Injuries to the anterior cruciate ligament (ACL) are very common in sports. When an ACL is torn, the patient-athlete must decide whether to let it remain so or to have surgery to repair it. Both choices are acceptable ones, depending on the particular desires and expectations of the patient. The purpose of this information is to help you decide which treatment is best for you.
In most cases, the ACL is completely torn ("ruptured"). Partial tears do occur and will be discussed later. Usually, the diagnosis can be made by a careful history and physical examination, but occasionally, other studies are necessary to confirm the diagnosis.
When the ACL is completely torn, the ends fall away from each other, so spontaneous healing is impossible. The unattached ends usually shrivel up and scar down. The patient has two immediate choices: 1) have the ligament surgically reconstructed or 2) try to live without an ACL, retaining the option of later reconstructive surgery should the knee prove unacceptable.
To judge which of these choices is best for you, you must understand what can happen to people whose ACL has ruptured. In medical jargon, we call this the Natural History of an ACL tear.
People who have torn their ACLs will fall into three groups:
- A small, unlucky group will develop a "trick knee" which "gives out" very easily, even with non-stressful activities such as turning around suddenly at home. During such a "giving out" episode, the patient feels the two main bones in his or her leg seem to slip or slide out of place. These episodes may be painful and are often followed by swelling.
- Another small, very lucky group is at the other extreme. Individuals in this group can do virtually anything without trouble. We really don’t know why an individual may fall into one of these first two groups, but we suspect that a number of factors may contribute towards making some knees very dependent on the ACL and others independent of it.
- The vast majority of people with a torn ACL fall between these two extremes. They can do all non-stressful daily activities and "straight ahead" sports such as running, swimming and bicycling without difficulty, but have some degree of "giving out" when they engage in activities requiring jumping, pivoting, cutting, or sudden changes of direction. Some of these people will find that their instability is controlled adequately by wearing a special brace, while others in this group will find that their knees give out even while wearing such a brace. The sports which present the most difficulty are those which require a lot of jumping or cutting and in which the athlete must react suddenly to another player. (Basketball, volleyball, soccer and football are good examples.) Sports in which the athlete may control his or her risk if he or she is willing to voluntarily moderate his or her participation are less likely to cause trouble.(Tennis, racquet ball and skiing are examples of this type of sport.)
In any case, the goal of the chosen treatment is to prevent "giving out" episodes. Not only are these episodes painful and inconvenient, they may cause secondary damage to the menisci ("cartilages") and the joint surfaces and thereby increase the risk of premature arthritis in the knee.
Let us look more closely at the advantages and disadvantages of the two treatment options.
Option One: Early Surgical Reconstruction of the ACL
The principal advantage of early surgery is that it provides the best chance of having normal knee function following an ACL tear. The surgery has about a 90-95% success rate. In other words, nine out of ten people who have this operation will not develop "giving out" episodes or cause further damage to their "cartilages" or joint surfaces. The primary disadvantage of early surgery is that it exposes the patient to the risks normally associated with knee surgery including infection, thromboembolism (blood clots traveling from the leg to the lungs) and post-operative stiffness. Modern techniques of surgery and rehabilitation have lowered the chance of these problems, but cannot completely eliminate these risks.
Option Two: Allowing the Ligament to Remain Torn
The principal advantage of this option is that the person choosing it avoids an operation and its associated risks, perhaps forever. The principal disadvantage is that it may not work, and the patient may end up with a "trick knee" which requires surgery months or years after the original injury. These knees may usually be helped with later reconstructive surgery, but may suffer unrepairable damage to the joint surfaces or "cartilages" during the period when the knee was unstable.
Which option is better for you?
Ideally, we would like to be able to foretell which patients will develop "trick knees" and offer them early surgery while discouraging surgery in the ones who will be able to get along without their ACL. Unfortunately, there is no way of predicting the future with 100% certainty in every case. There are, however, guidelines which are very helpful. Patients who refuse to give up "high risk" sports such as basketball, volleyball, soccer or football or to moderate their "aggressiveness" in medium-risk sports such as tennis, racquetball, or skiing, will probably not be satisfied with the results of non-surgical treatment. Conversely, patients who are willing to give up high risk sports and moderate their participation in medium-risk sports will often be satisfied without surgery. Treatment results tend to be age-related, but only because people’s priorities change with age. For example, a study from Baylor University showed that 80% of male patients under age 20 had major giving out episodes within a year of their initial injury, while very few patients over 30 had such problems. This is probably because men younger than 20 generally like to play high-risk sports and usually refuse to moderate their "aggressiveness." Conversely, people over age 30 have many family and career obligations and are often willing to moderate their sports participate in favor of low-risk sports.
If you are an elite athlete, or younger than 20, it is highly recommended to undergo reconstruction because of the high risk of re-injury ("giving way") to the knee. With each re-injury to the knee, there is an increased risk of damage to the cartilage, which further increases the risk of developing arthritis.
Making your Choice
You should, therefore, base your choice upon your own sports priorities. If you wish to play "high risk" sports at a competitive level, then surgery is usually the better option for you. If you are a recreational athlete and are willing to moderate your sports participation, you probably will be satisfied with the result of non-surgical treatment. Remember, however, that there is always some chance that you will develop "giving out" even at reduced activity levels and may later require reconstructive surgery. Some who choose non-surgical treatment may avoid ligament reconstruction, but require outpatient arthroscopic surgery because of associated "cartilage" tears or because the ends of the torn ligament are interfering with normal knee function.
There are many other factors which may influence your individual decision. If, after considering the alternatives and discussing them with me and your loved one, you are still having trouble making a decision, you probably should choose non-surgical treatment. Some people find a "second opinion" helpful in coming to a decision. I would be happy to provide you with a list of orthopedists who are knowledgeable in the field of knee injuries.
Timing and Techniques
It used to be taught that ACL surgery needed to be done with a "golden period" of 7-10 days following the injury. That is because early surgery used to mean suturing back together the shredded ends of the torn ACL. Since these remnants quickly "shrivel up," surgery had to be done soon after the injury. The results of this type of surgery have been shown to be very unreliable, and very few prominent sports medicine specialists now do it. All sports medicine specialists, myself included, now replace the ACL with a tendon graft. Because the graft provides the real strength of the repair and is "harvested" at the time of the surgery, early ACL surgery may safely be postponed a few weeks or even a few months if this would be more convenient with the demands of school or work. The risk of such a delay is small if the patient avoids stressful activities such as sports or dancing during the "waiting period." Recent studies show you are most likely to have problems regaining normal knee motion after the ACL reconstruction if you have surgery too soon after the ligament injury. Therefore, even if you are certain that you want to have ligament reconstruction, it is important to wait a few weeks to regain your motion and allow swelling to resolve prior to surgery.
There are four techniques that are used to reconstruct the anterior cruciate ligament. The two most common techniques are to utilize either a segment of your own patellar tendon or the hamstring tendons to reconstruct the anterior cruciate ligament.
The graft is implanted in the knee using arthroscopic techniques. This technique appears to reduce the chance of scarring within the joint (adhesion) and consequent stiffness compared to conventional methods. Skin incisions are still utilized to obtain the tendon graft and to fix both ends in place.
Some patients may prefer to have an allograft reconstruction. In this case, a similar piece of tendon is transplanted from a diseased donor. Although these tendons are very carefully screened and treated before use, there is a remote chance that a disease, such as hepatitis or AIDS may be transmitted from the deceased donor to the patient receiving the transplant. Allograft tissue probably takes longer to be incorporated than your own (autograft) tissue. For this reason, I only recommend using allograft for cases in which suitable autograft tissue is limited.
A final technique which is available is the use of synthetic ligament substitutes such as the Goretex ligament. Because their long-term results are uncertain, they have only been approved by the FDA for patients in whom conventional ligament reconstruction has failed. These may prove very valuable in the future. I do not currently recommend the use of synthetic ligaments except in very unusual cases.
Partial ACL Tears
As mentioned above, partial ACL tears sometimes occur. These will vary in severity from cases in which the entire ligament is permanently elongated but not disrupted, to cases in which part of the ligament is totally ruptured and the rest is elongated but still in continuity. Because at least part of the ligament is continuous, it will sometimes heal into a structure which will be strong enough to prevent "giving-out" of the knee. In other partial tears, the residual ligament will stretch and tear with time, leaving the patient in the same situation as one whose ligament ruptured completely at the time of the initial injury. Because some of these partial tears will heal into a functioning ACL, I advise most patients with a partial ACL tear to give the ligament time to heal before making a final decision regarding ligament reconstruction.
