Forward head posture and deep cervical flexor muscle morphology in obstructive sleep Apnea: a cross-sectional ultrasonographic analysis.

PURPOSE: This study aimed to evaluate postural and musculoskeletal features—including forward head posture (FHP), deep cervical flexor muscle endurance (DCF), and thickness—in patients with obstructive sleep apnea (OSA), and to explore their relationship with disease severity. The findings are expected to enhance understanding of postural biomechanics in OSA and support posture-based preventive and therapeutic approaches.

METHODS

This cross-sectional study (Jan–June 2025) included participants aged 18–80 who underwent polysomnography and were grouped by AHI (apnea-hypopnea index) into OSA or controls., Lateral photogrammetric analysis was employed to evaluate FHP via measurement of the craniovertebral angle (CVA), DCF muscle endurance, and morphology (Cross-sectional area (CSA) at C5 via ultrasonography) were assessed. Group comparisons and correlations with OSA severity and phenotypes were analyzed.

RESULTS

Of 85 participants (OSA: 67, controls: 18), the OSA group had higher body mass index (BMI) and neck circumference, but lower CVA, craniovertebral angle in rotation (CSAR), and craniovertebral angle in the lateral view (CSAL) (p < 0.05). DCF endurance did not differ significantly. Severe OSA cases had lower CSAR and CSAL. OSA severity showed inverse correlations with all posture angles and DCF thickness. No differences were found between OSA subtypes.

CONCLUSION

Our findings revealed an inverse relationship between OSA severity and both the CSA of deep cervical flexors and CVA measurements, suggesting that OSA involves systemic musculoskeletal components, particularly within the cervical myofascial system. These results highlight the need for a multidisciplinary approach in OSA evaluation and management. Further longitudinal and interventional studies are needed to clarify the role of cervical muscle structure and posture in key clinical outcomes such as AHI, oxygen desaturation, and symptom burden.