New technologies of surface treatment are speculated to reduce or prevent the generation of polyethylene particles. These new (spherical) bearing surfaces need to be evaluated with an appropriate testing method. Results from testing of flat surfaces are -in general- difficult to interpret.
A bi-axial “pin-on-ball“ device utilising commercially available components of artificial joints has been developed. The contact zone kinematics in hip joints according to in-vivo conditions are approximated. First results are promising: a phase shift between the pin and ball oscillations produced quasi-elliptical displacement trajectories, similar to the ones which are reported to take place during gait. The “pin-on-ball” set-up allowed to identify subtle characteristics of friction and generated a wear pattern which matched the features known from retrieval studies. Therefore, this new testing device might be an interesting alternative to common screening devices.