Arrangement for ascertaining function-determining geometric parameters of a joint of a
vertebrate, especially a hip or
shoulder joint of a
human being, in preparation for the installation of a
joint replacement implant, especially a hip or shoulder socket or an associated stem
implant, by means of an optical coordinate-measuring procedure, having a stereocamera or stereocamera arrangement for the spatial recording of optical
transducer signals, a mobile multipoint
transducer which is in the form of a movable sensor for sensing bony references in the joint region in order to determine the coordinates thereof, at least one bone-fixed multipoint
transducer which is configured for rigid attachment, especially screwed or clamped attachment, (in a region sufficiently distant from the joint) to an extremity originating from the joint, especially close to the proximal end of a
femur or a
humerus, an interactive sequence controller for controlling the sequential registration and storage of a set of
measurement point coordinates supplied by the mobile multipoint transducer and sets of
measurement point coordinates recorded in a first plurality of positions of the bone-fixed multipoint transducer in a plurality of rotated positions of the extremity and their subsequent
processing in accordance with a previously stored
processing sequence, an evaluation unit for evaluating the sets of
measurement point coordinates supplied by the multipoint transducers and recorded by the camera arrangement for the purpose of determining the geometric parameters, which comprises means for determining the transversal, vertical and sagittal body axes as well as means for carrying out an iterative procedure, especially an adjustment calculation in accordance with the
least squares method, to determine the coordinates of the center of rotation of the joint, and an output unit, which is connected to the sequence controller and to the evaluation unit, for issuing manipulation proposals to an operating surgeon in accordance with the predetermined process sequence and in dependence upon the results of the determination of the geometric parameters, and for displaying the results of the evaluation.