Head/Neck Kinematic Response of Human Subjects in Low-Speed Rear-End Collisions

Siegmund, Gunter P.; King, David J.; Lawrence, Jonathan M.; Wheeler, Jeffrey B.; Brault, John R.; Smith, Teresa

doi:10.4271/973341

Cited by 79 publications

(39 citation statements)

References 17 publications

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“…The motion of the head relative to the head restraint may be affected by seated height in relation to the head restraint geometry. It has been reported that females have a somewhat different dynamic response in rear volunteer tests, such as greater head forward acceleration, greater (or similar) T1 forward acceleration, lower (or similar) Neck Injury Criterion (NIC) values, and a more pronounced rebound than males (Carlsson et al 2011(Carlsson et al , 2012Croft et al 2002;Hell et al 1999;Linder et al 2008;Mordaka and Gentle 2003;Ono et al 2006;Schick et al 2008;Siegmund et al 1997;Szabo et al 1994;Viano 2003;Welcher and Szabo 2001).…”

Section: Introductionmentioning

confidence: 95%

Anthropometric Specifications, Development, and Evaluation of EvaRID—A 50th Percentile Female Rear Impact Finite Element Dummy Model

Carlsson

Chang²,

Lemmen³

et al. 2014

Traffic Injury Prevention

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The EvaRID dummy model demonstrated the potential of becoming a valuable tool when evaluating and developing seats and whiplash protection systems. However, updates of the joint stiffness will be required to provide better correlation at lower load levels. Moreover, the seated posture, curvature of the spine, and head position of 50th percentile female occupants needs to be established and implemented in future models.

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Section: Introductionmentioning

confidence: 95%

Anthropometric Specifications, Development, and Evaluation of EvaRID—A 50th Percentile Female Rear Impact Finite Element Dummy Model

Carlsson

Chang²,

Lemmen³

et al. 2014

Traffic Injury Prevention

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“…Two biomechanical studies that incorporated human volunteers demonstrated increased head-neck motions in females. 76,106 Van den Kroonenberg and colleagues 106 reported significantly increased head horizontal accelerations in females and an inverse correlation between peak head horizontal accelerations and neck circumference, highlighting a link between morphology and biomechanics. Stemper and colleagues 90 incorporated head-neck preparations from postmortem human subjects to demonstrate greater segmental flexion/extension and facet joint motions in female specimens, indicating greater soft tissue strains and an associated increased risk of injury.…”

Section: Occupant Kinematics During Rear Impactmentioning

confidence: 99%

Whiplash-Associated Disorders: Occupant Kinematics and Neck Morphology

Stemper¹,

Corner²

2016

J Orthop Sports Phys Ther

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FIGURE 1.Initial phases of head-neck response to automotive rear impacts. The rear impact initiates with the occupant in a neutral upright position. As the thorax is accelerated anteriorly, the head remains stationary during the retraction phase, producing an S-shaped cervical spine curvature. Eventually, loads from the thorax are transferred up the cervical spine and the head-neck complex transitions into extension, with the cervical spine in an overall C-shaped extension curvature. The head eventually rebounds forward (not shown), and the cervical spine then transitions into flexion. Used with permission from Stemper et al. 93 Copyright ©2011 Wiley-Liss, Inc. foam/springs and rearward deflection, which absorb energy and decrease impact severity for the occupant. The magnitude of seatback deformation and deflection is dependent on the occupant's torso mass and center of gravity. Greater mass and higher center of gravity contribute to greater deflection and decreased overall impact severity. Average female body mass is 20% lighter and torso height is 8% shorter. 30,31 Therefore, the ability to deflect the seatback is decreased in females, who would experience more severe loading on the head-neck complex during a given rear impact.This section highlighted the role of body size on cervical spine injury risk during automotive rear impacts, advancing the theory that size-based mismatches between the vehicle seat and occupant anthropometrics contribute to greater injury risk for smaller occupants. This concept would hold true for either males or females, but may help explain the preponderance of whiplash injuries in females due to their generally smaller body size. Shorter sitting height can result in head interaction with the bottom of the head restraint, which increases injury risk. However, taller occupants with incorrectly adjusted head restraints also experience increased injury risk due to the head rotating over the head restraint and increasing extension moments on the cervical spine. Decreased body mass and shorter center-of-torso mass in smaller occupants also contribute to decreased dynamic energy absorption of the seatback. While these differences illustrate mechanisms of increased injury risk for smaller occupants, other morphological differences may also contribute. Differences in Head and Neck MorphologyGiven that a majority of injuries resulting from automotive rear impacts affect the cervical spine, 9 differences in headneck morphology can influence injury risk. Once again, sex-based differences will be used to demonstrate this concept. Neck slenderness, a mechanical term body sizes farther from those standards may not be protected as well.Research studies report that head-tohead restraint backset is lower in females than in males due to rearward incline of automotive seats and decreased sitting height for average females compared to males.12 Sitting height for average females is approximately 6 cm shorter than that for average males. 30,31 This means that the posterior aspect of the head for the comp...

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“…For example, cervical spinal segmental and facet joint kinematics were shown to be significantly greater in female intact head-neck PMHS during simulated rear impacts [42,43]. Non-physiological head-neck kinematics were also shown to be greater in female volunteers following simulated rear impacts, although this metric is less specific to the injury mechanism [38,51]. Likewise, head-neck and spinal kinematics were shown to be decreased in occupants aware of the impending impact during human volunteer and computational modeling studies [24,39,40].…”

Section: Introductionmentioning

confidence: 86%

Axial head rotation increases facet joint capsular ligament strains in automotive rear impact

Storvik

Stemper

2010

Med Biol Eng Comput

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Axial head rotation prior to low speed automotive rear impacts has been clinically identified to increase morbidity and symptom duration. The present study was conducted to determine the effect of axial head rotation on facet joint capsule strains during simulated rear impacts. The study was conducted using a validated intact head to first thoracic vertebra (T1) computational model. Parametric analysis was used to assess effects of increasing axial head rotation between 0 and 60° and increasing impact severity between 8 and 24 km/h on facet joint capsule strains. Rear impacts were simulated by horizontally accelerating the T1 vertebra. Characteristics of the acceleration pulse were based on the horizontal T1 acceleration pulse from a series of simulated rear impact experiments using full-body post mortem human subjects. Joint capsule strain magnitudes were greatest in ipsilateral facet joints for all simulations incorporating axial head rotation (i.e., head rotation to the left caused higher ligament strain at the left facet joint capsule). Strain magnitudes increased by 47-196% in simulations with 60° head rotation compared to forward facing simulations. These findings indicate that axial head rotation prior to rear impact increases the risk of facet joint injury.

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Head/Neck Kinematic Response of Human Subjects in Low-Speed Rear-End Collisions

Cited by 79 publications

References 17 publications

Anthropometric Specifications, Development, and Evaluation of EvaRID—A 50th Percentile Female Rear Impact Finite Element Dummy Model

Anthropometric Specifications, Development, and Evaluation of EvaRID—A 50th Percentile Female Rear Impact Finite Element Dummy Model

Whiplash-Associated Disorders: Occupant Kinematics and Neck Morphology

Axial head rotation increases facet joint capsular ligament strains in automotive rear impact

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