Location and length of gap at the interface of an idealized cemented hip implant subjected to bending

The uncertainties of the residual stresses developed during cement polymerization and of the coefficient of friction were considered in the 3-D finite element model using nonlinear contact elements to model the debonded interface. An accurate modeling of the residual stresses and coefficient of friction are important to predict the gap lengths; for an interference of 0.05 mm and a coefficient of friction of 0.4, no gap was observed. These indicate possible true gap locations at the interface which could lead to initial loss of fixation of the implant.