What are the treatment options for an ACL tear?

The treatment options following an ACL tear are individualized for each patient depending on age, activity level, and the presence or absence of injury to other structures within the knee. In general, surgery is recommended for young patients who are active and for those in whom the ACL tear is associated with injury to other structures in the knee. Nonoperative (nonsurgical) treatment may be recommended in older or more sedentary patients.

The main reason to have surgery is to restore stability to the knee so it no longer gives out or slides too far forward, which is often painful. The other reason — perhaps the most important reason — is to protect the articular cartilage in the knee from being damaged. It is also important to protect the medial and lateral menisci in the knee.

The meniscus is a fibrous type of cartilage that sits between the ends of the tibia and femur, and is attached to the lining of the joint. There are two separate meniscal cartilages in the knee, each somewhat C-shaped: one on the inner half of the knee (the medial meniscus), and one on the outer half (the lateral meniscus). The medial and lateral menisci primarily serve as shock absorbers between the ends of the bones to protect the surface of the articular cartilage. With recurrent episodes of giving way, the meniscus can be damaged or torn, causing it to lose its shock-absorbing capability. Without a functioning meniscus, the articular cartilage is exposed to increased pressure and “wears” away, leading to arthritis. Additionally, the articular cartilage may be directly injured or damaged with each episode of giving way.

Nonsurgical Treatment

Nonsurgical treatment consists of physical therapy, activity modification and use of a brace. The goal of physical therapy is to strengthen the muscles around the knee to compensate for the absence of the ACL. Specifically, strengthening the muscles in the back of the thigh (the hamstrings) is helpful. Activity modification can be very successful. Sports that do not involve cutting, such as jogging, cycling or swimming, can often be performed successfully.

In addition to therapy and activity modification, the use of a hinged sports brace can be attempted. While bracing may be effective in some patients, in others, instability episodes may continue despite their use.

Surgical Treatment and ACL Reconstruction

Once the ACL tears, it has usually sustained enough damage that attempts to surgically repair it are not successful. Consequently, better results are obtained if the ACL is surgically replaced or reconstructed with another tendon from around the knee. There are a number of surgical options for reconstructing the ACL. The type of procedure done may vary from patient to patient depending on a specific surgeon’s preference as well as factors unique to an individual patient.

The surgical procedure is most commonly performed using arthroscopic techniques. Using one or two small incisions on the knee, the graft is taken from the patellar tendon or hamstring tendons, and a tunnel is drilled into both the tibia and femur. The graft is threaded across the knee, leaving a piece of bone in each of the tunnels and the patellar tendon in the position of the original ACL, thus reconstructing the ligament. The graft is then secured in this position, most commonly by “wedging” a screw between the side of the bone and the tunnel. Alternatively, the graft can be secured by other techniques — staples, sutures, buttons, etc. These fixation devices are usually left in place permanently.

In addition to the ACL reconstruction, additional procedures may be done to other structures within the knee if an injury is present. A torn meniscus can be either repaired or trimmed (meniscectomy), and other ligaments can be repaired or reconstructed as well.

Allografts most frequently used today are of the bone-patellar tendon-bone type or from the Achilles tendon at the heel, and come from cadavers that have been screened for infectious diseases, e.g., hepatitis and AIDS. The risk of AIDS from one of these grafts is not known, but it is generally believed to be one out of 1 million. All allografts are carefully screened and tested before they are used in surgery.

How long does rehabilitation take after surgery?

The exact course of therapy may vary somewhat depending on the specific type of reconstruction done, particularly if additional meniscus or ligament surgery was done. Physical therapy is done in a supervised setting in conjunction with a trained therapist. Early in the course of recovery, visits may be two to three times per week, but later, once every week or two is often sufficient. Home exercises are done on days not scheduled for a formal therapy session.

The rehabilitation following ACL reconstruction includes essentially three phases. The first phase of rehabilitation consists of controlling the pain and swelling in the knee, regaining knee motion, and getting an early return of muscle strength. The operated leg is typically placed into a brace immediately after surgery.

Initially, weight-bearing is allowed with crutches and is progressed to full-weight bearing independent of crutches as swelling, motion and muscle strength allows. Most patients are on crutches for one week, although some may be on crutches longer and some shorter. This phase typically takes six to eight weeks.

The second phase emphasizes the recovery of full knee motion and muscle strength. Cycling, running on the treadmill and light jogging are started in this phase. In some patients, a sports brace is obtained to replace the postoperative knee brace. This phase typically lasts from two to four months after surgery.

The final phase consists of graduated return to full activity. Normal muscle strength, coordination and the absence of swelling are required for a successful return to activity. A brace may be recommended early in the return to cutting and pivoting sports. This phase occurs at four to eight months after surgery, depending on the particular patient and the nature of his or her activities.

A patient's rehabilitation is monitored closely by both the therapist and surgeon for evidence of potential problems. Most significantly, patients are cautioned not to attempt a too premature return to full activity, which may cause the knee to be inflamed or reinjured. In every patient, the graft must both heal into place and be incorporated into the knee. Too much stress too soon may increase the risk of graft failure.

What are the potential complications after surgery?

Most patients experience no complications and return to full activity between six and eight months after surgery. However, the most common complications include pain in the front of the knee and loss of knee motion.

Pain in the front of the knee occurs in 10 to 20 percent of patients. Fortunately, it can usually be controlled by modification in the physical therapy protocol. Loss of motion occurs in less than 5 percent of patients and is most common in patients with limited motion before surgery. In some individuals, intermittent pain and swelling occur with activity despite a successful ligament reconstruction. This is often related to the amount of meniscal or cartilage injury that was present and identified at the time of surgery.

In the absence of identifiable causes, a small percentage of patients will end up with a persistent detectable increased amount of motion in their knee (a “loose” graft). This may be related to stretching of the graft over time or due to an additional injury.

Will I be able to return to my previous sporting activities?

Approximately 85 percent of patients return to their previous level of activity without restrictions. In the other 15 percent, a full return may be limited by a number of causes: pain, swelling, persistent laxity, change in lifestyle-related to age, intentional choice or other unidentifiable causes.