Primary prevention of anterior cruciate ligament injuries among collegiate women's soccer players

Abstract

Participation in soccer among female athletes has increased exponentially over the last three decades, and anterior cruciate ligament (ACL) injury rates have also increased at an alarming rate. Many of these ACL injuries occur without contact from another player and may be preventable. Non-contact ACL injuries may be the result of aberrant biomechanics and poor neuromuscular control of the trunk and lower extremities. Exercise-based injury prevention programs (IPPs) that emphasize neuromuscular control were created to mitigate risk. Participation in an IPP can significantly reduce the rate of non-contact ACL injuries, particularly in women. We do not know, however, how these IPPs reduce ACL injuries. In addition, although there is a preponderance of evidence that IPPs are effective in reducing ACL injuries, there has been low implementation of them among athletes and coaches. ☐ The goals of this dissertation were to describe the trunk mechanics that may contribute to ACL injury risk, to assess whether biomechanical risk factors during soccer-specific tasks can predict ACL injury, to measure whether the soccer-specific IPP the [FIFA] 11+ reduces ACL injury risk factors, and to identify barriers to implementation of IPPs. In the first aim of this dissertation we identified that healthy collegiate women’s soccer players typically demonstrate small amounts of trunk lateral flexion while cutting and decelerating, and that trunk center of mass typically moves laterally during a pre-planned cutting task. In the second aim, we assessed whether lower extremity biomechanical measures differentiate between players who go on to ACL injury and those who do not. Hip adduction angle was identified as a differentiating factor during the soccer specific tasks of decelerating and cutting. In the third aim of this dissertation we also evaluated whether these lower extremity biomechanical risk factors can be altered with participation in the 11+, a soccer-specific IPP. Players participating in the 11+ for a single soccer season demonstrated a statistically significant decrease in hip adduction angle, and a decrease in composite knee valgus collapse that exceeded the smallest detectable change. These changes suggest participation in the 11+ can have beneficial effects on biomechanics. Finally, the fourth aim of this dissertation determined that “cost” was the primary barrier to implementing an IPP among soccer coaches who do not currently use one. Additionally, the results from this aim suggested that utilizing a team-based approach may support long-term implementation. Ultimately, this dissertation research improves our understanding of biomechanical risk factors for ACL injury among collegiate women’s soccer players, how the 11+ effects biomechanical risk factors, and what barriers limit implementation of existing IPPs.