[Morphometric analysis of the temporomandibular joint with MRI in 320 joints].

PURPOSE: To compare several morphometric parameters in MRI with the functional status of the articular disc in a large patient group suffering from internal derangement (ID) of the temporomandibular joint (TMJ).

MATERIALS AND METHODS: In a retrospective study, 320 analyzable high resolution MRI examinations of the TMJs obtained in a 1.5 T unit were evaluated in 184 patients with clinically suspected ID. The analysis included the anatomical structures and a number of morphometric parameters previously described in the literature. The parameters were compared with the position of the articular disc.

RESULTS: The disc position was categorized as "normal" (NDP, 21.9 %, n = 70), "anterior displacement with reduction on opening" (AMR, 51.6 %, n = 165) and "anterior displacement without reduction on opening" (AOR, 26.6 %, n = 85). With increasing disc displacement, significant configurational changes of the disc were observed. Disc displacement was associated with changes of the condyle consisting of increasing deformity and other degenerative changes. A large tuberculum and marked inclination of the eminence can be seen as predisposition for the development of ID. With increasing severity of the ID, the position of the condyle moved from a centric position of the condylar center to an excentric (dorsal and cranial) position.

CONCLUSION: MRI demonstrated that increasing disc displacement is associated with changes of the disc, condyles and condylar position in the fossa.