Research Papers: General

Strain-induced optical changes in demineralized bone

[+] Author Affiliations
Michael R. Hardisty

University of California-Davis, School of Medicine, Lawrence J. Ellison Musculoskeletal Research Laboratory, Department of Orthopaedic Surgery, Sacramento, California, 95817

University of California-Davis, Biomedical Engineering Graduate Group, Davis, California, 95616

Daniel F. Kienle

University of California-Davis, Department of Chemical Engineering and Materials Science, Biomedical Engineering Graduate Group, Davis, California, 95616

Tonya L. Kuhl

University of California-Davis, Biomedical Engineering Graduate Group, Davis, California, 95616

University of California-Davis, Department of Chemical Engineering and Materials Science, Biomedical Engineering Graduate Group, Davis, California, 95616

Susan M. Stover

University of California-Davis, Biomedical Engineering Graduate Group, Davis, California, 95616

University of California-Davis, School of Veterinary Medicine, JD Wheat Veterinary Orthopedic Research Laboratory, Biomedical Engineering Graduate Group, Davis, 95616

David P. Fyhrie

University of California-Davis, Biomedical Engineering Graduate Group, Davis, California, 95616

University of California-Davis, Department of Biomedical Engineering, Davis, California, 95616

J. Biomed. Opt. 19(3), 035001 (Mar 06, 2014). doi:10.1117/1.JBO.19.3.035001
History: Received September 27, 2013; Revised January 7, 2014; Accepted February 3, 2014
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Abstract.  Bone “stress-whitens,” becoming visibly white during mechanical loading, immediately prior to failure. Stress-whitening is known to make materials tougher by dissipating mechanical energy. A greater understanding of stress-whitening, both an optical and mechanical phenomenon, may help explain age-related increases in fracture risk that occur without changes in bone mineralization. In this work, we directly measure the optical properties of demineralized bone as a function of deformation and immersing fluid (with different hydrogen-bonding potentials, water, and ethanol). The change in refractive index of demineralized bone was linear: with deformation and not applied force. Changes in refractive index were likely due to pushing low-refractive-index fluid out of specimens and secondarily due to changes in the refractive index of the collagenous phase. Results were consistent with stress-whitening of demineralized bone previously observed. In ethanol, the refractive index values were lower and less sensitive to deformation compared with deionized water, corroborating the sensitivity to fluid hydration. Differences in refractive index were consistent with structural changes in the collagenous phase such as densification that may also occur under mechanical loading. Understanding bone quality, particularly stress-whitening investigated here, may lead to new therapeutic targets and noninvasive methods to assess bone quality.

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© 2014 Society of Photo-Optical Instrumentation Engineers

Citation

Michael R. Hardisty ; Daniel F. Kienle ; Tonya L. Kuhl ; Susan M. Stover and David P. Fyhrie
"Strain-induced optical changes in demineralized bone", J. Biomed. Opt. 19(3), 035001 (Mar 06, 2014). ; http://dx.doi.org/10.1117/1.JBO.19.3.035001


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