Could Hip and Knee Muscle Strengthening Alter the Pain Intensity in Patellofemoral Pain Syndrome?

In patellofemoral pain syndrome (PFPS) as a common cause of knee pain in athletes, muscle weakness is proposed to contribute to its pain and dysfunction. This study was conducted to determine whether hip and knee muscles strengthening can accordingly reduce pain. In a single blinded, randomized clinical trial, 32 females (52 knees) with PFPS were randomly divided into a case and a control group. All the hip muscles and knee extensor in the case group and only the knee extensor in the control group were tested. In the case of recognizing weakness, they underwent a 4-week strengthening exercise program, after which a retest was taken. Pain as indicated on a visual analogue scale was recorded before and after the intervention. Both groups revealed pain reduction, although the amount of reduction was significantly greater in the cases compared to the subjects in the control group. Among the muscles selected for strengthening, only the hip flexors, abductors, and external rotators were found related to successful treatment as defined by at least 15% pain reduction on a pain visual analogue scale. Despite the current concept of focusing on quadriceps strengthening exercise in PFPS in the attempt to reduce pain and dysfunction, the results of this study did not support this idea. More attention should be shifted toward the hip muscles, if a long term and more efficient treatment is targeted.