Acetabular Shell System and Method for Making

Abstract

A method for forming an acetabular shell includes providing a working surface such as a mandrel, and spraying the working surface with a first layer of material having a first composition such as aluminum oxide. After a suitable thickness is generated, the spray composition is gradually changed to other compositions having desired particle sizes and distribution. In one example, the composition is changed to a mixture of aluminum oxide and titanium oxide and/or titanium. As thickness builds up, the relative amount of aluminum oxide is decreased such that the composition is all titanium and titanium oxide. After a desired thickness is generated, the acetabular shell is extracted off the mandrel.

1 . A method of making an implant for use in replacing a portion of a patient's joint, the method comprising:
 providing a first die defining a concave cavity having a textured die surface;   providing a second die defining a convex extension surface, the first and second die collectively forming a die cavity;   coating the textured die surface with powdered metal;   injecting a slurry of material into the die cavity;   casting the slurry of material thereby forming a ceramic shell;   removing the ceramic shell from the die cavity, the ceramic shell having a first surface and a second surface, the second surface being formed of metal from the powdered metal;   driving off excess fluid slurry by converting the ceramic shell to a stable dome in an oven;   locating the stable dome onto a mounting instrument;   plasma spraying a layer of material onto an outer surface of the stable dome that corresponds to the second surface of the ceramic shell; and   sintering the ceramic shell.   
   
   
       2 . The method of  claim 1 , further comprising polishing the second surface of the ceramic shell. 
   
   
       3 . The method of  claim 1  wherein forming the ceramic shell comprises casting a ceramic shell having a textured outboard surface having a plurality of dimples, the textured outboard surface adapted to accept the sprayed layer of material. 
   
   
       4 . The method of  claim 3  wherein plasma spraying the layer of material comprises spraying titanium oxide onto the second surface of the ceramic shell. 
   
   
       5 . The method of  claim 1  wherein the textured die surface includes a plurality of outwardly extending knobs