probing of the defect along the edge facing the trochlear groove can reveal additional fragments and these need to be loosened and removed. The joint then is lavaged copiously. Postoperative radiographs are

As with all other OCD lesions, thearthroscopic manifestations in c -~ . .""

but that crural

an

osteochondritis

in joint the

case had

dissecans illustrated an effusion

in

flap but Fig.

was

found.

no ;

~

pouch of the tarsocrural joint, or descend

the loose fragments and debridement of the primary] are needed. bandage -( and Elasticon@ -J operation. Maintenance

of J

are removed is particularly important since these incisions are prone to dehiscence and later sepsis.

The patients can be discharged from the clinic on the first postoperative day. Therefore the protocol depends on the severity of the case. Animals should be hand walked for 4 weeks and then allowed small paddock or controlled light exercise for an additional 4 weeks. Some clinicians consider the use of sodium hyaluronate or polysulfated glycosaminoglycan (Adequan@) useful 30 days postoperatively. Training can resume in 8-12 weeksunless some other clinical problem arises. Because of the early return to exercise. trainers are more willing to stop training and remedy the problem while it is fresh. The same advantages as discussed with regard to carpal and fetlock fragments apply to operations involving the tarsocrural joint.

Treatment

of osteochondritis

dissecans

of the trochlear ridges The technique for arthroscopic surgery of lesions on the lateral trochlear ridge of the talus is illustrated in Figure 7.21. Typical cases of OCD of the lateral trochlear ridge are illustrated in Figures 7.22-7.24. Defects on the trochlear I ridge may have an OCD flap in situ (Fig. 7.22), an osteo- I chondral fragment at the distal aspect of the lateral trochlear i ridge (Fig. 7.23), or both a primary lesion and a loose body remote from the lesion that is totally free or embedded in the synovial membrane (Fig. 7.24). The presenting clinical signs associatedwith OCDof the lateral trochlear ridge of the talus

may be the same as with lesions on the intermediate ridge of the tibia or they may be more severe. The severity of the clinical signs is usually related to the amount of lateral trochlear ridge that is affected.

For cases of OCD or fragmentation of the trochlear ridges, a triangulation approach using a medial arthroscope and lateral instrument portals is used (seeFig. 7.21). As discussed in the section concerning diagnostic arthroscopy, when a dorsomedial arthroscopic approach is made, the medial trochlear ridge on the near side is visualized easily, but the lateral trochlear ridge may be difficult to visualize because of the closer apposition of the extensor tendon bundle and associated joint capsule on this side. In all instances, use of a needle to ascertain the optimal site for the instrument portal is recommended. It should be recognized that the technique for lateral trochlear ridge debridement is more difficult than that used for intermediate ridge lesions. In the report on arthroscopic surgery for the treatment of OCD in 318 tarsocrural joints (Mcllwraith et alI991), one of the two surgeonswas still doing arthrotomy for lateral trochlear ridge lesions. Therefore, in that published report, the relative percentage of lateral trochlear lesions is smaller than a large population would provide because only the first author's (C.WM.) lateral trochlear ridge caseswere included. Although arthroscopic surgery for lateral trochlear ridge lesions is more challenging than for distal intermediate ridge problems, all lateral trochlear ridge lesions can be effectively managed using arthroscopic techniques.

The principles of fragment removal are the same as described for osteochondritis dissecans of the intermediate ridge. Debridement to healthy subchondral bone is important in the more involved trocWear ridge lesions. Any osteochondral flap or fragment on the trochlear ridge is elevated and removed and the lesion is debrided (Fig. 7.24). Loose bodies [13rC a-e removed. Fragments embeddedin the synovial membrane ,-짜

,-"ilJUV"'U

JJ .'-'-".1 ...'"

VJ"JU1"'.

OCD lesions on the medial trochlear ridge of the talus are rare, but do occur occasionally. When they occur, they are typically on the trochlear ridge immediately distal to the tibia when the leg is straight (Fig. 7.25). There were 3 casesin the initial series published by McIlwraith et a11991. All cases presented as typical undermining of the cartilage in this same position on the medial trochlear ridge (Fig. 7.25). The arthroscopic approach is illustrated in Figure 7.26.

Bone spurs and fragments (so-called dewdrop lesions)have been identified distal to the medial trochlear ridge of the talus. These spurs and fragments are typically extraarticular and are generally considered normal radiographic variations that are of no clinical significance (Shelley & Dyson 1986) (Fig. 7.27). Surgical intervention generally is not indicated.

Most articular lesions (depressions) on the medial trochlear ridge of the talus are incidental findings at arthroscopy (see

Osteochondritis dissecans of the medial malleolus of the tibia mentation of the I mon location and th

dial malleolus is tht:Iinical. nIrQ Irgical.

radiographic.

L

distal to the level of the arthroscopic portal. The fragment is then elevated away using an elevator or osteotome,depending on the degree of attachment remaining before fragmentation is removed and the defect debrided (Figs 7.30 and 7.31).

M

Results of arthroscopic surgery for treatment of osteochondritis dissecans of the tarsocrural joint

findings are consistent with OCD.The axial intraportion of the medial malleolus is affected. Such must be distinguished from fractures of the medial that typically involve the entire malleolus, exmanifestations of OCD in the medial malleolus

.

in our experience. the more common situation is the , effusion and/or lameness when animals are broken or beginning with race training or racing. usually confirm the presence of a lesion (Fig. 7.28),

A dorsomedial arthroscopic portal is used (Fig. 7.29). The , is extended. A needle is then used to decide on the position for the instrument portal. but because of positioning of the fragment it needs to be also in the pouch and is axial to the arthroscopic portal 7.29). The instrument portal is axial and usually slightly

The results of arthroscopic surgery for the treatment of OCD in 318 tarsocrural joints in 225 horses have been reported (Mcilwraith et al 1991). Arthroscopic surgery was an effective technique for treating OCD of the tarsocrural joint.

The overall functional ability and cosmetic appearance of the limbs were excellent. Post-surgical follow-up information was obtained for 183 horses, of which 140 (76.5%) horses raced successfully or performed their intended use following surgery. Of the remaining 43 horses, only 11 horses were still considered to have a tarsocrural joint problem. Nineteen horses developed other problems precluding successful performance, 8 horses were considered poor racehorses without any lameness problems, 3 horses were euthanized because of septic arthritis (all associated with the horse getting the bandage off within 24 hours of surgery), and 2 horses died from other causes.There was no significant effect of age, sex, or limb involvement on the outcome. The successrate relative to three size groups for intermediate ridge lesions was 27/33 (81.8%) for lesions 1-9 mm in width, 86/116 (74.1%) for lesions 10-19 mm in width, and 41/47 (87.2%) for lesions 20 mm or more in width (no significant difference).

When successrate was considered relative to the findings of additional lesions at arthroscopy, 16/19 (84.1%) with articular cartilage fibrillation, 5/10 (50%) with articular cartilage erosion or wear lines (seeFig. 7.32),3/5 (60%) with loose fragments (Fig. 7.33), 0/2 with proliferative synovitis and 0/1 with joint capsule mineralization were successful.

There was a significantly poorer outcome in racehorses with articular cartilage degeneration or erosion (p < 0.05).

The synovial effusion resolved in 117/131 racehorse joints (89.3%) and in 64/86 non-racehorse joints (74.4%).

The outcome for synovial fluid effusion was significantly inferior for lesions of the lateral trochlear ridge of the talus and medial malleolus of the tibia compared to distal intermediate ridge lesions. There was no significant relationship between resolution of effusion and successful performance outcome.

More recently, the results of 64 Thoroughbreds and 45 Standardbred horses treated for OCD of the tarsocrural joint with arthroscopic surgery prior to 2 years of agewere reported and were compared to those of other foals from the dams of the surgically treated horses (Beard et al 1994). For the Standardbreds, 22% of those who had surgery raced as 2 year olds and 43% raced as 3 year olds, compared with 42% and 50% of the siblings that raced as 2 year olds and 3 year olds respectively. For the Thoroughbreds, 43% of those that had surgery raced as 2 year olds and 78% raced as 3 year olds compared with 48% and 72% of the siblings that raced as

These

2 year olds and 3 year olds, respectively.The median number of starts for surgically treated horses was lower than the median number of starts for siblings for all groups except 3year-old Thoroughbreds. Median earnings were lower for affected horses than for siblings for both breeds and both age groups. There was a tendency for horses with multiple lesions to be less likely to start a race than horses with only a single lesion; however, the difference was significant only for 2-yearold Standardbreds. Mfected Standardbreds and Thoroughbreds were less likely to race as 2 year olds than were their siblings. It is noted that this study was quite different from the first follow-up study (McIlwraith et al 1991); the selection criteria and control groups were different and racing performance was not analyzed by year in previous studies. In another study, horses treated for OCD of the dorsal intermediate ridge of the tibia performed as well as matched controls (Laws et aI1993).

Subchondral cystic lesion of proximal trochlear groove of talus

uptake of technetium on a bone scan and diagnostic arthroscopy detected a hole and cystic lesion in the trochlear

lesionsare uncommon,but havebeenseen(Fig,7.34).Thegroove (using a plantar approach). A medial plantar case illustrated in Figure 7.34 showed an increased arthroscope approach and a lateral plantar instrument entry

allow debridement of trochlear groove cystic lesions. Some lesions can be quite deep,despite minor radiographic abnormalities (Fig. 7.34). Flexion of the joint after insertion of the arthroscope is used to exposethe cyst entry. Needle insertion then guides the instrument portal.

Fractures of the lateral malleolus These fragments are encountered less commonly than OCD fragments and appear to be traumatic in origin. The important point to note with fragments of the lateral malleolus is that a relatively small portion of the lateral malleolus is actually intra-articular; most of it is enclosed within the collateral ligaments. A caseexample is provided in Figure 7.35. Both a dorsolateral arthroscope and instrument portals are used and the arthroscope portal is axial to the instrument portal.

This permits dissection of the fragmentation from the lateral collateral ligaments and then removal and subsequent debridement of the parent bone and ligamentous attachments.

If fragmentation runs the full dorsoplantar width of the lateral mallelous. the arthroscope can usually be pushed through the traumatic defect. from the dorsal to the plantar compartments of the joint. Sometimes there will be fragmentation that will hinge on the short collateral ligaments into the plantar pouch or indeed become loose bodies in the plantar pouch and these can be retrieved with the arthroscope passing from dorsal to plantar and an instrument portal created laterally in the plantar pouch. Such procedures are difficult. because most of the fragments are embedded within soft tissue. and inexperienced arthrocopists may use radiographic localization with needles and/or external dissection down to the fragment.

Other intra-articular tarsocrural joint

fractures

of the

These fractures are relatively uncommon. Figure 7.36-7.39 show some examples of cases that may be encountered.

Fractures can occur through the medial malleolus of the tibia and will show different manifestations than medial malleolus OCD.There will be an obvious linear fracture line and usually the fragment is displaced distally (Fig. 7.36). The fragments are removed arthroscopically and prognosis will be related to whether the long medial collateral ligament can be left intact.

Fragments may occur off the proximal plantar aspect of the medial trocWear ridge (Figs 7.37 and 7.38) and are operated on using an approach through the plantar pouch. Larger

displaced fracture fragments may also occur off the medial trochlear ridge (Fig. 7.39).

Occasionally,fractures amenable to lag screw fixation will occur in the talus; these are usually in a sagittal plane (Fig. 7.40). Small linear fractures have been repaired with one screw, but the cases illustrated in Figure 7.40 required three cortical screws.

Retrieval of fragments talocentral (proximal intertarsal) Joint

from the

Fragments will occasionally be seenin the dorsal talocentral joint. They are often under a plica or a fibrous membrane. The dorsomedial arthroscopic portal is the same for all other surgery and allows visualization into the talocentral joint (Fig. 7AI). A needle is used to decide on optimal placement of the instrument portal. In some cases, a medial instrument portal will be satisfactory, while in most we have used a lateral instrument portal to retrieve the fragment from under the joint capsule or plica. Exchange of arthroscope and instrument portals may be useful and in several cases,a third incision, medial and distal, in the dorsomedial joint pouch has been required. Resection of the perimeter of the opening between the tarsocrural and talocentral joints is often necessary to identify and retrieve loose fragments from the dorsomedial recess of the joint (Fig. 7AI).

.,

Tarsocrural (Tibiotarsal) joint

Tears and avulsions of the collateral ligaments of the tarsocrural joint Tearsof the collateralligamentsare most commonlaterally.

The majority involve the short collateralligamentsonly. A will havelong collateralligamentinvolvement.and less the shortmedialligament.All present with lameness.tarsocrural distention. and

phase and later there may be an irregular abaxial to the malleolus. Ultrasound usually detectsdis(Fig. 7.42). Arthroscopically,the torn ligamentous into the dorsal compartmentand is with a motorizedresector(Fig.7.43).

Treatment

of proliferative

synovitis

Occasionally, severe proliferative synovitis occurs in the tarsocrural joint, and debridement of some of the tissue (partial synovectomy) can offer some relief" The authors have used both hand instrumentation or motorized instrumentation (the latter is usually better) for debridement in these cases.

Treatment of septic arthritis osteomyelitis

and septi

The use of arthroscopy in the treatment of septic osteomyelit lesions of the talus was mentioned previously. ArthroscoI has also been used to remove fibrin from patients wit septic arthritis and is considered to emulate the successfl results achieved with arthrotomy (Bertone et aI1987). Tl. management of sepsis in synovial structures is discussed i Chapter 14.

Aftercarl Careful maintenance of a bandage postoperatively is critic; (Fig. 7.44). As discussed with regard to osteochondrit dissecansin the intermediate ridge, routine aftercare involv( 1 month of stall rest with hand walking and then son: limited exercise before training commences at 2-4 month depending on the amount of disease. In cases of oste( arthritis or septic arthritis, the period of convalescence m8 vary. In cases of proliferative synovitis, anti-inflammatoI therapy is often indicated. Intra-articular corticosteroi administration also has been used.

Reference: Beard WL, Bramlage LR, SchneiderRK. EmbertsonRM. Post-operativ racing performance in Standardbreds and Thoroughbreds wit. osteochondrosis of the tarsocrural joint: 109 cases(1984-1990 JAmVetMedAssoc 1994: 204: 1655-1659.

Bertone AL. McIlwraith CWoJones RL. et al. Comparison of variou treatments for experimentally induced equine infectious arthritii AmJ Vet Res 1987: 48: 519-529.

Dik KJ. Emerink E. van Weeran PRoRadiographic development ( osteochondral abnormalitis in the hock and stifle of Dutc Warmblood foals from age 1 to 11 months. Equine Vet J 199~ Suppll. 31: 9-15.

Hoppe F. Radiological investigations of osteochondrosis dissecansi Standardbred Trotters and Swedish Warmblood horses. Equin VetJ 1984: 16: 425-429.

Laws EG. Richardson DW. Ross MW. et al. Racing performance i Standardbreds following conservative and surgical treatment fc tarsocrural osteochondrosis. Equine Vet J 1993: 25: 199-202.

McIlwraith CWoSurgery of the hock, stifle and shoulder. Vet Cli North Am Large Anim Pract 1983: 5: 333-362.

McIlwraith CWoFoerner JJ,Davis DM. Osteochondritis dissecans c the tarsocrural joint: Results of treatment with arthroscopi surgery. Equine Vet J 1991: 23: 155-162.

McIlwraith CWoFoerner JJ.Diagnostic and surgical arthroscopy 4 the tarsocrural joint. In: McIlwraith CW (ed). Diagnostic an surgical arthroscopy in the horse. 2nd edn. Philadelphia; Lea an Febiger,1990: 161-193.

Shelley J. Dyson S. Interpreting radiographs. 5. Radiology of tl: equine hock. Equine VetJ 1984; 16: 488-495.

Zamos DT. Honnas CM, Hoffman AG. Arthroscopic approach an intra-articular anatomy of the plantar pouch of the equir tarsocruraljoint. Vet Surg 1994; 23: 161-166.

.

surgery of the shoulder is not a common in horses and two of the authors' (C.W.M. and experience over 20 years includes only 114 cases, all but eight of those cases involving osteochondrosis. techniques for performing arthroscopic surgery of the

have been described:a craniolateral approach.

shoulder joint immediately caudal to the infraspinatus (Nixon 1987. Bertone & McIlwraith 1987b). In the use of arthroscopic surgery for treating osteoand the results achieved in 11 horses (13 have been published (Bertone & McIlwraith 1987a). (Note: in this discussion osteochondrosis is a collective term for osteochondritis dissecans (OCD) and subchondral cystic lesions, as both commonly occur together.)

Conservative (non-surgical) treatment of osteochondrosis of the shoulder has met with minimal success,particularly In the limited numbers of horses able to enter athletic activities (Meagher et al 1975, Nyack et al 1981, Rose et al 1986).

Rapid onset of osteoarthritis and a general delay in definitive diagnosis often limit the response to surgery. Early surgical reports describe several animals that responded well to treatment by arthrotomy (Schmidt et a11975, Mason & Maclean 1977, DeBowes et al 1982, Nixon et al 1984); however, extensive soft tissue dissection is necessary and the craniomedial aspect of the joint may not be visualized (Nixon et al 1984). Other complications include loss of lateral joint stability (Schmidt et al 1975) and seroma formation (Nixon et al 1984). These complications are not only avoided with arthroscopy but also the minimally invasive nature of arthroscopy provides many of the intraoperative and postoperative advantage~ seenin other joints. On the other hand, arthroscopy of the shoulder is more technically complex. and in adult horses it can be a particular challenge.

Surgical Anatomy the Shoulder

of

The shoulder is a relatively tightly articulated diarthrodial joint. and consists of the rounded articular surface of the humeral head and the depressed concavity of the glenoid

surface of the scapula. Collateral and stabilizing support for the shoulder is derived from periarticular tendons and ligaments. Lateral support is provided by the supraspinatus and infraspinatus tendons of insertion, while medial support is formed by the subscapularis tendon of insertion and a plical fold, referred to as the medial glenohumeral ligament.

The primary cranial stabilizer is the biceps tendon of origin.

Similarly, caudal support is derived from the tendons of origin of the teres minor and deltoideus muscles. Access for the arthroscope and instrument entry is limited to the lateral aspects by the close association of the scapula with the thorax. Finally, the accessible portions of the shoulder are functionally divided into cranial and caudal regions by the infraspinatus tendon of insertion.

Insertion of the arthroscope The horse is positioned in lateral recumbency. with the affected limb uppermost and unsupported in a slightly adducted position. The leg is draped so that traction can be applied to the limb during surgery. After aseptic preparation and draping of a wide sterile field. the appropriate landmark for insertion of a spinal needle immediately cranial to the infraspinatus tendon and proximal to the notch dividing the greater tubercle of the humerus into cranial and caudal components is identified (Fig. 8.1). An 18-gauge. 3-inch spinal needle is inserted at this location at an angle approximately 250 caudal and distal to penetrate the shoulder joint cranial cul-de-sac (Fig. 8.2). The needle is advanced until the tip contacts articular cartilage. and about 60 ml of a balanced electrolyte solution are then injected to distend the joint (Fig. 8.3).

The spinal needle is removed. and when the craniolateral approach to the shoulder is selected. a 5-mm vertical skin incision is made in the same location (if it is not made before placement of the spinal needle). For the lateral approach. the skin incision for the arthroscope portal is made 1 cm caudal to the palpable caudal border of the infraspinatus tendon.

The arthroscopecannula and conical obturator are then inserted through the joint capsulein the samedirection as the I8-gauge spinal needleunder the infraspinatustendon toward the caudal aspectof the joint (Fig. 8.4). Entry into the joint is confirmed by removing the obturator and observinga flow of fluid from the cannula.The arthroscope is then placed within the cannula. and the diagnostic arthroscopic evaluation can commencefrom this position (Fig.8.5).

Normal

arthroscopic

anatomy

Systematic examination of the joint begins with the tip of the arthroscope in the caudal aspect of the joint. In this position, the caudal humeral head (ventrally), glenoid (medially), and synovial membrane (laterally) can be visualized (Fig. 8.6).

The arthroscope and cannula are then withdrawn along the lateral aspect of the joint to allow visualization of the lateral rim of the glenoid medially, the humeral head ventrally, and the synovial surface of the infraspinatus tendon laterally. The synovial membrane adjacent to the infraspinatus tendon is arranged in longitudinal bands and is relatively devoid of villi (Fig. 8.7). At this stage, elevation of the limb to a position

to the floor (as opposedto the adductedposition) the joint capsule on the humeral head. and the lateral 8.8). Returning the humeral head.The tip of the arthroscopeis , the synovial membrane underlying the biceps tendon, and the cranial aspect of the humerus (Fig. 8.9).

With the joint maximally distendedso the glenoid and humeral head are separated,the tip of the arthroscope is inserted over the humeral head and under the glenoid toward the medial side of the joint. The articular surface of the glenoid and/or caudomedial humeral head can be closelyexamined by rotating the viewing angle of the scope 180째. Traction on the limb at this stage also facilitates the procedure. The medial aspect of the glenoid and humeral head are inspected as well as the medial surface of the synovial membrane, which contains a normal plica, devoid of villi, which has beenreferred to as the medial glenohumeral ligament, despite the fact it is not truly

a ligament (Fig.8.10). In mature horses,complete examination of the medial and caudomedial aspects of the shoulder joint become more difficult. Additional traction can aid exposure, but accesscan be limited unless erosion and malformation of the humeral head are extensive.

Lateral arthroscopic

approach

An alternative approach for arthroscopic examination of the shoulder joint uses a direct lateral approach (Nixon 1987). In this approach, the arthroscope penetrates the joint 1-2 cm

caudal to the infraspinatus tendon, entering betweenthe infraspinatus and teres minor muscles (Fig. 8.11). This approach allows examination of the cranial, lateral, and caudal portions of the humeral head and the glenoid cavity, and portions of the medial aspectdepending on the age of the horse and extent of disease.In most situations it also allows good visualization of the caudomedial aspect of the humeral head (Fig. 8.12), which can be difficult to examine using the craniolateral approach. Additionally, it also leavesthe portal cranial to the infraspinatus tendon available for the egresscannula. In adult horses the cranial portal can also provide access for the surgeon to insert a curved, blunt-tipped forceps across the non-articular portion of the shoulder joint to engage the glenoid notch and distract the humeral head from the glenoid by rotation of the forceps. This allows the arthroscope to be advanced safelyto the medial aspect of the joint (Fig 8.13). A third portal. 2-4 cm caudal to the arthroscope entry portal, is used as an instrument portal for arthroscopic surgery by triangulation. This method of internal distraction precludes the need for external traction; however. since it risks iatrogenic damage to the cranial aspect of the humeral head, it is generally used only in heavily muscled mature horses.

For surgical debridement of most OCD lesions, the younger age of the horse and the chronicity of the disease provide sufficient laxity that fluid distention and axial traction are adequate to allow accessto most regions of the articulation.

The primary indication for diagnostic arthroscopy of the shoulder joint is the evaluation and treatment of osteochondrosis section). Diagnostic arthroscopy is also indicated when lameness is localized to the shoulder by response to intra-articular anesthesia but when are equivocal. In such cases, fibrillation of the

dissecans.the arthroscopic findings do :with the radiographic changes. and the diagnostic examination is a critical part of the arthroscopic procedure. Arthro- l scopy is also appropriate in cases of septic arthritis. both for evaluating the articular cartilage and for treatment.

1 Using a probe during diagnostic arthroscopy of the shoulder joint is critical. An instrument portal is necessary for probe placement. and creation of this portal is describedin the next section. The optimal site to insert the probe is ascertained using an I8-gauge. 3-inch spinal needle.

In addition to defining intra-articular disease entities. arthroscopy has been used in human patients with shoulder

instability and in assessingcasesof supraspinatustendinitis (Cofield 1983), ruptured biceps tendon, and loose body removal Oohnson1986). Such indications have not been recognizedin the horse as yet; the horse does not have a glenoidlabrum.

Arthroscopic Surgery of the Shoulder joint for Treatment of Osteochondrosis As mentioned previously, non-surgical treatment of osteochondrosis in the equine shoulder has rarely allowed horses to regain athletic capability. Three different arthrotomy approaches have been used to treat cases of osteochondrosis in the equine shoulder. Complications of loss of lateral support (Schmidt et al197S), limited access(DeBowes et al 1982), and seroma formation (Nixon et al1984) have been seen, but probably of more importance is the fact that complete visualization of the articulation is not possible with an arthrotomy incision (Nixon et al1984). Extensive traction is also critical to the performance of the procedure.

Arthroscopy provides advantages over arthrotomy in both avoiding these complications as well as providing additional benefits through the minimally invasive approach. It should be stressed,however, that adequate arthroscopic visualization and surgical manipulation in the equine shoulder joint are more difficult than in other joints described previously in this text.

The material presented is based on the experience of the authors, both in evaluating the approaches in cadavers as well as involvement in 114 clinical cases,including a previously published series of cases of osteochondrosis with follow-up (Nixon 1986, Bertone & McIlwraith 1987a).

Preoperative considerations Most patients manifest clinical signs before 1 year of age.The age of presentation doesdepend somewhat on the observation skills of the owners. In some cases,a recent history of lameness may be described.Contracted conformation of the feetsignifies more accurately the duration of a problem. Preoperative clinical signs include lameness with a shortened cranial phase of stride. Some horses show resentment to firm digital pressure caudal to the infraspinatus tendon. Extension and flexion of the shoulder joint is also resented in some cases.

Intra-articular anesthesia of the shoulder joint improves or eliminates the lameness in most cases. However, when the articular cartilage over subchondral bone defectsis still intact, intra-articular local anesthesia may not generate a response.

Intra-articular anesthesia is performed by using the same landmark as previously described for placing the spinal needle during arthroscopy. The absence of these localizing clinical signs, however, does not rule out the presence of osteo-

chondrosis in the shoulder. In many instances, is evaluated after the elimination of problems in 1 limb with the use of nerve blocks.

The diagnosis of osteochondrosis is confirmed] graphically. Standing radiographs may be taken. and

are sometimes necessary to provide images of r quality to rule out the presence of any lesions in I Radiographic signs of osteochondritis dissecans in humeral head include malformation of the. flattening and/or undulation of the bone caudally,

caudal portion of the humeral head, particularly physeal junction, may be seen. Occasionally, ( . development is evident without other radiographic osteochondritis dissecans.

Radiographic abnormalities in the scapula that considered to relate to osteochondrosis j , of osteochondritis dissecans, osteochondral and abnormal flattening of , c .

8.16). In most instances, the glenoid cavity develops

border.More chronic shoulder OCDcaseshave

formation on the caudal aspect of the glenoid. In instances. however. r ." , articular

(

.-'-

1987a).

Arthrography of the shoulder' .a technique to diagnose OCD. but more importantly. to those that are eroded to the extent that they are salvage (Nixon & Spencer: ' -, -head and glenoid cavil, that one cartilage surf

prognosis,and can lead to surgery and generallya outlook(Fig.8.18).

Arthroscopic

technique

A thorough exploration of the scapulohumeral joint, previously described, is performed as the first step. r exploration involves probing all visible lesions as well entry for triangulation during arthroscopic surgery in shoulder, is illustrated in 1 .-. is selected to permit accessto the caudal humeral r central articular surface of the glenoid. To determine location. an I8-gauge spinal needle is inserted about ( caudal to the infraspinatus tendon and 4 cm distal (arthroscopic portal (Fig. 8.20). This location usually f

When the needle position is judged to be satisfactory, an 8 mm skin incision is made at that location. and a stab incision is continued into the muscle mass with the use of a No. 11 or 15 blade (Fig. 8.21). A conical obturator is inserted along the same path to ensure the presence of a workable portal. It is important that fluid pressure be at a minimum at this time. When the portal is unobstructed. intermuscular extravasation of fluid is minimal, although it usually becomes a problem later during surgery, regardless of the portal size.

The shoulder is one of the few sites where screw-in selfsealing cannulae are useful to prevent massive subcutaneous fluid accumulation. They limit the size of instrument entry, and so must be at least 7 mm internal diameter to be useful (described in Chapter 2). A blunt probe is initially passed through the instrument portal to evaluate the lesions in thejoint. to palpate the articular cartilage peripheral to the defects,and to explore the extent of the undermined cartilage in osteochondritis dissecanslesions as well as the openings of subchondral cystic lesions. The presence of all lesions and their degree is ascertained before any surgical manipulations are performed (Fig 8.22-8.31).

This caudolateral instrument portal is used for debriding most lesions. Laterally located defects are easier to operate than medially placed lesions. Therefore, procedures involving lesions on the medial side of the joint are performed first while maximal joint distention can be maintained. and separation of the glenoid and humeral head are achieved.

Adjunctive traction is also sometimes necessary at this stage

~

as well. Surgical intervention on laterally placed lesions is still possible later. when joint distention has decreased.

Humeral head defects (see Figs 8.23 and 8.24) are debrided initially with a hand curette or periosteal elevator; large pieces of cartilage are removed by using Ferris-Smith

rongeurs (Fig. 8.32). A motorized resector can be used for debriding large lesions. The resector works well in the debridement of easily accessiblehumeral head lesions. When the defect is deeper within the subchondral bone, however, the resector and/or burr may not reach, and a right-angled curette is used. Angled motorized resectors (see Chapter 2) can be very helpful to accommodate to the curvature of the humeral head. Similarly, small angled rongeurs (patellar

forceps) can be helpful to enter deep OCDlesions and retrieve cartilage flaps or debride subchondral bone (Fig. 8.34). At the completion of subchondral bone debridement, the edges of the defect are debrided with a hand curette and Ferris-Smith rongeurs. When intact articular cartilage overlies a subchondral defect(a common manifestation with osteochondritis dissecans in the shoulder), all cartilage superficial to the defect is removed and the defect beneath is debrided. Figures

8.30 and 8.31 depict defects on the humeral head after debridement.

Similarly, articular cartilage fissures,areas of erosion, cystlike lesions, and detached articular cartilage in the glenoid (Figs. 8.25-8.29) are debrided and removed by using FerrisSmith disk rongeurs, patellar forceps, curettes (both straight and angled) and occasionally the motorized resector or burr.

The concave shape of the glenoid sometimes makes accessibility with the straight resector blade difficult. An angled resector and the right-angled curette are particularly useful for debriding extensive lesions and deep lesions.

Osteochondral fragments are rare in the shoulder.

In some cases,an additional cranial incision or exchange of the arthroscope and instrument portals is needed to gain instrument accessto the cranial aspect of the joint (Figs 8.35 and 8.36). Alternatively, using the lateral arthroscope entry technique, the arthroscope remains caudal to the infraspinatus tendon, leaving the existing portal cranial to the infraspinatus tendon free for rongeurs or curettes, which replace any egress cannula that have been placed during the initial phase of surgery. Instrument entry through the cranial portal allows removal of free osteochondral fragments from the cranial cul-de-sac of the joint or access to lesions of the humeral head that extend more cranial than normal (Fig. 8.37).

At the completion of the procedure, the joint is lavaged by using a large-bore (4.5 mm) egress cannula through the instrument portal (Fig. 8.33). Suction is usually applied at some stage to ensure removal of debris. As discussed in

a focal subchondralcystic lesionmay alsobe noted. the cyst(Fig.8.25).

Postoperative management Antibiotics are administered perioperatively and for 2 days i postoperatively.Phenylbutazone is administered on the day of j the operation and for the successive 3-5 days. Horses are confined to a stall for 10 days, at which time hand walking commences. We usually start with hand walking for 5 minutes per day, with incremental increases of 5 minutes each week to 30 minutes per day. Horses are then turned out for periods of 4-12 months before forced exercisebegins.

Problems and complications and surgical manipulation are more difficult in tJ shoulder joint than in most other joints in which arti surgery is commonly performed. A definite J '

most people experience one or more of the difficultiesand complications.

Arthroscopic placement in the joint

Chapter 3. the use of a motorized pump is important in casesinvolving Difficulty can be experienced with this step. Accurate t extensive lesions. With an open large bore egress placement of the spinal needle. predistention of the joint. and cannula in position fluid flow is usually set at maximal to practice alleviate this problem. lavage the joint effectively.

As recorded previously (Bertone & McIlwraith 198 7a). the lesions found at arthroscopy are usually more extensive than Difficulty in establishing triangulation they appeared radiographically. In most instances. the Visualizing the spinal needle is dillicult in certain cases due to cartilaginous changes extend beyond the limits of the subthe depths of the joint from the skin surface, but the severity chondral bone abnormalities observed on the radiographs. of this problem decreases with surgical practice. Changes in particularly in the glenoid of the scapula. In some horses in limb position and difference in the size of the patient can which radiographically the lesion appears limited to the confuse the operator.

For most instances in which access to glenoid or humeral head, additional lesions are found the joint was not achieved initially, the needle was placed too arthroscopically on the opposing articular surface. The most cranial and/or too proximal.

Maintaining the limb in an common arthroscopic abnormalities of the humeral head are unsupported, adducted (resting) position facilitates joint cartilage discoloration with undermining and erosion down entry by widening the lateral aspect of the joint. to subchondral bone on the caudal aspect of the articular surface (see Figs 8.23 and 8.24). In some instances. a lesion is not visible initially and probing is required to ascertain the Extravasation of fluids area of undermined cartilage. The most common arthroscopic Extravasation occurs in all shoulder arthroscopy cases to abnormality in the glenoid is cracked undermined articular some degree. During surgery the amount of fluid in the pericartilage with fissure formation and fibrillation (see articlar tissue increases. causing increased extra-articular Figs 8.25-8.29). An additional common finding is friable, pressure. This increase in turn produces technical difficulty, defective subchondral bone. and these lesions may extend such as collapse of the joint space and decreased ability to see quite deeply. In most horses. the center of the glenoid cavity and manipulate instruments.

An efficient surgical procedure is most severelyaffected. Occasionally.however,lesions extend is critical in operations involving the shoulder.

A clear. laterally to the glenoid rim, and the bone of the glenoid rim unobstructed instrument portal. careful control of fluid may also be fragmented (see Fig. 8.29). In other instances, ingress and judicious use of self-sealing cannulae also the medial portion of the glenoid is affected. Although a improve surgical procedures in this region. diffuse osteochondritis dissecans lesion is the most common

Difficulty in reaching potential lesions

horses were completely sound at a jog within 4 months. Five horses were atWetically sound and were being shown, ridden, In some instances. the surgeon may visualize lesions and not or raced after 5-20 months. A sixth horse was sound when be able to reach them with the instruments. Theselesions are beginning race training. A seventh horse was pasture sound usually located on the caudomedial surface of the humeral and was to begin race training at the time of the report. An head of adult horses and become even more difficult to access eighth horse showed well in halter for 12 months, but in well-muscled patients. In one series (Bertone & McIlwraith shoulder lameness returned. This horse was donated, and a 1987a), the problem of inadequate instrument length was necropsy was performed. The ninth and tenth horses were encountered in three horses. Debridement of these areas can not completely sound at 11 months. The eleventh horse be performed in young horses without difficulty, where traction improved but remained lame and could not be used for on the limb opens the joint space and facilitates curettage of athletic performance. the medial surfaces. However, the ideal instrument for Follow-up radiographic assessmentrevealed improvement reaching medial lesions in larger horses has not been found. in contour of the humeral head and joint space and more Long rongeurs are rare, and instruments with somecurvature even density of the humeral epiphysis and the glenoid of the are also difficult to find. It is important to advise owners that scapula in 6 horses. One of these horses showed marked complete debridement may not be achieved when the horse improvement in subchondral bone density and surface weighs 500 kg or more. Large accumulations of subcutaneous contour of the glenoid cavity. In 2 of the remaining 5 horses, fluid also contribute to inadequate instrument length, and the caudal border of the glenoid cavity had remodeled to periodic application of pressure massageto drive fluid out the appear more like the contralateral joint. In the fourth of the skin portals often improves access to remote regions of the 6 horses, radiographs obtained 1 year later showed a subhumeral head. chondral cystic lesion in the scapula (1.5 cm in diameter) that had not been present previously (Fig. 8.38). However, this horse was athletically sound. The contour of the glenoid Damage to instruments articular surface and its caudal border was smoother postThe instrument portal passes through 6-8 cm of muscle operatively and the subchondral osteosclerosiswas reduced before entry into the joint. Manipulation of the instruments in thickness. In the fifth horse in this group, an osteophyte on is restricted by this muscle mass. The instrument portal can the humeral head had enlarged, but improvement was noted be enlarged, but. in certain instances, the probe or trocar has in joint contour of both the humeral head and glenoid cavity been bent when removed.

(Fig. 8.39). Radiographs obtained from one of the two horses One possible solution to the difficulty sometimes experithat improved but were still lame showed no improvement in enced in maintaining separation of the glenoid and humeral the glenoid lesion radiographically. In the horse where head (this distance becomes critical when fluid extravasation euthanasia was chosen when it deteriorated clinically, the inhibits distention) is placing the patient in dorsal recumbency.By humeral epiphysis was severelydistorted with a defect in the suspending the leg and lowering the table slightly, "gravity articular surface contour, a subchondral cystic lesion, and a traction" may provide a less energy-consuming alternative. small intra-articular fracture of the cranial margin of the The authors have not tried this technique. The possibility of glenoid cavity. damaging the brachial plexus is one potential hazard.

In summary, all 11 horses improved clinically. Soundness Transient paresthesia in the upper extremities after shoulder was achieved in 9 horses, and 5 of 11 horses have been used arthroscopy involving traction was reported in man, andbrachial athletically. Two horses did not become sound. One of these plexus strain versus joint accessibility with different horses was young but had extensive lesions of the glenoid shoulder positions has been described (Klein et al19 8 7). cavity and humeral head; a large osteophyte also developed.

The other horse was 4 years of age at the time of surgical intervention and did show some clinical but no radiographic Results improvement. One horse developed severe degenerative changes in the joint after being sound for 8 months. It seems The initial series of 11 horses reported by the authors that considerable healing response can be obtained if surgical included one postoperativecomplication (Bertone & Mcllwraith treatment occurs in a timely fashion.

1987a): a subcutaneous infection with Actinobacillus sp.

Hand curettage was satisfactory for treating most lesions, produced swelling and drainage from the incision 48 hours but the motorized resectors and burr provided the most after surgery. The incision and subcutaneous tissues were efficient debridement of articular cartilage and subchondral opened. flushed. and allowed to heal by second intention. bone in both the scapula and humerus, and it avoided the Moderate swelling in the shoulder region in all horses. potential difficulties associated with hand curettage. resulting from leakage of lavage fluid subcutaneously and Osteochondrotic lesions of the humeral head were the easiest intramuscularly. generally resolved within 7 days. to debride, especially in horses that were yearlings or None of the horses were more lame postoperatively. and all younger, because they had less muscle mass as well as more improved clinically from within 2 weeks of the operation flexible periarticular structures. However, the lesions were until the time of follow-up evaluation. Nine of the 11 horses accessibleeven in older horses when the joint was distracted. achieved soundness and 8 horses remained sound. Seven Traction is extremely important for access to extensive

scapular lesions, but arthroscopic surgery in the treatment of these lesions is recommended only for surgeons with considerable experience with this technique.

Euthanasia was chosen for four horses in this study. On the basis of ideas concerning postoperative healing gained from these four cases,it appeared that lesions of the humeral head healed with successivelayers of hyaline cartilage, fibrocartilage, and fibrous tissue. Whether the hyaline cartilage represented remnants from surgery or transformation of fibrocartilage to hyaline cartilage is unclear. The quality of the repaired tissue varied. From necropsy findings in three cases in which glenoid lesions were debrided, it seemedthese lesions did not heal as well as similar lesions of the humeral head. The defects were filled with mixtures of fibrous tissue and fibrocartilage.

In addition, cystic lesions in the bone also developed.

The development of cystic lesions in the subchondral bone of the glenoid subsequent to surgery is an interesting finding.

This may be a sequel to untreated osteochondritis dissecans or to debridement in which the articular cartilage is removed down to subchondral bone. Subchondral bone cystic lesions can form in normal joints if full-thickness articular cartilage defects are created surgically in weightbearing areas (Kold et al1986). These lesions can develop within 6 months, and some authors state that intra-articular synovial fluid pressure may exceed subchondral bone pressure in weight-

bearing areas, contributing to expansion of i in the bone (Landells 1953).

The radiographic evidence of remodeling of the cavity and humeral head in six horses less than 1 ~ may help explain the clinical improvement in severe

Since this published series. the authors have and humeral head and have achieved considerable improvement. ] , .

to avoid operating on these types of lesions usually high detail preoperative radiographs or even [ .'

Additionally. older horses may have a poor prognosis because of osteochondritis dissecans. In each instance. thehorse cartilage remodeling decreaseswith advancing age. was involved in athletic activity when the problemdevelop A more recent survey of 70 cases of one author (C.W.M.)reveals The lesions manifested arthroscopic ally as areas of an overall successrate for return to athletic activity fibrillation and were treated with debridement. of 45%.

Articular

Arthroscopic Surgery for Other Clinical Entities in the Shoulder Osteoarthritis The authors have been involved in sevencasesin which the horse was considered to have degenerative articular cartilage lesions of the humeral head that differed from the typical

cases Some Foals Bertone References

fracture

fractures of the glenoid and portions of the perimeter ofthe humeral head can lead to severe lameness, and requireremoval of fragments to improve the outcome. Fragmentation of the cranial or caudal glenoid rim can be removed arthroscopically, while larger fractures generally require compression by lag screw insertion. Extensive craniocaudallyoriented fractures of the glenoid cavity, which extend proximally to involve the neck of the scapula, may require both arthroscopic debridement and small fragment removal, and then screw compression. These types of fracture can appear normal in lateromedial radiographs, largely because of the minimal craniocaudal displacement of the fracture.

Septic arthritis/osteomyelitis

and weanlings are predisposed to septic physitis andosteomy which can seeda joint and necessitate furtherdebridem Routine arthroscopy of the shoulder for fibrinectomy and removal of inspissated debris is required for resolution in advanced cases.Lateral or cranial arthroscopic approaches provide visualization of the joint surfaces sufficient to allow debridement of synovial membrane andcartilage The large caudal and cranial cul-de-sacs need particularly aggressivelavage and manual fibrin removal toreduce the bacterial load. Debridement of deeper lesionsinvolving cartilage and subchondral bone may occasionallybe necessary (Fig. 8.40). Placing ingress drains for antibiotic delivery can also improve the outcome. Additional detail isprovided in Chapter 14.

AL. McIlwraith CWoArthroscopic surgery for the treatment of osteochondrosis in the equine shoulder joint. Vet Surg 1987 a; 16(4): 303-311.Bertone AL. McIlwraith CWoArthroscopic surgical approaches and intraarticular anatomy of the equine shoulder joint. Vet Surg 1987b; 16: 312-317.

Cofield RH. Arthroscopy of the shoulder. Mayo Clin Proc 1983; 58: 501-508.DeBowes RM. Wagner PC. Grant BD. Surgical approach to the equine scapulohumeral joint through a longitudinal infraspinatus tenotomy. Vet Surg 1982; 11: 125-128.

Johnson u,. Arthroscopic surgery principles and practice. 3rd edn.

St. Louis: Mosby; 1986.

Klein AH. France JC. MutscWer TA. Fu FH. Measurement of brachial plexus strain in arthroscopy of the shoulder. Arthroscopy 1987; 3: 45-52.Kold SE. Hickman J. Melsen F. An experimental study of the healing process of equine chondral and osteochondral defects.Equine Vet J 1986; 18: 18-24.

Landells JW. The bone cysts of osteoarthritis. J Bone Joint Surg Br 1953; 35-B: 643-649.

Mason TA. Maclean AA. Osteochondrosis dissecans of the head of the humerus in two foals. Equine Vet J 1977; 9(4): 189-191.

Meagher DM. Pool RR. O'Brien TR. Osteochondritis of the shoulder joint in the horse. Proc Am AssocEquine Prac 1975; 19: 247-256.

Nixon AJ. Diagnostic and operative arthroscopy of the equine shoulder joint. Vet Surg 1986; 15: 129.

Nixon AJ. Diagnostic and surgical arthroscopy of the equine shoulder joint. Vet Surg 1987; 16: 44-52.

Nixon AJ, Spencer CPoArthrography of the equine shoulder joint.

Equine VetJ 1990; 22(2): 107-113A.

Nixon AI. Stashak TS. et al. A muscleseparating ..., Vet Surg 1984; 13; 247-256.

Nyack B. Morgan JP. et al. Osteochondrosis of the shoulder the horse. Cornell Vet 1981; 71: 149-163. osteochondrosis in the horse. Proc 31st Annual Conv

1986.

Schmidt GR. Dueland R. Vaughan JT. .the equine shoulder joint. Vet Med/Small An Clin 1975; 542-547.

ER

~

diseases such as osteochondral fragmentation, , or traumatically induced cartilage frequency to warrant techniques for arthrosurgery of the various pouches of the elbow joint. 'humeral condyle or

a seconddescribingsevenhorses (Hopenet al 1992).

Other lesions. including osteochondritis dissecans .the humeral condyles. may be more appropriately by surgical debridement. Arthroscopic techniques access to the cranial portions of the humeral

.both condyles and to the anconeal the ulna using a caudoproximal approach via the complexity of periarticular neurovascular structures inherent risks of elbow arthroscopy are well known in (Lynch et al1986, Thomas et al1987, Baker & Jones 1999). and have also been described to a limited extent in the horse (Nixon 1990). Overall, arthroscopic accessto the cranial regions of the elbow in man and horses is relatively simple. while the caudal compartments are more challenging, with increased risk to adjacent neurovascular structures (Nixon 1990. Poehling & Ekman 1994. Baker & Jones1999).

The elbow joint of the horse is a complex articulation of the humerus. radius, and ulna. All three bones are intimately connected by substantial collateral ligaments. As a result. distraction of the humeroradial articulation and humeroulnar articulation results in little separation of the articular surfaces and therefore limited accessto regions predisposed to disease.particularly the proximal surface of the radius. For

the humeral condyles,this can be overcome to some extent by the large range of motion of the elbow, allowing articular surfaces to be exposed by flexion or extension. The tight articulation essentially divides the elbow to a cranial joint pouch, a limited caudal joint pouch, and a large proximocaudal joint pouch surrounding the anconeal process.

Approaches to the cranial portion of the elbow joint place small terminal branches of the radial nerve at risk as they arborize and terminate in the antebrachial extensor muscle bellies. The arthroscope entry avoids these branches; however, instrument accesscranially, through the muscle bellies, may impact on several small branches of the radial nerve. No clinical repercussions,including extensor muscle dysfunction, have been recognized. The caudomedial approach to the elbow joint penetrates between the muscle bellies of the flexor carpi radialis and flexor carpi ulnaris, and inadvertent entry caudal to the flexor carpi ulnaris places the arthroscope close to the ulnar nerve coursing over the caudomedial aspect of the humerus and continuing down the medial aspect of the ulna. Similarly, inadvertent entry to the elbow joint cranial to the flexor carpi radialis muscle belly places the median nerve at risk. During the caudomedial approach to the elbow, the instrument entry often penetrates through the flexor carpi ulnaris muscle belly, but also without repercussion. The caudal extremity of this approach also may impact on portions of the ulnar nerve. The approach to the olecranon pouch of the elbow penetrates the distal terminal portions of the triceps musculature or tendon of insertion; however, no significant neurovascular structures are at risk using this

approach.

Positioning Positioning for arthroscopy of the elbow is dictated by the site of surgical disease. Only dorsal recumbency will allow simultaneous accessto all three pouches of the elbow joint.

However, this can increase the degree of difficulty in

arthroscopic accessto the caudoproximal olecranon pouch.

For accessto specific diseaseconditions involving the cranial, caudal, or caudoproximal region of the elbow, lateral recumbency is preferred. The cranial pouch and the caudoproximal pouch of the elbow can be accessed with the affected limb uppermost, while access to the caudomedial pouch requires the affected limb to be placed down on the surgery table. Repositioning the horse from affected limb down to affected limb uppermost during the surgical procedure is another possibility, although this delays the surgical process.is manpower demanding, and risks breaks in sterile procedures.

Craniolateral

approach to the elbow

The horseis positionedin lateralrecumbencysothe limb can be manipulatedinto extensionand flexion of the elbowjoint.

After preparationand draping,the elbowjoint is distended throughthe cranialpouchwith 40-60 mlof lactatedRinger's solution.The cranial perimeterof the humeroradialarticulation is palpatedcranialto the lateral collateralligamentand a 5-mm stabincisionmade approximately2-3 cm cranialto this palpablecollateral ligamentborder.The musclebelly of the common digital extensorforms a cranial limit to the triangular target area for accessof the arthroscope.If the entry is made too close to the cranial palpable border of the lateral humeralcondyle.manipulationwithin the cranial pouch of the elbowbecomesmore difficult. The arthroscope sleeveis inserted across the cranial pouch of the elbow joint, and the obturator exchangedfor the forward oblique viewing arthroscope(Fig.9.1). The cranialarticular surfaces and cranial joint pouch of the elbowcan then be examined (Fig. 9.2). The arthroscopeis insertedas deeplyas possible to examine the craniomedialmargins of the radius and humerus. A 700 arthroscopemay be usefulin this region; however,it is not essential.Withdrawal of the arthroscope identifies the medial followed by the lateral condyles of the humerus, with a large synovial fossa interposed betweenthe two (seeFig. 9.2). Further withdrawal of the arthroscoperevealsthe lateral portion of the humeroradial articulation and the lateral collateral ligament. The cranial joint pouch of the elbow is voluminous and easily examined.

An instrument portal can be made cranial to the arthroscopeentry, afterplacing a 7.5 cm x 18-gaugespinal needle.This portal usually penetratesbetweenthe antebrachial extensormusclebellies,generallywhere a shallow division can be palpatedbetweenthe extensorcarpi radialis and commondigital extensormuscles.The midcranialregion should be avoided to minimize potential damage to the transversecubital artery. For lesionsinvolving the craniolateral extremityof the radius or lateralhumeralcondyle.the arthroscopeand instrument entry portal can be exchanged to provide instrument accessto the lateral portions of the articular perimeter.Following completionof the procedure. fluid is expressedfrom the joint and the skin incisionsclosed with interrupted sutures.

Fig. 9.1 Arthroscopic technique for access to the cranial pouch of the elbow joint. Arthroscope entry is made in the triangle formed by the craniolateral curvature of the lateral condyle of the humerus, the proximal perimeter of the craniolateral surface of the radius, and the caudal border of the muscle belly of the common digital extensor tendon. Instrument entry can be made between the muscle bellies of the common digital extensor and extensor carpi radialis muscles.

Caudomedial approach to the elbow joint

Dorsal positioning can be used if accessto ! joint pouches is expected, as previously described. preparation and draping, the site for arthroscope identified by systematically palpating from cranial! to identify the medial collateral ligament, the r

the approximation of flexor carpi radialis and flexor I ulnaris muscle bellies. A needle is inserted to identify humeroradial articulation, articular level and between the muscle bellies of the icarpi radialis and flexor carpi ulnaris is identified. palpable division between these muscle bellies is i more easily at the mid-radius level, and the tracked proximally to the point 2-3 cm distal to the the humeroradial articulation. The palpable'

overlying superficial pectoral muscles and

fascia. Insertion of the arthroscope proximal to the level of

the humeroradial articulation places the ulnar neurovascular structures at risk. particularly if a second entry for instruments is then made caudal to the flexor carpi ulnaris muscle belly.

Mter insertion of the needle to the caudomedial aspect of the joint. the elbow is distended with 60 ml of lactated Ringer's solution and a 5 mm skin incision made for entry of the

arthroscopesleeveand obturator(Fig.9.3). The arthroscope sleevewith obturator in placeis advancedproximally in an oblique direction to enter the caudomedialaspect of the elbowjoint pouch. Whencartilage or bone are encountered and joint fluid is returned through the egressoutlets on the arthroscope sleeve,the conical obturator is replaced by the arthroscope.In many instancesthe arthroscopesleeve can be insertedto its limit. as it penetratesinto the caudal

limb is made easier by positioning the horse in lateral rather than dorsal recumbency. Manipulating the tip of the arthroscope caudally. exposesthe trochlear notch of the ulna and the apposing articular surface of the humeral condyles (Fig. 9.4). Further caudally, the intrusion of the medial epicondyle of the humerus. and the proximal regions of the trochlear notch of the ulna are evident (Fig. 9.4). The large tendon of origin of the humeral head of the deep digital flexor tendon is also visible. The space between the trochlear notch of the ulna and this mobile tendon provides accessto the caudoproximal cul-de-sac of the elbow. However. for ease of surgical manipulation, the caudoproximal approach to this cul-de-sac using a lateral accesstechnique is recommended (describedlater).

Instrument entry portals are made through the muscle belly of the flexor carpi ulnaris. caudal to the arthroscope portal. The most suitable path for instrument entry is selected after inserting a 7.5 cm long spinal needle. This provides ready accessto the medial condyle and the medial aspectsof the lateral condyle. The central regions of the capitular fovea of the radius cannot be accessedsurgically.

Caudoproximal elbow Joint

approach to the

The voluminous caudoproximal pouch of the elbow joint can be accessedusing approaches similar to those described for arthrocentesis of the elbow (Stashak 1987). This approach is best done with the horse in lateral recumbency with the limb free to be manipulated through flexion and extension. The joint is distended with 60-80 ml of lactated Ringer's solution using a 7.5 cm spinal needleinserted overthe lateral epicondyle to enter the lateral portion of the caudoproximal cul-de-sac of the joint. Needle entry is approximately level with the point of the elbow,and caudal to the palpable lateral epicondyle of the humerus. The spinal needle is angled distally and cranially to target the anconeal process of the ulna. Following removal of the needle,the skin incision for arthroscope entry is made in a similar location and the arthroscope sleeve and conical obturator inserted, angling distally and cranially to contact the articular surface of the anconeal process (Fig. 9.5). The cul-de-sac of the elbow and farther into the caudoproximal obturator is then exchanged for the arthroscope. allowing cul-de-sac surrounding the anconeal process. A standard examination of the voluminous caudoproximal joint pouch forward oblique arthroscope is inserted and the caudal (Fig. 9.6). The anconeal processand proximal portions of the regions of the elbow examined. The medial humeral condyle humeral condyles are readily visible (Fig. 9.6). Flexion of the is readily visible (Fig. 9.4). The caudal perimeter of the elbow exposes the entire caudal one-half of the humeral humeroradial articulation is a convenient landmark to condyles for surgical procedures. Instrument entry for commence examination of the joint (Fig. 9.4). The articular access to lesions is then made by preplacing a 7.5 cm surfaces of the humeral condyles, particularly the medial spinal needle to give direct accessto lesions on the anconeal condyle. are readily evaluated. Flexion of the elbow improves process or humeral condyles. This entry usually perforates the exposure of the caudal portions of the humeral condyles. terminal portions of the triceps musculature and occasionPortions of the weightbeai"ing articular surface of the radius can be seen. but the arthroscope cannot be advanced ally the tendon of insertion on the olecranon. Hand instruments and motorized burrs can be inserted for surgical between the radius and humerus (Fig. 9.4). Distraction of the debridement. medial aspect of the humeroradial joint by abduction of the

of

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radius

therapy is

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ence

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,

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to the

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athletic appropriate'work.

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condyle with

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Pill et al2003), although the results of surgical treatment.

portion

The craniolateral portion of the distal humerus,particularly the lateral portion of the humeral condyle,is exposedto external impact injury, which can dislodgeintra-articular osteochondralfragments(Fig. 9.7). Removalof thesefragmentsis generallysimpleusing the craniolateralarthroscopic access.After examination of the remainder of the cranial aspectsof the elbow joint, the arthroscopeand instrument portals are reversed,placing the arthroscopethrough an instrument portal approximatelybetweenthe musclebellies of the extensorcarpi radialis and commondigital extensor.

This leavesthe more lateral portal for rongeur entry for fracture removal. Debridementof the subchondralbed is routine and debriscanbe flushedfrom the joint with a large egresscannula. The extentof articular involvementusually definesthe expectedoutcome,although the predisposed area for impactfracture is generally2-4 cm in length.

Fragmentation

of the anconeal

The anconeal process can develop fragmentation manifestation of osteochondrosis, f process using the caudoproximal approach is simple (Fig. 9.11). Fragment removal can be r using triangulation i ' ',- ; fragments are rare in this location, and many of fragments should be considered trauma-induced. : complex fractures of the I ' fixation. The open lateral approach to the anconeal during plate application to the olecranon f simple, and arthroscopy can be utilized to i the free fragment either during the plating (Fig. 9.11) or at a later time.

Septic arthritis Osteochondrosis and osteochondritis dissecans of the elbow Osteochondrosis of the elbow usually takes the form of either OCD flap lesions of the humeral condyles or subchondral cystic lesions of the proximal radius. To date, there are no arthroscopic techniques that will provide accessto the head

the

condyle.

simpler, safer, and provides more extensive room manipulate surgical instruments. Similar controversy: rounds treatment of elbow OCDin ] ,--

Fractures of the craniolateral of the humerus

the

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92).

similar

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et al19

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,

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et al1986).

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involved in hematogenous septic processes in foals. lateral aspect of the joint also has minimal: r . and is a common site for kicks from other animals' frequently penetrate the joint through or adjacent to lateral collateral ligament. Lavage and flushing of

compartments of the elbow joint represents minimal therapy for septic arthritis (see Chapter 14). Recalcitrant casesneed arthroscopic exploration, using debridement of inspissated and fibrinous material, and partial synovectomy of proliferative regions. Arthroscopic exploration also allows evaluation of the cartilage surfaces of the humerus and ulna, and debridement of any areas that have developed separation from the subchondral bone. The accessto the cranial pouch of the elbow joint is relatively simple using the craniolateral approach and, similarly, accessto the proximal caudal joint pouch can be provided using the caudoproximal approach.

Both can be accomplished with the patient in lateral recumbency. The necessity to enter the smaller joint pouch associated with the caudomedial arthroscopic approach is questionable. Most areas of the joint can be adequatelylavaged and inspissated material removed from the more voluminous cranial and caudoproximal pouches. Drains can be instilled or antibiotic repository devices placed in either or both of the cranial or caudoproximal pouches. The outcome for synovial sepsisis described in Chapter 14, and is generally dictated by the extent of osteomyelitis in the subchondral bone.

Arthroscopy

for osteoarthritis

Arthroscopic exploration and debridement of areas of cartilage degeneration in osteoarthritis is occasionally warranted. depending on the extent of osteophytosis in the elbow. The

prominent regions for osteophyte formation include cranial aspect of 1

lavage and chondroplasty for arthritis are questionable review in Chapter 17); ] matic relief may be provided for severalyears.

Despite the complexity of the elbow articulation and proximity to important neurovascular structures. ( complication during arthroscopic procedures around 1 elbow is subcutaneous fluid accumulation, which can extensive using the approaches described. Distention I visualization should be used in moderation, '

easilyexaminedwith moderatedistention.

Necropsy examination of horses used in the development of arthroscopic approaches to the elbow showed minor areas of muscle hemorrhage associatedwith instrument entry during triangulation (Nixon 1990). The primary concern in elbow arthroscopy is surgical planning to provide accessto the lesions without the necessity for repositioning the horse. The use of dorsal recumbency can result in difficulty in orientation and manipulation. but should be taken into consideration when all three compartments of the joint need to be examined.

References Baker CL Jr. Jones GL. Arthroscopy of the elbow. Am J Sports Med 1999; 27: 251-264.

Bertone AL. Mcllwraith CWoPowers BE et al. Subchondral osseous cystic lesions of the elbow of horses: conservative versus surgical treatment. J Am Vet Med Assoc 1986; 189: 540-546.

Hardy J. Marcoux M. Eisenberg H. Osteochondrosis-like lesion of the anconeal process in two horses. J AmVet Med Assoc 1986; 189:

802-803.

Hopen LA, Colahan PT,Turner TA, Nixon AJ. Nonsurgical treatment of cubital subchondral cyst-like lesions in horses: seven cases (1983-1987). J Am VetMed Assoc 1992; 200: 527-530.

Krijnen MR, Lim L, Willems WI. Arthroscopic treatment of osteochondritis dissecans of the capitellum: report of 5 female athletes. Arthroscopy 2003; 19: 210-214.

Lynch GJ, Meyers JF, Whipple TL, Caspari RB. Neurovascular anatomy and elbow arthroscopy: inherent risks. Arthroscopy 1986; 2: 190-197.

Nixon AJ. Arthroscopic approaches and intraarticular anatomy of the equine elbow. Vet Surg 1990; 19: 93-101.

Pill SG, Ganley TJ, Flynn IM, Gregg JR. Osteochondritis dissecansof the capitellum: arthroscopic-assisted treatment of large, fullthickness defects in young patients. Arthroscopy 2003; 19: 222-225.

Poehling GG,Ekman EF.Arthroscopy of the elbow. J Bone Joint Surg 1994; 76A: 1265-1271.

Stashak TS. Diagnosis of lameness. In: Stashak TS (ed.), Adams' lameness in horses. Philadelphia: Lea and Febiger; 1987:

150-153.

Thomas MA, Fast A, Shapiro D. Radial nerve damage as a complication of elbow arthroscopy. Clin Orthop 1987: 130-131.

. ~

recognize, and the need for arthroscopic evaluation diagnostic arthroscopy and surgical correction of problems in the hip are rare. They may be in part due to the inherent of isolating problems to the coxofemoral joint, horses with chronic lameness. Moreover, the associated with surgical therapy often diminish for arthroscopic exploration. However, an awareness of hip joint diseases and the use of imaging modalities such as nuclear scintigraphy and thermography, coupled with increased use of intra-articular anesthesia, have increased the likelihood of establishing a definitive lameness associated with the coxofemoral joint. A logical extension of improved diagnostic capabilities is the use of arthroscopic examination with a view to surgical correction of some diseases. Arthrotomy of the hip joint is difficult, results in limited exposure of relevant structures, is debilitating for the horse and surgeon, and is accompanied by high-wound healing complication rates: given this, it is rarely warranted for any surgical disease of the hip, other than separation of the proximal femoral capital physis. However, arthroscopy for diagnostic purposes is feasible, particularly in foals (Honnas et aI1993).

Diagnostic arthroscopy has been used to evaluate tearing of the ligament at the head of the femur (round ligament), osteoarthritis (qA) , fracture of the acetabulum, and osteochondrosis (DC) in the hip (Nixon 1994). In man, diagnostic arthroscopy of the hip is a useful technique to establish a diagnosis, as well as aid in treatment; it actually altered the preoperative diagnosis in 53% of 328 patients (Baber et al 1999). Given the preoperative use of computed tomography (CT) and magnetic resonance imaging (MRI) in man, these results represent a marked increase in diagnostic usefulness of arthroscopy. In foals, arthroscopic surgery is particularly valuable in the treatment of sepsisinvolving the coxofemoral joint, and in the treatment of osteochondrosis (Nixon 1994).

The clinical signs associated with clinical hip lameness in horses vary, depending on whether the derangement is a result of developmental disease in foals and weanlings, trauma to the hip resulting in tearing of the ligament of the head of the femur, degenerative osteoarthritis, or fracture of various portions of the acetabulum (Rose et al 1981, Miller & Todhunter 1987, Nixon et al1988). Under the best of circumstances, the diagnosis of hip disease is often protracted, leading to osteoarthritis as a common sequela.

When the lamenessis marked, muscle atrophy of the affected hind limb is evident in the gluteal and quadriceps musculature, facilitating an earlier diagnosis. More obscure upper hind limb lameness may take more diligence in the work-up. Diagnostic manipulative tests are useful; however, the definitive diagnosisoftenrequires intra-articular anesthesia.

Rectal examination is also recommended, although palpable enlargements have been recorded in only 50% of acetabular fractures (Rutkowski & Richardson 1989). and many other conditions including OCand OA are not detected using rectal

examination.

Nuclear scintigraphy has improved the diagnostic specificity for chronic hind limb lameness. but still lacks the conclusive nature of intra-articular anesthesia. Blocking the hip can be difficult until some familiarity with the surface anatomic landmarks is gained. Later confirmation and staging of the degree of the hip joint involvement can be provided by radiographs. Good-quality radiographs require general anesthesia.and ventrodorsal and oblique ventrodorsal views for evaluation of the acetabulum and femoral heads.

Moderate and severe degenerative osteoarthritis, osteochondrosis, osteochondritis dissecans (OCD),and luxation or subluxation of the hip are apparent on hip radiographs. Less obvious hip diseases,such as tearing of the ligament of the head of the femur and mild osteoarthritis, may not be evident on routine radiographs. These lesions may need to be identified through direct visualization during arthroscopic

examination.

to penetrate the joint of horses less than j

Arthroscopy is indicated for the diagnosis of hip joint disease, particularly in cases in which radiographs provide little additional information after a positive intra-articular anesthetic response has been obtained and as a therapeutic tool for other conditions. Arthroscopic examination of the hip joint in horses has been described in a limited case series (Honnas et al199 3, Nixon 1994). Arthroscopic visualization was useful in determining the extent of cartilage damage associated with fractures of the acetabular rim, in several cases where radiographically visible small fractures were identified associated with the periphery of the acetabular rim, in assessingthe degree of tearing of the ligament of the head of the femur, and in cases where cartilage defects were evident during examination of horses with hip joint lameness but no radiographic lesions (Nixon 1994). Intra-articular debridement of torn and partially torn ligaments of the head of the femur, debridement of OCD of the acetabulum, and cystic lesions of the femoral head have been described (Nixon 1994). Similarly, arthroscopic lavage and synovectomy with debris removal is a u~eful method for improving the response in foals with infectious arthritis of the hip.

Surgical technique Arthroscopic examination of the hip joint is readily accomplished in foals and can be performed with some difficulty in horses up to 500 kg. In larger horses, examination of the articular structures is less complete; the procedure is more technically demanding and is associated with more surgical trauma to the articular and periarticular structures than encountered during hip arthroscopy in foals.

However, hip joint laxity associated with persistent effusion provides a largely unrecognized advantage in adult horses with chronic hip disease. With appropriate axial traction on the affected hind limb. the femoral head can be distracted from the acetabulum sufficiently to allow examination of large portions of the femoral head and acetabulum.

The horse is anesthetized and positioned in lateral recumbency with the affected limb uppermost. The entire lateral region of the hip and gluteal muscle is draped for surgery with the affected limb supported but free to be mobilized during surgery. An arthroscope entry portal is made at the site that has been previously described for intraarticular anesthesia (Stashak 1987, Nixon 1994). A skin incision is made between the cranial and caudal portions of the greater trochanter, entering approximately 2 cm proximal to the palpable level of the trochanter (intertrochanteric fossa) (Fig. 10.1). This provides arthroscopic access to both the cranial and caudal recesses of the hip joint. The joint is initially distended with 60-80 ml of lactated Ringer's solution administered through a 15-20-cm spinal needle or th~ stvl~tt~ frQm a 15-cm intravenQUScatheter. The arthro-

arthroscope sleeve and 4-mm forward oblique viewing arthroscope (Fig. 10.2). However,a longer arthroscope (25-cm arthroscope, Karl Storz Endoscopy, Goleta, CA) is useful for more complete examination in adult horses (Fig. 10.3). The arthroscope sleeve and conical obturator are inserted through the skin and angled 200 ventral and 200 cranially,to follow the dorsal (proximal) contour of the femoral neck (Fig. 10.1). The lateral portion of the hip joint is penetrated, the obturator removed, and the arthroscope inserted. The standard 25 or 300 forward oblique viewing arthroscopes are satisfactory for examination of most regions of the hip joint. iJ A 700 arthroscope is useful but not essential to examine the 1 skin portal, for fluid egress and later instrument access,is made 4-5 cm cranial to the arthroscope portal. using a 1 5-cm spinal needle or catheter stylette to define the path for instrument entry prior to skin incision.

Visualization of the articular surface of the cranial, lateral, and caudal regions of the hip joint is accomplished with the limb supported in a horizontal position (Fig. 10.4).

Manipulation of the limb into a flexed and extended position allows other regions of the femoral head to be viewed. Given the depth of the joint from the skin surface. manipulation of the limb must be done with care, to avoid damage to the arthroscope. Distraction of the limb by axial tension is vital for a complete examination of the hip. This allows the arthroscope to be inserted between the femoral head and the acetabulum. In immature horses, distraction and arthroscope insertion can be accomplished easily and allow examination of the deeperregions of the joint (Fig. 10.5). In older horses, distraction and increased intra-articular fluid pressures are more important to allow visualization of the femoral head and round ligament of the head of the femur (Fig. 10.6). Joint distraction can be provided by axial tension on the limb from an assistant or by mechanical devices such as a winch attached to the surgery wall. The torso of the horse must be stabilized on the surgery table when distraction techniques are used. An intraoperative decision can be made as to the necessity and degree of mechanical distraction. The use of surgical assistants is necessary for arthroscopy of the hip joint in adults, primarily to manipulate the limb and to provide axial distraction when required.

Instrument access is generally provided through the cranial instrument portal after developing a path to the hip joint through the tendinous insertion of the middle gluteal muscle using a conical obturator. The arthroscope and instrument portals can be exchanged for better examination of the caudal acetabular rim. This allows entry for rongeurs and curettes through the original arthroscope portal. which can then be directed into the caudal regions of the joint. A long 6-mm diameter egress cannula (Sontec Instruments.

Englewood, CO)or a second arthroscope sleeveis suitable for fluid egress after surgical debridement. The use of motorized instruments is possible in small and moderate-sized horses, but use of motoriz~(J ~m1inm~nt ~f!n h~ limitp(J hv thp (Jpnth

1 j j j 1 j

generally have either focal or more widespread lesions associated with the femoral head and/or the ligament of the head of the femur when arthroscopic ally. Focal articular confined to the cranial aspect of the femoral head

from the cartilage lesion(Fig. 10.7). Removalof the instruments and motorized equipment need to be inserted to the limits of their length. Pressing in on the skin and gluteal musculature occasionally allows an extra 1-2 cm of effective length to be garnered from routine surgical instruments.

Long rongeurs and long egress cannulae are useful (Sontec Instruments). Most surgical triangulation techniques in the hip are difficult. Debridement of cartilage lesions of the femoral head and removal of free bodies and debris within the cranial and caudal recessesof the joint can be achieved with persistence. Lesions in the acetabulum can be more difficult to debride. In smaller horses, examination and debridement of torn portions of the round ligament of the head of the femur can be achieved. Osteochondrosis cysts of the head of the femur and fractures of the caudal acetabular rim are particularly difficult to adequately debride.

improved lameness in two racehorses.More osteophyte formation is often evident over caudal perimeter of the acetabulum (Fig. 10.8). moderate osteoarthritis, most of these osteophytes lesions of the femoral head can be accomplished appropriate manipulation of curettes and rongeurs combination with axial distraction. A moderate iatrogenic damage to surrounding cartilage is always possibility during debridement of these lesions advanced cases of hip joint osteoarthritis can arthroscopy (Fig. 10.9), however, lasting following debridement of fibrillated regions is rare.

Tearing of the ligament of the head of the femur Fraying and tearing of

of hip joints from small breed horses.but can also be

Femoral head cartilage lesions

of this ligament can occur, and the outlook even debridement is guarded (Fig. 10.10). Tearing in hreeds.

nHrtif'111Hrlv miniHt11re horses

f'Hn he Hdp,

in those cases with incomplete rupture of the ligament (Nixon 1994). Manipulation of biopsy punch rongeurs and motorized equipment is necessary for debridement of the visible portions of the accessory ligament of the head of 1 difficult to visualize. and lesions in this recognized.

Osteochondrosis dissecans

and

the lateral half of the femoral head. Lesions in the areas up to and including I insertion of the ligament of the head of the femur. deeper,more medial, aspects of l' , adequately visualized. extensive effusion, the hip joint is easily distracted. i ' better debridement of OCD lesions. Subchondral

the depths of the cyst can rarely be adequately debrided.

Secondary packing of the debrided cysts with cancellous bone or other graft materials has not been possible.Cartilage lesions associated with the caudal perimeter of the acetabulum may not necessarily represent OCD. but can be debrided with long rongeurs.

Acetabular

chip fractures

Small fractures of the cranial and caudal perimeter of the acetabulum can be removed with rongeurs. More extensive fractures can be removed with some difficulty; however, the outcome is rarely satisfactory, due to the resultant instability of the coxofemoral articulation (Fig. 10.13). Most of these proceduresare tedious and time-consuming due tothe increased depths of the joint from the skin surface. Insertion of instruments targeting the acetabular rim also places the sciatic nerve at risk, if the instrument rides over the acetabular rim and exits the dorsal (proximal) perimeter of the hip joint.

Infectious arthritis Arthroscopy provides an effective means for lavage and debridement of debris from septic hip joints. The voluminous cranial and caudal recessesof the hip joint frequently contain fibrinous and purulent debris. which can be removed by large-bore egress cannulae. or retrieved using rongeurs or motorized resectors. Lavage can also be facilitated by a second instrument entry portal for an egresscannula in the caudal recess of the hip joint. Careful insertion of all instruments into the caudal region of the hip is necessaryto avoid trauma to the sciatic nerve.

There are no large series of cases to describe the results of diagnostic or surgical arthroscopy for any of the conditions in the equine hip. Diagnostic arthroscopy has been useful in the treatment of septic hip joints in foals; however. a delay in diagnosis and involvement of other joints is common in foals. and reduces the likelihood of a sound horse. Diagnostic arthroscopy is also very useful to establish the severity of cartilage injury in mild and moderate degenerative osteoarthritis. Severalcaseshave had focal cartilage injuries which responded particularly well to local debridement. The establishment of a more accurate prognosis is also a useful benefit of hip arthroscopy.

Surgical debridementcan be expectedto improve the outcome with osteochondrosis and OCD conditions of the hip. Improvement in lameness after debridement of OCDflap lesions on the acetabular perimeter and after debridement of subchondral cysts of the femoral head have beenseen.Access for debridement of femoral head lesions depends on the lateromedial location of the cysts within the femoral head.

Debridement of relatively shallow cysts can be accomplished. and deeper cysts can be opened to some extent although debridement is incomplete. In foals and miniature horses, debridement of fraying and tearing of the ligament of the head of the femur can be easily performed, and at least with incomplete rupture, the results are quite satisfactory.

Removal of frayed ligament fibers and lavage of debris from the joint improve the degree of lameness and minimizes the likelihood of secondary osteoarthritis. Synovectomy of portions of the accessiblesynovial membrane also appears to improve the postoperative response in these cases.Complete disruption of the ligament of the head of the femur results in permanent lameness. and long-term improvement after

arthroscopyhas not beenseen.Theselesionsneed further stabilization.and techniquesfor hip stabilizationhave not beensuccessful in adult horses.

The prognosisfor a horsewith hip diseasedependson the type of lesion. extent of degenerativeosteoarthritis.and the completenessof lesiondebridement.In somecircumstances hip arthroscopyhas improved the prognosis.whereas in other casesthe extentof osteoarthritisand cartilagedamage has preventeda satisfactoryoutcome.Basedon limited case experience.arthroscopicdebridementof OCDlesionsin the hip appearsto improvethe prognosis.whereasa diagnosisof completerupt,ure of the head of the ligament of the femur is a predictor of continued lameness.Synovectomyand debridement of portions of incomplete rupture

of the

ligament of the head of the femur have been useful in providing lasting improvement in the level of lameness.

Removalof chip fracturesassociatedwith the acetabularrim is possible;however.significant improvementin outcomeis evident only with small fragments.Largerlesionsresult in destabilizationof the articulation and little long-termbenefit.

References Baber YF, Robinson AH, Villar RN, Is diagnostic arthroscopy of the hip worthwhile? A prospective review of 328 adults investigated for hip pain, J Bone Joint Surg (Br) 1999; 81: 600-603.

Honnas CM, Zamos DT, Ford TS. Arthroscopy of the coxofemoral joint of foals. Vet Surg 1993; 22: 115-121.

Miller CL, Todhunter R. Acetabular osteochondrosis dissecans in a foal. Cornell Vet 1987; 77: 75-83.

Nixon AJ. Diagnostic and operative arthroscopy of the coxofemoral joint in horses. Vet Surg 23, 377-385.

Nixon AJ, Adams RM, Teigiand ME. Subchondral cystic lesions (osteochondrosis)of the femoral heads in a horse.J Am Vet Med Assoc 1988; 192: 360-362.

Rose JA, Rose EM, Smylie DR. Case history: acetabular osteochondrosis in a yearling thoroughbred. J Equine Vet Sci 1981; 1: 173-175.

Rutkowski JA, Richardson DW. A retrospective study of 100 pelvic fractures in horses. Equine VetJ 1989; 21:256-259.

Stashak TS. Diagnosis of lameness. In: Stashak TS (ed.), Philadelphia: Lea and Febiger; Adams'lameness in horses. 1987:

150-153.

16 Warmblood horses were reported. An arthroscopic

Introduction As in other small joints. arthroscopy in the distal and proximal interphalangeal joints has specific features. The major differences between arthroscopy in "large" and "small" joints are as follows: .Exact anatomic positioning of arthroscope and instrumental portals is extremely important in all

smalljoints. .Limited distention in small joints results in limited field of view. .Limited distention and limited mobility in small joints leads to difficulties in orientation. .The tip of the arthroscope and the tips of instruments are always close to tissue. .The tip of the arthroscope is always close to the tip of hand instruments. which increases the risk of lens damage. .Diagnostic inspection of a small joint is done mainly by lateral movement and rotation of the telescope rather than by inserting and withdrawing the arthroscope as in big joints. .Re-arthroscopy is almost always performed through the same initial portals. .It is delicate surgery with delicate surgical equipment -equipment breakage or equipment failure can result in irretrievable loss of foreign bodies. .Air bubbles from escaping gas develop easier in small joints than in large joints. .Foals. yearlings. and ponies might require smaller diameter (2.7 mm) arthroscopes.

General considerations The author's G.B.)technique of diagnostic and surgical use of the arthroscope in the dorsal aspect of the distal interphalangeal joint (DIP) was first described in 1990 (Boening et al 1990). The arthroscopic technique and long-term results in

approach to the palmaroproximal and plantaroproximal aspect of the distal interphalangeal joints was subsequently developed by Vacek et al (1992), who describedthe anatomy.

It was the author's opinion that most conditions affecting these aspects of the coffin joint such as navicular bone fractures, arthrosis of the distal interphalangeal joint, penetrating wounds and septic arthritis, did not produce radiographic lesions in the acute phase and diagnostic arthroscopy was essential in establishing the diagnosis.

Recently Brommer et al (2001) described a case of a Warmblood yearling suffering from an osteochondral fragment at the palmaroproximal aspect of the DIP (Figs 11.1 and 11.2).

They successfullyremoved the fragment. which consisted of a bony core completely surrounded by cartilage. They used a lateral arthroscopic portal and a medial instrument portal.

Another clinical use for this approach is in evacuation of cystsin the navicular bone (Zierz et al2000).

Indications Indications for coffin joint arthroscopyinclude diagnostic inspectionof thedorsalpouchor of thepalmar/plantarpouch of the joint, removalof osteochondralfragmentsor avulsion fragments,removal of osteophytes(Bramlage1988), synovectomy,debridementand joint lavage.The most common indication in the dorsal distal interphalangealjoint is the removal of fragmentsof the extensorprocessof the distal phalanx(Fig. 11.3).

Diagnostic arthroscopy of the dorsal pouch of the distal interphalangeal joint

Insertion of the arthroscope The horse is under general anesthesia in dorsal recumbency.

The surgical leg is either passively flexed and loose or extended and supported in a stand. Some authors prefer a loose limb and, therefore, an assistant is needed for joint manipulation and support. After surgical preparation for aseptic surgery, the operating field is draped with sterile adhesive antibacterial barriers in addition to a large impervious arthroscopy drape. The articulation is extended and an 18- or 16-gauge needle is inserted into the dorsal joint cavity (Fig. 11.4), which is then distendedwith sterile isotonic polyionic Ringer's solution.

The dorsal joint capsule bulges easily with distention and a No. 11 scalpel blade is used to make a 5 mm vertical skin incision about 3 cm proximal to the coronary band and about 3 cm lateral or medial of the sagittal midline. This incision continues into the joint cavity. These landmarks assure an optimal position for the arthroscope -a portal too close to the coronary band and too far from the sagittal plane creates major problems in DIP joint arthroscopy. Misplacement of portal sites also incurs the risk of hitting a major blood vessel (Fig. 11.5) and the loss of orientation. As in all arthroscopic procedures. the shorter the distance from skin to joint cavity. the better.

The arthroscopic sleeveis introduced and positioned in the distal interphalangeal joint by the use of a blunt obturator to penetrate the fibrous joint capsule (Figs 11.6 and 11.7). Once the sleeve is in the joint. the obturator is exchanged for the arthroscope. and the camera. light cable. and fluid and gas ingress line are attached. The diagnostic arthroscopic evaluation can commence from this position. One author GB) prefers gas distention with carbon dioxide. as he considers it superior for all diagnostic and surgical procedures; a parallel fluid distention line is used for postoperative lavage. Hand instruments such as probes. forceps. rongeurs and cannulas are introduced through the instrument portal. This is determined by the use of a hypodermic needle.

Normal arthroscoPic anatomy of distal interphalangeal joint The dorsal pouch of the distal interphalangeal joint represents about 30% of the entire joint. The main landmark for this part of the joint is always the extensor process of the distal

phalanx (Fig. 11.8). From there the dorsal concave part of the articulation of the second phalanx and the convex part of the articulation of the third phalanx can be visualized. By rotation and relocation of the tip of the arthroscope. the lateral and medial rim of the articulation and the attachment of the joint capsule and the extensor tendon become visible.

Hyperflexion. hyperextension. and medial and lateral hoof rotation will expose additional. deeper parts. of the articulation. With this approach. even lateral or medial aspects of the distal articulation of the middle phalanx will become visible. By careful withdrawal and positioning the tip of the arthroscope into a more proximally orientated position. the dorsal joint capsule and the proximal reflection of the joint capsule can be examined.

Diagnostic arthroscopy of the palmar/plantar poucf1 of the distal Interphalangeal joint Indications Forthe palmar/plantar approachthe horsemaybepositioned in either dorsal or lateral recumbency.Dorsal recumbency

(Boening 1995). The palmar/plantar pouch of the DIP is quite spacious in the axial area, but surgical removal of fragments remains challenging. Through contralateral: instrument portals, only limited mobility of the hand instruments can be achieved.

CD

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Insertion of the arthroscope -palmar/plantar

aspect For inspection of the palmar/plantar

aspect of the (

interphalangeal joint. it is preferable to have the horse lateral recumbency. For preoperative distention of i an I8-gauge.:. ..

Up to 25 ml of sterile saline can be injected.:.into the dorsal: " .r palmar/plantar pouch. which is then used i ' -landmark to aid in exact positioning of the incision

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distention is palpable immediately axial to ; collateral cartilage. A 5 mm vertical skin incision is directly over the lateral or medial aspect of palmaro/plantaroproximal pouch. Landmarks for; orientation are the collateral cartilage (keep

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artery and nerve (keep axial) and the deep digital tendon and the digital tendon sheath (keep abaxial).

Esmarch bandage and/or a tourniquet can help to I

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Fig.11.7 Diagram of arthroscope position -dorsal pouch of the distal interphalangeal joint. CD, Common digital extensor tendon.

offers a more easy contralateral instrumental approach (Boening et al1990, Mcllwraith, 1990a).

The use of fluoroscopy for anatomic orientation is helpful.

Under such visualization, the insertion of the arthroscope, insertion of hand instruments, and the identification of the fragment's side can be achieved. In the palmar/plantar pouch of the coffin joint (seeFigs 11.1 and 11.2) fragment removal is the most common indication for arthroscopic surgery (Brommer et al 2001). These fragments are either free floating and OCDin origin or embeddedin the joint capsule or ligaments. Lesions that are the result of secondary bone metaplasia can be detected in these areas. In such cases their appearance seems to be flattish and generally accompanied by signs of degenerative joint disease.A further indication for palmar/plantar coffin joint arthroscopy is debridement of cystic lesions at the proximal rim of the navicular bone (Zierz etal 2000). The technique can be combined with cancellous bone grafts, in which CO2gas distention of the joint is required

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A conical obturator within ( . advanced (Figs 11.9 and 11.10) parallel to the plantar rim of the second phalanx. f' ., of the frog. Introduction of the sheath under jguidance is useful if available.

Entrance into the joint is marked by flow of fluid the open stopcocks. Once in the joint cavity, (replaced by the 300 arthroscope and joint distention maintained by either fluid or gas.

distal interphalangeal joint, the limited maneuverability in the coffin joint will be closed after completion of ination and/or surgery' .-, .

Sterile bandaging incorporating the entire hoof is value. The risk of and secondary joint infection is directly correlated improper bandaging. If loose bandages expose i' even loss of the patient from joint infection might result. The bandages should be changed every second day until primary healing of the skin incisions is achieved.

Normal arthroscoPic anatomy -palmarol plantaroproximal aspect The midsagittal ridge of the dorsal articular border of the navicular bone is the first structure to identify (Fig. 11.11).

DDF

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..J~/ The entire proximal border of the navicular bone plus the attachment of the joint capsule to this bone can be examined by moving the tip of the arthroscope in a palmar or plantar direction. At the medial aspect of the joint and also on the lateral aspect of the joint. parts of the collateral sesamoidean ligaments can be identified. These structures are not intraarticular but they are visible through the joint capsule at these locations. To view these ligaments the tip of the arthroscope has to be directed distally in between the navicular bone and the palmar/plantar articulation of the second phalanx. Hyperflexion causes the navicular bone to move away from its contact point with the second phalanx and this exposesmore of the distal axial parts of the joint cavity.

Arthroscopic surgery of the dorsal distal interphalangeal joint for treatment of extensor process fragments Indications The most common indication for arthroscopy of the dorsal distal interphalangeal joint is the removal of fragments of the

1

extensor process of the distal phalanx. 'I be securely embedded in the attachment of the ..., Their size and outline varies from 2 mm up to 30 mID diameter. They can be round with a smooth outline. as osteochondritis dissecans (OCD) fragments. or in ,. -with traumatic fractures they might appear more i in shape.

A complete set of preoperative radiographs :important information about the size and location of --

plantar view are standard; slightly oblique views can helpful in casesof an abaxial fragment. ( --~(CT)images may -~ of the damage, and, finally, arthroscopic accessibility. After arthroscopic identification the fragment with a periosteal elevator and removed from the joint by

of small cup rongeurs. Most of the fragments. bit is recommended. In case of

synovitis.The protruding synovialvilli ment. In suchcasesthe use of helpsto improvevisibility. processare much more difficult to access(Figs 11.12 mental portal (Vail & McIlwraith 1992) and: might be impossible to remove from the joint at all Fig. 11.14).

of postoperati~ osteoarthritis. Osteophytes and new formation. and trauma and damage to the coronary and to the attachment of the common digital tendon are potential complications after dorsal coffin arthrotomy.

One author (Hertsch 1972) removed' arthrotomy I longer an appropriate option scopyis the method of choice for all sizes of fragments.

Preoperative considerations

ments are often found on pre-purchase examination. j scopic surgery in such cases, therefore, is prophylactic

"cosmetic" in nature. However, we feel that many joints with so-called silent fragments develop secondary lesions, such as proliferative synovitis and articular cartilage damage.

In lame horses, the prognosis for complete recovery is still good as long as there are no signs of secondary new bone formation. The earliest signs of secondary osteoarthritis are osteophytes on the dorsal aspect of the middle phalanx and they are usually most obvious on oblique radiographic views.

Arthroscopic technique The surgical technique for extensor processfragment removal follows the steps of diagnostic coffin joint arthroscopy described earlier in this text. The instrument portal is carefully selected to permit access to the central articular surface. To determine the location of the instrument portal.

an 18-gauge needle is inserted about 3 cm medial to the sagittal line and 3 cm proximal to the coronary band. As most fragments are small, the tip and cutting edges of the needle can be used as a probe and for initial cut down of minor attachments of the fragment. When the needle position is judged to be satisfactory,a 5 rom stab incision with a No. 11 scalpelblade is made in the skin and continued into the joint. It is important to use well designed, strong, and unbreakable hand instruments (Fig. 11.15). In cases of instrument failure, pieces may disappear into an inaccessible area of the joint cavity.

The fragment is identified and the attachment to the connecting tissue is severed with a V-shaped periosteal elevator.The surgeon then identifies the softtissue line between the fragment and the remaining coffin bone and carefully elevatesthe 4agment from its origin (Fig. 11.16-11.19).

Narrow cup alligator forceps or low profile rongeurs are introduced into the joint and the fragment securely grasped, rotated (to make sure there are no remaining attachments), and removed from the joint cavity. At completion of the procedure, the defectcreated by the fragment is debrided and the joint cavity is lavaged using a 4.5 mm egresscannula.

In chronic cases,secondary hypertrophic reaction of the synovial membrane, combined with soft tissue fibrosis, can make identification and removal of fragments a challenge.

In such cases,it is helpful to remove the interfering synovium by the use of a mechanical synovial resector. In chronic cases, various stages of cartilage damage become visible.

Discoloration, fibrillation, and erosion up to full-thickness loss of cartilage will be in proportion to the duration of the initial disease.Intraoperative radiographs may be necessary to ensure that all parts of the fragment are removed.

Postoperativemanagement Special care is taken with bandaging, keeping in mind that bandage failure will result in exposure of the surgical incision and potential contamination with manure. It is important that the bandage covers the entire hoof. An elastic. adhesive bandage prevents slippage. Bandages are carefully monitored and changed until the skin sutures are removed 12 days after the procedure. Horses are confined to a stall for a minimum of 12 days and then hand walked daily for 15 minutes. Riding and more intensive training can start 3 to 6 weeks after the surgery. Antibiotics and phenylbutazone are administered postoperatively for a period of 3 days.

arthroscopic removal of extensor process

component, may develop (Gabel& Bukowieckie 1983).

another choice but incurs the risk of secondary failure. The implant at this location is exposedto cyclic loading and can break. The obvious operative time with less incisional exposure, visibility within the joint, and shortened period.

Problems and complications The most common problem in dorsal coffin joint arthroscopy is inadequate visualization. Suitable case selection and accurate placement of both arthroscope and instrument portals alleviates this problem. Only with optimal placement can effective triangulation be achieved. The most common mistakes are having the portals too far lateral or medial and/or to close too the coronary band. If a fragment or part of a fragment becomes loose it might be extremely difficult to relocate. Loose fragments either disappear further distally in the joint or move into the proximal pouch of the joint. Rearthroscopy within a few days after the first attempt is an option if the fragment cannot be found.

Results Since the first report in 1988 there have only been case reports published.Boening et al (1990) described 14 of 16 lame horses that recovered full athletic function after

Arthroscopic surgery of other conditions in the ~istal

joint

.

Abaxial articular fragments Other. intra-articular fragments (seeFigs 11.12 and 11.. including osteochondral chip fractures or ' & McIlwraith 1992, McIlwraith & Goodman visibility of i might still be a challenge (Fig. 11.22). The approach is routine. . portal site for hand instruments is located either medial to the extensor tendon. An 18-gauge characterized by significant porosity of the bone, reduction and fixation of the fragment is not {

Periosteal elevators are used to free ligamentous attachments and motorized arthroscopic cutting instruments can be used for resection of hypertrophic synovial membrane. fibrous bands, and for final cleaning up of the fragment bed. Joint lavage and skin closure follow the surgical procedure. These patients require securebandaging for 10 days and box rest for another 3 weeks,followed by hand walking for an additional 3 weeks. Visibility and accessibility seem to be the most demanding features of these cases.

Fragments in the palmarolplantaroproximal pouch of the distal interphalangeal joint Osteochondral fragments located in the palmar/plantar aspect (Figs 11.23 and 11.24) of the DIP proximal to the navicular bone are rare (Brommer et al 2001. Wagner et al 1982). Such fragments could be caused by an avulsion fracture of the middle phalanx or navicular bone. trauma to the articular cartilage with secondary ossification. or osteochondrosis.

With arthroscopy of the palmar/plantar

capsule at all or inadvertent intrusion into the navicular bursa or digital tendon sheath. Using fluoroscopic assistance, anatomically correct positioning can be achieved and essential structures in close proximity to each other can be protected. Injection of fluid into the dorsal aspectof the joint results in distention of the palmar/plantar pouch, which is then an important additional landmark to aid in exact positioning of the arthroscope sheath.

Distal phalanx cysts Cysts of the central weight bearing surface of the distal phalanx occur infrequently, and have beentreated with intraarticular medication and transcortical drilling. Most respond transiently to medication. and transcortical debridement through hoof wall windows has been complicated by recurrent abscessationand lameness. Intra-articular approaches for debridement have been described recently in 11 horses (Story & Bramlage 2004). Dorsal arthroscopic approaches with the distal interphalangeal joint extended and the joint distracted allow access for cyst debridement (Fig. 11.25).

Successfulreturn to work was reported in 10 of the 11 horses, which is a considerable improvement compared to results of extra-articular and conservative approaches.

proximal pouch of the DIP.the proximalarticular margin of the navicular bone can be visually assessed.

The palmar aspectof the distal articular margin of the middle phalanx. the collateral sesamoidean ligamentsof the distal sesamoid bone. and the joint capsule are further structures in the visual field.The distal margin of the navicular bone and the articulation betweenthe middleand distalphalanxcannotbe visualized(Vaceket al 1992). Arthroscopyin the palmar/ plantar pouch of the joint can be accompaniedby problems Proximal navicular cysts such as hemarthrosis and iatrogenic damageto articular Surgical treatment of cyst-like defects of the proximal rim or cartilage. Most errors are related to incorrect placementof body of the navicular bone was reported by Zierz et al (2000). the arthroscopesheath.resulting in failure to enterthe joint Referring to a technique published by Wolter & Ratusinski

co

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(1985), they drilled out bone cysts in the navicular bone of 5 horses.The arthroscopic approach was according to Vaceket al (1992). After the insertion and positioning of the arthroscope, they created a contralateral portal for a 4.5 mm drill and sleeve. The cyst was identified and subsequently drilled through diagonally. As soon as the drill reached the cyst, there was a significant loss in drill resistance. All 5 horses were Warmbloods from 6 to 16 years of age (3 show jumpers, 1 dressage,and 1 pleasure horse). Horse 1 was re-operated 9 months after the first surgery; 7 months after the second surgery there was significant progress in bone remodeling at the cyst site. Horse 2 was considered to be completely healed and was back in work 5 months after the surgery. Horse 3 became sound and went back into training after 12 weeks.

There are no reports on the outcome of horses 4 and 5. This report is contrary to experiences with drilling cysts in the medial femoral condyle, where progression of cyst enlargement after drilling has been observed.

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Fig. 11.27 Diagram of arthroscope position in the dorsal pouch of the proximal interphalange359al joint. CD, Common digital extensor tendon.

Arthroscopy of the dorsal pouch of the proximal interphalangeal joint Limited spacein the dorsal pouch makes accurate location of arthroscopic portals critical. The limb should be fixed in maximal extension and placement of the obturator and arthroscopic cannula into the joint is facilitated by distending Reports of arthroscopy of the proximal interphalangeal joint the joint with fluid from the palmar/plantar aspect are rare in the equine veterinary literature (Mcllwraith (Fig. 11.26). The cannula should be inserted along the dorsal 1990b, Schneider et al1994). One report describes a single proximal margin of the middle phalanx to the center of thejoint. case and the second a group of 3 Standardbred racehorses Ideally. the arthroscopic portal is in the distal aspects ofthe where osteochondral fragments were removed from the dorsal pouch (Fig. 11.27). Placement too far proximallylimits dorsal aspect of the proximal interphalangeal joint. In the the ability to view the entire dorsal joint space. Optimal latter study, after arthroscopic removal of the fragments from placement results in sufficient space in the joint to allowfragments the dorsal proximal interphalangeal joint, all 3 horsesreturned to be removed safely. Small alligator-cup, or lowprofile to training and raced successfully.

Ferris-Smith rongeurs are recommended because of

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space limitation. The intra-articular anatomy of the dorsal proximal interphalangeal joint is simple and consists of the dorsal distal articular cartilage of the proximal phalanx as well as the dorsal rim of the middle phalanx and joint capsule attachments (Fig. 11.28). This dorsal proximal rim of the middle phalanx is the usual location for osteochondral chip fragments (Fig. 11.29 and 11.30). Fragments found at this location could possibly result from osteochondrosis. These fragments usually cause synovitis. which results in local swelling of the proximal interphalangeal joint and associated lameness. Intra-articular anesthesia is essential for proper diagnosis. To establish the exact location of the operative site for fragment removal, at least four preoperative radiographs are required. Size and anatomic location of the fragment may be identified with a dorsopalmar/plantar, a

latero-medial, and two oblique views using radiographic films.

Following removal of fragments, ---' "--padded bandaging of the surgical site for 1 0 days confinement for 2 weeks post-surgery. hand-walked for another 2 weeks. The, allowed to train for a period of 6-8 weeks after surgery.

Arthroscopy of the p<?uchof the proximal Joint So far there are no reports found on arthroscopy of palmar/plantar pouch of '

in the literature. Although fragmentsoccur in the palmar/ plantar aspectof the pastern,it has beensuggestedthat the capsularand ligamentousattachmentslimit entry into the central part of the joint (McIlwraith 1990).

Fragments located in the axial palmar/plantar pouch are found occasionally on pre-purchase examination (Fig. 11.31). Thesecasesoften show only Grade1 lameness and insignificant clinical signs like joint distention and positiveflexiontest;someare without anylameness.

Fragments.that are located abaxialand which originate from the proximal lateral or medial rim of the middle

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2 cm proximal to the margin of the distal condyle of proximal phalanx (Fig. 11.26), close to the plantar margin, the obturator and cannula the palmar/plantar pouch aiming axially (Fig. 11.33 11.34). The axial palmar/plantar pouch is quite (Fig. 11.35), r

The instrument portal can be ipsilateral or orientation of portals and fragment identification.

After fragment removal, the joint is debrided and I and the skin is closed. The postoperative training phalanx, remain casesfor mini-arthrotomy as they cannot be accessed arthroscopically (Fig. 11.32). The pathogenesis of the avulsed abaxial fragments is traumatic; these fragments will create significant lameness in the acute stage.

For surgery of axial palmar/plantar fragments in the proxinlal interphalangeal joint, one of the authors OR)prefers the horse in lateral recumbency, while the remaining authors prefer dorsal recumbency. The joint is pre-distended with polyionic Ringer's solution by the use of a 16-gauge hypodermic needle. The landmarks for palmar/plantar injection are about 2-3 cm proxinlal to the palpable distal condyle of the proxinlal phalanx. After making a 5 mm skin incision

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interphalangeal joint arthroscopy. One author GB) of the proximal interphalangeal joint on 5 occasions: European Warmblood horses and 1 pony: Three of cases showed Grade I lameness which could be, after

joint. All fragments.ranging from 4 to 12 mm

had failedpreviouspre-purchaseexaminations.Only

after surgery. In this case the fragment could be visualized arthroscopically in between the distal condyles of I proximal phalanx. but was inaccessible.

References the 1st Advanced Arthroscopic Surgery Course, I University,1988.

Boening KJ. Contact-Arthro-Microscopy and synovial -

Annual ECVSScientificMeeting, Konstanz,1995: 71-72.

-EquinePract 1990; 311-317.

Brommer H. Rijkenhuizen ABM. van den Belt AIM. Keg Arthroscopic removal of an osteochondral fragment at palmaroproximal aspect of the distal interphalangeal.

Equine Vet Educ 2001; 13(6): 294-297.

Gabel AA. Bukowieckie CF. Fractures of the phalanges. Vet' North Am Large Anim Pract 1983; 5: 233-260.

Hertsch B. Diagnosis and treatment of pedal bone fractures. ~ Tieriirztl Wochenschr 1972; 79(21): 524-532.

Mcllwraith CWo Other uses for arthroscopy in the horse. horse. Philadelphia: Lea & Febiger 1990a: 219.

McIlwraith CWo Other uses for arthroscopy in the horse. Philadelphia: Lea & Febiger; 1990b: 220.

Mcllwraith CWoGoodman NL. Conditions of i

of osteochondral joint of the pelvic limbs in three horses. JAVMA

79-82.

Story MR. Bramlage LR. Arthroscopic debridement of bone cysts in the distal phalanx of 11 horses :-EquineVetJ2004; 36: 356-360. articular anatomy aspects of distal interphalangeal joints. Vet Surg 1992; 257-260.

Vail TB. McIlwraith CWoArthroscopic removal of ' C fragment from the middle phalanx of a horse. ~

269-272.

Wagner PC. Modransky PD. Gavin PRoGrant BD. ..Equine Pract 1982; 4: 9-15.

Wolter D. Ratusinski C. Das extraartikuliire. I

1985; 88:425-431.

ZieI"lJ. Schad D. GiersemehlK. Chirurgische Moglichkeiten Versorgung von Strahlbeinzystensowie Strukturdefekten Strahlbein.pferdeheilkunde2000; 16:171-176. out of this group of 5 horses had a problem in the front limb; all the others were affected in a hind limb. The horse with the fragment in the front leg was not lame before surgery and did not show lameness after fragment removal. All horses with affected hind limbs became sound and could go back into training; 1 of the horses with a hind limb fragment exhibited no evidence of pre-surgical lameness nor did it develop any signs of lameness post-surgically. Only the pony stayed lame

Tenoscopy of the Digital Flexor Tendon Sheath

digital flexor tendon sheath(Ragland1968. Dik et a11995.

Fortieretal1999. All are exquisitelysensitive.Surgicaltreatment of these complexcasesis appropriateto debridethe primary tendondefectand stopthe cycleof annular ligament constrictionandongoingsheathirritation (Fortieretal1999).

Introduction The primary indication for tenoscopy of the digital flexor tendon sheath is assessmentand treatment of the various manifestations of chronic, proliferative, so-called "complex tenosynovitis" of this sheath. Chronic tenosynovitis is a relatively common problem of the digital flexor tendon sheath, particularly in the hind limbs. Most mild and moderate forms of tenosynovitis cause only low-grade lameness and 'can be managed medically. More severe tenosynovitis cases, and those chronic cases that have disruption of the tendon sheath, the various mesotenons. the annular ligament, or the flexor tendons themselves,may result in a more profound and self-perpetuating cycle of increasing tendon sheath fibrosis and annular ligament thickening (Fortier et al1999). Tenosynovial massesand adhesions can developas a consequence (Watrous et al 1987). These latter types of complex tenosynovitis not only require surgical intervention but also generally have a reduced prognosis for good cosmetic outcome and return to complete soundness (Fortier et al1999, Wilderjans et al 2003). The duration of symptoms seems particularly relevant to the final outcome of these cases.

Pathogenesis Acute tenosynovitis can result from tearing of various portions of the digital flexor tendon sheath, the mesotenons, or linear tears in the flexor tendons within the sheath. Recalcitrant tenosynovitis and secondary constriction due to the palmar/ plantar annular ligament can then follow acute tenosynovitis (Dik et al19 95). Progressivefibrous thickening of the sheath and the intimately attached annular ligament can compress and restrict the free movement of the flexor tendons through the fetlock canal (Adams 1974, Gerring & Webbon 1984, Verschooten & Picavet 1986, 1988). The consequences include turgid fluid accumulation within the tendon sheath. enlarging tenosynovial massesalong the abaxial portions of the flexor tendons, particularly in the proximal portion of the digital flexor tendon sheath. and adhesions spanning from the tendons to the dorsal and abaxial parietal layers of the

CHAPTER

Preoperative assessment Lamenessoriginating from the digital flexor tendon sheath is confirmed by intrathecal anesthesia, and should be followed by a thorough ultrasonographic assessment. Particular attention should focus on the extent of tendonitis of the superficial digital flexor tendon (SDFT)and the deep digital flexor tendon (DDFT), since they profoundly affect the prognosis and the decision for surgery (Barr et al 1995).

Additionally, ultrasonographic evaluation determines the thickness of the tendon sheath wall and palmar annular ligament, and definesthe number, and lateral or medial attachment, of tenosynovial massesthat need to be addressedat the time of surgery (Stanek & Edinger 1990, Dik et al 1991, Redding 1991). Central core lesions of the flexor tendons can be treated by injection or stab incision at the time of surgical section of the annular ligament. Linear clefts within the DDFT and occasionally the SDFT present special problems in repair, with most requiring debridement, and some requiring suture repair (Wright & McMahon 1999). In the authors' experience ultrasonographic examination is not sensitive in detecting linear clefts in the tendon structure. Any ultrasonographic suggestion of echolucencies within the surface one-third of the flexor tendons is highly suspicious, and this region should b'~ carefully assessedduring endoscopic exploration. Additionally, adhesions and soft tissue masses within the tendon sheath, as well as between the SDFT and DDFT, need to be removed. Presurgical preparation and draping must provide accessto both lateral and medial portions of the digital flexor tendon sheath, to allow instrument access to these tissues for removal or sectioning.

Surgical anatomy The digital flexor tendon sheath consists of a parietal and visceral layer that provide the inner lining of the sheath and the surface layer of the enclosed tendons, respectively. The intimal layer is several cell layers thick, and is supported by

Cut annular ligament

dense subintimal and sheath fibrous layers (Hago et aI1990).

The digital flexor tendon sheath extends from the junction of distal and middle thirds of the third metacarpus/metatarsus to the level of the middle phalanx and navicular bone (Fig. 12.1). The sheath enclosesthe SDFTand DDFT, both of which have mesotenon attachments to the tendon sheath.

The most robust mesotenon extends from the palmar midline of the SDFT to the adjacent tendon sheath (Figs 12.2 and 12.3). Short thick mesotenons also extend from the proximomedial and proximolateral margins of the DDFT.The proximal portion of the DDFT is encircled by a complete but thin sleeve of the SDFTknown asthemanicaflexoria (seeFigs 12.1-12.3),

which ensures alignment of the tendons during their passage around the fetlock. The digital flexor tendon sheath has its proximal reflection and attachment to the full circumference of both the SDFT and DDFT, which forms the proximal endpoint of the sheath cavity. In the distal portions of the

digital flexor tendon sheath, the DDFT has several dorsal and a single palmar/plantar mesotenon attachment (seeFig. 12.1, inset). There is also a small encircling component (the digital manica) of the SDFT (see Fig. 12.1, inset), which stabilizes the SDFT against the DDFT during the final path toward

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tendon insertion (Nixon 1990c, Redding 1991 1993). The SDFTcan be seento bifurcate and exit the digital flexor tendon sheath in the region of the distal portion of the proximal phalanx (Fig. 12.4). Vascular supply to the flexor tendons is derived through the mesotenon and digital sheath reflections.

Synovial fluid from the tendon sheath has a similar composition to that from joints, with slightly reduced hyaluronic acid content (Malark et aI1991).

gentlyin a proximodorsaldirection dorsal recessesof the sheath (see Fig. 12.5). High wall of a fibrosed tendon: the initial phases of digital flexor tendon sheath allowing time for the tissues to expand and hemorrhage and synovial fluid to 1 ' , through severalneedles.

Tenoscopic techniques Diagnostic tenoscopy The standard approach to the digital flexor tendon sheath uses a skin entry portal for the arthroscope on the palmaro/ plantarolateral aspect of the sheath between the annular ligament and proximal digital annular ligament (Fig. 12.5).

Distention of the tendon sheath defines an outpouching at this site. A skin incision is made slightly palmar/plantar to the center of this prominent outpouching, to allow the arthroscope to be directed proximally through the fetlock canal, and then to be redirected for examination of the distal tendon sheath region (seeFig. 12.5). Entry of the arthroscope sleeveand conical obturator needsto be performed with care, since the flexor tendons in chronic caseshave fragile epitenal surface layers. and iatrogenic damage is a possibility. The skin incision and entry portal through the fibrotic tendon sheath need to be slightly larger than normal, so thatthe arthroscope sleeve and obturator enter easily. Once the sleeve and obturator have entered the digital sheath, they are pushed

should involve entry outside the manic a flexoria, many of the larger tendon sheath massesdevelop (Fig. canal and inserted beneath the manica the proximal DDFT. Linear clefts i found at this~vel, which may correspond to , stricted region of the fetlock canal when the limb SDFT, paying particular attention to adhesions and massesdirectly between the flexor tendons (Fig. 12. '; the arthroscope is withdrawn from I redirected palmar/plantar to the SDFT, where the mesotenon attachment is evident (seeFig. 12.7).

sheath is restricted. In such cases, examination can improved by severing the annular ] phases of the surgical procedure, ( tendon sheath masses and other adhesions. The

Fig. 12.6 Tenoscopic view of the fetlock canal region with the arthroscope inserted distal to the annular ligament and looking proximally (as in Fig. 12.5). The lateral sesamoid (Ses). annular ligament (AL). manica flexoria (MF) of the SDFT (S). and the DDFT (D) are evident.

Ses

~

instrument entry is made in the dorsolateral region of the proxinlal cul-de-sac of the digital flexor tendon sheath (see Fig. 12.5). This is defined by needle entry followed by scalpel incision. The entry to the digital flexor tendon sheath should be palmar to the neurovascular bundle, to avoid damage to these structures. Preoperative placement of a tourniquet is routine and is a useful means to limit hemorrhage from skin entries, adhesion and mass removal sites, and the annular ligament division. particularly if this is done early in the

surgical examination and treatment of complex cases. tourniquet is ] ment of a septic digital flexor tendon sheath. lateral skin entry then provides

motorizedresectors.As resectionof medial layer of entry 1_-

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'

~lade, Dyonics -Smith & Nephew,Andover,MA), with relatively \Tidecutting apertures and active suction, allow entry of theissue to the cutting blade. Biopsy punch rongeurs (Dyovac ;.2, Dyonics -Smith & Nephew), biopsy cutting forceps,etractable blades, and arthroscopic scissors can all be useful Drremoval of masses(Fig. 12.12). The biopsy punch rongeur s useful for removal of adhesions; however, motorized'esectors provide more efficient soft tissue mass removal.

Nith large masses,a secondinstrument portal may be required 0 provide tension on the mass while it is severed at its basemd removed using hand instruments. Access to the region )etweenthe DDFTand SDFTwill require an instrument entry ;hrough the proximal portion of the manic a flexoria of the)DFT. The original skin portal in the dorsal lateral surface of:he proximal portion of the digital flexor tendon sheath canJe used; however, a separate incision needs to be developed through the surface of the manica flexoria to allow instru-ments to enter between the DDFT and SDFT. The authorsl1ave not recognized complications associated with these additional perforations. Bleeding from the sheath and epitenon surface of the tendons after mass resection can be profuse,and a tourniquet becomesmore important as disease chronicity increases. In most circumstances, the palmar/ plantar annular ligament is transected after removal of flexor Ienaun ~Il~ltLIl LU ItUUW ~llLLY VI lla11U 111"" U111"1'." =1"motorized tendon sheath masses. However, if movement through the resectors for direct accessto synovial massesandadhesions fetlock canal is restricted, the annular ligament should bedivided (Fig. 12.8). early.

Redirection of the arthroscope into the distal regions ofthe digital flexor tendon sheath permits evaluation of bothsurfaces of the DDFT and the dorsal surface of the SDFT,the digital manica, and the mesotenon (vinculae) (Fig. 12.9).

"U"~C,"L'VII vI LII'" """"""""",.,,' Ultimately, the arthroscope can be inserted to the distal limits annular ligamentThe of the digital flexor tendon sheath. Generally, proliferativemasses only effective treatment for genuine palmar/plantarannular and adhesions are less prevalent in the distal regions ligament constriction is surgical division. A simpleannular of the sheath. ligament transection can be accomplished withoutthe Reversal of the instrument and arthroscope portals allows need for tenoscopy,but in many cases constriction is part examination of the digital flexor tendon sheath using a of a complex tenosynovitis syndrome which requires proximal approach (Fig. 12.10). Instruments can be inserted resection of tissues in addition to the annular ligament. through the distal skin portal, allowing further motorized Tenoscopically assisted annular ligament transection can be resection of adhesions and masses associated with the accomplished free hand using a variety of right-angled flexor tendons and tendon sheath distal to the level of blades, or preferably using a slotted cannula (Dyonics -Smith the fetlock. & Nephew, Andover, MA) for better control of the blade (Fig. 12.13). This latter technique was developed for carpal tunnel surgery in man (Chow 1989. 1999). and has been .eno~~op'~ mu~~"~'"UYU"UU"~~"'" ..u..~~'"..v.. adapted without change to the instrumentation for annular ligament releasein horses (Nixon et al1993). The advantages Open tendon surgery for removal of tenosynovial massesand of tenoscopic annular ligament release include the precision adhesions delays initiation of exercise postoperatively and of the cut, the safety of identifying and avoiding vital structures predisposes to adhesion reformation (Watrous et al 1987, such as the manica flexoria and flexor tendons, and the Nixon 1990b). Tenoscopic examination of the digital flexor extensive dissection that can be performed through limited tendon sheath is preferred, as the minimally invasive approach entry wounds. which provides better wound healing with provides complete access to most of the sheath contents, less risk of dehiscence and earlier postoperative exercise permits multiple mass removal, and allows early return to (Nixon et al 1993). Placement of the slotted cannula is walking in the convalescent period (Nixon 1990c). Large critical to facilitate insertion of the arthroscope and 900 tenosynovial masses can be challenging to remove, and angled blade.

The proximal entry portal should be dorsal in complete assessmentcan be difficult until some of the tissue the digital flexor tendon sheath and the distal exit portal is resected. Preoperative ultrasonography is used to target plantar/palmar. to allow the arthroscope or blades to clear and develop a plan for mass removal (Fig. 12.11). Straight

(Fig. 12.16). Complete division is verified by external palpation of the blade tip beneath the skin, transillumination of light from the arthroscope through the skin, and direct visual evidence of a lack of remaining ligament fibers along the path of the transection. Hemorrhage is flushed from the cannula and tendon sheath, the cannula is removed. and the skin incisions sutured if no further procedures are required. In

many cases the arthroscope is reinserted. the annular ligament desmotomy inspected. and further exploration and surgical procedures performed. The increased maneuverability of the arthroscope within the digital flexor tendon sheath provides a more complete assessmentof the adequacy of adhesion and mass removal.

Several single portal carpal tunnel release devices have beendeveloped for use in man (Arthrex. Naples, FL; Linvatec, Largo, FL). Both work for release of the annular ligament in horses. However, it is rare not to require a proximal and distal entry for other digital flexor tendon sheath procedures, so a single entry portal system has less utility in the horse.

Tendon linear clefts

the heel-bulbs (Fig. 12.14). Interference of the heel-bulb with the arthroscope and video camera can be frustrating, particularly in breeds such as Cobbs.

The cannula with obturator in place is inserted from proximal to distal using arthroscopic visualization (see Fig. 12.14). The insertion path must be external to the manica flexoria, or this ring of the SDFTwill be divided along with the annular ligament. As the slotted cannula and its ribbed obturator near the distal portal. the tip of the arthroscope is retracted 5 mm into its sleeve, to create a docking portal for the obturator of the slotted cannula (Fig. 12.15). This is then advanced, pushing the arthroscope and sleeve out of the tendon sheath and allowing the slotted cannula to exit the arthroscopic skin portal. The ribbed obturator is then removed from the slotted cannula, and the unsheathed arthroscope inserted to view and confirm positioning with respect to the flexor tendons, the sesamoid surface, and the palmar/plantar annular ligament. The slot in the cannula is then oriented to open directly toward the annular ligament (Fig. 12.14D), before the 900 angled blade is inserted and drawn across the fibers of the annular ligament to sever the full thickness of the ligament

An increasingly recognized syndrome involves longitudinal clefts in the DDFT and less frequently in the SDFT.The linear clefts can penetrate a variable distance into the substance of the tendon, and in some instances have been extensive. The treatment of choice is tenoscopic debridement (Fig. 12.17), which has proved superior to suture repair following open surgical approaches (Wright & McMahon 1999, Nixon 2002a). Length of tears in the DDFT can extend from 4 to 10 cm, and frequently involve the DDFT from the level of mid proximal phalanx to extend beyond the level of the apex of the proximal sesamoid bones. The depth of linear cleft varies from penetration to the center of the DDFT (seeFig. 12.17), to more superficial fiber erosion. Trimming of exposedtendon fiber can be accomplished using a combination of biopsy punch rongeurs (Dyovac 5.2), and motorized resectors with both side and forward aperture, which are also effective in trimming down epitenal and tendon fiber damage. The aim should be a relatively smooth tendon surface. Access to the region between the DDFT and SDFT may also be required to trim linear clefts in the DDFT that extend proximal to the

sesamoid,(bones,and this needs an entry through the proximal portion of the manica flexoria for instrumentation, as described earlier.

In some casesthere may be tearing of the manica flexoria.

This may result from ongoing pressure within the fetlock canal associated with constriction by the palmar/plantar annular ligament, or may arise as primary lesions. Depending on the extent of the tear, the edges of the cleft can be debrided, or the manica resected in toto using arthroscopic scissors, knives or motorized resectors (Fig. 12.18). No attempt at suture repair has been used. Other pathologic conditions can develop associated with chronic constriction of the annular ligament, including separation of the palmar mesotenon of the SDFT.These areas can be trimmed, and any secondary adhesions resected. The aim of digital flexor tendon sheath adhesion removal should be free motion of the

flexor tendons within the digital flexor tendon sheath.

Alternating the arthroscope entry from the distal to the proximal portals is necessaryto allow complete assessmentof the adequacy of the surgical procedures. Tears of the proximal mesotenon of the DDFT and of the digital manica have also been encountered by one of the authors (I.M.W.).

Postoperative care Sodium hyaluronan (NaHA; 20-40 mg) is frequently injected into the tendon sheath at the time of wound closure.

Researchin horses and smaller experimental animals indicates NaHA reduces the formation and reformation of tendon adhesions in the sheath area and enhances intrinsic tendon healing (Weiss et al1986, Amiel et al1989, Gaughan et al.

1991, Moro-oka et al 2000). Additionally, intrathecal local anesthetic installation provides good postoperative pain control. The use of long-acting anesthetic agents such as bupivacaine provides 4-6 hours of postoperative analgesia. A firm bandage is also applied, not only to provide a sterile environment but also to add counterpressure that provides additional comfort to the operated limb. The bandage is usually maintained for 3-4 weeks after surgery.

Antibiotics such as potassium or procaine penicillin are commenced prior to surgery and continued for 1 or 2 days postoperatively. Surgery around the bulb of the heel and the distal portion of the digital sheath can be difficult to establish and maintain a sterile field, particularly around the ergot, and antimicrobial drugs are a useful precaution. Longer-term pain control is provided with nonsteroidal anti-inflammatory agents such as phenylbutazone (4.4 mg/kg orally), which is usually administered for 7-10 days after surgery to minimize tissue inflammation and swelling.

Hand walking for increasing periods commences 2-3 days after surgery:Long periods of walking exerciseare particularly helpful if tendon adhesions were present at surgery. A compromise between incisional healing and the beneficial affects of early exercise is usually reached on a case-by-case basis. Use of mechanical walkers, swimming, and passive

~

injection of NaHA is recommended 2 Injection of the digital flexor tendon sheath is

intravenous NaHA (Legend,Bayer Corp, Animal ShawneeMission,KS)may alsobe useful.

Return to work' secondary tendonitis, which frequently delays return exercisefor 6-12 months. ultrasonographic examination is useful to evaluate

responseof the flexor tendons. particularly where linear tendontearsweretrimmed or corelesionswereinjectedwith growth factors or NaHA at the time of palmar/plantar annular ligamenttransection.

Results and prognosis Endoscopic mass removal and annular ligament division in 25 horses followed for 1-7 years revealed a normal cosmetic outcome in 10 horses, and an improved cosmetic outcome in 12 of 22 horses (Fortier et alI999). Lamenesswas eliminated in 18 horses (72%) and improved in another 4 horses, while 3 horses remained lame. The poorest responsewas evident in 2 horses with concurrent tendonitis in the region of the fetlock canal. The cosmetic outcome was inversely related to preoperative duration of clinical signs and the severity of synovial masses. Additionally, a longer history of symptoms led to a thicker annular ligament on preoperative ultrasonography, which was frequently later confirmed at surgery. The results following debridement of linear tears in the DDFT

have also been reasonably good (Wright & McMahon 1999, Wilderjans et aI2003).

Simple constrictive syndromes due to a wound, desmitis of the palmar/plantar annular ligament, or chronic fibrosing synovitis of the tendon sheath have a good prognosis for return to work after annular ligament transection. The outlook is guarded where extensive tendon adhesions are resected,as these casesoften have residual obliteration of the tendon sheath cavity with tendon tie-down in the proximal and distal limits of the sheath. A better prognosis can be afforded by an aggressive tenoscopic dissection to free the tendons within the tendon sheath.

Tenoscopy of the Carpal

Sheath Introduction The carpal sheathhas beenused for many yearsto refer to what is now listed in Nomina Anatomica as the common carpal sheathof the digital flexortendons.Throughout this chapter,we referto this structure as the "carpal sheath" for the sakeof brevity and readerfamiliarity. Additionally,other

terms occasionally used to indicate the carpal sheath include "carpal flexor tendon sheath" and "carpal canal". The carpal canal will be used to describe that subcomponent of the carpal sheath bound by the carpal flexor retinaculum, spanning from the accessory carpal bone to the carpal ligament.

Carpal sheath conditions that result in chronic and often insidious lameness have been increasingly recognized and examined by exploratory endoscopy (McIlwraith 2002a, Textor et al 2003, Nixon et al 2004). Many of the clinical components of carpal sheath/carpal canal lameness may be interrelated. Radial osteochondroma,radial physeal exostoses, tendonitis or myotendonitis of the proximal portion of the digital flexors, and idiopathic carpal tunnel syndromes may all result in lameness and/or sheath distention. These conditions frequently have little to differentiate them based on their clinical appearance. Endoscopic examination is useful for assessmentand confirmation of the diagnosis of many of these syndromes, and can then be followed by definitive repair. Arthroscopic approaches to the carpal sheath have been described (Cauvin et a11997, Southwood et alI998).

Removal of radial osteochondroma under arthroscopic visualization is simple and effective, and eliminates the deep dissectionnecessarywith open approaches(Squire et al1992, Southwood et al1997, ter Braake & Rijkenhuizen 2001).

Additionally, many horses have caudally protruding bony exostosesassociatedwith the closeddistal physis of the radius (Nixon et al 2004). These exostosesare considered to result from previous physitis and when centrally placed can penetrate the carpal sheath and excoriatethe DDFT (Nixon et al 2004). Idiopathic carpal canal syndrome can arise from damage to the carpal retinaculum, carpal sheath, myotendinous junction of the flexor tendons, and fracture of the accessory carpal bone. Tenoscopic division of the carpal retinaculum can be used to open the carpal canal and release pressure on the digital flexor tendons (Textor et al2003). This reduces the risk of complications associated with open surgery, including persistent swelling, seroma formation, wound dehiscence and fistula formation.

Surgical anatomy The carpal sheath is a voluminous synovial cavity that extendsfrom the levelof the lowermiddlethird of the radius to the uppermiddlethird of the metacarpus.It envelopsthe SDFTand DDFTand their myotendinousjunctions during passagethrough the carpal canal. Functionally,the carpal sheath provides protection and lubrication. and minor metabolicsupport.to bothtendonsastheytraversethecarpal canal.The parietal and visceralsurfacesof the carpal sheath are morphologically similar to the digital flexor tendon sheath.The carpal sheathis more spaciousproximal to the level of the accessorycarpal bone. where it contains both SDFTand DDFTand the radial head of the DDF,coursing from the caudalaspectof the radiusto its aponeurosison the DDFT(Fig. 12.19). The medial side of the SDFTwithin the carpal sheathalsohas an intimately attachedmedialpalmar

artery and nerve (Fig. 12.20), which can be compressedin carpal canal syndromes. These are rarely viewed during routine carpal sheath tenoscopy because the approach is generally from the lateral aspect. The SDFT and DDFT are closely intertwined during their passage through the carpal sheath, and have a common and extensive mesotenon that exits from the caudomedial aspect of the tendons and attaches to the caudal aspect of the carpal sheath (see Fig. 12.20). This effectively prevents complete examination of the carpal sheath using lateral surgical approaches. Other important neurovascular structures that lay outside of the carpal sheath (see Fig. 12.18), are relevant in carpal canal release (Textor et al 2003), and should be avoided in the tenoscopic dissection. The substance of the carpal flexor retinaculum forming the carpal canal and the distal extent of the proximal check ligament can be seen intruding on the medial wall of the carpal sheath in the center and proximal regions, respectively(seeFig. 12.19). Vascular support for the SDFTand DDFT is provided through the mesotenon attachment, the proximal and distal carpal sheath reflections to the tendons, the radial head of the DDFT, the proximal check ligament attachment to the SDFT,and the entry of vessels through the myotendinous junctions. The carpal sheath fluid has a similar composition to digital flexor tendon sheath fluid. The carpal sheath becomes considerably reduced in diameter distal to the carpal canal (Fig. 12.21), which limits the mobility of instruments during tenoscopic examination, despite the fact the mesotenon is thinner in the distal recessof the sheath.

Tenoscopic techniques Introduction The role of radiographically evident bony exostoses and osteochondromas in causing damage to the DDFT and carpal sheath effusion are well described. and tenoscopic removal has been curative (Squire et a11992. Southwood et al1997, Mcllwraith 2002a, Nixon etal2004). Carefulultrasonographic examination of the carpal sheath has also identified soft tissue lesions within the tendons or carpal sheath. and provides better preoperative information for planning the tenoscopic access. Casestwith carpal sheath effusion but without an obvious radiologic or ultrasonographic cause are frequently treated initially with a combination of intrathecal NaHA and corticosteroids. If lameness and/or distention persists, diagnostic tenoscopic examination is warranted.

Diagnostic arthroscopy of the carpal sheath The authors use variations of the standard proximolateral approach to the carpal sheath as described by Southwood et al (1998). This technique allows evaluation of the entire proximal portion of the carpal sheath, including the carpal canal region, but provides limited access to the metacarpal region of the sheath. Insertion of the arthroscope into the distal region of the carpal sheath improves examination of this area (Cauvin et aI1997).

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Extensor carpi .radialis tendon

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Surgery can be performed with the horse in dorsal recumbency, or in lateral recumbency with the affected limb uppermost. Dorsal recumbency is generally preferred by the authors. It has obvious advantages for bilateral evaluation and significantly reduces intraoperative hemorrhage. Lateral recumbency facilitates tenoscopy through the distal (metacarpal) portal and some surgeons find the operating position to be more comfortable. In both situations, the carpus is positioned in slight (approximately 15-20째) flexion. The carpal sheath is distended with 50-60 ml of lactated Ringer's solution and the arthroscope entry portal is made laterally, 6-8 cm proximal to the remnant of the radial physis. This allows examination of the carpal sheath, while leaving the region between the arthroscope entry and the distal physis of the radius available for instrument entry (Fig. 12.22).

Initial examination from the lateral approach reveals the caudal aspect of the radius, and the lateral portion of the DDFT, which at this level obscures most of the SDFT (Fig. 12.23). The SDFT can be examined later by rolling the DDFT with a probe, but this exposes only small portions of the tendon; complete examination of the SDFT is difficult using the lateral approach. The common mesotenon for the SDFTand DDFT attaches to the caudolateral aspect of the carpal sheath, and effectively prevents examination of the SDFT over its caudal and medial surfaces. In the more distal regions of the carpal sheath, the SDFT emerges, although better examination of this tendon is provided through a palmarolateral portal 4-6 cm distal to the accessory carpal bone (Cauvin et aI1997).

Maneuvering the arthroscope to examine the more proximal regions of the carpal sheath reveals the radial head of the DDFT coursing from its aponeurosis on the DDFT cranially to curve and expand into its origin on the caudal aspect of the radius (see Fig. 12.23). The proximal check ligament can also be identified within the medial wall of the

carpal sheath immediately cranial to the radial head of the DDFT,but can be more clearly defined by using an instrument to probe for the intrusion of the ligament into the sheath (see Fig. 12.23).

The arthroscope can then be redirected to more caudal regions of the carpal sheath, examining the caudal surface of the DDFT and a small portion of the SDFT (see Fig. 12.23).

The arthroscope can be inserted from the lateral to medial direction to assess these areas of the SDFT and can be inserted a small distance between the SDFTand DDFT before encountering the common mesotenon joining the DDFT and SDFT. Further examination of the craniomedial depths of the carpal sheath reveals the transversely oriented fibers of the carpal flexor retinaculum, forming the medial boundary to the carpal canal (Fig. 12-24). The proximal and distal limits of the retinaculum are not as distinct as the intrusion formed by the proximal check ligament. The proximal border of the retinaculum can be recognized only by the adjacent caudal protuberan~ of the physeal scar of the radius. The distal border of the retinaculum can be determined by digital pressure over the caudomedial portion of the carpal sheath, which can easily be indented only beyond this distal margin.

The distal regions of the carpal sheath can be examined beyond the level of the carpometacarpal joint, but mobility distal to this level is restricted. Examination of the most distal regions of the carpal sheath can be performed by inserting the arthroscope through the palmarolateral surface of the carpal sheath in the proximal metacarpus (Cauvin et al 1997), and viewing proximally. This can be difficult with the horse in dorsal recumbency, but the limb should be draped to allow this portal if needed.The arthroscope portal can also be made in the palmaromedial surface of the sheath at this level but, with the horse in dorsal recumbency, manipulating the arthroscope becomes even more difficult.

~

Removal of radial osteochondroma Radial osteochondromas originating on the caudal portion of the radial metaphysis penetrate a variable distance into the carpal sheath (Fig. 12.25). They are usually lateral and can be easily identified arthroscopically. An 18-gauge spinal needle is used to identify an appropriate instrument portal directly over the mass (Squire et al 1992). An osteotome (4 rom Cottle) is used to separate the osteochondroma from the caudal aspectto the radius. The osteochondroma is then retrieved using large rongeurs, and the bony bed smoothed using a curette, bone rasp, or motorized burr. Secondary damage to the DDFT may require debridement with biopsy rongeurs or motorized apparatus. Finally, debris is flushed from the sheath before routine skin closure.

One of the principal advantages of tenoscopy compared to open surgery for removal of osteochondroma is the ability to assessand treat tendon lesions, which also allows for a more accurate prognosis. Fibrosis and thickening of the carpal sheath secondary to osteochondroma is common, and an assessmentof the degree of resultant carpal canal stenosis can also be obtained tenoscopically. If there is evidence of carpal canal constriction, which can be subjectively determined by the limitation to arthroscope movement through the carpal canal, release of the carpal flexor retinaculum can also be accomplished (see later description).

Removal of radial physeal exostoses Radial physeal exostosesare removed using a similar techniqueto that for radial osteochondroma(Nixon2002a,

Nixon et al 2004). Most clinically relevant radial physeal exostosesinvolve protrusion of one or two caudally directed physeal remnants (Fig. 12.26). The lateral remnant is generally more severe than the medial, and they can form a valley through which the DDFTcourses. Damage to the DDFT can be extensive,including excoriation of the epitenon, linear

during division of the more proximal regions of the check ligament. With experience. it is generally easier to perform the entire surgery with the arthroscope placed in the more distal instrument portal. The instrument and arthroscope tend to follow a sinlilar plane, making triangulation more difficult during the latter portion of the surgery. However,the proximal fibers of the check ligament can be identified and divided using biopsy rongeurs. Use of a radiofrequency probe (Arthrex, Naples, FL) has been helpful to divide the proximal check ligament more cleanly (Fig. 12.30). However, because the probe cuts cleanly, and it can be difficult to seethe depths of the division between the closely apposed divided edges, particularly in the proximal region of the check ligament.

At the end of the procedure, the surface of the flexor tendons should be carefully examined to be sure there are no additional tendon injuries that may influence prognosis or require treatment. Severalcaseshave also had tearing of the aponeurosis of the radial head of the DDFT with the main structure of the DDFT (Fig. 12.31). This has been recognized by three of the authors; however, the clinical significance of this lesion is still unclear.

Carpal tunnel syndrome

recumbency. Penetration of the thin sheath surrounding the flexor carpi radialis tendon is routine. and is an important landmark since it defines the medial endpoint for the dissection (Nixon 1990a). Exchange of arthroscope and instrument portals is often useful to improve visualization

The carpal flexor retinaculum can be released using the tenoscopic access portal described above. but with the arthroscope directed distally rather than proximally (Fig. 12.32) (Textor et aI2003). Identification of the fibers of the carpal flexor retinaculum that form the medial aspect of the carpal tunnel is accomplished using digital pressure followed by insertion of a needle to define the distal and proximal extent of the retinaculum. An instrument portal is then made 10-15 mm proximal to the accessorycarpal bone.

This should be defined by prior insertion of a spinal needle to verify there will be sufficient angulation for instrument accessto the distal aspect of the retinaculum. If the incision is made immediately adjacent to the accessory carpal bone. it can be difficult to insert instruments obliquely to accessthe distal portion of the retinaculum. Arthroscopic release of the retinaculum is performed in the visible portion cranial to the SDFTand DDFT. Partial flexion of the carpus is used to allow retraction of the DDFT within the carpal canal and exposure of the~visible fibers of the carpal retinaculum. The incision in the ,retinaculum is made 5-10 mm caudal to its confluence with the palmar carpal ligament. which forms the palmar surface of the carpal joints (Fig. 12.33). Transection is confirmed by entry into the tendon sheath of the flexor carpi radialis. This is a major landmark in safely performing carpal retinaculum release. Severing the carpal retinaculum more caudally risks perforation of the radial artery or medial palmar vein. The palmar retinaculum predominantly runs on the deepsurface of the flexor carpi radialis tendon. although there are some portions that are superficial (medial) to this tendon (Textor et al 2003). The retinaculum is divided with a curved serrated blade or radiofrequency probe. cutting proximally from the distal edge until 1 cm beyond the proximal border of the accessory carpal bone. The carpal

sheath is then probed to ensure there are no thickened

areas containing residual fibers of the carpal retinaculum, either proximally or distally. The flexor carpi radialis tendon should be visible throughout the entire transected area (Fig. 12.34).

If necessary, the dissection can be continued superficial (medial) to the flexor carpi radialis tendon, by retraction of this tendon cranially and division of the superficial lamina of the flexor retinaculum (see Fig. 12.34). The surgeon should decide whether to continue the dissection through this thin medial portion of the carpal retinaculum. This is based on the degree of relief of the carpal canal, which can be assessedby the increased ease of movement of the arthroscope and the increase in viewable structures within the carpal canal.

Severing the medial portion of the retinaculum can be done safely,since the radial artery is approximately 7 mm caudal to the flexor carpi radialis tenqon. However,the medial palmar vein is only 2-4 mm caudal to this site, and careful dissection is necessaryto avoid perforating this vessel.

In clinical cases,the carpal sheath and flexor retinaculum have been thickened predominantly on the deep (inner) portion, forming the visible interior layer of the retinaculum overlying the flexor carpi radialis tendon. Division of only this portion of the retinaculum has been adequate to resolve carpal canal symptoms in two horses in a recent publication (Textor et al 2003), and a further seven horses operated on since then. However, a larger case series has not been published. Secondary carpal canal syndrome, developing as a result of radial physeal exostoses,or myotendonitis and/or tendonitis of the contained flexor tendons, may also benefit from division of the carpal retinaculum, using the same rationale as described for treating flexor tendonitis within the confines of the palmar annular ligament at the fetlock (Nixon

1990b). The procedure is simple. has few risks of wound healing complications. and can often be added to other procedures during the tenoscopic examination and treatment of disorders of the carpal sheath contents.

Postoperative

care

The use of tenoscopic techniques to evaluate the carpal sheath and address specific pathology has minimized wound healing complications. The need for extended wound support by bandaging and limitation of postoperative exercise has also been reduced. Return to an active walking program is rapid, and the extent of layoff from work is then dictated only by the pathology of the tendons themselves rather than the surgical approach. Animals are usually given perioperative antimicrobial,l:lrugs.

Intrathecal NaHA (20-40 mg) is commonly usep, both at surgery and 2-3 weeks later. Followup intravenous NaHA may also be useful, commencing 4-6 weeks after suture removal. Bandage support should be provided to keep the arthroscopic and instrument portals covered for the first 5-10 days after surgery. This usually consists of light bandages, sponges. and adhesive elastic bandage. Most horses undergoing tenoscopic procedures of the carpal sheath show little lameness beyond the initial day of surgery. Intrathecal anesthetics such as bupivacaine are useful during surgery but generally are unnecessary in the control of postoperativepain. Nonsteroidal anti-inflammatory agents are usually given for 2-3 days after surgery.

Horses are confined to the stall for the initial 1-2 days after surgery. and small periods of hand walking are then instituted. A balance is necessary between an early return to

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walking exerciseand healing of carpal sheathstructures.

Adhesions associatedwith surgery in the carpal sheath appearto berare.

Results and prognosis There are several individual case reports or small case series describing tenoscopic removal of osteochondroma, excision of exostosesof the caudal aspect of the physis of the radius, and release of the carpal tunnel (ter Braake & Rijkenhuizen 2001. Mcllwraith 2002a. Textoret al2003, Nixonet al2004).

These reports suggest exostoses from the physeal remnant and osteochondroma arising from the metaphyseal region present with similar carpal sheath effusion and lameness. and both resolve with mass removal (Mcllwraith 2002a.

Nixon et al 2004). Lameness and effusion resolved in all 10 cases reported with radial exostosis (Nixon et al 2004). A series of horses having endoscopicallyassistedcheck ligament division has also been described (Kretzschmar & Desjardins 2001). This procedure was considered minimally invasive and was completed in lesstime than open division. It has also resulted in a renewed interest in the use of proximal check ligament desmotomy for treating SDF tendonitis. However. one of the authors (A.J.N.) recommends the procedure should be performed bilaterally in all horses. regardless of age. since a 6% incidence of bowed tendon in the opposite limb has been recorded in a recent study (Nixon 2002b).

The prognosis following repair methods using carpal sheath tenoscopy largely depends on the original pathology.

Ultrasonographic examination followed by tenoscopic evaluation and treatment provides critical information for the prognosis, and the structure and duration of the convalescent interval. The prognosis following removal of osteochondroma and exostosesof the caudal perimeter of the physis of the radius is good to excellent (Held et al 1988.

Squire et al 1992, Southwood et al 1997. ter Braake & Rijkenhuizen 2001, Nixon et al 2004). The prognosis following carpal retinacular release is unknown. although

v., n.

five horsesundergoingtenoscopiccarpal canal releasehave recoveredfrom the lamenessassociatedwith the carpal sheath region (Textor et al 2003). The prognosisfor SDF tendonitistreatedby proximal checkligamentdesmotomyis difficult to determinebecauseof the influencesof ancillary treatmentto the tendon,exerciseprotocol,and the amount of time providedfor convalescence.

Tenoscopy of the Tarsal Sheath Introduction The nomenclature surrounding the tarsal sheath and the DDFThas been through severalchanges. The DDFT has been referred to as the flexor hallucis longus and as the flexor digiti I tendon. The m()re recent term for the DDFT is the "lateral digital flexor tendon". However, the use of DDFT is still extremely common among surgeons and has been continued here for the sake of clarity. Persisting lameness associated with tenosynovitis of the tarsal sheath (thoroughpin) is relatively common, and can result from trauma to the fibrous layers of the tarsal sheath, damage to the mesotenon attachments of the DDFT within the tarsal sheath, and tendonitis of the DDFT itself (Van Pelt etal1969, Van Pelt 1969, Dik & Merkens 1987. Mcllwraith 2002b). Additionally. the DDFT courses over the sustentaculum tali. which can be injured through direct trauma, resulting in bone proliferation and damage to the flexor tendon as it undergoes directional change through the region of the hock (Edwards 1978, Dik & Merkens 1987). The tarsal sheath is not invested by as dense a constrictive flexor retinaculum as the carpal sheath. and although "tarsal tunnel syndrome" is possible,it is poorly characterized (Van Pelt et a11969. Van Pelt 1969,

Indications for tarsal sheath tenoscopy include a chronic tenosynovitis that is poorly responsive to medical therapy.

These cases may be improved by debridement of massesand adhesions spanning from the tarsal sheath parietal lining to the DDFr. Severalother manifestations of chronic tenosynovitis may be tenoscopically debrided. including tears of the DDFT, mineralizing masses within the tarsal sheath. and mineralization of the surface and deeperstructures of the DDFT.Removal of fragmentation of the sustentaculum tali, and debridement and lavage of contaminated or infected tendon sheaths are also major indications for tenoscopy (MacDonald et al1989.

Welch et a11990. Santschi et al1997, Cauvin et al1999, Mcllwraith 2002b)

Surgical anatomy The structures and associationsof the tarsal sheath and the enclosedDDFTthroughout its coursearound the hock have beendescribed(Cauvin et al1999). The tarsal sheath commences6-7 cm proximal to the level of the medial malleolus, and extends approximatelyone fourth of the distance down the third metatarsus (Fig. 12.35). The enclosedDDFThas a continuous mesotenonattachmenton its caudo/plantaromedialmargin, which is relatively thin and contains obviousfine vasculature(seeFig. 12.35 and Fig.12.36). This can limit visualizationof caudaland caudolateral portions of the DDFT,dependingon the position of the arthroscopeaccessportal. The DDFTalso has several

small vinculae in the proximal recesses of the tarsal sheath (Cauvin et al 1999). As the DDFT approaches the sustentaculum, the tarsal sheath becomes narrowed by the flexor retinaculum forming the tarsal tunnel (Fig. 12.37).

The distal cul-de-sac of the tarsal sheath is narrow and slightly better defined on the plantar aspect of the DDFT. This cul-de-sac contains a synovial fold attached to the DDFT and the dorsomedial sheath wall, which forms a blind dorsomedial pouch (Fig. 12.38). The lateral extension of the tarsal sheath extends more distal than the medial terminal cul-de-sac, both of which can be viewed tenoscopically.The tendon of insertion of the medial digital flexor tendon (MDFT) (flexor digitorum longus), which has a separate tendon sheath, conjoins with the DDFT ilIimidiately distal to the termination of the tarsal sheath.

There are no major neurovascular structures within the tarsal sheath, but there are several neurovascular bundles associated with its outer fibrous layers that need to be recognized when making instrument portals. Proximally, the divided tibial nerve that has become the medial and lateral plantar nerves, the medial tarsal artery, and the recurrent tarsal vein are located in the caudomedial fibrous layers (see Fig. 12.36). The recurrent tarsal vein is in a more medial location, and is susceptibleto injury when making instrument portals. More distally, at the level of the sustentaculum tali, the medial and lateral plantar nerves, arteries, and veins are located caudally, deep in the fibrous layers of the tarsal sheath, but also within the confines of the tarsal flexor retinaculum (see Fig. 12.37). Distally, the chestnut overlies

Fig. 12.37 (A) Labeled diagram of B showing relevant structures in the cross-sectional specimen of the tarsal sheath at the level of the midsustentaculum tali. (B) Cross-sectional specimen of the sustentaculum level of the tarsal sheath.The sheath cavity contains red latex.

(C) Same cross section with DDFT retracted to show medial mesotenon attachment spanning from the DDFT to the tarsal sheath.

Long digital Dorsal metatarsalartery Lateral digital extensor tendon

Till

TIV

\\\ \

'\,,~\

Long plantar ~ ligament Lateral plantar a.,v.,n.

A

Chestnut Tarsal sheath cavity

the tarsal sheath medially, and has to be avoided. The lateral plantar neurovascular structures are positioned along the plantarolateral perimeter of the termination of the sheath and are relatively protected (Fig.12.38).

Tenoscopic techniques Diagnostic tenoscopy of the tarsal sheath Several approaches to the tarsal sheath have been described, but the preferred arthroscopic entry is a central medial portal made 1-2 cm proximal to the sustentaculum tali (Fig. 12.39).

This permits visualization of both proximal and distal regions of the sheath (Cauvin et aI1999). Examination and debridement of the visible portions of the DDFT and many areas of the sustentaculum tali can be performed using instrument portals directly over or immediately distal to the sustentaculum tali.

The central medial approach can be performed with the horse in dorsal or lateral recumbency with the limb extended.

Hemorrhage is slightly reduced by using dorsal recumbency. and a tourniquet is useful for hemorrhage control when using lateral recumbency, since the affected limb is down. The tarsal sheath is distended with saline if it is not already markedly enlarged. The voluminous outpouching of the proximomedial aspect of the tarsal sheath is readily palpated.

A skin incision is made in the distal region of this proximal outpouching. approximately level with the medial malleolus of the tibia. The arthroscope sleeveis inserted in a proximal direction to commence the examination in the proximal region of the tarsal sheath (Fig. 12.39). The mesotenon of the DDFT originates from the caudal/plantaromedial border of the DDFT and provides a barrier to complete examination of the caudal and medial portions of the tarsal sheath (Fig. 12.35). However,this layer is relatively thin. and can be

perforated in several areas if necessary, allowing the arthroscope to view the caudal portions of the proximal pouch of the tarsal sheath. A separate instrument entry, directly over lesions,is preferred for easeof triangulation. The dorsomedial or plantaromedial arthroscope entry incision into the sheath is positioned largely based on the location of the predominant lesions, dorsal or plantar, to the mesotenon.

With the arthroscope directed proximally, the DDFT and proximal reflection of the tarsal sheath are evident (Fig. 12.40). The mesotenon and medial and cranial/dorsal surfaces of the DDFTare readily examined. Redirection of the arthroscope more distally reveals the DDFT as it curves over the sustentaculum tali (Fig. 12.40). Limited portions of the fibrocartilage surface of the sustentaculum forming the support surface for the DDFT can also be examined. The DDFTcan be retracted after a local instrument portal is made, which improves access to the caudolateral surface of the sustentaculum (Fig. 12.40). The medial extremity of the sustentaculum is extrasynovial and cannot be viewed tenoscopically.lhis area is also the most frequent site for bony exostosis.and fragmentation, which may then have to be removed using open approaches. Over the sustentaculum the tarsal sheath is confined by the tarsal flexor retinaculum, which stabilizes the DDFT (Fig. 12.40). Redirection of the arthroscope allows the DDFTto be viewed as it curves distally (Fig. 12.41). When the arthroscope entry has been made dorsal to the mesotenon,the sustentaculum and dorsal surface of the DDFTare readily examined. Advancing the arthroscope further distally allows examination of the remainder of the sustentaculum and the DDFT as it courses toward the distal termination of the sheath. The medial mesotenon is thicker and somewhat compressed within the tarsal canal (Fig. 12.41), and to facilitate examination of the distal regions of the DDFT and sustentaculum, sequential entry both dorsal and plantar to the mesotenon allows complete assessmentof

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the DDFT surfaces and the weightbearing surfaces of the sustentaculum.

A distomedial approach to the tarsal sheath is less frequently necessary (Fig. 12.42). The retinaculum of the tarsal sheath is more dense distally, and the chestnut provides a problem for sterile skin preparation. However, examination of this area is occasionally necessary,and a skin incision can be made 1-2 cm proximal to the level of the chestnut over the medial aspect of the distended tarsal sheath (Fig. 12.42).

The DDFT can then be seen as it courses over the distal portions of the sustentaculum tali. Surgical procedures in the distal limits of the tarsal sheath are more difficult, due to the small volume of the tarsal sheath at this level and the overlying retinaculum. Additionally, the converging MDFT and check (accessory) ligament immediately distal to the tarsal sheath narrow the sheath as the distal limits are

approached.

i~ t"'\

Tenosynovial mass and adhesion resection ~ Ultrasonogr~phic evaluation of cases with chronic tarsal sheath distention frequently reveals tenosynovial masses within the sheath (Fig. 12.43). Further inflammation and advancing fibrosis of the tarsal sheath restrict the free range of motion of the DDFTwithin the tarsal sheath. Mineralization is a late complication of chronic disease, and can involve portions of the mesotenon as well as the surface layers of the DDFT(Fig. 12.44). Removal of most tenosynovial massescan be accomplished using the central medial approach to the tarsal sheath (Fig. 12.45). After a thorough examination, an 18-gauge 7.5 cm spinal needle is used to define the most appropriate portal for mass removal. The neurovascular structures caudal/plantar to the tarsal sheath can be avoided by penetration with arthroscope and instruments immediately adjacent to the cranial-caudal midline, allowing entry either

side of the mesotenon. This provides accessfor mass removal and debridement of the medial surfaces of the DDFT (Fig. 12.45). Massescan involve the inner layers of the tarsal sheath, or become more pendulous and float between the DDFT and the tarsal sheath lining (Fig. 12.46). With chronic disease, the tarsal sheath can become quite thick, and examination of the sheath contents can be slow and tedious.

High ingress fluid pressure frequently results in subcutaneous fluid accumulation, making the surgical exploration more difficult. A gradual increase in the areas available for examination can be accomplished using motorized resection of proliferative synovium. Masses can be removed with scissors and rongeurs, biopsy punch rongeurs, motorized resection (Fig. 12.47), or radiofrequency probes, depending on the density of the masses. Large masses and mineralized areas may need a second instrument portal to allow the mass to be stabilized prior to transection at its base. Mineralized masses generally result from dystrophic mineralization of chronic

lesions and are more common in the tarsal sheath than the equivalent syndromes in the carpal sheath. Radiographically evident mine~lization of the DDFT can be differentiated from mineralizatiqn in the mesotenon and sheath by comparing its position on extended and flexed radiographs. Motorized resection of massesand surface proliferation of the DDFT can be associated with hemorrhage. Tourniquet application proximal to the tarsal sheath may be helpful, but most hemorrhage is controlled by the pressure of the ingress fluid.

Distention with gas is an alternative if bleeding continues to hamper the diagnostic examination and further massremoval.

Mineralization can extend down to the terminal portions of the tarsal sheath, and a second arthroscope and/or instrument entry in the distal medial recess of the sheath may be required. After removal of masses,the sheath is flushed prior to routine skin closure. Intrathecal administration of NaHA may be helpful in reducing reformation of tendon sheath adhesions.

Debridement of the sustentaculumtali

Postoperative care

The sustentaculum tali is prone to trauma over its plantaromedial aspect, resulting in bone proliferation within or adjacent to the insertion of the retinaculum on the calcaneus.

Some wounds also cause contamination or infection of the tarsal sheath. The most medial areas of bone proliferation are beyond the medial extremity of the tarsal sheath. Resectionof accessibleproliferative bone, and debridement of the DDFTbearing surfaces of the sustentaculum, can be accomplished using the central medial arthroscope entry, with instrument portals made directly over the sustentaculum. Alternatively, and sometimes additionally, the distomedial portal (Figure 12.42), is required for arthroscope entry, to allow complete examination of the medial edges of the sustentaculum and the lateral perimeter of the tarsal tunnel as it curves proximally. Fragmented or infected foci in the sustentaculum can be removed and/or debrided using hand instruments.

Further details concerning the principles of treating contaminated or infected lesions are provided in Chapter 15.

Wound healing complications associated with tenoscopic evaluation of ;he tarsal sheath are generally minimal.

Exercise can b~ initiated 2-4 days after surgery, depending on the degree of lameness.Horses respond to tenoscopic surgery of the tarsal sheath differently, and some can be quite lame postoperatively.This can be controlled at the time of surgery by intrathecal deposition of bupivacaine at the time of closure, while postoperative pain relief is provided with nonsteroidal anti-inflammatory agents. More severe reactions to surgery or the primary disease can be treated using epidurally administered morphine and detomidine. Horses with disease processes involving the sustentaculum tali frequently also have damage to the dorsal surface of the DDFT, and are more lame than horses with tarsal sheath tenosynovitis.

Additionally, follow-up medication to the tarsal sheath is more likely to be necessary,and includes intrathecal NaHA and follow-up intravenous NaHA. Repeat ultrasonographic

examination is also useful in these cases to assessreturn of tenosynovial masses,and to evaluate tendon healing.

Results and prognosis There are few published case studies of tarsal sheath tenoscopy (Cauvin et aI1999). Contaminated and infected cases represent a large proportion of the tarsal sheaths requiring tenoscopy (MacDonald et al1989, Santschi et al 1997, Cauvin et al1999. McIlwraith 2002b). Their outcome is often improved by tenoscopic debridement and lavage, but osteomyelitis of the sustentaculum is considered a serious complication (MacDonald et al1989. Santschi et aI1997).

Non-infected tarsal sheath tenosynovitis can be improved by mass removal and synovectomy, depending on the extent of dystrophic mineralization.

Tenoscopy of the Extensor Tendon Sheaths Indications The extensor tendon sheaths are prone to injury due to their location on the dorsal aspect of the limb (Mason 1977, Platt & Wright 1997). Blunt trauma can result in variable degrees of tendonitis and chronic effusion of the sheath. A small number of these cases do not spontaneously resolve, but progress to develop intrathecal adhesions and soft tissue masses. This can involve the sheath of the extensor carpi radialis, the common digital extensor, or rarely the lateral digital extensor or extensor carpi obliquis in the forelimb. In the hind limb, the lateral digital extensor seemspredisposed to injury and chronic distention. The long digital extensor sheath can be distended; however, this sheath merges with that of the tibialis cranialis and the fascia of the dorsal aspect of the tarsus, and has little free spaceto distend with fluid or allow tenoscopic examination.

Extensor tendon fiber disruption varies from none to moderate (Fig. 12.48), and the most consistent features

include fibrous thickening of the sheath and secondary mass and adhesion formation. Ultrasonographic evaluation reveals areas of fibrinous and fibrous tissue deposition, considerable amounts of free fluid. and quite often relatively normal tendon fiber architecture (Fig. 12.49). Lameness is variable but restricted carpal flexion is common. In some cases tenoscopy is undertaken to improve the cosmetic appearance of the limb. The presence of infection usually results in more severe lameness. St~plechase horses are predisposed to thorn penetration of the forelimb extensor sheaths, which can lead to obvious lameness and the need for more aggressive surgical and medical therapy (Platt & Wright 1997).

Tenoscopic techniques Tenoscopy of the extensor sheaths can be done in lateral or dorsal recumbency. The arthroscope portal to the affected extensor sheath is generally made toward the proximal or distal extremity of the sheath, depending on ultrasonographic evidence of the more severely affected region, which is reserved for the instrument portal. Examination of the interior of the sheath often reveals adhesions and proliferative masses. Most masses are combinations of fluid pockets or

. organizing fibrinous deposits (Fig. 12.50). Instrument portals are made as necessaryto allow rongeur and motorized resector access for soft tissue debridement. The aims of debridement include removal of proliferative massesand re-establishment of free motion of the affected tendon. Synovectomy should be used judiciously in an attempt to reduce fluid accumulation in the sheath. After removal of synovial masses,the use of tie-down sutures can occasionally be employed to reduce dead space within the enlarged tendon sheaths (Fig. 12.51), although postoperative bandaging is considered more important. Cosmetic results can be difficult to achieve in chronically distended extensor sheaths, unless some attempt at reducing the extensor sheath volume is utilized. Synovectomy of the parietal surfaces of the extensor sheath and

pressure bandaging, occasionally with the use of splinting, can be effective in achieving cosmetic results. Occasionally, the use of cast-bandage combinations may also be necessary.

Use of tenoscopic approaches to close spontaneous or iatrogenic fistulae between the carpal joints and the common digital extensor tendon sheath or the tendon sheath of the extensor carpi radialis have been largely unsuccessful. A combination of arthroscopically assisted synovectomy and limited openapproachesfor suture are generallyrecommended for these fistulae.

Results of open treatment of chronic extensor sheath tenosynovitis are fair to good in the limited series of casesin the literature (Mason 1977, Platt & Wright 1997). In the authors' experience, tenoscopic treatment of the sheaths of

the extensor carpi radialis and common digital extensor. and the sheath of the lateral digital extensor of the hind limb. has allowed more aggressivedebridement with good resolution of lameness. Cosmetic appearance after debridement of most distended extensor sheaths can be substantially improved. although most have some residual fibrosis.

References Adams OR. Constriction of the palmar (volar) or plantar annular ligament of the felock in the horse. Vet Med/Small An Clin 1974; 69: 327-329.

Arniel D. Ishizue K, Billings E, et al. Hyaluronan in flexor tendon repair. J Hand Surg 1989; 14A: 837-843.

Barr ARS. Dyson SJ.Barr FJ,O'Brien JK. Tendonitis of the deepdigital flexor tendon in the distal metacarpal/metatarsal region associated with tenosynovitis of the digital sheath in the horse.

Equine VetJ 1995; 27: 348-355.

Cauvin ER, Tapprest J, Munroe GA, May SA, Schramme MC. Endoscopic examination of the tarsal sheath of the lateral digital flexor tendon in horses. Equine VetJ 1999; 31: 219-227.

Cauvin BRJ,Munroe GA, Boyd JS. Endoscopic examination of the carpal flexor tendon sheath in horses. Equine Vet J 1997; 29:

459-466.

Chow JC.Endoscopic release of the carpal ligament for carpal tunnel syndrome: long-term results using the Chow technique.

Arthroscopy 1999; 15: 417-421.

Chow JCY.Endoscopic release of the carpal ligament: a new technique for carpal tunnel syndrome. Arthroscopy 1989; 5: 19-24.

Dik KJ. Dyson SJ. Vail TB. Aseptic tenosynovitis of the digital flexor tendon sheath. fetlock and pastern annular ligament constriction. Vet Clin North Am Equine Pract 1995; 11: 151-162.

Dik KJ. Merkens HW. Unilateral distension of the tarsal sheath in the horse: a report of 11 cases.Equine Vet J 1987; 19: 307-313.

Dik KJ. Van Den Belt AJM. Keg PRoUltrasonographic evaluation of fetlock annular ligament constriction in the horse. Equine Vet J 1991; 23: 285-288.

Edwards GB. Changes in the sustentaculum tali associated with distension of t~ tarsal sheath (thoroughpin). Equine VetJ 1978; 10: 97-102. .

Fortier LA. Nixon AJ. Ducharme NG. Mohammed HO. Yeager A. Tenoscopic examination and proximal annular ligament desmotomy for treatment of equine "complex" digital sheath tenosynovitis. Vet Surg 1999; 28: 429-435.

Gaughan EM. Nixon AJ. Krook LP. et al. Effects of sodium hyaluronate on tendon healing and adhesion formation in horses. AmJ Vet Res 1991; 52: 764-773.

Gerring EL. Webbon PM. Fetlock annular ligament desmotomy: a report of 24 cases.Equine-Vet J 1984; 16: 113-116.

Hago BED.Plummer IM. Vaughan LC. Equine synovial tendon sheaths and bursae: an histological and scanning electron microscopical study. Equine VetJ 1999; 22: 264-272.

Held JP. Patton CS.Shires M. Solitary osteochondroma of the radius in three horses. J Am Vet Med Assoc 1988; 193: 563-564.

Kretzschmar BH. Desjardins MR. Clinical evaluation of 49 tenoscopically assisted superior check ligament desmotomies in

27 horses. Proc 47th Ann Conv Am Assoc Equine Pract 2001 47: 484-487.

MacDonald MH. Honnas CM. Meagher OM. Osteomyelitis of th, calcaneus in horses: 28 cases. J Am Vet Med Assoc 1989; 194

1317-1323.

Mcllwraith CW: Osteochondromas and physeal remnant spikes iI the carpal canal. Proc 12th Ann ACVS Symposium 2002a; 12

168-169.

Mcllwraith CW:Tenosynovitis; diseasesof joints. tendons. ligament and related structures. In: Stashak TS (ed.). Adams' lameness iI horses. Philadelphia: Lippincott. Williams & Williams; 2002b

630-633.

Malark JA. Nixon AJ. Skinner KL. Mohammed H. Characteristics a digital flexor tendon sheath fluid from clinically normal horses AmJ Vet Res 1991; 53: 1292-1294.

Mason TA. Chronic tenosynovitis of the extensor tendons anc tendon sheaths of the carpal region in the horse. Equine Vet 1977; 9: 186-188.

Moro-oka T. Miura H. Mawatari T. et al. Mixture of hyaluronic acu and phospholipid prevents adhesion formation on the injure! flexor tendon in rabbits. J Orthop Res2000; 18: 835-840.

Nixon AJ. Superficial flexor tendinitis. In: White NA. Moore IN (eds Current practice of equine surgery. Philadelphia: JB Lippincott 1990a: 441-448.

Nixon AJ. Annular ligament constriction. In: White NA. Moore Jr (eds). Current practice of equine surgery. Philadelphia: Jl Lippincott. 1990b: 435-440.

Nixon AJ. Endoscopy of the digital flexor tendon sheath in horses Vet Surg 1990c; 19: 266-271.

Nixon AJ. Arthroscopic surgery of the carpal and digital tendo! sheaths. Clin Techn Equine Pract 2002a; 1: 245-256.

Nixon AJ. Medical and surgical therapy for tendinitis. Proc ACV: Symposium 2002b; 12: 161-164.

Nixon AJ. Sams AE. Ducharme NG. Endoscopically assistedannula ligament release in horses. Vet Surg 1993; 22: 501-507.

Nixon AJ. Schachter BL. Pool RR. Exostosesof the caudal perimete of the radial physis as a cause of carpal synovial sheatl tenosynovitis and lameness in horses: 10 cases (1999-2003).

Am Vet Med Assoc 2004; 224: 264-270.

Platt D. Wright 1M. Chronic tenosynovitis of the carpal extenso tendon sheaths in 15 horses. Equine Vet J 1997; 29: 11-16.

Ragland WL III. Localized nodular tenosynovitis in the horse. Patho Vet 1968; 5: 436-441.

Redding WR. Ultrasonographic imaging of the structures of th, digital flexor tendon sheath. Comp Cont Educ 1991; 13

1824-1832.

Redding WR. Evaluation of the equine digital flexor tendon sheatl using diagnostic ultrasound and contrast radiography. Vet Radio illtrasound. 1993; 34: 42-48.

Santschi EM. Adams SB. Fessler JF. Widmer WR. Treatment a bacterial tarsal tenosynovitis and osteitis of the sustentaculun tali of the calcaneous in five horses. Equine Vet J 1997; 29 244-247.

Southwood 11. Stashak TS. Fehn JE. Ray C. Lateral approach fa endoscopic removal of solitary osteochondromas from the disu radial metaphysis in three horses. J Am Vet Med Assoc 199;

210: 1166-1168.

Southwood 11. Stashak TS. Kainer RA. Tenoscopic anatomy of th equine carpal flexor synovial sheath. Vet Surg 1998; 2; 150-157.

Southwood 11. Stashak TS. Kainer RA. Wrigley RH. Desmotomy < the accessory ligament of the superficial digital flexor tendon i the horse with use of a tenoscopic approach to the carpal sheatl VetSurg 1999; 28: 99-105.

Squire KR. Adams SB. Widmer WR. Coatney RW. Habig ( Arthroscopic removal of a palmar radial osteochondroma causin carpal canal syndrome in a horse. J Am Vet Med Assoc 199~ 201: 1216-1218.

Stanek C. Edinger H. Rontgendiagnostick bei der striktur de fesselringbandes bzw. durch das fesselringband beim pfer< pferdeheilkunde 1990; 6: 125-128. ter Braake F. Rijkenhuizen ABM. Endoscopic removal of oste< chondroma at the caudodistal aspect of the radius: an evaluatio in 4 cases.Equine Vet Educ 2001; 13: 90-93.

Textor JA. Nixon AJ. Fortier LA. Tenoscopic release of the equiD carpal canal. Vet Surg 2003; 32: 278-284.

Van Pelt RW. Inflammation of the tarsal synovial sheat (Thoroughpin) in horses. J Am Vet Med Assoc 1969; 15:

1481-1488.

Van Pelt RW. Riley WF. Jr. Tillotson PI. Tenosynovitis of the dee digital flexor tendon in horses. Can Vet J 1969; 10: 235-243.

Verschooten F. PicavetTM. Desmitis of the fetlock annular ligamer in the horse. Equine VetJ 1986; 18: 138-142.

Verschooten F. PicavetTM. Desmitis of the fetlock annular ligamer in the horse. Vet Ann 1988; 28: 98-101.

Watrous BJ. Dutra FR. Wagner PC. Schmotzer WB. Villonodula synovitis of the palmar and plantar digital flexor tendon sheath and the calcaneal bursa of the gastrocnemius tendon in th horse. Proc AAEP 1987; 33: 413-428.

Weiss C. Levy HI. Denlinger J. Suros JM. Weiss HE. The role of NE hylan in reducing postsurgical tendon adhesions. Bull Hosp Joir Dis Orthop Instit 1986; 46: 9-15.

Welch RD. Auer JA. Watkins JP. Baird AN. Surgical treatment < tarsal sheath effusion associated with an exostosis on the ca caneus of a horse. J Am Vet Med Assoc 1990; 196: 1992-1994 Wilderjans H. Boussauw B. Madder K. Simon O.Tenosynovitis of tb digital flexor tendon sheath and annular ligament constrictio syndrome caused by longitudinal tears in the deep digital flexc tendon: a clinical and surgical report of 17 cases in warmbloo horses. Equine VetJ 2003; 35: 270-275.

Wright 1M. McMahon PI. Tenosynovitis associated with longitudinl tears of the digital flexor tendons in horses: a report of 20 case: Equin~etJ 1999; 31: 12-18.

Introduction Bursoscopy is a term which has crept into common usage to describe intrathecal endoscopy of synovial bursae. These are closed sacs. found interposed between moving parts or at points of unusual pressure and may be congenital or acquired.

Congenital bursae develop before birth and are located in constant positions. They may be subfascial. subligamentous. submuscular. or subtendinous. The latter are most common and are found between tendons and bones at points where the tendon direction changes. The bursal side of the tendon and bone are fibrocartilaginous and in most circumstances the bursal margins are covered with villous synovium. In a classicalwork. translated by Ottaway & Worden(1940). Muller (1936) described 22 congenital subtendinous bursae in the horse. The principal congenital bursae of clinical importance (from an endoscopic perspective)are the calcaneal bursa. the intertubercular (bicipital) bursa. and the podotrochlear (navicular) bursa. Interestingly. techniques describing their endoscopic evaluation were all published within 2 months of each other by Ingle-Fehr & Baxter (1998). Adams & Turner (1999). and Wright et al (1999). respectively.

Acquired. also called reactive. functional. or pathological bursae. are formed after birth. They are most common over osseous prominences and may be subcutaneous. The most common etiology is synovial metaplasia within encapsulated seromas or hematomata. The most frequent sites of acquired bursae are subcutaneous or subfascial over the calcaneus and olecranon and either subcutaneously or between the extensor tendons and fibrous joint capsule of the metacarpophalangeal and metatarsophalangeal joints.

All bursae are amenable to evaluation with an arthroscope.

In man. techniques have been described for endoscopic treatment of the subacromial (Ellmann 1987). deep infrapatellar (Klein 1996). trochanteric (Bradley & Dillingham 1998) and retrocalcaneal (van Dijk et al 2001) bursae.

Techniques reported include ablation. removal of tendinous tears and mineralization. debridement of fibrocartilaginous and osseouslesions. and decompressionprocedures.including relief of impingement lesions. debridement of torn tissue. ligament resection. and synovectomy (Levy et al1991. Klein 1996. Bradley and Dillingham 1998. van Dijk et al 2001.

Suenaga et al 2002). Endoscopic resection of acquired olecranon and prepatellar bursae in man have also been described (Kerr & Carpenter 1990. Kaalund et al 1998.

Ogilvie-Harris & Gilbart 2000). All authors report improved

evaluation, reduced postoperative care, earlier return of mobility, reduced convalescenceand morbidity, and improved results compared with open surgical procedures,

Standard arthroscopic equipment is suitable for al~ bursal endoscopy and the usual principles of fluid distention with triangulation of arthroscope and instruments apply. In congenital bursae, portals are made abaxial to associated tendons. Corporate experience of bursal endoscopyis (as yet) limited, and thus understanding of bursal pathophysiology is in its infancy. It appears that bursae respond to aseptic insult in a manner similar to tendon sheaths but little is as yet known about healing of the fibrocartilaginous surfaces.

Endoscopy has resulted in identification of previously unreported lesions and it appears likely that the diagnostic and surgical advances that have followed arthroscopy and tenoscopy will also be enjoyed with bursoscopy.The response to open wounds and/or other introduction of contaminants is common to all synovial cavities. However, with establishment of infection, the response of congenital bursae has some features in common with tendon sheaths and some in common with diarthrodial joints.

Current indications for endoscopy of congenital bursae include lameness referable to the bursa, investigation of bursal distention, contamination and infection. Some cases will have radiologic and/or ultrasonographic changes, but there is invariably bursal distention. Lesions identified and treated endosc~ically include defects in the fibrocartilaginous surface of tendons and bones, osseous fractures, lesions of adja~ent ligaments, contamination, and infection.

The principal indications for endoscopy of acquired bursae are contamination and infection.

Calcaneal

Bursa

There are two congenital calcaneal bursae (Fig. 13.1). The largest has as its plantar margin the superficial digital flexor (sdf) tendon and. dorsally, is bordered by the tendon of insertion of gastrocnemius,the calcaneus,and the long plantar ligament (Fig. 13.2). A smaller bursa, which is sometimes conjoined, lies between the tendon of insertion of gastrocnemius and the calcaneus (Fig. 13.3).

Technique Endoscopy of the calcaneal bursa may be performed with a horse in lateral or dorsal recumbency. with the limb in an extended position. The technique described by Ingle-Fehr & Baxter (1998) is appropriate for the majority of circumstances (Fig. 13.4). Following standard preparation of the site. if the bursa is not distended markedly then it is inflated further. A 1.1 x 40 mm (19-gauge x 1.5 inch) needle is inserted between the sdf tendon and the plantar ligament distal to the medial or lateral retinacular insertion of the former and the bursa is distended maximally (Fig. 13.5A). A skin portal is created approximately 10 mm distal to the retinaculum, medially or laterally. and this is extended with a No. 11 or 15 blade through to the bursa. The arthroscopic sleeve with a conical or blunt obturator is then inserted and directed proximally, initially between the sdf tendon and long plantar ligament. and then plantar to the calcaneus and gastrocnemius to the proximal limit of the bursa (Fig. 13.5B).

This approach permits thorough examination of evaluationrequires rotation of the arthroscopein order utilize its lens angle effectively.Instrument portals created at appropriatelocations. as determined by the retinacular insertions of the sdf tendon and may ipsilateral or contralateral to the arthroscope.

Endoscopic anatomy Proximally, the bursa contains villous synovium. Almost circumferential evaluation of the tendon of insertion of gastrocnemius is possible (Fig. 13.6). It is at this site that there may be communication with the underlying bursa between the tendon of insertion of gastrocnemius and the calcaneus and, if present, this is usually identifiable.

Proximally, the sdf tendon may exhibit some evidence of longitudinal fiber orientation and proximal to the calcaneal tuber there are sometimes visible shallow transverse lines or

far as the retinacular insertions of the sdf tendon.

With further (distal) withdrawal of the arthroscope, plantar ligament emerges from the fibrocartilage of calcaneal tuber. As this courses distally, it ligamentous form (Fig. that the camera

distal recessof the bursa, the arthroscopemay be Villous synovium covers the capsular reflection from plantar ligament to the dorsal surface of the sdf tendon. where there may once again be discernible ligamentous form.

Clinical application Lesions identified and treated endoscopically include osteolytic lesions in the calcaneal tuber. tearing of the retinacular insertionsof the sdf tendon.tendonitisof the sdf tendon.traumatic fragmentationof the calcaneus,contamination through openwounds,and puncturesand infection. ridgesin its dorsalsurface:asthe sdf tendonapproachesthe calcaneusand becomeswider in a mediolateralplane.these are replaced by an amorphous fibrocartilaginous surface (Fig. 13.7). However.obliquelyangledfibresare identifiable. extending mediallyand laterally from the sdf tendonto the abaxial margins of the calcaneus:theseare the medial and lateral retinacular insertions of the sdf tendon (Fig. 13.8).

Fibrocartilagealsocoversthe apexof the calcanealtuberand

Osteolytic lesions of the calcaneal tuber Regions of osteolysis in the calcaneal tuber have been reported by Ingle-Fehr & Baxter (1998) and Bassage et al (2000). Affected animals present with distention of the calcaneal bursa and lameness that is responsiveto intrathecal local analgesia. Radiographs demonstrate radiolucencies in

the proximal plantar margin and/or apex of the calcaneal tuber (Fig. 13.10). Ultrasonography confirms distention of the calcaneal bursa and may also reveal disruption of the proximal plantar margin of the calcaneus and irregular echogenicity of the adjacent insertion of gastrocnemius. At endoscopy,there may be discoloration of the calcaneal fibrocartilage with soft, crumbling, and apparently degeneratebone exposedby use of a blunt probe. Removal of the degenerate bone and debridement has resulted in return to soundness but the number of cases is small and thus confident prognostication is difficult.

The etiology of such lesions is unknown. Previous authors have tentatively suggestedthat these may be avulsion injuries of the plantar ligament (Ingle-Fehr & Baxter 1998), or of gastrocnemius (Bassage et aI2000).

Tearing of the retinacular insertions of the superficial digital flexor tendon Tearing of the medial (most commonly) or lateral retinacular insertions of the sdf tendon has been associated with contralateral luxation or subluxation of the tendon from the apex of the calcaneal tuber (Sullins 2002). Partial tears of the retinaculi have beenidentified on endoscopic examination of the calcaneal bursa in animals with lameness, which localizes to a distended calcaneal bursa. A tentative diagnosis may be obtained ultrasonographically, but a definitive diagnosis is obtained endoscopically. In acute lesions there

may be hemorrhage at the site but torn fibrils are discernible (Fig. 13.11). Tearing and herniation of disrupted tendon fibrils is generally more obvious in long-standing cases (Fig. 13.12A). Removal of torn fibrils and debridement of the parent tendon is performed with a motorized synovial resector (Fig. 13.12B). Casestreated in this manner have returned to soundness.

Traumatic fragmentation of the calcaneus E.xternal trauma, usually as a result of falls or kicks from other horses, ~ay result in intrathecal fragmentation of the calcaneal tuber. These may be open or closed. Most fractures are identified radiographically and, when the apex of the calcaneus is involved. flexed plantaroproximal-plantarodistal oblique (skyline) projections are most useful.

Endoscopyshould be performed with ipsilateral arthroscope and instrument portals. When accompanied by wounds, the surgeon should look diligently for the presence of hair and foreign material. Fragments are removed with appropriately sized arthroscopic rongeurs and the fracture bed debrided with curettes. In some instances foreign material may be embeddedin bone. Lesions should be debrided using the same principles as applied with osteochondral fragmentation in diarthrodial joints but fibrocartilagenous margins always appear less sharply demarcated than their hyaline counterparts (seeFig. 14.9).

capsules and an intervening fat pad. '

I ntertubercular Bursa

(Bicipital)

The intertubercular bursa is found between the tendon of origin of biceps brachii and the cranial margin of the humerus (Fig. 13.13). The bursa envelops the medial and lateral margins of the tendon, and proximal to the humerus is separated from the scapulohumeral joint by their fibrous

the humerus bears three tubercles: lateral (lesser),and ~ intermediate tuberosity (tubercle). The overlying tendon is bilobed and indented markedly by the intermediate tuberosity. The medial lobe is slightly larger than its lateral counterpart. A tendinous band envelops the tendon and bursa in the region of the humeral tuberosities. Over the humeral tuberosities the biceps tendon is partly cartilaginous and presents a smooth fibrocartilaginous bursal surface. The musculotendinous junction of biceps brachii lies in the distal portion of the bursa. which terminates just proximal to the deltoid tuberosity of the humerus.

Technique Endoscopyis performed with the horse in lateral recumbency, with the affected limb uppermost and positioned parallel to

Fig. 13.14 Horse positioned for endoscopy of the left bicipital bursa.

the ground (Fig. 13.14). In the majority of circumstances a distal arthroscopic portal. as described by Adams & Turner (1999) (Fig. 13.15), is most suitable but occasionally there are advantages to a proximal arthroscopic portal. Generally, pathologic bursae are distended and there is no advantage to further distention. A skin portal is made using a No. 11 or 15 blade over the craniolateral margin of the humerus 2-3 cm proximal to the deltoid tuberosity. Using a conical obtur~tor the arthroscopic cannula is directed axially and proximally through the brachiocephalicus muscle and between the cranial margin of the humerus and the tendon of origin of biceps brachii. Entry of the bursa is usually accompanied by flow of synovial fluid from the cannula. and this is advanced proximally before the arthroscope is inserted (Fig. 13.16A and B). Instrument and/or additional arthroscopic portals may be made proximal to the lateral tuberosity of the humerus utilizing a percutaneous 1.2 x 90 mm (18 g x 3.5 inch) needle as a guide (Fig. 13 .16C). If necessary.arthroscopy and instrument portals can be interchanged (Fig. 13 .16D). At the end of the diagnostic and surgical procedures the skin portals may be closed in a routine manner and the wounds protected by oversewing swabs or gauze pads as stent bandages.

Endoscopic

anatomy

Proximal to the humeral tuberosities the bursal synovium is villous and covers the supraglenoid tuberosity of the scapula, the origin of biceps brachii, and the voluminous bursal recess cranial to the scapulohumeral joint. At this level, the proximal portion of the biceps brachii tendon has visible fiber orientation (Fig. 13.17). Withdrawing the arthroscope provides visualization of the lateral tuberosity and abaxial side of the intermediate tuberosity of the humerus. These and the overlying biceps brachii tendon are covered with smooth fibrocartilage

Fig. 13.15 Distal endoscopic approach to the bicipital bursa; D = deltoid tuberosity of humerus; B = tendon of origin of biceps brachii; S = supraglenoid tubercle of the scapula; J = scapulohumeral

joint.

(Fig. 13.18). The tight interdigitation of the tendon and the cranial surface of the humerus precludes evaluation of the medial tubercle and axial side of the intermediate tubercle of the humerus from this arthroscopic position. Abaxial to the lateral margin of the lateral tubercle of the humerus there is a cover of fine synovial villi through which tendinous bands from pectoralis ascendens are seen perpendicular and attaching to the lateral tuberosity. With further withdrawal of the arthroscope. a synovial plica is visible at the lateral margin of the intertubercular groove (Fig. 13.19). At this level the arthroscope can be insinuated between the biceps brachii tendon and fibrocartilagenous surface of the humerus as far axial only as the intermediate tubercle (Fig. 13.20).

Approaching its distal margin the fibrocartilage is slightly irregular (Fig. 13.21). Beyond this point the cranial surface of the humerus and biceps brachii tendon and musculotendinous junction are covered by villous synovium (Fig. 13.22).

In the distal recess it is possible to visualize also a small area of the fibrocartilage medial to the intermediate tubercle (Fig. 13.22) and to push the arthroscope axially to obtain limited visualization of the distal medial lobe of the tendon. Utilizing a proximolateral arthroscopic portal. the most proximal margin of the intermediate tubercle and a small portion of the medial lobe of the tendon can be visualized (Fig. 13.23).

Clinical application Endoscopy of the bicipital bursa has been used in the investigation of lameness referable to this site and to treat

intrathecal fragmentation of the supraglenoid tubercle of the scapula and lateral tuberosity of the humerus together with contaminated and infected bursae.

Traumatic bicipital bursitis Booth (1999) reported a horse with lameness.localizingto the bicipital bursa. that was accompaniedby radiologicand ultrasonographicabnormalities. Endoscopyrevealedwidespread loss of fibrocartilage from the humerus. with

adhesions to the bicipital tendon. The extensive nature of the lesions precluded treatment but endoscopy was considered diagnostically useful. The authors have seenloss of humeral fibrocartilage with fibrillation of the adjacent bicipital tendon (Fig. 13.24) and rupture of the lateral wall of the bursa in

,

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horseswith lamenesslocalizingto this site.Thesecaseshave beentreated endoscopicallyby debridementof torn and/or detachedtissue.

Fragmentation of the supraglenoid tubercle and lateral tuberosity of the humerus ii:1 '\

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Contamination and infection Endoscopic evaluation and treatment of an infected bursa has been described by Tudor et al (1998). The authors have endoscopically managed contaminated and infected bicipital bursae (seeFig. 14.5), including cases with infected osteitis/ osteomyelitis of the humeral tuberosities. The use of proximal and distal arthroscopeand instrument portals is recommended.

Treatment follows the principles detailed in Chapter 14.

Podotrochlear Bursa

If

I

Most fractures of the supraglenoid tubercle of the scapula produce large fragments that involve the articular surface and approximate to the physealline. However, occasionally, smaller more proximal fragments can displace distally and are intrathecal with respectto bicipital bursa. Such fractures can be visualized, removed. and associated tissues debrided endoscopically.

Intrathecal fragmentation of the lateral tuberosity of the humerus is most commonly associated with penetrating wounds. Radiologic signs can be subtle but frequently are highlighted by craniomedial-caudolateral oblique projections. llitrasonography may also image fragmentation at this site.

This may be removed and the fracture bed debrided utilizing the arthroscope and instrument portals described above.

~

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(Navicular)

The dorsal margins of the navicular bursa are, from distal to proximal, the impar ligament, the palmar/plantar surface of the navicular bone, the navicular suspensory ligaments, and the intervening T ligament. The latter is thin and consists of little more than the fibrous capsules of the distal interphalangeal joint, digital flexor tendon sheath, and navicular bursa. The dorsal surface of the deep digital flexor (ddf) tendon forms the palmar/plantar margin of the bursa.

Technique Endoscopic evaluation of the navicular bursa is performed with the distal limb joints in a slightly flexed position. The horse may be in either dorsal or lateral recumbency. Dorsal recumbency facilitates triangulation and use of medial and lateral arthroscope and instrument portals. whereas lateral recumbency is favored for investigation and treatment of solar penetrations. The technique described originally by Wright et al (1999). and subsequently by Cruz et al (2001)

~ and Rossignol & Perrin (2003), permits the most comprehensive evaluation of the bursa. A 5-mm skin incision is made proximal to the collateral cartilage on the abaxial margin of the ddf tendon, palmar/plantar to the digital neurovascular bundle. The arthroscope cannula with a conical obturator is then introduced through the skin wound and advanced distally and axially, dorsal to the ddf tendon to enter the bursa at approximately the midpoint of the middle phalanx (Fig. 13.25). As the bursa is entered, there is usually a loss of resistance to advancement of the cannula and the obturator is then withdrawn and replaced by the arthroscope.

An instrument portal can be created using a similar technique on the contralateral side of the limb following a

trajectory established by prior insertion of a 1.2 x 90-mm (18 g x 3.5-inch) stiletted needle.

Using the above technique, the trajectory of the arthroscopic cannula is proximodorsal to distopalmar/plantar. If the trajectory is too dorsal, then it is likely that the arthroscopic sleeve will pass through the T ligament and into the palmar/plantar compartment of the distal interphalangeal joint. In such circumstances, the sleeveshould be withdrawn and realigned to a more palmar/plantar direction before it is advanced again distally. This approach to the navicular bursa may also result in penetration of the digital flexor tendon sheath. In this event the arthroscope may be positioned dorsal to the ddf tendon at the distal reflection of the sheath wall before the arthroscope is withdrawn and replaced once again with a conical obturator. Advancement of the cannula in the trajectory described above along the dorsal surface of the ddf tendon, will usually result in successfulentry into the navicular bursa. It is also possible to enter the digital flexor tendon sheath, electively pass the arthroscope distally dorsal to the ddf tendon and, then, use cutting instruments to create portals on the dorsal and palmar/plantar sides of the T ligament into the distal interphalangeal joint and navicular bursa, respectively (Fig. 13.26).

Endoscopic

anatomy

Evaluation of the bursa usually commences distally. Here. villous synovium reflects off the ddf tendon and impar

ligament (Fig. 13.27). A slight withdrawal of the arthroscope will allow evaluation of the sagittal ridge of the navicular bone and the adjacent surface of the ddf tendon. The palmar/plantar surface of the navicular bone is covered by relatively homogeneous fibrocartilage. although in some animals there is a shallow indentation (sometimes termed a synovial fossa) in the sagittal ridge where the overlying fibrocartilage is thinner. The dorsal surface of the ddf tendon is indented to varying degrees for the sagittal ridge of the navicular bone (Fig. 13.28). In someanimals the dorsal surface of the ddf tendon presents a relatively homogeneous surface, whereas in others there is evidence of a longitudinally oriented fiber pattern. Movement of the arthroscope medially and laterally peRmitsevaluation of the abaxial margins of the bursa. This is ~nerally easieston the side contralateral to the arthroscope but with rotation of the lens can be achieved also on the ipsilateral side. At the margins there are plical reflections between the ddf tendon and the abaxial margins of the navicular bone (Fig. 13.29). If the arthroscope is then returned to an axial position and withdrawn slightly further, this will visualize the proximal margin of the navicular bone and reflection of the T ligament from this site (Fig. 13.30).

Abaxially, this thickens to blend imperceptibly into the insertions of the suspensory ligaments of the navicular bone. Further proximally, the bursal reflection from the ddf tendon, suspensory, and T ligaments is covered by villous synovium (see Fig. 13.30). Proximal to the navicular bone. the dorsal surface of the dill tendon has a recognizable fiber pattern.

date.thereareinadequatenumbersto assess the potential for endoscopicsurgeryto enhancecasemanagement.

Penetrating injuries of the navicular bursa The management principles for contamination and infection of the navicular bursa are similar to those of other synovial cavities and are dealt with in Chapter 14. However, at this site there are a number of features that merit special attention.

The navicular bursa may be punctured by penetrating wounds in the palmar/plantar one-half of the solar surface of the foot. The risk and site of penetration are determined by the length of the penetrating object and its trajectory. In order to reach the navicular bursa, there must be a penetrating wound in the~ddf tendon and, in some circumstances, perforating objfcts may continue also proximally through the T ligament and into the digital flexor tendon sheath or, more commonly, distally through the impar ligament and into the distal interphalangeal joint.

The bursa is evaluated utilizing an arthroscopic portal, as described above (Wright et al1999). In acute casesthere will usually be drainage of fluid from the puncture as soon as the application bursa is inflated (Fig. 13.31). Thorough evaluation of the bursa should be performed in all cases to include identification of Currently, the principal indication for endoscopy of thenavicular the puncture wound (Fig. 13.32) and detection of foreign bursa is evaluation and treatment of contaminationand material (Fig. 13.33). Penetrating objects may also produce infection resulting from penetrating wounds. The defects in the navicular fibrocartilage and/or underlying contribution of the technique to the evaluation of lamenesslocalizing palmar/plantar subchondral bone. Instruments are generally to this site has yet to be evaluated. Intrathecallesions introduced through the penetrating wound (Fig. 13.34). have been identified, removed, and debrided but, to From this site, removal of foreign material and pannus and

Clinical

debridement of contaminated and infected tissues may

The ddf tendonis debridedby rotating a motorizedsynovial resectoraround its circumference.

be evaluated and treated by redirecting the cannula with c

approachedin a conventionalmanner.

At the end of the procedures, arthroscopic

instrument skin portals are closedroutinely. Unless undermining of laminar tissues, solar wounds dressing.

The resu~ of 10 of 16 (Wright et al1999) and 15 of 27 (Wright 20P2) animals being sound and returning to their pre-injury useis significantlybetter than with opensurgical techniques (Richardsonet al 1986, Steckel et al 1989, Honnaset al199 5). Thereis also greaterpain relief,reduced postoperativenursing and medicalrequirementsand fewer complicationswith endoscopictreatment.

Diagnostic endoscopy Endoscopy of the navicular bursa may provide useful information in the evaluation of lameness localizing to this area but, as yet, its use has been limited. Lesions identified have included fragmentation of the distal margin of the bone (Fig. 13.35), tearing of the impar ligament (Dyson 2002) and

ddf tendon (Fig. 13.36), and disruptionof the fibrocartilage of the bone and ddf tendon (Fig. 13.37). However,the number of diagnosticexaminationsperformedis small and clinically correlativestudiesare lacking.

References AdamsMN. Turner TA. Endoscopyof the intertubercular bursa in horses.J Am VetMedAssoc1999; 214: 221-225.

BassageIJI ll. Garcia-Lopez J. Gurrid EM. Osteolyticlesionsof the tuber calcaneiin two horses.J Am VetMed Assoc2000; 217: 710-716.

BoothTM. Lamenessassociatedwith the bicipitalbursa in an Arab stallion. VetRec1999; 145: 194-198.

BradleyDM. DillinghamMF. Bursoscopyof the trochantericbursa.

Arthroscopy1998; 14: 884-887.

CruzAM. Pharr JW. BaileyJV.BarberSM. FretzPB. Podotrochlear bursa endoscopyin the horse:a cadaverstudy. VetSurg 2001; 30: 539-545.

DysonSf. In: Diagnosisand managementof lamenessin the horse.

RossMW and DysonSJ(eds).Philadelphia:WBSaunders;2002: 286-299.

Ellmann H. Arthroscopic subacromialdecompression:analysis of one to three yearresults.Arthroscopy1987; 3: 173-181.

Honnas CM. CrabillMR. MackieJT.YarbroughTB. SchumacherJ. Use of autogenouscancellousbone grafting in the treatmentof septic navicular bursitis and distal sesamoidosteomyelitisin horses.J Am VetMedAss1995; 206: 1191-1194.

Ingie-FehrIE. Baxter GM. Endoscopyof the calcanealbursa in horses.VetSurg 1998; 27: 561-567.

Kaalund S. BreddamM. KristensenG. Endoscopicresectionof the septicprepatellarbursa. Arthroscopy1998; 14: 757-758.

Kerr DR. Carpenter CW: Arthroscopic resection of olecranon and prepatellar bursae. Arthroscopy 1990; 6: 86-88.

Klein WK. Endoscopy of the deep infrapatellar bursa. Arthroscopy 1996; 12: 127-131. wvy HI. Gardner.Lenmak 1J.Arthroscopic subacromial decompression in the treatment of full-thickness rotator cuff tears. Arthroscopy 1991; 7: 8-13.

Muller F .ScWeimbeutel und Sebnenscheidendes Pferdes. Arch wiss pracktTierheiIk 1936; 70: 351-370.

~ Ogilvie-Harris

DJ, Gilbart M. Endoscopic bursal resection: Tl

olecranon bursa and prepatellar bursa. Arthroscopy 2000; 1

249-253.

Ottaway CW, Worden AN. Bursae and tendon sheaths of the hor~ Vet Rec 1940; 52: 477-483.

Richardson GL, O'Brien TR, Pascoe JR, Meagher DM. Punctu wounds of the navicular bursa in 38 horses: a retrospective stuc VetSurg 1986; 15: 156-160.

Rossignol F, Perrin R. Tenoscopy of the navicular bursa: endosco!; approach and anatomy. J Equine Vet Sci 2003; 23: 258-265.

Steckel RR, FesslerIF, Huston LC. Deep puncture wounds of tI equine hoof: a review of 50 cases.Proc Am Assoc Equine Pra 1989; 35: 167.

Suenaga N, Minami A, Kimitaka F, Kaneda K. The correlatu betweenbursoscopic and histologic findings of the acromion und

surface in patients with subacromial impingement syndrom Arthroscopy 2002; 18: 16-20.

Sullins KE. In: Stashak TS (ed.),Adams'lameness in horses, 5th ed Philadelphia: Lippincott, Williams & Wilkins 2002: 974-976.

Tudor RA, Bowman KF, Redding WR, Tomlinson JC. EndoscoJ; treatment of suspected infectious intertubercular bursitis in horse. J Am VetMed Assoc 1998; 213: 1584-1585. van Dijk CN, van Dyk GE , Scholten PE, Karte NP. EndoscOJ; calcaneoplasty AmJ Sports Med 2001; 29: 185-189.

Wright IM, Phillips TJ, Walmsley JP. Endoscopy of the navicul bursa: a new technique for the treatment of contaminated aJ septic bursae. Equine Vet 1999; 31: 5-11.

Wright IM. Endoscopy in the management of puncture wounds the foot. Proc Eur Coli Vet Surg 2002; 11: 107-108.

Introduction Diarthrodial joints, tendon sheaths, and bursae are closed spaces with a similar mesenchymal synovial lining that produces and maintains a selective physical, cellular, and biochemical environment. The principles of synovial contamination and infection are similar for each of these cavities.

Contamination results from the introduction of microorganisms and can occur through openwounds or self-sealing punctures, by hematogenous spread, local extension of a perisynovial infection, or iatrogenically. Open wounds and self-sealing punctures may also introduce foreign material.

Infection follows when the microorganisms reproduce and colonize the synovial cavity. The principal potentiating factors for establishing infection are considered to be the presence of foreign material and/or devitalized tissue, the nature and number of contaminating organisms, and immunologic compromise, particularly in young animals.

Following colonization of the synovium, a combination of bacterial pathogenicity and host-immune response lead to the release of a variety of enzymes and free radicals, which result in massive inflammation and ultimately destruction of the tissues in the synovial cavity. The acute inflammatory response following inoculation of microorganisms is characterized by a rapid influx of inflammatory cells, predominately neutrophils (Bertone & Mcllwraith 1987). A plethora of destructive enzymes have been detected in synovial fluid from infected joints, including collagenase, caseinase, lysozyme, elastase,cathepsin G, and gelatinase (Palmer & Bertone 1994, Spiers et al 1994). These appear to originate both from invading neutrophils and activated synoviocytes. Together with other inflammatory mediators, such as eicosanoids, interleukins, and tumor necrosis factor (Bertone et al1993) and the disturbed synovial environment in joints, these trigger production of degradative enzymes by chondrocytes (such as stromelysin, aggrecanase,collagenase,and gelatinase).

There also is reduced proteoglycan synthesis (Palmer & Bertone 1994).

Established infection frequently results in the production of an intrasynovial fibrinocellular conglomerate (pannus).

This may cover foreign material and devitalized tissue. and act as a nidus for bacterial multiplication; it is rich in inflammatory cells. degradative enzymes and radicals. It is also a barrier to synovial membrane diffusion. thus compromising further intrasynovial nutrition and limiting access for circulating antimicrobial drugs. The quantity and nature of pannus appears to be dependent on the type and number of infecting organisms. and its production is also enhanced by the presence of foreign material. Its presence has been associatedwith increasing duration of clinical signs. presence of osteochondral lesions. and presence of osteomyelitis (Wright et aI2003).

The objectives in treating contamination and infection are similar for all synovial structures: removal of foreign material. debridement of contaminated/infected and devitalized tissue. elimination of microorganisms.removal of destructiveenzymes and radicals. promotion of tissue healing. and restoration of a normal synovial environment. A number of techniques have been described which include use of drains Gackman et al 1989). through and through lavage (Koch 1979). open surgery (Rose& Love 1979. Honnas et al1991a. Bertone et al1992.

Schneider et,.al 1992a. Baxter 1996). and endoscopy (Mcllwraith ],983. Bertone et a11992. Wright et al1999.

2003. Frees et al 2002). Variations of these techniques have also been described. These include open surgery followed by insertion of closed suction (Mcllwraith 1983) or open passive (Santschi et a11997) drains or by open drainage (Bertone et al 1992. Schneider et al 1992a) and endoscopy followed by closed suction drainage (Rosset al1991. LaPointe etal1992). fenestrated drains (Honnas et al1991b). or creation of an open draining wound (Bertone 1999).

In treating joint infection in man. arthroscopy is consideredto offer severaladvantagesover lavage and arthrotomy. including improved visualization. identification of foreign material and infected or devitalized tissue. and access to a larger area of synovial surfaces(Dory & Wantelet 1985. Jackson 1985. Parisien & Shaffer 1990). Arthroscopy is reported to

ensure an efficiently evaluated, cleaned, debrided, decompressed joint with minimal morbidity, to other treatments Garrett et al1981, Ivey & Clark 1985, & Shaffer 1990, Bussiere & Beaufils 1999, Stutz et al2000, Wirtz et a12001. Vispo Seara et aI2002).

Four stages of joint infection have been reported in man (Gachter 1985. cited by Stutz et aI2000): .Stage I: turbid fluid, hyperemic synovium, possible petechial bleeding, no radiologic changes. .Stage II: severe inflammation. fibrinous deposition, purulent fluid, no radiologic changes. .Stage III: thickening of the synovial membrane. villous adhesions and compartment formation, no radiologic changes. .Stage IV: aggressive pannus with infiltration of the cartilage, possibly undermined cartilage. radiologic signs of subchondral osteolysis, possible osseous erosions. and cysts.

These stages are related to but do not follow precisely temporal categorization. Vispo Seara et al (2002) adopted this classification and recommended the following arthroscopic treatment protocols for each category: .Stage I: thorough irrigation of all joint compartments. .Stage II: removal of fibrin and clots. sometimes also with a limited synovectomy followed by I (above). .Stage III: as II, but with resection of adhesions and subtotal synovectomy. .Stage IV: as above. but including removal of detached cartilage and debridement of osseouslesions.

Stutz et al (2000) and Vispo Seara et al (2002) also reported correlation between the stage of the disease process. prognosis, and the number of arthroscopic procedures required. Like all attempts to categorize clinical disease,this classification suffers from oversimplification. Nonetheless, it provides a useful comparative guide.

Evaluation Most contaminated and infected synovial cavities are amenable to endoscopic evaluation and surgery. Occasionally, there will be sufficient capsular disruption to preclude inflation but in some individuals, even if there is marked tissue loss on one aspect of the limb, other synovial compartments may be treated endoscopically.The absenceof adequate synovial space precludes the use of endoscopy in few sites, the most frequently affected examples being the centrodistal (distal intertarsal) and tarsometatarsal joints.

Endoscopyis performed under general anesthesia and the patient should be positioned to permit all-round accessto the affected synovial cavity(ies). Esmarch bandages and tourniquets are recommended for distal limbs. Generally,there is

than in other endoscopic procedures and control of ] rhage improves the efficiency of the procedures significantly.

In most cases. made utilizing standard endoscopic portals as described in preceding chapters. It is important in all circumstances to evaluate fully each structure and thus to use all available portals. examining dorsal and palmar/plantar or cranial and caudal compartments. and also, whenever appropriate, evaluating each cavity from both medial and lateral sides.If a tourniquet is used,the surgeon should take particular care in the creation of portals (especially into the digital flexor tendon she~h), as neurovascular bundles are less readily appreciated,and iatrogenic damage is possible.

An initial lavage of the cavity is usually necessaryin order to clear discolored synovial fluid. A thorough systematic evaluation should follow, examining the whole intrasynovial environment and. in turn, all of the contained structures.

Particular attention should be paid to the vicinity of wounds (Fig. 14.1).

Acute synovial infection is characterized endoscopically by severesynovitis (Fig. 14.2). In the absenceof osteochondral defects. chronic joint infection is characterized by cartilage degeneration (Fig. 14.3). but if subchondral bone is breached then infected osteitis/osteomyelitis may result. If the epitenon is intact. chronic tenosynovitis is characterized by synovial proliferation and adhesion formation (Fig. 14.4). whereas if it is disrupted there is usually rapid intratendinous collagenolysis.

coveravillous synoviumand in someadvancedcasesit also coversarticular cartilageand tendonsurfaces.

Foreign material In the presence of open wounds or self-sealing punctures, the surgeon should be aware of the potential presence of foreign material within the synovial cavity. Frees et al (2002) found intrasynovial foreign material in 4/20 (20%) of tenoscopically investigated wounds involving the digital flexor tendon sheath, whereas Wright et al (2003) documented foreign material in 41 of 95 (43%) horses with wounds or punctures into synovial cavities which were investigated endoscopically.

In the latter series, foreign material was predicted preoperatively in only 15% of animals (Fig. 14.7). The majority are free floating but the foreign material may also be adherent to pannus or synovium, embeddedin osteochondral lesions or foun~in penetrating soft tissues.The most common contaminantsure hair and wood (Fig. 14.8A). An association has been demonstrated in man between the presence of foreign material and the development of infected synovitis following penetrating wounds (Reginato et alI990). Foreign material acts as a nidus for infection and causesphysical and biochemical irritation within the synovial environment.

Large pieces may be removed with Ferris-Smith rongeurs (Fig. 14.8B), small pieces by a motorized synovial resector, and if embeddedin bone, curettes may be necessary.

The features of chronic infective bursitis are similar to both infected arthritis and tenosynovitis (Fig. 14.5).

Pannus is usually identified first over areas of villous synovium and, as it increases in mass, villi become obscured (Fig. 14.6) If the infective process continues, pannus will also

Debridement In the seriesreportedby Wrightet al (2003),51 of 121 (42%) horseshad endoscopicallyidentifiableosseousor chondral

~

lesions, of which only 25 (49%) were predicted before endoscopy. Fragmentation may be removed with rongeurs.

Foreign material may be embedded in the fracture bed (Fig. 14.9) and debridement of contaminated or infected fracture sites is invariably appropriate. Foci of osteitis/ osteomyelitisare generallydebulked with rongeurs (Fig. 14.10) before debridement with curettes. Motorized burrs are rarely indicated. When debriding chondral or osteochondral defects in bursae, the surgeon should be cognizant that fibrocartilagenous m~ins will invariably be less well defined than their hyaline co1interparts in diarthrodial joints.

Penetrating wounds and punctures of tendon sheaths and bursae may result in defects in the associated tendons (Fig. 14.11) and frequently articular wounds will also traumatize periarticular ligaments; an incidence of 34% has been documented (Wright et al 2003). Removal of detached contaminated and infected tissue is appropriate and may be achieved with a motorized synovial resector. Occasionally, discrete detached pieces of tendon or ligament are removed more satisfactorily by sharp dissection using arthroscopic scissors or knives.

Piecemeal removal of pannus preserves underlying synovium and is appropriate with localized deposits. When pannus is widespread, use of a motorized synovial resector is usually required, although this almost invariably results in at

least partial synovial resection. The authors' preference in motorized resectors, for safety and efficiency, is an enclosed, serrated blade. This is used in a to-and-fro oscillating mode with suction applied to draw material into the blade. Angled blades are also available and can be useful in some areas.

It is suggestedthat synovium may harbor bacteria, sequester inflammatory cells, release potent inflammatory mediators, and be a source of immunologic components of inflammation (Riegels-Nielson & Jensen 1984, Riegels-Nielson et aI1991).

Synovectomy has therefore been proposed to be of benefit in treating infected arthritis (Rosset al1991, Bertone et al1992) although some surgeons consIder its use should be limited (Parisien & Shaffer 1990). The authors generally remove contaminated/infected synovium that is adjacent to wounds and punctures. More extensive resection is performed in the presence of marked pannus deposits, which are usually associatedwith long-standing infective processes.Regeneration of normal villous synovium does not occur following synovectomy (Theoret et al1996, Doyle-Jones et al 2002), but the clinical implication of this and potential compromise compared to the benefits of synovectomy have not been determined.

Lavage Lavage is visually directed, high pressure, and should be performed thoroughly until all areas of the synovial cavity are visibly clean (Gaughan 1994, Thiery 1989, Smith 1986).

The fluid of choice is sterile buffered polyionic solution

(Bertone et al 1987a. Baird et al 1990) and this should be delivered by a pump system capable of rates in excess of 500 ml/minute. It is important to move the arthroscope. and thus the fluid ingress. repeatedly to all parts of the cavity in order to produce effectivelavage.The surgeon should be aware of all synovial sulci as. without individual attention. fluids will frequently flow over or past pockets of debris in these sites.This is particularly important in tendon sheaths. where. in addition to moving around the tendons. the arthroscope should be insinuated betweenthese structures. The mechanical action of flushing removes small. free-floating debris. debulks microorganisms. and reduces the load of destructive radicals and enzymes. Lavage is also thought to raise the pH from the acidic environment produced by infective processes. This in turn imprDKesthe action of several antimicrobial drugs. including aInil1ogiycosides(Mcllwraith 1983). Effectivelavage invariably requires multiple ingress and egress portals. In animals with wounds or punctures. these may also serve as instrument and egressportals (Fig. 14.12).

Potential additives to lavage fluid include antimicrobial drugs. antiseptics. dimethyl sulfoxide. and fibrinolytics. Antimicrobial preparations used by the authors include a combination of sodiumbenzylpenicillin (2.5 x 106 ill) with gentamicin sulfate (250 mg). or alternatively ceftiofur sodium (500 mg). amikacin sulfate (500 mg). or enrofloxacin (500 mg). added to the final liter of lavage fluid. There is no objective evidence to support the use of antimicrobial drugs in this manner. although administration of an aqueous antimicrobial on completion of lavage has been suggested to be of benefit (Nixon 1990). Antiseptic solutions appear to offer no

benefits have been documented, but deleterious equine cartilage matrix metabolism have been (Matthews et al 1998. Smith et al 2000), J the use of fibrinolytics have been mentioned in the human literature (Jackson 1985), but they are uncommonly employed in veterinary medicine, With the advent of endoscopic removal of fibrinoid deposits, their use largely appears superfluous.

Wound management

advantages over buffered polyionic solution (Bertone et al 1986) and, evenin dilute concentrations may produce synovial irritation (Bertone et al1986, Wilson et aI1994). Dimethyl sulfoxide has been recommended as part of the final lavage (Bertone 1996,1999, Frees et al2002). Its efficacy has not

Arthroscope and instrument portals are closed routinely.

Traumatic wounds are debrided or (preferably) excised to a clean/ contaminated state and then if possible these also are closed. This is based on the premise that endoscopic surgery can thorou~y cleanse synovial cavities and that a closed wound minj,mizesthe risk of further and/or secondary contamination or infection. These principles contrast with those of others in the literature (Gibson et al 1989, Schneider et al 1992a, Baxter 1996) who advocate open management of infected synovial cavities in order to maintain decompression.

Such alternatives include closed suction drainage (Ross et al 1991, LaPointe et a11992), fenestrated drains (Honnas et al 1991b), or creation of an open draining wound (Bertone 1999), techniques which the authors also advocate in cases of chronic infection. Solar punctures are debrided, dressed, and managed as open wounds. Traumatic wounds elsewhere in which soft tissue loss precludes closure should be debrided as rigorously as if closure was to be effected. The wound is then dressed and the limb immobilized while second intention healing ensues.

constructinga RobertJonesbandage).Commercial.tailored elasticizedbandagesare effectiveon the carpus and tarsus. whereas in the proximal limb stent bandages may be oversewn.

Local antimicrobial

When wound healing will be optimized by limb immobilization. casts may be fitted. A nonadherent dressing is applied over the wound with a thin layer of conforming bandage.

This is followed by a layer (approximately 5 mm) of plaster of Paris and then layered fiberglass. Two of the authors (CWM. AJN) rarely use plaster of Paris anymore. Thermoplastic polymer may be applied around the solar surface to resist abrasion and slipping. Counterpressure should be applied to all other sites: this limits extravascular exudation of fluid. promotes primary wound healing. and reduces pain (Nixon 1990. Bertone 1999). It can be applied effectively to the distal limb with layered compressed cotton wool (as used in

therapy

At the completion of surgery, antimicrobial drugs may be given by regional intravenous (iv) technique. Regional antimicrobial drugs have been shown to produce high and prolonged levels in synovial fluid (Whitehair et al1992a) and their efficacy in treating experimentally induced infected arthritis in horses has also been reported (Whitehair et al 1992b). Foals have been given 1 x 106m of sodium benzylpenicillin with 100 mg of gentamicin sulfate or amikacin sulfate or, alternatively 100 mg of ceftiofur sodium. Other animals have received sodium benzylpenicillin (2.5 x 106 m) with gentamicin sulfate (500 mg) or, alternatively, amikacin sulfate (500 mg), ceftiofur sodium (500 mg), or enrofloxacin (500 mg). The dosesall are empiric and have been used safely in the authors' practices.

Antimicrobial drugs may also be given as intrasynovial deposits, by continuous infusion, or by elution from impregnated polymethylmethacrylate (PMMA) beads or collagen sponges. A number of authors have recommended intrasynovial injection of antimicrobial drugs (Lloyd et al1990, Schneider et al 1992a, McClure et al 1993, Baxter 1996, Bertone 1999, Frees et al2002). Dosagesare empiric but it is generally recommended that drugs are given at not greater than a single systemic doseand that this is not repeated at less than 24-hour intervals (Baxter 1996). Infusion catheters have been used for continuous administration of gentamicin into the tarsocrural joint of horses for up to 5 days (Lescunet al 2000). This produced> 100 x the MIC (minimum inhibitory concentration) reported for common equine pathogens. The use of antimicrobial-impregnated PMMA is based on the principle that the antimicrobial drug will be released from the cement over time, thereby achieving continuous antimicrobial action in situ (Weisman et al 2000). Many of the commonly used antimicrobial/PMMA combinations achieve higher local antimicrobial concentrations than can be achieved through systemic administration (Tobias etal1996).

However, in-vitro elution tests suggest that antimicrobial concentration at tissue level may be below the MIC for most bacteria after 2-3 days (Weisman et al2000). AntimicrobialimpregnatedPMMA beadsmay be depositedusing arthroscopic techniques but a second surgical procedure will be necessary for their removal. Wire breakagecan be a problem (Butson et al 1996) and their use has also been associated with intraarticular trauma and capsulitis (Farnsworth et al 2001).

Collagen sponges also can be deposited using endoscopic techniques. They are slowly absorbed and are reported to have no irritant effect, although marked wound exudation has been reported (Summerhays 2000). These techniques may not be necessary in acute cases but the authors recommend their consideration in cases of recalcitrant or recurrent infection.

Systemic antimicrobial drugs are appropriate in all cases.

In most situations antimicrobial choice must, at least initially, be made without the results of bacterial isolation and susceptibility determination. It is thus based on a knowledge of the likely microbial populations involved in contamination and infection of equine synovial cavities. Furthermore, with the exception of juvenile infective arthritis of hematogenous origin, results of bacterial isolation are frequently unrewarding and/or contribute little to the choice of effective antimicrobial regimes. When synovial contamination has a hematogenous etiology, single organisms may be responsible for infection.

However, horses that develop synovial infection following wounds are likely to have multiple bacterial involvement (Schneider et al 1992b). Reported bacterial studies and susceptibility patterns suggest that a cephalosporin/ aminoglycoside combination is likely to be most efficacious but that most organisms are likely to be susceptible to a synergistic combination of penicillin and an aminoglycoside (Snyder et al1987, Moore et al1992, Schneider et aI1992b).

Wright et al (2003) reported the use of sodium benzylpenicillin at > 30,000 ill/kg iv every 8 hours and gentamicin sulfate at 2.2 mg/kg iv every 8 hours. Single daily gentamicin administration at 6.6 mg has been proposed as an alternative. It is suggested that this achieves greater peak and lower trough concentrations in serum and thus provides greater immediate bactericidal effect, longer duration of post antibiotic effect (PAE),and reduced risk of nephrotoxicosis (Godberet aI1995).

However, the period of effective concentrations of gentamicin in tissues added to the PAEis also exceededby every 8 hours administration at 2.2 mg/kg (Godber et al 1995). Also, gentamicin toxicity in horses is rare and there is no documented reduction in incidence with once daily administration.

In the authors' experiencein animals which have no additional medical compromise, the three times daily regime has been safeand is clinically efficacious.

With wounds involving the foot or wounds contaminated by soil or feces, supplementing the above regimen with metronidazole at 20 mg/kg orally every 8 hours is logical.

Anaerobic species are important contributors to orthopedic infections in horses and a 25% isolation rate from post wound infected arthritis has been reported (Moore et al 1992).

The majority of these bacteria are susceptible to penicillin.

The most common isolates that are resistant to penicillin are Bacteroidesspp. which are common fecalcontaminants. These, and all other anaerobic isolates from orthopedic infections are susceptible to metronidazole (Moore et aI1992).

The authors also have used a penicillin/amikacin combination: penicillin dosed as above with amikacin sulfate at 6.6 mg/kg iv every 8 hours. Low incidences of resistance

to amikacin have been reported among common equine orthopedic isolates (Snyder et al19 8 7) and organisms isolated from horses with gentamicin resistance have demonstrated susceptibility to amikacin (Orsini et al19 89). With known or suspected staphylococcal involvement, such as casesof iatrogenic infection (LaPointe et al1992, Schneider et a11992b),

ceftiofur sodium is a logical choice at 3-4 mg/kg iv every 8 hours either alone or in combination with gentamicin sulfate dosed as above. Enrofloxacin at 5 mg/kg iv every 24 hours or 7.5 mg/kg orally every 24 hours has a broad spectrum of activity that includes staphylococci. It also has been useful in the treatment of aminoglycoside-resistant Gram-negative bacteria (Orsini & Perkous 1992). Chondrotoxicity has been reported at higher than clinically used doses (Beluche et al 1999, Davenport et al 2001, Egerbacher et al 2001) and, consequently, caution has been expressed with respect to its use in foals (Orsini & Perkous 1992, Baxter 1996).

Determination of an appropriate duration of antimicrobial administration is difficult. The authors prioritize clinical signs of response and continue antimicrobial administration until there is a consistent improvement in lameness, together with reduced synovial distention, adjacent soft tissue swelling, surface temperature, and engorgement of visible draining veins. The use of sequential synovial fluid analysis has also been advocated (Bertone 1999). Largely based on experiences of experimental joint infection (Bertone et a11987b), other authors have employed or recommended protracted administration of antimicrobial drugs (Gibsonet al1989, Honnas et al 1991b, Gaughan 1994, Frees et aI2002). In a review of 121 cases of synovial contamination and infection treated endoscopically,there was a mean period of antimicrobial administration of 13 days (Wright et al 2003). A shorter period of antimicrobial administration required with arthroscopic treatment of infected joints compared to other techniques has also been reported in man (Smith 1986).

Nonsteroidal anti-inflammatory drugs have beenadvocated in the treatment of synovial infection to provide analgesia and to limit deleterious effects of inflammatory mediators on the synovial environment (Bertone & McIlwraith 1987, Gaughan 1994, Baxter 1996, Cook & Bertone 1998, Schneider 1999). There is some support for the concept in an experimental rabbit model (Smith et al 1997). However, in this experiment,the treatment comparisons were only between administration of antimicrobial drugs or administration of antimicrobial and anti-inflammatory drugs; there was no surgical decompression or lavage, etc. Evidence that systemically administered therapeutic doses of nonsteroidal anti-inflammatory drugs suppress deleterious effects of intrasynovial ~flammatory mediators is lacking (May & Lees 1996). These\drugs may partially lessen release of factors involved in joint tissue breakdown (Lee et al 2003), but administration of nonsteroidal anti-inflammatory drugs effectively obviates use of clinical parameters, particularly lameness, in determining response to treatment (McIlwraith 1983, Gaughan 1994). Current opinion in assessingpotential benefits of postoperative administration of nonsteroidal antiinflammatory drugs is therefore divided. This is reflected in the diversity of clinical use in the authors' practices, although all use nonsteroidal anti-inflammatory drugs for provision of perioperative analgesia.

Intermittently, the use of other, adjunctive medicaments have also been recommended, principal of which is postoperative intrasynovial hyaluronan. Benefits have been reported in an experimental model of tarsocrural infection

(Brusie et al199 2) and it has been advocated in clinical cases of infected tenosynovitis (Nixon 1990, Gaughan 1994, Frees et aI2002).

Movement is necessary for restoration of a normal synovial environment and endoscopypermits an early return to exercise (Nixon 1990, Frees et al2002, Vispo Seara2002).

The association between immobilization and cartilage degeneration has been well documented (Palmoski et al19 79, Josza et al1987, Videman 1981, Kallio et aI1988). Benefits from early instigation of exercise,in the form of continuous passive motion, have been demonstrated in experimental models (Salter et al1981) and reported in clinical cases in man (Parisien & Shaffer 1990, Perry et aI1992). Dynamic loading counteracts effects of inflammatory mediators, such as bacterial lipopolysaccharide, on chondrocyte metabolism and it is suggested that this may have contributed to successfulmanagement of articular infection (Lee et al2 003).

Whenever possible,the authors recommend walking exercise to commence in1mediately after surgery and a graduated, controlled exercise program follows in line with tissue

compromise.

Close clinical monitoring is critical in the immediate postoperative period. Since most synovial structures will be enclosed in bandages at this time, pain is the most sensitive indicator of response to treatment. In the face of progressive lameness or lack of clinical improvement. complete case reevaluation, including repeated radiographs, ultrasonographs. and synoviocentesis, is always merited. If potential reasons for relapse or lack of response can be identified, then management can be changed in a logical manner. Since endoscopy maximizes intrasynovial evaluation, this is also indicated in recurrent or recalcitrant cases. Repeated endoscopy has proved useful in detecting and removing foreign material, infected bone, and intra-articular sequestra that were not present or identified at the first surgery (Wright et al 2003).

When no satisfactory explanation for a poor response or relapse has been identified, then lack of susceptibility of the causative organisms to the current antimicrobial regimen should be considered and modification is frequently appropriate. It always remains possible that infecting organisms are susceptible but that they have not been exposed to the antimicrobial drugs at an appropriate level; nonetheless, a change in regimen is usually made at this time.

Results of endoscopic surgery in treating clinical cases of contaminated and infected synovial cavities have been reported by a number of authors (Gibson et al1989, Rosset al 1991, LaPointe et al1992, Schneider et a11992a. Steel et al 1999. Wright et al1999, 2003. Freesetal2002). Arthroscopy and partial synovial resection were reported to be inferior to

arthrotomy and open drainage in the treatment of experimentally induced infection of tarsocrural joints (Bertone et al 1992). However, this experiment does not reflect many features found in clinical cases of synovial contamination and infection. Arthrotomy was also associated with an increased risk of secondary infection by other organisms and postoperative fibrosis and required a greater degree of postoperative care. The senior author of this report now also recommends endoscopyas a primary line of therapy (Bertone 1999). Frees et al (2002) reported 18 of 20 (90%) cases surviving and 14 (70%) returning to athletic soundness following tenoscopic treatment of contaminated and infected digital flexor tendon sheaths. A retrospective analysis of 121 cases of contaminated and infected synovial cavities treated endoscopically reported a 90% survival rate, with 81% of animals returning to their preoperative level of performance.

Negative prognostic indicators included involvement of the navicular bursa, the presence of marked pannus, and the presenceof osteochondral lesions (Wright etal2003). Neither of these studies found a correlation between the duration of clinical signs prior to endoscopy and case outcome. In a comparable series of 192 cases treated by combinations of lavage, open surgery, drainage, intrasynovial antimicrobial drugs, and systemic antimicrobial drugs, 73% of 126 animals >6 months of ageand 45% of foals < 6 months of agesurvived and 56% of 52 adult horses returned to performance (Schneider et a11992b).

The authors currently suggest that management of contaminated and infected synovial cavities is optimized by endoscopic treatment. This permits thorough evaluation, with appropriate debridement, effective lavage, and minimal tissue trauma. Multiple synovial cavities may be treated simultaneously, there is early pain relief, few complications, and minimal postoperative care. Animals are able to make an early return to exerciseand the prognosis appears to be better than with other reported regimens.

References Baird AM. Scruggs DW, Watkins JP, et al. Effect of antimicrobial solution on the palmar digital tendon sheath in horses. Am J Vet Res1990; 5~; 1488-1494.

Baxter GM. ,Instrumentation and techniques for treating orthopaedic infections in horses. Vet Clin N Am Equine Pract 1996; 12; 303-335.

Beluche LA. Bertone AL. Anderson DE, et al. Dose-dependent effect of enrol1oxacin on equine articular cartilage. AmJ Vet Res1999; 60; 571-582.

Bertone AL. Infectious arthritis in; Joint disease in the Horse Mcllwraith CW Trotter GW (eds), WE Saunders; Philadelphia; 1996; 397-409.

Bertone AL. Update on infectious arthritis in horses. EqUineVet Educ 1999; 11; 143-152.

Bertone AL. Davis DM. Cox HU et al. Arthrotomy versus arthroscopy and partial synovectomy for treatment of experimentally induced arthritis in horses. AmJ Vet Res 1992; 53; 585-591.

Bertone AL. Mcllwraith CWoA review of current concepts in the therapy of infectious arthritis. Proc Am Asso EqUine Pract 1987; 32; 323-339.

Bertone AL, Mcllwraith CW,Jones RL et al. Povidone-iodine lavage treatment of experimentally-induced equine infectious arthritis.

AmJ VetRes 1987a; 48: 712-715.

Bertone AL, Mcllwraith CW,Jones RL et al. Comparison of various treatments for experimentally induced equine infectious arthritis.

AmJ Vet Res1987b; 48: 519-529.

Bertone AL, Mcllwraith CW, Powers BE, et al. Effect of four antimicrobial lavage solutions on the tarsocrural joint in horses. Vet Surg 1986; 15: 305-315.

Bertone AL, Palmer JL, Jones J. Synovial fluid inflammatory mediators as markers of equine synovitis. Vet Surg 1993; 22: 372-373.

Brusie RW, Sullins KE, White NA, et al. Evaluation of sodium hyaluronate therapy in induced septic arthritis in the horse.

EquineVetJ 1992; (Suppl) 11: 18-23.

Bussiere F, Beaufils P. Apport de l'arthroscopie au traitment des arthritis septiques a pyogeres banals du genom de l'adulte: a propos de 16 cas. Revue de Chirurgie Orthopedique 1999; 85:

803-810.

Butson RJ.Schramme MC, Garlick M, et at. Treatment of intrasynovial infection with gentamicin impregnated polymethylmethacrylate beads. Vet Rec 1996; 138: 460-464.

Cook VL, Bertone AL. Infectious arthritis, In: White NA, Moore IN (eds), Current technique in equine surgery and lameness. 2nd edn. Philadelphia: WB Saunders; 1998: 381-385.

Davenport CLM, Boston RC, Richardson DW: Effects of enrofloxacin and magnesium deficiency on matrix metabolism in equine articular cartilage. AmJ Vet Res 2001; 62: 160-166.

Dory MA, Wantelet MJ. Arthroscopy in septic arthritis. Arthritis Rheum 1985; 28: 198-203.

Doyle-Jones PS, Sullins KE, Saunders GK. Synovial regeneration in the equine carpus after arthroscopic, mechanical or carbon dioxide laser synovectomy. Vet Surg 2002; 31: 331-343.

Egerbacher M, Edinger J, Tschulenk W. Effects of enrofloxacin and ciprofloxacin hydrochloride on canine and equine chondroytes in culture. Am J Vet Res 2001; 62: 704-708.

Farnsworth KD, White NA, Robertson J. The effect of implanting gentamicin impregnated polymethylmethacrylate beads in the tarsocrural joint of the horse. Vet Surg 2001; 30: 126-131.

Frees KE, Lillich JD,Gaughan EM, DeBowesRM. Tenoscopic-assisted treatment of open digital flexor tendon sheath injuries in horses: 20 cases (1992-2001).

J Am Vet Med Assoc 2002; 220: 1823-1827.

Giichter A. Der Gelenkinfekt Inform Arzt 1985; 6: 35-43.

Gaughan EM. Wounds of tendon sheaths and joints in horses. Comp Cont Educ Pract Vet 1994; 16: 517-529.

Gibson KT, Mcllwraith CW, Turner AS, et at. Open joint injuries in horses: 58 cases (1980-1986). J Am Vet Med Assoc 1989; 194:

398-404.

Godber 1M, Walker RD, Stein GE, et at. Pharmacokinetics, nephrotoxicosis, and in vitro antibacterial activity associated with single versus multiple (three times) daily gentamicin treatments in horses. AmJ Vet Res 1995; 56: 613-618.

Honnas CM, Schumacher J, Cohen ND, et al. Septic tenosynovitis in horses: 25 cases (1983-1989).J Am Vet Med Assoc 1991a; 199:

1616-1622.

Honnas CM, Schumacher J,Watkins JP.et at. Diagnosis and treatment of septic tenosynovitis in horses. Comp Cont Educ Pract Vet 1991b; 13: 301-311.

Ivey M, Clark R. Arthroscopic debridement of the knee for septic arthritis. Clin Orthop ReIRes 1985; 199: 201-206.

Jackman BR, Baxter GM, Parks AH, et at. The use of indwelling drains in the treatment of septic tenosynovitis. Proc Am Assoc EquinePract 1989; 35: 251-257.

JacksonRW. The septic knee -arthroscopic treatment. Arthroscopy 1985; 1: 194-197.

Jarrett MP. Grossman L. Sadler AH. et al. The role of arthroscopy in the treatment of septic arthritis. Arthritis Rheum 1981; 24: 737-739.

JoszaL. Jarrinen M. Kannus P. et al. Fine structural changes in the articular cartilage of the rat's knee following short-term immobilisation in various positions: a scanning electron microscopic study. Int Orthop 1987; (II): 129-133.

Kallis PE. Michelsson JE. Bjorkenheim JM. Immobilisation leads to early changes in hydrostatic pressure of bone and joint. A study on experimental osteoarthritis in rabbits. Scand J Rheumatol 1988; 17: 27-32.

Koch DB. Management of infectious arthritis in the horse. Comp ContEducPractVet 1979; 1: 545-550.

LaPointe IM. Laverty S. LaVoie Jp.Septic arthritis in 15 Standardbred racehorses after intra-articular injection. Equine Vet J 1992; 24: 430-434.

Lee MS. Ikenove T. Trindale MCD. et al. Protective effects of intermittent hydrostatic pressure on osteoarthritic chondrocytes activated by bacterial endotoxin in vitro. J Orthop ReI Res 2003; 21: 117-122.

Lescun TB. Adams SB. Wu CC. et al. Continuous infusion of gentamicin into the tarsocrural joint of horses. Am J Vet Res 2000; 61: 407-412.

Lloyd KCK. Stover SM. PascoeJR. et al. Synovial fluid pH. cytological characteristic. and gentamicin concentration after intraarticular administration of the drug in an experimental model of infectious arthritis in horses. AmJ Vet Res 1990; 51: 1363-1369.

McClure SR. Hooper RN. Watkins JP. Intermittent antimicrobial infusion for management of a septic distal interphalangeal joint in a horse. J Am Vet Med Assoc 1993; 202: 973-975.

Mcilwraith CWoTreatment of infectious arthritis. Vet Clin North Am Large Anim Pract 1983; 5: 363-379.

Matthews GL. Engler Sf. Morris EA. Effect of dimethylsulfoxide on

articular cartilage proteoglycan synthesis and degradation. chondrocyte viability and matrix water content. Vet Surg 1998; 27: 438-444.

May SA. Lees P. Nonsteroidal anti-inflammatory drugs. In: Mcilwraith CWo Totter GW (eds). Joint disease in the horse Philadelphia: W B Saunders; 1996: 223-237.

Nixon AJ. Septic tenosynovitis. In: White NA. Moore IN (eds). Current practice of equine surgery. Philadelphia: IE Lippincott 1990; 451-455.

Orsini JA. Benson CE. SpencerPA. et al. Resistanceto gentamicin and amikacin of Gram negative organisms isolated from horses. Am J Vet Res 1989; 50: 923-925.

Orsini JA. Perkous S. The fluoroquinolones: clinical applications in veterinary medicine. Compend Contin Educ Pract Vet 1992; 14:

1491-1496.

Palmer JL. Bertone AL. Joint structure. biochemistry and biochemical disequilibrilful in synovitis and equine joint disease.Equine Vet J 1994; 26: 263-277.

Palmoski M. Perricore E. Brande KD. Development and reversal of a proteoglycan aggregation defect in normal canine knee cartilage after immobilisation. Arthritis Rheum 1979; 22: 508-517.

Parisien JS.ShafferB. Arthroscopic management of pyarthrosis. Clin Orthop ReIRes 1990; 275: 243-246.

Perry CR. Hulsey RE. Mann FE. et al. Treatment of acutely infected arthroplasties with incision. drainage and local antibiotics deliveredvia an implantablepump. ClinOrthop 1992; 281: 216-223.

Reginato AJ. Ferreiro JL. O'Connor CR. et al. Clinical and pathologic studies of twenty-six patients with penetrating foreign body injury to the joints. bursae and tendon sheaths. Arthritis Rheum

1990;33:1753-1762.

Riegels-NielsonP. Frinodt-M011erN. S0rensenM. et al. Synovectomy for septic arthritis. Early versus late synovectomy studied in the rabbit knee. Acta Orthop Scand 1991; 62: 315-318.

Riegels-Nielson P. JensenJS. Septic arthritis of the knee. Five cases treated with synovectomy.Acta Orthop Scand 1984; 55; 657-659.

Rose RJ. Love DN. Staphylococcal septic arthritis in three horses.

Equine VetJ 1979; 2: 85-89.

RossMW. Orsini JA. Richardson DW. et al. Closed suction drainage in the treatment of infectious arthritis of the equine tarsocrural joint. VetSurg 1991; 20: 21-29.

Salter RE. Bell RS. Keeley FW. The protective effect of continuous passive motion on living articular cartilage in acute septic arthritis: an experimental investigation in the rabbit. Clin Orthop 1981; 159: 223-247.

Santschi EM. Adams SB. FosterIF. et al. Treatment of bacterial tarsal tenosynovitis and osteitis of the sustentaculum tali of the calcaneus in five horses. Equine VetJ 1997; 29 (3): 244-247.

Schneider RK. Bramlage LR. Mecklenburg 1M. et al. Open drainage. intra-articular and systemic antibiotics in the treatment of septic arthritis/tenosynovitis in horses.Equine VetJ 1992a; 24: 443--449.

Schneider RK. Bramlage LR. Moore RM. et al. A retrospective study of 192 horses affected with septic arthritis/tenosynovitis. Equine VetJ 1992b; 24: 436--442.

Schneider RK. Orthopaedic infections. In: Equine surgery. 2nd edn.

Auer JJ.StickJA. Philadelphia: WB Saunders; 1999: 727-735.

Skyhar MJ. Mubarak SJ.Arthroscopic treatment of septic knees in children. J Pediatr Orthop 1987; 7: 47-651.

Smith CL. MacDonald MH. TeschAM. et al. In vitro evaluation of the effect of dimethyl sulfoxide on equine articular cartilage matrix metabolism. Vet Surg 2000; 29: 347-357.

Smith MJ. Arthroscopic treatment of the septic knee. Arthroscopy 1986; 2: 30-34.

Smith RL. Kajiyama G. Schurman DJ. Staphylococcal septic arthritis: antibiotics and nonsteroidal anti-inflammatory drug treatment in a rabbit model. J Orthop Res1997; 15: 919-926.

Snyder JR. Pascoe JR. Hirsch DC. Antimicrobial susceptibility of microorganisms isolated from equine orthopaedic patients. Vet Surg 1987; 16: 197-201.

Spiers S. May SA. Harrison LJ. et al. Proteolytic enzymes in equine joints with infectious arthritis. Equine Vet J 1994; 26: 48-50.

SteelCM. Hunt AR. Adams PLE et al. Factors associatedwith prognosis for survival and athletic use in foals with septic arthritis: 93 cases (1987-1994).JAmVetMedAssoc 1999; 215: 973-977.

Stutz G. Kuster MS. Kheinstiick F. et al. Arthroscopic management of septic arthritis: stages of infection and results. Knee Surg Sports Traumatol Arthrosc 2000; 8: 270-274.

Summerhays GES. Treatment of traumatically induced synovial sepsisin horses with gentamicin-impregnated collagen sponges.

Vet Rec 2000; 147: 184-188.

Theoret CL. Barber SM. Moyana T. et al. Repair and function of synovium after arthroscopic synovectomy of the dorsal compartment of the equine antebrachiocarpal joint. VetSurg 1996; 25:

142-153.

Thiery JA. Arthroscopic drainage in septic arthritides of the knee: a multi-centre study. Arthroscopy 1989; 5: 65-69.

Tobias K. Schneider R. BesserT. Use of antimicrobial impregnated polymethylmethacrylate. J Am Vet Med Assoc 1996; 208:

841-845.

Videman T. Changes in compression and distances between tibial and femoral condyles during immobilization of rabbit knee. Arch OrthopTrauma Surg 1981; 98: 289-291.

Vispo Seara JL. Barthel T. Smitz H. et aI. Arthroscopic treatment of septic joints: prognostic factors. Arch Orthop Traum Surg 2002; 122: 204-211.

Weisman DL. Olmstead ML. Kowalski JJ. In vitro evaluation of antibiotic elution from polymethylmethacrylate (PMMA) and mechanical assessmentof antibiotic-PMMA composites Vet Surg 2000; 29: 245-251.

Whitehair KL. Blevins WE. FesslerIF. et al. Regional perfusion of the equine carpus for antibiotic delivery. Vet Surg 1992a; 21: 279-285.

Whitehair KL. Bowerstock TL. Blevins WE. et al. Regional limb perfusion for antibiotic treatment of experimentally induced septic arthritis. VetSurg 1992b; 21: 367-373.

Wilson DG. Cooley AJ. McWilliams PS. et al. Effects of 0.05% chlorhexidine lavage on the tarsocrural joints of horses. Vet Surg 1994; 23: 442-447.

Wirtz DC. Marth M. Miltner O. et al. Septic arthritis of the knee in adults: treatment by arthroscopy or arthrotomy. Int Orthopaed 2001; 25: 239-241.

Wright IM. Phillips TJ. Walmsley JP. Endoscopy of the navicular bursa: a new technique for the treatment of contaminated and septic bursae. Equine Vet J 1999; 31: 5-11.

Wright IM. Smith MRW. Humphrey DJ. et aI. Endoscopic surgery in the treatment of contaminated and infected synovial cavities.

Equine VetJ 2003; 35: 613-619.

Introduction There are only very few reports in the veterinary literature on equine temporomandibular joint (TMJ) disorders. Early clinical reports (Blasse 1909, Hardy & Shiroma 1991, Holmlund 1992) point out a relation between teeth and jaw abnormalities and TMJ diseases. It was never clear if abnormalities in teeth secondarily create TMJ diseasesor vice versa. Recently,clinical attention has been drawn to disorders of this joint as possiblereasons for headshaking, misbehavior, "back problems", and head tilt.

In humans, TMJ problems are much more commonly diagnosed; 5-12% of North American people develop significant and treatable disorders of the TMJ (Rugh & Solberg, 1985).

The few reports in the veterinary field describe mainly dramatic situations such as luxation (Barber et al 1985), intra-articular fractures (Hurtig et al 1984), and septic arthritis (Warmerdam et alI997). These few reports might give a wrong impression of actual percentage of TMJ disorders. An initial report was presented by Boening (1996) of a horse suffering from orthopedic symptoms which were later localized as primary TMJ disease.He described a clinical case of a German Warmblood dressagehorse with chronic "back problems" and active head tilt which was attributed to a transverse, unilateral tear in the joint disk of the TMJ. The diagnosis was made arthroscopically after previous scintigraphy of the head (Fig. 15.1), followed by intrasynovial anesthesia. This horse improved significantly after partial arthroscopic removal of the articular disk, debridement, and lavage. Postoperatively, this horse received repeated intraarticular corticosteroid injections.

Increasing use of imaging and minimally invasive techniques has led to increased opportunities for diagnostic and therapeutic procedures. Different authors (Tietje, et al 1996, Weller et al1999a, 1999b, Stadtbiiumer & Boening 2000, 2002, Maierl et al2000) have described the anatomy, pathogenesis, radiologic and sonographic findings, (Fig. 15.2), computer tomography abnormalities, and arthroscopic approaches, as well as therapeutic and arthroscopic surgery.

As the TMJis another small joint. all specificfeatures for small joints described previously for arthroscopic surgery of the distal and proximal interphalangeal joints can be adapted.

The TMJ is an incongruous joint formed ventrally by the condylar process of the mandibular head and dorsally by the zygomatic process of the temporal bone. As in all joints which are incongruous. a fibrocartilaginous disk is interposed to level out the incongruity. This disk has an elongated. roundish appearance,and is about 5 mm thick at the border.

Even in adult horses. the center of the disk is thinned and transparent (Fig. 15.3). The TMJ is completely divided into two compartments: the dorsal disco temporal compartment is more spacious than the ventral disco mandibular articulation. Both compartments have caudal recesses;the dorsal caudal recess allows arthroscopic accessto the disco temporal joint and the caudal ventral recess to the disco mandibular compartment. A significant joint capsule. as well as a lateral and a caudal (elastic) ligament, assure lateral

stabilizationof this joint. For invasivemanipulation of the TMJ.the more ventrally locatedtransversefacial artery and vein and the transverse facial branch of the auriculartemporal nerve have to be prelocated.Another structure of importance is the rostral-dorsal part of the parotid gland. partially coveredby the parotid-auricularmuscle.

For unilateral arthroscopy of the TMJ, the horse is under general anesthesia and in lateral recumbency -for a bilateral approach, dorsal recumbency is an option. After spacious shaving and aseptic preparation the caudal recessus of the disco temporal joint is predistended with about 10-15 ml of polyionic R~er's solution. The insertion of a hypodermic needle is made immediately adjacent to the dorsal aspect of the palpable condylar process. A skin incision is made with a No. 11 scalpel blade right over the bulging rostral joint capsule before the joint capsule is penetrated with an arthroscopic sleeveand a conical obturator of the 4 mm 300 arthroscope (Figs 15.4 and 15.5) and advanced in a rostromedial direction. The arthroscopic portal to the rostral recess of the ventral compartment is located immediately rostral to the mandibular caput and ventral to the joint space.To enter this compartment the sleeve has to be advanced in a more horizontal plane and in a medial direction. This joint compartment is even smaller than the dorsal compartment and does not allow surgical manipulation. In this particular compartment, because of the limited space.there is a higher risk of iatrogenic cartilage damage.

Once in the joint, gas distention (CO2) prevents the protrusion of synovium. After diagnostic evaluation of the joint. the ideal site for the instrument portal (about 1 cm further dorsally) is determined by inserting a hypodermic needle. Routine exploration of articular structures is followed by passive movement of the mandible. This will exposerostral parts and allow disk palpation with a probe. Figures 15.6to 15.10 show examination of the proximal compartment

with the temporal bone aboveand the disk below.Figures 15.6 and 15.7 are central and medial views respectively.

Chondropathyon the temporal articular surface can be seenin Fig 15.8 with more chronic change in Fig 15.9.

Penetrationof the medial joint capsuleresults in exposure of massetermuscle fibers. Each arthroscopic procedure is followed by lavage and skin closure with simple interrupted sutures.

Temporomandibular Joint

Table

15.1 Horses with diagnosis of inflammation

of the temporomandibular

joint (TMJ) (1996-2000)

Sound after 6 weeks postoperatively

Scintigraphy: left TMJ hot spot +, ultrasound: distended joint filling

Chronic, diffuse

Improved, but still irregular

proliferative

headshaking

Swelling TMJ with reduction of jaw

Ultrasound:

Post-traumatic

Improved, easy work possible

motility

intrasynovial hyper-echogenic structures

hemarthrosis, significant lesion joint capsule

Case 4 Warmblood, 6-year-old,gelding, showjumper

Chronic swelling, right joint capsule after colic

Scintigraphy: right hot spot +++, ultrasound: distended joint, increased thickness joint capsule

Significant traumatic synovitis and proliferation of villi +++

Sound,no symptoms after 6 weeks

Case 5 Warmblood, 9-year-old mare dressage

Significant back

Scintigraphy: right hot spot ++++, ultrasound: thickened joint capsule

Subtotal, transverse, axial rupture of articular disk, secondary mechanical synovitis, free floating bony fragment, small size

Sound and back to full work after 4 months

Slight chronic headshaking. behaviourai problems

Resu Its

problems, compression pain right TMJ, bilateral teeth abnormalities

joint

distention,

synovitis

graphy,and diagnostic/surgicalarthroscopy (Table 15.1).

Obviousclinical syndromesuch as fractures,luxations. and septic arthritis were not encountered in this study. The An initial clinical seriesinvolving 5 Warmbloodhorseswasreported

by Stadtbaumer& Boening(2002). Over 4 years ageranged from 6 to 12 years: 4 horseswere Warmbloods (1996-2000), they diagnosedTMJdiseasesusing different and one was a Quarter Horse; there were 3 geldingsand 2 mares. diagnostictools suchas scintigraphy,ultrasonography, radio-

Treatment is summarized in Table 15.1. The outcome was excellent in three of five horses. with the symptoms in the remaining two improved. The authors emphasised the need for careful examination of the TMJ in extended orthopedic

work-up when horses are presentedwith back problems. behavior problems. and headshaking.

References Barber SM. Doige CE. Humphreys SG. Mandibular condylectomie: technique and results in normal horses. Vet Surgery 1985: 14:

79-86.

Blasse A. Untersuchung fiber die Arthritis des Kiefergelenkes beim Pferde. Inaug.-Diss.. GieBen 1909.

Boening KI. Equine arthroscopy Seminar. Proc ESVOT. Munich.

Germany. 1996.

Hardy I. Shiroma IT. What is your diagnosis? Rostral luxation of the right temporomandibular joint. I Am Vet Med Assoc. 1991; 198: 1663-4.

Holmland A. Diagnostic TMI arthroscopy. Oral Surg Oral Diagn.

1992; 3:13-8.

Hurtig ME. Barber SM. Farrow. CS. Temporomandibular joint luxation in a horse. Am Vet Med Association 1984; 185: 78-80.

Maierl JR. Weller R. ZechmeisterR. Liebich HG. Arthroscopic anatomy of the equine temporomandibular joint. Polish I Vet Sci 2000; 3 (Suppl): 28.

May KA, Moll HD, Howard RD et al. Arthroscopic anatomy of the equine temporomandibular joint. Vet Surg 2001; 30: 564-571.

Rugh ]D, Solberg WK. Oral health status in the United States: temporomandibular joint disorders. J Dent Educ 1985; 49:

398-405.

Stadtbaumer G, Boening KJ. Diagnostische und minimal-invasive Verfahren am Kiefergelenk des Pferdes. Proc der Arbeitstagung der Fachgruppe "pferdekrankheiten" der DVG "Fortschritte in der Minimalinvasiven Chirurgie", Tutzing, 2000: 51-53.

Stadtbaumer G, Boening KJ. Diagnostische und arthroskopische Verfahren am Kiefergelenk des Pferdes. Tieriirztl Prax 2002; 30(G): 99-106.

Tietje S, Becker M, Bockenhoff G. Computed tomographic evaluation of head diseasesin the horse: 15 casesEquine VetJ 1996: 98-105.

Warmerdam EPL, Klein WR, Van Herpen BPJM. Infectious temporomandibular joint disease in the horse: computed tomographic diagnosis and treatment of two cases. Vet Rec 1997; 141:

172-174.

Weller R, Cauvin BR, Bowen 1M, May SA. Comparison of radiography, scintigraphy and ultrasonography in the diagnosis of a case of temporomandibular joint arthropathy in a horse. Vet Record 1999; 144: 377-379.

Weller R, Taylor S, Maierl J, Cauvin BRJ,May SA. Ultrasonographic anatomy of the equine temporomandibular joint Equine Vet J

1999;31:529-532.

Weller R, Maierl J, Bowen 1M et al. The arthroscopic approach and intra-articular anatomy of the equine temporomandibular joint.

Equine VetJ 2002; 34: 421-424.

Introduction Arthroscopy involves. in most circumstances. hospitalization of horses and general anesthesia. which can both result in complications to case management. In addition. there are a number of intraoperative and postoperative complications that are of particular importance with respectto arthroscopy.

The nature and incidence of complications in human arthroscopyhave beendocumented for the most commonly operated joints and will be reviewed briefly. Documentation of complications in equine arthroscopy is limited (McIlwraith 1990).

Complications

of

Arthroscopy in Man The most common joint for human arthroscopy is the knee.

Three surveys have reported complication rates of 0.8% (DeLee1985). 0.56% (Small 1986). and 1.68% (Small 1988).

However. in a smaller series. Sherman et al (1986) reported a complication rate of 8.2%. Complication rates of 9% for arthroscopyof the ankle and 9.8% for the foot and ankle combined were published by Ferkel et al (1996) and Ferkel et al (2001). respectively.Complications occurred in only 1.6% of hip arthroscopies reported by Griffin & Villar (1999). None of these were major or long term and most were attributed to use of traction techniques. Kelly et al (2001) reported serious complications in 0.8% and minor complications (which all resolved) in 11 % of arthroscopic procedures in the elbow. whereas Reddy et al (2000) documented an overall incidence of 1.6% at this site. The highest reported incidence of complications in man appearsto be associatedwith arthroscopy of the shoulder. where Berjano et al (1998) reported a 10.6% incidence.

The specific complications encountered in man vary with individual joints and also with the surgical techniques used.

The most common complications associatedwith arthroscopy of the human knee are presented in Table 16.1. The commonest complication associated with foot and ankle

Hemarthrosis Infection Thromboembolism Anesthetic complications Instrument breakage and/or failure Articular pain

Ligament injury Neurologic injury Fracture Adhesion formation Postoperative effusion Wound healing complications

Complex regional pain syndrome

Ecchymoses

Data from Delee (1985). Small (1986.1988) and Sherman et al (1986) reviewed

by Allum (2002).

(Ferkel et al 2001) and elbow (Kelly et a12001) arthroscopy is neurologic injury caused by iatrogenic damage to adjacent neural trunks. Systemic complications in man include cardiopulmonary events,atelectasis,pulmonary embolus,myocardial infarction, and death. Preoperative complications include incorrect diagnosis, lack of preoperative planning, and failure to obtain appropriate preoperative studies (Ferkel et al2001).

A number of factors have been identified as predisposing to complications. Small (1986) and Ferkel et al (2001) recognized complex surgical procedures such as meniscal repair and reconstruction of the anterior cruciate ligament as being associated with an increased incidence of complications. Indust&! injuries, meniscectomy,abrasionarthroplasty, patients of gre'aterthan 50 years of age,and tourniquet time were associated with increased risk by Sherman et (1986).

Allum (2002) commented that, surprisingly, the incidence of complications was unrelated to surgeon experience.

In making recommendations to minimize complications associatedwith arthroscopy of the knee, Allum (2002) made four specific recommendations: 1. Use of a sharp trocar should be avoided.

2. Instruments should be used only if they can be seenclearly.

3. Tissuesshould never be cut blindly but always under direct visualization.

4. Care should be taken with power instruments, particularly when suction is applied, as this can rapidly result in joint evacuation and compromised visibility.

The importance of thorough three-dimensional anatomic knowledge and location of the correct sites for creation of portals has been emphasized in the shoulder (Boardman & Cofield (1999) and ankle (Ferkel et al 2001). The use of appropriately sized instruments was also recommended by Ferkel et al (2001).

Postoperative infection rates of 0.08%, 0.1 %, 0.23%, and 0.42% have been reported following knee arthroscopy by (DeLee (1985), Sherman et al (1986), D'Angelo & OgilvieHarris (1988), and Armstrong et al (1992), respectively.

Barber et al (1990) reported a postoperative infection rate of 1.4% following arthroscopy of the ankle. The higher incidence at this site was attributed to thinner skin, less subcutaneous tissue and reduced local healing compared to the knee. Factors which predisposeto infection include longer operating times, an increased number of procedures during each surgery, prior surgical procedures, chondroplasty and soft tissue debridement (Armstrong et aI1992). Concurrent administration of corticosteroids has also been identified as producing an increased incidence of postoperative infection (Armstrong et al1992, Gosal et al1999, Kelly et al 2001).

Allum (2002) states that most surgeons undertaking arthroscopy of the knee routinely do not use prophylactic antimicrobial drugs except for complex procedures such as reconstruction of the anterior cruciate ligament. However, D'Angelo & Ogilvie-Harris (1988) have suggested that they may be indicated on a cost/benefit basis. Prophylactic antimicrobial drugs have been reported to reduce the infection rate associated with arthroscopy of the foot and ankle (Ferkelet a12001) and their use has also beenadvocated with arthroscopy of the elbow (Kelly et al2001) and should~r (Berjano et aI1998). In the face of postoperative infection the recommended treatment in man consists of intravenous antimicrobial drugs, repeated arthroscopy with debridement and vigorous high-volume lavage (Armstrong et al 1992, Ferkel et al2001, Allum 2002).

If instruments break, creating loose intra-articular debris, Allum (2002) recommends that, if the fragment is visible, the fluid should be switched off and the piece retrieved. If the piece is not visible, then lavage may flush it into view or it may be localized with conventional radiographs or fluoroscopy.

Occasionally, magnetic instruments may aid retrieval (e.g.

Golden RetrieveTMfrom Instrument Makar, Inc., Okamos,MI).

Pain is uncommon after diagnostic arthroscopy or simple surgical procedures but may be a problem following extensive soft tissue interference such as meniscal repair, synovectomy, or intra-articular reconstruction of ligaments (Allum 2002).

This may be controlled by intra-articular opiates Ooshi et al 1992) or local analgesics (Chirwa et al 1989). Complex regional pain syndrome, which has also been termed reflex sympathetic dystrophy, is a complex, unpredictable, and variable problem which has proved difficult to define, predict, or prevent (Allum 2002).

Iatrogenic damage to articular cartilage is considered the most frequently unreported complication of arthroscopy of any joint (Ferkel et al 2001). Small joints are most susceptible and long-term sequelaeare unknown (Ferkel et al 2001).

Perisynovial neurovascular structures can be injured by incorrect portal placement (Boardman & Cofield 1999, Ferkel et al 2001, Kelly et al 2001). More remote neural injury can result from inappropriate patient positioning or manipulation and from extrasynovial fluid extravasation (Kim et al2002).

Postoperative effusion can be considered a sign of unresolved lesions. Dandy (1987) has reported an incidence varying between zero and 15% and ascribed the effusion to inflammatory synovitis. Hemarthrosis is said to have an incidence of 1% in human arthroscopy (Allum 2002). It is treated by lavage and instillation of local analgesic and epinephrine.

In arthroscopy of the knee, the use of skin sutures has been reported to carry a higher complication rate than the use of adhesive tape (Fairclough & Moran 1987) or leaving wounds open (Maffulli et alI991). No significant differences were reported between the latter two techniques (Hussein & Southgate 2001). By contrast, the use of skin sutures is associated with a reduced complication rate in foot and ankle arthroscopy (Ferkel et al2001). Also, an increased rate of drainage or erythema was noted with adhesive tape compared to sutures in arthroscopy of the elbow (Kelly et al 2001). If synovial fistulae result. treatment is focused on immobilization (DeLee 1985, Proffer et alI991).

Hemarthrosis Hemarthrosis is not usually a significant problem. Distal limb hemorrhage is invariably reduced when animals are in dorsal recumbency compared to those positioned laterally. Use of an Esmarch bandage and tourniquet may be of benefit when dealing with lesions in which hemorrhage may be anticipated.

Examplesinclude contaminated and infected synovial cavities and tenoscopy of the digital flexor tendon sheath. In most other situations. hemorrhage is controlled by the pressure generated by i,rigating fluids. However. if the joint is exited, left undistended. and then re-entered, the surgeon will encounter hemorrhage. particularly from debrided tissues. In such instances. flushing with an open egress cannula, followed by closure of the cannula and redistention, is all that is necessary to eliminate the problem. The same procedure is performed if hemarthrosis is present at the time of initial entry.

The fact that hemorrhage is minimized with distention is important to note, particularly with reference to debridement of subchondral defects. During curettage of subchondral bone, hemorrhage (as seenduring arthrotomy) is not evident while the joint is distended. The surgeon must therefore either use other criteria to evaluate an appropriate depth of debridement or must release fluid pressure in order to assess bleeding from subchondral bone.

Obstruction

of view by synovial

villi

Within each synovial cavity there are regions of villous and avillous synovium. Synovial villi may obstruct arthroscopic visualization throughout a synovial cavity or this may be a localized problem. When generalized, this problem is usually associated with either inadequate distention or excessivefluid movement. Distention may be limited by inadequate delivery of fluid. capsular fibrosis. or the development of extrasynovial extravasation of fluid. Excessivefluid movement can occur with an open outflow portal. This is seen most commonly with an open egress cannula or an excessively large and patent instrument portal. The latter can occur as a technical error but more commonly follows removal of large intraarticular fragments. For these reasons, initial arthroscopic examination should be performed with a closedegresscannula.

In addition, whenever feasible, large fragments should be removed after small fragments. Many mechanical pumps will deliver fluids at rates up to 1 liter/minute. These will compensate for excessivefluid outflow in many situations, but at high flow rates bubbles are frequently produced, which also result in diminished visualization. Fluid exit through a large, patent instrument portal can also be controlled to some degree by retention of an instrument within the portal.

However. the surgeon must try not to prevent fluid outflow by placing a finger over the instrument portal. as this will result in rapid extrasynovial extravasation.

Proliferative synovial villi may obscure articular margins and lesions in these locations. Common examples include fragmentation of the dorsoproximal and plantaroproximal articular margins of the proximal phalanges (Fig. 16.1) &nd osteochondritis dissecans of the lateral trochlear ridge of the

femur.Assessment of thesesitescan usuallybe madeusing a probeto displacethe villi, but frequentlysufficientvisualization to permit confidentand accuratesurgicalinterference will require local synovial resection (Fig. 16.2). This is performed most efficiently with motorized apparatus with suctionattached.Resectionshould alwaysbe limited since, althoughthe clinical implicationsare unknown, it has been demonstratedthat regenerationof normal villous synovium doesnot occur (Theoretet a11996. Doyle-Jones et aI2002).

In addition. overzealoususe of motorized apparatus may resultin trauma to the fibrouscapsule.

Many of the problems associatedwith obstructing synovial villi are reduced or eliminated by use of gas distention.

Extrasynovial

extravasation

In most circumstances extravasated fluid dissipates within 24 hours of surgery. Occasionally.when associatedwith large fascial planes such as those adjacent to the femoropatellar joint. this may take longer.

of fluid

Extravasation of irrigating fluid into the subcutis and other fascial planes is a problem commonly encountered when learning arthroscopic techniques but occurs, to some degree, even with the most experienced surgeon, The principal predisposing factors are the shape of instrument portals, excessive perfusion pressure in the presence of obstructed outflow, and instrument manipulation.

Instrument portals in which the incision in the skin and extra-articular tissues is smaller than the opening into the joint will result in dissecting lines of fluid through fascial planes. This can occur quickly and may be controlled effectively by minimizing perfusion pressure at the time of portal creation and also by completing the incision through the skin before the blade is advanced into the joint. The shape of a No. 11 blade assists also, since this creates a triangular incision with the apex of the triangle at the point of the blade.

An obstructed outflow with excessiveperfusion pressure can occur while instruments (particularly large instruments) are being inserted or manipulated. It results also during removal of large fragments, while these are being pulled through the instrument portal. Selective reduction in perfusion pressure at this time will reduce the severity of the problem significantly. Similarly, repeated instrument entry and/or a large range of instrument movement through a portal will open up and/or weaken fascial planes with the same result. Noyes & Spievack (1982) demonstrated that excessiveintra-articular fluid pressure potentiates subcutaneous extravasation of fluid.

The site at which surgeons experience most difficulties with extravasation of fluid is the scapulohumeral joint. Here, caudal instrument portals must traverse not only the skin and subcutis but also several centimeters of muscle and multiple fascial planes. The ability of the periarticular muscles and their fascial planes to imbibe fluid can result in restricted articular distention and thus loss of visibility and surgical access,particularly to lesions which are axial in the joint. Since this joint generally requires a high perfusion pressure to maintain arthroscopic access, particular care should be taken in the creation and use of instrument portals.

Some degree of extra-articular extravasation is inevitable.

The surgeon should be cognizant of its occurrence and plan surgical procedures such that more axially located lesions are treated first. Also, once extravasation has begun surgical access time will be limited. Extrasynovial fluid accumulation can also hamper instrument entry to the stifle joints and both carpal and tarsal tendon sheaths. These areas can be reduced considerably by temporary cessation of ingress fluid and firm massage of fluid from skin portals.

Surgery can then recommence. At the end of surgery large quantities of subcutaneously extravasated fluid may result in excessive tension in skin sutures. This can usually be ameliorated by simple hand massage of the site prior to closure.

Iatrogenic damage to articular

cartilage

Full- and partial-thickness defects in articular cartilage can be created iatrogenically: this occurs most commonly when the joint is being entered and particularly when there is minimal distention. It can be limited by careful technique and use of a conical obturator (rather than a sharp trocar) in the arthroscopic sleeve.

Arthroscopic portals should be made using a blade directly into synovium and the sleeve then can be passed along this pathway with minimal resistance. Use of two hands, one to advance the cannula and the second positioned adjacent to the skin portal to act as a bridge or brake, is recommended. In addition. the surgeon should angle entry of the arthroscopic sleeveand subsequent instruments away from the direct line of articular surfaces. When minor scuffing of the cartilage does occur, it does not appear to be of major significance (Dick et al19 78. McIlwraith & Fessler1978).

Iatrogenic

damage to other tissues

Perisynovial structures may be damaged inadvertently during creation of arthroscope and/or instrument portals. Obviously, the risk is dependent on proximity to portal sites. Elements of the palmar/plantar neurovascular bundle may be traumatised in surgery of the digital flexor tendon sheath. Use of an Esmarchbandage and tourniquet appearsto be a predisposing factor in making the bundle difficult to identify. The surgeon is usually unaware of damage during surgery. Laceration of the palmar/plantar artery may become apparent on release of the tourniquet or by the presence of postoperative hemorrhage during recovery from general anesthesia. This usually is controlled by the application of counterpressure.

Damage to the palmar/plantar nerve may be clinically silent but a painful neuroma may develop at the site.

The carpal s~aths of extensor carpi radialis and common digital extensor tendons can be penetrated by injudicious placement of arthroscope and instrument portals. This is usually apparent to the surgeon as intra- and postoperative distention of the sheath. These sheaths can also be traumatized during removal of large fragments from the craniodistal margin of the radius. The tendon sheath of the common digital extensor is most commonly affected when fragments are removed from the craniolateral margin (intermediate facet) of the radius.

Intrasynovial

instrument

breakage

The most common cause of instrument breakage is the use of inappropriate force. It follows that the incidence of this

problem usually decreasesas a surgeon gains experience. If loose pieces are created within the synovial environment, then fluids should be stopped immediately or the perfusion rate reduced dramatically in order to maintain the fragment in the visible field. An appropriate grasping instrument should then be inserted and the fragment removed. If the piece disappears from view, a systematic search should follow, bearing in mind that most pieces will be metallic and therefore will gravitate to dependent areas (Fig. 16.3). If this fails to locate the debris, then intraoperative radiography should be employed (Fig. 16.4). Magnetic retrievers are available but the limited frequency of their use makes the cost hard to justify.

Prevention is certainly better than cure and the surgeon should avoid excessivebending or lever movements. The use of fixed rather than disposable blade cutting instruments within joints is also recommended. DisposableNo. 15 scalpel blades and the shafts of small angled spoon curettes are considered to be particularly vulnerable to intra-articular breakage.

Ferris-Smith arthroscopic rongeurs are a workhorse of equine arthroscopic surgery. However,if used inappropriately, particularly if attempts are made to twist firmly attached bone, then the pin linking the blades will shear. This disarms the instrument completely but does not produce debris. The pin can be replaced by manufacturers.

Minor trauma to the distal window of the arthroscope will result in cumulative image artifacts and loss of clarity, whereas major trauma can cause complete loss of image.

There is generally no intrasynovial debris. Trauma to the glass is minimized principally by careful surgical techniques and it is vital to maintain a direct view of instruments during surgical procedures. Protection of the distal window is aided also by a slightly recessed arthroscope position within the cannula.

Sudden movement during surgery, which occurs most commonly if an animal begins to wake, can bend or break instruments (Fig. 16.5).

Intrasynovial

foreign material

Tiny metallic fragments have been seen following impact of instruments on the arthroscopic sleeveor sometimesfollowing other "metal on metal" contact. Such debris is usually flushed out with the irrigating fluid or may become embedded in the synovial membrane. No detrimental effects have been recognized.

When needlesare used either to inflate a synovial cavity or to determine sites for appropriate instrument portals. these may cut small pieces of skin. which are carried into the synovial space. This is seen most frequently with stiletted needles. If adhesive drapes are employed. then needles will also carry small pieces of plastic into the synovial space.Such debris is readily flushed from the synovial environment and no adverse effects have been recognized. The risk of pushing larger pieces of plastic into the synovial cavity or adjacent tissues can be reduced by removing the adhesive material from the immediate vicinity of portals. Plastic fragments can result in swelling and discharge when lodged in the subcutis.

Infection The incidence of intrathecal infection following arthroscopic surgery in horses has not been documented but appears rare.

Nonetheless. the potentially devastating consequences of iatrogenic synovial infection mean that aseptic techniques should never be compromised. Direct visualization has been identified as an obvious potential source of contamination but its use is now virtually obsolete. The authors have

implicated inadequate or premature removal of postoperative bandagesin casesof postarthroscopic infection of tarsocrural joints.

There is no consensus on the use of prophylactic antimicrobial drugs with arthroscopic surgery, although the authors all useperioperativemedication. Penicillin preparations are most commonly employed. One frequently used regimen is intravenous sodium benzylpenicillin at >20,000 ill/kg given at the time of anesthetic premedication followed by three similar postoperative doses at 8-hour intervals. Alternatives include a similar protocol with potassium penicillin or use of intramuscular procaine penicillin. When implants are used or if there is a history of recent intra-articular medication, then a combination of penicillin and gentamicin may be employed.

Infected cellulitis and/or fasciitis have beendocumented as uncommon sequelae to arthroscopic surgery. All cases appear to have resolved following systemic administration of antimicrobial drugs. Drainage from skin portals or surgically created sites mayor may not occur (Fig. 16.6):Occasionally, small skin abscessesor suture sinuses are encountered. These almost invariably require no treatment and resolve when sutures are removed, although in some cases a small fibrous lump may persist at the site. Infection can also follow suture removal if this is not performed appropriately.

Postoperative

distention/synovitis

Distention usually signifies persistent synovitis and thus ongoing intra-articular (or intrathecal) problems.However, this is an oversimplification.Thereis variability accordingto site, e.g. in the femoropatellarjoint persistentdistentionis frequentlya sign of continuedintra-articular lesionsbut this

may not be so in the tarsocrural joint. Mild synovial distention may persist without clinical significance. for example when preoperative distention has been long-standing. In the absence of additional clinical signs. such as lameness and reduced or resented flexion. mild distention usually does not justify further investigation or treatment. Marked synovial distention is more likely to result when active intrasynovial lesions persist and re-evaluation is indicated. If causative lesions are not identified. then treatment of the synovitis may be beneficial.

Failure to remove fragments In surgery for removal of traumatic or developmental fragments it is possible. particularly in cases with multiple fragmentation. that all pieces are not removed. There are a number of possible explanations which fall into two broad categories: those fragments which may be identified immediately after surgery and those that are identified later.

The former category includes the simple surgical error of failing to identify lesions. Predisposing factors include inadequate preoperative examination -e.g. failure to identify fragments that may be medial and lateral in a joint and incomplete arthroscopic evaluation of the joint. At some sites -e.g. the dorsoproximal margin of the proximal phalanx fragmentation can be covered by proliferative synovium and may not be apparent until this is lifted with a probe. In some animals there is a distinct dorsal recess of the joint capsule at this site. which also can obscure fragments. At other sites e.g. in animals with multiple. loose osteochondral fragments in the femoropatellar joint -it may be difficult to determine accurately from preoperative radiographs the exact number of fragments which need to be accounted for. It should also be appreciated that some fragments identified radiographically may be embedded within the joint capsule. Current opinion suggests that the dissection necessaryto identify and remove these is not justified. Failure to remove fragments is limited by a thorough preoperative evaluation and the surgeon should ensure that all identified fragments are accounted for at surgery. Within individual joints. loose fragments move frequently to consistent locations. e.g. into the suprapatellar pouch of the femoropatellar joint (Fig. 16.7) or the inter-

condylar fossa of the medial femorotibial joint. These sites should always be assessedat the end of each surgery and debris removed. Use of intraoperative and postoperative radiography has been recommended (and can help avoid litigation), but is not necessarily an assurance.

Lesions that may be identified some time after surgery and misinterpreted as failure to remove fragments include new bone deposits at the site of previous lesions, fragmentation of the same, additional new fragments, and dystrophic mineralization in adjacent soft tissues.

Postoperative cal?sulitis, entheseous new bone, and soft tissue mineralization In many instances capsulitis may be present preoperatively, such as when there is tearing of the fibrous joint capsule (Fig. 16.8) or can be anticipated when articular damage is severe.Problems can also develop with surgical trauma to the joint capsule. Traumatic attempts at removing capsular fragments, trauma to the capsuleduring debridement, particularly with motorized apparatus, and undue trauma to the sensitive transition zone of the joint can all cause problems.

Problems associated with positioning Transient failure to extend hind limb joints on recovery from general anesthesia has been noted following long surgical procedures in which (usually both) hind limbs are fixed in an

extendedposition. Somecasesare thought to be associated with a femoralneuropathyor neuromyopathyinvolving the quadricepsmuscles.Others appearable to fix the proximal joints but fail to extendthe metatarsophalangeal and interphalangealjoints. In both instances,symptoms generally subside quickly. The problem is readily controlled by supportingextendedlimbs during surgeryand by flexing the contralaterallimb while this is not undergoingsurgery.

Pain Anesthetists frequently report that distention of the digital flexor tendon sheath is more painful than joint distention.

Postoperatively, the degree of pain exhibited by horses appears proportional to soft tissue (particularly tendon and ligament) involvement. However,this is usually transient and requires little more than analgesia provided by nonsteroidal anti-inflammatory drugs for 24 hours after surgery. It has been reported that horses with extensive articular or tendon sheath derangements can be maintained on lower levels of inhaled anesthetic agents and have improved recovery by using bupivacaine or mepivacaine for initial synovial inflation.

One author (AJN) now u~es such a protocol routinely.

Generally, most complications can be avoided by good techniqueand none precludethe advantagesof arthroscopic surgery.The problemswith equinearthroscopicsurgeryare mainly technicaland anatomic.Goodtechniquecomeswith training and experienceand the benefits of practice on cadaverlimbs cannotbe overemphasized.

References Allum R. Complications of arthroscopy of the knee. J Bone Joint Surg (Br) 2002; 84B: 937-945.

Armstrong RW. Bolding F. Joseph R. Septic arthritis following arthroscopy: clinical syndromes and analysis of risk factors.

Arthroscopy 1992; 8: 213-223. ' Barber FA. Click J. Britt BT. Complications of ankle arthroscopy. Foot Ankle 1990; 10: 263-266.

Berjano P. Gonzalez BG. Olmedo IF. Perez-EspanaLA. Munilla MG. Complications in arthroscopic shoulder surgery. Arthroscopy 1998; 14: 785-788.

Boardman ND. Cofield RH. Neurologic complications of shoulder surgery. Clin Orthop Del Res1999; 368: 44-53.

Chirwa SS. MacLeod BA, Day B. Intra-articular bupivacaine (Marcaine) after arthroscopic meniscectomy: a randomised double-blind controlled study. Arthroscopy 1989; 5: 33-35.

Dandy OJ. Complications and technical problems. Arthroscopic management of the knee 2nd edn. In: Dandy OJ(ed.). Edinburgh: Churchill Livingstone 1987: 64-71.

D'Angelo GL and Ogilvie-Harris DJ. Septic arthritis following arthroscopy with cost/benefit analysis of antibiotic prophylaxis.

Arthroscopy 1988; 4: 10-14.

DeLee JC. Complications of arthroscopy and arthroscopic surgery: results of a national survey. J Arthroscopic ReI Surg 1985; 1: 214-220.

Dick W, Glinz W, Henche HR, et al. Komplikationen in Arthroskopie.

Arch OrthopTrauma Surg 1978; 92: 69-73.

Doyle-Jones PS, Sullins KE, Saunders GK. Synovial regeneration in the equine carpus after arthroscopic, mechanical or carbon dioxide laser synovectomy. Vet Surg 2002; 31: 331-343.

Fairclough JA. Moran CG. The use of sterile adhesive tape in the closure of arthroscopic puncture wounds: a comparison with a single layer nylon closure. Ann R CoIl Surg Engl 1987; 69:

140-141.

Ferkel RD, Heath DD, Guhl JF.Neurological complications of ankle arthroscopy. Arthroscopy 1996; 12: 200-208.

Ferkel RD, Small HN, Gittins }E. Complications in foot and ankle arthroscopy. Clin Orthop ReIRes 2001; 391: 89-104.

Gosal HS, Jackson AM, Bickerstaff DR. Intra-articular steroids after arthroscopy for osteoarthritis of the knee. Bone Joint Surg (Br) 1999; 81B: 952-954.

Griffin DR, Villar RN. Complications of arthroscopy of the hip. JBone Joint Surg (Br) 1999; 81B: 604-606.

Hussein R, Southgate GW. Management of knee arthroscopy portals. The Knee 2001; 8: 329-331.

Joshi GP,McCarroll SM, Cooney CM, et al. Intra-articular morphine for pain relief after knee arthroscopy. JBone Joint Surg (Br) 1992; 74B: 749-751.

Kelly EW, Morney BF, O'Driscoll SW. Complications of elbow arthroscopy. J Bone Joint Surg (Am) 2001; 83A: 25-34.

Kim TK, Sarino RM, McFarland EG, Cosgarea AJ. Neurovascular complications of knee arthroscopy. Am J Sports Med 2002; 30:

619-629.

Maffulli N, Pintone E, Petricciuolo F. Arthroscopy wounds: to suture or not to suture. Acta Orthop Belg 1991; 57: 154-156.

McIlwraith CW, FesslerJF. Arthroscopy in the diagnosis of equine joint disease.J Am Vet MedAssoc 1978; 172: 263-268.

McIlwraith CWoIn: Diagnostic and surgical arthroscopy in the horse, 2nd edn. Philadelphia: Lea and Febiger; 1990.

Noyes FR, Spievack ES. Extra-articular fluid dissection in tissues during arthroscopy: a report of clinical cases and a study of intra-articular and thigh pressures in cadavers. Am J Sports Med 1982; 10: 346-351.

Proffer DS, Duez D, Daus GP. Synovial fistula of the knee: a complication of arthroscopy. Arthroscopy 1991; 7: 98-100.

Reddy AS, Kritre RS, Yocum LA, et al. Arthroscopy of the elbow: a longterm clinical review. Arthroscopy 2000; 16: 588-594.

Sherman OH, Fo~ JM, Snyder Sf, et al. Arthroscopy "No problem surgery", an 1'I1nalysisof complications in two thousand six hundred and'forty cases. J Bone Joint Surg (Am) 1986; 68A:

256-265.

Small NC. 1986; Complications in arthroscopy: the knee and other joints. Arthroscopy 1986; 2: 253-258.

Small NC. Complications in arthroscopic surgery performed by experienced arthroscopists. Arthroscopy 1988; 4: 215-221.

Theoret CL, Barber SM, Moyana T, Townsend HG, Archer JF.Repair and function of synovium after arthroscopic synovectomy of the dorsal compartment of the equine antebrachiocarpal joint. Vet Surg 1996; 25: 142-153.

Articular cartilage rarely reforms a functional hyaline surface after injury. Most simple cartilage lacerative injuries reach a benign non-healing phase,which remains unchanged over time (Mankin 1982, Hunziker & Rosenberg1996). Deeper cartilage lesions, violating the tidemark and extending into the subchondral bone plate, result in an improved healing response (Campbell 1969). This is largely due to the proliferation of undifferentiated mesenchymal cells from the deeper tissues. In horses, spontaneous healing in cartilage defectsprogressesfrom granulation to fibrous tissue and finally fibrocartilage (Riddle 1970). The fibrous tissue undergoes progressive chondrification to form a fibrocartilaginous mass, looselyattached to the original cartilage edges.The subchondral bone plate occasionally reforms to the same approximate level as the adjacent undamaged bone, but in cartilage lesions that do not involve substantial erosion of the underlying bone. the reformed subchondral bone plate may be higher than the surrounding normal bone plate (Frisbie et aI1999).

Immediately above the reformed subchondral plate, areas of cartilage proliferation predominate. The deeper cartilage layers and surface fibrous tissue generally follow a pattern of decreasing cellularity as the defect matures. At 12 months. type II collagen content approaches normal but proteoglycan levelsare only about half that of normal (Howard et aI1994).

The phenomenon of matrix flow, an intrinsic repair mechanism. may also contribute to healing of articular cartUage defects by centripetal collapse of the perimeter of the lesion (Ghadially & Ghadially 1975). In small defects. this can result in significant reduction in lesion size, but in defects over 9 mm, matrix flow is proportionally insignificant (Convery et al1972).

Depth of injury (full or partial thickness). the size of the defect, location in relation to weightbearing or nonweight bearing areas. and the age of the animal. influence the repair rate and resiliency of new cartilage surfaces. The healing of chondral and osteochondral defectsis more completein young animals. due to the increasedmitotic capacity of chondrocytes, more active matrix synthesis, and closer proximity to the vascular supply in the depths of the articular-epiphyseal complex cartilage (Madsen et al19 83). Examples of improved repair capacity are easily seen in the resurfacing potential following osteochondritis dissecans (OCD) flap removal in

weanlings compared to debridement of articular erosions in adults. The size of the lesion is critical. Convery et al (1972) showed that lesions in the equine femorotibial joint less than 3 mm in diameter healed with little residual deformity (Convery et al 1972). More recently, Hurtig et al (1988) determined that lesions larger than 15 mm2 in surface area (3 x 5 mm rectangle) tended to show reasonably good repair at 5 months but degeneratedwith increasing time (Hurtig et al 1988). These studies indicate that most clinically relevant defects in adults cannot be expected to heal well. The metaplasia of fibrous tissue to fibrocartilage is not always evident, and depending on the time of examination, degeneration to fibrous tissue and later mechanical erosion of the repair tissue can occur. Repair tissue is biomechanically inferior to normal articular cartilage, even though the histologic appearance is often fibrocartilage or even hyaline-like tissue (Ahsan & Sah 1999). Repair tissue generally has significantly less proteoglycan and to some extent type II collagen than normal cartilage. Additionally, the development of subchondral architecture and re-establishment of a tidemark is often irregular and inconsistent. This creates stress risers and susceptibility to cartilage deterioration with normal joint activity. Poor-quallty, relatively short-lived repair cartilage has led to the development of pharmacologic and surgical methods to improve the repair process.

Techniques that enhance the quantity and hyaline characteristics of cartilage repair tissue, would allow the surgeon to improve the long-term outcome when debriding cartilage lesions, particularly in challenging conditions of the stifle, carpus, and shoulder. These techniques should meet several important criteria: 1. be achievable arthroscopically 2. result from local manipulations or use of simple transplant tissues 3. be available to surgical specialists with minimal delay between the diagnosis, decision for surgery, and the institution of the surgical repair 4. be reasonably economical

5. be well tested in a research setting, and able to offer advantages in durability and hyaline quality in the repair

tissue 6. be amenable to the variety of shapes and locations of acute, subacute, and in some instances chronic, cartilage lesions in the joint.

No one arthroscopic system routinely provides all of these advantages. Indeed, those with inherent simplicity such as cartilage debridement, forage, and microfracture meet many of the criteria for simplicity, economy, and minimal delay between diagnosis and repair, but provide lessassuredhyaline cartilage and cartilage durability than many of the more complex transplant methods. Techniques for cartilage repair that are clinically used or have been studied in a research setting can be subdivided into two categories: local manipulative procedures or cell and tissue transplantation techniques.

Local manipulative

procedures

Surgical techniques that rely on simple manipulative procedures include: .cartilage debridement .chondroplasty to remove partial-thickness fibrillation .cartilage reattachment .forage or drilling of the subchondral bone using a drill to provide a uniform diameter perforation through the subchondral plate .microfracture or micropick, which uses a tapered surgical awl to perforate the subchondral bone to open marrow spaces .abrasion arthroplasty,using a motorized burr to remove a uniform layer of eburnated cartilage and bone .spongiallzation (saucerization) of the subchondral plate to open up larger marrow spacesby removal of greater thicknesses of the subchondral bone.

Cartilage debridement Some form of cartilage debridement is common during arthroscopic surgery. As a simple rule, fibrous interpositional ,,' tissue or exposed loose bone should be removed from fullthickness defects. Debridement should continue down to firm, normal appearing, subchondral bone plate. Maintaining as much subchondral bone as possible keeps the bone and overlying cartilage repair tissue contoured to the normal congruency of the opposing joint surface, thereby enhancing the chance of healing cartilage tissue persistence. However, the remaining bone must be viable. Crumbly, brownish bone should always be removed by debridement, using either hand instruments or motorized equipment (Fig. 17.1). At least for the carpus, the amount of residual bone after debridement is an important parameter in determining the prognosis for return to athletic activity (McIlwraith et al19 8 7, McIlwraith 1990). Several studies indicate the advantage of removal of full-thickness fibrillated cartilage. However, more debate sur-

rounds the potential advantagesof debriding partial-thickness cartilage defects down to subchondral bone. in efforts to encourage new cartilage formation from subchondral bone cellular and growth factor elements (Baumgaertner etal1990.

Hubbard 1996). Consensus appears to favor not debriding partial-thickness fibrillated cartilage, but rather leaving it attached to the calcified cartilage and underlying bone (Mcllwraith 1990). Partial-thickness defects have been shown to remain physically unchanged for at least 2 years (Mankin 1982). Conversely, some symptomatic benefit for several months can be derived from chondroplasty of the obviously fibrillated portion of partial-thickness defects,

Repair Methods which is described in more detail later (Thompson 1975, while leaving perpendicular cartilage defectwalls (Fig. 17.2).

Kim et al 1991). In summary. chondroplasty reduces the A controlled study in dogs indicated the benefit of perpenpossibility of damaged cartilage leaching degraded cartilage dicular cartilage walls following debridement, compared to matrix fragments, including collagen, proteoglycan, and beveled edges,which tended to increase the overall dimension cellular components to the synovial fluid. where they of the healing defect (Rudd et al198 7). increase synovitis and concurrent lameness (Thompson Exposed subchondral surfaces can be smoothed either with hand tools, which include curettes, rasps,and rongeurs, 1975).

Full-thickness cartilage lesions are debrided to removeresidual or with motorized burrs. Several types of burr heads are portions of the calcified cartilage layer, which tends available, varying from spherical to oval acromioplasty or to retard the development of well-attached cartilage repairtissue notchplasty blades, which have an elongated profile for from the subchondral bone and surrounding cartilage.The maximum bone removal effect (seeChapter 2). Hand tools are most appropriate tools for cartilage debridement include generally preferred to avoid excessivebone loss; however, for a seriesof spoonand ring curettes that allow adequateremovalof large areas of irregular hard bone, a burr may expedite the residual fibrous areas attached to the subchondral bone procedure and provide a better end result. Since the need for

substantialbone removalis low. an inventoryof a singleburr type is recommended.

Chondroplasty Resection of the protruding surface strands of partialthickness cartilage fibrillation has been promoted as a mechanism to reduce cartilage-derived detritus entering the synovial environment (Thompson 1975. Childers & Ellwood 1979. Kim et al1991. Altman et al1992). Motorized synovial abraders are used to smooth the surface of the more seriously damaged cartilage. The residual cartilage then presents a more uniform non-clefted surface, which may be more durable and incites less synovitis than the large surface area presented by multiple strands of fibrillated cartilage. The concept seems simple. but there is a paucity of evidence documenting any discrete benefit. either in reducing synovial levelsof fragmentedproteoglycan and collagen or in abrogating the symptoms of synovitis. Despite this, the technique has empirical benefits and has been used in equine arthroscopy for trimming extensive areas of partial-thickness fibrillated cartilage. The most frequent site for application in the horse is the stifle (Fig. 17.3). TrocWear ridge OCD in mature horses (>3 years) is often accompanied by fibrillation of the surrounding cartilage and the patella. Chondroplasty has been used to trim these areas to smooth articular cartilage and seems to reduce the incidence of persistent effusion when these horses re-enter competition. No controlled clinical or experimental data support chondroplasty in the horse. so its use remains controversial. It may be preferable to doing nothing. but the resection depth should only involve the fibrillated surface and not be aggressively pursued down to the subchondral bone, since the ensuing repair tissue rarely has the hyaline characteristics of the original deep cartilage layers that were resected.

Chondroplasty cannot be efficiently performed without sharp motorized abraders. Disposable cutting heads are recommended. Attached suction is also helpful in drawing and holding the cartilage fronds into the shaver blades. A "whisker" technique is used to avoid penetration of the intact deeperlayers of cartilage. Benefits in man have beendescribed for months to years after chondroplasty; however. as much as 6 months symptomatic relief has also been attributed to synovial washout using a saline lavage (Hubbf1rd 1996).

Cartilage reattachment Some cartilage flaps in the stifle. hock, and fetlock can be potentially salvagedand reattached (Nixon etal2003a). While not common, an OCDcartilage flap that is relatively smooth and has not detached on its entire perimeter can be elevated and the underlying necrotic cartilage and marrow fibrosis debrided. The flap can then be replaced and secured with polydioxanone (PDS) pins (OrthoSorb, Ethicon-Johnson & Johnson) (Fig. 17.4), or PLLA tacks (Chondral darts, Arthrex.

Naples, FL). Importantly, the OCD flap must be worth reattaching, which requires a smooth congruous surface, minimal fibrillation, and some perimeter continuity. This has

worked satisfactorily on large flaps in the fetlock, hock and stifle, where undulating OCDcartilage has been salvaged by pinning to th~ underlying bone (Nixon et al 2003a). The intervening fi~rosis between cartilage and bony defect should be removed if the procedure can be performed without disturbing remaining perimeter attachment. A 1.2 rom K-wire is then used to drill through the cartilage flap and into the underlying bone (Fig. 17AA). With changes in the degree of flexion of the joint, multiple K-wire perforations can be made, all perpendicular to the surface. The soft tissues are protected by insertion of the K-wire through an arthroscopic guide cannula. The kit also contains five 40 rom long x 1.3 rom diameter pins, each of which can be cut in half to provide two pins approximately 20 rom in length. Except in cases with extremely deep subchondral defects. these pins adequately secure the OCD flap. For deeper lesions, pins can be cut longer. up to the entire 40 rom pin. After carefully drilling the K-wire to end 1 rom short of the anticipated pin length. the

PDS pin is inserted down the cannula and pushed into place using the obturator (seeFig. 17.4B). Approximately 1 mm of pin is left protruding from the surface of the cartilage so it can be flattened level with the articular surface to make a securing head to the PDS pin. Any excess pin can be removed with

a biopsy punch rongeur or other severing rongeur (see Fig. 17AC). Multiple pins are inserted approximately 10 mm apart so that the entire cartilage flap is securely reattached to the subchondral bone. As few as 2 and as many as 10 PDS pins have been inserted (Nixon et al 2003a).

Use of the multi-shot chondral dart system (Arthrex, Naples, FL) for simultaneous multiple anchoring with bidirectional barbed pins is being explored, and appears a satisfactory alternative to PDS pins. Rapid resolution of effusion and subchondral bone lysis on radiographs is a consistent feature (Fig. 17.5), and reformation of the subchondral contour was complete in all but 2 of 16 joints in 12 horses (Nixon et aI2003a). This compares favorably to debridement of OCDlesions,which generallyleavesa depressedsubchondral bone plate at the lesion site. Eleven of the 12 horses were not

cartilage repair. It is simple and inexpensive. However, in a controlled study using arthrotomy approaches, it did not provide superior healing in defects on the equine third carpal bone (Vachon et aI1986). Similarly, it did not benefit healing of partial-thickness cartilage defects in the same third carpal bone model (Shamis et al1989).

Subchondral bone forage or drilling was introduced into human arthroscopy in the 1960s (Pridie 1959, InsalI1974).

Since then it has been frequently used to improve cartilage quality following chondromalacia of the patella (Childers & Ellwood 1979). Historically, the most frequent site for subchondral bone forage in the horse was the sclerotic rim associatedwith subchondral cystic lesions (Mcllwraith 1983, White etal1988). The use of this technique has diminished, as reports of cyst enlargement subsequent to forage have been published (Howard et al 1995), and surgeons have found difficulty in arthroscopically making drill holes that are perpendicular to a defect. The technique has largely been replaced by microfracture.

Microfrocture

lame, and it appearedthat reattachment was a valuable option to salvage the dissectedhyaline cartilage flap in selectedcases.

Forage Forageor subchondralbonedrilling has beenexploredin the horse.Therationaleis to perforatethe subchondralboneand allow entry of subchondralmarrow elements.vasculature. and growth factors to the defect,which then contribute to

The use of microfracture. or micropick as it has been referred to in equine arthroscopy, has many of the advantages associated with forage, including focal penetration of the dense subchondral plate to expose defects to the benefits of cellular and growth factor influx, as well as improving anchorage of the new tissue to the underlying subchondral bone and to some extent the surrounding cartilage (Rodrigo et al 1994, Frisbie et al 1999, Breinan et al 2000). The simplicity of microfracture comes from the use of a tapered awl (Unvatec, Largo, FL; Arthrex, Naples, FL), instead of a parallel-sided twist drill. Using the awl abrogates the need for powered instrumentation to perforate the subchondral bone. giving additional control over the placement of the perforation, and also allowing the formation of a tapered entry to the subchondral marrow spaces.The microfracture awls should penetratethe subchondral bone deepenough (2-4 mm) to provide ready access to the marrow spaces, thereby maximizing cellular and anabolic growth factor delivery (Fig. 17.6). The microfracture awl also tends to make a crater in the subchondral bone. which may playa role in better attachment of, the cartilage repair tissue (Lee et al 2000).

Microfracture, 'holes are generally placed 3-5 mm apart and cover the entire debrided area in a cartilage lesion (see Fig. 17.6). It is also important to microfracture the subchondral bone on the perimeter of the cartilage lesion to encourage new tissue at the junction of repair tissue and residual cartilage. The technique has become popular in human arthroscopy (Rodrigo et a11994, Blevins et a11998, Steadman et al2001. 2002), and is now frequently compared to chondrocyte transplantation as one of the two most frequently employed techniques to improve cartilage healing.

One experimental study in the horse documented improvements in the quantity of tissue and the hyaline quality of the cartilage (collagen type n content) at 4 and 12 months after micro fracture of full-thickness cartilage defects (Frisbie et al 1999). Improvements in early gene expression of cartilage

specificmarkers were evident within 8 weeks of microfracture (Frisbie et aI2003).

The technique clearly has advantages over forage and transplantation methods, including ease of application using arthroscopy, use of a simple hand tool. the relative economies of the equipment required, the simplicity and minimal planning required to use the technique. and the apparent increase in cartilage repair tissue that deve~ps after the procedure. ...

Results of microfracture in equine clinical syndromes have not been published. However, individual experiences with micro fracture have included focal and severe cartilage defects on the carpal bones, femoral condyles and trochlear ridges. proximal sesamoidsand distal metacarpal/metatarsal condyles, and the trochlear ridges of the talus (seeFig. 17.6).

Anecdotal evidence of improved cartilage healing has been derived from the use of microfracture at each of these sites. Further case numbers and comparative studies are required before a definitive recommendation can be made for its use. Of the available local manipulative procedures that follow debridement of cartilage lesions, microfracture appears to have the most benefit with the least cost and complexity.

Abrasion arthroplasty Abrasion arthroplasty uses a motorized burr to resect a uniform layer of residual cartilage and eburnated subchondral bone Gohnson 1986. 2001). Eburnated bone is often characterized by a surface layer of non-viable bone Gohnson2001). which forms a barrier to effective cartilage repair. Abrasion arthroplasty. a.it was originally conceived Gohnson 1986). removes this superficial layer of dead subchondral plate. thereby exposing vascular tufts from the deeper marrow spaces. In addition. it provides access to a viable pool of marrow-derived stem cells that could participate in cartilage repair. Use of motorized equipment is necessary due to the sclerosis associated with subchondral bone eburnation. The result is a coalescing group of fibrocartilaginous tissue tufts Gohnson 1986. 1991. Menche et al1996). Although. it has been used to a limited extent. particularly for areas of eburnation of the trochlear ridges of the talus. widespread experience with this technique in horses is lacking. and there are no published reports documenting other possible sites for abrasion arthroplasty. The utility of arthroplasty has been reduced by the introduction of marrow stimulating techniques such as micro fracture. which perforate the sub-

chondral bone plate at multiple sites over eburnated or debridedcartilageregionsand allow reformationof cartilage repair tissue while still maintaining the subchondralplate contour.

Spong;al;zat;on Spongialization can be considered an extension of abrasion arthroplasty. since extensive areas of the subchondral bone plate and overlying cartilage are removed (Ficat et aI1979).

Resection extends through the subchondral bone. essentially exposing the defect to the marrow spaces that then participate in cartilage repair. Given the benefitsto maintaining subchondral bone architecture. we do not consider there is any indication for the use of spongialization in equine arthroscopy.

Transplantation

procedures

In mature horses most debriding and marrow stimulatory techniques result in fibrocartilage formation with modestbiomechanical capabilities. The use of supplemental free cells. various vehicles containing cells. or entire tissues such as periosteum or cartilage grafts have been advocatedto improve the modest impact that these local manipulative procedures have on both the quality and quantity of cartilage repair tissue. Transplantation procedures can be classifiedaccording to the origin of transplanted tissue: (1) periosteal transplantation. (2) perichondrial transplantation. (3) autogenous cartilage (articular. sternal. or auricular) transplantation.

(4) osteochondral transplantation. (5) chondrocyte transplantation. and (6) pluripotent stem cell transplantation.

There is a considerable body of literature that describesthe potential advantages derived from transplantation of whole tissues. The disadvantages with these methods and the tissues they transfer predominantly hinges on the limited application by arthroscopic means. Arthrotomy is required for insertion of periosteum. perichondrium. intact cartilage. and osteochondral grafts. Similarly. tissue-engineeredcartilage analoges such as chondrocytes cultured on collagen. polygiycolic acid (PGA). or PGA/polylactic acid (PGA/PLA). or newer synthetic materials such as hyaluronan membranes. are also difficult or impossible to implant arthroscopically. This serious practical limitation has tempered interest in using thesrimplants.

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for focal cartilage injury in the knee has been reported (Niedermann et a1198S, O'DriscoII1998, 1999). On balance, the disadvantage of an arthrotomy for insertion of periosteal grafts in man is not outweighed by the potential benefits in hyaline cartilage. Additionally, in an equine study, periosteal transplants to the stifle occasionally induced vascularization of the healing cartilage, which led to exuberant tissue and mineralization in the repair, both of which were detrimental to the formation of durable hyaline cartilage (Nixon et al 2002, unpublished data).

In other equine studies, autogenous periosteal transfer to the radial carpal bone provided no additional advantage to defects healing spontaneously (Vachon et a11991a, 1991b).

Moreover, there was a tendency for synovial pannus and adhesions to overwhelm the healing defects (Vachon et al 1991b). In other research studies, the application of autogenous periosteal grafts as a mechanism to secure autogenous chondrocyte grafts in full-thickness cartilage defectsprovided better cartilage repair than periosteal graft alone (Breinan et al 1997), and is probably the only widespread clinical application of periosteal grafts in cartilage repair in man (Brittberg et al 1994). In horses, there are no reports of successful clinical application of periosteal grafting in cartilage repair.

Perichondrium Severalresearchgroups have studied the use of perichondrium rather than periosteum for improved cartilage repair (Ohlsen & Widenfalk 1983. Kwan et al 1989. Coutts et al 1992.

Bruns eta11992. Ritsilaet a11994. Bouwmeester etaI2002).

While these tissues behave similarly to periosteum. various investigators considered they were more programmed toward a chondrocyte lineage. and should hold special benefits for cartilage repair. In a study comparing free grafts of perichondrium to periosteumimplanted in equinejoints. perichondrium did not produce significant cartilage (Vachon et al 1989).

Perichondrial grafting holds few benefits over other techniques. and is rarely mentioned in clinical applications in horses or man (Ritsila et a11994. Bouwmeester et aI2002).

OsteochondralGrafts ~

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Chondrocyte transplantation Autogenous chondrocyte implantation is one of the few FDAapproved tissue engineering techniques to treat articular

--

articular cartilage biopsies are harvested arthroscopically from minimally weightbearing regions of the injured knee, propagated ex vivo in cell culture, and later implanted under an autogenous periosteal tissue patch (Brittberg et al1994).

The indications for the procedure include previously failed surgery, large lesions, and minimal secondary osteoarthriti~ (Brittberg et al 2001, King et al 2002). These indications include extensive focal defects and osteochondritis dissecans (Robert & Bahuaud 1999, Peterson et al 2000,2002). The delivery of cells requires an arthrotomy, and the harvest and suture attachment of a periosteal patch is tedious and technically demanding. Both factors complicate the surgery as well as the postoperative course. There are still several unresolved questions, including the ideal number of chondrocytes to transplant and most particularly the role of the periosteum in the technique. The periosteum has been shown by others to contribute to cartilage healing (O'Driscoll1999).

One study compared chondrocyte transplantation secured with a periosteal patch to defects treated with periosteal patches without chondrocyte implantation, and found no difference between the healing tissue after a year (Breinan et al19 97). Clinical outcome in multiple studies in man have reported good to excellent results, with 80-90% return to pain-free function for femoral condyle defects and slightly lower successrates for lesions on the patella (Minas 1998, 2001, Richardson Evans et al1999, Minas & Peterson 1999, Peterson etal2000, 2002. Minas & Chiu 2000, Brittberg et al 2001, Lindahl et al 2001). Long-term studies are becoming available for patients treated with autogenous chondrocyte repair, one of which shows that 84% of patients had a successful outcome from 2 to 9 years after the procedure (Richardson et al1999, Peterson et al2000, 2002, Brittberg et al2001, Minas 2001).

In horses,chondrocyte implantation techniques have been examined in a variety of matrix carrier vehicles (Hendrickson et al1994, Sams & Nixon 1995, Fortier et aI2002a). Initial research trials indicated the significant effect of chondrocyte implantation using a fibrin vehicle (Hendrickson et aI1994).

Subsequent methods to enhance the matrix vehicle, using tissue-engineering approaches with collagen matrix scaffolds, did not provide a satisfactory improvement in repair (Sams & Nixon 1995, Sams et al 1995). The addition of anabolic growth factors was initiated to bolster the matrix elaborated by transplanted chondrocytes. Initial studies used vehicles containing growth factors, but no cells, with the expectation that a repositofH of a growth factor would enhance repair tissue from pluclpotent cells arising from the subchondral bed (Nixon et aI1999). Insulin-like growth factor-1 (IGF-1) has been extensivelyevaluated for its effect on chondrocyte activity (Luyten et al1988, Nixon et al 1998, Fortier et al 1999), although other growth factors have also been found to stimulate proliferation, migration, matrix synthesis, and differentiation. Many of these growth factors, including basic fibroblast growth factor,transforming growth factor-g (TGF-g), and epidermal growth factor, induce beneficial effects to cartilage healing (Mankin et al1991, van den Berg 1995, Trippel et al1996, O'Connor et al2000). Local treatment of

ubiquitous matrix that further isolates them from the host immune response. Comparison of studies in the horse clearly documented the benefits of allograft cells compared to defects without cells (Hendrickson et a11994). Allograft chondrocyte persistence has also been assessedin horses, using a marker of male cells (the SRY gene) to track the survival of male allograft transplants in female recipients (Ostrander et al 2001, Hidaka et al 2003). This polymerase chain reactionbased assayindicated persistence of equine allograft cells at 8 months, ranging from 0 to 28% (Hidaka et al 2003). Most assaysof the persistence of allograft cells in more vascularized locations indicate rapid cell loss Oackson & Simon 2002).

Despite cell loss, enhanced repair can be induced, either by the initial impact of the allograft cells, or the later enhanced elaboration of paracrine growth factors and matrix that may improve the quality of cartilage repair. Clearly, however, an autogenous cell would be an advantage. Recent studies in the horse, using autogenous chondrocytes seededonto a collagen membrane and inserted via arthrotomy, have yielded encouraging results (Frisbie 2003, unpublished data). Use of bone marrow-derived pluripotent mesenchymal stem cells (MSCS)is one solution to the limited availability of predetermined chondrocytes.

Pluripotent mesenchymalstem cell transplantation

chondral or osteochondral defects with growth factors has the potential to stimulate a more durable and hyaline-like repair, provided the defect penetrates to the level of the subchondral bone, Despite the interest in many different growth factors, IGF-1 has the most potential to provide practical results in cartilage repair (described in more detail later).

Studies in the horse indicate that IGF-1 combined with chondrocytes results in superior cartilage repair compared with other cell-based methods for repair (Fortier et aI2002a).

Practical application of chondrocyte and growth factor transplantation techniques is being pursued in the horse. An integral part of chondrocyte implantation is the development of a banked source of allograft chondrocytes. Use of allograft cells raises questions concerning the immune response.

Several studies document an immune reSponse to the chondrocyte cell wall, which is both predictable and aggressive (Moskalewski et a11966, Elves 1974, Gertzbein et a11977, Kawabe & Yoshinao 1991, Lance et al 1993). However, chondrocytes implanted in vehicles,such as fibrin, hyaluronan, or synthetic composites. are immediately protected from the immune response (Heyner 1969). Additionally, chondrocytes are somewhat unique in that they are implanted in a relatively poorly vascularized region. Synovial fluid bathes the surface of cartilage repair areas,and the only direct access to vascularity comes through the defect base. To this end, defects that do not penetrate the subchondral bone plate, and are implanted with chondrocytes in an attachment vehicle, have some immediate protection against the immune cascade. Furthermore. chondrocytes rapidly elaborate a

The use of a pluripotent cell to enhance cartilage repair has been investigated for severalyears. Initial studies in the rabbit indicated MSCscould enhance cartilage repair (Wakitani et al 1994, Grande et al 1995, Johnstone & Yoo 1999, 1m et al 2001). Follow-up work in small animals demonstrated that MSCs can be partially induced down chondrocyte lineages (Butnariu-Ephrat et aI1996). Studies in the horse indicate that, bone marrow-derived MSCs can be harvested an4i cultured for sufficient time in defined media to differentiate toward a chondrocyte lineage (Fortier et a11998f. However, in-vivo studies in the horse report little advantage after 8 months in a femoral trochlear ridge cartilage defect model (Wilke et al2001). Moreover,bone marrow-derived stem cells from horses are tedious to culture, and accumulation of sufficient numbers to graft large articular defects can take up to a month. Additionally, the yield from mature horses (representing the majority of a clinic caseload) is reduced over yields fr~m immature animals, making the accumulation of sufficient cells for grafting age-dependent but generally very slow (Fortier et al 1998, Huibregtse et al 2000). Overcoming these limitations will require further research before this source of cells becomes a practical replacement method for fully differentiated chondrocytes.

Growth factors Several naturally occurring polypeptide growth factors play an important role in cartilage homeostasis.The differentiating and matrix anabolic promoting activity of IGF-1 and TGF-B are particularly important in counteracting the degradatory and catabolic activities of cytokines, serine proteases..and neutral metalloproteases (Fortier et al 1997. Nixon et al 1998). The manipulation of this balance in diseaseconditions

such as arthritis and acute cartilage injury may be possible by exogenous administration of IGF-l and TGF-B(Tyler et al1989.

Nixonetall998.

1999, Fortier et alI999). In-vitro chondrocyte monolayer and cartilage explant culture studies show IGF-l and TGF-B generally stimulate matrix elaboration and mitogenic effects (Fortier et a11997, Frisbie & Nixon 1997.

Nixon et aI1998). Three-dimensional culture assessmentof the impact of these same growth factors on equine chondrocyte metabolism. using fibrin gels to provide a stable suspension culture resembling cartilage matrix (Fortier et aI1999), also confirmed enhanced proteoglycan and collagen synthesis and resulted from exposure to IGF-l concentrations of 50-100 ng/ml and TGF-B levels of 5-10 ng/ml (Fortier et al 1997. Fortier et alI999). Further studies in the horse have largely focused on IGF-l, since TGF-B was toxic at moderate concentrations and IGF-I was stimulatory to chondrocyte metabolism. even when present in excess concentrations (Fortier et al2002b). In-vivo investigations of articular repair following TGF-B administration also showed synovitis and osteophyte development. both of which are alarming features of TGF-Buse in these animal studies (van den Berg et al199 3. van Beuningen et a11994. van den Berg 1995). Given these results. IGF-l was selected as a suitable growth factor for invivo studies in the horse. Slow-releasedelivery of IGF-l within the cartilage defect. to facilitate matrix production in local and transplanted chondrocytes, provides a mechanism for enhanced cartilage repair (Nixon et alI999). Elution studies using IGF-l-laden equine fibrin indicated that stimulatory levels of IGF-l (greater than 50 ng/ml) remained for up to 3 weeks following an initial loading dose of 25 ~ (Foley & Nixon 1997). In-vivo evaluation of a fibrin vehicle loaded with 2 5 ~g of IGF-l and polymerized in situ in cartilage lesionS in the femoropatellar joints, showed improved cell population with a more cartilage-like architecture after 6 months (Nixon et alI999). However. markers of hyaline cartilage such as type II collagen had increased to only 47%. far short of the 90% expected in normal articular cartilage. Nevertheless. simple fibrin vehicle grafts used in control stifles did not significantly enhance healing. with mean type II collagen content of 39%, similar to the healing in empty full-thickness defects (Hendrickson et alI994). Other studies using injected combinations of IGF-l and pentosan polysulfate show attenuation of the symptoms of synovitis in osteoarthritis models in dogs (Rogachefsky et alI993). In geiIeral, IGF-l seems to have better application in combination with chondrocyte grafts. where more complete cartilage repair develops (Fortier et al 2002a). Evaluation of stifle lesions 8 months following implantation of a mixture of chondrocytes and 25 ~ of IGF-I. showed considerably improved joint repair, with 58% type II collagen and better cartilage integration at the defect edges (Fortier et al 2002a).

Clinical applications of chondrocyte transplantation Clinical resurfacing trials in horses have used a regimen of autogenous fibrin laden with 50 IJ.gof IGF-l and 30 million chondrocytes per ml of fibrin.

Preparation of autogenous fibrinogen. The horse's jugular vein area is aseptically prepared for whole blood collection. A commercial 500 ml blood pack containing acid citrate dextrose (Travenol) is used for whole blood harvest.

The blood cell~are allowed to settle in a refrigerator for several hours before titrating off the plasma. The cells are then discarded and the plasma aliquoted to 50 ml centrifuge tubes prior to freezing at -80째C overnight. The plasma is then allowed to slowly thaw in a refrigerator for 30-36 hours, and the fibrinogen-rich cryoprecipitate collected by centrifugation at 3000 g at O째Cin a swinging bucket centrifuge. Approximately 0.5-0.75 ml of cryoprecipitate fibrinogen can be collected from each 50 ml tube of plasma (Fig. 17.8A). As a precaution against contamination at collection or handling, a bacterial culture is submitted prior to using the product for cell grafting. Fibrinogen can be stored refrigerated for several days, or frozen for later use.

Chondrocyte banking. Chondrocyte isolation requires the services of a laboratory equipped for cell culture. Allograft chondrocytes are harvested from foals destroyed for

noninfectious disease, most frequently irreparable fractures or severecongenital deformities. Cartilage slices are harvested aseptically from the stifle, shoulder, or elbow, and the cells isolated from their matrix by overnight collagenase digestion (Nixon et alI992). The cells are then counted and dimethyl sulfoxide (DMSO)added to the culture medium prior to freezing and storage in liquid nitrogen. When the cells are required, 48 hours lead time is neededto thaw the cells and then briefly culture to allow removal of any dead cells, before collection for use in surgery.

Clinical application. At the time of surgery the chondrocytes are mixed with fibrinogen and stored at 4째C. IGF-l (50 flg) is added to 250 or 500 units of activated thrombin, to provide a two-component system for immediate injection.

Thrombin is obtained from Sigma-Aldrich Corporation (Fig. 17.8B), and the lyophilized powder reconstituted with calcium chloride (40 mmol), and sterilized by filtration through a 0.2 ~ millipore syringe filter. At surgery, the polymerization process develops immediately upon injection of the two components into the articular defect (Fig. 17.8C).

Arthroscopic lesion debridement is followed by gas insuffiation for the few minutes required for fibrin injection. This allows drying of the defect using Q-tips or surgical sponges applied

to the end of a hemostat. Drying of the subchondral bed and surrounding intact cartilage allows better application of the naturally adhesiveproperties of fibrin. The polymerizing liquid nature of fibrin allows contouring of the cell transplant to the irregularities of many joint surfaces (Fig. 17.9).

Clinical application of chondrocyte grafting in horses has included traumatic cartilage lesions of the third carpal bone, fetlock metacari'al condylar fractures,and OCDor subchondral cystic lesions qF the fetlock (14 horses) and stifle (43 horses).

Chondrocyte augmentation following third carpal bone slab fracture repair and shoulder OCD debridement have resulted in few horses capable of returning to athletic work. However, results for stifle OCD and subchondral cyst grafting of the stifle and fetlock have been generally good. Complete radiographic filling has occurred in more than half of the stifle subchondral cysts radiographed at or beyond 12 months postoperatively (Fig. 17.10), and 73% of stifle subchondral cysts, including failures of previous simple debridement alone, have been in athletic work for a minimum of 2 years. Similarly, fetlock subchondral cYstshave been treated using arthroscopic extirpation and grafting (Fig. 17.11). Radiographic filling of the fetlock cysts can be slow, and residual deeperlytic regions can remain despite athletic performance (Fig. 17.12). All but

two horses more than 12 months postoperative have entered athletic work. Both of these caseshad evidence of remodeling due to osteoarthritis at the time of grafting.

Future directions Numerous tissue-engineered cartilage composites have been developed for cartilage repair during the past 10 years, using the concept of artificial implantable hyaline-like cartilage.

None of these techniques have entered clinical practice. The predominant reason for failure with preformed cartilage analoges is the lack of integration of the cartilage-like material to the subchondral bone and, most particularly, the surrounding cartilage. Most composites that begin to take on the biomechanical characteristics of cartilage before integration will fail. For this reason, soft, self-polymerizing and self-contouring grafts that are placed as liquids or soft composites and attach to the surrounding tissues are more likely to succeed.Thesegrafts accumulate intrinsic mechanical competency as the cells synthesize their own matrix, which allows a better stress transition to adjacent cartilage. Equine

studies with autogenous chondrocytes cultured on collagen matrix allow implantation of a soft composite, and the results have beenencouraging. Allograft chondrocytes can potentially offer younger, more metabolically active cells, which have better replicative capacity. However, as methods to induce chondrogenesisin MSCsbecomemore efficient, use of an autogenous cell of bone marrow origin that has been extensively programmed using a combination of growth factor peptide and gene modulations may provide a differentiated chondrocyte (Nixon et al 2000). Moreover, the addition of anabolic growth factors to the cell mixture, including IGF-l and several from the transforming growth factor superfamily, particularly BMP7 and/or BMP2, will promote long-term matrix synthesis and chondrocyte persistence (Nixon et al 2000). Studies of IGF-I and BMP7 gene enhanced chondrocyte function in equine models suggest both stimulate extraordinary early healing, be~nd that seen in unstimulated chondrocyte implanted cartilage defects (Goodrich et al2002, Hidaka et al 2003). Long-term provision of an anabolic growth factor (IGF-I) and an anticatabolic factor (1L-1 receptor antagonist) using gene therapy has shown encouraging results, at least in vitro (Nixon et al 2004b).

References Ahsan T. Sah RL. Biomechanics of integrative ~artilage repair.

Osteoarthritis. Cartilage 1999; 7: 29-40.

Altman. R.D.. Kates. J. Chun LE et aI () Preliminary observations of chondral abrasion in a canine model. Ann RheumDis 1992; 51:

1056-1062.

Aubin PP. Cheah IlK. Davis AM. Gross AE. Long-term followup of fresh femoral osteochondral allografts for posttraumatic knee defects. Clin. Orthop 2001; 391 (Suppl): S318-S327.

Baumgaertner MB. Cannon WD. Vittori JM. Schmidt ES. Maurer RC. Arthroscopic debridement of the arthritic knee. Clin Orthop 1990; 253:197-202.

Blevins FT. SteadmanJR. Rodrigo D. Silliman J. Treatment of articular cartilage defects in athletes: an analysis of functional outcome and lesion appearance. Orthopedics 1998; 21: 761-767.

Bodo G. Hangody L. Szabo Z. et aI. Arthroscopic autologous osteochondral mosaicplasty for the treatment of subchondral cystic lesion in the medial femoral condyle in a horse. Acta Vet Hung 2000: 48: 343-354.

Bodo G. Kaposi AD. Hangody L. et al. The surgical technique and the age of the horse both influence the outcome of mosaicplasty in a cadaveI equine stifle model. Acta Vet Hung 2001; 49: 111-116.

Bodo G. HangiIdy L. Modish. Hurtig M. Autologous osteochondral grafting (mosaic arthroplasty) for treatment of subchondral cystic lesions in the equine stifle and fetlock joints. Vet Surg 2004; 33: 588-596.

Bouwmeester PS. Kuijer R. Homminga GN. Bulstra SK. GeesinkRG. A retrospective analysis of two independent prospective cartilage repair studies: autogenous perichondrial grafting versus subchondral drilling 10 years post-surgery. J Orthop Res 2002; 20: 267-273.

Breinan HA. Martin SD. Hsu HP. Spector M. Healing of canine articular cartilage defects treated with microfracture. a type-II collagen matrix. or cultured autologous chondrocytes. J Orthop Res2000; 18: 781-789.

Breinan HA. Minas T. Hsu HP. et al. Effect of cultured autologous chondrocytes on repair of chondral defects in a canine model.

J Bone Joint Surg 1997; 79A: 1439-1451.

Brittberg M. Lindahl A. Nilsson A. et al. Treatment of deepcartilage defects in the knee with autologous chondrocyte transplantation.

NewEngiJMed 1994; 331: 889-941.

Brittberg M. Tallheden T. Sjogren-JanssonB. Lindahl A. PetersonL. Autologous chondrocytes used for articular cartilage repair: an update. Clin Orthop 2001; 391 (Suppl): S337-8348.

Bruns J. Kersten P. Lierse W. Silbermann M. Autologous rib perichondrial grafts in experimentally induced osteochondral lesions in the sheep-knee joint: morphological results. Virchows Archiv A Pathol Anat 1992; 421: 1-8.

Butnariu-Ephrat M. Robinson D. Mendes DG. Halperin N. Nevo Z. Resurfacing of goat articular cartilage by chondrocytes derived from bone marrow. Clin Orthop 1996; 330: 234-243.

Campbell CJ.The healing of cartilage defects. Clin Orthop 1969; 64: 45-63.

Childers JC. Ellwood SC. Partial chondrectomy and subchondral bone drilling for chondromalacia. Clin Orthop 1979; 144: 114-120.

Chu CR. Convery FR. Akeson WH. Meyers M. Amiel D. Articular cartilage transplantation. Clinical results in the knee. Clin Orthop 1999; 360: 159-168.

Convery FR. Akeson WHo Keown GH. The repair of large osteochondral defects. Clin Orthop 1972; 82: 253-262.

Coutts RD. Woo SLY. Arniel D. von Schroeder HP. Kwan MK. Rib periochondrial autografts in full thickness articular cartilage defects in rabbits. Clin Orthop 1992; 275: 263-273.

Elves MW. A study of the transplantation antigens on chondrocytes from articular cartilage; JBone Joint Surg 1974; 56-B: 178-185.

Elves MW. Zervas J. An investigation into the immunogenicity of various components of osteoarticular grafts. Br J Ex Path 1974; 55: 344-351.

Ficat RP. Ficat C. Gedeon P. Toussaint JB. Spongialization: a new treatment for diseased patellae. Clin Orthop 1979; 144: 74-83.

Foley RL. Nixon AJ. Insulin-like growth factor-l peptide elution profiles from fibrin polymers determined by high performance liquid chromatography. AmJ Vet Res 1997; 58: 1431-1435.

Fortier LA. Lust G. Mohanuned HO. Nixon AJ. Coordinate upregulation of cartilage matrix synthesis in fibrin cultures supplemented with exogenous insulin-like growth factor-I. J Orthop Res 1999: 17: 467-474.

Fortier LA. Lust G. Mohammed HO. Nixon AJ. Insulin-like growth factor-I enhances cell-based articular cartilage repair. J Bone Joint Surg 2002a; 84-B: 276-288.

Fortier LA. Nixon AJ. Lust G. Phenotypic expression of equine articular chondrocytes grown in three-dimensional cultures supplemented with supraphysiologic concentrations of insulinlike growth factor-I. AmJ Vet Res 2002b; 63: 301-305.

Fortier LA. Nixon AJ. Mohammed HO. Lust G. Altered biological activity of equine chondrocytes cultured in a tl1iee-dimensional fibrin matrix and supplemented with transforming growth factor Bl. AmJ Vet Res 1997; 58: 66-70.

Fortier LA. Nixon AJ. Williams J. CableCS. Isolation and chondrocytic differentiation of equine bone marrow-derived mesenchymal stem cells. AmJ Vet Res 1998; 59: 1182-1187.

Frisbie DD. Nixon AJ. Insulin-like growth factor 1 and corticosteroid modulation of chondrocyte metabolic and mitogenic activities in interleukin I-conditioned equine cartilage. Am J Vet Res 1997; 58: 524-530.

Frisbie DD. Oxford IT. Southwood L. et al. Early events in cartilage repair after subchondral bone microfracture. Clin Orthop 2003; 215-227.

Frisbie DD. Trotter GW. Powers BE. Arthroscopic subchondral bone plate microfracture technique augments healing of large chondral defects in the radial carpal bone and medial femoral condyle of horses. Vet Surg 1999; 28: 242-255

Gertzbein SD. Tait JR. Devlin SR. Argue S. The antigenicity of chondrocytes. Immunology 1977; 33; 141-145.

Ghadially JA. Ghadially FN. Evidence of cartilage flow in deepdefects in articular cartilage. Arch B Cell Path 1975; 18; 193-204.

Ghazavi MT. Pritzker KP. Davis AM. Gross AE. Fresh osteochondral allografts for post-traumatic osteochondral defects of the knee.

J Bone Joint Surg 1997; 79-B; 1008-1013.

Goodrich LR. Nixon AJ. Hidaka C. Robbins PD. Evans CH. Enhanced early healing of articular cartilage with genetically modified chondrocytes expressing insulin-like growth factor-I. Vet Surg 2002; 31; 482.

Grande DA. Southerland SS. Manji R. et al. Repair of articular cartilage defectsusing mesenchymal stem cells. Tissue Eng 1995; 1; 345-353.

Gross AE. Aubin P. Cheah HK. Davis AM. Ghazavi MT. A fresh osteochondral allograft alternative. J Arthroplasty 2002; 17;

50-53.

Hangody L. FeczkoP.Bartha L. Bodo G. Kish G. Mosaicplasty for the treatment of articular defects of the knee and ankle. Clin Orthop 2001a; 391 (Suppl); S328-S336.

Hangody L. Kish G. Karpati Z. Szerb I. Udvarhelyi I. Arthroscopic autogenous osteochondral mosaicplasty for the treatment of femoral condylar articular defects. Knee Surg Sports Traumatol Arthrosc 1997; 5: 262-267.

Hangody L. Kish G. Karpati Z. et aI. Mosaicplasty for the treatment of articular cartilage defects: application in clinical practice.

Orthopedics 1998; 21: 751-756.

Hangody L. Kish G. Modis L. et al. Mosaicplasty for the treatment of osteochondritis dissecans of the talus: two to seven year results in 36 patients. Foot Ankle Int 2001b; 22: 552-558.

Hendrickson DA. Nixon AJ. Grande DA, et al. Chondrocyte-fibrin matrix transplants for resurfacing extensive articular cartilage defects. J Orthop Res 1994; 12: 485-497.

Heyner S. The significance of the intercellular matrix in the survival of cartilage allografts. Transplantation 1969; 8: 666-677.

Hidaka C. Goodrich LR. Chen C-T, et aI. Acceleration of cartilage repair by genetically modified chondrocytes over-expressing bone morphogenetic protein-7. J Orthop Res 2003; 21:

573-583.

Howard RD. Mcllwraith CWoTrotter GW. Arthroscopic surgery for subchondral cystic lesions of the medial femoral condyle in horses: 41 cases (1988-1991). J AmVet Med Assoc 1995; 206:

842-850.

Howard RD. Mcllwraith CWoTrotter GW, et al. Long-term fate and effects of exercise on sternal cartilage autografts used for repair of large osteochondral defects in horses. Am J Vet Res 1994; 55:

1158-1168.

Hubbard MIS. Articular debridementversus washout for degeneration of the med1 femoral condyle. J Bone Joint Surg 1996; 78:

217-219.

Huibregtse BA. }ohnstone B, Goldberg VM. Caplan AI. Effect of age and sampling site on the chondro-osteogenic potential of rabbit marrow-derived mesenchymal progenitor cells. J Orthop Res 2000; 18: 18-24.

Hulse DA. Miller D. Roberts D. et aI. Resurfacing canine femoral trochleoplasties with free autogenous periosteal grafts. Vet Surg 1986; 15: 284-288.

Hunziker BE. Rosenberg LC. Repair of partial-thickness defects in articular cartilage: cel.lrecruitment from the synovial membrane.

J Bone Joint Surg 1996; 78-A: 721-733.

Hurtig M, Pearce S. Warren S. Kalra M, Miniaci A. Arthroscopic mosaic arthroplasty in the equine third carpal bone. Vet Surg 2001; 30: 228-239.

Hurtig MB. Experimental use of small osteochondral grafts for resurfacing the equine third carpal bone. Equine Vet J 1988; (SuppI6): 23-27.

Hurtig ME, Fretz PB, Doige CE,Schnurr DL. Effects of lesion size and location on equine articular cartilage repair. Can J Vet Res1988; 52: 137-146.

1m GI, Kim DY, Shin JH, Hyun CW, Cho WHo Repair of cartilage defect in the rabbit with cultured mesenchymal stem cells from bone marrow. J Bone Joint Surg (Br) 2001; 83: 289-294.

Insall J. The Pridie debridement operation for osteoarthritis of the knee. Clin Orthop 1974; 101: 61-67.

Jackson DW, Simon TM. Donor cell survival and repopulation after intraarticular transplantation of tendon and ligament allografts.

Microsc Res Tec 2002; 58: 25-33.

JakobRP,Franz T, Gautier E, Mainil- Varlet P.Autologous osteochondral grafting in the knee: indication, results, and reflections. Clin Orthop 2002; 401: 170-184.

Johnson 11. Arthroscopic abrasion arthroplasty historical and pathologic perspective: present status. Arthroscopy 1986; 2:

54-69.

Johnson 11. Characteristics of the immediate postarthroscopic blood clot formation in the knee joint. Arthroscopy 1991; 7: 14-23.

Johnson 11. Arthroscopic abrasion arthroplasty: a review. Clin Orthop 2001; 391 (Suppl): S306-S317.

Johnstone B, Yoo JU. Autologous mesenchymal progenitor cells in articular cartilage repair. Clin Orthop 1999; 367 (Suppl):

S156-S162.

Kawabe N, Yoshinao M. The repair of full-thickness articular cartilage defects. Immune responses to reparative tissue formed by allogeneic growth plate chondrocyte implants. Clin Orthop 1991; 268: 279-293.

Kim HKW, Moran ME, Salter RH. The potential for regeneration of articular cartilage in defects created by chondral shaving and subchondral abrasion. JEoneJointSurg 1991: 73A 9: 1301-1315.

King PJ,Bryant T, Minas T. Autologous chondrocyte implantation for chondral defects of the knee: indications and technique. J Knee Surg2002; 15: 177-184.

Kish G, Modis 1, Hangody L. Osteochondral mosaicplasty for the treatment of focal chondral and osteochondral lesions of the knee and talus in the athlete. Rationale, indications, techniques, and results. Clin Sports Med 1999; 18: 45-66, vi.

Kwan MK, Coutts RD, Woo SLY, Field FP. Morphological and biomechanical evaluations of neocartilage from the repair of fullthickness articular cartilage defects using rib perichondrium autografts: a long term study. J Biomech 1989; 22: 921-930.

Lance EM, Kimura LH, Manibog CN. The expression of major histocompatibility antigens on human articular chondrocytes. Clin Orthop 1993; 291: 266-282.

Lee CR, Grodzinsky AJ, Hsu HP, Martin SD, Spector M. Effects of harvest and selected cartilage repair procedures on the physical and biochemical properties of articular cartilage in the canine knee. J Orthop Res2000; 18: 790-799.

Lindahl A, Brittberg M, Peterson L. Health er:onomics benefits following autologous chondrocyte transplantation for patients with focal chondral lesions of the knee. Knee Surg Sports Traumatol Arthrosc 2001; 9: 358-363.

Luyten FP,Hascall VC, Nissley SP,Morales SP,Reddi AH. Insulin-like growth factors maintain steadystate metabolism of proteoglycans in bovine articular cartilage explants. Arch Biochem Biophys 1988; 276: 416-425.

Madsen K, Moskalewski S, von der Mark K, Friberg U. Synthesis of proteoglycans, collagen, and elastin by cultures of rabbit auricular chondrocytes -relation to age of the donor. Dev BioI 1983; 96: 63-73.

Mankin HJ.The response of articular cartilage to mechanical injury.

J Bone Joint Surg 1982; 64A: 460-466.

Mankin HJ, Jennings LC, Treadwell BV, Trippel SR. Growth factors and articular cartilage. J Rheumatol1991:18 (SuppI27):

66-67.

Mcllwraith CWoSurgery of the hock. stifle, and shoulder. Vet Clin North Am 1983; 5: 350-354.

Mcllwraith CWoDiagnostic and surgical arthroscopy in the horse.

2nd edn. Philadelphia: Lea and Febiger, 1990.

Mcllwraith CW, Yovich JV;Martin GS. Arthroscopic surgery for the treatment of osteochondral chip fractures in the equine carpus. J Am Vet Med Assoc 1987; 191: 531-540.

Menche DS, Frenkel SR,Blair B, et al. A comparison of abrasion burr arthroplasty and subchondral drilling in the treatment of fullthickness cartilage lesions in the rabbit. Arthroscopy 1996; 12: 280-286.

Mendicino RW, Catanzariti AR, Hallivis R. Mosaicplasty for the treatment of osteochondral defects of the ankle joint. Clin Podiatr Med Surg 2001; 18: 495-513.

Meyers MH, Akeson W, Convery FR. 1989 Resurfacing of the knee with fresh osteochondral allograft. J Bone Joint Surg 2001; 71A:

704-713.

Minas T. Chondrocyte implantation in the repair of chondral lesions of the knee: economics and quality of life. AmJ Orthop 1998; 27:

739-744.

Minas T. Autologous chondrocyte implantation for focal chondral defects of the knee. Clin Orthop 2001; 391 (Suppl): S349-8361.

Minas T, Chiu R. Autologous chondrocyte implantation. Am J Knee Surg 2000; 13: 41-50.

Minas T, Peterson L. Advanced techniques in autologous chondrocyte transplantation. Clin Sports Med 1999; 18: 13-vi.

Moran ME, Kim HKW, Salter RB. Biological resurfacing of fullthickness defects in patellar articular cartilage of the rabbit.

J Bone Joint Surg 1992; 74B: 659-667.

Moskalewski S, Kawiak J, Rymaszewska T. Local cellular response evoked by cartilage formed after auto- and allogeneic transplantation of isolated chondrocytes. Transplantation 1966; 4:

572-581.

Niedermann B, Boe S, Lauritzen J, Rubak JM. Glued periosteal grafts in the knee. Acta Ortho Scand 1985; 56: 457-460.

Nixon AJ, Brower-Toland BD, Bent Sf, et al. Insulin-like growth factor-I gene therapy applications in cartilage repair and degenerativejoint diseases.Clin Orthop 2000; 379S: S201-8213.

Nixon AJ, Fortier LA, Goodrich LR, Ducharme NG. Arthroscopic reattachment of select OCDlesions using resorbable polydioxanone pins. Equine Vet J 2004a; 36: 376-383.

Nixon AJ, Haupt JL, Frisbie DD, et al. Gene mediated restoration of cartilage matrix by combination insulin-like growth factor-II interleukin-l receptor antagonist therapy. Gene Therapy 2005; 12: 177-186.

Nixon AJ, Fortier LA, Williams J,Mohammed HO. Enhanced repair of extensive articular defects by insulin-like growth factor-I laden fibrin composites. J Orthop Res 1999; 17: 475-487.

Nixon AJ, Lillifh JT, Burton-Wurster N, Lust G, Mohammed HQ. Differentia{e;d cellular function in fetal chondrocytes cultured with insulin-like growth factor-I and transforming growth factorB. J Orthop Res 1998; 16: 531-541.

Nixon AJ, Lust G, Vernier-Singer M. Isolation, propagation and cryopreservation of equine articular chondrocytes. Am J Vet Res 1992; 53: 2364-2370.

O'Connor WI, Botti T, Khan SN, Lane JM. The use of growth factors in cartilage repair. Orthop Clin North Am 2000; 31: 399-410.

O'Driscoll SW. Healing and regeneration of articular cartilage. J Bone Joint Surg 1998; 80A: 1795-1812.

O'Driscoll SW. Articular cartilage regeneration using periosteum.

Clin Orthop 1999; 367 (Suppl): SI86-S203.

O'Driscoll SW, Keeley FW, Salter RB. The chondrogenic potential of free autogenous periosteal grafts for biological resurfacing of major full-thickness defectsin joint surfaces under the influence of continuous passive motion. J Bone Joint Surg 1986; 68A: 1017-1035.

O'Driscoll SW,Salter RB. The induction of neochondrogenesis in free intra-articular periosteal autografts under the influence of continuous passivemotion. JBone Joint Surg 1984; 66A: 1248-1257.

O'Driscoll SW, Salter RB. The repair of major osteochondral defects in joint surfaces by neochondrogenesis with autogenous osteoperiosteal grafts stimulated by continuous passive motion.

Clin Orthop 1986; 208: 131-140.

Ohlsen 1, Widenfalk B. The early development of articular cartilage after perichondrial grafting. Scand J Plast Reconstr Surg 1983; 17: 163-177.

Ostrander RV; Goomer RS, Tontz WL, et al. Donor cell fate in tissue engineering for articular cartilage repair. Clin Orthop 2001; 389: 228-237.

Pearce SG, Hurtig ME, Clarnette R, et al. An investigation of 2 techniques for optimizing joint surface congruency using multiple cylindrical osteochondral autografts. Arthroscopy 2001; 17: 50-55.

Peterson 1, Brittberg M, Kiviranta I, Akerlund EL, Lindahl A. Autologous chondrocyte transplantation. Biomechanics and long-term durability. AmJ Sports Med 2002; 30: 2-12.

Peterson 1, Minas T, Brittberg M, Nilsson A, Sjogren-Jansson E, Lindahl A. Two- to 9-year outcome after autologous chondrocyte transplantation of the knee. Clin Orthop 2000; 374: 212-234.

Pridie KH. A method of resurfacing osteoarthritic knee joints. JBone JointSurg 1959; 41B: 618.

Richardson]B, Caterson B, Evans EH, Ashton BA, Roberts S. Repair of human articular cartilage after implantation of autologous chondrocytes. J Bone Joint SurgBr 1999; 81:1064-1068.

Riddle WE. Healing of articular cartilage in the horse. J Am Vet Med Assoc 1970; 157:1471-1479.

Ritsila VA, Santavirta S, Alhopuro S, et al. Periosteal and perichondral grafting in reconstructive surgery. Clin Orthop 1994;

302:259-265.

Robert H, Bahuaud J. Autologous chondrocyte implantation. A review of techniques and preliminary results. Rev Rhum Engi Ed 1999; 66: 724-727.

Rodrigo JJ,Steadman JR, Silliman ]F, Fulstone HA. Improvement of full-thickness chondral defect healing in the human knee after debridement and microfracture using continuous passivemotion.

AmJ Knee Surg 1994; 7: 109-116.

Rogachefsky RA, Dean DD, Howell DS, Altman RD. Treatment of canine osteoarthritis with insulin-like growth factor-1 (IGF-1) and sodium pentosan polysulfate. Osteoarthritis Cart 1993; 1:

105-114.

Rubak JM. Reconstruction of articular cartilage defects with free periosteal grafts. An experimental study. Acta Orthop Scand 1982; 53: 175-180.

Rudd RG,Visco DM, Kincaid SA, Cantwell lID. The effects of beveling the margins of articular cartilage defects in immature dogs. Vet Surg 1987; 16: 378-383. ,,~.

Sams AE, Minor RR, Wootton JAM, Mohammed H, Nixon AJ. Local and regional matrix responses to chondrocyte laden collagen scaffold implantation in extensive articular cartilage defects.

Osteoarthritis Cart 1995; 3: 61-70.

Sams AE, Nixon AJ. Chondrocyte-laden collagen scaffolds for resurfacing extensive articular cartilage defects. Osteoarthritis Cart 1995; 3: 47-59.

Shamis LD, Bramlage LR, Gabel AA, Weisbrode S. Effect of subchondral drilling on repair of partial-thickness cartilage

defects of third carpal bones in horses. Am J Vet Res 1989; 50: 290-295.

Steadman JR. Rodkey WG. Briggs KK. Microfracture to treat fullthickness chondral defects: surgical technique. rehabilitation. and outcomes. J Knee Surg 2002; 15: 170-176.

Steadman JR. Rodkey WG. Rodrigo II. Microfracture: surgical technique and rehabilitation to treat chondral defects. Clin Orthop 2001391 (Suppl): S362-8369.

Strong OM. Friedlaender GE. Tomford WW. et al. Immunologic responses in human recipients of osseous and osteochondral allografts. Clin Orthop 1996; 326: 107-114.

Thompson RC. An experimental study of surface injury to articular cartilage and enzyme responses within the joint. Clin Orthop 1975; 107: 239-248.

Trippel SB. Coutts RD. Einhorn TA. Mundy GR. Rosenfeld RG. Growth factors as therapeutic agents. J Bone Joint Surg 1996; 78A: 1272-1286.

Tyler JA. Bird JLE. Giller T. Benton HP. Cytokines. growth factors and cartilage repair. In: Russel RGG. Dieppe PA (eds). Osteoarthritis.

Current research and prospectsfor pharmacological intervention.

Sheffield: mc Technical Services,1989: 144-153.

Vachon A. Bramlage LR. Gabel AA, Weisbrode S. Evaluation of the repair process of cartilage defects of the equine third carpal bone with and without subchondral bone perforation. Am J Vet Res 1986; 47: 2637-2645.

Vachon A. Mcllwraith CWoTrotter GW. Norrdin RW. Powers BE. Neochondrogenesis in free intraarticular, periosteal. and perichondrial autografts in horses. Am J Vet Res 1989; 50:

1787-1794.

Vachon AM. Mcllwraith CWoKeeleyFW. Biochemical study of repair of induced osteochondral defects of the distal portion of the radial carpal bone in horses by use of periosteal autografts. Am J Vet Res 1991a; 52: 328-332.

Vachon AM. Mcllwraith CWoTrotter GW. et al. Morphologic study of induced osteochondral defects of the distal portion of the radial carpal bone in horses by use of glued periosteal autografts. Am J Vet Res 1991b; 52: 317-327. van Beuningen HM. van der Kraan PM. Arntz OJ,van den Berg WB. Transforming growth factor-Bl stimulates articular chondrocyte proteoglycan synthesis and induces osteophyte formation in the murine knee joint. Lab Inves 1994; 71: 279-290. van den Berg WB. Growth factors in experimental osteoarthritis: transforming growth factor B pathogenic? J Rheumatol1995; 22: 143-145. van den Berg WE. van Osch GJ,van der Kraan PM. van Beuningen HM. Cartilage destruction and osteophytes in instability-induced murine osteoarthritis: role of TGF beta in osteophyte formation?

Agents Actions 1993; 40: 215-219.

Wakitani S. Goto T. Pineda. SJ. Mesenchymal cell-based repair of large. full-thi~ness defects of articular cartilage. J Bone Joint Surg 1994; 76A: 579-592.

White NA. Mcllwraith CWoAllen O. Curettage of subchondral bone cysts in medial femoral condyles of the horse. Equine Vet J 1988; Suppl6: 120-124.

Wilke M. Nixon AJ. Adams TA. Enhanced early chondrogenesis in equine cartilage defectsusing implanted autologous mesenchymal stem cells. Vet Surg 2001; 30: 508-509.

A

arthroscopy

abaxial plica, endoscopic view 421 abrasion arthroplasty 461-2 accessory carpal bone (ACB) 101, 385 accessory ligament of superficial digital flexor, desmotomy of 386 acetabulum, chip fracture removal 345 adhesion resection 398-400 adhesions 404 amikacin 436 amikacin sulfate 435 aminoglycosides 436 anatomy 36, 48 anconeal process, fragmentation 332 anesthesia, recovery of 64 angled rongeurs 321 annular ligament severing 377 tenoscopically assisted division 376 antebrachiocarpaljoint 36, 47,59,88,99,

108 arthroscopic examination 49-56 most lateral portion 56 antebrochiocarpal joint, with recurrent hemarthrosis 40 antimicrobial drug therapy 435 postoperative care 436-7 prophylactic 448, 452 Arthrex Continuous wave AR 6400S pump

13 Arthrex pump assembly 12 arthritis 345, 436 arthrofibrosis of the knee 39 arthroscope 7-9 angled lense 7-8 available types 8 conical obturator 9 direct view 8 fields of view 8 insertion 32-4, 59 magnifying 3 7 minor trauma to distal window 451 positioning 32-4, 90 protective stainless steelsleeve or cannula 8 range of sizes 7-9 rotating 34, 48, 54-6 self-locking sleeve8 small diameter 7 arthroscopic portals 4 arthroscopic probes 16 arthroscopic surgery seesurgical

arthroscopy

advantages of 3 complications in man 447-8 development 1-3 early applications 1-3 evolution 1-3 general technique 31-46 historical review 1-3 human 15 human knee 34 intraoperative problems 448-51 joint surgery 2 learning technique 45 overuse and abuse 3 overview 1-3 positioning problems 453-4 seealso diagnostic arthroscopy; surgical arthroscopy; and under specific applications arthrotomy 1 articular cartilage 72 degeneration 94 erosion 152-3 evaluation 41-3 iatrogenic damage 448. 450 lesions on medial condyle of femur 254 separation 153 articular fractures 2-3 articular surface damage 93 reconstruction 124 autoclavable cameras 10 autoclaving 25 autogenous fibrinogen, preparation 465 avascular synovium 37 axial osteitis of proximal sesamoid bones ,

V

186

B Bacteroidesspp. 436 basal sesamoid fragment 184 basket forceps 18. 20 Baxter-Edwards system 22 biceps brachii endoscopic view 417 indentation produced by 311 bicipital bursa endoscopy415-16 infection 430 proximal recess416 blade types 22-3 blunt obturator 33 blunt probe 16

Jo

'!

bone degeneration 94 bone density in third carpal bone 104 bone scintigraphy. temporomandibular joint (TMJ) 441 bulb pump 11-12 burrs. round or oval 22

bursae acquired 409 calcaneal 409-13 clinical application 421-4 communication between 410 congenital 409 contamination and infection 419 dissection 410 distention 410 endoscopic anatomy 411-12.420 endoscopic view with arthroscope close to entry portal and angled proximally 412 endoscopic view at apex of tuber 412 intertubercular (bicipital) 414-19 lateral endoscopic approach 411 medial approach 411 osteolytic lesions of calcaneal tuber

412-13 podotrochlear (navicular) 419-25 proximal endoscopic view 411 bursoscopy 409-26 clinical application 412-13.417-\9 general technique 409 overview 409

C calcaneus t1exedplantaroproximal-plantarodistal oblique radiograph 413 intrabursal fracture 433 traumatic fragmentation 413 camera coupler 11 capillary network 37 capitular fovea of proximal radius 334 capsulitis, postoperative 453 carpal canal 382 instrument insertion level 393 tenoscopically assistedrelease 392 use of term 380 carpal chip fractures 94, 99 carpal chip fragments distribution 61 repair with small fragement screws 124 specific sites 64-93 carpalchipremoval43,61-4

carpal flexor tendon sheath. use of term 380 carpal fragmentation. basic protocol 62 carpal joint 36.38.47-127 anatomy 47 arthroscopic view 34 diagnostic arthroscopy 47-58 skin incision 32 carpal lesions 147 carpal retinaculum 3

carpalsheath craniomedial depths 382 cross-section anatomy 381-2 diagnostic arthroscopy 380-91 lateral approach 382 postoperative care 391-3 proximolateral 392 standard entry point 383 surgical anatomy 380 tenoscopic view 384-5 tenoscopy 379-93 use of term 379-80 carpal slab fractures 3. 109-22. 124 current status of surgery 109-10 carpal tunnel syndrome 388-91

cartilage change 41 damage 146. 442 debridement 456-8 degeneration and immobilization 437 disruption III erosion 342 irregularity 343 lesions 340 reattachment 458-60 response to injury 455 shavings 45 seealso articular cartilage cartilage repair 3. 455-72 future directions 467 manipulative procedures for 456-62 methods 455-67 caudal cruciate ligament 217 caudal medial femoral condyle 221 caudal medial meniscus 221 caudal pouches. arthroscopic surgery 264 ceftiofur sodium 435-6 central trochlear groove of femur 233 cephalosporin 436 chip fractures 60

chondrocyte banking 465-6 clinical applications of transplantation 465 death 23 grafting. clinical application 466 transplantation 463-5 chondrocyte-IGF-1 grafting of subchondral cyst of femoral condyle 466 chondroplasty 458 chondrotoxicity 436 Cidex-activated dialdehyde solution 26 closed coupled device (CCD)chips 10

cold bandaging 28-9 collagen sponges435 comminution 110-11, 113, 118 common digital extensor tendon 133 computer-based simulations 45 condylar fracture AO/ASIF reduction forceps 194 arthroscopic monitoring 191 conical obturator 32-3 consistent osteochondral repair system (COR)463 contamination endoscopic evaluation and surgery 428 management 427-39 postoperative care 436-7 postoperative monitoring 437 results and prognosis 437 coxofemoral joint seehip joint cranial cruciate ligament 220 cranial cul-de-sac 321-2 cranial ligament 219 of lateral meniscus, avulsion fracture 264 cruciate injuries 2, 256 cubital joint see elbow joint curettage of undermined and separated cartilage 63 curettes 20 cutting forceps 18 cutting heads or blades for motorized units 22 cutting instruments 18-20 types available 19 cystic lesions of medial condyle of femur 246

D debridement44-5.62. 71-2. 83-4. 86.

88,106.108. Ill. 118. 142. 150.

153.161-4.184.188.287.334.

344-6.429-32 after chipfractureremoval94-6 cartilage456-8 conservativeapproach96 foreignmaterial430 !)umeralhead320 ~ '-osteochondritis dissecans(OCD)33~ .. subchondralcystic lesion164-7, 251 suspensorydefectwith motorized resector176 suspensoryligamenttags with motorizedresector175 sustentaculumtali 401 using motorizedequipment96 usingmotorizedresector187 deepdigital flexortendon(DDFT)278.

365-8.371-4.376-80.382.384-8.

395.397-400.404.421 endoscopicappearances of penetrating wounds423 nomenclature393 rupture of bodyof radialhead391 tearing of dorsalsurface425

desmotomy of accessoryligament of superficial digital flexor 386 dewdrop lesions at distal aspect of medial trochlear ridge of talus 292 diagnostic arthroscopy adjunctive diagnostic technique 35-9 carpal joint 47-58 femoropatellar joint 197-9 femorotibial joint 199-223 limitations 36 pitfalls 36 problems and complications 447-54 use of probe 35 usefulness of 36 seealso specific applications digital camera 23-4 digital extensor tendon sheath, multiple masses406 digital flexor tendon sheath adhesions between flexor tendons and dorsomedial aspect of tendon sheath

375 anatomic structures 366 composite tenoscopic view 370, 372 diagnostic tenoscopy 368-71 distention of 454 infection 429 medial instrument portal for resector entry 371 pathogenesis 365 penetrating wound 434 postoperative care 376-7 results and prognosis 3 77-9 reversed arthroscope entry 373 standard tenoscopic approach 369 structures 367-8 surgical anatomy 365 tenoscopy 365-79 ultrasound image 374 seealso deep digital flexor tendon sheath digital image capture and storage devices

24-5 digital video capture 9-10 discotemporal articulation under gas distention 443-4 disposableblades 22 distal articular surface of radius 55, 57 distal digital flexor tendon sheath, endoscopic view 420 distal epiphysis of radius 56 distal intermediate carpal bone 74-6 distal intermediate ridge of tibia, osteochondritis dissecans (OCD)

281-6 distal interphalangeal joints 2,347-59 abaxial articular fragments 356-7 coffin joint arthroscopy 348 coffin joint under carbon dioxide gas distention 355-6 diagnostic arthroscopy dorsal compartment 351 dorsal pouch 348-9 palmar compartment 353 palmar/plantar pouch 349-52

distal interphalangeal joints (Continued) dorsal approach for joint distention and palmar location of arthroscope portal 352 fracture of dorsomedial perimeter of distal condyle surface of middle phalanx 357 fragments in palmaro/plantaroproximal pouch 357-8 free-floating osteochondral fragment 347 general considerations 347 insertion of arthroscope 348-9 palmar/plantar aspect 350 normal arthroscopic anatomy 349 palmaro/plantaroproximal aspect

350-2 osteochondral fragment 348 osteochondritis dissecans (OCD)354 palmar cul-de-sac 358 position of arthroscope 350 palmar/plantar aspect 352 position of hypodermic needle 348 postoperative management 356 preoperative considerations 354-5 problems and complications 356 radiograph of abaxial intra-articular traumatic avulsion fracture of middle phalanx condyle 354 results of arthroscopy 356 surgical arthroscopy for treatment of extensor process fragments 352-6 surgical technique 355 distal lateral radius 85-7 fragmentation 88 distal medial radius 89-90 distal medial trochlear ridge 206 axial aspect 231 distal metacarpus 42 drilled hole 192 fractures of lateral condyle 189 distal navicular bursa. endoscopic view

420 distal phalangeal blood supply 349 distal radial carpal bone 43. 49. 65. 68.

70. 72. 107 distal radius lateral aspect 85-9 medial aspect 89-90 distal recess.endoscopic view 418 distal sesamoideanligaments 184 distended extensor carpi radialis tendon sheath 406 distention 11-12.32.48 digital flexor tendon sheath 454 maintenance 57-8 postoperative 452 dorsal arthroscopic portals 47 dorsal aspect of proximal phalanx. frontal fractures of 152 dorsal metacarpophalangeal joint 453 dorsal pouch of fetlock joint 132 insertion of arthroscope 130 synovial membrane proliferation 158

dorsalrecumbency48 dorsalsynovialpad.fibrousthickening 39

dorsalsynovialrecesses 48 dorsodistalarticular surfaceof radius 58 dorsodistalintermediatecarpalbone 69-73

dorsodistalradial carpalbone64-9 dorsolateralarthroscopicportal 53 dorsolateral-palmaromedial (DLPMO) obliqueviews65. 73-4. 78. 89 dorsolateralpouch,synovialmembraneof

272 dorsomedialeminenceof proximalphalanx

148 dorsomedialintercarpalligament39. 48 dorsomedialjoint pouch278 dorsomedial-palmarolateral (DMPLO) projection69. 85 dorsomedialportal 53 dorsoproximalchipfracturesof proximal phalanx 152 dorsoproximalmargin of radial carpal bone82 dorsoproximalradial carpalbone78 dorsoproximalthird carpalbone 73 drapesand drapingsystems27 DyonicsDyoVacsuctionpunchrongeurs

21 DyonicsInteliJETpump 14 DyonicsPowerMac system22 DyonicsPS3500EPpowershavingsystem 21

E egresscannula 15-16, 33-5, 62,131, 240, 295, 320 egressflushing 171 egressneedle 340 elbow joint 327-36 anatomy 327 arthroscopic approaches 327-36 arthroscopic surgery 332 caudomedial approach 328-30 caudomedial portions 331 ,;;-l'caudomedial pouch 330 ~ caudoproximal approach 330 caudoproximal aspect 333 caudoproximal pouch 332

complications334-6 cranial pouch 328-9 craniolateral approach 328 osteoarthritis 334 osteochondritis dissecans (OCD)332 osteochondrosis 332 positioning for arthroscopy 327-8 septic arthritis 332-4 triangulation 336 electrolyte solution 12, 308 electrosurgery 44 devices 23 malfunction 26 elevators 18-19

endoscopy calcaneal bursa 410 intertubular bursae 414 management of contamination and infection 427-39 enrofloxacin 435-6 entheseous new bone 453 epinephrine 448 esteotome 19 ethmoid forceps 141 ethmoid rongeurs 16-17 exfoliation 44-5 extensor carpi radialis (ECR)53.405-6 extensor tendon sheath removal of mass 407 tenoscopy 403-7 extrasynovial extravasation of fluid 450

F fasciitis 452 femoral condyle 217 chondrocyte-IGF-l grafting of subchondral cyst 466 femoral head cartilage erosion, over cranial portion 342 cartilage irregularity 343 cartilage lesions 340 complete rupture and contraction of proper ligament 343 lateral portions 342 partial rupture of ligament 344 subchondral cystic lesion 344 tearing of ligament 340-4 femoropatellar joint 2 clinical conditions 199 diagnostic arthroscopy 197-9 fragments in proximal pouch 239 insertion of arthroscope 197 insertion of arthroscopic sheath 199 lateral approach 212 normal arthroscopic anatomy

197-9 relationship of arthroscope and sleeve to patella and distal femur at initial entry 200 surgical arthroscopy 223-46 femoropatellar pouch, egresscannula to flush debris from 240 femorotibial joint 2,36 arthroscopic portals for caudal pouches 220 clinical conditions 223 cranial approach 199-212 diagnostic arthroscopy 199-223 insertion of arthroscope 199-212 into caudal compartment 222 into caudal pouch 218-20 normal arthroscopic anatomy of caudal compartment 222-3 of caudal pouch 220-2 of cranial compartment 218

femur articular cartilage lesions on medial condyle 254 central trochlear groove 233 concave subchondral defects of medial condyle 249 cystic lesions of medial condyle 246 postoperative management 252 preoperative considerations 246-9 results 252-4 technique 249-52 flattened lesion on lateral trochlear ridge 225 lateral trochlear ridge 228-9,232-3, 235,238 medial condyle 214,216 medial trochlear ridge 226, 229, 233,

236 osteochondritis dissecans (OCD)226 subchondral cystic lesion of medial condyle 248, 250, 467, 469 Ferris-Smithrongeurs 17, 62, 88-9, 157, 170-2,177-8,185,228,295,317,

320-1 fetlock joint 2,60 diagnostic arthroscopy 129-36 dorsal pouch of 132 insertion of arthroscope 132-5 loose plantar fragments in 172 palmar or plantar 132-5 palmar or plantar pouch 135-6 surgical arthroscopy 136-95 fetlock lesions 147 fibrillation 41-2, 44-5, 261 lateral patellar ligament 247 fibrotic changes 37-8 fibrotic synovial pad proliferation 157 fibrous joint capsule, tearing 453 flexed dorsoproximal dorsodistal (skyline) projections 110-11flexor digitorum longus seemedial digital flexor tendon (MDFT) flexor retinaculum 395 superficial lamina 391 tenoscopic view 394 flexor tendons, cross-section anatomy

381-2 flow-regulated roller pump 12 fluid egress 34 fluid extravasation 34 fluid ingress line 33 fluid irrigation system 11-15 fluid pumps, types and properties 12-13 fluid system, complications 34 focal bone disease 188 Foerner elevator 19 forage 460 forceps 16 foreign material debridement 430 detecting and removing 437 intrasynovial451 in synovial cavity 429

fractures2 fragmentation47. 88. 93 anconealprocess332 calcaneus413 carpusand fetlock2 distalmargin of navicularbone424 glenoid 319 multiple sites93 patella242-5 fragments.failure to remove453 frontal fracture of proximalphalanx152.

154 fucalsubchondralbonedisease43

~ GameReady for pneumaticpressureand coldbandaging28 gasdistention34 gasemphysema15 gasinsufflator 14-15 gentamicin435-6. 452 gienohumeralligament312 glenoid articular fracture 325 cranial rim 311 cyst debridement321 cystic lesion315. 318 fragmentation319 osteochondritis dissecans (OCD)315.318 osteochondrosis 324 underminedcartilage 319 gram-negativebacteria436 growth factors464-5

H hemarthrosis448 synovialmembrane40 hemorrhagictenosynovialmass403 hemostats64 high-frequency(HF)equipment44 hip joint 2, 337-46 arthroscopicexamination338-40 arthrotomy 337 cranial. middle.and caudalaspects341 diagnosticarthroscopy337-40, 345 diseases of 337 "' , infectious

arthritis

345

osteochondritisdissecans(OCD)344-6 osteochondrosis 344-6 preoperativeassessment 337 surgicalarthroscopy340-5 histologicanalysis95 historytaking 60 hookknives20 hookscissors20 human arthroscopy15. 35 humeralhead articular fracture 325 debridement320 osteochondrosis 324 positioningof arthroscopefor surgery 321

humerus cranial aspect 311 craniolateral portion 332 endoscopic view 417-18 lateral tuberosity 419 loss of fibrocartilage 418 osteochondritis dissecans (OCD)315 hyaluronan 436 hyperemic villi 37 hypertrophic medopatellar plica 39

I IGF-l 465.467 infectedcellulitis 452 infection classification428 endoscopicevaluationand surgery428 iatrogenicsynovial451 intrathecal451 management427-39 postoperative care436-7 postoperative complications451-2 postoperative monitoring 437 resultsand prognosis437 stagesof 428 treatmentprotocols428 infectiousarthritis 436 hip joint 345 infraspinatustendon308.310.312 instrumentportal 33. 35 instrumentation7-30 breakage448.450-1 brokeninstrumentretrieval 18 careand maintenance2 7-8 hand instruments16-23 motorized21-3 seealsospecifictypesand applications intercondylareminencefracture2 intermediatecarpalbone 52.54. 57 InternationalCartilageRepairSociety (ICRS)41. 94 interphalangealjoints 347-64 distalphalanxcysts358 proximal navicularcysts358-9 seealsodistalinterphalangealjoints; proximalinterphalangealjoints intersesamoidean ligament137-8 detachmentfrom proximalsesamoid bone 186 intra-articular fragments.locationof 60-1 intra-articular ligamentsand menisci. evaluation40 intrasynovialevaluation3 intrathecalendoscopyof synovialbursae 409

intrathecalNaHA 391 ipsilateralarthroscope183 irrigation 11.59.62

J joint capsule35, 64

medial

K kissing lesion62. 71 knee joint arthrofibrosis39 complicationin arthroscopy447 human 34 postoperativeinfectionratesfollowing arthroscopy448 recommendations to minimize complicationsassociatedwith arthroscopy447 knee regeneration45

L lameness3. 60. 110.223.246.325.365.

377.380.393.424 largefragments.removalof 34 lasers40. 44 typesand applications23 lateralcondylarfossa.glidehole 192 lateralcondylarfracture.repair of 186. 190 lateralcondyleof distal metacarpus. fracturesof 189 lateral digital extensortendon 133 lateraldigital flexortendon393 lateraleminence149 lateral femoralcondyle218-20. 222 lateralfemorotibialjoint. insertion of arthroscopeinto cranial compartment 214

lateralhumeral condyle.cranial portion 334

lateralmeniscus218-19 lateral palmar intercarpal ligaments (LPICL)105 lateral patellarligament.fibrillation 247 lateral portal 48 lateral recumbency48 lateral styloidprocess56 lateral tibial condyle219-20 lateral trocWearridge208-10.228-9.

232-3. 235. 238. 241 distal aspect230 lateromedialprojection69. 73-4. 78 lavage44. 432-4. 448 light cable33 light generators9 light intensity 9-10 light sources9-10 long digital extensortendon(LOE)219 long-handledforceps17 loosebodies18 loosebodyforceps18

M McIlwraith arthroscopicrongeurs 17 McIlwraith fragmentforceps18 McIlwraith-Scanlanelevator18 magneticretrievers451 manipulativeproceduresfor cartilage repair 456-62

collateral ligament 276medial condyle 133. 215-16 subchondral cysts of 467-9 medial digital flexor tendon (MDFT) 395 medial dorsal intercarpal ligament (MDIC) 69 medial eminence 149 medial femoral condyle 207medial femorotibial joint approach to cranial pouch 212-13 lateral approach 213 manipulation of arthroscopic sleeve and conical obturator 213 normal arthroscopic anatomy of cranial compartment 213-14 positioning of arthroscope 212. 214 rupture of cruciate ligaments 258 surgical arthroscopy 246-64 medial humeral condyle. osteochondritis dissecans (OCD) 335 medial lateral condyle 219 medial malleolus 278 displaced fracture 299 osteochondritis dissecans (OCD) 293-4 position of arthroscope and instrument 294 medial meniscus 215-16 fibrillation of free border of cranial horn 261 longitudinal tear of caudal horn 265 longitudinal tear of cranial horn 261-2 transverse vertical meniscal tear 264 medial palmar intercarpal ligament (MPICL) 37.48.104-6 medial patellar fibrocartilage 246 fracture of 247 medial patellar ligament 205 medial patellar plica syndrome 39 medial plica 73 medial portal 54 medial sesamoid bone. basal fragment 182 medial tibial intercondylar eminence. fracture of 256 medial trochlear ridge 204-5. 207.229.

231.233.236 meniscal injuries 257-64 meniscalligament injuries 257-64 {i meniscal tears 2. 260 meniscectomy in humans 1 meniscotome 22 meniscus and associatedligaments 260 removal of axial portion 261 repair technique 263 mercury vapor lamps 9 metacarpal/metatarsal condyle fractures 3 metacarpophalangeal joint 38 arthroscopic examination 129-32 indications for arthroscopy 129 infection 429 insertion of arthroscope 130-2 insertion of arthroscopic sheath and conical obturator 131

osteochondritis dissecans(OCD)158-62 palmar pouch136 pannusdeposits430 ultrasonographyof dorsalaspect431 metacarpophalangeal joints 129-96 metacarpus137 metaplasiaof villi 36 metatarsophalangeal joint indicationsfor arthroscopy129 osteochondritis dissecans(OCD)158-62 metatarsophalangeal joints 129-96 metronidazole436 microfracture460-1 middle carpaljoint 47.49.51.59.95 arthroscopicexamination48 middlepatellarligament. avulsionof 247 midsagittalridge 133 mineralization400. 402 mosaicplasty463-4 motorizedequipment21-3.39.96.

175-6.187.424.458 multiplejoints 59 multiple sites.fragmentationat 93 Myobacteriumtuberculosis 26

N navicularbone fibrillatedfibrocartilageon sagittalridge 425

fragmentationof distal margin 424 proximal margin421 sagittalridge421 navicularbursa acute endoscopy 422 diagnosticendoscopy 424-5 endoscopicapproach419 penetratinginjuries 421-4 proximalrecess424 treatmentof penetratingwound 435 necropsyexamination336 necrosisof villi 36 nephrotoxicosis 436 Nitinol sutureneedle263 nitrogendrivenflutter valve assembly12.

14

nonsteroidalanti-inflammatorydrugs436 nuclearscintigraphy337

0 obturator32-3. 99.131.213.309.376-7 olecranon.cranial cortexof 336 operatingarthroscope35 osteoarthritis(OA)60. 343 elbowjoint 334 in humans45 progressive111 secondary111 shoulderjoint 325 osteochondralautografttransfersystem (OATS)463 osteochondralchip fragmentation60

osteochondraldisease2. 44 osteochondralerosion43 osteochondralfragments60.65.147.453 palmar aspectof carpaljoints 99-100 proximal dorsalaspectof proximal phalanx 136-52 proximalpalmar or plantar aspectof proximal phalanx167-72 osteochondralgrafts462-3 osteochondralhealing99 osteochondritisdissecans(OCD)2. 16. 18.

105.223-42.269.315.466 cartilage flap re-attachment459 chronic lesions237 debridement335 distal dorsal aspectin metacarpophalangeal and metatarsophalangeal joints 158-62 distal intermediateridge of tibia 281-6 distal interphalangealjoints 354 distribution of lesions224 elbowjoint 332 glenoid315.318 hip joint 344-6 humeral head318 humerus 315 lateral trocWearridge224-6. 460 medialhumeral condyle335 medialmalleolus293-4 patella227 postoperativemanagement241 preoperativeconsiderations223-6 proximalinterphalangealjoints 361 results241-2 shoulderjoint 319 surgical treatment279 tarsocrural (tibiotarsal)joint 269. 280 technique226-40 osteochondroma. tenoscopicremoval393 osteochondrosis arthroscopictechnique314-22 elbowjoint 332 glenoid324 hip joint 344-6 humeralhead324 preoperativeconsiderations314 shoulderjoint 314-25 osteomyelitis325 osteophytes92-3 osteotome18. 62. 385

p pain and pain relief401. 454 palmar carpalligament(PCL)385 palmar intercarpalligaments.tearing

104-5 palmar osteochondralwedge87 palmar/plantar annular ligament. transection371-4 palmar pouch fetlockjoint 135-6 metacarpophalangeal joint 136

middlecarpaland antebrachiocarpal joints. arthroscopicexamination57 palmarolateraloutpouching59 pannus depositsin scapulohumeraljoint 432 formation 37 removal430 partial thicknesschondrectomy44-5 patella202-4. 208 articular surface230 fractures245-6 fragmentation242-5 postoperativemanagement245 preoperativeconsiderations242 results245 technique242-5 osteochondritisdissecans(OCD)227.

238

secondaryremodeling238 patellaforceps18 patellarongeur 17-18 patellofemoralarticulation36 pathologicplicaein man 39 penicillin 436.452 periarticularosteophytes60 periarticular swelling29 periarticular tissues59 perichondriumfor improvedcartilage repair462 periosteumtransplantation462 perisynovialstructures iatrogenicdamage450 injury 448 petechiationof villi 37. 429 phenylbutazone97. 322 photography23 plica-associated disease39 pluripotent mesenchymalstemcell transplantation464 pneumoperitoneum15 pneumoscrotum15 polymethylmethacrylate (PMMA)beads435 poplitealtendon222 post-antibioticeffect(PAE)436 post-arthroscopicirrigation and closure35 postoperative care436 pos~operative complications451-4 t postoperativeeffusion448 ' postoperative monitoring 437 preoperativeevaluation31 preoperativepreparation31 pressurebandaging28-9 pressuremanagementsystems28-9 probeuse 16 in diagnosticarthroscopy35 in medialpalmar intercarpalligament 37

proliferativesynovialvilli 449 proliferativesynovitis158. 305 proximalarticular surface53-4 intermediatecarpalbone 56 proximal aspectof intermediatecarpal bone83

proximal check desmotomy 389 proximal check ligament 386.390 proximal dorsal aspect of proximal phalanx. removal of osteochondral fragments from 136-52 proximal dorsal eminences of proximal phalanx 152 proximal dorsomedial eminence of proximal phalanx 146.153 proximal intermediate carpal bone 78. 82-4 proximal interphalangeal joints 359-64 arthroscopy of dorsal pouch 359-60 arthroscopy of palmar/plantar pouch

360-4 avulsion fracture of abaxial distal condyle of first phalanx 361 osteochondritis dissecans (OCD)361 position of arthroscope for palmar/plantar pouch 362 removal of palmar middle phalanx osteochondral fragmentation from axial midline of palmar pouch 364 proximal intertarsal joint (PIT) 274 proximal phalangeal fracture 144 proximal phalanx 2. 133-5. 139 dorsomedial eminence 148 dorsoproximal chip fractures 152 fragmentation of plantaroproximal articular surface 449 frontal fractures 152. 154 lateral eminence 147 multiple fragments associated with lateral plantar process 171 osteochondral fragments of proximal palmar or plantar aspect 167-72 proximal dorsal aspectof. removal of osteochondral fragments from

136-52 proximal proximal proximal proximal

dorsal eminences of 152 dorsal fragments of 139 dorsomedial aspect 143 dorsomedial eminence of 146.

153 proximodorsal aspect 147 proximal radial carpal bone 54. 82 proximal radius. capitular fovea of 334 proximal sesamoid bones apical-abaxial fragmentation 181 axial osteitis 186 removal of fragments 172-85 proximal third carpal bone 43 proximal ulnar carpal bone 85 Pseudomonas aeruginosa26 pumps 11-14. 34 punctate erosions 41

R radial carpal bone 42, 57, 66, 69, 71, 80-1,92,95,98-9,106,108 large fragment off dorso distal margin

125 slab fracture 123-4

radial osteochondroma 40 removal of 385 radial physeal exostoses,removal of 385-8 radiofrequency devices 23 radiofrequency energy (RFE)44

radiography postoperative 36,119,125 preoperative 36,119,125

radius distal articular surface of 55, 57 distal epiphysis of 56 dorsodistal articular surface of 58 Richard Wolf Surgical Arthro Power System 22 Ringer's solution 442 rongeurs 16-18, 20-1, 62, 321 seealso Ferris-Smith

5 scalpel blade 32.35 Scanlan-Mcllwraith scissor-action rongeurs 20 scapulohumeraljoint 307-26 caudal aspect 309 cranial aspect 311 exploration 314 lateral aspect 310 medial aspect 312 pannus deposits in 432 seealso shoulder joint sclerosis of third carpal bone 100 self-sealing cannula 20-1 septic arthritis 306. 325 diagnosis 37 elbow joint 332-4 septic osteomyelitis 306 septic physitis 325 sesamoid bone 137-9. 367 basal fragment of 183 fracture 172. 180 fragmentation of 185 shavers 22 suction use on 23 sheath insertion 32-3 sheathed blades 19 sheathed knife system 20

shoulderjoint arthroscopic surgery 31~25 caudal aspect 313 damage to instruments 323 diagnostic arthroscopy 307-14 difficulty in reaching potential lesions 323 final position of arthroscope within sheath 309 fluid extravasation 322 insertion of arthroscope 307-8 insertion of arthroscopic sheath and obturator 309 lateral approach 309-12 medial aspect 313 normal arthroscopic anatomy 308-9

osteoarthritis325 osteochondritisdissecans(OCD)319 osteochondrosis 314-25 placementof arthroscope322 postoperativemanagement322 problemsand complications322 radiographand positivecontrast arthrogram 316 resultsof surgicalarthroscopy323-5 septicjoint 325 specificindicationsand techniquefor diagnosticarthroscopy312 surgicalanatomy307 triangulation 317.322 seealsoscapulohumeraljoint skinabscesses 452 skin incision 32.35.48.64.89.282 suturing 35 skinportals.closure132 skinsutures.complicationrate 448 slabfracturesseecarpalslabfractures slottedcannula 376-7 smallfragments16-17 Smith& NephewDyonicsArthroplasty System22 smoothedgedresectors22 sodiumbenzylpenicillin435-6. 452 softtissuemineralization453 spinalneedle282.307-8.314.317.322.

340 spongialization462 spooncurettes20 spurs92-3 stemcelltransplantation464 sterilization10-11. 25-7 stifle joints 2 StorzAIDA digitalimagecaptureand storagedevice25 Strykerarthroscopypump14 StrykerSDCPro 2 digital videoand still imagestorageand printing system25 StrykerSystem22 subchondralbone42 disease100--4.152-3 drilling 460 subchondralcyst2.108-9.164-7.254-6.

467-9 :0, ยงlibchondrallucency104 subchondralmicrofracture99 subfascialcellulitis452 suction applications21 use on shavers23 sulcusmuscularis218 superficialdigital flexortendon (SDFT) 38.

365-8.371-4.378-80.384.386.

388.413-14

supraglenoidtubercle.fragmentation419 suprapatellarpouch201 surgicalarthroscopy44 advantagesof 58-9 basictechniques35 caseselection97

caudalpouches264 current status58-9 femoropatellarjoint 223-46 limb suspendedfor 32 medialfemorotibialjoint 246-64 post-surgicalfollow-upinformation97 postoperativemanagement97. 115 postoperativeprotocol 102 preoperativeinformation60 preoperativeplanning III principle of 34-5 problemsand complications59. 447-54 prognosis97 relevantpathobiology60 removalof osteochondralchip fragments58-99 results97.115-22 shoulderjoint 314-25 seealsospecificapplications surgicalassistants26-7 suspensory ligament tags resection with synovial resector 179

sustentaculumtali. debridement401 suturesinuses452 sutures35 synovectomy 39-40. 96 capsulardefectsand fibrosisfollowing 40

carbondioxidelaser40 effecton articular cartilagein equine joints 40 equinejoint tissues39 human hemophiliacpatients39 mechanical40 synovial449-51. 3649 synovialbursae3 intrathecal endoscopy 409 synovial diverticulum 218 synovial effusion 280 synoviall1ap 133 synoviall1uid bloody or brown 65-6 debris in 36 synovial fold 39 synovial fossa 273-4 synovial membrane 36-7, 205, 220, 273-4 biopsy 37 dorsal pouch 158 evaluation 36-9 hemarthrosis of 40 proliferation 39.158 resection of 170 synovial pattern 37 synovial proliferation 37.

40

synovialresection96 synovialresectorunits 22 infection427-39

synovial villi 38. 49 morphologic features 36 obstruction of view by 449-51

synovitis changes in 37 evaluation 36-9 experimentally induced 37 forms 37 post-operative 452 proliferation and thickening of synovial villi 38

T talocentraljoint fragmentsdislodgedfrom medial trochlearridgeand entered dorsomedialpouch304 retrieval of fragments299 talus centralmedial trocWearridge 277 dewdroplesionsat distal aspectof medial trocWearridge 292 distalmedial trocWearridge277 distaltrocWeargroove274 lateraltrochlearridge 272 lateral trochlearridgeand distaltibia junction 271 medialtrocWearridge273-4, 276, 278 and distaltibia and medialmalleolus junction 275 osteochondritisdissecans(OCD)

286-91 osteomyelitisof dorsodistallateral trocWearridge434 sagittalfracture 303 subchondralcystic lesionof trochlear groove294-5,297 wearlines on medialtrochlearridge295 tarsal sheath centromedialapproach398 cross-sectional specimen396-7 diagnostictenoscopy397-8 distal aspect401 distal region400, 404 inflammation402 medialaspect395 nomenclature393 postoperativecare 401-2 proximal region396. 399 surgicalanatomy395-7 sustentaculumlevel396 tenoscopy393-402 resultsand prognosisof tenoscopy 402

tenosynovitis402 wound healingcomplications401 tarsal tunnel 395 tarsal tunnel syndrome393 tarsocruraljoint 269-306 diagnosticarthroscopy269-79 dorsomedialapproach269-79 insertion of arthroscopicsleeve270

intra-articular fractures299 osteochondritis dissecans (OCD) 280. 296 results291-4 plantarlateral or plantar medial approaches278-9 positioningof arthroscope270 puncturewound in dorsolateralaspect 428

surgicalarthroscopy279-306 aftercare306 tearsand avulsionsof collateral ligaments305 tarsus.fracture of proximalplantar aspect of medialtrochlearridge 300-1 temporomandibularjoint (TMJ)441-5 arthroscopicapproach442-3 articular disk442 bone scintigraphy441 clinicalresults444-5 diagnosisof inflammation444 discotemporalcompartment441-2 medialpenetrationof joint capsule444 overview441 preoperativeconsiderations441-2 proximal compartment443 ultrasoundimage442 ventral discomandibulararticulation 441

tendonlinear clefts374-6 tendonsheath problems3 seealsoextensortendonsheath tenoscopy365-408 carpalsheath379-93 diagnostic368-71 digital flexortendonsheath365-79 extensortendonsheath403-7 massremoval/adhesiontransection 371 resultsand prognosis393 tarsal sheath3.393-402 techniques368-76. 380-91. 397-401 tenosynovialmasses398-400. 403 and adhesions371 tenosynovitis acute 365 1'$ chronic 365 complex365 thermal chondroplasty44 third carpalbone43.78-80.97.102 bone density104 lag screwfixation of slabfractures 110-15 sagittalfracture 121-2 sclerosisof 100 slabfracture 109-10.112.114-16.

118-20.124 third metacarpalbone debridementof subchondralcystic lesions164-7 subchondralcystin medialcondyle468 tibia 218 distalintermediateridge273

290-1 extremity254-6 tight spaces17 toothededgedresectors22 transillumination36

traumatic joint disease37. 40 triamcinoloneacetonide253 triangulation 1 elbowjoint 336 principle of 34-5 shoulderjoint 317.322 trochleargroove202-3.211

U ulnar carpalbone52. 85 ulnar fracture.mid-shaft336 ultrastructuralstudies45

V vacuumattachments21 vasculaturechanges37 VCRs 24

videocameras10-11 video documentation10. 23-4 videorecorders10 lightweight single-chipor three-chip10 videoarthroscopes 8. 11 videotape9. 24 villi metaplasia36 necrosis33 petechiation37.429 proliferativesynovial449 synovial36. 38.49.449-51 visualization47 villonodular synovitis152-8 villous regeneration40 villous synovialmembrane210. 219 viruses26

W wearlines 42, 44 wounds healingcomplications401 management434-5 postoperativecare436-7

X xenonlight sources9-10