Tips for Preventing an ACL Knee Ligament Injury

The knee is a joint where three bones join: the femur, or thigh bone; the tibia, or shin bone; and the patella, or knee cap. Four ligaments attach to the femur and tibia and give the joint strength and stability. One of these, the anterior cruciate ligament (ACL), is in the center of the knee and limits rotation and the forward movement of the tibia. Each year, more than 100,000 Americans tear their ACLs.

The ACL is most often stretched or torn (or both) by a sudden twisting motion -- when, for example, your feet are planted one way and your knees are turned another. You can also injure your ACL by quickly changing the direction in which you're moving; by putting the brakes on too quickly when running; or, if you're a woman, when landing from a jump. A woman's body structure causes her to land with more flex in her ankle and more foot roll out, which puts more stress on the knee.

"The ACL unravels like a braided rope when it's torn and doesn't heal on its own. But reconstruction surgery can help most people recover full knee function after an ACL tear," says Letha Y. Griffin, M.D., an orthopedic surgeon in Atlanta.

Recognizing an ACL injury

People who play basketball, volleyball or soccer or who ski are most likely to injure their ACLs when they slow down, pivot or land after a jump.

If you injure yours, you may not feel any pain immediately. You might hear a popping noise and feel your knee give out from under you.

Within a few hours, you'll notice swelling at the knee. The knee will hurt when you try to stand on it. It's important to keep weight off the knee until you can see your health care provider, or you may injure the knee cartilage. You should use an ice pack to reduce swelling and keep the leg elevated. If needed, use a pain reliever. If you must walk, use crutches.

"You need to get to your doctor right away to have your knee evaluated," says Dr. Griffin.

Diagnosis

Your doctor may conduct physical tests and take X-rays to determine the extent of your ACL damage. If the ACL is only partially torn, your doctor may prescribe an exercise program to strengthen surrounding muscles and a brace to protect the knee during activity. You may or may not need surgery. Surgery can reattach the torn ends of the ligament or reconstruct the torn ligament from a piece (graft) of strong, healthy tissue taken from another area near the knee (autograft) or from a cadaver (allograft). If the ACL is completely torn, it may need to be replaced surgically.

Successful surgery tightens your knee and restores its stability, which helps you avoid further injury.

"After ACL reconstruction, you'll need to do rehabilitation exercises to gradually return your knee to full flexibility and stability," says Dr. Griffin.

You also may need a knee brace temporarily and will probably have to stay out of sports for about a year after the surgery.

Prevention

Many ACL injuries can be prevented if the muscles that surround the knees are strong and flexible.

"Athletes of all ages should do drills that focus on balance, as well as those that link strength and speed," says Dr. Griffin. "Jumping and other balance drills help to provide conditioning that can reduce the risk of ACL injury."

Athletes also should practice staying balanced over their lower legs and playing on the balls of their feet with their hips and knees flexed.

The following training tips can reduce the risk of an ACL injury:

• Train and condition year-round.

• Practice proper landing technique after jumps.

• When you pivot, crouch and bend at the knees and hips. This reduces stress on the ACL.

• Strengthen your hamstring and quadriceps muscles. The hamstring muscle is at the back of the thigh; the quadriceps muscle is at the front. The muscles work together to bend or straighten the leg. Strengthening both muscles can better protect the leg against knee injuries.