Implantable joint prosthesis
First Claim
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.
1 Assignment
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Accused Products
Abstract
The invention relates to a surgical implant that provides an artificial diarthroidal-like 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 that large frictional forces strongly resist any slippage between the outer surface and the bone surfaces in the joint. They may be convex, and when inserted into a milled concavity, are immediately mechanically stable. Desirably, the outer surfaces of the shells are adapted to allow for bony ingrowth, which further stabilizes the shells in place. The inner surfaces of the shells are relatively smooth, and adapted to slide easily across a portion of the outer surface of a central body disposed between the shells. 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. A flexible sheath extends between edges of the opposing shells. The inner surface of this sheath, together with the inner surfaces of the rigid shells, defines a cavity encasing the central body. At least a portion of this cavity is filled with a fluid lubricant, further decreasing the frictional force between inner surfaces of the shell and the surface of the central body.
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Citations
44 Claims
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1. A surgical implant suitable for use in a joint between the surfaces of two bones, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A vertebral endoprosthesis, comprising:
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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. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A vertebral endoprosthesis, comprising:
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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. - View Dependent Claims (42, 43, 44)
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Specification