Spinal surgery tools and positioning method

Abstract

Instruments and methods are disclosed for positioning a spinal implant within an intervertebral disc space between adjacent vertebrae. The invention advantageously provides for positioning of the implant at a predetermined location with reduced likelihood of implant positioning which deviates from the predetermined location.

We claim:  
     
         1 . A method for preparing an implant site for implanting a spinal implant between adjacent vertebrae, the method comprising a step of: 
 inserting a first end of a distraction plug into an intervertebral disc space between the adjacent vertebrae to position a second end of the distraction plug within the intervertebral disc space;    attaching a first end of an obturator to the second end of the distraction plug, a second end of the obturator having an indicator arrangement at a predetermined distance from the first end of the obturator;    positioning a distal end of a guide tube against an exterior surface of the vertebrae, the distal end of the guide tube positioned over the intervertebral disc space and in axial alignment with the distraction plug;    aligning a proximal end of the guide tube relative to the indicator arrangement;    removing the obturator and distraction plug;    passing a first end of an instrument for preparing the implant site through the proximal end of the guide tube to the intervertebral disc space and advancing the first end of the instrument into the intervertebral disc space to prepare the implant site, advancement of the instrument being affirmatively stopped when a second end of the instrument contacts the proximal end of the guide tube.    
     
     
         2 . The method according to  claim 1  wherein the instrument is a reamer.  
     
     
         3 . The method according to  claim 1  wherein the instrument is a tap.  
     
     
         4 . The method according to  claim 1  wherein the indicator arrangement is a mark on the obturator.  
     
     
         5 . The method according to  claim 1  wherein the mark is laser etched.  
     
     
         6 . The method according to  claim 1  wherein the indicator arrangement is a groove.  
     
     
         7 . The method according to  claim 1  wherein the indicator arrangement includes a c-ring that cooperatively fits within a groove on the second end of the obturator.  
     
     
         8 . The method according to  claim 1  wherein the indicator arrangement is an obturator cap that mounts at the proximal end of the obturator.  
     
     
         9 . The method according to  claim 1  wherein the distal end of the guide tube includes paddles.  
     
     
         10 . The method according to  claim 1  wherein the distal end of the guide tube includes teeth for penetrating the exterior surface of the vertebrae.  
     
     
         11 . The method according to  claim 1  wherein the distraction plug is a lordotic distraction plug.  
     
     
         12 . The method according to  claim 1  wherein the implant site is prepared from an anterior aspect of the vertebrae.  
     
     
         13 . A method for implanting a spinal implant at a selected location, the method comprising a step of: 
 establishing a first reference point within an intervertebral disc space between adjacent vertebrae;    establishing a second reference point proximal to the first reference point;    utilizing the second reference point to indicate a position of instruments used to prepare the implant site;    preparing an implant bore with the instruments for insertion of the spinal implant; and    inserting the spinal implant into the prepared implant bore.    
     
     
         14 . The method according to  claim 13  wherein the instruments used to prepare the implant site include a reamer and a tap.  
     
     
         15 . The method according to  claim 13  wherein the first reference point is a trailing end of a distraction plug.  
     
     
         16 . The method according to  claim 13  wherein the second reference point is an indicator arrangement located on an obturator.  
     
     
         17 . The method according to  claim 13  wherein the second reference point provides for alignment of a proximal end of a guide tube, the proximal end of the guide tube providing an affirmative stop to advancement of the instruments used to prepare the implant bore.  
     
     
         18 . The method according to  claim 17  wherein the implant is passed through the guide tube into the prepared implant bore.  
     
     
         19 . The method according to  claim 18  wherein the implant is a proximity implant.  
     
     
         20 . The method according to  claim 18  wherein the implant is a lordotic implant.  
     
     
         21 . The method according to  claim 18  wherein the implant is threaded.  
     
     
         22 . The method according to  claim 13  wherein the first reference point is defined by the desired location of the implant when positioned within the implant site.  
     
     
         23 . A method for implanting a spinal implant at a selected location, the method comprising a step of: 
 determining a desired position of the spinal implant within an intervertebral disc space between adjacent first and second vertebral bodies and using the desired position as a first reference point;    correlating the first reference point with a second reference point located on a surface of at least one of a selected first and second vertebral body;    establishing a third reference point at a distance proximal to the second reference point;    preparing the implant bore utilizing the third reference point to limit distal advancement of instruments used to prepare an implant bore; and    inserting the spinal implant into the prepared implant bore.    
     
     
         24 . The method according to  claim 23  wherein the third reference point is provided by a proximal end of a guide tube positioned against a portion of the selected vertebral body.  
     
     
         25 . The method according to  claim 23  wherein the second reference point is provided by at least one surface of each of the first and second vertebral bodies.  
     
     
         26 . The method according to  claim 24  wherein the third reference point is determined by establishing a fixed distance between the first and third reference points.  
     
     
         27 . A method for preparing an implant bore for implanting a spinal implant between adjacent vertebrae, the method comprising a step of: 
 inserting a first end of a distraction device into an intervertebral disc space between the adjacent vertebrae to position a second end of the distraction device proximal to the intervertebral disc space, the second end of the distraction device having an indicator arrangement at a predetermined distance from the first end of the distraction device;    positioning a distal end of a guide tube against an exterior surface of the vertebrae, the distal end of the guide tube positioned over the intervertebral disc space and in axial alignment with the distraction device;    aligning a proximal end of the guide tube with the indicator arrangement at the second end of the distraction device;    removing the distraction device;    passing a first end of an instrument for preparing the implant bore through the proximal end of the guide tube to the intervertebral disc space and advancing the first end of the instrument into the intervertebral disc space to prepare the implant site, advancement of the instrument being affirmatively stopped when a second end of the instrument contacts the proximal end of the guide tube.    
     
     
         28 . The method according to  claim 27  wherein the distraction device comprises a distraction plug and an obturator.  
     
     
         29 . The method according to  claim 28  wherein the distraction plug and obturator are separable.  
     
     
         30 . A kit for implantation of a spinal implant comprising: 
 a distraction plug, the distraction plug having a leading end and a trailing end;    a guide tube having a proximal end, a distal end and a lumen of sufficient size for passing the distraction plug therethrough; and    an obturator, the obturator having a distal end for attaching to the trailing end of the distraction plug and a proximal end including an indicator arrangement, the indicator arrangement providing for alignment of the proximal end of the guide tube at a predetermined distance from the trailing end of the distraction plug.    
     
     
         31 . The kit according to  claim 30  wherein the indicator arrangement is a mark on the obturator.  
     
     
         32 . The kit according to  claim 30  wherein the indicator arrangement includes stop ring that cooperatively fits within a groove on the proximal end of the obturator.  
     
     
         33 . The kit according to  claim 30  wherein the indicator arrangement is an obturator cap that mounts at the proximal end of the obturator.  
     
     
         34 . The kit according to  claim 30  wherein the proximal end of the guide tube includes an adjustable affirmative stop arrangement.