Temporomandibular Joint 'Mice:' Report of Two Cases

AUTHORS

Tarun Mundluru, BDS, MSc, is an orofacial pain and oral medicine resident at the Herman Ostrow School of Dentistry of USC. Conflict of Interest Disclosure: None reported.

Fariba Farrokhi, DMD, is the associate director of temporomandibular disorders at Newark Beth Israel Medical Center in Newark, N.J. She is a master of the Academy of General Dentistry. Conflict of Interest Disclosure: None reported.

Melika Shahsavar Haghighi, DDS, is a general dentist. She practices dentistry at two private practices in Los Angeles and Orange County. Conflict of Interest Disclosure: None reported.

Mariela Padilla, DDS, MEd, is an associate professor of clinical dentistry, orofacial pain, at the Herman Ostrow School of Dentistry of USC. Conflict of Interest Disclosure: None reported.

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ABSTRACT

Background: The temporomandibular joint (TMJ) is subject to frequent loading, related mostly to its functional capabilities, and it commonly exhibits bone remodeling. The physiological adaptability and tolerance might be compromised and signs of degenerative change will appear. The presence of loose calcified bodies in the TMJ space might suggest osteochondritis dissecans or synovial chondromatosis, and patients may have symptoms of pain, joint sounds and limitation in the range of motion of the jaw.

Methods: In this paper, two cases with radiological loose and detached bone bodies in the TMJ suggestive of osteochondritis dissecans are discussed, including medical history, clinical findings, radiological appearance and treatment.

Results: The first case is a 66-year-old female with systemic conditions who presented with TMJ crepitus. The second case is a 55-year-old female with a previous diagnosis of rheumatoid arthritis who has jaw clicking and facial pain. Panoramic imaging in both cases revealed joint loose bodies, and conservative treatment was implemented.

Conclusions: The use of panoramic imaging as a preliminary diagnostic approach is useful to identify the presence of TMJ alterations. The management for these “joint mice” ranges from conservative treatment to surgical options.

Practical implications: A conservative approach includes physical therapy and activity modification to improve muscle mobility and increase range of motion of the TMJ. Close monitoring will identify the need to intervene with a surgical procedure.

Keywords: TMJ disorders, joint loose bodies, osteochondritis dissecans, synovial chondromatosis, TMJ mice

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The temporomandibular joint (TMJ) is subject to frequent loading, related mostly to its functional capabilities, and it commonly exhibits bone remodeling. In some instances, the physiological adaptability and tolerance might be compromised and signs of degenerative change will appear, including condylar flattening and erosion. [1] Campos et al. (2008) reported a series of TMJ magnetic resonance imaging characteristics, and even though they were not able to correlate the condylar changes with clinical symptoms, they documented the most common alterations as: osteophytes, erosion, avascular necrosis, subchondral cyst and intra-articular loose bodies. [2] Intra-articular loose bodies are not a common finding in the TMJ, but their appearance in other parts of the body has been related with diseases such as osteochondritis dissecans, intracapsular fractures, osteoarthritis, synovial chondromatosis and rheumatoid arthritis. [3]

Osteochondritis dissecans is an idiopathic bone anomaly, which appears as a detached bone fragment, as a result of bone modeling beneath the surface of the lesion. The diagnosis is often achieved with a 2D radiographic image (such as a panoramic X-ray) and four stages have been reported, depending on the progression of the condition. [4] One of the radiological characteristics in the TMJ is the presence of loose bodies on the condylar heads, and the patient might report pain, joint sounds and limitation of oral movement. [5] Possible causes include trauma, abnormal ossification, genetic alterations and endocrine factors. The management is controversial and ranges from conservative treatment, such as activity modification and physical therapy, to surgical approaches including fragment excision and remodeling. [6]

Synovial chondromatosis of the TMJ is characterized by chondrometaplasia of the synovial membrane, a process in which cartilaginous nodule formation is followed by detachment, forming loose bodies in the joint space. Although there are radiological findings, a definitive diagnosis requires a histopathologic examination. [7] This condition is considered benign and affects mostly large synovial joints such as knees and elbows; it is very rare in the TMJ, showing predilection for the upper articular space. [8] A challenge in the diagnosis is the inconsistencies because in some cases the nodules are not calcified enough to be evident and observable. [9] The most common signs and symptoms of synovial chondromathosis of the TMJ are pain, swelling and restricted mouth opening; however, in some cases this is an incidental finding. [10]

This is a report of two cases of joint mice of TMJ diagnosed based on the preliminary findings observed in the panoramic radiograph. Calibrated practitioners in orofacial pain from the advanced training program at the Herman Ostrow School of Dentistry of USC performed medical history and clinical examination. Once the cases were identified, the patients signed the authorization to use protected health information for education and instruction form. The first case is a 66-year-old female whose condition was an incidental finding. The second case is a 55-year-old female with jaw clicking and mild pain.

Case One

A 66-year-old female presented with a medical history significant for ulcerative colitis, high blood pressure, high cholesterol, osteoarthritis, depression and insomnia. The patient’s medications include carvedilol, budesonide, rosuvastatin and escitalopram. She visited the clinic for routine dental care and had no complaints of facial pain. Clinical examination showed normal range of motion of TMJ with an active interincisal opening of 48 mm and lateral movements of 8 mm. Muscle palpation revealed tenderness in the superficial and deep masseter muscles bilaterally with no referral pattern. Joint palpation was unremarkable, but crepitus was present in both joints. The presence of joint mice was an incidental finding on her panoramic radiograph (FIGURE 1).

Case Two

A 55-year-old female presented with a chief complaint of jaw clicking and facial pain. The patient has a history of rheumatoid arthritis and is taking hydroxychloroquine and etanercept. Clinical examination showed a normal range of motion of TMJ, with an active opening of 46 mm and lateral movements of 10 mm on each side. Muscle palpation revealed tenderness in the superficial and deep masseter muscles bilaterally. Mild tenderness was noted on the left TMJ on palpation. Clicking sounds were observed on both the TMJ upon wide opening of the jaw; however, no pain was associated with the clicks. On radiographic examination of the TMJ, irregular bone fragments were noticed related with the right TMJ (FIGURE 2).

The radiological characteristics in both cases were consistent with osteochondritis dissecans, stage IV, where the fragments are not attached to the bone surface. Both patients had findings suggesting localized myalgia; the second patient exhibited mild capsulitis. No functional limitations were identified. The followup plan included further imaging and monitor evolution. Physical therapy was included for the muscle pain and anti-inflammatories for the capsulitis.

Discussion

As discussed by Misirlioglu (2014) [5] , the follow-up in cases with degenerative changes includes volumetric imaging in order to have spatial information and to monitor evolution. The use of panoramic imaging as a preliminary diagnostic approach is useful to identify the presence of TMJ alterations such as joint mice; however, cone beam computed tomography provides better diagnostic information of the morphology of the osseous structures of the TMJ, including cortical bone integrity and subcortical bone destruction/production. If an evaluation of soft tissues is required, magnetic resonance imaging is to be considered. [11] For loose bone bodies, the use of volumetric images will provide adequate information regarding location and relationship with the cortical bone.

We selected a conservative approach, including physical therapy and activity modification as a therapeutic alternative, because the use of passive stretching improves muscle mobility and increases the range of motion of the TMJ. [12] It is important to consider that in cases with loose bone bodies, close monitoring will identify the need to intervene with a surgical procedure. Orhan (2006) [6] has suggested considering age, presentation, fragment size and fragment stability to decide the required intervention.

The use of comprehensive clinical examination including range of motion, palpation and auscultation of TMJ and evaluation of masticatory muscles as well as an appropriate protocol for imaging will provide the clinician the information needed to identify conditions such as alterations that might have clinical symptomology but require follow-up and monitoring.

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THE CORRESPONDING AUTHOR, Mariela Padilla, DDS, Med, can be reached at marielap@usc.edu.