There may be different causes of failures in bone; however, their origin generally lies at the lowest level of structural hierarchy, i.e., at the mineral-collagen composite. Any change in the nanostructure affects the affinity or bonding effectiveness between and within the phases at this level, and hence determines the overall strength and quality of bone. In this study, we propose a novel concept to assess change in the nanostructure and thereby change in the bonding status at this level by revealing change in the orientation distribution characteristics of mineral crystals. Using X-ray diffraction method, a parameter called Degree of Orientation (DO) has been quantified. The DO accounts for the azimuthal distribution of mineral crystals and represents their effective amount along any direction. Changes in the DOs in cortical bone samples from bovine femur with different preferential orientations of mineral crystals were estimated under external loads. Depending on the applied loads, change in the azimuthal distribution of the DOs and the degree of reversibility of the crystals was observed to vary. The characteristics of nanostructural change and thereby possible affect on the strength of bone was then predicted from the reversible or irreversible characteristics of distributed mineral crystals. Significant changes in the organization of mineral crystals were observed; however, variations in the applied stresses and elastic moduli were not evinced at the macroscale level. A novel concept to assess the alteration in nanostructure on the basis of mineral crystals orientation distribution has been proposed. The importance of nanoscale level information obtained noninvasively has been emphasized, which acts as a precise tool to estimate the strength and predict the possible fracture risks in bone.

References

References
1.
Almer
,
J. D.
, and
Stock
,
S. R.
, 2005, “
Internal Strains and Stresses Measured in Cortical Bone via High-Energy X-ray Diffraction
,”
J. Struct. Biol.
,
152
, pp.
14
27
.
2.
Almer
,
J. D.
, and
Stock
,
S. R.
, 2007, “
Micromechanical Response of Mineral and Collagen Phases in Bone
,”
J. Struct. Biol.
,
157
, pp.
365
370
.
3.
Fujisaki
,
K.
, and
Tadano
,
S.
, 2007, “
Relationship Between Bone Tissue Strain and Lattice Strain of HAp Crystals in Bovine Cortical Bone Under Tensile Loading
,”
J. Biomech.
,
40
, pp.
1832
1838
.
4.
Gupta
,
H. S.
,
Seto
,
J.
,
Wagermaier
,
W.
,
Zaslansky
,
P.
,
Boesecke
,
P.
, and
Fratzl
,
P.
, 2006, “
Cooperative Deformation of Mineral and Collagen in Bone at the Nanoscale
,”
Proc. Natl. Acad. Sci. U.S.A.
,
103
, pp.
17741
17746
.
5.
Giri
,
B.
,
Tadano
,
S.
,
Fujisaki
,
K.
, and
Sasaki
,
N.
, 2009, “
Deformation of Mineral Crystals in Cortical Bone Depending on Structural Anisotropy
,”
Bone
,
44
, pp.
1111
1120
.
6.
Currey
,
J. D.
, 1969, “
The Relationship Between the Stiffness and the Mechanical Content of Bone
,”
J. Biomech.
,
2
, pp.
477
480
.
7.
Katz
,
J. L.
, 1980, “
Anisotropy of Young’s Modulus of Bone
,”
Nature
283
, pp.
106
107
.
8.
Reilly
,
D. T.
, and
Burstein
,
A. H.
, 1975, “
The Elastic and Ultimate Properties of Compact Bone Tissue
,”
J. Biomech.
,
8
, pp.
393
405
.
9.
Bundy
,
K. J.
, 1985, “
Determination of Mineral-Organic Bonding Effectiveness in Bone-Theoretical Considerations
,”
Ann. Biomed. Eng.
,
13
, pp.
119
135
.
10.
Sasaki
,
N.
,
Ikawa
,
T.
, and
Fukuda
,
A.
, 1991, “
Orientation of Mineral in Bovine Bone and the Anisotropic Mechanical Properties of Plexiform Bone
,”
J. Biomech.
,
24
, pp.
57
61
.
11.
Wagner
,
H. D.
, and
Weiner
,
S.
, 1992, “
On the Relationship Between the Microstructure of Bone and Its Mechanical Stiffness
,”
J. Biomech.
,
25
, pp.
1311
1320
.
12.
Kotha
,
S. P.
, and
Guzelsu
,
N.
, 2000, “
The Effects of Interphase and Bonding on the Elastic Modulus of Bone: Changes With Age-Related Osteoporosis
,”
Med. Eng. Phys.
,
22
, pp.
575
585
.
13.
Nyman
,
J. S.
,
Reyes
,
M.
, and
Wang
,
X.
, 2005, “
Effect of Ultrastructural Changes on the Toughness of Bone
,”
Micron
,
36
, pp.
566
582
.
You do not currently have access to this content.