Damage estimator, a possible way to predict the failure of hip and knee endoprosthesis

Abstract

Purpose The purpose of this study was to realize finite element simulation in order to dynamically determine the area of the contact, the contact pressure and the strain energy density (identified as a damage function) for three different activities – normal walking, ascending stairs and descending stairs – that could be considered to define the level of the activity of the patient. Design/methodology/approach The finite element model uses a modern contact mechanism that includes friction between the metallic femoral condyles or femoral head (considered rigid) and the tibial polyethylene insert or acetabular cup (considering a non-linear behaviour). Findings For all three activities, the finite element analyses were performed, and a damage score was computed. Finally, a cumulative damage score (that accounts for all three activities) was determined, and the areas where the fatigue wear is likely to occur were identified. Originality/value A closer look at the distribution of the damage score reveals that the maximum damage is likely to occur not at the contact surface, but in the subsurface.