Crash Injury Research Engineering Network Research Articles

Determination of distal fibula fracture for prediction of ankle injuries

Objective This study quantified the local fracture tolerance of the distal fibula. The purpose of this data is to refine the understanding of ankle fracture tolerance in the population and enhance injury prediction by computational tools. Methods Fracture patterns of the fibula were obtained from the US National Highway Traffic Safety Administration (NHTSA) Crash Injury Research Engineering Network (CIREN). Of 143 cases of ankle injury, 120 included fibula fracture, many of which accompanied by radiology images. The most common fibula fracture type was a Weber C fracture, which was then used as the testing target to replicate with postmortem human surrogates. Isolated distal fibulae (male and female, across a wide anthropometric range) were subjected to quasi-static lateral-medial four-point bending superimposed on axial precompression. Results Of the 20 specimens tested, 17 fractured in compression and bending, two fractured in compression, bending, and shear, and one did not fracture upon the imposed displacement. Fractures occurring outside of the target testing span were treated as right-censored data points. Fracture patterns varied among specimens, with oblique fractures being most common, followed by segmental fractures. At failure, compressive force ranged from 77 N to 370 N and bending moment from 17 Nm to 47 Nm. Conclusions From the 19 fractured specimens, the variety of fracture patterns observed were generally consistent with the range of fibula fracture types and locations commonly observed in the field. While comparative studies with fibula specimens are largely absent from literature, comparison of this study to other long bones (radius and ulna) show that bending moment at fracture is similar. To the author’s knowledge, this is the first study to quantify the fracture tolerance of isolated distal fibulae under loading conditions representative of ankle injury mechanisms in motor vehicle collisions. By combining the results of this study with complementary results from parallel tibia-focused experiments (currently in-press), these results will aid development of tissue-level lower leg fracture prediction of human body models, thus enhancing prediction of ankle injury during safety assessment simulations. Specifically, the fracture tolerance information might generate an injury risk function to guide tissue-level injury prediction with human body models.

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

IntroductionInvestigating biomechanics of injury patterns from motor vehicle collisions (MVCs) informs improvements in vehicle safety. This study aims to investigate two-vehicle MVCs involving a passenger car and specific injury patterns associated with sources of injury, collision biomechanics, vehicle properties, and patient outcomes. MethodsRetrospective cohort study conducted to evaluate the biomechanics of specific injury patterns seen in MVCs involving passenger cars using the Crash Injury Research Engineering Network database between the years 2005 and 2015. ResultsA total of 631 MVC cases were included from 2005 to 2015. The majority of cases involved injuries to the head or neck, the thorax, and the abdomen (80.5%). Head/neck injuries from the steering wheel were associated with significantly higher injury severity score compared to those from seatbelts (26.11 versus 18.28, P < 0.001) and airbags (26.11 versus 20.10, P = 0.006), as well as a >6-fold higher fatality rate (P = 0.019). Thoracic injuries caused by the center console were twice as likely to be fatal than those caused by the seatbelt (P = 0.09). ConclusionsOccupants suffering injuries to the head/neck, the thorax, and the abdomen had higher injury severity score and fatality rates compared to other body regions, demonstrating that manufacturing and safety guidelines should focus on minimizing these injury patterns. Head/neck injuries caused by the steering wheel were associated with worse outcomes compared to those caused by seatbelts and airbags, further emphasizing the benefits of these critical safety features. Integration of innovative safety features like center-mounted airbags may improve occupant safety.

Nationwide Analysis of Biomechanics of Motor Vehicle Collisions Involving Passenger Vehicle and Associated Outcomes: Towards Improving Vehicle Safety Standards and Regulations.

Motor vehicle collisions (MVCs) pose significant mortality and economic burden on the United States. Biomechanics research may guide future vehicle innovation. The objective of this study is to investigate the biomechanics of two-vehicle MVCs involving passenger vehicle (PV) to evaluate associated injury patterns and outcomes including mortality. A retrospective cohort study of cases from the Crash Injury Research Engineering Network database was performed to evaluate the biomechanics (angle of impact, seatbelt use, and airbag deployment) of two-vehicle MVCs involving at least one PV from 2005-2015. Out of 629 MVCs evaluated, lateral collisions were most common (49.5%), followed by head-on (41.3%) and rear-end (9.2%) collisions. Thoracic injuries accounted for 30.1%, 31.4%, and 31.1% of injuries in lateral, head-on, and rear-end collisions, respectively, and were the most common body region injured for all collision types. Seatbelt use was associated with shorter ICU stay (10.9 vs 19.1days, P = .036) and mortality (Cramer's V = .224, P < .001), but a greater average number of injuries (10.2 injuries vs 8.6 injuries, P = .011). Passenger vehicle are commonly involved in MVCs nationwide and efforts are needed to prevent occupant injuries and fatalities. The incorporation of energy-absorbing material into common points of contact within the vehicle interior may decrease the severity of these injuries. Seatbelt use remains a protective factor against MVC-fatalities but is associated with collateral injuries and should be a focus of further innovation.

Belt-induced abdominal injuries in recent frontal impact CIREN cases

Objective The objective is to report sex-related variation in 3-point belt–related abdominal injuries in Crash Injury Research Engineering Network (CIREN) cases. Methods A query of CIREN cases was made for those with the highest ranked Collision Deformation Classification (CDC) to the front plane, a principal direction of force (PDOF) ±20° from 0°, and Abbreviated Injury Scale (AIS) 2+ abdomen injuries attributed to the seat belt. Patterns of injury were categorized as above the crest of the ilium, injuries below the crest of the ilium, and injuries above and below the ilium. This was done in the context of autonomous vehicle occupant kinematics testing results. Twelve 5th and 95th percentile 3-point belt–restrained postmortem human subjects were subjects; test speeds and recline angles varied. Abdomen injuries were anticipated; none were observed. Results Thirty-five occupants with belt-related abdominal injuries were identified. Seventeen case occupants sustained an injury only within the pelvic contents: 5 women and 12 men. Nine of the 17 were at or above the 81st percentile for height, 13 were between the 62nd and 80th percentile for height, and 4 were less than the 50th percentile for height. Conclusions The stature component of the body mass index (BMI) appears to be a plausible candidate for an independent variable that is a contributing factor explaining the incidence of pelvic contents injuries when a 3-point belt–restrained occupant is involved in a frontal impact.

Automated Spleen Injury Detection Using 3D Active Contours and Machine Learning

The spleen is one of the most frequently injured organs in blunt abdominal trauma. Computed tomography (CT) is the imaging modality of choice to assess patients with blunt spleen trauma, which may include lacerations, subcapsular or parenchymal hematomas, active hemorrhage, and vascular injuries. While computer-assisted diagnosis systems exist for other conditions assessed using CT scans, the current method to detect spleen injuries involves the manual review of scans by radiologists, which is a time-consuming and repetitive process. In this study, we propose an automated spleen injury detection method using machine learning. CT scans from patients experiencing traumatic injuries were collected from Michigan Medicine and the Crash Injury Research Engineering Network (CIREN) dataset. Ninety-nine scans of healthy and lacerated spleens were split into disjoint training and test sets, with random forest (RF), naive Bayes, SVM, k-nearest neighbors (k-NN) ensemble, and subspace discriminant ensemble models trained via 5-fold cross validation. Of these models, random forest performed the best, achieving an Area Under the receiver operating characteristic Curve (AUC) of 0.91 and an F1 score of 0.80 on the test set. These results suggest that an automated, quantitative assessment of traumatic spleen injury has the potential to enable faster triage and improve patient outcomes.

A multivariate approach for modeling driver injury severity by body region

Road traffic crashes remain a major concern globally resulting in loss of life and worsening the quality of life and productivity of the crash survivors. The current study contributes to road safety literature by focusing on developing high resolution crash severity models based on driver injury severity reported using Abbreviated Injury Scale (AIS) by body region. For this purpose, the research develops a joint random parameters multivariate model structure with as many dimensions as severity by body location. The proposed model system is developed using Crash Injury Research Engineering Network (CIREN) data, which includes patients admitted to trauma centers due to a crash from 2005 to 2015. The dataset contained information about a comprehensive set of exogenous variables including driver characteristics, vehicle characteristics, crash characteristics, roadway characteristics, and environmental characteristics. The empirical analysis involves the estimation of Random Parameters Multivariate Generalized Ordered Probit Model that allows for the influence of common unobserved factors affecting the vehicle occupant severity across body locations. The model estimation results are further augmented by conducting elasticity analysis to highlight the differential impact of various factors on severity across body regions.

Motor Vehicle Crash-Related Subdural Hematoma from Real-World Head Impact Data

Abstract Approximately 1,700,000 people sustain a traumatic brain injury (TBI) each year and motor vehicle crashes (MVCs) are a leading cause of hospitalization from TBI. Acute subdural hematoma (SDH) is a common intracranial injury that occurs in MVCs associated with high mortality and morbidity rates. In this study, SDH volume and midline shift have been analyzed in order to better understand occupant injury by correlating them to crash and occupant parameters. Fifty-seven head computed tomography (CT) scans were selected from the Crash Injury Research Engineering Network (CIREN) with Abbreviated Injury Scale (AIS) level 3+ SDH. Semi-automated methods were used to isolate the intracranial volume. SDH and additional occupant intracranial injuries were segmented across axial CT images, providing a total SDH injury volume. SDH volume was correlated to crash parameters and occupant characteristics. Results show a positive correlation between SDH volume and crash severity in near-side and frontal crashes. Additionally, the location of the resulting hemorrhage varied by crash type. Those with greater SDH volumes had significantly lower Glasgow Coma Scale (GCS) scores at the crash site in near-side crashes. Age and fracture type were found to be significant contributors to SDH volume. This study is a volumetric analysis of real world brain injuries and known MVC impacts. The results of this study demonstrate a relationship among SDH volume, crash mechanics, and occupant characteristics that provide a better understanding of the injury mechanisms of MVC-associated TBI.

Association between side-impact airbag deployment and risk of injury

Side-impact airbags (SABs) are designed to protect the head and thorax during a side-impact motor vehicle collision (MVC). Research on the effectiveness of SAB deployment has been limited. The objective of this study was to assess the effectiveness of deployed SABs in reducing head and thoracic injuries during side-impact MVCs. The 2000-2009 National Automotive Sampling System-Crashworthiness Data System and the Crash Injury Research Engineering Network databases were used to evaluate front seat occupants involved in side-impact MVCs using a matched cohort study design. The risk of serious head and thoracic injuries for occupants with and without deployed SABs were compared. Occupants in vehicles with a deployed SAB designed to protect the head had a 30% lower risk of head injuries with an Abbreviated Injury Scale score of 2+ (relative risk [RR], 0.70; 95% confidence interval [CI], 0.51-0.97). Regarding thoracic injury, occupants in vehicles with a deployed SAB designed to protect the torso had a risk of injury similar to that of occupants without a deployed SAB (RR, 0.99; 95% CI, 0.79-1.24), although the risk increased for occupants 50 years and older (RR, 1.27; 95% 0.84-1.93). The results of the current suggest that although SABs protect occupants from head injury, the protective effect for thoracic injury is limited. Future research should focus on whether the association with thoracic injury is modified by occupant seating posture. Prognostic study, level III.

Age: Is It All in the Head? Factors Influencing Mortality in Elderly Patients With Head Injuries

Elderly patients, an increasing segment of the population, who sustain traumatic brain injury (TBI) are known to have worse outcomes, including higher mortality. This objective of this study was to examine the Crash Injury Research Engineering Network and to determine at what age motor vehicle crash fatalities from head injuries increased. The Crash Injury Research Engineering Network database was queried from 1996 to 2009. Study inclusion criteria were adult vehicle occupants with TBI, with an Abbreviated Injury Scale score ≥2. The age at which mortality increased was calculated. Patients younger and older than this cutoff age were compared to determine differences in crash characteristics. The determined cutoff age was compared with one found in a larger, population-based database. There were 915 patients who met the study criteria. An increase in mortality was seen at age 60 years despite no difference in Injury Severity Score and a decrease in crash severity. Patients ≤60 years were more likely to have alcohol involved, to be in a rollover crash, and had higher crash speeds. Comparing the element of the crash attributed to the head injury, the patients >60 years were more likely to have struck the airbag, door, and seat. An analysis of the larger database revealed an increase in mortality at age 70 years. There was a higher mortality secondary to head injuries in those older than 60 years involved in motor vehicle crashes. Improved safety measures in vehicle design may decrease the number of head injuries seen in the older population.

BioTab—A New Method for Analyzing and Documenting Injury Causation in Motor-Vehicle Crashes

Objective: To describe a new method for analyzing and documenting the causes of injuries in motor vehicle crashes that has been implemented since 2005 in cases investigated by the Crash Injury Research Engineering Network (CIREN). Methods: The new method, called BioTab, documents injury causation using evidence from in-depth crash investigations. BioTab focuses on developing injury causation scenarios (ICSs) that document all factors considered essential for an injury to have occurred as well as factors that contributed to the likelihood and/or severity of an injury. The elements of an injury causation scenario are (1) the source of the energy that caused the injury, (2) involved physical components (IPCs) contacted by the occupant that are considered necessary for the injury to have occurred, (3) the body region or regions contacted by each IPC, (4) the internal paths between body regions contacted by IPCs and the injured body region, (5) critical intrusions of vehicle components, and (6) factors that contributed to the likelihood and/or the severity of injury. Results: Advantages of the BioTab method are that it • attempts to identify all factors that cause or contribute to clinically significant injuries, • allows for coding of scenarios where one injury causes another injury, • associates injuries with a source of energy and allows injuries to be associated with sources of energy other than the crash, such as air bag deployment energy, • allows for documenting scenarios where an injury was caused by two different body regions contacting two different IPCs, • identifies and documents the evidence that supports ICSs and IPCs, • assigns confidence levels to ICSs and IPCs based on available evidence, and • documents body region and organ/component-level “injury mechanisms” and distinguishes these mechanisms from ICSs. Conclusion: The BioTab method provides for methodical and thorough evidenced-based analysis and documentation of injury causation in motor vehicle crashes.

Occupant and Crash Characteristics for Case Occupants With Cervical Spine Injuries Sustained in Motor Vehicle Collisions

Motor vehicle collisions (MVCs) are the leading cause of spine and spinal cord injuries in the United States. Traumatic cervical spine injuries (CSIs) result in significant morbidity and mortality. This study was designed to evaluate both the epidemiologic and biomechanical risk factors associated with CSI in MVCs by using a population-based database and to describe occupant and crashes characteristics for a subset of severe crashes in which a CSI was sustained as represented by the Crash Injury Research Engineering Network (CIREN) database. Prospectively collected CIREN data from the eight centers were used to identify all case occupants between 1996 and November 2009. Case occupants older than 14 years and case vehicles of the four most common vehicle types were included. The National Automotive Sampling System's Crashworthiness Data System, a probability sample of all police-reported MVCs in the United States, was queried using the same inclusion criteria between 1997 and 2008. Cervical spinal cord and spinal column injuries were identified using Abbreviated Injury Scale (AIS) score codes. Data were abstracted on all case occupants, biomechanical crash characteristics, and injuries sustained. Univariate analysis was performed using a χ analysis. Logistic regression was used to identify significant risk factors in a multivariate analysis to control for confounding associations. CSIs were identified in 11.5% of CIREN case occupants. Case occupants aged 65 years or older and those occupants involved in rollover crashes were more likely to sustain a CSI. In univariate analysis of the subset of severe crashes represented by CIREN, the use of airbag and seat belt together (reference) were more protective than seat belt alone (odds ratio [OR]=1.73, 95% confidence interval [CI]=1.32-2.27) or the use of neither restraint system (OR=1.45, 95% CI=1.02-2.07). The most frequent injury sources in CIREN crashes were roof and its components (24.8%) and noncontact sources (15.5%). In multivariate analysis, age, rollover impact, and airbag-only restraint systems were associated with an increased odds of CSI. Using the population-based National Automotive Sampling System's Crashworthiness Data System data, 0.35% of occupants sustained a CSI. In univariate analysis, older age was noted to be a significant risk factor for CSI. Airbag-only restraint systems and both rollover and lateral crashes were also identified as risk factors for CSI. In addition, increasing delta v was highly associated with CSIs. In multivariate analysis, similar risk factors were noted. Of all the restraint systems, seat belt use without airbag deployment was found to be the most protective restraint system (OR=0.29, 95% CI=0.16-0.50), whereas airbag-only restraint was associated with the highest risk of CSI (OR=3.54, 95% CI=2.29-5.46). Despite advances in automotive safety, CSIs sustained in MVC continue to occur too often. Older case occupants are at an increased risk of CSI. Rollover crashes and severe crashes led to a much higher risk of CSI than other types and severity of MVCs. Seat belt use is very effective in preventing CSI, whereas airbag deployment may increase the risk of occupants sustaining a CSI. More protection for older occupants is needed and protection in both rollover and lateral crashes should remain a focus of the automotive industry. The design of airbag restraint systems should be evaluated so that they are not causative of serious injury. In addition, engineers should continue to focus on improving automotive design to minimize the risk of spinal injury to occupants in high severity crashes.

Crash Test Ratings and Real-World Frontal Crash Outcomes: A CIREN Study

To establish whether the Insurance Institute for Highway Safety (IIHS) offset crash test ratings are linked to different mortality rates in real world frontal crashes. The study used Crash Injury Research Engineering Network drivers of age older than 15 years who were involved in frontal crashes. The Crash Injury Research Engineering Network is a convenience sample of persons injured in crashes with at least one Abbreviated Injury Scale score of 3+ injury or two Abbreviated Injury Scale score of 2+ injuries who were either treated at a Level I trauma center or died. Cases were grouped by IIHS crash test ratings (i.e., good, acceptable, marginal, poor, and not rated). Those rated marginal were excluded because of their small numbers. Mortality rates experienced by these ratings-based groups were compared using the Mantel-Haenszel chi test. Multiple logistic regression models were built to adjust for confounders (i.e., occupant, vehicular, and crash factors). A total of 1,226 cases were distributed within not rated (59%), poor (12%), average (16%), and good (14%) categories. Those rated good and average experienced a lower unadjusted mortality rate. After adjustment by confounders, those in vehicles rated good experienced a lower risk of death (adjusted OR 0.38 [0.16-0.90]) than those in vehicles rated poor. There was no significant effect for "acceptable" rating. Other factors influencing the occurrence of death were age, DeltaV >or=70 km/h, high body mass index, and lack of restraint use. After adjusting for occupant, vehicular, and crash factors, drivers of vehicles rated good by the IIHS experienced a lower risk of death in frontal crashes.

The Utility of Seat Belt Signs to Predict Intra-Abdominal Injury Following Motor Vehicle Crashes

Objective: Safety belts are the most important safety system in motor vehicles and should always be worn to prevent serious injury. The purpose of this study, using Crash Injury Research Engineering Network (CIREN) data, was to assess occupant and crash factors associated with minor contusions and abrasions caused by the safety belt (commonly referred to as seat belt signs) and their association with serious intra-abdominal trauma. Methods: CIREN data were used to determine which factors are associated with seat belt signs. Occupant variables (age, gender, body mass index, proper safety belt use, driver v. passenger status) and crash variables (crash type, crash severity, and airbag deployment) were compared for occupants with seat belt sign who had serious (AIS 3 or greater) intra-abdominal injury and those who did not have intra-abdominal injuries. Adjusted odds ratios were used to quantify the independent association between predictive factors for serious intra-abdominal injury for occupants with seat belt signs. Results: Of 1539 occupants included in this study, 419 had a positive seat belt signs. Of those 419 occupants, 100 had serious intra-abdominal injury and 319 did not. Being in the passenger seat position increased the odds, whereas front airbag deployment and frontal impact were associated with decreased odds of serious intra-abdominal injury for occupants with seat belt signs. However, multivariate analysis showed only that being a passenger increased the odds (OR = 2.64) of having serious intra-abdominal injury for occupants with seat belt signs when other factors, including crash severity and type of impact, were controlled for in the analysis. Conclusions: Seat belt signs remain an important physical finding in patients with intra-abdominal injury following motor vehicle crashes. Front seat passengers presenting with seat belt signs were more than twice as likely to sustain intra-abdominal injury; thus, emergency physicians and trauma surgeons should be aware of passenger position when evaluating a seat belt sign.

Appropriate analysis of CIREN data: Using NASS-CDS to reduce bias in estimation of injury risk factors in passenger vehicle crashes

The Crash Injury Research Engineering Network (CIREN) database contains detailed medical and crash information on a large number of severely injured occupants in motor vehicle crashes. CIREN's major limitation for stand-alone analyses to explore injury risk factors is that control subjects without a given injury type must have another severe injury to be included in the database. This leads to bias toward the null in the estimation of risk associations. One method to cope with this limitation is to obtain information about occupants without a given injury type from the National Automotive Sampling System's Crashworthiness Data System (NASS-CDS), which is a probability sample of towaway crashes, containing similar crash information, but less medical detail. Combining CIREN and NASS-CDS in this manner takes advantage of the increased sample size when outcomes are available in both datasets; otherwise NASS-CDS can serve as a sample of controls to be combined with CIREN cases, possibly under a sensitivity analysis that includes and excludes NASS-CDS subjects whose status as a control is uncertain. Because CIREN is not a probability sample of crashes that meet its inclusion criteria, we develop a method to estimate the probability of selection for the CIREN cases using data from NASS-CDS. These estimated probabilities are then used to compute “pseudo-weights” for the CIREN cases. These pseudo-weights not only allow for reduced bias in the estimation of risk associations, they allow direct prevalence estimates to be made using medical outcome data available only in CIREN. We illustrate the use of these methods with both simulation studies and application to estimation of prevalence and predictors of AIS 3+ injury risk to head, thorax, and lower extremity regions, as well as prevalence and predictors of acetabular pelvic fractures. Results of these analyses demonstrate combining NASS and CIREN data can yield improvements in mean square error and nominal confidence interval coverage over analyses that use either the NASS-CDS or the CIREN sample alone.

Association of Contact Loading in Diffuse Axonal Injuries From Motor Vehicle Crashes

Although studies have been conducted to analyze brain injuries from motor vehicle crashes, the association of head contact has not been fully established. This study examined the association in occupants sustaining diffuse axonal injuries (DAIs). The 1997 to 2006 motor vehicle Crash Injury Research Engineering Network database was used. All crash modes and all changes in velocity were included; ejections and rollovers were excluded; injuries to front and rear seat occupants with and without restraint use were considered. DAI were coded in the database using Abbreviated Injury Scale 1990. Loss of consciousness was included and head contact was based on medical- and crash-related data. Sixty-seven occupants with varying ages were coded with DAI. Forty-one adult occupants (mean, 33 years of age, 171-cm tall, 71-kg weight; 30 drivers, 11 passengers) were analyzed. Mean change in velocity was 41.2 km/h and Glasgow Coma Scale score was 4. There were 33 lateral, 6 frontal, and 2 rear crashes with 32 survivors and 9 were fatalities. Two occupants in the same crash did not sustain DAI. Although skull fractures and scalp injuries occurred in some impacts, head contact was identified in all frontal, rear, and far side, and all but one nearside crashes. Using a large sample size of occupants sustaining DAI in 1991 to 2006 model year vehicles, DAI occurred more frequently in side than frontal crashes, is most commonly associated with impact load transfer, and is not always accompanied by skull fractures. The association of head contact in >95% of cases underscores the importance of evaluating crash-related variables and medical information for trauma analysis. It would be prudent to include contact loading in addition to angular kinematics in the analysis and characterization of DAI.

The influence of damage distribution on serious brain injury in occupants in frontal motor vehicle crashes

In spite of improvements in motor vehicle safety systems and crashworthiness, motor vehicle crashes remain one of the leading causes of brain injury. The purpose of this study was to determine if the damage distribution across the frontal plane affected brain injury severity of occupants in frontal impacts. Occupants in “head on” frontal impacts with a Principal Direction of Force (PDOF) equal to 11, 12, or 1 o’clock who sustained serious brain injury were identified using the Crash Injury Research Engineering Network (CIREN) database. Impacts were further classified based on the damage distribution across the frontal plane as distributed, offset, and extreme offset (corner). Overall, there was no significant difference for brain injury severity (based on Glasgow Coma Scale < 9, or brain injury AIS > 2) comparing occupants in the different impact categories. For occupants in distributed frontal impacts, safety belt use was protective (odds ratio (OR) = 0.61) and intrusion at the occupant's seat position was four times more likely to result in severe (Glasgow Coma Scale (GCS) < 9) brain injury (OR = 4.35). For occupants in offset frontal impacts, again safety belt use was protective against severe brain injury (OR = 0.25). Possibly due to the small number of brain-injured occupants in corner impacts, safety belts did not significantly protect against increased brain injury severity during corner impacts. This study supports the importance of safety belt use to decrease brain injury severity for occupants in distributed and offset frontal crashes. It also illustrates how studying “real world” crashes may provide useful information on occupant injuries under impact circumstances not currently covered by crash testing.

Do Initial Radiographs Agree With Crash Site Mechanism of Injury in Pelvic Ring Disruptions? A Pilot Study

Direction of injury force inferred from pelvic radiographs may be used in trauma care to predict associated injuries and guide intervention. Our objective was to compare injury direction determined from anteroposterior (AP) pelvic radiographs with injury forces determined from crash site investigation. We studied all 28 subjects from the Crash Injury Research Engineering Network (CIREN) database who met inclusion criteria of pelvic ring disruption, single-event crash, restrained front-seat occupant, diagnostic-quality pelvic radiography, and complete crash investigation data. Assessment of diagnostic quality of pelvic radiography was made by 2 radiologists who were blinded to all other subject information. Crash site investigation data included principal direction of force (PDOF), crash magnitude, and passenger compartment intrusion. An orthopedic trauma surgeon and a fellowship-trained emergency radiologist independently assessed the pelvic radiographs to determine the injury PDOF and the Young-Burgess and Tile fracture classifications, with disputes resolved by an additional emergency radiologist. Agreement between injury forces and pelvic radiographs was assessed using the kappa statistic. The PDOF was anterior in 9 (32%) and lateral in 19 (68%) subjects. The readers agreed with the crash primary direction of force in 21 (75%) subjects (kappa=0.42). In subjects with lateral PDOF, agreement was 89% (17/19) compared to 44% for anterior PDOF (4/9). Interobserver agreement for the Young and Tile classification schemes was moderate (weighted kappa 0.44 and 0.54, respectively). Crash site investigation and pelvic radiography may provide conflicting information about primary direction of injuring forces. Presumed anterior impact based on PDOF is not in consistent agreement with the pattern of injury evident on the AP pelvic radiograph.

Motor Vehicle-Related Cardiac and Aortic Injuries Differ From Other Thoracic Injuries

Traumatic cardiac and thoracic aortic injuries are hypothesized to result from rapid deceleration of occupants during a motor vehicle crash. The purpose of this study was to identify potential risk factors for motor vehicle-related cardiac and thoracic aortic (HTA) injury using the Crash Injury Research Engineering Network (CIREN) database. CIREN data were used to test the hypothesis that there is no difference between occupants with HTA injury and occupants with thoracic injury other than the heart or aorta (non-HTA). Occupant variables (restraint use, airbag deployment, Glasgow Coma Scale score, Injury Severity Score, concomitant injuries, driver versus passenger status, height, and comorbidity) and crash variables (principal direction of force, change in velocity, vehicle crush, intrusion, and vehicle type) were compared for these two groups. Odds ratios were used to quantify the potential risk factors for HTA injury compared with non-HTA injury. There were 168 occupants with an HTA injury and 731 with a non-HTA injury. Greater crash severity (based on vehicle crush and change in velocity), improper safety belt use, and lack of safety belt use were significantly associated with HTA injury. Unrestrained occupants had almost three times the chance of having an HTA injury (odds ratio = 2.86; p < 0.05). For restrained drivers, 41.4% of HTA injuries were caused by vehicle interior components. When not protected by both safety belts and air bags, 45.7% of driver HTA injuries were caused by the steering wheel. For passengers, the vehicle interior (armrests, side interior, and B-pillars) accounted for most HTA injuries regardless of safety system status. More than half of all occupants wearing safety belts who sustained an HTA injury were improperly wearing their safety belts. The high mortality associated with cardiac and aortic injuries supports the need to prevent these injuries from occurring during motor vehicle crashes. These results suggest proper use of safety belts is necessary to prevent cardiac and thoracic aortic injuries. However, other important potential risk factors, such as motor vehicle size and crash severity, might continue to present a challenge to motor vehicle safety professionals.

Factors influencing pediatric Injury Severity Score and Glasgow Coma Scale in pediatric automobile crashes: results from the Crash Injury Research Engineering Network

Background/Purpose Motor vehicle crashes account for more than 50% of pediatric injuries. Triage of pediatric patients to appropriate centers can be based on the crash/injury characteristics. Pediatric motor vehicle crash/injury characteristics can be determined from an in vitro laboratory using child crash dummies. However, to date, no detailed data with respect to outcomes and crash mechanism have been presented with a pediatric in vivo model. Methods The Crash Injury Research Engineering Network is comprised of 10 level 1 trauma centers. Crashes were examined with regard to age, crash severity (Δ V), crash direction, restraint use, and airbag deployment. Multiple logistic regression analysis was performed with Injury Severity Score (ISS) and Glasgow Coma Scale (GCS) as outcomes. Standard age groupings (0-4, 5-9, 10-14, and 15-18) were used. The database is biases toward a survivor population with few fatalities. Results Four hundred sixty-one motor vehicle crashes with 2500 injuries were analyzed (242 boys, 219 girls). Irrespective of age, Δ V > 30 mph resulted in increased ISS and decreased GCS (eg, for 0-4 years, Δ V < 30: ISS = 10, GCS = 13.5 vs Δ V > 30: ISS = 19.5, GCS = 10.6; P < .007, < .002, respectively). Controlling for Δ V, children in lateral crashes had increased ISS and decreased GCS versus those in frontal crashes. Airbag deployment was protective for children 15 to 18 years old and resulted in a lower ISS and higher GCS (odds ratio, 2.1; 95% confidence interval, 0.9-4.6). Front-seat passengers suffered more severe (ISS > 15) injuries than did backseat passengers (odds ratio, 1.7; 95% confidence interval, 0.7-3.4). A trend was noted for children younger than 12 years sitting in the front seat to have increased ISS and decreased GCS with airbag deployment but was limited by case number. Conclusion A reproducible pattern of increased ISS and lower GCS characterized by high severity, lateral crashes in children was noted. Further analysis of the specific injuries as a function and the crash characteristic can help guide management and prevention strategies.

Risk Factors Associated with Pelvic Fractures Sustained in Motor Vehicle Collisions Involving Newer Vehicles

Despite advances in automotive safety, pelvic fractures caused by motor vehicle collisions remain a significant cause of mortality, morbidity, and functional disability. This study was designed to evaluate epidemiologic and biomechanic risk factors associated with pelvic fractures resulting from motor vehicle collisions. We utilized the Crash Injury Research Engineering Network (CIREN) database to identify these risk factors in newer vehicles. Data were prospectively collected at the ten CIREN centers from 1996 to 2005. Specific data were then abstracted on all patients, biomechanic crash characteristics, and injuries sustained. Patients involved in a frontal or near-side lateral impact with pelvic fractures were compared with those without. Univariate analysis was performed using a chi2 analysis. Logistic regression was used to identify significant risk factors in a multivariate analysis to control for confounding associations. Of the 1,851 patients studied, 511 (27.6%) had a pelvic fracture. The overall mortality was 17%. Injury specific factors associated with pelvic fracture were higher Injury Severity Score (ISS) and fatality of the patient. Biomechanic factors associated with the risk of pelvic fracture included; no airbag deployment (p < 0.001), smaller vehicle (p = 0.05), and lateral deformation location (p < 0.001). When stratified by vehicle deformation location, logistic regression models revealed statically significant variables in a frontal impact which included; higher body mass index, higher ISS, large patient vehicle, no seatbelt use, and higher deltaV. For near-side lateral impacts, multivariate analysis revealed statistically significant variables of lower body mass index, higher ISS, female sex, small vehicle size, and higher deltaV. Even in newer vehicles with federally mandated safety features, pelvic fractures remain a common injury. Pelvic fractures may serve as a marker of crash severity and specific crash characteristics are associated with pelvic fractures. Lateral crashes are significantly more likely to result in a pelvic fracture and, therefore, prevention of pelvic fractures should focus on improving occupant safety in near-side lateral impacts. Recognition of other associations should lead researchers to further investigate causative factors that will ultimately result in improved vehicle design.