Prosthesis installation and assembly

Abstract

A system and method for improving assembly of a modular prosthesis, particularly a femoral stem. The system and method may include implementation of assembly systems for modular prosthesis having one or more intermediate components between a pair of “end components” such as a stem and a head. Grip structures are provided on non-aligned assembly axes and holders are used for each phase to engage appropriate grip structures for joinder of components having aligned assembly axes.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . An apparatus for assembly of a modular prosthesis including a stem portion and a trunnion portion coupled to the stem portion, the trunnion portion having an insertion profile defining an insertion axis and a pair of opposing side faces each defining a non-planar grip structure, and a prosthesis head configured to be installed on the trunnion portion and defining an installation aperture complementary to said insertion profile with the installation aperture defining an installation axis, comprising:
 a clamp including a pair of mating engagement structures, complementary to the grip structures, for a non-rotatingly securement of the prosthesis head to the trunnion portion, said clamp including a force applicator configured to apply a relative assembly force between the trunnion portion and to the prosthesis head to install the prosthesis head on the trunnion portion wherein said clamp aligns the axes and wherein said relative assembly force is constrained by said clamp to be coaxial with the axes.   
     
     
         2 . The apparatus of  claim 1  further comprising a fluid ejection system, coupled to said clamp, configured to direct a fluid into the installation aperture. 
     
     
         3 . The apparatus of  claim 2  wherein said fluid consists essentially of an inert gas. 
     
     
         4 . The apparatus of  claim 1  wherein each of the non-planar grip structures includes a trunnion polygon having a plurality of vertices, wherein one vertex of said plurality of vertices of said trunnion polygon includes a trunnion polygon apex disposed closer to the trunnion portion than other vertices of said trunnion polygon, and wherein said trunnion polygon apex is disposed on the installation axis, wherein each mating engagement structure includes a clamp polygon, complementary to said trunnion polygon, having a plurality of vertices, wherein one vertex of said plurality of vertices of said clamp polygon includes a clamp polygon apex, and wherein said clamp polygon apex is disposed on the installation axis during said non-rotatingly securement. 
     
     
         5 . The apparatus of  claim 4  wherein said polygons include a triangle. 
     
     
         6 . A method for securing a modular prosthesis head onto a trunnion portion of a modular prosthesis, comprising:
 deploying the modular prosthesis including a stem portion and the trunnion portion coupled to the stem portion, the trunnion portion having an insertion profile defining an insertion axis and a pair of opposing side faces each defining a non-planar grip structure, and a prosthesis head configured to be installed on the trunnion portion and defining an installation aperture complementary to said insertion profile with the installation aperture defining an installation axis; and   non-rotatingly securing the prosthesis head to the trunnion portion using a clamp including a pair of mating engagement structures, complementary to the grip structures, said clamp including a force applicator configured to apply a relative assembly force between the trunnion portion and to the prosthesis head to install the prosthesis head on the trunnion portion wherein said clamp aligns the axes and wherein said relative assembly force is constrained by said clamp to be coaxial with the axes.   
     
     
         7 . The method of  claim 6  further comprising a fluid ejection system, coupled to said clamp, and directing a fluid into the installation aperture using said fluid ejection system. 
     
     
         8 . The method of  claim 7  wherein said fluid consists essentially of an inert gas. 
     
     
         9 . The method of  claim 6  wherein each of the non-planar grip structures includes a trunnion polygon having a plurality of vertices, wherein one vertex of said plurality of vertices of said trunnion polygon includes a trunnion polygon apex disposed closer to the trunnion portion than other vertices of said trunnion polygon, and wherein said trunnion polygon apex is disposed on the installation axis, wherein each mating engagement structure includes a clamp polygon, complementary to said trunnion polygon, having a plurality of vertices, wherein one vertex of said plurality of vertices of said clamp polygon includes a clamp polygon apex, and wherein said clamp polygon apex is disposed on the installation axis during said non-rotatingly securement. 
     
     
         10 . The method of  claim 9  wherein said polygons include a triangle.