Contact sensitivity analysis of FE model of the pelvis with press-fit acetabular prosthesis

Introduction Lack of primary stability has been regarded as a major cause for implant loosening in total hip arthroplasty. For a cementless press-fit acetabular cup, primary stability is achieved by inserting an oversized component into an under-reamed acetabulum. Two features that result from the press-fitting process are – 1) pre-stress due to the difference in the radii of the cup and the reamed acetabulum and 2) a gap in the polar region between the dome of the cup and the acetabulum. There are experimental studies that investigate the stability of various contact conditions of press-fit cups such as [1]. However uncertainties still remain as to what effects different contact conditions have on FE simulation results. There exist FE studies that modelled the pelvis and cementless press-fit cups together but frictional contact without press-stress or polar gap is used frequently in such studies [2]. Moreover it is not clear how different contact conditions affect load transfer patterns to the trabecular bone. This study aims to investigate these two problems.