Fatigue behavior of zirconia hip joint heads: experimental results and finite element analysis.

Crack propagation in a commercial surgical grade zirconia ceramic was performed under static and cyclic loading. The slow crack growth (SCG) parameters were determined in both cases. The results reveal the existence of threshold values of applied stress intensity factor, for both static and cyclic loadings, below which no slow crack growth occurs. Such threshold values represent one of the best advantages of the present zirconia ceramic compared with other ceramic materials used in orthopedics, which could lead to a strong enhancement of implant lifetime. This threshold value was also identified by cyclic fatigue tests performed on zirconia femoral heads. From a new statistical approach based on the Monte Carlo method, the knowledge of SCG behavior, and the help of finite element analysis, an estimate of the lifetime prediction has been made and discussed.