The information that follows includes the details of anterior cruciate ligament (ACL) anatomy and the pathophysiology of an ACL tear, treatment options for ACL injuries along with a description of ACL surgical techniques and rehabilitation, potential complications, and outcomes. The information is intended to assist the patient in making the best-informed decision possible regarding the management of ACL injury. Anatomy Normal knee anatomy. The bone structure of the knee joint is formed by the femur, the tibia, and the patella. The ACL is one of the four main ligaments within the knee that connect the femur to the tibia. The knee is essentially a hinged joint that is held together by the medial collateral (MCL), lateral collateral (LCL), anterior cruciate (ACL) and posterior cruciate (PCL) ligaments. The ACL runs diagonally in the middle of the knee, preventing the tibia from sliding out in front of the femur, as well as providing rotational stability to the knee. The weight-bearing surface of the knee is covered by a layer of articular cartilage. On either side of the joint, between the cartilage surfaces of the femur and tibia, are the medial meniscus and lateral meniscus. The menisci act as shock absorbers and work with the cartilage to reduce the stresses between the tibia and the femur.