Bypassing mandibular osseous defect using the high oblique sagittal split osteotomy: a case report and review of literature.

The presence of a mandibular osseous defect significantly complicates revision orthognathic surgery by increasing the risk of unfavorable fractures and inferior alveolar nerve (IAN) injury. In such instances, the high oblique sagittal split osteotomy (HOSSO) serves as a strategic alternative to the conventional bilateral sagittal split osteotomy. We report a case involving a 31-year-old Chinese female presenting with skeletal relapse twelve years after the primary bimaxillary surgery. Preoperative imaging identified a 1.5×1.5 cm circular osseous defect in the right mandibular body, communicating with the IAN canal. To bypass the defect site, a unilateral HOSSO was performed on the right mandible, while a standard sagittal split ramus osteotomy was utilized on the left. Postoperative clinical and radiographic evaluations at six months demonstrated satisfactory facial profile improvement and stable occlusion, with absence of neurosensory deficits or unfavorable fractures. This case underscores the importance of thorough preoperative radiographic assessment and suggests that HOSSO is a safe, effective technique for bypassing localized mandibular body pathology, particularly during revision procedures.