Running Injuries (Part 3) - Runner's Knee, Patellar Tendonitis, and Muscle Strains
Updated: Dec 9, 2019
Patellofemoral Pain Syndrome (PFPS), often called “Runner’s Knee”, is a very common injury among... you guessed it, running athletes. Pain is typically reported behind or around the top of knee while completing activities such as squats, stairs, prolonged sitting, and of course... running. This happens when the kneecap (patella) rubs against the femur causing irritation of the joint surfaces. It has long been believed to be due to a tracking issue caused by insufficient activation of the medial quadriceps muscle (Vastus Medialis Obliquus - VMO).
The patella’s primary role is to increase the leverage of the quadriceps tendon on the femur and thus facilitate more knee extension. It’s tracking path can be seen moving up and lateral during knee extension. The patella has a protective layer of cartilage which helps it glide along the femoral grooves. PFPS can progress to chondromalacia patella if this protective layer sustains actual damage.
Poor activation of the VMO was mentioned earlier as the frequently identified culprit but lets explore other possibilities before jumping to conclusions. Other common factors affecting poor tracking are: 1) quadriceps weakness, 2) tendon, ligament, and/or muscle are too tight or too loose, and 3) lousy biomechanics.
The quadriceps are innervated by the femoral nerve which consists of large motor units shared between the four quadricep muscles. Due to a lack of individual fine motor units, the VMO cannot be trained in isolation. Straight leg raises (SLR) are a good starting point for acute symptoms as it allows for immediate strength training while decreasing strain on joint surfaces by immobilizing the knee joint. In an attempt to isolate the VMO, programs would implement SLR in a hip externally rotated position with pretty good outcomes. Understanding the inability to actually isolate the VMO, decrease in symptoms should be attributed to an overall increase in quadriceps strength rather than improved VMO activation. My recommendation would be to complete standard straight leg raise as it places greater training stimulus on quadriceps.
While I am a big advocate for gaining mobility through your daily movements, dedicated stretching programs can definitely help alleviate knee pains. Hip flexor and quadriceps tightness seem to be the norm for many running athletes. Make sure you take the time to stretch the anterior chain. Tip: Maintain strong core activation during these stretches to avoid movement occuring at the spine instead of the hips/knees. Also, while foam rolling is a great way to decrease muscle tone and get a loose feeling, it is not a substitute for stretching.
Finally, biomechanics as often mentioned in my posts is huge. Due to differences in hip structure, women are predisposed to knee collapse during activities resulting in higher incidence of runner's knee. Needless to say, we all still need to consider this last one. Strengthening hip musculature to prevent hip drop and/or excessive internal rotation of the hip can help maintain proper mechanics during your run.
PFPS and Patellar Tendonitis are two separate conditions. While PFPS symptoms are often felt behind or on top of the kneecap, Patellar Tendonitis is felt below the kneecap. The patellar tendon (which is actually a ligament) connects the patella to the tibia. Due to the leverage created by the patella, as mentioned earlier, the quadriceps is able to generate more forceful movements about the knee joint. These increased forces ultimately pass along to the patellar tendon. Unlike many of the previously mentioned injuries, this is one that more commonly plagues male runners.
Much like with Achilles Tendonitis, the severity of the problems lies in the poor alignment of fibers after damage rather than the initial inflammation. This means a similar treatment approach can be implemented. Eccentric squats will load the patellar tendon in a manner which best stimulates proper orientation of fibers. Performing these squats on a 25 degree decline places greater strain on the tendon for optimal results. Work your way up in number of sets to reach 3 sets of 15 repetitions. Icing after activities is also recommended (freeze water in paper cup and tear off bottom of nice ice massage).
Tearing or overstretching of a muscle results in a muscle strain, or pulled muscle. Very high intensities or training on overly fatigued muscles can cause such injuries. Any muscle can be strained and typical symptoms include inflammation and weakness. If you feel a pop at onset or pain does not decrease after 48 hours it is probably time to go see your.
If someone told you they pulled their muscle running, most of us will immediately suspect the hamstring. Some might even dive into the hip adductors or calves. However, running requires muscles beyond those in our legs. Imagine if all other trunk muscles were shut off, we’d look like those giant air-filled mascots at your local car dealership flapping in the wind. In reality, we have to stabilize our lumbar spine and head, expand/compress our rib cage, counter balance leg swing with arm swing, etc.
It’s time for some good old R.I.C.E. (Rest, Ice, Compress, Elevate). You might feel like it needs to be stretched but don’t do it. After all, I did say this injury occurs due to overstretching a muscle. It’s probably best to allow 2-3 days for your body's inflammatory process to do it's thing but then include gradual warm-ups and avoid pushing through pain when returning to sport. Low grade strains are simple, just be patient and avoid making things worse.
As always, with any of these injuries consult with your healthcare provider to determine what will be best for you.
Next week we will cover Medial Tibial Stress Syndrome (Shin Splints) and Stress Fractures