Is realistic modeling of the compliant cement-bone interface in cemented total hip arthroplasty important?

Fatigue failure of the cement mantle in terms of cement cracking is one of the failure mechanisms that leads to aseptic loosening in cemented hip reconstructions. Recently, experiments have demonstrated that there is substantial motion at the cement-bone interface, which may compromise cemented reconstructions [1]. In Finite Element (FE) models of cemented hip reconstructions, the cement-bone interface has been implemented as (I) an infinitely stiff interface, (II) a soft tissue layer with constant stiffness, or (III) a layer of cohesive elements with a mixed-mode behavior based on experimental data on failure in tension and shear. Recently μFE-models have been utilized to study the mixed-mode behavior of the cement-bone interface in more detail [2]. It is, however, unknown whether it is necessary to include the complex mixed-mode response of the cement-bone interface in FE models of cemented hip reconstructions. The following research questions were stated: (1) What is the evaluation of cement crack formation as a result of different cement-bone interface characteristics? (2) Is cement-bone interface failure likely? (3) Does fatigue failure of the cement mantle increase or decrease the probability of failure of the cement-bone interface