Patello-Femoral Syndrome

This knee problem is quite common in runners. If a runner has mild to severe knee pain in a site other than the outside of the knee and they don't have any previous history of knee injury, it's a good guess that there's some degree of PFS contributing to the pain. The pain is usually described as being located around or under the knee cap. PFS is also one of the most mis-diagnosed running related injuries, so read on.

The Anatomy

Patello-Femoral Syndrome is a condition caused by the patella (knee cap) not tracking properly over the femur (thigh bone). The patella normally rides in a groove on the femur. The patella is really a fulcrum - it gives leverage to the big muscles on the front of the thigh. These thigh muscles are called the quadriceps - or quads for short. The quads are so named because they consist of four muscles. With PFS, you get an imbalance in these muscles - usually the lateral or outside muscle over-powers the inner medial muscle - and this pulls the patella out of it's normal groove. When the patella doesn't track properly in it's groove, it causes pain under the patella.

As I stated above, PFS is often mis-diagnosed. It's often mis-diagnosed as Chondromalacia Patellae. This is a chronic, degenerative condition that affects the underside of the patella. The underside starts to soften (malacia means soft) and when it rubs on the femur it causes pain. Chondromalacia Patellae is thought to be a sequelae of long term PFS. In other words, PFS may progress to Chondromalacia over time. Mis-diagnosis occurs when a complete examination is not performed. Because these two conditions present with almost identical signs and symptoms an x-ray is often necessary to differentiate between the two. A special view called a "Skyline" view of the knee will show the underside of the patella which allows us to look for softening of the cartilage. There's a classic presentation on x-ray called "Crab Meat Sign" (the cartilage starts looking like crab meat!) that is indicative of Chondromalacia Patellae. Chondromalacia Patellae is only truly diagnosed with a positive Crab Meat Sign on x-ray. If you've been told that you have Chondromalacia Patellae but you haven't had an x-ray, or the x-ray doesn't show the Chondromalacia Patellae, get a second opinion.

Now, with that said I should also state that conservative treatment for both PFS and Chondromalacia Patellae is essentially the same, however Chondromalacia Patellae may sometimes require surgery so you want to make sure you have the diagnosis correct before you let anyone cut into you're knee!!

Signs and Symptoms

What's Going On

The cracking that is often associated with PFS is the sound of the patella clunking back into it's groove. Pain is often aggravated by bending because this causes the most motion of the knee cap over the femoral groove.

For whatever reason, the lateral muscles of the thigh have gotten tighter or stronger than the medial muscles of the thigh. This may be due to a problem with the feet such as over-pronation or fallen arches, or it may simply be due to the muscle's natural response to an increase in training.

What To Do About It

If there is an underlying problem with the feet, that's something that should be addressed by a professional. It may, however, be as simple as changing running shoes. If the muscles are at fault you should be able to remedy the problem with a home stretching and exercise routine. Massage may also prove useful as a means of loosening up the tight outer quad muscle.

Here's what you can do for yourself, in a nutshell:

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