Burst fractures of the lumbar spine in frontal crashes.

BACKGROUND: In the United States, major compression and burst type fractures (>20% height loss) of the lumbar spine occur as a result of motor vehicle crashes, despite the improvements in restraint technologies. Lumbar burst fractures typically require an axial compressive load and have been known to occur during a non-horizontal crash event that involve high vertical components of loading. Recently these fracture patterns have also been observed in pure horizontal frontal crashes. This study sought to examine the contributing factors that would induce an axial compressive force to the lumbar spine in frontal motor vehicle crashes. METHODS: We searched the National Automotive Sampling System (NASS, 1993-2011) and Crash Injury Research and Engineering Network (CIREN, 1996-2012) databases to identify all patients with major compression lumbar spine (MCLS) fractures and then specifically examined those involved in frontal crashes. National trends were assessed based on weighted NASS estimates. Using a case-control study design, NASS and CIREN cases were utilized and a conditional logistic regression was performed to assess driver and vehicle characteristics. CIREN case studies and biomechanical data were used to illustrate the kinematics and define the mechanism of injury. RESULTS: During the study period 132 NASS cases involved major compression lumbar spine fractures for all crash directions. Nationally weighted, this accounted for 800 cases annually with 44% of these in horizontal frontal crashes. The proportion of frontal crashes resulting in MCLS fractures was 2.5 times greater in late model vehicles (since 2000) as compared to 1990s models. Belted occupants in frontal crashes had a 5 times greater odds of a MCLS fracture than those not belted, and an increase in age also greatly increased the odds. In CIREN, 19 cases were isolated as horizontal frontal crashes and 12 of these involved a major compression lumbar burst fracture primarily at L1. All were belted and almost all occurred in late model vehicles with belt pretensioners and buckets seats. CONCLUSION: Major compression burst fractures of the lumbar spine in frontal crashes were induced via a dynamic axial force transmitted to the pelvis/buttocks into the seat cushion/pan involving belted occupants in late model vehicles with increasing age as a significant factor.

Cost of spinal cord injuries caused by rollover automobile crashes.

OBJECTIVE: To determine the reduction in direct cost for treatment of spinal cord injuries (SCI) in belted occupants involved in rollover automobile crashes in the USA that would result if severe roof intrusion were eliminated. METHODS: Risk of SCI per rollover crash and by belted/unbelted status was calculated for roof intrusion magnitude categories using 1993-2006 National Automotive Sampling System Crashworthiness Data System (CDS) data. Direct costs of SCI based on neurological level and completeness of SCI were calculated using data from the National SCI Statistical Center. RESULTS: A reduction in rate of SCI for belted occupants with >15 cm roof intrusion to the rate seen for belted occupants with 8-15 cm roof intrusion would reduce the direct cost of SCI by approximately $97 million annually. CONCLUSION: There would be substantial cost savings solely by a reduction in one uncommon type of injury, SCI, if severe roof intrusion were eliminated.

The effect of air bags on pregnancy outcomes in Washington State: 2002-2005.

OBJECTIVE: To estimate whether air-bag deployment is associated with an increased risk of adverse pregnancy outcomes. METHODS: We performed a retrospective cohort study to assess the effect of air-bag availability and air-bag deployment on the risk of adverse pregnancy outcomes among pregnant, front-seat occupants in motor vehicle crashes in Washington State. Pregnant women involved in motor vehicle crashes were identified by linking birth and fetal death certificate data with Washington State Patrol crash data, which reported air-bag availability and deployment. We calculated relative risks (RRs) of adverse maternal and perinatal outcomes and 95% confidence intervals (CIs) using Poisson regression, adjusted for maternal age, seatbelt use, and vehicle model year. RESULTS: We found no increased risk of adverse maternal or perinatal pregnancy outcomes among occupants of air-bag-equipped vehicles in all collisions (n=2,207) compared with those in vehicles without air bags (n=1,141). Among crashes in which air-bag deployment would be likely, we found a nonsignificant 70% increased risk of preterm labor (RR 1.7, 95% CI 0.9-3.2) and a nonsignificant threefold increased risk (RR 3.1, 95% CI 0.4-22.1) of fetal death among occupants in vehicles with air-bag deployment compared with occupants in vehicles without air bags, although fetal death results were limited by small numbers (2/198 [1.0%] in pregnant women whose air bags deployed; 2/622 [0.3%] in pregnant women whose air bags did not deploy). CONCLUSION: Our findings provide clinicians with evidence to advise women that air bags do not seem to elevate risk of most potential adverse outcomes during pregnancy. LEVEL OF EVIDENCE: II.

Severity of injury and outcomes among obese trauma patients with fractures of the femur and tibia: a crash injury research and engineering network study.

OBJECTIVE: To understand the influence of obesity on the morbidity and mortality outcomes of patients who have sustained fractures of the femur and tibia. DESIGN: Retrospective review. SETTING: Multicenter level I trauma facilities. PATIENTS/PARTICIPANTS: Motor vehicle crash victims enrolled in multicenter databases were reviewed. MAIN OUTCOME MEASUREMENTS: Outcome measurements for obese (body mass index, BMI > or = 30 kg/m) versus nonobese (BMI < 30 kg/m) patients included Injury Severity Score, Abbreviated Injury Scores, OTA fracture types, length of hospital stay, disposition, complications, and 36-Item Short Form Survey Instrument. RESULTS: We included 665 cases from the database, of which 461 (69%) were nonobese and 204 (31%) were obese. There was no difference in sex, mechanism of injury, Injury Severity Score, and Abbreviated Injury Score. The obese population was older with a mean age of 44 years compared with 41 years for the nonobese (P < 0.01) and had a greater incidence of reported baseline cardiac disease (P < 0.01) and diabetes (P < 0.01). Obese patients had more severe injury patterns (OTA B and C type) in the distal femur fractures (90% versus 61%, P < 0.01). Mortality rates did not show a statistically significant difference (5.6% versus 9.4%, P = 0.07). The baseline physical component on the 36-Item Short Form Survey Instrument was lower among the obese but not statistically different (P = 0.08). At 6 and 12 months post injury, a decline was noted in both groups; however, no differential decline was noted between the groups (P > 0.05). CONCLUSIONS: Obese patients are significantly more likely to have more severe distal femur fractures compared with nonobese when involved in motor vehicle crashes. In this study, there was no statistically significant difference in length of stay, complications, or mortality in obese patients.

The relationship between body weight and risk of death and serious injury in motor vehicle crashes.

We sought to investigate the effect of increased body weight on the risk of death and serious injury to occupants in motor vehicle crashes. We employed a retrospective cohort study design utilizing data from the National Automotive Sampling System, Crashworthiness Data System (CDS), 1993-1996. Subjects in the study included occupants involved in tow-away crashes of passenger cars, light trucks, vans and sport utility vehicles. Two outcomes were analyzed: death within 30 days of the crash and injury severity score (ISS). Two exposures were considered: occupant body weight and body mass index (BMI; kg/m2). Occupant weight was available on 27263 subjects (76%) in the CDS database. Mortality was 0.67%. Increased body weight was associated with increased risk of mortality and increased risk of severe injury. The odds ratio for death was 1.013 (95% CI: 1.007, 1.018) for each kilogram increase in body weight. The odds ratio for sustaining an injury with ISS > or = 9 was 1.008 (95% CI: 1.004, 1.011) for each kilogram increase in body weight. After adjustment for potentially confounding variables (age, gender, seatbelt use, seat position and vehicle curbweight), the significant relationship between occupant weight and mortality persisted. After adjustment, the relationship between occupant weight and ISS was present, although less marked. Similar trends were found when BMI was analyzed as the exposure. In conclusion, increased occupant body weight is associated with increased mortality in automobile crashes. This is probably due in part to increased co-morbid factors in the more overweight occupants. However, it is possibly also due to an increased severity of injury in these occupants. These findings may have implications for vehicle safety design, as well as for transport safety policy.