Nonlinear ultrasound monitoring of fatigue microdamage accumulation in cortical bone

Abstract Microdamage, in the form of small cracks, exists in healthy bone. Microdamage can be created by an overload or by repetitive motion (fatigue) during daily activities. Usually, microdamage is repaired during bone remodeling and a steady state is maintained. However, in cases of excessive microdamage creation or slowed bone remodeling, microdamage can coalesce to create a fracture. Our previous work [1,2] has investigated microdamage accumulation with increasing strain in bovine trabecular bone loaded in monotonic compression and compressive fatigue. Specimens fatigued at relatively high load levels fail after a few loading cycles, while specimens fatigued at lower load levels may undergo thousands of cycles before failure. During high cycle fatigue, microdamage may accumulate by the growth of pre-existing microcracks, as well as by the crack initiation seen in low cycle fatigue.

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The accumulation of fatigue microdamage in human cortical bone of two different ages in vitro

Clinical Biomechanics ◽

10.1016/0268-0033(96)00010-1 ◽

1996 ◽

Vol 11 (7) ◽

pp. 365-375 ◽

Cited By ~ 90

Author(s):

P Zioupos ◽

XT Wang ◽

JD Currey

Keyword(s):

Cortical Bone ◽

Human Cortical Bone ◽

Different Ages ◽

Fatigue Microdamage

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Fatigue Microdamage in Bovine Trabecular Bone

Journal of Biomechanical Engineering ◽

10.1115/1.1631584 ◽

2003 ◽

Vol 125 (6) ◽

pp. 769-776 ◽

Cited By ~ 32

Author(s):

Tara L. A. Moore ◽

Lorna J. Gibson

Keyword(s):

Trabecular Bone ◽

Compressive Strain ◽

Staining Technique ◽

Area Fraction ◽

Maximum Strain ◽

Yield Strain ◽

Fluorochrome Staining ◽

Microdamage Accumulation ◽

Small Cracks ◽

Fatigue Microdamage

Microdamage, in the form of small cracks, may accumulate in trabecular bone loaded in fatigue. Specimens of bovine trabecular bone were loaded in compressive fatigue at one of four normalized stresses and loading was stopped after the specimens reached one of six maximum strains. Microdamage was identified using a fluorochrome staining technique, and microdamage parameters, including the number of damaged trabeculae and the damaged area fraction, were measured. No microdamage was observed during loading to strains below the yield strain; at higher strains, all microdamage parameters increased with increasing maximum compressive strain. Few significant differences were observed in the type or amount of microdamage accumulation between specimens loaded to the same maximum strain at different normalized stresses; however, more trabecular fractures were observed at high numbers of cycles, which corresponded to low normalized stresses.

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Fatigue damage in cortical bone detected using nonlinear ultrasound

Journal of Biomechanics ◽

10.1016/s0021-9290(06)82896-4 ◽

2006 ◽

Vol 39 ◽

pp. S8

Author(s):

M. Muller ◽

A. D'Hanens ◽

D. Mitton ◽

M. Talmant ◽

P. Johnson ◽

...

Keyword(s):

Cortical Bone ◽

Fatigue Damage ◽

Nonlinear Ultrasound

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THe effects of suppressed bone remodeling by bisphosphonates on microdamage accumulation and degree of mineralization in the cortical bone of dog rib

Journal of Bone and Mineral Metabolism ◽

10.1007/bf03026321 ◽

2005 ◽

Vol 23 (S1) ◽

pp. 36-42 ◽

Cited By ~ 91

Author(s):

T. Mashiba ◽

S. Mori ◽

S. Komatsubara ◽

Y. Cao ◽

T. Manabe ◽

...

Keyword(s):

Cortical Bone ◽

Bone Remodeling ◽

Degree Of Mineralization ◽

Microdamage Accumulation

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Fatigue Microdamage in Bovine Cortical Bone Imaged by Micro-Computed Tomography Using a Barium Sulfate Contrast Agent

MRS Proceedings ◽

10.1557/proc-0898-l09-04 ◽

2005 ◽

Vol 898 ◽

Author(s):

Huijie Leng ◽

Xiang Wang ◽

Glen L Niebur ◽

Ryan K Roeder

Keyword(s):

Computed Tomography ◽

Contrast Agent ◽

Cortical Bone ◽

Barium Sulfate ◽

Spatial Density ◽

Distinct Region ◽

Micro Ct ◽

Micro Computed Tomography ◽

Microdamage Accumulation ◽

Notch Tip

AbstractAccumulation of microdamage during fatigue can lead to increased fracture susceptibility in bone. Current techniques for imaging microdamage in bone are inherently destructive and two-dimensional. A non-destructive, three-dimensional technique is needed to measure the spatial density of microdamage accumulation. Therefore, the objective of this study was to image microdamage accumulation in cortical bone during fatigue using micro-computed tomography (micro-CT) with a barium sulfate (BaSO4) contrast agent. Bovine cortical bone beams were loaded under four-point bending fatigue. Two symmetric notches were machined on the tensile surface in order to generate damage at the stress concentrations during loading. Specimens were loaded to a specified number of cycles or until one notch fractured, such that the other notch exhibited accumulated microdamage just prior to fracture. Microdamage ahead of the notch was stained by precipitation of BaSO4 and imaged using micro-CT. Reconstructed images showed a distinct region of bright voxels around the notch tip or along propagating cracks due to the presence of BaSO4, which was verified by backscattered electron imaging and energy dispersive spectroscopy. The stained region exhibited a characteristic kidney shape perpendicular to the notch tip, which was correlated to principal strain contours calculated by finite element analysis. The area of stained regions was positively correlated with the number of loading cycles.

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