Hyoid bone position and upper airway patency: A computational finite element modeling study

Abstract

Background and ObjectivesThe hyoid bones inferior baseline position in obstructive sleep apnea (OSA) has led to surgical hyoid repositioning treatment, yet outcomes vary widely. The influence of baseline hyoid position (phenotype) and surgical hyoid repositioning on upper airway function remains unclear. We aimed to investigate their impact on the upper airway using computational modeling. MethodsA validated finite element model of the rabbit upper airway was advanced and used to simulate changes in baseline hyoid position and surgical hyoid repositioning, alone and in combination. The hyoid was displaced in cranial, caudal, anterior, anterior-cranial and anterior-caudal directions from 1-4mm. Model outcomes included upper airway collapsibility, measured using closing pressure (Pclose), cross-sectional area (CSA) and soft tissue mechanics (stress and strain). ResultsGraded baseline hyoid position increments increased Pclose for all directions, and up to 29-43% at 4mm (relative to the original baseline hyoid position). Anterior-based surgical hyoid repositioning decreased Pclose ([~]-115% at 4mm) and increased {Delta}CSA ([~]+35% at 4mm). Cranial surgical hyoid repositioning decreased {Delta}Pclose (-29%), minimally affecting CSA. Caudal surgical hyoid repositioning increased {Delta}Pclose (+27%) and decreased {Delta}CSA (-7%). Anterior-cranial and anterior-caudal surgical hyoid repositioning produced the highest stresses and strains. Surgical hyoid repositioning effects on upper airway outcomes were dependent on baseline hyoid position, with more caudal baseline hyoid positions leading to less effective surgeries. ConclusionsBaseline hyoid position (phenotype) and surgical hyoid repositioning both alter upper airway outcomes, with effects dependent on hyoid displacement direction and magnitude. Baseline hyoid position influences the effectiveness of surgical hyoid repositioning in reducing upper airway collapsibility. These findings provide further insights into the hyoids role in upper airway patency and suggest that considering the hyoids baseline position and surgical repositioning direction/increment may help improve hyoid surgeries for OSA treatment.