FE MODELING OF EQUINE RADII USING CT IMAGING BASED PARAMETERISED STIFFNESS DISTRIBUTION

Abstract

For the set-up of finite element (FE) models of long bones software is available with which their geometry can be assessed on the basis of gray values in computer tomography (CT) images. Gray values of CT images are widely used to deduce the distribution of mass density, material stiffness, and strength of bones. In most cases, the apparent density is defined to be a linear function of the gray value HU as: = f · HU + g (1) For the local material stiffness, in turn, many empirical functions are available which define the Young’s module E in terms of the apparent density , typically in the form as follows: E = · (2) However, measured data of bone samples including gray value, density, and material stiffness are rarely available which cover the full density range from trabecular to cortical bone. The variety of stiffness functions available in literature is wide but the accuracy and the limitations of their application on the FE modelling of bones are unknown. Within the scope of the present study a sample of equine radii was tested in 3-point-bending and in pure torsion. By means of detailed FE models of these bones the tests were simulated for both load cases. The parameter study aimed at investigating the conformity of stiffness functions as in Eq. (2) in terms of the behaviour of the radii under 3-pointbending as well as under pure torsion.