Establishment of finite element model of ankle joint and its biomechanical study / 中华创伤杂志

ABSTRACT

Objective The three-dimensional finite element model of the normal ankle joint was established to simulate the changes of stress and displacement under stress from different directions and of different magnitudes so as to provide a theoretical basis for the biomechanical mechanism of the ankle joint injury.Methods Spiral CT scan was performed on the left ankle of a 30 year old healthy male volunteer to obtain the original CT image data.The three-dimensional digital model of ankle joint generated by Mimics and Geomagic softwares was imported into the software Ansys.The three-dimensional finite element model of ankle joint with complete anatomical structure was obtained after the main steps of meshing,central node,element linking and module loading using finite element method.Stress from different directions and of different magnitudes were loaded unto the model.The stress changes were measured by foot stress distribution measurement system.The stress changes,displacement change distribution,the stress peak value of heel are,metatarsal stress,and plantar contact stress area as well as the maximum,minimum,and contact are of the tibial articular surface contact stress were compared between the finite element model and the volunteer himself to verify the consistency.Results For the finite element model of normal ankle joint,the plantar peak stress was [(0.33 ± 0.10) MPa],the metatarsal stress was [(0.13 ± 0.21)MPa],the foot contact stress area was [(78.60 ±0.32)mm2],the tibial articular surface maximum contact stress was [(2.72 ± 0.10) MPa],the minimum contact stress was [(1.35 ±0.12)MPa],and the contact stress area was [(79.1 ± 0.14)mm2].For the volunteer,double foot plantar peak stress was [(0.35 ± 0.12)MPa],the metatarsal stress [(0.13 ±0.16)MPa],the foot contact stress area was [(77.3 ± 0.42)mm2],the tibial articular surface maximum contact stress was [(2.79 ± 0.23) MPa],the minimum contact stress was [(1.37 ± 0.20) MPa],and the contact stress area was [(79.10 ±0.14)mm2] (P ＜0.05).Therefore,the three finite element model of ankle joint was basically consistent with the real human ankle joint because of the similiar distribution,trend,and values.Conclusion The three-dimensional finite element model of normal ankle joint can objectively reflect the anatomical structure and biomechanical characteristics of the joint,which is of great value to understand the changes of the internal mechanics and ankle joint injury.