Anisotropic Post-Yield Behavior of Human Cortical Bone

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Abstract

Age-related bone fractures have been an increasing concern as the life expectancy of humans has been increasing. The increase of fracture incidences in the elderly is associated with the reduction of energy dissipation capacity of aging bone. Therefore, identifying the underlying mechanisms of energy dissipation during post-yield deformation is critical in developing strategies to prevent bone fractures. The purpose of this study was to determine the contribution orientation has on the post-yield properties of bone since it is an anisotropic material. It is hypothesized that while post-yield properties of cortical bone are transversely isotropic, the underlying mechanism of post-yield deformation is independent of loading orientation. To test this hypothesis, forty-eight cylindrical samples were obtained from femurs of eight middle-aged male donors (51.5 ± 3.3 years old). One set of 24 was tested monotonically and the other set was tested in a progressive loading scheme. After testing, the samples were stained and photographed under a fluorescent microscope to detect microdamage. The data show there are significant differences in energy dissipation between the longitudinal direction when compared with the transverse (circumferential and radial) directions, with values being larger in the longitudinal direction. The data also show that there are no significant orientation differences in the yield strain. These suggest that the underlying mechanism of post-yield deformation of cortical bone in compression is independent of orientation.

Cited Works (15)

Year	Entry
1994	Schaffler MB, Pitchford WC, Choi K, Riddle JM. Examination of compact bone microdamage using back-scattered electron microscopy. Bone. September–October 1994;15(5):483-488.
1974	Reilly DT, Burstein AH. The mechanical properties of cortical bone. J Bone Joint Surg. 1974;56A(5):1001-1022.
1975	Reilly DT, Burstein AH. The elastic and ultimate properties of compact bone tissue. J Biomech. 1975;8(6):393-405.
2001	Currey JD. Bone strength: what are we trying to measure? Calcif Tiss Int. April 2001;68(4):205-210.
2009	Leng H, Dong XN, Wang X. Progressive post-yield behavior of human cortical bone in compression for middle-aged and elderly groups. J Biomech. March 11, 2009;42(4):491-497.
1994	Zioupos P, Currey JD, Sedman AJ. An examination of the micromechanics of failure of bone and antler by acoustic emission tests and laser scanning confocal microscopy. Med Eng Phys. May 1994;16(3):203-212.
1996	Jepsen KJ, Goldstein SA, Kuhn JL, Schaffler MB, Bonadio J. Type‐I collagen mutation compromises the post‐yield behavior of Mov13 long bone. J Orthop Res. May 1996;14(3):493-499.
1996	Courtney AC, Hayes WC, Gibson LJ. Age-related differences in post-yield damage in human cortical bone: experiment and model. J Biomech. November 1996;29(11):1463-1471.
1995	Burr DB, Hooser M. Alterations to the en bloc basic fuchsin staining protocol for the demonstration of microdamage produced in vivo. Bone. October 1995;17(4):431-433.
1998	Martin RB, Burr DB, Sharkey NA. Skeletal Tissue Mechanics. New York, NY: Springer-Verlag; 1998.
1976	Burstein AH, Reilly DT, Martens M. Aging of bone tissue: mechanical properties. J Bone Joint Surg. 1976;58A(1):82-86.
2005	Nyman JS, Reyes M, Wang X. Effect of ultrastructural changes on the toughness of bone. Micron. October–December 2005;36(7-8):566-582.
1994	Zioupos P, Currey JD. The extent of microcracking and the morphology of microcracks in damaged bone. J Mater Sci. 1994;29(4):978-986.
1998	Burr DB, Turner CH, Naick P, Forwood MR, Ambrosius W, Hasan MS, Pidaparti R. Does microdamage accumulation affect the mechanical properties of bone? J Biomech. April 1998;31(4):337-345.
1993	McCalden RW, McGeough JA, Barker MB, Court-Brown CM. Age-related changes in the tensile properties of cortical bone: the relative importance of changes in porosity, mineralization, and microstructure. J Bone Joint Surg. 1993;75A(8):1193-1205.