No Perfect Solution for Knee Ligament Injuries

Question: My son is a college ball player. He suffered an anterior cruciate ligament injury. What is that exactly? What should be done?

Answer: Skiers, runners, ball players, athletes of all kinds are vulnerable to knee injuries. It’s bad news, though, when the anterior cruciate ligaments are involved because they are vital stabilizers of the knee. You can’t ignore the injury and hope it will go away. In fact, it will probably get worse. Here’s what you should know, and what you can do.

Picture the problem. The knee’s anterior cruciate ligament runs from the back of the femur (bigger leg bone) to attach on the articular (front) of the joint surface of the tibia (smaller leg bone).

Running through the ligament is a large artery. If the ligament tears, the artery is destroyed. That limits the capacity of the ligament to heal itself with anything approaching normal strength. You can sew the fibers back together but they won’t survive, so they no longer keep the knee strong and stable. If the ligament is merely torn from its attachment, reimplantation is usually successful and normal function returns.

The problem persists. Twenty years ago, an athlete with an anterior cruciate injury was out of luck. Doctors couldn’t help much. The injured athletes were told to strengthen the leg muscles as much as possible, but in fact, it usually meant the end of competitive sports. As time goes on, the injured knee becomes worse. The slightest pressure might make it give way. Increasing wear and tear inside the knee leads to painful arthritic changes.

Surgeons try to compensate. Knee surgeons look for ways to compensate for damaged anterior cruciate ligaments. They may try transferring other tendons around the inside of the knee to minimize rotational instability.

Sometimes it works well and the player can return to sports. Even when it does work, however, it tends to be a temporary solution: In time, the tendon replacement will stretch, too, and the knee will become unstable again.

Surgeons may also try replacing the cruciates with healthy tendons from the hamstrings, quadriceps or elsewhere. All of these replacements have drawbacks. They are either not as strong as the original ligament or they weaken other structures in the knee.

- Looking for a better solution. Currently, doctors are searching for some synthetic material to replace the anterior cruciate ligaments. This material has to be strong and provide stability throughout the entire range of knee motion. A synthetic ligament must also be compatible with the body’s tissues. It can’t cause reaction and infection.

A variety of synthetic substances have been used as experimental transplants: carbon fibers, Dacron, polypropolene, even ligaments from other animals. So far, nothing has been universally successful.

You and your son should be in touch with the best sports medicine people you can find. Know that there is no perfect solution to the anterior cruciate problem, but medical scientists are working on it. Let’s hope.