Dynamic Stability Assessment of the Temporomandibular Joint as a Sequela of Open Reduction and Internal Fixation of Unilateral Condylar Fracture.

PURPOSE: Dynamic stability of the temporomandibular joint (TMJ) is the characteristic of the joint to achieve normal function by harmonious, balanced, synchronized interactions of the various functional subunits of the stomatognathic system. The aim of this study was to evaluate changes in the mechanics and dynamics of the TMJ during recovery from surgical treatment of an isolated condylar fracture.

PATIENTS AND METHODS: This is a prospective cohort study involving 30 patients who underwent open reduction and internal fixation for an isolated unilateral condylar fracture and were clinically asymptomatic at 6 months after surgery. The dynamics of the TMJ were assessed by bite-force analysis, both static and dynamic, to assess masticatory efficiency. Surface electromyography was recorded to assess changes in muscle dynamics. Joint vibration analysis was performed to evaluate the internal functioning of the TMJ. All the assessments were carried out bilaterally to allow comparison of the injured and uninjured joints, and the data were analyzed with the paired t test and independent-samples t test. Statistical significance was considered at P < .05.

RESULTS: The study included 18 male and 12 female patients aged between 20 and 40 years. Bite-force analyses showed significantly higher bite forces on the uninjured side at 6 months after surgery. Similarly, surface electromyography analysis showed increased muscle activity on the affected side pointing toward some compensatory hyperactivity in the masticatory muscles. Joint vibration analysis showed that there was increased friction during function in both the injured and uninjured joints.

CONCLUSIONS: The observations in this study suggest that residual imbalances are present in the TMJ at 6 months after open reduction and internal fixation of condylar fractures. Therefore, long-term studies are required to establish a complete timeline of adaptive changes occurring in the TMJ after condylar fractures, especially in comparison with other treatment modalities.