769 FO73 – Anatomical risk factors for primary and secondary non-contact ACL injury – a prospective cohort study in 880 female elite players

Background Anterior cruciate ligament (ACL) injury is one of the most severe injuries for athletes. It is important to identify risk factors, since a better understanding of injury causation can help to inform athletes about risk and increase their understanding and motivation for injury prevention. Objective To investigate the relationship between anatomical factors and risks for future non-contact ACL injuries. Design Prospective cohort study. Setting and Participants 870 female elite handball and football players (age 14–37 years), 86 of which with a history of ACL injury were enrolled in the analysis. All complete ACL injuries among the tested players were recorded prospectively from 2007 to 2015. Assessment of Risk Factors The 18 anatomical risk factors for non-contact ACL injuries were invested, including anthropometrics, alignment, joint laxity and mobility. Main Outcome Measurements Univariate analysis between groups with and without new ACL injury to detect risk factors for non-contact primary and secondary ACL injury. Results 64 new non-contact ACL injuries were registered. Only small or no differences were found between those with and without a new ACL injury among the variables that were measured. However, static knee valgus was significant higher in the new injury group than in no new injury group among all players, and this tendency was clearer players with a previous ACL injury. Players with secondary injury also had higher degree of knee hyperextension compared with previously injured that did not get a secondary injury Conclusion The anatomical factors we investigated had weak or no association with risk for an index non-contact ACL injury risk. Increased static knee valgus was associated with increased risk for non-contact ACL injury, in particular for secondary injury. Furthermore, hyperextension of the knee was also a risk for secondary ACL injury.