Safety And Effect Of Mandibular Distraction Osteogenesis For Hemifacial Microsomia

Background:Mandibular distraction osteogenesis was applied for hemifacial microsomia.This study focus on the complications and masseter muscle volume change after mandibular distraction osteogenesis process,aiming to assess the safety and effect on mandibular distraction osteogenesis in children with hemifacial microsomia.Methods:This retrospective study examined the records of 71 hemifacial microsomia patients undergoing mandibular distraction osteogenesis from February 2010 to March 2015.Three-dimensional reconstruction,computer-aided design and rapid prototyping technique were adopted to assist the modified mandibular osteotomy.Distraction began 4-7 days postoperation with a frequency of 1 mm/d and the distractor was kept in place 4 to 13 months,then the distractor was removed.All incidents encountered during and following the mandibular distraction process were documented.Then,25 cases were arranged for masseter muscle volume measurement by Mimics software.Mandibular Ramus Height and masseter muscle volume was measured.Results:The average follow-up period is 34.4 months.The overall rate of complication incidents was 36.6%.Minor complications that could be resolved with or without noninvasive therapy were observed in 18.3%of all procedures.Moderate complications needing invasive therapy were reported in 12.7%.The rate of major complication that could not be resolved with invasive therapy was 5.6%.Amomg 25 cases with masseter muscle volume measurement,the height of mandibular ramus after osteogenesis was significantly increased than that before osteogenesis(32.2±6.4mm vs 39.2±5.9mm,P<0.001).Masseter muscle volume in the affected side increased significantly after osteogenesis(5343 ± 342mm3 vs 6580± 413mm3,P=0.008).Type IIA or IIB mandibular deformity show no impact on the improvement of masseter muscle volume,neither the change of mandibular ramus height.Conclusions:Regardless of incidents,mandibular distraction osteogenesis remains a safe and predictable procedure for lengthening the mandible in hemifacial microsomia patients.Besides,distraction osteogenesis may help to increase the masseter muscle volume in hemifacial microsonia.