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Load-bearing in cortical bone microstructure: selective stiffening and heterogeneous strain distribution at the lamellar level

Load-bearing in cortical bone microstructure: selective stiffening and heterogeneous strain distribution at the lamellar level
Load-bearing in cortical bone microstructure: selective stiffening and heterogeneous strain distribution at the lamellar level
An improved understanding of bone mechanics is vital in the development of evaluation strategies for patients at risk of bone fracture. The current evaluation approach based on bone mineral density (BMD) measurements lacks sensitivity, and it has become clear that as well as bone mass, bone quality should also be evaluated. The latter includes, among other parameters, the bone matrix material properties, which in turn depend on the hierarchical structural features that make up bone as well as their composition. Optimal load transfer, energy dissipation and toughening mechanisms have, to some extent, been uncovered in bone. Yet, the origin of these properties and their dependence upon the hierarchical structure and composition of bone are largely unknown. Here we investigate load transfer in the osteonal and sub-osteonal levels and the mechanical behaviour of osteonal lamellae and interlamellar areas during loading. Using cantilever-based nanoindentation, in situ microtensile testing during atomic force microscopy (AFM) and digital image correlation (DIC), we report evidence for a previously unknown mechanism. This mechanism transfers load and movement in a manner analogous to the engineered "elastomeric bearing pads" used in large engineering structures. ?-RAMAN microscopy investigations showed compositional differences between lamellae and interlamellar areas. The latter have lower collagen content but an increased concentration of noncollagenous proteins (NCPs). Hence, NC-enriched areas on the microscale might be similarly important for bone failure as ones on the nanoscale. Finally, we managed to capture stable crack propagation within the interlamellar areas in a time-lapsed fashion, proving their significant contribution towards fracture toughness.
cortical bone, crack propagation, nanoindentation, raman spectroscopy, bone structure
1751-6161
152-165
Katsamenis, Orestis
8553e7c3-d860-4b7a-a883-abf6c0c4b438
Chong, Harold M.H.
795aa67f-29e5-480f-b1bc-9bd5c0d558e1
Andriotis, Orestis G.
714f98eb-2fa3-4a97-99f9-f7e7765ec128
Thurner, Philipp J.
ab711ddd-784e-48de-aaad-f56aec40f84f
Katsamenis, Orestis
8553e7c3-d860-4b7a-a883-abf6c0c4b438
Chong, Harold M.H.
795aa67f-29e5-480f-b1bc-9bd5c0d558e1
Andriotis, Orestis G.
714f98eb-2fa3-4a97-99f9-f7e7765ec128
Thurner, Philipp J.
ab711ddd-784e-48de-aaad-f56aec40f84f

Katsamenis, Orestis, Chong, Harold M.H., Andriotis, Orestis G. and Thurner, Philipp J. (2013) Load-bearing in cortical bone microstructure: selective stiffening and heterogeneous strain distribution at the lamellar level. Journal of the Mechanical Behavior of Biomedical Materials, 17, 152-165. (doi:10.1016/j.jmbbm.2012.08.016). (PMID:23131790)

Record type: Article

Abstract

An improved understanding of bone mechanics is vital in the development of evaluation strategies for patients at risk of bone fracture. The current evaluation approach based on bone mineral density (BMD) measurements lacks sensitivity, and it has become clear that as well as bone mass, bone quality should also be evaluated. The latter includes, among other parameters, the bone matrix material properties, which in turn depend on the hierarchical structural features that make up bone as well as their composition. Optimal load transfer, energy dissipation and toughening mechanisms have, to some extent, been uncovered in bone. Yet, the origin of these properties and their dependence upon the hierarchical structure and composition of bone are largely unknown. Here we investigate load transfer in the osteonal and sub-osteonal levels and the mechanical behaviour of osteonal lamellae and interlamellar areas during loading. Using cantilever-based nanoindentation, in situ microtensile testing during atomic force microscopy (AFM) and digital image correlation (DIC), we report evidence for a previously unknown mechanism. This mechanism transfers load and movement in a manner analogous to the engineered "elastomeric bearing pads" used in large engineering structures. ?-RAMAN microscopy investigations showed compositional differences between lamellae and interlamellar areas. The latter have lower collagen content but an increased concentration of noncollagenous proteins (NCPs). Hence, NC-enriched areas on the microscale might be similarly important for bone failure as ones on the nanoscale. Finally, we managed to capture stable crack propagation within the interlamellar areas in a time-lapsed fashion, proving their significant contribution towards fracture toughness.

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Published date: January 2013
Keywords: cortical bone, crack propagation, nanoindentation, raman spectroscopy, bone structure
Organisations: Bioengineering Group, Electronics & Computer Science

Identifiers

Local EPrints ID: 351857
URI: http://eprints.soton.ac.uk/id/eprint/351857
ISSN: 1751-6161
PURE UUID: cf226d65-821e-4518-8990-e5ab94d29ee7
ORCID for Orestis Katsamenis: ORCID iD orcid.org/0000-0003-4367-4147
ORCID for Harold M.H. Chong: ORCID iD orcid.org/0000-0002-7110-5761
ORCID for Philipp J. Thurner: ORCID iD orcid.org/0000-0001-7588-9041

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Date deposited: 30 Apr 2013 12:57
Last modified: 18 Feb 2021 17:16

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Author: Harold M.H. Chong ORCID iD
Author: Orestis G. Andriotis

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