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Questions and Answers About Knee Problems

Savvy Consumer: Questions and Answers About Knee Problems
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National Institute of Arthritis and Musculoskeletal and Skin Diseases

This fact sheet contains general information about knee problems. It includes descriptions and a diagram of the different parts of the knee, including bones, cartilage, muscles, ligaments, and tendons. Individual sections of the fact sheet describe the symptoms, diagnosis, and treatment of specific types of knee injuries and conditions. (See index.) Information is also provided on the prevention of knee problems.

What Causes Knee Problems?

Some knee problems result from wear of parts of the knee, such as occurs in osteoarthritis. Other problems result from injury, such as a blow to the knee or sudden movements that strain the knee beyond its normal range of movement.

How Can People Prevent Knee Problems?

  • Some knee problems, such as those resulting from an accident, cannot be foreseen or prevented. However, a person can prevent many knee problems by following these suggestions:
  • First warm up by walking or riding a stationary bicycle, then do stretches before exercising or participating in sports. Stretching the muscles in the front of the thigh (quadriceps) and back of the thigh (hamstrings) reduces tension on the tendons and relieves pressure on the knee during activity.
  • Strengthen the leg muscles by doing specific exercises (for example, by walking up stairs or hills, or by riding a stationary bicycle). A supervised workout with weights is another pathway to strengthening leg muscles that benefit the knee.
  • Avoid sudden changes in the intensity of exercise. Increase the force or duration of activity gradually.
  • Wear shoes that both fit properly and are in good condition to help maintain balance and leg alignment when walking or running. Knee problems may be caused by flat feet or overpronated feet (feet that roll inward). People can often reduce some these problems by wearing special shoe inserts (orthotics). Maintain appropriate weight to reduce stress on the knee. Obesity increases the risk of degenerative (wearing) conditions such as osteoarthritis of the knee.

What Kinds of Doctors Treat Knee Problems?

Extensive injuries and diseases of the knees are usually treated by an orthopaedic surgeon, a doctor who has been trained in the nonsurgical and surgical treatment of bones, joints, and soft tissues (for example, ligaments, tendons, and muscles). Patients seeking nonsurgical treatment of arthritis of the knee may also consult a rheumatologist (a doctor specializing in the diagnosis and treatment of arthritis and related disorders).

What Are the Major Structures of the Knee? What Do They Do?

The knee joint works like a hinge to bend and straighten the lower leg. It permits a person to sit, stand, and pivot. The knee is composed of the following parts (see diagram):

[Image omitted]

Structures of the Knee

Bones and Cartilage

The knee joint is the junction of three bones—the femur (thigh bone or upper leg bone), the tibia (shin bone or larger bone of the lower leg), and the patella (kneecap). The patella is about 2 to 3 inches wide and 3 to 4 inches long. It sits over the other bones at the front of the knee joint and slides when the leg moves. It protects the knee and gives leverage to muscles.

The ends of the three bones in the knee joint are covered with articular cartilage, a tough, elastic material that helps absorb shock and allows the knee joint to move smoothly. Separating the bones of the knee are pads of connective tissue called menisci, which are divided into two crescent-shaped discs positioned between the tibia and femur on the outer and inner sides of each knee. The two menisci in each knee act as shock absorbers, cushioning the lower part of the leg from the weight of the rest of the body, as well as enhancing stability.


There are two groups of muscles at the knee. The quadriceps muscle comprises four muscles on the front of the thigh that work to straighten the leg from a bent position. The hamstring muscles, which bend the leg at the knee, run along the back of the thigh from the hip to just below the knee.


Ligaments are strong, elastic bands of tissue that connect bone to bone. They provide strength and stability to the joint. Four ligaments connect the femur and tibia:

  • The medial collateral ligament (MCL) provides stability to the inner (medial) aspect of the knee.
  • The lateral collateral ligament (LCL) provides stability to the outer (lateral) aspect of the knee.
  • The anterior cruciate ligament (ACL), in the center of the knee, limits rotation and the forward movement of the tibia.
  • The posterior cruciate ligament (PCL), also in the center of the knee, limits backward movement of the tibia.

Other ligaments are part of the knee capsule, which is a protective, fiber-like structure that wraps around the knee joint. Inside the capsule, the joint is lined with a thin, soft tissue, called synovium.


Tendons are tough cords of tissue that connect muscle to bone. In the knee, the quadriceps tendon connects the quadriceps muscle to the patella and provides power to extend the leg. The patellar tendon connects the patella to the tibia. Technically, it is a ligament, but it is commonly called a tendon.

How Are Knee Problems Diagnosed?

Doctors use several methods to diagnose knee problems.

  • Medical history—the patient tells the doctor details about symptoms and about any injury, condition, or general health problem that might be causing the pain.
  • Physical examination—the doctor bends, straightens, rotates (turns), or presses on the knee to feel for injury and discover the limits of movement and location of pain.
  • Diagnostic tests—the doctor uses one or more tests to determine the nature of a knee problem.
  • X ray (radiography)—an x-ray beam is passed through the knee to produce a two-dimensional picture of the bones.
  • Computerized axial tomography (CAT) scan—x rays lasting a fraction of a second are passed through the knee at different angles, detected by a scanner, and analyzed by a computer. This produces a series of clear cross-sectional images ( slices”) of the knee tissues on a computer screen. CAT scan images show soft tissues more clearly than normal x rays. Individual images can be combined by computer to give a three-dimensional view of the knee.
  • Bone scan (radionuclide scanning)—a very small amount of radioactive material is injected into the patient's bloodstream and detected by a scanner. This test detects blood flow to the bone and cell activity within the bone, and can show abnormalities in these processes that may aid diagnosis..
  • Magnetic resonance imaging (MRI)—energy from a powerful magnet (rather than x rays) stimulates tissues of the knee to produce signals that are detected by a scanner and analyzed by computer. This creates a series of cross-sectional images of a specific part of the knee. An MRI is particularly sensitive for detecting damage or disease of soft tissues, such as ligaments and muscles. As with a CAT scan, a computer can be used to produce three-dimensional views of the knee during MRI.
  • Arthroscopy—the doctor manipulates a small, lighted optic tube (arthroscope) that has been inserted into the joint through a small incision in the knee. Images of the inside of the knee joint are projected onto a television screen.

Index to Knee Injuries and Problems

Cartilage Injuries and Disorders
Arthritis of the Knee
Ligament Injuries
Tendon Injuries and Disorders
Other Knee Injuries

Cartilage Injuries and Disorders


What Is Chondromalacia?

Chondromalacia (pronounced KON-DRO-MAH-LAY-SHE-AH), also called chondromalacia patellae, refers to softening of the articular cartilage of the kneecap. The disorder occurs most often in young adults and may be caused by trauma, overuse, parts out of alignment, or muscle weakness. Instead of gliding smoothly across the lower end of the thigh bone, the kneecap rubs against it, thereby roughening the cartilage underneath the kneecap. The damage may range from a slight abnormality of the surface of the cartilage to a surface that has been worn away completely to the bone. Traumatic chondromalacia occurs when a blow to the knee cap tears off either a small piece of articular cartilage or a large fragment containing a piece of bone (osteochondral fracture).

What Are the Symptoms of Chondromalacia? How Is It Diagnosed?

The most frequent symptom of chondromalacia is a dull pain around or under the kneecap that worsens when walking down stairs or hills. A person may also feel pain when climbing stairs or during other activities when the knee bears weight as it is straightened. The disorder is common in runners and is also seen in skiers, cyclists, and soccer players. A patient's description of symptoms and a followup x ray usually help the doctor make a diagnosis. Although arthroscopy can confirm the diagnosis of chondromalacia, it is not performed unless the condition requires extensive treatment.

How Is Chondromalacia Treated?

Many doctors recommend that patients with chondromalacia perform low-impact exercises that strengthen muscles, particularly the inner part of the quadriceps, without injuring joints. Swimming, riding a stationary bicycle, and using a cross-country ski machine are acceptable as long as the knee is not bent more than 90 degrees. Electrical stimulation may also be used to strengthen the muscles. If these treatments fail to improve the condition, the physician may perform arthroscopic surgery to smooth the surface of the articular cartilage and wash out” cartilage fragments that cause the joint to catch during bending and straightening. In more severe cases of chondromalacia, surgery may be necessary to correct the angle of the kneecap and relieve friction involving the cartilage or to reposition parts that are out of alignment.

Injuries to the Meniscus

What Is the Cause of Injuries to the Meniscus?

The two menisci are easily injured by the force of rotating the knee while bearing weight. A partial or total tear of a meniscus may occur when a person quickly twists or rotates the upper leg while the foot stays still (for example, when dribbling a basketball around an opponent or turning to hit a tennis ball). If the tear is tiny, the meniscus stays connected to the front and back of the knee; if the tear is large, the meniscus may be left hanging by a thread of cartilage. The seriousness of a tear depends on its location and extent.

What Are the Symptoms of Injury?

Generally, when people injure a meniscus, they feel some pain, particularly when the knee is straightened. The pain may be mild, and the person may continue activity. Severe pain may occur if a fragment of the meniscus catches between the femur and tibia. Swelling may occur soon after injury if blood vessels are disrupted, or swelling may occur several hours later if the joint fills with fluid produced by the joint lining (synovium) as a result of inflammation. If the synovium is injured, it may become inflamed and produce fluid to protect itself. This causes swelling of the knee. Sometimes, an injury that occurred in the past but was not treated becomes painful months or years later, particularly if the knee is injured a second time. After any injury the knee may click, lock, or feel weak. Symptoms of meniscal injury may disappear on their own but frequently, symptoms persist or return and require treatment.

How Is Meniscal Injury Diagnosed?

In addition to listening to the patient's description of the onset of pain and swelling, the physician may perform a physical examination and take x rays of the knee. The examination may include a test in which the doctor flexes (bends) the leg then rotates the leg outward and inward while extending it. Pain or an audible click suggests a meniscal tear. An MRI test may be recommended to confirm the diagnosis. Occasionally, the doctor may use arthroscopy to help diagnose and treat a meniscal tear.

How Is an Injured Meniscus Treated?

If the tear is minor and the pain and other symptoms go away, the doctor may recommend a muscle-strengthening program. Exercises for meniscal problems are best performed with initial guidance from a doctor and physical therapist or exercise therapist. The therapist will make sure that the patient does the exercises properly and without risk of new or repeat injury. The following exercises after injury to the meniscus are designed to build up the quadriceps and hamstring muscles and increase flexibility and strength.

  • Warming up the joint by riding a stationary bicycle, then straightening and raising the leg (but avoiding straightening the leg too much).
  • Extending the leg while sitting (a weight may be worn on the ankle for this exercise).
  • Raising the leg while lying on the stomach.
  • Exercising in a pool, including walking as fast as possible in chest-deep water, performing small flutter kicks while holding onto the side of the pool, and raising each leg to 90 degrees in chest-deep water while pressing the back against the side of the pool.

If the tear to a meniscus is more extensive, the doctor may perform either arthroscopic surgery or open surgery” to see the extent of injury and to repair the tear. The doctor can suture (sew) the meniscus back in place if the patient is relatively young, the injury is in an area with a good blood supply, and the ligaments are intact. Most young athletes are able to return to vigorous sports with meniscus-preserving repair.

If the patient is elderly or the tear is in an area with a poor blood supply, the doctor may cut off a small portion of the meniscus to even the surface. In some cases, the doctor removes the entire meniscus. However, degenerative changes, such as osteoarthritis, are more likely to develop in the knee if the meniscus is removed. Medical researchers are currently investigating a procedure called an allograft, in which the surgeon replaces the meniscus with one from a cadaver. A grafted meniscus is fragile and may shrink and tear easily. Researchers have also attempted to replace a meniscus with an artificial one, but the procedure is even less successful than an allograft.

Recovery after surgery to repair a meniscus takes several weeks longer and post-operative activity is slightly more restricted than when the meniscus is removed. Nevertheless, putting weight on the joint actually fosters recovery. Regardless of the form of surgery, rehabilitation usually includes walking, bending the legs, and doing exercises that stretch and build up the leg muscles. The best results of treatment for meniscal injury are obtained in people who do not show articular cartilage changes and who have an intact anterior cruciate ligament.

Arthritis of the Knee

What Is Arthritis of the Knee?

Arthritis of the knee is most often osteoarthritis, a degenerative disease where cartilage in the joint gradually wears away. In rheumatoid arthritis, which can also affect the knees, the joint becomes inflamed and cartilage may be destroyed.1 Arthritis not only affects joints, it may also affect supporting structures such as muscles, tendons, and ligaments.

Osteoarthritis may be caused by excess stress on the joint, such as from repeated injury, deformity, or if a person is overweight. It most often affects middle-aged and older people. A young person who develops osteoarthritis may have an inherited form of the disease or may have experienced continuous irritation from an unrepaired torn meniscus or other injury. Rheumatoid arthritis usually affects people at an earlier age than osteoarthritis.

What Are the Signs of Knee Arthritis and How Is It Diagnosed?

A person who has arthritis of the knee may experience pain, swelling, and a decrease in knee motion. A common symptom is morning stiffness that lessens after moving around. Sometimes the knee joint locks or clicks when the knee is bent and straightened, but these signs may also occur in other knee disorders. The doctor may confirm the diagnosis by performing a physical examination and taking x rays, which typically show a loss of joint space. Blood tests may be helpful for diagnosing rheumatoid arthritis, but other tests may be needed as well. Analysis of fluid from the knee joint may be helpful in diagnosing some kinds of arthritis. The doctor may use arthroscopy to directly visualize damage to cartilage, tendons, and ligaments and to confirm a diagnosis, but arthroscopy is usually done only if a repair procedure is to be performed.

How Is Arthritis of the Knee Treated?

Most often osteoarthritis of the knee is treated with analgesics (pain-reducing medicines), such as aspirin or acetaminophen (Tylenol):* nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Nuprin, Advil); and exercises to restore joint movement and strengthen the knee. Losing excess weight can also help people with osteoarthritis. Rheumatoid arthritis of the knee may require a treatment plan that includes physical therapy and use of more powerful medications. In people with arthritis of the knee, a seriously damaged joint may need to be surgically replaced with an artificial one. (Note: A new procedure designed to stimulate the growth of cartilage using a patient's own cartilage cells is being used experimentally to repair cartilage injuries at the end of the femur at the knee. It is not a treatment for arthritis.)

Ligament Injuries

Anterior and Posterior Cruciate Ligament Injury

What Are the Causes of Injury to the Cruciate Ligaments?

Injury to the cruciate ligaments of the knee is sometimes referred to as a "sprain." The anterior cruciate ligament is most often stretched, torn, or both by a sudden twisting motion (for example, when the feet are planted one way and the knees are turned another way). The posterior cruciate ligament is most often injured by a direct impact, such as in an automobile accident or football tackle.

What Are the Symptoms of Cruciate Ligament Injury? How Is Injury Diagnosed?

Injury to a cruciate ligament may not cause pain. Rather, the person may hear a popping sound, and the leg may buckle when he or she tries to stand on it. To diagnose an injury, the doctor may perform several tests to see if the parts of the knee stay in proper position when pressure is applied in different directions. A thorough examination is essential to the diagnosis. An MRI is very accurate in detecting a complete tear, but arthroscopy may be the only reliable means of detecting a partial tear.

How Are Cruciate Ligament Tears Treated?

For an incomplete tear, the doctor may recommend that the patient begin an exercise program to strengthen surrounding muscles. The doctor may also prescribe a protective knee brace for the patient to wear during activity. For a completely torn anterior cruciate ligament

in an active athlete and motivated patient, the doctor is likely to recommend surgery. The surgeon may reattach the torn ends of the ligament or reconstruct the torn ligament by using a piece (graft) of healthy ligament from the patient (autograft) or from a cadaver (allograft). Although repair using synthetic ligaments has been tried experimentally, the procedure has not yielded as good results as use of human tissue. One of the most important elements in a patient's successful recovery after cruciate ligament surgery is following an exercise and rehabilitation program for 4 to 6 months that may involve the use of special exercise equipment at a rehabilitation or sports center. Successful surgery and rehabilitation will allow the patient to return to a normal full lifestyle.

Medial and Lateral Collateral Ligament Injury

What Is the Most Common Cause of Injury to the Medial Collateral Ligament?

The medial collateral ligament is more easily injured than the lateral collateral ligament. It is most often caused by a blow to the outer side of the knee, which often happens in contact sports like football or hockey, that stretches and tears the ligament on the inner side of the knee.

What Are the Symptoms of Collateral Ligament Injury? How Is Injury Diagnosed?

When injury to the medial collateral ligament occurs, a person may feel a pop and the knee may buckle sideways. Pain and swelling are common. A thorough examination is essential to determine the nature and extent of injury. To diagnose a collateral ligament injury, the doctor exerts pressure on the side of the knee to determine the degree of pain and looseness of the joint. An MRI is helpful in diagnosing injuries to these ligaments.

How Are Collateral Ligament Injuries Treated?

Most sprains of the collateral ligaments will heal if the patient follows a prescribed exercise program. In addition to exercise, the doctor may recommend that the patient apply ice packs to reduce pain and swelling and wear a small sleeve-type brace to protect and stabilize the knee. A sprain may take 2 to 4 weeks to heal. A severely sprained or torn collateral ligament may be accompanied by a torn anterior cruciate ligament, which usually requires surgical repair.

Tendon Injuries and Disorders

Tendinitis and Ruptured Tendons

What Are the Causes of Tendinitis and Ruptured Tendons?

Knee tendon injuries range from tendinitis (inflammation of a tendon) to a ruptured (torn) tendon. If a person overuses a tendon during certain activities such as dancing, cycling, or running, the tendon stretches like a worn-out rubber band and becomes inflamed. Movements such as trying to break a fall may cause excessive contraction of the quadriceps muscles and tear the quadriceps tendon above the patella or the patellar tendon below the patella. This type of injury is most likely to happen in older people whose tendons tend to be weaker. Tendinitis of the patellar tendon is sometimes called jumper's knee. This is because in sports requiring jumping, such as basketball, the muscle contraction and force of hitting the ground after a jump strain the tendon. The tendon may become inflamed or tear after repeated stress.

What Are the Symptoms of Tendon Injuries? How Are Injuries Diagnosed?

People with tendinitis often have tenderness at the point where the patellar tendon meets the bone. They also may feel pain during faster movements, such as running, hurried walking, or jumping. A complete rupture of the quadriceps or patellar tendon is not only painful but also makes it difficult for a person to bend, extend, or lift the leg against gravity. If there is not much swelling, the doctor will be able to feel a defect in the tendon near the tear during a physical examination. An x ray will show that the patella is lower in position than normal in a quadriceps tendon tear and higher than normal in a patellar tendon tear. The doctor may use an MRI to confirm a partial or total tear.

How Are Knee Tendon Injuries Treated?

Initially, the doctor may ask a patient with tendinitis to rest, elevate, and apply ice to the knee and to take medicines such as aspirin or ibuprofen to relieve pain and decrease inflammation and swelling. If the quadriceps or patellar tendon is completely ruptured, a surgeon will reattach the ends. After surgery, the patient will wear a cast for 3 to 6 weeks and use crutches. If the tear is only partial, the doctor might apply a cast without performing surgery.

A partial or complete tear of a tendon requires an exercise program as part of rehabilitation that is similar to but less vigorous than that prescribed for ligament injuries. The goals of exercise are to restore the ability to bend and straighten the knee and to strengthen the leg to prevent a repeat knee injury. A rehabilitation program may last 6 months, although the patient can return to many activities before then.

Osgood-Schlatter Disease

What Are the Causes of Osgood-Schlatter Disease?

Osgood-Schlatter disease is caused by repetitive stress or tension on a part of the growth area of the upper tibia (the apophysis). It is characterized by inflammation of the patellar tendon and surrounding soft tissues at the point where the tendon attaches to the tibia. The disease may also be associated with an avulsion injury, in which the tendon is stretched so much that it tears away from the tibia and takes a fragment of bone with it. The disease most commonly affects active young people, particularly boys between the ages of 10 and 15, who play games or sports that include frequent running and jumping.

What Are the Symptoms of Osgood-Schlatter Disease? How Is It Diagnosed?

People with this disease experience pain just below the knee joint that usually worsens with activity and is relieved by rest. A bony bump that is particularly painful when pressed may appear on the upper edge of the tibia (below the knee cap). Usually, motion of the knee is not affected. Pain may last a few months and may recur until a child's growth is completed.

Osgood Schlatter disease is most often diagnosed by the symptoms. An x ray may be normal, or show an avulsion injury, or, more typically, show that the apophysis is in fragments.

How Is Osgood-Schlatter Disease Treated?

Usually, the disease disappears without treatment. Applying ice to the knee when pain first begins helps relieve inflammation and is sometimes used along with stretching and strengthening exercises. The doctor may advise the patient to limit participation in vigorous sports. Children who wish to continue participating in moderate or less stressful sports may need to wear knee pads for protection and apply ice to the knee after activity. If a great deal of pain is felt during sports activities, participation may be limited until any remaining discomfort is tolerable.

Iliotibial Band Syndrome

What Causes Iliotibial Band Syndrome?

This is an overuse inflammatory condition due to friction (rubbing) of a band of a tendon over the outer bone (lateral condyle) of the knee. Although iliotibial band syndrome may be caused by direct injury to the knee, it is most often caused by the stress of long-term overuse, such as sometimes occurs in sports training.

What Are the Symptoms of Iliotibial Band Syndrome and How Is It Diagnosed?

A person with this syndrome feels an ache or burning sensation at the side of the knee during activity. Pain may be localized at the side of the knee or radiate up the side of the thigh. A person may also feel a snap when the knee is bent and then straightened. Swelling is usually absent and knee motion is normal. The diagnosis of this disorder is usually based on the patient's symptoms, such as pain at the lateral condyle, and exclusion of other conditions with similar symptoms.

How Is Iliotibial Band Syndrome Treated?

Usually, iliotibial band syndrome disappears if the person reduces activity and performs stretching exercises followed by muscle-strengthening exercises. In rare cases when the syndrome doesn't disappear, surgery may be necessary to split the tendon so it is not stretched too tightly over the bone.

Other Knee Injuries

Osteochondritis Dissecans

What Is Osteochondritis Dissecans?

Osteochondritis dissecans results from a loss of the blood supply to an area of bone underneath a joint surface and usually involves the knee. The affected bone and its covering of cartilage gradually loosen and cause pain. A person with this disruption of the joint may eventually develop osteoarthritis. This disorder usually arises spontaneously in an active adolescent or a young adult. It may be due to a slight blockage of a small artery or to an unrecognized injury or tiny fracture that damages the overlying cartilage.

The bone undergoes avascular necrosis (degeneration from lack of a blood supply). 2 The involvement of several joints or the appearance of osteochondritis dissecans in several family members may indicate that the disorder is inherited.

What Are the Symptoms of Osteochondritis Dissecans? How Is It Diagnosed?

If spontaneous healing doesn't occur, cartilage eventually separates from the diseased bone and a fragment breaks loose into the knee joint, causing locking of the joint, weakness, and sharp pain. An x ray, MRI, or arthroscopy can determine the condition of the cartilage and be used to diagnose osteochondritis dissecans.

How Is Osteochondritis Dissecans Treated?

If cartilage fragments have not broken loose, a surgeon may fix them in place with pins or screws that are sunk into the cartilage to stimulate a new blood supply. If fragments are loose, the surgeon may scrape down the cavity to reach fresh bone and add a bone graft and fix the fragments in position. Fragments that cannot be mended are removed, and the cavity is drilled or scraped to stimulate new growth of cartilage. Research is currently being done to assess the use of cartilage cell transplants and other tissues to treat this disorder.

Plica Syndrome

Plica (pronounced PLI-KAH) syndrome occurs when plicae (bands of remnant synovial tissue) are irritated by overuse or injury. Synovial plicae are remnants of tissue pouches found in the early stages of fetal development. As the fetus develops, these pouches normally combine to form one large synovial cavity. If this process is incomplete, plicae remain as four folds or bands of synovial tissue within the knee. Injury, chronic overuse, or inflammatory conditions are associated with development of this syndrome.

What Are the Symptoms of Plica Syndrome? How Is It Diagnosed?

People with this syndrome are likely to experience pain and swelling, a clicking sensation, and locking and weakness of the knee. Because the symptoms are similar to symptoms of some other knee problems, plica syndrome is often misdiagnosed. Diagnosis usually depends on the exclusion of other conditions that cause similar symptoms.

How Is Plica Syndrome Treated?

The goal of treatment is to reduce inflammation of the synovium and thickening of the plicae. The doctor usually prescribes medicine such as ibuprofen to reduce inflammation. The patient is also advised to reduce activity, apply ice and compression wraps (elastic bandage) to the knee, and do strengthening exercises. If this treatment program fails to relieve symptoms within 3 months, the doctor may recommend arthroscopic or open surgery to remove the plicae. A cortisone injection into the region of the plica folds helps about half of the patients treated. The doctor can also use arthroscopy to confirm the diagnosis and treat the problem.

Other Sources of Information on Knee Problems

  • American Academy of Orthopaedic Surgeons
    6300 N. River Road
    Rosemont, IL 60018-4262
    World Wide Web address:

    The academy publishes several brochures on the knee, including Knee Arthroscopy” and Total Knee Replacement,” which doctors can obtain and give to their patients. Single copies of two other pamphlets, Arthroscopy” and Total Joint Replacement,” are available free to the public if a self-addressed, stamped envelope is provided.

  • American Physical Therapy Association
    1111 N. Fairfax Street
    Alexandria, VA 22314
    800/999-APTA (2782)
    World Wide Web address:

    The association has published a free brochure titled Taking Care of the Knees.”

  • Arthritis Foundation
    1330 Peach Tree Street
    Atlanta, GA 30309
    800/283-7800 or call your local chapter (listed in the local telephone directory)
    World Wide Web address: h

    The Foundation has several free brochures about coping with arthritis, taking nonsteroid and steroid medicines, and exercise. A free brochure on protecting your joints is titled Using Your Joints Wisely.” The foundation also provides doctor referrals.

  • American College of Rheumatology/Association of Rheumatology Health Professionals
    60 Executive Park South, Suite 150
    Atlanta, GA 30329
    Fax: 404/633-1870
    World Wide Web address:

    This national professional organization can provide referrals to rheumatologists and allied health professionals, such as physical therapists. One-page fact sheets are available on various forms of arthritis. Lists of specialists by geographic area and fact sheets are also available on ACR's web site.

  • National Arthritis and Musculoskeletal and Skin Diseases Information
    Clearinghouse (NAMSIC)

    National Institutes of Health
    1 AMS Circle
    Bethesda, MD 20892-3675
    Phone: 301/495-4484
    TTY: 301/ 565-2966
    World Wide Web address:

    The Clearinghouse has additional information about some of the knee problems described in this fact sheet, including osteoarthritis and avascular necrosis, as well as information about total knee replacement and arthritis and exercise. Single copies of fact sheets and information packages on these topics are available free upon request.

  *Brand names included in this fact sheet are provided as examples only, and their inclusion does not mean that these products are endorsed by the National Institutes of Health or any other Government agency. Also, if a particular brand name is not mentioned, this does not mean or imply that the product is unsatisfactory.


The NIAMS gratefully acknowledges the assistance of Frank A Pettrone, M.D., of Arlington/Vienna,Virginia; W. Norman Scott, M.D., of Beth Israel Medical Center in New York, New York; and James Panagis, M.D., M.P.H., and John H. Klippel, M.D., of the National Institutes of Health, in the preparation and review of this fact sheet.

The National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse (NAMSIC) is a public service sponsored by the NIAMS that provides health information and information sources. The NIAMS, a part of the National Institutes of Health (NIH), leads the Federal medical research effort in arthritis and musculoskeletal and skin diseases. The NIAMS sponsors research and research training throughout the United States as well as on the NIH campus in Bethesda, MD, and disseminates health and research information.

JW 9/97
Office of Scientific and Health Communications

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