Rainfall, evaporation and the risk of non‐contact anterior cruciate ligament injury in the Australian Football League

Abstract

To determine if weather conditions affect the risk of anterior cruciate ligament (ACL) tear in Australian Football. Prospective observational analytic study of football matches. The Australian Football League (AFL), a professional competition. All players in 2280 matches from 1992-1998. Surgically-proven ACL injury, not involving a direct contact mechanism, during a match; rainfall; water evaporation. 59 ACL injuries not involving direct contact occurred during the study period, more commonly in cities north of Melbourne (chi 2 = 17.0; df = 1; P < 0.001). Senior grade matches (relative risk [RR], 3.03; 95% confidence interval [CI], 1.52-6.03), high water evaporation in the month before the match (RR, 2.80; 95% CI, 1.53-5.10) and low rainfall in the year before the match (RR, 1.93; 95% CI, 1.12-3.34) were significantly associated with these injuries. Low water evaporation and high rainfall significantly lower the risk of ACL injuries in AFL footballers. The likely mechanism is a softening of the ground, which lowers shoe-surface traction. Consistent extra watering and covering of grounds during periods of high water evaporation may lower the rate of ACL injuries.