Chondromalacia patella

Definition

Chondromalacia patella is the softening and breakdown of the tissue (cartilage) that lines the underside of the kneecap (patella).

It is a common cause of anterior knee pain.

Alternative Names

Patellofemoral syndrome; Knee pain - chondromalacia

Causes, incidence, and risk factors

Chondromalacia of the patella occurs in adolescents and young adults.

The condition is more common in females. It can be related to the abnormal position of the knee.

Your kneecap (patella) sits over the front of your knee joint. As you bend or straighten your knee, the underside of the patella glides over the bones that make up the knee.

Strong tendons help attach the patella to the bones and muscles that surround the knee. These tendons are called:

• The patellar tendon (where the kneecap attaches to the shin bone)
• The quadriceps tendon (where the thigh muscles attach to the top of the kneecap)

Problems begin when the kneecap does not move properly and rubs against the lower part of the thigh bone. This may occur because:

• The kneecap is in an abnormal position (also called poor alignment of the patellofemoral joint)
• There is tightness or weakness of the muscles on the front and back of your thigh
• You are doing too much activity that places extra stress on the kneecap (such as running, jumping or twisting, skiing, or playing soccer)
• You have flat feet

Chondromalacia of the patella can also be a sign of arthritis of the kneecap, which is usually seen in older people.

People who have previously had a dislocation, fracture, or other injury to the kneecap are more likely to develop chondromalacia.

Symptoms

• A grating or grinding sensation when the knee is flexed (moved so that the ankle is brought closer to the back of the thigh)
• Knee pain in the front of the knee that occurs when you get up after sitting for a long period of time
• Knee pain that worsens when you use stairs or get out of a chair
• Knee tenderness

Signs and tests

The doctor will perform a physical examination. The knee may be tender and mildly swollen, and the kneecap may not be perfectly lined up with the femur (thigh bone).

When you flex your knee, you may feel a grinding sensation below the kneecap. Pressing the kneecap when the knee is straightening out may be painful.

X-rays are usually normal, although a special x-ray view of the kneecap may show signs of arthritis or tilting.

Treatment

Temporarily resting the knee and taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, or aspirin may help relieve pain. Physical therapy, especially quadriceps strengthening and hamstring stretching, may be helpful.

Stretch the muscles on the back (hamstrings) and front (quadriceps) of your upper leg.

Your health care provider can teach you ways to make these muscles tighter. Stronger muscles will help hold your kneecap in the correct position.

If you need to lose weight, find out how.

Changing the way you exercise may help:

• Avoid running straight down hills; walk down instead.
• Bicycle or swim, instead of running.
• Reduce the amount of exercise you do.
• Run on a smooth, soft surface such as a track, rather than on cement.

Other techniques are:

• Special shoe inserts and support devices (orthotics) may help people with flat feet.
• Taping to realign the kneecap may help prevent symptoms.

Make sure your running shoes:

• Are made well
• Fit well
• Have good cushion

If the pain does not improve and there are signs of arthritis developing around the kneecap, surgery may be an option. Surgery may be done using:

• Arthroscopy (using a camera, which allows a smaller cut)
• An open approach, with a surgical cut

During the surgery, kneecap cartilage that has been damaged may be removed. Changes may be made to the tendons to help the kneecap move more evenly.

Support Groups

Expectations (prognosis)

Chondromalacia patella usually improves with therapy and use of NSAIDs. For the few people who need it, surgery is successful most of the time.

Complications

The main complication is failure of treatment to relieve pain.

When surgery is necessary, surgical complications may include:

• Failure to relieve pain
• Infection
• Worsening pain

Calling your health care provider

Call for an appointment with your health care provider if you have symptoms of this disorder.

Prevention

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References

May TJ. Persistent anterior knee pain. Am Fam Physician. 2007;76:277-278.

De Carlo M, Armstrong B. Rehabilitation of the knee following sports injury. Clin Sports Med. 2010;29:81-106.

Steiner T, Parker RD. Patella: subluxation and dislocation. 2. Patellofemoral instability: recurrent dislocation of the patella. In: DeLee JC, Drez D Jr., Miller MD, eds. DeLee and Dree's Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier;2009:chap 22:sect C.