Effect of micromorphology of cortical bone tissue on crack propagation under dynamic loading

Mayao Wang,Björn Busse,Xing Gao,Simin Li,Adel Abdel-Wahab,Christoph Riedel,Elizabeth A Zimmermann,Vadim V Silberschmidt,E Cadoni

doi:10.1051/epjconf/20159403005

Abstract

Structural integrity of bone tissue plays an important role in daily activities of humans. However, traumatic incidents such as sports injuries, collisions and falls can cause bone fracture, servere pain and mobility loss. In addition, ageing and degenerative bone diseases such as osteoporosis can increase the risk of fracture [1]. As a composite-like material, a cortical bone tissue is capable of tolerating moderate fracture/cracks without complete failure. The key to this is its heterogeneously distributed microstructural constituents providing both intrinsic and extrinsic toughening mechanisms. At micro-scale level, cortical bone can be considered as a four-phase composite material consisting of osteons, Haversian canals, cement lines and interstitial matrix. These microstructural constituents can directly affect local distributions of stresses and strains, and, hence, crack initiation and propagation. Therefore, understanding the effect of micromorphology of cortical bone on crack initiation and propagation, especially under dynamic loading regimes is of great importance for fracture risk evaluation. In this study, random microstructures of a cortical bone tissue were modelled with finite elements for four groups: healthy (control), young age, osteoporosis and bisphosphonate-treated, based on osteonal morphometric parameters measured from microscopic images for these groups. The developed models were loaded under the same dynamic loading conditions, representing a direct impact incident, resulting in progressive crack propagation. An extended finite-element method (X-FEM) was implemented to realize solution-dependent crack propagation within the microstructured cortical bone tissues. The obtained simulation results demonstrate significant differences due to micromorphology of cortical bone, in terms of crack propagation characteristics for different groups, with the young group showing highest fracture resistance and the senior group the lowest.

Highlights

IntroductionOne of the most suitable approaches is an extended finite-element method (X-FEM) that was introduced by Belyschko and Black in 1999 [7]
Random microstructures of a cortical bone tissue were modelled with finite elements for four groups: healthy, young age, osteoporosis and bisphosphonate-treated, based on osteonal morphometric parameters measured from microscopic images for these groups
The authors [8, 9] employed X-FEM to study the function of cement lines in bone fracture

Summary

Introduction

One of the most suitable approaches is an extended finite-element method (X-FEM) that was introduced by Belyschko and Black in 1999 [7] Since it has been used increasingly in simulation of discontinuity problems such as crack propagation. Budyn et al [12] developed a multiple scale statistical X-FEM simulation method to evaluate crack propagation of cortical bone under uniaxial tension. Quantitative correlations between the type and distribution of microstructural constituents and the fracture behaviour of human cortical bones in different groups are still unknown. Numerical simulations with X-FEM were used to simulate the facture behaviour of cortical bone under dynamic loading condition to understand the relationships between microstructural constituents and crack propagation

Methods

Results

Conclusion