Design Of Porous Spatial Structure Bone Tissue Engineering Scaffold For Performance Control

Bone tissue engineering scaffold repair is one of the important ways of clinical treatment of bone defects.Repair of bone defect requires scaffold structure to be similar to the pore structure of human natural bone,scaffold material is conducive to the regeneration of bone tissue cells,and scaffold mechanical and biological properties are similar to the natural bone properties of human body.In this paper,the performance indexes of bone tissue engineering scaffolds are given,and a model structure and modeling method which can adjust and control the performance of bone scaffolds are proposed.The mapping relationship between the modeling parameters and the performance of bone scaffolds is established by theoretical analysis,simulation experiment and laboratory model experiment.Specific research contents are as follows:According to the basic requirements of bone tissue engineering,the structural design indexes of bone tissue engineering scaffolds were put forward,and three kinds of spatial structure of bone scaffolds were constructed by using regular cell cube,cylinder and sphere.Taking porosity,specific surface area and elastic modulus as performance indexes,the comprehensive performance of the scaffold was evaluated by fuzzy theory,and the better comprehensive performance of the cube structure bone scaffold was selected.Based on the performance requirements and indexes of the bionic bone scaffold,a parametric modeling method of Tyson polygon bone scaffold based on Rhino and Grasshopper software was proposed.The spatial three-dimensional bone scaffold model with Tyson polygon structure and the bone scaffold model matched with the shape of human body defect parts were constructed.The construction method of Tyson polygonal bone scaffold with bone-like gradual pore structure is presented.Two modeling parameters controlling the number and size of the mesh of Tyson polygonal bone scaffold were found,which were seed number and scaling factor.The finite element analysis models of bone scaffolds with different seed points and scaling factors were established.The effects of seed points and scaling factors on the porosity,specific surface area and equivalent elastic modulus of bone scaffolds were analyzed,and the feasible region of seed points and scaling factors for modeling bone scaffolds meeting the performance requirements was determined.The Abaqus-CFD fluid simulation software was used to establish the nutrient fluid flow and adhesion performance analysis model inside the bone scaffold,and the pressure field and velocity field inside the bone scaffold were obtained;the permeability of the bone scaffold was calculated through a combination of theory and simulation.The mapping relationship between porosity and permeability,porosity and specific surface area was discussed;the adhesion layer thickness and permeability range of the designed bone scaffold model were determined.Propose a 3D printing method for bone tissue engineering scaffolds with porous spatial structure,using fused deposition 3D printing technology,using polylactic acid renewable biodegradable materials,reasonable selection of printing parameters and processes,and achieving 3D printing of complex microporous structure bone scaffolds;Compression experiments were performed on the bone scaffold models with different seed points and scaling factors,which further verified the mechanical properties of the designed Tyson polygonal bone scaffold,and proposed the mapping relationship between the porosity of the bone scaffold and the equivalent elastic modulus.