Subject-Specific Geometry of FE Lumbar Spine Models for the Replication of Fracture Locations Using Dynamic Drop Tests.

For traumatic lumbar spine injuries, the mechanisms and influence of anthropometrical variation are not yet fully understood under dynamic loading. Our objective was to evaluate whether geometrically subject-specific explicit finite element (FE) lumbar spine models based on state-of-the-art clinical CT data combined with general material properties from the literature could replicate the experimental responses and the fracture locations via a dynamic drop tower-test setup. The experimental CT datasets from a dynamic drop tower-test setup were used to create anatomical details of four lumbar spine models (T12 to L5). The soft tissues from THUMS v4.1 were integrated by morphing. Each model was simulated with the corresponding loading and boundary conditions from the dynamic lumbar spine tests that produced differing injuries and injury locations. The simulations resulted in force, moment, and kinematic responses that effectively matched the experimental data. The pressure distribution within the models was used to compare the fracture occurrence and location. The spinal levels that sustained vertebral body fracture in the experiment showed higher simulation pressure values in the anterior elements than those in the levels that did not fracture in the reference experiments. Similarly, the spinal levels that sustained posterior element fracture in the experiments showed higher simulation pressure values in the vertebral posterior structures compared to those in the levels that did not sustain fracture. Our study showed that the incorporation of the spinal geometry and orientation could be used to replicate the fracture type and location under dynamic loading. Our results provided an understanding of the lumbar injury mechanisms and knowledge on the load thresholds that could be used for injury prediction with explicit FE lumbar spine models.

Kinematic response of seated male volunteers in various reclined postures on a sled subjected to a braking pulse.

Vehicle occupants expect greater postural flexibility with the introduction of highly automated vehicles, such as reclined postures. Experiments have been conducted with post mortem human subjects to study the risk of injury under impact conditions in reclined postures. However, the influence of the pre-crash phase on the kinematics in reclined postures has not yet been thoroughly studied. The aim of the present study is to investigate human responses under low g braking conditions focusing on different backrest angles in a generic sled environment. Three 50th percentile male volunteers were recruited to participate in a sled experiment. Each of them was subjected to a total of fourteen trials under a braking pulse with a maximum acceleration of 0.7 g for 700 ms. Different sitting postures were investigated: from 23° to 45°, 60° and 75° backrest tilt with respect to the vertical axis. In addition, two different seat pan tilt angles were considered: a 16° tilt angle for 23°, 45° and 60° backrest inclination and a 36° tilt angle for 60° and 75° backrest inclination. Measurements of volunteer kinematics, muscle activation and interaction forces between the volunteers and the sled, among others, were acquired. Initial results show a significant reduction in maximum forward head displacement from the upright to the reclined postures (p < 0.02), with the exception of the 45° reclined posture. However, no significant difference in maximum head displacement was found between the different reclined postures (p > 0.1). Seat pan tilt angle did significantly influence forward head excursion when considering the same seatback inclination (p < 0.01). It is of great importance to investigate occupant kinematics during the pre-crash phase to understand its influence on the potential injuries that may occur with a reclined posture in the event of a collision.

Subcutaneous adipose tissue thickness around the ASIS area for human body models in reclined positions.

OBJECTIVE: Subcutaneous adipose tissue (SAT) thickness above the anterior superior iliac spine (ASIS) influences belt fit of a vehicle occupant. To improve finite element (FE) human body models and their application assessing future seating positions in cars, there is a need for more detailed data. METHODS: Anthropometric input data were used to statistically model a lower limit of the SAT thickness in the area around the ASIS (at the ASIS or in the groin) extracted from 102 postmortem computed tomography (pmCT) data sets (56 males and 46 females). Additionally, 2 pmCT scans of 1 male individual in both supine and sitting conditions were used to estimate change in SAT thickness by position. RESULTS: Distributions and locations of minimum values for SAT thickness were derived for males and females. Sex, age, and body mass index (BMI) remained in a linear regression model for the minimum SAT thickness in the ASIS area. Thirty-seven percent of the variance in the SAT distribution of the sample can be explained by these input variables. The individual with data in supine and sitting positions showed an SAT thickness value above the ASIS 6 times higher in the sitting position than in the supine position. CONCLUSIONS: Individual factors influence SAT thickness around the ASIS in addition to BMI, sex, and age. The presented values need to be regarded as a lower limit of SAT thickness, because in 63% the minimum was found in the groin area and the measurements were performed in a supine position. The increase in SAT thickness in a sitting position compared to supine seen in the case example shows the need for further data acquisition to establish a transfer function interpolating between both positions. The SAT thickness minimum values in the ASIS area shown in this study can provide valuable input for soft tissue modeling in human body models with the aim to analyze seat belt fit and to computationally assess lap belt and occupant interaction sensitivity to SAT tissue thickness under load. This might be crucial in reclined sitting positions in automated driving.

The Effect of Seat Back Inclination on Spinal Alignment in Automotive Seating Postures.

Experimental studies have demonstrated a relationship between spinal injury severity and vertebral kinematics, influenced by the initial spinal alignment of automotive occupants. Spinal alignment has been considered one of the possible causes of gender differences in the risk of sustaining spinal injuries. To predict vertebral kinematics and investigate spinal injury mechanisms, including gender-related mechanisms, under different seat back inclinations, it is needed to investigate the effect of the seat back inclination on initial spinal alignment in automotive seating postures for both men and women. The purpose of this study was to investigate the effect of the seat back inclination on spinal alignments, comparing spinal alignments of automotive seating postures in the 20° and 25° seat back angle and standing and supine postures. The spinal columns of 11 female and 12 male volunteers in automotive seating, standing, and supine postures were scanned in an upright open magnetic resonance imaging system. Patterns of their spinal alignments were analyzed using Multidimensional Scaling presented in a distribution map. Spinal segmental angles (cervical curvature, T1 slope, total thoracic kyphosis, upper thoracic kyphosis, lower thoracic kyphosis, lumbar lordosis, and sacral slope) were also measured using the imaging data. In the maximum individual variances in spinal alignment, a relationship between the cervical and thoracic spinal alignment was found in multidimensional scaling analyses. Subjects with a more lordotic cervical spine had a pronounced kyphotic thoracic spine, whereas subjects with a straighter to kyphotic cervical spine had a less kyphotic thoracic spine. When categorizing spinal alignments into two groups based on the spinal segmental angle of cervical curvature, spinal alignments with a lordotic cervical spine showed significantly greater absolute average values of T1 slope, total thoracic kyphosis, and lower thoracic kyphosis for both the 20° and 25° seat back angles. For automotive seating postures, the gender difference in spinal alignment was almost straight cervical and less-kyphotic thoracic spine for the female subjects and lordotic cervical and more pronounced kyphotic thoracic spine for the male subjects. The most prominent influence of seatback inclination appeared in Total thoracic kyphosis, with increased angles for 25° seat back, 8.0° greater in spinal alignments with a lordotic cervical spine, 3.2° greater in spinal alignments with a kyphotic cervical spine. The difference in total thoracic kyphosis between the two seatback angles and between the seating posture with the 20° seat back angle and the standing posture was greater for spinal alignments with a lordotic cervical spine than for spinal alignments with a kyphotic cervical spine. The female subjects in this study had a tendency toward the kyphotic cervical spine. Some of the differences between average gender-specific spinal alignments may be explained by the findings observed in the differences between spinal alignments with a lordotic and kyphotic cervical spine.

Comparison of Upper Neck Loading in Young Adult and Elderly Volunteers During Low Speed Frontal Impacts.

Cervical pain and injuries are a major health problem globally. Existing neck injury criteria are based on experimental studies that included sled tests performed with volunteers, post-mortem human surrogates and animals. However, none of these studies have addressed the differences between young adults and elderly volunteers to date. Thus, this work analyzed the estimated axial and shear forces, and the bending moment at the craniocervical junction of nine young volunteers (18-30 years old) and four elderly volunteers (>65 years old) in a low-speed frontal deceleration. Since the calculation of these loads required the use of the mass and moment of inertia of the volunteers' heads, this study proposed new methods to estimate the inertial properties of the head of the volunteers based on external measurements that reduced the error of previously published methods. The estimated mean peak axial force (Fz) was -164.38 ± 35.04 N in the young group and -170.62 ± 49.82 N in the elderly group. The average maximum shear force (Fx) was -224.42 ± 54.39 N and -232.41 ± 19.23 N in the young and elderly group, respectively. Last, the estimated peak bending moment (My) was 13.63 ± 1.09 Nm in the young group and 14.81 ± 1.36 Nm in the elderly group. The neck loads experienced by the elderly group were within the highest values in the present study. Nevertheless, for the group of volunteers included in this study, no substantial differences with age were observed.

Dynamic Responses of Female Volunteers in Rear Impact Sled Tests at Two Head Restraint Distances.

The objective of this study was to assess the biomechanical and kinematic responses of female volunteers with two different head restraint (HR) configurations when exposed to a low-speed rear loading environment. A series of rear impact sled tests comprising eight belted, near 50th percentile female volunteers, seated on a simplified laboratory seat, was performed with a mean sled acceleration of 2.1 g and a velocity change of 6.8 km/h. Each volunteer underwent two tests; the first test configuration, HR10, was performed at the initial HR distance ∼10 cm and the second test configuration, HR15, was performed at ∼15 cm. Time histories, peak values and their timing were derived from accelerometer data and video analysis, and response corridors were also generated. The results were separated into three different categories, HR10 C (N = 8), HR15 C (N = 6), and HR15 N C (N = 2), based on: (1) the targeted initial HR distance [10 cm or 15 cm] and (2) whether the volunteers' head had made contact with the HR [Contact (C) or No Contact (NC)] during the test event. The results in the three categories deviated significantly. The greatest differences were found for the average peak head angular displacements, ranging from 10° to 64°. Furthermore, the average neck injury criteria (NIC) value was 22% lower in HR10 C (3.9 m2/s2), and 49% greater in HR15 N C (7.4 m2/s2) in comparison to HR15 C (5.0 m2/s2). This study supplies new data suitable for validation of mechanical or mathematical models of a 50th percentile female. A model of a 50th percentile female remains to be developed and is urgently required to complement the average male models to enhance equality in safety assessments. Hence, it is important that future protection systems are developed and evaluated with female properties taken into consideration too. It is likely that the HR15 test configuration is close to the limit for avoiding HR contact for this specific seat setup. Using both datasets (HR15 C and HR15 N C ), each with its corresponding HR contact condition, will be possible in future dummy or model evaluation.

Interobserver variability of injury severity assessment in polytrauma patients: does the anatomical region play a role?

BACKGROUND: The Abbreviated Injury Scale (AIS) and Injury Severity Score (ISS) are widely used to assess trauma patients. In this study, the interobserver variability of the injury severity assessment for severely injured patients was analyzed based on different injured anatomical regions, and the various demographic backgrounds of the observers. METHODS: A standardized questionnaire was presented to surgical experts and participants of clinical polytrauma courses. It contained medical information and initial X-rays/CT-scans of 10 cases of severely injured patients. Participants estimated the severity of each injury based on the AIS. Interobserver variability for the AIS, ISS, and New Injury Severity Score (NISS) was calculated by employing the statistical method of Krippendorff's α coefficient. RESULTS: Overall, 54 participants were included. The major contributing medical specialties were orthopedic trauma surgery (N = 36, 67%) and general surgery (N = 13, 24%). The measured interobserver variability in the assessment of the overall injury severity was high (α ISS: 0.33 / α NISS: 0.23). Moreover, there were differences in the interobserver variability of the maximum AIS (MAIS) depending on the anatomical region: αhead and neck: 0.06, αthorax: 0.45, αabdomen: 0.27 and αextremities: 0.55. CONCLUSIONS: Interobserver agreement concerning injury severity assessment appears to be low among clinicians. We also noted marked differences in variability according to injury anatomy. The study shows that the assessment of injury severity is also highly variable between experts in the field. This implies the need for appropriate education to improve the accuracy of trauma evaluation in the respective trauma registries.

Biological variability of cell-free DNA in healthy females at rest within a short time course.

INTRODUCTION: Alterations in cell-free DNA concentration (cfDNA) over time have been studied in diseased or injured patients or analyzed in athletes during exhaustive exercise. However, no fluctuations have been examined over a short time course in healthy humans at rest so far, wherefore the aim of this study was to examine individual variations at different time points within 75 min. METHODS: Serial blood drawing was performed in 14 healthy female volunteers at rest within 75 min. Plasma DNA was quantified by real-time qPCR, and absolute levels were analyzed together with relative variations. cfDNA alterations were moreover analyzed in consideration of potential volunteer-related impact factors (e.g., pulse) and were compared to alterations of plasma CK and AST. RESULTS: Absolute cfDNA concentration ranged from 0.6 to 3.4 ng/ml. Regarding alterations over time, positive and negative variations were identified, whereby the interdecile range of fold changes was from 0.5 to 1.4. The maximum fold change was determined at 10 min. No relations were found between cfDNA levels and the analyzed individual factors. CONCLUSION: We evidenced the variability of cfDNA in healthy humans at rest within a short time course. The determined variations should serve in future studies to distinguish small cfDNA increases after minor trauma from natural fluctuations. Without such reference of intra-individual variation at rest, it would not be feasible to distinguish an injury from a fluctuation with certainty. Thus, a basis was established for the application of cfDNA as biomarker for the detection of mild injuries in forensic biomechanics.

Maximum tensile stress and strain of skin of the domestic pig-differences concerning pigs from organic and non-organic farming.

The purpose of this work has been to determine differences in biomechanical properties of porcine skin from organic and non-organic farming as porcine skin is widely used as a model for human skin. A test apparatus was used, using gravity to stretch and finally tear a dumbbell-shaped specimen of prepared abdominal skin with a testing surface area of 25 × 4 mm. A total of 32 specimens were taken from seven individual pigs, three from organic and four from non-organic farming, in different orientations with respect to the Langer's lines. The tests were performed at a dynamic speed of around 1.66 m/s (corresponding to a nominal strain rate of 67 s-1). Engineering strain at rupture was higher in pig skin from non-organic farming with values up to 321% as opposed to 90% in organic pig skin. The maximum tensile stress found in non-organic pig skin was lower than in pig skin from organic farming with maximum values of 34 MPa as opposed to 58 MPa. The reason for the difference in biomechanical properties is unclear; the effect of sunlight is discussed as well as other factors like age and exercise. It seems that the biomechanical properties of porcine skin from organic farming are more similar to those of human skin.

Feasibility study of a safe sled environment for reclined frontal deceleration tests with human volunteers.

Objective: The goal of the study was to assess the feasibility of a safe crash environment for volunteer tests in reclined seating positions. An iterative multimodal approach was chosen, consisting of full-body human body model (HBM) simulations, anthropomorphic test device (ATD) physical testing, and volunteer testing.Methods: To estimate a noninjurious deceleration pulse, the iterative inclination of the seat was supported through HBM simulations and physical ATD testing. One male volunteer was exposed to 5 low-speed frontal sled impacts with stepwise reclined seat angles. The volunteer was restrained with a non-pretensioned 3-point seat belt. All procedures were approved by the relevant ethics boards.Results: Volunteer sled tests in 3 different seat configurations were performed with one volunteer at noninjurious deceleration levels. Inclination of the seat and the absence of a footrest resulted in elevated axial seat reaction forces and almost pure translational motion of the human body.Conclusions: A maximum speed of 7.1 km/h and peak deceleration of 3.0 g was found to be a safe pulse for volunteer testing in frontal impacts with a rigid reclined seat. Larger soft tissue deformations were observed when reclined, possibly associated with higher shear loads within the soft tissue. Preliminary results highlight trade-offs between the degree of seat angulation, friction force, and restraint capability of a 3-point seat belt, thus causing forward translation and/or axial spinal compression of the occupant that may need to be addressed in the future.

Comparing consequences of using two different definitions for body regions for the improvement of personal protective equipment for powered two-wheelers.

Objective: Various definitions and uses of the term body region can be found in the literature. A definition of body regions using the Abbreviated Injury Scale (AIS) codes not strictly aligned with AIS chapters was developed for use in the European Commission-funded PIONEERS project (Protective Innovations of New Equipment for Enhanced Rider Safety). This work aims to examine the consequences of differently defined body regions on injury priority ranking using the percentage of patients showing at least moderate injury severity (AIS 2+) per regarded body region.Methods: Three different crash investigation data sets of injured riders and/or pillion riders of powered 2-wheelers (PTWs) were used for this analysis. The first contained data for 143 fatalities, the second contained data for 58 severely injured, and the last for contained data for 982 patients from a sample that was close to national representativeness. Frequency of injury was examined using body regions based on the AIS chapters (and first digit of the AIS Unique Identifier) and based on the PIONEERS definition.Results: Though different body region definitions did not result in different top-ranked body regions in terms of injury frequency, different definitions did provide different levels of information that impact priority within AIS chapter-defined regions. For PTW riders, cervical injuries are the highest priority spinal injuries. Thoracic and lumbar spinal injuries seem to occur together with other injuries in the thorax and abdominal region. Severe lower extremity injuries frequently involve the pelvis and the leg.Conclusions: Body regions need to be defined carefully to avoid misinterpretations. Publications that use body regions for their analysis to present injury frequencies should clearly define what they include in each region.

Relationship Between Cervical, Thoracic, and Lumbar Spinal Alignments in Automotive Seated Posture.

The purpose of this study was to investigate the relationship between cervical, thoracic, and lumbar spinal alignments in one automotive occupant seated posture. An image dataset of the spinal column in the automotive seated posture, previously acquired by an upright open magnetic resonance imaging (MRI) system, was re-analyzed in this study. Spinal alignments were presented by the geometrical centers of the vertebral bodies extracted from the image data. Cervical, thoracic, and lumbar spinal alignments were analyzed separately with multidimensional scaling (MDS). Based on distribution maps of cervical, thoracic, and lumbar spinal alignments created by MDS, representative spinal alignment patterns of the cervical, thoracic, and lumbar spines and the relationship between cervical, thoracic, and lumbar spinal alignments were investigated. As a result, this study found a correlation between cervical and thoracic spinal alignments in an automotive occupant seated posture. According to representative spinal alignment patterns illustrated by the distribution map of spinal alignments, subjects who had kyphotic cervical spinal alignment tended to have less kyphotic thoracic spinal alignment, while subjects who had lordotic cervical spinal alignment tended to have more kyphotic thoracic spinal alignment. For lumbar spinal alignments, no prominent relationship was found between cervical and thoracic spinal alignment in the seated condition of this study.

A priori prediction of the probability of survival in vehicle crashes using anthropomorphic test devices and human body models.

Objective: In the development of restraint systems, anthropomorphic test devices (ATDs) and human body models (HBMs) are used to estimate occupant injury risks. Due to conflicting objectives, this approach limits an injury severity risk tradeoff between the different body regions. Therefore, we present and validate a protocol for the aggregation of injury risks of body regions to a probability of survival (PoS). Methods: Injuries were clustered in regions similar to ATD or HBM investigations and the most severe injury as rated by the Maximum Abbreviated Injury Scale (MAIS) per body region was determined. Each injury was transformed into a dichotomous variable with regard to the injury severity level (e.g., MAIS 3+) whose injury risk was computed using the German In-Depth Accident Study (GIDAS) and NASS-CDS databases. Without loss of generality, we focus on 2 body regions-Head/face/neck (HFN) and chest (C)-at the MAIS 3+ level. The PoS was calculated using injury outcomes from the databases. The method of predicting PoS was validated by stratifying the database by crash type and technical crash severity. Results: The PoS of occupants injured in both HFN and C at the AIS 3+ level was found to be lower, at a statistically significant level, than that of occupants with AIS 3+ injuries to just one of the body regions. Focusing on occupants with only one body region injured at the AIS 3+ level, HFN injuries tended to decrease PoS more than chest injuries. For the validation cases, observed PoS could be reproduced in the majority of cases. When comparing predicted to observed values, a correlation of R2 = 0.92 was observed when not taking the restraint system into account. Focusing on frontal crashes, the correlation was R2 = 0.89. Considering only belted occupants, R2 increased to 0.93, whereas for cases with deployed airbag systems the R2 decreased to 0.68. The PoS for side crashes is reproduced with R2= 0.97 independent of the restraint system; it was 0.95 with belted occupants and 0.55 when also factoring in airbag deployment. Conclusions: The method showed an excellent predictive capability when disregarding the restraint system, or restraint-specific subgroups, for the considered validation cases.

Are Pre-hospital Trauma Deaths Preventable? A Systematic Literature Review.

BACKGROUND: The first and largest peak of trauma mortality is encountered on the trauma site. The aim of this study was to determine whether these trauma-related deaths are preventable. We performed a systematic literature review with a focus on pre-hospital preventable deaths in severely injured patients and their causes. METHODS: Studies published in a peer-reviewed journal between January 1, 1990 and January 10, 2018 were included. Parameters of interest: country of publication, number of patients included, preventable death rate (PP = potentially preventable and DP = definitely preventable), inclusion criteria within studies (pre-hospital only, pre-hospital and hospital deaths), definition of preventability used in each study, type of trauma (blunt versus penetrating), study design (prospective versus retrospective) and causes for preventability mentioned within the study. RESULTS: After a systematic literature search, 19 papers (total 7235 death) were included in this literature review. The majority (63.1%) of studies used autopsies combined with an expert panel to assess the preventability of death in the patients. Pre-hospital death rates range from 14.6 to 47.6%, in which 4.9-11.3% were definitely preventable and 25.8-42.7% were potentially preventable. The most common (27-58%) reason was a delayed treatment of the trauma victims, followed by management (40-60%) and treatment errors (50-76.6%). CONCLUSION: According to our systematic review, a relevant amount of the observed mortality was described as preventable due to delays in treatment and management/treatment errors. Standards in the pre-hospital trauma system and management should be discussed in order to find strategies to reduce mortality.

Can a threshold for 11-nor-9-carboxy-Δ9 -tetrahydrocannabinol in hair be derived when its respective concentration in blood serum indicates regular use?

A 100 µg/L or higher concentration of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in blood serum is generally assumed to be associated with regular and/or heavy use of cannabis. At present, determination of the extent of cannabis use by means of the concentration of THC-COOH in hair has not been assessed. Therefore, we aimed at establishing a threshold for THC-COOH concentrations in hair to prove frequent consumption by comparing THC-COOH concentrations in 129 corresponding serum and hair samples, respectively. The concentration of THC-COOH in the serum was analyzed by gas chromatography-mass spectrometry and in the hair by liquid chromatography-tandem mass spectrometry. Data were statistically evaluated using receiver operating characteristic curves and contingency tables. Our results suggest that a THC-COOH concentration of ≥4.2 pg/mg in hair was always accompanied by a THC-COOH concentration of at least 100 µg/L in blood serum. Should this be confirmed by further studies of a larger study population, a hair concentration of 4.2 pg/mg THC-COOH can be set as a threshold to predict regular and/or heavy consumption of cannabis even if no corresponding blood sample is available for analysis.

Quantitative analysis of individual cell-free DNA concentration before and after penetrating trauma.

INTRODUCTION: Cell-free DNA (cfDNA) elevations were remarked in the blood of trauma patients. Published increases refer to comparative values of a healthy control group, ignoring thereby inter- and intra-individual differences under normal conditions. The aim of this study was to quantify cfDNA in patients in the time course of a planned orthopedic surgery, which constitutes the advantage of obtaining individual pre- and post-trauma values for each patient. By this approach, a basis should be established for the potential future application of cfDNA as biomarker for the detection of mild injuries related to volunteer experiments in forensic biomechanics. METHODS: Plasma samples of ten patients obtaining knee or hip arthroplasty were analyzed quantitatively for cfDNA by real-time qPCR the day prior operation (Prior), immediately afterwards (Day0), and the day after the surgery (Day1). RESULTS: Prior values exhibited a broad range, indicating pronounced inter-individual differences in the basic level of cfDNA. After surgery, levels were significantly elevated on both days (Wilcoxon test p = 0.002). In nine patients, highest values were measured on Day0, whereby a fold change of 19 was remarked once. After Day0, values decreased, though they did not reach Prior values until Day1 in nine patients. CONCLUSION: Endoprosthesis surgery represents a well-defined trauma scenario for the measurement of individual cfDNA elevations. The analysis of pre- to post-trauma alterations lay the groundwork for the application of cfDNA as biomarker for the detection of minor injuries in the field of forensic biomechanics.

Chest injuries of elderly postmortem human surrogates (PMHSs) under seat belt and airbag loading in frontal sled impacts: Comparison to matching THOR tests.

OBJECTIVE: The goal of the study was to develop experimental chest loading conditions that would cause up to Abbreviated Injury Scale (AIS) 2 chest injuries in elderly occupants in moderate-speed frontal crashes. The new set of experimental data was also intended to be used in the benchmark of existing thoracic injury criteria in lower-speed collision conditions. METHODS: Six male elderly (age >63) postmortem human subjects (PMHS) were exposed to a 35 km/h (nominal) frontal sled impact. The test fixture consisted of a rigid seat, rigid footrest, and cable seat back. Two restraint conditions (A and B) were compared. Occupants were restrained by a force-limited (2.5 kN [A] and 2 kN [B]) seat belt and a preinflated (16 kPa [A] and 11 kPa [B]; airbag). Condition B also incorporated increased seat friction. Matching sled tests were carried out with the THOR-M dummy. Infra-red telescoping rod for the assessment of chest compression (IRTRACC) readings were used to compute chest injury risk. PMHSs were exposed to a posttest injury assessment. Tests were carried out in 2 stages, using the outcome of the first one combined with a parametric study using the THUMS model to adjust the test conditions in the second. All procedures were approved by the relevant ethics board. RESULTS: Restraint condition A resulted in an unexpected high number of rib fractures (fx; 10, 14, 15 fx). Under condition B, the adjustment of the relative airbag/occupant position combined with a lower airbag pressure and lower seat belt load limit resulted in a reduced pelvic excursion (85 vs. 110 mm), increased torso pitch and a substantially lower number of rib fractures (1, 0, 4 fx) as intended. CONCLUSIONS: The predicted risk of rib fractures provided by the THOR dummy using the Cmax and PC Score injury criteria were lower than the actual injuries observed in the PMHS tests (especially in restraint condition A). However, the THOR dummy was capable of discriminating between the 2 restraint scenarios. Similar results were obtained in the parametric study with the THUMS model.

Fatal falls in the elderly and the presence of proximal femur fractures.

Fatal falls are frequent and seem to be an increasing problem in the elderly. Especially ground level falls (GLFs) and falls on or from stairs and steps (stairs falls) are worth examining for forensic classification and in order to improve the development of preventive measures. We retrospectively analyzed 261 fatal falls of elderly age 65 + years, which were autopsied at the Institute of Legal Medicine in Munich between 2008 and 2014. After careful screening, the sub-set of all 77 GLFs and 39 stairs falls were analyzed towards socio-demographic characteristics, fall circumstances, injuries, and circumstances of death. A subsequent analysis of GLF cases regarding the presence of proximal femur fractures (PFF) was performed. The injury pattern of the GLFs and the stairs falls clearly differ with a higher share of injuries to the lower extremities in the GLFs. However, the most severely injured body region was the head in both groups (62% of the stairs cases, 49% of the GLF cases). Alcohol as contributing to the fall was seen more frequently in the stairs falls. PFF were not seen in the stairs falls, but then in 18 GLF cases. Yet, for 17 among them (22% of 77), their hip fracture was the only serious injury leading to hospitalization and death. Only one GLF case was already found dead. This finding indicates a potential of avoiding up to 22% of the GLF fatalities by preventing hip fractures by optimized hip protectors or other measures, especially for the elderly aged 75 + years.

Accident analysis to support the development of strategies for the prevention of brain injuries in car crashes.

This study estimated the frequency and risk of Moderate-to-Maximal traumatic brain injuries sustained by occupants in motor vehicle crashes in the US. National Automotive Sampling System - Crashworthiness Data System crashes that occurred in years 2001-2015 with light vehicles produced 2001 or later were incorporated in the study. Crash type, crash severity, car model year, belt usage and occupant age and sex were controlled for in the analysis. The results showed that Moderate concussions account for 79% of all MAISbrain2+ injuries. Belted occupants were at lower risks than unbelted occupants for most brain injury categories, including concussions. After controlling for the effects of age and crash severity, belted female occupants involved in frontal crashes were estimated to be 1.5 times more likely to sustain a concussion than male occupants in similar conditions. Belted elderly occupants were found to be at 10.5 and 8 times higher risks for sub-dural haemorrhages than non-elderly belted occupants in frontal and side crashes, respectively. Adopted occupant protection strategies appear to be insufficient to achieve significant decreases in risk of both life-threatening brain injuries and concussions for all car occupants. Further effort to develop occupant and injury specific strategies for the prevention of brain injuries are needed. This study suggests that these strategies may consider prioritization of life-threatening brain vasculature injuries, particularly in elderly occupants, and concussion injuries, particularly in female occupants.

Quality of head injury coding from autopsy reports with AIS © 2005 update 2008.

ABSTACT Objective: Coding injuries from autopsy reports of traffic accident victims according to Abbreviated Injury Scale AIS © 2005 update 2008 [1] is quite time consuming. The suspicion arose, that many issues leading to discussion between coder and control reader were based on information required by the AIS that was not documented in the autopsy reports. METHODS: To quantify this suspicion, we introduced an AIS-detail-indicator (AIS-DI). To each injury in the AIS Codebook one letter from A to N was assigned indicating the level of detail. Rules were formulated to receive repeatable assignments. This scheme was applied to a selection of 149 multiply injured traffic fatalities. The frequencies of "not A" codes were calculated for each body region and it was analysed, why the most detailed level A had not been coded. As a first finding, the results of the head region are presented. RESULTS: 747 AIS head injury codes were found in 137 traffic fatalities, and 60% of these injuries were coded with an AIS-DI of level A. There are three different explanations for codes of AIS-DI "not A": Group 1 "Missing information in autopsy report" (5%), Group 2 "Clinical data required by AIS" (20%), and Group 3 "AIS system determined" (15%). Groups 1 and 2 show consequences for the ISS in 25 cases. Other body regions might perform differently. CONCLUSIONS: The AIS-DI can indicate the quality of the underlying data basis and, depending on the aims of different AIS users it can be a helpful tool for quality checks.