Abstract: The invention relates to a surgical instrument comprising a handle portion or mounting portion and a functional portion and/or tip, wherein a display device is provided on the instrument and includes or enables displays which serve to assist in image-guided and/or navigation-assisted surgery. It also relates to a method for navigating a surgical instrument, wherein its position is determined and tracked by means of a medical tracking system and the position data is processed within the framework of medical navigation by means of a medical navigation system, wherein displays for navigation assistance and/or for assisting in image-guided surgery are provided on the instrument or on an element which is positionally assigned to the instrument or fastened to the instrument.

Abstract: A device for determining the aperture angle of a joint includes a detection device for detecting positions of joint components and/or positions of structures connected to or to be connected to the joint and a computational unit for ascertaining the aperture angle of the joint based on the detected positions.

Abstract: A data processing method for planning a medical treatment comprising following steps performed by a computer: acquiring reference patient data describing medical information on at least one reference patient including information on progression of the medical constitution of the at least one reference patient; acquiring current patient data describing medical information on a current patient; determining information on the progression of the medical constitution of the current patient based on the reference patient data and the current patient data.