Effects of Mandibular Distraction Osteogenesis on Three-dimensional Airway Anatomy in Children with Congenital Micrognathia

Purpose: To assess the 3-dimensional (3D) computed tomography (CT) changes in airway size and shape in children with congenital micrognathia treated by mandibular distraction osteogenesis (DO).

Patients And Methods: This was a retrospective study of patients with congenital micrognathia, treated by mandibular DO, who had pre- and postoperative 3D maxillofacial CT scans from the hard palate to the hyoid bone. Digital 3D-CT reconstructions were made before and after distraction. Demographic (age, gender, and diagnosis) and anatomic (airway size and shape) variables were recorded and analyzed. The pre-distraction measures of size and shape were compared with the post-distraction measures. P≤.05 was considered significant.

Results: During the study period (1999 to 2010), 17 children with congenital micrognathia underwent mandibular DO. Of these patients, 11 (3 females) met the inclusion criteria. The mean age was 6.8 years (range 1.3 to 20.6). All subjects had first and second pharyngeal arch deformities. Nine were tracheostomy dependent before distraction. Postdistraction increases in the anteroposterior diameter (153%), lateral airway diameter (70%), airway volume (76%), minimal retroglossal (162%) and retropalatal (77%), and minimal cross-sectional areas (282%) were obtained. The mean airway length decreased after distraction by 4 mm DO also affected the airway shape: the airway surface area and airway compactness increased after distraction. Six subjects were decannulated or had their tracheostomies capped. Three subjects remained tracheostomy dependent after distraction. The reasons for continued tracheostomy included copious secretions, muscle hypotonia, hypopharnygeal stenosis, and mandibular hypomobility.

Conclusions: DO for congenital micrognathia increases airway size, decreases airway length, and alters the shape as measured using 3D-CT.