Finite Element Simulation Of Biomechanics Of Human Ankle Joints

The ankle joint is an important joint of the human body and the ground,once the ankle joint damaged will directly affect the normal activities of the human body.Understanding the biomechanics of the ankle joint for the diagnosis and treatment has a very important significance.Therefore,this paper chose the finite element simulation analysis method to study the biomechanical characteristics of the ankle joint.The main method of this study is to use the Mimics,Geomagic studio and other software to establish the three-dimensional solid model of the ankle joint based on the MRI image of the ankle joint,and then the finite element simulation of the ankle joint was carried out,and finally the mechanical distribution of the ankle joint was obtained.The details include the following sections:1)Established the three-dimensional solid model of ankle joint with tibia,fibula,talus,scaphoid,calcaneus,tibial distal cartilage,talus cartilage,articular cartilage,analysed of the static neutral ankle joint including tibia,fibula,talus,distal tibial cartilage and talus cartilage by the finite element method,obtained the displacement,stress and strain distribution of the ankle joint in the neutral position,and verified its validity.The geometric entity model was more similar to the anatomical model of the ankle joint when the geometric model was established by dividing the articular cartilage region of the ankle joint into the boundary of the joint line between the ankle cartilage;in the loading stage,considering the difference of the weight of each ankle bone,the difference between the talus and fibula is loaded.The established finite element model is more close to the actual force of the human body than the previous studies.2)Finite element analysis of neutral ankle joints with ligament tissue was performed.A spring element is used to simulate the ligament tissue,and the mechanical characteristics of the ankle joint in neutral position are obtained when the complexity of ankle ligament is simplified.By contrast with the ankle without contain ligament tissue,it can be found the result of the ankle joint with the ligament in the overall displacement,stress and strain were decreased,indicating ligament tissue has a very important role in the stability of the ankle.3)Three dimensional finite element model of ankle joint was established based on the MRI of ankle with limited varus position,and the mechanical characteristics of ankle joint under different loads were studied.The study found that when the ankle joint was under the load of 3100N,ankle joint’s maximum displacement reached 5.77mm,the whole talus displacement reached 5mm,the contact area of the ankle joint was reduced by 80%,the ankle injury probability increased greatly.This provided a theoretical basis for the ankle joint injury diagnosis and foot protective clothing design.4)Established the ankle joint 3D geometry solid model with two screws fixation of medial malleolus after osteochondral autograft transfer surgery and the ankle joint 3D geometry solid model with three screws fixation of medial malleolus after osteochondral autograft transfer surgery and analysed the two models by finite element method.By comparing the mechanical properties of these two groups of ankle joint and normal ankle joint under the same boundary condition,the biomechanical characteristics of the ankle joint with two screws fixation of medial malleolus after osteochondral autograft transfer surgery were similar with the normal ankle,and the MAX equivalent stress of its screws were smaller.So with double screws to fix the medial treatment effect is better.