Diseases & Conditions

Anterior Knee Pain - Chondromalacia Patellae


Overview, Causes, & Risk Factors

Chondromalacia patella (CMP) is a syndrome involving discomfort at the front of the knee. It is associated with irritation or wear on the underside of the kneecap, or patella.

What is going on in the body?

Normally, the cartilage on the underside of the kneecap glides smoothly over the surface of the thighbone, or femur. The cartilage may become soft or rough due to the normal aging process, overuse, or injury.

What are the causes and risks of the condition?

Possible causes of CMP include:

  • overuse of the knee, such as running or exercising beyond tolerance
  • increased pressure between the kneecap and thighbone, such as deep knee bending
  • bruising or fracture of the kneecap
  • lack of alignment of the legs, with knock knees. A person with knock knees has an inward curving of the legs so that the knees touch.
  • improper tracking of the kneecap due to a complete or partial dislocation
  • outward rotation of the lower leg in relation to the thigh

  • Symptoms & Signs

    What are the signs and symptoms of the condition?

    Symptoms include pain on the front of the knee, particularly during stair climbing. The pain may also occur after the person has been sitting for too long, squatting, or exercising. Sometimes a feeling of stiffness of the knee or buckling can occur.

    Signs include clicking or rubbing of the kneecap that can be felt by a healthcare provider during bending and straightening of the knee. There may be tenderness around the kneecap, especially in the lower, inside area. Sometimes there is limitation of or pain during knee flexing.


    Diagnosis & Tests

    How is the condition diagnosed?

    Diagnosis is based on frequency of symptoms and confirmed by signs. Wear can be shown on joint x-rays of the knee. It can also appear on an MRI, although this type of scan is not routinely performed for this purpose.


    Prevention & Expectations

    What can be done to prevent the condition?

    A person should avoid overuse, obesity, deep knee bends or squats, or repetitive pressure on the knee. Sports safety guidelines for adults, adolescents, and children are designed to help prevent this type of condition.

    What are the long-term effects of the condition?

    There are usually no long-term effects. Rarely, this condition can lead to arthritis of the knee.

    What are the risks to others?

    There are no risks to others.


    Treatment & Monitoring

    What are the treatments for the condition?

    Treatment involves exercises to decrease the pressure between the knee and thighbone and strengthen the thigh muscles. Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, are used to decrease pain and swelling. Arch supports within sneakers can help runners keep the legs well aligned. Sometimes a knee brace is helpful. Surgery is rarely necessary.

    What are the side effects of the treatments?

    NSAIDs have the potential for stomach upset or liver or kidney damage. Symptoms may continue after surgery.

    What happens after treatment for the condition?

    Treatment is generally successful. After treatment, it is important to avoid further joint strain and and maintain strength of the thigh muscle.

    How is the condition monitored?

    Any increased swelling and pain, knee dislocation, and other symptoms should be reported to a healthcare provider.


    Attribution

    Author:John A.K. Davies, MD
    Date Written:
    Editor:Planko, Christa, MA
    Edit Date:05/02/00
    Reviewer:Eileen McLaughlin, RN, BSN
    Date Reviewed:09/04/01