Does knee joint alignment with the axis of the isokinetic dynamometer affect peak torque?

Abstract

The aim of this study was to determine the reliability of five positions of alignment of the knee joint with the axis of a Cybex Norm isokinetic dynamometer. Seventeen physically active males volunteered for this study. The knee joint was positioned in five xy-plane coordinate s from the rotational axis of the dynamometer (cm): (0,0); (2,0); (4,0 ); (0,-2) and (0;-4). Repeated measures Analysis of Variance (ANOVA) and Ratio Limits of Agreement (RLOA) were calculated for knee extension and flexion peak torque in all positions of alignm ent. The ANOVA demonstrated no significant differences in peak to rque for knee extension (F(4,64) = 1.813, P > 0.05) and significant differences in peak torque for knee flexion (F(4,64) = 5.760, P < 0.05). The RLOA showed a standard bias ranging from 7 to 12% and systematic error ranging from 21 to 29% for knee flexio n. Knee extension peak torque did not significantly change when the knee joint was misaligned with the axis of the dynamometer. However, knee flexion peak torque was significantly affected when the knee was moved away both horizontally and vertically from the centre of the axis of the dynamometer.