What is Runner’s Knee?
Runner’s Knee, or patellofemoral pain syndrome, is an overuse injury that is categorized by pain around the kneecap. It is different to (and should not be confused with) IT Band Syndrome or Patellar Tendinopathy. The location of the pain is the most important factor in the different diagnoses, Runner’s Knee is always directly around or behind the kneecap, IT Band Syndrome is on the outside of the knee, and patellar tendinopathy is under the kneecap, towards the shin.
Runner’s Knee got its name because of how commonly it affects runners – stats indicate that 75% of diagnosed cases happen in runners and up to 15% of runners deal with the injury at some point in their running career. But despite being one of the most common injuries, it is often misunderstood and poorly treated because the scientific evidence explaining cause and pathology is still relatively new. Each year, researchers are learning more about why runners get this injury and clinicians are finding better ways of treating it. Although we still don’t have all the answers, we do now have a good understanding of what is going on.
Firstly, the pain of Runner’s Knee comes from inflamed tissues around the kneecap. These are things like fat, bursa, and connective tissue. A common misconception is that something is damaged in the knee, but this isn’t true. Runner’s Knee is not associated with wear-and-tear or any structural damage of the bones, ligaments, or muscles.
It is an injury of tissue irritation, not an injury of tissue damage.
This is important because recovering from Runner’s Knee isn’t dependent on waiting for something to ‘heal’ – nothing is broken, torn, or damaged in any way. Recovering from Runner’s Knee is more about dealing with the inflammation and addressing what caused the inflammation in the first place.
What Causes Runner’s Knee?
Inflammation that leads to the pain starts because of excess (more than usual) stress on the kneecap – for runners, this is usually correlated with an increase in training volume, whether it’s longer distances or faster speeds.
But not every runner who increases training volume gets Runner’s Knee. So, why are some people more prone to get the injury? While we don’t know for sure, we do have some strong theories.
For a long time, everyone thought it was because the kneecap in some people was tracking (moving) at an odd angle and rubbing along the femur. In this theory, the repetitive rubbing of the bones caused the inflammation. However, although some people with Runner’s Knee do have misaligned kneecaps, it is not as common as we thought and it certainly doesn’t explain every case. It’s also important to note that there are people who have misaligned kneecaps who never develop Runner’s Knee.
So while we cannot completely rule out this theory, it doesn’t seem to be the primary cause of Runner’s Knee.
Since moving away from that initial theory, clinicians and scholars now believe that Runner’s Knee is most likely caused by a general lack of ‘readiness’ in the tissues to deal with the new amount of stress.
Every tissue in the body has a certain amount of stress (or load) that it can handle. This can change over time depending on how we use our body. For example, someone who strength trains and gradually increases resistance will build up their muscle tolerance over time be able to lift heavier weight without injury. But this adaptation takes time, usually weeks or months. If there is a sudden increase in stress that goes beyond what the tissue can handle, it will get irritated and inflamed – this is what we think happens in Runner’s Knee.
This means that runners who are new to the sport, increasing volume quickly, or are weaker will be at the highest risk of developing Runner’s Knee.
The first step of Runner’s Knee rehab is to reduce inflammation and pain. Anti-inflammatory medications, ice, massage and rest will all help.
At this point, it’s also important to reduce the activity that’s causing the inflammation – in this case, running. Depending on how severe your injury is, and how many miles you tend to run, you will either need to take a complete break or significantly drop your training volume.
If you continue running during this phase of rehab, it should be kept to a distance that feels comfortable and pain-free. You should not have any exacerbation of symptoms either during the run, or the next day.
While you reduce the amount of running you do, you should continue training both your aerobic fitness (with cross-training activities such as swimming or cycling) and anaerobic fitness (with strength training) as long as these activities do not increase pain.
During the first stage of rehab, when you are focused on reducing pain and inflammation, it is important to continue training as much as possible with activities that do not exacerbate symptoms.
This is also when you should begin rehab strength training. Here is a sample of what your training week should look like during this first stage. *Note: if you continue running, substitute the cross-training/walking with running.
Strength training is key to recovering well from Runner’s Knee and getting back to your normal training routine.
There is a lot of strong evidence showing runner’s with patellofemoral pain have weakness in their hips, knees, and core and thus benefit greatly from strength training programs.
In the training schedule presented above, we have included four 20-30 minute strength sessions coinciding with our structured rehab program. Four strength sessions are ideal but understandably difficult to fit into a busy schedule for some. At the very least, runners dealing with Runner’s Knee should do a minimum of two strength sessions per week.
In the first stage of rehab, it’s necessary to cut back on your running or stop completely to allow pain & inflammation to settle down. In the second stage, once the pain is gone or at a minimum, you’ll begin re-introducing running and slowly increasing volume.
While there is no magic recipe for how to safely get back into your regular routine, there are a few rules general to follow:
1. Only run 3-4 times per week, allowing rest days in between each running session
2. Continue strength training and cross-training regularly (following a structured program).
3. Increase volume by small increments each week – no more than 10% per weekly mileage
4. If you notice pain or any symptoms returning, stop increasing volume and go back to the previous pain-free distance for 2 weeks before attempting to increase the volume again.
5. If you are unsure about any aspect of the rehab or your pain does not settle quickly, consult your Physiotherapist or sports doctor before continuing.
Esculier et al. 2016, Effects of Rehabilitation Approaches for Runners with Patellofemoral Pain: Protocol of a Randomised Clinical Trial Addressing Specific Underlying Mechanisms, BMC Musculoskeletal Disorders, 17, p. 5
Bolga et al. 2016, Pain, Function and Strength Outcomes for Males and Females with Patellofemoral Pain who Participate in Either a Hip/Core or Knee Based Rehabilitation Program, International Journal of Sports Physical Therapy, 11,p. 926-935