Observations on the measurement of joint stiffness

Abstract Joint stiffness is a major manifestation of joint disease. Nevertheless, an extensive review of the literature reveals that little has been done to characterize joint stiffness quantitatively or qualitatively. A method is described whereby joint stiffness can be measured in precise physical terms. The major components of joint stiffness in normal and arthritic subjects are elasticity and plasticity. Viscous stiffness is small, and friction is negligible even in badly damaged joints.