Keeping The Tracks Under The Train
The topic of patellofemoral pain syndrome (PFPS) has been covered here several times over the past two decades, and for good reason:
According to a 2002 study of 1579 subjects, it is the #1 overuse injury, with 21% of the top ten injuries affecting runners falling within this diagnosis. (Which helps explain why it has become known as “Runner’s Knee” though it not exclusive to that group – PFPS comprises 25% of all knee diagnoses in the general population.)
As described in earlier installments (Articles #15-16, 72, and 89), the pain from PFPS generally arises when the protective coating of cartilage tissue on the back of the kneecap (patella) is damaged, either by trauma or wear-and-tear degeneration, allowing compressive and friction forces to be transmitted to the sensitive bone tissue underneath. While this premise is commonly accepted, the reason for this degeneration is still somewhat controversial.
The part most agree upon is the model of “faulty tracking” of the patella within the anterior groove of the femur (thigh bone) as the knee is bent and straightened, as we do with every step, thereby placing uneven forces on the surface of the kneecap, forces that eventually lead to breakdown. And, if you have followed this column through the years, you may remember that there are multiple theories explaining how and why this occurs.
The original theory was based on a “train going off the tracks” concept. The argument was that the patella was being pulled unevenly by the four quadriceps muscles, causing it to slide off to one side of the femoral groove. The proposed solution was to balance the strength of the muscles, or change the timing and proportion of the muscle contractions by training the individual muscles with biofeedback. If that didn’t work well enough, taping or bracing was used to try to keep the train on the tracks.
Later, a new theory began to emerge that turned this model upside-down. Noticing a relationship between PFPS and overpronation of the foot in many subjects, some investigators hypothesized that what was really happening in these cases was analogous to the “tracks moving out from underneath the train.” In other words, the problem was actually due to the femur moving improperly inward as a consequence of the faulty foot movement, with the same end-result of improper tracking of the patella. Foot orthotic devices were the most frequently used intervention to correct this faulty movement pattern.
Several studies appeared to support this theory and practice, though some experts questioned the validity of those investigations. More recently, as I noted in one of the earlier articles, there has been a greater focus on functional weakness of particular muscles of the hip as the true culprit causing this faulty movement of the thigh, leading to the “tracks/train wreck.” That article, which appeared here in 2003, cited several studies that were just beginning to validate this hypothesis, especially in female athletes. Now, seven years later, there is even more evidence to support targeting the hip as the area to address in treating this specific knee problem.
I have previously described (Articles #89 and 95) two effective exercises for improving strength and motor control of the hip abductors and external rotators. Here are two additional exercises that studies have shown to be effective in preventing and resolving PFPS:
- The Clam – lying on one side in a fetal position (hips and knees comfortably flexed), raise the knee on top toward the ceiling while keeping the feet together and avoiding rolling the trunk or pelvis back. Just move the knee up. Lower slowly and repeat 10-20 times.
- The Fire Hydrant – position yourself on your hands and knees. Lift one leg up and out to the side, as if … well, the name of the exercise should give you the picture. Don’t roll your trunk or pelvis. Lower slowly and repeat 10-20 times.
These two simple exercises, done once or twice a day, will specifically improve the strength and function of the hip muscles that need to work correctly to help you avoid the #1 running injury.