Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative dynamic positioning and monitoring by sonography.

PURPOSE: Most methods of condylar positioning merely maintain the preoperative condyle-fossa relationship and therefore produce similar prevalences of postoperative dysfunction. This study evaluates dynamic proximal segment positioning by intraoperative sonography versus the splint and plate technique discussed in a previous issue.

PATIENTS AND

METHODS

Condylar positioning was monitored by sonography alone in 30 bimaxillary operated patients (14 Angle Class II, 16 Class III), the control group had a splint and plate positioning in 23 patients (9 Angle Class II, 14 Class III). The clinical dysfunction index, prevalence of condylar translation, and disc dislocation were compared preoperatively and at 1, 6, and 12 months postoperatively.

RESULTS

The postoperative range of motion did not disclose statistically significant differences between study and control group (Pearson's proportionality index r = 0.78, 2-way analysis of variance: P <.4, F = 4.4, alpha =.05 significance level). Sonographic placement allowed dynamic intraoperative monitoring of the condylar position and required an average of 5 minutes compared with 25 minutes for conventional positioning. Postoperative dysfunction prevalence was reduced 89% for Class II and 100% in Class III in the study group versus 50% for Class II and 100% for Class III in the control group (r = 0.45, P <.3, F = 9.3). Prevalence of disc dislocation was reduced 76% in Class II and 80% in Class III patients in the study group and 50% of Class II and 100% of Class III in the control group (r = 0.7, P <.48, F = 9.2).

CONCLUSIONS

Comparable postoperative reduction of condylar translation and recovery, dysfunction, and disc dislocation was seen with use of both methods in a 1-year follow-up. The new technique allowed intraoperative real-time monitoring and dynamic correction and was safe, easier, and faster than conventional plate positioning.