Intervertebral implant component with three points of contact

Abstract

An intervertebral implant is made up of components which each have an inner surface and an outer surface which engages an adjacent vertebra and presents only three distinct points of contact with a cortical rim of the vertebra. Preferably, the outer surface has a footprint which is sized to be within that of the cortical rim. In disclosed embodiments, the footprint can be convexo-concave shaped, D shaped, or kidney shaped. The intervertebral implant can be provided with upper and lower (or first and second) components which engage adjacent first and second vertebrae and which move relative to one another. The implant has both the first and second outer surfaces sized to present a respective footprint sufficient for two lateral-anterior and one posterior points of contact with an adjacent cortical rim of the respective first and second vertebra.

1 . An intervertebral implant component comprising:
 an outer surface for engaging an adjacent vertebra and an inner surface;   wherein said outer surface is constructed to present only three distinct points of contact for engaging a cortical rim of the adjacent vertebra, and said outer surface has a footprint which is sized to be within that of the cortical rim to be engaged.   
   
   
       2 . (canceled) 
   
   
       3 . An intervertebral implant component as claimed in  claim 21  wherein said footprint of said outer surface is convexo-concave shaped. 
   
   
       4 . An intervertebral implant component as claimed in  claim 1 , wherein said footprint of said outer surface is D shaped. 
   
   
       5 . An intervertebral implant component as claimed in  claim 1 , wherein said footprint of said outer surface is kidney shaped. 
   
   
       6 . An intervertebral implant component as claimed in  claim 1 , wherein said three points of contact of said footprint of said outer surface with the cortical rim are two lateral-anterior points and one posterior point. 
   
   
       7 . An intervertebral implant component as claimed in  claim 6 , wherein a footprint of said outer surface includes opposed ends which provide the two lateral-anterior points of contact. 
   
   
       8 . An intervertebral implant component as claimed in  claim 1 , wherein said outer surface includes at least one vertebra engaging protrusion. 
   
   
       9 . An intervertebral implant component as claimed in  claim 8 , wherein said at least one vertebra engaging protrusion includes a protruding keel located adjacent a longitudinal end of said outer surface. 
   
   
       10 . An intervertebral implant component as claimed in  claim 9 , wherein said keel is curved. 
   
   
       11 . An intervertebral implant component as claimed in  claim 1 , wherein said inner surface includes a pair of instrument receiving cutouts extending to an adjacent outer edge thereof. 
   
   
       12 . An intervertebral implant component as claimed in  claim 11 , wherein said cutouts are angled centrally inwardly. 
   
   
       13 . An intervertebral implant component as claimed in  claim 12 , wherein said cutouts are dovetail shaped in cross section. 
   
   
       14 . An intervertebral implant comprising:
 a first part which has a first outer surface for engaging a first vertebra and a first inner surface;   a second part which has a second outer surface for engaging a second vertebrae and a second inner surface; and   said first and second parts being moveable relative to one another;   wherein said first and second outer surfaces are sized to present a respective footprint sufficient for only three points of contact with an adjacent cortical rim of the respective first and second vertebra to be engaged, said footprints also being sized to be within that of the adjacent cortical rim to be engaged.   
   
   
       15 . (canceled) 
   
   
       16 . An intervertebral implant as claimed in  claim 14 , wherein said footprints of said outer surfaces are convexo-concave shaped. 
   
   
       17 . An intervertebral implant as claimed in  claim 14 , wherein said footprints of said outer surfaces are D shaped. 
   
   
       18 . An intervertebral implant as claimed in  claim 14 , wherein said footprints of said outer surfaces are kidney shaped. 
   
   
       19 . An intervertebral implant as claimed in  claim 14 , wherein said three points of contact of each of said footprints of said outer surfaces with the adjacent cortical rims are two lateral-anterior points and one posterior point. 
   
   
       20 . An intervertebral implant as claimed in  claim 19 , wherein each of said footprints of said outer surfaces include opposed ends which provide the two lateral-anterior points of contact. 
   
   
       21 . An intervertebral implant as claimed in  claim 14 , wherein each of said outer surfaces includes at least one vertebra engaging protrusion. 
   
   
       22 . An intervertebral implant as claimed in  claim 21 , wherein each said at least one vertebra engaging protrusion includes a protruding keel located adjacent a longitudinal end of the respective said outer surface. 
   
   
       23 . An intervertebral implant as claimed in  claim 22 , wherein each said keel is curved. 
   
   
       24 . An intervertebral implant as claimed in  claim 14 , wherein each of said inner surfaces includes a pair of instrument receiving cutouts extending to an adjacent outer edge thereof. 
   
   
       25 . An intervertebral implant as claimed in  claim 24 , wherein each of said cutouts is angled centrally inwardly. 
   
   
       26 . An intervertebral implant as claimed in  claim 25 , wherein each of said cutouts is dovetail shaped in cross section.