Occupants In Crashes Research Articles

Effect of ESC (electronic stability control) on tree and pole impacts with focus on rear impacts

ObjectiveThe effect of ESC (Electronic Stability Control) was investigated for the rate of crash exposure, serious injury and fatality in pole and tree impacts. Field data was analyzed by crash type (front, side, rear and rollover) and model year (MY) before, during and after the implementation of ESC. MethodsThe number of pole and tree impacts was determined for four groups of vehicle model years (MY): 1981–1989 MY and 1990–2002 MY before the introduction of ESC, 2003–2009 during the phase-in of ESC and 2010–2020 MY after essentially all vehicles were equipped with ESC. Collisions were grouped by front, side, rear and rollover. Three databases were analyzed: 1990–2020 FARS, 1990–2015 NASS-CDS and 2017–2020 CISS. Vehicle registration was obtained from IHS Markit to determine the rate of pole and tree impacts per 100,000 registered vehicles. The same vehicle selection criteria was used for vehicle registration and crash data. ResultsFatalities dropped 65.2 % (95 % CI, 63.0–67.4 %), z = 43.7, p < 0.001 into poles and 60.3 % (95 % CI, 59.0–61.5 %), z = 72.4, p < 0.001 into trees in vehicles equipped with ESC comparing 1990–2002 MY to 2010–2020 MY vehicles. Seriously injured occupants in crashes with poles dropped 75.9 % (95 % CI, 75.0–76.9 %), z = 116, p < 0.001 between 1990 and 2002 MY and 2010–2020 MY vehicles. There was a 65.2 % (95 % CI, 64.4–65.9 %), z = 141, p < 0.001 reduction in tree impacts. The crash exposure to pole impacts dropped 36.0 % (95 % CI, 35.8–36.3 %), z = 252, p < 0.001 from 80.77/100,000 registered vehicles in 1990–2002 MY vehicles to 51.69/100,000 in 2010–2020 MY vehicles. There was a 61.0 % (95 % CI, 60.8–61.2 %), z = 434, p < 0.001 reduction in tree impacts. For rear impacts, fatalities dropped 82.9 % (95 % CI, 71.3–94.4 %), z = 9.37, p < 0.001 into poles and 74.8 % (95 % CI, 67.8–81.9 %), z = 14.8, p < 0.001 into trees. Serious-injury in rear impacts with poles and trees were essentially eliminated in 2010–2020 MY vehicle crashes. There were significant drops in fatalities in side and frontals impacts and rollovers in vehicles equipped with ESC. ConclusionESC helps the driver maintain vehicle heading and significantly reduced the rate of serious injury and fatality in off-road impacts with poles and trees. The benefits of ESC may not be realized with impairments when the driver does not appropriately steer the vehicle.

Injury risk curves to guide safe speed limits on Swedish roads using German crash data supplemented with estimated non-injury crashes

Vision Zero postulates that no one should be killed or seriously injured in road traffic; therefore, it is necessary to define evidence-based speed limits to mitigate impact severity. The overall aims to guide the definition of safe speeds limits by establishing relations between impact speed and the risk of at-least-moderate (MAIS2+) and at-least-severe (MAIS3+) injuries for car occupants in frontal and side crashes in Sweden. As Swedish in-depth data are unavailable, the first objective was to assess the applicability of German In-depth Accident Study (GIDAS) data to Sweden. The second was to create unconditional injury risk curves (risk of injury given involvement in any crash), rather than risk curves conditional on the GIDAS sampling criterion of suspected-injury crashes. Thirdly, we compared the unconditional and conditional risk curves to quantify the practical implications of this methodological choice. Finally, we provide an example to demonstrate how injury risk curves facilitate the definition of safe, evidence-based speed limits in Sweden. Characteristics important for the injury outcome were similar between GIDAS and Swedish data; therefore, the injury risk curves using German GIDAS data are applicable to Sweden. The regression models yielded the following results for unconditional injury risk curves: 10 % MAIS2+ at 25 km/h impact speed for frontal head-on crashes, 20 km/h for frontal car-to-object crashes, 55 km/h in far-side crashes, and 45 km/h in near-side crashes. A 10 % MAIS3+ risk was reached between 70 and 75 km/h for all crash types. Conditional injury risk curves gave substantially different results; the 10 % MAIS3+ risk in near-side crashes was 140 km/h, twice the unconditional value. For example, if a 10 % MAIS3+ risk was acceptable, treating remaining uncertainty conservatively, assuming compliance with speed limits and that Automated Emergency Braking takes 20 km/h of the travel speed before impact in longitudinal traffic, the safe speed limit for car occupants on most Swedish roads would be 80 km/h and 60 km/h in intersections.

Assessing injury risks of reclined occupants in a frontal crash preceded by braking with varied seatbelt designs using the SAFER Human Body Model

Objective This study investigated the effects of different seatbelt geometries and load-limiting levels on the kinematics and injury risks of a reclined occupant during a whole-sequence frontal crash scenario, using simulations with the Active SAFER Human Body Model (Active SHBM). Methods The Active SHBM was positioned in a reclined position (50°) on a semi-rigid seat model. A whole-sequence frontal crash scenario, an 11 m/s2 Automated Emergency Braking (AEB) phase followed by a frontal crash at 50 km/h, was simulated. The seatbelt geometry was varied using either a B-pillar-integrated (BPI) or Belt-in-seat (BIS) design. The shoulder belt load-limiting level of the BPI seatbelt was also varied to achieve either similar shoulder belt forces (BPI_Lower_LL) or comparable upper body displacements (BPI_Higher_LL) to the BIS seatbelt. Kinematics of different body regions and seatbelt forces were compared. The risks of sustaining a mild traumatic brain injury (mTBI), two or more fractured ribs (NFR2+), and lumbar spine vertebral fractures were also compared. Results During the pre-crash phase, head, first thoracic vertebra, and first lumbar vertebra displacements were greater with the BPI seatbelt than with the BIS, mainly due to the lack of initial contact between the torso and the seatbelt. Pelvis pre-crash displacements, however, remained consistent across seatbelt types. In the in-crash phase, variations in shoulder belt forces were directly influenced by the different load-limiting levels of the shoulder belt. The mTBI (around 20%) and NFR2+ (around 70–100%) risks were amplified with BPI seatbelts, especially at higher load-limiting force. However, the BPI design demonstrated reduced lumbar spine fracture risks (from 30% to 1%). Conclusions The BIS seatbelt appears promising, as seen with the reduced mTBI and NFR2+ risks, for ensuring the protection of reclined occupants in frontal crashes. However, additional solutions, such as lap belt load limiting, should be considered to reduce lumbar spine loading.

Computed tomography assessment of pelvic bone density: Associations with age and pelvic fracture in motor vehicle crashes

Motor vehicle crash (MVC) occupants routinely get a computed tomography (CT) scan to screen for internal injury, and this CT can be leveraged to opportunistically derive bone mineral density (BMD). This study aimed to develop and validate a method to measure pelvic BMD in CT scans without a phantom, and examine associations of pelvic BMD with age and pelvic fracture incidence in seriously injured MVC occupants from the Crash Injury Research and Engineering Network (CIREN) study. A phantom-less muscle-fat calibration technique to measure pelvic BMD was validated using 45 quantitative CT scans with a bone calibration phantom. The technique was then used to measure pelvic BMD from CT scans of 252 CIREN occupants (ages 16+) in frontal MVCs who had sustained either abdominal or pelvic injury. Pelvic BMD was analyzed in relation to age and pelvic fracture incidence. In the validation set, phantom-based calibration vs. phantom-less muscle-fat calibration yielded similar BMD values at the anterior superior iliac spine (ASIS; R2 = 0.95, p < 0.001) and iliac crest (R2 = 0.90, p < 0.001). Pelvic BMD was measured in 150 female and 102 male CIREN occupants aged 16–89, and 25% of these occupants sustained pelvic fracture. BMD at the ASIS and iliac crest declined with age (p < 0.001). For instance, iliac crest BMD decreased an average of 25 mg/cm3 per decade of age. The rate of iliac crest BMD decline was 7.6 mg/cm3 more per decade of age in occupants with pelvic fracture compared to those not sustaining pelvic fracture. Findings suggest pelvic BMD may be a contributing risk factor for pelvic fracture in MVCs.

Impact of Steering Column Stiffness on the Injury Criteria of Dummies using Siemens Madymo

In the event of an accident, in today’s vehicle belt and airbag systems and steering columns absorb the kinetic energy of occupants in front crashes. Most steering columns are equipped with a deformation device, which provides additional forward displacement of the steering wheel when being impacted dynamically by the occupant. As these features perform on predefined force levels, they deform less when loaded with lower energy, e.g. when impacted by a smaller occupant. So especially for occupants of lower kinetic energy the maximum available forward displacement is not provided, so they will be decelerated on a higher g-levels than needed. This study investigates for different dummies how the force level of the steering column must be designed to keep the standard injury criteria as low as possible. The aim is to make a statement about the required optimized force levels of the steering column in order to examine technical feasibility in subsequent studies. To carry out these investigations, a parameter study is carried out in Siemens Madymo and the results obtained are interpreted. Subsequently, the limitations of this study are pointed out and further improvements are suggested.

Influences of human thorax variability on population rib fracture risk prediction using human body models.

Rib fractures remain a common injury for vehicle occupants in crashes. The risk of a human sustaining rib fractures from thorax loading is highly variable, potentially due to a variability in individual factors such as material properties and geometry of the ribs and ribcage. Human body models (HBMs) with a detailed ribcage can be used as occupant substitutes to aid in the prediction of rib injury risk at the tissue level in crash analysis. To improve this capability, model parametrization can be used to represent human variability in simulation studies. The aim of this study was to identify the variations in the physical properties of the human thorax that have the most influence on rib fracture risk for the population of vehicle occupants. A total of 15 different geometrical and material factors, sourced from published literature, were varied in a parametrized SAFER HBM. Parametric sensitivity analyses were conducted for two crash configurations, frontal and near-side impacts. The results show that variability in rib cortical bone thickness, rib cortical bone material properties, and rib cross-sectional width had the greatest influence on the risk for an occupant to sustain two or more fractured ribs in both impacts. Therefore, it is recommended that these three parameters be included in rib fracture risk analysis with HBMs for the population of vehicle occupants.

Serious-to-fatal injury to second-row occupants in rear impacts using 1994–2020 field data

Objective Serious-to-fatal injury was analyzed for second-row children aged 0–14 years and adults aged 15 and older in rear impacts by body region, restraint use, and injury mechanism using field data collected by NHTSA. Method 1994–2015 NASS-CDS and 2017–2020 CISS data were used to investigate the rate for Maximum Abbreviated Injury Scale (MAIS) 3 + F injury in rear crashes involving 1994+ model year vehicles. All second-row occupants were included, irrespective of restraint use and ejection status. The data were analyzed by group: children (0–14 years old) and adults (15+ years old). All available electronic files for seriously injured second-row occupants in the rear impacts were reviewed for mechanism of injury. Results The rate of serious injury (MAIS 3 + F) for second-row occupants was 0.93% ± 0.36% in rear crashes; it was 0.76% ± 0.39% for children and 1.22% ± 0.40% for adults. There were 2.8 AIS 3+ injuries per seriously to fatally injured occupant on average. Most serious injuries occurred to the head in children and to the head and chest in adults. Restraint use was only 31.3% for all seriously injured second-row occupants in the rear impacts. It was 45.1% for children and 17.8% for adults. The overall rate of serious injury in rear impacts was 10.0 times higher when unrestrained than restrained overall; it was 5.6 times higher for children and 20.2 times higher in adults. The case review indicated that many young children were improperly restrained or placed in the incorrect child seat. More than 17% of second-row adults were ejected; all were unrestrained. The primary mechanism for child injury was related to intrusion (86.0%). About 14% was not related to intrusion; 12.3% involved the front seat rotating rearward into the child. The primary mechanisms for adult injury differed from those for children; 68.0% was related to intrusion, 21.6% was not related to intrusion, and 10.4% involved ground impact with ejection. Of the non-intrusion-related cases, 19.1% involved acceleration forces injuring the adult and 2.5% involved the front seat rotating rearward. Conclusions The primary mechanism for serious injury to second-row occupants in rear crashes was intrusion either by direct force, compression into front components, or acceleration into forward components. The front seat moving rearward was an infrequent cause for injury.

Effects of muscle quantity and bone mineral density on injury and outcomes in older adult motor vehicle crash occupants

Objectives: Quantify the independent and combined effects of abdominal muscle quantity and lumbar bone mineral density (BMD) on injury risk and in-hospital outcomes in severely injured motor vehicle crash (MVC) occupants ages 50 and older. Methods: Skeletal muscle area measurements of MVC occupants were obtained through semi-automated segmentation of an axial computed tomography (CT) slice at the L3 vertebra. An occupant height-normalized Skeletal Muscle Index (SMI) was calculated - a defining metric of sarcopenia and low muscle mass (sarcopenia thresholds: <38.5 cm2/m2 females; <52.4 cm2/m2 males). Lumbar BMD was obtained using a validated, phantomless CT calibration method (osteopenia threshold: <145 mg/cm3). SMI and BMD values were used to categorize occupants, and logistic regression was used to associate sarcopenia, osteopenia, and osteosarcopenia predictors to injury outcomes (e.g., Injury Severity Score (ISS), maximum Abbreviated Injury Scale (MAIS) score, fractures) and hospital outcomes (e.g., length of stay, ICU days). Results: Of the 336 occupants, 210 (63%) were female (mean ± SD: age 66.3 ± 10.6). SMI was 41.7 ± 8.0 cm2/m2 in females and 51.2 ± 10.8 cm2/m2 in males. Based on SMI, 40% of females and 55% of males were classified as sarcopenic. BMD was 163.2 ± 38.3 mg/cm3 in females and 164.1 ± 35.4 mg/cm3 in males, with 41% of females and 33% of males classified as osteopenic. Prevalence of both conditions (osteosarcopenia) was similar between females (21%) and males (22%). Incidence of low SMI and BMD increased with age. Sarcopenic individuals were less likely to sustain a MAIS 2+ thorax injury and had longer ICU stays. Osteopenic individuals were more likely to sustain upper extremity injuries and fractures, and were less likely to be discharged to a rehabilitation facility. Osteosarcopenic individuals were less likely to be ventilated or admitted to the ICU but tended to spend more time on the ventilator if placed on one. Conclusions: Osteosarcopenia was not associated with any injury outcomes, but sarcopenia was associated with thoracic injury and osteopenia was associated with upper extremity injury incidence. Sarcopenia was only associated with ICU length of stay, while osteopenia was only associated with discharge destination. Osteosarcopenia was associated with likelihood of being ventilated, being admitted to the ICU, and with increased length of ventilation.

Failure tolerance of the human lumbar spine in dynamic combined compression and flexion loading

Vehicle safety systems have substantially decreased motor vehicle crash-related injuries and fatalities, but injuries to the lumbar spine still have been reported. Experimental and computational analyses of upright and, particularly, reclined occupants in frontal crashes have shown that the lumbar spine can be subjected to simultaneous and out-of-phase combined axial compression and flexion loading. Lumbar spine failure tolerance in combined compression-flexion has not been widely explored in the literature. Therefore, the goal of this study was to measure the failure tolerance of the lumbar spine in combined compression and flexion. Forty lumbar spine segments with three vertebrae (one unconstrained) and two intervertebral discs (both unconstrained) were pre-loaded with axial compression (2200N, 3300N, or 4500N) and then subjected to rotation-controlled dynamic flexion bending until failure. Clinically relevant middle vertebra fractures were observed in twenty-one of the specimens, including compression and burst fractures. The remaining nineteen specimens experienced failure at the potting-grip interface. Failure tolerance varied within the sample and were categorized by the appropriate data censoring, with clinically relevant middle vertebrae fractures characterized as uncensored or left-censored and potting-grip fractures characterized as right-censored. Average failure force and moment were 3290N (range: 1580N to 5042N) and 51Nm (range: 0Nm to 156 Nm) for uncensored data, 3686N (range: 3145N to 4112N) and 0Nm for left-censored data, and 3470N (range: 2138N to 5062N) and 101Nm (range: 27Nm to 182Nm) for right-censored data. These data can be used to develop and improve injury prediction tools for lumbar spine fractures and further research in future safety systems.

Evaluation of a diverse population of morphed human body models for prediction of vehicle occupant crash kinematics

Morphing can be used to alter human body models (HBMs) to represent a diverse population of occupants in car crashes. The mid-sized male SAFER HBM v9 was parametrically morphed to match 22 Post Mortem Human Subjects, loaded in different configurations. Kinetics and kinematics were compared for the morphed and baseline HBMs. In frontal impacts, the morphed HBMs correlated closer with the kinematics of obese subjects, but lower to small females. In lateral impacts HBM responses were too stiff. This study outlines a necessary evaluation of all HBMs that should be morphed to represent the diverse population in vehicle safety evaluations.

Analysis of Injury Severity involving of Passenger Vehicles’ Occupants in Frontal Impact Collisions

&#x0D; &#x0D; &#x0D; In Malaysia, Passenger Vehicles (PV) accounted for the second-highest proportion of vehicles involved in road crashes (13.5%) as well as the total number of casualties (18.6%) after motorcycles. This raised the alarm that a thorough investigation should be conducted on the injury severity of occupants in PV crashes involving frontal impact collisions. The objective of this study is to evaluate injury severity outcome based on the selected crash parameters for the front seat occupants involved in frontal impact collision. The data for this study was sourced from the MIROS crash investigation database (MICARS) from 2007 until 2019, during which MIROS had investigated a total of 975 cases in both East and West Malaysia. After filtering through the cases, a total of 129 frontal impact crashes (PV versus PV) involving 206 PV and 349 front seat occupants were selected for data analysis. From the total number of selected cases, 82 cases were involved in head-on collisions while 47 cases were involved in side-impact collisions. As a result, crash configuration, crush extent, airbag availability, and seatbelt wearing are strongly related to the level of injury severity of frontal seat occupants involved in a frontal impact collision. Meanwhile, collision types and occupant seating position do not appear to be significantly related to the severity of the occupants’ injuries.&#x0D; &#x0D; &#x0D;

Change in seating position of children in towaway crashes from 1989 to 2019

ObjectiveThe purpose of this study was to examine the impact of the nationwide response to passenger airbag (PA) related deaths of children. The response was implemented in 1996 and focused on moving children to rear seats. This study determined the change in seating position of children from 1989 to 2019. MethodsField accident data on exposed occupants in towaway crashes was determined using 1989–2015 NASS-CDS in five groups (1989–1995, 1996–99, 2000–04, 2005–09 and 2010–15) and 2017–19 CISS in one group. Children were grouped as 0–2 yo (years old), 3–7 yo and 8–12 yo. Occupants 13 + were included for completeness. Seat position was defined as left-front (LF), right-front (RF), 2nd row and 3rd row. The weighted data provided an estimate for the change in seating position over time by occupant age with standard errors. ResultsFor 0–2 yo, 27.9% were in the RF seat in 1989–95. The fraction decreased to 0.40% in the 2017–19 (p < 0.001). For 3–7 yo, 32.1% were in the RF seat in 1989–95 and 3.2% in 2017–19 (p < 0.001). There has been a steady decrease in 0–7 yo using the RF seat. For 8–12 yo, there was a step decline in use of the RF seat from 39.5% in 1989–95 to 23.2% in the 2017–19 (p < 0.001). ConclusionsThe immediate reduction in front-seat use among younger children was associated with the nationwide public information efforts implemented in 1996 to move children to rear seats. Children up to 7 yo are no longer riding in the RF seat of vehicles in towaway crashes, unless there is no other option. Children 8–12 yo are still using the RF seat, but at a lower rate. The change in use of the RF seat for children 0–7 yo provides evidence that safety campaigns on placing young children in rear seats were successful in the US.

Comparison of injuries in multiple and single event crashes

Objective: Compare injuries for occupants in multiple event (ME) crashes where a less severe event preceded a more severe event to occupants in similar single event (SE) crashes. Methods: Occupants in ME crashes from NASS-CDS years 2000–2015 where the most severe event occurred subsequent to a less severe event were matched to occupants in SE crashes where the SE was similar to the most severe event in the ME crash. Occupants were matched based on occupant, vehicle, and crash characteristics and were compared across 21 detailed body regions using conditional logistic regression. Finite element (FE) simulations were performed with human surrogate models (detailed GHBMC and Hybrid III) and in both low- and high-speed conditions (n = 8 total simulations). At each speed, the crash simulations with both human body models reproduced a common multidirectional ME crash scenario, where the second impulse was more severe and similar to the SE impulse. Relative injury risk was assessed, and ME versus SE were computed and compared to those from the field data. Results: 1,663 ME occupants were matched to 3,217 SE occupants. ME occupants had higher MAIS2+ and MAIS3+ injury risk, and showed directionally higher injury risk in all but one body region. Eleven out of the 27 injury groups had higher injury risk in ME (false discovery rate (FDR)<0.1; all p-values < 0.0427). Increased injury risk was seen in some injuries to the head, thorax, lumbar spine, shoulder, and lower extremity (odds ratios >1.54). In FE simulations, ME displayed larger anterior and lateral displacement compared to SE. Head and thorax injury risk was increased in ME simulations by up to 5-fold. The detailed GHBMC and Hybrid III exhibited different kinematics and injury risk across all simulations, as did low- and high-speed conditions. Conclusions: The field data and FE simulations suggest that a first, less severe crash event results in occupants having greater injury risk when they are involved in a second, more severe crash event than if they were involved only in the second event. Several factors could cause this increase in injury risk, such as improper interaction with safety systems and airbags after the first event renders the occupant out-of-position.

Submarining sensitivity across varied seat configurations in autonomous driving system environment

Objective Self-driving technology will bring novelty in vehicle interior design and allow for a wide variety of occupant seating choices. Thus, vehicle safety systems may be challenged to protect occupants over a wider range of potential postures. This study aims to investigate the effects of the seat cushion angle on submarining risk, lumbar spine loads and pelvis excursion for reclined occupants in frontal crashes. Methods Frontal crash finite element simulations were performed with two of the simplified Global Human Body Model Consortium (GHBMC) occupant models: the small female and the midsize male. Occupant restraints consisted of a frontal airbag, a seatback-integrated 3-point belt with a lap belt anchor pre-tensioner, and a retractor pre-tensioner with a force limiter. For each simulation, parameters including seat cushion angle (3°, 8°, 13°), seatback recline angle (0°, 10°, 20°, 30°), and knee bolster (KB) position relative to the occupant (baseline and no KB) were varied. A full-factorial simulation matrix was performed using the USNCAP 56 km/h frontal crash pulse. Occupant kinematics data were extracted from each simulation to investigate how changes in seat cushion angle, anthropometry, seatback angle, and KB position would affect submarining across all simulated cases. Results Overall, the F05-OS female model was more likely to submarine when compared to the male occupant model. The threshold for submarining was also affected by the seat cushion angle, seatback angle and KB distance. For the F05-OS model, increasing the seat cushion angle to 13° prevented submarining in the 10° seatback angle case, regardless of the KB position. Similarly, the 13° cushion angle prevented submarining for the M50-OS in the 30° seatback angle configuration but only in the presence of a KB. The results further show an increased lumbar flexion load with increased seat recline angle, as well as occupant-to-KB distance, although an opposite trend with the increased seat cushion angle. Conclusions Submarining may be a major challenge to overcome for reclined occupants in autonomous driving systems. This study shows that seat cushion angle plays a role in restraining occupants in recline scenarios, but it is not sufficient to prevent submarining without additional countermeasures.

Seatbelt laws and seatbelt use among front- and rear-seat vehicle occupants in fatal crashes in the United States

Seatbelt laws are deemed effective at increasing seatbelt use, consequently, reducing fatalities associated with motor vehicle crashes in the United States. Previous studies have provided significant insights about the effectiveness of seatbelt laws, however, studies exploring passenger seatbelt use accounting for the variations in seatbelt laws are not well documented in the literature. Seatbelt laws vary by whether they cover front-seat occupants only or include rear-seat passengers as well. The primary objective of this study was to investigate the differences in adult seatbelt compliance rate based on six categories of seatbelt laws in the United States using crash data. In this present study, six categories of seatbelt laws are considered ranging from no seatbelt law to primary seatbelt law covering all vehicle occupants. Using Tukey-type multiple comparison test, a positive relationship between seatbelt laws and adult seatbelt use was found. Specifically, states with stricter seatbelt laws, that is primary law for all front- and rear-seat occupants, exhibit higher seatbelt compliance rate than those with less strict (partial primary/secondary laws) or no seatbelt laws. Given the significant differences in adult seatbelt use based on our study design (using six categories of seatbelt laws), the analysis support that if states upgrade their seatbelt laws from no/secondary laws to primary laws covering all vehicle occupants, there likely will be positive impacts on adult seatbelt use. The findings in this study are to inform and support decision policies and intervention strategies that are effective at promoting safety for motor vehicle occupants.

Sarcopenia and osteosarcopenia in seriously injured motor vehicle crash occupants

Objective: The objective of this study was to examine the prevalence of sarcopenia (low muscle mass) and osteosarcopenia (low bone density and muscle mass) in older motor vehicle crash (MVC) occupants and the relationship of these musculoskeletal conditions with age, sex, and injury.Methods: Sarcopenia and osteopenia was assessed from abdominal computed tomography (CT) scans of 61 seriously injured MVC occupants over age 50 in the Crash Injury Research and Engineering Network (CIREN) database.Results: The prevalence was 43% for sarcopenia, 25% for osteopenia, and 15% for osteosarcopenia in the CIREN occupants. The Injury Severity Score (ISS) was higher in those with only sarcopenia (mean ± SE = 22.4 ± 2.3), followed by those with osteosarcopenia (17.9 ± 2.4) and only osteopenia (12.8 ± 1.5). More total fractures were observed in occupants with sarcopenia alone (7.6 ± 1.5) or osteosarcopenia (7.0 ± 2.1) compared to nonsarcopenic occupants with osteopenia (4.0 ± 2.5).Conclusions: Sarcopenia and osteosarcopenia may be associated with more serious injuries and fractures in MVCs.

Factors contributing to serious and fatal injuries in belted rear seat occupants in frontal crashes

Objectives: Earlier research has shown that the rear row is safer for occupants in crashes than the front row, but there is evidence that improvements in front seat occupant protection in more recent vehicle model years have reduced the safety advantage of the rear seat versus the front seat. The study objective was to identify factors that contribute to serious and fatal injuries in belted rear seat occupants in frontal crashes in newer model year vehicles.Methods: A case series review of belted rear seat occupants who were seriously injured or killed in frontal crashes was conducted. Occupants in frontal crashes were eligible for inclusion if they were 6 years old or older and belted in the rear of a 2000 or newer model year passenger vehicle within 10 model years of the crash year. Crashes were identified using the 2004–2015 National Automotive Sampling System Crashworthiness Data System (NASS-CDS) and included all eligible occupants with at least one Abbreviated Injury Scale (AIS) 3 or greater injury. Using these same inclusion criteria but split into younger (6 to 12 years) and older (55+ years) cohorts, fatal crashes were identified in the 2014–2015 Fatality Analysis Reporting System (FARS) and then local police jurisdictions were contacted for complete crash records.Results: Detailed case series review was completed for 117 rear seat occupants: 36 with Maximum Abbreviated Injury Scale (MAIS) 3+ injuries in NASS-CDS and 81 fatalities identified in FARS. More than half of the injured and killed rear occupants were more severely injured than front seat occupants in the same crash. Serious chest injury, primarily caused by seat belt loading, was present in 22 of the injured occupants and 17 of the 37 fatalities with documented injuries. Nine injured occupants and 18 fatalities sustained serious head injury, primarily from contact with the vehicle interior or severe intrusion. For fatal cases, 12 crashes were considered unsurvivable due to a complete loss of occupant space. For cases considered survivable, intrusion was not a large contributor to fatality.Discussion: Rear seat occupants sustained serious and fatal injuries due to belt loading in crashes in which front seat occupants survived, suggesting a discrepancy in restraint performance between the front and rear rows. Restraint strategies that reduce loading to the chest should be considered, but there may be potential tradeoffs with increased head excursion, particularly in the absence of rear seat airbags. Any new restraint designs should consider the unique needs of the rear seat environment.

How far from home do crashes occur? A network based analysis

This paper investigates the proximity of crashes to the residential locations of the crash occupants. To this end, two years of crash data was disaggregated by the crash occupants’ ZIP codes for a study area in Southwest Florida in order to calculate the roadway network distances between their residential ZIP code area centroids (origins) and crash spots (destinations). These distances are then used to create multiple O-D vectors, so that several different groups can be analyzed controlling for non-motorist types (e.g. pedestrians, cyclists), rural vs. urban origin ZIP codes, different levels of crash severity, DUI involvement, and different age groups. Then, the best-fitting statistical distributions were identified for each group to assess the proximity of crash spots to the residences of crash occupants. Finally, a selection model was implemented to identify the effects of several factors on the distance between the crash spots and the residence locations. Results indicate clear differences in crash involvement among the groups with respect to varying urban densities, people’s ages and modes of travel. These findings can help in the development of more accurate crash prediction methods, as most current approaches only implement variables associated with traffic and roadway geometry.

Cervical and thoracic spine injury in pediatric motor vehicle crash passengers

Objective: Motor vehicle occupants aged 8 to 12 years are in transition, in terms of both restraint use (booster seat or vehicle belt) and anatomical development. Rear-seated occupants in this age group are more likely to be inappropriately restrained than other age groups, increasing their vulnerability to spinal injury. The skeletal anatomy of an 8- to 12-year-old child is also in developmental transition, resulting in spinal injury patterns that are unique to this age group. The objective of this study is to identify the upper spine injuries commonly experienced in the 8- to 12-year-old age group so that anthropomorphic test devices (ATDs) representing this size of occupant can be optimized to predict the risk of these injuries.Methods: Motor vehicle crash cases from the National Trauma Data Bank (NTDB) were analyzed to characterize the location and nature of cervical and thoracic spine injuries in 8- to 12-year-old crash occupants compared to younger (age 0–7) and older age groups (age 13–19, 20–39).Results: Spinal injuries in this trauma center data set tended to occur at more inferior vertebral levels with older age, with patients in the 8- to 12-year-old group diagnosed with thoracic injury more frequently than cervical injury, in contrast to younger occupants, for whom the proportion of cases with cervical injury outnumbered the proportion of cases with thoracic injury. With the cervical spine, a higher proportion of 8- to 12-year-olds had upper spine injury than adults, but a substantially lower proportion of 8- to 12-year-olds had upper spine injury than younger children. In terms of injury type, the 8- to 12-year-old group’s injury patterns were more similar to those of teens and adults, with a higher relative proportion of fracture than younger children, who were particularly vulnerable to dislocation and soft tissue injuries. However, unlike for adults and teens, catastrophic atlanto-occipital dislocations were still more common than any other type of dislocation for 8- to 12-year-olds and vertebral body fractures were particularly frequent in this age group.Conclusions: Spinal injury location in the cervical and thoracic spine moved downward with age in this trauma center data set. This shift in injury pattern supports the need for measurement of thoracic and lower cervical spine loading in ATDs representing the 8- to 12-year-old age group.

Rollover injury in vehicles with high-strength-to-weight ratio (SWR) roofs, curtain and side airbags, and other safety improvements

Purpose: This study investigated trends in severe injury and ejection in rollover crashes involving lap–shoulder-belted drivers and right-front passengers. It was conducted because of changes in 2009 to consumer information programs and regulations related to rollover protection. The data are presented by model year (MY) of the vehicle in groups from 1995 to 2016. NASS-CDS cases with 2010–2016 MY vehicles were also evaluated to determine the crash circumstances and causes for severe injury of belted occupants in vehicles with a high strength-to-weight (SWR) roof, curtain, and side airbags and other safety improvements.Methods: 1997–2015 NASS-CDS data were evaluated for severe injury and ejection of lap–shoulder-belted front outboard occupants in light vehicles. Crashes were grouped by front, side, rear, and rollover. The injury and ejection data were grouped by vehicle MY: 1995–1999, 2000–2004, 2005–2009, and 2010–2016. Only drivers and right-front passengers were included if they were lap–shoulder belted and 15+ years old. Severely injured occupants were defined as those with Maximum Abbreviated Injury Scale (MAIS) 4–6 or fatality (MAIS 4 + F). National estimates were made with weighted data using the ratio weight in NASS-CDS. All NASS-CDS electronic cases were evaluated for belted occupants with MAIS 4 + F injury in rollovers involving 2010–2016 MY vehicles. The crash circumstances and injuries were studied. These vehicles had high-SWR roofs to meet Insurance Institute for Highway Safety (IIHS) ratings and FMVSS 216.Results: The 1997–2015 NASS-CDS included 2,083,776 belted front occupants in rollover crashes with 24,466 (1.17%) MAIS 4 + F injuries. The frequency of rollover crashes has decreased with modern vehicles (P < .0001). The 1995–1999 MY vehicles involved in a rollover accounted for 7.03% of all crashes (756,228/10,760,000). The corresponding proportion was 3.57% with 2010–2016 MY vehicles (81,406 vs. 2,282,062).The risk for MAIS 4 + F was 1.325 ± 0.347% in rollover crashes with 1995–1999 MY vehicles. It was 27.2% lower in 2010–2016 MY vehicles at 0.964 ± 0.331% (P < .001). There were 42,567 (2.002%) ejections of belted occupants in rollover crashes, irrespective of injury outcome. The risk for ejection was 3.042 ± 1.44% in rollover crashes with 1995–1999 MY vehicles. It was 43.6% lower in 2004–2009 MY vehicle at 1.715 ± 0.660% (P < .001) and 83.4% lower in 2010–2016 MY vehicle at 0.505 ± 0.336% (P < .001). There were 17 rollovers with MAIS 4 + F in 2010–2016 MY vehicles in NASS-CDS. Their roof strength was SWR =4.15 ± 1.05 based on 15 vehicles. Many of the collisions involved front or side impacts and then a rollover. Four cases involved 16- to 30-year-old drivers in extremely high-speed loss-of-control crashes resulting in >10-cm vertical roof deformation or substantial roof deformation based on photos. The roof strength (SWR) of 4.20 ± 1.0 was not sufficient to prevent roof deformation in these crashes.Conclusions: This study found a reduction in severe injury and ejection risk with modern vehicles. It indicates that vehicle safety has improved in response to IIHS and NHTSA efforts to expand the array of safety requirements and increase performance so that newer models are safer than earlier ones. There has been an incremental improvement in safety due to these advances.