Bio-Lubrication Phenomena affect Residual Stresses and Phases of Zirconia Implants

In hip simulation studies, zirconia fails in water and saline but survive in calf serum environments at specific protein concentrations. Until now there has not been a theoretical basis for explaining this behaviour. Here we present for the first time a body of microstructural evidences based on Raman microprobe spectroscopy, which clarify the origin of this different behaviour. Microscopic maps of residual stresses and localised phase transformation from tetragonal to monoclinic are presented. These findings provide the theoretical basis for better understanding wear phenomena in zirconia and to establish the structural and micromechanical reasons for their superior behavior in physiologic environments.