Abstract: In order to be able to ascertain the position of the bone in the body without complicated procedures in a process for the preoperative determination of the positioning data of endoprosthetic parts of a central joint relative to the bones forming the central joint, a respective outer articular point is determined by way of movement of the bones about a respective outer joint which is located at the end of the two bones facing away from the central joint. An articular point is determined for each of the two bones in the area of the central joint, and a direction characteristic for each of these bones is determined by way of a straight-line connection of the two articular points obtained in this manner for the two bones. The orientation of the endoprosthetic parts relative to this characteristic direction is then determined. Apparatus for carrying out the process is also provided.

Abstract: A method for determining the center of rotation of a bone in a revolute joint, for example, a femur in the iliac bone, including the steps of displacing said bone, locating several ones of its positions, and memorizing them, imposing a constraint to the displacement of said center of rotation without for all this immobilizing it, and searching a point linked to the referential of said bone for which an optimization criterion taking into account said constraint is reached.

Abstract: The invention concerns a system for determining the ideal theoretical position of a knee prosthesis comprising, for determining the position of a tibial prosthesis, means for: determining the shape of the tibia proximal part and its position relative to the centre of the ankle joint; determining a high point of the tibial plateau; calculating the position of the ankle, the orientation and the size relative to the tibia of the tibial prosthesis and the section plane corresponding to the tibial prosthesis taking into account the following parameters: the perpendicular to the section plane passing through the centre of the prosthesis also passes through the centre of the ankle joint; the section plane is at a distance from said high point equal to the height of the prosthesis to be fixed; the large end of the prosthesis is centred on the large end of the tibia cross-section in the section plane; the front edge of the small end of the prosthesis is at a predetermined distance from the small end of the tibia cross

Abstract: In order to be able to ascertain the position of the bone in the body without complicated procedures in a process for the preoperative determination of the positioning data of endoprosthetic parts of a central joint relative to the bones forming the central joint, a respective outer articular point is determined by way or movement of the bones about a respective outer joint which is located at the end of the two bones facing away from the central joint. An articular point is determined for each of the two bones in the area of the central joint, and a direction characteristic for each of these bones is determined by way of a straight-line connection of the two articular points obtained in this manner for the two bones. The orientation of the endoprosthetic parts relative to this characteristic direction is then determined. Apparatus for carrying out the process is also provided.

Abstract: The present invention relates to a method for readjusting the reference frame of a three-dimensional image of a patient on the reference frame of this patient placed in a operating chamber, including the step of placing on the patient a device having a predetermined position relation with the patient's anatomic structure. The present invention also relates to various devices applicable to a wide series of patients and having a predetermined relation with the patient's anatomic structure. Thus, a device applicable to a patient's head includes an element including three anatomic bearings to bear against the forehead and the root of the nose, and a holding bar coupled to the patient's ears.

Abstract: In order to be able to ascertain the position of the bone in the body without complicated procedures in a process for the preoperative determination of the positioning data of endoprosthetic parts of a central joint relative to the bones forming the central joint, a respective outer articular point is determined by way of movement of the bones about a respective outer joint which is located at the end of the two bones facing away from the central joint. An articular point is determined for each of the two bones in the area of the central joint, and a direction characteristic for each of these bones is determined by way of a straight-line connection of the two articular points obtained in this manner for the two bones. The orientation of the endoprosthetic parts relative to this characteristic direction is then determined. Apparatus for carrying out the process is also provided.

Abstract: In order to be able to ascertain the position of the bone in the body without complicated procedures in a process for the preoperative determination of the positioning data of endoprosthetic parts of a central joint relative to the bones forming the central joint, a respective outer articular point is determined by way of movement of the bones about a respective outer joint which is located at the end of the two bones facing away from the central joint. An articular point is determined for each of the two bones in the area of the central joint, and a direction characteristic for each of these bones is determined by way of a straight-line connection of the two articular points obtained in this manner for the two bones. The orientation of the endoprosthetic parts relative to this characteristic direction is then determined. Apparatus for carrying out the process is also provided.

Abstract: A system for simulating an orthognatic surgery action, including an X-ray scanner, a device of three-dimensional localization of relative positions of dental castings, each associated with a unit locatable in position and orientation by the localization device, and an image processing system for combining tomographic images provided by the scanner with positioning data provided by the localization device to obtain three-dimensional images.

Abstract: A method for determining the position of a point F1 of a femur with respect to a point T1 of a tibia such that the distance between F1 and T1 is substantially invariant. The method uses a three-dimensional locating system including triplets of emitting elements especially including a pointer that can be located by the system, and includes the steps of linking a first triplet to the first organ; pointing with the pointer at the position of point T1 and locating this position with respect to the position of the first triplet; pointing with the pointer at the positions of an assembly of second points that are positioned within an area of the femur where the invariant point is likely to be found; calculating the distances separating point from each of points Fi; moving the tibia with respect to the femur add calculating the variations in the distances; and selecting point F1 for which the distance is invariant.

Abstract: A method for determining the position of a patient's organ with respect to at least two imaging devices includes a step of making at least one three-dimensional first image of an organ of a patient giving a first coordinate system and of a surface of the organ or skin region using a first imaging device without fixing any mark to the patient, placing the patient in an operation site having a second coordinate system and determining a first position of a second imaging device with respect to the second coordinate system of the operation site. In addition, the method includes the steps of making a second image with the second imaging device, matching the first and second images and providing a third device having a third coordinate system. The third device is positioned with respect to the second image of the second device which thereby positions the third device with respect to the first image of the first imaging device.

Abstract: A robot for guiding movements has its power provided by an operator who handles a tool integral with the robot. Like a conventional robot, the guiding robot has several axes respectively associated with rotation sensors that are connected to a computer system memorizing a path to be followed. When the operator moves the tool beyond the stored path, blocking devices, controlled by the computer system and replacing the robot's motors, prevent the tool from continuing to depart from the path. Thus, at any time, the operator can move the tool within the stored path only. The blocking devices are passive, that is, they are such that they can only resist to a movement but cannot generate a movement, which prevents the occurrence of any uncontrolled movement.