Shoulder joint implant
AssigneeAscension Orthopedics, Inc.
InventorsJerome J. Klawitter, Monti R. Gourley
Life of this patent
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Abstract
A prosthetic implant comprising a head having a spherical pyrocarbon shell (13,73) that is attached to a metal substructure (17,77) via an intermediate element (15,45,75). A subassembly of the intermediate element and the pyrocarbon shell may be connected to the metal substructure via a metal split ring (19) that resides partially in each of two facing grooves (33,35) or via interengaging elements (85,87,91) that are provided in two juxtaposed cylindrical surfaces. The design is such that compressive forces applied to the implant at its spherical articulating surface are transferred via compression through the pyrocarbon shell to the metal substructure.
Claims21
An implant for providing a replacement articulating surface for the head of one bone member of an orthopedic joint, which implant comprises:
- a pyrocarbon shell having an outer surface which is a section of a sphere, a concave interior surface and an open proximal base,
- a metal substructure having a convex distal surface and means at a proximal end thereof for securing the implant in a cavity formed at the end of a bone, and
- an intermediate element which is sufficiently flexible to allow its insertion axially into said open proximal base of said pyrocarbon shell and create an interference fit that prevents its withdrawal from this subassembly of shell and intermediate element,
- said element and said metal substructure having interengaging means which allows said metal substructure to be inserted fully into said subassembly but prevents its withdrawal therefrom, whereby forces at said joint are transferred compressively through said pyrocarbon shell to said convex surface of said metal substructure.
An implant for providing a replacement articulating surface for the head of one bone member of an orthopedic joint, which implant comprises:
- a pyrocarbon shell having an outer surface which is a section of a sphere, a concave interior surface and an open proximal base,
- a metal substructure having a convex distal surface, a proximal cylindrical surface section and means at a proximal end thereof for securing the implant in a cavity formed at the end of a bone, and
- an intermediate element which has a convex domed outer surface distal section, that substantially abuts said interior concave domed surface of said pyrocarbon shell, and has a proximal cylindrical interior surface section, and which is sufficiently flexible to allow its axial insertion into said open proximal base of said pyrocarbon shell and create an interference fit that prevents its withdrawal from this subassembly of shell and intermediate element,
- said metal substructure being mated with said intermediate element so that its cylindrical surface juxtaposes with that of said intermediate element, and
- said intermediate element and said metal substructure having interengaging elements which allow said metal substructure to be inserted fully into said subassembly but prevent its withdrawal therefrom so that forces at said joint are transferred compressively through said pyrocarbon shell and said intermediate element to said convex surface of said metal substructure.
An implant for providing a replacement articulating surface for the head of the humerus in the shoulder joint, which implant comprises:
- a pyrocarbon shell having an outer convex surface which is a section of a sphere, a concave interior surface and an open proximal base,
- a metal substructure having a convex distal surface and means at the proximal surface thereof for securing the implant in a cavity formed at the end of a bone, and
- an intermediate element in the form of a shell which is sufficiently flexible to allow its insertion axially into said open proximal base of said pyrocarbon shell and create an interference fit that prevents its withdrawal from this subassembly of shell and intermediate element, said shell having a convex outer surface section which substantially abuts said interior concave surface of said pyrocarbon shell,
- said intermediate element having a cylindrical interior surface section and said metal substructure having a cylindrical surface section proportioned to juxtapose with that of said intermediate element,
- said element and said metal substructure having facing grooves in said cylindrical surfaces that align with each other when said metal substructure is fully inserted into said subassembly, and
- an expandable retainer that is completely received in the groove in said metal substructure that expands and resides partially in each of said facing grooves after such insertion of said metal substructure into said subassembly, whereby forces at said shoulder joint are transferred compressively through said pyrocarbon shell to said convex surface of said metal substructure.
Dependencies are inferred from the claim text.