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Effect of Pediatric Growth on Cervical Spine Injury Risk in Automotive Crashes
KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.ORCID iD: 0000-0001-7908-6270
KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.ORCID iD: 0000-0003-0125-0784
(English)Manuscript (preprint) (Other academic)
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 decreases 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.

Keywords [en]
Finite element model, Pediatric Growth, Automotive crash, Cervical spine, Injury risk
National Category
Other Medical Engineering
Research subject
Applied Medical Technology
Identifiers
URN: urn:nbn:se:kth:diva-215644OAI: oai:DiVA.org:kth-215644DiVA, id: diva2:1148601
Projects
PIPER
Funder
EU, FP7, Seventh Framework Programme, 605544
Note

QC 20171012

Available from: 2017-10-11 Created: 2017-10-11 Last updated: 2017-10-12Bibliographically approved
In thesis
1. Understanding Boundary Conditions for Brain Injury Prediction: Finite Element Analysis of Vulnerable Road Users
Open this publication in new window or tab >>Understanding Boundary Conditions for Brain Injury Prediction: Finite Element Analysis of Vulnerable Road Users
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Vulnerable road users (VRUs) are overrepresented in the statistics on severe and deadly injuries in traffic accidents, most commonly involving the head. The finite element (FE) method presents the possibility to model complex interactions between the human body and vehicles in order to better understand the injury mechanisms. While the rapid development of computer capacity has allowed for increasingly detailed FE-models, there is always a benefit of reducing the studied problem. Due to its material properties, the brain is more sensitive to rotational motion than to purely linear, resulting in complex injury causation. When studying brain injuries caused by a direct impact to the head, simulations using an isolated head model significantly increases efficiency compared to using a complete human body model. Also evaluation of head protective systems uses isolated mechanical head representations. It is not, however, established the extent to which the boundary conditions of the head determine the outcome of brain injuries.

FE models of both the entire human body and the isolated head were used in this thesis to study the effect of the body, as well as active neck muscle tension, on brain injury outcome in VRU accidents. A pediatric neck model was also developed to enable the study of age-specific effects. A vehicle windscreen model was developed to evaluate the necessity of capturing the failure deformation during pedestrian head impacts.

It was shown that the influence of the neck and body on brain injury prediction is greater in longer duration impacts, such as pedestrian head-to-windscreen impacts with an average difference of 21%. In accidents with shorter duration impacts, such as head-to-ground bicycle accidents, the average influence was between 3-12%. The influence did not consistently increase or limit the severity, and was dependent on the degree of rotation induced by the impact, as well as the mode of deformation induced in the neck. It was also shown that the predicted brain injury severity is dependent on capturing the large deformations of fractured windscreen, with the greatest effect near the windscreen frame. The pediatric neck model showed a large effect of age-dependent anatomical changes on inertial head loading, making it a promising tool to study the age-dependent effects in VRU accidents.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. p. 83
Series
TRITA-STH : report, ISSN 1653-3836 ; 2017:11
Keywords
Brain injuries; Vulnerable Road Users; windscreen impacts; Finite Element Analysis; pedestrian accidents; cycling accidents; pediatric neck
National Category
Other Medical Engineering
Research subject
Applied Medical Technology
Identifiers
urn:nbn:se:kth:diva-215643 (URN)978-91-7729-568-6 (ISBN)
Public defence
2017-11-06, T2, Hälsovägen 11C, Huddinge, 10:00 (English)
Opponent
Supervisors
Note

QC 20171013

Available from: 2017-10-13 Created: 2017-10-12 Last updated: 2017-10-16Bibliographically approved

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