Patellofemoral pain syndrome (PFPS) affects one out of every four active individuals, making it one of the most common knee problems among athletes and military recruits. What causes this problem? Well, it can be fairly complex. Usually there isn’t just one reason why people develop PFPS.
The patella, or kneecap, can be a source of knee pain when it fails to function properly. Alignment or overuse problems of the patella can lead to wear and tear of the cartilage behind the patella. This produces pain, weakness, and swelling of the knee joint. Several different problems (including PFPS) can affect the patella and the groove it slides through in the knee joint.
It is believed that PFPS occurs because of altered biomechanics between the patella and the femur (thigh bone). The patellofemoral joint is where the kneecap moves up and down over the lower end of the femur. If the patella doesn’t track up and down over the femur where it should, uneven wear and tear can occur. The protective cartilage behind the patella can get torn and shredded. Patellofemoral pain syndrome is most noticeable when kneeling, squatting, or during other activities that require bending the knee. That’s because altered hip and knee motion increase the pressure from contact between the patella and femur during these motions.
That’s one side of the equation. The other side involves the foot, such as in your case. Pronation/i> of the foot (toward a flat-foot position) alters the biomechanical relationship between the foot and knee. A simple drop in the arch of the foot shifts the weightbearing load on the knee toward the medial half of the joint (side closest to the other knee). Repetitive knee motions will increase pressure and load on that one side more than the other — potentially leading to patellofemoral syndrome or even knee arthritis later in life.
Correcting the foot position is important, but it may not be the only problem. Research shows that the hip angle as well as any muscle weakness or imbalance anywhere in the leg can contribute to patellofemoral pain syndrome. But there’s nothing wrong with making one correction and seeing how you feel. Having someone such as an orthopedic surgeon or physical therapist evaluate your posture, muscle strength, and kinematics (how the knee moves) is a good way to identify early on other problems that could be corrected as well, thus possibly reducing your risk for other knee problems or a recurrence of the PFPS.