Subject-specific finite element simulation of the human femur considering inhomogeneous material properties: A straightforward method and convergence study

  • Authors:
  • Andreas HöLzer;Christian SchröDer;Matthias Woiczinski;Patrick Sadoghi;Andreas Scharpf;Bernhard Heimkes;Volkmar Jansson

  • Affiliations:
  • Department of Orthopaedic Surgery, Hospital of the Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany;Department of Orthopaedic Surgery, Hospital of the Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany;Department of Orthopaedic Surgery, Hospital of the Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany;Department of Orthopaedic Surgery, Medical University of Graz, Auenbruggerplatz 5, 8036 Graz, Austria;Department of Orthopaedic Surgery, Hospital of the Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany;Department of Orthopaedic Surgery, Hospital of the Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany;Department of Orthopaedic Surgery, Hospital of the Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany

  • Venue:
  • Computer Methods and Programs in Biomedicine
  • Year:
  • 2013

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Abstract

In numerical finite element (FE) simulations of human bones subject-specific models are necessary to reproduce the physiological conditions, which include the determination of inhomogeneous material properties from computed tomography (CT) scans and their implementation in the numerical model. In the present approach common software packages are directly used for the entire simulation process from segmentation of CT scans, surface reconstruction, mesh generation, calculation of mean element densities to FE simulation. The influence of the mesh discretisation level on the maximum displacement, the total system energy and the principal surface stress distribution of eight human femurs was analysed. Both the maximum displacement and the total system energy showed typical convergence behaviour towards an asymptotic value with decreasing element size. The principal surface stress distribution followed similar qualitative trends at all mesh discretisation levels studied for the same femur. However, the stress distributions did not converge with decreasing element size and still differed significantly between the two smallest element sizes studied of approximately 2mm and 1mm. The magnitude of convergence differed among the individual femurs. Thus, individual convergence studies in terms of local stress or strain distributions are necessary for accurately predicting local stress and strain values in subject-specific FE bone models.