Design And Evaluation Of Personalized Titanium Alloy Tibial Bone Plate

Although metal bone plate is a common medical device in fracture surgical fixation,its non-personalized design and complex traditional manufacturing technology still have some deficiencies.However,the personalized design and the direct additive manufacturing of bone plate can solve the problems of traditional technology,and further enlarge the comprehensive benefits of additive manufacturing.In view of this,a bone plate applied in the surgical treatment of 42-A simple fracture in the lower 1/3 segment of tibia was selected as a model for related design and evaluation.The purpose is to achieve better individual adaptability and lower stress shielding rate,and further realize the comprehensive benefits of additive manufacturing.At the same time,the research results can provide references for the design and manufacturing of other parts of internal fixation plates and even other related additive manufacturing orthopedic implants,as well as the establishment of relevant standards.Based on the structure,blood supply,fracture classification and internal fixation of the tibia,the design of the titanium alloy tibial bone plate was completed by using CT data and related Reverse Engineering softwares such as Mimics,3-matic,Geomagic and NX UG.The trial production and evaluation of the bone plate were also conducted.Through finite element analysis,the surface grooving design and optimization of tibial bone plate were further completed.The main conclusions are as follows:(1)The difference between the elastic modulus of the TC4 titanium alloy in the Sintering Laser Melting and the traditional forging process is small.However,the range of the elastic stage has been expanded and the tensile strength has been improved.Therefore,Sintering Laser Melting has certain technological substitution,but the premise is appropriate heat treatment process.(2)Under normal conditions,the stress of the tibia was concentrated in the front edge and rear side of the tibia.However,obvious stress shielding can be observed in the mounting area of the bone plate after the fracture was fixed,At this time,the stress distribution on the bone plate was relatively uniform,which mainly distributed on the front right side and the back left edge of the bone plate.What’s more,there was a large stress area in the main force area of the bone plate near the fracture gap,and the stress on the tibia was mainly distributed in the posterior side of the tibia,which can resulte in slight compression on the ends of the posterior tibial fracture.Therefore,the bone plate in the fracture gap area and the the bone near the contralateral area of the fixing area should be emphatically analyzed in the correlation analysis and evaluation.(3)After the grooving design,the stress on the bone plate after fracture fixation was more distributed in the plate body,and a low-stress "island" would be formed on the screw hole wall of the plate.The contact between the two ends of the fracture was improved,and the stress shielding rate of the bone plate decreased.The grooving designs can reduce the stress shielding ratio.The larger the grooving range,the more obvious the reduction effect.Regardless of the difference in the number of grooves or the structure of the grooves,the grooving of the bone plate has little effect on the maximum stress on the tibia after fracture fixation.Therefore,the surface grooving design is one of the effective ways to reduce the stress shielding rate of bone plate.In addition,it can be considered to increase the grooving range as much as possible under the condition of ensuring the strength of bone plate and the stability of fracture fixation.(4)The design of longitudinal grooving on the inner surface can lead to more stress distribution in the plate body of the bone plate,more obvious island phenomenon,and further reduction of the stress shielding rate of the bone graft plate.Therefore,this design is the best personalized plate type design for the internal fixation of the 42-A simple fracture in the lower 1/3 segment of tibia.The research results provide a new design idea for the practical application and relative improvement of personalized bone plate.