Vertebral interbody spacer

Abstract

An interbody spacer includes an elongated body with a maximum width between opposite side walls and a maximum height between upper and lower bearing surfaces. The interbody spacer also includes a leading end nose connecting the side walls to facilitate insertion of the interbody spacer into a disc space between vertebrae in an insertion orientation, from which the interbody device is then rotated to position the upper and lower bearing surfaces in contact with the endplates of the adjacent vertebrae. The leading end nose forms a blunt convex nose between the upper and lower bearing surfaces to maximize the bearing surface area available to contact the adjacent endplates.

1 - 25 . (canceled) 
     
     
         26 . A method for positioning an interbody spacer between vertebrae, comprising:
 providing an interbody spacer comprising a body extending along a longitudinal axis between a leading end and an opposite trailing end, the body comprising a pair of opposite lateral side walls extending between the leading and trailing ends, the body comprising opposite upper and lower surfaces each extending between the leading and trailing ends and between the side walls, the upper and lower surfaces each including a series of spaced apart projections that extend transverse to the longitudinal axis;   positioning the spacer between the vertebrae such that one of the side walls faces a superior vertebra and the other one of the side walls faces an adjacent inferior vertebra; and   rotating the spacer between the vertebrae about the longitudinal axis such that the projections of one of the top and bottom surfaces engage the superior vertebra and the projections on the other of the top and bottom surfaces engages the inferior vertebra.   
     
     
         27 . A method according to  claim 26 , wherein:
 the leading end defines a bullet-shaped nose; and   positioning the spacer between the vertebrae includes inserting the spacer into a disc space between the vertebrae such that the bullet-shaped nose leads entry of the spacer into the disc space.   
     
     
         28 . A method according to  claim 26 , wherein a corner connects each of the side walls to a respective one of the upper and lower surfaces and each of the corners is defined by an arcuate surface. 
     
     
         29 . A method according to  claim 28 , wherein a tangent of at least one of the arcuate surfaces at an intersection of the arcuate surface with the side wall is closer to lying on the side wall than a tangent of the arcuate surface at an intersection with the respective one of the upper and lower surfaces is to lying on the respective surface. 
     
     
         30 . A method according to  claim 26 , wherein:
 the body defines a mid-length plane that is orthogonal to the longitudinal axis; and   the side walls each define a continuous convexly curved profile extending from the leading end to the trailing end, the continuous convexly curved profiles defining a maximum width of the body between the side walls at a second location that is offset from the mid-length plane toward the leading end portion.   
     
     
         31 . A method according to  claim 30 , wherein the continuous convexly curved profile of each of the side walls are defined by a first arc having a first radius with the first arc extending from the trailing end to the second location, and the continuous convexly curved profile of each of the side walls is defined by a second arc having a second radius with the second arc extending from the second location to the leading end, the first radius being greater than the second radius so that the side walls converge toward the leading end. 
     
     
         32 . A method according to  claim 26 , wherein:
 the projections each have a truncated crest extending between the side walls, each of the truncated crests defining a first arc having a first radius; and   the upper and lower surfaces are each defined by a second arc having a second radius, the second radius being greater than the first radius.   
     
     
         33 . A method according to  claim 32 , wherein opposite ends of each projection are rounded from an adjacent one of the side walls to the crest of the projection to facilitate rotation of the spacer about the longitudinal axis. 
     
     
         34 . A method according to  claim 32 , wherein:
 the truncated crests of the projections on at least one of the upper and lower surfaces lie on a third arc having a third radius with the third arc extending from the leading end to the trailing end;   at least one of the upper and lower surfaces lies on a fourth arc having a fourth radius with the fourth arc extending from the leading end to the trailing end; and   the truncated crests define a maximum height of the body portion at a location that is offset toward the trailing end from a junction of the upper and lower surfaces and the leading end.   
     
     
         35 . A method according to  claim 26 , wherein:
 the upper surface is continuously curved between the leading end and the trailing end; and   the lower surface is continuously curved between the leading end and the trailing end.   
     
     
         36 . A method according to  claim 26 , wherein:
 the body defines a mid-length plane that is orthogonal to the longitudinal axis; and   the upper and lower surfaces define a maximum height between the upper and lower surfaces at a first location that is offset from the mid-length plane toward the leading end.   
     
     
         37 . A method according to  claim 36 , wherein the side walls each include an elongated slot therein that extends from the trailing end to an opposite end of the slot that is located adjacent the mid-length plane. 
     
     
         38 . A method according to  claim 36 , wherein the slots each include a height that increases from the trailing end toward the leading end. 
     
     
         39 . A method according to  claim 26 , wherein at least one of the side walls includes projections. 
     
     
         40 . A method according to  claim 26 , wherein:
 the body defines a cavity that extends between and opens at each of the upper and lower surfaces;   the side walls each include an opening extending therethrough that is in communication with the cavity; and   the method comprises inserting bone growth promoting material in the cavity prior to positioning the spacer between the vertebrae.   
     
     
         41 . A method for positioning an interbody spacer between vertebrae, comprising:
 providing an interbody spacer comprising a body extending along a longitudinal axis between a leading end and an opposite trailing end, the leading end defining a bullet-shaped nose, the body comprising a pair of opposite side walls extending between the leading and trailing ends, the side walls each defining a continuous convexly curved profile extending from the leading end to the trailing end, wherein a corner connects each of the side walls to a respective one of the upper and lower surfaces and each of the corners is defined by an arcuate surface, the body comprising an upper surface and an opposite lower surface each extending between the leading and trailing ends and between the side walls, the upper and lower surfaces being continuously curved between the leading and trailing ends, the upper and lower surfaces each including a series of spaced apart projections that extend transverse to the longitudinal axis, the body defining a cavity that extends between and opens at each of the upper and lower surfaces, the side walls each including an opening extending therethrough that is in communication with the cavity;   inserting bone growth promoting material in the cavity;   inserting the spacer into a disc space between the vertebrae such that the bullet-shaped nose leads its entry into the disc space;   positioning the spacer between the vertebrae such that one of the side walls faces a superior vertebra and the other one of the side walls faces an adjacent inferior vertebra; and   rotating the spacer between the vertebrae about the longitudinal axis such that the projections of one of the top and bottom surfaces engage the superior vertebra and the projections on the other of the top and bottom surfaces engages the inferior vertebra.   
     
     
         42 . A method for positioning an interbody spacer between vertebrae, comprising:
 providing an inserter comprising an outer member comprising an inner surface defining a passage and an outer surface engaging a handle, a distal end of the outer member comprising a pair of spaced apart fingers, the inserter comprising an inner member movably disposed within the passage,   providing an interbody spacer comprising a body extending along a longitudinal axis between a leading end and an opposite trailing end including a central receptacle, the body comprising a pair of opposite lateral side walls extending between the leading and trailing ends, the side walls each including an elongated slot therein that has a concave profile and extends from the trailing end, the body comprising an upper surface and an opposite lower surface each extending between the leading and trailing ends and between the side walls, the upper and lower surfaces each including a series of spaced apart projections that extend transverse to the longitudinal axis;   engaging the fingers with the slots to prevent rotation of the inserter relative to the spacer;   disposing a distal end of the inner member in the receptacle;   positioning the spacer between the vertebrae with the inserter such that one of the side walls faces a superior vertebra and the other one of the side walls faces an adjacent inferior vertebra; and   rotating the outer member to rotate the spacer between the vertebrae about the longitudinal axis such that the projections of one of the top and bottom surfaces engage the superior vertebra and the projections on the other of the top and bottom surfaces engages the inferior vertebra.   
     
     
         43 . A method according to  claim 42 , wherein the fingers include convexly curved facing surfaces that match the concave profile of the slots and diverge to provide an intimate fit therewith. 
     
     
         44 . A method according to  claim 42 , wherein:
 the distal end of the outer member comprises a first flange positioned between the fingers and a second flange positioned between the fingers opposite the first flange; and   the method further comprises engaging the first flange with one of the upper surface and the lower surface and engaging the second flange with the other one of the upper surface and the lower surface simultaneously with engaging the fingers with the slots.   
     
     
         45 . A method according to  claim 42 , wherein:
 the distal end of the inner member includes a first thread form and the receptacle includes a second thread form; and   engaging a distal end of the inner member in the receptacle engaging the first thread form with the second thread form.