[Loose bodies of the temporomandibular joint. A rare pathology].

Loose bodies of the temporomandibular joint (TMJ) are an uncommon condition which can be caused by various complaints that can now be diagnosed with high resolution CT. The authors report on 10 cases observed from 1983 to 1992 which were studied with both conventional radiography and CT. The most common conditions were synovial chondromatosis and osteochondrosis dissecans. In the two cases of synovial chondromatosis, the demonstration of ossified loose bodies made the diagnosis easier. The cases of osteochondrosis dissecans presented with more complex diagnostic problems: in two instances the characteristic subchondral bone fragment in the condylar head was clearly visible, but in the third case this small fragment was difficult to identify as it had migrated backwards, making the disorder troublesome to diagnose. An osteophyte fracture and the presence of a bone fragment following condylar head fracture were easily diagnosed by correctly assessing the associated articular changes resulting from an arthrosic and a traumatic condition, respectively. The only case of loose body due to previous TMJ remodeling was easily diagnosed as the totally ossified formation was not seen on the preoperative X-ray film. Finally, two very similar cases, characterized by the presence of an elongated radiopaque formation in the site of the posterior meniscal ligament, were difficult to interpret as no such case is reported in the literature. In both cases an anatomical variant was presumed, characterized by posterior meniscal ligament ossification.