577 FO29 – In-lab ACL injury risk screening lacks ecological validity, let’s go to the football field!

Background Establishing anterior cruciate ligament (ACL) injury risk during cutting movements has traditionally been performed in relatively standardized laboratory environments. This current paradigm inherently assumes that cutting biomechanics is independent of a sport-specific context. However, measuring movement in an ecological valid environment may potentially reshape the current definition of high-risk biomechanics based on real environment data instead of laboratory data only. Objective The aim of the present study was to investigate if the presence of ACL injury risk factors depicted in the laboratory would reflect at-risk patterns on the football field. Design Players performed unanticipated cutting maneuvers in a laboratory setting and on the football field during football-specific exercises (F-EX) and games (F-GAME). Setting Youth sports Participants Twenty-four talented female football players (14.9±0.9 years old) Assessment of Risk Factors Knee kinetics were collected in the laboratory and grouped using hierarchical agglomerative clustering. The clusters were used to investigate the kinematics collected on field through wearable sensors. Main Outcome Measurements Hip, knee and trunk kinematics (laboratory and field) and kinetics (laboratory). Results Three clusters emerged: Cluster 1 presented the lowest knee moments; Cluster 2 presented high knee extension but low knee abduction and rotation moments; Cluster 3 presented the highest knee abduction, extension, and external rotation moments. In F-EX, greater knee abduction angles were found in Cluster 2 and 3 compared to Cluster 1 (p=0.007). In F-GAME Cluster 3 showed the lowest knee flexion angles (pConclusions Context matters. Clinically relevant differences towards ACL injury identified in the laboratory partially disappeared on the field. Players who showed relatively high knee abduction in the laboratory, which is considered as risky, showed less knee abduction on the field. In-lab injury risk screening may lack ecological validity.