Experimental Study On Pathological Changes About Gunshot Wound And Explosive Blast Injury In Limbs Of Rabbit Models

Gunshot in limbs is the most popular part of war-wound with the incidence of 59% to 68%, in which the most complicated and hard to cure injury is the fracture that occurred in a war, and it's incidence was about 30%-50%. With the development of military science and technique, blast injury has the more and more ration proportion in modern war, so it's the high time to study on the therapy of it. The topic of this paper is to perform a preliminary study on characteristics of pathological changes in gunshot bone injury and the injury of vessels, nerves, muscles etc. in limbs after blast injury occurred through the establishment of gunshot bone injury and explosion shock models.1. Experimental study on pathological changes in long bone sclerotin of rabbit limbs after gunshotObjective: To observe the characteristics of pathological changes after gunshot bone injury happened, and with the observation we were assumpted to provide the theory basises for clinically curing firearm bone injury. Methods: We established the femoral bone gunshot model of rabbits by using experimental rifle (caliber size: 7.62mm, ball bearing weight: 0.25g, type: 53) to shoot the middle piece of the rabbits'thigh-bone. And we used HG202A-II speed measurement system to detect the velocity of the ball bearing before and after it penetrated the limb and compute the vulnerant parameters. Then observed the radiological, histological and electron microscopic changes in the injured part. Results: Gunshot bone injury is syntripsis which looked like comminution and was accompanied with much bone defect; at the both broken ends of fractured bone, severe injury with dissected periosteum and subperiosteal specific changes, such as break, irregular arrangement and fluffiness, inordinate grid structure occurred on the bone fibers, such changes showed a obvious and gradual shifting injured belt on the injured area. The electron microscopic scan result showed that the injury of osteocyte and Haversian system is progressive and irreversible. Conclusion: Gunshot bone injury often appears as serious syntripsis and periosteum dissection, and it can be divided into two areas: the comminution and the shock, and the later area has the worse subperiosteal bone injury.2. Experimental study on the injury of peripheral vessels nerves and muscles in rabbit's limbs by explosion shock wave.Objective:To explore the pathological features of peripheral vessels, nerves and muscles in extremities injured by explosion shock wave, and provide scientific the basis for emergency treatment of war injuries and preventing or decreasing its'complications. Methods: A total of 18 rabbits were placed 1, 2, 3m away from the explosive center, and high explosive shells were placed 60cm from the ground and electrically exploded. The physical parameters of blastwave was recorded with PCB pressure transducers. After explosion, the femoral arteries, sciatic nerve and muscles were examined, grossly, histologically and immunohistochemiscally. Results: The vascular endothelial cells were denudated, the spaces of contractile fiber cells increased and appeared puff, the vassular elastic fibers ruptured, flexed and deformed visibly. Some parts of the vessel wall ruptured completely or partly, leading to bleeding. A lot of apoptosis cells were observed in the blood vessel endothelium layer, smooth muscle layer and membrana adventitia layer under fluorescence. Nerve fibers arrayed disorderly with fully broke or partly broke, endolemmas were destructed severely and the nerve cell nucleus deformed with different sizes and displacement, these changes were observed through HE stain and using microscope, further more, muscel fibers break with loose arrangement, obvious sarcolemma and perimysium disruption were found under HE stain. A large number of apoptosis cells were found in the broken nerve fibers and epineurial small vessels by Tunnel stain and availing fluorescence microsope. Conclusions: Explosion shock does not only do serious injury to main target organs such as lung, stomach intestine and deaphragma auris etc., instantly but also to peripheral soft tissues for instance, large blood vessels, nerves and muscles etc; the smaller distance from the explosion center, the worse injury. Proper treatment of explosion shock injury in limbs should receive much attention.