ILIAC CREST HARVEST
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For more than 4 decades the iliac crest has been the accepted place to get bone for augmentation procedures. Main indications in OMFS are osteoplasty in patients with cleft lip and palate, augmentation of bony defects after operations for tumours or large cysts and augmentation in preprosthetic surgery for severe cases of atrophy of the alveolar crest from early loss of teeth or aging process. Main advantages of iliac crest : - Easy accessibility. - Possibility of harvesting large amounts of bone. www.indiandentalacademy.com
- Ability to close the wound primarily. Anterior iliac crest is more accessible as a donor region and bicortical grafts can be taken. Two disadvantages : - Bicortical bone layers between the internal and external cortices below the anterior iliac crest are as thin as a blade, often making it difficult to obtain a sufficient bone volume. - Risk of fracturing anterior iliac spine, which results in a long lasting obstacle to walking and climbing stairs. www.indiandentalacademy.com
Bicortical width of the bone layer beneath the posterior iliac crest does not shrink this region, it always offers enough cortical and cancellous bone for augmentation even in cases of extreme alveolar atrophy or for the reconstruction of large bony defects. Less morbidity - Irregularities of gait do not occur, the patient can be mobilized earlier and has less pain. Main disadvantage – Necessity to turn the patient in the course of the operation, which lengthens the operating time. www.indiandentalacademy.com
This prospective, non – randomised study was conducted in 1998 and compares the amount of bone harvested, the operating time and the postoperative morbidity.
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PATIENTS AND METHODS : 118 patients were operated on 127 occasions in 1998. In 81 cases the bone was harvested from anterior iliac crest, in 46 from the posterior. There were 65 men and 53 women. Mean age was 44 years. ( Range : 8 – 80 ). Indications for harvesting : - Bony defects after resection of tumours ( n = 40 ). - Extreme atrophy of the upper and lower alveolar crests ( n=33 ). www.indiandentalacademy.com
- Cleft lip or palate defects ( n=25 ). - Defects after removal of large cysts ( n=17 ). - Posttraumatic defects ( n=12). Anterior iliac crest was chosen in all patients with cleft lip or palate and in patients with large cystic lesions. (Only cancellous bone). This was also preferred if only one quadrant of the jaws had to be augmented and for sinus lift operation in patients with highly atrophic alveolar processes.
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For defects after resection of tumours or trauma the anterior iliac site was used, if the defects could be reconstructed by a maximum of 2 or 3 corticocancellous bone strips about 40 - 50 mm long and 10 – 12 mm wide. Antibiotic prophylaxis ( Penicillin 10 million units IV) started the evening before operation and was continued twice a day until the evening of 2nd post op day. Steroid ( Prednisalone ) given 250mg morning and evening on the day of operation and 125mg morning and evening on 1st post op day. www.indiandentalacademy.com
Criteria for exclusion : Previous operations in this area. Systemic bony or neurological diseases. Long standing treatment with steroids, immunosuppression drugs. Chemotherapy in the previous 2 months. Drug misuse in the previous 3 months.
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All patients operated under general anaesthesia. For harvesting bone from the anterior iliac crest the patient lies supine. The pelvis is raised about 30 degrees. Skin over the iliac crest is put under stretch by placing a fist above the iliac crest and pushing the abdominal wall medially. Skin incision is about 50mm long, starts about 20mm behind the anterior iliac spine and runs parallel to the crest. www.indiandentalacademy.com
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After relaxing the skin the incision line finally lies about 20mm lateral to the crest, avoiding mechanical irritation of the scar by tight clothes. Blunt dissection of the subcutaneous tissues until the periosteum of the crest is found. Periosteum is incised and periosteal layer with the iliac muscle dissected bluntly medially. Iliac fossa is dissected to a depth of about 80mm. An oscillating saw is used to cut parallel strips of monocortical bone from the inner table of pelvic bone at right angles to the line of iliac crest. www.indiandentalacademy.com
Strips are about 15mm wide. Cancellous bone is then harvested using a sharp spoon. Area of defect is rinsed and a collagenous tampon is used to stop bleeding. Wound is closed in layers and pressure bandage is applied. In adolescents only anterior approach was used. The cartilage covering the iliac crest is incised after the fashion of a double door. After harvesting the bone the cartilage cover is replaced and sutured with absorbable sutures. www.indiandentalacademy.com
Anterior iliac crest showing exposure of the superior
crest.
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Posterior incision is made with the patient prone. Incision is about 80mm long, follows a diagonal line from a cranial and medial position below and laterally and crosses the posterior iliac crest. It is the safe way to protect the gluteal branches of posterior cutaneous nerves. After blunt dissection of the gluteal muscles the external bony wall of the posterior iliac crest is exposed. The external cortical bone is cut and harvested in the same way as anterior iliac crest and wound is closed similarly. www.indiandentalacademy.com
Time taken for positioning either supine or prone was recorded. All patients required bed rest for first 24 hrs and were then mobilized on 2nd post op day. Disturbances of gait – including limp, unsteadiness and deviation were documented on days 14 and 28 after operation. On 3rd post op day patients were asked to estimate pain from where bone had been harvested using Visual Analogue Scale from 0 to 10. www.indiandentalacademy.com
Exposure of the posterior site of harvesting in the iliac crest.
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RESULTS : Mean volume of 15 cu.cm ( range 9 – 25.5 ) was harvested from iliac crest , which included monocortical bone chips, bicortical bone chips and bone taken with punch needle. Mean volume harvested : - Anterior iliac crest – 9 cu.cm ( range 5 – 12 ) ( n=81 ). - Posterior iliac crest – 25.5 cu.cm ( range 17 – 29 ) www.indiandentalacademy.com
(n= 46 ).
Mean operating time : - AIC – 35 min ( range 22 – 48 ). - PIC – 40 min (range 32 – 55 ). These times does not include preparation of the area around the head and neck and for changing the position of the patient for harvesting bone from the PIC. This maneuver took an additional mean time of 20 min.
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DISCUSSION : Overall rate of complication was 12 % and the anterior approach to the ilium caused considerably more problems than posterior approach. Main advantage of PIC region is that up to 3 times more cancellous bone can be obtained for transplantation. Disadvantages of a slightly prolonged operation time, the necessity to change the position of the patient and the restriction to harvest only monocortical bone grafts seem to be less important. www.indiandentalacademy.com
In adult patients, particularly in those cases, in which large volumes of bone are required, posterior approach is preferred. Patients have significantly less pain and fewer irregularities of gait. In patients with cleft lip or palate the anterior iliac crest should be used as the amount of bone needed is usually not as great as in operations for augmentation of atrophic alveolar processes.
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www.indiandentalacademy.com Leader in continuing dental education
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