Sex-Specific Associations Between Craniocervical Posture and Obstructive Sleep Apnoea Severity

Introduction and aims Obstructive sleep apnoea (OSA) is a prevalent sleep disorder associated with significant systemic complications. While lateral cephalograms are effective for evaluating craniocervical posture and OSA risk, the correlation between specific craniocervical postural parameters and OSA severity remains unexplored. This study aimed to analyse this correlation using polysomnography and cephalometric analysis, with a focus on sex-dependent differences. Methods We retrospectively evaluated 154 adults diagnosed with OSA (97 males, 57 females; median age 28.00 years [interquartile range (IQR), 24.00–34.00 years] and 30 non-OSA controls. All participants underwent clinical examination, overnight polysomnography, and standardized lateral cephalometric imaging. Twenty-one craniocervical cephalometric parameters were measured and analysed for their correlation with OSA severity indicators, with all analyses stratified by sex. Results In the overall OSA sample, higher apnoea-hypopnoea index (AHI) was associated with greater craniocervical inclination. Lower LSaO₂ was associated with several craniocervical postural variables, such as SN-OPT and RL-OPT. After sex stratification, no craniocervical postural parameter was associated with AHI in males, whereas in females SN-VER and FH-VER were significantly associated with both higher AHI and lower LSaO₂. Conclusion Several craniocervical cephalometric parameters showed associations with OSA severity, with notable sex-specific patterns. In the overall OSA sample, RL-OPT and RL-CVT were positively correlated with AHI, suggesting that a more inclined mandibular ramus relative to the cervical spine may be linked to greater OSA risk. Among females, greater inclinations of the SN and FH lines relative to the true vertical line were associated with both higher AHI and lower LSaO₂. No such correlations reached statistical significance in males. These findings indicate that craniocervical posture on lateral cephalograms may serve as a sex-dependent indicator of OSA severity.