Which of the following is NOT a function of the ACL?

The function of the anterior cruciate ligament (ACL) is primarily to stabilize the knee by preventing excessive forward movement of the tibia relative to the femur and controlling the knee's rotational stability. While the ACL plays a significant role in stabilizing knee movement and preventing hyperextension, it does not allow for full rotational movement of the knee.

The knee joint itself is a hinge joint that permits some rotation, but this rotation is limited. The ACL helps to restrict excessive rotational movements, which can lead to injury. If the knee were allowed full rotational movement uncontrolled by ligaments like the ACL, it would increase the risk of damage to the cartilage and other ligaments in the knee.

The other options indicate important roles of the ACL: stabilizing knee movement helps maintain alignment during activities, and preventing hyperextension protects the joint from movements beyond its normal range. Additionally, while shock absorption can be influenced by various soft tissues surrounding the knee, it is not a primary function of the ACL, which is mainly focused on stability and control rather than direct shock absorption.