Method and apparatus for spinal interbody fusion including fixation or locking plate

Abstract

A spinal fusion implant has a parallelepiped main body with a rotatably mounted retention plate secured to its distal end. The distal retention plate has a first position co-planar with the main body and a second, deployed position normal to the plane of the main body. The distal retention plate is in the first position when the main body is inserted between adjacent vertebral bodies and is in the second position after the main body is inserted between adjacent vertebral bodies. In further embodiments, a proximal retention plate is permanently deployed in normal relation to the main body or both the distal and proximal retention plates are rotatably mounted and both are deployed co-planar to the main body before insertion and normal to the main body after insertion.

1 . A spinal fusion implant comprising:
 a main body having a distal end, a proximal end, a superior surface extending between said distal end and said proximal end, said superior surface being configured to engage a first vertebral body of a spinal joint, and an inferior surface extending between said distal end and said proximal end, said inferior surface being configured to engage a second vertebral body of a spinal joint;   a distal retention plate rotatably disposed adjacent to said distal end of said main body, said distal retention plate having (i) a first position wherein said distal retention plate is located within axial projections of said superior and inferior surfaces of said main body, and (ii) a second position wherein said distal retention plate extends beyond axial projections of said superior and inferior surfaces of said main body;   wherein said distance between said distal end of said main body and the proximal end of said main body is approximately the same as the distance between opposing cortical distal and proximal faces of the first and second vertebral bodies, wherein the opposing cortical distal and proximal faces are disposed normal to said superior surface of said main body and said inferior surface of said main body;   wherein said distal retention plate is in said first position when said main body is inserted into the spinal joint between the first vertebral body and the second vertebral body; and   wherein said distal retention plate is in said second position after said main body is inserted into the spinal joint between the first vertebral body and the second vertebral body, and said distal retention plate is disposed in said second position after said insertion such that said distal retention plate engages the opposing cortical distal faces of the first vertebral body and the second vertebral body, whereby to inhibit retraction of said main body and hold said spinal fusion implant and adjacent vertebral bodies in a stable relationship relative to one another.   
     
     
         2 . The spinal fusion implant according to  claim 1 , further comprising a spacer disposed between said distal end of said main body and said distal retention plate. 
     
     
         3 . The spinal fusion implant according to  claim 1 , wherein said distal retention plate comprises a roughened inboard surface. 
     
     
         4 . The spinal fusion implant according to  claim 1 , further comprising a proximal retention plate disposed adjacent to said proximal end of said main body, wherein at least a portion of said proximal retention plate extends beyond axial projections of at least one of said superior surface and said inferior surface of said main body, such that said proximal retention plate limits travel of said main body as said main body is inserted between said adjacent vertebral bodies. 
     
     
         5 . The spinal fusion implant according to  claim 4 , wherein said proximal retention plate is rotatably mounted to said proximal end of said main body. 
     
     
         6 . (canceled) 
     
     
         7 . The spinal fusion implant according to  claim 4 , wherein said proximal retention plate comprises a roughened inboard surface. 
     
     
         8 . The spinal fusion implant according to  claim 1 , wherein said main body is substantially solid. 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . The spinal fusion implant according to  claim 1 , wherein said main body comprises at least one opening formed therein to permit bone in-growth. 
     
     
         12 . The spinal fusion implant according to  claim 11 , wherein said at least one opening extends completely through said main body from said superior surface of said main body to said inferior surface of said main body. 
     
     
         13 . The spinal fusion implant according to  claim 11 , wherein a bone growth promoter is disposed in said at least one opening. 
     
     
         14 . The spinal fusion implant according to  claim 1 , wherein at least one of said superior surface of said main body and said inferior surface of said main body comprises at least one protrusion configured to inhibit retraction of said main body when said main body is positioned between adjacent vertebral bodies. 
     
     
         15 . (canceled) 
     
     
         16 . The spinal fusion implant according to  claim 1 , wherein said distal retention plate comprises at least one protrusion extending distally from an inboard surface of said proximal retention plate, and said proximal end of said main body comprises at least one groove;
 wherein said at least one groove receives said at least one protrusion when said distal retention plate is rotated.   
     
     
         17 . The spinal fusion implant according to  claim 1 , wherein said proximal retention plate comprises at least one protrusion extending distally from an inboard surface of said proximal retention plate, and said proximal end of said main body comprises at least one groove;
 wherein said at least one groove receives said at least one protrusion when said proximal retention plate is rotated.   
     
     
         18 . The spinal fusion implant according to  claim 1 , wherein said distal retention plate comprises two separate parts, wherein each of said two separate parts is rotatably secured to said distal end of said main body, and further wherein said two separate parts are rotatable in opposite directions relative to one another. 
     
     
         19 . The spinal fusion implant according to  claim 4 , wherein said proximal retention plate comprises two separate parts, wherein each of said two separate parts is rotatably secured to said proximal end of said main body, and further wherein said two separate parts are rotatable in opposite directions relative to one another. 
     
     
         20 . The spinal fusion implant of  claim 1 , wherein said main body comprises two independently formed sections divided from one another along a parting line that is transverse to a longitudinal axis of said main body extending between said distal end and said proximal end of said main body, said parting line being disposed substantially mid-length of said main body such that said two independently formed sections have a substantially common length. 
     
     
         21 . The spinal fusion implant of  claim 20 , further comprising:
 a longitudinally-extending bore formed in said two independently formed sections of said main body, said longitudinally-extending bore being disposed in substantial coincidence with a longitudinal axis of symmetry of said main body;   a central rod disposed in said longitudinally-extending bore;   said central rod having a first length substantially equal to said distance between said distal end and said proximal end of said main body;   said central rod comprising having two parts that are screwthreadedly secured to one another such that relative rotation between said two parts in a first direction lengthens said central rod, and relative rotation between said two parts in a second, opposite direction shortens said central rod;   wherein said two independently formed sections of said main body are disposed in abutting relation to one another when said central rod is at its first length; and   said two independently formed sections of said main body being disposed in longitudinally spaced apart relation to one another when said central rod is lengthened.   
     
     
         22 . The spinal fusion implant according to  claim 21 , further comprising a pair of substantially parallel anti-rotation rods disposed parallel to said central rod on opposite sides thereof;
 wherein said anti-rotation rods connect said proximal end of said main body to said distal end of said main body, whereby to prevent relative rotation therebetween.   
     
     
         23 - 25 . (canceled) 
     
     
         26 . The spinal fusion implant according to  claim 1 , wherein said distal end of said main body is tapered relative to said main body such that said distal end of said main body is not as thick as a central region of said main body disposed between said distal end of said main body and said proximal end of said main body. 
     
     
         27 . (canceled) 
     
     
         28 . A method for preventing movement of a first vertebral body relative to a second vertebral body, said method comprising:
 providing a spinal fusion implant, comprising:
 a main body having a distal end, a proximal end, a superior surface extending between said distal end and said proximal end, said superior surface being configured to engage a first vertebral body of a spinal joint, and an inferior surface extending between said distal end and said proximal end, said inferior surface being configured to engage a second vertebral body of a spinal joint; 
 a distal retention plate rotatably disposed adjacent to said distal end of said main body, said distal retention plate having (i) a first position wherein said distal retention plate is located within axial projections of said superior and inferior surfaces of said main body, and (ii) a second position wherein said distal retention plate extends beyond axial projections of said superior and inferior surfaces of said main body; 
 wherein said distance between said distal end of said main body and the proximal end of said main body is approximately the same as the distance between opposing cortical distal and proximal faces of the first and second vertebral bodies, wherein the opposing cortical distal and proximal faces are disposed normal to said superior surface of said main body and said inferior surface of said main body; 
 wherein said distal retention plate is in said first position when said main body is inserted into the spinal joint between the first vertebral body and the second vertebral body; and 
 wherein said distal retention plate is in said second position after said main body is inserted into the spinal joint between the first vertebral body and the second vertebral body, and said distal retention plate is disposed in said second position after said insertion, such that said distal retention plate engages the opposing cortical distal faces of the first vertebral body and the second vertebral body, whereby to inhibit retraction of said main body and hold said spinal fusion implant and adjacent vertebral bodies in a stable relationship relative to one another; 
 while said distal retention plate is disposed in said first position, inserting said main body into the spinal joint between the first vertebral body and the second vertebral body; 
 rotating said distal retention plate to said second, rotated position, such that said distal retention plate engages the opposing cortical distal face of the first vertebral body and the second vertebral body.