3D Printed Polylactic Acid/Hydroxyapatite Composite Implants For Bone Repair

As the aging of the Chinese population is getting worse,the bone defects caused by own factors or external factors are also increasing.The traditional treatments currently used in clinic are generally bone transplantation,including autologous transplantation,allograft transplantation and artificial scaffold transplantation.The many defects of these methods limit their use.This makes it necessary to design and develop more strategies for the treatment of large-area bone defects to meet clinical needs.Three-dimensional(3D)printing has developed rapidly in the past few decades due to its many advantages.Polylactic acid(PLA),as a thermoplastic polymer material,has a relatively stable melting temperature,proven biodegradability and FDA-certified biocompatibility,and has been widely used in traditional orthopedic surgery.This article discusses the different applications of 3D printed polylactic acid and its composite materials in orthopedics to help guide the development of 3D printing and improve orthopedic 3D printing strategies.The main contents and conclusions of this study are as follows:(1)Synthesis of polylactic acid/nano-hydroxyapatite(PLA/nHA)composite filament.Nanoscale hydroxyapatite was synthesized by the co-precipitation method,and the composite filament containing 10%nHA was synthesized by the melt blending method.The 3D printing PLA/nHA were characterized by infrared spectroscopy,Raman spectroscopy,and scanning electron microscopy.The mechanical properties of PLA/nHA composites were tested using a universal testing machine.The research results show that the melt blending method does not affect the original chemical structure of PLA and nHA,and the composite filaments prepared by this method are mixed uniformly.The thermodynamic properties of PLA composites after adding nHA will not change,and the mechanical properties will be increased.(2)Biocompatibility test and small animal experiment of 3D printed PLA/nHA composite implantPLA/nHA composite implants were prepared by 3D printing.MG-63 cells were selected to test the biocompatibility of 3D printed PLA/nHA composite materials,and New Zealand rabbits were used to test the osteogenesis ability of PLA/nHA composite implants and the effect for repairing bones.The results show that PLA/nHA composites have good cell compatibility,and the composite implants after 3D printing have osteogenesis and bone conduction effects.(3)3D printed PLA/nHA composite scaffold for repairing alveolar bone in pig oral cavityThe PLA/nHA scaffolds were prepared by 3D printing,pigs were used as experimental animals because of the structure are more similar to human oral cavity.The biocompatibility and osteogenic properties of the composite scaffolds in alveolar bone were tested,and the results showed that histology was mature.The trabecular bone has high calcification and good osteogenesis,and has potential value as an alveolar bone repair material.