Development And Experimental Study Of Three-dimensional Printing System For Porous Bionic Bone Unit Implants

The ideal artificial bone implants should not only match the patient's bone defect area, but also have good mechanical properties and the internal interconnected micro-porous structure. Those bone implants made with traditional methods had some problems, such as time-consuming, difficult to process the internal micro-porous structure and could not meet individual needs of patients. Preparing artificial bone implants on the basis of 3D printing technology could overcome those drawbacks. In fact, the pore shape, size and distribution could be controlled precisely which would provide growth space for cell proliferation and accelerate bone repair process. At present, there still exist some problems in the preparation of artificial bone implants using 3D printing method, such as rare research on modeling of gradient porous structure and immaturity 3DP (Three Dimensional Printing) prototyping methods for bone defect repair. Thus, in this paper we presented an improved three-dimensional printing method and relative forming system for manufacturing porous bone unit. The main contents were as follows:Firstly,the research work focused on the bone defects which were created on a trabecular bone of a rabbit. The three-dimensional model was established by image segmentation and feature extraction on trabecular bone structure. After obtaining the outer of the trabecular bone defect site, four kinds of porous bone unit model, named"loose","close", "double-layer" and "three-layer", were designed to meet the bio-mechanical requirements of the implantation environment. And then the three-dimensional models of porous bone implant were set up by Boolean operation.The influences of the structural features of the proposed bone implants on its bio-mechanical properties were analyzed by finite analyzing method. According to the results,the "three-layer" structure expressed the most similarity to the nature human bone and better mechanical properties.Secondly,we present an improved three-dimensional printing process for the generation of porous bone unit based on 3DP method. The 3D printing platform for bone repair was build including design of the mechanical structure, motion control system and software system. The porous bone unit implants were made by the improved platform. During the formation of bone unit implants, the influence of system parameters, model structure and sintering process on the microscopic appearance and mechanical properties of bone grafts were discussed through the corresponding performance tests.The research results could provide a theoretical basis for the realization of high quality bionic bone printing based on 3DP technology,which has important theoretical and experimental significance for the clinical repair of artificial bone.