Structural Design And Biological Evaluation Of 3D Printing Ti Based Porous Implants For Individualized Osteoporosis Adaptation

Osteoporosis is a bone degeneration disease commonly occurring in the middle-aged and elderly people.Currently,medical implantation is one of the effective treatments for osteoporotic bone injury,and surgical treatment often requires the aid of bone implants.The biocompatibility and mechanical compatibility of bone implants are two key factors for successful implantation.At present,the high mechanical strength of the most commonly used metal bone implants is easy to cause stress shielding resulting in implant failure.The porous structure reduces the mechanical strength of the implant and increases the ability of the implant to combine with the bone tissue.At present,combining finite element simulation which is used to control the pore structure with 3D printing to manufacture implant is one of the hot topics in the field of bone implants.Ti6Al4 V is currently the most widely used material for clinical bone implants.In this thesis,the Ti6Al4 V and 3D printing technology are used to explore a kind of bone screw with good biocompatibility and mechanical compatibility.The closer to the elastic modulus of bone implant and human bone,the more likely it is to avoid stress shielding after implantation.In this thesis,the finite element software and 3D drawing software are used to design and analyze the structure of bone screw unit and the influence of different structural parameters on elastic modulus of the unit is also studied.The quadrilateral elements combinations were selected for cell experiments.It was found that the torsion resistance of the bone screw was poor.So the torsion resistance of the bone screw was optimized.It was shown that the porosity was the main influence factor for the elastic modulus of the wall structure.Then,the 3D printing technology was used to shape the designed structure.Before printing,the support and print scan mode were designed.After printing,the forming precision and surface morphology of the formed parts were observed and analyzed.The results showed that the precision of the forming part was within the range of 0.1 mm,which meets the requirement in application and the powder particles would adhere to the surface,thus the subsequent surface treatment is necessary.Two ways of the surface treatment were applied,acid etching and micro arc oxidation.By adjusting the processing parameters,the samples with micron pit structures were obtained.The osteoblasts were inoculated on the treated surface to observe the biological behavior.The results show that the pit like surface structure by the acid etching treatment was more favorable for cell growth and the cells had certain tendency growing on the implant surface.To sum up,the implant structure with suitable elastic modulus can be obtained by changing the structural parameters.The 3D print implants with microcosmic induced structure can provide a favorable environment for the growth of osteoblasts.This study provides a possible way for designing and manufacturing of new implants.