Airway changes and prevalence of obstructive sleep apnoea after bimaxillary orthognathic surgery with large mandibular setback

This study used three-dimensional computed tomography and polysomnography to evaluate the effect of a large mandibular setback on the postoperative pharyngeal airway space and obstructive sleep apnoea (OSA). Twelve patients who underwent bimaxillary surgery for a mandibular setback movement of >9mm were included in this study. Changes in the pharyngeal airway space and polysomnography parameters based on the surgical movements were analyzed. The median mandibular setback movement was 11.08mm. The total pharyngeal, oropharyngeal, and hypopharyngeal volumes, and the retroglossal cross-sectional area were significantly decreased postoperatively (P=0.006; P=0.005; P=0.012; P=0.005, respectively). The apnoea-hypopnoea index (AHI) increased significantly after surgery (P=0.021). There were significant positive correlations between the preoperative inferiorly located hyoid bone and both AHI and respiratory disturbance index (RDI) postoperative (P=0.008 and P=0.027) and between the postoperative inferiorly dislocated retropalatal level and both AHI and RDI postoperative (P=0.002 and P=0.014). Four patients (33.3%) developed new onset OSA postoperatively. Large mandibular setback movements significantly reduced the pharyngeal airway space in the setting of bimaxillary surgery (P=0.006).