DESIGN AND DEVELOPMENT OF AN UNCONSTRAINED DYNAMIC KNEE SIMULATOR

A dynamic knee simulator has been developed to allow in-vitro investig ation of the mechanical response of the joint corresponding to dynamic functional activities, e.g., walking. In the simulator, the controlle d inputs are the time-histories of three parameters of a given dynamic activity: the flexion angle, and the flexion/extension moment and tib ial axial force components of the foot-to-floor reaction. A combinatio n of stepping motors and electro-hydraulic actuators is used to apply to a knee specimen, simultaneously and independently, the specified lo ad and/or displacement inputs while allowing unconstrained relative mo tion between the joint members. Satisfactory performance of the simula tor has been established for walking gait conditions based on measurem ents on three fresh-frozen specimens.