A multisport epidemiologic comparison of anterior cruciate ligament injuries in high school athletics

Abstract

Background: The knee joint is the second most commonly injured body site after the ankle and the leading cause of sport-related surgeries. Knee injuries, especially of the anterior cruciate ligament (ACL), are among the most economically costly sport injuries, frequently requiring expensive surgery and rehabilitation.

Objective: To investigate the epidemiology of ACL injuries among high school athletes by sport and sex.

Design: Descriptive epidemiology study.

Main outcome measure(s): Using an Internet-based data-collection tool, Reporting Information Online (RIO), certified athletic trainers from 100 nationally representative US high schools reported athlete-exposure and injury data for athletes from 9 sports during the 2007/08-2011/12 academic years. The outcome of interest in this study was ACL injuries.

Results: During the study period, 617 ACL injuries were reported during 9 452 180 athlete exposures (AEs), for an injury rate of 6.5 per 100 000 AEs. Nationally, in the 9 sports studied, an estimated 215 628 ACL injuries occurred during the study period. The injury rate was higher in competition (17.6) than practice (2.4; rate ratio [RR] = 7.3, 95% confidence interval [CI] = 6.08, 8.68). Girls' soccer had the highest injury rate (12.2) followed by boys' football (11.1), with boys' basketball (2.3) and boys' baseball (0.7) having the lowest rates. In sex-comparable sports, girls had a higher rate (8.9) than boys (2.6; RR = 3.4, 95% CI = 2.64, 4.47). Overall, 76.6% of ACL injuries resulted in surgery. The most common mechanisms of injury were player-to-player contact (42.8%) and no contact (37.9%).

Conclusions: Anterior cruciate ligament injury rates vary by sport, sex, and type of exposure. Recognizing such differences is important when evaluating the effectiveness of evidence-based, targeted prevention efforts.

Figure 1.

Anterior cruciate ligament injuries as a proportion of all injuries and all knee injuries, High School Sports-Related Injury Surveillance Study, United States, 2007/2008–2011/2012.

Figure 2.

Outcome of anterior cruciate ligament injury in terms of time loss by sport, High School Sports-Related Injury Surveillance Study, United States, 2007/2008–2011/2012. ^a Other category consists of season ended before athlete returned to play, athlete chose not to continue, and athlete released from team for nonmedical reason.

Figure 3.

Proportion of anterior cruciate ligament injuries resulting in surgery by sport, High School Sports-Related Injury Surveillance Study, United States, 2007/2008–2011/2012.