Effects of Blast Wave-induced Biomechanical Changes on Lung Injury in Rats

Objective To observe the dynamic impacts of shock waves on the severity of lung injury in rats with different injury distances.Methods Simulate open-field shock waves;detect the biomechanical effects of explosion sources at distances of 40,44,and 48 cm from rats;and examine the changes in the gross anatomy of the lungs,lung wet/dry weight ratio,hemoglobin concentration,blood gas analysis,and pathology.Results Biomechanical parameters such as the overpressure peak and impulse were gradually attenuated with an increase in the injury distance.The lung tissue hemorrhage,edema,oxygenation index,and pathology changed more significantly for the 40 cm group than for the 44 and 48 cm groups.The overpressure peak and impulse were significantly higher for the 40 cm group than for the 44 and 48 cm groups(P<0.05 or P<0.01).The animal mortality was significantly higher for the 40 cm group than for the other two groups(41.2%vs.17.8%and 10.0%,P<0.05).The healing time of injured lung tissues for the 40 cm group was longer than those for the 44 and 48 cm groups.Conclusions The effects of simulated open-field shock waves on the severity of lung injuries in rats were correlated with the injury distances,the peak overpressure,and the overpressure impulse.

A novel conceptual design of a biomimetic oral implant and its biomechanical effect on the repairment of a large mandibular defect

This study aimed to propose a novel biomimetic design strategy of an oral implant and to numerically examine its biomechanical effect according to clinical interests.The designed implant conceptually mimicked the morphology and elastic modulus of the mandibular bone.Basing on a CT-image-based patient-specific reconstruction of the tumor-excised mandible,the biomechanical effects of the implants with three materials(PEEK/n-HA/CF,PEEK/HA and Ti6Al4V),two surgical conditions(removed and retained muscles),and two postoperative stages(early and late)were fully investigated by a static finite element analysis.Moreover,according to clinical interests(e.g.failure and stability of the implant and rivets),maximum von Mises stresses and strains of the implant and rivets,maximum implant-bone gap in the early postoperative stage,and maximum von Mises stress of the mandible were mainly analyzed.The results showed that the implant composed of Ti6Al4V material was suitable for the current design strategy with respect to the other two PEEK-based materials.Although the implants in the muscle-retained surgical condition had relative greater indices compared to the muscle-removed surgical condition,the index difference between the two conditions was slight.The biomechanical indices indicating the failure and loosening risks of implant and rivets were much reduced in the late postoperative stage with respect to the early postoperative stage due to the osteointegration at the implant-bone interface.Generally,the proposed novel design strategy could be useful to guide the design of the oral implant addressing different implant materials and surgical conditions,and further made proper suggestion to clinicians and patients.