A 3D kinematic measurement of knee prosthesis using X-ray projection images (Countermeasure to miss-estimation and effects of image quality on the estimation accuracies)

We have developed a technique for estimating 3D motion of knee prosthesis from its 2D perspective projections. Our primary studies of computer model simulation and experiments on the CCD images of prosthesis demonstrated sufficient accuracies of position/orientation estimation for knee prosthesis. Then we changed over our project from the basic analyses and experiments to the countermeasurements against various problems which could possibly happen at clinical application. Among them, the following problems and their solutions are stated in this paper : Miss estimation for an orientations of a tibial compartment due to its symmetry-like shape, effects of image quality on the estimation accuracies. It is also ahown an idea how to improve the estimation accuracy of translation along the direction perpendicular to the image plane.