Does spinal alignment influence car occupant responses? -The influence of variation in whole spinal alignment patterns on vertebral kinematics under rear impact conditions-
Doktorsavhandling, 2019

The susceptibility of women to Whiplash Associated Disorders (WADs) has been the focus of numerous epidemiologic studies. Summarising the epidemiologic WAD studies, women were found to be subject to up to three times higher risk of sustaining WADs than men. To improve occupant safety for both men and women, the overall aim of this thesis was to provide fundamental knowledge to understand how gender differences influence the injury mechanisms and risk of sustaining WADs. WADs are generally considered to be derived from cervical soft tissue damage caused by excessive cervical vertebral kinematics. This thesis has focused on the whole spinal alignment in automotive seated postures as one of the gender differences, and investigated its potential impact on cervical vertebral kinematics during a rear impact, clarifying gender specific dynamic characteristics of cervical vertebral kinematics.
Previous rear impact sled test series comprising female and male volunteers were reanalysed to determine the dynamic characteristics of inertia-induced cervical vertebral kinematics during rear impacts. For spinal alignment, image data of the spinal column in automotive seated postures, acquired with an upright open Magnetic Resonance Imaging (MRI) system, were analysed. Typical patterns of the whole spinal alignment, including average gender specific spinal alignment patterns, were obtained through Multi-Dimensional Scaling (MDS). Implementing these typical spinal alignment patterns in a whole-body occupant FE model, the potential impact of whole spinal alignment on cervical vertebral kinematicswere investigated in reconstruction simulations of previous rear impact sled tests.
In the sled tests, the female subjects were subjected to a more pronounced cervical S-shape than the male subjects, beyond the voluntary muscle-induced cervical kinematics range for female subjects. The average gender specific spinal alignment patterns of the automotive seated posture included a slight kyphotic, or almost straight cervical spine, with a less-kyphotic thoracic spine for the female subjects, and a lordotic cervical spine with a more pronounced kyphotic thoracic spine for the male subjects. In the reconstructed simulations, the average female spinal alignment pattern demonstrated greater intervertebral displacements from the lower cervical spine to the upper thoracic spine with a more pronounced cervical S-shape, compared to the average male spinal alignment pattern. Greater elongation of the cervical ligaments occurred at intervertebral levels where greater intervertebral displacement was found.
Rear impact reconstruction simulations performed in this thesis demonstrated a potential impact of gender differences in whole spinal alignment on cervical vertebral kinematics and ligament elongation. The female spinal alignment trend may make women exposed to more significant deformation of the cervical soft tissues due to greater cervical vertebral kinematics during a rear impact. The findings may partially contribute to a greater understanding of the increased injury risk of women sustaining WADs.

neck injury

rear impact

whiplash

occupant

female

cervical vertebral kinematics

MRI

Multi-Dimensional Scaling

automotive seated posture

spinal alignment

Alfa, Saga, Hörselgången 4, Gothenburg
Opponent: Professor Duane Cronin, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Canada

Författare

Fusako Sato Sakayachi

Chalmers, Mekanik och maritima vetenskaper, Fordonssäkerhet

Dynamic Cervical Vertebral Motion of Female and Male Volunteers and Analysis of its Interaction with Head/Neck/Torso Behavior during Low‐Speed Rear Impact

International Research Council on the Biomechanics of Injury Conference, IRCOBI 2014; Berlin; Germany; 10 September 2014 through 12 September 2014,; (2014)p. 227-249

Paper i proceeding

Investigation of Whole Spine Alignment Patterns in Automotive Seated Posture Using Upright Open MRI Systems

2016 International Research Council on the Biomechanics of Injury, IRCOBI 2016, Malaga, Spain, 14-16 September 2016,; (2016)p. 113-130

Paper i proceeding

The effect of seatback inclination on spinal alignment in automotive seated postures

Effects of whole spine alignment patterns on neck responses in rear end impact

Traffic Injury Prevention,; Vol. 18(2017)p. 199-206

Artikel i vetenskaplig tidskrift

Whiplash Associated Disorders (WADs), broadly known as whiplash injuries, are the most common injuries associated with motor vehicle crashes. Over the past few decades, the susceptibility of women sustaining WADs have been the focus of numerous injury statistical studies. According to these studies,women are subject to up to a three times higher risk of sustaining WADs compared to men. WADs can occur in all impact directions, although they are sustained more frequently in rear impacts, than in any other type of automobile impact. Even in similar crash situations, women are more likely to be vulnerable to WADs than men.Having sustained a WAD, gender is a notablefactor of the recovery time, whereby the recovery time for women is more likely to be longer compared to men. To improve occupant safety for women as well as men, the overall aim of this thesis was to provide fundamental knowledge to answer the following question: Why do women have a higher risk of sustaining WADs?
WADs are generally considered to be derived from damage to the cervical soft tissues caused by excessive cervical vertebral kinematics during vehicle crashes. Greater cervical vertebral kinematics might induce harmful local deformation in the cervical soft tissues. Gender-dependent anatomical differences, e.g., anthropometrical dimensions of the neck, geometrical dimensions of cervical vertebrae, etc., have been considered the possible causes of the difference in cervical vertebral kinematics between men and women. In order to understand how such gender differences influence the risk of sustaining WADs, this thesis has focused on the whole spinal alignment in automotive seated postures as one of the gender anatomical differences, and investigated its potential impact on cervical vertebral kinematics and cervical soft tissues during a rear impact.
Rear impact reconstruction simulations performed in this thesis demonstrate that the average female spinal alignment pattern is subject to greater cervical vertebral kinematics with greater cervical soft tissue elongations. The findings contribute to elevating our knowledge of the increased injury risk of women sustaining WADs.

Styrkeområden

Transport

Livsvetenskaper och teknik

Ämneskategorier

Farkostteknik

ISBN

978-91-7597-860-4

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4541

Utgivare

Chalmers tekniska högskola

Alfa, Saga, Hörselgången 4, Gothenburg

Opponent: Professor Duane Cronin, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Canada

Mer information

Senast uppdaterat

2019-02-12