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 . A device for preventing the escape of natural, artificial, or therapeutic material through a defective region in an annulus fibrosis of a spinal disc, and for preventing disc herniation, comprising: 
 an implant having a first physical extent facilitating introduction of the implant relative to the defective region in the annulus fibrosis, and a predetermined second physical extent forming a final shape of the device, different from the first,    wherein the implant is composed of material that naturally returns to the predetermined second physical extent and that functions to occlude the defective region by expanding from the first physical extent to the second physical extent, and    wherein no further steps are required to form the predetermined second physical extent.    
   
   
       2 . A device according to  claim 1 , wherein: 
 the implant is composed of flexible or compressible material;    the first physical extent is achieved by compacting the implant; and    the second physical extent is achieved through expansion of the implant.    
   
   
       3 . A device according to  claim 2 , wherein the implant includes a flexible screen or patch.  
   
   
       4 . A device according to  claim 1 , further comprising one or more anchors to hold the implant in place relative to the defective region.  
   
   
       5 . A device according to  claim 1 , wherein: 
 the implant comprises a liquid or gel that solidifies to achieve the predetermined second physical extent.    
   
   
       6 . A device according to  claim 5 , further comprising a hydrogel or elastomer.  
   
   
       7 . A device according to  claim 1 , wherein the first physical extent is achieved by 
 straightening the implant for introduction; and    the second physical extent is achieved as the implant returns to the predetermined shape.    
   
   
       8 . A device according to  claim 1 , further comprising a plurality of implants that function collectively to achieve the second physical extent.  
   
   
       9 . The device according to  claim 8 , wherein the implants are introduced separately.  
   
   
       10 . A device according to  claim 1 , wherein the implant occludes the defective region while allowing compression and distraction of the disc with respect to normal spinal movement.  
   
   
       11 . A device according to  claim 1 , wherein the implant incorporates a radio-opaque contrast material.  
   
   
       12 . A device according to  claim 1 , wherein the implant is retained in notches in the upper and lower vertebrae.