Anatomy and biomechanics of the anterior cruciate ligament.

The ACL is an important living soft-tissue component of ancient origin that acts in combination with other complex structures to provide control of femorotibial kinematics. The effect on the knee of its loss, resulting in disruptive kinematics and often subsequent degenerative changes, probably occurs not only because of its lack of structural integrity but also perhaps because of disruption of its proprioceptive function. The complexity of this ligament and associated normal kinematics of the knee challenges the ability of orthopaedists to devise effective therapeutic measures to reconstitute its function when lost. A clearer understanding of the normal role of the ACL will aid in this effort.