The patella is the bone that makes the knee cap. Patellofemoral pain syndrome is a condition in which pain is felt under the kneecap. This pain occurs during exercise or movement. It is most common during weight bearing activities such as running. It is often increased by going down stairs or down hills.

It is caused by abnormal movement of the patella. As the leg extends and flexes, the patella normally moves both up and down, and tilts slightly. It should not touch the other bones of the knee.

The femur is the thigh bone. This bone forms the upper part of the knee. In people with patellofemoral pain syndrome, the patella painfully rubs against the femur. If you have knee or joint pain during activity, call your doctor.

The Kneecap

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There is no single cause for this condition. It can be due to a number of different factors or conditions. These conditions include:

  • Malalignment of the knee joint—often caused by dysfunction in the feet. People who pronate (roll their feet out) when they walk pull the kneecap out of line. This causes painful rubbing of the kneecap against the bones of the knee. Rarely, this condition occurs because the kneecap is located too high or too low in the knee joint.
  • Weak anterior thigh muscles (quadriceps)—help to hold the kneecap in place as it moves. If these muscles are weak, they cannot hold the kneecap in the correct position. This causes the kneecap to rub against the femur during movement.
  • Overuse and overloading the knee joint—especially from high-impact sports or activities can cause pain.

Risk Factors

The following factors increase your chance of developing patellofemoral pain syndrome:

  • Any condition that causes misalignment of the knee joint, such as:
    • Flat feet]]>
    • High arches
    • Hip dysfunction
    • Pronation when walking
    • External rotation of the lower leg
    • Knock knees
  • Participation in high-impact sports, such as running
  • Trauma, such as an automobile accident where the kneecap hits the dashboard



The first symptom is pain around or under the kneecap. The pain may first occur during high-impact activities. This includes playing sports or going down stairs. As the condition gets worse, the pain may be triggered by long periods of sitting. This is sometimes called movie-goer’s sign. It is thought to be caused by the pressure on the kneecap while the leg is flexed. Other symptoms include:

  • Swelling of the knee
  • Popping or grinding sounds in the knee joint during activity
  • A snapping sensation in the knee

These symptoms may be caused by other, less serious health conditions. If you experience any one of them, see your physician.


Your doctor will first ask about your symptoms. A medical history will also be taken. To rule out other disorders, your doctor may want you to have the following tests:

  • X-ray of the knee joint
  • CT]]> or ]]>MRI]]> scan of the knee joint

Your doctor may refer you to a specialist. Orthopedic surgeons focus on bone and joint disorders.



The initial step is to rest the knee. High-impact activities should be switched for lower impact exercise. For example switch running for swimming. Your doctor may suggest that you apply ice to the kneecap after activity.

Longer term treatment involves a number of different strategies, including:

Exercise and Physical Therapy

Most people will benefit from strengthening the muscles around the knee. This includes the quadriceps muscle. It runs down the front of each thigh. Physical therapists can recommend specific exercises. This treatment is very helpful. It can take 6 to 12 weeks to see an improvement.

Pharmacological Treatment

Some people may benefit from nonsteroidal anti-inflammatory agents (NSAIDs). These may include Motrin]]> and Advil. They may be helpful in relieving the pain. They work best when combined with other treatments, such as physical therapy.

External Devices

Many people find relief from knee braces or knee sleeves. These devices typically have a cut-out in the knee cap area. They are designed to hold the kneecap in place during activity. Some are designed to hold the patella from going too far laterally.

Certain methods of taping the patella in position have also been helpful to many patients.

Special shoe inserts, called orthotics, may also be helpful. They are most helpful when the condition is due to dysfunction in the foot (as in flat feet or excessive pronation).


In rare cases, people who do not respond to other forms of treatment may be recommended for surgery. This will be done to correct malalignment of the patella.


It may not be possible to totally prevent the development of this condition. There are steps you can take to reduce your risk and avoid making the it worse. These measures include:

  • Proper warming up before exercising. This includes stretching after warm-up and post-activity. This will help to prevent sports-related injuries.
  • Vary the types of activities that you participate in. For example, rather than running or jogging every day, alternate between running and swimming.
  • Take care of injuries immediately. This includes getting first aid and resting the injury until it is healed before beginning an activity again.