Are Patellofemoral Pain and Quadriceps Femoris Muscle Torque Associated With Locomotor Function?

The purpose of this investigation was to determine the influence of pain and muscle weakness on gait variables in subjects with patellofemoral pain (PFP). Nineteen female subjects with a diagnosis of PFP and 19 female subjects without PFP participated in the study. Subjects underwent gait analysis (stride characteristics and joint motion) during level walking, ascending and descending stairs, and ascending and descending ramps, in addition to isometric torque testing of the knee extensors of the involved limb. Pain and functional status also were assessed. Compared with the comparison group, the primary gait compensation in the PFP group was a reduced walking speed, which was a function of both a reduced stride length and cadence. Knee extensor torque was the only predictor of gait function, with increased torque correlating with improved stride characteristics. In addition, PFP was not associated with locomotor function. These findings suggest that functional ability in persons with PFP is associated with increased quadriceps femoris muscle torque. Future research is needed to determine whether function improves with quadriceps femoris muscle strengthening.