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Radiographic stereophotogrammetric evaluation of intersegmental stability after mandibular sagittal split osteotomy
1Department of Oral and Maxillofacial Surgery, Helsingborg Hospital, Helsingborg, Sweden. gert.wall@helsingborgslasarett.se
Purpose:
The purpose of this study was to determine if rigid fixation with bicortical screws and/or miniplates with monocortical screws prevent mobility at the osteotomy site after bilateral mandibular sagittal split osteotomy.
Patients And Methods:
Three metal bone markers were inserted in the proximal and the distal segments of the mandible during the sagittal split operation in 10 patients. These served as measurement points in postoperative follow-up by radiographic stereophotogrammetry. The patients were examined at intervals during the first postoperative year. At each examination, 2 sets of radiographic stereograms were obtained: 1 in rest position and 1 with stress applied to the osteotomy sites. The difference in the position of the proximal segment in relation to the distal segment between the 2 sets of stereograms was recorded. Findings greater than 0.4 degrees and 0.2 mm change indicated true displacement of the bone segments.
Results:
Immediately after surgery, mobility at of the osteotomy site(s) was found in 8 of 10 patients, and after 1 year it was still present in 4 patients.
Conclusions:
Fixation with bicortical screws or miniplates and monocortical screws does not prevent mobility at the osteotomy site after sagittal split osteotomies. This mobility may remain as long as 1 year after surgery. The term "rigid fixation" is thus not a proper term for this kind of fixation.