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Yue Y, Hayashi R, Yokota Y. Co-Self-Assembly of Amphiphiles into Nanocomposite Hydrogels with Tailored Morphological and Mechanical Properties. ACS APPLIED MATERIALS & INTERFACES 2023; 15:21507-21516. [PMID: 37068768 PMCID: PMC10166085 DOI: 10.1021/acsami.3c01862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/28/2023] [Indexed: 05/05/2023]
Abstract
As one of the most amazing aspects of life, all living organisms are formed by self-assembly, a fundamental biological design process in which ordered nanostructures are assembled from small parts. For example, most of the biological tissues contain structurally soft and hard parts that are usually hierarchically organized at nano or micro levels to achieve specific functions. Hydrogels are one of the most promising soft materials owing to their potential applications in building of biological tissues and stretchable sensors. In this work, a series of hydrogels are synthesized through the co-self-assembly of two types of amphiphiles in their aqueous solution prior to polymerization. Soft and hard parts with nanostructures of different order parameters are incorporated into the hydrogels. The hydrophilic segment (as soft phases) of the polymer network provides water absorption, fluid flow, and softness, whereas the hydrophobic segment (as hard phases) provides strength and tearing and fracture resistance. Appropriate soft/hard nanostructures and their interfaces allow for the tailoring of the desired morphological and mechanical properties, including a different wetting ability, toughness, energy dissipation, self-recovery, and fracture resistance arising from their nanostructures. This work provides insights into the design of nanostructured anisotropic hydrogels with controlled morphological and mechanical properties.
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Affiliation(s)
- Youfeng Yue
- Research
Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology
(AIST), Tsukuba 305-8565, Japan
- Precursory
Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - Rika Hayashi
- Research
Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology
(AIST), Tsukuba 305-8565, Japan
| | - Yoshiko Yokota
- Research
Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology
(AIST), Tsukuba 305-8565, Japan
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2
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Al-Qudsy L, Hu YW, Xu H, Yang PF. Mineralized Collagen Fibrils: An Essential Component in Determining the Mechanical Behavior of Cortical Bone. ACS Biomater Sci Eng 2023; 9:2203-2219. [PMID: 37075172 DOI: 10.1021/acsbiomaterials.2c01377] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Bone comprises mechanically different materials in a specific hierarchical structure. Mineralized collagen fibrils (MCFs), represented by tropocollagen molecules and hydroxyapatite nanocrystals, are the fundamental unit of bone. The mechanical characterization of MCFs provides the unique adaptive mechanical competence to bone to withstand mechanical load. The structural and mechanical role of MCFs is critical in the deformation mechanisms of bone and the marvelous strength and toughness possessed by bone. However, the role of MCFs in the mechanical behavior of bone across multiple length scales is not fully understood. In the present study, we shed light upon the latest progress regarding bone deformation at multiple hierarchical levels and emphasize the role of MCFs during bone deformation. We propose the concept of hierarchical deformation of bone to describe the interconnected deformation process across multiple length scales of bone under mechanical loading. Furthermore, how the deterioration of bone caused by aging and diseases impairs the hierarchical deformation process of the cortical bone is discussed. The present work expects to provide insights on the characterization of MCFs in the mechanical properties of bone and lays the framework for the understanding of the multiscale deformation mechanics of bone.
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Affiliation(s)
- Luban Al-Qudsy
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, China
- Department of Medical Instrumentation Engineering Techniques, Electrical Engineering Technical College, Middle Technical University, 8998+QHJ Baghdad, Iraq
| | - Yi-Wei Hu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Huiyun Xu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, China
| | - Peng-Fei Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, China
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3
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Ofer L, Zaslansky P, Shahar R. A comparison of the structure, composition and mechanical properties of anosteocytic vertebrae of medaka (O. latipes) and osteocytic vertebrae of zebrafish (D. rerio). JOURNAL OF FISH BIOLOGY 2021; 98:995-1006. [PMID: 32239680 DOI: 10.1111/jfb.14334] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 03/06/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Medaka (O. latipes) and zebrafish (D. rerio) are two teleost fish increasingly used as models to study human skeletal diseases. Although they are similar in size, swimming pattern and many other characteristics, these two species are very distant from an evolutionary point of view (by at least 100 million years). A prominent difference between the skeletons of medaka and zebrafish is the total absence of osteocytes in medaka (anosteocytic), while zebrafish bone contains numerous osteocytes (osteocytic). This fundamental difference suggests the possibility that the bony elements of their skeleton may be different in a variety of other aspects, structural, mechanical or both, particularly in heavily loaded bones like the vertebrae. Here we report on the results of a comparative study that aimed to determine the similarities and differences in medaka and zebrafish vertebrae in terms of their macro- to nanostructure, composition and mechanical properties. Our results reveal many similarities between medaka and zebrafish vertebrae, making the lack or presence of osteocytes the only major difference between the bones of these two species.
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Affiliation(s)
- Lior Ofer
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Paul Zaslansky
- Department for Restorative and Preventive Dentistry, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | - Ron Shahar
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
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Mechanical Properties. Biomed Mater 2021. [DOI: 10.1007/978-3-030-49206-9_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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4D Printing of Origami Structures for Minimally Invasive Surgeries Using Functional Scaffold. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app11010332] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Origami structures have attracted attention in biomedical applications due to their ability to develop surgical tools that can be expanded from a minimal volume to a larger and functional device. On the other hand, four-dimensional (4D) printing is an emerging technology, which involves 3D printing of smart materials that can respond to external stimuli such as heat. This short communication introduces the proof of concept of merging origami and 4D printing technologies to develop minimally invasive delivery of functional biomedical scaffolds with high shape recovery. The shape-memory effect (SME) of the PLA filament and the origami designs were also assessed in terms of deformability and recovery rate. The results showed that herringbone tessellation origami structure combined with internal natural cancellous bone core satisfies the design requirement of foldable scaffolds. The substantial and consistent SME of the 4D printed herringbone tessellation origami, which exhibited 96% recovery compared to 61% for PLA filament, was the most significant discovery of this paper. The experiments demonstrated how the use of 4D printing in situ with origami structures could achieve reliable and repeatable results, therefore conclusively proving how 4D printing of origami structures can be applied to biomedical scaffolds.
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Bigham A, Kermani S, Saudi A, Aghajanian AH, Rafienia M. On the Bioactivity and Mechanical Properties of Gehlenite Nanobioceramic: A Comparative Study. JOURNAL OF MEDICAL SIGNALS & SENSORS 2020; 10:105-112. [PMID: 32676446 PMCID: PMC7359955 DOI: 10.4103/jmss.jmss_41_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/12/2019] [Accepted: 01/30/2020] [Indexed: 01/29/2023]
Abstract
Background: For a new biomaterial which is going to be applied in bone tissue regeneration, bioactivity (bone bonding ability) and desirable mechanical properties are very essential parameters to take into consideration. In the present study, the gehlenite's mechanical properties and bioactivity are assessed and compared with hydroxyapatite (HA) for bone tissue regeneration. Method: Gehlenite and HA nanoparticles are synthesized through sol–gel method and coprecipitation technique, respectively, and their physical and chemical properties are characterized through X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. Results: The results prove that the gehlenite and HA phases without any undesirable phase are obtained, and the particles of both compounds are in the nanometer range with spherical morphology. The compressive strength of both compounds are assessed, and the values for gehlenite and HA disks are 144 ± 5 and 150 ± 4.8 MPa, respectively. Next, their bioactivity potential is assessed into simulated body fluid (SBF) up to 21 days, and the results show that after 14 days, gehlenite disk's surface is completely covered with newly formed Ca-P particles. However, some sporadic precipitations after 21 days soaking into SBF are formed onto the HA disk's surface. Conclusion: This comparative study shows that nanostructured gehlenite disk with desirable mechanical properties and faster bioactivity kinetic than HA can be considered as a promising bioceramic for bone tissue regeneration.
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Affiliation(s)
- Ashkan Bigham
- Department of Materials Engineering, Advanced Materials Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran
| | - Saeed Kermani
- Department of Bioelectrics and Biomedical Engineering, School of Advanced Technologies in Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.,Medical Image and Signal Processing Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ahmad Saudi
- Student Research Committee, School of Advanced Medical Technologies in Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Amir Hamed Aghajanian
- Department of Materials Engineering, Faculty of Engineering, Razi University, Kermanshah, Iran
| | - Mohammad Rafienia
- Biosensor Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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Wright ZM, Arnold AM, Holt BD, Eckhart KE, Sydlik SA. Functional Graphenic Materials, Graphene Oxide, and Graphene as Scaffolds for Bone Regeneration. REGENERATIVE ENGINEERING AND TRANSLATIONAL MEDICINE 2018. [DOI: 10.1007/s40883-018-0081-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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8
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Holt BD, Wright ZM, Arnold AM, Sydlik SA. Graphene oxide as a scaffold for bone regeneration. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2016; 9. [PMID: 27781398 DOI: 10.1002/wnan.1437] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/26/2016] [Accepted: 09/06/2016] [Indexed: 12/12/2022]
Abstract
Graphene oxide (GO), the oxidized form of graphene, holds great potential as a component of biomedical devices, deriving utility from its ability to support a broad range of chemical functionalities and its exceptional mechanical, electronic, and thermal properties. GO composites can be tuned chemically to be biomimetic, and mechanically to be stiff yet strong. These unique properties make GO-based materials promising candidates as a scaffold for bone regeneration. However, questions still exist as to the compatibility and long-term toxicity of nanocarbon materials. Unlike other nanocarbons, GO is meta-stable, water dispersible, and autodegrades in water on the timescale of months to humic acid-like materials, the degradation products of all organic matter. Thus, GO offers better prospects for biological compatibility over other nanocarbons. Recently, many publications have demonstrated enhanced osteogenic performance of GO-containing composites. Ongoing work toward surface modification or coating strategies could be useful to minimize the inflammatory response and improve compatibility of GO as a component of medical devices. Furthermore, biomimetic modifications could offer mechanical and chemical environments that encourage osteogenesis. So long as care is given to assure their safety, GO-based materials may be poised to become the next generation scaffold for bone regeneration. WIREs Nanomed Nanobiotechnol 2017, 9:e1437. doi: 10.1002/wnan.1437 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Brian D Holt
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Zoe M Wright
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Anne M Arnold
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Stefanie A Sydlik
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
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9
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Spiesz EM, Zysset PK. Structure–mechanics relationships in mineralized tendons. J Mech Behav Biomed Mater 2015; 52:72-84. [DOI: 10.1016/j.jmbbm.2015.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 03/19/2015] [Accepted: 03/23/2015] [Indexed: 01/07/2023]
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10
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Lefèvre E, Lasaygues P, Baron C, Payan C, Follet H, Pithioux M. Ultrasonic assessment of diagonal stiffness coefficients in children cortical bone. Comput Methods Biomech Biomed Engin 2015; 18 Suppl 1:1978-9. [DOI: 10.1080/10255842.2015.1070587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- E. Lefèvre
- Aix-Marseille Université, CNRS, ISM UMR 7287, Marseille, France
- APHM, Institute for Locomotion, Sainte-Marguerite Hospital, Marseille, France
| | - P. Lasaygues
- Laboratory of Mechanics and Acoustics, UPR CNRS 7051, Aix-Marseille University, Marseille, France
| | - C. Baron
- Aix-Marseille Université, CNRS, ISM UMR 7287, Marseille, France
- APHM, Institute for Locomotion, Sainte-Marguerite Hospital, Marseille, France
| | - C. Payan
- Laboratory of Mechanics and Acoustics, UPR CNRS 7051, Aix-Marseille University, Marseille, France
| | - H. Follet
- INSERM, UMR 1033, University of Lyon, Lyon, France
| | - M. Pithioux
- Aix-Marseille Université, CNRS, ISM UMR 7287, Marseille, France
- APHM, Institute for Locomotion, Sainte-Marguerite Hospital, Marseille, France
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11
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Lefèvre E, Lasaygues P, Baron C, Payan C, Launay F, Follet H, Pithioux M. Analyzing the anisotropic Hooke׳s law for children׳s cortical bone. J Mech Behav Biomed Mater 2015; 49:370-7. [DOI: 10.1016/j.jmbbm.2015.05.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/13/2015] [Accepted: 05/17/2015] [Indexed: 11/25/2022]
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12
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Blouin S, Puchegger S, Roschger A, Berzlanovich A, Fratzl P, Klaushofer K, Roschger P. Mapping dynamical mechanical properties of osteonal bone by scanning acoustic microscopy in time-of-flight mode. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:924-936. [PMID: 24725753 DOI: 10.1017/s1431927614000646] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An important determinant of mechanical properties of bone is Young's modulus and its variation in individual osteons of cortical bone tissue. Its mechanical behavior also depends on deformation rate owing to its visco- or poroelastic properties. We developed a method to measure dynamical mechanical properties of bulk bone tissue at osteonal level based on scanning acoustic microscopy (SAM) using time-of-flight (TOF) measurements in combination with quantitative backscattered electron imaging (qBEI). SAM-TOF yields local sound velocities and qBEI corresponding material densities together providing elastic properties. Osteons (n=55) were measured in three human femoral diaphyseal ground bone sections (∼ 30 µm in thickness). In addition, subchondral bone and mineralized articular cartilage were investigated. The mean mineral contents, the mean sound velocities, and the mean elastic modulus of the osteons ranged from 20 to 26 wt%, from 3,819 to 5,260 m/s, and from 21 to 44 GPa, respectively. There was a strong positive correlation between material density and sound velocity (Pearson's r=0.701; p<0.0001) of the osteons. Sound velocities between cartilage and bone was similar, though material density was higher in cartilage (+4.46%, p<0.0001). These results demonstrate the power of SAM-TOF to estimate dynamic mechanical properties of the bone materials at the osteonal level.
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Affiliation(s)
- Stéphane Blouin
- 11st Medical Department,Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling,Hanusch Hospital,Heinrich Collin Str. 30,A-1140 Vienna,Austria
| | - Stephan Puchegger
- 2Faculty of Physics,University of Vienna,Dynamics of Condensed Systems,Strudlhofgasse 4,A-1090 Vienna,Austria
| | - Andreas Roschger
- 11st Medical Department,Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling,Hanusch Hospital,Heinrich Collin Str. 30,A-1140 Vienna,Austria
| | - Andrea Berzlanovich
- 3Department of Forensics,Medical University of Vienna,Sensengasse 2,A-1090 Vienna,Austria
| | - Peter Fratzl
- 4Department of Biomaterials,Max Planck Institute of Colloids and Interfaces,14424 Potsdam,Germany
| | - Klaus Klaushofer
- 11st Medical Department,Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling,Hanusch Hospital,Heinrich Collin Str. 30,A-1140 Vienna,Austria
| | - Paul Roschger
- 11st Medical Department,Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling,Hanusch Hospital,Heinrich Collin Str. 30,A-1140 Vienna,Austria
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Elastic properties of collagen in bone determined by measuring the Debye-Waller factor. J Biomech 2013; 46:2824-30. [PMID: 24090493 DOI: 10.1016/j.jbiomech.2013.08.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 08/23/2013] [Accepted: 08/31/2013] [Indexed: 11/20/2022]
Abstract
Force constant values for thermal vibrational motion of a collagen molecule along the helix axis in tendon, completely demineralized bone (CDB), and partially demineralized bone (PDB) were estimated by determining the Debye-Waller factor (DW factor) for the diffracted X-ray intensity from these specimens. The DW factor for nominal value of 0.286nm meridional diffraction representing a period along the helical axis of a collagen molecule was measured. As the atomic scattering factor of mineral constituents is much larger than that of collagen, it is difficult to detect the diffraction from collagen in bone specimen. Therefore, PDB was used in this study. In order to compare obtained force constant value for CDB with mechanical properties of collagen in the literature, the value was translated into Young's modulus value using the cross-sectional area of a collagen molecule. In the case of collagen in PDB, i.e., collagen with the close presence of HAp mineral particles, as the DW factor of the diffracted intensity by hydroxyapatite (HAp) was considered to be negligible compared with that of collagen, the DW factor determined was interpreted as that of collagen molecule in PDB specimen. The force constant value obtained for collagen in PDB was significantly larger than that of collagen in CDB. This result was thought to be a manifestation of the hardening of collagen matrix in bone by HAp mineral particles and the first straightforward evidence for a difference in collagen properties depending on the presence of HAp mineral particles. The method employed in this study can be utilized for detecting mechanical properties of the individual constituents of composite materials.
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Leng H, Reyes MJ, Dong NX, Wang X. Effect of age on mechanical properties of the collagen phase in different orientations of human cortical bone. Bone 2013; 55:288-91. [PMID: 23598045 PMCID: PMC3679220 DOI: 10.1016/j.bone.2013.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/11/2013] [Accepted: 04/09/2013] [Indexed: 10/27/2022]
Abstract
The collagen phase plays an important role in mechanical behaviors of cortical bone. However, aging effects on the mechanical behavior of the collagen phase is still poorly understood. In this study, micro-tensile tests were performed on demineralized human cortical bone samples from young, middle-aged, and elderly donors and aging effects on the mechanical properties of the collagen phase in different orientations (i.e. longitudinal and transverse directions of bone) were examined. The results of this study indicated that the elastic modulus and ultimate strength of the demineralized bone specimens decreased with aging in both the longitudinal and transverse orientations. However, the failure strain exhibited no significant changes in both orientations regardless of aging. These results suggest that the stiffness and strength of the collagen phase in bone are deteriorated with aging in both longitudinal and transverse directions. However, the aging effect is not reflected in the failure strain of the collagen phase in both longitudinal and transverse orientations, implying that the maximum sustainable deformation of the collagen phase is independent of aging and orientation.
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Affiliation(s)
- Huijie Leng
- Department of Orthopaedics, Peking University Third Hospital
| | | | - Neil X Dong
- Mechanical Engineering, University of Texas at Tyler
| | - Xiaodu Wang
- Mechanical Engineering, University of Texas at San Antonio
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15
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Novitskaya E, Lee S, Lubarda VA, McKittrick J. Initial anisotropy in demineralized bovine cortical bone in compressive cyclic loading-unloading. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:817-23. [PMID: 25427492 DOI: 10.1016/j.msec.2012.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 10/02/2012] [Accepted: 11/04/2012] [Indexed: 10/27/2022]
Abstract
The mechanical properties of demineralized bovine cortical femur bone were investigated by cyclic loading-unloading compression in three anatomical directions (longitudinal, radial, transverse) within the physiological strain range. The loading responses in the radial and transverse directions were nearly linear up to 2% strain, while the response in longitudinal direction was strongly non-linear in that range. The unloading responses were non-linear for each anatomical direction, giving rise to overall loading-unloading hysteresis and cyclic dissipation of energy. The mechanical properties were observed to be anisotropic: the radial direction was found to be the most energy dissipative, while the longitudinal direction appeared to be the stiffest bone direction. The cyclic loading mostly affects the bone stiffness in the radial and transverse directions, while the longitudinal direction was found to be the least affected. These anisotropic properties can be attributed to the differences in collagen fibers alignment and different microstructural architecture in three different anatomical bone directions.
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Affiliation(s)
- Ekaterina Novitskaya
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Steve Lee
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Vlado A Lubarda
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Joanna McKittrick
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA; Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA
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16
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Baumann AP, Deuerling JM, Rudy DJ, Niebur GL, Roeder RK. The relative influence of apatite crystal orientations and intracortical porosity on the elastic anisotropy of human cortical bone. J Biomech 2012; 45:2743-9. [DOI: 10.1016/j.jbiomech.2012.09.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 09/05/2012] [Accepted: 09/06/2012] [Indexed: 10/27/2022]
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17
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Singhal A, Almer J, Dunand D. Variability in the nanoscale deformation of hydroxyapatite during compressive loading in bovine bone. Acta Biomater 2012; 8:2747-58. [PMID: 22465576 DOI: 10.1016/j.actbio.2012.03.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 03/10/2012] [Accepted: 03/21/2012] [Indexed: 11/27/2022]
Abstract
High-energy synchrotron X-ray diffraction is used to study in situ elastic strains in hydroxyapatite (HAP) for bovine femur cortical bone subjected to uniaxial compressive loading. Load-unload tests at room temperature (27°C) and body temperature (37°C) show that the load transfer to the stiff nanosized HAP platelets from the surrounding compliant protein matrix does not vary significantly (p<0.05) with temperature. This emphasizes that the stiffness of bone is controlled by the stiffness of the HAP phase, which remains unaffected by this change in temperature. Both the extent of hysteresis and the residual value of internal strains developed in HAP during load-unload cycling from 0 to -100 MPa increase significantly (p<0.05) with the number of loading cycles, indicative of strain energy dissipation and accumulation of permanent deformation. Monotonic loading tests, conducted at body temperature to determine the spatial variation of properties within the femur, illustrate that the HAP phase carries lower strain (and thus stresses) at the anterio-medial aspect of the femur than at the anterio-lateral aspect. This is correlated to higher HAP volume fractions in the former location (p<0.05). The Young's modulus of the bone is also found to correlate with the HAP volume fraction and porosity (p<0.05). Finally, samples with a primarily plexiform microstructure are found to be stiffer than those with a primarily Haversian microstructure (p<0.05).
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18
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Yamamoto K, Nakatsuji T, Yaoi Y, Yamato Y, Yanagitani T, Matsukawa M, Yamazaki K, Matsuyama Y. Relationships between the anisotropy of longitudinal wave velocity and hydroxyapatite crystallite orientation in bovine cortical bone. ULTRASONICS 2012; 52:377-386. [PMID: 22014464 DOI: 10.1016/j.ultras.2011.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 09/03/2011] [Accepted: 09/14/2011] [Indexed: 05/31/2023]
Abstract
Quantitative ultrasound (QUS) is now widely used for evaluating bone in vivo, because obtained ultrasonic wave properties directly reflect the visco-elasticity. Bone tissue is composed of minerals like hydroxyapatite (HAp) and a collagen matrix. HAp crystallites orientation is thus one parameter of bone elasticity. In this study, we experimentally investigated the anisotropy of ultrasonic wave velocity and the HAp crystallites orientation in the axial-radial and axial-tangential planes in detail, using cylindrical specimens obtained from the cortical bone of three bovine femurs. Longitudinal bulk wave propagation was investigated by using a conventional ultrasonic pulse system. We used the one cycle of sinusoidal pulse which was emitted from wide band transmitter. The nominal frequency of the pulse was 1MHz. First, we investigated the anisotropy of longitudinal wave velocity, measuring the anisotropy of velocity in two planes using cylindrical specimens obtained from identical bone areas. The wave velocity changed due to the rotation angle, showing the maximum value in the direction a little off the bone axis. Moreover, X-ray pole figure measurements also indicated that there were small tilts in the HAp crystallites orientation from the bone axis. The tilt angles were similar to those of the highest velocity direction. There were good correlations between velocity and HAp crystallites orientation obtained in different directions. However, a comparatively low correlation was found in posterior bone areas, which shows the stronger effects of bone microstructure. In the radial-tangential plane, where the HAp crystallites hardly ever align, weak anisotropy of velocity was found which seemed to depend on the bone microstructure.
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Affiliation(s)
- Kazufumi Yamamoto
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashiku, Hamamatsu, Shizuoka 431-3192, Japan
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Novitskaya E, Chen PY, Lee S, Castro-Ceseña A, Hirata G, Lubarda VA, McKittrick J. Anisotropy in the compressive mechanical properties of bovine cortical bone and the mineral and protein constituents. Acta Biomater 2011; 7:3170-7. [PMID: 21571104 DOI: 10.1016/j.actbio.2011.04.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 04/01/2011] [Accepted: 04/26/2011] [Indexed: 11/18/2022]
Abstract
The mechanical properties of fully demineralized, fully deproteinized and untreated cortical bovine femur bone were investigated by compression testing in three anatomical directions (longitudinal, radial and transverse). The weighted sum of the stress-strain curves of the treated bones was far lower than that of the untreated bone, indicating a strong molecular and/or mechanical interaction between the collagen matrix and the mineral phase. Demineralization and deproteinization of the bone demonstrated that contiguous, stand-alone structures result, showing that bone can be considered an interpenetrating composite material. Structural features of the samples from all groups were studied by optical and scanning electron microscopy. Anisotropic mechanical properties were observed: the radial direction was found to be the strongest for untreated bone, while the longitudinal one was found to be the strongest for deproteinized and demineralized bones. A possible explanation for this phenomenon is the difference in bone microstructure in the radial and longitudinal directions.
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Affiliation(s)
- Ekaterina Novitskaya
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA.
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20
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Rudy DJ, Deuerling JM, Espinoza Orías AA, Roeder RK. Anatomic variation in the elastic inhomogeneity and anisotropy of human femoral cortical bone tissue is consistent across multiple donors. J Biomech 2011; 44:1817-20. [PMID: 21543070 DOI: 10.1016/j.jbiomech.2011.04.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 04/05/2011] [Accepted: 04/06/2011] [Indexed: 11/19/2022]
Abstract
Numerical models commonly account for elastic inhomogeneity in cortical bone using power-law scaling relationships with various measures of tissue density, but limited experimental data exists for anatomic variation in elastic anisotropy. A recent study revealed anatomic variation in the magnitude and anisotropy of elastic constants along the entire femoral diaphysis of a single human femur (Espinoza Orías et al., 2009). The objective of this study was to confirm these trends across multiple donors while also considering possible confounding effects of the anatomic quadrant, apparent tissue density, donor age, and gender. Cortical bone specimens were sampled from the whole femora of 9 human donors at 20%, 50%, and 80% of the total femur length. Elastic constants from the main diagonal of the reduced fourth-order tensor were measured on hydrated specimens using ultrasonic wave propagation. The tissue exhibited orthotropy overall and at each location along the length of the diaphysis (p < 0.0001). Elastic anisotropy increased from the mid-diaphysis toward the epiphyses (p < 0.05). The increased elastic anisotropy was primarily caused by a decreased radial elastic constant (C(11)) from the mid-diaphysis toward the epiphyses (p < 0.05), since differences in the circumferential (C(22)) and longitudinal (C(33)) elastic constants were not statistically significant (p > 0.29). Anatomic variation in intracortical porosity may account for these trends, but requires further investigation. The apparent tissue density was positively correlated with the magnitude of each elastic constant (p < 0.0001, R(2) > 0.46), as expected, but was only weakly correlated with C(33)/C(11) (p < 0.05, R(2) = 0.04) and not significantly correlated with C(33)/C(22) and C(11)/C(22).
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Affiliation(s)
- David J Rudy
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, United States
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21
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Chen PY, Toroian D, Price PA, McKittrick J. Minerals form a continuum phase in mature cancellous bone. Calcif Tissue Int 2011; 88:351-61. [PMID: 21274705 PMCID: PMC3075393 DOI: 10.1007/s00223-011-9462-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 12/29/2010] [Indexed: 11/09/2022]
Abstract
Bone is a hierarchically structured composite consisting of a protein phase (type I collagen) and a mineral phase (carbonated apatite). The objective of this study was to investigate the hierarchical structure of mineral in mature bone. A method to completely deproteinize bone without altering the original structure is developed, and the completion is confirmed by protein analysis techniques. Stereoscopy and field emission electron microscopy are used to examine the structural features from submillimeter- to micrometer- to nanometer-length scales of bovine femur cancellous bone. Stereoscopic images of fully deproteinized and demineralized bovine femur cancellous bone samples show that fine trabecular architecture is unaltered and the microstructural features are preserved, indicating the structural integrity of mineral and protein constituents. SEM revealed that bone minerals are fused together and form a sheet-like structure in a coherent manner with collagen fibrils. Well-organized pore systems are observed at varying hierarchical levels. Mineral sheets are peeled off and folded after compressive deformation, implying strong connection between individual crystallites. Results were compared with commercially available heat-deproteinized bone (Bio-Oss(®)), and evidence showed consistency in bone mineral structure. A two-phase interpenetrating composite model of mature bone is proposed and discussed.
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Affiliation(s)
- Po-Yu Chen
- Materials Science and Engineering Program, Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411 USA
| | - Damon Toroian
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0322 USA
| | - Paul A. Price
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0322 USA
| | - Joanna McKittrick
- Materials Science and Engineering Program, Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411 USA
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22
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Post-yield nanomechanics of human cortical bone in compression using synchrotron X-ray scattering techniques. J Biomech 2010; 44:676-82. [PMID: 21112589 DOI: 10.1016/j.jbiomech.2010.11.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 11/01/2010] [Accepted: 11/02/2010] [Indexed: 11/23/2022]
Abstract
The ultrastructural response to applied loads governs the post-yield deformation and failure behavior of bone, and is correlated with bone fragility fractures. Combining a novel progressive loading protocol and synchrotron X-ray scattering techniques, this study investigated the correlation of the local deformation (i.e., internal strains of the mineral and collagen phases) with the bulk mechanical behavior of bone. The results indicated that the internal strains of the longitudinally oriented collagen fibrils and mineral crystals increased almost linearly with respect to the macroscopic strain prior to yielding, but markedly decreased first and then gradually leveled off after yielding. Similar changes were also observed in the applied stress before and after yielding of bone. However, the collagen to mineral strain ratio remained nearly constant throughout the loading process. In addition, the internal strains of longitudinal mineral and collagen phases did not exhibit a linear relationship with either the modulus loss or the plastic deformation of bulk bone tissue. Finally, the time-dependent response of local deformation in the mineral phase was observed after yielding. Based on the results, we speculate that the mineral crystals and collagen fibrils aligned with the loading axis only partially explain the post-yield deformation, suggesting that shear deformation involving obliquely oriented crystals and fibrils (off axis) is dominant mechanism of yielding for human cortical bone in compression.
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Deuerling JM, Yue W, Espinoza Orías AA, Roeder RK. Specimen-specific multi-scale model for the anisotropic elastic constants of human cortical bone. J Biomech 2009; 42:2061-7. [PMID: 19664772 DOI: 10.1016/j.jbiomech.2009.06.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 05/29/2009] [Accepted: 06/02/2009] [Indexed: 11/30/2022]
Abstract
The anisotropic elastic constants of human cortical bone were predicted using a specimen-specific micromechanical model that accounted for structural parameters across multiple length scales. At the nano-scale, the elastic constants of the mineralized collagen fibril were estimated from measured volume fractions of the constituent phases, namely apatite crystals and Type I collagen. The elastic constants of the extracellular matrix (ECM) were predicted using the measured orientation distribution function (ODF) for the apatite crystals to average the contribution of misoriented mineralized collagen fibrils. Finally, the elastic constants of cortical bone tissue were determined by accounting for the measured volume fraction of Haversian porosity within the ECM. Model predictions using the measured apatite crystal ODF were not statistically different from experimental measurements for both the magnitude and anisotropy of elastic constants. In contrast, model predictions using common idealized assumptions of perfectly aligned or randomly oriented apatite crystals were significantly different from the experimental measurements. A sensitivity analysis indicated that the apatite crystal volume fraction and ODF were the most influential structural parameters affecting model predictions of the magnitude and anisotropy, respectively, of elastic constants.
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Affiliation(s)
- Justin M Deuerling
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, United States of America
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24
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Biomaterials: Processing, Characterization, and Applications. Biomed Mater 2009. [DOI: 10.1007/978-0-387-84872-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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TODOH M, TADANO S, GIRI B, NISHIMOTO M. Effect of Gradual Demineralization on the Mineral Fraction and Mechanical Properties of Cortical Bone. ACTA ACUST UNITED AC 2009. [DOI: 10.1299/jbse.4.230] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Masahiro TODOH
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
| | - Shigeru TADANO
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
| | - Bijay GIRI
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
| | - Masahiro NISHIMOTO
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University
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26
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Gupta H, Zioupos P. Fracture of bone tissue: The ‘hows’ and the ‘whys’. Med Eng Phys 2008; 30:1209-26. [DOI: 10.1016/j.medengphy.2008.09.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 09/01/2008] [Accepted: 09/02/2008] [Indexed: 11/25/2022]
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27
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Espinoza Orías AA, Deuerling JM, Landrigan MD, Renaud JE, Roeder RK. Anatomic variation in the elastic anisotropy of cortical bone tissue in the human femur. J Mech Behav Biomed Mater 2008; 2:255-63. [PMID: 19627830 DOI: 10.1016/j.jmbbm.2008.08.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 07/14/2008] [Accepted: 08/28/2008] [Indexed: 10/21/2022]
Abstract
Experimental investigations for anatomic variation in the magnitude and anisotropy of elastic constants in human femoral cortical bone tissue have typically focused on a limited number of convenient sites near the mid-diaphysis. However, the proximal and distal ends of the diaphysis are more clinically relevant to common orthopaedic procedures and interesting mechanobiology. Therefore, the objective of this study was to measure anatomic variation in the elastic anisotropy and inhomogeneity of human cortical bone tissue along the entire length (15%-85% of the total femur length), and around the periphery (anterior, medial, posterior and lateral quadrants) of the femoral diaphysis, using ultrasonic wave propagation in the three orthogonal specimen axes. The elastic symmetry of tissue in the distal and extreme proximal portions of the diaphysis (15%-45% and 75%-85% of the total femur length, respectively) was, at most, orthotropic. In contrast, the elastic symmetry of tissue near the mid- and proximal mid-diaphysis (50%-70% of the total femur length) was reasonably approximated as transversely isotropic. The magnitudes of elastic constants generally reached maxima near the mid- and proximal mid-diaphysis in the lateral and medial quadrants, and decreased toward the epiphyses, as well as the posterior and anterior quadrants. The elastic anisotropy ratio in the longitudinal and radial anatomic axes showed the opposite trends. These variations were significantly correlated with the apparent tissue density, as expected. In summary, the human femur exhibited statistically significant anatomic variation in elastic anisotropy, which may have important implications for whole bone numerical models and mechanobiology.
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Affiliation(s)
- Alejandro A Espinoza Orías
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, United States
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28
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Ruppel ME, Miller LM, Burr DB. The effect of the microscopic and nanoscale structure on bone fragility. Osteoporos Int 2008; 19:1251-65. [PMID: 18317862 DOI: 10.1007/s00198-008-0579-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 01/25/2008] [Indexed: 12/20/2022]
Abstract
Bone mineral density is the gold-standard for assessing bone quantity and diagnosing osteoporosis. Although bone mineral density measurements assess the quantity of bone, the quality of the tissue is an important predictor of fragility. Understanding the macro- and nanoscale properties of bone is critical to understanding bone fragility in osteoporosis. Osteoporosis is a disease that affects more than 75 million people worldwide. The gold standard for osteoporosis prognosis, bone mineral density, primarily measures the quantity of bone in the skeleton, overlooking more subtle aspects of bone's properties. Bone quality, a measure of bone's architecture, geometry and material properties, is evaluated via mechanical, structural and chemical testing. Although decreased BMD indicates tissue fragility at the clinical level, changes in the substructure of bone can help indicate how bone quality is altered in osteoporosis. Additionally, mechanical properties which can quantify fragility, or bone's inability to resist fracture, can be changed due to alterations in bone architecture and composition. Recent studies have focused on examination of bone on the nanoscale, suggesting the importance of understanding the interactions of the mineral crystals and collagen fibrils and how they can alter bone quality. It is therefore important to understand alterations in bone that occur at the macro-, micro- and nanoscopic levels to determine what parameters contribute to decreased bone quality in diseased tissue.
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Affiliation(s)
- M E Ruppel
- Department of Biomedical Engineering, State University of New York-Stony Brook, Stony Brook, NY 11794, USA
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29
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Raum K. Microelastic imaging of bone. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2008; 55:1417-1431. [PMID: 18986931 DOI: 10.1109/tuffc.2008.817] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Several high-frequency ultrasound techniques have been developed during the last decade with the intention of assessing elastic properties of bone at the tissue level. The basic measurement principles can be divided into: 1) measurement of the compressional wave velocity in thin tissue sections; 2) measurement of surface acoustic wave velocities in thick sections; and 3) derivation of the acoustic impedance from the confocal reflection amplitude in thick sections. In this paper, the 3 principles are described with example measurements given in the frequency range from 50 MHz to 1.2 GHz. The measurements were made with 2 microscopes operating in the pulse-echo mode, either with frequencies up to 200 MHz and time-resolved detection or between 100 MHz and 2 GHz and amplitude detection. The methods are compared and their application potentials and limitations are discussed with respect to the hierarchical structure of cortical bone. Mapping of the confocal reflection amplitude has superior capabilities for deriving quantitative elastic and structural parameters in the heterogeneous bone material. Even at low frequencies (50 MHz), the mineralized tissue matrix can be separated from the larger pores (Haversian canals), and the elastic coefficient in the probing direction can be measured in 2 dimensions. Depending on the type of sample surface preparation (flat or cylindrically shaped), local distribution of a single elastic coefficient or the average transverse isotropic stiffness tensor can be derived. With frequencies in the GHz range, the lamellar bone structure can be analyzed. However, at one GHz, the acoustic wavelength is still one order of magnitude larger than the individual mineralized collagen fibrils. Although the thickness of a lamellar unit can easily be assessed from the acoustic image, the derivation of the anisotropic elastic properties of the mineralized collagen fibrils as well as the detailed structure of a lamella can only be accomplished with further model assumptions.
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Affiliation(s)
- K Raum
- Dept. of Orthopedics, Martin Luther Univ. of Halle-Wittenberg, Halle, Germany.
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30
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Kashii M, Hashimoto J, Nakano T, Umakoshi Y, Yoshikawa H. Alendronate treatment promotes bone formation with a less anisotropic microstructure during intramembranous ossification in rats. J Bone Miner Metab 2008; 26:24-33. [PMID: 18095060 DOI: 10.1007/s00774-007-0782-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Accepted: 05/29/2007] [Indexed: 10/22/2022]
Abstract
There are safety concerns regarding administration of bisphosphonates to children. Little is known about the effects of bisphosphonates on bone matrix organization during bone modeling. The present study examined the effects of alendronate (ALN) on bone matrices formed by intramembranous ossification in the appendicular growing skeleton. ALN was administered to 1-week-old Sprague-Dawley rats at a dose of 0, 35, or 350 microg/kg/week for 4 or 8 weeks. The position of femoral diaphysis formed exclusively by intramembranous ossification was identified, and cross sections of cortical bone at this position were analyzed. Bone mineral density (BMD) and geometric parameters were evaluated using peripheral quantitative computed tomography. The preferential orientation degree of biological apatite (BAp) crystals in the bone longitudinal direction, which shows the degree of bone matrix anisotropy, was evaluated using microbeam X-ray diffraction analysis. We analyzed bone histomorphometrical parameters and performed bone nanomechanical tests to examine the material properties of newly developing cortical bone. The preferential orientation degree of BAp crystals significantly decreased in 35 microg/kg/week ALN-treated groups compared with vehicle-treated groups, although there were no significant differences in BMD between the two groups. The periosteal mineral apposition rate significantly increased in the 35 microg/kg/week ALN-treated group. We found a high negative correlation between bone matrix anisotropy and the regional periosteal mineral apposition rate (r = -0.862, P < 0.001). Nanomechanical tests revealed that 35 microg/kg/week ALN administration caused deterioration of the material properties of the bone microstructure. These new findings suggest that alendronate affects bone matrix organization and promotes bone formation with a less anisotropic microstructure during intramembranous ossification.
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Affiliation(s)
- Masafumi Kashii
- Department of Orthopedic Surgery, Faculty of Medicine, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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31
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Baron C, Talmant M, Laugier P. Effect of porosity on effective diagonal stiffness coefficients (cii) and elastic anisotropy of cortical bone at 1 MHz: a finite-difference time domain study. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2007; 122:1810. [PMID: 17927440 DOI: 10.1121/1.2759165] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Finite-difference time domain (FDTD) numerical simulations coupled to real experimental data were used to investigate the propagation of 1 MHz pure bulk wave propagation through models of cortical bone microstructures. Bone microstructures were reconstructed from three-dimensional high resolution synchrotron radiation microcomputed tomography (SR-muCT) data sets. Because the bone matrix elastic properties were incompletely documented, several assumptions were made. Four built-in bone matrix models characterized by four different anisotropy ratios but the same Poisson's ratios were tested. Combining them with the reconstructed microstructures in the FDTD computations, effective stiffness coefficients were derived from simulated bulk-wave velocity measurements. For all the models, all the effective compression and shear bulk wave velocities were found to decrease when porosity increases. However, the trend was weaker in the axial direction compared to the transverse directions, contributing to the increase of the effective anisotropy. On the other hand, it was shown that the initial Poisson's ratio value may substantially affect the variations of the effective stiffness coefficients. The present study can be used to elaborate sophisticated macroscopic computational bone models incorporating realistic CT-based macroscopic bone structures and effective elastic properties derived from muCT-based FDTD simulations including the cortical porosity effect.
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Affiliation(s)
- Cécile Baron
- Université Pierre et Marie Curie-Paris 6, Laboratoire d'Imagerie Paramétrique, Paris F-75005, France.
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32
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Lakshmanan S, Bodi A, Raum K. Assessment of anisotropic tissue elasticity of cortical bone from high-resolution, angular acoustic measurements. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2007; 54:1560-70. [PMID: 17703659 DOI: 10.1109/tuffc.2007.426] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Assessment of anisotropic elastic properties at the tissue level is still one of the major challenges in bone research. In previous studies, bone sections were cut in different directions relative to a principle axis of symmetry. This causes a high preparation and measurement effort. We have developed a new acoustic scanning procedure that allows one to measure the angular dependence of the acoustic impedance of cylindrically shaped samples (diameter: 4.4 mm) with a single measurement. Our scanning acoustic microscope was equipped with a rotational stage, and a scanning procedure was developed that measures the surface reflection of the rotating cylinder. It was shown in a previous study that the acoustic impedance derived from the reflection coefficient is highly correlated with the elastic coefficient in the probing direction. From the angular reflection, the independent elastic coefficients were derived using assumptions of transverse isotropy and continuum micromechanical model constraints. This method was applied to the inspection of human femoral bone samples. Four cylinders were prepared from the anterior, posterior, medial, and lateral regions. The measurements were performed with a 50 MHz transducer, providing a lateral resolution of 23 microm. Remarkable structural and elastic variations were observed between the four samples. The means and standard deviations of the derived elastic coefficients were: c33 = 29.9 +/- 5.0 GPa, c11 = 21.9 +/- 2.1 GPa, c12 = 9.2 +/- 1.5 GPa, c13 = 9.7 +/- 1.6 GPa, and c44 = 6.7 +/- 1.2 GPa. The results demonstrate that microstructural and anisotropic elastic tissue parameters can be assessed by ultrasound in very small bone samples.
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Affiliation(s)
- Sannachi Lakshmanan
- Department of Orthopedics, Medical Faculty, Martin Luther University of Halle-Wittenberg, Magdeburger Strasse 22, 06097 Halle, Germany
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33
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Converse GL, Yue W, Roeder RK. Processing and tensile properties of hydroxyapatite-whisker-reinforced polyetheretherketone. Biomaterials 2007; 28:927-35. [PMID: 17113143 DOI: 10.1016/j.biomaterials.2006.10.031] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Accepted: 10/30/2006] [Indexed: 11/17/2022]
Abstract
Polyetheretherketone (PEEK) was reinforced with 0-50 vol% hydroxyapatite (HA) whiskers using a novel powder processing and compression molding technique which enabled uniform mixing at high whisker content. Texture analysis showed that viscous flow during compression molding produced a preferred orientation of whiskers along the specimen tensile axis. Consequently, the elastic modulus or ultimate tensile strength of HA-whisker-reinforced PEEK was able to be tailored to mimic human cortical bone. PEEK reinforced with 40 and 50 vol% HA whiskers exhibited elastic moduli of 17 and 23 GPa, respectively. Elastic constants were measured using ultrasonic wave propagation and revealed an orthotropic anisotropy also similar to that measured in human cortical bone. PEEK reinforced with 10 and 20 vol% HA whiskers exhibited an ultimate tensile strength of 90 and 75 MPa, respectively. Tensile specimen fracture surfaces showed evidence of brittle failure in both reinforced and un-reinforced PEEK. Whisker pullout was observed with PEEK adhered to HA whiskers, suggesting a relatively strong interface between the PEEK matrix and HA whisker reinforcements.
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Affiliation(s)
- Gabriel L Converse
- Department of Aerospace and Mechanical Engineering, The University of Notre Dame, Notre Dame, IN 46556, USA
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34
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Hube R, Mayr H, Hein W, Raum K. Prediction of biomechanical stability after callus distraction by high resolution scanning acoustic microscopy. ULTRASOUND IN MEDICINE & BIOLOGY 2006; 32:1913-21. [PMID: 17169703 DOI: 10.1016/j.ultrasmedbio.2006.06.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 06/05/2006] [Accepted: 06/15/2006] [Indexed: 05/13/2023]
Abstract
Accurate clinical prediction of the resistance to fracture after callus distraction requires a detailed understanding of structural and elastic properties of the newly formed bone. We investigated 26 sheep that underwent middiaphyseal callus distraction at a rate of 0.5 mm every 12 h for 30 d using a standard unilateral fixator system. The sample population included four groups undergoing different treatments to improve bone healing, including bone grafting and the local application of growth factors. All animals were sacrificed eight weeks after the end of distraction. The fracture forces of the lengthened tibia and the contralateral control tibia from each animal were evaluated by biomechanical (four-point bending) testing. The microstructure and anisotropic acoustic impedance distributions were assessed by quantitative 50-MHz scanning acoustic microscopy. The relationships between resistance to fracture, structural properties and acoustic impedance of the newly formed callus tissue and adjacent cortical tissue were investigated. A significant linear multivariate regression model was developed that predicts the fracture force with a high accuracy (RMSE = 248 N, R(2) = 0.86, p < 0.0001).
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Affiliation(s)
- Robert Hube
- Q-BAM Group, Department of Orthopedics, Martin Luther University of Halle-Wittenberg, Germany
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35
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Lievers WB, Lee V, Arsenault SM, Waldman SD, Pilkey AK. Specimen size effect in the volumetric shrinkage of cancellous bone measured at two levels of dehydration. J Biomech 2006; 40:1903-9. [PMID: 17054965 DOI: 10.1016/j.jbiomech.2006.09.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Accepted: 09/04/2006] [Indexed: 11/26/2022]
Abstract
Water is commonly removed from bone to study its effect on mechanical behaviour; however, dehydration also alters the bone structure. To make matters worse, measuring structural changes in cancellous bone is complicated by a number of factors. Therefore, the goals of this study were to address these issues by (1) comparing Archimedes' method and a helium pycnometer as methods for measuring cancellous bone volume; (2) measuring the apparent dimensional and volumetric tissue shrinkage of cancellous bone at two levels of dehydration; and, (3) identifying whether a size effect exists in cancellous bone shrinkage. Cylindrical specimens (3, 5 and 8.3 mm diameters) of cancellous bone were taken from the distal bovine femur. The apparent dimensions of each cylindrical specimen were measured in a fully hydrated state (HYD), after drying at room temperature (AIR), and after oven drying at 105 degrees C (OVEN). Tissue volume measurements for those three hydration states were obtained using both a helium pycnometer and Archimedes' method. Aluminium foams, which mimic the cancellous structure, were used as controls. The results suggest that the helium pycnometer and Archimedes' method yield identical results in the HYD and AIR states, but that Archimedes' method under-predicts the nominal OVEN volume by incorporating the collagen-apatite porosity. A distinct size effect on volumetric shrinkage is observed (p<0.025) using the pycnometer in both AIR and OVEN states. Apparent dimensional shrinkage (2% and 7%) at the two dehydration levels is much smaller than the measured volumetric tissue shrinkage (16% and 29%), which results in a reduced dehydrated bone volume fraction.
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Affiliation(s)
- W Brent Lievers
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ont., Canada K7L 3N6
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Fritsch A, Hellmich C. 'Universal' microstructural patterns in cortical and trabecular, extracellular and extravascular bone materials: micromechanics-based prediction of anisotropic elasticity. J Theor Biol 2006; 244:597-620. [PMID: 17074362 DOI: 10.1016/j.jtbi.2006.09.013] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 09/06/2006] [Accepted: 09/08/2006] [Indexed: 11/25/2022]
Abstract
Bone materials are characterized by an astonishing variability and diversity. Still, because of 'architectural constraints' due to once chosen material constituents and their physical interaction, the fundamental hierarchical organization or basic building plans of bone materials remain largely unchanged during biological evolution. Such universal patterns of microstructural organization govern the mechanical interaction of the elementary components of bone (hydroxyapatite, collagen, water; with directly measurable tissue-independent elastic properties), which are here quantified through a multiscale homogenization scheme delivering effective elastic properties of bone materials: at a scale of 10nm, long cylindrical collagen molecules, attached to each other at their ends by approximately 1.5nm long crosslinks and hosting intermolecular water inbetween, form a contiguous matrix called wet collagen. At a scale of several hundred nanometers, wet collagen and mineral crystal agglomerations interpenetrate each other, forming the mineralized fibril. At a scale of 5-10microm, the extracellular solid bone matrix is represented as collagen fibril inclusions embedded in a foam of largely disordered (extrafibrillar) mineral crystals. At a scale above the ultrastructure, where lacunae are embedded in extracellular bone matrix, the extravascular bone material is observed. Model estimates predicted from tissue-specific composition data gained from a multitude of chemical and physical tests agree remarkably well with corresponding acoustic stiffness experiments across a variety of cortical and trabecular, extracellular and extravascular materials. Besides from reconciling the well-documented, seemingly opposed concepts of 'mineral-reinforced collagen matrix' and 'collagen-reinforced mineral matrix' for bone ultrastructure, this approach opens new possibilities in the exploitation of computer tomographic data for nano-to-macro mechanics of bone organs.
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Affiliation(s)
- Andreas Fritsch
- Institute for Mechanics of Materials and Structures, Vienna University of Technology (TU Wien), A-1040 Vienna, Austria.
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37
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Skedros JG, Sorenson SM, Takano Y, Turner CH. Dissociation of mineral and collagen orientations may differentially adapt compact bone for regional loading environments: results from acoustic velocity measurements in deer calcanei. Bone 2006; 39:143-51. [PMID: 16459155 DOI: 10.1016/j.bone.2005.12.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 11/25/2005] [Accepted: 12/07/2005] [Indexed: 11/28/2022]
Abstract
In limb bone diaphyses, it is hypothesized that collagen and extra-fibrillar mineral are aligned differently in relatively simple loading conditions (e.g., habitual longitudinal compression) when compared to complex or potentially deleterious strain environments (e.g., habitual shear or tension). These putative differences in collagen/mineral organization might be adaptations that enhance toughness and fatigue resistance by controlling the direction of microdamage propagation. This study examined relationships between the non-uniform strain distribution of wild deer calcanei and elastic anisotropy of cortical bone specimens in three preparations: (1) demineralized (collagen only), (2) deproteinized (mineral only), and (3) untreated. Using simulated functional loading, the following strain data were obtained from the dorsal "compression", plantar "tension", and medial and lateral ("neutral axis") cortices of one calcaneus of each of seven pairs: (1) peak strain magnitude, (2) prevalent/predominant strain mode (compression, tension, shear), and (3) principal strain orientation with respect to the bone's long axis. In the contralateral calcanei, elastic anisotropy ratios (ARs) were calculated using acoustic velocity (longitudinal and transverse) measurements from a pair of orthogonally sliced specimens (representing each of three preparation types) from each cortex. In a separate set of seven adult calcanei, predominant collagen fiber orientation (CFO) was measured using circularly polarized light (CPL) in the four cortical locations. Results showed that, in general, elastic anisotropy was significant in each region, with ARs being significantly different from isotropy (where AR=1.0). Compared to CFO, mineral orientation more strongly influenced this anisotropy, which was most notable in the plantar "tension" cortex. High correlations (r values from -0.675 to -0.734, P<0.05) were found between collagen anisotropy obtained from acoustic data when compared to the CPL data. Significant correlations of mineral and collagen anisotropy were also found between strain mode, magnitude, and orientation (all r values approximately -0.750). The habitual compression, tension, and shear (neutral axis) regions also had different collagen/mineral organizations, which may be important in accommodating the well-known disparity in the mechanical properties of bone in these loading modes.
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Affiliation(s)
- John G Skedros
- Department of Orthopaedic Surgery, University of Utah, and Bone and Joint Research Laboratory, Department of Veteran's Affairs Medical Center, Salt Lake City, UT 84107, USA.
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38
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Dong XN, Guo XE. Prediction of Cortical Bone Elastic Constants by a Two-Level Micromechanical Model Using a Generalized Self-Consistent Method. J Biomech Eng 2005; 128:309-16. [PMID: 16706580 DOI: 10.1115/1.2187039] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A two-level micromechanical model of cortical bone based on a generalized self-consistent method was developed to take into consideration the transversely isotropic elasticity of many microstructural features in cortical bone, including Haversian canals, resorption cavities, and osteonal and interstitial lamellae. In the first level, a single osteon was modeled as a two-phase composite such that Haversian canals were represented by elongated pores while the surrounding osteonal lamellae were considered as matrix. In the second level, osteons and resorption cavities were modeled as multiple inclusions while interstitial lamellae were regarded as matrix. The predictions of cortical bone elasticity from this two-level micromechanical model were mostly in agreement with experimental data for the dependence of transversely isotropic elasticity of human femoral cortical bone on porosity. However, variation in cortical bone elastic constants was greater in experimental data than in model predictions. This could be attributed to variations in the elastic properties of microstructural features in cortical bone. The present micromechanical model of cortical bone will be useful in understanding the contribution of cortical bone porosity to femoral neck fractures.
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Affiliation(s)
- X Neil Dong
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
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39
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Raum K, Leguerney I, Chandelier F, Bossy E, Talmant M, Saïed A, Peyrin F, Laugier P. Bone microstructure and elastic tissue properties are reflected in QUS axial transmission measurements. ULTRASOUND IN MEDICINE & BIOLOGY 2005; 31:1225-35. [PMID: 16176789 DOI: 10.1016/j.ultrasmedbio.2005.05.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 04/25/2005] [Accepted: 05/11/2005] [Indexed: 05/04/2023]
Abstract
Accurate clinical interpretation of the sound velocity derived from axial transmission devices requires a detailed understanding of the propagation phenomena involved and of the bone factors that have an impact on measurements. In the low megahertz range, ultrasonic propagation in cortical bone depends on anisotropic elastic tissue properties, porosity and the cortical geometry (e.g., thickness). We investigated 10 human radius samples from a previous biaxial transmission study using a 50-MHz scanning acoustic microscope (SAM) and synchrotron radiation microcomputed tomography. The relationships between low-frequency axial transmission sound speed at 1 and 2 MHz, structural properties (cortical width Ct.Wi, porosity, Haversian canal density and material properties (acoustic impedance, mineral density) on site-matched cross-sections were investigated. Significant linear multivariate regression models (1 MHz: R(2) = 0.84, p < 10(-4), root-mean-square error (RMSE) = 38 m/s, 2 MHz: R(2) = 0.65, p < 10(-4), RMSE = 48 m/s) were found for the combination of Ct.Wi with porosity and impedance. A new model was derived that accounts for the nonlinear dispersion relation with Ct.Wi and predicts axial transmission velocities measured at different ultrasonic frequencies (R(2) = 0.69, p < 10(-4), RMSE = 52 m/s).
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Affiliation(s)
- Kay Raum
- Laboratoire d'Imagerie Paramétrique, CNRS/Université Paris 6, Paris, France.
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40
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Iyo T, Maki Y, Sasaki N, Nakata M. Anisotropic viscoelastic properties of cortical bone. J Biomech 2004; 37:1433-7. [PMID: 15275852 DOI: 10.1016/j.jbiomech.2003.12.023] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2003] [Indexed: 11/28/2022]
Abstract
Relaxation Young's modulus of cortical bone was investigated for two different directions with respect to the longitudinal axis of bone (bone axis, BA): the modulus parallel (P) and normal (N) to the BA. The relaxation modulus was analyzed by fitting to the empirical equation previously proposed for cortical bones, i.e., a linear combination of two Kohlraush-Williams-Watts (KWW) functions (Iyo et al., 2003. Biorheology, submitted): E(t)=E0 (A1 exp[-(t/tau1)beta]+(1-A1) exp[-(t/tau2)gamma]), [0 < A1, beta, gamma < 1], where E0 is the initial modulus value E0. Tau1 and tau2(>>tau1) are characteristic times of the relaxation, A1 is the fractional contribution of the fast relaxation (KWW1 process) to the whole relaxation process, and beta and gamma are parameters describing the shape of the relaxation modulus. In both P and N samples, the relaxation modulus was described well by the empirical equation. The KWW1 process of a P sample almost completely coincided with that of an N sample. In the slow process (KWW2 process), there was a difference between the relaxation modulus of a P sample and that of an N sample. The results indicate that the KWW1 process in the empirical equation represents the relaxation in the collagen matrix in bone and that the KWW2 process is related to a higher-order structure of bone that is responsible for the anisotropic mechanical properties of bone.
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Affiliation(s)
- Toshiya Iyo
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-ku, Sapporo 060-0810, Japan
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41
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Schwartz-Dabney CL, Dechow PC. Variations in cortical material properties throughout the human dentate mandible. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2003; 120:252-77. [PMID: 12567378 DOI: 10.1002/ajpa.10121] [Citation(s) in RCA: 179] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Material properties and their variations in individual bone organs are important for understanding bone adaptation and quality at a tissue level, and are essential for accurate mechanical models. Yet material property variations have received little systematic study. Like all other material property studies in individual bone organs, studies of the human mandible are limited by a low number of both specimens and sampled regions. The aims of this study were to determine: 1) regional variability in mandibular material properties, 2) the effect of this variability on the modeling of mandibular function, and 3) the relationship of this variability to mandibular structure and function. We removed 31 samples on both facial and lingual cortices of 10 fresh adult dentate mandibles, measured cortical thickness and density, determined the directions of maximum stiffness with a pulse transmission ultrasonic technique, and calculated elastic properties from measured ultrasonic velocities. Results showed that each of these elastic properties in the dentate human mandible demonstrates unique regional variation. The direction of maximum stiffness was near parallel to the occlusal plane within the corpus. On the facial ramus, the direction of maximum stiffness was more vertically oriented. Several sites in the mandible did not show a consistent direction of maximum stiffness among specimens, although all specimens exhibited significant orthotropy. Mandibular cortical thickness varied significantly (P < 0.001) between sites, and decreased from 3.7 mm (SD = 0.9) anteriorly to 1.4 mm posteriorly (SD = 0.1). The cortical plate was also significantly thicker (P < 0.003) on the facial side than on the lingual side. Bone was 50-100% stiffer in the longitudinal direction (E(3), 20-30 GPa) than in the circumferential or tangential directions (E(2) or E(1); P < 0.001). The results suggest that material properties and directional variations have an important impact on mandibular mechanics. The accuracy of stresses calculated from strains and average material properties varies regionally, depending on variations in the direction of maximum stiffness and anisotropy. Stresses in some parts of the mandible can be more accurately calculated than in other regions. Limited evidence suggests that the orientations and anisotropies of cortical elastic properties correspond with features of cortical bone microstructure, although the relationship with functional stresses and strains is not clear.
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Affiliation(s)
- C L Schwartz-Dabney
- Division of Oral and Maxillofacial Surgery, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9109, USA
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42
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Abstract
The hypothesis of this study is that the mechanical integrity of the collagen network in bone deteriorates with age, and such adverse changes correlate with the decreased toughness of aged bone. To test the hypothesis, 30 human cadaveric femurs from donors ranging from 19 to 89 years of age were tested to determine the age-related changes in the mechanical properties of demineralized bone and fresh bone samples. Along with bone porosity, bone density, and weight fractions of the mineral and organic phases, collagen denaturation and concentrations of collagen cross-links (HP, hydroxylysylpyridinoline; LP, lysylpyridinoline; PE, pentosidine) were determined for these bone specimens as a function age. Analysis of variance (ANOVA) showed that age-dependent changes were reflected in the decreased strength, work to fracture, and fracture toughness of bone; in the decreased strength, elastic modulus, and work to fracture of the collagen network; as well as in the increased concentration of pentosidine (a marker of nonenzymatic glycation) and increased bone porosity. Regression analyses of the measured parameters showed that the age-related decrease in work to fracture of bone (especially its postyield portion) correlated significantly with deterioration in the mechanical integrity of the collagen network. The results of this study indicate that the adverse changes in the collagen network occur as people age and such changes may lead to the decreased toughness of bone. Also, the results suggest that nonenzymatic glycation may be an important contributing factor causing changes in collagen and, consequently, leading to the age-related deterioration of bone quality.
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Affiliation(s)
- X Wang
- Department of Mechanical Engineering, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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43
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Cool SM, Forwood MR, Campbell P, Bennett MB. Comparisons between bone and cementum compositions and the possible basis for their layered appearances. Bone 2002; 30:386-92. [PMID: 11856646 DOI: 10.1016/s8756-3282(01)00686-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In humans, age estimation from the adult skeleton represents an attempt to determine chronological age based on growth and maturational events. In teeth, such events can be characterized by appositional growth layers in midroot cementum. The purpose of this study was to determine the underlying cause of the layered microstructure of human midroot cementum. Whether cementum growth layers are caused by changes in relative mineralization, collagen packing and/or orientation, or by variations in organic matrix apposition was investigated by subjecting midroot sections of human canine teeth to analysis using polarized light and scanning electron microscopy (SEM). Polarized light was used to examine transverse midroot sections in both mineralized and demineralized states. Mineralized sections were also reexamined following subsequent decollagenization. Polarized light was additionally used in the examination of mineralized sections taken transversely, longitudinally, and obliquely from the same tooth root. From the birefringence patterns it was concluded that collagen orientation does not change with varying section plane. Instead, the mineral phase was most responsible for the birefringence of the cementum. SEM studies suggested that neither collagen packing nor collagen orientation change across the width of the cementum, confirming and validating the results of the polarized light examination. Also, SEM analysis using electron backscatter and the electron probe suggested no changes in the mean atomic number density, calcium, phosphate, and sulfur levels across the width of the cementum. Therefore, we conclude that crystalline orientation and/or size is responsible for the layered appearance of cementum.
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Affiliation(s)
- S M Cool
- School of Biomedical Sciences, Department of Anatomy and Developmental Biology, University of Queensland, Brisbane, Queensland, Australia.
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HENGSBERGER S, BOIVIN G, ZYSSET PK. Morphological and Mechanical Properties of Bone Structural Units: A Two-Case Study. ACTA ACUST UNITED AC 2002. [DOI: 10.1299/jsmec.45.936] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Stefan HENGSBERGER
- Laboratoire de Biomécanique de l'Os, LBOS-BIOE-FSTI-EPFL, Ecole Polytechnique Fédérale de Lausanne
| | | | - Philippe K. ZYSSET
- Laboratoire de Biomécanique de l'Os, LBOS-BIOE-FSTI-EPFL, Ecole Polytechnique Fédérale de Lausanne
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45
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Vashishth D, Gibson GJ, Khoury JI, Schaffler MB, Kimura J, Fyhrie DP. Influence of nonenzymatic glycation on biomechanical properties of cortical bone. Bone 2001; 28:195-201. [PMID: 11182378 DOI: 10.1016/s8756-3282(00)00434-8] [Citation(s) in RCA: 343] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this study, the influence of nonenzymatic glycation (NEG) on the mechanical properties of bone and bone collagen were investigated. Bovine cortical bone specimens were incubated in ribose to cause collagen cross-links in vitro, and nondestructive mechanical testing was used to determine tensile and compressive elastic modulus as a function of incubation time. Mechanical properties associated with yield, postyield, and final fracture of bone were determined at the end of the incubation period. The stiffness of the collagen network was measured using stress relaxation tests of demineralized bone cylinders extracted periodically throughout the incubation period. It was found that accumulation of nonenzymatic glycation end-products in cortical bone caused stiffening of the type I collagen network in bone (r2 = 0.92; p < 0.001) but did not significantly affect the overall stiffness of the mineralized bone (p = 0.98). The ribosylated group had significantly more NEG products and higher yield stress and strain than the control group (p < 0.05). Postyield properties including postyield strain and strain energy were lower in the ribosylated group but were not significantly different from the control group (p = 0.24). Compared with the control group, the ribosylated group was characterized by significantly higher secant modulus and lower damage fraction (p < 0.05). Taken together, the results of this study suggest that collagen in bone is susceptible to the same NEG-mediated changes as collagen in other connective tissues and that an increased stiffness of the collagen network in bone due to NEG may explain some of the age-related increase in skeletal fragility and fracture risk.
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Affiliation(s)
- D Vashishth
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180,
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46
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Athanasiou KA, Zhu C, Lanctot DR, Agrawal CM, Wang X. Fundamentals of biomechanics in tissue engineering of bone. TISSUE ENGINEERING 2000; 6:361-81. [PMID: 10992433 DOI: 10.1089/107632700418083] [Citation(s) in RCA: 206] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The objective of this review is to provide basic information pertaining to biomechanical aspects of bone as they relate to tissue engineering. The review is written for the general tissue engineering reader, who may not have a biomechanical engineering background. To this end, biomechanical characteristics and properties of normal and repair cortical and cancellous bone are presented. Also, this chapter intends to describe basic structure-function relationships of these two types of bone. Special emphasis is placed on salient classical and modern testing methods, with both material and structural properties described.
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Affiliation(s)
- K A Athanasiou
- Department of Bioengineering, Rice University, Houston, Texas 77251-1892, USA.
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47
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Abstract
To investigate the source of bone brittleness in the disease osteogenesis imperfecta (OI), biomechanical properties have been measured in the femurs from a homozygous (oim/oim) mutant mouse model of OI, its heterozygous littermates, and wild-type animals. The novel technique of ultrasound critical-angle reflectometry (UCR) was used to determine bone material elasticity matrix from measurements of the pressure and shear wave velocity at different orientations about selected points of the bone specimens. This nondestructive method is the only available means for obtaining measurements of this nature from a single surface. The ultrasound pressure wave velocity showed an increased isotropy in the homozygous compared to the wild-type specimens. This was reflected in a significant decrease in the principal elastic modulus measured along the length of the oim/oim bones (E33) while the modulus along the width (E11) did not change significantly, compared to wild-type specimens. The Poisson's ratio, v12, also had a significantly increased value in oim/oim bones. Measurements of these parameters in heterozygous animals generally fell between those from homozygous and control mice. The differences in the elasticity components in oim/oim bones indicate an altered stress distribution and a modified elastic response to loads, compared to normal bone.
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Affiliation(s)
- S S Mehta
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas 75235-9058, USA.
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48
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Abstract
The purpose of this study was to examine the relationships that exist between the elastic properties and the physicochemical properties of cortical bone in two groups of experimental animals. The animal model was the immature mutant dwarf rat, and the groups consisted of rats treated and not treated with recombinant human growth hormone (rhGH). The objective was to establish and broaden the quantifiable link between the three-dimensional form and function of bone beyond the typical unidirectional measures. This study was based on previously reported work that refined the ultrasonic elasticity technique for use with small specimens (<1.0 mm) and determined that the administration of rhGH can counter the degenerative effects produced by hormone-suppressed downregulation on the elastic and physicochemical characteristics of cortical bone. Ultrasonic wave propagation and density measurements were used previously to determine the three-dimensional (orthotropic) material properties of rat femoral cortical bone. X-ray powder diffraction, microscopic, morphometric, and biochemical analysis techniques have been used to describe physicochemical properties, including mineral crystal size, cortical porosity, mineral and nonmineral content, and microstructural characteristics. In this study, mathematical relationships between the local physicochemical (independent variable) and elastic (dependent variable) properties were formulated via linear and nonlinear regression analyses. In general, apparent density was found to have the highest level of correlation with most of the longitudinal and shear moduli (R(2) = 0.300 to 0.800). Concomitantly, mineral crystal width and cortical porosity offered the best correlations with the Poisson's ratios (R(2) up to 0.600). Wilcoxon t tests verified a significant decrease in the elastic properties in dwarf rat cortical bone after rhGH treatments (p < 0.05). Physicochemical measures of bone quality (density, crystal size) generally decreased while measures of bone quantity (cortical area, moments of inertia) generally increased (p < 0.05) after rhGH treatments. Some mineral and nonmineral properties were unchanged. This study presents a quantifiable link between cortical bone elasticity and its composite construction as measured across two dramatically different experimental groups.
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Affiliation(s)
- S S Kohles
- Departments of Biomedical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609-2280 USA.
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49
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Raspanti M, Cesari C, De Pasquale V, Ottani V, Strocchi R, Zucchelli G, Ruggeri A. A histological and electron-microscopic study of the architecture and ultrastructure of human periodontal tissues. Arch Oral Biol 2000; 45:185-92. [PMID: 10761871 DOI: 10.1016/s0003-9969(99)00145-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structure of periodontal tissues is still far less understood than their clinical relevance would demand. Here the periodontal ligament and radicular cementum in healthy human teeth were studied by light microscopy, transmission and scanning electron microscopy. These observations showed that the extracellular matrix of periodontal ligament is composed of a loose plexus of wavy collagen fibrils immersed in a highly hydrated interfibrillar matrix. Only close to their cemental insertion do these fibrils gather in thick, parallel fascicles (Sharpey's fibres). As these cross the mineralization front, they become infiltrated by the mineral phase and continue directly with the cementum matrix. Sharpey's fibres, "extrinsic" and "intrinsic" fibres all appear to be the same fibres, which bend and branch repeatedly during their course within the thickness of the cementum. Because of its physical continuity with the cementum, a limited portion of the periodontal ligament approximately corresponding to the length of Sharpey's fibres remains unaffected by enzymatic digestion of the interfibrillar matrix while the rest of the ligament is completely dissolved. The findings here indicate that the periodontal ligament and dental cementum join by a continuity rather than a contiguity of structures; that the collagen-mineral relation in cementum has distinctive features in comparison to other hard tissues; that extrinsic and intrinsic fibres of cementum and the adjoining portion of periodontal ligament form a structural, mechanical and metabolic unit distinct from the central, more metabolically active portion of the periodontal ligament.
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Affiliation(s)
- M Raspanti
- Institute of Human Morphology, Insubria University, Varese, Italy.
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50
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Wang X, Bank RA, TeKoppele JM, Hubbard GB, Athanasiou KA, Agrawal CM. Effect of collagen denaturation on the toughness of bone. Clin Orthop Relat Res 2000:228-39. [PMID: 10693570 DOI: 10.1097/00003086-200002000-00027] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The purpose of this study was to explore the relationship between the integrity of collagen and biomechanical properties of bone. In this study, age (range, 5-26 years old) and gender related changes in cortical bone samples from 33 baboon femurs (15 males and 18 females) were examined. The percentage of denatured collagen was determined using a selective digestion technique. The fracture toughness, elastic modulus, yield and ultimate strength, and energy to fracture of bone were determined in three-point bending configurations. The porosity and weight fractions of the mineral and organic phase also were measured. A two-way analysis of variance showed that age dependent changes were reflected primarily in the amount of denatured collagen, fracture toughness, energy to fracture, and elastic modulus, whereas gender had effects on the fracture toughness, elastic modulus, and porosity of bone. In addition, regression analyses indicated that the percentage of denatured collagen had an inverse correlation with the toughness of bone and a positive correlation with its elastic modulus, whereas mineral content had positive correlation with the strength and elastic modulus of bone. The results of this study suggest collagen influences the toughness of bone, whereas mineral content predominantly contributes to bone stiffness and strength.
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Affiliation(s)
- X Wang
- Musculoskeletal Bioengineering Center, University of Texas Health Science Center, San Antonio 78284, USA
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