Methods and instruments for interbody fusion

Abstract

A laparoscopic surgical technique is provided for preparing a site for implantation of a novel fusion device or implant. In accordance with one embodiment of the technique, a laparoscope is provided having an outer sleeve with distraction fingers at one end to distract the disc space. The laparoscope provides a sealed working channel to the disc space, through which the disc space is distracted, the vertebral endplates and surrounding disc is reamed, and the fusion device inserted. A distraction plug is provided for centering the outer sleeve and for providing midline distraction of the disc space. In one embodiment, a fusion device includes diverging bone screws passing through an end wall and upper and lower walls of the device to engage the adjacent vertebrae. In another embodiment, a connector plate is engaged to bilaterally position fusion devices to prevent rotation and resist expulsion of the devices from the disc space.

1 .- 37 . (canceled) 
     
     
         38 . An interbody fusion apparatus for implantation in a disc space between adjacent vertebrae to be fused, comprising:
 a hollow body having an upper substantially cylindrical portion defining a first aperture therethrough, said hollow body having a lower substantially cylindrical portion defining a second aperture therethrough disposed generally opposite said first aperture, said hollow body having a first end and an opposite second end each arranged along a longitudinal axis, said first end including an end wall defining an upper end wall portion and a lower end wall portion, said end wall defining a first screw bore through said upper end wall portion and extending along a first bore axis oriented such that said first bore axis intersects said first aperture in said upper substantially cylindrical portion, said end wall defining a second screw bore through said lower end wall portion and extending along a second bore axis oriented such that said second bore axis intersects said second aperture in said lower substantially cylindrical portion.   
     
     
         39 . The interbody fusion apparatus of  claim 38 , wherein said first screw bore has a first cylindrical inner surface extending along said first bore axis, said second screw bore having a second cylindrical inner surface extending along said second bore axis. 
     
     
         40 . The interbody fusion apparatus of  claim 38 , wherein said first and second bore axes intersect one another at said longitudinal axis. 
     
     
         41 . The interbody fusion apparatus of  claim 40 , wherein said first and second bore axes intersect one another at a location outside of said hollow body adjacent said end wall. 
     
     
         42 . The interbody fusion apparatus of  claim 38 , wherein said first and second bore axes diverge away from one other relative to said longitudinal axis toward said second end of said hollow body. 
     
     
         43 . The interbody fusion apparatus of  claim 38 , wherein said first and second bore axes extend along a common plane. 
     
     
         44 . The interbody fusion apparatus of  claim 43 , wherein said longitudinal axis of said hollow body extends along said common plane. 
     
     
         45 . The interbody fusion apparatus of  claim 38 , further comprising a first bone screw extending through said first screw bore and arranged along said first bore axis, said first bone screw projecting through said first aperture in said upper substantially cylindrical portion; and
 a second bone screw extending through said second screw bore and arranged along said second bore axis, said second bone screw projecting through said second aperture in said lower substantially cylindrical portion.   
     
     
         46 . The interbody fusion apparatus of  claim 45 , wherein said first and second screw bores each include an enlarged recessed portion opening onto said end wall of said hollow body, said first bone screw including a head portion seated within said enlarged recessed portion of said first screw bore, said second bone screw including a head portion seated within said enlarged recessed portion of said second screw bore. 
     
     
         47 . The interbody fusion apparatus of  claim 46 , wherein said head portions of said first and second bone screws are flush with or recessed below an end surface defined by said end wall of said hollow body. 
     
     
         48 . The interbody fusion apparatus of  claim 46 , wherein said end wall of said hollow body defines a threaded bore positioned between said first and second screw bores; and
 further comprising a locking screw threadedly engaged with said threaded bore and contacting said head portions of said first and second bone screws.   
     
     
         49 . The interbody fusion apparatus of  claim 38 , wherein said end wall of said hollow body defines a pair of elongated slots positioned on opposite sides of said longitudinal axis. 
     
     
         50 . The interbody fusion apparatus of  claim 38 , wherein said hollow body defines a midline extending generally along said end wall between said upper and lower substantially cylindrical portions with said first and second screw bores disposed generally along said midline. 
     
     
         51 . The interbody fusion apparatus of  claim 50 , wherein said midline intersects said longitudinal axis. 
     
     
         52 . The interbody fusion apparatus of  claim 50 , wherein said end wall defines a pair of elongated slots positioned on opposite sides of said longitudinal axis of said hollow body and having a length extending generally along said midline. 
     
     
         53 . The interbody fusion apparatus of  claim 38 , wherein said first and second apertures each comprise an elongate slot having a length extending generally along said longitudinal axis of said hollow body. 
     
     
         54 . The interbody fusion apparatus of  claim 38 , wherein said upper and lower substantially cylindrical portions include external threads configured for threading engagement with the adjacent vertebrae. 
     
     
         55 . The interbody fusion apparatus of  claim 38 , wherein said hollow body defines two substantially flat side wall portions arranged generally opposite one another and extending between said upper and lower substantially cylindrical portions. 
     
     
         56 . The interbody fusion apparatus of  claim 38 , wherein said upper and lower substantially cylindrical portions are tapered from said first end to said second end. 
     
     
         57 . The interbody fusion apparatus of  claim 38 , wherein said upper and lower substantially cylindrical portions define an outer diameter that is greater than a height of the disc space between the adjacent vertebrae.