Pearls and Pitfalls in the Preoperative Planning for Maxillomandibular Advancement

Obstructive sleep apnea (OSA) is often of multifactorial etiology. When the pathogenesis of OSA is associated with anatomical abnormalities such as retrognathia, bimaxillary retrusion, transverse maxillary deficiency, and clockwise inclination of the occlusal plane, skeletal correction is indicated. The maxillomandibular advancement (MMA) for OSA treatment is a site-specific surgery that enlarges the posterior airway space and increases pharyngeal wall tension at multiple anatomic levels, including the nasopharynx, oropharynx, and hypopharynx. The MMA for airway expansion is carried out through osteotomies of the maxilla, mandible, and chin with available concomitant adjunctive procedures such as nasal septoplasty, bilateral inferior turbinate reductions, uvulectomy, and genial tubercle advancement. Advancement of the maxilla pulls the soft tissues of the palate forward, including the palatoglossal muscles, and increases tongue support. Advancement of the mandible repositions several muscles forward, including the anterior belly of the digastric, mylohyoid, genioglossus, and geniohyoid muscles. Both maxillary and mandibular surgeries increase available tongue space. The genial tubercle advancement provides additional advancement of the genioglossus and geniohyoid muscles. The MMA is a first-line surgical treatment for patients with pre-existing dentofacial deformities, severe OSA, and/or complete concentric collapse airway pattern (at velum and lateral pharyngeal walls), as demonstrated by drug-induced sleep endoscopy (DISE). Secondary indications for MMA are failure of other forms of therapy. The success rate for MMA ranges between 75% and 100%. In addition to AHI reduction, the MMA also mitigates patient symptoms and comorbid risk. It is important to clarify the patient’s diagnosis of occlusion and facial aesthetic needs in addition to sites of upper airway obstructions. In efforts to maximally treat OSA, treatment planning includes a cosmetically viable maximal skeletal advancement for the maxilla, mandible, and chin with maximization of the chin advancement through counterclockwise (CCW) rotation. For most patients, facial aesthetics can be improved or preserved through the MMA. Unpleasant aesthetic changes may result in the perinasal region if strategies are not employed to limit perinasal fullness, such as CCW rotation and recontouring of the nasal floor and aperture. The purpose of this chapter is to review pearls and pitfalls in the preoperative planning for maxillomandibular advancement.