Objective: To determine the effects of a weight-bearing rehabilitation program on quadriceps and gluteus medius electromyographic activity, pain, and function in subjects diagnosed with patellofemoral pain syndrome (PFPS).
Design: Pretest and posttest 6-week intervention study.
Setting: Musculoskeletal research laboratory.
Participants: Fourteen subjects diagnosed with PFPS and 14 healthy control subjects volunteered to participate in this study. No subjects withdrew from the study because of adverse effects.
Intervention: Subjects diagnosed with PFPS participated in a 6-week rehabilitation program. The rehabilitation program consisted of weight-bearing exercises that focused on strengthening the quadriceps and hip abductor musculature.
Main outcome measures: Electromyographic onsets of the vastus medialis oblique (VMO) and vastus lateralis and onset and duration of the gluteus medius were collected during a stair-stepping task that was performed during the pretest and posttest. A visual analog scale (VAS) and Functional Index Questionnaire (FIQ) were administered at pretest and posttest and each week of the intervention.
Results: Vastus lateralis and VMO onset timing differences (vastus lateralis electromyographic onset minus VMO electromyographic onset) and VAS and FIQ scores significantly improved for patients diagnosed with PFPS. Vastus lateralis and VMO onset timing in the PFPS group were significantly different from those in the control group at baseline and were not significantly different from the control group after the intervention. We did not find differences in gluteus medius onsets or duration of activity.
Conclusions: Subjects diagnosed with PFPS responded favorably and quickly to a therapeutic exercise program that incorporated quadriceps and hip musculature strengthening. The efficacy of the therapeutic exercise program used in this study should be further investigated in a larger subject population.