89 / 2018-06-22 08:35:25

Design and Automatic Modelling of Gradient Porous Implant

porous structure,functional gradient implant,Finite Element Analysis

全体主题 > vi. BAMOS (Biomaterials and Additive Manufacturing: Osteochondral Scaffold innovation)

Introduction: Long-term loosening initiated by stress shielding is the major cause of the failure of arthroplasty. Design with porous structure is believed to reduce the stress shielding of metal implant. Usually, the design of porous implant is implemented by the determination of the elastic modulus distribution. However, the lack of efficient modelling tools restricts the application of implant with irregular gradient porous distribution. The aim of this study was to develop a general methodology for the design of customized gradient porous implant.
Materials and methods: Functional relationship between macro mechanical properties and micro structure of porous representative volume elements (RVEs) was established by finite element (FE) analysis as well as mechanical properties. The optimal distribution of elastic modulus of the implant was obtained in line with the design criterions of safety and stability, under the control of algorithms in FE model. Elastic modulus of all the elements in the FE model of the implant were read and transformed to the mechanical properties of every RVEs. Then porous prosthesis was established by assembling all the RVEs automatically according to the functional relationship between elastic modulus and geometrical parameters through python script in Abaqus software (V6.14, Dassault, France). Finally, the realistic 3D model of porous prosthesis was transformed to STL format which apply to additive manufacturing.
Results: A hip stem with gradient modulus distribution was taken as an example, the porous structure of the hip stem was automatic modelled in Abaqus with a type of body centred cubic (BCC) unit. The RVEs near the stem axis were almost solid while the RVEs near the surface had high porosity which stimulating bone remodelling and were benefit for long-term stability.
Conclusions: This study provided a universal method for the design and modelling of gradient porous implant. The methodology can also be utilized in various porous components.