Sagittal Split Osteotomy in a Previously Distracted Mandible

Sir:FigureMandibular distraction osteogenesis was first performed in a patient in May of 19891 and has become a recognized technique for mandible lengthening. A retrospective, institutional review board–approved review was performed of 211 mandibular distraction procedures from May of 1989 to May of 2009. Two patients were identified who previously had undergone unilateral mandibular distraction osteogenesis in childhood for the correction of craniofacial microsomia and then underwent sagittal split osteotomy of the distracted mandible along with a Le Fort I osteotomy at the time of skeletal maturity. The patient in case 1 was a male patient who presented with right unilateral craniofacial microsomia and plagiocephaly. He had a right microtia, right marginal mandibular nerve palsy, and a partial frontal branch palsy. He had a right epibulbar dermoid and strabismus. There was unilateral underdevelopment of the cheek soft tissues, a macrostomia, and occlusal cant. He had a Pruzansky-Kaban grade I mandible,2,3 a congenital fusion of C5-C6 vertebrae, and a right seventh cervical rib with a torticollis. His renal tract was normal. At age 9 months, he underwent frontoorbital advancement with cranial vault remodeling. At age 22 months, he was the first patient to undergo mandibular distraction.1 At age 19 years, he underwent a Le Fort I osteotomy with bilateral sagittal split osteotomies of the mandible and asymmetric genioplasty for correction of an anterior open bite, with a class III malocclusion. Six months later, he underwent reconstruction of the soft tissues of the right face with a free right circumflex scapular adipofascial flap. The patient in case 2 was a female patient who presented with right craniofacial microsomia with a right Pruzansky-Kaban grade IIa mandible2,3 and a right microtia. At age 3 months, she underwent repair of a right macrostomia and excision of bilateral accessory preauricular auricles. She had a left (contralateral) congenital marginal mandibular palsy. At age 4 years, she underwent distraction osteogenesis of the right mandible. At age 18, she underwent a Le Fort I osteotomy, bilateral sagittal split osteotomies of the mandible, and genioplasty. Preoperatively, the patient had a significant occlusal cant of 8 degrees up on the right side with micrognathia and mandibular asymmetry. A preoperative three-dimensional computed tomographic scan was obtained (Fig. 1).Fig. 1: A preoperative three-dimensional computed tomographic scan was obtained for patient 2 and the images were analyzed using OsiriX software. (Left) The length of the right (previously distracted) mandibular ramus from the sigmoid notch to the inferior border of the mandible was 4.14 cm. (Right) The thickness of the right lateral cortex behind the molar teeth on the side that had undergone distraction osteogenesis was 0.20 cm; also note the well-developed cancellous bone. The length of the left (nondistracted) mandibular ramus from the sigmoid notch to the inferior border of the mandible was 5.54 cm. The thickness of the left lateral cortex behind the molar teeth was 0.21 cm.Distraction osteogenesis of the mandible has become an established technique that is useful in the management of growing patients with craniofacial microsomia.1 When children attain skeletal maturity, it may be necessary to correct problems in occlusion and facial dysmorphism with a combination of Le Fort I osteotomy, bilateral sagittal split osteotomies of the mandible, and genioplasty. There had been concern that mandibular bone generated following distraction would not provide the skeletal architecture (i.e., bicortical bone with an intervening marrow space) that is critical for the success of a sagittal split of the ramus and body of the mandible. However, we found that the distracted bone is of satisfactory quality to perform a sagittal split osteotomy, and computed tomographic measurements (Fig. 1) demonstrated cortical bone similar in thickness and architecture to that of the nondistracted side. This supports the findings in animal studies of mandibular distraction.4 Aina V. H. Greig, Ph.D., F.R.C.S.(Plast.) Hitesh Kapadia, D.D.S., Ph.D. Barry H. Grayson, D.D.S. Joseph G. McCarthy, M.D. Institute of Reconstructive Plastic Surgery, New York University Langone Medical Center, New York, N.Y. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article.