Objectives: To show the characteristic MRI features of synovial chondromatosis (SC) of the temporomandibular joint (TMJ).
Methods: All patients with histologically proven SC of the TMJ who underwent MRI at our clinic were examined. In 14 patients (male-to-female ratio, 2:12; average age 46+/-14 years), clinical and conventional radiographic findings were reviewed. In addition, the MRI findings of articular disc and condyle position, shape and signal intensity of the joint spaces, and bone changes of surrounding structures were analysed.
Results: The main symptoms were pain (in 93% of the patients) and limitation of mouth opening (64%). Two cases showed typical multiple calcifications around the TMJ on conventional radiography. On MRI, the disc position was normal in 12 (86%) patients and the condyle was inferiorly displaced in 9 (64%) patients. 11 (79%) patients showed enlargement of the joint space, with either a "dumbbell" shape or bulging. SC in the upper compartment showed various degrees of bone changes of the articular eminence and fossa. SC in the lower compartment showed concavity or hypertrophy of the condyle. The severity of the bone changes progressed with duration of symptoms.
Conclusions: About 0.3% of the patients complaining of TMJ pain and dysfunction were found to have SC. There was great variation in the MRI features of the TMJs with SC. More severe destruction of surrounding bone structures with features resembling a tumour were found in patients with a longer duration of symptoms.