Videofluoroscopic analysis of temporomandibular joint ankylosis

The causes of temporomandibular joint (TMJ) ankylosis, or hypomobility, are many, and it is important to understand the underlying etiology before treatment. Classically, TMJ ankylosis has been diagnosed by clinical evaluation and static imaging techniques such as plain radiographs, computed tomography, and magnetic resonance imaging. Static imaging demonstrates the size and location of the bones and soft tissues of the TMJ at a given moment; however, it fails to show the dynamic relationship of structures as the condylar head goes through its range of motion. The purpose of this study is to evaluate the use of videofluoroscopy as a dynamic means of assessing TMJ ankylosis. To do so, videofluoroscopy must be able to distinguish between bony fusion, fibrosis of the surrounding soft tissues, degeneration of the joint space, and mechanical causes of joint limitation. Six patients--2 healthy controls and 4 patients with known TMJ ankylosis--were submitted to standardized videofluoroscopic evaluation and thorough physical examination that included measurement of mandibular excursion. Videofluoroscopic data were compared with physical data. Condylar displacement was recorded in all patients, and values ranged from 0% to 100%. Videofluoroscopy allowed for the measurement of the TMJ joint space and for a detailed observation of bony and soft tissue components as they ranged in motion. In all cases, the exact cause limiting mandibular excursion was noted. Videofluoroscopy has become our preferred method of imaging the TMJ because it provides a detailed and dynamic evaluation at a reasonable cost.