Method of making an implantable joint prosthesis

A method of making an implantable joint prosthesis, comprising the steps of:

• (a) ascertaining the geometry of a bone cavity in a bone adapted to receive an implantable joint prosthesis by scanning said bone by irradiation;
• (b) determining a lie of a geometrical centroid axis from the geometry ascertained in step (a);
• (c) developing a shaft core region extending along said axis by finite element analysis of said geometry with the boundary conditions
• (c.sub.1) that a shaft core formed by said region along said axis must have an undercut-free configuration, and
• (c.sub.2) that there must be a uniform stress distribution along said shaft of normal stresses arising in a shaft/bone transition region;
• (d) establishing a configuration of a surface region on said core considering condition (c.sub.1) and in accordance with the result of condition (c.sub.2);
• and
• (e) selecting from a collection of implantable joint shafts a shaft of an implantable joint prosthesis for said bone with said core and said surface region.

A method of forming a joint prosthesis implant, comprising the steps of:

• (a) ascertaining the geometry of a bone cavity in a bone adapted to receive an implantable joint prosthesis by scanning said bone by irradiation;
• (b) determining a lie of a geometrical centroid axis from the geometry ascertained in step (a);
• (c) developing a shaft core region extending along said axis by finite element analysis;
• (d) establishing a configuration of a surface region on said core by applying a coating of a synthetic bone material thereto in response to said geometry and said analysis and configured to provide, on implantation, a uniform stress distribution for normal stresses in a bone/shaft transition region;
• and
• (e) implanting the shaft provided with said coating in said cavity.