Porous‐media simulation of bone‐cement spreading during vertebroplasty

Abstract

The reinforcement of porous vertebral cancellous bone by the injection of bone cement is a practical procedure for the stabilisation of osteoporotic compression fractures and other weakening lesions. This contribution concerns the reproduction and prediction of the resulting bone‐cement distribution during the injection procedure by means of numerical simulation. A detailed micromechanical (locally single‐phasic) model exhibits the drawback that all geometrical and physical transition conditions of the individual parts of the complex aggregate have to be known. Therefore, we rather proceed from a macroscopic (and multi‐constituent) continuum‐mechanical model based on the Theory of Porous Media. In this regard, the homogenisation of the underlying micro‐structure results in a model of three constituents: these are the solid bone skeleton, which is saturated by the liquid bone marrow that may be displaced by the injected liquid bone cement. The influence of the micro‐architecture of the pore space on the spreading of the bone cement is considered by a spatial diversification of the anisotropic permeability tensors, obtained through image processing techniques applied to medical imaging data (µCT). The numerical investigation of the strongly coupled problem enables the study of vertebroplasty and allows for the comparison between the simulation results and the experimentally determined bone‐cement distribution that were imaged during injections. (© 2013 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)