Epidemiological characteristics of lateral ankle sprains in male collegiate rugby union players with and without injury history

Lateral ankle sprains (LAS) account for a substantial proportion of ankle injuries in rugby union and are associated with a high recurrence rate. A history of LAS is known to increase future injury risk, yet few studies have quantitatively examined this relationship. This study aimed to investigate the epidemiological characteristics of LAS among male collegiate rugby players based on the presence or absence of prior injury history. A total of 146 players were prospectively followed over seven seasons and divided into two groups according to their LAS history. Group-specific exposure time was used to calculate injury incidence, severity, and mechanism-specific burden. A total of 131 LAS cases were recorded. The History group showed a significantly higher incidence rate (1.22/1,000 player-hours) than the No History group (0.72/1,000 player-hours), while no significant difference in severity was observed. Contact-related mechanisms, including other player collisions and lineout landings, were more frequent and burdensome in the History group. These findings suggest that injury history is not merely a contextual factor, but a key determinant of future injury risk and characteristics. Prevention and rehabilitation strategies should be tailored accordingly. Mechanism-specific training and history-informed return-to-play protocols are essential to reduce the burden of LAS in athletes with prior injuries.