Postoperative migration at the individual osteotomy site following sagittal split ramus osteotomy: a stereometric radiographic study.

The aim of the present study was to evaluate whether migration occurs at individual osteotomy sites following sagittal split osteotomy of the mandible stabilized with rigid internal fixation, and if it occurs, how long it lasts. In 10 consecutive patients operated with bilateral sagittal split osteotomies, postoperative migration, defined as displacement of the proximal segments in relation to the distal over time, was studied 3-dimensionally by means of stereometric radiography. Follow-up was performed with stereometric radiographs obtained at intervals from 2 days until 1 year after surgery. During the 1-year observation period, migration at one or both of the osteotomy sites was found at some stage in all of the patients and in as many as 4 patients during the final 6 months. It is concluded that rigid internal fixation, as performed in the present study, does not prevent postoperative migration at the osteotomy. Furthermore, stable bone union at the osteotomy site appears to be a slower process than previously expected, thus emphasizing the importance of follow-up procedures to prevent relapse.