Guide wire navigation

#The present invention relates to guide wires and, more particularly, to a system and method for navigating a guide wire.

#Guide wires typically are used, for example, to “thread” bone fragments after a bone fracture and before introduction of an intramedullary pin. The guide wire can be a long, flexible and relatively thin rod with a proximal end at which the guide wire can be gripped and with a distal end that can be advanced through the bone channel or the channels of bone fragments, in order to thread the fragments.

#In this activity, it would be advantageous if the location of the distal end of the guide wire were known at any time. It would then be possible to ascertain whether said distal end has been advanced far enough to guarantee sufficient threading.

#The forgoing and other embodiments of the invention are hereinafter discussed with reference to the drawings.

#FIG. 1 is a schematic diagram showing an exemplary mapping of the surroundings of a guide wire navigated in accordance with the invention.

#FIG. 2 is a schematic representation of the guide wire for the purpose of theoretical discussion.

#Referring to FIG. 1, there is shown a guide wire 1 that includes a grip 1 a at its proximal end 2. A first navigation reference device 4 is attached to the grip la of the guide wire 1, and a second navigation reference device 5 is arranged on a bone 6. The navigation reference devices 4 and 5 can be positionally detected by a navigation and tracking system 10, which is only represented schematically. Although not shown, the navigation and tracking system 10 can include tracking cameras, a data processing facility and an image output and data input means, for example, or any other component/system used in navigation and tracking systems. The system 10 can be a conventional optical navigation and tracking system, for example, and the reference devices 4 and 5 can be formed as reference stars that reflect (passive) or emit (active) invisible (e.g., infrared) light. The navigation system 10 can be one such as is described as a “Neuro-navigation System” in DE 196 39 615 A1, for example.

#The navigation and tracking system 10 can identify the position and orientation of the proximal end 2 (r2, dr2/dl) of the guide wire 1. The position and orientation of the bone 6 also can be identified and, in particular, the orientation of the inner tubular channel (not shown) in the bone 6. What is sought is the vector r3 (i.e., the position of the distal end 3 of the guide wire 1).

#Using the steps described herein, the insertion depth of the distal end 3 can be identified under certain conditions. To this end, and contrary to all previous approaches, optical navigation, as opposed to magnetic navigation, is used. The grip 1a of the guide wire 1 (distal end 2) can be easily tracked and, because the bone orientation is already known via reference device 5, the orientation of the axis of the tubular bone into which the guide wire 1 is inserted is known. This allows the insertion depth of the guide wire 1 to be virtually displayed on a computer monitor.