Spinal interspace shaper
View Patent ↗A device and method for use in a vertebral spine to prepare a space between adjacent vertebral bodies to receive an implant. The device includes a shaft, and a mounting member at one end of the shaft. A working end is mounted on the mounting member and is coupled to a drive mechanism adjacent to the working end. The drive mechanism is operable to move the upper and lower cutters of the working end to create surfaces having predetermined contours in the end plate region of the adjacent vertebral bodies. A guard provides protected access to the disc space and the adjacent vertebral bodies for the working end of the bone removal device through a passageway.
1. A system for preparing a space in the human spine to receive an implant between adjacent vertebral bodies, said system comprising:
a bone removal device comprising:
a shaft having a proximal end, a distal end opposite said proximal end, and a mid-longitudinal axis therebetween;
at least a first and a second cutter sized and shaped to remove bone from the adjacent vertebral body endplates simultaneously as said first and second cutters are moved to create an implantation space, each of said first and second cutters having a leading end and an opposite trailing end, said leading ends of said first and second cutters defining a forward facing cutting area having a maximum height as measured along a line passing through said leading end of each of said first and second cutters and transverse to the mid-longitudinal axis of said shaft;
a drive element having a leading portion and a trailing portion opposite said leading portion, said leading portion of said drive element connecting to said trailing ends of said first and second cutters for moving said first and second cutters, at least a portion of said distal end of said shaft and said leading portion of said drive element each having a maximum height transverse to the mid-longitudinal axis of said shaft not greater than the maximum height of said forward facing cutting area of said first and second cutters, said at least a portion of said distal end of said shaft and said leading portion of said drive element each being located within and not extending beyond the maximum height of said forward facing cutting area of said cutters; and
a power source operably connected to said drive element; and
a guard for providing protected access to the adjacent vertebral bodies, said guard comprising a body having a leading end, a trailing end opposite said leading end, a mid-longitudinal axis therebetween, and an opening passing through said leading and trailing ends, said opening having a height and a width transverse to and greater than said height, said height of said opening being greater than the maximum height of the forward facing cutting area of said bone removal device, said opening being sized and shaped to permit said first and second cutters to pass through said body and access the vertebral body endplates.
2. The system of claim 1 , wherein said first and second cutters include teeth formed thereon to cooperatively engage said drive element, said drive element and said teeth being configured such that said first and second cutters are rotated by said drive element.
3. The system of claim 1 , wherein said first and second cutters are adapted to be rotated in opposite directions by said drive element.
4. The system of claim 1 , wherein at least one of said first and second cutters has a width, said width substantially matching the width of the nucleus pulposus of a disc space in which it is inserted.
5. The system of claim 1 , wherein said first and second cutters are inclined relative to one another.
6. The system of claim 1 , wherein said first and second cutters are driven in a reciprocating, arcuate motion by said drive element.
7. The system of claim 1 , wherein said drive element is adapted to produce a rotary movement of said first and second cutters about an axis generally perpendicular to the mid-longitudinal axis of said shaft.
8. The system of claim 1 , wherein said drive element is adapted to produce one of an oscillating rotation and a vibratory motion of said first and second cutters.
9. The system of claim 1 , wherein said guard further includes a foot plate sized and shaped to contact at least a portion of each of the adjacent vertebral bodies, said foot plate having at least one opening configured to receive a fastener adapted to secure said foot plate to the vertebral bodies.
10. The system of claim 1 , wherein said guard further comprises first and second disc penetrating extensions extending from said guard for insertion into the disc space between the adjacent vertebral bodies, each of said disc penetrating extensions having a portion for bearing against each of the adjacent end plates of the adjacent vertebral bodies, each of said portions of said disc penetrating extensions having an upper surface adapted to contact one of the adjacent end plates of the adjacent vertebral bodies and a lower surface adapted to contact the other of the adjacent end plates of the adjacent vertebral bodies, said portions of said disc penetrating extensions having a height between said upper and lower surfaces and a length sufficient to properly align and distance apart the adjacent vertebral bodies.
11. The system of claim 10 , wherein said upper and lower surfaces are parallel to each other along a substantial portion of the length of said portions.
12. The system of claim 10 , wherein said disc penetrating extensions are diametrically opposed to each other and spaced apart from one another to provide access to the adjacent vertebral bodies from within the disc space.
13. The system of claim 10 , wherein the height of said disc penetrating extensions have at least a portion that approximates the height of a normal disc space between the adjacent vertebral bodies.
14. The system of claim 10 , wherein said disc penetrating extensions have a tapered leading end to facilitate placement of said disc penetrating extensions into the disc space, said portion of said disc penetrating extensions having opposite surfaces for bearing against the end plates of the adjacent vertebral bodies, said opposite surfaces diverging away from said guard along at least a portion of their length.
15. The system of claim 10 , wherein said upper and lower surfaces converge away from said guard along at least a portion of their length.
16. The system of claim 10 , wherein said opening of said guard has an interior having a cooperating surface for guiding a corresponding cooperating surface of said first and second cutters.
17. The system of claim 1 , in combination with an implant sized and shaped to match the implantation space formed in the spine by said first and second cutters.
18. The system of claim 17 , wherein said implant is one of a spinal implant and a spacer.
19. The system of claim 1 , wherein at least a portion of said first and second cutters are separated by a space and substantially overlie one another, said drive element being configured to engage said first and second cutters outside the space separating said cutters.
20. The system of claim 1 , wherein at least a portion of said first and second cutters is operatively connected to said drive element in a plane parallel to the mid-longitudinal axis of said shaft.