Anterior cruciate ligament (ACL) reconstruction is a surgical procedure that replaces the injured ACL with a tendon graft. Anterior cruciate ligament is one of the four major ligaments of the knee that connects the femur (thigh bone) to the tibia (shin bone) and helps stabilize your knee joint. The anterior cruciate ligament prevents excessive forward movement of the lower leg bone (the tibia) in relation to the thigh bone (the femur) and limits rotational movements of the knee.
A tear of this ligament can make you feel as though your knees will not allow you to move or even hold you up. Anterior cruciate ligament reconstruction is surgery to reconstruct the torn ligament of your knee with a tissue graft.
An ACL injury most commonly occurs during sports that involve twisting or overextending your knee. An ACL can be injured in several ways:
When you injure your ACL, you might hear or feel a loud “pop” sound and you may feel the knee buckle. Within a few hours after an ACL injury, your knee may swell due to bleeding from vessels within the torn ligament. You may notice that the knee feels unstable or seems to give way, especially when trying to change direction on the knee.
An ACL injury can be diagnosed with a thorough physical examination of the knee and diagnostic tests such as X-rays, MRI scans and arthroscopy. X-rays may be needed to rule out any fractures. In addition, Dr. Grimes will often perform the Lachman’s test to see if the ACL is intact. During a Lachman test, knees with a torn ACL may show increased forward movement of the tibia and a soft or mushy endpoint compared to a healthy knee.
Pivot shift test is another test to assess ACL tear. During this test, if the ACL is torn, the tibia will move forward when the knee is completely straight and as the knee bends past 30° the tibia shifts back into correct place in relation to the femur.
The goals of ACL reconstruction surgery is to tighten your knee and to restore its stability and preserve motion.
Anterior cruciate ligament reconstruction is a surgical procedure to replace the torn ACL with a tendon graft.
Most commonly, the graft is obtained from a tissue bank. Dr. Grimes has been performing arthroscopically assisted ACL reconstruction using frozen tissue bank grafts for over 20 years and has not had any problem with the grafts. A distinct advantage of a tissue bank graft is that the tendon graft does not have to be taken from somewhere else on the knee. This helps minimize the invasiveness of the procedure. Tissue bank donors are routinely screened for a wide variety of diseases.
An alternative graft source is to harvest one or more hamstring tendons. The Hamstrings are muscles located on the back of your thigh. A small incision is made over the hamstring tendon attachment to the tibia and the two tendons are stripped off the muscle and the graft is prepared. A disadvantage of harvesting the patient’s hamstring tendons is that it permanently deactivates the associated muscles. Although patients generally do not notice any weakness, computerized muscle testing machines have shown a small percentage of decreased flexion power of the knee after harvesting hamstring tendons.
A third alternative is the patellar tendon graft, also known as bone-tendon-bone graft. This tendon graft is harvested at the time of surgery. The middle third of the tendon that connects the kneecap to the shinbone is removed along with segments of bone at both ends of the graft. If this sounds invasive, it’s because it is. Harvesting this graft can cause more discomfort than the rest of the procedure. Due to the excellent results obtained with tissue bank grafts and hamstring tendon grafts, bone-tendon-bone grafts are rarely used by Dr. Grimes.
The torn ACL remnants will be arthroscopically removed and the pathway for the new ACL is prepared. The arthroscope is reinserted into the knee joint through one of the small incisions. Small holes are drilled into the upper and lower leg bones where these bones come together at the knee joint. The holes form tunnels in your bone to accept the new graft. Then the graft is pulled through the predrilled holes in the tibia and femur. The new tendon is then fixed into the bone with screws to hold it into place while the ligament heals into the bone. The incisions are then closed with sutures and a dressing is placed.
Possible risks and complications associated with ACL reconstruction with hamstring method include:
Following the surgery, rehabilitation begins immediately. A physical therapist will teach you specific exercises to be performed to strengthen your leg and restore knee movement. Swimming and bicycling can be resumed by one month. Some patients may resume straight ahead jogging by 4 months. However, it takes one year for an ACL graft to fully mature. During this time, avoid running, jumping, or cutting sports.
Anterior cruciate ligament reconstruction is a very common and successful procedure. It is usually indicated in patients wishing to return to an active lifestyle especially those wishing to play sports involving running and twisting. Anterior cruciate ligament injury is a common knee ligament injury. If you have injured your ACL, surgery may be needed to regain full function of your knee.