A computer-aided control system, a computer-based method and a computer program or a computer program product control an implant positioning of an endoprosthesis. Planning data are generated on the basis of a preoperatively acquired first image data set. The endoprosthesis is provisionally positioned intraoperatively. A second image data set representing the current ACTUAL position of the endoprosthesis is thereupon acquired. Control data are thereupon generated, the control data serve for the fine positioning of the endoprosthesis and being based on a comparison between DESIRED and ACTUAL states.
