Spinal fusion implants and tools for insertion and revision

Abstract

An interbody fusion device in one embodiment includes a tapered body defining a hollow interior or chamber for receiving bone graft or bone substitute material. The body defines exterior threads which are interrupted over portions of the outer surface of the device. The fusion device includes truncated side walls so that on end view the body takes on a cylindrical form. In another embodiment, the tapered body is solid and formed of a porous biocompatible material having sufficient structural integrity to maintain the intradiscal space and normal curvature. The material is preferably a porous tantalum composite having fully interconnected pores to facilitate complete bone tissue ingrowth into the implant. In further embodiments, the fusion devices are provided with osteogenic material to facilitate bone ingrowth. A cap is also provided to block the opening of hollow fusion devices. The cap includes an occlusion body and an elongated anchor. In some embodiments the anchor includes a lip which is engageable to openings in the body wall. Tools are also provided for manipulating caps for interbody fusion devices. In one embodiment the tool includes a pair of prongs each having facing engagement surfaces for engaging the fusion device, and a shaft slidably disposed between the prongs. The shaft has a first end defining a cap-engaging tip for engaging a tool hole in the cap. In one embodiment the cap engaging tip defines threads. In another embodiment the prongs include a pair of releasing members on each of the facing engagement surfaces. The releasing members have a height and a width for being insertable into apertures in a body wall in the fusion device to disengage the elongate anchors from the apertures.

1 . A cap for blocking the opening of a hollow fusion device defining a thru-hole, comprising:
 an occlusion body sized and shaped for blocking the opening; and   an elongate anchor projecting from said occlusion body, said anchor including a first end attached to said occlusion body and an opposite second end having a lip for engaging the thru-hole, said anchor having a length which reaches from said occlusion body to the thru-hole when the cap is inserted into the opening and said lip is engaged to said thru-hole.   
     
     
         2 . The cap of  claim 1  further comprising a flange projecting from a perimeter of said occlusion body. 
     
     
         3 - 22 . (canceled) 
     
     
         23 . A fusion device for facilitating arthrodesis in the disc space between adjacent vertebrae, comprising:
 a metal body composed of a porous, biocompatible bone ingrowth material having interconnected continuous pores; and   an osteogenic material within the pores of said bone ingrowth material, said osteogenic material including a bone morphogenetic protein.   
     
     
         24 . The device of  claim 23  wherein said bone morphogenetic protein is a recombinant human protein. 
     
     
         25 . The device of  claim 24  wherein said bone morphogenetic protein is rhBMP-2, rhBMP-7 or a mixture thereof. 
     
     
         26 - 38 . (canceled) 
     
     
         39 . A fusion device for facilitating arthrodesis in the disc space between adjacent vertebrae, comprising:
 a hollow load bearing body having an internal surface defining a chamber and an opening in communication with said chamber; and   an osteogenic material placed within said chamber, said osteogenic material including a bone morphogenetic protein in a suitable carrier.   
     
     
         40 . The device of  claim 39  wherein said bone morphogenetic protein is selected from the group consisting of BMP-1, BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9, BMP-10, BMP-11, BMP-12, BMP-13. 
     
     
         41 . The device of  claim 40  wherein said carrier is selected from the group consisting of calcium sulphate, polylactic acids, polyanhydrides, collagen, calcium phosphates and polymeric acrylic esters. 
     
     
         42 . The device of  claim 41  wherein said carrier is a sponge. 
     
     
         43 . The device of  claim 39  wherein said carrier is a biphasic ceramic including hydroxyapatite and tricalcium phosphate. 
     
     
         44 . The device of  claim 39  wherein said load bearing body comprises a calcium phosphate composition. 
     
     
         45 . The device of  claim 44  wherein said load bearing body comprises hydroxyapatite. 
     
     
         46 . The device of  claim 45  wherein said load bearing body comprises biphasic hydroxypatite/tricalcium phosphate. 
     
     
         47 . The device of  claim 39  further comprising a cap for blocking said opening, said cap including:
 an occlusion body sized and shaped for contacting said opening and including,
 an outer wall defining osteogenic apertures, said apertures sized to permit bone ingrowth and protein egress, 
 an opposite inner surface; and 
 a rim in communication with said outer wall and said inner surface, said rim defining an engaging surface for contacting said opening; and 
   an elongate anchor projecting from said rim, said anchor including a first end attached to said rim and an opposite second end having a lip, said lip projecting from said second end to contact said internal surface to hold said occlusion body within said opening.   
     
     
         48 . The device of  claim 47  further comprising a flange projecting from a perimeter of said occlusion body. 
     
     
         49 . The device of  claim 39  wherein said load bearing body: is elongated having a length between a first end and a second end thereof, and a first diameter at said first end sized to be greater than the space between the adjacent vertebrae, said load bearing body having an outer surface with a pair of opposite cylindrical portions extending along substantially the entire length of said load bearing body and defining said first diameter, and a pair of substantially flat opposite side walls connected between said opposite cylindrical portions, said side walls extending along a substantial portion of said length of said load bearing body. 
     
     
         50 . The device of  claim 48  further comprising external threads defined on said pair of opposite cylindrical portions of said outer surface and extending along substantially the entire length of said load bearing body. 
     
     
         51 - 60 . (canceled)