The Analysis Based On RSA Of Kinematic Measurement And Experiment Error Of Nature And Artificial Knee Joint

This research was supported by the National Natural Science Foundation of China“the research on high-flexion stability mechanism of high-flexion artificial knee(project number: 31370999)”,The movement characteristics of femur versus tibia in natural knee and knee prosthesis based on RSA technique were studied.The principle of experiment: According to the predecessors' research on RSA principle,a set of RSA technology based on three-dimensional knee accurate motion measurement program was proposed,adopting the basic requirements of in vivo,non-invasive and weight-bearing.Knee joint patella femoral joint movement measurement experiment combined knee three-dimensional reconstruction model,double C-arm photographing and 2d-3d registration principle.Methods: the test subjects were the natural group and the knee prosthesis replacement group.All volunteers reconstructed the knee model by three-dimensional CT scan.The subjects were instructed to complete the three movements of squatting,walking and climbing stairs,and the fluoroscopic images obtained were calibrated and calibrated.The two-dimensional images of two C-arms were registered based on the three-dimensional knee joint geometry model.Finally,the data of the six degrees of the relative positions of the tibia and the femur of the knee joint were obtained.Analysis of results: According to the data obtained,the knee tibiofemoral joint movement was analyzed.With the flexion of knee increasing,natural knee joints continued to deepen the external rotation.In the squatting movement when knee flexion reached 95 degrees,the natural knee joint had a maximum of 26.5 degrees relative to the external rotation of the tibia.Thereafter,the angle of external rotation gradually decreased.During the flexion of the knee,the femoral continued posterior and the maximum was 19.4mm.Through the natural knee and artificial section comparative analysis,artificial knee and natural knee had the same trend.But artificial knee flexion is limited,less than 100 degrees in squat.The displacement of the femur is greater than that of the natural knee joint.The internal rotation Angle of the artificial knee joint was larger,reached 28.9 degree.The displacement of the femur of the artificial knee relative to the tibia was slightly larger than that of the natural knee,In addition,a small number of artificial knee joints appeared anterior femoral displacement.Error Analysis: The errors were occurred in the whole experiment include C-arm calibration,image correction,three-dimensional geometric modeling of knee joint,establishment of local coordinates of knee joint,synchronization of experimental instruments and post-manuscript errors.This paper mainly analyzed the synchronization error of two C-arms,the error of coordinate system establishment and the error of the contour line.Measured by experimental error synchronization error within 1 frame and The error of the coordinate system to establish the error translation direction was within 2mm,and the error on the rotation was within 4 degrees.The femoral contour error was 2.02 mm,and the tibia contour error was 1.89mm.