Artificial functional spinal unit assemblies

Abstract

An artificial functional spinal unit is provided comprising, generally, an expandable artificial intervertebral implant that can be placed via a posterior surgical approach and used in conjunction with one or more artificial facet joints to provide an anatomically correct range of motion. Expandable artificial intervertebral implants in both lordotic and non-lordotic designs are disclosed, as well as lordotic and non-lordotic expandable cages for both PLIF (posterior lumber interbody fusion) and TLIF (transforaminal lumbar interbody fusion) procedures. The expandable implants may have various shapes, such as round, square, rectangular, banana-shaped, kidney-shaped, or other similar shapes. By virtue of their posteriorly implanted approach, the disclosed artificial FSU's allow for posterior decompression of the neural elements, reconstruction of all or part of the natural functional spinal unit, restoration and maintenance of lordosis, maintenance of motion, and restoration and maintenance of disc space height.

1 - 106 . (canceled)  
     
     
         107 . A spinal implant assembly comprising: 
 at least one intervertebral implant comprising:    a lower body having an inferior surface and a superior surface, the superior surface having an upwardly projecting wall forming a channel thereupon, the wall having an opening defined therethrough;    an upper body located above the lower body, the upper body having a superior surface and a substantially concave inferior surface;    a joint insert having an inferior surface and a substantially convex superior surface, the joint insert residing within the channel on the lower body; and    an expansion device capable of being inserted through the opening in the wall on the lower body such that, upon insertion of the expansion device, the joint insert is lifted above the channel causing the insert to articulate with the substantially concave inferior surface of the upper body; and    at least one artificial facet joint.    
     
     
         108 . The spinal implant assembly of  claim 107 , wherein at least one artificial facet joint comprises: 
 an upper multi-axial pedicle screw having a non-locking head with a hole defined therethrough;    a lower multi-axial pedicle screw having a non-locking head with a hole defined therethrough; and    a rod having a central rod portion and two washer-type heads on each end of the central rod portion, the central rod portion slidingly positioned through the hole in the non-locking head of the upper multi-axial pedicle screw and the lower multi-axial pedicle screw such that the heads of the upper and lower multi-axial pedicle screws slide freely along the central rod portion.    
     
     
         109 . The spinal implant assembly of  claim 107 , wherein at least one artificial facet joint comprises: 
 an upper pedicle screw having a lockable head with a hole defined therethrough;    a lower multi-axial pedicle screw having a non-locking head with a hole defined therethrough; and    a rod having a central rod portion, an upper end and a lower end, the lower end having a washer-type head, the central rod portion slidingly positioned through the hole in the non-locking head of the lower multi-axial pedicle screw such that the washer-type lower head prohibits dislocation of the lower multi-axial pedicle screw from the central rod portion, and the upper end of the rod slidingly positioned through the hole in the lockable head of the upper pedicle screw such that, upon locking of the lockable head, rotational and translational motion of the upper end of the rod is prohibited.    
     
     
         110 . The spinal implant assembly of  claim 107 , wherein at least one artificial facet joint comprises: 
 an upper pedicle screw having a lockable head with a hole defined therethrough;    a lower pedicle screw having a lockable head with a hole defined therethrough; and    a rod having an upper end, a lower end and a central ball joint connecting the upper and lower end that permits the rod to bend, the upper end of the rod slidingly positioned within the hole of the head of the upper pedicle screw, the lower end of the rod slidingly positioned within the hole of the lower pedicle screw, the lockable heads of the upper and lower pedicle screw being locked such that rotational and translational motion of the rod is prohibited.    
     
     
         111 . The spinal implant assembly of  claim 107 , wherein at least one intervertebral implant comprises osteoconductive scaffolding into which bone may grow disposed on the superior surface of the upper body.  
     
     
         112 . The spinal implant assembly of  claim 107 , wherein at least one expandable intervertebral implant comprises osteoconductive scaffolding into which bone may grow disposed on the inferior surface of the lower body.  
     
     
         113 . The spinal implant assembly of  claim 107 , wherein the upper body and lower body have substantially similar shapes.  
     
     
         114 . The spinal implant assembly of  claim 113 , wherein the shape of the upper body when viewed proximally is round.  
     
     
         115 . The spinal implant assembly of  claim 113 , wherein the shape of the upper body when viewed proximally is banana-shaped.  
     
     
         116 . An artificial functional spinal unit, comprising: 
 at least one intervertebral implant, wherein at least one intervertebral implant comprises a lower body configured to couple to a first human vertebra and an upper body configured to couple to a second human vertebra, and wherein the upper body is moveable relative to the lower body to accommodate at least flexion of the first human vertebra relative to the second human vertebra; and    at least one artificial facet joint configured to couple to the first human vertebra and the second human vertebra.    
     
     
         117 . The artificial functional spinal unit of  claim 116 , wherein at least one artificial facet joint comprises: 
 a first pedicle screw;    a second pedicle screw; and    a rod configured to couple to the first pedicle screw and the second pedicle screw such that a head of the first pedicle screw and a head of the second screw are able to slide relative to the rod after installation of the artificial facet joint.    
     
     
         118 . The artificial functional spinal unit of  claim 116 , wherein at least one artificial facet joint comprises: 
 a first pedicle screw;    a second pedicle screw; and    a rod configured to couple to the first pedicle screw and the second pedicle screw such that the rod is secured to a head of the first pedicle screw, and the rod is able to slide relative to a head of the second pedicle screw after installation of the artificial facet joint.    
     
     
         119 . The artificial functional spinal unit of  claim 116 , wherein at least one artificial facet joint comprises: 
 a first pedicle screw;    a second pedicle screw;    a rod configured to couple to the first pedicle screw and the second pedicle screw,    wherein the rod includes a ball joint that allows the rod to bend, and wherein the rod is secured to a head of the first pedicle screw and to a head of the second pedicle screw during installation of the artificial facet joint.    
     
     
         120 . The artificial functional spinal unit of  claim 116 , wherein at least one intervertebral implant comprises osteoconductive scaffolding into which bone may grow.  
     
     
         121 . The artificial functional spinal unit of  claim 116 , wherein the shape of the upper body when viewed proximally is round.  
     
     
         122 . The artificial functional spinal unit of  claim 116 , wherein the shape of the upper body when viewed proximally is banana-shaped.  
     
     
         123 . A method of forming an artificial functional spinal unit, comprising: 
 placing one or more intervertebral implants between a first human vertebra and a second human vertebra, wherein at least one intervertebral implant is configured to accommodate flexion of the first human vertebra relative to the second human vertebra; and    securing at least one artificial facet joint to the first human vertebra and the second human vertebra.    
     
     
         124 . The method of  claim 123 , wherein placing at least one of the intervertebral implants comprises inserting the intervertebral implant between the first human vertebra and the second human vertebra, and expanding the intervertebral implant.  
     
     
         125 . The method of  claim 123 , wherein securing at least one artificial facet joint to the first human vertebra and the second human vertebra comprises: placing a first pedicle screw in the first human vertebra; placing a second pedicle screw in the second human vertebra; coupling a rod to the first pedicle screw and the second pedicle screw, wherein the rod is able to move relative to the first pedicle screw after the rod is coupled to the first pedicle screw.  
     
     
         126 . The method of  claim 123 , wherein at least one artificial facet joint comprises a ball joint configured to accommodate flexion of the first human vertebra relative to the second human vertebra.