Correction of hemifacial microsomia in the growing child: a follow-up study.

: Based on longitudinal observation of more than 80 patients, we concluded that mandibular hypoplasia is the earliest skeletal manifestation of hemifacial microsomia. The clinical defect becomes worse with time as a result of continued asymmetric growth and progressive secondary deformation of the midface. We hypothesize that midface growth is restricted by the hypoplastic mandible. Therefore, early elongation of the mandible should result in a more symmetrical growth pattern by eliminating mandibular restriction and creating a space for vertical midface growth.