Design And Preparation Of Hydroxyapatite-based Implants With Honeycomb Sandwich Structure

Aging population,obesity,lack of exercise and other external factors lead to an increasing number of patients with bone defects year by year.Bone tissue has a certain ability of self-repair.However,bone defects beyond critical size cannot be completely cured by self-repair,so implants are needed to restore normal function.Autogenous bone graft and allogeneic bone graft have good adaptability to bone graft,but due to the limited number of autogenous bone graft,the low safety and infection of allogeneic bone graft,it cannot be widely used.Therefore,the study of artificial bone implants has social significance.At present,calcium phosphate ceramic materials such as hydroxyapatite(HA)are widely used in bone implants because they have similar inorganic components to human bone tissue,and can form good bone bonding,promoting the growth of new bone along the pores.However,HA based implants with three-dimensional porous structure are not suitable for non-load bearing bone replacement or bone defect filling due to their poor mechanical properties and brittleness.In this paper,honeycomb sandwich structure was designed as bone implant structure,which can reduce weight,increase strength and has good mechanical properties.In order to meet the requirements of high mechanical properties and good biocompatibility of bone implants,the composite PEGDA / SA and HA / COL were used to increase the mechanical properties and biocompatibility of bone implants,and the structure was prepared by SLA 3D printing technology.The specific work of this paper is as follows:1.The finite element analysis of the size effect of honeycomb sandwich structure was carried out by using the orthogonal test method.Based on the minimum requirements of the three indexes of internal stress peak value,axial deformation and Anteroposterior(AP)deformation,the optimal structure size combination was determined,and the overall structure of the implant is locally optimized through stress analysis,and the honeycomb sandwich structure bone implant with stable structure and good mechanical properties was designed;2.PEGDA hydrogel was prepared by light-curing,and its curing time and mechanical property were tested.The effects of different content photoinitiators on the structure and property of PEGDA hydrogel was investigated.SA was introduced into PEGDA hydrogel,and the interpenetrating network structure was formed by chemical crosslinking and photo-crosslinking to improve the mechanical property of PEGDA hydrogel.PEGDA/SA composite hydrogel was prepared,and the viscosity and mechanical property were tested;3.Using SLA 3D printing technology,according to the data ratio of PEGDA/SA composite hydrogel,the effect of 3D printing parameters on the shaping effect of the scaffolds was explored.Then,HA/COL composite powder was added into PEGDA/SA composite biomaterial to increase biocompatibility.In this paper,the design and preparation of HA based honeycomb sandwich implants were studied.The honeycomb sandwich structure with stable structure and excellent mechanical properties was designed as bone implant structure by finite element analysis.The mechanical property and biocompatibility of the honeycomb sandwich structure were improved by composite materials.The structure was prepared by SLA 3D printing,which proved that the honeycomb sandwich structure could be used as bone implant in the field of bone defect repair.This study provides a feasible idea and method for the design,preparation and clinical application of orthopedic implants.