Heat treatment of bone is one of the reliable and simple sterilization methods to overcome the risk of rejection and disease transfer from allograft and xenograft, in particular for the prevention of human immunodeficiency virus (HIV) infection. However, the mechanical property of the micro-structural level after heat treatment is not well characterized. To address this issue, this study was carried out to compare the localized mechanical properties of micro-structural tissue with those at the global structural level. Nanoindentation technique has been well accepted as an accurate technique to measure mechanical property of small and heterogeneous specimen nondestructively, as well as the complex bio-material of micro-structural level, often with a resolution of better than 1 μm. In this study, nanoindentation was conducted to measure the localised elastic modulus and hardness values of bones at temperature of 23°C (room temperature – non-heated sample), 90°C and 150°C, respectively. All experiments were conducted at room temperature (~23°C). The elastic modulus ( E ) and nanoindentation hardenss ( H ) values in the longitudinal direction of bones heated at 150°C were recorded as 23.43 GPa and 0.73 GPa, respectively; as in transverse direction, the E and H values were 12.77 GPa and 0.54 GPa, respectively. It showed significant increases of 44% and 43% in the longitudinal direction as compared to those of the non heat-treated bones. In addition, E and H values in transverse direction also showed increases of 23% and 38%, respectively as compared to those of the non heat-treated bones. Furthermore, heat-treated bones at 90°C in longitudinal direction also appeared to have significant increases of 18% and 31% in E and H values, respectively. However, the E and H values in transverse direction increase only by 0.4% and 12.8%, respectively. In addition, compressive test is employed to measure the global stiffness ( E ) of the bone samples. When heated at 150°C, the bone specimen showed an increase of 60% in stiffness ( E ) and an increase of 26% in yield stress. On the other hand, when heated at 90°C, a slight increase of 11.4% in stiffness ( E ) and 21.5% in yield stress were recorded respectively. Furthermore, energy dispersive X-ray spectroscopy (EDX) which integrated with Backscattered Electron (BSE) imaging was conducted to examine the relationship between mineral content and mechanical strength within the nanoindentation regions. The data demonstrated that the non heat-treated bones obtained the highest calcium wt% amongst the three groups; as temperature increased, there was a slight decrease in calcium wt%; however, the changes were not severe in this study.
KeywordsBoneHeat Treatment
J. Catanese III, J. D. Featherstone and T. M. Keaveny, “Characterization of the Mechanical and Ultrastructural Properties of Heat-Treated Cortical Bone for Use as a Bone Substitute,” Journal of Biomedical Meterials Research, Vol. 45, No. 4, 1999, pp. 327-336. doi:10.1002/(SICI)1097-4636(19990615)45:4 3.0.CO;2-L
S. Shin, H. Yano, T. Fukunaga, S. Ikebe, K. Shimizu, N. Kaku, H. Nagatomi and S. Masumi, “Biomechanical Properties of Heat-Treated Bone Grafts,” Archives of Orthopaedic and Trauma Surgery, Vol. 125, No. 1, 2005, pp. 1-5. doi:10.1007/s00402-004-0746-6
J. Y. Rho, L. Kuhn-Spearing and P. Zioupos, “Mechanical Properties and the Hierarchical Structure of Bone,” Medical Engineering and Physics, Vol. 20, No. 2, 1998, pp. 92-102. doi:10.1016/S1350-4533(98)00007-1
A. Stanishevsky, S. Chowdhury, P. Chinoda and V. Thomas, “Hydroxyapatite Nanoparticle Loaded Collagen Fiber Composites: Microarchitecture and Nanoindentation Study,” Journal of Biomedical Meterials Research, Vol. 86A, No. 4, 2008, pp. 873-882. doi:10.1002/jbm.a.31657
F. Ferreira, M. A. Vaz and J. A. Sim?es, “Mechanical Properties of Bovine Cortical Bone at High Strain Rate,” Material Characterization, Vol. 57, No. 2, 2006, pp. 71-79. doi:10.1016/j.matchar.2005.11.023
A. Tatarinov, N. Sarvazyan and A. Sarvazyan, “Use of Multiple Acoustic Wave Modes for Assessment of Long Bones: Model Study,” Ultrasonics, Vol. 43, No. 8, 2005, pp. 672-680. doi:10.1016/j.ultras.2005.03.004
T. Jamsa, J. Y. Rho, Z. Fan, C. A. MacKay, S. C. Marks Jr. and J. Tuukkanen, “Mechanical Properties in Long Bones of Rat Osteopetrotic Mutations,” Journal of Biomechanics, Vol. 35, No. 2, 2000, pp. 161-165. doi:10.1016/S0021-9290(01)00203-2
Z. Fan, P. A. Smith, E. C. Eckstein and G. F. Harris, “Mechanical Properties of OI type III Bone Tissue Meas- ured by Nanoindentation,” Journal of Biomedical Meterials Research, Vol. 79A, No. 1, 2006, pp. 71-77. doi:10.1002/jbm.a.30713
J. Y. Rho and G. M. Pharr, “Effects of Drying on the Mechanical Properties of Bovine Femur Measured by Nanoindentation,” Journal of Materials Science: Materials in Medicine, Vol. 10, No. 8, 1999, pp. 485-488. doi:10.1023/A:1008901109705
T. Hoc, L. Henry, M. Verdier, D. Aubry, L. Sedel and A. Meunier, “Effect of Microstructure on the Mechanical Properties of Haversian Cortical Bone,” Bone, Vol. 38, No. 4, 2006, pp. 466-474. doi:10.1016/j.bone.2005.09.017
B. van Rietbergen, S. Majumdar, W. Pistoia, D. C. Newitt, M. Kothari, A. Laib and P. Rüegsegger, “Assessment of Cancellous Bone Mechanical Properties from Micro-FE Models Based on Micro-CT, pQCT and MR Images,” Technology and Health Care, Vol. 6, No. 5-6, 1998, pp. 413-420.
Nanoindentation
Mechanical Properties
BSE and EDX
A. Ural and D. Vashishth, “Cohesive Finite Element Modeling of Age-Related Toughness Loss in Human Cortical Bone,” Journal of Biomechanics, Vol. 39, No. 16, 2006, pp. 2974-2982. doi:10.1016/j.jbiomech.2005.10.018
A. Ural and D. Vashishth, “Anisotropy of Age-Related Toughness Loss in Human Cortical Bone: A Finite Ele- ment Study,” Journal of Biomechanics, Vol. 40, No. 7, 2007, pp. 1606-1614. doi:10.1016/j.jbiomech.2006.07.023
Z. Fan, J. Y. Rho and J. G. Swadener, “Three-Dimensional Finite Element Analysis of the Effects of Anisotropy on Bone Mechanical Properties Measured by Nanoindentation,” Journal of Meterials Research, Vol. 19, No. 1: 2004, pp. 114-122. doi:10.1557/jmr.2004.19.1.114
S. M. Bowman, J. Zeind, L. J. Gibson, W. C. Hayes and T. A. McMahon, “The Tensile Behavior of Demineralized Bovine Cortical Bone,” Journal of Biomechanics, Vol. 29, No. 11, 1996, pp. 1497-1501. doi:10.1016/0021-9290(96)84546-5
S. P. Kotha and N. Guzelsu, “Tensile Behavior of Cortical Bone: Dependence of Organic Matrix Material Properties on Bone Mineral Content,” Journal of Biomechanics, Vol. 40, No. 1, 2007, pp. 36-45. doi:10.1016/j.jbiomech.2005.11.016
J. D. Currey, “The Effect of Porosity and Mineral Content on the Young’s Modulus of Elasticity of Compact Bone,” Journal of Biomechanics, Vol. 21, No. 2, 1988, pp. 131- 139. doi:10.1016/0021-9290(88)90006-1
C. H. Turner, J. Y. Rho, Y. Takano, T. Y. Tsui and G. M. Pharr, “The Elastic Properties of Trabecular and Cortical Bone Tissues Are Similar: Results from Two Microscopic Measurement Techniques,” Journal of Biomechanics, Vol. 32, No. 4, 1999, pp. 437-441. doi:10.1016/S0021-9290(98)00177-8
X. J. Wang, X. B. Chen, P. D. Hodgson and C. E. Wen, “Elastic Modulus and Hardness of Cortical and Trabecular Bovine Bone Measured by Nanoindentation,” Transactions of Nonferrous Metals Society China, Vol. 16, No. 2, 2006, pp. s744-s748. doi:10.1016/S1003-6326(06)60293-8
J. Y. Rho, T. Y. Tsui and G. M. Pharr, “Elastic Properties of Human Cortical and Trabecular Lamellar Bone Measured by Nanoindentation,” Biomaterials, Vol. 18, No. 20, 1997, pp. 1325-1330. doi:10.1016/S0142-9612(97)00073-2
L. Oyen, “Nanoindentation Hardness of Mineralized Tissues,” Journal of Biomechanics, Vol. 39, No. 14, 2006, pp. 2699-2702. doi:10.1016/j.jbiomech.2005.09.011
P. K. Zysset, X. E. Guo, C. E. Hoffler, K. E. Moore and S. A. Goldstein, “Elastic Modulus and Hardness of Cortical and Trabecular Bone Lamellae measured by Nanoinden- tation in the Human Femur,” Journal of Biomechanics, Vol. 32, No. 10, 1999, pp. 1005-1012. doi:10.1016/S0021-9290(99)00111-6
J. Y. Rho, M. E. Roy II, T. Y. Tsui and G. M. Pharr, “Elastic Properties of Microstructural Components of Human Bone Tissue as Measured by Nanoindentation,” Jour- nal of Biomedical Meterials Research, Vol. 45, No. 1, 1999, pp. 48-54.
M. Todoh, S. Tadano and Y. Imari, “Effect of Heat Denaturation of Collagen Matrix on Bone Strength,” Proceedings of 13th International Conference on Biomedical Engineering, Singapore, Vol. 23, 3-6 December 2008, pp. 2034-2037.
R. Akhtar, S. Morse and P. M. Mummery, “Nanoindentation of Bone in a Physiological Environment,” Materials Research Society Symposium Proceedings, Vol. 844, 2005, pp. 15-20.
J. D. Currey, K. Brear, P. Zioupoa and G. C. Reilly, “Effect of Formaldehyde Fixation on Some Mechanical Properties of Bovine Bone,” Biomaterials, Vol. 16, No. 16, 1995, pp. 1267-1271. doi:10.1016/0142-9612(95)98135-2
X. Wang, R. A. Bank, J. M. Teloppele, K. A. Athansiou and C. M. Agrawal, “Effect of Collagen Denaturation on Bone Biomechanical Integrity,” 45th Annual Meeting, Orthopaedic Research Society, Anaheim, 1-4 February 1999, p. 782.
Z. Fan, J. G. Swadener, J. Y. Rho, M. E. Roy and G. M. Pharr, “Anisotropic Properties of Human Tibial Cortical Bone as Measured by Nanoindentation,” Journal of Orthopaedic Research, Vol. 20, No. 4, 2000, pp. 806-810. doi:10.1016/S0736-0266(01)00186-3
C. E. Hoffler, K. E. Moore, K. Kozloff, P. K. Zysset, M. B. Brown and S. A. Goldstein, “Heterogeneity of Bone Lamellar-Level Elastic Moduli,” Bone, Vol. 26, No. 6, 2000, pp. 603-609. doi:10.1016/S8756-3282(00)00268-4
P. Roschger, E. P. Paschalis, P. Fratzl and K. Klaushofer, “Bone Mineralization Density Distribution in Health and Disease,” Bone, Vol. 42, No. 3, 2008, pp. 456-466. doi:10.1016/j.bone.2007.10.021
W. C. Oliver and G. M. Pharr, “An Improved Technique for Determining Hardness and Elastic Modulus Using Load and Displacement Sensing Indentation Experiments,” Journal of Biomedical Meterials Research, Vol. 7, No. 6, 1992, pp. 1564-1583. doi:10.1557/JMR.1992.1564
D. Roylance, “Stress Strain Curve,” Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, 1999. http://ocw.mit.edu/courses/materials-science-and-engineering/3-11-mechanics-of-materials-fall-1999/modules/ss.pdf
R. D. Bloebaum, J. G. Skedros, E. G. Vajda, K. N. Bachus and B. R. Constantz, “Determining Mineral Content Variations in Bone Using Backscattered Electron Imaging,” Bone, Vol. 20, No. 5, 1997, pp. 485-490. doi:10.1016/S8756-3282(97)00015-X
H. Trebacz and K. Wójtowicz, “Thermal Stabilization of Collagen Molecules in Bone Tissue,” International Journal of Biological Macromolecules, Vol. 37, No. 5, 2005, pp. 257-262. doi:10.1016/j.ijbiomac.2005.04.007
P. Zioupos, J. D. Currey and A. J. Hamer, “The Role of Collagen in the Declining Mechanical Properties of Aging Human Cortical Bone,” Journal of Biomedical Meterials Research, Vol. 45, No. 2, 1999, pp. 108-116. doi:10.1002/(SICI)1097-4636(199905)45:2 3.0.CO;2-A
X. Wang, R. A. Bank, J. M. Te-Koppele and C. M. Agrawal, “The Role of Collagen in Determining Bone Mechanical Properties,” Journal of Orthopaedic Research, Vol. 19, No. 6, 2001, pp. 1021-1016. doi:10.1016/S0736-0266(01)00047-X
J. Y. Rho, P. Zioupos, J. D. Currey and G. M. Pharr, “Microstructural Elasticity and Regional Heterogeneity in Human Femoral Bone of Various Ages Examined by NanoIndentation,” Journal of Biomechanics, Vol. 35, No. 2, 2002, pp. 189-198. doi:10.1016/S0021-9290(01)00199-3
M. Raspanti, S. Guizzardi, V. De Pasquale, D. Martini and A. Ruggeri, “Ultrastructure of Heat-Deproteinated Compact Hone,” Biomaterials, Vol. 15, No. 6, 1994, pp. 433- 437. doi:10.1016/0142-9612(94)90222-4
J. L. Holden, J. G. Clement and P. P. Phakey, “Age and Temperature Related Changes to the Ultrastructure and Composition of Human Bone Mineral,” Journal of Bone and Mineral Research, Vol. 10, No. 9, 1995, pp. 1400-1409. doi:10.1002/jbmr.5650100918