Injuries/Violence
Location-specific musculoskeletal injury risk following mild traumatic brain injury among United States service members Alexander Ivan B. Posis* Alexander Ivan B. Posis Amy Silder James M. Zouris Daniel J. Crouch Pinata H. Sessoms Andrew J. MacGregor
Background: Mild traumatic brain injury (mTBI) is associated with greater risk of musculoskeletal injury (MSKI). However, it is unclear if the association of mTBI with risk of subsequent MSKI among a large cohort of United States (US) service members (SMs) with extended follow-up differs by specific MSKI location.
Methods: This retrospective cohort study included 777,811 SMs (mean ± SD age = 20.5 ± 3.4 years; 18.9% female; 53.7% White; mTBI = 2.6%) who joined between 2016-2020 and had medical record data until 2023. mTBIs and incident MSKI events were identified using International Classification of Diseases, 10th Revision, codes. We fit accelerated failure time models with a gamma distribution to estimate time ratios (TRs) and 95% CIs for the association of mTBI with subsequent overall MSKI and location-specific MSKI outcomes. All models were adjusted for demographic and military-relevant characteristics.
Results: During 1,589,903 person-years of follow-up, there were 543,463 MSKI events (342 MSKIs per 1,000 person-years). mTBI was associated with a 52% (TR = 0.48, 95% CI 0.46-0.51) reduction in time to overall MSKI relative to no mTBI. The most common MSKI locations were ankle/foot (22.9%), knee (16.3%), and lumbopelvic-hip (14.1%). mTBI was associated with reduced time to MSKI in all location-specific MSKI models. For example, mTBI was associated with reduced time to MSKI related to lower (TRankle/foot = 0.77, 95% CI 0.70-0.84; TRknee = 0.62, 95% CI 0.56-0.69; TRlumbopelvic-hip = 0.95, 95% CI 0.90-1.00) and upper (TRcervicothoracic = 0.19, 95% CI 0.16-0.21) body regions.
Conclusions: Among US SMs, mTBI was associated with faster time to subsequent MSKI. These associations differed by MSKI location. Findings highlight the importance of focusing on injury locations, such as lower body regions, which may be more prone to MSKI following an mTBI. This information can inform patient counseling on injury risk following mTBI.