Cluster analysis of seriously injured occupants in motor vehicle crashes.

Permanent monitoring of real-world crashes is important to identify injury patterns and injury mechanisms that still occur in the field despite existing regulations and consumer testing programs. This study investigates current injury patterns at the MAIS 3+ level in the accident environment without limiting the impact direction. The approach consisted of applying unsupervised clustering algorithms to NASS-CDS crash data in order to classify seriously injured, belted occupants into clusters based on injured body regions, biomechanical characteristics and crash severity. Injury patterns in each cluster were analyzed and associated with other characteristics of the crash, such as the collision configuration. The groups of seriously injured occupants found in this research contain a large amount of information and research possibilities. The resulting clusters represent new opportunities for vehicle safety, which have been highlighted in this study.

Biomechanical response of the human clavicle: the effects of loading direction on bending properties.

The purpose of this study was to determine the influence of loading direction on the structural response of the human clavicle subjected to three-point bending. A total of 20 clavicles were obtained from 10 unembalmed fresh-frozen postmortem human subjects ranging from 45 to 92 years of age. The right and left clavicles from each subject were randomly divided into two test groups. One group was impacted at 0 degrees from the transverse plane, and the second group was impacted at 45 degrees angle from the transverse plane. There was no statistically significant difference in peak force (p = .22), peak moment (p = .30), or peak displacement (p = .44) between specimens impacted at 0 degrees versus 45 degrees from the transverse plane. However, there was a significant difference in the structural stiffness (p = .01) and peak strain (p < .01) between specimens impacted at 0 degrees versus 45 degrees from the transverse plane. The peak strain, however, must be evaluated with caution because of the variation in fracture location relative to the strain gauge. Due to the controlled matched data set, the differences in the structural stiffness with respect to loading direction can be attributed to the complex geometry of the clavicle and not material differences.

Characterization of crash-induced thoracic loading resulting in pulmonary contusion.

BACKGROUND: Pulmonary contusion (PC) is commonly sustained in motor vehicle crash. This study utilizes the Crash Injury Research and Engineering Network (CIREN) database and vehicle crash tests to characterize the occupants and loading characteristics associated with PC. A technique to match CIREN cases to vehicle crash tests is applied to quantify the thoracic loading associated with this injury. METHODS: The CIREN database and crash test data from the National Highway Traffic Safety Administration were used in this study. An analysis of CIREN data were conducted between three study cohorts: patients that sustained PC and any other chest injury (PC+ and chest+), patients with chest injury and an absence of PC (PC- and chest+), and a control group without chest injury and an absence of PC (PC- and chest-). Forty-one lateral impact crash tests were analyzed and thoracic loading data from onboard crash tests dummies were collected. RESULTS: The incidence of PC in CIREN data were 21.7%. Crashes resulting in PC demonstrated significantly greater mortality (23.9%) and Injury Severity Score (33.1 +/- 15.7) than the control group. The portion of lateral impacts increased from 27% to 48% between the control group and PC+ and chest+ cohort, prompting the use of lateral impact crash tests for the case-matching portion of the study. Crash tests were analyzed in two configurations; vehicle-to-vehicle tests and vehicle-to-pole tests. The average maximum chest compression and deflection velocity from the dummy occupants were found to be 25.3% +/- 2.6% and 4.6 m/s +/- 0.42 m/s for the vehicle-to-pole tests and 23.0% +/- 4.8% and 3.9 m/s +/- 1.1 m/s for the vehicle-to-vehicle tests. Chest deflection versus time followed a roughly symmetric and sinusoidal profile. Sixteen CIREN cases were identified that matched the vehicle crash tests. Of the 16 matched cases, 12 (75%) sustained chest injuries, with half of these patients presenting with PC. CONCLUSIONS: Quantified loading at the chest wall indicative of PC and chest injury in motor vehicle crash is valuable boundary condition data for bench-top studies or computer simulations focused on this injury. In addition, because PC often exhibits a delayed onset, knowing the population and crash modes highly associated with this injury may promote earlier detection and improved management of this injury.

A population-based comparison of CIREN and NASS cases using similarity scoring.

The Crash Injury Research and Engineering Network (CIREN) provides significant details on injuries, and data on patient outcomes that is unavailable in the National Automotive Sampling System (NASS). However, CIREN cases are selected from specific Level I trauma centers with different inclusion criteria than those used for NASS, and the assertion that a given case is similar to the population of NASS cases is often made qualitatively. A robust, quantitative method is needed to compare CIREN to weighted NASS populations. This would greatly improve the usefulness and applicability of research conducted with data from the CIREN database. Our objective is to outline and demonstrate the utility of such a system to compare CIREN and NASS cases. This study applies the Mahalanobis distance metric methodology to determine similarity between CIREN and NASS/CDS cases. The Mahalanobis distance method is a multivariate technique for population comparison. Independent variables considered were total delta V, age, weight, height, maximum AIS, ISS, model year, gender, maximum intrusion, number of lower and upper extremity injuries, and number of head and chest injuries. The technique provides a unit-independent quantitative score which can be used to identify similarity of CIREN and NASS cases. Weighted NASS data and CIREN data were obtained for the years 2001-2005. NASS cases with Maximum AIS 3 resulted in a subset of 1,869 NASS cases, and 2,819 CIREN cases.

Numerical simulation of a cellular-level experiment to induce traumatic injury to neurons.

Previous research has developed a pneumatically driven device for delivering a controlled mechanical insult to cultured neurons. The neuronal cell culture was injured by applying a transient air pulse to a culture well fitted with a highly elastic Silastic culture well bottom. In response to the pressure pulse, he Silastic culture well bottom deformed, stretched the attached cell culture, and resulted in observable cell injuries and death. The goal of this paper was to computationally model the spatial distribution of membrane strain, stress, and strain rate to which these cultures were subjected. The simulation results, using a finite element model of the culture well membrane, compared well with the results from the original experiments. When peak air pressure was varied from 69 kPa to 345 kPa (10 to 50 psig), numerical simulations showed that the corresponding membrane strains varied from 20 to 95% and the stress response varied from 0.5 to 1.2 MPa.