Anterior Cruciate Ligament Force and Strain in Males and Females during Anticipated and Unanticipated Side-Stepping

Abstract

Females have a greater number of Anterior Cruciate Ligament (ACL) injuries per activity hours than males. The cause of this injury rate is speculated to be an increased strain on the ACL in performing a side-stepping manoeuvre. The purpose of this study was to determine the magnitude of ACL force and strain and the knee angle at initial foot contact during anticipated and unanticipated side-stepping. 12 male and 12 female, young, healthy, college-age, athletes were recruited for this study. 3D kinematics and kinetics were collected in each of anticipated and unanticipated conditions. A computational musculo-skeletal model was used to estimate the ACL force and strain. No differences were found between males and females in any of the ACL or knee angle parameters (P>0.05). However, there was a significant difference in ACL force and strain between anticipated and unanticipated side-stepping conditions with unanticipated force and strain greater than in the anticipated condition (P<0.05). These results support previous evidence that athletes may be at greater risk of injury during sidestepping tasks where planning time is reduced due to greater elongation of the ACL. Future research should focus upon investigating tasks to mitigate the high-risk strategies athletes use during unanticipated sports tasks.