ACL reconstruction


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 ligment in the center of your knee that prevents the shin bone (tibia) from moving forward on the femur (thigh bone). A tear of this ligament can cause your knee to give way during physical activity.

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

The procedure is usually performed 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 evaluates the cartilage and ligaments of the knee. If there is other damage, such as a meniscus tear, the surgeon will fix the problem. Most patients go to sleep for the procedure, but it can be performed under different types of anesthesia.

Then, the surgeon will replace the ACL. Additional 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 the patient’s 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:

  • Instability  
  • Giving way  
  • Knee pain  
  • Inability to play sports or other activities


The risks for any anesthesia are:

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

Expectations after surgery  

ACL reconstruction is usually a very successful surgery. A tear of the ACL used to be a career-ending injury for many athletes, but improvement in the surgery and rehabilitation have led to greatly improved results. These improvements have resulted in less pain and stiffness, fewer complications, and faster recovery time. Up to 90% of patients will have a stable knee that does not give way after ACL reconstruction.


Following the surgery, many patients are placed into a knee brace for the first 1- 4 weeks. Crutches are also necessary for 1 - 4 weeks. Most patients are allowed to move the knee immediately after surgery to help prevent any stiffness. Pain is usually managed with medication.

For many patients, physical therapy can help regain the motion and strength of the knee. The length of therapy can vary, but can last from 2 - 6 months.

Activities such as returning to work will depend on one’s occupation, but can be anywhere from a few days to a few months. A full return to activities and sports generally takes from 4 - 6 months.

Johns Hopkins patient information

Last revised: December 6, 2012
by Dave R. Roger, M.D.

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