The development of a knee joint simulator

The authors describe the development of a knee joint simulating apparatus. Various types of knee prostheses can now be tested with respect to either friction and wear or to the forces occurring by simply carrying out the appropriate modifications. So far as the possible applications of the knee joint simulator the following remarks may be of interest: Hinged prostheses can be tested by removing the loadcell in the tibia-holder. Different patterns of loading and kinematics can be introduced by applying different cams and bars respectively. The effect of ligaments and menisci is simulated by the four-bar mechanism and replacement of this mechanism in order to alter this simulation is possible. The research project that is now being carried out on the knee joint simulator is an investigation of the stress and strain patterns in the bone implant configuration by means of combined static and dynamic experiments with different types of knee prosthesis. Various categories of prostheses are under investigation, i.e. hinged prostheses, semi-constrained prostheses, and condylar prostheses. The femur and tibia (of cadaver knees) are cast in acrylate at either end and placed into the femur- and tibia-holder. Strain gauges are connected to bone and implant surfaces and the experiments are carried out in a physiological invironment.