ACL tears are not usually repaired using suture to sew them back together, because repaired ACLs have generally been shown to fail over time. Therefore, the torn ACL is generally replaced by 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
Patients treated with surgical reconstruction of the ACL have long-term success rates of 82 percent to 95 percent. Recurrent instability and graft failure are seen in approximately 8 percent of patients.
The goal of the ACL reconstruction surgery is to prevent instability and restore the function of the torn ligament, creating a stable knee. This allows the patient to return to sports. There are certain factors thatthe patient must consider when deciding for or against ACL surgery.
After the graft has been prepared to the correct size for the patient, the surgeon places an arthroscope into the joint. 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 the most common ACL reconstruction treatment technique, bone tunnels are drilled 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 as 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.
Variations on this surgical technique 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).
Before the surgery is complete, the surgeon will probe the graft to make sure it has good tension, verify that the knee has full range of motion, and perform tests such as the 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.
Physical therapy is a crucial part of successful ACL surgery, with exercises beginning immediately after the surgery. Much of the success and recovery time for ACL reconstruction depends on the patient’s dedication to rigorous physical therapy. With new surgical techniques and stronger graft fixation, current physical therapy uses an accelerated course of rehabilitation.
The goals for rehabilitation of ACL reconstruction include reducing knee swelling, maintaining mobility of the kneecap to prevent anterior knee pain problems, and regaining full range of motion of the knee, as well as strengthening the quadriceps and hamstring muscles.
The patient may return to sports when there is no longer 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.
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. The use of a functional brace when returning to sports is ideally not needed after a successful ACL reconstruction, but some patients may feel a greater sense of security by wearing one.