Method for elimination of consequences of simulated mine-splinter-directed injury to soft tissues and pelvic organs with pelvic eventration

Abstract

FIELD: military field surgery; traumatology.SUBSTANCE: shockwave trauma and damage from projectiles are inflicted on the previously shaved surface of the animal's body. To simulate a rupture of the uterine wall in females, separating it from the ligaments and the Denon-Villiers aponeurosis, which separates the vagina from the rectum, trauma is inflicted with an M67 RS airsoft grenade, firing projectiles in the form of 2 mm diameter balls containing a powder charge consisting of magnesium powder and potassium perchlorate, from a distance of 50 cm. The animal is placed in a container, lying horizontally on its back with its hind legs spread and fixed. The area of the perineum subject to injury is located at the level of the dispersion and ricochet of the striking elements, and the airsoft grenade is oriented along the explosion vector towards the perineum. After modeling, a macroscopic assessment of the lesion and dissection of the soft tissues are performed. The section plane is located perpendicular to the skin surface and passes through the center of the injury area. The defect of the muscular-fascial layer is eliminated, the damaging elements are removed, and the rupture of the ligamentous apparatus with pelvic eventration is eliminated by installing a transplant. On the 5th and 10th days of the experiment, blood is collected, the number of band neutrophils, ESR and regeneration index are determined. To assess the engraftment of the transplant, 10 days after its installation, material is collected for morphological and biomechanical studies.EFFECT: method, being practical and simple to implement, does not require implementation in specially equipped rooms or equipped training grounds, allows for the elimination of the consequences of simulated mine-fragment-directed trauma to soft tissues and pelvic organs with pelvic eventration, and is therefore available to research groups subject to safety precautions.1 cl, 5 dwg, 1 ex

Description

[0001] Technical field

[0002] The invention relates to the field of medicine, namely to experimental medicine, military field surgery and traumatology, and can be used to treat injuries corresponding to mine-fragmentation-directed trauma (with the following traumatic factors: shock wave and damage by damaging fragments) of soft tissues and pelvic organs in female rats.

[0003] Technology Level

[0004] A prior art method for closing a pelvic floor defect after extralevator abdominoperineal rectal extirpation using the Cardioplant xenopericardial plate (see patent RU 2636417, IPC A61B17 / 00, published November 23, 2017) is known. This method involves restoring the anatomical integrity of the pelvic diaphragm using a biological-based graft. After suturing the muscles and anococcygeal ligament, the plate is secured with U-shaped sutures. Prior to this, the smooth side of the plate is treated with an anti-adhesion gel. The fibrous side of the plate is positioned against the soft tissues of the perineum. The plate is adjusted to the size of the defect, ensuring moderate tension without the formation of folds. The excess plate is removed and secured at the edges with continuous sutures using non-absorbable thread. The ischiorectal tissue and perineal skin are then sutured.This method restores the integrity of the pelvic diaphragm and reduces the risk of postoperative complications by accelerating the tissue healing process.

[0005] However, this method is complex and labor-intensive. There are several disadvantages to using prolene mesh: firstly, the presence of a foreign body that can come into contact with small intestinal loops, requiring measures to isolate the intestine; secondly, this method is limited in its use in cases of extensive pelvic floor defects, when it is impossible to cover the prolene mesh externally on the perineum with subcutaneous fat and skin; thirdly, there is a risk of graft rejection and possible allergic reactions when using biological materials.

[0006] A known method for simulating an explosive injury to soft tissues of a limb with a fracture of the femur (patent RU 2748384, IPC A61B5 / 00, published 05 / 25 / 2021), includes inflicting injury on the previously trimmed surface of the femur of a small laboratory animal - a rat - under anesthesia. The injury is caused by organizing an explosion by detonating an explosive charge, which is a household pyrotechnic product - an ordinary Corsar-2 scratching firecracker, which is installed in the rat's thigh in close proximity to the bone - at a distance of 0.5-0.8 cm from it, in a channel 2.0-2.5 cm long, formed in the area of ​​the semitendinosus, semimembranosus and biceps femoris muscles, through a linear incision of the skin 0.8-1.0 cm long, made in the middle third of the lateral surface of the rat's thigh parallel to the long axis of the femur, for which the skin is spread apart and the thigh muscles are stratified in a blunt manner with a clamp, minimally damaging the tissue.The Korsar-2 firecracker is positioned so that its fuse protrudes 2 cm above the skin surface, while the remaining portion is positioned within the formed channel and partially protrudes 0.3-1.0 cm from the counter-aperture on the opposite thigh. Rats weighing 320 ± 30 g are used to simulate isolated blast injury to soft tissue of the limb with a femur fracture.

[0007] However, this method requires several surgical interventions and selection of explosive elements, which increases the simulation time.

[0008] A method for analyzing the results of surgical care for wounded and injured patients with eventration of abdominal internal organs is known (https: / / vmeda.mil.ru / upload / site56 / document_file / Tekst_dissertacii(247).pdf). The developed experimental biological model of eventration in small and large animals allows for a reliably reconstructed picture of the pathological condition and a set of comparative clinical, laboratory, microbiological, morphological, and microcirculatory studies aimed at assessing the safety and effectiveness of standard medical devices and prototype dressings for the protection and moisturizing of eventrated abdominal organs.Testing of laboratory samples of medical devices for the protection and moisturizing of eventrated hollow abdominal organs on small animals (rats) showed that the use of an aseptic abdominal dressing made of non-woven spunbond material and impregnated with vinylin + silicone allows to reduce the frequency of infection of the abdominal cavity from 80.0 to 28.6%, reduce the frequency of development of the adhesion process from 55 to 25%, prevent the development of peritonitis and fatal outcomes, whereas in the control group in 53% of cases peritonitis developed and 20% mortality was noted.

[0009] However, this aseptic dressing only helps to reduce the frequency of infection and, as a consequence, complications, but does not stimulate the processes of reparation of damaged anatomical structures.

[0010] A known method for simulating explosive trauma to soft tissues of a limb (see patent RU 2741238, IPC G09B 23 / 28, published 01 / 22 / 2021) involves inflicting trauma on the pre-shaved surface of the femur of a small anesthetized laboratory animal by causing an explosion using a household pyrotechnic device—a Korsar-2 firecracker—as an explosive charge. This device is inserted into the rat's femur in a 2.8-3.0 cm long channel formed in the area of ​​the semitendinosus, semimembranosus, and biceps femoris muscles, parallel to the long axis of the femur. The firecracker is installed no closer than 1.0-1.3 cm from the femur and in such a way that its part from the fuse site protrudes 2 cm above the surface of the skin, and the remaining part is located in the formed channel and partially, namely 0.3-1.0 cm, protrudes from the counter-aperture on the opposite surface of the thigh.

[0011] However, this method has low reproducibility due to the use of uncalibrated household pyrotechnics, which leads to variability in the explosion force and distorted results. The technical difficulty of accurately placing the firecracker within a narrow range of distances on small animals increases the risk of bone or vascular damage, and the protruding portion of the charge above the skin creates uncontrolled injury factors that do not correspond to clinical reality, making the data incomparable and reducing the scientific value of the method.

[0012] Also known is a method for eliminating the consequences of a simulated mine-explosive injury to soft tissues and pelvic organs with pelvic eventration (see patent RU 2846154, IPC A61B 17 / 00, A61F 2 / 04, G09B 23 / 28, published 01.09.2025), according to which trauma is inflicted by a shock wave, thermal damage and damage by damaging elements on the previously trimmed surface of the animal's body. To simulate a rupture of the uterine walls in female animals with separation from the ligaments and the Denon-Villiers aponeurosis, which limits the vagina from the rectum, the injury is inflicted with a spring-type trigger with threaded cartridges, having a sleeve with a primer cap, a powder charge consisting of powdered magnesium and potassium perchlorate and a signal star, weighing 0.009 g, with a charge burning time of 3-5 seconds, from a distance of + / - 5 cm.The animal is placed in a horizontal supine position with its hind legs spread and immobilized, and the trigger is oriented along the blast vector toward the perineum. A macroscopic assessment of the lesion is then performed, along with a soft tissue dissection, ensuring the plane of the section is perpendicular to the skin surface and passes through the center of the injury site. The defect in the muscular-fascial layer is repaired, the lesions are removed, and the ligamentous apparatus rupture with pelvic eventration is repaired by implantation of a graft. To assess graft engraftment, 10 days after implantation, tissue is collected for morphological and biomechanical studies.

[0013] A known method for simulating the impact of mine-directed fragmentation on soft tissue and pelvic organs in laboratory animals (see patent RU 2841907, IPC G09B 23 / 28, published 06 / 18 / 2025), involves inflicting trauma with a shock wave and damage from striking elements on a previously trimmed surface of the animal's body. To simulate rupture of the uterine walls in female animals, separating it from the ligaments and the Denon-Villiers aponeurosis, which separates the vagina from the rectum, the injury is inflicted with an M67 RS airsoft grenade with striking elements in the form of 2 mm diameter balls containing a powder charge consisting of magnesium powder and potassium perchlorate, from a distance of 50 cm.In this case, the animal is placed in a container, in a horizontal position lying on its back with its hind legs spread and fixed so that the area of ​​the perineum to be injured is at the level of the scattering and ricochet of the damaging elements, and the airsoft grenade is oriented along the explosion vector towards the perineum.

[0014] The above methods are unique and have no shortcomings.

[0015] Disclosure of the essence of the invention

[0016] The technical problem of the claimed invention is the development of a method for eliminating the consequences of a simulated mine-fragmentation-directed injury to soft tissues and pelvic organs with pelvic eventration.

[0017] The technical result consists in ensuring the reproducibility of results and in expanding the functional capabilities by modeling the rupture of the uterine walls in female animals while simplifying the method and reducing the modeling time.

[0018] The technical result is achieved by the fact that in the method for eliminating the consequences of a simulated mine-fragmentation-directed action of trauma to soft tissues and pelvic organs with pelvic eventration in an anesthetized laboratory animal - a rat, according to the solution, trauma is inflicted by a shock wave and damage by damaging elements on the previously trimmed surface of the animal's body;to simulate a rupture of the uterine walls in female animals with separation from the ligaments and from the Denon-Villiers aponeurosis, which limits the vagina from the rectum, the injury is inflicted with an M67 RS airsoft grenade with damaging elements in the form of balls with a diameter of 2 mm, having a powder charge consisting of magnesium powder and potassium perchlorate, from a distance of 50 cm, while the animal is placed in a container, in a horizontal position lying on its back with its hind legs spread and fixed so that the area of ​​the perineum subject to injury is at the level of the dispersion and ricochet of the damaging elements, and the airsoft grenade is oriented along the explosion vector onto the perineum; after which a macroscopic assessment of the lesion is performed and a dissection of the soft tissues is carried out so that the section plane is perpendicular to the skin surface and passes through the center of the injury area;The defect of the muscular-fascial layer is corrected, the damaging elements are removed, and the rupture of the ligamentous apparatus with pelvic eventration is repaired by installing a transplant; on the 5th and 10th days of the experiment, blood is collected, the number of band neutrophils, ESR and regeneration index are determined; to assess the engraftment of the transplant, 10 days after its installation, material is collected for morphological and biomechanical studies.

[0019] The WallFlex RX biliary stent is used as a graft.

[0020] The graft is installed by laparotomy.

[0021] Brief description of drawings

[0022] The invention is explained by drawings, where Fig. 1 shows Table 1 reflecting the average values ​​of the OAC indicators on the 5th day; Fig. 2 shows Table 2 reflecting the average values ​​of the OAC indicators on the 10th day; Fig. 3 shows Table 3 reflecting the results of biomechanical tests of experimental samples; Fig. 4 shows the morphological picture of the samples of the 1st group; Fig. 5 shows the morphological picture of the samples of the 2nd group.

[0023] The positions on the figures indicate:

[0024] 1. the appearance of immature collagen with distinct capillarization processes,

[0025] 2. muscle fiber atrophy,

[0026] 3. leukocyte infiltration.

[0027] Implementation of the invention

[0028] The method is as follows.

[0029] The studies were conducted on 20 female laboratory rats of the Standard breed weighing 200±50 g. All manipulations and keeping of animals were regulated by the local ethics committee of the Reaviz Medical University (protocol No. 10, 01.06.2025). The conditions of keeping in the vivarium of laboratory animals are regulated by RD-APK 3.10.07.02-09 "Methodological recommendations for keeping laboratory animals in vivariums of research institutes and educational institutions", the order of the Ministry of Health of the Russian Federation dated 01.04.2016 No. 199n "On approval of the rules of good laboratory practice", GOST 33216-2014 "Guidelines for the care and maintenance of laboratory animals. Rules for the maintenance and care of laboratory rodents and rabbits" (updated on 01.01.2021).

[0030] The mine-fragmentation-directed-action trauma (MFD) was simulated using the M67 RS airsoft grenade (SG), which fires 2 mm diameter plastic balls, which act as fragmentation projectiles, contained inside the SG body. The nominal explosive power is up to 0.5 grams of propellant powder. The SG body is made of plastic. The grenade diameter is 6.35 cm, the length along the fuse is 9.2-9.25 cm, and the weight is approximately 115 (±5-10) grams. The radius of destruction by grenade fragments is 15 meters, the radius of possible destruction is 25 meters. Manufactured by Straykom LLC (Moscow, Russia).

[0031] To simulate the MONT, a laboratory animal is placed in a closed space, in a container (a galvanized tank with a closing lid, 51 cm in diameter, with a capacity of 100 l), lying on its back with its hind legs spread and fixed. The legs are fixed so that the perineal area subject to injury is at the level of the scattering and ricochet of the shrapnel, which are 2 mm diameter plastic balls that act as fragmentation projectiles contained within the SG body at a distance of ±50 cm. The trigger is oriented along the perineal vector. To activate the device, the SG is secured to the inside of the tank. The tabs of the trigger clip are unscrewed, and a cord is attached to it to extract the trigger clip and trigger the detonation portion of the SG, which consists of magnesium powder and potassium perchlorate.From a safe location, 2 m away from the galvanized tank, they pulled the cord to remove the safety clip of the device, thereby releasing the trigger lever, which activated the fuse located in the housing.

[0032] After the detonation, a macroscopic assessment of the injury was performed by examining the external surface of the perineal area. The edges of multiple small wounds were uneven, making it impossible to align the wound edges (a "minus tissue" defect according to M.I. Raisky). After an external examination of the lesion site, the soft tissue was dissected so that the cutting plane was perpendicular to the skin surface and passed through the center of the injury site. During tissue dissection, it was determined that multiple entry wounds continued into a blind wound channel approximately 1 / 3 of the thickness of the musculofascial layer. The musculofascial layer defect was stellate in shape and corresponded to the size of the skin defect.In numerous wound channels, damaging elements formed by the scattering of damaging elements of an explosive device and a section of the myometrium with a shrapnel-torn defect of the uterine wall and its separation from the ligaments and from the Denon-Villiers aponeurosis, which separates the vagina from the rectum, were found.

[0033] Thus, the use of SGs that release 2 mm diameter plastic balls as a conventional striking element, which act as fragmentation projectiles contained inside the SG body, with a conventional power of up to 0.5 grams of gunpowder, with a radius of destruction by grenade fragments of 15 meters, makes it possible to receive multiple small-fragmentation wounds formed as a result of the detonation of a powder charge consisting of magnesium powder and potassium perchlorate of the detonation part of the device, the scattering of striking elements, and the ricochet of some of the striking elements against the walls of a galvanized tank, which in this case are traumatic agents.

[0034] Further morphological assessment revealed that the edges of the rupture were jagged, with signs of crushing and hemorrhage. The surrounding tissue showed marked acute inflammation with a large number of band neutrophils. Foci of coagulative necrosis were also observed.

[0035] Furthermore, it was found that the MONTs obtained using this method were identical in the nature and severity of soft tissue damage, including its location, shape, area, and depth, in all experimental animals. Each laboratory animal experienced a complete rupture of the uterine wall, separating it from the ligaments and the Denon-Villiers aponeurosis, which separates the vagina from the rectum.

[0036] Next, the ligamentous apparatus rupture with pelvic eventration is repaired by implanting grafts via laparotomy. An uncovered endoscopic biliary stent (WallFlex RX) was used for this purpose and was implanted in female rats 1 day after MONT. Esfil surgical meshes made of 0.14 mm diameter polypropylene monofilaments were used to comparatively evaluate the use of an endoscopic biliary stent in the wound after MONT. For the comparative evaluation, the animals were divided into 2 groups of 10 rats each. Animals in Group 1 were implanted with an uncovered endoscopic biliary stent, while animals in Group 2 were implanted with Esfil surgical meshes made of 0.14 mm diameter polypropylene monofilaments. Ten days after graft placement, material was collected for morphological and biomechanical studies.

[0037] During the experiment, laboratory blood tests were conducted on the rats on the 5th and 10th days. On the 5th day, a slight increase in band neutrophils, the regeneration index, and the erythrocyte sedimentation rate (ESR) in the complete blood count was detected in both groups, indicating an inflammatory process (Fig. 1). On the 10th day of the experiment, in Group 1, the band neutrophils, regeneration index, and ESR were within normal values, while in Group 2, a persistent increase in band neutrophils and ESR was observed, while the regeneration index was 0.2, indicating a persistent inflammatory process and suggesting possible complications (Fig. 2).

[0038] Biomechanical properties were assessed using an INSTRON-5944 tensile testing machine. To analyze tensile test data, stress and strain graphs were plotted over time. Stress (a parameter used to compare the tension of tissue structural elements, obtained by multiplying the relative tensile load by the tissue density; MPa), strain (with the maximum load value (N), and Young's modulus (modulus of elasticity) (Pa) were analyzed at the moment of biomechanical behavior phase transition and at the moment of maximum strain preceding flap rupture.

[0039] The digital data obtained from the INSTRON-5944 tensile testing machine were processed using variation analysis. Quantitative data in the study groups were presented as the arithmetic mean (M) and standard deviation (SD; σ). The confidence coefficient was defined as the marginal sampling error ∆Xср., calculated by the formula ∆Xср.=tμср., i.e., the marginal sampling error is equal to t-fold the number of average sampling errors. Differences were interpreted as significant at an error probability of less than 5% (p<0.05), i.e., if p>0.05, the null hypothesis was not rejected.

[0040] Further, by comparing the biomechanical properties, the following average values ​​of load (N), stress (MPa), and Young's modulus (Pa) were obtained, shown in Fig. 3. It should be clarified that up to 35 seconds, the material under study behaved as elastic-plastic, while afterward, inelastic fracture processes were detected. Therefore, the characteristics for up to 35 seconds were subject to comparison.

[0041] By examining the digital data from the tensile testing machine shown in Fig. 1, the best results were found in the 1st group, where an uncovered endoscopic biliary stent (WallFlex RX), made of a metal alloy - nitinol (characterized by chemical inertness and not causing a rejection reaction), was used as a transplant to eliminate the rupture of the ligamentous apparatus with pelvic eventration.

[0042] Morphological signs of a favorable course of the regenerative process in eliminating the rupture of the ligamentous apparatus with pelvic eventration by implanting transplants are the appearance of mature collagen with distinct capillarization processes 1, the presence of areas of neoangiogenesis represented by newly formed vessels, minimal leukocyte infiltration, the formation of a dense hyalinized scar, with the integration of an uncoated endoscopic biliary stent with muscle fibers within 10 days after surgery (Fig. 4); Signs of an unfavorable regenerative process include the absence of mature collagen for up to 10 days after surgery with pronounced leukocyte infiltration 3, with visualization of multiple cystic formations, the presence of foreign body cells, with marked atrophy of muscle fiber 2, which is observed during morphological examination of preparations of the 2nd group (Fig. 5).

[0043] Thus, a morphological study confirmed that the use of an uncovered endoscopic biliary stent (WallFlex RX) as a graft results in more significant elimination of ligamentous apparatus rupture and a significant improvement in the strength characteristics of the operated MONT. Morphological signs of mature collagen in the postoperative scar, the presence of neoangiogenesis sites represented by newly formed vessels, minimal leukocyte infiltration, and the formation of a dense hyalinized scar with integration of the uncovered endoscopic biliary stent with muscle fibers indicate a favorable regenerative process and the sufficient quality of the surgery performed using the WallFlex RX stent.

[0044] The data on the significance of the morphological study are confirmed by the indicators of the general blood test (a persistent increase in band neutrophils, ESR and regeneration index indicates a persistent inflammatory process and allows us to assume possible complications) and the average values ​​of load (N), stress (MPa), and Young's modulus (Pa), obtained on a tensile testing machine (with an unfavorable morphological picture, a decrease in the strength characteristics of the abdominal wall is observed).

[0045] The claimed method is quite simple to carry out, involves the use of a trigger grenade of the M67 RS brand to organize an explosion instead of complex and expensive devices and accessories, the handling of which does not require special knowledge and skills, which are produced by domestic manufacturers and are available for sale, does not require carrying out in specially equipped rooms or equipped sites of training grounds, is practical, and therefore is available to research groups subject to safety precautions.

Claims

1. A method for eliminating the consequences of a simulated mine-fragmentation-directed trauma to soft tissues and pelvic organs with pelvic eventration in an anesthetized laboratory animal - a rat, characterized by the fact that trauma is inflicted by a shock wave and damage by striking elements on a previously trimmed surface of the animal's body;to simulate a rupture of the uterine walls in female animals with separation from the ligaments and from the Denon-Villiers aponeurosis, which limits the vagina from the rectum, the injury is inflicted with an M67 RS airsoft grenade with damaging elements in the form of balls with a diameter of 2 mm, having a powder charge consisting of magnesium powder and potassium perchlorate, from a distance of 50 cm, while the animal is placed in a container, in a horizontal position lying on its back with its hind legs spread and fixed so that the area of ​​the perineum subject to injury is at the level of the dispersion and ricochet of the damaging elements, and the airsoft grenade is oriented along the explosion vector onto the perineum; after which a macroscopic assessment of the lesion is performed and a dissection of the soft tissues is carried out so that the section plane is perpendicular to the skin surface and passes through the center of the injury area;The defect of the muscular-fascial layer is corrected, the damaging elements are removed, and the rupture of the ligamentous apparatus with pelvic eventration is repaired by installing a transplant; on the 5th and 10th days of the experiment, blood is collected, the number of band neutrophils, ESR and regeneration index are determined; to assess the engraftment of the transplant, 10 days after its installation, material is collected for morphological and biomechanical studies.

2. The method according to paragraph 1, characterized in that a WallFlex RX biliary stent is used as a transplant.

3. The method according to paragraph 1, characterized in that the transplant is installed by laparotomy.

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