Anatomical modelling and simplified modelling in total hip replacement: difference in contact mechanics perspective

Abstract

Total hip replacements (THR) is a surgical operation to replace defect bone at the hip joints. The rate of succession of THR post-operative still debatable as complication and failure rate of the prosthesis still exists. Edge-loading, dislocation, fracture and longevity are among the concerned issues with many studies were conducted via software analysis. This study aims to simulate the difference of anatomical and simplified modelling in finite element analysis (FEA) and investigate edge-loading effect at different inclination angle in both modelling conditions. A CT scan hemi-pelvic model was reshaped and converted into 3D model in SolidWorks and the next step, FEA was conducted in ANSYS Workbench V16 at different inclination angle. Anatomical and simplified model were run in ANSYS Workbench and the results were recorded. The anatomical modelling produced less contact pressure range 26% to 51% compared with simplified modelling at four inclination angle conditions. Von Mises stress and total deformation in anatomical also produced reduction of more than 65%. Both modelling conditions shows agreement that elevated inclination angle had induced higher contact pressure at superior region of acetabular cup. The inclusion of hemi-pelvic model gives lower value recorded in FEA as contact stress dispersed into the bone that already integrated with the implant given statistically significant (p<0.05). Noteworthy to include bone integration into implant during FEA study to produce unambiguous contact mechanics studies.