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Franchetti G, Viel G, Fais P, Fichera G, Cecchin D, Cecchetto G, Giraudo C. Forensic applications of micro-computed tomography: a systematic review. Clin Transl Imaging 2022. [DOI: 10.1007/s40336-022-00510-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Abstract
Purpose
The aim of this systematic review was to provide a comprehensive overview of micro-CT current applications in forensic pathology, anthropology, odontology, and neonatology.
Methods
A bibliographic research on the electronic databases Pubmed and Scopus was conducted in the time frame 01/01/2001–31/12/2021 without any language restrictions and applying the following free-text search strategy: “(micro-computed tomography OR micro-CT) AND (forensic OR legal)”. The following inclusion criteria were used: (A) English language; (B) Application of micro-CT to biological and/or non-biological materials to address at least one forensic issue (e.g., age estimation, identification of post-mortem interval). The papers selected by three independent investigators have been then classified according to the investigated materials.
Results
The bibliographic search provided 651 records, duplicates excluded. After screening for title and/or abstracts, according to criteria A and B, 157 full-text papers were evaluated for eligibility. Ninety-three papers, mostly (64) published between 2017 and 2021, were included; considering that two papers investigated several materials, an overall amount of 99 classifiable items was counted when referring to the materials investigated. It emerged that bones and cartilages (54.55%), followed by teeth (13.13%), were the most frequently analyzed materials. Moreover, micro-CT allowed the collection of structural, qualitative and/or quantitative information also for soft tissues, fetuses, insects, and foreign materials.
Conclusion
Forensic applications of micro-CT progressively increased in the last 5 years with very promising results. According to this evidence, we might expect in the near future a shift of its use from research purposes to clinical forensic cases.
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Keys K, Ross AH. Identifying Blunt Force Traumatic Injury on Thermally Altered Remains: A Pilot Study Using Sus scrofa. BIOLOGY 2022; 11:biology11010087. [PMID: 35053085 PMCID: PMC8773201 DOI: 10.3390/biology11010087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 11/23/2022]
Abstract
Simple Summary Human remains are often burned in an effort to conceal the identity of the victim and/or obscure traumatic injuries related to the death event. Thermal exposure can produce artifacts resembling trauma and disguise preexisting trauma. However, there is a paucity of experimental studies with varied results addressing the differentiation of thermally induced artifacts from traumatic signatures. To address this gap in the literature, we conducted a small-scale study using domestic pigs as correlates to test the impact of thermal alteration on blunt force trauma to the cranium. Two tools (e.g., hammer and crowbar) were utilized to manually inflict injuries on the human analogs before controlled burning in an outdoor environment. The results of this experiment demonstrated that the most diagnostic variable to differentiate thermally induced alternations from blunt force fractures was fracture pattern. Abstract In forensic scenarios involving homicide, human remains are often exposed to fire as a means of disposal and/or obscuring identity. Burning human remains can result in the concealment of traumatic injury, the creation of artifacts resembling injury, or the destruction of preexisting trauma. Since fire exposure can greatly influence trauma preservation, methods to differentiate trauma signatures from burning artifacts are necessary to conduct forensic analyses. Specifically, in the field of forensic anthropology, criteria to distinguish trauma from fire signatures on bone is inconsistent and sparse. This study aims to supplement current forensic anthropological literature by identifying criteria found to be the most diagnostic of fire damage or blunt force trauma. Using the skulls of 11 adult pigs (Sus scrofa), blunt force trauma was manually produced using a crowbar and flat-faced hammer. Three specimens received no impacts and were utilized as controls. All skulls were relocated to an outdoor, open-air fire where they were burned until a calcined state was achieved across all samples. Results from this experiment found that blunt force trauma signatures remained after burning and were identifiable in all samples where reassociation of fragments was possible. This study concludes that distinct patterns attributed to thermal fractures and blunt force fractures are identifiable, allowing for diagnostic criteria to be narrowed down for future analyses.
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Brazda IJ, Reeves J, Langohr GDG, Crookshank MC, Schemitsch EH, Zdero R. Biomechanical properties and thermal characteristics of frozen versus thawed whole bone. Proc Inst Mech Eng H 2020; 234:874-883. [PMID: 32515277 DOI: 10.1177/0954411920929455] [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] [Indexed: 11/17/2022]
Abstract
Biomechanics research often requires cadaveric whole bones to be stored in a freezer and then thawed prior to use; however, the literature shows a variety of practices for thawing. Consequently, this is the first study to report the mechanical properties of fully frozen versus fully thawed whole bone as 'proof of principle'. Two groups of 10 porcine ribs each were statistically equivalent at baseline in length, cross-sectional area, and bone mineral density. The two groups were stored in a freezer for at least 24 h, thawed in air at 23 °C for 4 h while temperature readings were taken to establish the time needed for thawing, and once again returned to the freezer for at least 24 h. Mechanical tests to failure using three-point bending were then done on the 'frozen' group immediately after removal from the freezer and the 'thawed' group when steady-state ambient air temperature was reached. Temperature readings over the entire thawing period were described by the line-of-best-fit formula T = (28.34t - 6.69)/(t + 0.38), where T = temperature in degree Celsius and t = time in hours, such that frozen specimens at t = 0 h had a temperature of -17 °C and thawed specimens at t = 1.75 h reached a steady-state temperature of 20 °C-23 °C. Mechanical tests showed that frozen versus thawed specimens had an average of 32% higher stiffness k, 34% higher ultimate force Fu, 28% lower ultimate displacement δu, 40% lower ultimate work Wu, 43% higher elastic modulus E, 37% higher ultimate normal stress σu, and 33% higher ultimate shear stress τu. Whole ribs failed at midspan primarily by transverse cracking (16 of 20 cases), oblique cracking (three of 20 cases), or surface denting (one of 20 cases), each having unique shapes for force versus displacement graphs differentiated mainly by ultimate force location.
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Affiliation(s)
- Ignace J Brazda
- Orthopaedic Biomechanics Lab, Victoria Hospital, London, ON, Canada
| | - Jacob Reeves
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada
| | - G Daniel G Langohr
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada
| | | | - Emil H Schemitsch
- Orthopaedic Biomechanics Lab, Victoria Hospital, London, ON, Canada.,Division of Orthopaedic Surgery, Western University, London, ON, Canada
| | - Radovan Zdero
- Orthopaedic Biomechanics Lab, Victoria Hospital, London, ON, Canada.,Department of Mechanical and Materials Engineering, Western University, London, ON, Canada.,Division of Orthopaedic Surgery, Western University, London, ON, Canada.,Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
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Li Z, Wang J, Song G, Ji C, Han X. Anisotropic and strain rate-dependent mechanical properties and constitutive modeling of the cancellous bone from piglet cervical vertebrae. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 188:105279. [PMID: 31865093 DOI: 10.1016/j.cmpb.2019.105279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 11/06/2019] [Accepted: 12/13/2019] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND OBJECTIVE Characterizing the mechanical properties of the cancellous bone from the cervical vertebrae of child or child surrogate is important for the development of spine finite element models and the investigation of injury mechanism, however, there is currently no public data available as far as we know. METHODS Compression tests were conducted on the specimens from the cervical vertebrae of 8-week-old piglets (child surrogates) in axial and radial directions at the strain rates of 0.01, 0.1, 1 and 10/s. The influences of directionality and strain rate on the mechanical properties of the vertebral cancellous bone were statistically investigated. The typical transversely isotropic model, which was added a strain rate item and a plasticity item, was implemented into LS-DYNA finite element code. Based on the material subroutine code, simulation was conducted on the vertebral tissue under compression in axial and radial directions at different strain rates. RESULTS The mechanical properties of the cancellous bone of cervical vertebrae were obtained and most of the stress-strain curves showed major linear elastic stage and short plastic stage before fracture. Significant anisotropic behavior was observed for the vertebral tissue in axial and radial directions. The elastic modulus, ultimate stress,yield stress, and ultimate strain of the speimens in axial direction was obtained, with on average, 2.5 ± 0.6 times, 2.1 ± 0.15 times, and 2.1 ± 0.1 times higher and 0.86 ± 0.076 times lower respecitvely, than those in radial direction. In addition, with the strain rate varying from 0.01/s to 10/s, the mechanical parameters, like elastic modulus, yield and ultimte stresses exhibited significant strain rate effect, however, no significant difference was found for the ultimate strain. CONCLUSIONS The cervical vertebrae showed significant anisotropic and strain rate-dependent behaviors. The self-developed subroutine codes based on the strain rate-dependent transversely isotropic elastic and plastic constitutive model can simulate the behaviors well.
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Affiliation(s)
- Zhigang Li
- School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China.
| | - Jinjin Wang
- School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - Guanghui Song
- School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - Cheng Ji
- School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - Xinfeng Han
- HanDan Central Hospital, Handan 056001, China
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Ondruschka B, Lee JHC, Scholze M, Zwirner J, Tong D, Waddell JN, Hammer N. A biomechanical comparison between human calvarial bone and a skull simulant considering the role of attached periosteum and dura mater. Int J Legal Med 2019; 133:1603-1610. [PMID: 31203433 DOI: 10.1007/s00414-019-02102-4] [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] [Received: 11/16/2018] [Accepted: 06/04/2019] [Indexed: 10/26/2022]
Abstract
PURPOSE Current forensic analysis of blunt force trauma relies on the use of cadaveric or animal tissues, posing ethical and reproducibility concerns. Artificial substitutes may help overcome such issues. However, existing substitutes exhibit poor anatomic and mechanical biofidelity, especially in the choice of skull simulant material. Progress has been made in identifying materials that have similar mechanical properties to the human skull bone, with the potential to behave similarly in mechanical loading. AIMS To compare the biomechanical properties of the human calvarial bone with an epoxy resin-based simulant material. Data collected was also used to analyse the effect of periosteal attachment on the mechanical properties of skull bone compared with that of the counterpart samples. METHODS Fifty-six human skull bone specimens were prepared from two cadaveric heads. Half of these specimens were removed of periosteum and dura mater as the PR (periosteum removed) group, whereas periosteum was left attached in the PA (periosteum attached) group. Duplicates of the bone specimens were fabricated out of an epoxy resin and paired in corresponding PR and PA groups. The specimens were loaded under three-point bending tests until fracture with image-based deformation detection. RESULTS Comparison of the epoxy resin and skull specimens yielded similarity for both the PR and PA groups, being closer to the PA group (bending modulus resin PR 2665 MPa vs. skull PR 1979 MPa, resin PA 3165 MPa vs. skull PA 3330 MPa; maximum force resin PR 574 N vs. skull PR 728 N, resin PA 580 N vs. skull PA 1034 N; strain at maximum force resin PR 2.7% vs. skull PR 5.1%, resin PA 2.3% vs. skull PA 3.5%, deflection at maximum force resin PR 0.5 mm vs. skull PR 0.8 mm, resin PA 0.5 mm vs. skull PA 1.0 mm). Bending strength was significantly lower in the resin groups (resin PR 43 MPa vs. skull PR 55 MPa, resin PA 44 MPa vs. skull PA 75 MPa). Moreover, the correlations of the mechanical data exhibited closer accordance of the PR group with the epoxy resin compared with the PA group with the epoxy resin. CONCLUSIONS The load-deformation properties of the epoxy resin samples assessed in this study fell within a closer range to the skull specimens with PR than with PA. Moreover, the values obtained for the resin fall within the reference range for skull tissues in the literature suggesting that the proposed epoxy resin may provide a usable artificial substitute for PA but does not totally represent the human skull in its complex anatomical structure.
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Affiliation(s)
- Benjamin Ondruschka
- Institute of Legal Medicine, University of Leipzig, Johannisallee 28, 04103, Leipzig, Germany.
| | | | - Mario Scholze
- Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz, Germany.,Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Johann Zwirner
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Darryl Tong
- Department of Oral Diagnostic and Surgical Sciences, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
| | - John Neil Waddell
- Faculty of Dentistry, University of Otago, Dunedin, New Zealand.,Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand
| | - Niels Hammer
- Department of Anatomy, University of Otago, Dunedin, New Zealand.,Department of Orthopedic, Trauma and Reconstructive Surgery, University of Leipzig, Leipzig, Germany.,Fraunhofer Institute for Machine Tools and Forming Technology IWU, Dresden, Germany
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Ambrose CG, Soto Martinez M, Bi X, Deaver J, Kuzawa C, Schwartz L, Dawson B, Bachim A, Polak U, Lee B, Crowder C. Mechanical properties of infant bone. Bone 2018; 113:151-160. [PMID: 29800692 DOI: 10.1016/j.bone.2018.05.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 05/11/2018] [Accepted: 05/13/2018] [Indexed: 11/15/2022]
Abstract
Although an understanding of bone material properties is crucial for interpreting and predicting fracture patterns due to injury or defining the effects of disease on bone strength, information about infant bone properties is scant in the literature. In this study we present the mechanical testing results from 47 tibia and 52 rib specimens taken from 53 infant decedents in order to further our understanding of infant bone strength. Bone specimens were imaged using microCT and tested in three-point bending until failure. Extrinsic and intrinsic properties demonstrated an increase in strength and stiffness over the first year of life, while ductility measures remained largely unchanged. Donor race had no effect on the material properties, but tibia bone specimens showed significant sex differences, with the elastic modulus from females being larger than males. When compared to properties from adolescent and adult donors, infant bone is less strong, less stiff, and more ductile.
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Affiliation(s)
- Catherine G Ambrose
- The University of Texas Health Science Center at Houston McGovern Medical School, Department of Orthopaedic Surgery, United States.
| | | | - Xiaohong Bi
- The University of Texas Health Science Center at Houston McGovern Medical School, Department of Nanomedicine and Biomedical Engineering, United States
| | - Juanita Deaver
- The University of Texas Health Science Center at Houston McGovern Medical School, Department of Orthopaedic Surgery, United States
| | - Cole Kuzawa
- The University of Texas Health Science Center at Houston McGovern Medical School, Department of Orthopaedic Surgery, United States
| | - Lindsey Schwartz
- The University of Texas Health Science Center at Houston McGovern Medical School, Department of Orthopaedic Surgery, United States
| | - Brian Dawson
- Baylor College of Medicine, Department of Molecular and Human Genetics, United States
| | - Angela Bachim
- Baylor College of Medicine, Section of Public Health Pediatrics, United States
| | - Urszula Polak
- Baylor College of Medicine, Department of Molecular and Human Genetics, United States
| | - Brendan Lee
- Baylor College of Medicine, Department of Molecular and Human Genetics, United States
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Pluim JME, Jimenez-Bou L, Gerretsen RRR, Loeve AJ. Aerosol production during autopsies: The risk of sawing in bone. Forensic Sci Int 2018; 289:260-267. [PMID: 29909298 PMCID: PMC7126880 DOI: 10.1016/j.forsciint.2018.05.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/08/2018] [Accepted: 05/26/2018] [Indexed: 11/25/2022]
Abstract
When sawing during autopsies on human remains, fine dust is produced, which consists of particles of sizes that may fall within the human respirable range, and can act as vectors for pathogens. The goal of this study was to explore the potential effects of saw blade frequency and saw blade contact load on the number and size of airborne bone particles produced. The methodology involved the use of an oscillating saw with variable saw blade frequencies and different saw blade contact loads on dry human femora. Released airborne particles were counted per diameter by a particle counter inside a closed and controlled environment. Results corroborated with the hypotheses: higher frequencies or lower contact loads resulted in higher numbers of aerosol particles produced. However, it was found that even in the best-case scenario tested on dry bone, the number of aerosol particles produced was still high enough to provide a potential health risk to the forensic practitioners. Protective breathing gear such as respirators and biosafety protocols are recommended to be put into practice to protect forensic practitioners from acquiring pathologies, or from other biological hazards when performing autopsies.
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Affiliation(s)
- Jip M E Pluim
- Department of Forensic Anthropology, Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB The Hague, The Netherlands; Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, F-0-200, Mekelweg 2, 2628CD Delft, The Netherlands.
| | - Lucas Jimenez-Bou
- Department of Forensic Anthropology, Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB The Hague, The Netherlands.
| | - Reza R R Gerretsen
- Department of Forensic Anthropology, Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB The Hague, The Netherlands.
| | - Arjo J Loeve
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, F-0-200, Mekelweg 2, 2628CD Delft, The Netherlands; Co van Ledden-Hulsebosch Centrum, Science Park Building 904, 1098XH Amsterdam, The Netherlands.
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Mokrane FZ, Dercle L, Meyrignac O, Crubézy É, Rousseau H, Telmon N, Dedouit F. Towards multi-phase postmortem CT angiography in children: a study on a porcine model. Int J Legal Med 2018; 132:1391-1403. [PMID: 29380125 DOI: 10.1007/s00414-018-1783-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 01/16/2018] [Indexed: 10/18/2022]
Abstract
PURPOSE Multi-phase postmortem computed tomography angiography (MPMCTA) is a growing technique, which is standardized for adults. Application of this protocol for a children population is not so well defined. Our study aims to adapt the adult's protocol to children, using a porcine model. MATERIAL AND METHODS Three groups of 18 pigs were studied, with a weight distribution between 4 and 48 kg. Different pump devices were used. Pigs of group I were studied using the Virtangio® machine, whereas pigs of groups II and III were studied using used the Medrad® machine. Study of vascular opacification was possible using a semi-quantitative method based on 26 arterial and 26 venous segments that were distributed over the entire body from the cephalic extremity to the posterior pawns. RESULTS While thoracic, abdominal, and pelvic vascular opacification were complete for each individual pig in a group, group III showed better vascular opacification for the cephalic extremity. This was also true for anterior and posterior pawns vascular opacification. Spearman correlation tests showed a significant relationship between anthropometric characteristics of pigs, injection parameters, and percentage of opacified segments. A higher percentage of opacification was obtained for individuals of lower weights, with comparatively lower quantities of contrast agent injected. CONCLUSION Postmortem computed tomography angiography (PMCTA) was possible for all the individuals, particularly for small weights (4 kg) using the Medrad® machine. However, further studies are needed to better understand the procedure.
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Affiliation(s)
- F Z Mokrane
- Radiology Department, Rangueil University Hospital, 1 Avenue du Professeur Jean Poulhes, 31059 cedex, Toulouse, France. .,French National Center for Scientific Research, AMIS Laboratory: University of Toulouse, UMR 5288, 37 allées Jules Guesde, 31073, Toulouse, France.
| | - L Dercle
- Gustave Roussy Institute, Université Paris-Saclay, F-94805, Villejuif, France.,New York Presbyterian Hospital, Columbia University, New York, NY, 10039, USA
| | - O Meyrignac
- Radiology Department, Rangueil University Hospital, 1 Avenue du Professeur Jean Poulhes, 31059 cedex, Toulouse, France
| | - É Crubézy
- French National Center for Scientific Research, AMIS Laboratory: University of Toulouse, UMR 5288, 37 allées Jules Guesde, 31073, Toulouse, France
| | - H Rousseau
- Radiology Department, Rangueil University Hospital, 1 Avenue du Professeur Jean Poulhes, 31059 cedex, Toulouse, France
| | - N Telmon
- French National Center for Scientific Research, AMIS Laboratory: University of Toulouse, UMR 5288, 37 allées Jules Guesde, 31073, Toulouse, France.,Forensic Department, Rangueil University Hospital, 1 avenue du Professeur Jean Poulhes. 31059 cedex, Toulouse, France
| | - F Dedouit
- French National Center for Scientific Research, AMIS Laboratory: University of Toulouse, UMR 5288, 37 allées Jules Guesde, 31073, Toulouse, France.,Unit of Forensic and Anthropological Imaging, Centre universitaire romand de médecine légale (CURML), Chemin de la Vulliette 4, CH-1000, Lausanne 25, Switzerland
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Macoveciuc I, Márquez-Grant N, Horsfall I, Zioupos P. Sharp and blunt force trauma concealment by thermal alteration in homicides: An in-vitro experiment for methodology and protocol development in forensic anthropological analysis of burnt bones. Forensic Sci Int 2017; 275:260-271. [DOI: 10.1016/j.forsciint.2017.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 01/16/2017] [Accepted: 03/20/2017] [Indexed: 10/19/2022]
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10
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Blackburne WB, Waddell JN, Swain MV, Alves de Sousa RJ, Kieser JA. Biomechanical investigation of impact induced rib fractures of a porcine infant surrogate model. J Mech Behav Biomed Mater 2016; 62:588-598. [DOI: 10.1016/j.jmbbm.2016.05.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 05/10/2016] [Accepted: 05/23/2016] [Indexed: 11/29/2022]
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Beadle N, Burnett TL, Hoyland JA, Sherratt MJ, Freemont AJ. A novel ex vivo model of compressive immature rib fractures at pathophysiological rates of loading. J Mech Behav Biomed Mater 2015; 51:154-62. [PMID: 26253206 DOI: 10.1016/j.jmbbm.2015.06.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/19/2015] [Accepted: 06/27/2015] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Compressive rib fractures are considered to be indicative of non-accidental injury (NAI) in infants, which is a significant and growing issue worldwide. The diagnosis of NAI is often disputed in a legal setting, and as a consequence there is a need to model such injuries ex vivo in order to characterise the forces required to produce non-accidental rib fractures. However, current models are limited by type of sample, loading method and rate of loading. Here, we aimed to: i) develop a loading system for inducing compressive fractures in whole immature ribs that is more representative of the physiological conditions and mechanism of injury employed in NAI and ii) assess the influence of loading rate and rib geometry on the mechanical performance of the tissue. METHODS Porcine ribs (5-6 weeks of age) from 12 animals (n=8 ribs/animal) were subjected to axial compressive load directed through the anterior-posterior rib axis at loading rates of 1, 30, 60 or 90 mm/s. Key mechanical parameters (including peak load, load and percentage deformation to failure and effective stiffness) were quantified from the load-displacement curves. Measurements of the rib length, thickness at midpoint, distance between anterior and posterior extremities, rib curvature and fracture location were determined from radiographs. RESULTS This loading method typically produced incomplete fractures around the midpoint of the ribs, with 87% failing in this manner; higher loads and less deformation were required for ribs to completely fracture through both cortices. Loading rate, within the range of 1-90 mm/s, did not significantly affect any key mechanical parameters of the ribs. Load-displacement curves displaying characteristic and quantifiable features were produced for 90% of the ribs tested, and multiple regression analyses indicate that, in addition to the geometrical variables, there are other factors such as the micro- and nano-structure that influence the measured mechanical data. CONCLUSIONS A reproducible method of inducing fractures in a consistent location in immature porcine ribs has been successfully developed. Fracture appearance may be indicative of the amount of load and deformation that produced the fracture, which is an important finding for NAI, where knowledge of the aetiology of fractures is vital. Characteristic rib behaviour independent of loading rate and, to an extent, rib geometry has been demonstrated, allowing further investigation into how the complex micro- and nano-structure of immature ribs influences the mechanical performance under compressive load. This research will ultimately enable improved characterisation of the loading pattern involved in non-accidental rib fractures.
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Affiliation(s)
- Nicola Beadle
- Centre for Tissue Injury and Repair, Institute of Inflammation and Repair and Manchester NIHR Musculoskeletal BRU, Faculty of Medical and Human Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom
| | - Timothy L Burnett
- Materials Science Centre, University of Manchester, Oxford Road, M13 9PT, United Kingdom
| | - Judith A Hoyland
- Centre for Tissue Injury and Repair, Institute of Inflammation and Repair and Manchester NIHR Musculoskeletal BRU, Faculty of Medical and Human Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom
| | - Michael J Sherratt
- Centre for Tissue Injury and Repair, Institute of Inflammation and Repair and Manchester NIHR Musculoskeletal BRU, Faculty of Medical and Human Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom
| | - Anthony J Freemont
- Centre for Tissue Injury and Repair, Institute of Inflammation and Repair and Manchester NIHR Musculoskeletal BRU, Faculty of Medical and Human Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom.
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Biomechanical investigation of the classic metaphyseal lesion using an immature porcine model. AJR Am J Roentgenol 2015; 204:W503-9. [PMID: 25905956 DOI: 10.2214/ajr.14.13267] [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] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The classic metaphyseal lesion is highly associated with abuse in infants. Classic metaphyseal lesions, also referred to as corner or bucket-handle fractures, are fractures through the metaphyseal region of the long bones near the growth plate. Knowledge of the biomechanics and mechanisms necessary to produce a classic metaphyseal lesion may provide insight into the injury causation associated with this unique fracture type. Thus, the purpose of this study was to investigate loading conditions necessary to create a classic metaphyseal lesion using an immature porcine model. MATERIALS AND METHODS Twenty-four pelvic limb specimens from 7-day-old and 3-day-old piglets were tested in lateral bending (varus and valgus) using an electromechanical testing machine. All specimens were loaded dynamically in four-point bending at a rate of 100 inches/min. Microcomputed tomography was performed on specimens before and after testing. Pre- and posttest CT images were compared to assess whether fracture had occurred. RESULTS Fractures resembling classic metaphyseal lesions were identified in 12 of the 24 specimens. Microcomputed tomography images revealed trabecular disruptions visually similar to classic metaphyseal lesions in children. CONCLUSION Metaphyseal fractures, consistent with clinical classic metaphyseal lesions, resulted from a single loading event delivering varus or valgus bending to the stifle (knee). A classic metaphyseal lesion is a unique type of fracture with specific morphologic characteristics. Therefore, we suggest using the term "classic metaphyseal fracture" in lieu of classic metaphyseal lesion to improve precision of terminology.
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