The continued burden of spine fractures after motor vehicle crashes

Simulative investigation of the required level of geometrical individualization of the lumbar spines to predict fractures

Injury mechanisms of the lumbar spine under dynamic loading are dependent on spine curvature and anatomical variation. Impact simulation with finite element (FE) models can assist the reconstruction and prediction of injuries. The objective of this study was to determine which level of individualization of a baseline FE lumbar spine model is necessary to replicate experimental responses and fracture locations in a dynamic experiment.Experimental X-rays from 26 dynamic drop tower tests were used to create three configurations of a lumbar spine model (T12 to L5): baseline, with aligned vertebrae (positioned), and with aligned and morphed vertebrae (morphed). Each model was simulated with the corresponding loading and boundary conditions from dynamic lumbar spine experiments. Force, moment, and kinematic responses were compared to the experimental data. Cosine similarity was computed to assess how well simulation responses match the experimental data. The pressure distribution within the vertebrae was used to compare fracture risk and fracture location between the different models.The positioned models replicated the injured spinal level and the fracture patterns quite well, though the morphed models provided slightly more accuracy. However, for impact reconstruction or injury prediction, the authors recommend pure positioning for whole-body models, as the gain in accuracy was relatively small, while the morphing modifications of the model require considerably higher efforts. These results improve the understanding of the application of human body models to investigate lumbar injury mechanisms with FE models.

Human Lumbar Spine Injury Risk in Dynamic Combined Compression and Flexion Loading

Anticipating changes to vehicle interiors with future automated driving systems, the automobile industry recently has focused attention on crash response in novel postures with increased seatback recline. Prior research found that this posture may result in greater risk of lumbar spine injury in the event of a frontal crash. This study developed a lumbar spine injury risk function (IRF) that estimated injury risk as a function of simultaneously applied compression force and flexion moment. Force and moment failure data from 40 compression-flexion tests were utilized in a Weibull survival model, including appropriate data censoring. A mechanics-based injury metric was formulated, where lumbar spine compression force and flexion moment were normalized by specimen geometry. Subject age was incorporated as a covariate to further improve model fit. A weighting factor was included to adjust the influence of force and moment, and parameter optimization yielded a value of 0.11. Thus, the normalized compression force component had a greater effect on injury risk than the normalized flexion moment component. Additionally, as force was nominally increased, less moment was required to produce injury for a given age and specimen geometry. The resulting IRF may be utilized to improve occupant safety in the future.

Current status of traumatic spinal cord injury caused by traffic accident in Northern China

The study aims to investigate the characteristics of traumatic spinal cord injury (TSCI) caused by motor vehicle collisions (MVCs). The study included 649 cases who experienced MVC-induced TSCI. The mean age was 37.3 years old, ranging from 1 to 82 years old. The male-to-female ratio was 2.7:1. We extracted data of gender, age, occupation, neurological level of injury, fracture level, complications, vehicle type, accident type and other features. The results showed that the most common vehicles involved in accidents were passenger cars (65.1%). Collision was the leading cause of MVCs (35.8%). The lesion level was cervical in 51.6% and thoracic in 42.2%. The most common fracture levels in drivers and passengers were C3–C7, while those in pedestrians were T11–L2. The frequency of tetraplegia (51.6%) was slightly higher than paraplegia (48.4%), and cases with tetraplegia with incomplete injury accounted for 61.2%. MVC-induced TSCI has unique clinical features. Collision was the most common cause. People sitting in cars were more likely to suffer from cervical fractures, while thoracolumbar fractures were more common in pedestrians. Tetraplegic cases were mainly incomplete injuries, while paraplegic cases were mainly complete injuries.

Biomechanics of Lumbar Spine Injury in Road Barrier Collision-Finite Element Study

Literature and field data from CIREN database have shown that lumbar spine injuries occur during car crashes. There are multiple hypotheses regarding how they occur; however, there is no biomechanical explanation for these injuries during collisions with road safety barriers (RSBs). Therefore, the objective of this study was to investigate the mechanics of vertebral fractures during car collisions with concrete RSBs. The finite element method was used for the numerical simulations. The global model of the car collision with the concrete RSB was created. The lumbar spine kinematics were extracted from the global simulation and then applied as boundary conditions to the detailed lumbar spine model. The results showed that during the collision, the occupant was elevated, and then dropped during the vehicle landing. This resulted in axial compression forces 2.6 kN with flexion bending moments 34.7 and 37.8 Nm in the L2 and L3 vertebrae. It was shown that the bending moment is the result of the longitudinal force on the eccentricity. The lumbar spine index for the L1-L5 section was 2.80, thus indicating a lumbar spine fracture. The minimum principal strain criterion of 7.4% and damage variable indicated L2 and L3 vertebrae and the inferior part of L1, as those potentially prone to fracture. This study found that lumbar spine fractures could occur as a consequence of vehicle landing during a collision with a concrete RSB mostly affecting the L1-L3 lumbar spine section. The fracture was caused by a combination of axial forces and flexion bending moments.

A numerical investigation of factors affecting lumbar spine injuries in frontal crashes

Recent field data analyses have shown that lumbar spine fractures occurred more frequently in late model vehicles than the early ones in frontal crashes. Therefore, the objective of this study was to investigate risk factors associated with lumbar spine fractures in frontal crashes. Parametric simulations were conducted using a set of validated vehicle driver compartment model, restraint system model, and a HIII mid-size male crash test dummy model. Risk factors considered in the study included occupant seating posture, crash pulse, vehicle pitch angle, seat design, anchor pre-tensioner, dynamic locking tongue, and shoulder belt load limiter. ANOVA and ANCOVA were used to test the statistical significance (p < 0.05). Simulation results showed that all the factors that reduced the risk of submarining increased the lumbar spine forces, indicating a direct conflict between submarining and lumbar spine fractures. Among all the factors selected, seat structure is the most significant factor in determining the lumbar spine force (p < 0.001). Crash pulse severity, time at which the peak crash deceleration reached, and pitch angle are also crucial for lumbar spine force. Specifically, increase in vehicle pitch angle increased lumbar spine force, but reduced injury measures to other body regions; while a crash pulse with early peak produced greater lumbar spine force than that with a late peak. On average, more reclined posture increased the lumbar spine force compared to upright posture, and decreases in the coefficient of friction between the pelvis and the seat cushion reduced the lumbar spine force. However, they are not statistically significant. This study provided better understanding of effects from design countermeasures to reduce occupant lumbar spine injuries in new generation of vehicle models.

Epidemiological profile of thoracolumbar fracture (TLF) over a period of 10 years in Tianjin, China

CONTEXT/OBJECTIVE

The objective of the research was to illustrate the epidemiology profile of thoracolumbar fracture (TLF) in Tianjin Medical University General Hospital, China, from 2006-2015.

DESIGN

Hospital-based retrospective study.

SETTING

Tianjin Medical University General Hospital.

METHODS

Medical records of inpatient patients with TLF from 1 January 2006 to December 2015 were collected. Detailed information on epidemiological characters were analyzed based on the medical records suffering from TLF from T11-L2 level, including incidence, age and sex, marital, occupation, etiology and fracture type, types of injuries.

RESULTS

Totally 132 cases were identified. The incidence rate was 2.4 patient per million population at 2015. Male-to-female ratio was 1.4:1, with a mean age of 49.1 ± 17.7 years. The cases number in 46-60 group, totally 35 and accounting for 26.5%, was the largest. There is a significant differences of cases number between 2011-2015 group and 2006-2010 group. Retiree, taken up 48.5%, was the largest group among TLF patients. The most common injury level was T12 (34) accounting for 25.7%. Falls (57, 43.2%) (low falls and high falls) were the leading causes, followed by motor vehicle collisions (MVCs) (23, 17.4%).Compression is the only type of osteoporosis and took up 55.3%.

CONCLUSIONS

The incidence ratio is increased annually in TMUGH. Male was more vulnerable than female based on different social character. The average age was older in 2011-2015, retiree accounted for the main proportion and compression took up the largest percentage, the mean age increased and osteoporosis takes more in recent years.

Airbag deployment and cervical spine injury in restrained drivers following motor vehicle collisions

PURPOSE

Seatbelts and airbags are the most important devices protecting drivers from cervical spine injury (CSI) following motor vehicle collisions (MVCs). However, there have been few reports on the radiographic characteristics of CSI sustained by restrained, airbag-deployed drivers.

METHODS

A single-center, retrospective observational study was conducted using prospectively acquired data. Between January 2011 and December 2017, 564 restrained drivers, whose vehicle had been severely damaged in MVCs, underwent whole-body computed tomography for evaluation of bodily injuries. The drivers were dichotomized into airbag (+) group (n = 218) and airbag (-) group (n = 139), after excluding 207 drivers in whom airbag deployment status was unknown.

RESULTS

Eight and nine drivers sustained CSIs in the airbag (+) and airbag (-) group, respectively. The frequency of CSI did not differ significantly between the two groups (3.7% vs. 6.5%, p = 0.31). All eight CSIs in the airbag (+) group were classified as hyperextension injuries, and four of them sustained concomitant spinal cord injuries caused by dislocation. Within the airbag (+) group, the drivers with CSIs were significantly older than those without CSIs (65.2 ± 18.5 vs. 44.8 ± 18.7 years, p = 0.002).

CONCLUSION

Although it is without doubt that the combination of seatbelt and airbag reduces the frequency and severity of CSIs following MVCs, the CSIs sustained in restrained, airbag (+) drivers may not always be mild, and elderly drivers may be at an elevated risk of CSI. In addition, the possibility of a causal role of airbags in CSI requires consideration in this population.

Computational modeling and analysis of thoracolumbar spine fractures in frontal crash reconstruction

OBJECTIVE

This study aimed to reconstruct 11 motor vehicle crashes (6 with thoracolumbar fractures and 5 without thoracolumbar fractures) and analyze the fracture mechanism, fracture predictors, and associated parameters affecting thoracolumbar spine response.

METHODS

Eleven frontal crashes were reconstructed with a finite element simplified vehicle model (SVM). The SVM was tuned to each case vehicle and the Total HUman Model for Safety (THUMS) Ver. 4.01 was scaled and positioned in a baseline configuration to mimic the documented precrash driver posture. The event data recorder crash pulse was applied as a boundary condition. For the 6 thoracolumbar fracture cases, 120 simulations to quantify uncertainty and response variation were performed using a Latin hypercube design of experiments (DOE) to vary seat track position, seatback angle, steering column angle, steering column position, and D-ring height. Vertebral loads and bending moments were analyzed, and lumbar spine indices (unadjusted and age-adjusted) were developed to quantify the combined loading effect. Maximum principal strain and stress data were collected in the vertebral cortical and trabecular bone. DOE data were fit to regression models to examine occupant positioning and thoracolumbar response correlations.

RESULTS

Of the 11 cases, both the vertebral compression force and bending moment progressively increased from superior to inferior vertebrae. Two thoracic spine fracture cases had higher average compression force and bending moment across all thoracic vertebral levels, compared to 9 cases without thoracic spine fractures (force: 1,200.6 vs. 640.8 N; moment: 13.7 vs. 9.2 Nm). Though there was no apparent difference in bending moment at the L1-L2 vertebrae, lumbar fracture cases exhibited higher vertebral bending moments in L3-L4 (fracture/nonfracture: 45.7 vs. 33.8 Nm). The unadjusted lumbar spine index correctly predicted thoracolumbar fracture occurrence for 9 of the 11 cases (sensitivity = 1.0; specificity = 0.6). The age-adjusted lumbar spine index correctly predicted thoracolumbar fracture occurrence for 10 of the 11 cases (sensitivity = 1.0; specificity = 0.8). The age-adjusted principal stress in the trabecular bone was an excellent indicator of fracture occurrence (sensitivity = 1.0; specificity = 1.0). A rearward seat track position and reclined seatback increased the thoracic spine bending moment by 111-329%. A more reclined seatback increased the lumbar force and bending moment by 16-165% and 67-172%, respectively.

CONCLUSIONS

This study provided a computational framework for assessing thoracolumbar fractures and also quantified the effect of precrash driver posture on thoracolumbar response. Results aid in the evaluation of motor vehicle crash-induced vertebral fractures and the understanding of factors contributing to fracture risk.

Biomechanics of Lumbar Motion-Segments in Dynamic Compression

Recent epidemiology studies have reported increase in lumbar spine injuries in frontal crashes. Whole human body finite element models (FEHBM) are frequently used to delineate mechanisms of such injuries. However, the accuracy of these models in mimicking the response of human spine relies on the characterization data of the spine model. The current study set out to generate characterization data that can be input to FEHBM lumbar spine, to obtain biofidelic responses from the models. Twenty-five lumbar functional spinal units were tested under compressive loading. A hydraulic testing machine was used to load the superior ends of the specimens. A 75N load was placed on the superior PMMA to remove the laxity in the joint and mimic the physiological load. There were three loading sequences, namely, preconditioning, 0.5 m/s (non-injurious) and 1.0 m/s (failure). Forces and displacements were collected using six-axis load cell and VICON targets. In addition, acoustic signals were collected to identify the times of failures. Finally, response corridors were generated for the two speeds. To demonstrate the corridors, GHBMC FE model was simulated in frontal impact condition with the default and updated lumbar stiffness. Bi-linear trend was observed in the force versus displacement plots. In the 0.5 m/s tests, mean toe- and linear-region stiffnesses were 0.96±0.37 and 2.44±0.92 kN/mm. In 1.0 m/s tests, the toe and linear-region stiffnesses were 1.13±0.56 and 4.6±2.5 kN/mm. Lumbar joints demonstrated 2.5 times higher stiffness in the linear-region when the loading rate was increased by 0.5 m/s.

Functional Recovery Following Early Kyphoplasty Versus Conservative Management in Stable Thoracuolumbar Fractures in Parachute Jumpers: A Randomized Clinical Trial

STUDY DESIGN

A randomized clinical trial.

OBJECTIVE

To compare the functional recovery between early kyphoplasty and conservative care in paratroopers with stable thoracolumbar fractures.

SUMMARY OF BACKGROUND DATA

Treatment of traumatic stable thoracolumbar fractures in young individuals is still a debate. Conservative management and kyphoplasty are options of therapy. But enough data are not available for supporting each.

METHODS

We included 70 paratroopers with stable thoracolumbar fractures (A1 and A2 classification according to AOSpine thoracolumbar spine injury classification system) presenting <60 days after trauma and hyperintensity in T2-weighted magnetic resonance imaging. Old fractures and those requiring fixation were excluded. Patients were randomly assigned to 2 study groups to undergo percutaneous balloon kyphoplasty (n=34) or conservative care (n=36) by applying orthosis for 2 months. Patients were followed for 12 months and were evaluated clinically using visual analogue scale (VAS) and Oswestry disability index (ODI).

RESULTS

The baseline characteristics were comparable between 2 study groups. The VAS score and ODI decreased significantly in both study groups after 12 months of treatment. The VAS score was significantly lower in kyphoplasty group after the intervention (P<0.001), 1 month (P<0.001), 3 months (P<0.001), 6 months (P<0.001), and 12 months (P<0.001) after the intervention. In addition, the ODI was significantly lower after the intervention (P<0.001), 1 month (P<0.001), 3 months (P<0.001), 6 months (P<0.001), and 12 months (P<0.001) after the intervention. Kyphoplasty was associated with shorter duration of returning to parachuting (P<0.001) and shorter duration of absence from work (P<0.001).

CONCLUSIONS

Early kyphoplasty in stable thoracolumbar fractures after parachute jumping is associated with less pain, better functional recovery, less days of absence from work, and shorter duration of returning to parachuting.

Incidence and pattern of traumatic spinal fractures and associated spinal cord injury resulting from motor vehicle collisions in China over 11 years: An observational study

To investigate the incidence and pattern of traumatic spinal fractures (TSFs) and associated spinal cord injury (SCI) resulting from motor vehicle collisions (MVCs).This was a cross-sectional study. We retrospectively reviewed 698 patients with TSFs resulting from MVCs admitted to our university-affiliated hospitals from 2001 to 2011. The incidence and pattern were summarized with respect to different age groups, fracture levels, and the role of patients.There were 464 males (66.5%) and 234 females (33.5%) aged 40.5 ± 13.8 years old. The most common roles of patients in MVCs were car drivers (189, 27.1%), pedestrians hurt by a car (155, 22.2%), and car passengers (145, 20.8%). The most common fracture levels were L1 (n = 198, 19.2%) and T12 (n = 116, 11.3%), followed by C2 (n = 86, 8.3%). A total of 298 (42.7%) patients suffered a spinal cord injury. The frequencies of SCIs decreased from 53.1% to 24.6% with increasing age. The patients in the 20 to 39 age group (45.3% of all patients) had the largest sex ratio (2.4) and highest frequency of complete SCIs (19.3%) and complications (3.2%). Motorcycle drivers had the youngest mean age (35.7 ± 10.2), largest sex ratio (10.4), and highest frequency of SCIs (56.0%) and complications (4.4%). Motorcycle passengers had the highest frequency of complete SCI (22.7%) and ASOIs (45.5%) and the largest mean injury severity scoring (ISS) (18.9 ± 9.6). The most common fracture levels of motorcycle drivers were C3-C7, while that of others were T11-L2.The most common role of patients who sustained TSFs were car drivers who were 20 to 39 years old. Motorcycle drivers had the highest frequency of SCIs and complications. Motorcycle passengers had the highest frequency of complete SCIs and ASOIs and the largest ISS. Therefore, we should pay more attention to MVC patients, especially car drivers and motorcycle drivers and passengers.

Multicenter analysis of CIREN occupant lumbar bone mineral density and correlation with age and fracture incidence

OBJECTIVE

This study aimed to quantify lumbar volumetric bone mineral density (vBMD) for 873 seriously injured Crash Injury Research and Engineering Network (CIREN) motor vehicle crash occupants (372 male, 501 female) from 8 centers using phantomless computed tomography scans and to associate vBMD with age, fracture incidence, and osteopenia/osteoporosis diagnoses. The novelty of this work is that it associates vBMD with region of injury by applying an established method for vBMD measurement using phantomless computed tomography (CT).

METHODS

A validated phantomless CT calibration method that uses patient-specific fat and muscle measurements to calibrate vBMD measured from the L1-L5 trabeculae was applied on 873 occupants from various CIREN centers. CT-measured lumbar vBMD < 145 mg/cc is indicative of osteopenia using a published threshold. CIREN occupant lumbar vBMD in milligrams per cubic centimeter was regressed against age, osteopenia/osteoporosis comorbidities, height, weight, body mass index (BMI), and the incidence of fracture in vertebral (cervical, thoracic, lumbar) and rib/sternum regions.

RESULTS

Among the 873 occupants analyzed, 11% (92 occupants) were diagnosed as osteopenic in CIREN. Of these 92 occupants, 42% (39 occupants) had normal vBMD measures (≥145 mg/cc), suggesting possible misclassification in CIREN. Of the 134 occupants classified as osteopenic in vBMD analysis, 60% were not classified as osteopenic in CIREN, suggesting undiagnosed osteopenia, and 40% were correctly classified in CIREN. Age was negatively correlated with vBMD (P <.0001) and occupants with <145 mg/cc vBMD sustained a median number of 2 rib/sternum fractures compared to a median value of 0 rib/sternum fractures for the ≥145 mg/cc vBMD group (P <.0001). Vertebral fracture analysis revealed that the thoracolumbar region was the most common region of injury in the spine. Though the incidence of fracture was not significantly different in the thoracic (10% versus 6%, P =.122) and lumbar (16% versus 13%, P =.227) regions between the 2 bone quality groups, the proportion of thoracolumbar fractures was significantly higher in occupants with <145 mg/cc vBMD versus occupants with ≥145 mg/cc vBMD (24% versus 17%, P =.043).

CONCLUSIONS

Low lumbar vertebral bone quality is associated with an increased number of rib/sternum fractures and a greater incidence of thoracolumbar vertebral body fractures within the CIREN population analyzed.

The epidemiology of thoracolumbar trauma: A meta-analysis

PURPOSE

To describe the epidemiology of thoracolumbar fractures and associated injuries in blunt trauma patients.

METHODS

A systematic review and metaanalysis was performed based on a MEDLINE database search using MeSH terms for studies matching our inclusion criteria. The search yielded 21 full-length articles, each sub-grouped according to content. Data extraction and multiple analyses were performed on descriptive data.

RESULTS

The rate of thoracolumbar fracture in blunt trauma patients was 6.90% (±3.77, 95% CI). The rate of spinal cord injury was 26.56% (±10.70), and non-contiguous cervical spine fracture occurred in 10.49% (±4.17). Associated injury was as follows: abdominal trauma 7.63% (±9.74), thoracic trauma 22.64% (±13.94), pelvic trauma 9.39% (±6.45), extremity trauma 18.26% (±5.95), and head trauma 12.96% (±2.01). Studies that included cervical spine fracture with thoracolumbar fracture had the following rates of associated trauma: 3.78% (±5.94) abdominal trauma, 21.65% (±16.79) thoracic trauma, 3.62% (±1.07) pelvic trauma, 18.36% (±4.94) extremity trauma, and 15.45% (±11.70) head trauma. A subgroup of flexion distraction injuries showed an associated intra-abdominal injury rate of 38.70% (±13.30). The most common vertebra injured was L1 at a rate of 34.40% (±15.90). T7 was the most common non-junctional vertebra injured at 3.90% (±1.09). Burst/AO type A3 fractures were the most common morphology 39.50% (±16.30) followed by 33.60% (±15.10) compression/AO type A1, 14.20% (±8.08) fracture dislocation/AO type C, and 6.96% (±3.50) flexion distraction/AO type B. The most common etiology for a thoracolumbar fracture was motor vehicle collision 36.70% (±5.35), followed by high-energy fall 31.70% (±6.70).

CONCLUSIONS

Here we report the incidence of thoracolumbar fracture in blunt trauma and the spectrum of associated injuries. To our knowledge, this paper provides the first epidemiological road map for blunt trauma thoracolumbar injuries.

Occupant and Crash Characteristics of Elderly Subjects With Thoracic and Lumbar Spine Injuries After Motor Vehicle Collisions

STUDY DESIGN

Retrospective study of a prospectively gathered database.

OBJECTIVE

To investigate the incidence and pattern of thoracic and lumbar (T and L) spine injuries among elderly subjects involved in motor vehicle collision (MVC).

SUMMARY OF BACKGROUND DATA

Adults age 65 and older currently constitute more than 16% of all licensed drivers. Despite driving less than the young, older drivers are involved in a higher proportion of crashes. Notwithstanding the safety features in modern vehicles, 15.8% to 51% of all T and L spine injuries result from MVCs.

METHODS

Crash Injury Research and Engineering Network database is a prospectively maintained, multicentered database that enrolls MVC occupants with moderate-to-severe injuries. It was queried for T and L spine injuries in subjects 65 and older. 142 Crash Injury Research and Engineering Network files for all elderly individuals were reviewed for demographic, injury, and crash data. Each occupant's T and L injury was categorized using a modified Denis classification.

RESULTS

Of 661 elderly subjects, 142 (21.48%) sustained T and L spine injuries. Of the 102 major injuries, there were 63 compression, 20 burst and 12 extension fractures. Seatbelt use predisposed elderly subjects to compression and burst fractures, whereas seatbelt and airbag use predisposed to burst fractures. Deployment of airbags without seatbelt use appeared to predispose elderly subjects to neurological injury, higher Injury Severity Score, and higher mortality. Occupants using 3-point belts who had airbags deployed during the collision had the lowest rates of fatality and neurological injury.

CONCLUSION

T and L spine injuries in the elderly are not uncommon despite restraint use. Whereas seatbelts used alone and in conjunction with airbag deployment reduced fatalities and neurological injuries in the elderly, deployment of airbags in occupants without seatbelts predisposed to more severe injury.

Incidence and mechanism of neurological deficit after thoracolumbar fractures sustained in motor vehicle collisions

OBJECT To determine the incidence of and assess the risk factors associated with neurological injury in motor vehicle occupants who sustain fractures of the thoracolumbar spine. METHODS In this study, the authors queried medical, vehicle, and crash data elements from the Crash Injury Research and Engineering Network (CIREN), a prospectively gathered multicenter database compiled from Level I trauma centers. Subjects had fractures involving the T1-L5 vertebral segments, an Abbreviated Injury Scale (AIS) score of ≥ 3, or injury to 2 body regions with an AIS score of ≥ 2 in each region. Demographic parameters obtained for all subjects included age, sex, height, body weight, and body mass index. Clinical parameters obtained included the level of the injured vertebra and the level and type of spinal cord injury. Vehicular crash data included vehicle make, seatbelt type, and usage and appropriate use of the seatbelt. Crash data parameters included the principal direction of force, change in velocity on impact (ΔV), airbag deployment, and vehicle rollover. The authors performed a univariate analysis of the incidence and the odds of sustaining spinal neurological injury associated with major thoracolumbar fractures with respect to the demographic, clinical, and crash parameters. RESULTS Neurological deficit associated with thoracolumbar fracture was most frequent at extremes of age; the highest rates were in the 0- to 10-year (26.7% [4 of 15]) and 70- to 80-year (18.4% [7 of 38]) age groups. Underweight occupants (OR 3.52 [CI 1.055-11.7]) and obese occupants (OR 3.27 [CI 1.28-8.31]) both had higher odds of sustaining spinal cord injury than occupants with a normal body mass index. The highest risk of neurological injury existed in crashes in which airbags deployed and the occupant was not restrained by a seatbelt (OR 2.35 [CI 0.087-1.62]). Reduction in the risk of neurological injuries occurred when 3-point seatbelts were used correctly in conjunction with the deployment of airbags (OR 0.34 [CI 1.3-6.6]) compared with the occupants who were not restrained by a seatbelt and for whom airbags were not deployed. Crashes with a ΔV greater than 50 km/hour had a significantly higher risk of spinal cord injury (OR 3.45 [CI 0.136-0.617]) than those at lower ΔV values. CONCLUSIONS Deployment of airbags was protective against neurological injury only when used in conjunction with 3-point seatbelts. Vehicle occupants who were either obese or underweight, very young or elderly, and those in crashes with a ΔV greater than 50 km/hour were at higher risk of thoracolumbar neurological injury. Neurological injury at thoracic and lumbar levels was associated with multiple factors, including the incidence of fatality, occupant factors such as age and body habitus, energy at impact, and direction of impact. Current vehicle safety technologies are geared toward a normative body morphology and need to be reevaluated for various body morphologies and torso compliances to lower the risk of neurological injury resulting from thoracolumbar fractures.

Spinal injuries in an airplane crash: a description of incidence, morphology, and injury mechanism

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

Spinal injuries of the survivors of an airplane crash are described. On the basis of injury morphology and knowledge of the conditions of the accident, injury mechanisms are described and prevention measures are discussed.

SUMMARY OF BACKGROUND DATA

The most common causes of spinal fractures are a high energy fall (incidence 21.2%-39%) and motor vehicle accidents (21.7%-33.61%). Detailed reports solely on spinal injuries, as a result of an airplane crash, are scarce in literature.

METHODS

An analysis was performed on the spinal injuries of all 126 survivors of a commercial airplane (Boeing 737) crash near Amsterdam in 2009. Level of injury and fracture classification by morphology, independently performed by 4 specialists in spinal trauma, was documented. An analysis was done on the type of injuries and the suggested mechanism of injury by evaluating the crash characteristics analysis.

RESULTS

Twenty-three (18.3%) of the survivors sustained a total of 27 spinal injuries. Four (17.1% of the patients with spinal injury) experienced a single cervical spine fracture. Eight (29.6%) injuries were at the thoracic spine and 15 (55.6%) at the lumbar spine level. More than half of the injuries included a burst component.

CONCLUSION

A high number of spinal injuries was found after this airplane crash. The morphology of the injuries consisted of a high rate of burst-type fractures presumably caused by a mainly vertical trauma mechanism as shown by the accident analysis.

LEVEL OF EVIDENCE

4.

Has the incidence of thoracolumbar spine injuries increased in the United States from 1998 to 2011?

BACKGROUND

While most motor vehicle crash (MVC)-related injuries have been decreasing, one study showed increases in MVC-related spinal fractures from 1994 to 2002 in Wisconsin. To our knowledge, no studies evaluating nationwide trends of MVC-related thoracolumbar spine injuries have been published. Such fractures can cause pain, loss of functionality or even death. If the incidence of such injuries is increasing, it may provide a motive for reassessment of current vehicle safety design.

QUESTIONS/PURPOSES

We questioned whether the incidence of thoracolumbar spine injuries increased in the United States population with time (between 1998 and 2011), and if there was an increased incidence of thoracolumbar injuries, whether there were identifiable compensatory "trade-off injury" patterns, such as reductions in sacropelvic injuries.

PATIENTS AND METHODS

Institutional review board approval was obtained for retrospective review of three national databases: the National Trauma Databank® (NTDB®), 2002-2006, National Automotive Sampling System (NASS), 2000-2011, and National Inpatient Sample (NIS), 1998-2007. In each database, the total number of MVC-related injuries and the number of MVC-related thoracolumbar injuries per year were identified using appropriate Abbreviated Injury Scale (AIS) or ICD-9 codes. Sacropelvic injuries also were identified to evaluate their potential as trade-off injuries. Poisson regression models adjusting for age were used to analyze trends in the data with time.

RESULTS

All databases showed increases in MVC-related thoracolumbar spine injuries when adjusting for age with time. These age-adjusted relative annual percent increases ranged from 8.22% (95% CI, 5.77%-10.72%; p<0.001) using AIS of 2 or more (AIS2 +) injury codes in the NTDB®, 8.59% (95% CI, 5.88%-11.37%; p<0.001) using ICD-9 codes in the NTDB®, 8.12% (95% CI, 7.20%-9.06%; p<0.001) using ICD-9 codes in the NIS, and 8.10 % (95% CI 5.00%-11.28%; p<0.001) using AIS2+ injury codes in the NASS. As these thoracolumbar injuries have increased, there has been no consistent trend toward a compensatory reduction in terms of sacropelvic injuries.

CONCLUSIONS

While other studies have shown that rates of many MVC-related injuries are declining with time, our data show increases in the incidence of thoracolumbar injury. Although more sensitive screening tools likely have resulted in earlier and increased recognition of these injuries, it cannot be stated for certain that this is the only driver of the increased incidence observed in this study. As seatbelt use has continued to increase, this trend may be the result of thoracolumbar injuries as trade-offs for other injuries, although in our study we did not see a compensatory decrease in sacropelvic injuries. Investigation evaluating the root of this pattern is warranted.

High Rotation Rate Behavior of Cervical Spine Segments in Flexion and Extension

Numerical finite element (FE) models of the neck have been developed to simulate occupant response and predict injury during motor vehicle collisions. However, there is a paucity of data on the response of young cervical spine segments under dynamic loading in flexion and extension, which is essential for the development or validation of tissue-level FE models. This limitation was identified during the development and validation of the FE model used in this study. The purpose of this study was to measure the high rotation rate loading response of human cervical spine segments in flexion and extension, and to investigate a new tissue-level FE model of the cervical spine with the experimental data to address a limitation in available data. Four test samples at each segment level from C2–C3 to C7–T1 were dissected from eight donors and were tested to 10 deg of rotation at 1 and 500 deg/s in flexion and extension using a custom built test apparatus. There was strong evidence (p < 0.05) of increased stiffness at the higher rotation rate above 4 deg of rotation in flexion and at 8 deg and 10 deg of rotation in extension. Cross-correlation software, Cora, was used to evaluate the fit between the experimental data and model predictions. The average rating was 0.771, which is considered to demonstrate a good correlation to the experimental data.

Occupant and crash characteristics in thoracic and lumbar spine injuries resulting from motor vehicle collisions

BACKGROUND CONTEXT

Motor vehicle collisions (MVC) are a leading cause of thoracic and lumbar (T and L) spine injuries. Mechanisms of injury in vehicular crashes that result in thoracic and lumbar fractures and the spectrum of injury in these occupants have not been extensively studied in the literature.

PURPOSE

The objective was to investigate the patterns of T and L spine injuries after MVC; correlate these patterns with restraint use, crash characteristics, and demographic variables; and study the associations of these injuries with general injury morbidity and fatality.

STUDY DESIGN/SETTING

The study design is a retrospective study of a prospectively gathered database.

PATIENT SAMPLE

Six hundred thirty-one occupants with T and L (T1-L5) spine injuries from 4,572 occupants included in the Crash Injury Research and Engineering Network (CIREN) database between 1996 and 2011 were included in this study.

OUTCOME MEASURES

No clinical outcome measures were evaluated in this study.

METHODS

The CIREN database includes moderate to severely injured occupants from MVC involving vehicles manufactured recently. Demographic, injury, and crash data from each patient were analyzed for correlations between patterns of T and L spine injuries, associated extraspinal injuries and overall injury severity score (ISS), type and use of seat belts, and other crash characteristics. T and L spine injuries patterns were categorized using a modified Denis' classification to include extension injuries as a separate entity.

RESULTS

T and L spine injuries were identified in 631 of 4,572 vehicle occupants, of whom 299 sustained major injuries (including 21 extension injuries) and 332 sustained minor injuries. Flexion-distraction injuries were more prevalent in children and young adults and extension injuries in older adults (mean age, 65.7 years). Occupants with extension injuries had a mean body mass index of 36.0 and a fatality rate of 23.8%, much higher than the fatality rate for the entire cohort (10.9%). The most frequent extraspinal injuries (Abbreviated Injury Scale Grade 2 or more) associated with T and L spine injuries involved the chest (seen in 65.6% of 631 occupants). In contrast to occupants with major T and L spine injuries, those with minor T and L spine injuries showed a strikingly greater association with pelvic and abdominal injuries. Occupants with minor T and L spine injuries had a higher mean ISS (27.1) than those with major T and L spine injuries (25.6). Among occupants wearing a three-point seat belt, 35.3% sustained T and L spine injuries, whereas only 11.6% of the unbelted occupants sustained T and L spine injuries. Three-point belted individuals were more likely to sustain burst fractures, whereas two-point belted occupants sustained flexion-distraction injuries most often and unbelted occupants had a predilection for fracture-dislocations of the T and L spines. Three-point seat belts were protective against neurologic injury, higher ISS, and fatality.

CONCLUSIONS

T and L spine fracture patterns are influenced by the age of occupant and type and use of seat belts. Despite a reduction in overall injury severity and mortality, seat belt use is associated with an increased incidence of T and L spine fractures. Minor T and L spine fractures were associated with an increased likelihood of pelvic and abdominal injuries and higher ISSs, demonstrating their importance in predicting overall injury severity. Extension injuries occurred in older obese individuals and were associated with a high fatality rate. Future advancements in automobile safety engineering should address the need to reduce T and L spine injuries in belted occupants.

Health-related quality-of-life outcomes after thoracic (T1-T10) fractures

BACKGROUND CONTEXT

The thoracic spine exhibits a unique response to trauma as the result of recognized anatomical and biomechanical differences. Despite this response, clinical studies often group thoracic fractures (T1-T10) with more caudal thoracolumbar injuries. Subsequently, there is a paucity of literature on the functional outcomes of this distinct group of injuries.

PURPOSE

To describe and identify predictors of health-related quality-of-life outcomes and re-employment status in patients with thoracic fractures who present to a spine injury tertiary referral center.

STUDY DESIGN

An ambispective cohort study with cross-sectional outcome assessment.

PATIENT SAMPLE

A prospectively collected fully relational spine database was searched to identify all adult (>16 years) patients treated with traumatic thoracic (T1-T10) fractures with and without neurologic deficits, treated between 1995 and 2008.

OUTCOME MEASURES

The Short-Form-36, Oswestry Disability Index, and Prolo Economic Scale outcome instruments were completed at a minimum follow-up of 12 months. Preoperative and minimum 1-year postinjury X-rays were evaluated.

METHOD

Univariate and multivariate regression analysis was used to identify predictors of outcomes from a range of demographic, injury, treatment, and radiographic variables.

RESULTS

One hundred twenty-six patients, age 36±15 years (mean±SD), with 135 fractures were assessed at a mean follow-up of 6 years (range 1-15.5 years). Traffic accidents (45%) and translational injuries (54%) were the most common mechanism and dominant fracture pattern, respectively. Neurologic deficits were frequent-53% had complete (American Spinal Injury Association impairment scale [AIS] A) spinal cord deficits on admission. Operative management was performed in 78%. Patients who sustain thoracic fractures, but escaped significant neurologic injury (AIS D or E on admission) had SF-36 scores that did not differ significantly from population norms at a mean follow-up of 6 years. Eighty-eight percent of this cohort was re-employed. Interestingly, Oswestry Disability Index scores remained inferior to healthy subjects. In contrast, SF-36 scores in those with more profound neurologic deficits at presentation (AIS A, B, or C) remained inferior to normative data. Fifty-seven percent were re-employed, 25% in their previous job type. Using multiple regression analysis, we found that comorbidity status (measured by the Charlson Comorbidity index) was the only independent predictor of SF-36 scores. Neurologic impairment (AIS) and adverse events were independent predictors of the SF-36 physical functioning subscale. Sagittal alignment and number of fused levels were not independent predictors.

CONCLUSIONS

At a mean follow-up of 6 years, patients who presented with thoracic fractures and AIS D or E neurologic status recovered a general health status not significantly inferior to population norms. Compared with other neurologic intact spinal injuries, patients with thoracic injuries have a favorable generic health-related quality-of-life prognosis. Inferior outcomes and re-employment prospects were noted in those with more significant neurologic deficits.

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.

Cervical spine injury biomechanics: Applications for under body blast loadings in military environments

BACKGROUND

While cervical spine injury biomechanics reviews in motor vehicle and sports environments are available, there is a paucity of studies in military loadings. This article presents an analysis on the biomechanics and applications of cervical spine injury research with an emphasis on human tolerance for underbody blast loadings in the military.

METHODS

Following a brief review of published military studies on the occurrence and identification of field trauma, postmortem human subject investigations are described using whole body, intact head-neck complex, osteo-ligamentous cervical spine with head, subaxial cervical column, and isolated segments subjected to differing types of dynamic loadings (electrohydraulic and pendulum impact devices, free-fall drops).

FINDINGS

Spine injuries have shown an increasing trend over the years, explosive devices are one of the primary causal agents and trauma is attributed to vertical loads. Injuries, mechanisms and tolerances are discussed under these loads. Probability-based injury risk curves are included based on loading rate, direction and age.

INTERPRETATION

A unique advantage of human cadaver tests is the ability to obtain fundamental data to delineate injury biomechanics and establish human tolerance and injury criteria. Definitions of tolerances of the spine under vertical loads based on injuries have implications in clinical and biomechanical applications. Primary outputs such as forces and moments can be used to derive secondary variables such as the neck injury criterion. Implications are discussed for designing anthropomorphic test devices that may be used to predict injuries in underbody blast environments and improve the safety of military personnel.

Preventing motor vehicle crashes related spine injuries in children

BACKGROUND

Spinal cord injury (SCI) is a devastating event that results in permanent disability for injured children. Among all etiologies of SCI, motor vehicle crashes (MVCs) are the leading cause and account for 29% of all traumatic SCIs in children. We tried to evaluate types and mechanisms of MVC-related spinal column and spinal cord injuries, risk factors, safety issues and legislation.

DATA SOURCES

A literature review was performed using PubMed from 1966 to 12th April 2010 with the following key words: children OR pediatric, spine, injury OR trauma, restraint, seat belt, motor vehicle, road OR traffic, collision OR crash, safety. Cross referencing of discovered articles was also performed.

RESULTS

Risk factors for MVC-related SCI include single vehicle crashes, vehicle rollover, and ejection of the passenger from the vehicle. Any anatomic region of the spinal cord may be injured as a result of MVC and may vary according to the type of accident and restraint system usage. Increasing use of three-point seat belts, which are more protective than isolated lap seat belts, has decreased the incidence of MVC-related SCI. There is evidence that airbag use without seatbelt use is associated with an increased risk of cervical spine fractures with or without SCI. Vehicle designers need to give more attention to the prevention of vehicle rollover and to improve occupant protection when rollover occurs.

CONCLUSIONS

MVC is a common cause of SCI in children; therefore, paying attention to risk factors and modes of prevention is important. As MVC-related SCI can lead to permanent disability, prevention and education play an important role in decreasing childrens' morbidity and mortality. Making behavior, roads and vehicles safer can significantly reduce MVC-related SCI in children.

Trends in the treatment of lumbar spine fractures in the United States: a socioeconomics perspective

Object

The objective of this study was to investigate a national health care database and analyze demographics, hospital charges, and treatment trends of patients diagnosed with lumbar spine fractures in the US over a 5-year period.

Methods

Clinical data were derived from the Nationwide Inpatient Sample (NIS) for the years 2003 through 2007. The NIS is maintained by the Agency for Healthcare Research and Quality and represents a 20% random stratified sample of all discharges from nonfederal hospitals within the US. Patients with lumbar spine fractures were identified using the appropriate ICD-9-CM code. Data on the number of vertebral body augmentation procedures were also retrieved. National estimates of discharges, hospital charges, discharge patterns, and treatment with spinal fusion trends were retrieved and analyzed.

Results

More than 190,000 records of patients with lumbar spine fractures were abstracted from the database. During the 5-year period, there was a 17% increase in hospitalizations for lumbar spine fractures. This was associated with a 27% increase in hospital charges and a 55% increase in total national charges (both adjusted for inflation). The total health care bill associated with lumbar spine fractures in 2007 exceeded 1 billion US dollars. During this same time period, there was a 24% increase in spinal fusions for lumbar fractures, which was associated with a 15% increase in hospital charges. The ratio of spinal fusions to hospitalizations (surgical rate) during this period, however, was stable with an average of 7.4% over the 5-year period. There were an estimated 13,000 vertebral body augmentation procedures for nonpathological fractures performed in 2007 with a total national bill of 450 million US dollars.

Conclusions

An increasing trend of hospitalizations, surgical treatment, and charges associated with lumbar spine fractures was observed between 2003 and 2007 on a national level. This trend, however, does not appear to be as steep as that of surgical utilization in degenerative spine disease. Furthermore, the ratio of spinal fusions to hospitalizations for lumbar fractures appears to be stable, possibly indicating no significant changes in indications for surgical intervention over the time period studied.

Diagnostic accuracy of clinical examination in cervical spine injuries in awake and alert blunt trauma patients

Study Design

Observational, case series.

Purpose

To determine the sensitivity and specificity of clinical judgment as compared to the use of X-ray images in detecting cervical spine injuries in trauma patients presenting in the emergency department of Aga Khan University Hospital, Karachi.

Overview of Literature

Cross-table cervical spine views are important in patients with signs and symptoms relating to cervical spine, but asymptomatic patients constitute a different subgroup. Accuracy of clinical examination in these patients has not been subjected to scrutiny.

Methods

All patients with blunt trauma who presented to the emergency department and underwent cross-table X-rays as part of their trauma workup were included. The X-rays were read by a radiologist not aware of the history of the patients. We recorded demographic data along with mechanism of injury, associated neck signs or symptoms whether present or not, cervical spine range of motion, associated injuries and X-ray findings. The history and examination were carried out by the on-call neurosurgery team member. The sensitivity and specificity along with negative and positive predictive value of the clinical examination were calculated. Data were analyzed using SPSS ver. 16.0.

Results

Of 50 patients with positive signs and symptoms, 4 (8%) had positive X-rays while only 1 out of 324 (0.3%) with no associated signs and symptoms had positive X-ray findings.

Conclusions

The clinical examination is 80% sensitive and 73.98% specific in detecting true cervical spine injuries as compared to C-spine X-rays in alert and awake patients with blunt trauma.

Estudo retrospectivo dos resultados da utilização do halo craniano nas fraturas-luxações subaxiais

OBJETIVO: avaliar o emprego do halo craniano em fraturas e luxações cervicais no atendimento inicial, relacionado com a taxa de sucesso na redução fechada de lesões cervicais nos diferentes tipos de fraturas. MÉTODOS: investigação retrospectiva de prontuários de pacientes atendidos e tratados de Janeiro de 2004 até Março de 2009, em um total de 222 pacientes, categorizando as lesões encontradas de acordo com a classificação AO. RESULTADOS: encontramos alta taxa de sucesso de redução fechada em pacientes com lesões cervicais por compressão axial (AO tipo A) no emprego do halo craniano; em lesões por distração (AO tipo B) e movimento rotacional (AO tipo C) observamos aproximadamente 50% de redução fechada da luxação; além disso, lesões em níveis mais craniais apresentam maior taxa de sucesso na redução. CONCLUSÃO: o emprego do halo craniano é encorajado, pois, além de realizar um papel imobilizador no atendimento inicial, apresenta resultados satisfatórios na tentativa de redução fechada da lesão cervical, melhorando o conforto do paciente, facilitando a abordagem cirúrgica posterior e o cuidado da equipe de enfermagem.

Escolha da via cirúrgica para tratamento das fraturas cervicais

OBJETIVO: definir características epidemiológicas da população vitimada, classificar as fraturas subaxiais e analisar como foram os tratamentos cirúrgicos, tendo como desfecho a via cirúrgica escolhida - anterior, posterior ou combinada - reunindo tais dados para observar padrões de tratamento para o melhor cuidado desses doentes. MÉTODOS: análise retrospectiva em prontuários médicos de 222 pacientes atendidos e tratados entre o ano de 2004 e o mês de Março de 2009 com fraturas, fraturas-luxações e luxações cervicais. Desses 222 pacientes, 163 correspondiam àqueles que tinham fraturas subaxiais classificáveis pelo método AO, ou seja, correspondiam a aproximadamente 73,4% do total. RESULTADOS: dentre os pacientes, 83% eram homens e aproximadamente 78% tinham entre 21 e 60 anos. Foram classificados como Tipo A 54 pacientes, e 50% foram operados - 85,18% via anterior, com corpectomia associada ou não à artrodese; foram classificados como Tipo B 77 pacientes, e 85,7% foram operados - 77,3% via posterior, considerando-se a lesão ligamentar; como Tipo C foram classificados 21 pacientes, e 81% foram operados - 94,1% via posterior; como Múltiplos Níveis foram considerados 11 pacientes, e 54,5% foram operados - 83,3% via posterior, nenhum por via anterior isoladamente. CONCLUSÃO: os dados obtidos podem contribuir para a padronização do atendimento ao paciente com traumatismo cervical e tornar os resultados do tratamento mais previsíveis. A experiência acumulada e revertida em números facilitará a escolha da via cirúrgica.