Application of pattern matching method in motion analysis for TKA

A 3-D motion analysis of the artificial knee joint is expected, as one of important techniques for geometrical design of the artificial knee joint. This study aimed to develop a 3-D motion analysis with high precision by using pattern matching (PM) technique with wide spreading high-resolutional computed radiography (CR). We report the method for calculating the geometry of the X-ray source and the evaluation of PM. The full six degrees of freedom (DOF) pose of prosthetic component were calculated by matching computer-synthesized projection images with experimentally acquired 2-D CR image. The 3-D geometry of prosthetic component was reconstructed using a curved surface by B-spline. PM was done using the parametrically calculated the six DOF in order to minimize the exclusive OR (XOR) between both of the binarized image. Further, some objective windows were set up on the screen to make reference time shorten. The femoral component was rotated in the center of calibration flame to examine accuracies of the PM technique. The numbers of pixels of XOR became zero by making the stop of 6-D parameters smaller. The accuracies of below 0.7 mm for translation and 0.7° for rotation were confirmed.