Problems during Bone Splitting or Fixation in Sagittal Splitting Ramus Osteotomy

要旨

Sagittal splitting ramus osteotomy (SSRO) is commonly used to treat jaw deformities. We must avoid the occurrence of problems that may disrupt the social relationships of our patients.We investigated cases involving unfavorable bone splitting or fixation and studied their causes and measures to prevent these problems.In the last 13 years, 261 SSROs have been performed in our department, of which 11 were problematic cases associated with bone splitting or fixation. The problems consisted of six unfavorable fractures during surgery, one unfavorable fracture postoperatively, and one case each of a screw loosening postoperatively, a miniplate breaking postoperatively, a miniplate loosening postoperatively, and lateral dislocation of the condyle.The most frequent problem was an unfavorable fracture during surgery. The six cases included five bad splits and one incorrect horizontal cut in the lingual aspect of the mandibular ramus. The unfavorable postoperative fracture also resulted from an incorrect cut in the lingual aspect of the mandibular ramus. We treated these cases with re-fixation of the mandible, additional intermaxillary fixation, or both. In all cases, we confirmed bone healing within 1 year. In the case of lateral dislocation, although the patient has had symptoms for a long time, no functional problems have occurred.The loosening or breaking of the miniplate or screw was caused by an incorrect drilling angle into cortical bone or inadequate mobility of the proximal segments due to insufficient dissection of masticatory muscles. The surgeons' skill also affected the results. In each case, the problem might have been avoided if the ramus shape had been known preoperatively and the operation simulated. The basic technique of SSRO has not changed, but the methods and materials used for bone fixation are improving. To avoid these problems, it is essential to understand the patient's anatomy, to simulate surgery and to become proficient with the surgical techniques.

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