Distraction Osteogenesis of Costocartilaginous Rib Grafts and Treatment Algorithm for Severely Hypoplastic Mandibles

In craniofacial microsomia, patients with severely hypoplastic mandibles (Pruzansky type III) require replacement of the ramus and condyle unit. Autogenous costocartilaginous rib graft and distraction osteogenesis are the most important techniques used, but long-term results need to be looked at to determine optimal management.Of the 485 patients with craniofacial microsomia and mandibular abnormality identified by the authors' craniofacial multidisciplinary clinic, 31 patients were identified with Pruzansky type III mandibles who underwent treatment and were available for study. Patients primarily had either costocartilaginous grafts or mandibular distraction after molar extraction. Outcomes assessed rib failure, undergrowth, or overgrowth. Reoperation included regrafting for graft failure, rib distraction for undergrowth, and mandibular setback for overgrowth. Details surrounding complications for each modality including osteotomy site were recorded.For primary mandibular reconstruction, 27 patients underwent costocartilaginous rib graft surgery (30 grafts, three bilateral) at 9.9 ± 4.1 years; four patients underwent mandibular distraction at 7.4 ± 2.3 years. Rib graft failure in seven of 30 cases (23 percent) required regrafting. Undergrowth in 17 cases (57 percent) required rib distraction. Overgrowth in three cases (10 percent) required correction at the time of orthognathic correction. For rib graft distraction, osteotomy site locations included native mandible (25 percent), rib-mandible junction (19 percent), and rib graft (56 percent). The rib-mandible junction site had graft-related complications (100 percent) that the other sites did not.For the severely hypoplastic mandibles (Pruzansky type III), costocartilaginous grafts are an accepted modality. However, when rib graft growth is insufficient, secondary distraction should be performed within the native mandible or rib graft and not at the rib graft-mandible junction site.