Design And Additive Manufacturing For Skull Porous Scaffold

The development of bone tissue engineering provides a new way to solve the skull defect problem.Nowadays,the bone tissue engineering scaffold still can not well meet the demands for the osteocyte attachment,growth and differentiation.The reason is that the micropore size and morphology in the scaffold can not meet the bionic requirements.To solve this problem,an isoparametric mapping porous scaffold modeling method was proposed and the scaffold forming technology was studied.Firstly,by scanning of skull specimen through the micro-CT,the shape model of the skull specimen and the micropore model of the cancellous bone were reconstructed.The feature surface of the skull was thickened according to the thickness of the cancellous bone measured.The macro model of the skull scaffold was obtained by constructing the accurate surface of the thickened feature surface model.The micropore model was inverted to obtain the trabecular bone model in cancellous bone.The size distribution of the trabecular structure and its morphological characteristics were analyzed to provide the basis for the design of the porous scaffoldSecondly,based on the trabecular morphology and the P-type implicit surface structure,the bionic micro solid units with the “spherical matrices” and “cylindrical tubes” structures were designed.Based on the cancellous bone micropore size and distribution data,hexahedral meshes were divided of the scaffold macro model.According to the isoparametric mapping algorithm in finite element theory,the whole macro-micro porous scaffold model was designed by transforming the micro solid unit into each hexahedral mesh.The scaffold micropore shape and size and the porosity parameters were changeable to realize the similarity with the trabecular bone.Then,finite element analysis of the scaffold model was carried out with two aspects of scaffold deformation and equivalent stress.The results show that the scaffold model has balanced mechanical properties.Finally,the feasibility of porous scaffold fabrication with biomimetic size was explored by using stereolithography and selective laser sintering technologies.The manufacturing error of stereolithography and surface roughness of the scaffolds fabricated by two different technologies were evaluatedThis design method overcame the problems that the porosity of the scaffold was not high enough and the inappropriate micropore size to a certain degree.With the combination of the additive manufacturing technology,it laid the foundation for the application of bone tissue engineering in the clinical practice for skull repair.