Endoscopic-assisted medial osteotomy during sagittal split ramus osteotomy.

In this article, we describe endoscopic-assisted medial ramus osteotomy during sagittal split ramus osteotomy (SSRO). Surgical repositioning of the mandible by bilateral SSRO has become a safer and more reliable procedure through ingenuity of surgical methods, development of special instruments and improvement of surgical skills. The horizontal medial osteotomy should be located at or just above the tip of the lingula and terminated just posterior to the lingula, and carried through the lingual cortex into the medullary bone of the mandibular ramus. However, unfavourable fractures sometimes occur during the intraoral approach. When the osteotomy is terminated anterior to the lingula, the bone tends to split anterior to the lingula. Osteotomy located too far superior to the lingula or angled too far upwards and not parallel to the occlusal plane may also risk unfavourable fractures, which includes the condylar process. The lingula, therefore, should be carefully identified to avoid such complications. However, even after reduction of the internal ridge with an angled blade, it is not always easy to visualise the lingula due to the convex form of the intraoral oblique ridge. In such cases, the medial bone must be cut under poor visibility. An endoscope provides excellent visualisation in many operative situations, and has been applied for vertical ramus osteotomy in orthognathic surgery. For SSRO, however, we found only one report of an unfavourable fracture of the ramus that had been repaired using an endoscopy-assisted technique. We used a 30, 67 mm-long endoscope with a 4 mm diameter and a concave blade retractor connected to a video camera system (Karl Storz, Tuttingen, Germany) for medial osteotomy during SSRO (Figure 1). The device was originally developed for assisting in the reduction of subcondylar fractures. After conventional soft tissue and periosteum incision, and exposure of the bone surface of the anterior ramus, medial soft tissues are reflected subperiosteally to the posterior border of the ramus. The endoscope is inserted along the medial side of the mandible. A focal distance of 30 mm and a wide visual angle are adequate for direct visualisation of the medial operative site, notch of the lingula, mandibular notch and condylar