Patellofemoral pain syndrome is one of the most common causes of knee pain in young athletes. The condition is an overuse injury that results from activities that cause pressure or friction on the cartilage behind the kneecap. Patellofemoral pain syndrome occurs frequently in athletes who participate in sports that involve running, jumping, or squatting.

The kneecap functions as a shield to protect the front of the knee. As a result, direct impact to the kneecap can cause damage to the cartilage that lines the back surface of the kneecap. In addition, the kneecap functions as a fulcrum to help the quadriceps (thigh muscles) straighten the knee. In this capacity, there is pressure on this same cartilage behind the kneecap that is related to how hard the quadriceps are contracting (Fc) and how bent the knee is (β) (see Figure 1). It is not unusual for the pressure on...

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