A Study On The Fracture Model Of Tibiofibulas Based On Impact Biomechanics

With the development of the transportation industry,China has been one of the countries with the most deaths from road traffic accidents in the world since the load traffic accidents has been the focus of attention.Although the total number of traffic accidents happening every year has been effectively controlled,domestic traffic accidents are still very serious as the number is too large and the decline too slow when the road transportation industry developed rapidly and the number of motor vehicles increased steadily in China.According to statistics,in the past five years,road traffic accidents caused an average of 60 000 deaths and 212 000 injuries every year.Though lower limb injuries are not usually fatal,they are one of the most common causes of disability,causing huge economic losses and burdens for the injured and their families.Therefore,it is particularly important to fully analyze the cause of road accident and differentiate the responsibility of the case in the process of handling occurred traffic accidents in detail.In the traffic accidents involving pedestrians,the pedestrian’s no regulating moving route pose great challenges to the cause analysis and the responsibility differentiation.This topic has been studied the fracture morphology of the long bone of the lower limb under different lateral loads,aiming to the analysis of the relationship between the pedestrian’s lower limb fracture morphology with pedestrian facing in the car-pedestrian traffic accident.Nowadays,there are a large number of studies on the mechanism of lower limb injury and the threshold of lower limb bone fracture,but little on the fracture morphology under different stress condition.We collected local pedestrian traffic accidents via the Chongqing traffic accident identification agencies to speculate the relationship between tibial fracture morphology and pedestrian facing in pedestrian-car collision.The results were verified and supplemented by mechanical formula deduction,finite element simulation of pedestrian-car accident and fresh pig fibula three-point bending experiment.1)Case collection and study of lower limb fractures: Based on the traffic accident identification platform of Chongqing,460 pedestrian-car accidents in Chongqing and some surrounding areas from 2010 to now were collected and statistically analyzed.And the reason of the regularity between fracture shape and collision force direction is deduced by mechanical formula.Conclusion: In pedestrian-car accident,most of the long bones of pedestrian lower limbs were wedge-shaped fractures or oblique fractures.According to theoretical derivation,when the long bone is subjected to lateral load,the fracture site should be near the load and there is a possibility of generating wedges.2)Finite element high-speed collision simulation: In the simulation,the parts of pedestrians facing towards the car were adjusted,and simulation experiments were carried out on the collision of the car and pedestrians in front,left,right and rear respectively.On this basis,supplementary experiments were carried out to obtain the fracture morphology of bones in low-speed extrusion.Conclusion: The fracture morphology of the tibia was related to the pedestrian facing when impacted,we call it anterior impact,right impact left impact and rear impact.The anterior impact,right impact and left impact were all wedge-shaped fractures.The wedge was located on the side where the long bone was impacted.It is more difficult to fracture the tibia under rear impact than front impingement and side impact and the fracture section is mostly transverse fracture.Under low speed compression,the tibia mostly presented oblique fracture.3)Low-speed squeezing three-point bending experiment of porcine fibula: The mechanics experiment platform was set up,suitable specimens were selected and prepared for the three-point bending mechanics experiment of long bone.In the experiment,the threepoint bending experiment was divided into three groups according to the anatomical structure of bones,medial surface loaded,lateral surface loaded and front-rear loaded.The corresponding data were collected and analyzed.Conclusion: The fracture sites of the bone were all at the loading point of the fibula,and the fracture sections were all oblique fracture.Fibula experiments of Front-rear loaded is accompanied by torsion,and the fracture pattern without torsion cannot be shown.In the experiment of medial surface loaded,the pre-fracture bending is more serious than that lateral surface loaded,and the peak load in the failure process is relatively small,which is relatively more prone to fracture.