Implantable joint prosthesis

Claim 2

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 the inner surfaces of the shells comprising an outer surface, at least a portion of which has a shape that complements and articulates with the shape of the inner surface of one or both rigid opposing shells to allow the inner surface of the rigid opposing shell 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.

Claim 3

2 . The surgical implant of claim 1 , further comprising: 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.

Claim 4

3 . The surgical implant of claim 2 , further comprising: a liquid lubricant, which occupies at least a portion of the cavity.

Claim 5

4 . The surgical implant of claim 1 , wherein the inner surface of at least one of the rigid opposing shells comprises a motion limiting device disposed thereon.

Claim 6

5 . The surgical implant of claim 4 , wherein the motion limiting device comprises a bead or ridge formed on the inner surface.

Claim 7

6 . The surgical implant of claim 5 , wherein the bead or ridge is located at the edge of the shell, and extends toward the central body.

Claim 8

7 . The surgical implant of claim 4 , wherein the surface of the central body comprises a motion limiting device disposed thereon, and which contacts the motion limiting device of the shell when the implant reaches the end of an acceptable range of motion.

Claim 9

8 . The surgical implant of claim 7 , wherein the motion limiting device on the central body retainer comprises a ridge that circumscribes the area of the inner surface of the shell that contacts the outer surface of the central body.

Claim 10

9 . The surgical implant of claim 4 , wherein the motion limiting device comprises a post extending toward the deformable resilient central body, and wherein the outer surface of the central body further comprises at least one opening adapted to receive the post.

Claim 11

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

Claim 12

11 . The surgical implant of claim 10 , wherein the tab is adapted to releasably receive a tool for manipulating, inserting or removing the implant.

Claim 13

12 . The surgical implant of claim 11 , wherein the edges of both rigid opposing shells comprise a tab.

Claim 14

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

Claim 15

14 . The surgical implant of claim 13 , wherein the porous coating comprises nonspherical sintered beads of a biocompatible metal or metal alloy.

Claim 16

15 . The surgical implant of claim 14 , wherein the rigid shell comprises a titanium alloy and wherein the porous coating comprises nonspherical sintered titanium beads.

Claim 17

16 . The surgical implant of claim 1 , wherein at least one of the rigid opposing shells further comprises a closable passage between its outer surface and its inner surface.

Claim 18

17 . The surgical implant of claim 16 , wherein the closable passage comprises a hole that is closable by insertion of a correspondingly sized plug.

Claim 19

18 . The surgical implant of claim 2 , wherein the edge between the outer surface and the inner surface of the rigid opposing shells comprises a circumferential groove adapted to receive a retaining ring.

Claim 20

19 . The surgical implant of claim 18 , wherein the sheath overlaps the circumferential groove and is held against the edge of the rigid opposing shells by the retaining ring.

Claim 21

20 . The surgical implant of claim 9 , wherein the implant is a vertebral endoprosthesis.

Claim 22

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

Claim 23

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

Claim 24

22 . The vertebral endoprosthesis of claim 21 , further comprising: 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.

Claim 25

23 . The vertebral endoprosthesis of claim 22 , further comprising a lubricant disposed within the enclosed cavity.

Claim 26

24 . The vertebral endoprosthesis of claim 21 , 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.

Claim 27

25 . The vertebral endoprosthesis of claim 24 , 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.

Claim 28

26 . The vertebral endoprosthesis of claim 24 , wherein the shoulder circumscribes the convex surface of the central body.

Claim 29

27 . The vertebral endoprosthesis of claim 21 , wherein the outer surface of the shell is convex.

Claim 30

28 . The vertebral endoprosthesis of claim 21 , wherein the outer surface of the shell comprises a porous biocompatible coating.

Claim 31

29 . The vertebral endoprosthesis of claim 28 , wherein the porous biocompatible coating comprises nonspherical sintered beads of a biocompatible metal.

Claim 32

30 . The vertebral endoprosthesis of claim 21 , wherein the edge of at least one of the shells comprises a circumferential groove adapted to be overlapped by the sheath and to receive a retaining ring securing the sheath to the shell.

Claim 33

31 . The vertebral endoprosthesis of claim 30 , further comprising a retaining ring disposed in the circumferential groove, and compressing the edge of the sheath into the groove.

Claim 34

32 . The vertebral endoprosthesis of claim 31 , wherein the retaining ring comprises a wire or filament of biocompatible material, formed into a ring.

Claim 35

33 . The vertebral endoprosthesis of claim 32 , wherein the ends of the ring are laser welded.

Claim 36

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

Claim 37

35 . The vertebral endoprosthesis of claim 34 , wherein the tab is adapted to releasably engage a tool for manipulating or inserting the endoprosthesis.

Claim 38

36 . The vertebral endoprosthesis of claim 35 , wherein the tab comprises an opening to releasably receive a retaining prong of the tool.

Claim 39

37 . The vertebral endoprosthesis of claim 21 , 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.

Claim 40

38 . The vertebral endoprosthesis of claim 21 , wherein at least one of the shells further comprises a closable passage between its outer surface and its inner surface.

Claim 41

39 . The vertebral endoprosthesis of claim 38 , wherein the closable passage comprises a hole that is closable by insertion of a correspondingly sized plug.

Claim 42

40 . The vertebral endoprosthesis of claim 39 , wherein the hole and plug are threaded with complementary threads.

Claim 43

41 . 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.

Claim 44

41 . 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.

Claim 45

42 . The vertebral endoprosthesis of claim 41 , further comprising: 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.

Claim 46

43 . The vertebral endoprosthesis of claim 42 , further comprising: a lubricant disposed within the implant cavity.

Claim 47

44 . The vertebral endoprosthesis of claim 43 , wherein a plug is disposed in the closable passage of each concavo-convex shell.