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Zhou, Z., Li, X. & Kleiven, S. (2019). Biomechanics of acute subdural hematoma in the elderly: A fluid-structure interaction study. Journal of Neurotrauma, 36(13), 2099-2108
Open this publication in new window or tab >>Biomechanics of acute subdural hematoma in the elderly: A fluid-structure interaction study
2019 (English)In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 36, no 13, p. 2099-2108Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Mary Ann Liebert, 2019
National Category
Medical and Health Sciences Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-243833 (URN)10.1089/neu.2018.6143 (DOI)000473049600431 ()30717617 (PubMedID)2-s2.0-85068219142 (Scopus ID)
Note

QC 20190212

Available from: 2019-02-06 Created: 2019-02-06 Last updated: 2019-08-05Bibliographically approved
Fahlstedt, M., Kleiven, S. & Li, X. (2019). Current Playground Surface Test Standards Underestimate Brain Injury Risk for Children. Journal of Biomechanics
Open this publication in new window or tab >>Current Playground Surface Test Standards Underestimate Brain Injury Risk for Children
2019 (English)In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380Article in journal (Refereed) Published
Abstract [en]

Playgrounds surface test standards have been introduced to reduce the number of fatal and severe injuries. However, these test standards have several simplifications to make it practical, robust and cost-effective, such as the head is represented with a hemisphere, only the linear kinematics is evaluated and the body is excluded. Little is known about how these simplifications may influence the test results. The objective of this study was to evaluate the effect of these simplifications on global head kinematics and head injury prediction for different age groups. The finite element human body model PIPER was used and scaled to seven different age groups from 1.5 up to 18 years old, and each model was impacted at three different playground surface stiffness and three head impact locations. All simulations were performed in pairs, including and excluding the body. Linear kinematics and skull bone stress showed small influence if excluding the body while head angular kinematics and brain tissue strain were underestimated by the same simplification. The predicted performance of the three different playground surface materials, in terms of head angular kinematics and brain tissue strain, was also altered when including the body. A body and biofidelic neck need to be included, together with suitable head angular kinematics based injury thresholds, in future physical or virtual playground surface test standards to better prevent brain injuries.

National Category
Medical Engineering
Identifiers
urn:nbn:se:kth:diva-250703 (URN)10.1016/j.jbiomech.2019.03.038 (DOI)000469156200001 ()2-s2.0-85064461545 (Scopus ID)
Note

QC 20190625

Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-06-25Bibliographically approved
Saeedimasine, M., Montanino, A., Kleiven, S. & Villa, A. (2019). Impact of lipid composition and ion channel on the mechanical behavior of axonal membranes: a molecular simulation study. Paper presented at Joint 12th EBSA European Biophysics Congress / 10th IUPAP International Conference on Biological Physics (ICBP), JUL 20-24, 2019, Madrid, SPAIN. European Biophysics Journal, 48, S99-S99
Open this publication in new window or tab >>Impact of lipid composition and ion channel on the mechanical behavior of axonal membranes: a molecular simulation study
2019 (English)In: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 48, p. S99-S99Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
SPRINGER, 2019
National Category
Biophysics
Identifiers
urn:nbn:se:kth:diva-255420 (URN)000473420400263 ()
Conference
Joint 12th EBSA European Biophysics Congress / 10th IUPAP International Conference on Biological Physics (ICBP), JUL 20-24, 2019, Madrid, SPAIN
Note

QC 20190815

Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2019-08-15Bibliographically approved
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
Montanino, A., Deryckere, A., Famaey, N., Seuntjens, E. & Kleiven, S. (2019). Mechanical characterization of squid giant axon membrane sheath and influence of the collagenous endoneurium on its properties. Scientific Reports, 9(1), Article ID 8969.
Open this publication in new window or tab >>Mechanical characterization of squid giant axon membrane sheath and influence of the collagenous endoneurium on its properties
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 8969Article in journal (Refereed) Published
Abstract [en]

To understand traumas to the nervous system, the relation between mechanical load and functional impairment needs to be explained. Cellular-level computational models are being used to capture the mechanism behind mechanically-induced injuries and possibly predict these events. However, uncertainties in the material properties used in computational models undermine the validity of their predictions. For this reason, in this study the squid giant axon was used as a model to provide a description of the axonal mechanical behavior in a large strain and high strain rate regime (ε=10%,ε⋅=1s−1), which is relevant for injury investigations. More importantly, squid giant axon membrane sheaths were isolated and tested under dynamic uniaxial tension and relaxation. From the lumen outward, the membrane sheath presents: an axolemma, a layer of Schwann cells followed by the basement membrane and a prominent layer of loose connective tissue consisting of fibroblasts and collagen. Our results highlight the load-bearing role of this enwrapping structure and provide a constitutive description that could in turn be used in computational models. Furthermore, tests performed on collagen-depleted membrane sheaths reveal both the substantial contribution of the endoneurium to the total sheath’s response and an interesting increase in material nonlinearity when the collagen in this connective layer is digested. All in all, our results provide useful insights for modelling the axonal mechanical response and in turn will lead to a better understanding of the relationship between mechanical insult and electrophysiological outcome.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Medical Engineering Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-255034 (URN)10.1038/s41598-019-45446-y (DOI)000472137700065 ()2-s2.0-85067621816 (Scopus ID)
Note

QC 20190729

Available from: 2019-07-16 Created: 2019-07-16 Last updated: 2019-07-29
Meng, S., Cernicchi, A., Kleiven, S. & Halldin, P. (2019). The biomechanical differences of shock absorption test methods in the US and European helmet standards. International Journal of Crashworthiness, 24(4), 399-412
Open this publication in new window or tab >>The biomechanical differences of shock absorption test methods in the US and European helmet standards
2019 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 24, no 4, p. 399-412Article in journal (Refereed) Published
Abstract [en]

Nowadays crash helmets are tested by dropping a free or unrestrained headform in Europe but a guided or restrained headform in the United States. It remains unclear whether the free fall and the guided fall produce similar impact kinematics that cause head injury. A ?nite element helmet model is developed and compared with experimental tests. The resulting head kinematics from virtual tests are input for a ?nite element head model to compute the brain tissue strain. The guided fall produces higher peak force and linear acceleration than the free fall. Eccentric impact in the free fall test induces angular head motion which directs some of the impact energy into rotational kinetic energy. Consequently, the brain tissue strain in the free fall test is up to 6.3 times more than that in the guided fall. This study recommends a supplemental procedure that records angular head motion in the free fall test.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2019
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-252954 (URN)10.1080/13588265.2018.1464545 (DOI)000468457900004 ()2-s2.0-85046630058 (Scopus ID)
Note

QC 20190802

Available from: 2019-08-02 Created: 2019-08-02 Last updated: 2019-08-02Bibliographically approved
Kapeliotis, M., Musigazi, G. U., Famaey, N., Depreitere, B., Kleiven, S. & Vander Sloten, J. (2019). The sensitivity to inter-subject variability of the bridging vein entry angles for prediction of acute subdural hematoma. Journal of Biomechanics, 92, 6-10
Open this publication in new window or tab >>The sensitivity to inter-subject variability of the bridging vein entry angles for prediction of acute subdural hematoma
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2019 (English)In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 92, p. 6-10Article in journal (Refereed) Published
Abstract [en]

Acute subdural hematoma (ASDH) is one of the most frequent traumatic brain injuries (TBIs) with high mortality rate. Bridging vein (BV) ruptures is a major cause of ASDH. The KTH finite element head model includes bridging veins to predict acute subdural hematoma due to BV rupture. In this model, BVs were positioned according to Oka et al. (1985). The aim of the current study is to investigate whether the location and entry angles of these BVs could be modelled using data from a greater statistical sample, and what the impact of this improvement would be on the model's predictive capability of BV rupture. From the CT angiogram data of 78 patients, the relative position of the bridging veins and their entry angles along the superior sagittal sinus was determined. The bridging veins were repositioned in the model accordingly. The performance of the model, w.r.t. BV rupture prediction potential was tested on simulations of full body cadaver head impact experiments. The experiments were simulated on the original version of the model and on three other versions which had updated BV positions according to mean, maximum and minimum entry angles. Even though the successful prediction rate between the models stayed the same, the location of the rupture site significantly improved for the model with the mean entry angles. Moreover, the models with maximum and minimum entry angles give an insight of how BV biovariability can influence ASDH. In order to further improve the successful prediction rate, more biofidelic data are needed both with respect to bridging vein material properties and geometry. Furthermore, more experimental data are needed in order to investigate the behaviour of FE head models in depth.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Head impact, Acute subdural hematoma, Bridging vein rupture, CT angiogram, Bridging vein position, Finite element head model
National Category
Biophysics
Identifiers
urn:nbn:se:kth:diva-255748 (URN)10.1016/j.jbiomech.2019.05.016 (DOI)000476965500002 ()31201011 (PubMedID)2-s2.0-85066931524 (Scopus ID)
Note

QC 20190813

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13Bibliographically approved
Zhou, Z., Li, X., Kleiven, S., Shah, C. & Hardy, W. (2018). A reanalysis of experimental brain strain data: implication for finite element head model validation. Stapp Car Crash Journal, 62, 293-318
Open this publication in new window or tab >>A reanalysis of experimental brain strain data: implication for finite element head model validation
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2018 (English)In: Stapp Car Crash Journal, ISSN 1532-8546, Vol. 62, p. 293-318Article in journal (Refereed) Published
Abstract [en]

Relative motion between the brain and skull and brain deformation are biomechanics aspects associated with many types of traumatic brain injury (TBI). Thus far, there is only one experimental endeavor (Hardy et al., 2007) reported brain strain under loading conditions commensurate with levels that were capable of producing injury. Most of the existing finite element (FE) head models are validated against brain-skull relative motion and then used for TBI prediction based on strain metrics. However, the suitability of using a model validated against brain-skull relative motion for strain prediction remains to be determined. To partially address the deficiency of experimental brain deformation data, this study revisits the only existing dynamic experimental brain strain data and updates the original calculations, which reflect incremental strain changes. The brain strain is recomputed by imposing the measured motion of neutral density target (NDT) to the NDT triad model. The revised brain strain and the brain-skull relative motion data are then used to test the hypothesis that an FE head model validated against brainskull relative motion does not guarantee its accuracy in terms of brain strain prediction. To this end, responses of brain strain and brain-skull relative motion of a previously developed FE head model (Kleiven, 2007) are compared with available experimental data. CORrelation and Analysis (CORA) and Normalized Integral Square Error (NISE) are employed to evaluate model validation performance for both brain strain and brain-skull relative motion. Correlation analyses (Pearson coefficient) are conducted between average cluster peak strain and average cluster peak brain-skull relative motion, and also between brain strain validation scores and brain-skull relative motion validation scores. The results show no significant correlations, neither between experimentally acquired peaks nor between computationally determined validation scores. These findings indicate that a head model validated against brain-skull relative motion may not be sufficient to assure its strain prediction accuracy. It is suggested that a FE head model with intended use for strain prediction should be validated against the experimental brain deformation data and not just the brain-skull relative motion.

Place, publisher, year, edition, pages
NLM, 2018
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:kth:diva-242238 (URN)30608998 (PubMedID)2-s2.0-85059498927 (Scopus ID)
Note

QC 20190514

Available from: 2019-01-29 Created: 2019-01-29 Last updated: 2019-05-10Bibliographically approved
Kapeliotis, M., Musigazi, G., Famaey, N., Depreitere, B., Kleiven, S. & Vander Sloten, J. (2018). Assessment of bridging vein rupture associated with acute subdural hematoma through finite elements analysis after biofidelic position adaptation. In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI: . Paper presented at 2018 International Research Council on the Biomechanics of Injury, IRCOBI 2018, 12 September 2018 through 14 September 2018 (pp. 695-696). International Research Council on the Biomechanics of Injury
Open this publication in new window or tab >>Assessment of bridging vein rupture associated with acute subdural hematoma through finite elements analysis after biofidelic position adaptation
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2018 (English)In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2018, p. 695-696Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
International Research Council on the Biomechanics of Injury, 2018
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-247417 (URN)2-s2.0-85061096844 (Scopus ID)
Conference
2018 International Research Council on the Biomechanics of Injury, IRCOBI 2018, 12 September 2018 through 14 September 2018
Note

QC20190502

Available from: 2019-05-02 Created: 2019-05-02 Last updated: 2019-05-02Bibliographically 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
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0125-0784

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