Risk of thoracic injury from direct steering wheel impact in frontal crashes

Analysis of Biomechanics of Motor Vehicle Collisions for Passenger Cars: Implications for Passenger Vehicle Safety and Future Car Design Innovations

INTRODUCTION

Investigating biomechanics of injury patterns from motor vehicle collisions (MVCs) informs improvements in vehicle safety. This study aims to investigate two-vehicle MVCs involving a passenger car and specific injury patterns associated with sources of injury, collision biomechanics, vehicle properties, and patient outcomes.

METHODS

Retrospective cohort study conducted to evaluate the biomechanics of specific injury patterns seen in MVCs involving passenger cars using the Crash Injury Research Engineering Network database between the years 2005 and 2015.

RESULTS

A total of 631 MVC cases were included from 2005 to 2015. The majority of cases involved injuries to the head or neck, the thorax, and the abdomen (80.5%). Head/neck injuries from the steering wheel were associated with significantly higher injury severity score compared to those from seatbelts (26.11 versus 18.28, P < 0.001) and airbags (26.11 versus 20.10, P = 0.006), as well as a >6-fold higher fatality rate (P = 0.019). Thoracic injuries caused by the center console were twice as likely to be fatal than those caused by the seatbelt (P = 0.09).

CONCLUSIONS

Occupants suffering injuries to the head/neck, the thorax, and the abdomen had higher injury severity score and fatality rates compared to other body regions, demonstrating that manufacturing and safety guidelines should focus on minimizing these injury patterns. Head/neck injuries caused by the steering wheel were associated with worse outcomes compared to those caused by seatbelts and airbags, further emphasizing the benefits of these critical safety features. Integration of innovative safety features like center-mounted airbags may improve occupant safety.

Non-traumatic ecchymoses: A literature review from a medico-legal perspective

Ecchymosis, as a general term, refers to discoloration of the skin due to the presence of extravasated blood into the dermis and/or subcutaneous tissue. However, it can occasionally be observed without any trauma, as a symptom of disease, a clinical condition, or even during the course of treating a disease. It is extremely important that these non-traumatic lesions are known and recognized and can be distinguished from traumatic ecchymoses by both clinicians and forensic scientists. This review of the literature includes detailed descriptions of non-traumatic periorbital ecchymosis, Slapped Cheek Syndrome, Cullen's Sign, Grey Turner's Sign, Stabler's Sign, Ransohoff Sign, Bryant's Sign, postsacral ecchymosis, perianal ecchymosis, Fox's Sign, other lower leg ecchymosis, and ecchymosis on various body regions. In this article, it is emphasized that failure to correctly identify these findings may subject practitioners to malpractice lawsuits, and failure to correctly identify findings by forensic experts may result in unjust legal judgments against people or loss of rights. It is also this review encourages accurate diagnosis of non-traumatic ecchymoses.

Factors Associated with Cardiac/Pericardial Injury among Blunt Injury Patients: A Nationwide Study in Japan

The lack of established diagnostic criteria makes diagnosing blunt cardiac injury difficult. We investigated the factors associated with blunt cardiac injury using the Japan Trauma Data Bank (JTDB) in a multicenter observational study of blunt trauma patients conducted between 2004 and 2018. The primary outcome was the incidence of blunt cardiac/pericardial injury. Multivariable logistic regression analysis was used to identify factors independently associated with blunt cardiac injuries. Of the 228,513 patients, 1002 (0.4%) had blunt cardiac injury. Hypotension on hospital arrival (adjusted odds ratio (AOR) 4.536, 95% confidence interval (CI) 3.802–5.412), thoracic aortic injury (AOR 2.722, 95% CI 1.947–3.806), pulmonary contusion (AOR 2.532, 95% CI 2.204–2.909), rib fracture (AOR 1.362, 95% CI 1.147–1.618), sternal fracture (AOR 3.319, 95% CI 2.696–4.085). and hemothorax/pneumothorax (AOR 1.689, 95% CI 1.423–2.006)) was positively associated with blunt cardiac injury. Regarding the types of patients, car drivers had a higher rate of blunt cardiac injury compared to other types of patients. Driving a car, hypotension on hospital arrival, thoracic aortic injury, pulmonary contusion, rib fracture, sternal fracture, and hemothorax/pneumothorax were positively associated with blunt cardiac injury.

EFFECT OF STEERING WHEEL HEIGHT AND INCLINATION ANGLE ON BLUNT CARDIAC INJURY DURING THE THORAX-TO-STEERING WHEEL IMPACT

Blunt cardiac injury (BCI) in the traffic accidents usually causes serious consequences like heart failure or even death, and the impact of steering wheel to the thorax is one of the main causes of blunt heart injury. Therefore, more realistic heart models are needed to predict the biomechanical response and related injury of the heart during a thorax-to-steering wheel impact. This study developed three-dimensional finite element (FE) models of lungs, aorta and heart, and validated the models through published cadaver tests by comparing the contact force and intracardiac pressures in four heart chambers. Then, various simulations of thorax-to-steering wheel impact were carried out at different impact heights (lower, middle and higher) and different inclination angles of steering wheel (15∘, 30∘, 45∘ and 60∘) to investigate the effects of impact height and inclination angle on heart injury. The result showed that (1) the biomechanical response of the heart model was agree with the test data; (2) the contact force, myocardial stress and intracardiac pressure were decreased when the inclination angle was increased; (3) when the impact height was middle and the inclination angle of steering wheel was 15∘, the myocardial stress and intracardiac pressure were both maximum which indicated that the blunt heart injury was more likely to occur in this condition.

Blunt trauma related chest wall and pulmonary injuries: An overview

Physical traumas are tragic and multifaceted injuries that suddenly threaten life. Although it is the third most common cause of death in all age groups, one out of four trauma patients die due to thoracic injury or its complications. Blunt injuries constitute the majority of chest trauma. This indicates the importance of chest trauma among all traumas. Blunt chest trauma is usually caused by motor vehicle accident, falling from height, blunt instrument injury and physical assault. As a result of chest trauma, many injuries may occur, such as pulmonary injuries, and these require urgent intervention. Chest wall and pulmonary injuries range from rib fractures to flail chest, pneumothorax to hemothorax and pulmonary contusion to tracheobronchial injuries. Following these injuries, patients may present with a simple dyspnea or even respiratory arrest. For such patient, it is important to understand the treatment logic and to take a multidisciplinary approach to treat the pulmonary and chest wall injuries. This is because only 10% of thoracic trauma patients require surgical operation and the remaining 90% can be treated with simple methods such as appropriate airway, oxygen support, maneuvers, volume support and tube thoracostomy. Adequate pain control in chest trauma is sometimes the most basic and best treatment. With definite diagnosis, the morbidity and mortality can be significantly reduced by simple treatment methods.

Pattern Recognition: A Mechanism-based Approach to Injury Detection after Motor Vehicle Collisions

Motor vehicle collisions cause substantial mortality, morbidity, and expense worldwide. Certain types of injuries are more likely to result from frontal versus side-impact collisions, and knowledge of these specific patterns and why they occur aids in accurate and efficient diagnosis of traumatic injuries. Although the proper use of seat belts decreases crash-related mortality during frontal impact, certain injury patterns to the torso are directly attributed to restraint use. The spectrum of seat belt-related injuries ranges from mild skin and soft-tissue contusions to traumatic bowel injuries and unstable spine injuries that require surgery. Impact with the steering wheel or windshield during a frontal crash can cause characteristic injuries to the head, neck, torso, and distal upper extremity. Steering wheel deformity is an independent predictor of serious thoracic and abdominal injury among front-seat passengers. Impact of a flexed knee with the dashboard during a frontal collision can cause knee, thigh, and hip injuries. Distal lower extremity injuries are encountered frequently when the floorboard is driven into the foot. Lateral impact crashes often result in traumatic brain, thoracic, abdominal, and pelvic injuries, which are more often fatal to occupants on the side of the impact. The specific mechanism-based injury patterns are reviewed to establish a structured systematic search pattern that enables the radiologist to identify traumatic injuries with greater accuracy and speed, thereby improving the care of patients who experience acute trauma. ^©RSNA, 2019 See discussion on this article by Ballard and Mellnick .

Design and Evaluation of a Surface Electromyography-Controlled Steering Assistance Interface

Millions of drivers could experience shoulder muscle overload when rapidly rotating steering wheels and reduced steering ability at increased steering wheel angles. In order to address these issues for drivers with disability, surface electromyography (sEMG) sensors measuring biceps brachii muscle activity were incorporated into a steering assistance system for remote steering wheel rotation. The path-following accuracy of the sEMG interface with respect to a game steering wheel was evaluated through driving simulator trials. Human participants executed U-turns with differing radii of curvature. For a radius of curvature equal to the minimum vehicle turning radius of 3.6 m, the sEMG interface had significantly greater accuracy than the game steering wheel, with intertrial median lateral errors of 0.5 m and 1.2 m, respectively. For a U-turn with a radius of 7.2 m, the sEMG interface and game steering wheel were comparable in accuracy, with respective intertrial median lateral errors of 1.6 m and 1.4 m. The findings of this study could be utilized to realize accurate sEMG-controlled automobile steering for persons with disability.

Risk factors affecting injury severity determined by the MAIS score

OBJECTIVE

Traffic crashes result in a loss of life but also impact the quality of life and productivity of crash survivors. Given the importance of traffic crash outcomes, the issue has received attention from researchers and practitioners as well as government institutions, such as the European Commission (EC). Thus, to obtain detailed information on the injury type and severity of crash victims, hospital data have been proposed for use alongside police crash records. A new injury severity classification based on hospital data, called the maximum abbreviated injury scale (MAIS), was developed and recently adopted by the EC. This study provides an in-depth analysis of the factors that affect injury severity as classified by the MAIS score.

METHOD

In this study, the MAIS score was derived from the International Classification of Diseases. The European Union adopted an MAIS score equal to or greater than 3 as the definition for a serious traffic crash injury. Gains are expected from using both police and hospital data because the injury severities of the victims are detailed by medical staff and the characteristics of the crash and the site of its occurrence are also provided. The data were obtained by linking police and hospital data sets from the Porto metropolitan area of Portugal over a 6-year period (2006-2011). A mixed logit model was used to understand the factors that contribute to the injury severity of traffic victims and to explore the impact of these factors on injury severity. A random parameter approach offers methodological flexibility to capture individual-specific heterogeneity. Additionally, to understand the importance of using a reliable injury severity scale, we compared MAIS with length of hospital stay (LHS), a classification used by several countries, including Portugal, to officially report injury severity. To do so, the same statistical technique was applied using the same variables to analyze their impact on the injury severity classified according to LHS.

RESULTS

This study showed the impact of variables, such as the presence of blood alcohol, the use of protection devices, the type of crash, and the site characteristics, on the injury severity classified according to the MAIS score. Additionally, the sex and age of the victims were analyzed as risk factors, showing that elderly and male road users are highly associated with MAIS 3+ injuries. The comparison between the marginal effects of the variables estimated by the MAIS and LHS models showed significant differences. In addition to the differences in the magnitude of impact of each variable, we found that the impact of the road environment variable was dependent on the injury severity classification.

CONCLUSIONS

The differences in the effects of risk factors between the classifications highlight the importance of using a reliable classification of injury severity. Additionally, the relationship between LHS and MAIS levels is quite different among countries, supporting the previous conclusion that bias is expected in the assessment of risk factors if an injury severity classification other than MAIS is used.

Injury mitigation estimates for an intersection driver assistance system in straight crossing path crashes in the United States

OBJECTIVE

Accounting for one fifth of all crashes and one sixth of all fatal crashes in the United States, intersection crashes are among the most frequent and fatal crash modes. Intersection advanced driver assistance systems (I-ADAS) are emerging vehicle-based active safety systems that aim to help drivers safely navigate intersections. The objective of this study was to estimate the number of crashes and number of vehicles with a seriously injured driver (Maximum Abbreviated Injury Scale [MAIS] 3+) that could be prevented or reduced if, for every straight crossing path (SCP) intersection crash, one of the vehicles had been equipped with an I-ADAS.

METHODS

This study retrospectively simulated 448 U.S. SCP crashes as if one of the vehicles had been equipped with I-ADAS. Crashes were reconstructed to determine the path and speeds traveled by the vehicles. Cases were then simulated with I-ADAS. A total of 30 variations of I-ADAS were considered in this study. These variations consisted of 5 separate activation timing thresholds, 3 separate computational latency times, and 2 different I-ADAS response modalities (i.e., a warning or autonomous braking). The likelihood of a serious driver injury was computed for every vehicle in every crash using impact delta-V. The results were then compiled across all crashes in order to estimate system effectiveness.

RESULTS

The model predicted that an I-ADAS that delivers an alert to the driver has the potential to prevent 0-23% of SCP crashes and 0-25% of vehicles with a seriously injured driver. Conversely, an I-ADAS that autonomously brakes was found to have the potential to prevent 25-59% of crashes and 38-79% of vehicles with a seriously injured driver. I-ADAS effectiveness is a strong function of design. Increasing computational latency time from 0 to 0.5 s was found to reduce crash and injury prevention estimates by approximately one third. For an I-ADAS that delivers an alert, crash/injury prevention effectiveness was found to be very sensitive to changes in activation timing (warning delivered 1.0 to 3.0 s prior to impact). If autonomous braking was used, system effectiveness was found to largely plateau for activation timings greater than 1.5 s prior to impact. In general, the results of this study suggest that I-ADAS will be 2-3 times more effective if an autonomous braking system is utilized over a warning-based system.

CONCLUSIONS

This study highlights the potential effectiveness of I-ADAS in the U.S. vehicle fleet, while also indicating the sensitivity of system effectiveness to design specifications. The results of this study should be considered by designers of I-ADAS and evaluators of this technology considering a future I-ADAS safety test.

Paired vehicle occupant analysis indicates age and crash severity moderate likelihood of higher severity injury in second row seated adults in frontal crashes

The majority of advances in occupant protection systems for motor vehicle occupants have focused on occupants seated in the front row of the vehicle. Recent studies suggest that these systems have resulted in lower injury risk for front row occupants as compared to those in the second row. However, these findings are not universal. In addition, some of these findings result from analyses that compare groups of front and second row occupants exposed to dissimilar crash conditions, raising questions regarding whether they might reflect differences in the crash rather than the front and second row restraint systems. The current study examines factors associated with injury risk for pairs of right front seat and second row occupants in frontal crashes in the United States using paired data analysis techniques. These data indicate that the occupant seated in the front row frequently experiences the more severe injury in the pair, however there were no significant differences in the rate of occurrence of these events and events where the more severe injury occurs in the second row occupant of the pair. A logistic regression indicated that the likelihood of the more severe injury occurring in the second row seated occupant of the pair increased as crash severity increased, consistent with data from anatomic test dummy (ATD) tests. It also indicated that the second row occupant was more likely to have the more severe injury in the pair if that occupant was the older occupant of the pair. These findings suggest that occupant protection systems which focus on providing protection specifically for injuries experienced by older occupants in the second row in higher severity crash conditions might provide the greatest benefit.

Finite element comparison of human and Hybrid III responses in a frontal impact

The improvement of finite element (FE) Human Body Models (HBMs) has made them valuable tools for investigating restraint interactions compared to anthropomorphic test devices (ATDs). The objective of this study was to evaluate the effect of various combinations of safety restraint systems on the sensitivity of thoracic injury criteria using matched ATD and Human Body Model (HBM) simulations at two crash severities. A total of seven (7) variables were investigated: 3-point belt with two (2) load limits, frontal airbag, knee bolster airbag, a buckle pretensioner, and two (2) delta-v's - 40kph and 50kph. Twenty four (24) simulations were conducted for the Hybrid III ATD FE model and repeated with a validated HBM for 48 total simulations. Metrics tested in these conditions included sternum deflection, chest acceleration, chest excursion, Viscous Criteria (V*C) criteria, pelvis acceleration, pelvis excursion, and femur forces. Additionally, chest band deflection and rib strain distribution were measured in the HBM for additional restraint condition discrimination. The addition of a frontal airbag had the largest effect on the occupant chest metrics with an increase in chest compression and acceleration but a decrease in excursion. While the THUMS and Hybrid III occupants demonstrated the same trend in the chest compression measurements, there were conflicting results in the V*C, acceleration, and displacement metrics. Similarly, the knee bolster airbag had the largest effect on the pelvis with a decrease in acceleration and excursion. With a knee bolster airbag the simulated occupants gave conflicting results, the THUMS had a decrease in femur force and the ATD had an increase. Preferential use of dummies or HBM's is not debated; however, this study highlights the ability of HBM metrics to capture additional chest response metrics.