Mechanical assembly including exterior surface preparation

Abstract

A system and method for improving mechanical assemblies, such as prosthetic implants, intended to be installed in living tissue such as bone. Force-imparting devices are adapted and may include angularity, which may be introduced with specialized additive manufacturing, which may impart congruent cross-sections while providing variable stiffness. In some cases, the variable stiffness may be “stretchy” in a longitudinal direction and “rigid” in a radial directional which may provide an assembly bias. Additive manufacturing may allow the material of a prosthesis to be varied (e.g., density/porosity) to create variable stiffness over a length.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . A mechanical interface between a first prosthesis component and a second prosthesis component, the first prosthesis component including a cavity and the second prosthesis component including an extension to engage the cavity and produce a mechanical join, comprising:
 a first mating taper wall of the cavity having a first cross-sectional profile wherein said first cross-sectional profile is non-circular; and   a second mating taper wall of the extension having a second-cross-sectional profile wherein said second cross-sectional profile is complementary to said first cross-sectional profile.   
     
     
         2 . The mechanical interface of  claim 1  wherein said first cross-sectional profile defines a first perimeter having a first perimeter portion and a second perimeter portion. 
     
     
         3 . The mechanical interface of  claim 2  wherein, said first perimeter profile includes a circular arc greater than 270 degrees and said second perimeter portion includes a key. 
     
     
         4 . The mechanical interface of  claim 2  wherein said first perimeter includes a first series of circular arc portions and wherein said second perimeter includes a second series of keys, a particular one key interposed between pairs of said arc portions. 
     
     
         5 . The mechanical interface of  claim 2  wherein said first perimeter profile includes a plurality of sides. 
     
     
         6 . The mechanical interface of  claim 5  wherein, said first perimeter profile includes a polygon having an N number of sides, N an element of a set {3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more}. 
     
     
         7 . The mechanical interface of  claim 6  wherein said polygon consists essentially of a regular polygon. 
     
     
         8 . The mechanical interface of  claim 1  wherein the cavity defines a cavity axis, wherein the extension defines an extension axis, and wherein said mating taper walls are configured for aligning said axes during engagement of the cavity with the extension. 
     
     
         9 . A method for constructing a set of mating components of a modular prosthesis, comprising:
 a) producing a first component including a cavity;   b) producing a second component including an extension configured to engage said cavity;   c) defining, during the first component producing step a), said cavity having a first mating taper wall including a first cross-sectional profile wherein said first cross-sectional profile is non-circular; and   d) defining, during the second component producing step b), said extension having a second mating taper wall including a second cross-sectional profile wherein said second cross-sectional profile is complementary to said first cross-sectional profile.