(1311) Impact of Maxillomandibular Advancement on Pharyngeal Collapsibility: A Pilot Study

Introduction: Obstructive sleep apnea (OSA) is characterized by recurrent episodes of airflow limitation due to upper airway (UA) collapse during sleep. Surgical procedures to treat OSA have high failure rates. Virtual surgery planning based on computer simulations of UA biomechanics has the potential to improve patient outcomes. This pilot project aims to quantify metrics of UA mechanical stability and correlate them to OSA severity in 6 patients who underwent maxillomandibular advancement (MMA).

Methods: Three-dimensional models of the UA airspace and soft tissues were created from pre and post-surgery computed tomography. Fluid-structure interaction (FSI) simulations of UA collapse were performed to quantify metrics of UA mechanical stability such as airspace cross-sectional areas, airflow resistance, pharyngeal compliance, and maximum flowrate. The apnea-hypopnea index (AHI) was used as a clinical measure of OSA severity.

Results: MMA increased the airspace minimal cross-sectional area (mCSA) of the pharynx from 0.79 ± 0.46 cm2 preintervention to 2.9 ± 1.6 cm2 postintervention (p = 0.02). This increase in mCSA was associated with a reduction in airflow resistance from 211 ± 182 Pa.s/L pre-intervention to 40 ± 13 Pa.s/L post-intervention (p = 0.06) and an increase in the maximum flowrate from 0.93 ± 0.60 L/s pre-intervention to 2.9 ± 1.0 L/s post-intervention (p = 0.003). Several biomechanical variables had a strong correlation with AHI with absolute values of the Spearman correlation coefficient around 0.7.

Conclusions: This pilot study supports the hypothesis that FSI-derived biomechanical variables are predictive of intervention outcomes after MMA. Future studies with larger sample sizes are needed to confirm our findings.