Analysis of rider and child pillion passenger kinematics along with injury mechanisms during motorcycle crash

Abstract

Objective: Traffic fatalities among motorcycle users are intolerably high in Thailand. They account for 73% of the total number of road fatalities. Children are also among these victims. To improve countermeasures and design of protection equipment, understanding the biomechanics of motorcycle users under impact conditions is necessary. The objective of this work is to analyze the overall kinematics and injuries sustained by riders and child pillion passengers in various accident configurations.

Methods: Motorcycle accident data were analyzed. Common accident scenarios and impact parameters were identified. Two numerical approaches were employed. The multibody model was validated with a motorcycle crash test and used to generate possible accident cases for various impact conditions specified to cover all common accident scenarios. Specific impact conditions were selected for detailed finite element analysis. The finite element simulations of motorcycle-to-car collisions were conducted to provide insight into kinematics and injury mechanisms.

Results: Global kinematics found when the motorcycle’s front wheel impacts a car (config-MC) highlighted the translation motion of both the rider and passenger toward the impact position. The rider’s trunk impacted the handlebar and the head either impacted the car or missed. The hood constituted the highest head impact occurrence for this configuration. The child mostly impacted the rider’s back. Different kinematics were found when car impacted the lateral side of the motorcycle (config-CM). Upper bodies of both rider and child were laterally projected toward the car front. The windshield constituted the highest proportion of head impacts. The hood and A-pillar recorded a moderate proportion. The rider in finite element simulations with config-MC experienced high rib stress, lung strain, and pressure beyond the injury limit. A high head injury criterion was observed when the head hit the car. However, the simulation with config-CM exhibited high lower extremities stress and lung pressure in both occupants. Hyperextension of the rider’s neck was observed. The cumulative strain damage measure of the child’s brain was higher than the threshold for diffuse axonal injury (DAI).

Conclusions: This study revealed 2 kinematics patterns and injury mechanisms. Simulations with config-MC manifested a high risk of head and thorax injury to the rider but a low risk of severe injury to the child. Thorax injury to the rider due to handlebar impact was only found in simulations with config-MC. However, a high risk of skull, lower extremity, brain, and neck injuries were more pronounced for cases with config-CM. A high risk of DAI was also noticed for the child. In simulations with config-CM the child exhibited a higher risk of severe injury.     

Prediction of probability of fatality due to brain injury in traffic accidents

Abstract

Objective: Fatal brain injuries result from physiological changes in brain tissues, subsequent to primary damage caused by head impact. Although efforts have been made in past studies to estimate the probability of brain injury, none of them involved prediction of such physiological changes. The goal of this study was to evaluate the fatality prediction capability of a novel approach that predicts an increase in intracranial pressure (ICP) due to primary head injury to estimate the fatality rate using clinical data that correlate ICP with fatality rate.

Methods: A total of 12 sets of head acceleration time histories were used to represent no, severe, and fatal brain injury. They were obtained from the literature presenting head kinematics data in noninjurious volunteer sled tests or from accident reconstruction for severe and fatal injury cases. These were first applied to a Global Human Body Models Consortium (GHBMC) head–brain model to predict nodal displacement time histories of the brain, which were then fed into FEBio to predict ICP. A Weibull distribution was applied to the data for the relationship between fatality rate and ICP obtained from a clinical paper to estimate fatality rate from ICP (procedure A). Fatality rate was also estimated by applying the temporal and spatial maximum value of maximum principal strain (MPS_max) obtained from the GHBMC simulation to an injury probability function for MPS_max (procedure B). Estimated fatality rates were compared between the 2 procedures.

Results: Both procedures estimated higher average fatality rate for higher injury severity. The average fatality rate for procedure A without ischemia representation and procedure B was 72.4 and 51.0% for the fatal injury group and 8.2 and 21.7% for the severe injury group, respectively, showing that procedure A provides more distinct classification between fatal and nonfatal brain injury. It was also found that representation of ischemia in procedure A provides results sensitive to injury severity and impact conditions, requiring further validation of the initial estimate for the relationship between brain compression and ischemic cell death.

Conclusions: Prediction of the probability of fatality by means of a combination of simulations of the primary brain deformation and subsequent ICP increase was found to be more distinct compared to the prediction of primary injury alone combined with the injury probability function from a past study in the select 12 head impact cases.     

Integrated model of simulated occupant injury risk and real medical costs

Introduction

The purpose of this study was to develop an integrated methodology that links occupant injury risk functions, estimated in the laboratory, with real world medical treatment costs by using the abbreviated injury score (AIS). Using our model, the expected medical treatment costs for crash injuries to various body regions and of different severities can be investigated.

Methods

First, the simulation results are compared with NHTSA crash data. We used a modified kinematics simulation model that incorporates an F = E^b function as a supplement to the previous Steffan's model to obtain a more accurate acceleration history a(t). Second, head injury criteria HIC₃₆ can be calculated from a(t), and we use the injury probability P as a function of HIC_36, as proposed by Kuppa, to obtain the injury risk function for various AIS values. Third, medical treatment cost models for various AIS values can be calculated by using a regression cost model with real world data. Finally, the injury risk function and medical treatment cost models are linked through AIS values. We establish an integrated methodology and predict medical costs and car safety data using real world police reports, medical treatment costs, and laboratory simulation results.

Results

Using head injuries in frontal crashes as an example, we focus on simulation parameters for different vehicle models, with and without airbags. We specifically examine impact closing speed, Delta-V, and impact directions.

Conclusion

Simulation results can be used to supplement insufficient real crash data, in particular ΔV, and injury risk results from police crash reports.

Impact on industry

The proposed integrated methodology may provide the vehicle industry with a new safety assessment method. Real crash data coupling provides consumers with more realistic and applicable information.     

Positive affectivity neutralizes transformational leadership's influence on creative performance and organizational citizenship behaviors

This study uses an interactionist approach to examine the moderating effect of follower trait positive affectivity (trait PA) on the relation between transformational leadership and both follower creative performance and organizational citizenship behaviors (OCB). On the basis of responses from 212 employees and their direct supervisors from the research and development department of a company in Mainland China, results support the hypothesized moderation effect. Specifically, the positive influence of transformational leadership on creative performance was significantly reduced for followers who were higher on trait PA (ΔR² = .02, p < .05). The same pattern, in which followers' trait PA appeared to substitute for the influence of transformational leadership, generalized to the outcome of follower OCB as well (ΔR² = .04, p < .01). We discussed theoretical and practical implications of these findings. Copyright © 2012 John Wiley & Sons, Ltd.     

Lumbar Bone Mineral Density Phantomless Computed Tomography Measurements and Correlation with Age and Fracture Incidence

Objective: Low bone quality is a contributing factor to motor vehicle crash (MVC) injury. Quantification of occupant bone mineral density (BMD) is important from an injury causation standpoint. The first aim of this study was to validate a technique for measuring lumbar volumetric BMD (vBMD) from phantomless computed tomography (CT) scans. The second aim was to apply the validated phantomless technique to quantify lumbar vBMD in Crash Injury Research and Engineering Network (CIREN) occupants for correlation with age, fracture incidence, and osteopenia/osteoporosis diagnoses.

Methods: Quantitative CT (qCT) and dual-energy X-ray absorptiometry (DXA) were collected prospectively for 50 subjects and used to validate a technique to measure vBMD from 281 phantomless CT scans of CIREN occupants. Hounsfield unit (HU) measurements were collected from the L1–L5 vertebrae, right psoas major muscle, and anterior subcutaneous fat for all subjects and from 3 phantom ports with known mg/cc calcium hydroxyapatite values for the validation group. qCT calibration was accomplished using regressions between the phantom HU and mg/cc values to convert L1–L5 HU values to mg/cc. A phantomless calibration technique was developed where the fat and muscle HU values were linearly regressed against fat (?69 mg/cc) and muscle (77 mg/cc) to establish a conversion for L1–L5 HU measurements to mg/cc. vBMD calculated from qCT versus the phantomless method was compared for the 50 subjects to assess agreement and a mg/cc osteopenia threshold was established using DXA T-scores. CIREN HU measurements were converted to mg/cc using the phantomless technique and the mg/cc osteopenia threshold was used to compare vBMD to age, fracture incidence, and osteopenia comorbidity classifications in CIREN.

Results: Linear regression of lumbar vBMD derived from the qCT versus phantomless calibrations showed excellent agreement (R² = 0.87, P <.0001). A 145 mg/cc threshold for osteopenia was established (sensitivity = 1, specificity = 0.57) and 44 CIREN occupants had vBMD below this threshold. Of these 44 occupants, 64% were not classified as osteopenic in CIREN, but vBMD suggested undiagnosed osteopenia. Age was negatively correlated with vBMD in both sexes (P <.0001) and CIREN occupants with less than 145 mg/cc vBMD sustained an average 1.7 additional rib/sternum fractures (P =.036).

Conclusions: Because lumbar vBMD was estimated from phantomless CT scans with accuracy similar to qCT, the phantomless technique can be broadly applied to both prospectively and retrospectively assess patient bone quality for research and clinical studies related to MVCs, falls, and aging.     

Differential protective effects of motorcycle helmets against head injury

Background: Although numerous observational studies have demonstrated a protective effect of motorcycle helmets against head injury, the degree of protection against specific head injury types remains unclear. Experimental biomechanics studies involving cadavers, animals, and computer models have established that head injuries have varying etiologies. This retrospective cross-sectional study compared helmet protection against skull fracture, cerebral contusion, intracranial hemorrhage, and cerebral concussion in a consecutive series of motorcycle operators involved in recent traffic crashes in Kentucky.

Methods: Police collision reports linked to hospital inpatient and emergency department (ED) claims were analyzed for the period 2008 to 2012. Motorcycle operators with known helmet use who were not killed at the crash scene were included in the study. Helmet use was ascertained from the police report. Skull fracture, cerebral contusion, intracranial hemorrhage, and cerebral concussion were identified from International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes on the claims records. The relative risks of each type of head injury for helmeted versus unprotected operators were estimated using generalized estimating equations.

Results: Helmets offer substantial protection against skull fracture (relative risk [RR] = 0.31, 95% confidence interval [CI], 0.23, 0.34), cerebral contusion (RR = 0.29, 95% CI, 0.16, 0.53), and intracranial hemorrhage (RR = 0.47, 95% CI, 0.35, 0.63). The findings pertaining to uncomplicated concussion (RR = 0.80, 95% CI, 0.64, 1.01) were inconclusive. A modest protective effect (20% risk reduction) was suggested by the relative risk estimate, but the 95% confidence interval included the null value.

Conclusions: Motorcycle helmets were associated with a 69% reduction in skull fractures, 71% reduction in cerebral contusion, and 53% reduction in intracranial hemorrhage. This study finds that current motorcycle helmets do not protect equally against all types of head injury. Efforts to improve rotational acceleration management in motorcycle helmets should be considered.     

Nationwide risk factors for hospital readmission for subsequent injury after motor vehicle crashes

Abstract

Objective: Some drivers involved in motor vehicle crashes across the United States may be identified as at risk of subsequent injury by a similar mechanism. The purpose of this study was to perform a national review of the risk factors for hospitalization for a new injury due to a subsequent motor vehicle crash. It was hypothesized that presenting to a different hospital after subsequent injury would result in worse patient outcomes when compared to presentation at the same hospital.

Methods: The Nationwide Readmissions Database for 2010–2014 was queried for all inpatient hospitalizations with injury related to motor vehicle traffic. The primary patient outcome of interest was subsequent motor vehicle crash–related injury within 1 year. The secondary patient outcomes were different hospital subsequent injury presentation, higher Injury Severity Score (ISS), longer length of stay (LOS), and in-hospital death after subsequent injury. The analysis of secondary patient outcomes was performed only on patients who were reinjured. Univariable analysis was performed for each outcome using all variables during the index admission. Multivariable logistic regression was performed using all significant (P < .05) variables on univariate analysis. Results were weighted for national estimates.

Results: During the study period, 1,008,991 patients were admitted for motor vehicle–related injury; 12,474 patients (1.2%) suffered a subsequent injury within 1 year. From the reinjured patients, 32.9% presented to a different hospital, 48.9% had a higher ISS, and 22.1% had a longer LOS. The in-hospital mortality rate after subsequent injury was 1.1%. Presentation to a different hospital for subsequent injury was associated with a longer LOS (odds ratio [OR]?=?1.32; 95% confidence interval [CI], 1.20–1.45; P < .01) and a higher ISS (OR?=?1.38; 95% CI, 1.27–1.49; P < .01). Motorcyclists were more likely to suffer subsequent injury (OR?=?1.39; 95% CI, 1.32–1.46; P < .01) and motorcycle passengers were more likely to present to a different hospital with a subsequent injury (OR?=?2.49; 95% CI, 1.73–3.59; P < .01). Alcohol abuse was associated with subsequent injury (OR?=?1.12; 95% CI, 1.07–1.18; P < .01).

Conclusions: Nearly a third of patients suffering subsequent motor vehicle crash–related injury after an initial motor vehicle crash in the United States present to a different hospital. These patients are more likely to suffer more severe injuries and longer hospitalizations due to their subsequent injury. Future efforts to prevent these injuries must consider the impact of this fragmentation of care and the implications for quality and cost improvements.     

Sensitivity of Head and Cervical Spine Injury Measures to Impact Factors Relevant to Rollover Crashes

Objective: Serious head and cervical spine injuries have been shown to occur mostly independent of one another in pure rollover crashes. In an attempt to define a dynamic rollover crash test protocol that can replicate serious injuries to the head and cervical spine, it is important to understand the conditions that are likely to produce serious injuries to these 2 body regions. The objective of this research is to analyze the effect that impact factors relevant to a rollover crash have on the injury metrics of the head and cervical spine, with a specific interest in the differentiation between independent injuries and those that are predicted to occur concomitantly.

Methods: A series of head impacts was simulated using a detailed finite element model of the human body, the Total HUman Model for Safety (THUMS), in which the impactor velocity, displacement, and direction were varied. The performance of the model was assessed against available experimental tests performed under comparable conditions. Indirect, kinematic-based, and direct, tissue-level, injury metrics were used to assess the likelihood of serious injuries to the head and cervical spine.

Results: The performance of the THUMS head and spine in reconstructed experimental impacts compared well to reported values. All impact factors were significantly associated with injury measures for both the head and cervical spine. Increases in impact velocity and displacement resulted in increases in nearly all injury measures, whereas impactor orientation had opposite effects on brain and cervical spine injury metrics. The greatest cervical spine injury measures were recorded in an impact with a 15° anterior orientation. The greatest brain injury measures occurred when the impactor was at its maximum (45°) angle.

Conclusions: The overall kinetic and kinematic response of the THUMS head and cervical spine in reconstructed experiment conditions compare well with reported values, although the occurrence of fractures was overpredicted. The trends in predicted head and cervical spine injury measures were analyzed for 90 simulated impact conditions. Impactor orientation was the only factor that could potentially explain the isolated nature of serious head and spine injuries under rollover crash conditions. The opposing trends of injury measures for the brain and cervical spine indicate that it is unlikely to reproduce the injuries simultaneously in a dynamic rollover test.     

Trends in bicycle-related injuries,hospital admissions,and deaths in the USA 1997–2013

Objective: Cycling is associated with numerous health benefits but also the risk of traumatic injury. Recent data demonstrate an increase in overall cycling injuries as well as hospital admissions from 1997 to 2013 in the United States. We seek to better understand the causes of the increase in cycling injuries and hospital admissions.

Methods: Data regarding cycling-related injuries and hospital admissions were obtained from the National Electronic Injury Surveillance System (NEISS). Participation data were derived from the National Sporting Goods Association Sports Participation Survey, and fatality data were collected from the Fatality Analysis Reporting System (FARS). Population estimates were obtained using a complex survey design. Linear regression was used to evaluate univariate relationships between cycling injuries, hospital admissions, deaths, and participation. To evaluate factors associated with hospital admission, we developed a multivariable logistic regression model that included year, age, gender, body part injured, and injury type (i.e., contusion, fracture, or laceration).

Results: The number of individuals who cycle did not change significantly over time, but there was a substantial increase in cycling-related injuries, leading to an increase in per participant injuries from 701/100,000 in 1997 to 1,164/100,000 in 2013. When the injuries were evaluated by age group, younger cyclists have an increased risk for injury, whereas the rise in injuries among older cyclists stemmed from an increase in ridership rather than a unique susceptibility to injury. Trends in hospital admissions and fatalities appeared to be driven by increases in the older age groups. In the multivariable model evaluating factors related to hospital admission, the odds of hospital admission increased for each decade after age 25, as well as male gender and body part injured.

Conclusion: On a per participant basis, the rate of cycling-related injuries and hospital admissions increased between 1997 and 2013. This trend likely reflects a combination of shifting demographics among cyclists with an increase in older cyclists who are at increased risk of severe injury.     

Health-related quality of life 24 months after sustaining a minor musculoskeletal injury in a road traffic crash: A prospective cohort study

Objectives: A better understanding of the long-term factors that independently predict poorer quality of life following mild to moderate musculoskeletal injuries is needed. We aimed to establish the predictors of quality of life (including sociodemographic, health, psychosocial, and pre-injury factors) 24 months after a noncatastrophic road traffic injury.

Methods: In a prospective cohort study of 252 participants with mild/moderate injury sustained in a road traffic crash, quality of life was measured 24 months following the baseline survey. A telephone-administered questionnaire obtained information on various potential explanatory variables. Health-related quality of life was measured using the European Quality of Life–5 Dimensions (EQ-5D) and Medical Outcomes Survey Short Form–12 (SF-12). Multivariable linear regression analyses determined the associations between explanatory variables and quality of life measures.

Results: Mean SF-12 physical component summary (PCS) and mental component summary (MCS) scores increased by 7.3 and 2.5 units, respectively, from baseline to 24-month follow-up. Each 10-year increase in baseline age was independently associated with 3.1-unit (P < .001) and 1.5-unit (P = .001) decrease in EQ Visual Analogue Scale (VAS) and SF-12 PCS scores at follow-up, respectively. Poor/fair compared to excellent pre-injury health was associated with a 0.16-, 21.3-, and 11.5-unit decrease in EQ-5D summary (P = .03), VAS scores (P = .001), and SF-12 PCS scores (P < .001), respectively. Baseline pain severity ratings and pain catastrophizing scores were inversely associated with 24-month EQ VAS scores (both P < .001). Each unit increase in baseline pain score (P = .001) and pain catastrophizing score (P = .02) was associated with a 1.0- and 4.6-unit decrease in SF-12 MCS scores at 24 months, respectively. Other observed predictors of quality of life measures (EQ-5D summary and/or VAS scores and/ or SF-12 MCS) included marital status, smoking, hospital admission, pre-injury health (anxiety/depression and chronic illness), and whiplash injury.

Conclusion: Sociodemographic indicators, pre-injury health, and biopsychosocial correlates were independently associated with health-related quality of life 24 months following a noncatastrophic road traffic crash injury.     

The effect of correct cross-chest clip use on injury outcomes in young children during motor vehicle crashes

Objective: Traffic crashes have high mortality and morbidity for young children. Though many specialized child restraint systems improve injury outcomes, no large-scale studies have investigated the cross-chest clip's role during a crash, despite concerns in some jurisdictions about the potential for neck contact injuries from the clips. This study aimed to investigate the relationship between cross-chest clip use and injury outcomes in children between 0 and 4 years of age.

Methods: Child passengers between 0 and 4 years of age were selected from the NASS-CDS data sets (2003–2014). Multiple regression analysis was used to model injury outcomes while controlling for age, crash severity, crash direction, and restraint type. The primary outcomes were overall Abbreviated Injury Score (AIS) 2+ injury, and the presence of any neck injury.

Results: Across all children aged 0–4 years, correct chest clip use was associated with decreased Abbreviated Injury Scale (AIS) 2+ injury (odds ratio [OR] = 0.44, 95% confidence interval [CI], 0.21–0.91) and was not associated with neck injury. However, outcomes varied by age. In children <12 months old, chest clip use was associated with decreased AIS 2+ injury (OR = 0.09, 95% CI, 0.02–0.44). Neck injury (n = 7, all AIS 1) for this age group only occurred with correct cross-chest clip use. For 1- to 4-year-old children, cross-chest clip use had no association with AIS 2+ injury, and correct use significantly decreased the odds of neck injury (OR = 0.49; 95% CI, 0.27–0.87) compared to an incorrectly used or absent cross-chest clip. No serious injuries were directly caused by the chest clips.

Conclusions: Correct cross-chest clip use appeared to reduce injury in crashes, and there was no evidence of serious clip-induced injury in children in 5-point harness restraints.     

Cross-correlation between the controlled collision environment and real-world motor vehicle collisions: Evaluating the protection of the thoracic side airbag

Objective: Thoracic side airbags (tSABs) were integrated into the vehicle fleet to attenuate and distribute forces on the occupant's chest and abdomen, dissipate the impact energy, and move the occupant away from the intruding structure, all of which reduce the risk of injury. This research piece investigates and evaluates the safety performance of the airbag unit by cross-correlating data from a controlled collision environment with field data.

Method: We focus exclusively on vehicle–vehicle lateral impacts from the NHTSA's Vehicle Crash Test Database and NASS-CDS database, which are replicated in the controlled environment by the (crabbed) barrier impact. Similar collisions with and without seat-embedded tSABs are matched to each other and the injury risks are compared.

Results: Results indicated that dummy-based thoracic injury metrics were significantly lower with tSAB exposure (P <.001). Yet, when the controlled collision environment data were cross-correlated with NASS-CDS collisions, deployment of the tSAB indicated no association with thoracic injury (tho. MAIS 2+ unadjusted relative risk [RR] = 1.14; 90% confidence interval [CI], 0.80–1.62; tho. MAIS 3+ unadjusted RR = 1.12; 90% CI, 0.76–1.65).

Conclusion: The data from the controlled collision environment indicated an unequivocal benefit provided by the thoracic side airbag for the crash dummy; however, the real-world collisions demonstrate that no benefit is provided to the occupant. This has resulted from a noncorrelation between the crash test/dummy-based design taking the abstracting process too far to represent the real-world collision scenario.     

New Methodology for an Expert-Designed Map From International Classification of Diseases (ICD) to Abbreviated Injury Scale (AIS) 3+ Severity Injury

Objective: There has been a longstanding desire for a map to convert International Classification of Diseases (ICD) injury codes to Abbreviated Injury Scale (AIS) codes to reflect the severity of those diagnoses. The Association for the Advancement of Automotive Medicine (AAAM) was tasked by European Union representatives to create a categorical map classifying diagnoses codes as serious injury (Abbreviated Injury Scale [AIS] 3+), minor/moderate injury (AIS 1/2), or indeterminate. This study's objective was to map injury-related ICD-9-CM (clinical modification) and ICD-10-CM codes to these severity categories.

Methods: Approximately 19,000 ICD codes were mapped, including injuries from the following categories: amputations, blood vessel injury, burns, crushing injury, dislocations/sprains/strains, foreign body, fractures, internal organ, nerve/spinal cord injury, intracranial, laceration, open wounds, and superficial injury/contusion. Two parallel activities were completed to create the maps: (1) An in-person expert panel and (2) an electronic survey. The panel consisted of expert users of AIS and ICD from North America, the United Kingdom, and Australia. The panel met in person for 5 days, with follow-up virtual meetings to create and revise the maps. Additional qualitative data were documented to resolve potential discrepancies in mapping. The electronic survey was completed by 95 injury coding professionals from North America, Spain, Australia, and New Zealand over 12 weeks. ICD-to-AIS maps were created for: ICD-9-CM and ICD-10-CM. Both maps indicated whether the corresponding AIS 2005/Update 2008 severity score for each ICD code was AIS 3+, 1/2, or indeterminable. Though some ICD codes could be mapped to multiple AIS codes, the maximum severity of all potentially mapped injuries determined the final severity categorization.

Results: The in-person panel consisted of 13 experts, with 11 Certified AIS specialists (CAISS) with a median of 8 years and an average of 15 years of coding experience. Consensus was reached for AIS severity categorization for all injury-related ICD codes. There were 95 survey respondents, with a median of 8 years of injury coding experience. Approximately 15 survey responses were collected per ICD code. Results from the 2 activities were compared, and any discrepancies were resolved using additional qualitative and quantitative data from the in-person panel and survey results, respectively.

Conclusions: Robust maps of ICD-9-CM and ICD-10-CM injury codes to AIS severity categories (3+ versus <3) were successfully created from an in-person panel discussion and electronic survey. These maps provide a link between the common ICD diagnostic lexicons and the AIS severity coding system and are of value to injury researchers, public health scientists, and epidemiologists using large databases without available AIS coding.     

Local vs. national: Epidemiology of pedestrian injury in a mid-Atlantic city

Objective: Understanding pedestrian injury trends at the local level is essential for program planning and allocation of funds for urban planning and improvement. Because we hypothesize that local injury trends differ from national trends in significant and meaningful ways, we investigated citywide pedestrian injury trends to assess injury risk among nationally identified risk groups, as well as identify risk groups and locations specific to Baltimore City.

Methods: Pedestrian injury data, obtained from the Baltimore City Fire Department, were gathered through emergency medical services (EMS) records collected from January 1 to December 31, 2014. Locations of pedestrian injuries were geocoded and mapped. Pearson's chi-square test of independence was used to investigate differences in injury severity level across risk groups. Pedestrian injury rates by age group, gender, and race were compared to national rates.

Results: A total of 699 pedestrians were involved in motor vehicle crashes in 2014—an average of 2 EMS transports each day. The distribution of injuries throughout the city did not coincide with population or income distributions, indicating that there was not a consistent correlation between areas of concentrated population or concentrated poverty and areas of concentrated pedestrian injury. Twenty percent (n = 138) of all injuries occurred among children age ≤14, and 22% (n = 73) of severe injuries occurred among young children. The rate of injury in this age group was 5 times the national rate (Incident Rate Ratio [IRR] = 4.81, 95% confidence interval [CI], [4.05, 5.71]). Injury rates for adults ≥65 were less than the national average.

Conclusions: As the urban landscape and associated pedestrian behavior transform, continued investigation of local pedestrian injury trends and evolving public health prevention strategies is necessary to ensure pedestrian safety.     

Work injuries and disability

Problem

This study estimated the hazard ratio for disability pension retirement (DPR) for persons who have experienced a work injury causing absence lasting at least one day after the accidental injury occurred and to estimate the fraction of DPR attributable to work injuries.

Methods:

A total of 4,217 male and 4,105 female employees from a national survey were followed up for subsequent DPR.

Results and impact on industry and government:

Having had a work injury was a strong predictor of DPR among men. After control for age, smoking, body mass index, body postures, and physical demands, the hazard ratio (HR) among those employees who had ever experienced a work injury was 1.80 (95% confidence interval (CI): 1.20-2.68). No association was found among women.

Summary:

Having had a reportable work injury is a strong predictor of subsequent DPR for men.     

Impact of helmet use on traumatic brain injury from road traffic accidents in Cambodia

Objective: Rapid urbanization and motorization without corresponding increases in helmet usage have made traumatic brain injury due to road traffic accidents a major public health crisis in Cambodia. This analysis was conducted to quantify the impact of helmets on severity of injury, neurosurgical indication, and functional outcomes at discharge for motorcycle operators who required hospitalization for a traumatic brain injury following a road traffic accident in Cambodia.

Methods: The medical records of 491 motorcycle operators who presented to a major tertiary care center in Cambodia with traumatic brain injury were retrospectively analyzed using multivariate logistic regression.

Results: The most common injuries at presentation were contusions (47.0%), epidural hematomas (30.1%), subdural hematomas (27.9%), subarachnoid hemorrhages (12.4%), skull fractures (21.4%), and facial fractures (18.5%). Moderate-to-severe loss of consciousness was present in 36.3% of patients. Not wearing a helmet was associated with an odds ratio of 2.20 (95% confidence interval [CI], 1.15–4.22) for presenting with moderate to severe loss of consciousness compared to helmeted patients. Craniotomy or craniectomy was indicated for evacuation of hematoma in 20.0% of cases, and nonhelmeted patients had 3.21-fold higher odds of requiring neurosurgical intervention (95% CI, 1.25–8.27). Furthermore, lack of helmet usage was associated with 2.72-fold higher odds of discharge with functional deficits (95% CI, 1.14–6.49). In total, 30.1% of patients were discharged with severe functional deficits.

Conclusions: Helmets demonstrate a protective effect and may be an effective public health intervention to significantly reduce the burden of traumatic brain injury in Cambodia and other developing countries with increasing rates of motorization across the world.     

An investigation of the willingness of managerial employees to accept an expatriate assignment

Data obtained with the aid of structured questionnaires from a Singaporean managerial sample (N = 228) were used to examine receptivity to an expatriate assignment in terms of the cultural similarity or dissimilarity of the country of relocation. Results of a paired t-test indicated that respondents were significantly more receptive to an expatriate assignment in a culturally similar location than in a culturally dissimilar location. Results of hierarchical regression analyses revealed mixed support for the study's propositions and explained only modest amounts of the variance in the culturally similar (R² = 22 per cent) and dissimilar (R² = 20 per cent) models. Limitations of the study, directions for future research and implications of the findings are discussed.     

Occupant responses in conventional and ABTS seats in high-speed rear sled tests

Objective: This study compared biomechanical responses of a normally seated Hybrid III dummy on conventional and all belts to seat (ABTS) seats in 40.2 km/h (25 mph) rear sled tests. It determined the difference in performance with modern (≥2000 MY) seats compared to older (<2000 MY) seats and ABTS seats.

Methods: The seats were fixed in a sled buck subjected to a 40.2 km/h (25 mph) rear sled test. The pulse was a 15 g double-peak acceleration with 150 ms duration. The 50th percentile Hybrid III was lap–shoulder belted in the FMVSS 208 design position. The testing included 11 <2000 MY, 8 ≥2000 MY, and 7 ABTS seats. The dummy was fully instrumented, including head accelerations, upper and lower neck 6-axis load cells, chest acceleration, thoracic and lumbar spine load cells, and pelvis accelerations. The peak responses were normalized by injury assessment reference values (IARVs) to assess injury risks. Statistical analysis was conducted using Student's t test. High-speed video documented occupant kinematics.

Results: Biomechanical responses were lower with modern (≥2000 MY) seats than older (<2000 MY) designs. The lower neck extension moment was 32.5 ± 9.7% of IARV in modern seats compared to 62.8 ± 31.6% in older seats (P =.01). Overall, there was a 34% reduction in the comparable biomechanical responses with modern seats. Biomechanical responses were lower with modern seats than ABTS seats. The lower neck extension moment was 41.4 ± 7.8% with all MY ABTS seats compared to 32.5 ± 9.7% in modern seats (P =.07). Overall, the ABTS seats had 13% higher biomechanical responses than the modern seats.

Conclusions: Modern (≥2000 MY) design seats have lower biomechanical responses in 40.2 km/h rear sled tests than older (<2000 MY) designs and ABTS designs. The improved performance is consistent with an increase in seat strength combined with improved occupant kinematics through pocketing of the occupant into the seatback, higher and more forward head restraint, and other design changes. The methods and data presented here provide a basis for standardized testing of seats. However, a complete understanding of seat safety requires consideration of out-of-position (OOP) occupants in high-speed impacts and consideration of the much more common, low-speed rear impacts.