Facet joint prosthesis

• US 7,896,903 B2
• Filed: 12/12/2006
• Issued: 03/01/2011
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: Facet-Link Inc.
• Original Assignee: DERU GmbH
• Inventors: Link, Helmut D.
• Primary Examiner(s): Robert; Eduardo C
• Assistant Examiner(s): HAMMOND, ELLEN CHRISTINA
• Application Number:
  US11/637,237
• Publication Number:
  US 20070149983A1
• Time in Patent Office: 1,540 Days
• Field of Search: 623/17.11, 606/247
• US Class Current: 606/247
• CPC Class Codes: A61F 2/4405 for apophyseal or facet joints, i.e. between adjacent spinous or transverse processes devices implanted between spinous or transverse processes A61B17/7062
• CPC Class Codes: A61F 2002/30125 elliptical or oval
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30364 Rotation about the common longitudinal axis
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30471 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2002/30476 locked by an additional locking mechanism
• CPC Class Codes: A61F 2002/3052 unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30601 telescopic
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30635 Cardan or gimbal joints
• CPC Class Codes: A61F 2002/30649 Ball-and-socket joints
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30883 dovetail-shaped
• CPC Class Codes: A61F 2002/30904 serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/449 comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2220/0091 : connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2230/0008 : elliptical or oval
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0007 : for adjusting length
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A prosthesis for facet joints of the spinal column includes a bearing piece and a guide rod. The bearing piece includes a pressure plate that is configured for resting on an articular surface of the vertebra and, on the opposite side, a bearing insert which has an articular surface configured for interacting with an articular surface of an adjacent vertebra. The guide rod is secured on the bearing piece by means of a pivot joint. The bearing forces are transmitted to the vertebra via the pressure plate. In this way, the guide rod can have a narrow configuration, such that a slit excavated in the vertebra for receiving the guide rod can also be made narrow to permit a simple and reliable implantation technique which at the same time is gentle on the bone substance.

Claims

1. A prosthesis for facet joints of the spinal column, comprising a first bearing piece, a retaining piece, a guide rod comprising an outer guide rod and an inner guide rod, and a locking device,

the inner guide rod configured to engage in a telescopic manner with the outer guide rod, the locking device configured to secure the inner and outer guide rods against moving apart, and

the first bearing piece comprising a first pressure plate configured to rest on a vertebra and, on a side opposite to the first pressure plate, a first bearing shell which has an articular surface configured to interact with an articular surface of a vertebra adjacent to the vertebra on which the first pressure plate rests,

wherein a pivot joint is provided to secure the guide rod on the first bearing piece.

2. The prosthesis of claim 1, wherein the pivot joint is a cardan joint.

3. The prosthesis of claim 1, wherein a second bearing piece comprising a second pressure plate and a second bearing shell is arranged at another end of the guide rod.

4. The prosthesis of claim 3, wherein one of the first and second bearing pieces has a contour with an oval envelope, and the other of the first and second bearing pieces has a contour with a rectangular envelope.

5. The prosthesis of claim 3, wherein at least one of the first and second bearing pieces has a screw opening in its articular surface and is connected in a rotationally fixed manner to the inner guide rod.

6. The prosthesis of claim 3, wherein a thickened part is formed at the another end of the guide rod.

7. The prosthesis of claim 6, wherein the thickened part has a curvature on its side directed toward the first bearing piece.

8. The prosthesis of claim 7, wherein the curvature has a rotationally symmetrical design.

9. The prosthesis claim 6, 7 or 8, wherein the thickened part has a spheroid design.

10. The prosthesis of claim 3, wherein the second pressure plate is provided with a coating that promotes bone growth.

11. The prosthesis of claim 3, wherein the second bearing shell has an articular surface with a convex curvature.

12. The prosthesis of claim 1, wherein the first bearing piece comprising the first pressure plate and the first bearing shell are made in one piece.

13. The prosthesis of claim 1, wherein the guide rod is adapted for insertion into a slit between articular surfaces of the vertebra.

14. The prosthesis of claim 13, wherein the guide rod has a non-circular cross section whose greatest width is greater than the width of the slit.

15. The prosthesis of claim 14, wherein the interacting articular surface on the adjacent vertebra has a complementary curvature.

16. The prosthesis of claim 1 or 3, further comprising a radially protruding serration along the guide rod.

17. The prosthesis of claim 1, further comprising a toothing arrangement provided on the first pressure plate and adapted to engage in the vertebra.

18. The prosthesis of claim 1, wherein the first pressure plate is provided with a coating that promotes bone growth.

19. The prosthesis of claim 18, wherein the coating comprises hydroxyapatite.

20. The prosthesis of claim 1, wherein the first bearing shell has an articular surface with a convex curvature.

21. A prosthesis set comprising at least one prosthesis of claim 1 or 3, and including at least one prosthesis with two bearing pieces and at least one prosthesis with one bearing piece.

22. The prosthesis of claim 1, wherein the locking device comprises catch elements.

23. The prosthesis of claim 1, wherein the locking device comprises a self-locking screw connection.