Patient education: Anterior cruciate ligament tear (The Basics)

What is an anterior cruciate ligament tear? — 

This is a type of knee injury. It usually causes swelling and pain in the knee. It also makes the knee feel unstable, or like it is "giving out."

A ligament is a tough band of tissue that connects 1 bone to another. The anterior cruciate ligament, or "ACL," connects the thigh bone (called the "femur") to the shin bone (called the "tibia") (figure 1). It works with another ligament to keep the knee from moving too far forward or backward.

What are the symptoms of an ACL tear? — 

People often hear a "pop" when the ACL tears. This tends to happen when people are playing sports that involve quick changes in direction, such as basketball or soccer. It can also happen when a person slows down suddenly while changing direction or lands from a jump.

Within a few hours of an ACL injury, the knee usually swells. It can also feel unstable or wobbly, like it can't hold your weight.

Is there a test to check for an ACL tear? — 

Yes. If your doctor or nurse thinks that you might have an ACL tear, they will do an exam. They might also order an imaging test called an MRI. This test creates pictures of the inside of your knee.

What can I do on my own to feel better? — 

You might feel better if you do certain exercises. Ask your doctor or nurse which exercises might help.

Should I see a doctor or nurse? — 

Yes. If you have the symptoms listed above or think that you might have an ACL injury, see your doctor or nurse.

How are ACL tears treated? — 

You will do special exercises for a while after your injury. These exercises are called "rehabilitation," or "rehab." They help you strengthen your knee and get back the ability to move it around.

After the swelling and pain get better, some people have surgery to rebuild the torn ACL. Doctors remove the damaged ACL, then replace it with a strip of tissue taken from another part of the leg. (Sometimes, the tissue comes from another person's leg.) After surgery, people do a lot more rehab to make sure that the rebuilt ACL works well.

But some people do not need surgery. Instead, they just do more rehab work.

The decision about whether to have surgery depends on a lot of things, including:

●How unstable your knee feels after some rehab

●How severe your injury is – Surgery is often needed if other parts of the knee are also injured.

●What kind of physical activity you do – If you are very active or do a lot of things that involve twisting or turning your knee, surgery might be a good idea.

●Your age

●If you have other health problems

●If you are willing to do a lot of rehab after surgery to make sure that the repaired ACL works well

Should I have surgery? — 

You and your doctor will work together to decide. As you talk about surgery, ask:

●How will my rehab be different if I do or do not have surgery?

●What are the risks of surgery?

●What are the risks of not having surgery?

●How well will my knee work if I have surgery?

●Will I be able to keep doing my favorite physical activities if I do not have surgery?

How can I prevent ACL injuries? — 

You can reduce your chances if you:

●Stay active, and do exercises that make the muscles that support the knee strong and flexible. As part of your training, work on your balance. For example, practice standing on 1 foot.

●Learn how to move so there is less stress on your knee during sports. This might involve talking to a fitness expert. They can show you how to move and position your body to protect your knee, especially during physical activity.

More on this topic

Patient education: Knee sprain (The Basics)
Patient education: Knee arthroscopy (The Basics)
Patient education: How to use a knee brace (The Basics)

Patient education: Anterior cruciate ligament injury (Beyond the Basics)