Should I have an MRI or arthroscopy to diagnose a possible torn meniscus?

Introduction

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This information will help you understand your choices, whether you choose to share in the decision-making process or to rely on your doctor's recommendation.

Key points in making your decision

If the physical examination suggests a meniscus tear, your doctor may recommend more diagnostic testing to confirm the diagnosis. Magnetic resonance imaging (MRI) and arthroscopy can give an accurate picture of the location and size of your knee injury. Consider the following when making your decision:

• If your doctor thinks you have a minor meniscus tear and symptoms are not severe, you may wait to see if it heals with rest. In these cases, an initial MRI or arthroscopy may not be needed.
• If your doctor thinks you need surgical meniscus repair, the procedure should be performed as soon as possible after the injury. But if the tear is in the red zone and you choose to put off the surgery to see if the meniscus tear heals on its own, a later repair should still heal the meniscus properly.
• If your symptoms are moderate to severe and your doctor thinks you have a meniscus tear, he or she may recommend either an MRI or arthroscopy. Your doctor may also recommend either of these tests if additional injuries to your knee are suspected, such as a torn anterior cruciate ligament (ACL). Some doctors favor skipping MRI in favor of arthroscopy, which can confirm the diagnosis and treat the problem at the same time.
• You may be able to prevent long-term complications, such as osteoarthritis, by diagnosing and subsequently surgically repairing your tear. Although there are no long-term studies to prove this, many doctors believe that successful meniscus repair helps to evenly distribute the forces on the knee joint. If the knee is protected from uneven force, there is a lower risk of joint degeneration.

Medical Information

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What is a meniscus tear?

A meniscus tear is a common knee joint injury. This rubbery tissue acts as a shock absorber between the upper and lower leg bones. Each knee has two C-shaped menisci (plural of meniscus): a lateral meniscus on the outer side of the knee and a medial meniscus on the inner side of the knee. A meniscus tear can limit your knee function. See a picture of the knee and the menisci .

How is the meniscus injured or torn?

A meniscus tear usually occurs with a twisting or pivoting motion and often with the foot planted and the knee partially flexed (for example, when lifting or playing tennis). Other knee injuries, such as a torn ligament, can happen at the same time. In older people whose menisci are worn (degenerated), the menisci may tear more easily. Meniscus tears are rare in young children.

How will I know if I have a meniscus tear?

The symptoms of a meniscus tear often vary. In a typical minor tear, there may be pain and swelling at first. These symptoms usually go away in 2 to 3 weeks.

In a typical moderate tear, you may feel pain at the side or center of the knee, depending on where the tear is located. You likely are still able to walk. Swelling increases gradually over 2 to 3 days and may make the knee feel stiff and limit bending. There's often sharp pain when twisting or squatting. These symptoms go away but tend to recur with minor twisting or overuse.

In severe tears, pieces of the torn meniscus can dislocate into the joint space. This can make the knee catch, pop, or lock. The knee can also feel "wobbly" or unstable, or can give way without warning. You may not be able to straighten it. The knee may swell and become stiff right after the injury, or over 2 to 3 days.

Older people whose menisci are worn may not be able to think of a specific event that caused the tear, or they may recall symptoms developing after a minor incident such as rising from a squatting position. Pain and minimal swelling are often the only symptoms.

How will my doctor diagnose a meniscus tear?

Your doctor will ask how the injury happened and whether you have ever had any other knee injuries. A physical examination is done to determine if a torn meniscus is the cause of your pain and to rule out other knee injuries.

He or she will do a physical examination of both knees to evaluate 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. He or she may suggest that you follow up with an orthopedic surgeon, although it is not always necessary. Your doctor or the orthopedic surgeon may order further diagnostic testing, usually MRI or arthroscopy.

If the initial pain with the injury is severe, you might go to the emergency room. With less severe pain, you might wait to see if the swelling and pain go away. Often, people end up going to a doctor when pain and swelling recur with use.

How will an MRI help in diagnosing a meniscus tear?

Magnetic resonance imaging (MRI) is a test that provides pictures of organs and structures, such as the menisci, inside the body. It produces these images by using a magnetic field and pulses of radio wave energy. MRI typically gives a good picture of the location and size of a meniscus tear and also provides images of the ligaments, cartilage, and tendons.

MRIs of the knee are most helpful to confirm the diagnosis of a meniscus tear and to detect associated injuries to the ligament, cartilage, and tendons.

How is arthroscopy used in diagnosis and treatment of a meniscus tear?

Your doctor may recommend arthroscopy instead of MRI to directly view the structures in your knee, including your meniscus, especially when your symptoms indicate that surgery is needed. Larger tears usually cause more pain and immediate swelling and stiffness, although swelling may also develop over 2 to 3 days. The knee may lock, catch, buckle (suddenly give way), or pop. If other injuries occurred with the meniscus tear, especially torn ligaments, there is increased pain, swelling, and difficulty walking. Often arthroscopy is done in these cases, because surgical repair of the meniscus and/or other knee structures may be needed. Surgical repair is usually done during the initial arthroscopy. During arthroscopy, a thin viewing scope, called an arthroscope, is inserted into the knee joint through a small incision in the skin.

What are discomforts or risks of having an MRI or arthroscopy?

You will not feel any effects from the actual MRI. But the table you lie on may be hard, and the room may be chilly. You may become uncomfortable from lying in one position for a long time. Some people feel uneasy or anxious (claustrophobic) inside a standard, closed-type MRI machine. If this keeps you from lying still, you can be given medicine to help you relax. You may want to talk with your doctor about the availability of an open MRI machine, which is less confining than a standard MRI.

During arthroscopy, bleeding within the joint can occur. There is a small risk of infection, formation of a blood clot in your leg, or nerve or joint damage. Rarely, a serious condition called compartment syndrome can occur if pressure builds within the leg. When this occurs, immediate medical treatment is needed to release the pressure.

After arthroscopy, you may notice swelling of the skin around the incision. This is temporary and should disappear within 2 weeks. It is normal for the site to feel tender for about a week. A small amount of bleeding from the incision site can be expected. Ask your doctor how much drainage to expect.

It may take several weeks for your knee to recover from arthroscopy. Your doctor will give you pain medicine and recommend rehabilitation exercises for you to do during your recovery period. You may have some soreness and pain after the procedure. Your doctor may also instruct you to apply ice to the joint—and possibly elevate it—to reduce swelling and pain. Keep the bandages that cover your incision clean and dry.

How is a meniscus tear treated?

How your doctor treats your meniscus tear depends upon the size and location of the tear, when the injury happened, and your pain, age, health status, and activity level, as well as your surgeon's preference. Treatment options include:

• Nonsurgical treatment with rest, ice, compression, elevation, and physical therapy. This may include wearing a temporary knee brace.
• Surgical repair to sew the tear together.
• Partial meniscectomy, which is surgery to remove the torn section.
• 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 (most commonly to the anterior cruciate ligament [ACL] and/or the medial collateral ligament) may occur at the same time as a meniscus tear. Your doctor may be able to determine this with the physical examination. In these cases, treatment for the meniscus tear will follow the plan for treating the other knee injury.

For more information, see the topic Meniscus Tear.

Your Information

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Your choices are:

• Have a physical examination only, wait to see if knee symptoms subside, and possibly start physical rehabilitation.
• Have further diagnostic testing to see if your meniscus is torn and needs surgical repair.

The decision about whether to have additional diagnostic testing takes into account your personal feelings and the medical facts.

Deciding about more tests

Reasons to have diagnostic tests

Reasons not to have diagnostic tests

Your orthopedist can determine which treatment is best for you based on either of these tests. You and your orthopedist agree that surgical repair is the best way to restore your knee's function. MRIs do not emit radiation or have harmful side effects. Complications of arthroscopy are uncommon. MRI or arthroscopy can also detect injuries to surrounding ligaments and tendons. Surgical repair of a tear in your meniscus may prevent degenerative changes in years to come.

You may not need an MRI, because if the tear is minor it might heal on its own. MRI and arthroscopy are expensive tests. Arthroscopy is a surgical procedure that can involve (rare) complications and requires a recovery period. MRIs can be confining and uncomfortable. They are not recommended for pregnant women; women with IUDs; or people with metal prostheses, surgical clips or pins, or pacemakers.

These personal stories may help you make your decision.

Wise Health Decision

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Use this worksheet to help you make your decision. After completing it, you should have a better idea of how you feel about having tests to diagnose a meniscus tear. Discuss the worksheet with your doctor.

Circle the answer that applies to you.

I am very active so I need to know what's wrong with my knee.	Yes	No	Unsure
I am going to have arthroscopy to determine the cause of my knee pain, because my orthopedist said he could repair the meniscus at the same time if needed.	Yes	No	Unsure
My knee pain went away, but now it has returned. I want to know what's wrong.	Yes	No	Unsure
I have a pacemaker (or an IUD, artificial joint, drug infusion pump, or other metal object inside my body).	Yes	No	Unsure
I am pregnant.	Yes	No	NA*
I am concerned about the cost of MRI or arthroscopy.	Yes	No	Unsure
I am reasonably comfortable in confined spaces.	Yes	No	Unsure
Since surgery could possibly help my knee in the long run, I want to find out if I need it.	Yes	No	Unsure

*NA=Not applicable

Use the following space to list any other important concerns you have about this decision.

What is your overall impression?

Your answers in the above worksheet are meant to give you a general idea of where you stand on this decision. You may have one overriding reason to have or not to have additional diagnostic tests.

Check the box below that represents your overall impression about your decision.

Leaning toward having additional diagnostic tests

Leaning toward NOT having additional diagnostic tests

Return to the topic:

• Meniscus Tear
• MRI of the Knee
• Arthroscopy

Credits

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Author	Shannon Erstad, MBA/MPH
Editor	Kathleen M. Ariss, MS
Associate Editor	Pat Truman, MATC
Primary Medical Reviewer	William M. Green, MD - Emergency Medicine
Specialist Medical Reviewer	Kenneth J. Koval, MD - Orthopedic Surgery, Orthopedic Trauma
Last Updated	September 22, 2008