Surgery for an ACL Tear

Anterior Cruciate Ligament Reconstruction Surgery

ACL graft choice
ACL reconstruction surgery requires the selection of a graft. Credit: Photo ©

An ACL tear is an injury to one of the four major knee ligaments. When an ACL tear occurs, the knee can become unstable, and have a tendency give out when the knee joint is pivoting during sports activities. Because of this, many people who sustain an ACL tear will decide to have ACL surgery in an effort to return to their normal activities.

Timing of Surgery

ACL reconstruction is typically not performed until several weeks after the injury.

Studies have shown improved results when ACL reconstruction surgery is delayed several weeks from the time of injury. This allows the inflamed and irritated knee to cool down. Swelling decreases, inflammation subsides, and range of motion improves. Resolution of swelling and stiffness prior to ACL reconstruction surgery improves the post-operative function of the joint.

More recently, some surgeons have challenged this delay, and there are some locations where ACL reconstruction is performed almost immediately following the injury. The bottom line, is everyone responds differently to ACL injury, and some people have more swelling and stiffness, while others have less acute symptoms. Determining the optimal time for surgery depends on the individual patient's response to the injury. In addition, many patients are best served by a period of time to emotionally prepare to have the surgery and begin the rehabilitation.

Repair or Reconstruction

ACL reconstruction surgery is commonly, and improperly, referred to as an "ACL repair." Unfortunately, a torn ACL cannot be repaired. Rather, the torn ligament must be entirely removed, and a new ACL must be reconstructed using other healthy tissue. It is not possible to repair the torn ACL by simply reconnecting the torn ends.

The correct terminology is an ACL reconstruction, not an ACL repair.

Recent research has investigated some new techniques that do stimulate a healing response of the torn ACL, and augment this with some reconstructive support. This technique is exciting, and may pave the way for a more natural way to heal the ACL, but at this point it is still considered experimental.

Determining Type of Graft

Once the decision is made to undergo ACL reconstructive surgery, the type of reconstruction must be decided. The major decision is whether to use tissue obtained from your body to create a new ACL, or to use tissue from a donor to make the new ACL. There are various pros and cons with each type of graft.

There are also newer techniques, such as the "double-bundle" ACL reconstruction, that may be offered to you. These techniques have not been shown to be more effective at getting people back to their pre-injury level of activities.

Having ACL Reconstruction Surgery

The ACL reconstruction surgery lasts about 1 1/2 to 2 hours, depending on the graft choice and any other work that may need to be done in the knee joint. Following the procedure, you will be given crutches and may be given a knee brace. The decision to use a knee brace is controversial and can be discussed with your doctor.

Some doctors also use a CPM (continuous passive motion) machine in the days following the ACL reconstruction. This is also controversial and may be discussed with your doctor.

There are many variations on how exactly to perform the surgical procedure, and most surgeons have a preferred routine. While it is helpful for patients to research their upcoming surgery and learn about the variations in technique, graft options, and other variables, I always caution patients on trying to fine tune their surgeon's preferred routine. Ask questions, find a surgeon that makes you comfortable, and then trust in their plan.

Altering a surgeon's routine may not be beneficial for your recovery.

Rehab After ACL Surgery

Rehab is one of the most important, yet often neglected, aspects of ACL reconstruction surgery. Rehab following ACL surgery focuses on restoring motion and strength, and improving the stability of the joint to prevent future injuries.

While general guidelines exist for ACL rehab, it is critically important that each person progresses through their rehab as their knee allows. Progressing too quickly or too slowly can be detrimental to overall results from surgery, therefore it is important to ensure your therapist and physician are guiding your rehab.

Return to Sports

More than 90% of patients are able to resume their previous level of activity after ACL reconstruction. A small percentage of patients will be limited by persistent pain or instability; however, changes in activity level following ACL reconstruction surgery are often due to personal choice rather than limitations of the knee joint.


RL Larson and M Tailon "Anterior Cruciate Ligament Insufficiency: Principles of Treatment" J. Am. Acad. Ortho. Surg., Jan 1994; 2: 26 - 35.

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