Pelvic ring fractures: implications of vehicle design, crash type, and occupant characteristics

BACKGROUND: Pelvic ring fractures (PRFs) are a major cause of morbidity and mortality in motor vehicle collisions (MVCs). Understanding the factors leading to PRFs may help improve vehicle design and safety. This study sought to determine the vehicular, crash, and occupant characteristics that contribute to PRFs. METHODS: From 1997 to 2003, 240 adult patients involved in lateral or frontal crashes were prospectively studied. Comprehensive crash reconstructions, vehicle analysis, and occupant data were compiled and analyzed as part of the national Crash Injury Research Engineering Network project. RESULTS: Of 240 study patients, 38 had PRFs. The incidence of PRFs was significantly associated with female gender, lateral impact crashes, vehicle incompatibility, and severity of crash. Seat belts and airbags were not protective against PRFs in either lateral or frontal crashes. CONCLUSIONS: All vehicles in the current study were less than 6 years old at the time of the MVC and thus reflect newer safety designs. Compared with studies of PRFs in MVCs before the widespread adoption of modern safety standards, our series suggests there has been a modest decrease in the incidence of PRFs in newer vehicles. Current safety standards do not adequately protect against PRFs, especially in lateral MVCs involving incompatibility and female occupants. New technology needs to be developed and implemented. Our data suggest that side impact airbags, alteration of vehicle geometry, and increased reinforcement of side panels and doors may result in fewer PRFs.     

The effect of unrestrained rear-seat passengers on driver mortality

BACKGROUND: It is well documented that seat belt usage effectively reduces the severity of motor vehicle occupant injuries and fatalities in roadway crashes. This research examines how the presence of an unrestrained rear-seat passenger seated directly behind an airbag and/or belt-restrained driver affects the driver's risk of injury in two different idealized crash scenarios. Empirical data used in the study was obtained from four sled tests conducted with various size Hybrid III crash test dummies. METHODS: Three tests simulated a frontal (head-on) impact between two vehicles. The first established the baseline condition: a driver dummy restrained by a belt and an airbag system, with an identical belt-restrained dummy seated directly behind. The other two frontal-mode tests involved different size driver dummies restrained in the same manner, with different size unrestrained dummies behind them. A fourth test featured an angled driver-side impact crash with a restrained driver and unrestrained rear seat passenger. RESULTS: In both of the latter cases the driver incurred a high likelihood of severe head and chest injuries relative to that inferred in the baseline exposure. The last test featured two identical dummies in a simulated lateral (driver-side) inter-vehicular impact using a belt-restrained (only) driver and an unrestrained rear-seat passenger. Driver mortality was not significantly affected in this configuration. CONCLUSION: Unrestrained rear-seat passengers place themselves as well as their driver at great risk of serious injury when involved in a head-on crash.     

The new car assessment program: does it predict the relative safety of vehicles in actual crashes?

BACKGROUND: Federal motor vehicle safety standards are based on crash test dummy analyses that estimate the relative risk of traumatic brain injury (TBI) and severe thoracic injury (STI) by quantifying head (Head Injury Criterion [HIC]) and chest (Chest Gravity Score [CGS]) acceleration. The New Car Assessment Program (NCAP) combines these probabilities to yield the vehicle's five-star rating. The validity of the NCAP system as it relates to an actual motor vehicle crash (MVC) remains undetermined. We therefore sought to determine whether HIC and CGS accurately predict TBI and STI in actual crashes, and compared the NCAP five-star rating system to the rates of TBI and/or STI in actual MVCs. METHODS: We analyzed frontal crashes with restrained drivers from the 1994 to 1998 National Automotive Sampling System. The relationship of HIC and CGS to the probabilities of TBI and STI derived from crash tests were respectively compared with the HIC-TBI and CGS-STI risk relationships observed in actual crashes while controlling for covariates. Receiver operating characteristic curves determined the sensitivity and specificity of HIC and CGS as predictors of TBI and STI, respectively. Estimates of the likelihood of TBI and/or STI (in actual MVCs) were compared with the expected probabilities of TBI and STI (determined by crash test analysis), as they relate to NCAP ratings. RESULTS: The crash tests overestimate TBI likelihood at HIC scores >800 and underestimate it at scores <500. STI likelihood is overestimated when CGS exceeds 40 g. Receiver operating characteristic curves demonstrated poor sensitivity and specificity of HIC and CGS in predicting injury. The actual MVC injury probability estimates did not vary between vehicles of different NCAP rating. CONCLUSION: HIC and CGS are poor predictors of TBI and STI in actual MVCs. The NCAP five-star rating system is unable to differentiate vehicles of varying crashworthiness in actual MVCs. More sensitive parameters need to be developed and incorporated into vehicle crash safety testing to provide consumers and automotive manufacturers with useful tools with which to measure vehicle safety.     

Intoxicated motor vehicle passengers warrant screening and treatment similar to intoxicated drivers.

BACKGROUND: Alcohol interventions decrease alcohol consumption and recurrent injury. The study hypotheses are (1) intoxicated passengers are similar to intoxicated drivers in crashes and driving under the influence of alcohol (DUI), and (2) DUI conviction rates after injury are low. METHODS: Intoxicated motor vehicle occupants hospitalized for injury in 1996-1998 were matched to the state traffic database for crashes and DUI. Drivers and passengers were compared for crashes and DUI in the 2 years preceding and 1 year after admission. Driver DUI citation at the time of admission was also recorded. A logistic regression model for crash and DUI probability was constructed. RESULTS: Six hundred seventy-four patients met inclusion criteria. In the 2 years preceding admission, passengers and drivers were equally cited for crashes (14.7% vs 19.3%, p = 0.12). In 1 year after admission, they were also equally cited (7.1% vs 7.7%, p = 0.92). Driver/passenger status was not a predictor by logistic regression; 13.4% of intoxicated drivers were convicted of DUI for the admitting crash. CONCLUSION: Intoxicated passengers and drivers are equally likely to be cited for crashes and DUI before and after admission for injury. Few admitted intoxicated drivers are convicted of DUI. Screening and intervention for all intoxicated crash occupants is warranted.     

Factors influencing the patterns of injuries and outcomes in car versus car crashes compared to sport utility, van, or pick-up truck versus car crashes: Crash Injury Research Engineering Network Study.

BACKGROUND: Data using crash dummies suggest that motor vehicle crashes (MVCs) involving passenger sedans (S) vs sport utility, vans, or light trucks (SUVTs) produce more severe injuries than those involving two sedans (SvS). However, no detailed data regarding pattern of injuries or force mechanisms involved have been presented in real patients. METHODS: The relationship of injury patterns and severities with MVC reconstruction data were obtained in 412 MVC patients, drivers or front seat passengers. Crashes were examined with regard to impact direction, frontal (F) or lateral (L) crashes, vehicle mass ratio, ISS, DELTA V, seat belt use, and airbag deployment (AB). RESULTS: In 309 F-MVC, AB reduced overall ISS (24.3 to 17.9) with a reduction in the mean severity of traumatic brain injury (TBI) GCS < or = 12, from 48% to only 28%. This AB protection from TBI was preserved as DELTA V increased to > 30 mph even though non-AB protected body areas (thorax, lung, liver, and lower extremity injuries) all increased. When vehicles of incompatible size and mass (SUVT) had F-MVC with sedans the incidence of severe TBI rose as did face lacerations despite AB or belt use. In L-MVC between SUVT and sedans compared with SvS MVC, there was a cephalad shift in body injuries with increased thorax, but decreased lower extremity injuries. The incidence of TBI increased. Analysis of injury contact sites (hits) showed more hits and a wider distribution of contract sites in SUVT vs sedan MVC. These appeared due to the greater mass excess and larger mass ratio, hood height, and width in the F-SUVT vs S crashes. All of these factors plus the increased bumper height above the body frame side-door sill were injury causal factors in the L-SUVT vs S MVCs. CONCLUSION: Both F and L crashes between sedans and SUVT with a high mass ratio shift the pattern of injury cephalad with increased thorax and intrathoracic organ injuries, and more severe TBI. These data suggest that improved head and thorax side-impact buffering and design features which transmit MVC forces from the higher front end of the larger mass SUVT to the frame of the sedan may better protect sedan occupants from side-impacts.     

Characteristics of kangaroo-related motor vehicle crashes

BackgroundKangaroo-related motor vehicle collisions are common but there is limited literature on this topic. Drivers confronted by kangaroos may choose to swerve or to directly collide with the kangaroo. The effect of these differing crash mechanisms, along with the effect of vehicle type or time of day, has not yet been reported.MethodsA retrospective cohort study was performed, examining patients admitted to our tertiary trauma centre for kangaroo-related motor vehicle collisions between 2000 and 2020. Data on patient demographics, crash characteristics, and hospital stay were collected and analysed.ResultsA total of 366 patients were included and were predominantly male (76%) with an median age of 40. Swerve crashes were more common (59%) than direct impact and swerving was a statistically significant predictor of reduced injury severity score on multivariable analysis (other significant factors were female sex and no rollover). Motor vehicle crashes and motorbike crashes had differing crash characteristics. Motor vehicle crashes were more likely the result of swerving, and swerving was less likely to cause ejection or require extrication but more likely to cause rollover. Motorbike crashes however, were more likely the result of head on collision and riders were more likely to be ejected from the vehicle, require extrication, or be involved in a rollover. In terms of time of day, there were more crashes at dawn and there was a trend towards higher injury severity score and length of stay for night-time crashes.ConclusionFor kangaroo-related motor vehicle crashes, predictors of increased injury severity score on multivariable analysis were male sex, direct impact, and rollover. Motorbikes and motor vehicles had differing crash mechanisms and characteristics, as did night-time crashes when compared to daytime or twilight crashes.Level of evidenceIV, prognostic     

Risk factors associated with pelvic fractures sustained in motor vehicle collisions involving newer vehicles

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.     

Factors influencing pediatric injury in side impact collisions

BACKGROUND: Side impact collisions pose a great risk to children in crashes, but information about the injury mechanisms is limited. METHODS: This study involves a case series of children in side impact collisions who were identified through Partners for Child Passenger Safety, a large, child-focused crash surveillance system. The aim of the current study was to use in-depth crash investigations to identify injury mechanisms to children in side impact collisions. RESULTS: Ninety-three children in 55 side impact crashes were studied. Twenty-three percent (n = 22) of the children received an Abbreviated Injury Scale (AIS) score > or = 2 (clinically significant) injury. In these 22 children, head (40%), extremity (23%), and abdominal injuries (21%) were the most common significant injuries. Cases that illustrate body region-specific injury mechanisms are discussed. CONCLUSION: The cases revealed that serious injuries, particularly head injuries, occur even in minor crashes, and efforts should be made to make the interiors of vehicles more child occupant friendly. Lower extremity and abdominal injuries occurred because of contact with the intruding door. Design of vehicles to minimize crush should mitigate the occurrence and severity of these injuries.     

Blood alcohol testing of motor vehicle crash admissions at a regional trauma unit

Motor vehicle crashes remain a leading cause of death and injury in the industrialized world. Alcohol consumption is implicated as a major factor in fatal motor vehicle crashes (MVCs), but only poor estimates of blood alcohol concentrations among nonfatally injured crash victims are available. A 3-year study was undertaken at a Regional Trauma Unit to determine the demographics, injury severity, and alcohol positivity of motor vehicle crash victims. Between August 1, 1986 and July 31, 1989, 825 motor vehicle crash victims were available for study; 368 drivers were admitted to the unit within a period of 4 hours. Of 715 patients tested for alcohol, 31.0% were positive. A total of 333 drivers were tested for blood alcohol; 128 (38.4%) were positive. The mean blood alcohol concentration (BAC) at admission for the drivers was 145.6 mg/100 ml; the estimated mean BAC at crash was 180.9 mg/100 ml. The mean age of BAC positive drivers was 31.4 years, compared to a mean age in the BAC negative drivers of 35.2 years (p less than 0.02). Male patients represented 76.6% of the drivers, yet represented 83.6% of the BAC positive drivers (p less than 0.05). There was a marked seasonal variation in BAC positivity, with 46.1% of drivers positive during the summer months. Alcohol appears to be a significant factor in nonfatal MVCs.     

„Einklemmungstrauma“ im Straßenverkehr

AIM: Crash mechanisms, injury patterns, and severity of injury of entrapped motor vehicle occupants were analysed by the Accident Research Unit's scientific teams between 1983 and 2003. RESULTS: Of the 1281 vehicle passenger entrapments in our study, 18.3% happened on highways, 25.6% on federal roads, 35.9% on country roads, and 18.3% on city roads. Of those involved, 69.9% were drivers, 19.4% were front passengers, and 8.5% were rear passengers. Coinvolved objects in car collisions were: other cars 30.9%, trucks 50.2%, objects 18.6%, and motorbikes 0.3%. Coinvolved objects in truck collisions were: other trucks 61.8% and objects 38.2%. The mean Delta-V was 42 km/h (cars 46.2, trucks 32.2). Maximum AIS levels were 31% I, 25.2% II, 19.4% III, 7.8% IV, 7.8% V, and 8.6% VI. Of injuries, 68.7% were to the head, 23.5% to the neck, 50.8% to the chest, 43.6% to upper extremities, 15.4% to the abdomen, 16.4% to the pelvis, and 52.9% to lower extremities. The incidence of multiple injuries (ISS>16) was 23.7%, and mortality was 15.9%. CONCLUSION: Car drivers are more at risk of accidents with entrapment on rural streets, and truck drivers are more at risk on highways. In most cases car occupants crash with trucks or other cars, and truck drivers collide more frequently with other trucks or objects. Besides a high degree of severe single injuries, there is also a high incidence of multiple injury victims and high mortality. Of the fatalities, 74.5% occur during the preclinical course and 24.5% during the clinical course.     

Human body tolerance to high energy trauma: influence of subcutaneous and visceral fat

Every year in the US, over 40,000 individuals are killed and more than 3 million others injured as a result of motor vehicle collisions (MVCs). The economic cost of crash injuries each year is greater than $230 billion. In order to improve vehicle safety, a better understanding of the mechanism by which injuries are caused in current crashes as well as the human factors that affect injury tolerance is required. Biomechanical studies using cadavers suggest that factors such as bone density, muscle mass and body geometry influence the body’s ability to tolerate injurious forces. We hypothesized that fat in both the subcutaneous and visceral compartments may act as an energy absorbing material and affect injury patterns in MVCs. This study examined the relationship between the severity of the injuries sustained in MVCs and that occupant’s subcutaneous and visceral fat volumes as measured by CT. 139 adults MVC occupants were studied. Field and vehicle inspection was performed to determine crash configuration, crash severity and restraint use. All of the patients received CT evaluation of their abdomen and pelvis as part of their trauma workup. A three-dimensional image of the abdomen was reconstructed and volumetric measurement of both the subcutaneous and visceral fat were performed on a two-inch slab at the level of the third lumbar vertebra. The results showed that increased volume of either subcutaneous or visceral fat correlated with a significant decrease in the overall Injury Severity Score (ISS) (p < 0.02). Increased subcutaneous fat was associated with significantly decreased injury severity to the head (p = 0.001) and abdominal (p = 0.02) regions, but significantly worse injury severity to the lower extremities (p < 0.0001). Subcutaneous fat volume was found to have greater influence on injury severity than occupant age, restraint status or crash severity.     

Age and gender differences in risk-taking behaviour as an explanation for high incidence of motor vehicle crashes as a driver in young males

Risk-taking behaviour has been identified as a possible explanation for the high incidence of motor vehicle crashes involving young male drivers. This study examines the extent to which differences in risk-taking behaviour explain the differential crash rates by age and gender. A random sample of 689 adults aged 17-88 were selected from motor vehicle license holders within randomly selected geographical areas across Queensland. Participants completed a questionnaire covering their attitudes towards driving behaviour and general risk-taking behaviour, selected demographic characteristics and self-reported history of road crashes as a driver. Univariate analysis showed that males scored higher means than females in driver aggression and thrill seeking and in their general risk acceptance. Multivariate logistic regression analysis indicated that males were twice as likely (OR 2.46, CI 1.59-3.83) to have reported at least one crash as a driver compared to females and nearly three times as likely (OR 2.88, CI 1.84-4.49) to have reported two or more crashes. Drivers aged 17-29 were also twice as likely (OR 2.31, CI 1.10-4.19) to have reported at least one crash when compared to those aged over 50 years. When risk-taking behaviours were introduced into the logistic model the odds of males (OR 1.70, CI 1.29-3.30) or 17-29 year olds (OR 1.30, CI 0.93-3.91) being involved in at least one crash substantially reduced. An increased risk of a crash as a driver can, in part, be explained by the age and gender differential in risk-taking behaviour. The challenge for public health professionals is to determine suitable strategies to modify risk-taking behaviour in young or male drivers.     

The effectiveness of active head restraint in preventing whiplash.

BACKGROUND: Whiplash injury claims have increased for two decades and manual head restraints are often incorrectly adjusted. A Self-Aligning Head Restraint (SAHR) was designed to move upward and forward by occupant motion in a rear crash providing earlier neck support, even when the head restraint is positioned low. This study determines its field effectiveness. METHODS: Insurance records were analyzed for consecutive Saab rear crashes in Sweden over 18 months. The Saab 9000/900 had standard head restraints and Saab 9-5/9-3 had SAHR. A questionnaire was mailed to the occupants, insurance and medical records were reviewed, and phone interviews were conducted. RESULTS: SAHR reduced whiplash injury risks by 75 +/- 11% from an 18 +/- 5% incidence in 85 occupants with standard head restraints to 4 +/- 3% in 92 occupants with SAHR. No SAHR seat required repair or replacement after the crashes. CONCLUSION: SAHR is effective in reducing whiplash injury in rear crashes and is a passive public-health approach that works irrespective of manual head-restraint adjustment.     

Maxillofacial and ocular injuries in motor vehicle crashes

BACKGROUND: Injuries from motor vehicle crashes constitute a leading cause of death in the young and a high degree of morbidity and mortality in all age groups. Facial trauma has been consistently shown to be the single most common injury to the occupants of vehicles involved in crashes. This has been confirmed by more recent studies which have demonstrated a continuing high incidence of facial fractures amongst belted drivers. Airbags have been advocated as a supplemental restraint system. However, their deployment can cause injury particularly if the driver is of short stature, unrestrained or out of position within the vehicle. METHODS: The Crash Injury Research Engineering Network (CIREN) project aims to correlate the injuries received by occupants in vehicle crashes with the biomechanics of vehicle deformation. All cases of facial injury which presented to the University of Michigan Medical Center, USA in 1999 were retrospectively evaluated with reference to the methods of occupant restraint and to the correlation between the injuries sustained and vehicle deformation. RESULTS AND CONCLUSIONS: The case analysis confirmed the value of airbags to the safety of vehicle occupants but reinforced the conclusion that they must still be considered supplemental restraint systems. New generation airbags will minimise the risk of injury even to small stature or out of position occupants as they will prevent deployment in situations where they may have an adverse effect.     

Protection against head injuries should not be optional: a case for mandatory installation of side-curtain air bags

Background

More than 9,000 vehicle occupants die each year in side-impact vehicle collisions, primarily from head injuries. The authors hypothesized that side-curtain air bags significantly improve head and neck safety in side-impact crash testing.

Methods

Side-impact crash-test data were obtained from the Insurance Institute for Highway Safety, which ranks occupant protection as good, acceptable, marginal, or poor. Vehicles of the same make and model that underwent side-impact crash testing both with and without side-curtain air bags were compared, as well as the protective effect of these air bags on occupants' risk for head and neck injury.

Results

Of all the passenger vehicles, 25 models have undergone side-impact crash testing with and without side-curtain air bags by the Insurance Institute for Highway Safety. Only 3 models without side-curtain air bags (12%) provided good head and neck protection for drivers, while 21 cars with side-curtain air bags (84%) provided good protection (P < .001). For rear passengers, the added protection from side-curtain air bags was less dramatic but significant (84% without vs 100% with side-curtain air bags, P = .04).

Conclusion

Side-curtain air bags significantly improve vehicle occupant safety in side-impact crash tests. Installation of these air bags should be federally mandated in all passenger vehicles.     

Seat belt use by police: should they click it?

BACKGROUND: Motor vehicle crashes are a leading cause of mortality in the United States, although seat belts significantly reduce the risk of death. Police officers do not always wear a seat belt. A retrospective study was conducted on all crashes that involved marked police vehicles in the United States and included a death in any of the involved vehicles. METHODS: For the years 1997 through 2001, crash data were collected and analyzed from the Fatality Analysis Reporting System that included an isolated or multiple vehicle crash with a marked police vehicle and a resulting death in any of the involved vehicles. Motorcycle, aircraft, and undercover police crashes were excluded from this study. Only the occupants of the police vehicle involved in the crash were included in the study. In addition, crashes involving police vehicles where the status of seat belt use by the occupants of the police vehicle was unknown were also excluded. RESULTS: When the crashes occurred, 59.9% of the officers were responding to nonemergency calls, 79.8% of the occupants were wearing their seat belts, and 79.5% survived. Of the 104 occupants that were not belted, 42 (40.4%) died in the crash, compared with 64 (15.5%) of the 412 belted occupants (risk ratio, 2.6; odds ratio, 3.7). CONCLUSION: The risk of death was 2.6 times higher for unbelted occupants of police vehicles than for belted occupants in our study population. In addition, seat belt use was not statistically related to emergency versus nonemergency calls.     

Thoracic aortic injury in motor vehicle crashes: the effect of impact direction, side of body struck, and seat belt use

BACKGROUND: Using in-depth, real-world motor vehicle crash data from the United States and the United Kingdom, we aimed to assess the incidence and risk factors associated with thoracic aorta injuries. METHODS: De-identified National Automotive Sampling System Crashworthiness Data System (U.S.) and Co-operative Crash Injury Study (U.K.) data formed the basis of this retrospective analysis. Logistic regression was used to assess the level of risk of thoracic aorta injury associated with impact direction, seat belt use and, given the asymmetry of the thoracic cavity, whether being struck toward the left side of the body was associated with increased risk in side-impact crashes. RESULTS: A total of 13,436 U.S. and 3,756 U.K. drivers and front seat passengers were analyzed. The incidence of thoracic aorta injury in the U.S. and U.K. samples was 1.5% (n = 197) and 1.9% (n = 70), respectively. The risk was higher for occupants seated on the side closest to the impact than for occupants involved in frontal impact crashes. This was the case irrespective of whether the force was applied toward the left (belted: relative risk [RR], 4.6; 95% confidence interval [CI], 2.9-7.1; p < 0.001) or the right side (belted: RR, 2.6; 95% CI, 1.4-5.1; p < 0.004) of the occupant's body. For occupants involved in side-impact crashes, there was no difference in the risk of thoracic aorta injury whether the impacting force was applied toward the left or toward the right side of the occupant's body. Seat belt use provided a protective benefit such that the risk of thoracic aorta injury among unbelted occupants was three times higher than among belted occupants (RR, 3.0; 95% CI, 2.2-4.3; p < 0.001); however, the benefit varied across impact direction. Thoracic aorta injuries were found to be associated with high impact severity, and being struck by a sports utility vehicle relative to a passenger vehicle (RR, 1.7; 95% CI, 1.2-2.3; p = 0.001). CONCLUSION: Aortic injuries have been conventionally associated with frontal impacts. However, emergency clinicians should be aware that occupants of side-impact crashes are at greater risk, particularly if the occupant was unbelted and involved in a crash of high impact severity.     

Kinematics of belted fatalities in frontal collisions: A new approach in deep studies of injury mechanisms

BACKGROUND: More than half of car crash fatalities are belted occupants, and the majority of these occur as a consequence of frontal crashes. In an earlier study of crash configuration characteristics, we have shown that 48% of fatalities occurred in frontal small overlap (SO) crashes in which less than 30% of the vehicle front was engaged. Only 23% of fatalities occurred in large overlap (LO) crashes engaging the drive train, similar to most barrier front crash testing procedures. The main purpose of this study was to analyze the characteristics of injury mechanisms and injuries in fatal SO and LO car crashes in Sweden. METHOD: Retrospective examination and analysis of 61 fatally injured occupants from 53 car crashes within a sample area covering 40% of the population of Sweden was conducted. RESULTS: A clear difference in injury mechanisms and injuries was found between SO and LO crashes. The major injury mechanisms in SO crashes are explained by an oblique torso movement and rotation toward the outboard side, which causes a high proportion of serious lateral chest and head injuries. In contrast, LO crashes were generally characterized by serious anterior chest injuries in elderly occupants (> or =60 years). CONCLUSION: Current government and consumer barrier crash test procedures are not designed to estimate the performance of cars and restraint systems for the type of crashes which caused the majority of occupant fatalities in this data set.     

The applicability of a computer model for predicting head injury incurred during actual motor vehicle collisions

BACKGROUND: Head injury is a significant cause of both morbidity and mortality. Motor vehicle collisions (MVCs) are the most common source of head injury in the United States. No studies have conclusively determined the applicability of computer models for accurate prediction of head injuries sustained in actual MVCs. This study sought to determine the applicability of such models for predicting head injuries sustained by MVC occupants. METHODS: The Crash Injury Research and Engineering Network (CIREN) database was queried for restrained drivers who sustained a head injury. These collisions were modeled using occupant dynamic modeling (MADYMO) software, and head injury scores were generated. The computer-generated head injury scores then were evaluated with respect to the actual head injuries sustained by the occupants to determine the applicability of MADYMO computer modeling for predicting head injury. RESULTS: Five occupants meeting the selection criteria for the study were selected from the CIREN database. The head injury scores generated by MADYMO were lower than expected given the actual injuries sustained. In only one case did the computer analysis predict a head injury of a severity similar to that actually sustained by the occupant. CONCLUSION: Although computer modeling accurately simulates experimental crash tests, it may not be applicable for predicting head injury in actual MVCs. Many complicating factors surrounding actual MVCs make accurate computer modeling difficult. Future modeling efforts should consider variables such as age of the occupant and should account for a wider variety of crash scenarios.     

Type II odontoid fracture from frontal impact: case report and biomechanical mechanism of injury

The authors report a case of Type II odontoid fracture from a frontal impact sustained in the crash of a late-model motor vehicle. They discuss the biomechanical mechanisms of injury after considering patient demographic data, type and use of restraint systems including seatbelt and airbags, crash characteristics, and laboratory-based experimental studies. Multiple factors contributed to the Type II odontoid fracture: the patient's tall stature and intoxicated state; lack of manual three-point seat belt use; obliqueness of the frontal impact; and the most likely preflexed position of the head-neck complex at the time of impact, which led to contact of the parietal region with the A-pillar roof-rail area of the vehicle and resulted in the transfer of the dynamic compressive force associated with lateral bending. Odontoid fractures still occur in individuals involved in late-model motor vehicle frontal crashes, and because this injury occurs secondary to head impact, airbags may not play a major role in mitigating this type of trauma to an unrestrained occupant. It may be more important to use seat belts than to depend on the airbag alone for protection from injury.