The influence of acetabular bone cracks in the press-fit hip replacement: Numerical and experimental analysis

BackgroundThe press-fit hip acetabular prosthesis implantation can cause crack formation in the thin regions surrounding the acetabular. As a consequence the presence of cracks in this region can lead to poor fixation and fibrous tissue formation.MethodsNumerical and experimental models of commercial press-fit hip replacements were developed to compare the behavior between the intact and implanted joints. Numerical models with an artificial crack and without crack were considered. The iliac and the femur were created through 3D geometry acquisition based on composite human replicas and 3D-Finite Element models were generated.FindingsThe mechanical behavior was assessed numerically and experimentally considering the principal strains. The comparison between Finite Element model predictions and experimental measurements revealed a maximum difference of 9%. Similar distribution of the principal strains around the acetabular cavity was obtained for the intact and implanted models. When comparing the Von Mises stresses, it is possible to observe that the intact model is the one that presents the highest stress values in the entire acetabular cavity surface.InterpretationThe crack in the posterior side changes significantly the principal strain distribution, suggesting bone loss after hip replacement. Relatively to micromotions, these were higher on the superior side of the acetabular cavity and can change the implant stability and bone ingrowth.