Anterior cruciate ligament (ACL) reconstruction is a common procedure performed by orthopedic surgeons, particularly in association with sports-related injuries. Traditional methods such as suturing and sewing may not be used, because repaired ACLs have generally been shown to fail over time. With the advances in orthopedic surgery, it is possible to have an anatomic and individualized ACL reconstruction that closely reproduces the native ACL characteristics and offers improved patient outcomes. In an ACL reconstruction, the torn ligament is surgically removed and replaced with a substitute graft made of tendon.
The grafts commonly used to replace the ACL include:
- Patellar tendon autograft (autograft comes from the patient)
- Hamstring tendon autograft
- Quadriceps tendon autograft
- Allograft (taken from a cadaver) patellar tendon, Achilles tendon, semitendinosus, gracilis, or posterior tibialis tendon
Evidence from clinical research indicates that the long-term success rate of surgical reconstruction of the ACL is 95% and only a small percentage of patients experience recurrent instability and graft failure.
The major goals of ACL surgery are to restore normal joint anatomy, provide static and dynamic knee stability, restore the function of the torn ligament, prevent instability, and allow the patient to return to work and/or sports as soon as possible. It is very important that the patient takes an active part in the rehabilitation, both before and after the ACL surgery.
Following the preparation of a suitable graft, small (one-centimeter) incisions called portals are made in the front of the knee, to insert the arthroscope and instruments, and the surgeon examines the condition of the knee. Meniscus and cartilage injuries are trimmed or repaired, and the torn ACL stump is then removed.
In most cases, ACL reconstruction surgery involves drilling bone tunnels into the tibia and the femur to place the ACL graft in almost the same position as the torn ACL. A long needle is then passed through the tunnel of the tibia, up through the femoral tunnel, and then out through the skin of the thigh. The sutures of the graft are placed through the eye of the needle and the graft is pulled into position up through the tibial tunnel and then up into the femoral tunnel. The graft is held under tension while it is fixed in place using interference screws, spiked washers, posts or staples. The devices used to hold the graft in place are generally not removed. Among variations in ACL reconstruction surgical procedure include the “two-incision,” “over-the-top” and “double-bundle” types of ACL reconstructions, which may be used because of the preference of the surgeon or special circumstances (revision ACL reconstruction, open growth plates).
Prior to the completion of the surgical procedure, it is important to probe the graft to make sure it has good tension, verify that the knee has full range of motion, and perform tests (Lachman’s test) to assess graft stability. The skin is closed and dressings (and perhaps a postoperative brace and cold therapy device, depending on surgeon preference) are applied. The patient will usually go home on the same day of the surgery.
Much of the success and recovery time for ACL reconstruction depends on the patient’s dedication to rigorous physical therapy. Rehabilitation is a vital part of ACL recovery and is essential to getting back to regular physical activity. The goals for rehabilitation are to reduce knee swelling, diminish pain and inflammation, maintain mobility of the kneecap to prevent anterior knee pain problems, and regain full range of motion of the knee, as well as strengthening the quadriceps and hamstring muscles. The patient’s sense of balance and control of the leg must also be restored through exercises designed to improve neuromuscular control. This usually takes four to six months.
Patients who achieve full active range of motion in extension and flexion within the first four weeks of ACL reconstruction surgery typically have less difficulty later on with anterior knee pain, chronic swelling, abnormal gait mechanics, and secondary complications. The patient may return to sports when there is no longer any pain or swelling, when full knee range of motion has been achieved, and when muscle strength, endurance and functional use of the leg have been fully restored.