Foot strike angle as key predictor of multi-plane knee joint moments in sidestep cutting: implications for ACL injury prevention.

Video analyses of ACL injury situations in change-of-direction tasks suggest an elevated injury risk during flatfooted or rearfoot landing. While loading in each individual plane of the knee can contribute to injury, combined loading seems to be the most likely mechanism. This study investigated if knee joint moments are related to the foot strike angle in pre-planned and unplanned handball-specific sidestep cuts performed by n = 51 female handball players. Canonical correlation analysis (CCA) with the foot strike angle at initial ground contact serving as the predictor variable was performed on the knee joint moment vector field (Mxyz). In both conditions, the foot strike angle was related to Mxyz. Subsequently, post-hoc tests were conducted using CCA for moment couples (Mxy, Mxz, Myz) and linear regression for individual moment components. Results revealed that traditional analyses focusing on individual planes only partially explain the observed relationships, particularly during the unplanned cutting condition. Given the time periods in which correlations exist, this study shows that manipulating the foot strike angle has the potential to reduce multi-plane knee loading associated with ACL injury, while limiting analyses to individual planes might underestimate the potential to mitigate ACL injury risk.