Acetabular cup assembly for multiple bearing materials

Abstract

A modular acetabular cup assembly for use with multiple bearing liners is disclosed. The acetabular cup assembly includes a shell having a tapered inner wall and two circumferential grooves. The shell may be used with polyethylene, ceramic, metal, and other types of liners.

1 . An acetabular cup system, comprising:
 a shell having a generally concave inner surface, an outer surface, an end face formed at an upper end of the shell, an apex formed at a lower end of the shell, and a central axis extending through the apex, wherein the inner surface comprises an inwardly-facing scallop positioned adjacent the end face, an upper wall defining a taper with respect to the central axis and extending below the scallop, a lower wall located below the upper wall, a protrusion located below the lower wall, and a lower groove located below the protrusion, wherein the lower groove is partially defined by the protrusion;   a polymer liner comprising a plurality of tabs sized and shaped to be received in the scallops, and a lower bump sized and shaped to be received in the lower groove;   a metal liner comprising a tapered outer surface;   a locking mechanism including the lower groove of the shell and the lower bump of the polymer liner, wherein the locking mechanism has a locking state in which the lower bump is engaged with the lower groove, an interference fit is formed between the polymer liner and the shell, and the locking mechanism couples the polymer liner with the shell, and wherein the interference fit includes engagement of the bump with the groove; and   an engagement mechanism including the upper wall of the shell and the tapered outer surface of the metal liner, wherein the engagement mechanism has an engaged state in which the upper wall is engaged with the tapered outer surface and the engagement mechanism couples the metal liner with the shell.   
     
     
         2 . The system of  claim 1 , wherein, the inner surface of the shell has a polished finish, and the tapered outer surface of the metal liner has a roughened finish. 
     
     
         3 . The system of  claim 2 , wherein a surface roughness of the inner surface is less than 16 microinches. 
     
     
         4 . The system of  claim 1 , wherein the lower wall is parallel to the central axis. 
     
     
         5 . The system of  claim 1 , wherein the shell further comprises an upper groove located above the protrusion, wherein the upper groove is partially defined by the protrusion, wherein the polymer liner further includes an upper bump located above the lower bump, wherein the locking mechanism further includes the upper groove and the upper bump, and wherein with the locking mechanism in the locking state, the upper bump is engaged with the upper groove. 
     
     
         6 . The system of  claim 5 , wherein with the locking mechanism in the locking state, a dimension of the locking mechanism in a direction parallel to the central axis is less than 20 millimeters.