COMPARISON BETWEEN THE SURFACE ELECTROMYOGRAM OF THE QUADRICEPS SURROUNDING THE KNEES OF HEALTHY WOMEN AND THE KNEES OF WOMEN WITH OSTEOARTHROSIS

The purpose of this study was to compare the electromyographic (EMG) a ctivity of the quadriceps femoris (QF) muscles of women with osteoarth rosis (OA) of the knee with the EMG activity of the QF muscles of heal thy women. To this end, a total of 14 subjects attended a single test session during which full-wave rectified surface electromyograms were recorded from the rectus femoris (RF), vastus lateralis (VL) and vastu s medialis (VM) muscles during maximum voluntary isometric quadriceps contractions performed at knee angles of 30 degrees and 60 degrees fle xion. A comparison of the resultant normalized peak EMG ratios using i ndependent t-tests demonstrated significantly higher composite QF musc le activation for the osteoarthrotic subjects (p < 0.05). A higher RF activation also differentiated the two groups. The findings raise the possibility of a direct correlation between abnormal activation of the QF and joint status. They also suggest that patients with knee OA may benefit functionally from rehabilitation designed to improve QF coord ination and endurance, and not merely strength.