[Position identification in knee joint endoprosthesis]. / Lageerkennung in der Kniegelenkendoprothetik.

In this paper we present a method for measuring the wear of the polyethylene inlay in knee joint endoprostheses from standard X-ray images. Our approach is to estimate the spatial position of the tibial and femoral components of the prostheses from their contours in the X-ray image. When we know the exact shape of these two components, we can calculate the minimal spatial distance between them which approximates the remaining thickness of the inlay. First results show that this approach might provide sufficient accuracy for the given task.