Locking nail and stereotaxic apparatus therefor

• US 20050080335A1
• Filed: 09/21/2004
• Published: 04/14/2005
• Est. Priority Date: 09/24/2003
• Status: Active Grant

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker Trauma GmbH (Stryker Corporation)
• Inventors: Fullgraf, Rene, Simon, Bernd
• Granted Patent: US 7,686,818 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• CPC Class Codes: A61B 17/1707 using electromagnetic effects, e.g. with magnet and external sensors
• CPC Class Codes: A61B 17/1725 for applying transverse screws or pins through intramedullary nails or pins
• CPC Class Codes: A61B 17/72 Intramedullary pins, nails or other devices A61B17/744 takes precedence
• CPC Class Codes: A61B 2090/397 electromagnetic other than visible, e.g. microwave

Abstract

A stereotaxic apparatus for a locking nail which has two oscillating circuits which are disposed along the longitudinal direction of the locking nail. The apparatus has a guide sleeve to place a drill and/or bone screw which, when the stereotaxic apparatus is in an oriented condition, points to a cross-bore in the locking nail. The guide sleeve has three or more oscillating circuits arranged in a first plane that are equidistant each from a first center located in the plane; three or more oscillating circuits are arranged in a second plane extending in parallel with said first plane that are equidistant each from a second center located in said second plane. The first and second planes are arranged towards each other such that a face normal to one of said planes extends through the first and second centers. A pair of oscillating circuits are arranged at a distance from a straight line extending through the centers and the interconnecting straight line of which, in the aligned condition with the locking nail, is substantially perpendicular to the longitudinal direction of the locking nail.

Claims

1. A stereotaxic apparatus for a locking nail comprising two oscillating circuits which are disposed along the longitudinal direction of the locking nail, the apparatus having a guide sleeve to place a drill and/or bone screw which, when the stereotaxic apparatus is in an oriented condition, points to a cross-bore in the locking nail wherein the stereotactic apparatus has:

three or more oscillating circuits are arranged in a first plane that are equidistant each from a first center located in said plane;

three or more oscillating circuits are arranged in a second plane extending in parallel with said first plane that are equidistant each from a second center located in said second plane;

wherein said first and second planes are arranged towards each other such that a face normal to one of the planes extends through said first and second centers; and

at least two oscillating circuits are arranged at a distance from a straight line extending through said centers and the interconnecting straight line of which, in the condition aligned with said locking nail, is substantially perpendicular to the longitudinal direction of said locking nail.

2. The stereotaxic apparatus as set forth in claim 1 wherein four oscillating circuits are arranged at a rectangle towards each other in said first plane.

3. The stereotaxic apparatus as set forth in claim 2 wherein said oscillating circuits are arranged at a square towards each other.

4. The stereotaxic apparatus as set forth in claim 1 wherein said oscillating circuits are arranged as a rectangle in said second plane.

5. The stereotaxic apparatus as set forth in claim 4 wherein said oscillating circuits are arranged at a square towards each other.

6. The stereotaxic apparatus as set forth in claim 1 wherein said oscillating circuits are arranged in congruence in said first and second planes.

7. The stereotaxic apparatus as set forth in claim 1 wherein said oscillating circuits are connected to an internal evaluation unit.

8. The stereotaxic apparatus as set forth in claim 7 wherein said evaluation unit has filtration and amplification units which are each tuned to a working frequency of said oscillating circuits.

9. The stereotaxic apparatus as set forth in claim 8 wherein said amplification unit has an amplifier and a bandpass filter with amplification substantially taking place by an active bandpass filter.

10. The stereotaxic apparatus as set forth in claim 9 wherein the amplified and filtered measuring values of the oscillating circuits are rectified and are digitized via an A/D converter.

11. The stereotaxic apparatus as set forth in claim 10 wherein the digitized data is routed, via a serial interface, onto a computer for an evaluation.

12. The stereotaxic apparatus as set forth in claim 11 wherein the evaluated data are graphically plotted on the computer.

13. The stereotaxic apparatus as set forth in claim 1 wherein said oscillating circuits are connected to an external evaluation unit.

14. The stereotaxic apparatus as set forth in claim 13 wherein said evaluation unit has filtration and amplification units which are each tuned to a working frequency of said oscillating circuits.

15. The stereotaxic apparatus as set forth in claim 14 wherein said amplification unit has an amplifier and a bandpass filter with amplification substantially taking place by an active bandpass filter.

16. The stereotaxic apparatus as set forth in claim 15 wherein the amplified and filtered measuring values of the oscillating circuits are rectified and are digitized via an A/D converter.

17. The stereotaxic apparatus as set forth in claim 16 wherein the digitized data is routed, via a serial interface, onto a computer for an evaluation.

18. The stereotaxic apparatus as set forth in claim 17 wherein the evaluated data are graphically plotted on the computer.

19. The stereotaxic apparatus as set forth in claim 1 wherein an additional excitation coil is provided which emits a HF pulse for an excitation of the oscillating circuits in the locking nail.

20. A locking nail comprising a hollow shank which has at least one cross-bore for the reception of a bone screw and a recess arranged in the area of the at least one cross-bore in which two oscillating circuits having different resonant frequencies are arranged in a series, the oscillating circuits being oriented in said recess such that the main direction of radiation of the electromagnetic fields produced extend in parallel to each other.

21. The stereotaxic apparatus as set forth in claim 20 wherein said recess radially faces outwardly in the shank wall and is sealed by a plastic compound.

22. The stereotaxic apparatus as set forth in claim 21 wherein at least one of said oscillating circuits is arranged around a cross-bore.

23. The stereotaxic apparatus as set forth in claim 20 wherein said oscillating circuits are operated by their resonant frequency.

24. A system for locating a bore in a medical implant comprising:

an implant having a bore and an oscillating circuit located on said implant in a known spatial relationship to said bore;

a guide sleeve having at least three oscillating circuits attached thereto located on a first plane and at least three oscillating circuits attached thereto located on a second plane oriented parallel to and spaced from said first plane along a central axis;

a pair of oscillating circuits attached to said guide sleeve and spaced on either side of an axis extending perpendicularly from said central axis; and

a stereotaxic sensing system for sensing the relative location of each of said oscillating circuits.

25. The system as set forth in claim 24 wherein the implant is a locking nail comprising a hollow shank which has at least one cross-bore for the reception of a bone screw and a recess arranged in the area of the at least one cross-bore in which two oscillating circuits having different resonant frequencies are arranged in a series, the oscillating circuits being oriented in said recess such that the main direction of radiation of the electromagnetic fields produced extend in parallel to each other.

26. The stereotaxic apparatus as set forth in claim 25 wherein at least one of said oscillating circuits is arranged around a cross-bore.