Common Running Injuries: Runner’s Knee
by Tim Waanders, PT, DPT
Many people have heard the term “runner’s knee” before, and you may have experienced it for yourself a time or two. But what actually is runner’s knee? Why is this so common in runners? And most importantly, how do you treat it?
“Runner’s knee” is another term for patellofemoral pain syndrome (PFPS), which is a broad umbrella term for any pain of or surrounding the knee joint that does not generally have any structural cause such as ligament damage or osteoarthritis. In fact, ‘runners knee’ is the most prevalent injury in the running community, with some studies showing up to 30% of runners have experienced runner’s knee at some point. Besides running, any activity that loads the knee joint can cause pain, such as squatting, jumping, climbing stairs, and even sitting for a long period of time.
What causes Runner’s Knee?
As is common with many injuries, especially running-related injuries, there can be a number of factors or combinations of factors that can be attributed to the resulting injury which is why it may be so common. Runner’s knee is most often associated with a misalignment of the patella (aka the kneecap) as the knee moves, which can be due to biomechanical issues, muscular imbalance, poor flexibility, or simple overuse.
Often, excessive adduction and internal rotation of the femur when the foot lands on the ground during gait can be the main biomechanical factor playing a role in the onset of runner’s knee. Basically, as the foot hits the ground, the knee collapses inward toward the midline of the body, which places the joint at too much of an angle. It is also common for the opposite side hip to drop down too much, which again places excessive force into the knee of the leg that is landing on the ground.
Studies also show that strength imbalances in the hip musculature can be a contributing factor in runner’s knee. The muscles most commonly implicated include the quadriceps, which work to straighten the knee, as well as the hip rotators/abductors such as the gluteal muscles, which work to control the forward motion of the lower extremity during gait. If the hip muscles are not sufficiently strong enough to control the motion of the extremity below it, it can lead to the “collapsing” in of the knee as mentioned above.
Poor muscle flexibility can also be a major factor in runner’s knee onset. If the hip flexors/quadricep group are too inflexible, it can compress the patella and pull it too far back which can lead to pain in and around the knee. This can also be true with the TFL/ITB complex, which can pull the patella too far laterally (aka to the outside) and cause the knee to track wrong – leading to pain. The cause may also be from the bottom up, meaning the ankle could be contributing to the runner’s knee onset, not just the hip. Poor ankle dorsiflexion could lead to compensation at the knee by collapsing inward in order to allow the body to continue its forward momentum. Whether the cause is from the ankle joint itself or shortened/tight calf muscles can be determined by your physical therapist’s assessment.
It is also important to note that as runners, we need to make sure we are training properly and preventing overuse syndromes by increasing our mileage or speed slowly and making sure we are not overdoing it on uphill/downhill running. Proper recovery time and strategies (i.e. adequate sleep, nutrition, etc.) are also important.
How is Runner’s Knee treated?
Since there are clearly many different ways that can cause runner’s knee, treatment of it will be based on those contributing factors and what your body needs. The first goal in any rehabilitation plan should be to reduce pain severity. Soft tissue work of the quads and patellar tendon, as well as light joint mobilization can help modify the pain response surrounding the knee. At home this can be achieved via foam rolling or other forms of self massage, but can be a part of your therapy routine in the clinic.
Gaining proper mobility through active or dynamic stretching would be the next step. Depending on where there is a loss of flexibility will determine what muscle or muscle groups need to be stretched. As mentioned previously, most often the quadriceps or other hip flexors, the TFL/ITB complex, or even the calf muscles may need to be stretched in order to improve hip, knee, and ankle range of motion.
Strength and stability surrounding the knee will be the major factor that needs improvement, once symptom reduction allows this to occur. Quadricep, hamstring, and glute/hip rotator strength need to be the focus in order to help control the knee during active movement like running or jumping. Moving from double leg to single leg exercises in more functional patterns will be necessary not only to strengthen the muscle groups further, but also to train the brain and nervous system to have better control in these positions. This can include gait retraining in order to prevent collapsing inward of the knee when running as well as plyometric exercises that teach the body how to absorb and properly reuse ground reaction forces.
If you are currently having issues with runner’s knee, reach out to us and we’ll get you in touch with one of our physical therapists for a proper assessment and rehabilitation program that fits your needs!