Mandibular distraction in the absence of an ascending ramus and condyle.

Abstract

The introduction of distraction osteogenesis (DO) as a method of mandibular elongation has provided the craniofacial surgeon with a valuable tool in the approach to patients with mandibular deficiencies. A growing number of case reports and clinical series have proven the efficacy of mandibular DO as an augmentative technique in patients with hemifacial microsomia (HFM). Although DO has become a part of the treatment algorithm for many patients with HFM, surgeons have been reluctant to apply the technique in patients with complete agenesis of the ascending mandibular ramus and condyle (grade III HFM). In the following cases, mandibular DO was successfully performed in two patients with grade III HFM. Preoperative images and intraoperative findings confirmed that both patients lacked the entire ascending mandibular ramus and condyle on the affected side. After unilateral multiplanar DO, both patients showed new bone formation within the distraction gap and development of a pseudoarthrosis between the proximal segment of the mandible and the skull base. Facial symmetry improved dramatically, and speech and mandibular excursion were maintained. The patients have been followed for 1 to 2 years after distraction with durable functional and esthetic outcomes. Mandibular DO offers many advantages compared with rib grafting, including avoidance of donor site morbidity, application in patients who are not candidates for graft harvest, and use after rib graft failure. The following cases support the use of mandibular DO as a mechanism of endogenous tissue engineering in patients with complete agenesis of the ascending mandibular ramus and condyle.