Experimental and numerical static failure analyses of total hip replacement interfaces

In joint replacement surgery, the critical point in the success of cemented implants is the stabilisation between the implant and bone. The stronger the interlocking achieved on both the implant–cement interface and the cement–bone interface, the more durable is the surgical intervention. However, to date, it has not been possible to prevent aseptic loosening of hip implants, thus making a revision surgery necessary after a period of about 10 years. In this study, the tensile and shear strengths of the implant–cement and cement–bone interfaces and factors which can affect these strengths such as sandblasting parameters and implant material choice were investigated experimentally. The stresses on the total hip replacement interfaces were then determined via finite element analysis and the findings compared with the strength values obtained from the mechanical tests. The total hip replacement prosthesis was designed using SolidWorks software, and material properties and boundary conditions were modelled with the ANSYS Workbench software. Stresses due to the loads applied to the femur head had exceeded the highest tensile and shear strength values obtained by the classical test methods and damaged the contact surfaces in some regions. In light of these findings, the damage sites of the interfaces were determined.