ACL Reconstruction with Hamstring
The semitendinosus hamstring tendon on the inner side of the knee is used in creating the hamstring tendon autograft for ACL reconstruction. Some surgeons use an additional tendon, the gracilis, which is attached below the knee in the same area. This creates a two- or four-strand tendon graft. Hamstring graft proponents claim there are fewer problems associated with harvesting of the graft compared to the patellar tendon autograft, including:
Less anterior knee pain or kneecap pain after surgery
Less postoperative stiffness problems
The graft function may be limited by the strength and type of fixation in the bone tunnels, as the graft does not have bone plugs. There have been conflicting results in research studies as to whether hamstring grafts are slightly more susceptible to graft elongation (stretching), which may lead to increased laxity during objective testing. Recently, some studies have demonstrated decreased hamstring strength in patients after surgery.
There are some indications that patients who have intrinsic ligamentous laxity and knee hyperextension of 10 degrees or more may have increased risk of postoperative hamstring graft laxity on clinical exam. Therefore, some clinicians recommend the use of patellar tendon autografts in these hypermobile patients.
Additionally, since the medial hamstrings often provide dynamic support against valgus stress and instability, some surgeons feel that chronic or residual medial collateral ligament laxity (grade 2 or more) at the time of ACL reconstruction may be a contra-indication for use of the patient’s own semitendinosus and gracilis tendons as an ACL graft.
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 with hamstring 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 with hamstring 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.