Gender-Based Differences in Cervical Angle Alignment in the Supine Position: An Analytical Study Using a 3D Motion Capture System

Abstract

Purpose: This study aimed to quantify gender-based variations in cervical spine alignment in the supine position and identify morphological factors influencing cervical curvature using three-dimensional (3D) motion capture. Given the supine posture’s relevance to sleep ergonomics, clarifying whether cervical curvature differs by gender can inform ergonomic pillow design and cervical health interventions.

Methods: Fifty-four healthy adults (28 males, 26 females; mean age 21.1 ± 1.25 years) participated. Reflective markers were attached to the spinous processes of C1, C4, and C7, and vertical displacement (Z-axis) was recorded for one minute using a Qualisys Oqus 300 system at 100 Hz. Cervical angles were derived from coordinate trajectories, and statistical analyses included paired and independent t-tests (α = 0.05).

Results: Cervical angles did not differ significantly between males (175.54 ± 2.16°) and females (175.79 ± 2.34°) (p > 0.05). No gender-based differences were found in C1_Z, C4_Z, or C7_Z displacement.

Conclusions: Gender does not significantly influence cervical curvature in the supine position, yet morphological factors—particularly body height and weight—affect segmental alignment. The mean cervical angle (175.66°) serves as a normative reference for supine posture and may guide personalized pillow design and posture-based sleep interventions.