Sex Differences in Shoulder Anatomy and Biomechanics: A Systematic Review and Meta-Analysis

Abstract

BACKGROUND: Studies analyzing sex-related differences in anatomy, biomechanics, and injury patterns have burgeoned in recent years. While the majority of these manuscripts have highlighted differences about the knee, there remains a paucity of descriptions of the sex-related differences about the shoulder. Herein we summarize the sex-related differences of shoulder 1) osteology, 2) soft tissue anatomy, and 3) neuromuscular function. METHODS: A systematic review of literature was performed querying manuscripts from Medline, Web of Science, Embase, and Google Scholar databases according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All articles investigating shoulder differences by sex were included. Metrics of the sex-related differences in osteology, soft-tissue anatomy, and neuromuscular function were recorded. Meta-analysis was performed when metrics were available from 3 or more studies.  RESULTS:  Sixteen articles were included for analysis. There were 7 cadaveric studies, 1 review article, and 8 studies with Level-III or IV evidence. Glenoid height and width were significantly smaller in females (4.57 mm, p<0.001) compared to males (4.60mm, p=0.001), respectively. There was no significant sex-related difference in glenoid retroversion. Females demonstrated significantly less dynanomotor shoulder strength and greater shoulder range of motion than males. There were no significant sex-related differences in shoulder proprioception and the results for shoulder instability were variable. CONCLUSION: Significant interactions of sex were found in both glenoid and humeral osteology, functional shoulder strength, and range of motion (ROM). Further study is warranted to determine proper conceptualization and treatment of shoulder injuries among sexes.