Diffusion-hardened medical implant

A medical implant comprising:

• (a) a first implant portion, said first implant portion having a bearing surface;
• (b) a second implant portion, said second implant portion having a bearing surface;
• (c) wherein the bearing surface of said first implant portion and the bearing surface of said second implant portion each having a size and shape to engage or cooperate with one another;
• (d) wherein one or both of the two portions of the medical implant comprises a biocompatible alloy having an elastic modulus less than 200 GPa;
• (e) wherein the difference in radius of the mating portions is greater than about 50 microns;
• and
• (f) wherein one or both of said first implant portion and said second implant portion comprises:
• a substrate;
• a diffusion hardened zone in contact with said substrate, said diffusion hardened zone comprising a diffusion hardening species,
• a substantially defect-free ceramic layer in contact with said diffusion hardened zone and comprising a surface of said medical implant;
• and
• a metallic hardened layer in contact with the top of the ceramic layer;
• wherein the thickness of the diffusion hardened zone is at least equal to that of the ceramic layer.

A medical implant comprising:

• a substrate comprising a biocompatible alloy having an elastic modulus less than 98 GPa;
• a diffusion hardened zone in contact with said substrate, said diffusion hardened zone comprising a diffusion hardening species, and
• a substantially defect-free ceramic layer in contact with said diffusion hardened zone and comprising a surface of said medical implant;
• wherein the diffusion hardened zone has a layered structure comprising at least two distinct layers under metallographic analysis, the layered structure characterized by:
• a first layer directly below the ceramic layer;
• an interface between the first layer and the ceramic layer;
• and
• a second layer directly below the first layer;
• and
• wherein the thickness of the diffusion hardened zone is at least equal to that of the ceramic layer.

A medical implant comprising:

• a substrate comprising a biocompatible alloy having an elastic modulus less than 98 GPa;
• a diffusion hardened zone in contact with said substrate, said diffusion hardened zone comprising a diffusion hardening species and having a thickness of greater than 2 microns;
• and
• a ceramic layer in contact with said diffusion hardened zone;
• wherein the thickness of the diffusion hardened zone is at least equal to or greater than that of the ceramic layer.