The relationship between hip muscular stiffness and the biomechanical factors associated with ACL injury

Anterior cruciate ligament (ACL) injury is prevalent in physically active individuals. Diminished hip neuromuscular control is thought to contribute to ACL injury. The purpose of this study was to explore the relationship between hip muscular stiffness and biomechanical ACL loading mechanisms. Subjects underwent a hip muscular stiffness assessment and a dynamic movement assessment. Individuals with greater hip abductor stiffness displayed lesser peak knee valgus angles and displacement during landing. The combination of hip extensor and abductor stiffness significantly predicted peak knee valgus angle, valgus angle at IGC, and knee valgus displacement. Our findings suggest a link between hip abductor stiffness and knee valgus motion, factors which have ACL injury implications. Because muscular stiffness can be altered, consideration should be given to the inclusion of stiffness training in ACL injury prevention programs. Future research is needed to determine the effects of increased hip muscular stiffness on ACL loading and injury risk