The Establishment and Preliminary Application of the Three-dimensional Finite Element Model of Ankle Joint
|School||Dalian Medical University|
|Keywords||three-dimensional finite element model ankle joint biomechanics astragalus injuries|
Objective: (1) Use ANSYS software to build finite element model of human ankle and ligaments. (2)Compare the calculated results with the foreign experimental results, verify the validity of the model. Simulate and analyze stress distribution on astragals in the middle of human walking, and calculate the model.Method: (1) Select an ankle segment specimen without pathological changes as the research object. First get rid of soft tissues around the ankle ligaments like skin, muscles, etc, dissect the ligaments inside and outside anatomical ankle and mark them with metal line; And then make a CT scan and get 746 CT images with 1 mm layer and save them in the form of DICOM standard format. Use EFILM software to transfer the cross-section images into JPG format. Use the software of Matlab and ANSYS to build finite element models of ankle and ligaments around. (2) Apply 600 vertical loads on tibia lower part, and calculate the contact area and contact pressure on lower part of ankle and tibia. Bind the talus, the scaphoid and the calcaneal to the model, apply 2100 vertical load on the surface of tibia fibula, simulate and analyze the stress distribution on bones when a man of 60kg weight walks. Compare the calculated results with the foreign experimental results, and verify the validity of the model.Result: (1) The whole model has 114784 cell numbers and 22921 points, and the complex three-dimensional finite element model includes talus, scaphoid, tibia’s under section and the inner and outer side ligament. The model has good biological forms, and obtains satisfying and freely rotating 3d information, and meets the need of finite element analysis. (2) In the aspect of model verification, compared the calculated results with the foreign experimental results, this model has similar parts and it can be used in research and medical treatment. Through calculation and analysis of human body’s walking, talus’stress distributes mainly on talus neck, outer protuberance and inner protuberance, articular surface, tibial articular surface and back heel joint. And small part of the stress distributes on inner ankle joint and front heel joint.Conclusion: (1) The three-dimensional finite element ankle model built with CT scan is accurate and reliable, and it eliminates human interference to the best level, and it has the advantages of convenience, quickness and accuracy. And it can be applied to ankle biomechanics analysis for clinical work, and it provides theoretical data and reference. (2) The stress analysis results of astragalusthe can well explain the bone damage mechanism.