Implantable joint prosthesis

• US 7,641,692 B2
• Filed: 08/08/2001
• Issued: 01/05/2010
• Est. Priority Date: 08/08/2000
• Status: Active Grant

• Current Assignee: Companion Spine LLC
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Conta, Robert, Gil, Carlos E., Bryan, Vincent, Kunzler, Alex, Clark, Charles R.
• Primary Examiner(s): Philogene; Pedro
• Application Number:
  US09/924,298
• Publication Number:
  US 20020128715A1
• Time in Patent Office: 3,072 Days
• Field of Search: 623/16.11, 623 1711- 1716
• US Class Current: 623/17.15
• CPC Class Codes: A61B 17/02 for holding wounds open; Tractors specula A61B1/32 ; drainage appliances for wounds A61M27/00
• CPC Class Codes: A61B 17/1664 for the hip
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1675 for the knee
• CPC Class Codes: A61B 17/1684 for the shoulder
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61B 2017/1602 Mills
• CPC Class Codes: A61B 2090/034 abutting on parts of the device itself
• CPC Class Codes: A61B 90/10 for stereotaxic surgery, e.g. frame-based stereotaxis
• CPC Class Codes: A61B 90/50 Supports for surgical instruments, e.g. articulated arms
• CPC Class Codes: A61F 2/30742 Bellows or hose-like seals; Sealing membranes A61B17/8808 takes precedence; sealing membranes for retaining bone substitute A61F2/2846
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30474 using an intermediate sleeve interposed between both prosthetic parts to be coupled
• CPC Class Codes: A61F 2002/30495 using a locking ring
• CPC Class Codes: A61F 2002/30528 : Means for limiting said movement
• CPC Class Codes: A61F 2002/30563 : having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30578 : having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30662 : with rotation-limiting means
• CPC Class Codes: A61F 2002/30673 : Lubricating means, e.g. synovial pocket
• CPC Class Codes: A61F 2002/30682 : Means for preventing migration of particles released by the joint, e.g. wear debris or cement particles
• CPC Class Codes: A61F 2002/30769 : madreporic
• CPC Class Codes: A61F 2002/30772 : Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/443 : having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00407 : Coating made of titanium or of Ti-based alloys

Abstract

The invention relates to a surgical implant that provides an artificial diarthroidal-like D joint, suitable for use in replacing any joint, but particularly suitable for use as an intervertebral disc endoprosthesis. The invention contains two rigid opposing shells, each having an outer surface adapted to engage the surfaces of the bones of a joint in such a way that the shells are immobilized by friction between their outer surfaces and the surfaces of the bone. These outer surfaces are sufficiently rough, while the inner surfaces of the shells are relatively smooth. The central body has a shape that cooperates with the shape of the inner surface of the shell so as to provide a range of motion similar to that provided by a healthy joint.

Claims

1. A surgical implant suitable for use in a joint between the surfaces of two bones, comprising:

two rigid opposing shells, each having

an outer surface adapted to engage the surfaces of the bones of a joint in such a way that movement of the shell relative to the bone surface is resisted by friction between the outer surface and the surface of the bone;

an inner surface that is smoother than the outer surface; and

an edge between the outer surface and the inner surface;

a deformable, resilient central body disposed between and slidable with respect to the inner surfaces of the shells, the central body comprising an outer surface, at least a portion of which has a shape that complements and articulates with the shape of the inner surfaces of both rigid opposing shells to allow the inner surfaces of the rigid opposing shells and the outer surface of the central body to move easily with respect to each other within a constrained range of motion, but to resist such movement outside the constrained range of motion, wherein an upper portion and a lower portion of the outer surface of the central body are harder than an interior region of the central body disposed between the upper and lower portions;

a flexible sheath extending between edges of the opposing shells, having an inner surface that, together with the inner surfaces of the rigid shells, defines a cavity containing the central body; and

a liquid lubricant, which occupies at least a portion of the cavity between the central body and the opposing shells.

2. The surgical implant of claim 1, wherein the edge of at least one of the rigid opposing shells comprises a tab extending axially away from the central body.

3. The surgical implant of claim 2, wherein the tab is adapted to releasably receive a tool for manipulating, inserting or removing the implant.

4. The surgical implant of claim 3, wherein the edges of both rigid opposing shells comprise a tab.

5. The surgical implant of claim 1, wherein the outer surface of each rigid opposing shell is cooled with a biocompatible porous coating.

6. The surgical implant of claim 5, wherein the porous coating comprises nonspherical sintered beads of a biocompatible metal or metal alloy.

7. The surgical implant of claim 6, wherein the rigid shell comprises a titanium alloy and wherein the porous coating comprises nonspherical sintered titanium beads.

8. A surgical implant suitable for use in a joint between the surfaces of two bones, comprising:

two rigid opposing shells, each having

an outer surface adapted to engage the surfaces of the bones of a joint in such a way that movement of the shell relative to the bone surface is resisted by friction between the outer surface and the surface of the bone;

an inner surface that is smoother than the outer surface; and

an edge between the outer surface and the inner surface;

wherein at least one of the rigid opposing shells further comprises a closable passage between its outer surface and its inner surface;

a deformable, resilient central body disposed between the inner surfaces of the shells comprising an outer surface, at least a portion of which has a shape that compliments and articulates with the shape of the inner surfaces of the rigid opposing shells to allow the inner surfaces of the rigid opposing shells and the outer surface of the central body to slidably move easily with respect to each other within a constrained range of motion, but to resist such movement outside the constrained range of motion; and

a lubricant positioned between the central body and the opposing shells;

wherein the closable passage is configured in a manner that permits the introduction of the lubricant into the implant between the central body and the opposing shells.

9. The surgical implant of claim 8, wherein the closable passage comprises a hole that is closable by insertion of a correspondingly sized plug.

10. A vertebral endoprosthesis, comprising:

an upper and a lower rigid, opposed, biocompatible shell, each comprising;

an outer, rough surface;

an inner, smooth concave surface; and

an edge between the surfaces;

wherein the inner smooth surface of at least one of the shells comprises a motion limiting device;

a deformable, resilient central body disposed between the inner, smooth concave surfaces of the upper and lower shells, comprising;

a smooth convex upper surface adjacent to the inner smooth concave surface of the upper shell and a smooth convex lower surface adjacent to the inner smooth concave surface of the lower shell, the upper and lower surfaces being harder than an interior region of the central body disposed between the upper and lower surfaces; and

a motion limiting device disposed on at least one of the smooth convex upper and lower surfaces adapted to contact the motion limiting device of the inner surface and limit the relative motion of the shell with respect to the central body; and

an elastic sheath disposed between the upper and lower shells and external to the central body, comprising an inner surface, an outer surface, an upper edge attached to the upper shell, and a lower edge attached to the lower shell;

wherein the inner surface of the sheath and the inner surfaces of the shells define an enclosed cavity receiving the central body; and

a lubricant disposed within the enclosed cavity surrounding the central body.

11. The vertebral endoprosthesis of claim 10, wherein the motion limiting device on the shell comprises a first ridge disposed on the inner surface of the shell, and the motion limiting device on the central body comprises a shoulder disposed on the surface of the central body.

12. The vertebral endoprosthesis of claim 11, wherein the first ridge comprises an axial extension of at least a portion of the edge of the shell toward the central body, and circumscribes the area of the inner surface that can contact the smooth convex surface of the central body.

13. The vertebral endoprosthesis of claim 11, wherein the shoulder circumscribes the convex surface of the central body.

14. The vertebral endoprosthesis of claim 10, wherein the outer surface of the shell is convex.

15. The vertebral endoprosthesis of claim 10, wherein the outer surface of the shell comprises a porous biocompatible coating.

16. The vertebral endoprosthesis of claim 15, wherein the porous biocompatible coating comprises nonspherical sintered beads of a biocompatible metal.

17. The vertebral endoprosthesis of claim 10, wherein the edge of at least one of the shells comprises a circumferential groove adapted to be overlapped by a sheath and to receive a retaining ring securing the sheath to the shell.

18. The vertebral endoprosthesis of claim 17, further comprising a retaining ring disposed in the circumferential groove, and compressing the edge of the sheath into the groove.

19. The vertebral endoprosthesis of claim 18, wherein the retaining ring comprises a wire or filament of biocompatible material, formed into a ring.

20. The vertebral endoprosthesis of claim 19, wherein the ends of the ring are laser welded.

21. The vertebral endoprosthesis of claim 10, wherein the edge of at least one of the shells comprises an tab extending axially away from the central body.

22. The vertebral endoprosthesis of claim 21, wherein the tab is adapted to releasably engage a tool for manipulating or inserting the endoprosthesis.

23. The vertebral endoprosthesis of claim 22, wherein the tab comprises an opening to releasably receive a retaining prong of the tool.

24. The vertebral endoprosthesis of claim 10, wherein the inner surface of at least one shell comprises a post extending toward the central body, and wherein the outer surface of the central body comprises at least one opening adapted to receive the post.

25. The vertebral endoprosthesis of claim 10, wherein at least one of the shells further comprises a closable passage between its outer surface and its inner surface.

26. The vertebral endoprosthesis of claim 25, wherein the closable passage comprises a hole that is closable by insertion of a correspondingly sized plug.

27. The vertebral endoprosthesis of claim 26, wherein the hole and plug are threaded with complementary threads.

28. A vertebral endoprosthesis, comprising:

an upper and a lower rigid, opposed biocompatible concavo-convex shell, each comprising;

an outer, rough convex surface, comprising a porous coating of a biocompatible material;

an inner concave surface, comprising;

a smooth contact area; and

an axial post extending toward the opposing shell; and

an edge between the surfaces, comprising;

a circumferential groove adapted to receive a retaining ring;

a first ridge circumscribing the contact area of the inner concave surface and extending axially toward the opposing shell;

a tab extending axially away from the opposing shell, and comprising an opening adapted to releasably engage a tool for manipulating, inserting, or removing the endoprosthesis;

a closable passage between the outer surface and the inner surface of the shell;

a deformable, resilient central body disposed between the inner, smooth concave surfaces of the upper and lower shells, comprising;

smooth convex upper and lower surfaces complementary and adjacent to the smooth contact area of the inner surfaces of the respective upper and lower shells;

a shoulder circumscribing each of the smooth convex upper and lower surfaces and adapted to contact the first ridge of the adjacent shell and limit the relative motion of the shell with respect to the central body;

a laterally extending equatorial ridge disposed between the first ridge of the upper concavo-convex shell and the first ridge of the lower concavo-convex shell;

an opening in the upper and lower convex contact surfaces adapted to receive the axial post of the inner surface of each shell;

an elastic sheath disposed between the upper and lower shells and external to the central body, comprising an inner surface, an outer surface, an upper edge attached to the upper shell, and a lower edge attached to the lower shell, wherein the inner surface of the sheath and the inner surfaces of the shells define an enclosed cavity;

an upper retaining ring of a biocompatible material disposed in the circumferential groove in the upper concavo-convex shell and securing the upper edge of the elastic sheath to the shell and a lower retaining ring of a biocompatible material disposed in the circumferential groove of the lower concavo-convex shell and securing the lower edge of the sheath to the shell a plug of biocompatible material disposed in the closable passages between the outer surface and inner surface of at least one of the concavo-convex shells; and

a lubricant disposed within the implant cavity.

29. The vertebral endoprosthesis of claim 28, wherein a plug is disposed in the closable passage of each concavo-convex shell.

30. The endoprosthesis of claim 28 wherein the outer porous coating of biocompatible material is disposed to promote bony ingrowth.

31. The endoprosthesis of claim 28 wherein the outer porous coating of biocompatible material is formed by vacuum sintering.

32. The endoprosthesis of claim 28 wherein the outer porous coating is a titanium coating.

33. The implant of claim 32 wherein the outer porous, titanium coating meets ASTM F-67.

34. A bone joint implant comprising

two shells interconnected by a sleeve to form a cavity therein,

a central body having at least one indentation therein positioned within the cavity,

wherein at least one of the shells includes a retaining post that extends into the indentation and a lubricant within the cavity between the central body and the two shells;

wherein at least one of the shells includes an opening to allow introduction of the lubricant into the cavity, wherein the opening is sealed with a plug tool having a handle and a detachable integral plug associated therewith after introduction of the lubricant into the cavity.

35. The implant of claim 34 wherein the plug detaches from the tool when a predetermined torque has been reached during insertion of the plug into the opening.

36. A method of introducing the lubricant into a bone joint implant comprising two shells interconnected by a sleeve to form a cavity therein, and a central body having at least one indentation therein positioned within the cavity, wherein at least one of the shells includes a retaining post that extends into the indentation, and wherein both of the shells include an opening to allow introduction of a lubricant into the cavity, the method comprising:

(1) sealing one of the openings, (2) slightly compressing the implant to remove excess air, (3) injecting the lubricant into the unsealed opening, and (4) sealing the second opening.

37. The method of claim 36 wherein the openings in the shells are sealed using a seal plug tool having a segment designed to disengage at a predetermined torque.