Valid μ finite element models of vertebral trabecular bone can be obtained using tissue properties measured with nanoindentation under wet conditions

U. Wolfram, Hans-Joachim Wilke, Philippe K. Zysset

Research output: Contribution to conferencePaperpeer-review

Abstract

Osteoporosis-related vertebral fractures represent a major public health problem. Anatomy-specific CT-based finite element (FE) simulations could help in identifying which vertebrae have the highest risk of fracture and thus help to decide upon the need for vertebroplasty or other surgical intervention. Continuum level FE simulations require effective macroscopic material properties of the vertebra. Micro finite element (microFE) models can be used to circumvent the difficult experiments that are necessary to determine these effective properties. From a quantitative point of view, these microFE models depend critically on the chosen trabecular tissue properties. The question remains whether linear elastic microFE models of vertebral trabecular bone with and without specimen-specific tissue properties yield similar results as non-destructive macroscopic experiments under moist conditions. microFE models were set up from microCT scans with specimen-specific or average tissue moduli measured by nanoindentation under dry and wet testing conditions. Non-destructive macroscopic mechanical compression, tension and torsion tests were performed. Experimentally obtained and simulated apparent stiffnesses were compared. No significant difference was found when comparing microFE simulations with wet tissue properties and experiments for tension, compression and torsion (p>0.05). Concordance correlation coefficients were high for tension and compression (r(c)(wet)>or=0.96,p<0.05) but moderate for torsion (r(c)(wet)=0.81,p<0.05). The agreement between simulation and experiment was confirmed by Bland-Altman plots which showed mean differences <or=10MPa. Surprisingly, the agreement between simulation and experiment was not reduced by using an average tissue modulus. The results indicate that valid microFE models can be set up using average tissue properties obtained under wet indentation conditions.
Original languageEnglish
Publication statusPublished - 2010
Event9th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering - Westin Hotel, Valencia, Spain
Duration: 23 Feb 201027 Feb 2010
http://www.tandfonline.com/doi/abs/10.1080/17521742.2010.516157

Conference

Conference9th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering
Abbreviated titleCMBBE 2010
CountrySpain
CityValencia
Period23/02/1027/02/10
Internet address

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