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.

Not all ACL tears require surgery. You and your health professional 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:

Pretreatment exercises for an ACL injury.

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, the knee's instability cannot be controlled with nonsurgical methods, the child has both an ACL injury and a meniscus tear, or the child is a serious athlete in sports that require running, jumping, and decelerating.^{6, 7} In these cases, postsurgery rest and a sustained rehabilitation program are extremely important.

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 can move your knee again, and you have regained any lost strength in the muscles in the front of your thigh (quadriceps). You and your health professional determine the timing of your surgery.
• Whether you have surgery immediately after the injury or weeks later does not seem to affect recovery significantly.⁴
• 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 occasionally 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; in extremely rare circumstances, this blood clot can migrate to the lungs and block blood flow out of the lungs (pulmonary embolism).