Search Results

Over the past decade, there has been an increase in awareness and concern about the occurrence and long-term effects of concussions. Traumatic brain injury (TBI)-related emergency department (ED) visits associated with motor vehicle collisions, including patients with a diagnosis of concussion or mild TBI (mTBI), have increased while deaths and hospital admissions related to TBI have decreased. The diagnostic criteria for concussion have evolved and broadened, and based on current assessments and diagnostic imaging techniques, there are often no objective findings, yet a diagnosis of concussion may still be rendered. Clinical assessment of concussion may be based only on patient-reported symptoms and history, making it difficult to objectively relate the reported increase in TBI-related ED visits due to motor vehicle collisions to specific collision parameters.

SAE J211 provides no definitive specification as to the appropriate procedures for filtering angular rate sensor data prior to differentiation into angular acceleration data, especially for impact data. Accordingly, a 3-2-2-2 array (nine-accelerometer-package or NAP) of linear accelerometers and a triaxial angular rate sensor were mounted into a Hybrid III 50th-percentile-male ATD headform and compared in a variety of impact events and multibody simulations. Appropriate low-pass digital filter cutoff frequencies for differentiating the angular rate sensor data into angular accelerations were sought via residual analysis in accordance with current SAE J211 guidelines.

Few studies have investigated pediatric head injury mechanics with subjects below the age of 8 years. This paper presents non-injurious head accelerations during various activities for young children (2 to 7 years old). Eight males and five females aged 2-7 years old were equipped with a head sensor package and head kinematics were measured while performing a series of playground-type activities. The maximum peak resultant accelerations were 29.5 G and 2745 rad/s2. The range of peak accelerations was 2.7 G to 29.5 G. The range of peak angular velocities was 4.2 rad/s to 22.4 rad/s. The range of peak angular accelerations was 174 rad/s2 to 2745 rad/s2. Mean peak resultant values across all participants and activities were 13.8 G (range 2.4 G to 13.8 G), 12.8 rad/s (range 4.0 rad/s to 12.8 rad/s), and 1375 rad/s2 (range 105 rad/s2 to 1375 rad/s2) for linear acceleration, angular velocity, and angular acceleration, respectively.

Neck injury assessment reference values (IARVs) and tolerance values for children have been specified using animal data compared to the loading of anthropomorphic test devices (ATDs). However, there is a paucity of data regarding the neck loads generated during non-injurious situations for children. Six males and six females aged 8-11 years old were equipped with a validated head sensor package and upper neck loads and moments were calculated from measured head kinematics while performing a series of playground-type activities. The maximum forces were 686 N in compression, 177 N in tension, and 471 N in shear, the maximum moments were 18.2 N-m in flexion, 6.0 N-m in extension, 6.4 N-m in lateral bending, and 12.1 N-m in axial twist. Female subjects exhibited similar loads and moments to their male counterparts, but larger Nij values. The peak loads measured in this study are larger than or comparable to those undertaken with adult subjects participating in similar activities.

Approximately 600,000 fatalities occur each year as a result of pedestrians being impacted by motor vehicles (World Bank, 2008). Previous studies (Heller et al., 2009) have utilized databases such as the National Inpatient Sample (NIS) to gain a more thorough understanding of the common injury patterns that occur in real-world traffic collisions involving pedestrians in the United States. The NIS contains records on five to eight million hospital stays annually and provides a wealth of information regarding injuries to hospitalized pedestrian casualties in the U.S. Because of the large number of applicable records in the NIS and the randomized sampling procedure, the data can be used to complete analyses that are not possible with smaller databases such as the Pedestrian Crash Data Study (PCDS), which is not intended to be statistically representative of pedestrian crashes in general.

A 3-2-2-2 array of linear accelerometers and a combination of a triaxial linear accelerometer and a triaxial angular rate sensor were mounted into a Hybrid III 50th percentile male ATD head-form and compared in a variety of short- and long-duration events. An appropriate low-pass filter cutoff frequency for differentiating the angular rate sensor data into angular accelerations was found by using a residual analysis to find individual cutoff frequencies for the three center of mass (COM) linear accelerometer channels and the three angular rate sensor channels and taking the arithmetic mean of the six cutoffs. The angular rate sensors provide more accurate rotational rates than integrated angular accelerations calculated from arrays of linear accelerometers and are less cumbersome, especially for events lasting longer than 200 ms.

Over half of the 1.2 million annual traffic fatalities worldwide are pedestrians struck by motor vehicles [ 1 ]. Medical databases, such as the National Inpatient Sample (NIS), have been utilized to ascertain injury patterns in the general population of injured pedestrians [ 2 - 3 ]. However, the authors are not aware of any studies investigating how factors, such as physical impairments, intoxication, and pre-existing medical implants (e.g. hip replacement, artificial knee, etc.) affect the prevalence of pedestrian accidents or injury outcomes. Five to eight million inpatient hospitalization records are included in the NIS annually, and this large sample size allows for analyses that are not possible with smaller data sets on pedestrian injuries. The current study utilizes the NIS to evaluate how several factors such as blindness, deafness, intoxication, and pre-existing medical implants affect injury patterns when compared to the general population of hospitalized pedestrians.

While adult head injuries have been studied over the past six decades, few studies have investigated pediatric head injury mechanics. This paper presents non-injurious head accelerations during various activities in a pediatric population. Six males and six females aged 8–11 years old were equipped with a validated head sensor package and head kinematics were measured while performing a series of playground-type activities. Maximum resultant values across all participants and activities were 25.7 g (range 3.0 g to 25.7 g), 16.0 rad/s (range 10.4 rad/s to 16.0 rad/s), and 1705 rad/s2 (range 520 rad/s2 to 1705 rad/s2) for linear acceleration, angular velocity, and angular acceleration, respectively. Mean maximum resultant values across all participants and activities were 9.7 g (range 2.1 g to 9.7 g) and 734 rad/s2 (range 188 rad/s2 to 734 rad/s2) for linear and angular acceleration, respectively.

For over 30 years, there has been a safety standard in the United States that governs the design and performance of child restraint systems, and since 1981 this standard has prescribed dynamic test requirements for the performance of child restraint systems (CRS) in frontal collisions. However, this standard does not include a dynamic test specifically designed to evaluate the performance of CRSs during side impact collisions. One of the reasons a side impact standard has not been implemented is that feasible countermeasures have not been identified. This study addresses this issue by evaluating the effectiveness of padding as a countermeasure in side impact collisions. Head acceleration data were collected during both drop testing and side impact sled testing with and without the use of energy absorbing padding in the CRS side wing.

Each year, over half of the world's 1.17 million fatalities resulting from traffic collisions are pedestrians (World Bank, 2008). Mitigation of such fatalities and serious injuries requires a thorough understanding of the common injury mechanisms that occur in pedestrian impacts. Studying the frequency of injury to each body region and how injury patterns are related may provide additional insight into pedestrian injury mechanisms, which could be used to develop additional prevention strategies. There is a wealth of information regarding pedestrian collisions within national databases that have not been extensively used to investigate these issues to date. This paper presents a review of selected databases that contain information regarding injuries to pedestrians who have been involved in a motor vehicle collision, including the strengths and weaknesses of each in performing this type of analysis.

This study integrates data from multiple sources to obtain a more complete understanding of inertially-induced pediatric cervical spine injury risk and the role of impact severity and restraint type. Data from previously conducted frontal crash and sled tests using a variety of anthropomorphic test devices (ATDs) in various restraint configurations were compiled and compared to injury assessment reference values (IARVs). The data show that neck loads in frontal collisions increase with increasing delta-V. At high delta-Vs, the neck loads correspond to a relatively high risk of neck injury regardless of restraint configuration. Pediatric inertial cervical spine injury risk in frontal collisions is governed primarily by the energy involved in the collision.

There is a paucity of data regarding the potential for pediatric cervical spine injury as a result of acceleration of the head with no direct impact during automotive crashes. Sled tests were conducted using a 3-year-old anthropomorphic test device (ATD) to investigate the effect of restraint type and crash severity on the risk of pediatric inertial neck injury. At higher crash severities, the ATD restrained by only the vehicle three-point restraints sustained higher peak neck tension, peak neck extension and flexion moments, neck injury criterion (Nij) values, peak head accelerations, and HIC values compared to using a forward-facing child restraint system (CRS). The injury assessment reference values (IARVs) for peak tension and Nij were exceeded in all 48 and 64 kph delta-V tests using any restraint type.

No regional or directional large-deformation constitutive data for brain exist in the current literature. To address this deficiency, the large strain (up to 50%) directional properties of gray and white matter were determined in the thalamus, corona radiata, and corpus callosum. The constitutive relationships of all regions and directions are well fit by an Ogden hyperelastic relationship, modified to include dissipation. The material parameter α, representing the non-linearity of the tissue, was not significantly sensitive to region, direction, or species. The average value of the material parameter µ, corresponding to the shear modulus of the tissue, was significantly different for each region, demonstrating that brain tissue is inhomogeneous. In each region, µ, obtained in 2 orthogonal directions, was compared. Consistent with local neuroarchitecture, gray matter showed the least amount of anisotropy and corpus callosum exhibited the greatest degree of anisotropy.