Instrument for image guided applications

1. A trackable medical instrument for use in a computer assisted image guided surgery system having a digitizer for tracking the position of the instrument in three dimensional space and a display providing an indication of the position of the instrument with respect to images of a body part taken preoperatively, the instrument comprising:

a) a guide member having a tracking device mounted thereon for being tracked by the digitizer;

b) a proximal shaft attached to the guide member, the proximal shaft having a longitudinal axis and a proximal end portion and a distal end portion, the proximal shaft being non-rotatable with respect to the guide member while being fixable to the guide member in a direction of the longitudinal axis;

c) a drive handle extending from the distal end portion of the proximal shaft for imparting rotary motion, the drive handle having a proximal end portion and a distal end portion and being rotatable about the distal end portion of the proximal shaft while being fixed with respect to the guide member in a direction of the longitudinal axis;

d) an instrument tip extending from the distal end portion of the drive handle; wherein the instrument tip rotates relative to the guide member while being fixable axially relative to the guide member,

wherein the drive handle imparts rotary motion to the instrument tip.

2. The instrument of claim 1 wherein the guide member comprises a post, wherein the tracking device is mounted upon the post.

3. The instrument of claim 2 wherein the guide member further comprises a bushing, wherein the post is connected to the bushing.

4. The instrument of claim 3 wherein the bushing is attached to the proximal end portion of the proximal shaft.

5. The instrument of claim 3 wherein the bushing is replaceably attached to the proximal end portion of the proximal shaft.

6. The instrument of claim 1 wherein the proximal shaft has a second handle formed thereon.

7. The instrument of claim 6 wherein the second handle is located between the guide member and the drive handle.

8. The instrument of claim 7 wherein the second handle extends in a direction transverse to the proximal shaft.

9. The instrument of claim 7 wherein the second handle extends in a direction parallel to the proximal shaft.

10. The instrument of claim 7 wherein the proximal shaft is offset from a longitudinal axis of the drive handle.

11. The instrument of claim 10 wherein the proximal shaft further comprises a hand attachment feature.

12. The instrument of claim 10 wherein the hand attachment feature is selected from the group consisting of a c-clip and a securement belt.

13. The instrument of claim 1 wherein the proximal portion of the drive handle includes a sleeve having a bore.

14. The instrument of claim 13 wherein the distal portion of the proximal shaft is inserted in the bore of the sleeve of the proximal portion of the drive handle.

15. The instrument of claim 1 wherein the distal portion of the drive handle further comprises a ratchet mechanism.

16. The instrument of claim 1 wherein the distal portion of the drive handle further comprises a modular attachment mechanism.

17. The instrument of claim 1 wherein the instrument tip is selected from the group consisting of a probe, a drill, and a tap.

18. A method of using a medical instrument in a computer assisted image guided surgery system having a digitizer for tracking the position of the instrument in three dimensional space and a display providing an indication of the position of the instrument with respect to images of a body part taken preoperatively, the method comprising the steps of:

a) selecting an instrument of claim 1 ,

b) contacting the instrument tip to an implant disposed in the body part.

19. A method of using a medical instrument in a computer assisted image guided surgery system having a digitizer for tracking the position of the instrument in three dimensional space and a display providing an indication of the position of the instrument with respect to images of a body part taken preoperatively, the method comprising the steps of:

a) selecting an instrument of claim 1 ,

b) contacting the instrument tip to the body part.

20. The method of claim 19 wherein the body part is a vertebra.

21. The instrument of claim 1 wherein the drive handle is between the instrument tip and the proximal shaft.