The influence of seat back rake on ligament loadings in rear-end impact

Golinski, W Z; Gentle, R

doi:10.1243/095440705x6541

Cited by 6 publications

(5 citation statements)

References 24 publications

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“…The authors justified this decision on the basis that the magnitude of gravity is small compared to the loading magnitude and therefore the gravitational effects are negligible (Brolin et al 2005;Panzer 2006;van der Horst 2002). Still others failed to report whether gravity was included in their simulations (Deng and Goldsmith 1987;Golinski and Gentle 2005;Lee et al 2004;Meyer et al 2004;Stemper et al 2004). A select few studies reported determining gravitational stabilization muscle activation schemes that were initiated before simulation loading (Brelin-Fornari et al 2005;Chancey et al 2003;Deng and Fu 2002;Östh et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Dibb¹,

Cox²,

Nightingale³

et al. 2013

Traffic Injury Prevention

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Objective: During dynamic injury scenarios, such as motor vehicle crashes, neck biomechanics contribute to head excursion and acceleration, influencing head injuries. One important tool in understanding head and neck dynamics is computational modeling. However, realistic and stable muscle activations for major muscles are required to realize meaningful kinematic responses. The objective was to determine cervical muscle activation states for 6-year-old, 10-year-old, and adult 50th percentile male computational head and neck models. Currently, pediatric models including muscle activations are unable to maintain the head in an equilibrium position, forcing models to begin from nonphysiologic conditions. Recent work has realized a stationary initial geometry and cervical muscle activations by first optimizing responses against gravity. Accordingly, our goal was to apply these methods to Duke University's head-neck model validated using living muscle response and pediatric cadaveric data.Methods: Activation schemes maintaining an upright, stable head for 22 muscle pairs were found using LS-OPT. Two optimization problems were investigated: a relaxed state, which minimized muscle fatigue, and a tensed activation state, which maximized total muscle force. The model's biofidelity was evaluated by the kinematic response to gravitational and frontal impact loading conditions. Model sensitivity and uncertainty analyses were performed to assess important parameters for pediatric muscle response. Sensitivity analysis was conducted using multiple activation time histories. These included constant activations and an optimal muscle activation time history, which varied the activation level of flexor and extensor groups, and activation initiation and termination times.Results: Relaxed muscle activations decreased with increasing age, maintaining upright posture primarily through extensor activation. Tensed musculature maintained upright posture through coactivation of flexors and extensors, producing up to 32 times the force of the relaxed state. Without muscle activation, the models fell into flexion due to gravitational loading. Relaxed musculature produced 28.6-35.8 N of force to the head, whereas tensed musculature produced 450-1023 N. Pediatric model stiffnesses were most sensitive to muscle physiological cross-sectional area.Conclusions: Though muscular loads were not large enough to cause vertebral compressive failure, they would provide a prestressed state that could protect the vertebrae during tensile loading but might exacerbate risk during compressive loading. For example, in the 10-year-old, a load of 602 N was produced, though estimated compressive failure tolerance is only 2.8 kN. Including muscles and time-variant activation schemes is vital for producing biofidelic models because both vary by age. The pediatric activations developed represent physiologically appropriate sets of initial conditions and are based on validated adult cadaveric data.

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Section: Introductionmentioning

confidence: 99%

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Dibb¹,

Cox²,

Nightingale³

et al. 2013

Traffic Injury Prevention

View full text Add to dashboard Cite

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“…The rate of rotation was consistent between all simulations and maximum rotation magnitude was achieved in 300 ms. This rotation rate was similar to a previous computational modeling study [10]. Caudal vertebral segments were allowed to adjust for the remaining time until application of the simulated rear impact.…”

Section: Methodsmentioning

confidence: 99%

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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“…Neck injury mechanisms have been the subject of research for many years. Typically two methods, multibody dynamics (MBD) 23–30 and finite element methods (FEM) 31–39 are being used to study human spine and soft tissues injury mechanisms in order to have a better understanding of the kinetics, kinematics, and clinical aspects.…”

Section: Introductionmentioning

confidence: 99%

An investigation into neck injuries in simulated frontal impacts

Alshammari

Neal-Sturgess

2012

Proceedings of the Institution of Mechanical Engineers, Part K:

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Spinal injury is one of the most debilitating and costly injuries. It is a devastating condition that disrupts the life of the injured and their families. Vehicle crashes are the most common cause of fractures, soft tissue injuries and dislocations of the neck and cervical spine. Among vehicle crashes frontal impacts are the most frequent cause for head and neck injuries. Neck injuries are often caused due to unusual head motion. Improvement of the knowledge of the correlation between crash dynamics, human body behaviour and internal neck phenomena could contribute to the development of new protection systems for the neck. The most acceptable way to study the behaviour of the human body and internal interactions during car crashes is mathematical modeling as it is non-invasive and repeatable. In this work, computer simulations have been performed using a multibody dynamic model of the cervical and thoracic-lumbar spine, where rigid bodies are connected by articulated joints and spring-damper elements. The models were developed using the ‘Working Model 2D’ and were used to simulate frontal impacts in vehicles. The models were validated based on experimental data available in literature. The verified models were used to analyse the behaviour of the driver and vehicle kinematics and calculate the internal neck forces and motion. Principle virtual power of neck was applied at inter-vertebral levels for various impact speeds. Principle virtual power of neck was then correlated with real world crash data of neck injuries. It has been shown that principle virtual power of neck at each intervertebral level correlates well with the crash data and can be used as a predictor of neck injuries.

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The influence of seat back rake on ligament loadings in rear-end impact

Cited by 6 publications

References 24 publications

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

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

An investigation into neck injuries in simulated frontal impacts

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