Patello-Femoral Stress Syndrome


Patello‐femoral stress syndrome (PFSS) is a common cause of pain in the font of the knee. It is also called anterior knee pain syndrome or runner’s knee. PFSS is an overuse injury, which means it develops over a period of time and does not occur with one specific event. The knee joint includes the thigh bone (femur), kneecap (patella) and shin (tibia). During walking and running, the quadriceps (anterior thigh muscle) pulls the kneecap over the end of the thigh bone. In PFSS, irritation or stress develops because of the repeated pressure between the kneecap and thigh bone during activities.

How does PFSS develop?

There are many factors that may make a person more likely to develop this problem. Some of these include knock‐knees (genu valgus), flat feet (pes planus), tight hamstrings and weak quadriceps. PFSS may also develop in individuals who participate in activities for which they are not properly trained. An example of this is an athlete who “does too much, too soon” by trying to run longer distances or train at a higher intensity than he is physically prepared for. Other factors that may contribute to PFSS are running in shoes that are worn out or do not have enough arch support, cushioning or heel counters.

People with PFSS usually have intermittent, aching knee pain around or under the kneecap. The pain is worsened by activities like running or walking on stairs. After sitting for a long time, the knee may feel very stiff. Sometimes the knee may be weak and feel like it will buckle or collapse. PFSS does not usually cause the knee to swell.

Are X‐rays necessary?

Your doctor may want to X‐ray your knee to confirm the injury diagnosis or rule out other possible causes of your knee pain. People with PFSS usually have normal X‐rays.

What can be done to treat my PFSS?

There are many ways to treat and improve your PFSS. Start by modifying your activities and avoid doing anything that immediately worsens your pain. If you are a runner, cut back on how far you run or change your route to avoid hills and hard surfaces. Have your doctor examine your running shoes to check for the amount of wear and support remaining. You can wear a brace, strap or sleeve designed to stabilize the kneecap and provide additional relief. Physical therapy can also help reduce or eliminate your knee pain by properly exercising your quadriceps and hamstrings.

Another way to treat your PFSS is to apply an ice pack to the front of your knee. Doing this provides immediate relief, especially right after an activity that has worsened your knee pain.  For more relief, apply an ice massage by freezing a foam cup of water and then tearing off one inch around the cup’s rim to create a frozen snow cone. Apply this cone of ice directly to the sore area in a circular motion for about 10 to 15 minutes, until the area becomes numb. You can repeat this ice massage every 60 to 90 minutes, up to several times a day.

Anti‐inflammatory medications may also help relieve your knee pain and inflammation. Your doctor may suggest an over‐the‐counter medicine, such as ibuprofen or naproxen, or he may prescribe a medicine for you. Take anti‐inflammatory medicine for 10 to 14 days to allow the medicine to build up to therapeutic levels in your body. If you take the anti‐inflammatory medicine infrequently, the level of medicine in your system will drop and its effectiveness will decrease.