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Elastic modulus varies along the bovine femur

Elastic modulus varies along the bovine femur
Elastic modulus varies along the bovine femur

Bone is a heterogeneous material and its mechanical properties vary within the body. Variations in the mechanical response of different bone samples taken from the body cannot be fully explained by only looking at local compositional information at the tissue level. Due to different states of the stress within bones, one might expect that mechanical properties change over the length of a bone; this has not been a matter of systematic research in previous studies. In this study, the distribution of the tissue elastic modulus along the bovine femur is investigated using three-point bending tests. Two bovine femora were split to seven and eight blocks from proximal to distal metaphysis, respectively and twenty beam shaped bone samples were extracted and tested from each block. Based on our findings, the longitudinal elastic modulus follows a gradient pattern along the bovine femur as it increases along the bone from the proximal metaphysis to mid-diaphysis and then decreases toward the distal metaphysis again. Considering long bones to be subjected to bending loads, this mechanism alters the bone structure to support load in the regions where it is needed; similar as outlined by Wolff's law. In another part of this study, microfocus X-ray computed tomography (μCT) was found unable to predict the same trend of changes for the elastic modulus via image-based or density-based elastic moduli calculations. This is insofar important as conventional finite element models of bone are often directly shaped from μCT data. Based on our findings, it seems that current computed tomography based finite element models generated in this manner may not adequately capture the local variation of material behavior of bone tissue, but this may be improved by considering the changes of the elastic modulus along the femur.

Cortical bone mechanics , Micro-computed tomography, Micro-CT gray-level to elastic modulus conversion
1751-6161
279-285
Nobakhti, Sabah
085cb1c0-f856-4c9e-a068-f41d5d0257b7
Katsamenis, Orestis L.
8553e7c3-d860-4b7a-a883-abf6c0c4b438
Zaarour, Nizar
3d4f5c6c-d7e8-4cbb-b44c-eae6d329c611
Limbert, Georges
a1b88cb4-c5d9-4c6e-b6c9-7f4c4aa1c2ec
Thurner, Philipp J.
ab711ddd-784e-48de-aaad-f56aec40f84f
Nobakhti, Sabah
085cb1c0-f856-4c9e-a068-f41d5d0257b7
Katsamenis, Orestis L.
8553e7c3-d860-4b7a-a883-abf6c0c4b438
Zaarour, Nizar
3d4f5c6c-d7e8-4cbb-b44c-eae6d329c611
Limbert, Georges
a1b88cb4-c5d9-4c6e-b6c9-7f4c4aa1c2ec
Thurner, Philipp J.
ab711ddd-784e-48de-aaad-f56aec40f84f

Nobakhti, Sabah, Katsamenis, Orestis L., Zaarour, Nizar, Limbert, Georges and Thurner, Philipp J. (2017) Elastic modulus varies along the bovine femur. Journal of the Mechanical Behavior of Biomedical Materials, 71, 279-285. (doi:10.1016/j.jmbbm.2017.03.021).

Record type: Article

Abstract

Bone is a heterogeneous material and its mechanical properties vary within the body. Variations in the mechanical response of different bone samples taken from the body cannot be fully explained by only looking at local compositional information at the tissue level. Due to different states of the stress within bones, one might expect that mechanical properties change over the length of a bone; this has not been a matter of systematic research in previous studies. In this study, the distribution of the tissue elastic modulus along the bovine femur is investigated using three-point bending tests. Two bovine femora were split to seven and eight blocks from proximal to distal metaphysis, respectively and twenty beam shaped bone samples were extracted and tested from each block. Based on our findings, the longitudinal elastic modulus follows a gradient pattern along the bovine femur as it increases along the bone from the proximal metaphysis to mid-diaphysis and then decreases toward the distal metaphysis again. Considering long bones to be subjected to bending loads, this mechanism alters the bone structure to support load in the regions where it is needed; similar as outlined by Wolff's law. In another part of this study, microfocus X-ray computed tomography (μCT) was found unable to predict the same trend of changes for the elastic modulus via image-based or density-based elastic moduli calculations. This is insofar important as conventional finite element models of bone are often directly shaped from μCT data. Based on our findings, it seems that current computed tomography based finite element models generated in this manner may not adequately capture the local variation of material behavior of bone tissue, but this may be improved by considering the changes of the elastic modulus along the femur.

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JMBBM_Nobakhti_et_al_2017_Accepted_manuscript - Accepted Manuscript
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More information

Accepted/In Press date: 25 March 2017
e-pub ahead of print date: 27 March 2017
Published date: July 2017
Keywords: Cortical bone mechanics , Micro-computed tomography, Micro-CT gray-level to elastic modulus conversion
Organisations: Engineering Mats & Surface Engineerg Gp, Engineering Science Unit, nCATS Group, Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 408267
URI: http://eprints.soton.ac.uk/id/eprint/408267
ISSN: 1751-6161
PURE UUID: 6be64d69-fe9b-410f-a66d-d80339e08932
ORCID for Orestis L. Katsamenis: ORCID iD orcid.org/0000-0003-4367-4147
ORCID for Philipp J. Thurner: ORCID iD orcid.org/0000-0001-7588-9041

Catalogue record

Date deposited: 18 May 2017 04:02
Last modified: 08 Oct 2020 04:11

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Contributors

Author: Sabah Nobakhti
Author: Nizar Zaarour
Author: Georges Limbert

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