Objective To compare frontal plane knee moments, and kinematics and kinetics associated with knee valgus moments between cutting to 45° and 110°, and to determine the predictive value of kinematics and ground reaction forces (GRFs) on knee valgus moments when cutting to these angles. Also, to determine whether sex differences exist in kinematics and kinetics when cutting to 45° and 110°. Design Cross-sectional study. Setting Laboratory setting. Participants Forty five (20 females) healthy young adult soccer athletes ages 16-23 years. Assessment of Risk Factors Kinematic and kinetic variables were compared between randomly-cued side-step cutting maneuvers to 45° and 110°. Predictors of knee valgus moment were determined for each task. Main Outcome Measures Kinematic variables: knee valgus angle, hip abduction and internal rotation angles. Kinetic variables: vertical, posterior, and lateral GRFs, and knee valgus moment. Results Knee valgus moments were greater when cutting to 110° compared to 45°, and females exhibited greater moments than males. Vertical and lateral GRFs, hip internal rotation angle, and knee valgus angle explained 63% of the variance in knee valgus moment during cutting to 45°. During cutting to 110°, posterior GRF, hip internal rotation angle, and knee valgus angle explained 41% of the variance in knee valgus moment. Conclusion Cutting tasks with larger redirection demands result in greater knee valgus moments. Similar factors including shear GRFs, hip internal rotation and knee valgus position contribute to knee valgus loading during cuts performed to smaller (45°) and larger (110°) angles.

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These relations have important implications for ACL injury prevention programs. Although restricting frontal and transverse plane movement has been emphasized in many programs, these movement recommendations may not be appropriate for cutting tasks performed at greater angles.