Le ligament sphénomandibulaire, obstacle anatomique à l’allongement du ramus

Abstract

The sphenomandibular ligament is strong and its insertion below the medial cut of the sagittal split osteotomy explains that it is a barrier to the mobilization of the distal segment. It is the main obstacle to ramus lengthening. We describe the disinsertion technique with an anatomical dissection. After sagittal split ramus osteotomy, we verify that a stable occlusion has been achieved without straining. In case of resistance, a 90° angled periosteal rugine is introduced below the periosteum, against the medial cortex. It is used to detach the last fibers of the medial pterygoid muscle under visual control, and it is carefully moved to the lingula to detach the anterior sphenomandibular ligament insertion. In case of a very short ramus, there is hypoplasia of soft tissues, especially the pterygomasseteric sling, and the stylomandibular ligaments are short. This is why it seems necessary to release the sphenomandibular ligament in all forms of ramus lengthening.