By Jonathan Chu, MD
Interventional Pain Medicine
PM&R

So, let’s talk about Runner’s Knee, one of the most common causes of knee pain. So common in fact, that it’s been estimated that at any given time, almost 6 percent of the adult population in the United States is suffering from it.

Now Runner’s Knee is the colloquial term for the condition, but the medical term is Patellofemoral Pain Syndrome.

Now it’s a big term, but let’s break it down, because it explains pretty much exactly what this condition is.

Patella refers to the knee cap, or the bone right in front of your knee.

Femur refers to your large thigh bone.

Thus, patellofemoral refers to the joint compartment in the front of your knee, where your kneecap articulates with the cartilage of the femur, in a large groove known as the trochlea of the femur.

Thus, patellofemoral pain syndrome thus refers to pain arising from this joint in the front of your knee, which usually presents as pain either underneath your kneecap, or around your knee cap.

Typically, patellofemoral pain syndrome is an overuse injury, and usually occurs after a period of excessive running, going up and down stairs, and squatting. Due to anatomical differences between men and women, it is slightly more common in women, since they tend to have a little more valgus morphology to their knees, meaning their knees tend to have a little more inward bowing, which makes sense since women tend to have relatively wider hips.

Another major risk factors for this condition are weakness of weakness of the quadriceps muscle, which is the really big and powerful muscle in the front your thigh. The last main risk factor is something known as patellar instability, which means that the knee cap is less stable than normal, usually because of muscular weakness or weakness of the surrounding ligamentous structures.

In terms of presentation, Patellofemoral Pain Syndrome typically presents as pain around the front of the knee, either around or beneath the knee cap, worse with flexing the knee and with squatting. Often, the pain and stiffness is also worsened by prolonged sitting, since the knee is fixed in a flexed position for a long time in that scenario. Sometimes, with this condition, the knee can even buckle and give out intermittently, though this is a lot less common.

Now let’s talk about your physical examination. According meta-analyses, one of the most sensitive tests for patellofemoral pain syndrome is when your pain reproduced by squatting. Another test that I personally like to use a lot is the Clarke’s test, which is also known as the patellar grind test, with a slight variation being referred to as the patellar compression test. With this test, your physician will place some pressure on the upper part of your patella and ask you to contract your quadriceps muscle; if the pain is reproduced, this is a positive test, which would provide supporting evidence for the diagnosis of patellofemoral pain syndrome.

Imaging

Next, as far as imaging goes, it x-rays and MRI are not really that useful in the diagnosis of Patellofemoral Pain Syndrome, as it is really much more of what you would call a clinical diagnosis, and depends mostly on your history and physical. Really, imaging in this clinical scenario is actually most important for ruling out other potential diagnoses and causes of pain.

Treatments

Now, if you’ve been diagnosed with Patellofemoral Pain Syndrome, the next question becomes, what do you do about it?

As with most pain conditions, the first step is to control the inflammation and pain.

And so for most people, that would of course entail relative rest, which means minimizing or eliminating the activities that exacerbate the pain. For example, if you notice that running worsens your symptoms, then it would make sense to greatly reduce your mileage, or if the pain is severe, taking a break from running completely. Now, this does not mean eliminating all activity, as most of the literature recommends that you continue to stay as active as possible, with exercises that do not exacerbate the pain, and easy examples might be walking or swimming.

Additionally, applying ice can also be a good option in the early stages. If you do not have stomach or kidney problems, a short course of non-steroidal anti-inflammatory medications, such as naproxen or ibuprofen for one or two weeks, can also be helpful. If ice and non-steroidal anti-inflammatory medications are not effective enough in controlling the inflammation and pain, another option is a steroid injection to the knee. It’s a very simple an easy procedure, and I’ve done many hundreds of them, both with and without ultrasound guidance, and they tend to be very effective in properly selected patients. Now, steroids do have some side effects, including temporarily raising blood sugar and blood pressure, so depending on your past medical history, you may or may not be a candidate for an injection, and so you can talk to your doctor about the risks and benefits, and whether it would be a good option for you.

Now, of course, after you get the pain under decent control initially, the most important aspect of treatment for this condition is physical therapy, which will focus on strengthening of the quadriceps muscle, as well as nearby supporting musculature, including the hip and core, in addition to stretches for those muscle groups as well. Hamstring tightness, in particular, has been associated with increased patellofemoral pain, so that’s likely a muscle group that your therapist will help you work on, in terms of stretching. There is some limited evidence that there can be some benefit from kinesiotaping for the knee, which can temporarily help to improve the tracking of the patella. There are also some knee braces that perform a similar function. However, of course, for both taping and bracing, there isn’t a ton of evidence supporting their use, but if you personally find it helpful, they could be a useful part of your overall treatment plan. Lastly, if all conservative treatments fail, there is also the option of surgery; however, in the vast majority of cases, this really isn’t necessary, and patellofemoral pain syndrome will improve with conservative measures alone.

I know that it’s a lot of information and pain conditions can be overwhelming to deal with, but hopefully you found the video valuable and it made patellofemoral pain syndrome less intimidating for you. Take care until the next video.

References:

Benzon, H. T., et al. (2018). Essentials of pain medicine (4th ed.). Elsevier.

Braddom, R. L. (Ed.). (2010). Physical medicine and rehabilitation (4th ed.). Saunders/Elsevier.

Cuccurullo, S. J. (2004). Physical medicine and rehabilitation board review. Demos Medical Publishing.

Gaitonde, D. Y., Ericksen, A., & Robbins, R. C. (2019). Patellofemoral pain syndrome. American Family Physician, 99(2), 88-94.