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Skedros JG, Dayton MR, Cronin JT, Mears CS, Bloebaum RD, Wang X, Bachus KN. Roles of collagen cross-links and osteon collagen/lamellar morphotypes in equine third metacarpals in tension and compression tests. J Exp Biol 2024; 227:jeb247758. [PMID: 39045755 PMCID: PMC11418171 DOI: 10.1242/jeb.247758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 06/18/2024] [Indexed: 07/25/2024]
Abstract
Many bones experience bending, placing one side in net compression and the other in net tension. Because bone mechanical properties are relatively reduced in tension compared with compression, adaptations are needed to reduce fracture risk. Several toughening mechanisms exist in bone, yet little is known of the influences of secondary osteon collagen/lamellar 'morphotypes' and potential interplay with intermolecular collagen cross-links (CCLs) in prevalent/predominant tension- and compression-loaded regions. Paired third metacarpals (MC3s) from 10 adult horses were prepared for mechanical testing. From one MC3/pair, 5 mm cubes were tested in compression at several mid-shaft locations. From contralateral bones, dumbbell-shaped specimens were tested in tension. Hence, habitual/natural tension- and compression-loaded regions were tested in both modes. Data included: elastic modulus, yield and ultimate strength, and energy absorption (toughness). Fragments of tested specimens were examined for predominant collagen fiber orientation (CFO; representing osteonal and non-osteonal bone), osteon morphotype score (MTS, representing osteonal CFO), mineralization, porosity and other histological characteristics. As a consequence of insufficient material from tension-tested specimens, CCLs were only examined in compression-tested specimens (HP, hydroxylysylpyridinoline; LP, lysylpyridinoline; PE, pentosidine). Among CCLs, only LP and HP/LP correlated significantly with mechanical parameters: LP with energy absorption, HP/LP with elastic modulus (both r=0.4). HP/LP showed a trend with energy absorption (r=-0.3, P=0.08). HP/LP more strongly correlated with osteon density and mineralization than CFO or MTS. Predominant CFO more strongly correlated with energy absorption than MTS in both testing modes. In general, CFO was found to be relatively prominent in affecting regional toughness in these equine MC3s in compression and tension.
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Affiliation(s)
- John G. Skedros
- University of Utah, Department of Orthopaedics, Salt Lake City, UT 84108, USA
| | - Michael R. Dayton
- University of Colorado, Department of Orthopedics, Aurora, CO 80045, USA
| | - John T. Cronin
- University of Utah, Department of Orthopaedics, Salt Lake City, UT 84108, USA
| | - Chad S. Mears
- University of Utah, Department of Orthopaedics, Salt Lake City, UT 84108, USA
| | - Roy D. Bloebaum
- University of Utah, Department of Orthopaedics, Salt Lake City, UT 84108, USA
| | - Xiaodu Wang
- Department of Mechanical Engineering, University of Texas, San Antonio, TX 78249, USA
| | - Kent N. Bachus
- University of Utah, Department of Orthopaedics, Salt Lake City, UT 84108, USA
- Research Service, Veterans Affair Medical Center, Salt Lake City, UT 84148, USA
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2
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Hieronymus TL, Waugh DA, Ball HC, Vinyard CJ, Galazyuk A, Cooper LN. Comparing age- and bone-related differences in collagen fiber orientation: A case study of bats and laboratory mice using quantitative polarized light microscopy. Anat Rec (Hoboken) 2024; 307:2084-2102. [PMID: 38095113 DOI: 10.1002/ar.25368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 11/17/2023] [Accepted: 11/26/2023] [Indexed: 05/08/2024]
Abstract
As bones age in most mammals, they typically become more fragile. This state of bone fragility is often associated with more homogenous collagen fiber orientations (CFO). Unlike most mammals, bats maintain mechanically competent bone throughout their lifespans, but little is known of positional and age-related changes in CFO within wing bones. This study tests the hypothesis that age-related changes in CFO in big brown bats (Eptesicus fuscus) differ from those of the standard mammalian model for skeletal aging, the C57BL/6 laboratory mouse. We used data from quantitative polarized light microscopy (qPLM) to compare CFO across the lifespan of long-lived big brown bats and age matched C57BL/6 mice. Eptesicus and C57BL/6 mice displayed idiosyncratic patterns of CFO. Consistent age-related changes were only apparent in the outer cortical bone of Eptesicus, where bone tissue is more longitudinally arranged and more anisotropic in older individuals. Both taxa displayed a ring of more transversely oriented bone tissue surrounding the medullary cavity. In Eptesicus, this tissue represents a greater proportion of the overall cross-section, and is more clearly helically aligned (arranged at 45° to the bone long axis) than similar bone tissue in mice. Bat wing bones displayed a proximodistal gradient in CFO anisotropy and longitudinal orientation in both outer and inner cortical bone compartments. This study lays a methodological foundation for the quantitative evaluation of bone tissue architecture in volant and non-volant mammals that may be expanded in the future.
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Affiliation(s)
- Tobin Lee Hieronymus
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Musculoskeletal Research Focus Area, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - David A Waugh
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Musculoskeletal Research Focus Area, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Hope C Ball
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Musculoskeletal Research Focus Area, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | | | - Alex Galazyuk
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Lisa Noelle Cooper
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Musculoskeletal Research Focus Area, Northeast Ohio Medical University, Rootstown, Ohio, USA
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Baleani M, Erani P, Acciaioli A, Schileo E. Tensile Yield Strain of Human Cortical Bone from the Femoral Diaphysis Is Constant among Healthy Adults and across the Anatomical Quadrants. Bioengineering (Basel) 2024; 11:395. [PMID: 38671816 PMCID: PMC11048186 DOI: 10.3390/bioengineering11040395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/12/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
The literature suggests that the yield strain of cortical bone is invariant to its stiffness (elastic modulus) and strength (yield stress). However, data about intra-individual variations, e.g., the influence of different collagen/mineral organisations observed in bone aspects withstanding different habitual loads, are lacking. The hypothesis that the yield strain of human cortical bone tissue, retrieved from femoral diaphyseal quadrants subjected to different habitual loads, is invariant was tested. Four flat dumbbell-shaped specimens were machined from each quadrant of the proximal femoral diaphysis of five adult donors for a total of 80 specimens. Two extensometers attached to the narrow specimen region were used to measure deformation during monotonic tensile testing. The elastic modulus (linear part of the stress-strain curve) and yield strain/stress at a 0.2% offset were obtained. Elastic modulus and yield stress values were, respectively, in the range of 12.2-20.5 GPa and 75.9-136.6 MPa and exhibited a positive linear correlation. All yield strain values were in the narrow range of 0.77-0.87%, regardless of the stiffness and strength of the tissue and the anatomical quadrant. In summary, the results corroborate the hypothesis that tensile yield strain in cortical bone is invariant, irrespective also of the anatomical quadrant. The mean yield strain value found in this study is similar to what was reported by inter-species and evolution studies but slightly higher than previous reports in humans, possibly because of the younger age of our subjects. Further investigations are needed to elucidate a possible dependence of yield strain on age.
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Affiliation(s)
- Massimiliano Baleani
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; (P.E.); (A.A.)
| | - Paolo Erani
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; (P.E.); (A.A.)
| | - Alice Acciaioli
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy; (P.E.); (A.A.)
| | - Enrico Schileo
- Laboratorio di Bioingegneria Computazionale, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy;
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Skedros JG, Dayton MR, Bloebaum RD, Bachus KN, Cronin JT. Strain-mode-specific mechanical testing and the interpretation of bone adaptation in the deer calcaneus. J Anat 2024; 244:411-423. [PMID: 37953064 PMCID: PMC10862189 DOI: 10.1111/joa.13971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/18/2023] [Accepted: 10/21/2023] [Indexed: 11/14/2023] Open
Abstract
The artiodactyl (deer and sheep) calcaneus is a model that helps in understanding how many bones achieve anatomical optimization and functional adaptation. We consider how the dorsal and plantar cortices of these bones are optimized in quasi-isolation (the conventional view) versus in the context of load sharing along the calcaneal shaft by "tension members" (the plantar ligament and superficial digital flexor tendon). This load-sharing concept replaces the conventional view, as we have argued in a recent publication that employs an advanced analytical model of habitual loading and fracture risk factors of the deer calcaneus. Like deer and sheep calcanei, many mammalian limb bones also experience prevalent bending, which seems problematic because the bone is weaker and less fatigue-resistant in tension than compression. To understand how bones adapt to bending loads and counteract deleterious consequences of tension, it is important to examine both strain-mode-specific (S-M-S) testing (compression testing of bone habitually loaded in compression; tension testing of bone habitually loaded in tension) and non-S-M-S testing. Mechanical testing was performed on individually machined specimens from the dorsal "compression cortex" and plantar "tension cortex" of adult deer calcanei and were independently tested to failure in one of these two strain modes. We hypothesized that the mechanical properties of each cortex region would be optimized for its habitual strain mode when these regions are considered independently. Consistent with this hypothesis, energy absorption parameters were approximately three times greater in S-M-S compression testing in the dorsal/compression cortex when compared to non-S-M-S tension testing of the dorsal cortex. However, inconsistent with this hypothesis, S-M-S tension testing of the plantar/tension cortex did not show greater energy absorption compared to non-S-M-S compression testing of the plantar cortex. When compared to the dorsal cortex, the plantar cortex only had a higher elastic modulus (in S-M-S testing of both regions). Therefore, the greater strength and capacity for energy absorption of the dorsal cortex might "protect" the weaker plantar cortex during functional loading. However, this conventional interpretation (i.e., considering adaptation of each cortex in isolation) is rejected when critically considering the load-sharing influences of the ligament and tendon that course along the plantar cortex. This important finding/interpretation has general implications for a better understanding of how other similarly loaded bones achieve anatomical optimization and functional adaptation.
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Affiliation(s)
- John G Skedros
- Department of Orthopaedics, University of Utah, Salt Lake City, Utah, USA
| | - Michael R Dayton
- Department of Orthopedics, University of Colorado, Aurora, Colorado, USA
| | - Roy D Bloebaum
- Department of Orthopaedics, University of Utah, Salt Lake City, Utah, USA
| | - Kent N Bachus
- Department of Orthopaedics, University of Utah, Salt Lake City, Utah, USA
- Research Service, Veterans Affair Medical Center, Salt Lake City, Utah, USA
| | - John T Cronin
- Department of Orthopaedics, University of Utah, Salt Lake City, Utah, USA
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Lad SE. Absence of secondary osteons in femora of aged rats: Implications of lifespan on Haversian remodeling in mammals. J Morphol 2023; 284:e21600. [PMID: 37313764 DOI: 10.1002/jmor.21600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/05/2023] [Accepted: 05/08/2023] [Indexed: 06/15/2023]
Abstract
Bone is a dynamic tissue capable of adapting to its loading environment, allowing the skeleton to remain structurally sound throughout life. One way adaptation occurs in mammals is via Haversian remodeling: the site-specific, coupled resorption and formation of cortical bone that results in secondary osteons. Remodeling occurs at a baseline rate in most mammals, but it also occurs in relation to strain by repairing deleterious microdamage. Yet, not all animals with bony skeletons remodel. Among mammals, there is inconsistent or absent evidence for Haversian remodeling among monotremes, insectivores, chiropterans, cingulates, and rodents. Three possible explanations for this disparity are discussed: the capacity for Haversian remodeling, body size as a constraint, and age and lifespan as constraints. It is generally accepted, although not thoroughly documented, that rats (a common model used in bone research) do not typically exhibit Haversian remodeling. The present aim is to more specifically test the hypothesis that rats of advanced age do remodel intracortically because of the longer lifespan over which baseline remodeling could occur. Most published histological descriptions of rat bone only include young (3-6 months) rats. Excluding aged rats possibly overlooks a transition from modeling (i.e., bone growth) to Haversian remodeling as the primary mode of bone adaptation. Here, midshaft and distal femora (typical sites for remodeling in other mammals) of 24-month-old rats were examined for presence of secondary osteons. None were found, suggesting that Haversian remodeling does not occur in rats under normal physiological conditions at any age. A likely explanation is that modeling of cortical bone continues throughout most of the short rat lifespan, negating the stimulus for Haversian remodeling. Thorough sampling of key rodent taxa of varying body sizes and lifespans is key to elucidating the reasons why (i.e., body size, age/lifespan, phylogenetic factors) Haversian remodeling might not occur in all mammals.
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Affiliation(s)
- Susan E Lad
- Department of Exercise Science, High Point University, High Point, North Carolina, USA
- Department of Physical Therapy, High Point University, High Point, North Carolina, USA
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6
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Skedros JG, Cronin JT, Dayton MR, Bloebaum RD, Bachus KN. Exploration of the synergistic role of cortical thickness asymmetry ("Trabecular Eccentricity" concept) in reducing fracture risk in the human femoral neck and a control bone (Artiodactyl Calcaneus). J Theor Biol 2023; 567:111495. [PMID: 37068584 DOI: 10.1016/j.jtbi.2023.111495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/24/2023] [Accepted: 04/10/2023] [Indexed: 04/19/2023]
Abstract
The mechanobiology of the human femoral neck is a focus of research for many reasons including studies that aim to curb age-related bone loss that contributes to a near-exponential rate of hip fractures. Many believe that the femoral neck is often loaded in rather simple bending, which causes net tension stress in the upper (superior) femoral neck and net compression stress in its inferior aspect ("T/C paradigm"). This T/C loading regime lacks in vivo proof. The "C/C paradigm" is a plausible alternative simplified load history that is characterized by a gradient of net compression across the entire femoral neck; action of the gluteus medius and external rotators of the hip are important in this context. It is unclear which paradigm is at play in natural loading due to lack of in vivo bone strain data and deficiencies in understanding mechanisms and manifestations of bone adaptation in tension vs. compression. For these reasons, studies of the femoral neck would benefit from being compared to a 'control bone' that has been proven, by strain data, to be habitually loaded in bending. The artiodactyl (sheep and deer) calcaneus model has been shown to be a very suitable control in this context. However, the application of this control in understanding the load history of the femoral neck has only been attempted in two prior studies, which did not examine the interplay between cortical and trabecular bone, or potential load-sharing influences of tendons and ligaments. Our first goal is to compare fracture risk factors of the femoral neck in both paradigms. Our second goal is to compare and contrast the deer calcaneus to the human femoral neck in terms of fracture risk factors in the T/C paradigm (the C/C paradigm is not applicable in the artiodactyl calcaneus due to its highly constrained loading). Our third goal explores interplay between dorsal/compression and plantar/tension regions of the deer calcaneus and the load-sharing roles of a nearby ligament and tendon, with insights for translation to the femoral neck. These goals were achieved by employing the analytical model of Fox and Keaveny (J. Theoretical Biology 2001, 2003) that estimates fracture risk factors of the femoral neck. This model focuses on biomechanical advantages of the asymmetric distribution of cortical bone in the direction of habitual loading. The cortical thickness asymmetry of the femoral neck (thin superior cortex, thick inferior cortex) reflects the superior-inferior placement of trabecular bone (i.e., "trabecular eccentricity," TE). TE helps the femoral neck adapt to typical stresses and strains through load-sharing between superior and inferior cortices. Our goals were evaluated in the context of TE. Results showed the C/C paradigm has lower risk factors for the superior cortex and for the overall femoral neck, which is clinically relevant. TE analyses of the deer calcaneus revealed important synergism in load-sharing between the plantar/tension cortex and adjacent ligament/tendon, which challenges conventional understanding of how this control bone achieves functional adaptation. Comparisons with the control bone also exposed important deficiencies in current understanding of human femoral neck loading and its potential histocompositional adaptations.
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Affiliation(s)
- John G Skedros
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA; Research Service, Veterans Affairs Medical Center, Salt Lake City, UT, USA.
| | - John T Cronin
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA
| | - Michael R Dayton
- University of Colorado, Department of Orthopedics, Aurora, CO, USA
| | - Roy D Bloebaum
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA; Research Service, Veterans Affairs Medical Center, Salt Lake City, UT, USA
| | - Kent N Bachus
- University of Utah, Department of Orthopaedics, Salt Lake City, UT, USA; Research Service, Veterans Affairs Medical Center, Salt Lake City, UT, USA
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7
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Vitienes I, Mikolajewicz N, Hosseinitabatabaei S, Bouchard A, Julien C, Graceffa G, Rentsch A, Widowski T, Main RP, Willie BM. Breed and loading history influence in vivo skeletal strain patterns in pre-pubertal female chickens. Bone 2023; 173:116785. [PMID: 37146896 DOI: 10.1016/j.bone.2023.116785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/28/2023] [Accepted: 04/28/2023] [Indexed: 05/07/2023]
Abstract
The influence of loading history on in vivo strains within a given specie remains poorly understood, and although in vivo strains have been measured at the hindlimb bones of various species, strains engendered during modes of activity other than locomotion are lacking, particularly in non-human species. For commercial egg-laying chickens specifically, there is an interest in understanding their bones' mechanical behaviour, particularly during youth, to develop early interventions to prevent the high incidence of osteoporosis in this population. We measured in vivo mechanical strains at the tibiotarsus midshaft during steady activities (ground, uphill, downhill locomotion) and non-steady activities (perching, jumping, aerial transition landing) in 48 pre-pubescent female (egg-laying) chickens from two breeds that were reared in three different housing systems, allowing varying amounts and types of physical activity. Mechanical strain patterns differed between breeds, and were dependent on the activity performed. Mechanical strains were also affected by rearing environment: chickens that were restricted from performing dynamic load bearing activity due to caged-housing generally exhibited higher mechanical strain levels during steady, but not non-steady activities, compared to chickens with prior dynamic load-bearing activity experience. Among chickens with prior experience of dynamic load bearing activity, those reared in housing systems that allowed more frequent physical activity did not exhibit lower mechanical strains. In all groups, the tibiotarsus was subjected to a loading environment consisting of a combination of axial compression, bending, and torsion, with torsion being the predominant source of strain. Aerial transition landing produced the highest strain levels with unusual strain patterns compared to other activities, suggesting it may produce the strongest anabolic response. These results exemplify how different breeds within a given specie adapt to maintain different patterns of mechanical strains, and how benefits of physical activity in terms of resistance to strain are activity-type dependent and do not necessarily increase with increased physical activity. These findings directly inform controlled loading experiments aimed at studying the bone mechanoresponse in young female chickens and can also be associated to measures of bone morphology and material properties to understand how these features influence bone mechanical properties in vivo.
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Affiliation(s)
- Isabela Vitienes
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Department of Biological and Biomedical Engineering, McGill University, Montreal, Canada; Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada
| | | | - Seyedmahdi Hosseinitabatabaei
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Department of Biological and Biomedical Engineering, McGill University, Montreal, Canada; Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada
| | - Alice Bouchard
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada
| | - Catherine Julien
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada
| | - Gabrielle Graceffa
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada
| | - Ana Rentsch
- Department of Animal Bioscience, University of Guelph, Guelph, Canada
| | - Tina Widowski
- Department of Animal Bioscience, University of Guelph, Guelph, Canada
| | - Russell P Main
- Weldon School of Biomedical Engineering, Purdue University, Indiana, USA; Department of Basic Medical Sciences, Purdue University, Indiana, USA
| | - Bettina M Willie
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Department of Biological and Biomedical Engineering, McGill University, Montreal, Canada; Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada.
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8
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Stockhausen KE, Qwamizadeh M, Wölfel EM, Hemmatian H, Fiedler IAK, Flenner S, Longo E, Amling M, Greving I, Ritchie RO, Schmidt FN, Busse B. Collagen Fiber Orientation Is Coupled with Specific Nano-Compositional Patterns in Dark and Bright Osteons Modulating Their Biomechanical Properties. ACS NANO 2021; 15:455-467. [PMID: 33404232 DOI: 10.1021/acsnano.0c04786] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bone continuously adapts to its mechanical environment by structural reorganization to maintain mechanical strength. As the adaptive capabilities of bone are portrayed in its nano- and microstructure, the existence of dark and bright osteons with contrasting preferential collagen fiber orientation (longitudinal and oblique-angled, respectively) points at a required tissue heterogeneity that contributes to the excellent fracture resistance mechanisms in bone. Dark and bright osteons provide an exceptional opportunity to deepen our understanding of how nanoscale tissue properties influence and guide fracture mechanisms at larger length scales. To this end, a comprehensive structural, compositional, and mechanical assessment is performed using circularly polarized light microscopy, synchrotron nanocomputed tomography, focused ion beam/scanning electron microscopy, quantitative backscattered electron imaging, Fourier transform infrared spectroscopy, and nanoindentation testing. To predict how the mechanical behavior of osteons is affected by shifts in collagen fiber orientation, finite element models are generated. Fundamental disparities between both osteon types are observed: dark osteons are characterized by a higher degree of mineralization along with a higher ratio of inorganic to organic matrix components that lead to higher stiffness and the ability to resist plastic deformation under compression. On the contrary, bright osteons contain a higher fraction of collagen and provide enhanced ductility and energy dissipation due to lower stiffness and hardness.
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Affiliation(s)
- Kilian E Stockhausen
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
| | - Mahan Qwamizadeh
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
| | - Eva M Wölfel
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
- Forum Medical Technology Health Hamburg (FMTHH), Butenfeld 34, 22529 Hamburg, Germany
- Interdisciplinary Competence Center for Interface Research (ICCIR), Martinistrasse 52, 20251 Hamburg, Germany
| | - Haniyeh Hemmatian
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
| | - Imke A K Fiedler
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
- Forum Medical Technology Health Hamburg (FMTHH), Butenfeld 34, 22529 Hamburg, Germany
| | - Silja Flenner
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany
| | - Elena Longo
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
| | - Imke Greving
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany
| | - Robert O Ritchie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Felix N Schmidt
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
- Forum Medical Technology Health Hamburg (FMTHH), Butenfeld 34, 22529 Hamburg, Germany
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center, Lottestrasse 55a, 22529 Hamburg, Germany
- Interdisciplinary Competence Center for Interface Research (ICCIR), Martinistrasse 52, 20251 Hamburg, Germany
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
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9
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Nguyen JT, Barak MM. Secondary osteon structural heterogeneity between the cranial and caudal cortices of the proximal humerus in white-tailed deer. J Exp Biol 2020; 223:jeb225482. [PMID: 32366689 PMCID: PMC7295587 DOI: 10.1242/jeb.225482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 04/27/2020] [Indexed: 01/13/2023]
Abstract
Cortical bone remodeling is an ongoing process triggered by microdamage, where osteoclasts resorb existing bone and osteoblasts deposit new bone in the form of secondary osteons (Haversian systems). Previous studies revealed regional variance in Haversian systems structure and possibly material, between opposite cortices of the same bone. As bone mechanical properties depend on tissue structure and material, it is predicted that bone mechanical properties will vary in accordance with structural and material regional heterogeneity. To test this hypothesis, we analysed the structure, mineral content and compressive stiffness of secondary bone from the cranial and caudal cortices of the white-tailed deer proximal humerus. We found significantly larger Haversian systems and canals in the cranial cortex but no significant difference in mineral content between the two cortices. Accordingly, we found no difference in compressive stiffness between the two cortices and thus our working hypothesis was rejected. As the deer humerus is curved and thus likely subjected to bending during habitual locomotion, we expect that similar to other curved long bones, the cranial cortex of the deer humerus is likely subjected primarily to tensile strains and the caudal cortex is subject primarily to compressive strains. Consequently, our results suggest that strain magnitude (larger in compression) and sign (compression versus tension) affect the osteoclasts and osteoblasts differently in the basic multicellular unit. Our results further suggest that osteoclasts are inhibited in regions of high compressive strains (creating smaller Haversian systems) while the osteoid deposition and mineralization by osteoblasts is not affected by strain magnitude and sign.
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Affiliation(s)
- Jack T Nguyen
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA
| | - Meir M Barak
- Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, NY 11548, USA
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10
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Main RP, Shefelbine SJ, Meakin LB, Silva MJ, van der Meulen MC, Willie BM. Murine Axial Compression Tibial Loading Model to Study Bone Mechanobiology: Implementing the Model and Reporting Results. J Orthop Res 2020; 38:233-252. [PMID: 31508836 PMCID: PMC9344861 DOI: 10.1002/jor.24466] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/23/2019] [Indexed: 02/04/2023]
Abstract
In vivo, tibial loading in mice is increasingly used to study bone adaptation and mechanotransduction. To achieve standardized and defined experimental conditions, loading parameters and animal-related factors must be considered when performing in vivo loading studies. In this review, we discuss these loading and animal-related experimental conditions, present methods to assess bone adaptation, and suggest reporting guidelines. This review originated from presentations by each of the authors at the workshop "Developing Best Practices for Mouse Models of In Vivo Loading" during the Preclinical Models Section at the Orthopaedic Research Society Annual Meeting, San Diego, CA, March 2017. Following the meeting, the authors engaged in detailed discussions with consideration of relevant literature. The guidelines and recommendations in this review are provided to help researchers perform in vivo loading experiments in mice, and thus further our knowledge of bone adaptation and the mechanisms involved in mechanotransduction. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:233-252, 2020.
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Affiliation(s)
- Russell P. Main
- Department of Basic Medical Sciences and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA,Corresponding author: Russell Main ()
| | - Sandra J. Shefelbine
- Department of Bioengineering, Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA
| | - Lee B. Meakin
- Bristol Veterinary School, University of Bristol, Langford, Bristol BS40 5DU, UK
| | - Matthew J. Silva
- Departments of Orthopaedic Surgery and Biomedical Engineering, Musculoskeletal Research Center, Washington University, Saint Louis, MO, USA
| | - Marjolein C.H van der Meulen
- Meinig School of Biomedical Engineering and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | - Bettina M. Willie
- Research Centre, Shriners Hospital for Children-Canada, Department of Pediatric Surgery, McGill University, Montreal, Canada
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11
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Willie BM, Zimmermann EA, Vitienes I, Main RP, Komarova SV. Bone adaptation: Safety factors and load predictability in shaping skeletal form. Bone 2020; 131:115114. [PMID: 31648080 DOI: 10.1016/j.bone.2019.115114] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/06/2019] [Accepted: 10/17/2019] [Indexed: 02/09/2023]
Abstract
Much is known about skeletal adaptation in relation to the mechanical functions that bones serve. This includes how bone adapts to mechanical loading during an individual's lifetime as well as over evolutionary time. Although controlled loading in animal models allows us to observe short-term bone adaptation (epigenetic mechanobiology), examining an assemblage of extant vertebrate bones or a group of fossils' bony structures can reveal the combined effects of long-term trends in loading history and the effects of natural selection. In this survey we examine adaptations that take place over both time scales and highlight a few of the extraordinary insights first published by John Currey. First, we provide a historical perspective on bone adaptation control mechanisms, followed by a discussion of safety factors in bone. We then summarize examples of structural- and material-level adaptations and mechanotransduction, and analyze the relationship between these structural- and material-level adaptations observed in situations where loading modes are either predictable or unpredictable. We argue that load predictability is a major consideration for bone adaptation broadly across an evolutionary timescale, but that its importance can also be seen during ontogenetic growth trajectories, which are subject to natural selection as well. Furthermore, we suggest that bones with highly predictable load patterns demonstrate more precise design with lower safety factors, while bones that experience less predictable loads or those that are less capable of repair and adaptation are designed with a higher safety factor. Finally, exposure to rare loading events with high potential costs of failure leads to design of structures with very high safety factor compared to everyday loading experience. Understanding bone adaptations at the structural and material levels, which take place over an individual's lifetime or over evolutionary time has numerous applications in translational and clinical research to understand and treat musculoskeletal diseases, as well as to permit the furthering of human extraterrestrial exploration in environments with altered gravity.
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Affiliation(s)
- Bettina M Willie
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Department of Pediatric Surgery, McGill University, Montreal, Canada.
| | - Elizabeth A Zimmermann
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Department of Pediatric Surgery, McGill University, Montreal, Canada
| | - Isabela Vitienes
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Department of Pediatric Surgery, McGill University, Montreal, Canada
| | - Russell P Main
- Department of Basic Medical Sciences and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Svetlana V Komarova
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada; Faculty of Dentistry, McGill University, Montreal, Canada
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Woodward HN, Tremaine K, Williams SA, Zanno LE, Horner JR, Myhrvold N. Growing up Tyrannosaurus rex: Osteohistology refutes the pygmy " Nanotyrannus" and supports ontogenetic niche partitioning in juvenile Tyrannosaurus. SCIENCE ADVANCES 2020; 6:eaax6250. [PMID: 31911944 PMCID: PMC6938697 DOI: 10.1126/sciadv.aax6250] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 11/01/2019] [Indexed: 06/10/2023]
Abstract
Despite its iconic status as the king of dinosaurs, Tyrannosaurus rex biology is incompletely understood. Here, we examine femur and tibia bone microstructure from two half-grown T. rex specimens, permitting the assessments of age, growth rate, and maturity necessary for investigating the early life history of this giant theropod. Osteohistology reveals these were immature individuals 13 to 15 years of age, exhibiting growth rates similar to extant birds and mammals, and that annual growth was dependent on resource abundance. Together, our results support the synonomization of "Nanotyrannus" into Tyrannosaurus and fail to support the hypothesized presence of a sympatric tyrannosaurid species of markedly smaller adult body size. Our independent data contribute to mounting evidence for a rapid shift in body size associated with ontogenetic niche partitioning late in T. rex ontogeny and suggest that this species singularly exploited mid- to large-sized theropod niches at the end of the Cretaceous.
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Affiliation(s)
- Holly N. Woodward
- Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, 1111 W. 17th St., Tulsa, OK 74104, USA
| | - Katie Tremaine
- Department of Earth Science, Montana State University, P.O. Box 173480, Bozeman, MT 59717, USA
- Museum of the Rockies, Montana State University, 600 W. Kagy Blvd., Bozeman, MT 59717, USA
| | - Scott A. Williams
- Museum of the Rockies, Montana State University, 600 W. Kagy Blvd., Bozeman, MT 59717, USA
| | - Lindsay E. Zanno
- Paleontology, North Carolina Museum of Natural Sciences, 11 W. Jones St., Raleigh, NC 27601, USA
- Department of Biological Sciences, North Carolina State University, 3510 Thomas Hall, Campus Box 7614, Raleigh, NC 2769, USA
| | - John R. Horner
- Chapman University, 1 University Dr., Orange, CA 92866, USA
| | - Nathan Myhrvold
- Intellectual Ventures, 3150 139th Avenue Southeast, Bellevue, WA 98005, USA
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Raguin E, Drapeau MSM. Relation between cross-sectional bone geometry and double zonal osteon frequency and morphology. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 171:598-612. [PMID: 31675105 DOI: 10.1002/ajpa.23954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/08/2019] [Accepted: 10/15/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVES While double-zonal osteons (DZ) are characterized by a hyper-mineralized ring inside their lamellae, recent findings suggest that this ring is also defined by a change in the collagen fibers' orientation. Collagen and minerals are essential components to the maintenance of adequate bone strength and their alteration can modify the mechanical properties of the bone tissue. Consequently, the aim of this study is to explore the effect of past loads, as estimated from cross-sectional geometric properties, on the formation of DZ osteons compared to type I (common) osteons. MATERIALS AND METHODS The sample consists of paired humerus and femur midshaft sections (n = 23) of Eurocanadian settlers from the historical St. Matthew cemetery, Quebec City (1771-1860). Histomorphometric variables included in this study are osteon density for DZ and type I osteons (DZD; OPD), osteon area (DZOn.Ar; On. Ar), Haversian canal area (DZH.Ar; H.Ar), and the area within the hypermineralized ring (HR. Ar). Loading history is estimated from cross-sectional properties including the following variable: cortical and total area (CA, TA), maximum and minimum second moment of area (Imax , Imin ) and polar moment of area (J). RESULTS When the humerus and femur of the same individuals are compared, the femur has a higher OPD, DZD, and relative DZD (DZD/OPD). DZ osteons have a smaller area and Haversian canal area compared to type I osteons. The area within the hypermineralized ring in DZ is higher than the Haversian canal area of the type I osteons. Correlations between the residual scores of the regression of histomorphometric variables and cross-sectional properties of the humerus on the femur were not significant. DISCUSSION Based on the analysis of the entire cross-section, the lack of correlation between variations in cross-sectional properties and remodeling combined with the significant differences between humeri and femura suggests that the creation of DZ or type I osteons in the bone tissue might be due to a bone specific response, possibly related to differences in bone tissue age that needs to be further investigated. Definitive conclusion regarding biomechanical loads still seem to be premature as regional variations associated with mechanical properties remain to be explored.
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Affiliation(s)
- Emeline Raguin
- Département d'anthropologie, Université de Montréal, Montréal, Québec, Canada
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Skedros JG, Doutré MS. Collagen fiber orientation pattern, osteon morphology and distribution, and presence of laminar histology do not distinguish torsion from bending in bat and pigeon wing bones. J Anat 2019; 234:748-763. [PMID: 30924933 DOI: 10.1111/joa.12981] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2019] [Indexed: 12/17/2022] Open
Abstract
Bone can adapt to its habitual load history at various levels of its hierarchical structural and material organization. However, it is unclear how strongly a bone's structural characteristics (e.g. cross-sectional shape) are linked to microstructural characteristics (e.g. distributions of osteons and their vascular canals) or ultrastructural characteristics [e.g. patterns of predominant collagen fiber orientation (CFO)]. We compared the cross-sectional geometry, microstructure and ultrastructure of pigeon (Columba livia domestica) humeri, and third metacarpals (B3M) and humeri of a large bat (Pteropus poliocephalus). The pigeon humerus is habitually torsionally loaded, and has unremodeled ('primary') bone with vessels (secondary osteons are absent) and high 'laminarity' because a large majority of these vessels course circularly with respect to the bone's external surface. In vivo data show that the bat humerus is also habitually torsionally loaded; this contrasts with habitual single-plane bending of the B3M, where in vivo data show that it oscillates back and forth in the same direction. In contrast to pigeon humeri where laminar bone is present, the primary tissue of these bat bones is largely avascular, but secondary osteons are present and are usually in the deeper cortex. Nevertheless, the load history of humeri of both species is prevalent/predominant torsion, producing diffusely distributed shear stresses throughout the cross-section. We tested the hypothesis that despite microstructural/osteonal differences in these pigeon and bat bones, they will have similar characteristics at the ultrastructural level that adapt each bone for its load history. We postulate that predominant CFO is this characteristic. However, even though data reported in prior studies of bones of non-flying mammals suggest that CFO would show regional variations in accordance with the habitual 'tension regions' and 'compression regions' in the direction of unidirectional habitual bending, we hypothesized that alternating directions of bending within the same plane would obviate these regional/site-specific adaptations in the B3M. Similarly, but for other reasons, we did not expect regional variations in CFO in the habitually torsionally loaded bat and pigeon humeri because uniformly oblique-to-transverse CFO is the adaptation expected for the diffusely distributed shear stresses produced by torsion/multidirectional loads. We analyzed transverse sections from mid-diaphyses of adult bones for CFO, secondary osteon characteristics (size, shape and population density), cortical thickness in quadrants of the cortex, and additional measures of cross-sectional geometry, including the degree of circular shape that can help distinguish habitual torsion from bending. Results showed the expected lack of regional CFO differences in quasi-circular shaped, and torsionally loaded, pigeon and bat humeri. As expected, the B3M also lacked CFO variations between the opposing cortices along the plane of bending, and the quasi-elliptical cross-sectional shape and regional microstructural/osteonal variations expected for bending were not found. These findings in the B3M show that uniformity in CFO does not always reflect habitual torsional loads. Osteon morphology and distribution, and presence of laminar histology also do not distinguish torsion from bending in these bat and pigeon wing bones.
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Affiliation(s)
- John G Skedros
- Bone and Joint Research Laboratory, George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Orthopaedic Surgery, The University of Utah, Salt Lake City, UT, USA
| | - Madison S Doutré
- Bone and Joint Research Laboratory, George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
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15
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Rajão MD, Leite CS, Nogueira K, Godoy RF, Lima EMM. The bone response in endurance long distance horse. Open Vet J 2019; 9:58-64. [PMID: 31086768 PMCID: PMC6500865 DOI: 10.4314/ovj.v9i1.11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 02/14/2019] [Indexed: 11/30/2022] Open
Abstract
The aim of this study was to understand the bone response against the exercise adaptations to reduce the occurrence of orthopedic injuries in endurance horses. To this end, the objective of the present work was to investigate how the bone adaptation on adult equines that were trained for 4–5 yr to endurance races responds to the long-term exercise of moderate intensity by comparing to non-athlete horses. For this purpose, 14 Arabian horses were selected and divided equally into two groups; a control group formed by animals that had never practiced physical activity nor been tamed and an exercise group formed by athlete animals. Radiographs were obtained using a digital radiography system and penetrometer. The radiographs were stored and later processed to determine cortical bone thickness using the ProgRes® Capture Pro 2.5 (Jenoptik, Germany), cortical bone density using Adobe Photoshop CS6 (version 6.0, Adobe Systems Inc., San Jose, CA), and trabecular bone density using the Image-Pro Plus 4.1 (Media Cybernetics Inc. Silver Springs, MD). The EG presented an increase in cortical bone density and thickness compared to the control. This adaptation of the cortical bone in the exercised horses is an important factor in increasing bone resistance to exercise. These structural changes are related to a morphofunctional response by the bone tissue as a whole.
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Affiliation(s)
- Mariana Damazio Rajão
- Department of Veterinary Anatomy, Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília (UnB), ICC Ala Sul, Campus Darcy Ribeiro, Brasília DF 70760-701, Brazil
| | - Carol S Leite
- Department of Veterinary Anatomy, Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília (UnB), ICC Ala Sul, Campus Darcy Ribeiro, Brasília DF 70760-701, Brazil
| | - Kaique Nogueira
- Department of Veterinary Anatomy, Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília (UnB), ICC Ala Sul, Campus Darcy Ribeiro, Brasília DF 70760-701, Brazil
| | - Roberta F Godoy
- Writtle University College, Chelmsford CM1 3RR, United Kingdom
| | - Eduardo Maurício Mendes Lima
- Department of Veterinary Anatomy, Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília (UnB), ICC Ala Sul, Campus Darcy Ribeiro, Brasília DF 70760-701, Brazil
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16
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Skedros JG, Su SC, Knight AN, Bloebaum RD, Bachus KN. Advancing the deer calcaneus model for bone adaptation studies: ex vivo strains obtained after transecting the tension members suggest an unrecognized important role for shear strains. J Anat 2018; 234:66-82. [PMID: 30411344 DOI: 10.1111/joa.12905] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2018] [Indexed: 12/15/2022] Open
Abstract
Sheep and deer calcanei are finding increased use as models for studies of bone adaptation, including advancing understanding of how the strain (deformation) environment influences the ontogenetic emergence of biomechanically relevant structural and material variations in cortical and trabecular bone. These artiodactyl calcanei seem ideal for these analyses because they function like simply loaded short-cantilevered beams with net compression and tension strains on the dorsal and plantar cortices, respectively. However, this habitual strain distribution requires more rigorous validation because it has been shown by limited in vivo and ex vivo strain measurements obtained during controlled ambulation (typically walking and trotting). The conception that these calcanei are relatively simply and habitually loaded 'tension/compression bones' could be invalid if infrequent, though biologically relevant, loads substantially change the location of the neutral axis (NA) that separates 'compression' and 'tension' regions. The effect on calcaneus strains of the tension members (plantar ligament and flexor tendon) is also not well understood and measuring strains after transecting them could reveal that they significantly modulate the strain distribution. We tested the hypothesis that the NA location previously described during simulated on-axis loads of deer calcanei would exhibit limited variations even when load perturbations are unusual (e.g. off-axis loads) or extreme (e.g. after transection of the tension members). We also examined regional differences in the predominance of the three strain modes (tension, compression, and shear) in these various load conditions in dorsal, plantar, medial, and lateral cortices. In addition to considering principal strains (tension and compression) and maximum shear strains, we also considered material-axis (M-A) shear strains. M-A shear strains are those that are aligned along the long axis of the bone and are considered to have greater biomechanical relevance than maximum shear strains because failure theories of composite materials and bone are often based on stresses or strains in the principal material directions. We used the same load apparatus from our prior study of mule deer calcanei. Results showed that although the NA rotated up to 8° medially and 15° laterally during these off-axis loads, it did not shift dramatically until after transection of all tension members. When comparing results based on maximum shear strain data vs. M-A shear strain data, the dominant strain mode changed only in the plantar cortex - as expected (in accordance with our a priori view) it was tension when M-A shear strains were considered (shear : tension = 0.2) but changed to dominant shear when maximum shear strain data were considered (shear : tension = 1.3). This difference leads to different conclusions and speculations regarding which specific strain modes and magnitudes most strongly influence the emergence of the marked mineralization and histomorphological differences in the dorsal vs. plantar cortices. Consequently, our prior simplification of the deer calcaneus model as a simply loaded 'tension/compression bone' (i.e. plantar/dorsal) might be incorrect. In vivo and in finite element analyses are needed to determine whether describing it as a 'shear-tension/compression' bone is more accurate. Addressing this question will help to advance the artiodactyl calcaneus as an experimental model for bone adaptation studies.
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Affiliation(s)
- John G Skedros
- Department of Orthopedics, University of Utah, Salt Lake City, UT, USA.,Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Steven C Su
- Department of Orthopedics, University of Utah, Salt Lake City, UT, USA.,Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Alex N Knight
- Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Roy D Bloebaum
- Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Kent N Bachus
- Department of Orthopedics, University of Utah, Salt Lake City, UT, USA.,Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
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17
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Beresheim AC, Pfeiffer SK, Alblas A. The Influence of Body Size and Bone Mass on Cortical Bone Histomorphometry in Human Ribs. Anat Rec (Hoboken) 2018; 301:1788-1796. [DOI: 10.1002/ar.23933] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/14/2018] [Accepted: 01/17/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Amy C. Beresheim
- Department of Anthropology; University of Toronto; Toronto Ontario Canada
| | - Susan K. Pfeiffer
- Department of Anthropology; University of Toronto; Toronto Ontario Canada
- Department of Archaeology; University of Cape Town; Rondebosch South Africa
| | - Amanda Alblas
- Division of Anatomy and Histology, Department of Biomedical Sciences; Faculty of Medicine and Health Sciences, Stellenbosch University; Cape Town South Africa
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18
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Raguin E, Streeter MA. Brief communication: Test of a method to identify double-zonal osteon in polarized light microscopy. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 167:407-415. [PMID: 30132791 DOI: 10.1002/ajpa.23616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/23/2018] [Accepted: 05/09/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Double-zonal osteons (DZ) have been of interest in paleopathological research because they might be linked to physiological pathology. DZ are thought to be evidence of arrested osteon formation with a brief but abrupt increase in mineralization of lamellae occurring during bone remodeling. Originally identified from microradiographs as hypermineralized rings, recent studies have identified DZ from linear polarized light microscopy (PLM). However, PLM does not guarantee the adequate detection of DZ since PLM captures bone birefringence and not hyper-mineralization. Scanning electron microscopy with backscatter electrons (BSE-SEM) allows observation of DZ by detecting differences in mineralization. The purpose of this study is to investigate whether DZ, as identified by BSE-SEM, can indeed be identified with PLM. MATERIALS AND METHODS The sample consists of an archaeological collection of adult midshaft femurs (n = 30) from St. Matthew cemetery, Quebec City (1771-1860). DZ were identified and counted independently with PLM and BSE-SEM for the same sections. Results from both methods were compared. RESULTS Chi-square test shows that there was no significant difference between the two methods (p = 0.404). No significant bias was found on Bland-Altman analysis and Cohen's kappa shows a substantial agreement between the two methods (Κ = 0.66). PLM shows a good accuracy (sensitivity 79%, specificity 99.4%) and reliability (Positive Predictive Value: 86.71%; Negative Predictive Value: 99.45%). DISCUSSION These findings indicate that the two methods are interchangeable. PLM, using our proposed protocol, is reliable to accurately identify DZ. We discuss how PLM and BSE-SEM that measure different features of the bone tissue can converge on the identification of DZ.
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Affiliation(s)
- Emeline Raguin
- Département d'anthropologie, Université de Montréal, Montréal, Québec, H3C 3J7, Canada
| | - Margaret A Streeter
- Department of Anthropology, Boise State University, Boise, Idaho, 83725-1950
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19
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Rolvien T, Vom Scheidt A, Stockhausen KE, Milovanovic P, Djonic D, Hubert J, Hawellek T, Wacker A, Jebens V, Püschel K, Zimmermann EA, Djuric M, Amling M, Busse B. Inter-site variability of the osteocyte lacunar network in the cortical bone underpins fracture susceptibility of the superolateral femoral neck. Bone 2018; 112:187-193. [PMID: 29679732 DOI: 10.1016/j.bone.2018.04.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/02/2018] [Accepted: 04/18/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND The osteocytic lacunar network is considered to be an integral player in the regulation of bone homeostasis, and reduction in osteocytes is associated with reduced bone strength. Here, we analyzed site-specific patterns in osteocyte characteristics and matrix composition in the cortical compartment of the femoral neck to reveal the structural basis of its fragility. METHODS Cross-sections of the human femoral neck - one of the most common fracture sites - were acquired from 12 female cadavers (age 34-86 years) and analyzed with backscattered scanning electron microscopy and high-resolution micro-computed tomography (μ-CT). The 2D/3D density and size of the osteocyte lacunae as well as bone mineral density distribution (BMDD) were measured in two regions subject to different biomechanical loads in vivo: the inferomedial (medial) region (habitually highly loaded in compression) and the superolateral (lateral) region (lower habitual loading intensity). Using quantitative polarized light microscopy, collagen fiber orientation was quantified in these two regions, accordingly. RESULTS In 2D measurements, the inferomedial region displayed lower mineralization heterogeneity, 19% higher osteocyte lacunar density (p = 0.005), but equal lacunar size compared to the superolateral region. 3D measurements confirmed a significantly higher osteocyte lacunar density in the inferomedial region (p = 0.015). Osteocyte lacunar density decreased in aged individuals, and inter-site differences were reduced. Site-specific osteocyte characteristics were not accompanied by changes in collagen fiber orientation. CONCLUSIONS Since osteocyte characteristics may provide valuable insights into bone mechanical competence, the variations in osteocyte properties might reflect the increased fracture susceptibility of the superolateral neck.
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Affiliation(s)
- Tim Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
| | - Annika Vom Scheidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Kilian E Stockhausen
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Petar Milovanovic
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, 11000 Belgrade, Serbia
| | - Danijela Djonic
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, 11000 Belgrade, Serbia
| | - Jan Hubert
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
| | - Thelonius Hawellek
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
| | - Alexander Wacker
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
| | - Volker Jebens
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
| | - Klaus Püschel
- Department of Legal Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529 Hamburg, Germany
| | - Elizabeth A Zimmermann
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Marija Djuric
- Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Dr Subotica 4/2, 11000 Belgrade, Serbia
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany.
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Skedros JG, Henrie TR, Doutré MS, Bloebaum RD. Sealed osteons in animals and humans: low prevalence and lack of relationship with age. J Anat 2018; 232:824-835. [PMID: 29460315 PMCID: PMC6429975 DOI: 10.1111/joa.12786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2018] [Indexed: 11/28/2022] Open
Abstract
Sealed osteons are unusual variants of secondary osteons that have received little attention, especially in non-human bones. Sealed osteons are characterized by central canals that are plugged with bone tissue. As with other variants of secondary osteons (e.g. drifting, dumbbell, multi-canal), understanding how and why sealed osteons form can shed light on the mechanisms that regulate normal bone remodeling and how this process can be perturbed with aging and some diseases. In a recent microscopic evaluation of human tibiae obtained after traumatic amputations, 4-5% of the osteons were sealed. It is suggested that this high prevalence reflects occasional localized microscopic ischemia from normal osteonal remodeling; hence sealed osteons are implicated in human skeletal fragility. Therefore, osteon prevalence would be expected to correlate with the bone remodeling seen with aging; for example, showing positive relationships between sealed osteons and the population density of typical secondary osteons (OPD). We evaluated the prevalence of partially sealed (80-99% sealed) and fully sealed osteons with respect to age and variations in OPD in 10 adult human femora (34-71 years) and in various non-human appendicular bones of mature animals that were not of advanced age, including deer calcanei, equine radii and equine third metacarpals. An additional sample of 10 bilateral human femora with unilateral non-cemented total hip replacements (F,+HR) and non-implanted contralateral femora (F,-HR) were evaluated (10 patients; 52-94 years). In non-human bones, sealed + partially sealed osteons were rare (~0.1%) even when having relatively high OPD. When considering sealed + partially sealed osteons in femora from patients without any HR, results showed that 1.6% of the osteons were sealed or partially sealed, which was much lower than anticipated, but this is 10- to 20-fold more than in any of the non-human bones. Additionally, in all bones, sealed + partially sealed osteons were significantly smaller than typical secondary osteons (mean diameters: 125 vs. 272 μm; P < 0.005). In the patients with HR, the percentage of sealed + partially sealed osteons: (i) did not correlate with age, (ii) showed no significant difference between F,-HR and F,+HR (1.9 vs. 2.1%; P = 0.2), and (iii) was positively correlated with OPD (r = 0.67, P = 0.001), which differs from the very weak or lack of correlations in the non-human bones and the other human femur sample. The lack of an age-related relationship, in addition to the very low prevalence of sealed + partially sealed osteons are inconsistent with the idea that they contribute to reduced bone quality seen in aging humans. The small size of sealed and partially sealed osteons, regardless of species affiliation, suggests that they represent closing cones at the termini of some osteons. Available evidence suggests that osteons of primates might have a greater capacity for branching that is associated with closing cones, which might explain the 10-20 times higher prevalence of sealed + partially sealed osteons in the human bones examined in this study.
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Affiliation(s)
- John G. Skedros
- George E. Whalen Department of Veterans Affairs Medical CenterBone and Joint Research LaboratorySalt Lake CityUTUSA
- Department of Orthopaedic SurgeryThe University of UtahSalt Lake CityUTUSA
| | - Tanner R. Henrie
- George E. Whalen Department of Veterans Affairs Medical CenterBone and Joint Research LaboratorySalt Lake CityUTUSA
- Department of Orthopaedic SurgeryThe University of UtahSalt Lake CityUTUSA
| | - Madison S. Doutré
- George E. Whalen Department of Veterans Affairs Medical CenterBone and Joint Research LaboratorySalt Lake CityUTUSA
- Department of Orthopaedic SurgeryThe University of UtahSalt Lake CityUTUSA
| | - Roy D. Bloebaum
- George E. Whalen Department of Veterans Affairs Medical CenterBone and Joint Research LaboratorySalt Lake CityUTUSA
- Department of Orthopaedic SurgeryThe University of UtahSalt Lake CityUTUSA
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Tang T, Cripton PA, Guy P, McKay HA, Wang R. Clinical hip fracture is accompanied by compression induced failure in the superior cortex of the femoral neck. Bone 2018; 108:121-131. [PMID: 29277713 DOI: 10.1016/j.bone.2017.12.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/22/2017] [Accepted: 12/20/2017] [Indexed: 10/18/2022]
Abstract
Hip fractures pose a major health problem throughout the world due to their devastating impact. Current theories for why these injuries are so prevalent in the elderly point to an increased propensity to fall and decreases in bone mass with ageing. However, the fracture mechanisms, particularly the stress and strain conditions leading to bone failure at the hip remain unclear. Here, we directly examined the cortical bone from clinical intra-capsular hip fractures at a microscopic level, and found strong evidence of compression induced failure in the superior cortex. A total of 143 sections obtained from 24 femoral neck samples that were retrieved from 24 fracturing patients at surgery were examined using laser scanning confocal microscopy (LSCM) after fluorescein staining. The stained microcracks showed significantly higher density in the superior cortex than in the inferior cortex, indicating a greater magnitude of strain in the superior femoral neck during the failure-associated deformation and fracture process. The predominant stress state for each section was reconstructed based on the unique correlation between the microcrack pattern and the stress state. Specifically, we found clear evidence of longitudinal compression and buckling as the primary failure mechanisms in the superior cortex. These findings demonstrate the importance of microcrack analysis in studying clinical hip fractures, and point to the central role of the superior cortex failure as an important aspect of the failure initiation in clinical intra-capsular hip fractures.
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Affiliation(s)
- Tengteng Tang
- Department of Materials Engineering, University of British Columbia, Vancouver, BC, Canada; Centre for Hip Health and Mobility, Vancouver, BC, Canada
| | - Peter A Cripton
- Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, Canada; Centre for Hip Health and Mobility, Vancouver, BC, Canada; International Collaboration On Repair Discoveries, Vancouver, BC, Canada
| | - Pierre Guy
- Department of Orthopaedics, University of British Columbia, Vancouver, BC, Canada; Centre for Hip Health and Mobility, Vancouver, BC, Canada
| | - Heather A McKay
- Department of Orthopaedics, University of British Columbia, Vancouver, BC, Canada; Centre for Hip Health and Mobility, Vancouver, BC, Canada
| | - Rizhi Wang
- Department of Materials Engineering, University of British Columbia, Vancouver, BC, Canada; Centre for Hip Health and Mobility, Vancouver, BC, Canada.
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Warshaw J, Bromage TG, Terranova CJ, Enlow DH. Collagen Fiber Orientation in Primate Long Bones. Anat Rec (Hoboken) 2017; 300:1189-1207. [PMID: 28205407 DOI: 10.1002/ar.23571] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 01/31/2016] [Accepted: 02/10/2016] [Indexed: 11/07/2022]
Abstract
Studies of variation in orientation of collagen fibers within bone have lead to the proposition that these are preferentially aligned to accommodate different kinds of load, with tension best resisted by fibers aligned longitudinally relative to the load, and compression best resisted by transversely aligned fibers. However, previous studies have often neglected to consider the effect of developmental processes, including constraints on collagen fiber orientation (CFO), particularly in primary bone. Here we use circularly polarized light microscopy to examine patterns of CFO in cross-sections from the midshaft femur, humerus, tibia, radius, and ulna in a range of living primate taxa with varied body sizes, phylogenetic relationships and positional behaviors. We find that a preponderance of longitudinally oriented collagen is characteristic of both periosteal primary and intracortically remodeled bone. Where variation does occur among groups, it is not simply understood via interpretations of mechanical loads, although prioritized adaptations to tension and/or shear are considered. While there is some suggestion that CFO may correlate with body size, this relationship is neither consistent nor easily explicable through consideration of size-related changes in mechanical adaptation. The results of our study indicate that there is no clear relationship between CFO and phylogenetic status. One of the principle factors accounting for the range of variation that does exist is primary tissue type, where slower depositing bone is more likely to comprise a larger proportion of oblique to transverse collagen fibers. Anat Rec, 300:1189-1207, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Johanna Warshaw
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York
| | - Timothy G Bromage
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York.,Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, New York
| | - Carl J Terranova
- Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Donald H Enlow
- Thomas Hill Emeritus Professor, Department of Orthodontics, Case Western Reserve University, Cleveland, Ohio
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Keenan KE, Mears CS, Skedros JG. Utility of osteon circularity for determining species and interpreting load history in primates and nonprimates. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017; 162:657-681. [PMID: 28121024 DOI: 10.1002/ajpa.23154] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 10/31/2016] [Accepted: 12/02/2016] [Indexed: 11/07/2022]
Abstract
OBJECTIVES Histomorphological analyses of bones are used to estimate an individual's chronological age, interpret a bone's load history, and differentiate species. Among various histomorphological characteristics that can influence mechanical properties of cortical bone, secondary osteon (Haversian system) population density and predominant collagen fiber orientation are particularly important. Cross-sectional shape characteristics of secondary osteons (On.Cr = osteon circularity, On.El = osteon ellipticality) are considered helpful in these contexts, but more robust proof is needed. We sought to determine if variations in osteon shape characteristics are sufficient for accurately differentiating species, load-complexity categories, and regional habitual strain-mode distributions (e.g., tension vs. compression regions). MATERIALS AND METHODS Circularly polarized light images were obtained from 100-micron transverse sections from diaphyses of adult deer calcanei; sheep calcanei, radii, and tibiae; equine calcanei, radii, and third metacarpals (MC3s); chimpanzee femora; and human femora and fibulae. Osteon cross-sectional area (On.Ar), On.Cr, and On.El were quantified indiscriminately and in the contexts of load-complexity and regional strain-mode distributions. RESULTS On.Cr and On.El, when examined independently in terms of all data, or mean (nested) data, for each bone, exceeded 80% accuracy in the inter-species comparisons only with respect to distinguishing humans from nonhumans. Correct classification among the nonhuman species was <70%. When On.Cr and On.El were coupled together and with On.Ar in discriminant function analyses (nested and unnested data) there were high misclassifications in all but human vs. nonhuman comparisons. DISCUSSION Frequent misclassifications in nonhuman comparisons might reflect influences of habitual load complexity and/or strain-mode distributions, or other factors not accounted for by these two considerations.
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Affiliation(s)
- Kendra E Keenan
- Bone and Joint Research Laboratory, George E. Whalen Veteran's Affairs Medical Center, Salt Lake City, Utah
| | - Chad S Mears
- Bone and Joint Research Laboratory, George E. Whalen Veteran's Affairs Medical Center, Salt Lake City, Utah
| | - John G Skedros
- Bone and Joint Research Laboratory, George E. Whalen Veteran's Affairs Medical Center, Salt Lake City, Utah
- Department of Orthopaedics, University of Utah, Salt Lake City, Utah, 84132
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Goliath JR, Stewart MC, Stout SD. Variation in osteon histomorphometrics and their impact on age-at-death estimation in older individuals. Forensic Sci Int 2016; 262:282.e1-6. [DOI: 10.1016/j.forsciint.2016.02.053] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 02/28/2016] [Accepted: 02/29/2016] [Indexed: 10/22/2022]
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Gocha TP, Agnew AM. Spatial variation in osteon population density at the human femoral midshaft: histomorphometric adaptations to habitual load environment. J Anat 2015; 228:733-45. [PMID: 26708961 DOI: 10.1111/joa.12433] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2015] [Indexed: 12/01/2022] Open
Abstract
Intracortical remodeling, and the osteons it produces, is one aspect of the bone microstructure that is influenced by and, in turn, can influence its mechanical properties. Previous research examining the spatial distribution of intracortical remodeling density across the femoral midshaft has been limited to either considering only small regions of the cortex or, when looking at the entirety of the cortex, considering only a single individual. This study examined the spatial distribution of all remodeling events (intact osteons, fragmentary osteons, and resorptive bays) across the entirety of the femoral midshaft in a sample of 30 modern cadaveric donors. The sample consisted of 15 males and 15 females, aged 21-97 years at time of death. Using geographic information systems software, the femoral cortex was subdivided radially into thirds and circumferentially into octants, and the spatial location of all remodeling events was marked. Density maps and calculation of osteon population density in cortical regions of interest revealed that remodeling density is typically highest in the periosteal third of the bone, particularly in the lateral and anterolateral regions of the cortex. Due to modeling drift, this area of the midshaft femur has some of the youngest primary tissue, which consequently reveals that the lateral and anterolateral regions of the femoral midshaft have higher remodeling rates than elsewhere in the cortex. This is likely the result of tension/shear forces and/or greater strain magnitudes acting upon the anterolateral femur, which results in a greater amount of microdamage in need of repair than is seen in the medial and posterior regions of the femoral midshaft, which are more subject to compressive forces and/or lesser strain magnitudes.
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Affiliation(s)
- Timothy P Gocha
- Skeletal Biology Research Lab, Division of Anatomy, Injury Biomechanics Research Center, The Ohio State University, Columbus, OH, USA
| | - Amanda M Agnew
- Skeletal Biology Research Lab, Division of Anatomy, Injury Biomechanics Research Center, The Ohio State University, Columbus, OH, USA.,Department of Anthropology, The Ohio State University, Columbus, OH, USA
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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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Induction and quantification of collagen fiber alignment in a three-dimensional hydroxyapatite-collagen composite scaffold. Acta Biomater 2015; 17:26-35. [PMID: 25653215 DOI: 10.1016/j.actbio.2015.01.033] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 12/19/2014] [Accepted: 01/22/2015] [Indexed: 11/21/2022]
Abstract
Hydroxyapatite-collagen composite scaffolds are designed to serve as a regenerative load bearing replacement that mimics bone. However, the material properties of these scaffolds are at least an order of magnitude less than that of bone and subject to fail under physiological loading conditions. These scaffolds compositionally resemble bone but they do not possess important structural attributes such as an ordered arrangement of collagen fibers, which is a correlate to the mechanical properties in bone. Furthermore, it is unclear how much ordering of structure is satisfactory to mimic bone. Therefore, quantitative methods are needed to characterize collagen fiber alignment in these scaffolds for better correlation between the scaffold structure and the mechanical properties. A combination of extrusion and compaction was used to induce collagen fiber alignment in composite scaffolds. Collagen fiber alignment, due to extrusion and compaction, was quantified from polarized light microscopy images with a Fourier transform image processing algorithm. The Fourier transform method was capable of resolving the degree of collagen alignment from polarized light images. Anisotropy indices of the image planes ranged from 0.08 to 0.45. Increases in the degree of fiber alignment induced solely by extrusion (0.08-0.25) or compaction (0.25-0.44) were not as great as those by the combination of extrusion and compaction (0.35-0.45). Additional measures of randomness and fiber direction corroborate these anisotropy findings. This increased degree of collagen fiber alignment was induced in a preferred direction that is consistent with the extrusion direction and parallel with the compacted plane.
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Biomechanical Properties of the Equine Third Metacarpal Bone: In Vivo Quantitative Ultrasonography Versus Ex Vivo Compression and Bending Techniques. J Equine Vet Sci 2015. [DOI: 10.1016/j.jevs.2014.12.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Harrison KD, Cooper DML. Modalities for Visualization of Cortical Bone Remodeling: The Past, Present, and Future. Front Endocrinol (Lausanne) 2015; 6:122. [PMID: 26322017 PMCID: PMC4531299 DOI: 10.3389/fendo.2015.00122] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 07/24/2015] [Indexed: 11/24/2022] Open
Abstract
Bone's ability to respond to load-related phenomena and repair microdamage is achieved through the remodeling process, which renews bone by activating groups of cells known as basic multicellular units (BMUs). The products of BMUs, secondary osteons, have been extensively studied via classic two-dimensional techniques, which have provided a wealth of information on how histomorphology relates to skeletal structure and function. Remodeling is critical in maintaining healthy bone tissue; however, in osteoporotic bone, imbalanced resorption results in increased bone fragility and fracture. With increasing life expectancy, such degenerative bone diseases are a growing concern. The three-dimensional (3D) morphology of BMUs and their correlation to function, however, are not well-characterized and little is known about the specific mechanisms that initiate and regulate their activity within cortical bone. We believe a key limitation has been the lack of 3D information about BMU morphology and activity. Thus, this paper reviews methodologies for 3D investigation of cortical bone remodeling and, specifically, structures associated with BMU activity (resorption spaces) and the structures they create (secondary osteons), spanning from histology to modern ex vivo imaging modalities, culminating with the growing potential of in vivo imaging. This collection of papers focuses on the theme of "putting the 'why' back into bone architecture." Remodeling is one of two mechanisms "how" bone structure is dynamically modified and thus an improved 3D understanding of this fundamental process is crucial to ultimately understanding the "why."
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Affiliation(s)
- Kimberly D. Harrison
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - David M. L. Cooper
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK, Canada
- *Correspondence: David M. L. Cooper, Department of Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada,
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Martinez-Maza C, Alberdi MT, Nieto-Diaz M, Prado JL. Life-history traits of the Miocene Hipparion concudense (Spain) inferred from bone histological structure. PLoS One 2014; 9:e103708. [PMID: 25098950 PMCID: PMC4123897 DOI: 10.1371/journal.pone.0103708] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 07/04/2014] [Indexed: 11/18/2022] Open
Abstract
Histological analyses of fossil bones have provided clues on the growth patterns and life history traits of several extinct vertebrates that would be unavailable for classical morphological studies. We analyzed the bone histology of Hipparion to infer features of its life history traits and growth pattern. Microscope analysis of thin sections of a large sample of humeri, femora, tibiae and metapodials of Hipparion concudense from the upper Miocene site of Los Valles de Fuentidueña (Segovia, Spain) has shown that the number of growth marks is similar among the different limb bones, suggesting that equivalent skeletochronological inferences for this Hipparion population might be achieved by means of any of the elements studied. Considering their abundance, we conducted a skeletechronological study based on the large sample of third metapodials from Los Valles de Fuentidueña together with another large sample from the Upper Miocene locality of Concud (Teruel, Spain). The data obtained enabled us to distinguish four age groups in both samples and to determine that Hipparion concudense tended to reach skeletal maturity during its third year of life. Integration of bone microstructure and skeletochronological data allowed us to identify ontogenetic changes in bone structure and growth rate and to distinguish three histologic ontogenetic stages corresponding to immature, subadult and adult individuals. Data on secondary osteon density revealed an increase in bone remodeling throughout the ontogenetic stages and a lesser degree thereof in the Concud population, which indicates different biomechanical stresses in the two populations, likely due to environmental differences. Several individuals showed atypical growth patterns in the Concud sample, which may also reflect environmental differences between the two localities. Finally, classification of the specimens’ age within groups enabled us to characterize the age structure of both samples, which is typical of attritional assemblages.
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Affiliation(s)
- Cayetana Martinez-Maza
- Department of Paleobiology, Museo Nacional de Ciencias Naturales – CSIC, Madrid, Spain
- * E-mail:
| | - Maria Teresa Alberdi
- Department of Paleobiology, Museo Nacional de Ciencias Naturales – CSIC, Madrid, Spain
| | - Manuel Nieto-Diaz
- Molecular Neuroprotection Group, Hospital Nacional de Parapléjicos Toledo, Toledo, Castilla la Mancha, Spain
| | - José Luis Prado
- UE INCUAPA, CONICET-UNICEN University of Olavarria, Olavarria, Argentina
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Histocompositional organization and toughening mechanisms in antler. J Struct Biol 2014; 187:129-148. [DOI: 10.1016/j.jsb.2014.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/04/2014] [Accepted: 06/13/2014] [Indexed: 12/16/2022]
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Dumont M, Borbely A, Kaysser-Pyzalla A, Sander PM. Long bone cortices in a growth series ofApatosaurussp. (Dinosauria: Diplodocidae): geometry, body mass, and crystallite orientation of giant animals. Biol J Linn Soc Lond 2014. [DOI: 10.1111/bij.12335] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Maitena Dumont
- Max-Planck-Institut für Eisenforschung GmbH; Max-Planck-Strasse 1 40237 Düsseldorf Germany
| | - Andras Borbely
- UMR 5146; École Nationale Supérieure des Mines de Saint-Étienne; 158, cours Fauriel, F-42023 Saint-Étienne cedex 2 France
| | - Anke Kaysser-Pyzalla
- Division of Paleontology, Steinmann Institute; University of Bonn; Nussallee 8 53115 Bonn Germany
| | - P. Martin Sander
- Helmholtz-Zentrum Berlin GmbH; Hahn-Meitner-Platz 1 14109 Berlin Germany
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Goldman HM, Hampson NA, Guth JJ, Lin D, Jepsen KJ. Intracortical remodeling parameters are associated with measures of bone robustness. Anat Rec (Hoboken) 2014; 297:1817-28. [PMID: 24962664 DOI: 10.1002/ar.22962] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/21/2014] [Indexed: 11/11/2022]
Abstract
Prior work identified a novel association between bone robustness and porosity, which may be part of a broader interaction whereby the skeletal system compensates for the natural variation in robustness (bone width relative to length) by modulating tissue-level mechanical properties to increase stiffness of slender bones and to reduce mass of robust bones. To further understand this association, we tested the hypothesis that the relationship between robustness and porosity is mediated through intracortical, BMU-based (basic multicellular unit) remodeling. We quantified cortical porosity, mineralization, and histomorphometry at two sites (38% and 66% of the length) in human cadaveric tibiae. We found significant correlations between robustness and several histomorphometric variables (e.g., % secondary tissue [R(2) = 0.68, P < 0.004], total osteon area [R(2) = 0.42, P < 0.04]) at the 66% site. Although these associations were weaker at the 38% site, significant correlations between histological variables were identified between the two sites indicating that both respond to the same global effects and demonstrate a similar character at the whole bone level. Thus, robust bones tended to have larger and more numerous osteons with less infilling, resulting in bigger pores and more secondary bone area. These results suggest that local regulation of BMU-based remodeling may be further modulated by a global signal associated with robustness, such that remodeling is suppressed in slender bones but not in robust bones. Elucidating this mechanism further is crucial for better understanding the complex adaptive nature of the skeleton, and how interindividual variation in remodeling differentially impacts skeletal aging and an individuals' potential response to prophylactic treatments.
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Affiliation(s)
- Haviva M Goldman
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania; Department of Materials Science and Engineering, Drexel University College of Engineering, Philadelphia, Pennsylvania
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Spiesz EM, Reisinger AG, Kaminsky W, Roschger P, Pahr DH, Zysset PK. Computational and experimental methodology for site-matched investigations of the influence of mineral mass fraction and collagen orientation on the axial indentation modulus of lamellar bone. J Mech Behav Biomed Mater 2013; 28:195-205. [PMID: 23994944 PMCID: PMC3843116 DOI: 10.1016/j.jmbbm.2013.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/28/2013] [Accepted: 07/04/2013] [Indexed: 12/24/2022]
Abstract
Relationships between mineralization, collagen orientation and indentation modulus were investigated in bone structural units from the mid-shaft of human femora using a site-matched design. Mineral mass fraction, collagen fibril angle and indentation moduli were measured in registered anatomical sites using backscattered electron imaging, polarized light microscopy and nano-indentation, respectively. Theoretical indentation moduli were calculated with a homogenization model from the quantified mineral densities and mean collagen fibril orientations. The average indentation moduli predicted based on local mineralization and collagen fibers arrangement were not significantly different from the average measured experimentally with nanoindentation (p=0.9). Surprisingly, no substantial correlation of the measured indentation moduli with tissue mineralization and/or collagen fiber arrangement was found. Nano-porosity, micro-damage, collagen cross-links, non-collagenous proteins or other parameters affect the indentation measurements. Additional testing/simulation methods need to be considered to properly understand the variability of indentation moduli, beyond the mineralization and collagen arrangement in bone structural units. Site-matched assessment of nanoindentation modulus, mineral mass fraction and collagen fibers orientation in human cortical bone sections. Comparison of experimental nanoindentation modulus with its computed equivalent based on the site-matched morphological data. While mean experimental and computed nanoindentation moduli match well, their variations exhibit very weak correlations. Considering factors like nano-porosity and damage may be necessary to understand variability of lamellar stiffness of bone structural units. This is not in conflict with the well known anisotropy associated with the rotated plywood model at the sublamellar scale.
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Affiliation(s)
- Ewa M Spiesz
- Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Gusshausstrasse 27-29, A-1040 Vienna, Austria; Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, NL-5600 MB Eindhoven, The Netherlands.
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Sinclair KD, Farnsworth RW, Pham TX, Knight AN, Bloebaum RD, Skedros JG. The artiodactyl calcaneus as a potential ‘control bone’ cautions against simple interpretations of trabecular bone adaptation in the anthropoid femoral neck. J Hum Evol 2013; 64:366-79. [DOI: 10.1016/j.jhevol.2013.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 12/08/2012] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
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Skedros JG, Knight AN, Clark GC, Crowder CM, Dominguez VM, Qiu S, Mulhern DM, Donahue SW, Busse B, Hulsey BI, Zedda M, Sorenson SM. Scaling of Haversian canal surface area to secondary osteon bone volume in ribs and limb bones. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 151:230-44. [DOI: 10.1002/ajpa.22270] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 03/06/2013] [Indexed: 11/11/2022]
Affiliation(s)
- John G. Skedros
- Department of Veterans Affairs Medical Center; Bone and Joint Research Laboratory; Salt Lake City; UT
| | - Alex N. Knight
- Department of Veterans Affairs Medical Center; Bone and Joint Research Laboratory; Salt Lake City; UT
| | - Gunnar C. Clark
- Department of Veterans Affairs Medical Center; Bone and Joint Research Laboratory; Salt Lake City; UT
| | - Christian M. Crowder
- Office of the Armed Forces Medical Examiner; Armed Forces Medical Examiner System; Dover AFB; DE
| | | | - Shijing Qiu
- Bone and Mineral Research Laboratory; Henry Ford Hospital; Detroit; MI
| | | | - Seth W. Donahue
- Department of Mechanical Engineering; Colorado State University; Fort Collins; CO
| | - Björn Busse
- Department of Osteology and Biomechanics (IOBM); University Medical Center Hamburg-Eppendorf; Hamburg; Germany
| | | | - Marco Zedda
- Department of Animal Biology; University of Sassari; Sassari; Italy
| | - Scott M. Sorenson
- Department of Veterans Affairs Medical Center; Bone and Joint Research Laboratory; Salt Lake City; UT
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Skedros JG, Keenan KE, Williams TJ, Kiser CJ. Secondary osteon size and collagen/lamellar organization (“osteon morphotypes”) are not coupled, but potentially adapt independently for local strain mode or magnitude. J Struct Biol 2013; 181:95-107. [DOI: 10.1016/j.jsb.2012.10.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 09/27/2012] [Accepted: 10/08/2012] [Indexed: 11/17/2022]
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Yamada S, Tadano S, Fujisaki K, Kodaki Y. Influence of osteon area fraction and degree of orientation of HAp crystals on mechanical properties in bovine femur. J Biomech 2012; 46:31-5. [PMID: 23084783 DOI: 10.1016/j.jbiomech.2012.09.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 09/14/2012] [Accepted: 09/16/2012] [Indexed: 10/27/2022]
Abstract
Cortical bone has a hierarchical structure, spanning from the macrostructure at several millimeters or whole bone level, the microstructure at several hundred micrometers level, to the nanostructure at hydroxyapatite (HAp) crystals and collagen fibrils levels. The aim of the study is to understand the relationship between the HAp crystal orientation and the elastic modulus and the relationship between the osteon area fraction and the deformation behavior of HAp crystals in cortical bone. In the experiments, five strip specimens (40×2×1mm(3)) aligned with the bone axis were taken from the cortical bone of a bovine femur. The degree of c-axis orientation of HAp crystals in the specimens was measured with the X-ray diffraction technique with the imaging plate. To measure the deformation behavior of HAp crystals in the specimens, tensile tests under X-ray irradiation were conducted. The specimens were cut at the X-ray measurement positions and osteon area fraction and porosity at the transverse cross-sections were observed. Further, the volume fraction of HAp of the specimens was measured. Results showed the degree of c-axis orientation of HAp crystals was positively correlated with the elastic modulus of the specimens (r=0.94). The volume fraction of HAp and the porosity showed no statistical correlation with the elastic modulus and the tensile strength. The HAp crystal strain ε(H) increased linearly with the bone tissue strain ε. The average value of ε(H)/ε was 0.69±0.13 and there was no correlation between the osteon area fraction and ε(H)/ε (r=-0.27, p=0.33). The results suggest that the degree of c-axis orientation of HAp crystals affects the elastic modulus and the magnitude of HAp crystal strain does not depend on the osteon area fraction.
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Affiliation(s)
- Satoshi Yamada
- Division of Human Mechanical Systems and Design, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
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Rose DC, Agnew AM, Gocha TP, Stout SD, Field JS. Technical note: The use of geographical information systems software for the spatial analysis of bone microstructure. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 148:648-54. [PMID: 22700420 DOI: 10.1002/ajpa.22099] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 04/27/2012] [Indexed: 11/08/2022]
Abstract
Geographic information systems (GIS) software is typically used for analyzing geographically distributed data, allowing users to annotate points or areas on a map and attach data for spatial analyses. While traditional GIS-based research involves geo-referenced data (points tied to geographic locations), the use of this technology has other constructive applications for physical anthropologists. The use of GIS software for the study of bone histology offers a novel opportunity to analyze the distribution of bone nano- and microstructures, relative to macrostructure and in comparison to other variables of interest, such as biomechanical loading history. This approach allows for the examination of characteristics of single histological features while considering their role at the macroscopic level. Such research has immediate promise in examining the load history of bone by surveying the functional relationship between collagen fiber orientation (CFO) and strain mode. The diversity of GIS applications that may be utilized in bone histology research is just beginning to be explored. The goal of this study is to introduce a reliable methodology for such investigation and our objective is to quantify the heterogeneity of bone microstructure over an entire cross-section of bone using ArcGIS v 9.3 (ESRI). This was accomplished by identifying the distribution of remodeling units in a human metatarsal relative to bending axes. One biomechanical hypothesis suggests that CFO, manifested by patterns of birefringence, is indicative of mode of strain during formation. This study demonstrates that GIS can be used to investigate, describe, and compare such patterns through histological mapping.
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Affiliation(s)
- David C Rose
- Department of Anthropology, The Ohio State University, Columbus, 43210, USA.
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41
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Skedros JG, Knight AN, Farnsworth RW, Bloebaum RD. Do regional modifications in tissue mineral content and microscopic mineralization heterogeneity adapt trabecular bone tracts for habitual bending? Analysis in the context of trabecular architecture of deer calcanei. J Anat 2012; 220:242-55. [PMID: 22220639 DOI: 10.1111/j.1469-7580.2011.01470.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Calcanei of mature mule deer have the largest mineral content (percent ash) difference between their dorsal 'compression' and plantar 'tension' cortices of any bone that has been studied. The opposing trabecular tracts, which are contiguous with the cortices, might also show important mineral content differences and microscopic mineralization heterogeneity (reflecting increased hemi-osteonal renewal) that optimize mechanical behaviors in tension vs. compression. Support for these hypotheses could reveal a largely unrecognized capacity for phenotypic plasticity - the adaptability of trabecular bone material as a means for differentially enhancing mechanical properties for local strain environments produced by habitual bending. Fifteen skeletally mature and 15 immature deer calcanei were cut transversely into two segments (40% and 50% shaft length), and cores were removed to determine mineral (ash) content from 'tension' and 'compression' trabecular tracts and their adjacent cortices. Seven bones/group were analyzed for differences between tracts in: first, microscopic trabecular bone packets and mineralization heterogeneity (backscattered electron imaging, BSE); and second, trabecular architecture (micro-computed tomography). Among the eight architectural characteristics evaluated [including bone volume fraction (BVF) and structural model index (SMI)]: first, only the 'tension' tract of immature bones showed significantly greater BVF and more negative SMI (i.e. increased honeycomb morphology) than the 'compression' tract of immature bones; and second, the 'compression' tracts of both groups showed significantly greater structural order/alignment than the corresponding 'tension' tracts. Although mineralization heterogeneity differed between the tracts in only the immature group, in both groups the mineral content derived from BSE images was significantly greater (P < 0.01), and bulk mineral (ash) content tended to be greater in the 'compression' tracts (immature 3.6%, P = 0.03; mature 3.1%, P = 0.09). These differences are much less than the approximately 8% greater mineral content of their 'compression' cortices (P < 0.001). Published data, suggesting that these small mineralization differences are not mechanically important in the context of conventional tests, support the probability that architectural modifications primarily adapt the tracts for local demands. However, greater hemi-osteonal packets in the tension trabecular tract of only the mature bones (P = 0.006) might have an important role, and possible synergism with mineralization and/or microarchitecture, in differential toughening at the trabeculum level for tension vs. compression strains.
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Affiliation(s)
- John G Skedros
- Bone and Joint Research Laboratory, Veterans Affairs Medical Center, Salt Lake City, Utah 84107, USA.
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Spiesz EM, Kaminsky W, Zysset PK. A quantitative collagen fibers orientation assessment using birefringence measurements: calibration and application to human osteons. J Struct Biol 2011; 176:302-6. [PMID: 21970947 PMCID: PMC3218218 DOI: 10.1016/j.jsb.2011.09.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 09/14/2011] [Accepted: 09/20/2011] [Indexed: 12/01/2022]
Abstract
Even though mechanical properties depend strongly on the arrangement of collagen fibers in mineralized tissues, it is not yet well resolved. Only a few semi-quantitative evaluations of the fiber arrangement in bone, like spectroscopic techniques or circularly polarized light microscopy methods are available. In this study the out-of-plane collagen arrangement angle was calibrated to the linear birefringence of a longitudinally fibered mineralized turkey leg tendon cut at variety of angles to the main axis. The calibration curve was applied to human cortical bone osteons to quantify the out-of-plane collagen fibers arrangement. The proposed calibration curve is normalized to sample thickness and wavelength of the probing light to enable a universally applicable quantitative assessment. This approach may improve our understanding of the fibrillar structure of bone and its implications on mechanical properties.
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Affiliation(s)
- Ewa M Spiesz
- Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Vienna, Austria.
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Skedros JG, Sybrowsky CL, Anderson WE, Chow F. Relationships between in vivo microdamage and the remarkable regional material and strain heterogeneity of cortical bone of adult deer, elk, sheep and horse calcanei. J Anat 2011; 219:722-33. [PMID: 21951210 DOI: 10.1111/j.1469-7580.2011.01428.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Natural loading of the calcanei of deer, elk, sheep and horses produces marked regional differences in prevalent/predominant strain modes: compression in the dorsal cortex, shear in medial-lateral cortices, and tension/shear in the plantar cortex. This consistent non-uniform strain distribution is useful for investigating mechanisms that mediate the development of the remarkable regional material variations of these bones (e.g. collagen orientation, mineralization, remodeling rates and secondary osteon morphotypes, size and population density). Regional differences in strain-mode-specific microdamage prevalence and/or morphology might evoke and sustain the remodeling that produces this material heterogeneity in accordance with local strain characteristics. Adult calcanei from 11 animals of each species (deer, elk, sheep and horses) were transversely sectioned and examined using light and confocal microscopy. With light microscopy, 20 linear microcracks were identified (deer: 10; elk: six; horse: four; sheep: none), and with confocal microscopy substantially more microdamage with typically non-linear morphology was identified (deer: 45; elk: 24; horse: 15; sheep: none). No clear regional patterns of strain-mode-specific microdamage were found in the three species with microdamage. In these species, the highest overall concentrations occurred in the plantar cortex. This might reflect increased susceptibility of microdamage in habitual tension/shear. Absence of detectable microdamage in sheep calcanei may represent the (presumably) relatively greater physical activity of deer, elk and horses. Absence of differences in microdamage prevalence/morphology between dorsal, medial and lateral cortices of these bones, and the general absence of spatial patterns of strain-mode-specific microdamage, might reflect the prior emergence of non-uniform osteon-mediated adaptations that reduce deleterious concentrations of microdamage by the adult stage of bone development.
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Affiliation(s)
- John G Skedros
- Department of Orthopaedic Surgery, University of Utah and the Utah Bone and Joint Center, Salt Lake City, UT, USA.
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Abstract
BACKGROUND Advances in diagnostic and treatment regimens that aim to reduce fracture incidence will benefit from a better understanding of how bone morphology and tissue quality define whole-bone mechanical properties. QUESTIONS/PURPOSES The goal of this article was to review what is known about the interactions among morphologic and tissue quality traits and how these interactions contribute to bone quality (ie, whole-bone mechanical function). Several questions were addressed. First, how do interactions among morphology and tissue quality traits relate to functional adaptation? Second, what are the emergent patterns of functionally adapted trait sets in long bones? Third, how effective is phenotypic integration at establishing function across a population? Fourth, what are the emergent patterns of functionally adapted trait sets in corticocancellous structures? Fifth, how do functional interactions change with aging? METHODS A literature review was conducted with papers identified primarily through citations listed in reference sections as well as general searches using Google Scholar and PubMed. RESULTS The interactions among adult traits or phenotypic integration are an emergent property of the compensatory mechanisms complex systems used to establish function or homeostasis. Traits are not regulated independently but vary simultaneously (ie, covary) in specific ways to establish function. This covariation results in individuals acquiring unique sets of traits to establish bone quality. CONCLUSIONS AND CLINICAL RELEVANCE Biologic constraints imposed on the skeletal system result in a population showing a pattern of trait sets that is predictable based on external bone size and that can be used to identify individuals with reduced bone quality relative to their bone size and body size.
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Affiliation(s)
- Karl J Jepsen
- Leni and Peter W. May Department of Orthopaedics, Mount Sinai School of Medicine, Box 1188, One Gustave Levy Place, New York, NY 10029, USA.
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Shahar R, Lukas C, Papo S, Dunlop JWC, Weinkamer R. Characterization of the spatial arrangement of secondary osteons in the diaphysis of equine and canine long bones. Anat Rec (Hoboken) 2011; 294:1093-102. [PMID: 21618437 DOI: 10.1002/ar.21405] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 03/18/2011] [Indexed: 11/08/2022]
Abstract
The blood supply of bone cells in compact bone is provided primarily by blood vessels located within Haversian canals forming the centre of osteons. Mid-diaphysial cross-sections of radii and third metacarpal bones from two horses and radii from two mature dogs were studied using reflective light microscopy to quantify the spatial ordering of canals and compared to a computational model. The distributions of canals were analyzed using: 1) the autocorrelation function (ACF), which describes the probability of finding two canals separated by a given distance and 2) the shortest distance distribution (SDD), which describes the probability that a site within bone is located at a given distance from the nearest canal. The order in the investigated horse radii, as characterized by the oscillations of the ACF, was found to be independent of the anatomical location although, in the metacarpal bone the order was higher in the lateral than in the cranial location. Among the dogs, marked differences were only found in the ACF. An analysis of the SDD demonstrates that ordering of canals minimizes the distance of osteocytes from a blood vessel. This suggests that the efficiency of the blood supply can be adapted through differences in the order of the Haversian canals. In our model, the ordering of canals is achieved via an exclusion zone around each canal, imposed upon newly formed osteons. Simulations demonstrate that differences in the observed order can be explained by either a larger size or a larger variability of this exclusion zone.
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Affiliation(s)
- Ron Shahar
- Laboratory of Bone Biomechanics, Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
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46
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De Micheli P, Witzel U. Microstructural mechanical study of a transverse osteon under compressive loading: The role of fiber reinforcement and explanation of some geometrical and mechanical microscopic properties. J Biomech 2011; 44:1588-92. [DOI: 10.1016/j.jbiomech.2011.02.075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 01/30/2011] [Accepted: 02/20/2011] [Indexed: 11/27/2022]
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47
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Yamada S, Tadano S, Fujisaki K. Residual stress distribution in rabbit limb bones. J Biomech 2011; 44:1285-90. [DOI: 10.1016/j.jbiomech.2011.01.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 01/29/2011] [Accepted: 01/31/2011] [Indexed: 10/18/2022]
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Skedros JG, Kiser CJ, Keenan KE, Thomas SC. Analysis of osteon morphotype scoring schemes for interpreting load history: evaluation in the chimpanzee femur. J Anat 2011; 218:480-99. [PMID: 21323667 DOI: 10.1111/j.1469-7580.2011.01348.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Osteon morphotype scores (MTSs) allow for quantification of mechanically important collagen/lamellar variations between secondary osteons when viewed in circularly polarized ight (CPL). We recently modified the 6-point MTS method of Martin et al. (Martin RB, Gibson VA, Stover SM, Gibeling JC, Griffin LV (1996a) Osteonal structure in the equine third metacarpus. Bone 19, 165-71) and reported superiority of this modified method in correlating with 'tension' and 'compression' cortices of both chimpanzee proximal femoral diaphyses and diaphyses of other non-anthropoid bones that are loaded in habitual bending (Skedros et al. 2009, 2011). In these studies, the 'tension' and 'compression' cortices differed significantly in predominant collagen fiber orientation (CFO) based on weighted-mean gray levels (CFO/WMGLs) in CPL images. In chimpanzee femora, however, some osteons were difficult to score with the 6-point method; namely, 'hybrids' with peripherally bright 'hoops' and variability in alternating rings within the osteon wall. We hypothesized that some of these hybrids would be more prevalent in regions subject to torsion than bending. In this perspective the present study was aimed at expanding our 6-point scoring method (S-6-MTS) into two 12-point methods with six additional morphotypes that considered these hybrids. Three- and 4-point methods were also evaluated. We hypothesized that at least one of these other methods would out-perform the S-6-MTS in terms of accuracy, reliability, and interpreting torsion vs. bending load histories. Osteon morphotypes were quantified in CPL images from transverse sections of eight adult chimpanzee femora (neck, proximal diaphysis, mid-diaphysis), where the mid-diaphysis and base- and mid-neck locations have relatively more complex loading (e.g. torsion + bending) than the proximal diaphysis, where bending predominates. Correlation coefficients between CFO/WMGL and MTSs showed that the S-6-MTS method was either stronger or equivalent to the 12-point methods, and typically stronger than the 3- and 4-point methods for all load environments. In nearly all instances the S-6-MTS is more reliable and accurate when it is applied to cases where interpreting load history requires distinguishing habitual bending from torsion. Consequently, in studies of osteonal adaptations for these load histories the 3- and 4-point methods are not stronger correlates, and the extra time required to assign additional scores in the 12-point methods is both unnecessary and can be highly unreliable.
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Affiliation(s)
- John G Skedros
- Bone and Joint Research Laboratory, Department of Veterans Affairs Medical Center, The University of Utah, Salt Lake City, UT, USA.
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Skedros JG, Kiser CJ, Mendenhall SD. A weighted osteon morphotype score outperforms regional osteon percent prevalence calculations for interpreting cortical bone adaptation. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2010; 144:41-50. [DOI: 10.1002/ajpa.21365] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 05/24/2010] [Indexed: 11/08/2022]
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50
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Middleton KM, Goldstein BD, Guduru PR, Waters JF, Kelly SA, Swartz SM, Garland T. Variation in within-bone stiffness measured by nanoindentation in mice bred for high levels of voluntary wheel running. J Anat 2010; 216:121-31. [PMID: 20402827 PMCID: PMC2807980 DOI: 10.1111/j.1469-7580.2009.01175.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2009] [Indexed: 12/17/2022] Open
Abstract
The hierarchical structure of bone, involving micro-scale organization and interaction of material components, is a critical determinant of macro-scale mechanics. Changes in whole-bone morphology in response to the actions of individual genes, physiological loading during life, or evolutionary processes, may be accompanied by alterations in underlying mineralization or architecture. Here, we used nanoindentation to precisely measure compressive stiffness in the femoral mid-diaphysis of mice that had experienced 37 generations of selective breeding for high levels of voluntary wheel running (HR). Mice (n = 48 total), half from HR lines and half from non-selected control (C) lines, were divided into two experimental groups, one with 13-14 weeks of access to a running wheel and one housed without wheels (n = 12 in each group). At the end of the experiment, gross and micro-computed tomography (microCT)-based morphometric traits were measured, and reduced elastic modulus (E(r)) was estimated separately for four anatomical quadrants of the femoral cortex: anterior, posterior, lateral, and medial. Two-way, mixed-model analysis of covariance (ancova) showed that body mass was a highly significant predictor of all morphometric traits and that structural change is more apparent at the microCT level than in conventional morphometrics of whole bones. Both line type (HR vs. C) and presence of the mini-muscle phenotype (caused by a Mendelian recessive allele and characterized by a approximately 50% reduction in mass of the gastrocnemius muscle complex) were significant predictors of femoral cortical cross-sectional anatomy. Measurement of reduced modulus obtained by nanoindentation was repeatable within a single quadrant and sensitive enough to detect inter-individual differences. Although we found no significant effects of line type (HR vs. C) or physical activity (wheel vs. no wheel) on mean stiffness, anterior and posterior quadrants were significantly stiffer (P < 0.0001) than medial and lateral quadrants (32.67 and 33.09 GPa vs. 29.78 and 30.46 GPa, respectively). Our findings of no significant difference in compressive stiffness in the anterior and posterior quadrants agree with previous results for mice, but differ from those for large mammals. Integrating these results with others from ongoing research on these mice, we hypothesize that the skeletons of female HR mice may be less sensitive to the effects of chronic exercise, due to decreased circulating leptin levels and potentially altered endocannabinoid signaling.
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Affiliation(s)
- Kevin M Middleton
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA.
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