Synovial Chondromatosis of the Temporomandibular Joint

Synovial chondromatosis is the benign chondroid metaplasia of the synovium. Cartilaginous nodules form at the synovium and may detach to form loose bodies within the joint. Ossification of these bodies changes the name from chondromatosis to osteochondromatosis.

Synovial chondromatosis usually occurs in large joints such as the knee or shoulder, and has a male predominance. Involvement of the temporomandibular joint is rare and has a female predominance. In the temporomandibular joint, it is usually located on the right with a right-to-left ratio of 4 to 1.

Patients present with restricted movement, as well as preauricular swelling and pain.

Radiographs may reveal widening of the joint space, limitation of motion, irregularity of the joint surfaces, calcified loose bodies, and sclerosis of the glenoid fossa and mandibular condyle. When all these findings are present, a diagnosis of synovial chondromatosis can be made on radiographs; however, some or even all of these findings (except for calcified bodies) can also be seen with osteoarthritis.

On CT and MR, the diagnosis is more straightforward with demonstration of cartilagenous or ossified objects within the joint with joint effusion and erosions of the joint surfaces.

References

• Herzog S, Mafee M. Synovial chondromatosis of the TMJ: MR and CT findings. AJNR Am J Neuroradiol. 1990 Jul-Aug;11(4):742-5.
• Koyama J, Ito J, Hayashi T, Kobayashi F. Synovial chondromatosis in the temporomandibular joint complicated by displacement and calcification of the articular disk: report of two cases. AJNR Am J Neuroradiol. 2001 Jun-Jul;22(6):1203-6.
• Manco LG, DeLuke DM. CT diagnosis of synovial chondromatosis of the temporomandibular joint. AJR Am J Roentgenol. 1987 Mar;148(3):574-6.