Patellofemoral syndrome

Alternative names
Chondromalacia patellae; Anterior knee pain

Definition
Chondromalacia patellae is the softening and degeneration of the cartilage beneath the kneecap (patella).

Causes, incidence, and risk factors

Chondromalacia patella that occurs in adolescents and young adults is thought to be related to overuse, trauma, and/or abnormal forces on the knee. It is more common in females. Many affected adolescents have a mildly abnormal alignment of the kneecap.

Chondromalacia patella may also reflect arthritis of the kneecap, which is usually seen in older individuals.

People who have previously had a dislocation, a fracture, or other trauma to the kneecap may be more likely to get chondromalacia.

Symptoms

     
  • Knee tenderness  
  • Knee pain in the front of the knee that worsens after sitting for prolonged time  
  • Knee pain that worsens with using stairs or getting out of a chair  
  • A grating or grinding sensation when the knee is extended

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) underneath.

When the knee is extended from the flexed (bent) position, a grinding sensation may be felt below the kneecap. With the knee extended (straight), pressing the kneecap against the femur may be painful.

X-rays are usually normal, although a special X-ray view of the kneecap may show arthritic changes.

Treatment

Temporarily resting or immobilizating 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.

Participation in sports or strenuous activity should be limited until the pain has gone away. Activities that increase the knee pain, such as deep knee bends, should be avoided until the pain improves.

If the alignment of the patella that cannot be corrected with therapy, surgery may be an option. Depending on the nature of the misalignment, the surgery may be arthroscopic (using a camera, which allows a smaller incision) or open.

Expectations (prognosis)

Chondromalacia patella usually improves with therapy and use of NSAIDs. For the few people who need it, surgery is successful about 90% of the time.

Complications

The primary complication is failure of treatment to relieve pain.

When surgery is necessary, surgical complications may include infection, failure to relieve pain, and worsening pain.

Calling your health care provider

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

Prevention

Avoid trauma or abnormal stress on the knee. Keep the leg muscles strong and flexible, especially the quadriceps and the hamstrings.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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