Method and apparatus for determining the position of a body part

• US 5,807,252 A
• Filed: 10/22/1996
• Issued: 09/15/1998
• Est. Priority Date: 02/23/1995
• Status: Expired due to Fees

• Current Assignee: Aesculap AG (Lonza Group AG)
• Original Assignee: Aesculap AG (Lonza Group AG)
• Inventors: Schulz, Joachim, Muhling, Joachim, Hassfeld, Stefan, Lutze, Theodor
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): SHAW, SHAWNA JEANNINE
• Application Number:
  US08/735,032
• Time in Patent Office: 693 Days
• Field of Search: 128/653.1, 128/898, 128/664, 128/665, 606/130, 606/59, 606/65, 606/73, 606/104, 356/247, 378/205, 378/206, 600/407, 600/473, 600/476
• US Class Current: 600/407
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61B 2090/363 Use of fiducial points
• CPC Class Codes: A61B 2090/3945 Active visible markers, e.g. light emitting diodes
• CPC Class Codes: A61B 90/10 for stereotaxic surgery, e.g. frame-based stereotaxis
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61B 90/98 using electromagnetic means, e.g. transponders
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

To improve the reliability of a process for determining the position of a body part in which bone screws are screwed into the bone of the body part in question, each bone screw is provided with a radiation emitter or radiation receiver. A number of fixed receivers or emitters are used as appropriate to receive radiation from the bone screw transmitters or direct radiation towards the bone screw receivers. The radiation direction and/or radiation propagation time and/or radiation field strength or frequency is used to determine the position of each radiation emitter or receiver. A system for determining position based on this procedure and bone screws which can be used therefor are also disclosed.

Claims

1. An apparatus for determining the position of a body part, comprising:

(a) a unitary bone screw having a threaded end and an opposing driven end;

said threaded end being adapted to threadedly engage the body part to affix said bone screw thereto;

said bone screw comprising a bore hole which extends from said driven end and through an interior portion of said bone strew toward said threaded end; and

(b) a radiation device having an insert foot;

wherein;

said bore hole is sized to receive and engage said insert foot to secure said radiation device therein in a defined position with respect to said bone screw; and

said radiation device comprises one of a radiation emitter and a radiation receiver.

2. The apparatus of claim 1, wherein:

said insert foot is secured in said bore hole via a press fit.

3. The apparatus of claim 1, wherein:

said driven end comprises a polygonal insert opening which is adapted to receive a corresponding polygonal tool for driving said bone screw.

4. The apparatus of claim 1, wherein:

the radiation device is removeably receivable in said bore hole.

5. The apparatus of claim 1, wherein:

said bone screw is adapted to be used alone as a marking element.

6. The apparatus of claim 1, wherein:

said bone screw is sized to protrude only a few millimeters over a surface of the body part when affixed thereto.

7. The apparatus of claim 1, wherein:

said body part comprises a skull bone.

8. The apparatus of claim 1, wherein:

said radiation device comprises a light-emitting diode with a diode head;

an underside of said diode head is supported on an upper edge of said driven end when said insert foot is secured in said bore hole.

9. A system for determining the position of a body part comprising a plurality of the bone screws and respective radiation devices of claim 1, comprising:

a plurality of stationary receivers or emitters for communicating with the respective radiation devices;

a data processing device which determines the positions of the radiation devices based on characteristics of radiation which is communicated between the radiation devices and the stationary receivers or emitters;

said characteristics including at least one of direction, propagation time, strength and frequency of the radiation.

10. The system of claim 9, wherein:

at least three of said bone screws are used to determine the position of the body part;

said data processing device monitors the relative position of the radiation devices with respect to one another; and

in determining the position of the body part, said data processing device ignores the positional data of one of said radiation devices whose position has changed with respect to the position of the remaining radiation devices.

11. A method for determining the position of a body part, wherein bone screws are screwed into the bone of the body part, comprising the steps of:

providing a unitary bone screw with a bore hole extending from a head portion thereof toward a threaded portion thereof;

providing a radiation device with an insert foot;

inserting said insert foot into said bore hole to removably secure said insert foot therein;

arranging a plurality of stationary receivers or emitters for communicating with the radiation devices of the respective bone screws; and

determining the positions of the radiation devices based on characteristics of radiation which is communicated between the radiation devices and the stationary receivers or emitters;

said characteristics including at least one of direction, propagation time, strength and frequency of the radiation.

12. The method of claim 11, wherein:

said radiation device comprises a light-emitting diode.

13. The method of claim 11, wherein:

said bone screws are sized to protrude only a few millimeters over a surface of the body part when affixed thereto.

14. The method of claim 11, wherein at least three of said bone screws are used to determine the position of the body part, comprising the further steps of:

monitoring the relative position of the radiation devices with respect to one another; and

ignoring the positional data of one of said radiation devices whose position has changed with respect to the position of the remaining radiation devices when determining the position of the body part.

15. The method of claim 11, comprising the further step of:

removing the respective radiation device from at least one of the bone screws and using the at least one bone screw alone as a marking element.

16. The method of claim 11, wherein:

said body part comprises a skull bone.