Purpose: This study was to evaluate the change of condylar position after BSSRO with posterior bending osteotomy (PBO) to minimize the interferences between proximal and distal segment in facial asymmetry.

Methods: PBO was done to minimize major interferences between proximal and distal segment after BSSRO in patients with facial asymmetry ( n = 13), while grinding of proximal and distal segment was used in minor interferences ( n = 9). The condylar torque due to inter-segmental interferences was evaluated using preoperative and postoperative CT: (1) condylar position within glenoid fossa by measuring the intra-articular space of condylion, (2) the change of condylar position by calculating the amount of condylar displacement on condylion, lateral and medial pole, and (3) analyzing the change of condylar axis 3-dimensionally using Mimics 13.0 (Materialise NV, Belgium). The comparison between PBO and grinding method and between deviated and non-deviated side were performed and statistically analyzed.

Results: The condyles were well-positioned in the glenoid fossa in both groups. The amount of condylar displacement on condylion showed statistically significant difference between deviated and non-deviated sides in grinding method, while it was similar on deviated and non-deviated side with PBO. The condyles on deviated side in grinding method rotated more to lateral side compared with those of PBO method.

Conclusion: If the bony interference is great, PBO is useful to remove bony interference between proximal and distal segment. If the bony interference is little, bone grinding may be effective.

Conflict of interest: None declared.