Surgical treatment of the jaw deformities in hemifacial microsomia.

The surgical treatment of the mandibular and maxillary deformities in patients with hemifacial microsomia requires some form of mandibular lengthening. This is usually either via ramus interpositional bone grafting or end-on bone grafting. In a few cases, ramus lengthening may be completed by a sagittal split. Once the mandible has been reconstructed, the maxillary surgery can be completed. In previous forms of treatment, mandibular bone grafting was completed without regard to function and neuromuscular adaptation and a significant percentage of such procedures completed failed. Egil Harvold and his colleagues developed a method by which changes in form and function are co-ordinated by using a functional appliance resulting in neuromuscular adaptation. After the bone grafting is completed, as the second of six phases of treatment, a specially designed registration bite-block further facilitates neuromuscular adaptation by controlling mandibular movements (function), but in addition it protects the bone graft from excessive forces thereby aiding in osteogenesis (third phase). The theoretical basis, classification of deformities, and phases of treatment developed are presented and the surgery is described in detail. The results of a consecutive group of patients treated by these methods is then presented. While this form of treatment is not the only one possible, it is the only one that has been tested in the laboratory, proven in patient care, and stood the test of time.