Use of robotics technology to measure friction in animal joints.

A new system to measure friction in animal joints has been designed. The system utilizes a robotic arm. Force control of the robotic arm was used to survey the geometry of a sliding surface before the friction of the joint is measured. This enables the precise measurement of friction in joints of complex shape. To test the reliability of the new system we took friction measurements from 10 rabbit stifles. The experimental conditions were: (i) intact joints, (ii) joints after the surfaces were washed. The mean values of the frictional coefficients were 0.008 in the intact joints and 0.015 in the washed joints. These mean values were similar to some previous results obtained from canine hip joints under the same experimental conditions. Furthermore, the standard deviations in this study were smaller than in the previous study. These facts suggest that the new system is reliable. RELEVANCE:--The pathology of osteoarthritis is related to the lubrication mechanisms of joints. In any study of the lubrication mechanisms, an accurate friction measurement is important. In this study we used robotics technology to measure friction in joints.