Defending Puts the Anterior Cruciate Ligament at Risk During Soccer

BACKGROUND Soccer athletes are at risk for anterior cruciate ligament (ACL) injury. To date, there are limited studies on the mechanisms of ACL injuries in soccer athletes and no video-based analysis or sex-based comparison of these mechanisms. HYPOTHESIS There is no difference in ACL injury mechanisms among soccer athletes by sex. STUDY DESIGN Case series. LEVEL OF EVIDENCE Level 4. METHODS Fifty-five videos of ACL injuries in 32 male and 23 female soccer players were reviewed. Most athletes were professionals (22 males, 4 females) or collegiate players (8 males, 14 females). Visual analysis of each case was performed to describe the injury mechanisms in detail (game situation, player behavior, and lower extremity alignment). RESULTS The majority of ACL injuries occurred when the opposing team had the ball and the injured athlete was defending (73%). Females were more likely to be defending when they injured their ACLs (87% vs 63% for males, P = 0.045). The most common playing action was tackling (51%), followed by cutting (15%). Most injuries occurred due to a contact mechanism (56%) with no significant difference for sex. Females were more likely to suffer a noncontact injury in their left knee (54%) than males (33%) (P = 0.05). CONCLUSION Soccer players are at greatest risk for ACL injury when defending, especially when tackling the opponent in an attempt to win possession of the ball. Females are more likely to injure their ACLs when defending and are at greater risk for noncontact injuries in their left lower extremity. CLINICAL RELEVANCE Soccer ACL injury prevention programs should include proper defending and tackling techniques, particularly for female athletes.