Internal Derangement of the Temporomandibular Joint

Internal Derangement of the Temporomandibular Joint (TMJ), more commonly known as dislocation of the TMJ, occurs due to an abnormal positional and functional relationship between the articular disc and the articulating surface. The images above are from a patient with anterior dislocations of the bilateral TMJs.

While this abnormality can usually be detected on plain films or bone NECT, MRI is the best modality to evaluate the TMJ especially in cases of recurrent derangement. On MRI, the low signal intensity articular disc will be displaced relative to the mandibular condyle. T1WI can show specific disc abnormalities including perforation, fibrosis or adhesions. The presence of a joint effusion can be detected as high signal on T2WI. The presence of synovitis can be detected as enhancement of the disc on T1WI after administration of contrast.


REFERENCES
Sommer OJ, Aigner F, Rudisch A, et al. Cross-sectional and functional imaging of the temporomandibular joint: radiology, pathology, and basic biomechanics of the jaw. Radiographics 2003;23:e14.
Tomas X, Pomes J, Berenguer J, et al. MR imaging of temporomandibular joint dysfunction: a pictorial review. Radiographics 2006;26:765-81.