Knee ligament reconstruction is performed to repair damaged ligaments that have become unstable. One of the most common ligaments to be injured is the anterior cruciate ligament (ACL), which is located at the front of the knee as it is easily stretched or torn. The posterior cruciate ligament, which is located at the back of the knee, is also prone to injury during sports or direct impact in an accident. These injuries can be repaired with a surgical procedure, in which the torn ligament is replaced with a piece of healthy tissue taken from another part of the leg such as the knee cap or hamstring. The healthy tissue is grafted into position and helps to hold the knee joint in place.