Acetabular component with improved liner seal and lock

Abstract

An acetabular component for a hip replacement system comprises an acetabular shell, and a liner having a seal for insertion into the acetabular shell. In the preferred embodiment, the shell has a smooth tapered surface in its peripheral inner surface, and the liner has several annular ridges protruding from its outer surface. Upon insertion of the liner into the shell, the annular ridges of the liner come into sealing engagement with the smooth tapered surface of the shell. This sealing engagement substantially prevents a migration of debris along an interface of the liner with the shell. The liner is provided with several peripheral tabs for interference fit with several peripheral notches in the shell. An interlock comprising another liner ridge and a shell groove, provide a positive engagement to hold the liner in the shell as it bottoms therein. In an alternative embodiment, each notch is provided with protruding lips which project into the notch and firmly grasp one of the tabs of the liner upon insertion of the liner into the shell. In this manner, micromotion between the liner and the shell is substantially inhibited.

1. An acetabular component comprising:
 an acetabular shell, said shell including at least one screw hole formed therein, said shell including a smooth inner sealing surface;    said acetabular shell also having at least one interlock circumferential groove and a plurality of peripheral notches formed therein;    a liner configured to seat within said acetabular shell, said liner including at least one circumferential peripheral annular seal, said at least one peripheral seal engaging said smooth inner sealing surface of said acetabular shell in a sealing engagement to restrict migration of debris toward said at least one screw hole;    said liner also including a separate raised locking ridge positioned to engage said interlock groove of said acetabular shell in a snap-lock arrangement; and    a plurality of generally rounded peripheral tabs on the peripheral edge of said liner, said tabs disposed to engage said plurality of notches on said acetibular shell so as to prevent rotational movement of said liner within said acetabular shell.    
     
     
       2. The acetabular component of  claim 1  wherein said acetabular component is load bearing, said liner being formed to substantially conform to and contact said shell under load bearing conditions, said at least one peripheral seal being positioned to maintain its sealing engagement between said liner and smooth inner sealing surface of said shell under load bearing conditions. 
     
     
       3. The acetabular component of  claim 2  wherein said at least one seal includes at least one ridge of resilient material so that load bearing contact between said liner and said shell maintains said ridge a sealing engagement therebetween. 
     
     
       4. The acetabular component of  claim 3  wherein each of said at least one ridges is an annulus integrally formed on said liner, and said smooth inner sealing surface is sized and spaced to receive and seat all of said at least one ridges, said seal thereby restricting migration of debris. 
     
     
       5. The acetabular component of  claim 4  wherein said at least one seal extends annularly around the liner to thereby restrict debris from passing to the screw holes. 
     
     
       6. The acetabular component of  claim 1  wherein each notch includes a pair of inwardly projecting lips to grasp said tabs as they engage. 
     
     
       7. A prosthesis comprising:
   a shell having at least one screw hole formed therein and a smooth inner sealing surface;        a liner configured to seat within said smooth inner surface of said shell, said liner including at least one circumferential peripheral annular seal flexibly and sealingly engaging said smooth inner sealing surface of said shell to restrict migration of debris toward said at least one screw hole;        said shell having a plurality of peripheral notches therein; and        said liner having a plurality of tabs extending outwardly from the liner with each tab being received in a respective one of said notches in said shell, each said notch having a pair of inwardly projecting lips to grasp its respective said tab.     
     
     
       8. The prosthesis of  claim 7 , wherein with said tabs so disposed in said notches, micromotion of said liner within said shell is inhibited. 
     
     
       9. A component for an orthopedic joint replacement system, said component comprising a metal shell adapted to be affixed to a bony structure within the human body by means of bone screws, said shell having one or more holes therein for reception of said bone screws and an inner surface, a liner of a suitable synthetic resin material adapted to fit closely within said inner surface of said shell, said liner constituting a bearing surface for another component of said joint replacement system, said liner having at least one flexible seal extending outwardly from said liner for sealing engagement with said inner surface of said shell around the entire liner so as to prevent the migration of joint fluid and debris from said joint to said screw holes, said seal being configured so as to flex upon insertion of said liner into said shell after said shell has been affixed to said bony structure by said bone screws, said liner further having a lock separate from said seal, said lock comprising a plurality of notches in an upper peripheral edge of said shell and a plurality of tabs, at least one notch for each said tab, said tabs extending outwardly from said liner and being adapted to be received in said notches upon installation of said liner into said shell, each said notch having a pair of inwardly sloping sidewalls cooperating with said tabs so as to substantially inhibit micro motion between said liner and said shell. 
     
     
       10. The prosthesis of  claim 7 , wherein each of said tabs has a rounded surface and an flat surface, wherein said rounded surfaces bear on the base of said recess and wherein said lips engage said flat surface of said tabs as the tabs are received within said notches.