Abdominal and Pelvic Injuries Caused by Road Traffic Accidents: Characteristics and Outcomes in a French Cohort of 2,009 Casualties

The effect of hepatic steatosis and fibrosis on liver weight and dimensions

The liver is the most commonly injured abdominal organ, accounting for around half of abdominal organ injuries. The emergence of liver injury is determined by the injury mechanism, force, and tissue vulnerability. The vulnerability of the liver depends on the strength of the capsule and parenchyma, as well as the weight and dimensions of the liver. The common hepatic diseases, like steatosis, fibrosis, and cirrhosis, can change the organ weight and dimensions, but their exact correlation is not well known. This study was designed to evaluate the correlation between liver diseases, weight, and dimensions. The liver weight, horizontal, vertical, and antero-posterior length were measured obtained by 213 forensic autopsies. The recorded data were compared with body height, age, and liver histology. Body height positively correlated with liver weight (R² = 0.252), but the correlation was much stronger in the case of livers without structural disease (R² = 0.450). The liver size seems to significantly decrease with age (R² = 0.081), but the effect is mostly due to structural alterations that are proven by histology. The comparison of the liver weight in various histological groups clearly indicated that steatosis increases the liver size, but fibrosis does not (if no steatosis is present at the same time). In general, liver dimensions increase proportionally to the liver weight. However, hepatic steatosis causes disproportional enlargement: it does not have a significant effect on the horizontal dimension and has only a minor effect on the vertical dimension. Steatosis affects disproportionally the dimensions with a strange tendency to expand liver anteroposteriorly.

The effect of steatosis and fibrosis on blunt force vulnerability of the liver

The aim of our study was to examine the possible effect of steatosis and fibrosis on the blunt force vulnerability of human liver tissue. 3.5 × 3.5 × 2-cm-sized liver tissue blocks were removed from 135 cadavers. All specimens underwent microscopical analysis. The tissue samples were put into a test stand, and a metal rod with a square-shaped head was pushed against the capsular surface. The force (Pmax) causing liver rupture was measured and registered with a Mecmesin AFG-500 force gauge. Six groups were formed according to the histological appearance of the liver tissue: intact (group 1), mild steatosis (group 2), moderate steatosis (group 3), severe steatosis (group 4), fibrosis (group 5), and cirrhosis (group 6). The average Pmax value was 34.1 N in intact liver samples (range from 18.1 to 60.8 N, SD ± 8.7), 45.1 N in mild steatosis (range from 24.2 to 79.8 N SD ± 12.6), 55.4 N in moderate steatosis (range from 28.9 to 92.5 N, SD ± 16.0), 57.6 N in severe steatosis (range from 39.8 to 71.5 N, SD ± 11.9), 63.7 N in fibrosis (range from 37.8 to 112.2 N, SD ± 19.5), and 87.1 N in the case of definite cirrhosis (range from 52.7 to 162.7 N, 30.3). The Pmax values were significantly higher in samples with visible structural change than in intact liver sample (p = 0.023, 0.001, 0.009, 0.0001, 0.0001 between group 1 and groups 2 to 6 respectively). Significant difference was found between mild steatosis (group 2) and cirrhosis (group 6) (p = 0.0001), but the difference between mild, moderate, and severe steatosis (groups 2, 3, and 4) was not significant. Our study demonstrated that contrary to what is expected as received wisdom dictates, the diseases of the parenchyma (steatosis and presence of fibrosis) positively correlate with the blunt force resistance of the liver tissue.

Abdominopelvic injuries due to road traffic accidents: Characteristics in a registry of 162,695 victims

OBJECTIVE

Road traffic accidents (RTAs) are the first cause of abdominopelvic injuries (APIs). The objective of this study was to describe the characteristics and severity of APIs due to traffic accidents in a large French trauma registry and to identify risk factors for API.

METHODS

All victims from the French Rhône registry of victims of RTAs were analyzed from 1996 to 2013. This registry contained data that were issued over a 20-year period from 245 medical departments, from prehospital care until re-adaptation, and forensic medicine departments. All APIs, defined as an injury between the diaphragm and the pelvic bone, were extracted and studied.

RESULTS

Among 162,695 victims, 10,165 had an API (6.7%). Accidents frequently involved young men and 2 cars. Mean Injury Severity Score (ISS) was 8.7. Mortality rate was 5.6%. Soft tissue injuries largely predominated (n = 6,388; 54.4% of patients). Overall, 2,322 victims had a pelvic bone injury. Internal abdominal organs were involved in 2,425 patients; the most frequent were the spleen, liver, and kidney. Wearing of the seat belt appeared to be a significant protective factor in API, including serious injuries. A partial analysis over the past 2 years among the most severe patients hospitalized in the intensive care unit indicated that nonoperative management was carried out in two thirds of the wounded. In uni- or multivariate analysis, sex, age, type of user, antagonist, time of occurrence, associated severe lesions, or wearing of the seat belt were statistically associated with the occurrence of API, highlighting a more dangerous user profile.

CONCLUSIONS

Abdominopelvic injuries concern a minority of road traffic injuries, but they are responsible for significant mortality. Large solid organs are the most frequently affected. Women drivers wearing a seat belt and driving in town during the day appear to be more protected against API.

Patterns of injury detected by pan-computed tomography after road traffic accidents: retrospective review from a trauma center in Saudi Arabia

BACKGROUND

Pan-scan (whole-body) computed tomography (CT) has a paramount role in the diagnosis of injuries in road traffic accidents (RTA).

OBJECTIVE

Identify patterns of injuries on pan-CT scans.

DESIGN

Retrospective medical record review.

SETTING

Tertiary care center.

PATIENTS AND METHODS

The records of all RTA patients who presented to the radiology department at King Fahad Military Medical Complex (KFMMC) in Dhahran for the 3-year period from July 2014 to July 2017 and underwent pan-CT were retrospectively reviewed. Drivers and front-seat passengers with complete clinical information on seating, safety and mechanism of injury were selected. Children under 5 years of age, pregnant women and back-seat passengers were excluded. Patterns of injuries were categorized as 'no abnormality detected' (NAD), isolated or combined head, face and neck (H), isolated or combined chest, abdomen and pelvis (C) or both regions of the body (B).

MAIN OUTCOME MEASURES

Injury patterns on pan-CT scans.

SAMPLE SIZE

305 RESULTS: Most patients were males (n=287, 94.1%). The median age was 26 years for males (IQR, 22-33 years) and 30 years for females (IQR, 28-39). More than two-thirds were drivers (all males); the remainder were front-seat passengers. Young males were most often involved. The most common type of accident was a roll-over. Of those who sustained injuries, 273 (89.5%) were not wearing a seat belt (unrestrained). The patterns of injuries were NAD (87, 28%), H (27, 9%), C (93, 30.5%), B (98, 32%).

CONCLUSION

When abnormalities were detected, most high-speed vehicular injuries affected the torso. Unrestrained young male drivers are most often involved in RTAs in Saudi Arabia.

LIMITATIONS

Retrospective study with a small sample size. Types and severity of injuries on pan-CT were not documented.

CONFLICT OF INTEREST

None.

An anatomic and morphometric analysis of splenic variability using 3D reconstruction and spatial orientation from computed tomography

INTRODUCTION

In terms of frequency, the spleen is the first organ affected in abdominal trauma, resulting even today in a high rate of mortality (10%). Nevertheless, very few studies have investigated splenic quantitative morphometry as to shape and spatial orientation. Therefore, we analysed healthy spleen variability in order to integrate it in its environment and to correlate its morphometric parameters to anthropometric characteristics.

METHODS

Ninety abdominopelvic CT-scans performed on patients over 16 years with no splenic pathology were retrospectively selected among a Mediterranean population. Three age groups ([16-30], [30-60] and [over 60 years]), equally distributed among genders, were created. Parameters, such as volume, characteristic checkpoints, orientation, and morphology, were measured on the spleen, the 11th thoracic vertebra and the 10th ribs in three-dimensional reconstructions. Anthropometric parameters were characterised by waist circumference, costo-xiphoid angle, abdominal height and chest depth.

RESULTS

Observed variations in splenic morphology were divided into three groups: cupped (66.7%), coiled (17.8%), and flat (15.5%). Splenic morphometry tends to be abdominal-shaped (54.5%) or dorsal-shaped (45.5%). The mean of the angle between the main axis of the spleen and the CT-scan horizontal axis was 40±14°. Correlations were highlighted between volume and gender (p<0.05), splenic morphology and liver morphometry (p<0.05) as well as between orientation of hilar surface and splenic morphometry (p<0.01). Moreover, the spleen is more horizontal in women (p<0.05), in the elderly (p<0.05) and in the obese (p<0.01).

CONCLUSION

This study defines three groups based on shape and highlights correlations between parameters describing healthy splenic variability and its anthropometric characteristics, which are of great importance for numerical modelling in splenic studies.

Statistical modeling of human liver incorporating the variations in shape, size, and material properties

The liver is one of the most frequently injured abdominal organs during motor vehicle crashes. Realistic numerical assessments of liver injury risk for the entire occupant population require incorporating inter-subject variations into numerical models. The main objective of this study was to quantify the shape variations of human liver in a seated posture and the statistical distributions of its material properties. Statistical shape analysis was applied to construct shape models of the livers of 15 adult human subjects, recorded in a typical seated (occupant) posture. The principal component analysis was then utilized to obtain the modes of variation, the mean model, and 95% statistical boundary shape models. In addition, a total of 52 tensile tests were performed on the parenchyma of three fresh human livers at four loading rates (0.01, 0.1, 1, and 10 s^-1) to characterize the rate-dependent and failure properties of the human liver. A FE-based optimization approach was employed to identify the material parameters of an Ogden material model for each specimen. The mean material parameters were then determined for each loading rate from the characteristic averages of the stress-strain curves, and a stochastic optimization approach was utilized to determine the standard deviations of the material parameters. Results showed that the first five modes of the human liver shape models account for more than 60% of the overall anatomical variations. The distributions of the material parameters combined with the mean and statistical boundary shape models could be used to develop probabilistic finite element (FE) models, which may help to better understand the variability in biomechanical responses and injuries to the abdominal organs under impact loading.

Effect of storage methods on indentation-based material properties of abdominal organs

To investigate the possible changes in material properties of cadaveric abdominal organs due to the preservation methods, the indentation data obtained from porcine abdominal organs (kidney, liver, and spleen) preserved by cooling and freezing are analyzed statistically in this study. Indentation tests were first conducted on fresh specimens. One half of the specimens of each organ were then frozen (preserved at −12 °C), and the other half of the specimens were cooled (preserved at 4 °C). All preserved specimens were retested after 20 days. Force and displacement data recorded during indentation were analyzed using a quasi-linear viscoelastic model. The results show that both cooling and freezing storage increased the kidney stiffness. In contrast, both storage methods decreased the stiffness of the spleen specimens. While cooling increased the liver stiffness, no significant changes of the instantaneous elastic response were observed in the liver specimens preserved by freezing. The liver and spleen’s reduced relaxation responses and the liver’s instantaneous elastic response were significantly different when comparing between cooling and freezing effects after 20 days of preservation. This study showed that both cooling and freezing storage methods significantly changed the material properties of abdominal organs, especially the instantaneous elastic response. More research is needed in investigating the effect of preservation on failure properties and mechanical properties under large deformation.