Intervertebral Implant Component With Three Points of Contact

Abstract

A method of implanting an intervertebral implant or component thereof, in which each component is selected to 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. The outer surface is selected to have a footprint which is sized to be within that of the cortical rim. In disclosed embodiments, the footprint can be convexo-concave 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 configured to engage a cortical rim of an adjacent vertebra, the outer surface defining an outer surface footprint;   an inner surface configured to engage an intervertebral insert, the inner surface opposite the outer surface;   wherein the outer surface engages the cortical rim at only three distinct points of contact, and the outer surface footprint is sized to fit entirely within the cortical rim.   
     
     
         2 . The intervertebral implant component of  claim 1 , wherein the outer surface footprint is convexo-concave shaped. 
     
     
         3 . The intervertebral implant component of  claim 1 , wherein the outer surface footprint is D-shaped. 
     
     
         4 . The intervertebral implant component of  claim 1 , wherein the outer surface footprint is kidney shaped. 
     
     
         5 . The intervertebral implant component of  claim 1 , wherein the three distinct points of contact of the outer surface with the cortical rim are two lateral-anterior points and one posterior point. 
     
     
         6 . The intervertebral implant component of  claim 5 , wherein the outer surface includes opposed ends which provide the two lateral-anterior points of contact. 
     
     
         7 . The intervertebral implant component of  claim 1 , wherein the outer surface further comprises at least one vertebra engaging protrusion. 
     
     
         8 . The intervertebral implant component of  claim 7 , wherein the at least one vertebra engaging protrusion comprises a keel. 
     
     
         9 . The intervertebral implant component of  claim 8 , wherein the keel is curved. 
     
     
         10 . The intervertebral implant component of  claim 1 , wherein the inner surface comprises a pair of instrument receiving cutouts which extend to an outer edge of the inner surface. 
     
     
         11 . The intervertebral implant component of  claim 10 , wherein the cutouts are angled centrally inwardly. 
     
     
         12 . The intervertebral implant component of  claim 12 , wherein the cutouts are dovetail shaped in cross section. 
     
     
         13 . An intervertebral implant comprising:
 a first part comprising a first outer surface configured to engage a first vertebra and a first inner surface;   a second part comprising a second outer surface configured to engage a second vertebra and a second inner surface; and   an insert comprising an upper surface and an opposing lower surface, the upper surface engaging with the first inner surface and the lower surface engaging with the second inner surface, such that the first part and the second part are moveable relative to one another;   wherein the first outer surface and the second outer surface each engage an adjacent cortical rim of the respective first and second vertebra at only three, distinct points of contact, the first outer surface and the second outer surface each comprising a footprint configured to fit completely within the adjacent cortical rim to be engaged.   
     
     
         14 . The intervertebral implant of  claim 13 , wherein said footprints of said outer surfaces are convexo-concave shaped. 
     
     
         15 . The intervertebral implant of  claim 13 , wherein said footprints of said outer surface are D-shaped. 
     
     
         16 . The intervertebral implant of  claim 13 , wherein said footprints of said outer surfaces are kidney shaped. 
     
     
         17 . The intervertebral implant of  claim 13 , 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. 
     
     
         18 . The intervertebral implant of  claim 17 , wherein each of said footprints of said outer surfaces include opposed ends which provide the two lateral-anterior points of contact. 
     
     
         19 . The intervertebral implant of  claim 13 , wherein each of said outer surfaces includes at least one vertebra engaging protrusion. 
     
     
         20 . The intervertebral implant of  claim 19 , wherein each of said at least one vertebra engaging protrusions includes a protruding keel located adjacent a longitudinal end of the respective said outer surface. 
     
     
         21 . The intervertebral implant of  claim 20 , wherein each said keel is curved. 
     
     
         22 . The intervertebral implant of  claim 13 , wherein each of said inner surfaces includes a pair of instrument receiving cutouts extending to an adjacent outer edge thereof 
     
     
         23 . The intervertebral implant of  claim 22 , wherein each of said cutouts is angled centrally inwardly. 
     
     
         24 . The intervertebral implant of  claim 23 , wherein each of said cutouts is dovetail shaped in cross section. 
     
     
         25 . The intervertebral implant of  claim 13 , wherein the upper surface and the first inner surface comprise corresponding curved surfaces which enable the first part and the second part to move relative to one another. 
     
     
         26 . The intervertebral implant of  claim 25 , wherein the curved surfaces of the upper surface and the lower surface are concave and the curved surfaces of the first inner surface and the second inner surface are convex.