Prosthesis structure

Abstract

A prosthesis structure ( 1 ) for anchorage to the joint end of an articulatory part of a joint ( 11 ) in a human or animal body comprises an engagement element ( 3 ) which presents a flat or substantially flat engagement surface ( 3 b ) for engaging with a complementary joint end surface ( 14 ) provided at the joint end and an elongate fixture ( 4 ) connected to and spaced from the engagement surface for insertion into a complementary bore ( 12 ) provided at the joint end at a distance from the joint end surface ( 14 ). The elongate fixture forms an acute angle (β) with the engagement surface ( 3 b ).

1 . A prosthesis structure ( 1 ) for anchorage to a joint end of an articulatory part ( 11 ) of a joint in a human or animal body comprising an engagement element ( 3 ) which presents a flat or substantially flat engagement surface ( 3   b ) for engaging with a complementary joint end surface ( 14 ) provided at said joint end and an elongate fixture ( 4 ) connected to and spaced from the engagement surface for insertion into a complementary bore ( 12 ) provided at said joint end at a distance from said joint end surface ( 14 ) characterised in that the elongate fixture ( 4 ) forms an acute angle (β) with the engagement surface ( 3   b ).  
     
     
         2 . A prosthesis structure as claimed in  claim 1 , characterised in that said acute angle (β) is greater than or equal to 1°.  
     
     
         3 . A prosthesis structure as claimed in  claim 1  or  2 , characterised in that said acute angle (β) is less than or equal to 5°.  
     
     
         4 . A prosthesis structure as claimed in any one of  claims 1  to  3 , characterised in that said acute angle (β) is within the range of 1° to 3°.  
     
     
         5 . A prosthesis structure as claimed in any one of the preceding claims, characterised in that the elongate fixture is a first elongate fixture ( 4 ) and that the structure ( 1 ) comprises one or more further corresponding elongate fixtures ( 5 ) extending generally in parallel with said first elongate fixture ( 4 ) for insertion into a corresponding number of further complementary bores ( 13 ) provided in said joint end at a distance from said joint end surface ( 14 ).  
     
     
         6 . A prosthesis structure as claimed in any one of the preceding claims, characterised in that an insertion end portion ( 4   a ) of the or each fixture ( 4 ,  5 ) is of a reduced cross-section.  
     
     
         7 . A prosthesis structure as claimed in  claim 6 , characterised in that the or each insertion end portion ( 4   a ) is bevelled on a side facing the engagement surface ( 3   b ) for obtaining said reduced cross section.  
     
     
         8 . A prosthesis structure as claimed in  claim 7 , characterised in that the or each insertion end portion ( 4   a ) is bevelled to such a degree that the side of the insertion end portion facing the engagement surface ( 3   b ) forms an angle (δ) with the corresponding side of the remaining portion ( 4   b ,  4   c ) of the fixture ( 4 ,  5 ) in the range of 1° to 4°.  
     
     
         9 . A prosthesis structure as claimed in  claim 8 , characterised in that the angle (δ) between the bevelled side of the or each insertion end portion ( 4   a ) and the corresponding side of the remaining portion ( 4   b ,  4   c ) of the fixture ( 4 ,  5 ) is approximately 2°.  
     
     
         10 . A prosthesis structure as claimed in any one of the preceding claims, characterised in that the engagement surface ( 3   b ) is provided with one or more bone tissue receiving cavities ( 6   a ,  6   b ,  7   a ,  7   b ) which are adapted to receive bone tissue of the joint end surface on anchorage of the prosthesis structure to the joint end.  
     
     
         11 . A prosthesis structure as claimed in  claim 10 , characterised in that the or each bone tissue receiving cavity ( 6   a ,  6   b ,  7   a ,  7   b ) is in the form of a longitudinal groove formed in the engagement surface ( 3   b ) which extends generally in the direction of the or each fixture ( 4 ,  5 ).  
     
     
         12 . A prosthesis structure as claimed in any one of the preceding claims, characterised in that the or each elongate fixture ( 4 ,  5 ) extends between opposed sides of the engagement element ( 3 ) at an inclined angle relative to the general direction in which the opposed sides extend.  
     
     
         13 . A prosthesis structure as claimed in any one of the preceding claims, characterised in that the prosthesis structure ( 1 ) is an anchoring component part of a joint prosthesis assembly ( 2 ) for partial or total replacement of the joint end of the articulatory part ( 11 ) of the joint.  
     
     
         14 . A prosthesis structure as claimed in any one of the preceding claims, characterised in that the prosthesis structure ( 1 ) is adapted for anchorage to the knee-joint end of one of the articulatory parts ( 11 ) of a human or animal knee-joint.  
     
     
         15 . A prosthesis structure ( 1 ) for anchorage to a joint end of an articulatory part of a joint in a human or animal body substantially as hereinbefore described with reference to the accompanying Figures of drawings.