KNEE EXTENSION AND FLEXION TORQUE AS A FUNCTION OF THIGH ASYMMETRY

Although tape measurement of thigh girth is a common component of a cl inical knee examination, the implications of thigh girth asymmetry are not well understood. The purpose of this study was to examine the rel ationship between high girth asymmetry and torque asymmetry for extens ion and flexion of the knee. Thirty subjects with thigh girth asymmetr y of at least 2 cm, measured at a site 15 cm proximal to the superior pole of the patella, were studied. Subjects were measured for girth at 10 sites along each thigh. Knee flexion and extension torque producti on were also tested on a Cybex II isokinetic dynamometer. Girth asymme try was determined by the difference in measurements between the subje cts' smaller and larger thighs. Percent girth asymmetries varied by si te, with the greatest average girth asymmetry (asymmetry = 5.94%) at 1 6 cm proximal to the superior patellar pole. Percent peak torque asymm etries were computed from the differences between subjects' stronger v s. weaker thighs. Correlations and regressions of both extension and f lexion torque asymmetries upon girth asymmetry sites showed higher ass ociations and less error for more proximal measurements. Fair to moder ate correlation coefficients (r = .37-.42, p < .05) were statistically significant for extension torque asymmetry compared with girth asymme try at sites 12, 14, 16, and 20 cm proximal to the patella and for fle xion torque asymmetry only at the 14-cm site. Although girth and torqu e asymmetries were found to be somewhat related, percent girth asymmet ry provided only a limited prediction of percent peak torque asymmetry .