Anterior Cruciate Ligament (ACL) Injuries

Surgery

Most surgery for anterior cruciate ligament (ACL) injuries involves replacing the ACL with tissue called a graft. Usually an autograft (tendon tissue taken from another part of the body) is used. Repair is also done when the ACL has been torn from the upper or lower leg bone (avulsion). This type of injury is uncommon. In the case of an avulsion fracture, the bone fragment connected to the ACL is reattached to the bone.

Most ACL surgery is done by making small incisions in the knee and inserting instruments for surgery through these incisions (arthroscopic surgery). Open surgery (cutting a large incision in the knee) is sometimes required.

The goals of surgical treatment for anterior cruciate ligament (ACL) injuries are to:

• Restore normal or almost normal stability in the knee.
• Restore the level of function you had before the knee injury.
• Limit loss of function in the knee.
• Prevent injury or degeneration to other knee structures.

Surgical techniques and rehabilitation programs used today generally are successful. Between 80% and 90% of people who have ACL surgery have favorable results, with reduced pain, good knee function and stability, and a return to normal levels of activity.⁶ Unfortunately, 3% to 10% of people who have ACL surgery still have knee pain and instability.⁷ Athletes and those who participate in sports generally can return to their sports within months, depending on how intense and sports-focused the rehabilitation was.

Not all ACL tears require surgery. You and your doctor will decide whether rehabilitation only or surgery plus rehabilitation is right for you. For more information, see:

Should I have surgery for an ACL injury?

Before ACL surgery, strength and motion exercises are often done to help condition the knee for surgery and the subsequent rehabilitation program. Surgery is followed by a short period of performing home exercises, increased activity, and the use of crutches for walking. An intensive rehabilitation program to strengthen the knee then begins. The rehabilitation program often lasts up to a year. For more information, see:

ACL injury: Exercises to do before treatment.

Surgery in a child might be necessary to prevent injury to other structures within the knee, such as the menisci. You may consider surgery if the child's knee is very unstable doing simple daily activities, if the knee's instability cannot be controlled with nonsurgical methods, if the child has both an ACL injury and a meniscus tear, or if the child is a serious athlete in sports that require running, jumping, and decelerating. Postsurgery rest and a sustained rehabilitation program are extremely important.⁵

The main risks of surgery in a child whose bones are still growing is slowed growth (physeal arrest), which may result in one leg being longer than another. Other risks include the thigh bone pointing inward (distal femoral valgus or angular limb deformity). The risks of these conditions is lower the closer a child or teen is to skeletal maturity.

Surgery Choices

ACL surgery

What To Think About

• Depending on how severe your injury is, surgery followed by a rehabilitation program may offer the best chance of making your knee stable again and of your continuing an active lifestyle without further pain, injury, or loss of strength and movement in your knee. Without surgery, it is more likely that loss of knee function, osteoarthritis, and other knee problems will develop later.
• In adults, age is not a factor in surgery, although your overall health may be. Surgery may not be the ideal treatment for people with medical conditions that make surgery a greater risk. These people may choose nonsurgical treatment and try to change their activity level to protect their knee from further injury.
• Surgery is sometimes delayed until the swelling goes down, you have full range of motion in your knee again, and you can strongly contract (flex) the muscles in the front of your thigh (quadriceps). You and your doctor decide on the timing of your surgery.
• Whether you have surgery soon after the injury or weeks later does not seem to affect recovery significantly.³
• You will need to follow a rehabilitation program whether or not you have surgery. If you do not complete a rehabilitation program, even with surgery you may not regain full stability and function in your knee.
• If your initial injury resulted in an unstable knee that sometimes gives out (chronic ACL deficiency) and you continue participating in activities that require a stable knee and don't have surgery, you may injure your knee again.
• Possible complications of arthroscopic knee surgery include a loss of motion (most common), pain that does not go away, fluid in the knee joint (postoperative effusion), damage to the knee cartilage from the arthroscope scraping against it, and infection. Other risks include a blood clot in the leg, and in extremely rare circumstances, this blood clot can migrate to the lungs and block blood flow out of the lungs (pulmonary embolism).

You may choose to have surgery if you:

• Have completely torn your ACL or have a partial tear and your knee is very unstable.
• Have gone through a rehabilitation program and your knee is still unstable.
• Are very active in sports or have a job that requires knee strength and stability (such as construction work), and you want your knee to be as strong and stable as it was before your injury.
• Are willing to complete a long and rigorous rehabilitation program.
• Have a chronic ACL deficiency.
• Have injured other parts of your knee, such as the cartilage, meniscus, other knee ligaments, or tendons, or you have broken bones in the knee joint.

You may choose not to have surgery if you:

• Have a minor tear in your ACL (a tear that can heal with rest and rehabilitation).
• Are not very active in sports or your work does not require a stable knee.
• Are willing to stop doing activities that require a stable knee or stop doing them at the same level of intensity. You may choose to substitute other activities that don't require a stable knee, such as cycling or swimming.
• Can complete a rehabilitation program that stabilizes your knee and strengthens your leg muscles to reduce the chances that you will injure your knee again and are willing to live with a small amount of knee instability.
• Do not feel motivated to complete the long and rigorous rehabilitation program necessary after surgery.

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Author:	Shannon Erstad, MBA/MPH	Last Updated: May 16, 2008
Medical Review:	William M. Green, MD - Emergency Medicine Adam Husney, MD - Family Medicine Freddie H. Fu, MD - Orthopedic Surgery Patrick J. McMahon, MD - Orthopedics
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