Sex and Occupation Are Salient Risk Factors for Lateral Ankle Sprain Among Military Tactical Athletes

ABSTRACT Introduction Lateral ankle sprains (LAS) are ubiquitous among tactical athletes and a substantial burden in the military. With the changes in operational demand and the beginning of integration of women into previously closed occupations, an updated assessment of the burden of ankle sprains in the military is warranted. Methods A population-based epidemiological retrospective cohort study of all service members in the US Armed Forces was performed assessing risk of sex and military occupation on the outcome of LAS incidence. The Defense Medical Epidemiology Database was queried for the number of individuals with ICD-9 diagnosis codes 845.00 (sprain of ankle, unspecified) and 845.02 (calcaneofibular ligament sprain) on their initial encounter from 2006 to 2015. Relative risk (RR) and chi-square statistics were calculated in the assessment of sex and occupational category. Results A total of 272,970 enlisted males (27.9 per 1000 person-years), 56,732 enlisted females(34.5 per 1000 person-years), 24,534 male officers (12.6 per 1000 person-years), and 6020 female officers (16.4 per 1000 person-years) incurred LAS. Enlisted females in all occupational groups were at significantly higher risk for LAS than their male counterparts (RR 1.09–1.68; p < 0.01), except for Engineers ( p = 0.15). Female officers had consistently higher risk for LAS in all occupational groups (RR 1.10–1.42; p < 0.01) compared with male officers, except Ground/Naval Gunfire ( p = 0.23). Contrasted with Infantry, enlisted members in the Special Operations Forces, Mechanized/Armor, Aviation, Maintenance, and Maritime/Naval Specialties were at lower risk (RR, 0.38–0.93; p < 0.01), Artillery, Engineers, and Logistics Specialties were at higher risk (RR 1.04–1.18; p < 0.01), and Administration, Intelligence, and Communications were no different ( p = 0.69). Compared with Ground/Naval Gunfire officers, Aviation officers were at significantly lower risk (RR, 0.75; p < 0.01), and Engineers, Maintenance, Administration, Operations/Intelligence, and Logistics officers were at higher risk (RR, 1.08–1.20; p < 0.01). Conclusion Sex and military occupation were salient factors for LAS risk. Colocation of interdisciplinary neuromusculoskeletal specialists to provide targeted preventive interventions should be considered in practice and policy. Disclaimer The authors are military service members or employees of the U.S. Government. This work was prepared as part of their official duties. Title 17, U.S.C. §105 provides that copyright protection under this title is not available for any work of the U.S. Government. Title 17, U.S.C. §101 defines a U.S. Government work as work prepared by a military service member or employee of the U.S. Government as part of that person’s official duties. The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the U.S. Government. The study protocol was approved by the Naval Health Research Center Institutional Review Board in compliance with all applicable Federal regulations governing the protection of human subjects. Research data were derived from an approved Naval Health Research Center Institutional Review Board protocol, number NHRC.2019.0200-NHSR. Highlights - Female sex and military occupation were salient factors in risk for LAS. - These injuries continue to be pervasive among military service members - Findings likely attribited in part to differences in sex-related musculoskeletal structure and function - Occupational hazard exposure, physical fitness, and health care access and utilization also likely contributory to LAS risk