Patterning of Musculoskeletal Injuries in the U.S. Army: A Sociocentric Social Network Analysis.

Background: Musculoskeletal injuries (MSKIs) are the most prevalent and costly threat to U.S. soldier health and medical readiness. Although sociodemographic and physical factors contributing to MSKIs have been well studied, the role of social relationships-particularly social disconnection-remains underexplored, despite mounting evidence of its negative impact on health outcomes.

Methods: Cross-sectional sociocentric social network analysis was applied to 2 Army combat arms units (N = 776; Cohort 1 [C1] N = 394, Cohort 2 [C2] N = 382). Social interaction networks were measured by asking soldiers to identify others within their unit with whom they socialized outside of duty hours. Descriptive analyses followed by multiple logistic regression with quadratic assignment procedure assessed dyadic similarity in injury status accounting for network dependencies, sociodemographic variables, and known risk factors for MSKIs.

Results: Participants, representative of combat arms units, were predominately young, male, White, and single and had a mean time in service of 5 to 6 years (C1: 5.6 ± 4.4 years, C2: 5.9 ± 4.7 years). Over 25% reported duty-limiting profiles for MSKIs (C1: 26.1%, C2: 27.7%). Injured soldiers were significantly more likely to identify other injured soldiers as those with whom they socialized outside of duty hours (C1 OR= 1.255, P = .040; C2 OR = 1.336, P = .008). High modularity scores (C1: 0.767, C2: 0.788) indicated distinct, cohesive subgroups. Injured soldiers also endorsed having 0.76 to 1.5 fewer social ties compared to uninjured soldiers (P = .025 [C1], P = .003 [C2]).

Conclusions: Injured soldiers were distributed non-randomly within military units, forming distinct subgroups and reporting significantly fewer social ties compared to uninjured soldiers. Future studies should explore whether social disconnection increases susceptibility to MSKIs through social selection or influence, whether MSKIs reduce social connection and integration, or if both dynamics interact.