The influences of distraction osteogenesis therapy on airway morphology in patients with hemifacial microsomia

Summary Objective Focused on the measurement of the oropharynx and laryngopharynx, the aim of this study was to explore how mandibular distraction osteogenesis affects the morphological changes of the oropharynx and laryngopharynx. Method We designed a retrospective study of airway parameters measurement in CFM patients undertaking the mandibular distraction osteogenesis treatment. The indication of the surgical treatment was the obvious facial asymmetry. Mimics 17.0(Materialise Inc. Belgium) was used to build 3D models of the oro- and laryngopharynx. The minimum cross-sectional area (CSA), mean-CSA, volume, length, and surface area were measured in the 3D models. All data were entered into SPSS v23.0 (SPSS Inc. USA), statistical differences pre-and postoperatively were assessed by using Wilcoxon test. Results Thirty-two patients diagnosed with CFM were included in this study. Five were classified as type IIa，21 as type IIb and six as type III using the Pruzanksy-Kaban classification. The average age of the patients was 8.34 years old; 14 were females and 18 were males. The average traction time was 35.59 days and the average length of traction was 35.81 mm. The total volume of the airway was significantly increased after MDO (P=0.001). In the oropharynx and laryngopharynx segments, the mean-CSA, minimum CSA and surface area were significantly different in statistical results. From the results, the expansion of oropharynx and laryngopharynx were found after MDO. Conclusion As one of surgery treatment, MDO could expand the volume of oropharynx and laryngopharynx in 3D CT models. It was found the increase in the mean-CSA, minimum CSA and surface area in oropharynx and laryngopharynx after MDO in measurement as well. Thus, the MDO is considered as a clinically useful treatment to change oropharynx and laryngopharynx structure.