Fracture of bone tissue: The ‘hows’ and the ‘whys’

doi:10.1016/j.medengphy.2008.09.007

Medical Engineering & Physics

Volume 30, Issue 10, December 2008, Pages 1209-1226

https://doi.org/10.1016/j.medengphy.2008.09.007 Get rights and content

Abstract

The mechanical performance of bone is of paramount importance for the quality of life we experience. The structural integrity of bone, its hierarchical structure, organisation and its physicochemical constitution, all influence its ability to withstand loads, such as those seen occasionally in everyday life loading scenarios, which are either above the norm, prolonged, or repetitive. The present review explores three interconnected areas of research where significant progress has been made lately: (i) The recorded mechanical behaviour of bone and the way it fails; (ii) the inner architecture, organisational, hierarchical structure of bone tissue; and (iii) the bone properties at the micro/nanostructural and biophysical level. Exercising a line of thought along a structure/function based argument we advance from ‘how’ bone fractures to ‘why’ it fractures, and we seek to obtain a fresh insight in this field.

Introduction

The mechanical performance of bone is of paramount importance for the quality of life we experience, as fractures are painful debilitating events. Some fractures are quite obviously due to the fact that bone is subject to loads that exceed certain threshold levels (in terms of stress or damage), that may also be prolonged (creep), or repetitive (fatigue). Others are caused by bone being structurally compromised as a result of disease, ageing, surgical intervention, pharmaceutical treatments, poor diet, lack of exercise, and so forth. In all cases some sense can be made by invoking either material/ engineering principles to explain the effects of overload, or structure/function relationships [1] to grapple with the effects of a materially and structurally compromised tissue.

Section snippets

How bone breaks

There is a consensus regarding the various stages leading to and during fracture of bone, but what is still debated is the relative importance of the various phases in determining the final failure outcome [2]. The stress/strain curve (in tension) for bone as a material shows a (macroscopically) linear phase followed by a ‘knee’ region where the material yields and then a region of strain hardening (which can be shorter or longer depending on the circumstances) followed by sudden catastrophic

Hierarchical structure and composite mechanics

In order to understand the origins of the high toughness and stiffness of bone, and the reasons for its alterations with age and disease, we have to consider the full complexity of the hierarchical architecture [1], [27] from the macro- to the micro-scale and the mechanical properties of the various constituents at each level. The heterogeneity of bone at the meso- and microscale has a direct influence on growth of cracks within bone and on the failure process (Fig. 6).

Bone nanostructure: collagen fibres, fibril arrays, crystals

The most prominent nanostructures are the collagen fibres, surrounded and infiltrated by mineral. The attachment sites of macromolecules onto the collagen framework are not distinctly known, although several immunohistological studies have shown preferential labelling of some macromolecules in a periodic fashion along the collagen molecules and fibres [86].

The three main building materials are crystals, collagen, and non-collagenous organic proteins. Mature crystals are most likely not

Conclusions

To develop a clear picture of the structure/function relationships in bone, research follows two paths: (i) conventional material characterization of its performance and (ii) structural analysis of the mechanisms underlying bone fracture. For the latter, we can identify two main current challenges, one at the bone material level and one at the microstructural level. At the material level, one critical limitation now appears to be the difficulty in developing an accurate quantitative picture of

Conflict of interest statement

None.

Acknowledgments

P. Zioupos is grateful to various colleagues: R. Cook, K. Winwood, V. Wise, J.D. Currey, U. Hansen, A.J. Sedman, and also to J.-Y. Rho whose untimely death was a great loss. H.S. Gupta would like to thank the Max Planck Society and the German-Israeli Foundation (Project no. I-800-180.10\2003) for support, and numerous coworkers, in particular: P. Fratzl, W. Wagermaier, S. Krauß, J. Seto, K. Kanawka, M. Kerschnitzki, G. Benecke, U. Stachewicz, and P. Roschger.

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¹: Current address: School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS.

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Fracture of bone tissue: The ‘hows’ and the ‘whys’

Abstract

Introduction

Section snippets

How bone breaks

Hierarchical structure and composite mechanics

Bone nanostructure: collagen fibres, fibril arrays, crystals

Conclusions

Conflict of interest statement

Acknowledgments

Medical Engineering & Physics

Materials Science & Engineering C: Biomimetic Materials, Sensors & Systems

Composites Science and Technology

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Biomaterials

Bone

Bone

Journal of Biomechanics

Journal of Biomechanics

Medical Engineering & Physics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Medical Engineering & Physics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Acta Biomaterials

Journal of Structural Biology

Bone

Journal of Biomechanics

Bone

Journal of Biomechanics

Journal of Biomechanics

Journal of Biomechanics

Bone

Journal of Molecular Biology

Biophysical Journal

Journal of Structural Biology

Bone

Fractography of bone

From brittle to ductile fracture of bone

Nature Materials

Observations of damage morphologies in nacre during deformation and fracture

Journal of Materials Science

Fracture mechanics of bone

Journal of Biomechanical Engineering—Transactions of the ASME

The true toughness of human cortical bone measured with realistically short cracks

Nature Materials

Toughening mechanisms in cortical bone

42nd Annual Meeting ORS, February 19–22

In:

A fracture mechanics and mechanistic approach to the failure of cortical bone

Fatigue & Fracture of Engineering Materials & Structures

Mechanistic fracture criteria for the failure of human cortical bone

Nature Materials

The effect of strain rate on the mechanical properties of human cortical bone

Journal of Biomechanical Engineering—Transactions of the ASME