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de Souza AF, Pereira CAM, Fürst A, Kümmerle JM, De Zoppa ALDV. Does the proximal screw type affect stress and strain in pastern arthrodesis with locking plate in horses? Res Vet Sci 2024; 178:105378. [PMID: 39137606 DOI: 10.1016/j.rvsc.2024.105378] [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: 03/29/2024] [Revised: 07/08/2024] [Accepted: 08/07/2024] [Indexed: 08/15/2024]
Abstract
The implantation of unicortical cortex screws in the proximal hole of locking compression plates (LCP) has been recommended for proximal interphalangeal (PIP) arthrodesis in horses to prevent fractures resulting from stress risers in the proximal phalanx (P1). However, this cortex screw fixation technique may limit efficient dorsal compression of the PIP joint by the plate, potentially affecting the stability of the construct. In this study, we aimed to measure stress and strain in P1 and the plate using an ex vivo model of PIP arthrodesis in horses. We employed various implantation methods and proximal screw types in conjunction with two 5.5 mm transarticular cortex screws. Ten pairs of equine forelimbs were divided into four groups based on proximal screw placement: GUC (unicortically placed cortex screw), GBC (bicortically placed cortex screw), GUL (unicortically placed locking screw), and GBL (bicortically placed locking screw). We calculated the magnitude and direction of strain, strain ratio, and stress using strain gauges during an axial compression mechanical testing. The palmar surface of P1 exhibited higher stress and strains than the dorsal surface, with the plate part located at the articular level suffered more stress than the proximal part. Both the implantation method and proximal screw type significantly influenced the analyzed parameters. The GUC promoted greater changes in strain direction in the proximal portion of the P1. Bicortical placement of a cortex screw appears to be the most suitable option for filling the proximal hole of the LCP, because it allows effective dynamic compression via the plate and prevents abrupt shifts in the direction of the forces acting on the proximal part of P1 during loading.
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Affiliation(s)
- Anderson Fernando de Souza
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.
| | | | - Anton Fürst
- Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | | | - André Luis do Valle De Zoppa
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
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Byron C, Reed D, Iriarte-Diaz J, Wang Q, Strait D, Laird MF, Ross CF. Sagittal suture strain in capuchin monkeys (Sapajus and Cebus) during feeding. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 180:633-654. [PMID: 36790169 DOI: 10.1002/ajpa.24701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 12/13/2022] [Accepted: 01/16/2023] [Indexed: 05/26/2023]
Abstract
OBJECTIVES Morphological variation in cranial sutures is used to infer aspects of primate feeding behavior, including diet, but strain regimes across sutures are not well documented. Our aim is to test hypotheses about sagittal suture morphology, strain regime, feeding behavior, and muscle activity relationships in robust Sapajus and gracile Cebus capuchin primates. MATERIALS AND METHODS Morphometrics of sinuosity in three regions of the sagittal suture were compared among museum specimens of Sapajus and Cebus, as well as in robust and gracile lab specimens. In vivo strains and bilateral electromyographic (EMG) activity were recorded from these regions in the temporalis muscles of capuchin primates while they fed on mechanically-varying foods. RESULTS Sapajus and the anterior suture region exhibited greater sinuosity than Cebus and posterior regions. In vivo data reveal minor differences in strain regime between robust and gracile phenotypes but show higher strain magnitudes in the middle suture region and higher tensile strains anteriorly. After gage location, feeding behavior has the most consistent and strongest impact on strain regime in the sagittal suture. Strain in the anterior suture has a high tension to compression ratio compared to the posterior region, especially during forceful biting in the robust Sapajus-like individual. DISCUSSION Sagittal suture complexity in robust capuchins likely reflects feeding behaviors associated with mechanically challenging foods. Sutural strain regimes in other anthropoid primates may also be affected by activity in feeding muscles.
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Affiliation(s)
- Craig Byron
- Department of Biology, Mercer University, Macon, Georgia, USA
| | - David Reed
- Department of Oral Biology, University of Illinois, Chicago, Illinois, USA
| | - Jose Iriarte-Diaz
- Department of Biology, University of the South, Sewanee, Tennessee, USA
| | - Qian Wang
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - David Strait
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
- Palaeo-Research Institute, University of Johannesburg, Johannesburg, South Africa
| | - Myra F Laird
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA
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Sharp AC, Dutel H, Watson PJ, Gröning F, Crumpton N, Fagan MJ, Evans SE. Assessment of the mechanical role of cranial sutures in the mammalian skull: Computational biomechanical modelling of the rat skull. J Morphol 2023; 284:e21555. [PMID: 36630615 PMCID: PMC10107956 DOI: 10.1002/jmor.21555] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 01/13/2023]
Abstract
Cranial sutures are fibrocellular joints between the skull bones that are progressively replaced with bone throughout ontogeny, facilitating growth and cranial shape change. This transition from soft tissue to bone is reflected in the biomechanical properties of the craniofacial complex. However, the mechanical significance of cranial sutures has only been explored at a few localised areas within the mammalian skull, and as such our understanding of suture function in overall skull biomechanics is still limited. Here, we sought to determine how the overall strain environment is affected by the complex network of cranial sutures in the mammal skull. We combined two computational biomechanical methods, multibody dynamics analysis and finite element analysis, to simulate biting in a rat skull and compared models with and without cranial sutures. Our results show that including complex sutures in the rat model does not substantially change overall strain gradients across the cranium, particularly strain magnitudes in the bones overlying the brain. However, local variations in strain magnitudes and patterns can be observed in areas close to the sutures. These results show that, during feeding, sutures may be more important in some regions than others. Sutures should therefore be included in models that require accurate local strain magnitudes and patterns of cranial strain, particularly if models are developed for analysis of specific regions, such as the temporomandibular joint or zygomatic arch. Our results suggest that, for mammalian skulls, cranial sutures might be more important for allowing brain expansion during growth than redistributing biting loads across the cranium in adults.
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Affiliation(s)
- Alana C Sharp
- Department of Musculoskeletal and Ageing Sciences, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK.,Department of Cell and Developmental Biology, University College London, London, UK
| | - Hugo Dutel
- Department of Engineering, University of Hull, Hull, UK.,Faculty of Science, School of Earth Sciences, University of Bristol, Bristol, UK
| | | | - Flora Gröning
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Nick Crumpton
- Department of Cell and Developmental Biology, University College London, London, UK
| | | | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, London, UK
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Marcé-Nogué J. One step further in biomechanical models in palaeontology: a nonlinear finite element analysis review. PeerJ 2022; 10:e13890. [PMID: 35966920 PMCID: PMC9373974 DOI: 10.7717/peerj.13890] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 07/21/2022] [Indexed: 01/19/2023] Open
Abstract
Finite element analysis (FEA) is no longer a new technique in the fields of palaeontology, anthropology, and evolutionary biology. It is nowadays a well-established technique within the virtual functional-morphology toolkit. However, almost all the works published in these fields have only applied the most basic FEA tools i.e., linear materials in static structural problems. Linear and static approximations are commonly used because they are computationally less expensive, and the error associated with these assumptions can be accepted. Nonetheless, nonlinearities are natural to be used in biomechanical models especially when modelling soft tissues, establish contacts between separated bones or the inclusion of buckling results. The aim of this review is to, firstly, highlight the usefulness of non-linearities and secondly, showcase these FEA tool to researchers that work in functional morphology and biomechanics, as non-linearities can improve their FEA models by widening the possible applications and topics that currently are not used in palaeontology and anthropology.
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Affiliation(s)
- Jordi Marcé-Nogué
- Department of Mechanical Engineering, Universitat Rovira i Virgili Tarragona, Tarragona, Catalonia, Spain
- Institut Català de Paleontologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Catalonia, Spain
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Singer E, Garcia T, Stover S. How does bone strain vary between the third metacarpal and the proximal phalangeal bones of the equine distal limb? J Biomech 2021; 123:110455. [PMID: 34004392 DOI: 10.1016/j.jbiomech.2021.110455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 04/02/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Strain parameters at injury prone sites of the equine third metacarpal (MC3) and proximal phalangeal (P1) bones were investigated with the aim of improving understanding of injury pathogenesis. We hypothesized that dorsal principal and shear strain patterns, magnitudes and directions would differ from proximal-to-distal; and would be similar from medial-to-lateral across each bone. Unilateral limbs from nine equine cadavers were instrumented with rosette strain gauges during limb loading to 10,500 N. Gauges were attached at seven dorsal sites: middle MC3, distal MC3 (medial, middle, lateral) and proximal P1 (medial, middle, lateral). Outcome measures were analysed with repeated measures analysis of variance. Distal MC3 had the greatest, and proximal P1 the smallest magnitude of minimum principal and shear strains. Directions of maximum and minimum principal strain were similar at the middle and distal MC3 sites with a 20-40° direction difference compared to proximal P1. The patterns of strain magnitude and direction were similar from medial-to-lateral on distal MC3 but varied in pattern and magnitude among the P1 sites. Overall, as load reached maximum, direction of minimum principal strain became more axial in orientation, converging from opposite directions between bones, potentially maximising stability of the distal limb. The difference in strain parameters and strain ratio for adjacent anatomic sites on distal MC3 and proximal P1 was not anticipated, in light of the anatomic congruity of the metacarpophalangeal joint. Based on the predominance of shear strain across proximal P1, shear forces are likely the predominant biomechanical contributor to sagittal fractures of P1.
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Affiliation(s)
- Ellen Singer
- E Singer Equine Orthopaedics and Surgery, 14 Brooklands Rd, Parkgate, Neston, Cheshire, CH646SW, UK.
| | - Tanya Garcia
- JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, CA, USA
| | - Susan Stover
- JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, CA, USA
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Marcé-Nogué J, Püschel TA, Daasch A, Kaiser TM. Broad-scale morpho-functional traits of the mandible suggest no hard food adaptation in the hominin lineage. Sci Rep 2020; 10:6793. [PMID: 32322020 PMCID: PMC7176708 DOI: 10.1038/s41598-020-63739-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 03/01/2020] [Indexed: 11/14/2022] Open
Abstract
An on-going debate concerning the dietary adaptations of archaic hominins and early Homo has been fuelled by contradictory inferences obtained using different methodologies. This work presents an extensive comparative sample of 30 extant primate species that was assembled to perform a morpho-functional comparison of these taxa with 12 models corresponding to eight fossil hominin species. Finite Element Analysis and Geometric Morphometrics were employed to analyse chewing biomechanics and mandible morphology to, firstly, establish the variation of this clade, secondly, relate stress and shape variables, and finally, to classify fossil individuals into broad ingesta related hardness categories using a support vector machine algorithm. Our results suggest that some hominins previously assigned as hard food consumers (e.g. the members of the Paranthropus clade) in fact seem to rely more strongly on soft foods, which is consistent with most recent studies using either microwear or stable isotope analyses. By analysing morphometric and stress results in the context of the comparative framework, we conclude that in the hominin clade there were probably no hard-food specialists. Nonetheless, the biomechanical ability to comminute harder items, if required as fallback option, adds to their strategy of increased flexibility.
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Affiliation(s)
- Jordi Marcé-Nogué
- Centrum für Naturkunde, University of Hamburg, Martin-Luter-King-Platz 3, 20146, Hamburg, Germany.
- Institut Català de Paleontologia M. Crusafont, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain.
| | - Thomas A Püschel
- Primate Models for Behavioural Evolution, Institute of Cognitive and Evolutionary Anthropology, University of Oxford, 64 Banbury Road, Oxford, OX2 6PN, United Kingdom
| | - Alexander Daasch
- Centrum für Naturkunde, University of Hamburg, Martin-Luter-King-Platz 3, 20146, Hamburg, Germany
| | - Thomas M Kaiser
- Centrum für Naturkunde, University of Hamburg, Martin-Luter-King-Platz 3, 20146, Hamburg, Germany
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Dental topography and the diet of Homo naledi. J Hum Evol 2018; 118:14-26. [DOI: 10.1016/j.jhevol.2018.02.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 11/20/2022]
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Sylvester AD, Kramer PA. Young's Modulus and Load Complexity: Modeling Their Effects on Proximal Femur Strain. Anat Rec (Hoboken) 2018; 301:1189-1202. [PMID: 29451371 DOI: 10.1002/ar.23796] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 10/23/2017] [Accepted: 11/27/2017] [Indexed: 01/22/2023]
Abstract
Finite element analysis (FEA) is a powerful tool for evaluating questions of functional morphology, but the application of FEA to extant or extinct creatures is a non-trivial task. Three categories of input data are needed to appropriately implement FEA: geometry, material properties, and boundary conditions. Geometric data are relatively easily obtained from imaging techniques, but often material properties and boundary conditions must be estimated. Here we conduct sensitivity analyses of the effect of the choice of Young's Modulus for elements representing trabecular bone and muscle loading complexity on the proximal femur using a finite element mesh of a modern human femur. We found that finite element meshes that used a Young's Modulus between 500 and 1,500 MPa best matched experimental strains. Loading scenarios that approximated the insertion sites of hip musculature produced strain patterns in the region of the greater trochanter that were different from scenarios that grouped muscle forces to the superior greater trochanter, with changes in strain values of 40% or more for 20% of elements. The femoral head, neck, and proximal shaft were less affected (e.g. approximately 50% of elements changed by 10% or less) by changes in the location of application of muscle forces. From our sensitivity analysis, we recommend the use of a Young's Modulus for the trabecular elements of 1,000 MPa for the proximal femur (range 500-1,500 MPa) and that the muscular loading complexity be dependent on whether or not strains in the greater trochanter are the focus of the analytical question. Anat Rec, 301:1189-1202, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Adam D Sylvester
- The John Hopkins University School of Medicine, Center for Functional Anatomy and Evolution, 1830 E. Monument Street, Baltimore, Maryland
| | - Patricia A Kramer
- Department of Anthropology, University of Washington, 314 Denny Hall, Seattle, Washington
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Berthaume MA, Schroer K. Extant ape dental topography and its implications for reconstructing the emergence of early Homo. J Hum Evol 2017; 112:15-29. [DOI: 10.1016/j.jhevol.2017.09.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/01/2017] [Accepted: 09/05/2017] [Indexed: 11/30/2022]
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Panagiotopoulou O, Iriarte-Diaz J, Wilshin S, Dechow PC, Taylor AB, Mehari Abraha H, Aljunid SF, Ross CF. In vivo bone strain and finite element modeling of a rhesus macaque mandible during mastication. ZOOLOGY 2017; 124:13-29. [PMID: 29037463 DOI: 10.1016/j.zool.2017.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 12/29/2022]
Abstract
Finite element analysis (FEA) is a commonly used tool in musculoskeletal biomechanics and vertebrate paleontology. The accuracy and precision of finite element models (FEMs) are reliant on accurate data on bone geometry, muscle forces, boundary conditions and tissue material properties. Simplified modeling assumptions, due to lack of in vivo experimental data on material properties and muscle activation patterns, may introduce analytical errors in analyses where quantitative accuracy is critical for obtaining rigorous results. A subject-specific FEM of a rhesus macaque mandible was constructed, loaded and validated using in vivo data from the same animal. In developing the model, we assessed the impact on model behavior of variation in (i) material properties of the mandibular trabecular bone tissue and teeth; (ii) constraints at the temporomandibular joint and bite point; and (iii) the timing of the muscle activity used to estimate the external forces acting on the model. The best match between the FEA simulation and the in vivo experimental data resulted from modeling the trabecular tissue with an isotropic and homogeneous Young's modulus and Poisson's value of 10GPa and 0.3, respectively; constraining translations along X,Y, Z axes in the chewing (left) side temporomandibular joint, the premolars and the m1; constraining the balancing (right) side temporomandibular joint in the anterior-posterior and superior-inferior axes, and using the muscle force estimated at time of maximum strain magnitude in the lower lateral gauge. The relative strain magnitudes in this model were similar to those recorded in vivo for all strain locations. More detailed analyses of mandibular strain patterns during the power stroke at different times in the chewing cycle are needed.
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Affiliation(s)
- Olga Panagiotopoulou
- Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia; Department of Anatomy and Developmental Biology, School of Biomedical Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - José Iriarte-Diaz
- Department of Oral Biology, University of Illinois, 801 S. Paulina St., Chicago, IL 60612, USA
| | - Simon Wilshin
- Department of Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, United Kingdom
| | - Paul C Dechow
- Department of Biomedical Sciences, College of Dentistry, Texas A&M University, 3302 Gaston Ave., Dallas, TX 75246, USA
| | - Andrea B Taylor
- Department of Basic Science, Touro University, 1310 Club Drive, Mare Island, Vellejo, CA 94592, USA
| | - Hyab Mehari Abraha
- Moving Morphology & Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Sharifah F Aljunid
- Materialise Unit 5-01, Menara OBYU, No. 4, Jalan PJU 8/8A, Damansara Perdana, 47820 Petaling Jaya, Selangor, Malaysia
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th St., Chicago, IL 60637, USA.
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Internal Bone Architecture in the Zygoma of Human andPan. Anat Rec (Hoboken) 2016; 299:1704-1717. [DOI: 10.1002/ar.23499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 08/07/2016] [Accepted: 08/16/2016] [Indexed: 11/07/2022]
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Wang Q, Dechow PC. Divided Zygomatic Bone in Primates With Implications of Skull Morphology and Biomechanics. Anat Rec (Hoboken) 2016; 299:1801-1829. [DOI: 10.1002/ar.23448] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/12/2016] [Accepted: 04/15/2016] [Indexed: 01/06/2023]
Affiliation(s)
- Qian Wang
- Department of Biomedical Sciences Texas A&M University College of Dentistry; Dallas Texas
| | - Paul C. Dechow
- Department of Biomedical Sciences Texas A&M University College of Dentistry; Dallas Texas
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Cuff AR, Bright JA, Rayfield EJ. Validation experiments on finite element models of an ostrich (Struthio camelus) cranium. PeerJ 2015; 3:e1294. [PMID: 26500813 PMCID: PMC4614885 DOI: 10.7717/peerj.1294] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 09/15/2015] [Indexed: 11/20/2022] Open
Abstract
The first finite element (FE) validation of a complete avian cranium was performed on an extant palaeognath, the ostrich (Struthio camelus). Ex-vivo strains were collected from the cranial bone and rhamphotheca. These experimental strains were then compared to convergence tested, specimen-specific finite element (FE) models. The FE models contained segmented cortical and trabecular bone, sutures and the keratinous rhamphotheca as identified from micro-CT scan data. Each of these individual materials was assigned isotropic material properties either from the literature or from nanoindentation, and the FE models compared to the ex-vivo results. The FE models generally replicate the location of peak strains and reflect the correct mode of deformation in the rostral region. The models are too stiff in regions of experimentally recorded high strain and too elastic in regions of low experimentally recorded low strain. The mode of deformation in the low strain neurocranial region is not replicated by the FE models, and although the models replicate strain orientations to within 10° in some regions, in most regions the correlation is not strong. Cranial sutures, as has previously been found in other taxa, are important for modifying both strain magnitude and strain patterns across the entire skull, but especially between opposing the sutural junctions. Experimentally, we find that the strains on the surface of the rhamphotheca are much lower than those found on nearby bone. The FE models produce much higher principal strains despite similar strain ratios across the entirety of the rhamphotheca. This study emphasises the importance of attempting to validate FE models, modelling sutures and rhamphothecae in birds, and shows that whilst location of peak strain and patterns of deformation can be modelled, replicating experimental data in digital models of avian crania remains problematic.
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Affiliation(s)
- Andrew R Cuff
- GEE, University College London , London , United Kingdom ; Structure and Motion Laboratory, The Royal Veterinary College , Hatfield , United Kingdom ; School of Earth Sciences, University of Bristol , Bristol , United Kingdom
| | - Jen A Bright
- School of Earth Sciences, University of Bristol , Bristol , United Kingdom ; Department of Animal and Plant Sciences, University of Sheffield , Sheffield , United Kingdom
| | - Emily J Rayfield
- School of Earth Sciences, University of Bristol , Bristol , United Kingdom
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Abstract
BACKGROUND Changes in health care access and birthing practices may pose barriers to optimal breastfeeding in modernizing rural populations. OBJECTIVES We evaluated temporal and maternal age-related trends in birth and breastfeeding in a modernizing Maya agriculturalist community. We tested 2 hypotheses: (1) home births would be associated with better breastfeeding outcomes than hospital births, and (2) vaginal births would be associated with better breastfeeding outcomes than cesarean births. METHODS We interviewed 58 Maya mothers (ages 21-85) regarding their births and breastfeeding practices. General linear models were used to evaluate trends in birthing practices and breastfeeding outcomes (timing of breastfeeding initiation, use of infant formula, age of introduction of complementary feeding, and breastfeeding duration). We then compared breastfeeding outcomes by location (home or hospital) and mode of birth (vaginal or cesarean). RESULTS Timing of breastfeeding initiation and the rate of formula feeding both increased significantly over time. Younger mothers introduced complementary foods earlier, breastfed for shorter durations, and formula fed more than older mothers. Vaginal hospital births were associated with earlier breastfeeding initiation and longer breastfeeding durations than home births. Cesarean births were associated with later breastfeeding initiation, shorter breastfeeding durations, and more formula feeding than vaginal hospital births. CONCLUSION We have observed temporal and maternal age-related trends toward suboptimal breastfeeding patterns in the Maya community. Contrary to our first hypothesis, hospital births per se were not associated with negative breastfeeding outcomes. In support of our second hypothesis, cesarean versus vaginal births were associated with negative breastfeeding outcomes.
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