Characterization of Secondary Health Conditions Among United States Service Members with Combat-Related Lower Extremity Limb Salvage

<b>Background:</b> Musculoskeletal trauma involving the lower extremities is an unfortunately prevalent injury pattern in contemporary warfare, and the secondary health conditions (SHCs) associated with these injuries remain largely unexplored. <b>Methods:</b> U.S. Service members (SMs) with combat-related lower extremity injuries between 2004 and 2014 were categorized into primary amputation (PA), limb salvage (LS), and non-threatened limb trauma (NTLT) cohorts. The LS cohort was further divided into those with secondary amputation (LS-SA) and those without (LS-NA). The prevalence and incidence of 12 SHCs were analyzed across cohorts to test the hypotheses that (1) the prevalence of deleterious SHCs would differ among SMs with PA, LS, or NTLT, and (2) LS-SA would exhibit a greater prevalence of SHCs compared to LS-NA. <b>Results:</b> The prevalence of SHCs varied significantly across cohorts. Mental health disorders, nonspecific pain, and movement abnormalities were more prevalent in the PA cohort, while osteoarthritis, internal derangement of the knee, joint pain, and late-effect musculoskeletal injury were more prevalent in the LS cohort, specifically in the LS-SA subpopulation. The LS cohort had a higher prevalence of several SHCs than the NTLT cohort. Osteoarthritis incidence increased over time in all cohorts except NTLT, while unspecified back disorders decreased. Notable incidence differences were observed for late-effect musculoskeletal injury and other soft tissue disorders. <b>Conclusions:</b> This study characterizes SHCs associated with combat-related extremity trauma, emphasizing the need for tailored interventions and follow-up care based on specific injury management. Future research should explore underlying mechanisms and evaluate targeted interventions to minimize SHCs' impact on patient outcomes.