Background: Ankle-foot injuries are common in military personnel and substantially degrade function and force readiness. The purpose of this retrospective cohort study was to assess the incidence and contributing factors of traumatic ankle-foot fractures in the US military.
Methods: A population-based study of all service members in the US military was performed assessing the factors of sex, occupation, service branch, rank, and year on segmental tibia-fibula, rearfoot, and forefoot fracture incidence between 2006 and 2015. The Defense Medical Epidemiology Database was queried for the number of individuals with fractures of the tibia-fibula, rearfoot, and forefoot using International Classification of Diseases, Ninth Revision, Clinical Modification on the initial medical encounter. Unadjusted relative risk (RR) calculations were performed assessing sex and occupation. A negative binomial regression assessed the adjusted factors of sex, branch, rank, and year.
Results: During this study, 95,540 enlisted service members (8.4 per 1,000 person-years) and 13,318 military officers (5.8 per 1,000 person-years) were diagnosed with ankle-foot fractures. In the adjusted analysis, sex was found to only be a significant factor in forefoot fractures (RR, 1.54), with female service members having a significantly higher risk. There were no significant sex-related differences observed in tibia-fibula or rearfoot fractures. US Navy and Air Force personnel had significantly lower risk of tibia-fibula fractures (RR range, 0.76-0.84) compared with the US Army. Forefoot fracture risk was significantly higher in the US Marine Corps (RR, 1.47) compared with the US Army. Officers had consistently lower risk for fractures in each segment (RR range, 0.68-0.77) compared with enlisted personnel. Enlisted engineers, aviation, and artillery/gunnery compared to infantry, and ground/naval gunfire officers had the greatest relative risk compared all other officer fields (RR range, 1.11-3.67).
Conclusions: Sex, occupation, branch, and rank were salient factors for macrotraumatic ankle-foot fractures. These findings can be used to inform and increase precision in medical planning and in the targeted development of preventive interventions.