Abstract
BACKGROUND: To evaluate musculoskeletal modification after open reduction and internal fixation of condylar fracture by clinical examinations and computed tomography reconstruction to guide the clinical therapeutic strategy. MATERIALS AND METHODS: This retrospective study enrolled patients with condylar fracture treated by open reduction of internal fixation (ORIF) between November 2015 and January 2020 and followed up for over 2 years. Mouth opening, mandible deviation and occlusal relationship were compared before ORIF and 2 years after ORIF. Condyle volume, ramus height, masseter volume and lateral pterygoid volume immediately and 2 years after ORIF were reconstructed and compared among different fracture types (including condylar head, neck and base fractures), fixation types (including screws and plates) and implanted material removal or not using statistical analysis. This retrospective study was subject to inherent limitations, including possible selection bias and lack of standardised imaging protocols. All retrospective data usage complied with institutional ethical approval. RESULTS: The study involved 105 patients with unilateral condylar fractures. Condylar head fractures accounted for 53% of the total, condylar neck fractures for 24% and condylar base fractures for 23%. The average mouth opening increased from 1.4 ± 0.8 cm to 3.8 ± 0.7 cm following the procedure. Mandible deviation decreased from 39.3% to 6.2%. Abnormal occlusal relationships decreased from 84% to none. As the fracture line moved up to the condylar top, more condylar bone resorption and masticatory muscle atrophy tended to occur. Screw fixation showed significant condylar bone resorption compared to plate fixation. The retention of the implanted material showed a significant negative influence on ramus height and condyle volume while removal of the implanted material significantly led to masticatory muscle atrophy. CONCLUSIONS: The musculoskeletal modification after ORIF of a condylar fracture is closely related to fracture type, fixation types and implanted material removal. Surgeons should be aware of these trends and choose therapies accordingly. CLINICAL RELEVANCE: This study revealed that prolonged retention of implanted materials is associated with long-term bone resorption, whereas a second surgery may lead to masticatory muscle atrophy, which provides insight into non-removable implanted materials with mechanical properties closer to human bone.