Effect of a Functional Rehabilitation Program on EMG Activity and Pain in Patients with Patellofemoral Pain Syndrome

The purpose of this study is to determine the effect of a functional rehabilitation program on EMG activity and pain in patients with patellofemoral pain syndrome (PFPS). Thirty subjects between the ages of 18-40 diagnosed with PFPS will participate in this study. Inclusion criteria includes: anterior or retropatellar knee pain present during at least two of the following- ascending/descending stairs, hopping/running, squatting, kneeling, and prolonged sitting; insidious onset of symptoms not related to trauma; pain with quadriceps inhibition and compression of the patella; pain on palpation of patellar facets. Exclusion criteria includes: symptoms present for less than two months; clinical evidence of other knee' pathology; knee surgery; history of patella dislocations or subluxations; current significant injury affecting other lower extremity joints; age::: 40; less than 30-min. of physical activity three days/week. A pre and post-test study design will be used. The independent variables are test (pre and post), phase (ascent, descent), and muscles (vastus medialis oblique, vastus lateralis, gluteus medius). The dependent variables are onset timing ofthree lower extremity muscles, and changes in scores on the visual analog scale (VAS) and functional index questionnaire (FIQ). The alternate hypotheses include: 1) EMG onsets ofthe VMO, VL, and gluteus medius will significantly differ between pre and post-test measures, 2) EMG duration of the gluteus medius will significantly differ between pre and post-test measures, 3) there will be a decrease in pain between the pre and post-test measures assessed using the visual analog scale, and 4) there will be a significant difference in perception of functional abilities between pre and post-test measures assessed using the functional index questionnaire. The pre and post test measures will consist of subjects performing a stair-stepping task in which EMG data will be collected on the onsets of the VMO and VL, and the onset and duration of the gluteus medius during both ascent and descent. Subjects will also complete a visual analog scale and functional index questionnaire during the pre and post-test. At the pre-test subjects will begin a six week functional rehabilitation program, and return to the lab once a week for instruction and progression of rehabilitation exercises. Following the six weeks of rehabilitation, subjects will perform the post-test. Separate repeated measures ANOVA will be performed to determine differences in EMG onset of the VMO, VL, gluteus medius, VAS scores, and FIQ scores.