Patellofemoral Pain Syndrome
(Runner’s Knee)
Definition
The patella is the bone that makes the knee cap. Patellofemoral pain syndrome is a condition in which pain is felt under the kneecap. 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.
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. If you have knee or joint pain during activity, call your doctor.
Causes
There is no single cause for this condition. It can be due to a number of different factors or conditions, including:
- Malalignment of the knee joint—often caused by dysfunction in the feet. People who roll their feet out when they walk can 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—these muscles 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 that 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—rolling feet outward
- 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
Symptoms
The first symptom is pain around or under the kneecap. The pain may first occur during high-impact activities. As the condition gets worse, the pain may be triggered by long periods of sitting. 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
Diagnosis
Your doctor will ask about your symptoms and medical history. A physical exam will be done.
Images may be taken of your knee. This can be done with:
Your doctor may refer you to a specialist. Orthopedic surgeons focus on bone and joint disorders.
Treatment
The initial step is to rest the knee. High-impact activities should be switched for lower impact exercise. For example, choose swimming instead of running. 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 muscles in the thigh as well as other muscles near the hip. 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). 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 work best when the condition is due to dysfunction in the foot, such as flat feet or excessive pronation.
Surgery
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.
Prevention
It may not be possible to totally prevent this condition. There are steps you can take to reduce your risk and avoid making the condition it worse, including:
- 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 right away. This includes getting first aid and resting the injury until it is healed before beginning an activity again.
RESOURCES
American Academy of Family Physicians
http://familydoctor.org
American Academy of Orthopaedic Surgeons
http://orthoinfo.aaos.org
The President’s Council on Fitness, Sports, and Nutrition
http://www.fitness.gov
CANADIAN RESOURCES
Canadian Orthopaedic Association
http://www.coa-aco.org
Health Canada
http://www.hc-sc.gc.ca
References
Browner BD et al. Skeletal Trauma: Basic science, management, and reconstruction. 4th ed. Philadelphia, PA: Elsevier, 2008.
Canale, ST, ed. Campbell's Operative Orthopaedics. 11th ed. St. Louis, MO: Mosby, 2007.
DeLee, JC and D. Drez. DeLee and Drez’s Orthopaedic Sports Medicine. 3rd ed. Philadelphia, PA: Saunders, 2009.
Juhn MS. Patellofemoral pain syndrome: a review and guidelines for treatment.
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