Dislocation of the temporomandibular joint meniscus: contrast arthrography vs. computed tomography.

A prospective study to determine the accuracy of computed tomography (CT) for the diagnosis of dislocation of the temporomandibular joint (TMJ) meniscus was made by performing both CT and contrast arthrography on 18 joints suspected of meniscus dislocation. Arthrography rather than surgery was chosen as the quality standard for comparing CT findings, as not all patients undergoing the studies underwent surgery. The CT protocol included scanning with both closed- and open-mouth series, 1.5-mm-thick slices, soft-tissue and bone-detail settings, and coronal and sagittal reformations. Arthrography was done with linear tomography, after both lower and upper compartmental injections under fluoroscopic control. The results of each test were reported independently by the radiologist who obtained either all of the arthrograms or all of the CT scans. For dislocation of the meniscus, there was excellent agreement between the two methods. Nine menisci were dislocated according to both arthrography and CT. One meniscus was thought to be dislocated by CT, but this was not confirmed with arthrography. CT seems to be nearly as accurate as arthrography for showing meniscus dislocation, is performed with lower x-ray exposure, and is noninvasive. Arthrography discloses more detailed information about the joint meniscus, such as perforation and maceration, and should continue to be used when this kind of information is clinically important.