Expandable articulating intervertebral implant with limited articulation

Abstract

An artificial functional spinal unit including an expandable intervertebral implant that can be inserted via a posterior surgical approach and used with one or more facet replacement devices to provide an anatomically correct range of motion is described. Lordotic and non-lordotic expandable, articulating implants and cages are described, along with embodiments of facet replacement devices and instruments for insertion. Methods of insertion are also described.

1 .- 157 . (canceled) 
     
     
         158 . An intervertebral implant for a human spine, comprising:
 a lower body comprising a superior surface and an inferior surface, wherein the inferior surface of the lower body is configured to engage a first vertebra of a human spine;   an upper body comprising an inferior surface and a superior surface, wherein the superior surface of the upper body is configured to engage a second vertebra of a human spine;   an insert positioned between the superior surface of the lower body and the inferior surface of the upper body before insertion of the intervertebral implant between the first vertebra of a human spine and the second vertebra of a human spine; and   an expansion member configured to engage the insert to increase a separation distance between the upper body and the lower body after insertion of the intervertebral implant between the first vertebra and the second vertebra of a human spine;   wherein the insert is moved in a substantially linear direction and both the upper body and lower body are moved at an oblique angle with respect to the insert.   
     
     
         159 . The intervertebral implant of  claim 158 , wherein the insert comprises generally upwardly projecting protrusions and the upper body comprises recesses in which the protrusions of the insert are positioned, wherein the protrusions and the recesses are configured to secure the upper body and the lower body together to inhibit dislocation of the upper body from the lower body after insertion of the intervertebral implant between the first vertebra and the second vertebra of a human spine. 
     
     
         160 . The intervertebral implant of  claim 158 , further comprising a cage comprising a first opening in a superior surface of the cage and a second opening in the inferior surface of the cage;
 wherein the upper body is inserted and maintained at least partially in the first opening of the cage and the second member is inserted and at least partially maintained in the second opening of the cage, wherein the upper body is expanded above the superior surface of the cage and the inferior surface of the lower body is expanded below the inferior surface of the cage.   
     
     
         161 . The intervertebral implant of  claim 160 , wherein prior to expansion, at least a portion of the superior surface of the upper body rests upon at least a portion of the superior surface of the cage and at least a portion of the inferior surface of the lower body rests on at least a portion of the inferior surface of the cage. 
     
     
         162 . The intervertebral implant of  claim 160  wherein the cage comprises a superior structure and an inferior structure, and further wherein at least one of the superior and inferior structures is configured to maintain at least a portion of the expandable element within the cage. 
     
     
         163 . An intervertebral implant for a human spine, comprising:
 a lower body comprising a superior surface and an inferior surface, wherein the inferior surface of the lower body is configured to engage a first vertebra of a human spine;   an upper body comprising an inferior surface and a superior surface, wherein the superior surface of the upper body is configured to engage a second vertebra of a human spine;   an insert comprising an elongated body having a substantially flat inferior surface, a substantially flat superior surface, and a first angled portion; and   an expansion member configured move the insert, wherein the expansion member is configured to be positioned between the upper body and the lower body;   wherein insert is configured such that the substantially flat superior and inferior surfaces of the elongated body of the insert move in a substantially linear direction and both the upper and lower bodies are moved at least partially at an oblique angle with respect to the insert to increase a separation distance between the superior surface of the upper body and the inferior surface of the lower body.   
     
     
         164 . The intervertebral implant of  claim 163 , wherein the first angled portion of the insert engages an angled portion on the upper member to increase a separation distance between the superior surface of the upper body and the inferior surface of the lower body. 
     
     
         165 . An intervertebral implant for a human spine, the intervertebral implant comprising:
 a first body comprising a first surface and a second surface, wherein the first surface of the first body is configured to engage a first vertebra of a human spine;   a second body comprising a first surface and a second surface, wherein the second surface of the second body is configured to engage a second vertebra of a human spine; and   an expansion member comprising an elongated body having a substantially flat first surface, a substantially flat second surface, and a first angled portion at an insertion end of the elongated body, wherein the expansion member is configured to be positioned between the first body and the second body such that applying a force to a trailing end of the elongated body opposite the insertion end of the elongated body is configured to advance the first angled portion and the substantially flat first and second surfaces of the expansion member in a substantially linear direction between, and at least partially oblique to, at least a portion of the second surface of the first body and at least a portion of the first surface of the second body after insertion of the first and second bodies in a human spine so as to increase a separation distance between the first surface of the first body and the second surface of the second body.   
     
     
         166 . An intervertebral implant for a human spine, comprising:
 a first member comprising a first inferior surface and a first superior surface, where the first superior surface comprises a substantially planar surface configured to contact and support a first vertebra of a human spine;   a second member comprising a second inferior surface and a second superior surface, where the second inferior surface comprises a substantially planar surface configured to contact and support a second vertebra of a human spine;   a cage comprising a first opening in a superior surface of the cage and a second opening in an inferior surface of the cage, wherein the first member is inserted at least partially into the first opening and the second member is inserted at least partially in the second opening; and   an expansion element that is inserted between the first inferior surface of the first member and the second superior surface of the second member, wherein insertion of the expansion member expands the first and second members relative to one another to increase a separation distance between the first superior surface of the first member and the second inferior surface of the second member, wherein the first superior surface is expanded above the superior surface of the cage and the second inferior surface is expanded below the inferior surface of the cage, such that the distance between the first superior surface and the second inferior surface is greater than the distance between the superior surface and the inferior surface of the cage, and wherein the first superior surface supports at least a portion of the first vertebra above the superior surface of the cage and the second inferior surface supports at least a portion of the second vertebra below the inferior surface of the cage;   wherein portions of the first and second members are maintained within the first and second openings, respectively, of the cage.   
     
     
         167 . The intervertebral implant of  claim 166 , wherein prior to expansion, at least a portion of the superior surface of the upper body rests upon at least a portion of the superior surface of the cage and at least a portion of the inferior surface of the lower body rests on at least a portion of the inferior surface of the cage. 
     
     
         168 . The intervertebral implant of  claim 166  wherein the cage comprises a superior structure and an inferior structure, and further wherein at least one of the superior and inferior structures is configured to maintain at least a portion of the expandable element within the cage.