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Wojciechowska-Puchałka J, Calik J, Krawczyk J, Obrzut J, Tomaszewska E, Muszyński S, Wojtysiak D. The effect of caponization on bone homeostasis of crossbred roosters. I. Analysis of tibia bone mineralization, densitometric, osteometric, geometric and biomechanical properties. Sci Rep 2023; 13:14512. [PMID: 37667027 PMCID: PMC10477200 DOI: 10.1038/s41598-023-41806-x] [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: 05/30/2023] [Accepted: 08/31/2023] [Indexed: 09/06/2023] Open
Abstract
The presented study focuses on assessing the effect of caponization on the densitometric, osteometric, geometric and biomechanical parameters of tibial bones in crossbred chickens. The study was carried out on 96 hybrids between Yellowleg Partridge hens (Ż-33) and Rhode Island Red cockerels (R-11) aged 16 weeks, 20 weeks and 24 weeks. Birds were randomly assigned to 2 groups-the control group (n = 48; which consisted of intact roosters) and the experimental group (n = 48, which consisted of individuals subjected to caponization at the age of 8 weeks). The caponization had no effect on the densitometric, osteometric and geometric parameters (except the horizontal internal diameter of 16-week-old individuals) of tibia bone, as well as the content of calcium (Ca), phosphorus (P) and the Ca/P ratio in the bone mineral fraction in all analyzed age groups of animals. However, it contributes to a lower percentage of ash in the bones of capons at 20 and 24 weeks of age compared to cockerels. On the contrary, some mechanical and material parameters show the negative effect of caponization. Ultimate load and bending moment decreased in capons in all of the analyzed age groups of animals and yield load, stiffness and ultimate stress also decreased but only in the group of 20-week-old and 24-week-old individuals. This can contribute to the weakening of the capon bones, and in the perspective of prolonged maintenance to their deformation and even fracture.
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Affiliation(s)
- J Wojciechowska-Puchałka
- Department of Animal Reproduction, Anatomy and Genomics, University of Agriculture in Kraków, 24/28 Mickiewicza Ave., 30-059, Cracow, Poland.
| | - J Calik
- Department of Poultry Breeding, National Research Institute of Animal Production, 32-083, Balice, Poland
| | - J Krawczyk
- Department of Poultry Breeding, National Research Institute of Animal Production, 32-083, Balice, Poland
| | - J Obrzut
- Department of Poultry Breeding, National Research Institute of Animal Production, 32-083, Balice, Poland
| | - E Tomaszewska
- Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 12 Akademicka St., 20-950, Lublin, Poland
| | - S Muszyński
- Department of Biophysics, Faculty of Environmental Biology, University of Life Sciences in Lublin, 13 Akademicka St., 20-950, Lublin, Poland
| | - D Wojtysiak
- Department of Animal Genetics, Breeding and Ethology, Faculty of Animal Sciences, University of Agriculture in Kraków, 24/28 Mickiewicza Ave., 30-059, Cracow, Poland
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2
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Flaherty T, Rando C, Watts R. Dehydration-Induced alterations to sharp force trauma on Sus domesticus radii. Sci Justice 2023; 63:63-73. [PMID: 36631183 DOI: 10.1016/j.scijus.2022.11.007] [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: 08/29/2022] [Revised: 11/02/2022] [Accepted: 11/21/2022] [Indexed: 11/26/2022]
Abstract
Dehydration is a taphonomic process that affects nearly all skeletal remains, yet there is a dearth of evidence on this process within the forensic taphonomy literature. When considering the forensic implications of skeletal dehydration, a particular area of concern is sharp force trauma due to its global prominence in forensic cases. In an attempt to address these literature gaps and quantify the effects that dehydration has on skeletal elements, a controlled experiment subjected Sus domesticus (i.e., domestic pig) radii samples (n = 36) to laboratory-induced dehydration after they were inflicted with knife trauma. All samples were photographed pre- and post-dehydration; bone section and kerf mark length, width, and area were then measured from these photographs using ImageJ. Statistical analysis of pre- and post-dehydration samples showed that all measurements experienced significant (p ≤ 0.001) shrinkage, with bone sample area shrinking an average of 8.8 % and kerf mark area an average of 29.7 %. Alterations in length, width and area between the kerf marks and bone samples showed a weak, moderate, and strong correlation, respectively. These findings suggest that anthropological analysis may be affected by dehydration-induced shrinkage, highlighting the necessity of continued research into the effects of dehydration on skeletal trauma.
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Affiliation(s)
- Taylor Flaherty
- Department of Anthropology University of Nevada, Las Vegas, United States.
| | - Carolyn Rando
- Institute of Archaeology University College London, United Kingdom
| | - Rebecca Watts
- Institute of Archaeology University College London, United Kingdom
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3
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Wang JY, Mansfield JC, Brasselet S, Vergari C, Meakin JR, Winlove CP. Micro-mechanical damage of needle puncture on bovine annulus fibrosus fibrils studied using polarization-resolved Second Harmonic Generation(P-SHG) microscopy. J Mech Behav Biomed Mater 2021; 118:104458. [PMID: 33761373 DOI: 10.1016/j.jmbbm.2021.104458] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 02/28/2021] [Accepted: 03/10/2021] [Indexed: 11/24/2022]
Abstract
Needle injection has been widely used in spinal therapeutic or diagnostic processes, such as discography. The use of needles has been suspected in causing mild disc degeneration which can lead to long-term back pain. However, the localised microscopic damage caused by needles has not been well studied. The local progressive damage on a microscopic level caused by needle punctures on the surface of bovine annulus fibrosus was investigated. Four different sizes of needle were used for the puncture and twenty-nine bovine intervertebral discs were studied. Polarization-resolved second harmonic generation and fluorescent microscopy were used to study the local microscopic structural changes in collagen and cell nuclei due to needle damage. Repeated 70 cyclic loadings at ±5% of axial strain were applied after the needle puncture in order to assess progressive damage caused by the needle. Puncture damage on annulus fibrosus were observed either collagen fibre bundles being pushed aside, being cut through or combination of both with part being lift or pushed in. The progressive damage was found less relevant to the needle size and more progressive damage was only observed using the larger needle. Two distinct populations of collagen, in which one was relatively more organised than the other population, were observed especially after the puncture from skewed distribution of polarization-SHG analysis. Cell shape was found rounder near the puncture site where collagen fibres were damaged.
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Affiliation(s)
- J-Y Wang
- College of Engineering, Mathematics & Physical Sciences, Physics Building, Stocker Road, Exeter, EX4 4QL, UK.
| | - J C Mansfield
- College of Engineering, Mathematics & Physical Sciences, Physics Building, Stocker Road, Exeter, EX4 4QL, UK
| | - S Brasselet
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France
| | - C Vergari
- Arts et Métiers Institute of Technology, Université Sorbonne Paris Nord, IBHGC - Institut de Biomécanique Humaine Georges Charpak, HESAM Université, F-75013, Paris
| | - J R Meakin
- College of Engineering, Mathematics & Physical Sciences, Physics Building, Stocker Road, Exeter, EX4 4QL, UK
| | - C P Winlove
- College of Engineering, Mathematics & Physical Sciences, Physics Building, Stocker Road, Exeter, EX4 4QL, UK
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4
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Xie S, Wallace RJ, Pankaj P. Time-dependent behaviour of demineralised trabecular bone - Experimental investigation and development of a constitutive model. J Mech Behav Biomed Mater 2020; 109:103751. [PMID: 32347212 DOI: 10.1016/j.jmbbm.2020.103751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 03/20/2020] [Accepted: 03/23/2020] [Indexed: 11/16/2022]
Abstract
Trabecular bone is a cellular composite material comprising primarily of mineral and organic phases and its mechanical response to loads is time-dependent. The contribution of the organic phase to the time-dependent behaviour of bone is not yet understood. We investigated the time-dependent response of demineralised trabecular bone through tensile multiple-load-creep-unload-recovery experiments. We found that demineralised trabecular bone's time-dependent response is nonlinearly related to the applied stress levels - it stiffens with increased stress levels. Our results also indicated that the time-dependent behaviour is associated with the original bone volume ratio (BV/TV). Irrecoverable strain exists, even at the low strain levels, but are not associated with BV/TV. Furthermore, we found that the nonlinear viscoelastic model can accurately predict the time-dependent behaviour of the trabecular bone's organic phase, which can be incorporated together with the properties of mineral to generate a composite model of bone. This study will help to provide a better understanding of this natural composite material.
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Affiliation(s)
- Shuqiao Xie
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Alrick Building, The King's Buildings, Edinburgh, EH9 3BF, UK
| | - Robert J Wallace
- Department of Orthopaedics, The University of Edinburgh, Chancellor's Building, Edinburgh, EH16 4SB, UK
| | - Pankaj Pankaj
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Alrick Building, The King's Buildings, Edinburgh, EH9 3BF, UK.
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Xie S, Wallace RJ, Callanan A, Pankaj P. From Tension to Compression: Asymmetric Mechanical Behaviour of Trabecular Bone's Organic Phase. Ann Biomed Eng 2018; 46:801-809. [PMID: 29589168 PMCID: PMC5934460 DOI: 10.1007/s10439-018-2009-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 03/15/2018] [Indexed: 11/26/2022]
Abstract
Trabecular bone is a cellular composite material comprising primarily of mineral and organic phases with their content ratio known to change with age. Therefore, the contribution of bone constituents on bone's mechanical behaviour, in tension and compression, at varying load levels and with changing porosity (which increases with age) is of great interest, but remains unknown. We investigated the mechanical response of demineralised bone by subjecting a set of bone samples to fully reversed cyclic tension-compression loads with varying magnitudes. We show that the tension to compression response of the organic phase of trabecular bone is asymmetric; it stiffens in tension and undergoes stiffness reduction in compression. Our results indicate that demineralised trabecular bone struts experience inelastic buckling under compression which causes irreversible damage, while irreversible strains due to microcracking are less visible in tension. We also identified that the values of this asymmetric mechanical response is associated to the original bone volume ratio (BV/TV).
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Affiliation(s)
- Shuqiao Xie
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Faraday Building, The King's Buildings, Edinburgh, EH9 3DW, UK
| | - Robert J Wallace
- Orthopaedics and Trauma, The University of Edinburgh, Chancellor's Building, Edinburgh, EH16 4SB, UK
| | - Anthony Callanan
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Faraday Building, The King's Buildings, Edinburgh, EH9 3DW, UK
| | - Pankaj Pankaj
- School of Engineering, Institute for Bioengineering, The University of Edinburgh, Faraday Building, The King's Buildings, Edinburgh, EH9 3DW, UK.
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Tomaszewska E, Kwiecień M, Dobrowolski P, Klebaniuk R, Muszyński S, Olcha M, Blicharski T, Grela ER. Dose-dependent effects of probiotic supplementation on bone characteristics and mineralisation in meat-type female turkeys. ANIMAL PRODUCTION SCIENCE 2018. [DOI: 10.1071/an16289] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To evaluate the influence of the probiotic on bone tissue in female turkeys, bone mineral density and geometrical and mechanical properties of the tibia and femur were determined in a dose-dependent manner (107 colony-forming units (cfu)/g, 108 cfu/g, 109 cfu/g). No effect of the treatments on bone mass and wall thickness of femur was observed, but the administration of the probiotic resulted in the elongation and the reduction of both strengths. The increase in the cross-sectional area of the femur was dose-dependent. Probiotic supplementation at a concentration of 108 cfu/g resulted in a reduction in ultimate strength, but at a concentration of 107 cfu/g, it resulted in the enhancement of the maximum elastic strength of the tibia compared with other groups. The influence of the probiotic administration on tibia geometry was dose-dependent. No effect of the treatments on the relative bone weight and the ratio of mass to length was observed. In general, the influence of the probiotic administration on bone mineral density, bone mineral concentration, bone tissue density, and bone ash, calcium and phosphorus concentrations was dose-dependent. The investigated properties of long bones in female turkeys are affected through probiotic-supplemented diets in a dose-dependent manner. However, on the basis of densitometry, it seems that the administration of the probiotic at a higher concentration of cells is more beneficial for bone development in turkeys.
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Tomaszewska E, Kwiecień M, Muszyński S, Dobrowolski P, Kasperek K, Blicharski T, Jeżewska-Witkowska G, Grela ER. Long-bone properties and development are affected by caponisation and breed in Polish fowls. Br Poult Sci 2017; 58:312-318. [PMID: 28102084 DOI: 10.1080/00071668.2017.1280770] [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] [Indexed: 10/20/2022]
Abstract
1. The aim of the study was to investigate the effects of caponisation on bone development of males of two native breeds in Poland. 2. The weight, length and cross-sectional area of tibiae and femora were measured, densitometric measurements and tests of strength were determined and dimensions were calculated. 3. Breed and caponisation did not influence bone weight and length. Higher mechanical strength of the femur was found in entire males, mainly in the Polbar breed. Tibial strength was reduced in capons of the Green Partridge breed. Maximum elastic strength was greater in the Polbar, irrespective of caponisation. Bone cross-sectional area was influenced by breed, while caponisation reduced femoral bone mineral density in both breeds. 4. Caponisation thus increased growth rate but had adverse effects on bone development. 5. Caponisation had fewer negative effects in the Polbar than in the Greenleg Partridge.
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Affiliation(s)
- E Tomaszewska
- a Department of Animal Physiology, Faculty of Veterinary Medicine , University of Life Sciences in Lublin , Lublin , Poland
| | - M Kwiecień
- b Institute of Animal Nutrition and Bromatology, Faculty of Biology, Animal Science and Bioeconomy , University of Life Sciences in Lublin , Lublin , Poland
| | - S Muszyński
- c Department of Physics, Faculty of Production Engineering , University of Life Sciences in Lublin , Lublin , Poland
| | - P Dobrowolski
- d Department of Comparative Anatomy and Anthropology, Faculty of Biology and Biotechnology , Maria Curie-Skłodowska University , Lublin , Poland
| | - K Kasperek
- e Department of Biological Basis of Animal Production, Faculty of Biology, Animal Science and Bioeconomy , University of Life Sciences in Lublin , Lublin , Poland
| | - T Blicharski
- f Department of Rehabilitation and Orthopaedics , Medical University in Lublin , Lublin , Poland
| | - G Jeżewska-Witkowska
- e Department of Biological Basis of Animal Production, Faculty of Biology, Animal Science and Bioeconomy , University of Life Sciences in Lublin , Lublin , Poland
| | - E R Grela
- b Institute of Animal Nutrition and Bromatology, Faculty of Biology, Animal Science and Bioeconomy , University of Life Sciences in Lublin , Lublin , Poland
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Tomaszewska E, Muszyński S, Dobrowolski P, Kostro K, Taszkun I, Żmuda A, Blicharski T, Kędzia P. Bentonite diminishes DON-induced changes in bone development in mink dams. J Vet Res 2016. [DOI: 10.1515/jvetres-2016-0033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Introduction: The aim of this study was to determine the effect of deoxynivalenol (DON), given alone or with bentonite (which eliminates mycotoxicity) in the diet of mink dams throughout mating, pregnancy, and lactation period to pelt harvesting, on the mechanical properties and geometry of their long bones.
Material and Methods: The minks were randomly assigned into two groups: a control group (not supplemented with DON, n = 15) and a group fed naturally DON-contaminated wheat and divided into three sub-groups (each sub-group n = 15), depending on bentonite dose: 0 M – sub-group fed naturally DON-contaminated wheat at a concentration of 3.7 mg kg−1 alone; 2 M – sub-group fed naturally DON-contaminated wheat at a concentration of 3.7 mg kg−1 and bentonite at a concentration of 2 kg 1000 kg−1; 0.5 M – sub-group fed naturally DON-contaminated wheat at a concentration of 3.7 mg kg−1 and bentonite at a concentration of 0.5 kg 1000 kg−1.
Results: The DON treatment reduced the length of the femur compared to the control group and reduced the bone weight dependently on the amount of bentonite supplementation. However, DON treatment reduced the MRWT and CI of the femur, irrespective of the bentonite supplementation, compared to the control. The total BTD and BMC decreased in all DON-treated groups (irrespective of the bentonite supplementation). Furthermore, the densitometric analysis showed that the main changes in BMD and BMC indicated bone loss in the proximal and distal parts of bone covering the trabecular bone; whereas when bentonite was given at the dose of 2 kg 1000 kg−1 an increase in the whole BMD and BMC was observed in the femoral midshaft.
Conclusion: Analysis of the geometrical parameters seems to indicate that endosteal resorption was delayed after bentonite supplementation. The addition of bentonite diminished the DON action on bone homeostasis in the mink dams. Thus bentonite could prevent DON-induced bone loss in a dose-dependent manner.
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Affiliation(s)
- Ewa Tomaszewska
- Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences, 20-950 Lublin, Poland
| | - Siemowit Muszyński
- Department of Physics, Faculty of Production Engineering, University of Life Sciences, 20-950 Lublin, Poland
| | - Piotr Dobrowolski
- Department of Comparative Anatomy and Anthropology, Maria Curie-Skłodowska University, 20-950 Lublin, Poland
| | - Krzysztof Kostro
- Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences, 20-950 Lublin, Poland
| | - Iwona Taszkun
- Sub-department of Clinical Diagnostics and Veterinary Dermatology, Department and Clinic of Internal Medicine, Faculty of Veterinary Medicine, University of Life Sciences, 20-950 Lublin, Poland
| | - Andrzej Żmuda
- Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences, 20-950 Lublin, Poland
| | - Tomasz Blicharski
- Chair and Department of Rehabilitation and Orthopaedics, Medical University in Lublin, 20-090 Lublin, Poland
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Experimental study of diffusion coefficients of water through the collagen: apatite porosity in human trabecular bone tissue. BIOMED RESEARCH INTERNATIONAL 2014; 2014:796519. [PMID: 24967405 PMCID: PMC4055463 DOI: 10.1155/2014/796519] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/16/2014] [Accepted: 04/28/2014] [Indexed: 11/21/2022]
Abstract
We firstly measured the swelling of single trabeculae from human femur heads during water imbibition. Since the swelling is caused by water diffusing from external surfaces to the core of the sample, by measuring the sample swelling over time, we obtained direct information about the transport of fluids through the intimate constituents of bone, where the mineralization process takes place. We developed an apparatus to measure the free expansion of the tissue during the imbibition. In particular, we measured the swelling along three natural axes (length L, width W, and thickness T) of plate-like trabeculae. For this aim, we developed a 3D analytical model of the water uptake by the sample that was performed according to Fickian transport mechanism. The results were then utilized to predict the swelling over time along the three sample directions (L, W, T) and the apparent diffusion coefficients DT, DW, and DL.
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10
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Marinozzi F, Bini F, Marinozzi A. Water uptake and swelling in single trabeculæ from human femur head. BIOMATTER 2014; 4:e28237. [PMID: 24553097 PMCID: PMC4091056 DOI: 10.4161/biom.28237] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The swelling of air-dried single trabeculae from human femur heads was obtained by complete immersion in water and the dimensional changes of the samples were measured over time. The experimental results were analyzed under the viewpoint of the diffusion through a porous material. The dimensional changes of the single trabeculae were 0.26 ± 0.15 percent (length), 0.45 ± 0.25 percent (width) and 1.86 ± 0.97 percent (thickness). The diffusion coefficients were then calculated from the swelling recorded over time and a value of (4.12 ± 0.8) x 10−10(m2s−1) (mean ± standard deviation) was found.
Since the dimensional variations of the specimens is due to the swelling of the collagen bone matrix, this technique could offer new insights for (1) a selective characterization of bone microstructure at the collagen matrix level and (2) the dynamics of diffusion through bone tissue.
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Affiliation(s)
- Franco Marinozzi
- Mechanical and Thermal Measurements Laboratory; Department of Mechanical and Aerospace Engineering; Sapienza University of Rome; Rome, Italy
| | - Fabiano Bini
- Mechanical and Thermal Measurements Laboratory; Department of Mechanical and Aerospace Engineering; Sapienza University of Rome; Rome, Italy
| | - Andrea Marinozzi
- Orthopedy and Traumatology Area; Campus Bio-Medico University; Rome, Italy
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11
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Lievers W, Poljsak A, Waldman S, Pilkey A. Effects of dehydration-induced structural and material changes on the apparent modulus of cancellous bone. Med Eng Phys 2010; 32:921-5. [DOI: 10.1016/j.medengphy.2010.06.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 04/26/2010] [Accepted: 06/02/2010] [Indexed: 11/26/2022]
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12
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Lievers WB, Petryshyn AC, Poljsak AS, Waldman SD, Pilkey AK. Specimen diameter and "side artifacts" in cancellous bone evaluated using end-constrained elastic tension. Bone 2010; 47:371-7. [PMID: 20380901 DOI: 10.1016/j.bone.2010.03.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 03/25/2010] [Accepted: 03/29/2010] [Indexed: 11/28/2022]
Abstract
In cancellous bone testing of cored samples, side artifacts are the underestimation of the true (i.e. in situ) mechanical properties due to the severing of the trabecular network during specimen preparation. Although other researchers have suggested correction factors derived from finite element method (FEM) models, it is proposed that side effects can be minimized by increasing the specimen diameter. Six different diameter specimens (3.1-10.6 mm), from two different anatomic sites (bovine femoral condyle and bovine lumbar vertebrae), were mechanically tested in elastic tension using an epoxy endcap protocol to eliminate end artifacts. Elastic modulus was found to be significantly affected by diameter in both sites. For example, the 5.1 mm samples underestimated the elastic modulus of the 10.6 mm samples by an average of roughly 20%. Yet no statistical difference was detected between the 8.3 and 10.6 mm samples in either anatomic site, suggesting that 8.3 mm diameter specimens were sufficiently large to avoid side artifacts. FEM models created from micro-CT images reveal that modulus approaches an asymptotic value with increasing diameter, and demonstrate an architecture-dependent drop in modulus at decreasing diameters. These results confirm, both experimentally and numerically, that side effects can be ignored given a suitably large specimen diameter and that this minimum diameter will be dependent on the cancellous architecture. An important implication of the latter result is that specimen diameters must be chosen appropriately when comparing test groups with different architectures (e.g. normal versus osteoporotic) to ensure that the magnitude of side artifacts does not confound the true differences between the groups.
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Affiliation(s)
- W B Lievers
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada K7L 3N6
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13
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Abstract
The skeletons of birds are universally described as lightweight as a result of selection for minimizing the energy required for flight. From a functional perspective, the weight (mass) of an animal relative to its lift-generating surfaces is a key determinant of the metabolic cost of flight. The evolution of birds has been characterized by many weight-saving adaptations that are reflected in bone shape, many of which strengthen and stiffen the skeleton. Although largely unstudied in birds, the material properties of bone tissue can also contribute to bone strength and stiffness. In this study, I calculated the density of the cranium, humerus and femur in passerine birds, rodents and bats by measuring bone mass and volume using helium displacement. I found that, on average, these bones are densest in birds, followed closely by bats. As bone density increases, so do bone stiffness and strength. Both of these optimization criteria are used in the design of strong and stiff, but lightweight, manmade airframes. By analogy, increased bone density in birds and bats may reflect adaptations for maximizing bone strength and stiffness while minimizing bone mass and volume. These data suggest that both bone shape and the material properties of bone tissue have played important roles in the evolution of flight. They also reconcile the conundrum of how bird skeletons can appear to be thin and delicate, yet contribute just as much to total body mass as do the skeletons of terrestrial mammals.
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Affiliation(s)
- Elizabeth R Dumont
- Department of Biology, University of Massachusetts at Amherst, 221 Morrill Science Center, Amherst, MA 01003, USA.
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