Biomechanical analysis of traumatic mesenteric avulsion

Isolated superior mesenteric artery rupture caused by abdominal trauma

The superior mesenteric artery (SMA) is one of the visceral branches of the abdominal aorta. It has multiple branches to supply blood and nutrition to the intestinal segment, and these form an anastomosis with each other. SMA injuries are usually classified as major visceral artery injuries, and have an incidence of <1%. The clinical manifestations of patients with SMA injuries include intra-abdominal bleeding and peritoneal irritation. The compromised blood supply can lead to intestinal ischemia and perforation. These injuries are often not diagnosed in time and have significant mortality rates of 25%‍-‍68% due to the lack of specific features (Maithel et al., 2020). Not only that, but patients with less severe trauma or no visible damage on initial examination may still have clinically significant intra-abdominal injuries (Nishijima et al., 2012). Emergency departments often encounter multiple cases that require urgent diagnosis and treatment (Li et al., 2021; Zhang et al., 2021; Zhou et al., 2021), and therefore, it is imperative to diagnose and manage these rare injuries expeditiously.

Laparoscopic treatment of mesenteric avulsion and intestinal perforation after blunt abdominal trauma: A report of a case

INTRODUCTION

Intestinal injuries are quite involved in non-penetrating abdominal trauma after liver and spleen. The incidence of small bowel injury after blunt abdominal trauma has increased nowadays, since high-energy transfer impacts producing large abdominal wall displacements are more frequent, such as car crash.

CASE REPORT

We report a case of a 49-year-old Caucasian woman, victim of a violent car crash, resulting in multiple small bowel perforations and mesenteric avulsion. Since the patient was hemodynamically stable, a laparoscopic approach was carried on.

DISCUSSION

Blunt abdominal trauma are responsible of 6-14.9% of all traumatic injuries (Galia et al., 2017). The frequency of small bowel lesions ranges from 5% to 15%, while small bowel mesenteric injuries are approximately found in 5% of patients after blunt abdominal trauma. There are different biomechanical reasons explaining how a blunt trauma can cause damages to small bowel and its mesentery. Clinical diagnosis of small bowel perforation after blunt abdominal trauma is often challenging for non-specific objective clinical signs and because peritoneal irritation symptoms are present only in collaborative patients.

CONCLUSION

Laparoscopy is a safe and feasible tool in selected patients with blunt abdominal trauma, both for diagnosis and treatment. The prerequisites for applying mini invasive approach are both the hemodynamic stability of the patient and an adequate surgical expertise in advanced laparoscopy.

Lethal mesenteric perforation by osteophytes after blunt abdominal trauma

A 50 year-old homeless man was found dead the day after he had sustained blunt abdominal trauma during a physical assault. Autopsy revealed no apparent injury to the abdominal wall, but showed a massive hemoperitoneum resulting from a large (8 cm) tear of the mesenteric root. It also revealed prominent and diffuse spinal osteophytes predominating in the lumbar region, where they were fused and formed a large anterior ossified excrescence. The diagnosis of diffuse idiopathic skeletal hyperostosis was established in the presence of continuous ossification along the anterior aspect of five contiguous vertebral bodies, without any additional features of degenerative disease on imaging. Death was attributed to intra-abdominal hemorrhage due to mesenteric perforation caused by blunt abdominal trauma in the context of diffuse idiopathic skeletal hyperostosis. This pre-existing condition was considered an aggravating factor, as anterior lumbar osteophytosis had made the mesentery more vulnerable to blunt trauma by reducing both the space separating the abdominal wall from the spine and the surface of interaction between the spine and the mesentery. Only a few cases of osteophyte-related visceral injury have been described in the literature. To our knowledge, this is the first reported case of lethal abdominal injury caused by osteophytes after blunt trauma.

Difference in severity and distribution of bodily injuries following collision between drivers of K-cars and standard vehicles

BACKGROUND

Although K-cars, small four-wheeled vehicles with an engine capacity of <660 cc, have been used almost exclusively in Japan, they have recently become increasingly popular in other countries. Therefore, reporting the characteristics of bodily injuries sustained by K-car drivers after road traffic accidents (RTAs) may be important not only for health professionals but also for car manufacturers.

METHODS

A single-center, retrospective observational study was conducted using prospectively acquired data. Between January 2010 and December 2017, 494 restrained drivers (331 men/163 women with a mean age of 45.1 years) whose vehicles had been severely damaged in RTAs underwent whole-body computed tomography prospectively. They were subsequently dichotomized into 221 K-car drivers and 273 standard vehicle drivers and compared for severity and distribution of bodily injuries.

RESULTS

K-car drivers tended to be older and were significantly more likely to be female than standard vehicle drivers. The frequency of subjects with severe bodily injuries significantly higher among K-car drivers than among standard vehicle drivers (21.7% vs. 14.3%; p = 0.04), and the frequency of bowel/mesentery injuries tended to be higher in the former (9.0% vs. 4.4%; p = 0.06). However, the frequency of abdominal solid viscus injuries did not differ significantly between the two groups. Multivariable regression analysis showed that age [odds ratio (OR): 1.022; 95% confidence interval (CI): 0.998-1.047; p = 0.07] and K-cars (OR: 3.708; 95% CI: 0.984-6.236; p =  0.05) tended to be associated with bowel/mesentery injuries in restrained drivers. The frequency of pelvic/hip fractures also tended to be higher in K-car drivers than in standard vehicle drivers (5.9% vs. 2.6%; p =  0.10). By contrast, the severity and frequency of the upper torso injuries were similar between the two groups.

CONCLUSIONS

Compared to standard vehicle drivers, K-car drivers seem to experience more severe bodily injuries after severe RTAs. Despite there being no answer for the increased frequency of only hollow viscus injuries but not solid viscus injuries among restrained K-car drivers, advanced age may, at least in part, be responsible. Given the limitations inherent to this study's single-center, retrospective design, multi-center prospective studies are warranted to verify our findings.

Development and validation of an optimized finite element model of the human orbit

INTRODUCTION

The authors' main purpose was to develop a detailed finite element model (FEM) of the human orbit and to validate it by analyzing its behavior under the stress of blunt traumas.

MATERIALS AND METHODS

A pre-existing 3D FEM of a human head was modified and used in this study. Modifications took into account preliminary research carried out on PubMed database. Data from a CT scan of the head were computed with Mimics^® software to re-create the skull geometry. The mesh production, the model's properties and the simulations of blunt orbital traumas were conducted on Hyperworks^® software.

RESULTS

The resulting 3D FEM was composed of 640 000 elements and was used to perform blunt trauma simulations on an intact orbit. A total of 27 tests were simulated. Fifteen tests were realized with a metallic cylinder impactor; 12 tests simulated a hit by a closed fist. In all the tests conducted (27/27), the orbital floor was fractured. Fracture patterns were similar to those found in real clinical situations according to the buckling and hydraulic theories of orbital floor fractures.

DISCUSSION

The similitude between the fracture patterns produced on the model and those observed in vivo allows for a validation of the model. This model constitutes, at the authors knowledge, the most sophisticated one ever developed.

Dynamic biomechanical characterization of colon tissue according to anatomical factors

INTRODUCTION

The aim of this study was to determine the mechanical response of colonic specimens retrieved from the entire human colon and placed under dynamic solicitation until the tissue ruptured.

MATERIAL AND METHODS

Specimens were taken from 20 refrigerated cadavers from different locations of the colonic frame (ascending, transverse, descending and sigmoid colon) in two different directions (longitudinal and circumferential), with or without muscle strips (taenia coli). A total of 120 specimens were subjected to tensile tests, after preconditioning, at the speed of 1m/s.

RESULTS

High-speed video analysis showed a bilayer injury process with an initial rupture of the serosa / external muscular layer followed by a second rupture of the inner layer consisting of the internal muscle / submucosa / mucosa. The mechanical response was biphasic, with a first point of initial damage followed by a complete rupture. The levels of stress and strain at the failure site were statistically greater in terms of circumferential stress (respectively 69±22% and 1.02±0.50MPa) than for longitudinal stress (respectively 55±32% and 0.70±0.34MPa). The difference between longitudinal and circumferential stress was not statistically significant (3.17±2.05MPa for longitudinal stress and 3.15±1.73MPa for circumferential stress). The location on colic frame significantly modified the mechanical response both longitudinally and circumferentially, whereas longitudinal taenia coli showed no mechanical influence.

CONCLUSION

The mechanical response of the colon specimen under dynamic uniaxial solicitation showed a bilayer and biphasic injury process depending on the direction of solicitation and colic localization. Furthermore these results could be integrated into a numeric model reproducing abdominal trauma to better understand and prevent intestinal injuries.

Hollow viscus injury due to blunt trauma: A review

Blunt abdominal trauma results in injury to the bowel and mesenteries in 3-5% of cases. The injuries are polymorphic including hematoma, seromuscular tear, perforation, and ischemia. They preferentially involve the small bowel and may result in bleeding and/or peritonitis. An urgent laparotomy is necessary if there is evidence of active bleeding or peritonitis at the initial examination, but these situations are uncommon. The main diagnostic challenge is to promptly and correctly identify lesions that require surgical repair. Diagnostic delay exceeding eight hours before surgical repair is associated with increased morbidity and probably with mortality. Because of this risk, the traditional therapeutic approach has been to operate on all patients with suspected bowel or mesenteric injury. However, this approach leads to a high rate of non-therapeutic laparotomy. A new approach of non-operative management (NOM) may be applicable to hemodynamically stable patients with no signs of perforation or peritonitis, and is being increasingly employed. This attitude has been described in several recent studies, and can be applied to nearly 40% of patients. However, there is no consensual agreement on which criteria or combination of clinical and radiological signs can insure the safety of NOM. When NOM is decided upon at the outset, very close monitoring is mandatory with repeated clinical examinations and interval computerized tomography (CT). Larger multicenter studies are needed to better define the selection criteria and modalities for NOM.