Mechanisms of non-contact ACL injuries.

In soccer one of the most common knee injuries is the anterior cruciate ligament (ACL) tear, which usually occurs through non-contact mechanisms. Female soccer players are at higher risk of sustaining non-contact ACL injuries than male soccer players. A good understanding of ACL loading mechanisms is the basis for a good understanding of the mechanisms of non-contact ACL injuries, which in turn is essential for identifying risk factors and developing prevention strategies. Current literature demonstrates that sagittal plane biomechanical factors, such as small knee flexion angle, great posterior ground reaction force and great quadriceps muscle force, are the major ACL loading mechanisms. A great posterior ground reaction force may be associated with a great quadriceps muscle force, which would cause great anterior draw force at the knee. A small knee flexion is associated with a large patella tendon-tibia shaft angle and ACL elevation angle, which would result in great ACL loading. Current literature also demonstrates that the ACL is not the major structure of bearing knee valgus-varus moment and internal-external rotation loadings. Knee valgus-varus moment and internal-external rotation moment alone are not likely to result in isolated ACL injuries without injuring other knee structures.