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 . 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 for an osteogenic material and an opening in communication with said chamber, said load bearing body having a length and a first diameter at a 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 and a pair of substantially flat opposite side walls between said opposite cylindrical portions, said side walls extending along a substantial portion of said length of said load bearing body; and    a cap for blocking said opening, said cap having an occlusion body sized and shaped for contacting said 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 engaging means for engaging said load bearing body to hold said occlusion body within said opening.    
   
   
       4 . The device of  claim 3  wherein said outer surface defines a thru-hole in communication with said chamber and said anchor has a length which reaches from said occlusion body to said thru-hole when said cap is inserted into said opening and said lip is engaged within said thru-hole.  
   
   
       5 . The device of  claim 3  further comprising a flange projecting from a perimeter of said occlusion body.  
   
   
       6 . 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 for an osteogenic material and an opening in communication with said chamber, said load bearing body having a length and a first diameter at a first end and a larger second diameter at a second end opposite said first end, said first and second diameters sized to be greater than the space between the adjacent vertebrae, said load bearing body having an outer surface tapered from said first diameter to said second diameter; and    a cap for blocking said opening, said cap having an occlusion body sized and shaped for contacting said 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 engaging means for engaging said load bearing body to hold said occlusion body within said opening.    
   
   
       7 . The device of  claim 6  wherein said outer surface defines a thru-hole in communication with said chamber and said anchor has a length which reaches from said occlusion body to said thru-hole when said cap is inserted into said opening and said lip is engaged within said thru-hole.  
   
   
       8 . A tool for manipulating a cap for a hollow interbody fusion device, comprising: 
 a pair of prongs each having a proximal end defining first engaging means for engaging the fusion device;    a shaft having a first end defining second engaging means for engaging the cap; and    means for slidably supporting said shaft between said prongs.    
   
   
       9 . A tool for manipulating a cap for a hollow interbody fusion device, comprising: 
 a body defining a passageway therethrough;    a pair of prongs each having a distal end attached to said housing and a proximal end having facing engagement surfaces for engaging the fusion device; and    a shaft slidably disposed within said body, said shaft having a first end defining a cap-engaging tip for engaging a tool hole in the cap, said shaft slidable between a retracted position and an extended position at which said first end is adjacent and between said proximal ends of said prongs.    
   
   
       10 . The tool of  claim 9  wherein said prongs are made of a resilient material.  
   
   
       11 . The tool of  claim 9  wherein said cap engaging tip defines threads.  
   
   
       12 . The tool of  claim 9  further comprising: 
 a pair of releasing members, one of said releasing members disposed on each of said facing engagement surfaces, said releasing members having a height and a width for being insertable into apertures in a body wall in the fusion device.    
   
   
       13 . The tool of  claim 9  further comprising releasing means for applying pressure to elongate arms of the cap to deflect the arms inwardly to release the cap from the interbody fusion device.  
   
   
       14 . The tool of  claim 13  wherein said releasing means includes a pair of releasing members, one of said releasing members disposed on each of said facing engagement surfaces, said releasing members having a height and a width for being insertable into apertures in a body wall in the fusion device to disengage the elongate arms from the apertures.  
   
   
       15 . The tool of  claim 9  further comprising: 
 a proximal stop member disposed on said shaft adjacent said first end for preventing said first end from entering said passageway.    
   
   
       16 . The tool of  claim 15  wherein said proximal stop member comprises an O-ring engaged to said shaft.  
   
   
       17 . The tool of  claim 16  wherein said shaft defines a groove for seating said O-ring.  
   
   
       18 . The tool of  claim 9  further comprising a distal stop member attached to a second end of said shaft, said distal stop member having a perimeter which is larger than a perimeter of said passageway to prevent said second end of said shaft from entering said passageway.  
   
   
       19 . The tool of  claim 17  further comprising a distal stop member attached to a second end of said shaft, said distal stop member having a diameter which is larger than a diameter of said passageway to prevent said second end of said shaft from entering said passageway.  
   
   
       20 . The tool of  claim 9  further comprising a distal shaft manipulating member attached to a second end of said shaft for rotating and sliding said shaft within said passageway.  
   
   
       21 . The tool of  claim 20  wherein said manipulating member has a dimension that is larger than a perimeter of said passageway to prevent said second end of said shaft from entering said passageway.  
   
   
       22 . The tool of  claim 21  wherein said manipulating member is a thumb wheel.  
   
   
       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 . The device of  claim 23 , further comprising a bonding layer provided over said metal body, said layer extending into said pores.  
   
   
       27 . The device of  claim 26  wherein said bonding layer includes a calcium phosphate composition.  
   
   
       28 . The device of  claim 27  wherein said calcium phosphate composition comprises hydroxyapatite.  
   
   
       29 . The device of  claim 28  wherein said calcium phosphate composition further comprises tricalcium phosphate, said calcium phosphate composition being a biphasic ceramic.  
   
   
       30 . The fusion device according to  claim 23  wherein said porous material is a composite comprising a nonmetallic rigid foam substrate formed by an interconnected network of carbonaceous material defining continuous, interconnected pores and a metallic film substantially covering said interconnected network.  
   
   
       31 . The fusion device according to  claim 30  wherein said carbonaceous material is a carbon foam.  
   
   
       32 . The fusion device according to  claim 30  wherein said metallic film comprises a group VB metal or an alloy of said group VB metal.  
   
   
       33 . The fusion device according to  claim 32  wherein said metallic film comprises tantalum or an alloy thereof.  
   
   
       34 . The device of  claim 30  further comprising a bonding layer of a calcium phosphate composition, said calcium phosphate composition layered over said interconnected network.  
   
   
       35 . The device of  claim 23  wherein said body: 
 is elongated having a length, a first diameter at a first end and a larger second diameter at a second end opposite said first end, said first and second diameters sized to be greater than the space between the adjacent vertebrae;    said body having an outer surface that is substantially continuously tapered from said first end to said second end with external threads defined on said outer surface and extending substantially entirely along said length of said body.    
   
   
       36 . The device of  claim 23  wherein said 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 body having an outer surface with a pair of opposite cylindrical portions extending along substantially the entire length of said 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 body.    
   
   
       37 . The device of  claim 36  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 body.  
   
   
       38 . The device of  claim 37  wherein said cylindrical portions are tapered along a substantial portion of said length and define a second diameter at a second end thereof that is greater than said first diameter.  
   
   
       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 . The device of  claim 49  further comprising a cap for blocking said opening, said cap having: 
 an occlusion body sized and shaped for contacting said 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 engaging means for engaging said load bearing body to hold said occlusion body within said opening.    
   
   
       52 . The device of  claim 51  wherein said occlusion body includes an outer wall defining osteogenic apertures sized to permit bone ingrowth and protein egress.  
   
   
       53 . The device of  claim 51  wherein said engaging means comprises a lip projecting from said second end to contact said internal surface.  
   
   
       54 . The device of  claim 51  wherein said load bearing body defines a thru-hole in communication with said chamber and said anchor has a length which reaches from said inner surface to said thru-hole when said cap is inserted into said opening and said lip is engaged within said thru-hole.  
   
   
       55 . The device of  claim 53  wherein said outer wall is flush with said opening when said lip is engaged to the thru-hole.  
   
   
       56 . The device of  claim 51  further comprising a second elongate anchor projecting from said occlusion body.  
   
   
       57 . The device of  claim 51  wherein said anchor is composed of a resilient material.  
   
   
       58 . The device of  claim 51  wherein said cap is composed of a biocompatible polymer.  
   
   
       59 . The device of  claim 58  wherein said polymer is polyethylene.  
   
   
       60 . The device of  claim 56  wherein said occlusion body defines a tool hole for receiving a driving tool.