Pedestrian lower extremity injury risk in car-pedestrian collisions

ABSTRACTThis study aimed to identify the correlations of pedestrian with moderate to untreatable (AIS2+) lower extremity injury risk with the pedestrian kinematics and vehicle front profile variables using real-world accident data. A subsample of 404 pedestrian accident cases with lower extremity injuries was selected from German in-Depth Accident Study (GIDAS) database to conduct statistical analysis. Variance test and logistic regression analysis was performed to analyze associations between selected variables and risk of pedestrian with AIS2+ lower extremtiy injuries. The results revealed that the predicted variables of the impact speed, pedestrian age and weight, the Lower bumper height (LBH) and the Bonnet leading edge height (BLEH) were statistically significant for AIS2+ lower extremity injuries. The higher impact speed, the higher LBH and BLEH corresponded to a greater likelihood of suffering an AIS 2+ lower extremity injury. The results could provide background knowledge for improving pedestrain protective strategies in passenger vehicle design.

This study aimed to identify the correlations of pedestrian AIS2+ lower extremity injury risk with the vehicle front design variables and impact speed by using real-world accident data. A subsample of 404 pedestrian accident cases with AIS1+ lower extremity injuries was selected from German in-Depth Accident Study (GIDAS) database based on a defined sample criterion to conduct statistical analysis. The main variables related to severity of lower extremity injuries were determined at present study, including vehicle impact speed and vehicle design variables: lower bumper height (LBH), upper bumper height (UBH), bumper leading (BL) and bonnet leading edge height (BLEH). Firstly, analysis of variance (ANOVA) was employed to examine whether the mean values of these variables were statistically significance for pedestrian with or without AIS2+ lower extremity injuries. Furthermore, logistic regression analysis was performed to analyze associations between these predicted variables and risk of the pedestrian with AIS2+ lower extremity injury. The results revealed that the predicted variables of the impact speed, the LBH and the BLEH were statistically significant for AIS2+ lower extremity injuries. The higher impact speed, the higher LBH and BLEH correspond to a greater likelihood of suffering an AIS2+ lower extremity injury.

Performance assessment and optimal design of hybrid material bumper for pedestrian lower extremity protection

The influence of passenger car front shape on pedestrian injury risk observed from German in-depth accident data

Background: Knee injuries are common in older adolescent and adult female soccer players, and abnormal valgus knee appearance characterized by low normalized knee separation (NKS) is a proposed injury risk factor. What constitutes normal NKS in younger adolescents and whether low NKS is an injury risk factor are unknown. Purpose: To determine the normal range of NKS using a drop-jump test in female perimenarchal youth soccer players and whether low NKS contributes to lower extremity injuries or knee injuries. Study Design: Cohort study; Level of evidence, 2. Methods: From 2008 to 2012, a total of 351 female elite youth soccer players (age range, 11-14 years) were followed for 1 season, with complete follow-up on 92.3% of players. Baseline drop-jump testing was performed preseason. Lower extremity injuries during the season were identified using a validated, Internet-based injury surveillance system with weekly email reporting. Normalized knee separation at prelanding, landing, and takeoff was categorized 2 ways: as ≤10th percentile (most extreme valgus appearance) compared with >10th percentile and as a continuous measure of 1 SD. Poisson regression modeling with adjustment for clustering by team estimated the relative risk (RR) and 95% confidence interval (CI) of the association between the NKS and the risk of lower extremity and knee injury, stratified by menarche. Results: Of the study participants, 134 players experienced 173 lower extremity injuries, with 43 (24.9%) knee injuries. For postmenarchal players (n = 210), those with NKS ≤10th percentile were at 92% increased risk of lower extremity injury (RR, 1.92; 95% CI, 1.17-3.15) and a 3.62-fold increased risk of knee injury (RR, 3.62; 95% CI, 1.18-11.09) compared with NKS >10th percentile at prelanding and landing, respectively. Among postmenarchal players, there was an 80% increased risk of knee injury (RR, 1.80; 95% CI, 1.01-3.23) with a decrease of 1 SD in landing NKS and a 66% increased risk of knee injury (RR, 1.66; 95% CI, 1.04-2.64) with a decrease of 1 SD in takeoff NKS. Among premenarchal players (n = 141), there was no statistically significant association between the NKS at prelanding, landing, and takeoff and the risk of lower extremity or knee injury. Conclusion: Low NKS was associated with increased risk of lower extremity and knee injury only among postmenarchal players.

Temporal prediction of the lower extremity (LE) injury risk will benefit clinicians by allowing them to better leverage limited resources and target those athletes most at risk. To characterize the instantaneous risk of LE injury by demographic factors of sex, sport, body mass index (BMI), and injury history. Descriptive epidemiologic study. National Collegiate Athletic Association Division I athletic program. A total of 278 National Collegiate Athletic Association Division I varsity student-athletes (119 males, 159 females; age = 19.07 ± 1.21 years, height = 175.48 ± 11.06 cm, mass = 72.24 ± 12.87 kg). Injuries to the LE were tracked for 237 ± 235 consecutive days. Sex-stratified univariate Cox regression models were used to investigate the association between time to first LE injury and sport, BMI, and LE injury history. The instantaneous LE injury risk was defined as the injury risk at any given point in time after the baseline measurement. Relative risk ratios and Kaplan-Meier curves were generated. Variables identified in the univariate analysis were included in a multivariate Cox regression model. Female athletes displayed similar instantaneous LE injury risk to male athletes (hazard ratio [HR] = 1.29; 95% CI= 0.91, 1.83; P = .16). Overweight athletes (BMI >25 kg/m2) had similar instantaneous LE injury risk compared with athletes with a BMI of <25 kg/m2 (HR = 1.23; 95% CI = 0.84, 1.82; P = .29). Athletes with previous LE injuries were not more likely to sustain subsequent LE injury than athletes with no previous injury (HR = 1.09; 95% CI = 0.76, 1.54; P = .64). Basketball (HR = 3.12; 95% CI = 1.51, 6.44; P = .002) and soccer (HR = 2.78; 95% CI = 1.46, 5.31; P = .002) athletes had a higher risk of LE injury than cross-country athletes. In the multivariate model, instantaneous LE injury risk was greater in female than in male athletes (HR = 1.55; 95% CI = 1.00, 2.39; P = .05), and it was greater in male athletes with a BMI of >25 kg/m2 than that in all other athletes (HR = 0.44; 95% CI = 0.19, 1.00; P = .05), but these findings were not significantly different. In a collegiate athlete population, previous LE injury was not a contributor to the risk of future LE injury, whereas being female or being male with a BMI of >25 kg/m2 resulted in an increased risk of LE injury. Clinicians can use these data to extrapolate the LE injury risk occurrence to specific populations.

The lower extremities of cyclists are the most vulnerable body parts in vehicle-bicycle traffic accidents. However, few studies have been conducted on the effects of vehicle front-end profile parameters on cyclist lower extremity injuries by using real accident data. This paper aimed to explore the correlation between the cyclist’s severe lower extremity injury (AIS2+) risk and impact speed, vehicle front-end profile variables, and cyclist parameters via using real cyclist accidents. A subsample of 390 cyclist accident cases with lower extremity injuries was selected from the German In-Depth Accident Study (GIDAS) to conduct statistical analysis. Furthermore, an independent samples t-test was performed to analyse the associations between the selected predictive parameters and the risk of cyclists with AIS2+ lower extremity injuries. Finally, the risk function for cyclists with AIS2+ lower extremity injuries was developed by using the logistic regression method. The research results indicated that vehicle impact speed, lower bumper height (LBH), bumper depth (BD), cyclist age, and weight were statistically significant factors for cyclists with AIS2+ lower extremity injuries. The higher vehicle speed, higher LBH and BD corresponded to a greater likelihood of the cyclist suffering an AIS2+ lower extremity injury. These findings contribute to developing more effective safety measures for vehicle front designs and establishing regulations to protect the lower extremities of cyclists.

Have pedestrian subsystem tests improved passenger car front shape?

ABSTRACTObjective: Though it is common to refer to age-specific groups (e.g., children, adults, elderly), smooth trends conditional on age are mainly ignored in the literature. The present study examines the pedestrian injury risk in full-frontal pedestrian-to–passenger car accidents and incorporates age—in addition to collision speed and injury severity—as a plug-in parameter.Methods: Recent work introduced a model for pedestrian injury risk functions using explicit formulae with easily interpretable model parameters. This model is expanded by pedestrian age as another model parameter. Using the German In-Depth Accident Study (GIDAS) to obtain age-specific risk proportions, the model parameters are fitted to the raw data and then smoothed by broken-line regression.Results: The approach supplies explicit probabilities for pedestrian injury risk conditional on pedestrian age, collision speed, and injury severity under investigation. All results yield consistency to each other in the sense that risks for more severe injuries are less probable than those for less severe injuries. As a side product, the approach indicates specific ages at which the risk behavior fundamentally changes. These threshold values can be interpreted as the most robust ages for pedestrians.Conclusions: The obtained age-wise risk functions can be aggregated and adapted to any population. The presented approach is formulated in such general terms that in can be directly used for other data sets or additional parameters; for example, the pedestrian's sex. Thus far, no other study using age as a plug-in parameter can be found.

This study proposes engineering countermeasures for lowering the possibility of pedestrian lower-extremity injuries. Pedestrian safety tests are commonly performed using anthropometric test device (ATD) subsystems. The lower legform is used to assess lower-extremity injuries during impact. In this study, a computer model of a mechanical surrogate for a pedestrian lower extremity is developed based on the finite element (FE) method. Results from the FE model indicate that the surrogate passes all certification tests proposed by the European Enhanced Vehicle-Safety Committee (EEVC), meaning that the model is biofidelic and suitable for the assessment of lower-extremity injuries due to car-pedestrian impact. In addition, a bumper system is chosen as an example to demonstrate safety evaluation by this pedestrian lower extremity surrogate. Based on the demonstration results, the safety of the bumper system is investigated.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Logistic regression analysis for accident cases of NASS-PCDS (National Automotive Sampling System-Pedestrian Crash Data Study) clearly shows that the extent and the degree of pedestrian's lower extremity injury depend on various factors such as the impact speed, the ratio of the pedestrian height to that of the bonnet leading edge (BLE) of the striking vehicle, bumper to knee ratio, bumper lead angle, age of the pedestrian, and posture of the pedestrian at the time of impact. The pedestrian population is divided in 3 groups, equivalent to small-shorter, medium-height and large-taller pedestrian with respect to the “pedestrian to BLE height-ratio” in order to quantify the degree of influence of lower leg injuries in each group. Large adult male finite element model (95th percentile male: 190 cm and 103 kg) was developed by morphing the Japan Automobile Manufacturers Association (JAMA) 50th percentile male. Lower extremity of developed large male was fine meshed to predict the fractures accurately. A car model was systematically morphed to create different designs having various front end profile dimensions. Large male model with fine meshed lower extremity was impacted against those series of morphed vehicle models. Effect of vehicle's front end profile on lower extremity bone injuries was evaluated by accident analysis of PCDS data and their trends are verified by FE simulation of large male HBM. The results from accident analysis had good correlation with those obtained from FE simulations.&lt;/div&gt;&lt;/div&gt;

Background: Previous research has identified higher pedestrian injury rates in London among ‘Black’&#13;\nchildren and lower rates among ‘Asian’ children, compared to ‘White’ children. Whilst area affluence&#13;\nprotects ‘White’ and ‘Asian’ from pedestrian injury, this is not true for ‘Black’ children. The&#13;\nmechanisms linking ethnicity, disadvantage and child pedestrian injury risk remain poorly&#13;\nunderstood.&#13;\nAims: To investigate a series of hypotheses about how ethnicity is related to pedestrian injury risk in&#13;\nLondon&#13;\nMethods: Five studies analysed quantitative data sources to: (i) identify any ethnic differences in&#13;\nthe quality of the road environment where children live; (ii) estimate the quantity of travel-time that&#13;\nchildren spend exposed to road traffic; (iii) examine whether night-time exposure is more hazardous&#13;\nfor minority ethnic children; (iv) explore the relationship between ethnicity, deprivation and injury&#13;\nrisk controlling for the quantity and quality of pedestrian exposure; and (v) examine whether ‘group&#13;\ndensity’ effects can shed light on the relationship between ethnicity, deprivation and injury risk.&#13;\nResults: There was little evidence of differences in the quality of the road environment where&#13;\n‘White’, ‘Black’ and ‘Asian’ children live. There was no evidence of a difference in the quantity of&#13;\ntravel-time pedestrian exposure between ‘White’ and ‘Black’ children and some evidence that&#13;\n‘Asian’ children walk less than their counterparts. There was no evidence that night-time exposure is&#13;\nmore hazardous for minority ethnic children. Controlling for the quantity and quality of exposure&#13;\nchanged the relationship between ethnicity, deprivation, and injury risk such that rates among&#13;\n‘Black’ children were highest in the most affluent areas. ‘Group density’ effects may explain these&#13;\nfindings.&#13;\nConclusions: The quantity and quality of exposure are important mediators of child pedestrian&#13;\ninjury risk, although there was little evidence that they explain ethnic inequalities. The findings from&#13;\nthis thesis suggest that that the meaning of pedestrian exposure plays a crucial role in complex&#13;\npathways linking ethnicity to injury risk. Further investigation of individual causal explanations may&#13;\nhave diminishing returns, given the evidence from this study that ethnic differences result from&#13;\ninter-related mechanisms.

This study quantifies the spatiotemporal risk of pedestrian and bicyclist injury in New York City at the census tract level over a recent 10-year period, identifies areas of increased risk, and evaluates the role of socioeconomic and traffic-related variables in injury risk. Crash data on 140,835 pedestrian and bicyclist injuries in 1908 census tracts from 2001 to 2010 were obtained from the New York City Department of Transportation. We analyzed injury counts within census tracts with Bayesian hierarchical spatial models using integrated nested Laplace approximations. The model included variables for social fragmentation, median household income, and average vehicle speed and traffic density, as well as a spatially unstructured random effect term, a spatially structured conditional autoregression term, a first-order random walk-correlated time variable, and an interaction term for time and place. Incidence density ratios, credible intervals, and probability exceedances were calculated and mapped. The yearly rate of crashes involving injuries to "pedestrians" (including bicyclists) decreased 16.2% over the study period, from 23.7 per 10,000 population to 16.2 per 10,000. The temporal term in the spatiotemporal model indicated that much of the decrease over the study period occurred during the first 4 years of the study period. Despite an overall decrease, the model identified census tracts that were at persistently high risk of pedestrian injury throughout the study period, as well as areas that experienced sporadic annual increases in risk. Aggregate social, economic, and traffic-related measures were associated with pedestrian injury risk at the ecologic level. Every 1-unit increase in a standardized social fragmentation index was associated with a 19% increase in pedestrian injury risk (incidence density ratio = 1.19 [95% credible interval = 1.16 - 1.23]), and every 1 standardized unit increase in traffic density was associated with a 20% increase in pedestrian injury risk (1.20 [1.15 - 1.26]). Each 10-mile-per-hour increase in average traffic speed in a census tract was associated with a 24% decrease in pedestrian injury risk (0.76 [0.69 - 0.83]). The risk of a pedestrian or bicyclist being struck by a motor vehicle in New York City decreased from 2001 to 2004 and held fairly steady thereafter. Some census tracts in the city did not benefit from overall reductions or experienced sporadic years of increased risk compared with the city as a whole. Injury risk at the census tract level was associated with social, economic, and traffic-related factors.

Sport-related concussions (SRCs) are now classified as a major health concern affecting athletes across all sporting levels, with recent evidence suggesting upwards of 3.8 million SRCs occur each year. Multiple injury surveillance datasets have recently determined that athletes post-SRC, compared to non-concussed counterparts, are at greater risk for lower extremity (LE) injury beyond the resolution of traditional SRC assessment batteries. However, it is presently uncertain if common clinical practices (symptom reporting, neuropsychological (NP) examination, and static postural control analysis) can determine athletes at risk for LE injury following an SRC. A comprehensive review of the literature determined that these tools may not reveal subtle cognitive and neuromuscular deficits that lead to subsequent LE injury during dynamic sporting tasks. Current return-to-play (RTP) protocols should consider clarifying the addition of specific objective locomotor analysis, such as gait tasks and sport-specific maneuvers, to determine the risk of LE injury after an athlete has sustained an SRC.

Objective: To investigate the relative likelihood of pedestrian head injuries based on person, vehicular, and environmental factors in China. Methods: A team was established to collect passenger car–pedestrian accident cases occurring between 2006 and 2011 in Beijing, Shanxi Province, and Chongqing, China. Some key variables for person-, vehicle-, and environment-related factors on head injuries were analyzed using multivariate logistic regression analysis to determine relative risk/likelihood. Pedestrians were classified according to injury outcome and age. Pedestrian head injuries were scored using the Abbreviated Injury Scale (AIS). Results: A total of 285 vehicle–pedestrian crashes were collected and analyzed: 30 in Beijing, 20 in Shanxi Province, and 235 in Chongqing. The distribution in age and road type by study location differed. The injury outcome, head injury severity, and head contact site were different among 4 age groups. The variables including head contact site and impact speed were the common determinants for head injury severity. A higher pedestrian fatality risk was associated with age over 46, impact speeds over 40 km/h, and higher likelihoods of the victim's head striking the windscreen frame/A pillar and of the victim sustaining a head injury. Similarly, a higher risk of head injury was associated with being female, age over 60, impact speeds over 40 km/h, and a likelihood of the victim's head striking the vehicle rather than the ground. Impact speeds of over 40 km/h and head contact site on windscreen frame/A pillar retained a strong association with severe head injury (AIS 5–6) rate. Conclusions: Pedestrian age, vehicle impact speed, and head contact site were common pertinent factors for the risk of pedestrian head injury and the risk of death. Further studies would be valuable to fully characterize vehicle–pedestrian crashes in China and to develop targeted injury prevention strategies based on surveillance results. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.