Development of a finite element biomechanical whole spine model for analyzing lumbar spine loads under caudocephalad acceleration.

Spine injury risk due to military conflict is an ongoing concern among defense organizations throughout the world. A better understanding of spine biomechanics could assist in developing protection devices to reduce injuries caused by caudocephalad acceleration (+Gz) in under-body blasts (UBB). Although some finite element (FE) human models have demonstrated reasonable lumbar spine biofidelity, they were either partial spine models or not validated for UBB-type loading modes at the lumbar functional spinal unit (FSU) level, thus limiting their ability to analyze UBB-associated occupant kinematics.

Occupant kinematics and biomechanics during frontal collision in autonomous vehicles-can rotatable seat provides additional protection?

In a highly autonomous vehicle (HAV), the rotatable seat is likely to be designed to facilitate ease of communication between the occupants. We hypothesize that the protective effects of current restraint systems vary among different seating configurations and that by using the rotational seat to alter the occupant's orientation in accordance with the direction of impact, occupants will be better protected. Moreover, in HAVs, it's likely that an imminent impact could be detected at a time of 200 ms, or even longer, prior to the initial contact.

Porcine growth plate experimental study and estimation of human pediatric growth plate properties.

Growth plate (GP) is a type of tissue widely found in child's immature skeleton. It may have significant influence on the overall injury pattern since it has distinguishing mechanical properties compared to the surrounding bony tissue. For more accurate material modeling and advanced pediatric human body modeling, it is imperative to investigate the material property of GPs in different loading conditions.

An Experimental and Numerical Study of Hybrid III Dummy Response to Simulated Underbody Blast Impacts.

Anthropometric test devices (ATDs) such as the Hybrid III dummy have been widely used in automotive crash tests to evaluate the risks of injury at different body regions. In recent years, researchers have started using automotive ATDs to study the high-speed vertical loading response caused by underbody blast impacts. This study analyzed the Hybrid III dummy responses to short-duration, large magnitude vertical accelerations in a laboratory setup.

The Role of Neck Muscle Activities on the Risk of Mild Traumatic Brain Injury in American Football.

Concussion, or mild traumatic brain injury (mTBI), is frequently associated with sports activities. It has generally been accepted that neck strengthening exercises are effective as a preventive strategy for reducing sports-related concussion risks. However, the interpretation of the link between neck strength and concussion risks remains unclear.

Computational Study of Fracture Characteristics in Infant Skulls Using a Simplified Finite Element Model.

Skull fracture characteristics are associated with loading conditions (such as the impact point and impact velocity) and could provide indication of abuse or accident-induced head injuries. However, correlations between fracture characteristics and loading conditions in infant and toddler are ill-understood. A simplified computational model representing an infant head was built to simulate skull responses to blunt impacts.

Numerical simulations of the 10-year-old head response in drop impacts and compression tests.

Background And Objective: Studies on traumatic injuries of children indicate that impact to the head is a major cause of severe injury and high mortality. However, regulatory and ethical concerns very much limit development and validation of computer models representing the pediatric head. The purpose of this study was to develop a child head finite element model with high-biofidelity to be used for studying pediatric head injury mechanisms.

Testing and Modeling the Responses of Hybrid III Crash-Dummy Lower Extremity under High-speed Vertical Loading.

Anthropometric test devices (ATDs), such as the Hybrid III crash-test dummy, have been used to simulate lowerextremity responses to military personnel subjected to loading conditions from anti-vehicular (AV) landmine blasts. Numerical simulations [e.g.

Characterization of Human Rib Biomechanical Responses due to Three-Point Bending.

In the elderly population, rib fracture is one of the most common injuries sustained in motor vehicle crashes. The current study was conducted to predict the biomechanical fracture responses of ribs with respect to age, gender, height, weight and percentage of ash content. Three-point bending experiments were conducted on 278 isolated rib samples extracted from 82 cadaver specimens (53 males and 29 females between the ages of 21 and 87 years) for 6th and 7th levels of ribs.

Vehicular Causation Factors and Conceptual Design Modifications to Reduce Aortic Strain in Numerically Reconstructed Real World Nearside Lateral Automotive Crashes.

Aortic injury (AI) leading to disruption of the aorta is an uncommon but highly lethal consequence of trauma in modern society. Most recent estimates range from 7,500 to 8,000 cases per year from a variety of causes. It is observed that more than 80% of occupants who suffer an aortic injury die at the scene due to exsanguination into the chest cavity.

Parametric analysis of the biomechanical response of head subjected to the primary blast loading--a data mining approach.

Traumatic brain injury due to primary blast loading has become a signature injury in recent military conflicts and terrorist activities. Extensive experimental and computational investigations have been conducted to study the interrelationships between intracranial pressure response and intrinsic or 'input' parameters such as the head geometry and loading conditions. However, these relationships are very complicated and are usually implicit and 'hidden' in a large amount of simulation/test data.

Nodal versus Total Axonal Strain and the Role of Cholesterol in Traumatic Brain Injury.

Traumatic brain injury (TBI) is a health threat that affects every year millions of people involved in motor vehicle and sporting accidents, and thousands of soldiers in battlefields. Diffuse axonal injury (DAI) is one of the most frequent types of TBI leading to death. In DAI, the initial traumatic event is followed by a cascade of biochemical changes that take time to develop in full, so that symptoms may not become apparent until days or weeks after the original injury.

Development of a new biomechanical indicator for primary blast-induced brain injury.

Primary blast-induced traumatic brain injury (bTBI) has been observed at the boundary of brain tissue and cerebrospinal fluid (CSF). Such injury can hardly be explained by using the theory of compressive wave propagation, since both the solid and fuid materials have similar compressibility and thus the intracranial pressure (ICP) has a continuous distribution across the boundary. Since they have completely different shear properties, it is hypothesized the injury at the interface is caused by shear wave.

Computational Modeling of Traffic Related Thoracic Injury of a 10-Year-Old Child Using Subject-Specific Modeling Technique.

Traffic injuries have become a major health-related issue to school-aged children. To study this type of injury with numerical simulations, a finite element model was developed to represent the full body of a 10-year-old (YO) child. The model has been validated against test data at both body-part and full-body levels in previous studies.

A biomechanical study of standard posterior pelvic ring fixation versus a posterior pedicle screw construct.

Objectives: The purpose of this study was to biomechanically test a percutaneous pedicle screw construct for posterior pelvic stabilisation and compare it to standard fixation modalities.

Methods: Utilizing a sacral fracture and sacroiliac (SI) joint disruption model, we tested 4 constructs in single-leg stance: an S1 sacroiliac screw, S1 and S2 screws, the pedicle screw construct, and the pedicle screw construct+S1 screw. We recorded displacement at the pubic symphysis and SI joint using high-speed video.

Biomechanical sex differences of crewmembers during a simulated space capsule landing.

Introduction: The objective of this study was to observe the differences in the biodynamic responses of male and female crewmembers during a simulated Soyuz spacecraft (short-duration flights) impact landing.

Methods: There were 16 volunteers (8 men and 8 women) recruited to sit in a pseudo-supine position and be exposed to several impact acceleration pulses. The acceleration peaks ranged from 7.

Investigation of pediatric neck response and muscle activation in low-speed frontal impacts.

Pediatric necks present different responses and injury patterns compared with those of adults in motor vehicle crashes (MVCs). To evaluate the effect of different muscle modeling methodologies, three muscle models were developed and simulated under low-speed frontal impact conditions with an average peak acceleration of 3g's. The muscle activation curve for the curve-guided model, the muscle segment was curved using guiding nodes, was further optimized based on experimental data.

Development of a 10-year-old full body geometric dataset for computational modeling.

The objective of this study was to create a computer-aided design (CAD) geometric dataset of a 10-year-old (10 YO) child. The study includes two phases of efforts. At Phase One, the 10 YO whole body CAD was developed from component computed tomography and magnetic resonance imaging scans of 12 pediatric subjects.

Application of an anatomically-detailed finite element thorax model to investigate pediatric cardiopulmonary resuscitation techniques on hard bed.

Objectives: Improved Cardiopulmonary Resuscitation (CPR) approaches will largely benefit the children in need. The constant peak displacement and constant peak force loading methods were analyzed on hard bed for pediatric CPR by an anatomically-detailed 10 year-old (YO) child thorax finite element (FE) model. The chest compression and rib injury risk were studied for children with various levels of thorax stiffness.

A modified controlled cortical impact technique to model mild traumatic brain injury mechanics in mice.

For the past 25 years, controlled cortical impact (CCI) has been a useful tool in traumatic brain injury (TBI) research, creating injury patterns that includes primary contusion, neuronal loss, and traumatic axonal damage. However, when CCI was first developed, very little was known on the underlying biomechanics of mild TBI. This paper uses information generated from recent computational models of mild TBI in humans to alter CCI and better reflect the biomechanical conditions of mild TBI.

A theoretical analysis of stress wave propagation in the head under primary blast loading.

Traumatic brain injury due to primary blast loading has become a signature injury in recent military conflicts. Efforts have been made to study the stress wave propagation in the head. However, the relationship of incident pressure, reflected pressure and intracranial pressure is still not clear, and the experimental findings reported in the literature are contradictory.

Dynamic changes of macaque cancellous bone following head-down bed rest.

Introduction: Skeletal unloading during a spaceflight could result in bone loss and osteopenia, ultimately leading to poor bone strength. The purpose of the present study was to investigate the influence of bone loss on the dynamic behavior of cancellous bone.

Methods: Microgravity-induced bone loss and osteopenia were simulated in a macaque head-down bed rest (HDBR) model, in which 20 macaques were laid on a bed tilted by -6 degrees from the horizontal.

Effect of vehicle front end profiles leading to pedestrian secondary head impact to ground.

Most studies of pedestrian injuries focus on reducing traumatic injuries due to the primary impact between the vehicle and the pedestrian. However, based on the Pedestrian Crash Data Study (PCDS), some researchers concluded that one of the leading causes of head injury for pedestrian crashes can be attributed to the secondary impact, defined as the impact of the pedestrian with the ground after the primary impact of the pedestrian with the vehicle. The purpose of this study is to understand if different vehicle front-end profiles can affect the risk of pedestrian secondary head impact with the ground and thus help in reducing the risk of head injury during secondary head impact with ground.

Constitutive modeling of pia-arachnoid complex.

The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain during impact or inertial loading. Recent studies have revealed the complicated material behavior of the PAC. In this study, the nonlinear viscoelastic, transversely isotropic material properties of the PAC were modeled as Mooney-Rivlin ground substance with collagen fibers strengthening within the meningeal plane through an exponential model.

A comprehensive experimental study on material properties of human brain tissue.

A comprehensive study on the biomechanical response of human brain tissue is necessary to investigate traumatic brain injury mechanisms. Published brain material property studies have been mostly performed under a specific type of loading, which is insufficient to develop accurate brain tissue constitutive equations. In addition, inconsistent or contradictory data in the literature made it impossible for computational model developers to create a single brain material model that can fit most, if not all, experimental results.