ACL reconstruction is surgery to replace the ligament in the center of the knee (the anterior cruciate ligament, or ACL) with a new ligament.

The purpose of a ligament is to hold two bones together. The ACL is a ligament in the center of your knee that prevents the shin bone (tibia) from moving forward on the thigh bone (femur). A tear of this ligament can cause your knee to give way during physical activity. Research suggests that if a torn ACL is left untreated, and the knee repeatedly gives way, cartilage damage and early arthritis may occur.

ACL reconstruction is surgery to replace the torn ligament. There are several choices of tissue to use for the new ligament, including tissue from your own body (an autograft) or tissue from someone who has died (allograft). The most common autografts use part of the tendon in the front of the knee (patellar tendon) or in the hamstring. Each type of graft has small advantages and disadvantages, and works well for many people.

The procedure is usually done by knee arthroscopy. With arthroscopy, a camera is inserted into the knee through a small poke-hole. The camera is connected to a video monitor. The surgeon checks the cartilage and ligaments of the knee. If there is other damage, such as a meniscus tear, the surgeon will fix the problem. You will most likely go to sleep for the procedure, but it can be performed under different types of anesthesia.

Then, the surgeon will replace the ACL. Other small incisions are made around the knee to place the new ligament. The old ligament will be removed using a shaver or other instruments. Bone tunnels will be made to place the new ligament in the knee at the site of the old ACL. If your own tissue is to be used for the new ligament, a larger, "open" incision will be made to take the tissue. The new ligament is then fixed to the bone using screws or other devices to hold the ligament in place.

At the end of the surgery, the incisions are closed, and a dressing is applied. During the arthroscopy, most surgeons take pictures of the procedure from the video monitor to show you what was found and what was done.

ACL reconstruction may be recommended for knee problems such as:

• Unstable knee
• Knee that gives way
• Knee pain
• Inability to play sports or other activities

The risks for any anesthesia are:

• Allergic reactions to medications
• Problems breathing

The risks for any surgery are:

• Bleeding
• Infection
• Nerve damage

Additional risks include:

• Stiffness of the knee
• Failure of the surgery to relieve symptoms
• Failure of the ligament to heal
• Pain in the knee
• Weakness of the knee

ACL reconstruction is usually a very successful surgery. A tear of the ACL used to be a career-ending injury for many athletes, but improvements in the surgery and in rehabilitation have led to greatly improved results. These improvements have resulted in less pain and stiffness, fewer complications, and faster recovery time. Most people will have a stable knee that does not give way after ACL reconstruction.

After the surgery, you may have to wear a knee brace for the first 1 to 4 weeks. You also may need crutches for 1 to 4 weeks. Most people are allowed to move the knee immediately after surgery to help prevent any stiffness. Pain is usually managed with medication.

Physical therapy can help many people regain motion and strength in the knee. Therapy can last from 2 to 6 months.

How soon you restart activities such as returning to work will depend on your job, but can be anywhere from a few days to a few months. A full return to activities and sports generally takes from 4 to 6 months.