FEA Of The Injury Mechanism Of Posterior Pilon Fracture

OBJECTIVE: To analyze the mechanism of posterior Pilon fracture by finite element analysis,and to provide reference for the classification and diagnosis of post-Pilon fracture.METHODS: A healthy middle-aged male was selected for CT scan of the ankle joint flexion.After obtaining the ankle joint image data,the three-dimensional finite element model of the ankle joint flexion was established using Mimics,Geomagic Studio,UG,Ansys and other software.According to the boundary conditions,different vertical and downward pressures were applied to the upper end of the humerus,and the stress state of the Pilon fracture was simulated.The mechanical analysis was performed.RESULTS: Through the finite element analysis of the posterior Pilon fracture,the stress cloud map,displacement cloud map and pressure value of the ankle joint skeleton are obtained,and it is concluded that the posterior lateral and posterolateral two stress concentrations appear on the lower tibial articular surface when subjected to different vertical and downward loads.The area and the stress concentration area are always at the back of the inter-turn line.When the load is 600 N,the stress peak is located on the posterolateral side of the joint surface.As the load increases,the stress peak shifts from the posterolateral side of the joint surface to the posterior medial side..In addition,when the load size reaches 900 N,the stress concentration area begins to appear in the lateral plexus nodules,and the stress-concentration area also appears in the calcaneus and the articular surface in contact with it.Under the action of different loads,thedisplacement peak of the lower part of the humerus is always in the lower tibial articular surface.Conclusion: In this experiment,the three-dimensional finite element model of the ankle joint was mechanically analyzed.It is speculated that the posterior medial aspect of the inferior tibial articular surface is more prone to fracture and the posterior medial fracture line is more widely distributed.When the violence is large enough,the posterior medial and posterior lateral bones will appear.The results can explain the classification theory of post-Pilon fracture proposed by Yu Guangrong and Haraguchi.The resulting stress distribution of the ankle joint is also consistent with the four-column typing theory of Pilon fracture proposed by Tang Xin.In addition,the talus anterior fracture may be due to the relative movement of the calcaneus after the ankle joint is in the plantar flexion and subjected to vertical violence,thereby hitting the lateral ganglia nodules and causing the fracture.