Anterior cruciate ligament (ACL) disruption is a common injury that is detrimental to an athlete's quality of life. Determining the mechanisms that cause ACL injury is important in order to develop proper interventions. A failure locus defined as various combinations of loadings and movements, internal/external rotation of femur and valgus and varus moments at a 25(o) knee flexion angle leading to ACL failure was obtained. The results indicated that varus and valgus movements were more dominant to the ACL injury than femoral rotation. Also, Von Mises stress in the lateral tibial cartilage during the valgus ACL injury mechanism was 83% greater than that of the medial cartilage during the varus mechanism of ACL injury. The results of this study could be used to develop training programmes focused on the avoidance of the described combination of movements which may lead to ACL injury.

Anterior cruciate ligament (ACL) disruption is a common injury that is detrimental to an athlete’s quality of life. Determining the mechanisms that cause ACL injury is important in order to develop proper interventions. This study was conducted to provide insight into the specific knee orientations associated with ACL injuries. A failure locus for the ACL was developed by simulating multiple loading scenarios using a 3-D finite element analysis (FEA) model of the knee. The results indicated varus and valgus were more dominant to the ACL injury compared to femoral rotation. The order of MCL failure, ACL failure, and maximum meniscus stress was also determined with respect to time during loading. The results of this study could be used to develop training programs focused on the avoidance of the described combination of movements, which may lead to ACL injury.

A full or partial tear of the anterior cruciate ligament (ACL) is a common and painful injury that has been estimated to occur approximately 250,000 times annually in the U.S. [1]. Articular cartilage and meniscal injuries are also associated with ACL injuries [2]. ACL injuries can often lead to degenerative osteoarthritis of the articular cartilage [2]. An epidemiology study of athletic injuries by Majewski et al. [3] determined that out of 19,530 sports injuries, 20% were ACL injuries and 8% were medial collateral ligament (MCL) injuries.