Purpose
Analysis of influence of anthropomorphometry, splenic variability and crash’s circumstances on the severity of splenic injury.
Methods
Seventy-seven patients with blunt splenic trauma had a tomodensitometry at time of admission. Localisation, type, and lesion’s severity (AAST classification), were determined. Severe splenic lesion was defined by: Grade 4 or 5, lesion of entire parenchyma, or fracture. Three-dimensional splenic segmentation allowed calculation of volume, orientation (colatitude and azimuth), morphometry, morphology and span of hilar vessels. Anthropometric parameters were: Age, gender, BMI, and morphotype. Relationships between spleen, stomach, liver and 10th left rib were detailed.
Results
In univariate analysis, splenic parameters for a severer lesion were: Orientation of hilar side turned towards vertebral column (azimuth, p=0.05), spread conformation of hilar vessels (p=0.10), and high splenic volume (p=0.06). The younger the patient, the more severe was the splenic lesion (p=0.07). A full stomach and a left liver overflowing in the left hypochondrium, were associated with low gravity splenic lesion, (p=0.02 and p=0.03). In multivariable analysis, injured patients whose hilar area was vertically oriented, were more at risk of severe splenic lesion (OR=0.92, 95% CI (0.85-0.99), p=0.02). An abdominal-shaped liver was associated with low gravity splenic lesion (OR= 0.13, 95% CI (0.02-0.93), p=0.04).
Conclusions
Topographic and morphologic variability of the spleen condition its vulnerability in trauma cases. Using this analysis and the biomechanical behaviour of splenic tissue will allow for the creation of a splenic numerical model, and its integration in the virtual human scientific application of modern traumatology.
Demographic characteristics |
n= 77 |
Mean age (years) |
32 ±15.2 |
Gender M/F |
59 (76.6%) /18 (23.4%) |
Individual Anthropometry |
|
General morphotype |
|
Stocky |
28 (36.4%) |
Slender |
49 (63.6%) |
Abdominal perimeter (mm) |
838.7 ±121.4 |
BMI (Kg/Cm2) |
|
Normal |
58 (75.3%) |
Overweight |
9 (11.7%) |
Obesity |
5 (6.5%) |
Severe obesity |
2 (2.6%) |
Malnutrition |
3 (3.9%) |
Accident circumstances |
|
Pedestrian |
3 (3.9%) |
Two-Wheelers |
34 (44.2%) |
Truck and light vehicles |
40 (51.9%) |
Position during the impact |
|
Driver |
47 (61%) |
Front passenger |
4 (5.2%) |
Passenger back left / back right / back middle |
4(5.2%)/1(1.3%)/2(2.6%) |
Direction of the impact |
|
Lateral right / Lateral left |
3 (3.9%)/ 8 (10.4%) |
Frontal |
38 (49.4%) |
Back |
2 (2.6%) |
Gravity of the accident |
|
Ejection outside the vehicle |
11 (14.3) |
Extrication outside the vehicle more than 20 minutes |
16 (20.8%) |
Rolled over |
3 (3.9%) |
System of protection |
|
None |
13 (16.9%) |
Seat belt |
20 (26%) |
Helmet |
25 (32.5%) |
Airbag |
19 (24.6%) |
Morphometric analysis of the spleen and neighbouring organs |
|
Splenic characteristics |
|
Splenic volume (cc) |
233.2±119.5 |
Splenic morphometry |
|
Abdominal-shape |
41 (53.3%) |
Dorsal-shape |
36 (46.7%) |
Angle between horizontal and biggest axis of the spleen (°) |
50.5±12.6 |
Splenic morphology |
|
Flat |
13(16.9%) |
Cupped |
57(74%) |
Coiled |
7(9.1%) |
Percentage of splenic volume under the 10th left rib |
|
0% |
5 (6.5%) |
Less than 20% |
18 (23.4%) |
20 - 50% |
30 (38.9%) |
More than 50% |
24 (31.2%) |
Orientation in space |
|
Colatitude (°) |
80±20.7 |
Azimuth (°) |
118.6±29 |
Conformation of hilar vessels |
|
Spread |
37 (48.1%) |
Grouped |
40 (51.9%) |
Neighbouring organs |
|
Occupation of the left hypochondrium by the left liver |
|
01/4 |
26 (33.8%) |
01/2 |
28 (36.4%) |
03/4 |
15 (19.5%) |
04/4 |
8 (10.3%) |
Hepatic morphometry |
|
Abdominal-shape |
47 (61%) |
Dorsal-shape |
30 (39%) |
Fracture of the left 10th rib |
|
Stomach |
|
Full |
33 (42.9%) |
Empty |
25 (32.5%) |
Analysis of the splenic lesion |
|
Splenic lesion: AAST Grade: |
|
1 |
31 (40.3%) |
2 |
24 (31.2%) |
3 |
14 (18.2%) |
4 |
8 (10.3%) |
5* |
0 (0%) |
Localisation of the lesion |
|
Hilar |
35 (45.5%) |
Lateral |
15 (19.5%) |
Lateral and hilar |
23 (29.8%) |
Splenic tip |
4 (5.2%) |
Type of lesion |
|
Contusion |
2 (2.6%) |
Intra-parenchymatous hematoma |
12 (15.5%) |
Sub-capsular hematoma |
10 (13%) |
Laceration |
27 (35.1%) |
Fracture |
23 (29.9%) |
Burst |
3 (3.9%) |
Table 1: Descriptive parameters of the study population (Quantitative variables are in mean±299 standard deviation).
* No grade 5 in the 77 splenic traumas. 18 / 95 splenic trauma had a splenectomy for haemostasis before going through tomodensitometry.
Parameters |
Low severity splenic |
High severity splenic |
p |
Lesion |
Lesion |
||
Mean age (years) |
40±16.3 |
24±6.8 |
0.07 |
Gender M/F |
52 (75.3%)/17 (24.7%) |
7 (87.5%)/1 (12.5%) |
0.44 |
Individual Anthropometry |
|||
General morphotype |
|
|
0.45 |
Stocky |
25 (36.2%) |
3 (37.5%) |
|
Slender |
44 (63.8%) |
5 (62.5%) |
|
BMI (Kg/Cm2) |
|
|
0.57 |
Normal |
58 (84%) |
0 (0%) |
|
Overweight |
7 (10.1%) |
2 (25%) |
|
Obesity |
4 (5.7%) |
1 (12.5%) |
|
Severe obesity |
2 (2.9%) |
0 (0%) |
|
Malnutrition |
3 (4.3%) |
0 (0%) |
|
Accident circumstances |
|||
Type of transport |
|
|
0.2 |
Pedestrian |
2 (2.9%) |
1(12.5%) |
|
Two-Wheelers |
31 (44.9%) |
3 (37.5%) |
|
Truck and light vehicles |
36 (52.2%) |
4 (50%) |
|
Position during the impact |
|
|
0.39 |
Driver |
40 (60.6%) |
7 (87.5%) |
|
Front passenger |
3(4.3%) |
1 (12.5%) |
|
Direction of the impact |
|
|
0.44 |
Lateral right |
2 (2.9%) |
5 (62.5%) |
|
Frontal |
33 (47.8%) |
2 (25%) |
|
Unknown |
24 (34.8%) |
1 (12,5%) |
|
Gravity of the accident |
|
|
0.07 |
Extrication outside the vehicle more than 20 |
|
|
|
minutes |
13 (18.8%) |
3 (37,5%) |
|
Unknown |
39 (56.5%) |
5 (62.5%) |
|
System of protection |
|
|
0.49 |
None |
9 (13%) |
4 (50%) |
|
Seat belt |
19 (27.5%) |
1 (12.5%) |
|
Helmet |
23 (33.3%) |
2 (25%) |
|
Airbag |
18 (26%) |
1 (12.5%) |
|
Splenic characteristics |
|||
Mean Splenic volume (cc): |
233±119.7 |
233±145.1 |
0.06 |
Splenic morphometry: |
|
|
0.85 |
Abdominal-shape |
37(53.6%) |
4 (50%) |
|
Dorsal-shape |
32 (46.4%) |
4 (50%) |
|
Splenic morphology: |
|
|
0.2 |
Flat |
10 (14.5%) |
3 (37.5%) |
|
Cupped |
52 (75.4%) |
5 (62.5%) |
|
Coiled |
7 (10.1%) |
0 (0%) |
|
Percentage of splenic volume under the 10th left rib |
|||
0% |
2 (2.9%) |
3 (37.5%) |
|
Less than 20% |
16 (23.2%) |
2 (25%) |
|
20-50% |
29 (42%) |
1 (12.5%) |
|
More than 50% |
22 (31.9%) |
2 (25%) |
|
Orientation in space (Mean) |
|||
Colatitude (°) |
93.2±20.4 |
66.8±24.4 |
0.19 |
Azimuth (°) |
123,1±28.8 |
114.1±29.6 |
0.05 |
Conformation of hilar vessels |
|
|
0.11 |
Spread |
32 (46.4%) |
5 (62.5%) |
|
Grouped |
37 (63.6%) |
3 (37.5%) |
|
Neighbouring organs |
|||
Occupation of the left hypochondrium by the left liver |
|
|
0.48 |
1/4 |
22 (31.9%) |
4 (50%) |
|
1/2 |
24(34.8%) |
4 (50%) |
|
3/4 |
15 (21.7%) |
0 (0%) |
|
4/4 |
8 (11.6%) |
0 (0%) |
|
Hepatic morphometry |
|
|
0.03 |
Abdominal-shape |
46 (66.7%) |
1 (12.5%) |
|
Dorsal-shape |
23 (33.3%) |
7 (87.5%) |
|
Fracture of the left 10th rib |
7(10.1%) |
0(0%) |
0.35 |
Stomach |
|
|
0.02 |
Full |
30(43.5%) |
3(37.5%) |
|
Empty |
20(29%) |
5(62.5%) |
|
Almost empty |
19 (27.5%) |
0 (0%) |
|
Table 2: Significant parameters in univariate analysis, associated with a more severe splenic lesion (p<10%).
There were four splenic parameters for more severe lesions: The hilar side was oriented toward the vertebral column (determined by the azimuth measure, p=0.05), a spread conformation of the hilar vessels (p=0.10), a recovery of the spleen by the 10th left rib (p=0.08) and a high splenic volume (p=0.06). Neither the morphometry nor the morphology of the spleen was linked to the severity of the splenic lesion (respectively p=0.85 and p= 0.2) and anthropometric parameters did not seem to influence the seriousness of injury. Obesity did not appear to be an aggravating or protecting argument for splenic trauma (p=0.62). Younger patients suffered severe splenic lesions most frequently (p=0.07) and gender was not a significant factor (p=0.44). As for the circumstances of the accident, none of the situations recorded seemed to influence the severity of the splenic lesion. The use of a seat belt or the airbag setting didn’t seem to aggravate or protect from high splenic trauma (p=0.49). As to the relationship between intra-abdominal organs, a left liver overflowing in the left hypochondrium and covering the upper part of the spleen was associated with a low severity splenic lesion (p=0.03), whereas an empty stomach was associated with more severe splenic lesions (p=0.02).
The splenic organ varies widely between individuals in terms of anatomic characteristics, morphology, geometry, orientation in space and vascularisation [16]. In this study, we have shown that some parameters related to the three-dimensional anatomy of the spleen, such as orientation of the splenic vessels, could be associated with the severity of a splenic injury during a road accident.
Splenic lesions may occur in many different circumstances. Therefore, to gather a relatively homogenous population, this study focused on traffic accidents only, but even with this selection parameter, the injury mechanisms involved can be multiple (direct impact, deceleration) and associated. The results in this study show no evidence of aggravating or mitigating circumstances for the conditions in which the accident occurred in severe splenic trauma; even for seatbelt use, which agrees with some studies [19,20]. However, Holbrook et al., have demonstrated the negative role of the seat belt on the liver [21]. The debate continues since studies have shown that the incidence rate of injury to intraabdominal organs was higher for belted passengers [22].
The analysis of clinical or radiological data does not make it possible to understand the process leading to traumatic injury. However, classifying injuries according to their severity highlights the factors associated with their seriousness, which makes it possible to speculate on the role of each factor in the traumatic process. Orientation of the spleen’s hilar surface is associated to severe lesions in this study, as its position affects the way the neighbouring organs will fit together and around the splenic parenchyma and the hilum. If the hilar side is turned toward the front of the body, the hilar vessels will get more protection from the parenchyma behind them. A full stomach will also protect the spleen from severe splenic trauma, acting like an airbag inside the abdomen. The left liver overflowing into the left hypochondrium will have the same protective effect, and, like the rib cage, gastric and hepatic tissues will absorb the shock waves. The incidence of 10th left rib fracture is not related to a more severe splenic lesion in our study. This result reaffirms the debate associated to the rib cage [23]: Is it a protective hammock or a danger for the parenchyma? in this analysis, the younger patients had the most severe injuries, which suggests anatomical avenues for reflection. As people age, the thoraco-abdominal region changes: morphotype tends to be stocky, costo-xiphoid angle opens, muscle strap loosens, the vertebral column settles down, and this brings about a re-organisation, re orientation of the relationships between intra-abdominal organs. Factoring for different local conditions, might explain that the elderly present less severe splenic lesions. Likewise, our population of young people, essentially male, corresponds to those more exposed to severe injuries, as highlighted by French demographic data [1]. In this study, a status of obesity was not associated with a higher risk of severe splenic lesion. The adipose tissue would protect the splenic parenchyma in a case of direct impact, but cases of existing deceleration in blunt abdominal trauma have not been studied yet. Other studies on trauma in obese patients have reported that complications due to trauma increase morbidity and mortality rates, but not the severity of the original lesion to the internal organs themselves [24-26].
The main limitation of this study is the low number of patients included in the severe splenic lesion group. This bias results from the study’s methodology which requires a spleen CT-scan. Grade 5 hemodynamically unstable patients go directly to the operative room and undergo haemostasis splenectomy, and are therefore impossible to include in this type of analysis.
This work suggests that parameters of intrinsic and extrinsic variability condition the tolerance threshold of the abdominal organs during trauma. These hypotheses require further laboratory study to define the role of each movement and each anatomical structure in terms of shock resistance [10-13]. Such a study could use a numerical 3D model in which the biomechanical properties of each organ are determined by experimental tests [27-30]. This would be of major interest because it allows for wide-scale tests as they are free from the problems inherent in studies using post-mortem human surrogates. Trauma conditions can be infinitely adapted (high or low kinetic trauma, car or bike accident and so forth), as well as the means of prevention (effects of seat belts, airbags, and so forth). This virtual human could then be used to improve prevention, protection devices, but also as a way to aid clinical decision.
Conflict of interest: The authors declare that they have no conflict of interest. For this type of study, formal consent is not required. This article does not contain any studies with animals performed by any of the authors.
The authors wish to thank the Laboratory of Applied Biomechanics of Aix-Marseille University, Marseille, France and Kathleen Beaumont for language and writing assistance.
Citation: PurposeAnalysis of influence of anthropomorphometry, splenic variability and crash’s circumstances on the severity of splenic injury.MethodsSeventy-seven patients with blunt splenic trauma had a tomodensitometry at time of admission. Localisation, type, and lesion’s severity (AAST classification), were determined. Severe splenic lesion was defined by: Grade 4 or 5, lesion of entire parenchyma, or fracture. Three-dimensional splenic segmentation allowed calculation of volume, orientation (colatitude and azimuth), morphometry, morphology and span of hilar vessels. Anthropometric parameters were: Age, gender, BMI, and morphotype. Relationships between spleen, stomach, liver and 10th left rib were detailed.ResultsIn univariate analysis, splenic parameters for a severer lesion were: Orientation of hilar side turned towards vertebral column (azimuth, p=0.05), spread conformation of hilar vessels (p=0.10), and high splenic volume (p=0.06). The younger the patient, the more severe was the splenic lesion (p=0.07). A full stomach and a left liver overflowing in the left hypochondrium, were associated with low gravity splenic lesion, (p=0.02 and p=0.03). In multivariable analysis, injured patients whose hilar area was vertically oriented, were more at risk of severe splenic lesion (OR=0.92, 95% CI (0.85-0.99), p=0.02). An abdominal-shaped liver was associated with low gravity splenic lesion (OR= 0.13, 95% CI (0.02-0.93), p=0.04).ConclusionsTopographic and morphologic variability of the spleen condition its vulnerability in trauma cases. Using this analysis and the biomechanical behaviour of splenic tissue will allow for the creation of a splenic numerical model, and its integration in the virtual human scientific application of modern traumatology.
Copyright: © 2018 Anne-Sophie Studer, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.