FIGURE 1.

The anterior cruciate ligament is a band of dense connective tissue that prevents the tibia from sliding out in front of the femur as well as provides rotational stability to the knee. The term “cruciate” refers to the crossing over (from “crus” meaning “cross”) of anterior and posterior ligaments. The posterior cruciate ligament (PCL) courses from a more anterior position in the femoral notch to the posterior aspect of the proximal tibia. The medial and lateral collateral ligaments control the sideways motion of your knee and brace it against unusual movement. The average tensile strength for the ACL is 2160 N. This is slightly less than the strength of the posterior cruciate ligament and approximately half as strong as the medial collateral ligament. Mechanoreceptors in the intact ACL contribute toward the functional stability of the knee joint, and injury leads to disturbance of neuromuscular control from their damage or loss. The patella sits in front of the joint to provide protection (not shown).