Establishment Of Digital Library For TKA Prostheses And Related Instruments Based On Reverse Engineering And 3D Printing

Objectives: To establish a model library of total knee arthroplasty(TKA)instruments using reverse engineering and three dimensional printing(3DP)technology.Based on the clinically practiced knee joint prosthesis as the standard prototype,a digital simulation model library(hereinafter referred to as the digital model)and a physical simulation model library(hereinafter referred to as the physical model)of the TKA devices was established through reverse engineering,optimizing 3D printing techniques with related materials.Method: The Gemini PS prostheses and supporting surgical instruments of German LINK Company were used as research objects.1.Under the premise of non-contact measurement,combined with the advantages of high-precision hand-held scanning system and 3Shape TRIOS~? portable color intra-oral scanner system,the scanning method used in combination is selected to obtain the three-dimensional structure of the TKA device.Then use the reverse engineering technology to restore the original structure of the device one by one on the digital simulation model to establish a TKA device digital simulation model library;2.Based on the source and error theory of the reverse engineering error,form the evaluation standard of the reverse engineering reconstruction TKA device model surface accuracy;3.The left knee joint femoral end replacement prosthesis L5,which has a complex curved surface and a regular plane and a large model size,was selected as an initial sample,and the experiment was designed based on the error theory.Three different fabrication schemes were used to test the feasibility of reverse engineering and 3D printing technology in simulating the accuracy of TKA instruments.Thereby,a digital simulation model library with high accuracy.Results: Scanning and modeling of TKA related equipment of German LINK Company have been performed through reverse engineering technology.A digital simulation model library was established with a series number for each individual piece following the original numbering system.The accuracy requirement of the 3D printing simulation model is the total error of 0.5 mm.According to the error theory,under this premise,when using the scheme 1 to make a model,the maximum error range of the secondary engineering reconstruction is 0.4086 mm.The average deviation of the model produced by the actual scheme 1 after reverse engineering is 0.1197 mm,and the standard deviation of local details is only 0.0798 mm,which is all within the tolerance of reverse reconstruction.When using the scheme 3 to make the model,the allowable error range of the secondary reconstruction of reverse engineering does not exceed 0.1872 mm.As a whole,its standard deviation of 0.1392 mm is within the allowable range of reconstruction errors,but from a local perspective,its standard deviation of 0.2096 mm has exceeded the allowable range.The deviation of the model produced in scheme 2 is 0.5288 mm,which has exceeded the requirement of the total error range.Conclusions: 1.A digital model library of TKA-related instruments,consisting of 122 instruments from German LINK Gemini PS-type prosthesis and supporting surgical instruments was established;2.A reverse engineering operation process and standards has been formed;3.The combination of reverse engineering and 3D printing technology meets the needs of the TKA device model library in accuracy,and the scheme 1 can be used as the preferred method for making physical simulation models of TKA devices.4.Preliminarily laid the foundation of digital model and 3D physical model for clinical pre-operative simulation exercise in future.