Measurement and statistical analysis of the passive viscoelastic properties of the human knee joint during flexion and extension motion.

Abstract

The purpose of the present investigation was to determine the net passive elastic joint moment and the angular damping coefficient of the human knee joint in full range flexion-extension. A secondary purpose was to develop regression equations to predict the measured passive properties from anthropometric data. The passive elastic moments increased exponentially as the limits of either flexion or extension were approached. The midrange of joint motion was a low moment (5 N$\cdot$m), low stiffness region. Considerable variability in the magnitudes of the passive elastic moments existed across subjects. At 140$\sp\circ$ of flexion, between about 5 N$\cdot$m and 86 N$\cdot$m was measured while the range at full extension (0$\sp\circ$) was about 6 N$\cdot$m to 22 N$\cdot$m. The angular damping coefficient was a nonlinear function (approximately quadratic) of the knee joint angle. The variability was not quite as high compared to the elastic component. Application of the data to the late swing phase of walking indicated that, for some subjects, the passive moments may contribute (or oppose) significantly to the net joint moment. (Abstract shortened by UMI.)