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Li, X., Sandler, H. & Kleiven, S. (2019). Infant skull fractures: Accident or abuse? Evidences from biomechanical analysis using finite element head models. Forensic Science International, 294, 173-182
Open this publication in new window or tab >>Infant skull fractures: Accident or abuse? Evidences from biomechanical analysis using finite element head models
2019 (English)In: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 294, p. 173-182Article in journal (Refereed) Published
Abstract [en]

Abusive Head Trauma (AHT) is considered by some authors to be a leading cause of traumatic death in children less than two years of age and skull fractures are commonly seen in cases of suspected AHT. Today, diagnosing whether the observed fractures are caused by abuse or accidental fall is still a challenge within both the medical and the legal communities and the central question is a biomechanical question: can the described history explain the observed fractures? Finite element (FE) analysis has been shown a valuable tool for biomechanical analysis accounting for detailed head geometry, advanced material modelling, and case-specific factors (e.g. head impact location, impact surface properties). Here, we reconstructed two well-documented suspected abuse cases (a 3- and a 4-month-old) using subject-specific FE head models. The models incorporate the anatomical details and age-dependent anisotropic material properties of infant cranial bones that reflect the grainy fibres radiating from ossification centres. The impact locations are determined by combining multimodality images. The results show that the skull fracture patterns in both cases of suspected abuse could be explained by the described accidental fall history, demonstrating the inherent potential of FE analysis for providing biomechanical evidence to aid forensic investigations. Increased knowledge of injury mechanisms in children may have enormous medico-legal implications world-wide. 

Place, publisher, year, edition, pages
ELSEVIER IRELAND LTD, 2019
Keywords
Abusive Head Trauma, Multiple skull fractures, Finite element head model, Ossification centers, Impact location
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-241324 (URN)10.1016/j.forsciint.2018.11.008 (DOI)000454861200029 ()30529991 (PubMedID)2-s2.0-85057577148 (Scopus ID)
Note

QC 20190125

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-01-25Bibliographically approved
Zhou, Z., Li, X. & Kleiven, S. (2018). Biomechanics of acute subdural hematoma in the elderly: A fluid-structure interaction study. Journal of Neurotrauma
Open this publication in new window or tab >>Biomechanics of acute subdural hematoma in the elderly: A fluid-structure interaction study
2018 (English)In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042Article in journal (Refereed) In press
Abstract [en]

Acute subdural hematoma (ASDH) due to bridging vein (BV) rupture is a frequent and lethal head injury, especially in the elderly. Brain atrophy has been hypothesized to be a primary pathogenesis associated with the increased risk of ASDH in the elderly. Though decades of biomechanical endeavours have been made to elucidate the potential mechanisms, a thorough explanation for this hypothesis appears lacking. Thus, a recently improved finite element head model, in which the brain-skull interface was modelled using a fluid-structure interaction (FSI) approach with special treatment of the cerebrospinal fluid as arbitrary Lagrangian-Eulerian fluid formulation, is used to partially address this understanding gap. Models with various degrees of atrophied brains and thereby different subarachnoid thicknesses are generated and subsequently exposed to experimentally determined loadings known to cause ASDH or not. The results show significant increases in the cortical relative motion and BV strain in the atrophied brain, which consequently exacerbates the ASDH risk in the elderly. Results of this study are suggested to be considered while developing age-adapted protecting strategies for the elderly in the future.

National Category
Medical and Health Sciences Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-243833 (URN)
Note

QC 20190212

Available from: 2019-02-06 Created: 2019-02-06 Last updated: 2019-02-12Bibliographically approved
Alvarez, V. S. & Kleiven, S. (2018). Effect of pediatric growth on cervical spine kinematics and deformations in automotive crashes. Journal of Biomechanics, 71, 76-83, Article ID S0021-9290(18)30075-7.
Open this publication in new window or tab >>Effect of pediatric growth on cervical spine kinematics and deformations in automotive crashes
2018 (English)In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 71, p. 76-83, article id S0021-9290(18)30075-7Article in journal (Refereed) Published
Abstract [en]

Finite element (FE) models are a powerful tool that can be used to understand injury mechanisms and develop better safety systems. This study aims to extend the understanding of pediatric spine biomechanics, where there is a paucity of studies available. A newly developed and continuously scalable FE model was validated and scaled to 1.5-, 3-, 6-, 10-, 14- and 18-year-old using a non-linear scaling technique, accounting for local topological changes. The oldest and youngest ages were also scaled using homogeneous geometric scaling. To study the effect of pediatric spinal growth on head kinematics and intervertebral disc strain, the models were exerted to 3.5 g acceleration pulse at the T1 vertebra to simulate frontal, rear and side impacts. It was shown that the head rotation increases with age, but is over predicted when geometrically scaling down from 18- to 1.5-year-old and under predicted when geometrically scaling up from 1.5- to 18-year-old. The strain in the disc, however, showed a clear decrease with age in side impact and for the upper cervical spine in rear impact, indicating a higher susceptibility for neck injury at younger ages. In the frontal impact, no clear age dependence could be seen, suggesting a large contribution from changed facet joint angles, and lower levels of strain, suggesting a lower risk of injury. The results also highlight the benefit of rearward facing children in a seat limiting head lateral motion.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Automotive crash, Cervical spine, Finite element model, Injury risk, Pediatric growth
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-226283 (URN)10.1016/j.jbiomech.2018.01.038 (DOI)000430765500010 ()29456172 (PubMedID)2-s2.0-85042008342 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme
Note

QC 20180418

Available from: 2018-04-14 Created: 2018-04-14 Last updated: 2018-05-14Bibliographically approved
Zhou, Z., Li, X. & Kleiven, S. (2018). Fluid–structure interaction simulation of the brain–skull interface for acute subdural haematoma prediction. Biomechanics and Modeling in Mechanobiology
Open this publication in new window or tab >>Fluid–structure interaction simulation of the brain–skull interface for acute subdural haematoma prediction
2018 (English)In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2018
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-233858 (URN)10.1007/s10237-018-1074-z (DOI)000457974500012 ()
Note

QC 20180906

Available from: 2018-08-30 Created: 2018-08-30 Last updated: 2019-02-22Bibliographically approved
Li, X. & Kleiven, S. (2018). Improved safety standards are needed to better protect younger children at playgrounds. Scientific Reports, 8, Article ID 15061.
Open this publication in new window or tab >>Improved safety standards are needed to better protect younger children at playgrounds
2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 15061Article in journal (Refereed) Published
Abstract [en]

Playground-related traumatic brain injuries (TBIs) in children remain a considerable problem world-wide and current safety standards are being questioned due to historical reasons where the injury thresholds had been perpetuated from automobile industry. Here we investigated head injury mechanisms due to falls on playgrounds using a previously developed and validated age-scalable and positionable whole body child model impacted at front, back and side of the head simulating head-first falls from 1.59 meters (m). The results show that a playground material passing the current testing standards (HIC < 1000 and resultant linear acceleration <200g) resulted in maximum strain in the brain higher than known injury thresholds, thus not offering sufficient protection especially for younger children. The analysis highlights the age dependence of head injuries in children due to playground falls and the youngest have a higher risk of brain injury and skull fracture. Further, the results provide the first biomechanical evidence guiding age-dependent injury thresholds for playground testing standards. The results also have direct implications for novel designs of playground materials for a better protection of children from TBIs. Only making the playground material thicker and more compliant is not sufficient. This study represents the first initiative of using full body human body models of children as a new tool to improve playground testing standards and to better protect the children at playgrounds.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Neurosciences
Identifiers
urn:nbn:se:kth:diva-237094 (URN)10.1038/s41598-018-33393-z (DOI)000446856000009 ()30305685 (PubMedID)2-s2.0-85054699576 (Scopus ID)
Note

QC 20181022

Available from: 2018-10-24 Created: 2018-10-24 Last updated: 2018-10-24Bibliographically approved
Laksari, K., Kurt, M., Babaee, H., Kleiven, S. & Camarillo, D. (2018). Mechanistic Insights into Human Brain Impact Dynamics through Modal Analysis. Physical Review Letters, 120
Open this publication in new window or tab >>Mechanistic Insights into Human Brain Impact Dynamics through Modal Analysis
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120Article in journal (Refereed) Published
Abstract [en]

Although concussion is one of the greatest health challenges today, our physical understanding of the cause of injury is limited. In this Letter, we simulated football head impacts in a finite element model and extracted the most dominant modal behavior of the brain’s deformation. We showed that the brain’s deformation is most sensitive in low frequency regimes close to 30 Hz, and discovered that for most subconcussive head impacts, the dynamics of brain deformation is dominated by a single global mode. In this Letter, we show the existence of localized modes and multimodal behavior in the brain as a hyperviscoelastic medium. This dynamical phenomenon leads to strain concentration patterns, particularly in deep brain regions, which is consistent with reported concussion pathology.

Place, publisher, year, edition, pages
American Physical Society, 2018
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-226287 (URN)10.1103/PhysRevLett.120.138101 (DOI)000428783300021 ()2-s2.0-85044729383 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180418

Available from: 2018-04-14 Created: 2018-04-14 Last updated: 2018-04-18Bibliographically approved
Fahlstedt, M., Kleiven, S. & Li, X. (2018). The Influence of the Body on Head Kinematics in Playground Falls for Different Age Groups. In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference: . Paper presented at IRCOBI.
Open this publication in new window or tab >>The Influence of the Body on Head Kinematics in Playground Falls for Different Age Groups
2018 (English)In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference, 2018Conference paper, Published paper (Refereed)
National Category
Other Medical Sciences
Research subject
Applied Medical Technology
Identifiers
urn:nbn:se:kth:diva-248778 (URN)2-s2.0-85061107724 (Scopus ID)
Conference
IRCOBI
Note

QC20190418

Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-04-18
Giordano, C., Zappalà, S. & Kleiven, S. (2017). Anisotropic finite element models for brain injury prediction: the sensitivity of axonal strain to white matter tract inter-subjectvariability. Biomechanics and Modeling in Mechanobiology
Open this publication in new window or tab >>Anisotropic finite element models for brain injury prediction: the sensitivity of axonal strain to white matter tract inter-subjectvariability
2017 (English)In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940Article in journal (Refereed) Published
Abstract [en]

Computational models incorporating anisotropic features of brain tissue have become a valuable tool for studying the occurrence of traumatic brain injury. The tissue deformation in the direction of white matter tracts (axonal strain) was repeatedly shown to be an appropriate mechanical parameter to predict injury. However, when assessing the reliability of axonal strain to predict injury in a population, it is important to consider the predictor sensitivity to the biological inter-subject variability of the human brain. The present study investigated the axonal strain response of 485 white matter subject-specific anisotropic finite element models of the head subjected to the same loading conditions. It was observed that the biological variability affected the orientation of the preferential directions (coefficient of variation of 39.41% for the elevation angle—coefficient of variation of 29.31% for the azimuth angle) and the determination of the mechanical fiber alignment parameter in the model (gray matter volume 55.55–70.75%). The magnitude of the maximum axonal strain showed coefficients of variation of 11.91%. On the contrary, the localization of the maximum axonal strain was consistent: the peak of strain was typically located in a 2 cm3 volume of the brain. For a sport concussive event, the predictor was capable of discerning between non-injurious and concussed populations in several areas of the brain. It was concluded that, despite its sensitivity to biological variability, axonal strain is an appropriate mechanical parameter to predict traumatic brain injury.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Axonal strain; Brain anisotropy; Finite element analysis; Traumatic brain injury
National Category
Engineering and Technology
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-207792 (URN)10.1007/s10237-017-0887-5 (DOI)000405489600012 ()2-s2.0-85013659547 (Scopus ID)
Note

QC 20170529

Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2017-08-08Bibliographically approved
Cui, Z. Y., Famaey, N., Depreitere, B., Ivens, J., Kleiven, S. & Vander Sloten, J. (2017). On the assessment of bridging vein rupture associated acute subdural hematoma through finite element analysis. Computer Methods in Biomechanics and Biomedical Engineering, 20(5), 530-539
Open this publication in new window or tab >>On the assessment of bridging vein rupture associated acute subdural hematoma through finite element analysis
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2017 (English)In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 20, no 5, p. 530-539Article in journal (Refereed) Published
Abstract [en]

Acute subdural hematoma (ASDH) is a type of intracranial haemorrhage following head impact, with high mortality rates. Bridging vein (BV) rupture is a major cause of ASDH, which is why a biofidelic representation of BVs in finite element (FE) head models is essential for the successful prediction of ASDH. We investigated the mechanical behavior of BVs in the KTH FE head model. First, a sensitivity study quantified the effect of loading conditions and mechanical properties on BV strain. It was found that the peak rotational velocity and acceleration and pulse duration have a pronounced effect on the BV strains. Both Young's modulus and diameter are also negatively correlated with the BV strains. A normalized multiple linear regression model using Young's modulus, outer diameter and peak rotational velocity to predict the BV strain yields an adjusted -value of 0.81. Secondly, cadaver head impact experiments were simulated with varying sets of mechanical properties, upon which the amount of successful BV rupture predictions was evaluated. The success rate fluctuated between 67 and 75%. To further increase the predictive capability of FE head models w.r.t. BV rupture, future work should be directed towards improvement of the BV representation, both geometrically and mechanically.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
Bridging veins, acute subdural hematoma, mechanical properties, finite element modelling, head impact
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-205436 (URN)10.1080/10255842.2016.1255942 (DOI)000395351500008 ()27838925 (PubMedID)2-s2.0-84994896188 (Scopus ID)
Note

QC 20170522

Available from: 2017-05-22 Created: 2017-05-22 Last updated: 2017-05-22Bibliographically approved
Giordano, C., Li, X. & Kleiven, S. (2017). Performances of the PIPER scalable child human body model in accident reconstruction. PLoS ONE, 12(11), Article ID e0187916.
Open this publication in new window or tab >>Performances of the PIPER scalable child human body model in accident reconstruction
2017 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 11, article id e0187916Article in journal (Refereed) Published
Abstract [en]

Human body models (HBMs) have the potential to provide significant insights into the pediatric response to impact. This study describes a scalable/posable approach to perform child accident reconstructions using the Position and Personalize Advanced Human Body Models for Injury Prediction (PIPER) scalable child HBM of different ages and in different positions obtained by the PIPER tool. Overall, the PIPER scalable child HBM managed reasonably well to predict the injury severity and location of the children involved in real-life crash scenarios documented in the medical records. The developed methodology and workflow is essential for future work to determine child injury tolerances based on the full Child Advanced Safety Project for European Roads (CASPER) accident reconstruction database. With the workflow presented in this study, the open-source PIPER scalable HBM combined with the PIPER tool is also foreseen to have implications for improved safety designs for a better protection of children in traffic accidents.

Place, publisher, year, edition, pages
Public Library Science, 2017
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:kth:diva-219333 (URN)10.1371/journal.pone.0187916 (DOI)000415121200046 ()2-s2.0-85033796945 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 605544
Note

QC 20171204

Available from: 2017-12-04 Created: 2017-12-04 Last updated: 2017-12-04Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0125-0784

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