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Publications (10 of 20) Show all publications
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
Robinson, Y., Lison Almkvist, V., Olerud, C., Halldin, P. & Fahlstedt, M. (2018). Finite Element Analysis of Long Posterior Transpedicular Instrumentation for Cervicothoracic Fractures Related to Ankylosing Spondylitis. Global Spine Journal
Open this publication in new window or tab >>Finite Element Analysis of Long Posterior Transpedicular Instrumentation for Cervicothoracic Fractures Related to Ankylosing Spondylitis
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2018 (English)In: Global Spine Journal, ISSN 2192-5682, E-ISSN 2192-5690Article in journal (Refereed) Published
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-226880 (URN)000457230900005 ()2-s2.0-85053528044 (Scopus ID)
Note

QC 20180515

Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2019-02-18Bibliographically approved
Halldin, P. & Fahlstedt, M. (2018). How sensitive are different headform design parameters in oblique helmeted impacts?. In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference: . Paper presented at IRCOBI.
Open this publication in new window or tab >>How sensitive are different headform design parameters in oblique helmeted impacts?
2018 (English)In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference, 2018Conference paper, Published paper (Refereed)
National Category
Other Medical Sciences
Identifiers
urn:nbn:se:kth:diva-248779 (URN)2-s2.0-85061102416 (Scopus ID)
Conference
IRCOBI
Note

QC20190418

Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-04-18Bibliographically approved
Panzer, M. B., Giudice, J. S., Caudillo, A., Mukherjee, S., Kong, K., Cronin, D. S., . . . Brown, P. (2018). NUMERICAL CROWDSOURCING OF NFL FOOTBALL HELMETS. Paper presented at 3rd Joint Symposium of the International-and-National-Neurotrauma-Societies-and-AANS/CNS-Section on Neurotrauma and Critical Care, AUG 11-16, 2018, Toronto, CANADA. Journal of Neurotrauma, 35(16), A148-A148
Open this publication in new window or tab >>NUMERICAL CROWDSOURCING OF NFL FOOTBALL HELMETS
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2018 (English)In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 35, no 16, p. A148-A148Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Mary Ann Liebert, 2018
Keywords
Biomechanics, Computational / Modeling, Concussion / mTBI
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:kth:diva-234624 (URN)000441527400400 ()
Conference
3rd Joint Symposium of the International-and-National-Neurotrauma-Societies-and-AANS/CNS-Section on Neurotrauma and Critical Care, AUG 11-16, 2018, Toronto, CANADA
Note

QC 20180913

Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2019-08-20Bibliographically approved
Meng, S., Fahlstedt, M. & Halldin, P. (2018). The effect of impact velocity angle on helmeted head impact severity: A rationale for motorcycle helmet impact test design. 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. 454-469). International Research Council on the Biomechanics of Injury
Open this publication in new window or tab >>The effect of impact velocity angle on helmeted head impact severity: A rationale for motorcycle helmet impact test design
2018 (English)In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2018, p. 454-469Conference paper, Published paper (Refereed)
Abstract [en]

The impact velocity angle determined by the normal and tangential velocity has been shown to be an important description of head impact conditions but can vary in real-world accidents. The objective of this paper was to investigate the effect of impact velocity angle on helmeted head impact severity indicated by the brain tissue strain. The human body model coupled with a validated motorcycle helmet model was propelled at a constant resultant velocity but varying angle relative to a rigid surface. Different body angles, impact directions and helmet designs have also been incorporated in the simulation matrix (n=300). The results show an influence of impact velocity angle on brain tissue strain response. By aggregating all simulation cases into different impact velocity angle groups, i.e., 15, 30, 45, 60 and 75 degrees, a 30- or 45-degree angle group give the highest median and inter-quartile range of the peak brain tissue strain. Comparisons of strain pattern and its peak value between individual cases give consistent results. The brain tissue strain is less sensitive to the body angle than to the velocity angle. The study suggests that UN/ECE 22.05 can be improved by increasing the current 'oblique' angle, i.e. 15 degrees inclined to vertical axis, to a level that can produce sufficient normal velocity component and hence angular head motion. This study also underline the importance of understanding post-impact head kinematics, and the need for further evaluation of human body models.

Place, publisher, year, edition, pages
International Research Council on the Biomechanics of Injury, 2018
Keywords
finite element method, Head impact conditions, Impact severity, Motorcycle helmet, Test method
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:kth:diva-246506 (URN)2-s2.0-85061089583 (Scopus ID)
Conference
2018 International Research Council on the Biomechanics of Injury, IRCOBI 2018, 12 September 2018 through 14 September 2018
Note

QC 20190329

Available from: 2019-03-29 Created: 2019-03-29 Last updated: 2019-03-29Bibliographically 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

QC 20190418

Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-06-17Bibliographically approved
Fahlstedt, M., Halldin, P. & Kleiven, S. (2016). Comparison of multibody and finite element human body models in pedestrian accidents with the focus on head kinematics.. Traffic Injury Prevention, 17(3)
Open this publication in new window or tab >>Comparison of multibody and finite element human body models in pedestrian accidents with the focus on head kinematics.
2016 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 17, no 3Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: The objective of this study was to compare and evaluate the difference in head kinematics between the TNO and THUMS models in pedestrian accident situations.

METHODS: The TNO pedestrian model (version 7.4.2) and the THUMS pedestrian model (version 1.4) were compared in one experiment setup and 14 different accident scenarios where the vehicle velocity, leg posture, pedestrian velocity, and pedestrian's initial orientation were altered. In all simulations, the pedestrian model was impacted by a sedan. The head trajectory, head rotation, and head impact velocity were compared, as was the trend when various different parameters were altered.

RESULTS: The multibody model had a larger head wrap-around distance for all accident scenarios. The maximum differences of the head's center of gravity between the models in the global x-, y-, and z-directions at impact were 13.9, 5.8, and 5.6 cm, respectively. The maximum difference between the models in head rotation around the head's inferior-superior axis at head impact was 36°. The head impact velocity differed up to 2.4 m/s between the models. The 2 models showed similar trends for the head trajectory when the various parameters were altered.

CONCLUSIONS: There are differences in kinematics between the THUMS and TNO pedestrian models. However, these model differences are of the same magnitude as those induced by other uncertainties in the accident reconstructions, such as initial leg posture and pedestrian velocity.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keywords
finite element; accident reconstruction; multibody; head injuries; pedestrian
National Category
Health Sciences
Identifiers
urn:nbn:se:kth:diva-186232 (URN)10.1080/15389588.2015.1067803 (DOI)000372360200016 ()26218752 (PubMedID)2-s2.0-84961217239 (Scopus ID)
Note

QC 20170123

Available from: 2016-12-19 Created: 2016-05-06 Last updated: 2017-11-29Bibliographically approved
Fahlstedt, M., Halldin, P. & Kleiven, S. (2016). The protective effect of a helmet in three bicycle accidents: A finite element study. Accident Analysis and Prevention, 91, 135-143
Open this publication in new window or tab >>The protective effect of a helmet in three bicycle accidents: A finite element study
2016 (English)In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 91, p. 135-143Article in journal (Refereed) Published
Abstract [en]

There is some controversy regarding the effectiveness of helmets in preventing head injuries among cyclists. Epidemiological, experimental and computer simulation studies have suggested that helmets do indeed have a protective effect, whereas other studies based on epidemiological data have argued that there is no evidence that the helmet protects the brain. The objective of this study was to evaluate the protective effect of a helmet in single bicycle accident reconstructions using detailed finite element simulations. Strain in the brain tissue, which is associated with brain injuries, was reduced by up to 43% for the accident cases studied when a helmet was included. This resulted in a reduction of the risk of concussion of up to 54%. The stress to the skull bone went from fracture level of 80 MPa down to 13-16 MPa when a helmet was included and the skull fracture risk was reduced by up to 98% based on linear acceleration. Even with a 10% increased riding velocity for the helmeted impacts, to take into account possible increased risk taking, the risk of concussion was still reduced by up to 46% when compared with the unhelmeted impacts with original velocity. The results of this study show that the brain injury risk and risk of skull fracture could have been reduced in these three cases if a helmet had been worn.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Accident reconstruction, Bicycle, Finite element analysis, Head injuries, Helmet, Injury prevention
National Category
Health Sciences
Identifiers
urn:nbn:se:kth:diva-186933 (URN)10.1016/j.aap.2016.02.025 (DOI)000375162900015 ()2-s2.0-84960439409 (Scopus ID)
Note

QC 20160518

Available from: 2016-05-18 Created: 2016-05-16 Last updated: 2017-11-30Bibliographically approved
Pedersen, K., Fahlstedt, M., Jacobsson, A., Kleiven, S. & von Holst, H. (2015). A National Survey of Traumatic Brain Injuries Admitted to Hospital in Sweden from 1987 to 2010. Neuroepidemiology
Open this publication in new window or tab >>A National Survey of Traumatic Brain Injuries Admitted to Hospital in Sweden from 1987 to 2010
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2015 (English)In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208Article in journal (Refereed) Accepted
National Category
Other Medical Sciences
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-164082 (URN)
Funder
VINNOVA, IHF 2013-05118
Note

QP 201504

Available from: 2015-04-13 Created: 2015-04-13 Last updated: 2017-12-04Bibliographically approved
Pedersen, K., Fahlstedt, M., Jacobsson, A., Kleiven, S. & von Holst, H. (2015). A National Survey of Traumatic Brain Injuries Admitted to Hospitals in Sweden from 1987 to 2010. Neuroepidemiology, 45(1), 20-27
Open this publication in new window or tab >>A National Survey of Traumatic Brain Injuries Admitted to Hospitals in Sweden from 1987 to 2010
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2015 (English)In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208, Vol. 45, no 1, p. 20-27Article in journal (Refereed) Published
Abstract [en]

Background: With an increasing and aging population, there is a global demand for improving the primary prevention strategies aimed at reducing traumatic brain injuries (TBIs). The objective of the present epidemiological study was to evaluate the pattern of TBI in Sweden over a 24 years period (1987-2010). Methods: The Swedish Hospital Discharge Register was used, where in-patient care with a main diagnosis of TBI according to ICD9/10 was included. External factors, age and gender distribution was evaluated. Results: A decreasing number of annual incidence was observed, that is, from 230 to 156 per 100,000 inhabitants. A steady decrease of concussion was observed while other intracranial injuries increased especially traumatic subdural hemorrhage and subarachnoid hemorrhage. The study identified 3 groups of patients young, adults and elderly. The highest incidence and the largest increase of incidence were seen in the oldest age group (85+ years) while the population under 65 years had a decreasing incidence of TBI. The most frequent etiology was fall accidents (57%) with a relative constant trend over the study period. Conclusions: More effort should be focused on different strategies for different age groups, especially the elderly group. A well-planned strategy for primary prevention guidelines for different age groups will have the chance to further reduce not only the health-care costs but also complications among elderly care. (C) 2015 S. Karger AG, Basel

Keywords
Traumatic brain injury, Epidemiology, Age, Gender, Primary prevention
National Category
Production Engineering, Human Work Science and Ergonomics Neurology
Identifiers
urn:nbn:se:kth:diva-173454 (URN)10.1159/000381780 (DOI)000359881800003 ()26201267 (PubMedID)2-s2.0-84937800540 (Scopus ID)
Note

QC 20150915

Available from: 2015-09-15 Created: 2015-09-11 Last updated: 2017-12-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0980-4051

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