Methods and apparatus for treating disc herniation and preventing the extrusion of interbody bone graft

Abstract

Methods and apparatus for treating disc herniation provide a conformable device which assumes a first shape associated with insertion and a second shape or expanded shape to occlude the defect which typically follows partial discectomy. The device may take different forms according to the invention, including patches size to cover the defect or plugs adapted to fill the defect. In a preferred embodiment, however, the device is a gel or other liquid or semi-liquid which solidifies to occlude the defect from within the body of the disc itself. In another preferred embodiment, a mesh screen is collapsed into an elongated form for the purposes of insertion, thereby minimizing the size of the requisite incision while avoiding delicate surrounding nerves. Such a configuration also permits the use of instrumentation to install the device, including, for example, a hollow tube or sheath adapted to hold the collapsed screen, and a push rod to expel the collapsed device out of the sheath for use in occluding the disc defect. A device according to the invention may further include one or more anchors to assist in permanently affixing the device with respect to the defect.

1 . An implant for implantation between a nucleus and an annulus and across a defect in the annulus in an intervertebral disc, comprising:
 a barrier having a first and second surface, wherein said first surface is adapted to present a concave surface facing the nucleus in the implanted orientation and wherein said barrier is dimensioned to extend along the annulus across and beyond the periphery of the area defining a defeat.   
     
     
         2 . The implant of  claim 1 , wherein said barrier is resilient. 
     
     
         3 . The implant of  claim 1 , wherein said barrier is adapted to contact load bearing annulus tissue sufficient to prevent extrusion of said barrier through said defect. 
     
     
         4 . The implant of  claim 1 , wherein said barrier is adapted to contact load bearing vertebral body endplate tissue sufficient to prevent extrusion of said barrier through said defect. 
     
     
         5 . The implant of  claim 1 , wherein said barrier has a width of at least 1 cm. 
     
     
         6 . The implant of  claim 1 , wherein said barrier has a height of at least 0.05 cm. 
     
     
         7 . The implant of  claim 1 , wherein said second surface is adapted to present a convex surface in conformity with the interior surface of the annulus. 
     
     
         8 . The implant of  claim 1 , wherein said second surface is adapted to present a convex surface in conformity with the endplates. 
     
     
         9 . The implant of  claim 1 , wherein said barrier is adapted to fit between the nucleus and the annulus. 
     
     
         10 . The implant of  claim 1 , wherein said barrier has a top and bottom edge and a first and second side edge, wherein said top and bottom edge are dimensioned to contact the endplates at maximum distraction. 
     
     
         11 . The implant of  claim 1 , wherein said barrier is dimensioned such that when the barrier is centered in the posterior annulus, the first and second side edges of said barrier lie beyond the posterior annulus and along opposite lateral walls of the annulus. 
     
     
         12 . A device for augmenting an annulus of an intervertebral disc suitable for inserting along an interior aspect of an annular lamella substantially in front of a defect in the annulus, comprising:
 a thin resilient barrier having a first surface facing an interior aspect of the annular lamella and a second surface facing the interior of the intervertebral disc, wherein said barrier is adapted to be sealably positioned against the lamella via the exertion of force on the second surface sustained by a pressurized intervertebral disc environment.   
     
     
         13 . The device of  claim 12 , wherein the barrier is adapted to be inserted between the annulus and the nucleus. 
     
     
         14 . A device for partially encapsulating inter-annular material comprising resilient flexible material adapted to conform to at least a portion of the interior surface of an annulus fibrosus and of sufficient size and sufficient rigidity to not be extrudable through an annulus defect. 
     
     
         15 . An annulus augmentation implant for insertion along the surface of an annular lamella and across a defect in an intervertebral disc, comprising:
 a collapsible resilient barrier having a top and bottom edge and a first and second side edge,   wherein the top and bottom edge are sized to contact the endplates at maximum distraction;   and wherein the first and second edge extend beyond the defect.   
     
     
         16 . The device of  claim 15 , wherein the barrier has a concave cross section along at least a portion of its length. 
     
     
         17 . The implant of  claim 15 , wherein the first edge and the second edge are adapted to extend beyond the posterior annulus when implanted. 
     
     
         18 . A device for transferring intervertebral disc pressure from a defect in an annulus fibrosus to load bearing tissue, comprising:
 a flexible barrier having a first convex surface and a second concave surface;   wherein the first convex surface is in communication with a portion of the posterior annulus;   wherein the second concave surface is in communication with the nucleus pulposus; and   wherein said barrier is dimensioned to extend beyond the periphery of the area defining the defect such that the barrier contacts load bearing intervertebral disc tissue.   
     
     
         19 . A dynamically stable device for shielding defects in an annulus fibrosus of an intervertebral disc, comprising:
 a flexible membrane adapted to yield to interdiscal pressure and conform to at least a portion of the posterior annulus under both distraction and compression of the disc, wherein said membrane is sized to extend along the interior of The posterior annulus.   
     
     
         20 . The device of  claim 19 , wherein the device has a width in a lateral direction and a height in an inferior-superior direction, wherein the height exceeds the distance between an inferior vertebral body and a superior vertebral body when fully distracted so that the device is concave inwardly along an inferior superior axis in the implanted orientation. 
     
     
         21 .- 66 . (canceled)