Influence of interface crack and non-uniform cement thickness on mixed-mode stress intensity factor and prediction of interface failure of cemented acetabular cup

The goal is to determine the influence of interface crack and non-uniform cement thickness on mixed-mode stress intensity factors (SIF) and the prediction of interface failure of the cemented cup. Nine three-dimensional (3D) finite element (FE) models of implanted pelvic bone were developed having the uniform and non-uniform cement thickness based on computed tomography (CT) dataset. Physiological loading conditions and location-dependent material properties of cancellous bone were considered for the present analysis. In order to understand the influence of crack at cement-bone and implant-cement interfaces, two-dimensional (2D) cracked models were generated and solved using the element free Galerkin method (EFGM). For cracked analysis, a rectangular section was considered at both the interfaces in the superior, inferior, anterior, and posterior anatomic locations to determine the SIF. The average stress values obtained from 3D FE analysis was transferred at the cut boundary of the rectangular section and considered as a mixed-mode loading condition to understand the influence of crack and non-uniform cement thickness on interface failure. The results of the present study indicated that the cement thickness plays an important role in interface failure. SIF increases as the cement thickness decreases. Anterior location is more prone to failure as compared to other anatomic locations. The chance of cement-bone interface failure is more as compared to the implant-cement interface. The present study also indicated that the chance of interface failure is more for the generation of edge crack as compared to center crack.