Study Design Retrospective cohort.

Objectives To examine the incidence rate and describe the type of ankle injuries in intramural and club sports at the United States Military Academy.

Background Ankle injuries are common among athletes and military personnel. However, there is limited epidemiological data for intramural and club sports participation.

Methods and Measures Ten years (academic years 2006–2007 through 2015–2016) of ankle injury data was collected from the Cadet Illness and Injury Tracking System (CIITS) for flag football, team handball, judo, orienteering, rugby, and ultimate Frisbee. The primary outcome of interest was ankle injury incidence rate (IR) with 95% confidence intervals (CI) per 1000 athlete exposures (AEs) across all sports and by individual sport. AEs were defined as one cadet participating in a game or practice. Secondary outcomes included type of ankle injury and time lost (TL).

Results A total of 276 ankle injuries were documented in CIITS during 283,049 AEs, for an IR of 0.98/1000 AEs (95% CI: 0.86–1.10). By sport, the highest to lowest incidence rates were as follows: rugby (IR=2.29; 95% CI: 1.90–2.73), team handball (IR=1.57; 95% CI: 1.11–2.16), judo (IR=1.09; 95% CI: 0.70–1.61), orienteering (IR=0.76; 95% CI: 0.56–1.01), ultimate Frisbee (IR=0.60; 95% CI: 0.42–0.85), and flag football (IR=0.18; 95% CI: 0.09–0.31). Ankle sprains represented 87.1% of all ankle injuries at a rate of 0.84/1,000 AEs (95% CI: 0.73–0.95) with 20.04±34.89 days lost. The highest IR of ankle sprains were in rugby (IR=1.97; 95% CI: 1.61–2.38) and team handball (IR=1.41; 95% CI: 0.97–1.97). Other injuries included ankle strains (5.1%; TL=3.50±8.43 days), inflammation (3.7%; TL=33.60±73.24 days), fractures (1.9%; TL=105.40±50.60 days), contusions (1.5%; TL=6.25±5.80 days), and dislocations (0.4%; TL=163.00±0.00 days).

Conclusion Ankle sprains were the most frequent ankle injury across all six sports with the highest incidence rates in rugby and team handball. Clinical efforts should be targeted toward implementing injury-prevention strategies such as bracing or neuromuscular training.