Analysis of temporomandibular joint ankylosis caused by condylar fracture in adults.

PURPOSE: To analyze the main causes of temporomandibular joint (TMJ) ankylosis from condylar fracture in adults through a retrospective study.

MATERIALS AND

METHODS

The history and computed tomographic (CT) scans of patients diagnosed with ankylosis caused by mandibular condyle fracture treated in a closed fashion from 2010 to 2012 were reviewed in the department of oral surgery. According to the relation between the stump of the ramus and the TMJ fossa, condylar fractures were divided into 3 grades: grade 0, in which the ramus stump is in the fossa but without contact to it; grade 1, in which the stump of the ramus is in the fossa and attached to it; and grade 2, in which the stump of the ramus is laterally displaced out of the fossa. Other factors, such as type of condylar fracture, displacement of the fractured fragment, position of the disc, and the presence of concomitant mandibular fractures, also were analyzed for ankylosis development.

RESULTS

Of the 51 patients diagnosed with TMJ ankylosis, 13 patients (24 ankylosed joints) had full CT scans from injury to ankylosis, which showed that all condylar fractures were intracapsular fractures (ICFs), with sagittal fractures comprising 70%. Regarding the relation between the stump of the ramus and the TMJ fossa, no joints were classified as grade 0 (0%), 10 joints were classified as grade 1 (41.7%), and 14 joints were classified as grade 2 (58.3%). All discs were displaced with the fracture fragment, and the posterolateral retrodiscal tissue was torn. Among the condyle fractures leading to ankylosis, 77% featured symphysis fractures with widening of the mandibular arch.

CONCLUSION

The relation between the ramus stump and the TMJ fossa plays an important role in the prognosis of condylar fracture. Grade 0 is less likely to cause ankylosis; grade 1 is more likely to cause ankylosis and is the relative indication for surgery; and grade 2 is the strongest predictor of ankylosis and is the absolute indication for surgery. Other risk factors are sagittal ICFs and combined mandibular fractures with widening of the mandibular arch.