Acetabular cup conversion ring

Abstract

An acetabular implant for hip replacement surgery includes a shell component and first and second alternative bearing components interchangeably engageable with the shell component to provide a choice in bearing materials. The shell component has an engagement mechanism suitable for locking engagement with the first alternative shell component. A conversion ring is lockingly engageable with the shell component to adapt the shell component to provide an engagement mechanism suitable for locking engagement with the second alternative shell component.

1 . A conversion ring for converting an acetabular shell component engagement mechanism from a first engagement mechanism engageable with a first alternative bearing component to a second engagement mechanism engageable with a second alternative bearing component, the conversion ring comprising: 
 a ring shaped body having a sidewall defining an outer surface and an inner surface and extending axially from a first end to a second end;    a first engagement mechanism formed on the outer surface, the first engagement mechanism of the conversion ring being releasably engageable with the first engagement mechanism of the acetabular shell component in axial locking arrangement; and    a second engagement mechanism formed on the inner surface, the second engagement mechanism of the conversion ring being releasably engageable with the second engagement mechanism of the second alternative bearing component in axial locking arrangement, the first and second engagement mechanisms being of different types selected from the group consisting of snap-fit, press-fit, taper-fit, and threaded-fit engagement mechanisms.    
   
   
       2 . The conversion ring of  claim 1  wherein the first engagement mechanism comprises a snap-fit and the second engagement mechanism comprises a taper-fit.  
   
   
       3 . The conversion ring of  claim 2  wherein the first engagement mechanism comprises a plurality of annular projections formed on the outer surface of the body.  
   
   
       4 . The conversion ring of  claim 2  wherein a portion of the sidewall is slit to allow the conversion ring to resiliently compress and expand.  
   
   
       5 . The conversion ring of  claim 4  wherein the sidewall includes multiple slits extending part-way through the sidewall between the first and second ends, adjacent slits alternately originating from the first and second ends to form the sidewall into a serpentine sidewall.  
   
   
       6 . The conversion ring of  claim 1  wherein the conversion ring is provided in a plurality of configurations each configured to adapt the shell component to receive a differently configured second alternative bearing component.  
   
   
       7 . The conversion ring of  claim 1  wherein the first end defines a first opening and the second end defines a second opening, the first opening being able to receive the alternative bearing component and the second opening permitting the alternative bearing component to project through the body.  
   
   
       8 . A kit of acetabular components for assembling an acetabular joint prosthesis including a shell component and a bearing component disposed in the shell, the kit comprising: 
 a shell component having an external surface shaped for engagement with an acetabulum and an internal cavity, the cavity including a first engagement mechanism;    a first bearing component having an external surface, the external surface defining a complimentary first engagement mechanism engageable with the first engagement mechanism of the shell component,    a conversion ring having a sidewall defining an outer surface and an inner surface and extending axially from a first end to a second end, the outer surface defining a complimentary first engagement mechanism releasably engageable with the first engagement mechanism of the shell component, the inner surface defining a second engagement mechanism;    a second bearing component having an external surface, the external surface defining a complimentary second engagement mechanism releasably engageable with the second engagement mechanism of the conversion ring, such that the conversion ring is insertable into the shell component to convert the shell component from the first engagement mechanism to the second engagement mechanism, the first and second engagement mechanisms being of different types selected from the group consisting of snap-fit, press-fit, taper-fit, and threaded-fit engagement mechanisms.    
   
   
       9 . The kit of  claim 8  wherein the first engagement mechanism comprises a snap-fit and the first bearing component and the conversion ring each include an external surface having a relatively resilient portion for snapping into the shell component.  
   
   
       10 . The kit of  claim 9  wherein the second engagement mechanism comprises a taper-fit and the inner surface of the conversion ring defines a tapered surface such that the ring is intraoperatively engageable with the shell to convert the shell from a snap-fit to a taper-fit engagement mechanism.  
   
   
       11 . The kit of  claim 10  wherein the snap-fit mechanism comprises an annular projection formed on each of the first liner and conversion ring and an annular groove formed in the shell.  
   
   
       12 . The kit of  claim 11  wherein the snap-fit mechanism comprises first and second annular grooves formed in the shell, the grooves being spaced apart axially with the second annular groove being further into the shell than the first annular groove, the first bearing component comprising an annular projection engageable with the first annular groove and the conversion ring comprising an annular projection engageable with the second annular groove.  
   
   
       13 . The kit of  claim 10  wherein the taper-fit is self locking.  
   
   
       14 . The kit of  claim 8  wherein the first bearing component comprises a polymer body having an external surface engageable with the internal cavity of the shell, the external surface including a relatively flexible shell engagement portion and the second bearing component comprises a relatively rigid non-polymeric body having a relatively rigid external surface, the relatively rigid external surface defining a tapered engagement surface.  
   
   
       15 . The kit of  claim 8  wherein the first engagement mechanism comprises a snap-fit and the conversion ring is resiliently collapsible upon insertion into the shell to engage the snap-fit mechanism.  
   
   
       16 . The conversion ring of  claim 15  wherein a portion of the sidewall is slit to allow the conversion ring to resiliently compress and expand.  
   
   
       17 . The conversion ring of  claim 16  wherein the sidewall includes multiple slits extending part-way through the sidewall between the first and second ends, adjacent slits alternately originating from the first and second ends to form the sidewall into a serpentine sidewall.  
   
   
       18 . The conversion ring of  claim 15  wherein engagement of the second bearing component with the conversion ring prevents the conversion ring from collapsing.  
   
   
       19 . The conversion ring of  claim 8  wherein the conversion ring is provided in a plurality of configurations each configured to adapt the shell component to receive a differently configured second alternative bearing component.  
   
   
       20 . A conversion ring for converting an acetabular shell component engagement mechanism from a first engagement mechanism engageable with a first alternative bearing component to a second engagement mechanism engageable with a second alternative bearing component, the conversion ring comprising: 
 a ring shaped body having a sidewall defining an outer surface and an inner surface and extending axially from a first end to a second end, a portion of the sidewall being slit to allow the conversion ring to resiliently compress and expand radially, the sidewall including multiple slits extending part-way through the sidewall between the first and second ends, adjacent slits alternately originating from the first and second ends to form the sidewall into a serpentine sidewall;    a first engagement mechanism formed on the outer surface, the first engagement mechanism of the conversion ring being releasably engageable with the first engagement mechanism of the acetabular shell component in axial locking arrangement; and    a second engagement mechanism formed on the inner surface, the second engagement mechanism of the conversion ring being releasably engageable with the second engagement mechanism of the second alternative bearing component in axial locking arrangement.