| Objects:Fractures of small tubular bones such as the clavicle,fibula,and metatarsus are common clinical fractures.The surgical treatment of small tubular bone fractures includes steel plates and intramedullary nails.Intramedullary(IM)fixation is gradually accepted due to its minimally invasive advantages.There are various IM fixation methods,such as Kirschner wire,Rockwood needle,and Threaded Elastic Intramedullary Nail(TEIN).After 26 years of systematic research,Our team designed an Elastic Locking Intramedullary Nail(ELIN)through continuous improvement and innovation,which is used to treat small tubular bone fractures such as the clavicle,fibula,and phalanges.Based on this,Elastic Osteosynthesis(EO)is proposed,that is,1.Controllable intermittent rotation,bending and shear stress also promote bone healing.2.Anti-shrink elastic deformation internal fixation can not only promote fracture healing,but also accelerate fracture healing.At present,the clinically used ELIN material is 317L stainless steel.During the application process,it was found that the material has poor elasticity and fatigue resistance,which affects the effects of EO treatment,such as broken nails and other complications.Therefore,it is necessary to improve ELIN and choose materials with good elasticity and fatigue resistance to prevent broken nails and even failure of internal fixation.After research,nickel-titanium alloy has the characteristics of wear resistance,corrosion resistance,high damping,high fatigue resistance and super elasticity,and there have been reports of clinical application of nickel-titanium internal fixation.Based on the above problems,this project uses 317L stainless steel and nickel-titanium alloy as the internal fixation material to make ELIN,and tests and compares its mechanical properties.The first data is proposed to explore whether nickel-titanium alloy can replace 317L stainless steel as the preferred material for ELIN.Based on the data obtained from mechanical studies,a series of parameters such as the diameter of the nickel-titanium alloy ELIN could be designed.Methods:In this experiment,four different mechanical tests(static three-point bending test,tensile test,torsion test,and fatigue test)were used to determine the mechanical properties of 317L stainless steel ELIN and Ni-Ti alloy ELIN.Data were collected and analyzed by statistical analysis of SPSS statistical software.Data were expressed as mean±standard deviation.Statistically,difference was only considered significant when P<0.05.Results:1.In static three-point bending test,when the span is 100mm,the yield strength of 317L-ELIN is 53.00±2.65N,and the yield strength of Ni-Ti-ELIN is33.33±2.08N.The comparison between the two groups is statistically significant(P<0.05)).The compressive yield strength of 317L-ELIN is better than Ni-Ti-ELIN.2.In the pull-out test,the yield strength of 317L-ELIN was 3475.67±12.67N,and the yield strength of Ni-Ti-ELIN group was 1640.00±22.91N.There is statistical significance between the two groups(P<0.05).The tensile yield strength of317L-ELIN is better than that of Ni-Ti-ELIN,but the ductility is weaker than that of Ni-Ti-ELIN group.3.In the torsion experiment,at the thread,the maximum torque of the 317L-ELIN group is 1.90±0.08N·M,and the maximum torque of the Ni-Ti-ELIN group is 1.65±0.18N·M.There is no statistical difference between the two groups(P>0.05);In the nail body,the maximum torque of the 317L-ELIN group is 1.16±0.07N·M,and the maximum torque of the Ni-Ti-ELIN group was 1.48±0.08N·M.There is a statistical difference between the two groups(P<0.05).The rotation fatigue resistance of the Ni-Ti-ELIN group iss significantly better than that of the 317L-ELIN group.4.In the fatigue test,when the span is 100mm and the rated cycle number is 10~6times,the 317L-ELIN cycle number is 574665±55913 times,and the Ni-Ti-ELIN group is not broken within the rated number of times.The fatigue resistance of Ni-Ti-ELIN is significantly better than that of 317L-ELIN.Conclusions:Ni-Ti-ELIN’s torsional strength,ductility and fatigue resistance are better than 317L-ELIN.Although its rigidity is inferior to 317L-ELIN,it has met the requirements of intramedullary fixation of small tubular bones such as the clavicle,and more in line with the requirements of EO theory.It is initially believed that it can replace 317L-ELIN,but further verification by animal experiments and clinical trials is still needed. |
