Finite element simulation of cement-bone interface micromechanics; a comparison to experimental results

Recently, experiments have been performed to determine the micromechanical behavior of the cement-bone interface under tension-compression loading conditions. These experiments were simulated using finite element analysis (FEA) to test whether the micromechanical response of the cement-bone interface could be captured in micro-models. Cement-bone interface models were created of experimental specimens based upon micro-computed tomography data, including the complex interdigitated bone-cement morphology and simulated frictional contact at the interface. The models were subjected to a fully reversible tension-compression load, mimicking the experimental protocol. Similar to what was found experimentally, the simulated interface was stiffer in compression than in tension and the majority of displacement localized to the cement-bone interface. There was a weak correlation between the FEA predicted stiffness and the stiffness found experimentally, with average errors of 8.3 and 29.8% in tension and compression, respectively. The hysteresis behavior found experimentally was partially reproduced in the simulation by including friction at the cement-bone interface. Furthermore, stress analysis suggested that cement was more at risk of fatigue failure than bone, concurring with the experimental observation that more cracks were formed in the cement than in the bone. The current study provides information that may help to better understand the load transfer mechanisms taking place at the cement-bone interface.