Mechanical strength of a femoral reconstruction in paediatric oncology: A finite element study

F. Taddei, M. Viceconti, M. Manfrini, A. Toni

Research output: Contribution to journalArticlepeer-review

Abstract

In 1997 the proximal femur of a four-year-old child affected by a Ewing sarcoma was reconstructed using a massive bone allograft in conjunction with a vascularized fibula autograft. During the first three years of follow-up the reconstruction underwent important morphological changes. The aim of the present study was to evaluate the risk of fracture of the reconstructed proximal femur, once the physiological loads are restored, associated with a short, slow but unprotected level walk. Subject-specific finite element models of the operated femur, and of the intact contralateral one, were generated from a computed tomography exam, taken for routine clinical monitoring at month 33 of follow-up. The material properties were mapped on to the mesh and a loading condition comprising the hip joint reaction and the abductor muscle force was simulated. The risk of fracture was locally estimated, for the operated and intact femur, using the ratio between the bone tissue strength and the predicted Von Mises equivalent stress, taking into account the different behaviours of the bone tissue in tension or compression. The results showed that although the fibula grew dramatically during follow-up, the reconstructed femur had not recovered the whole mechanical strength of a normal femur. The reconstructed femoral neck seemed to be weaker than the contralateral one and hence at a higher fracture risk. However, no region reached the failure limit, so the model predicted no fracture of the femur if a short, slow but unprotected walk were allowed. The model predictions found an indirect clinical validation when the child was allowed to perform short unprotected walks and did not experience any fracture.

Original languageEnglish
Pages (from-to)111-119
Number of pages9
JournalProceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
Volume217
Issue number2
DOIs
Publication statusPublished - 2003

Keywords

  • Bone tumours
  • Computed tomography
  • Finite element
  • Risk of fracture
  • Skeletal reconstructions

ASJC Scopus subject areas

  • Biomedical Engineering
  • Mechanical Engineering
  • Medicine(all)

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