Intervertebral implant with conformable endplate

Abstract

An intervertebral implant replaces an intervertebral disc of the human spine. The intervertebral implant includes a first conformable endplate, the first conformable endplate being conformable to a boney vertebral endplate under an anatomical load, a second endplate and a core between the endplates, wherein the first conformable endplate partitions the core from the boney vertebral endplate, whereby the core does not contact the boney vertebral endplate. The invention is also directed to a method of replacing an intervertebral disc. The method includes removing at least a portion of an intervertebral disc to form an intervertebral disc space, implanting a first conformable endplate, into the intervertebral disc space and in contact with a first boney vertebral endplate, the first conformable endplate being conformable to the first boney vertebral endplate under an anatomical load; implanting a second endplate into the intervertebral disc space and in contact with a second boney vertebral endplate; and implanting a core between the first conformable endplate and the second endplate, wherein the first conformable endplate partitions the core from the first boney vertebral endplate, whereby the core does not contact the first boney vertebral endplate.

1 . An intervertebral implant, comprising: 
 (a) a first conformable endplate having a rigid inner surface, the first conformable endplate being conformable to a boney vertebral endplate under an anatomical load;    (b) a second endplate having a rigid inner surface opposing the rigid inner surface of the first conformable endplate; and    (c) a core between the endplates, wherein the first conformable endplate partitions the core from the boney vertebral endplate, whereby the core does not contact the boney vertebral endplate, wherein the core supports boney vertebral endplates between which the conformable endplates have been placed and the position of each conformable endplate is independent of the position of the other endplate.    
   
   
       2 . The intervertebral implant of  claim 1 , wherein the second endplate is conformable to a second boney vertebral endplate under an anatomical load.  
   
   
       3 . The intervertebral implant of  claim 2 , wherein the second endplate partitions the core from the second boney vertebral endplate, whereby the core does not contact the second boney vertebral endplate.  
   
   
       4 . The intervertebral implant of  claim 1 , wherein rigidity of the rigid inner surface of at least one of the endplates is provided by at least one rigid plate disposed between at least one of the first and second endplates and the core, the rigid plate including a material which does not deform under the anatomical load.  
   
   
       5 . The intervertebral implant of  claim 1 , wherein both the first and second endplate include a textured surface that facilitates bone growth.  
   
   
       6 . The intervertebral implant of  claim 5 , wherein the textured surface includes at least one member selected from the group consisting of porous beading, hydroxyapatite, and mesh.  
   
   
       7 . The intervertebral implant of  claim 5 , wherein the textured surface is treated with an osteoinductive material.  
   
   
       8 . The intervertebral implant of  claim 7 , wherein the osteoinductive material includes at least one member selected from the group consisting of a metallic, a polymeric, a ceramic, and a biologic material.  
   
   
       9 . The intervertebral implant of  claim 8 , wherein the metallic material includes at least one member selected from the group consisting of titanium, cobalt-chromium, nitinol, and stainless steel.  
   
   
       10 . The intervertebral implant of  claim 8 , wherein the polymeric material includes at least one member selected from the group consisting of polyethylene, polyester, polyurethane, silicone, and polycarbonate.  
   
   
       11 . The intervertebral implant of  claim 8 , wherein the ceramic material includes at least one member selected from the group consisting of zirconia, alumina, hydroxyapatite, and tricalcium phosphate.  
   
   
       12 . The intervertebral implant of  claim 8 , wherein the biologic material includes at least one member selected from the group consisting of collagen, bone morphogenic protein, a demineralized bone matrix, and a growth factor.  
   
   
       13 . The intervertebral implant of  claim 1 , further including at least one protrusion element coupled to a surface of at least one of the first and second endplates, the protrusion element being capable of penetrating a boney vertebral endplate, thereby securing a position of the first or second endplate to the boney vertebral endplate.  
   
   
       14 . The intervertebral implant of  claim 13 , wherein the protrusion element includes at least one member selected from the group consisting of a keel, a spike, a tooth, a fin, and a peg.  
   
   
       15 . The intervertebral implant of  claim 1 , wherein the conformable material includes at least one member selected from the group consisting of a metallic, a polymeric, and a biologic material.  
   
   
       16 . The intervertebral implant of  claim 1 , wherein the core is non-fluid.  
   
   
       17 . The intervertebral implant of  claim 1 , wherein the core includes an osteoinductive rigid matrix which provides for spinal fusion.  
   
   
       18 . The intervertebral implant of  claim 1 , wherein the implant is an artificial disc.  
   
   
       19 . The intervertebral implant of  claim 1 , wherein the implant is a fusion cage.  
   
   
       20 . A kit, comprising: 
 (a) at least two first conformable endplates, each first conformable endplate being conformable to a boney vertebral endplate under an anatomical load, each first conformable endplate having at least one dimension that is distinct from another conformable endplate of the kit;    (b) at least two second endplates, each second endplate having at least one dimension that is distinct from another second endplate of the kit, wherein each endplate includes a rigid inner surface; and    (c) at least one core, the core being dimensioned for implantation between a first conformable endplate and a second endplate in an intervertebral space that has been prepared for placement of the first conformable endplate, the second endplate and the core, wherein, upon implantation, the first conformable endplate partitions the core from a first boney vertebral endplate with which the first conformable endplate is in contact, whereby the core does not contact the first boney vertebral endplate, wherein the core supports boney vertebral endplates between which the conformable endplates have been placed and the position of each conformable endplate is independent of the position of the other endplate.    
   
   
       21 . The kit of  claim 20 , wherein the second endplate is conformable to a second boney vertebral endplate under an anatomical load.  
   
   
       22 . The kit of  claim 21 , wherein the second endplate, upon implantation of the second endplate and the core into an intervertebral space that has been prepared for placement of the first conformable endplate, the core and the second endplate, partitions the core from the second boney vertebral endplate, whereby the core does not contact the second boney vertebral endplate.  
   
   
       23 . An intervertebral implant, comprising: 
 (a) two conformable endplates, each endplate includes a material that conforms to a boney vertebral endplate under an anatomical load, wherein each endplate includes a rigid inner surface; and    (b) a core between the endplates, the core supporting boney vertebral endplates between which the conformable endplates have been placed and wherein the position of each conformable endplate is independent of the position of the other endplate.    
   
   
       24 . A method of replacing an intervertebral disc, comprising the steps of: 
 (a) removing at least a portion of an intervertebral disc to form an intervertebral disc space;    (b) implanting a first conformable endplate, into the intervertebral disc space and in contact with a first boney vertebral endplate, the first conformable endplate being conformable to the first boney vertebral endplate under an anatomical load;    (c) implanting a second endplate into the intervertebral disc space and in contact with a second boney vertebral endplate, wherein each endplate includes a rigid inner surface; and    (d) implanting a core between the first conformable endplate and the second endplate, wherein the first conformable endplate partitions the core from the first boney vertebral endplate, whereby the core does not contact the first boney vertebral endplate, wherein the core supports boney vertebral endplates between which the conformable endplates have been placed and the position of each conformable endplate is independent of the position of the other endplate.    
   
   
       25 . The method of  claim 24 , wherein the second endplate is conformable to the second vertebral endplate under an anatomical load.  
   
   
       26 . The method of  claim 25 , wherein the second endplate implanted partitions the core from the second boney vertebral endplate, whereby the core does not contact the second boney vertebral endplate.  
   
   
       27 . The method of  claim 26 , further including the step of implanting at least one rigid plate between the core and at least one of the first conformable endplate and the second endplate.