Mechanical testing of cancellous bone from the femoral head: Experimental errors due to off-axis measurements

Caroline Öhman, Massimiliano Baleani, Egon Perilli, Enrico Dall'Ara, Simone Tassani, Fabio Baruffaldi, Marco Viceconti

Research output: Contribution to journalArticle

Abstract

The aim of this study was to verify whether a misalignment between the testing direction and the trabecular main direction has a significant effect on the compressive behaviour of cancellous bone. Ten cylindrical specimens were extracted from femoral heads with a misalignment to the trabecular main direction of approximately 20°. Each specimen was paired with a specimen extracted aligned with the main direction of the trabeculae on the basis of the closest bone volume fraction, obtaining two groups, one 'aligned' and one 'misaligned'. The average off-axis angle was 6.1° and 21.6° for the 'aligned' and 'misaligned' group, respectively. The specimens underwent micro-tomographic analysis, compressive testing, micro-indentation testing and ashing. No significant differences were found in histomorphometric parameters, hardness and ash density between the two groups, whereas significant differences were found in Young's modulus and ultimate stress: both parameters, measured for the 'misaligned' group, were about 40% lower than those measured for the 'aligned' group. These results demonstrate a great effect of the angle between the testing direction and the main direction of the trabecular structure on the compressive behaviour of cancellous bone. This angle should be reduced as much as possible (in the present work the average value was 6.6±3.3°), in any case measured, and always reported together with the mechanical parameters of cancellous bone.

Original languageEnglish
Pages (from-to)2426-2433
Number of pages8
JournalJournal of Biomechanics
Volume40
Issue number11
DOIs
Publication statusPublished - 2007

Keywords

  • Bone quality
  • Bone strength
  • Cancellous bone
  • Mechanical testing
  • Trabecular architecture

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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