Patent ID: 8444645

Claim:
A method for computer assisted localization of first and second distal locking holes in a distal end section of an implanted intramedullary nail having a nail axis and a nail tip, the method comprising the steps of: entering at least a nail diameter and a diameter of the first and second distal locking holes of the intramedullary nail in a data store of a computer; positioning an X-ray device with an optical axis with regard to the distal end section of the intramedullary nail irrespectively to the orientation of the distal locking holes whereby said optical axis is oriented essentially perpendicular to the nail axis; acquiring one single image of the distal end section of said intramedullary nail by means of the X-ray device; calculating the positions of the distal locking holes using the computer, the computer being programmed to automatically determine the position of the nail tip, the center of the first distal locking hole and the center of the second distal locking hole on the nail axis in the one single image, calculate a direction of the nail axis in a plane defined through the nail tip, at least one of the centers of the first and second distal locking holes, and a focal point of the X-ray device, and calculate the positions of the first and second hole axes of the first and second distal locking holes, respectively, with respect to a three-dimensional coordinate system defined by a dynamic reference base fixedly connected with the intramedullary nail or with a bone in which the intramedullary nail is implanted; and controlling a roboter provided with a drill bit having a drill axis using the computer whereby the drill axis of the drill bit is adjusted to align sequentially with each of the first and second hole axes of the first and second distal locking holes respectively as calculated in the calculating step and whereby the roboter guides the drill bit to drill separate holes in the bone for the insertion of locking screws in the first and second distal locking holes respectively.