The anterior cruciate ligament (ACL) is inside of the knee joint capsule. The ligament connects the femur (thigh bone) to the tibia (shin bone). It is responsible for stabilizing the knee joint articulation. ACL tears are either partial or more commonly, complete tears. The surgeon will use a graft from a donated cadaver (allograft) or from the patient (autograft). The ACL would be replaced from hamstring, patellar or quadriceps tendon grafts. This is typically done as an arthroscopic surgery that requires a small incision and arthroscope (camera) to minimize muscle loss and damage. In some cases, open surgery may be necessary. The surgeon will determine the appropriate treatment after considering a patient’s age, injury severity, activity levels and overall knee stability.