A meniscus tear is a common knee injury. The meniscus is a rubbery, C-shaped disc that cushions your knee. Each knee has two menisci (plural of meniscus)—one at the outer edge of the knee and one at the inner edge. The menisci keep your knee steady by balancing your weight across the knee. A torn meniscus can prevent your knee from working right.

A meniscus tear is usually caused by twisting or turning quickly, often with the foot planted while the knee is bent. These tears can occur when you lift something heavy or play sports. Other knee injuries, such as a torn ligament, can happen at the same time. As you get older, your meniscus gets worn. This can make it tear more easily.

Symptoms of a meniscus tear depend on the size and location of the tear. They also depend on your age and the health of your knee.

Symptoms may include things like knee pain, swelling, or stiffness. It may be hard to walk. Your knee may feel unstable, or it may be hard to straighten all the way. Or you may feel like your knee "catches" when you move.

Some people have severe pain and swelling right away when the tear happens. Or they might have less pain and swelling at first but then notice that it gets worse over a few days.

Older people sometimes don't notice when the tear happens. But then they notice symptoms later.

Your doctor will ask how the injury happened and if you have ever had any other knee injuries. Your doctor may also ask you about pain, swelling, locking, or buckling of the knee. You will have a physical examination to find out if you have a torn meniscus and to rule out other knee injuries.

Your doctor will check both knees for tenderness, range of motion, and knee stability. X-rays are usually done. Based on your symptoms and the physical examination, your doctor may diagnose a meniscus tear. They may suggest that you follow up with an orthopedic surgeon, although it is not always needed. Your doctor or the orthopedic surgeon may suggest other tests such as an MRI or arthroscopy.

If your pain is very bad at first, you might go to the emergency room. If your pain is not so bad, you may wait to see if it goes away. Most people go to the doctor when pain and swelling comes back after they use their knee.

Magnetic resonance imaging (MRI) is a test that provides pictures of organs, bones, and joints. It makes these images by using a magnetic field and pulses of radio wave energy. MRI gives a good picture of the size of a meniscus tear and where it is. It also shows ligaments, cartilage, and tendons.

MRIs of the knee are helpful to identify a meniscus tear and to find any related injuries to the ligament, cartilage, and tendons.

Arthroscopy is a way to find problems and do surgery inside a joint without making a large cut (incision). Your doctor puts a lighted tube with a tiny camera—called an arthroscope, or scope—and surgical tools through small incisions.

Your doctor may recommend that you have arthroscopy instead of MRI if they think you might benefit from surgery to repair or remove part or all of your meniscus.

You will not have any side effects from the MRI test. But you may have some discomfort. For example:

• The table you lie on may be hard, and the room may be chilly.
• You may have discomfort from lying in one position for a long time.
• Some people feel worried or anxious inside a standard, closed-type MRI machine. If this keeps you from lying still, you can be given medicine to help you relax. Or you can talk with your doctor about using an open MRI machine, which is less confining than a standard MRI.

Risks of arthroscopy include:

• Bleeding within the joint.
• Infection.
• Blood clotting in your leg.
• Nerve or joint damage.
• A rare risk of compartment syndrome if pressure builds within the leg. When this occurs, you need treatment right away to release the pressure.

After arthroscopy, you may have swelling around the incision. This should go away within 2 weeks. It's normal for the site to feel tender for about a week. A small amount of bleeding from the incision is normal. Ask your doctor how much drainage to expect.

It may take several weeks to recover from arthroscopy. Your doctor may give you pain medicine and recommend rehabilitation exercises for you to do while you recover. You may have some soreness and pain after the procedure. You may need to apply ice to the joint and prop up the leg to reduce swelling and pain. Keep the bandages that cover your incision clean and dry.

How your doctor treats your meniscus tear depends upon the size and location of the tear; when the injury happened; your pain, age, health status, and activity level; and your surgeon's preference. Your treatment choices are:

• Non-surgical treatment with rest, ice, compression, elevation, and physiotherapy. You may wear a temporary knee brace.
• Surgical repair to sew the tear together.
• Partial meniscectomy, which is surgery to remove the torn section of the meniscus.
• Total meniscectomy, which is surgery to remove the entire meniscus. This is generally avoided, because this option increases the risk for osteoarthritis in the knee.

Other knee injuries, such as to the anterior cruciate ligament (ACL) or the medial collateral ligament, may happen at the same time as a meniscus tear. Your doctor may be able to find this out during a physical examination. In these cases, the meniscus tear will be treated as part of the treatment for the other injury.

Your doctor may advise you to have an MRI test or arthroscopy because:

• Surgery may be an option for you.
• The test could change your treatment plan.
• The test could help you decide what kind of surgery to have.