QUADRICEPS FEMORIS ACTIVATION IN HEALTHY WOMEN WITH GENU-VARUM AND WOMEN WITH OSTEOARTHROSIS AND GENU-VARUM

This study was designed to determine whether abnormalities in individu al or group activation of the knee extensors might be associated with the development of osteoarthrosis of the knee with varus deformity. Th e study consisted of nine healthy women with normal tibial alignment, nine age-matched healthy women with genu varum and nine women with ost eoarthrosis (OA) of the knee and genu varum. The outcome measures were normalized quadriceps femoris surface EMG amplitude parameters, recor ded during maximal voluntary static and dynamic knee extension movemen ts at 0-degree and 90-degrees s-1, expressed as a percentage and peak torque and rate of tension development at 0-degree s-1. Under static c onditions, the normalized EMG amplitudes, peak torque and rate of tens ion development of the knee extensors in those with OA differed signif icantly from the same parameters recorded for the healthy controls (P < 0.001). Although not significantly different under dynamic condition s (P = 0.1), there was a large effect size of f = 0.40 between the EMG amplitudes of the knee extensors of the two healthy groups, with a ne glible effect size between the EMG amplitudes as well as a trend towar ds reduced tension-generating capacity of the knee extensors in those with varus deformity, irrespective of joint status. The latter finding s suggest that the neural integration mechanisms governing the contrac tural pattern of the extensors surrounding a varus knee may abnormally reflect various aspects of the disease process of osteoarthrosis.