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Anterior Knee Pain, Part I: What Causes Knee Cap Pain?

Knee pain. Nobody likes it, and anybody dealing with it wants to know how to get rid of it!

What I’m talking about specifically is pain in the front of your knee. It’s called anterior knee pain, or patellofemoral pain (PFP) if you want to be anatomically correct. Anterior means the front side of your body; and patellofemoral refers to the joint where your knee cap (patella) and thigh bone (femur) come together and make your knee.

This pesky pain often comes on without a specific injury and the pain is poorly defined in the front of the knee (either front or back surface of the knee cap or off to the inside). It affects 1.5%-7.3% of all people seeking medical care. That may not sound like a lot, but that can be a rather substantial portion of people if you think of how many people seek medical care every day! Patellofemoral pain is most aggravated with activities that put a lot of force through the knee, such as stair climbing, squatting, jumping, or running. At least half of people experiencing PFP also can get increased pain after sitting for prolonged periods.

Does this sound like you? If so, read on.

The Journal for Orthopedic & Sport Physical Therapy (JOSPT) just published a major article about PFPS in September. It’s a great contribution to the field of Physical Therapy because the authors looked at the highest quality evidence between 1960 and 2018 on the topic and then dwindled it down to the most important, pertinent information so that physical therapists and patients have the most up-to-date, effective knowledge on how to treat this impairment. This publication acts as a guideline for clinical practice.

This is a two-part blog discussing anterior knee pain, and here in Part I is the breakdown from that article of what causes this pain in the front of the knee.

So, what exactly causes anterior knee pain?

The short of it is there are multiple possibilities that may cause this pain. Here are four primary reasons researchers of this article found:

  • Muscle weakness- Particularly, the front thigh muscles (quadriceps) are the guilty party on this one. Researchers consistently found that if there was a strength deficit in the involved limb, it was often these muscles. There have also been studies suggesting that this anterior knee pain causes hips to become weak. So while hip weakness in and of itself may not cause the knee pain, it’s a result and still something to address during rehab.

  • Muscle tightness- Consistently people with tighter leg and hip muscles were the same study participants who had anterior knee pain.

  • Poor mechanics- Sometimes it’s less-than-optimal angles at the knee with jumping or stair climbing that can be the reason there is knee pain because these mechanics generate more force than usual. This will be more challenging to discern by yourself but certainly something your physical therapist will assess if you seek care for this in a PT clinic.

  • Overuse or overloading the joint- Sometimes it’s just too much force demand through that joint, too suddenly all at once, that causes the anterior knee pain. This is very prevalent with military recruits at boot camp, just as one example. Anterior knee pain is a common ailment for these individuals when the physical demand on their body is suddenly ramped up significantly. Once the physical demand is lessened and treatment is sought, symptoms tend to resolve.

Clearly there are multiple factors that can cause PFP, and all may be relevant to certain degrees. If any of these symptoms describe pain you experience for yourself, stay tuned for Part II to see how you can help yourself resolve this anterior knee pain.

Also, know that you can always go see your local physical therapist, who can assess what is causing your pain specifically to help you get on the right track to healing. Either way, know that you don’t have to live with this pain and you can do something to change it.

Do you have questions or comments about anterior knee pain? Leave a comment below. I'd love to hear from you!


The reference for this information is: Journal of Orthopaedic & Sports Physical Therapy, 2019 Volume:49 Issue:9 Pages:CPG1–CPG95 DOI: 10.2519/jospt.2019.0302

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