Background Lateral ligament complex (LLC) ankle sprains are among the most common injuries in United States (US) college athletes. But, there is limited information about the specific epidemiology of such injuries.

Methods De-identified data from the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP) was analysed for 25 sports from the 2009/10–2014/15 academic years. Analyses were limited to injuries diagnosed as LLC sprains. Descriptive statistics include frequencies, rates per 10,000 athlete-exposures (AE), and rate ratios (RR) with 95% confidence intervals (CI).

Results LLC sprain was the most common injury diagnosis in 25 NCAA sports, with 2,429 reported in the sample from the study period. This results in a LLC sprain rate of 4.95/10,000 AEs and a national annual estimate of 16,022 LLC sprains in NCAA athletes. The sports with the highest LLC sprain rates were men’s/women’s basketball (11.96 and 9.50/10,000 AE, respectively), and men’s/women’s soccer (7.43 and 8.36/10,000 AE, respectively). Football had the largest national estimate in NCAA athletes (3,606 per year), despite having a moderate LLC sprain rate (6.87/10,000 AE). Most LLC sprains occurred during practices (57.3%); however, the LLC sprain rate was higher in competition than in practice (RR = 3.29; 95% CI: 3.03–3.56). Overall, 44.3% of LLC sprains required participation restriction time under 24 hours; 33.7%, 1–6 days; 15.7%, 7–21 days; and 3.6%, over 21 days. In total, 11.9% of LLC sprains were recurrent. The sports with the largest proportion of recurrent LLC sprains were women’s basketball and women’s outdoor track and field (both 21.1%). The most common injury mechanisms for LLC sprains were player contact (41.4%), and non-contact (27.4%).

Conclusions LLC sprains are the most common injury in US college athletes. Nearly 20% require at least 7 days of participation restriction time. Future research and interventions should address men’s/women’s soccer and basketball.