Runner’s Knee: Symptoms, Causes and Rehab
What is Runner’s Knee?
Runner’s Knee, or patellofemoral pain syndrome, is an overuse injury with pain around the kneecap.
Runner’s Knee is sometimes used as a blanket term to describe all knee pain in runners, but it’s important to note that Runner’s Knee is a specific type of knee injury and it is different to IT Band Syndrome or Patellar Tendinopathy. One way to differentiate between these injuries is by the location of pain. Runner’s Knee pain is always at the front of the knee, directly around or behind the kneecap. IT Band Syndrome is always on the outside of the knee, and Patellar Tendinopathy is below the kneecap, towards the shin bone.
Runner’s Knee is very common and while it is not exclusive to runners, about 75% of all cases happen in runners (the other 25% tends to be in other active people participating in sports like cycling and hiking). Among runners, thousands of people are diagnosed every year with stats showing that up to 15% of all runners deal with the injury at some point in their running career.
Although Runner’s Knee is very common, we still don’t know the exact cause and pathology of the injury. This is mostly due to the fact that Runner’s Knee pain isn’t a simple injury, meaning that it isn’t associated with a particular structure being damaged, torn or broken. If you do an X-ray or an MRI, you won’t see anything that would explain the pain. This is frustrating, but not uncommon. Many injuries and painful conditions in the body are complex and cannot be pinpointed to a particular ‘hurt’ structure.
The best explanation we have of Runner’s Knee at the moment is that the pain is coming from inflamed, or irritated tissues around the kneecap (patella). These “tissues” are things like bursa, fat, synovial membrane and connective tissue. In other words, 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 instead all about dealing with the inflammation and addressing the cause of that inflammation.
So, What Causes The Inflammation?
It all starts with excess stress on the kneecap. Every tissue/structure in the body has a certain amount of stress (or load) that it can handle before it starts to break down. Depending on how we use our body on a regular basis, our tissues adapt to handle our ‘typical’ stress. If we suddenly start doing more without giving our body time to adapt, tissues get overworked, inflamed and eventually injured.
For runners, ‘doing more’ usually correlates with increasing distance or training more frequently. This results in much more repetitive stress on the kneecap.
However, not every runner who increases training volume gets Runner’s Knee. So, why are some people more prone to getting the injury?
For a long time, everyone thought it was because the kneecap tracked or moved at an odd angle and rubbed against the femur. In this theory, the repetitive rubbing of the bones caused 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 but never develop Runner’s Knee.
So while we cannot completely rule out this theory, it doesn’t seem to be the sole cause of the injury.
The more likely theory is that Runner’s Knee is caused by a general lack of ‘readiness’ as well as weakness and muscle imbalance.
Runners who have weak glutes, core and quads have a higher risk of getting Runner’s Knee because they allow more strain to be placed across the kneecap. And, the injury tends to occur only on one side, indicating that there are imbalances in the stress between the left and right leg.
Before fixing the weaknesses, the first stage of rehab is settling down the inflammation and reducing pain. Medications, ice packs, and massage will help, but the most effective thing you can do is rest and avoid activities that flare up the injury.
For some, this means taking a complete break from running. If your knee gets sore with even short, slow runs, you will need to stop running for a couple of weeks.
However, if your injury is less severe and you’re only getting pain during longer runs, you may be able to continue some running but decrease your distance and speed to avoid aggravating the injury. The most important thing at this stage is to allow the inflammation to settle down and avoid anything that will flare it up further.
Runners with patellofemoral knee pain usually have weaknesses in their quads, glutes, and core which contribute to the excess stress on the knee joint.
There are lots of studies now showing that a structured strength training program is necessary in treating Runner’s Knee. People who participate in strength training not only recover quicker but also reduce their risk of getting the injury again in the future.
Rehab strength programs for Runner’s Knee need to include exercises for the quads, glutes, core, and hamstrings, plus balance and stability training. These programs should be created by a Physiotherapist or rehab trainer and include weekly progressions specific to your running goals.
Getting Back to Running
Once the pain & inflammation have settled, you can start gradually increasing your running training. Start slow, and conservative. The key here is to increase volume in small increments giving your body plenty of time to recover and adapt. Include rest days after every run and increase distance by no more than 10% each week. Remember it takes time for the tissues to adapt, and rest days are when they rebuild and get stronger.
As a general rule, run only 3 times per week – one long run, one speedwork/track run, and one tempo run. Plus, continue strength training and cross-training as supplemental workouts between the runs.
Getting back to running after an injury isn’t always straight-forward and simple. There may be days or weeks where you feel defeated and frustrated. Some weeks you might need more rest and recovery time. That’s okay. Prepare to play the long game. Steady improvements over time are what matter, if you listen to your body and rest when you need, you will reach your goals quicker than if you push yourself too much.
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Gulati et al. 2018, Current Clinical Radiological, and Treatment Perspectives of Patellofemoral Pain Syndrome, British Journal of Radiology, 91, p.1086
Dutton et al. 2016, Patellofemoral Pain, Physical Medicine and Rehabilitation Clinics in North America, 27, p. 31-52
Dye. S 2005, The Pathophysiology of Patellofemoral Pain, Clinical Orthopedics and Related Research, 436, p. 100-110
Neal et al. 2019, Risk Factors for Patellofemoral Pain: a Systematic Review and Meta-Analysis, British Journal of Sports Medicine, 53, p. 270-281
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
Earl-Boehm et al. 2018, Treatment Success of Hip and Core or Knee Strengthening for Patellofemoral Pain: Development for Clinical Prediction Rules, Journal of Athletic Training, 53, p. 545-552
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
ABOUT ALINA KENNEDY
Alina is an Australian Physiotherapist, Strength & Conditioning Specialist and avid runner. She works exclusively with runners in injury rehabilitation, prevention and performance improvement. Learn More Here