Knee abduction moment is decreased by gluteus medius force while increased by vertical and lateral ground reaction force

Knee abduction moment (KAM) during drop vertical jump (DVJ) and hip abductor strength predict ACL injury prospectively. The purpose of this study was to determine relationships between these risk factors during a dynamic landing task. Kinematics and kinetics, including muscle forces, during DVJ were calculated using electromyography (EMG)-informed musculoskeletal simulations. A multiple regression analysis showed that KAM was predicted by higher vertical and lateral ground reaction force (GRF) and lower gluteus medius force. Increased gluteus medius activation may decrease KAM by controlling the frontal plane pelvic and hip position during landing.