| Fracture is one of the most common traumatic diseases in clinical practice,and metal bone plates(such as stainless steel,titanium and its alloys)have always been the first choice for fracture treatment because of their high strength.However,the bone plates prepared from these materials have high elastic modulus and do not match the biomechanics of human bone,which will adversely affect callus formation and fracture healing.Moreover,the complex microenvironment in the human body can induce corrosion of metal materials and toxic ions release,which reduces the biocompatibility of the bone plate,and may necessitate surgical removal of the implant.Consequently,it is vital to develop advanced bone plate materials with suitable elastic modulus and good biocompatibility.Trabecular metal(TM)has an elastic modulus that matches human bone and with excellent biocompatibility.It shows excellent osseointegration and has a long-term chemical stability in clinical applications.However,the research on the use of plate materials in internal fixation systems for fractures has been in the blank.In addition,TM products produced abroad are based on glassy carbon,which is brittle and difficult to process and shape,additionally,their industrial production has been monopolized by foreign countries hindering mass production,causing price inflating and ultimately limiting their clinical applications.In recent years,porous silicon carbide(Si C)has attracted much attention due to its three-dimensional pore structure which is similar to human trabecular bone,has excellent physicochemical properties,the potential to become a novel scaffold material.In view of this,in this study,a novel of porous tantalum(pTa)metal was prepared by chemical vapor deposition(CVD)technology using porous Si C as scaffold.Based on the optimization of its preparation parameters,the kinetic process and structure-activity relationship of pTa prepared by CVD technology were explored,and trabecular bone pTa products with good mechanical and biological properties were screened out.On this basis,the osseointegration performance and biosafety of the trabecular bone pTa metal internal fixation system was further evaluated by constructing an animal fracture model,and the clinical therapeutic effect of the trabecular bone pTa metal internal fixation system was assessed via a clinical preliminarily study.The specific research contents are as follows:1.Carry out research on key CVD preparation technology of pTa products,exploration of the influence of process parameters such as vapor deposition temperature and gas flow rate on the thickness,surface purity and microstructure of Ta coatings.The kinetic process and formation mechanism of Ta coatings prepared by CVD technology were studied,and optimization of the preparation process of pTa products.On these basis,excellent trabecular bone pTa products were prepared,which solved the technical problem of quality stability control in batch production of pTa products.2.Optimization design and structure-activity relationship research of pTa products was carried out,the relationship between pTa structure and mechanical properties such as compressive strength,flexural strength,elastic modulus,etc.was established,and pTa products with good biomechanical compatibility with host bone was produced.Through optimized design,pTa products that are suitable for human bone tissue structure(pore size,porosity,etc.),biomechanics and other biological properties were prepared.The porosity of the product is as high as 80.2%,and the yield strength,compressive strength and elastic modulus are 45.8±2.9MPa,61.4±3.2 MPa and 4.8 GPa,which are consistent with the mechanical properties reported by Zimmer Inc.TM products.In vitro cell experiments confirmed that pTa metals have more significant cell proliferation,adhesion and osteogenic differentiation ability than p Ti metal.After 12 weeks of implantation in-vivo,the pTa product was surrounded by a large amount of new bone tissue,and there was no post-implantation inflammatory reaction.Histological staining showed that a large amount of new bone was formed around the pTa and in its porous structure,defining a product with good osseointegration ability.This study shows innovation of a trabecular bone pTa product structure with good mechanical and biological properties.This product has the potential of becoming a new material for bone implant.3.In-vivo fracture model was constructed to evaluate the effect of pTa metal internal fixation system on fracture healing and callus formation.By constructing a weight-bearing femoral neck fracture model on goats,it was proven that pTa screw can firmly fix fracture without displacement and fracture.This novel pTa screws have strong mechanical properties and can assist the bone plate in firmly fixing fracture.By constructing an internal fixation model of ulna fracture,this study shows that pTa metal plate internal fixation system can firmly fix fracture without breaking.Compared with Ti metal internal fixation system,pTa metal internal fixation system has low elastic modulus and high osteoconductivity,does not produce stress shielding,and can form good osseointegration with host bone,and implantation in the body does not negatively affect bone tissue.These results demonstrate the feasibility and advancement of pTa internal fixation system,which can be used as an internal fixation device for fractures.4.The clinical efficacy of trabecular bone pTa metal internal fixation system in the treatment of tibial fractures was clinically evaluated.The results show that after using a trabecular bone pTa metal internal fixation system,the average healing time of tibial fractures was 13.1±0.71 weeks,which was better than that of Ti metal internal fixation system.This clinical preliminarily study confirmed the good effect of the pTa metal bone plate internal fixation system in the treatment of tibial fractures.Furthermore,this solves the problems of existing traditional internal fixation system in fracture treatment and provides a new type of internal fixation system for clinical treatment of fractures,with a great application prospect. |
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