Scapular Kinematics by Sex Across Elevation Planes.

Area of Science:

• Biomechanics
• Orthopedics
• Human Movement Science

Background:

• Scapular kinematics are key indicators of shoulder dysfunction and dyskinesis.
• The influence of sex on healthy scapular kinematics remains largely unexplored.
• Understanding sex-based differences is vital for diagnosing and treating shoulder pathologies.

Purpose of the Study:

• To investigate and compare scapular kinematics between healthy males and females during arm elevation.
• To identify potential sex-specific differences in scapular motion patterns.
• To establish a baseline for sex-specific scapular movement in uninjured individuals.

Main Methods:

• Surface-mounted reflective markers tracked scapular positions during arm elevation in multiple planes (0°-120°).
• Calculated scapulothoracic rotations included protraction/retraction, medial/lateral rotation, and posterior/anterior tilt.
• Analysis of Variance (ANOVA) assessed effects of sex, plane, phase, and elevation angle on kinematics.

Main Results:

• Males and females exhibited similar protraction/retraction and medial/lateral rotation.
• Significant sex differences were observed in posterior/anterior tilt, particularly at higher elevation angles (up to 8.5°).
• Elevation, plane, and phase were significant main effects for all rotations; sex was not a main effect but showed significant interactions with other factors.

Conclusions:

• Sex-specific differences in scapular kinematics, especially posterior tilt, may contribute to the higher incidence of shoulder pathology in females.
• Scapular kinematics are influenced by sex, arm elevation, movement plane, and phase (concentric/eccentric).
• These findings provide essential sex-specific benchmarks for evaluating shoulder pathologies and informing clinical assessments.