Optimal Design And Functional Verification Of New Personalized Knee Prosthesis Joint Surface

BackgroundThe knee joints are major weight-bearing joints with a high utilization rate in sports and is prone to wear and tear in the process of movement.The total knee arthroplasty(TKA)is an effective treatment of the severe knee lesions and it has been widely used in clinic.Although The total knee arthroplasty surgery has become very mature,a large number of patients still need to undergo secondary repair surgery every year.Wear,looseness,local bleeding and inflammation are the main causes of the need for secondary repair.Studies have shown that the knee prosthesis with personalized design is more in line with the actual movement habit and mechanical environment of human body.However,in the actual design process,complete data of patients are often lacking,which make it difficult to implement the scheme.PurposeIn order to explore idea of precise design of personalized knee prosthesis,which can effectively reduce the probability of secondary repair,and effectively improve the use time of the prosthesis.This paper proposed to use the data of the healthy side as a template and combined with the parameter extraction method to forward design personalized knee prosthesis.Methods1.Feasibility verification of the design scheme of the prosthesisIn the Geomagic software,mirror the data on the left side and set it as the control group.The data on the right side were set as the experimental group for deviation analysis to verify the symmetry of bilateral knee joint.Effective data were collected for 18 cases of bilateral tibia and 69 cases of bilateral femur.The mimics 19.0 reconstruction was used to export the STL format file to Geomagic Wrap for surface optimization,and the deviation analysis function used to register it with the original STL format file to verify the software error.2.The method of the design of knee prosthesis2.1 contour design of femoral prosthesis of knee jointData in Dicom format of the distal femoral part of the healthy knee was imported into mimics to reconstruct the articular surface area in three dimensions.The reconstructed exported in STL file is then imported into the Geomagic software for surface optimization.The mirroring function in Geomagic software was used to construct the femur part prosthesis of the affected knee joint.2.2 contour design of tibial prosthesis of knee jiontThe designed STL format file of the knee joint femoral prosthesis was imported into mimics.Combined with the original data mask point,the trajectory of the articular surface slide wasextracted to determine the rotation position,and the surface characteristics of each part of the tibial prosthesis were determined by using the Boolean function,which was then fitted to the proximal end of the affected side to complete the contour design of the partial tibial prosthesis.2.3 construction of modular modeling systemPython is used to build 3 modules,including 3d-model building module,model continuous screening module and noise recognition module.It mainly depends on PIL,tesseract-ocr,pynput,opencv,numpy and aircv.Results1.Deviation analysis results showed that more than 95%regional differences were less than 1mm,and bilateral knee joints were highly similar.2.Before and after surface optimization with Geomagic,there was a significant statistical difference.However,the design concept of fitting and sliding of prosthesis surface is not affected.Moreover,because the femoral part of the knee joint prosthesis is a whole,and the tibial part is modularized,after the bone part of the femur is reconstructed by the mirror image method,the design of the knee joint prosthesis of the femoral part by the method of articular surface parameter fitting can effectively improve the design efficiency.3.Each module can complete its own work independently,and the continuous screening accuracy reaches 80%.However,the matching effect is relatively poor,which still needs to be further optimized.ConclusionsThe femur part of the knee joint prosthesis was designed by mirror image,and the personalized design scheme of the tibia part was designed by parameter extraction method.Modular modeling and filtering systems,though still requiring human intervention,can be used to move from data filtering to modeling.