Epidemiology of knee internal derangement injuries in United States high school girls' lacrosse, 2008/09-2016/17 academic years.

Research on knee internal derangement (KID) injuries in high school girls' lacrosse is limited, yet needed to identify sport-specific risk factors. This study describes the epidemiology of KID injuries in United States high school girls' lacrosse during the 2008/09-2016/17 academic years. Athletic trainers (ATs) reported injury and athlete-exposure (AE) data to the High School Reporting Information Online (RIO) surveillance system. KID injuries involved the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), and menisci. Injury rates per 10,000AE and injury rate ratios (IRR) with 95% confidence intervals (CI) were reported. Linear regression assessed injury rate time trends. ATs reported 148 KID injuries (rate = 1.92/10,000AE). The injury rate was higher in competition than practice (IRR = 8.40; 95%CI: 5.66-12.49). ACLs comprised a large proportion of KID injuries (46.6%). The ACL injury rate increased over time (P = 0.002), highlighting the need to develop/refine lacrosse-specific KID injury prevention programs.