As the knee rotates inward, additional strain is placed on the ACL, since the femur and tibia, which are the two bones that articulate together forming the knee joint, move in opposite directions, causing the ACL to tear. Most ACL tears are a result of a non-contact mechanism such as a sudden change in a direction causing the knee to rotate inward. Main article: Anterior cruciate ligament injuryĪn ACL tear is one of the most common knee injuries, with over 100,000 tears occurring annually in the US. For athletes who participate in sports involving cutting, jumping, and rapid deceleration, the knee must be stable in terminal extension, which is the screw-home mechanism. A key factor in instability after ACL injuries is having altered neuromuscular function secondary to diminished somatosensory information. The ACL has mechanoreceptors that detect changes in direction of movement, position of the knee joint, and changes in acceleration, speed, and tension. This function prevents anterior tibial subluxation of the lateral and medial tibiofemoral joints, which is important for the pivot-shift phenomenon. The purpose of the ACL is to resist the motions of anterior tibial translation and internal tibial rotation this is important to have rotational stability. The ACL attaches in front of the intercondyloid eminence of the tibia, where it blends with the anterior horn of the medial meniscus. The tibial plateau is a critical weight-bearing region on the upper extremity of the tibia. The two bundles of the ACL are the anteromedial and the posterolateral, named according to where the bundles insert into the tibial plateau.
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Its proximal fibers fan out along the medial wall of the lateral femoral condyle. The ACL originates from deep within the notch of the distal femur. ( January 2019) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources.