| Background:Blunt injuries can be caused by any blunt objects.The damage depended on the elasticity of the soft tissue and the rigidity of the bone in blunt violence,the damage occurred when the strength of the force exceeded the ability of the tissue to adapt or resist.Blunt injury was the most common type of injury in forensic practice,it was difficult to judge the damage mechanisms in practice.Forensic analysis and judgment of blunt injury mainly relied on specialist experience,it was not possible for general population to really explain the specific biomechanical mechanism of blunt injury,so it can cause some trouble to the judicial appraisal.However,most of the research in the literature was based on retrospective analyses,human and animal carcasses to explore human injury mechanisms,but due to the limitation of experimental samples,the differences of the physiological structure of the human body and animals body,corresponding ethical issues and big distinction between traditional biomechanics research and forensic medicine practice,all these factors contributed to slow progress in the biomechanics of forensic injury..The finite element method was a digital technology that uses modern computer technology for analysis and has been become an important experimental tool for studying human biomechanics.This research method was compared with traditional biomechanical experiments,it had the characteristics of accuracy,simplicity and repeatability.The finite element method can be effectively used to the study the biomechanical mechanism of damage and the method of injury.Objectives:In order to provide new ideas and new methods for the identification of blunt injury in forensic medicine,the finite element model and method was used to study the biomechanical mechanisms of blunt liver injury,spleen injury and rib fractures.Methods:This project used the THUMS model to study the mechanism of blunt injury under different conditions.The THUMS model was jointly developed by Toyota Motor Corporation and Toyota Central Research Institute,the purpose of developing this model was to study human kinematics and injury biomechanical response in traffic accidents.The loading injury methods include boxing,stick strike and fall from height.Simulating blunt liver,spleen injury and rib fracture under different injury modes.To analyze the injury mechanisms according to the stress-strain distribution of specific organs and tissues in the simulation results,the relative relationship of between surrounding tissues and specific organs,the corresponding biomechanical parameters and response trend,and compare the simulation results with real cases.Results:1.The mechanisms of liver and spleen injury in a boxing situation were that the liver was directly hit by the ribs,right-side boxing was most likely to cause liver injury,rear-side boxing was more difficult to cause liver injury.Rear and lateral impact were easy to cause spleen injury,front boxing was more difficult to cause spleen injury,in addition,the spleen was pulled by the splenic pedicle.2.The main mechanisms of liver and spleen injury were that liver and spleen moved relative to the surrounding tissues and organs,and caused direct impact with surrounding tissues,in addition,pulled by accessory ligaments and dominant blood vessels in high fall simulation.3.The study found that there were some differences in the rib fracture sites when different parts of the trunk collided the ground.The fracture were mainly located in the anterior side and side of ribs in prone position falling,the fracture were located in the posterior side and side of ribs in supine position falling,the fracture were mainly on the side under direct force when the side of trunk touched the ground.4.The mechanisms of rib fracture was caused by direct or indirect violence during the contact between the thorax and the ground,and damage can occur when exceeded the damage threshold.Conclusion:The finite element method can be used to explore the mechanisms of blunt liver,spleen injury and rib fractures,and has practical significance for the analysis of blunt injuries in forensic science. |
