Abstract: A marker for a navigation system for determining the spatial position (e.g., of a surgical instrument), said marker including a retroreflective ball (12). A retroreflective surface (13) of the ball (12) is protected by a dimensionally stable, translucent or transparent shell (14) in such a way that the reflected image remains essentially uninfluenced in terms of contour and the position of the centre of gravity.

Abstract: A marker for a navigation system for determining the spatial position (e.g., of a surgical instrument), said marker including a retroreflective ball (12). A retroreflective surface (13) of the ball (12) is protected by a dimensionally stable, translucent or transparent shell (14) in such a way that the reflected image remains essentially uninfluenced in terms of contour and the position of the centre of gravity.

Abstract: A method of finding the position of a mechanical axis running in the longitudinal direction through a limb that is rotatably supported by its first end in a center of rotation that is not fixed and is not accessible for the mechanical determination of coordinates, by means of an optical coordinate-measurement device with an indicator to detect measurement-point coordinates in one rotational position of the limb such that, for each rotational position, a multi-point indicator rigidly attached near the second end of the limb signals several measurement-point coordinates, and, from the sets of measurement-point coordinates detected in a plurality of rotational positions, at least one group is selected that can be assigned to the same site of the center of rotation, and the measurement-point-coordinate sets assigned to this site of the center of rotation are used to calculate the mechanical axis.

Abstract: A clamp for attaching surgical operating aids has at least two clamp members arranged so as to be movable relative to one another and a securing element for fixing the clamp members in at least one locked position. The clamp members have a connecting mechanism that allow the clamp members to be attached to a separate setting element actuatable for transmitting a setting force onto the clamp. A setting element, such as tongs, releasably connects to the clamp, and has a connecting mechanism connectible to the connecting mechanism of the clamp and has a spacing and/or aligning mechanism. A clamp and a setting element that is releasably joined to the clamp provide an arrangement for attachment of surgical operating aids to a bone during a surgical intervention, such as during a joint replacement surgery.

Abstract: A method of finding the position of a mechanical axis running in the longitudinal direction through a limb that is rotatably supported by its first end in a center of rotation that is not fixed and is not accessible for the mechanical determination of coordinates, by means of an optical coordinate-measurement device with an indicator to detect measurement-point coordinates in one rotational position of the limb such that, for each rotational position, a multi-point indicator rigidly attached near the second end of the limb signals several measurement-point coordinates, and, from the sets of measurement-point coordinates detected in a plurality of rotational positions, at least one group is selected that can be assigned to the same site of the center of rotation, and the measurement-point-coordinate sets assigned to this site of the center of rotation are used to calculate the mechanical axis.

Abstract: A method of finding the position of a mechanical axis running in the longitudinal direction through a limb that is rotatably supported by its first end in a center of rotation that is not fixed and is not accessible for the mechanical determination of coordinates, by means of an optical coordinate-measurement device with an indicator to detect measurement-point coordinates in one rotational position of the limb, such that, for each rotational position, a multi-point indicator rigidly attached near the second end of the limb signals several measurement-point coordinates, and, from the sets of measurement-point coordinates detected in a plurality of rotational positions, at least one group is selected that can be assigned to the same site of the center of rotation, and the measurement-point-coordinate sets assigned to this site of the center of rotation are used to calculate the mechanical axis.

Abstract: A knee-joint prosthesis with a tibial part having a flat tibial bearing surface, with a bearing body that can be shifted thereon in the anterior-posterior direction and includes two concave bearing shells within which a femoral joint part can be movably seated, and with a rotational guide that permits rotation of the bearing body on the tibial bearing surface about an axis of rotation perpendicular to said surface. The rotation guide includes a steering rod that is seated at the bearing body so as to be pivotable relative thereto and at the tibial part is guided in the medial/lateral direction and/or rotationally guided.

Abstract: Method of finding the position of a mechanical axis (5) running in the longitudinal direction through a limb (1), in particular a femur, that is rotatably supported by its first end in a center of rotation (3) that is not fixed and in particular is not accessible for the mechanical determination of coordinates, in particular the hip socket, by means of an optical coordinate-measurement device (7, 8, 9) with an indicator to detect measurement-point coordinates in one rotational position of the limb (1), such that for each rotational position a multi-point indicator (8) rigidly attached near the second end of the limb (1) signals several measurement-point coordinates, and from the sets of measurement-point coordinates detected in a plurality of rotational positions at least one group is selected that can be assigned to the same site of the center of rotation, and the measurement-point-coordinate sets assigned to this site of the center of rotation are used to calculate the mechanical axis (5).

Abstract: For indirect determination of point positions and/or of surface orientations in point positions a laser tracker (1) adapted for relative and absolute distance measurement is used. A measuring device is utilised, the device including a target point (retro-reflector 3) for the laser beam of the tracker, the target point being movable along a trajectory path (A). The position and orientation of the trajectory path (A) of the target point is precisely defined relative to a reference point (R) of the device (2) and the device (2) is positionable in the region of a point position (P) to be determined such that the position of the reference point (R) relative to the point position (P) to be determined is precisely defined. For determining the point position (P), the device (2) is positioned in the region of the point position (P) to be determined, the target point is positioned in a starting position (3.1) and is detected by the tracker (1) by direction determination and absolute distance measurement.

Abstract: The optical aiming device may be mounted on firearms. It comprises a light-collecting rod (8) consisting of a phosphor material to illuminate a central circular spot (22) of an aiming mark (6). Such illumination passes through a truncated hollow cone (25) and is used for good ambient light conditions. For poor ambient light four tritium luminous cells (18, 19, 20, 21) are mounted around the truncated hollow cone (25). Each tritrium cell illuminates one radial line component (23) of the aiming mark (6) via the external mirrored lateral area of cone (25). To adapt the brightness of the aiming mark to the brightness of the target the tritium luminous cells (18, 19, 20, 21) may be shifted on a circle around cone (25) with respect to the line components (23) of aiming mark (6).

Abstract: A restitution instrument for measuring and evaluating picture plates. The instrument includes a mounting stage for mounting the plate. The stage has two edges forming a 90.degree. angle. A carriage means attached to the stage, is used for guiding the stage free of rotation in directions parallel to the edges, i.e., X and Y directions. A drive means is attached to the stage for driving the stage in the X and Y directions along the carriage means. The drive means includes a drive unit slidably mounted to each of the edges and a drive member driven by a drive motor. The member is mounted at 90.degree. to the edge. The member drives the stage in a line of motion perpendicular to the edge. The lines of motion of each of the members intersects at a fixed point whose projection on to the stage falls upon an image point under observation. The drive means includes a measuring means for determining the distance the stage is driven in each of the X and Y directions.