Hip Prosthesis With Monoblock Ceramic Acetabular Cup

Abstract

An improved hlp prosthesis includes an acetabular cup bearing component constructed from a relatively hard and high strength ceramic material for articulation with a ball-shaped femoral head component which may be constructed from a compatible ceramic or metal material. In one form, the acetabular cup further includes a ceramic porous bone ingrowth surface adhered thereto for secure ingrowth attachment to natural patient bone.

1 . A hip joint prosthesis, comprising:
 a generally shell-shaped acetabular cup defining a convex upper side having a size and shape adapted for seated engagement within a patient's natural acetabulum, and a lower side defining a downwardly open and generally part-spherical cavity lined by an articulation surface having a size and shape for articulatory reception of a matingly shaped femoral component;   said acetabular cup being formed from ceramic material having relatively high a relatively high flexural strength and a relatively high fracture toughness for ultra-low wear upon post-implantation articulation with said matingly shaped femoral component.   
     
     
         2 . The hip joint prosthesis of  claim 1  wherein said ceramic material has a relatively high flexural strength greater than about 500 Mega-Pascal (MPa) and a relatively high fracture toughness greater than about 5 Mega-Pascal root meter (MPam 0.5 ). 
     
     
         3 . The hip joint prosthesis of  claim 1  wherein said ceramic material has a relatively high flexural strength greater than about 700 Mega-Pascal (MPa) and a relatively high fracture toughness greater than about 7 Mega-Pascal root meter (MPam 0.5 ). 
     
     
         4 . The hip joint prosthesis of  claim 3  wherein said ceramic material comprises doped silicon nitride. 
     
     
         5 . The hip joint prosthesis of  claim 1  further including a bone ingrowth surface on said convex upper side of said acetabular cup. 
     
     
         6 . The hip joint prosthesis of  claim 1  wherein said bone ingrowth surface comprises a ceramic bone ingrowth surface. 
     
     
         7 . The hip joint prosthesis of  claim 6  wherein said acetabular cup comprises a ceramic material having a variable porosity gradient defining a relatively low porosity first region forming a substrate defining said articulation surface, and a comparatively higher porosity second region defining said ceramic bone ingrowth surface, said first and second regions being integrally formed. 
     
     
         8 . The hip joint prosthesis of  claim 7  wherein said ceramic material has a porosity gradient ranging from about 2% to about 80% by volume, with said higher porosity region having a porosity in the range of from about 30% to about 80% by volume. 
     
     
         9 . The hip joint prosthesis of  claim 8  wherein said ceramic material has pores formed therein with a pore size ranging from about 100 microns to about 500 microns. 
     
     
         10 . The hip joint prosthesis of  claim 1  wherein said matingly shaped femoral component comprises a ball-shaped femoral head. 
     
     
         11 . The hip joint prosthesis of  claim 10  wherein said femoral head is formed from a ceramic material. 
     
     
         12 . The hip joint prosthesis of  claim 10  wherein said femoral head is formed from a ceramic material substantially identical to the acetabular cup ceramic material. 
     
     
         13 . The hip joint prosthesis of  claim 10  wherein said femoral head is formed from a biocompatible metal. 
     
     
         14 . The hip joint prosthesis of  claim 10  further including a retainer for movably retaining said acetabular cup on said femoral head. 
     
     
         15 . A hip joint prosthesis, comprising:
 a generally shell-shaped acetabular cup defining a downwardly open and generally part-spherical cavity lined by an articulation surface having a size and shape for articulatory reception of a matingly shaped femoral component;   said articulation surface of said acetabular cup being formed from ceramic material having relatively high a relatively high flexural strength and a relatively high fracture toughness for ultra-low wear upon post-implantation articulation with said matingly shaped femoral component;   said acetabular cup further defining a convex upper side having a porous bone ingrowth surface thereon and further defining a size and shape adapted for seated engagement within a patients natural acetabulum.   
     
     
         16 . The hip joint prosthesis of  claim 15  wherein said acetabular cup comprises a ceramic material having a variable porosity gradient defining a relatively low porosity first region forming a substrate defining said articulation surface, and a comparatively higher porosity second region defining said bone ingrowth surface, said first and second regions being integrally formed. 
     
     
         17 . The hip joint prosthesis of  claim 15  wherein said matingly shaped femoral component comprises a ball-shaped femoral head. 
     
     
         18 . The hip joint prosthesis of  claim 17  wherein said femoral head is formed from a ceramic material substantially identical to the acetabular cup ceramic material. 
     
     
         19 . The hip joint prosthesis of  claim 17  wherein said femoral head is formed from a biocompatible metal. 
     
     
         20 . A hip joint prosthesis, comprising:
 a generally shell-shaped acetabular cup defining a convex upper side and having a size and shape adapted for seated engagement within a patient's natural acetabulum, and a lower side defining a downwardly open and generally part-spherical cavity lined by an articulation surface having a size and shape for articulatory reception of a matingly shaped femoral component;   said acetabular cup being formed from ceramic material having a relatively high flexural strength and a relatively high fracture toughness for ultra-low wear upon post-implantation with said matingly shaped femoral component; and   said acetabular cup having a rim with a recessed geometry for increase range of motion.   
     
     
         21 . The hip joint prosthesis of  claim 20  wherein said rim includes multiple recesses formed therein for enhanced range of motion. 
     
     
         22 . The hip joint prosthesis of  claim 20  wherein said rim includes a pair of generally diametrically opposed recesses formed therein for enhanced range of motion.