[TMJ-function and -morphology after mandibular translocation-osteotomies with and without positioning plates]

Positioning devices are commonly used to avoid the malpositioning of the proximal segments in bilateral, sagittal split osteotomies and to make sure the preoperative fossa condyle relation is reproduced. The aim of our prospective study, with random selection of 24 patients, was to compare the morphological and functional outcome of the TMJs. The proximal segments in half of the patients had been positioned using devices, in the other half without devices. The segments were fixed by transoral bicortical miniscrew fixation. The evaluation of function is based on pre- and postoperative clinical and electronic axiographic investigations. To study the TMJ morphology, we performed MRI and X-ray investigations preoperatively and 6 months postoperatively. Preoperatively, 12 patients showed slight dysfunction, six patients moderate, and six patients severe dysfunction. Postoperatively, no patient was symptomless. Slight dysfunction was presented in 15 cases, moderate dysfunction in five and severe dysfunction in four cases. Evaluating the axiographic investigations preoperatively, 22 patients showed no mobility disturbances of the TMJ. Two patients showed severe mobility disturbances. Postoperatively, a significant increase in TMJ mobility disturbances could be seen. The MRI investigations of both groups showed both worsening and improvement in the disk positions. No significant differences could be determined between the two groups, however. Regarding the X-ray investigation, three patients from the group with positioning devices showed dislocated condyles; in the group without positioning devices four cases of condyle dislocation were seen. All dislocations were transversal except for one case in the group without positioning devices. Positioning devices do not seem to improve the functional and morphological outcome of the TMJ after BSSO.