Axial spinal implant and method and apparatus for implanting an axial spinal implant within the vertebrae of the spine

Abstract

Spinal implants for fusing and/or stabilizing spinal vertebrae and methods and apparatus for implanting one or more of such spinal implants axially within one or more axial bore within vertebral bodies in alignment with a visualized, trans-sacral axial instrumentation/fusion (TASIF) line in a minimally invasive, low trauma, manner are disclosed. Attachment mechanisms are provided that attach or affix or force the preformed spinal implants or rods to or against the vertebral bone along the full length of a TASIF axial bore or bores or pilot holes or at the cephalad end and/or caudal end of the TASIF axial bore or bores or pilot holes. The engagement of the vertebral body is either an active engagement upon implantation of the spinal implant into the TASIF axial bore or a passive engagement of the external surface configuration with the vertebral bone caused by bone growth about the external surface configuration. A plurality of such spinal implants can be inserted axially in the same TASIF axial bore or pilot hole or separately in a plurality of TASIF axial bores or pilot holes that extend axially and in a side-by-side relation through the vertebrae and discs, if present, between the vertebrae. Discectomies and/or vertebroblasty can be performed through the TASIF axial bore or bores or pilot holes prior to insertion of the spinal implants. Vertebroblasty is a procedure for augmentation of collapsed vertebral bodies by pumped-in materials, e.g., bone cement or bone growth materials. Materials or devices can also be delivered into the disc space to separate the adjoining vertebrae and/or into damaged vertebral bodies or to strengthen them.

What is claimed is:  
     
         1 . A method of treating a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect, the vertebrae separated by intact or damaged spinal discs, the method comprising the steps of: 
 accessing a posterior sacral position of a posterior surface of a sacral vertebra;    boring a curved posterior axial bore extending along a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies to be fused, the trans-sacral axial bore having a posterior axial bore opening through the posterior sacrum and extending cephalad through at least two vertebral bodies, comprising at least cephalad and caudal vertebral bodies, and any intervening spinal discs following the curvature of the spine cephalad from the posterior axial bore opening cephalad to the cephalad axial bore end within a lumbar vertebral body;    providing a spinal implant comprising an elongated spinal implant body formed of a bio-compatible material extending between a cephalad spinal implant body end that is dimensioned and configured to be inserted through said posterior axial bore opening and advanced in the cephalad direction to be seated in the cephalad bore end and a caudal spinal implant body portion that is dimensioned and configured with a curvature to fit the curved posterior axial bore and engage the vertebral bodies traversed by the curved posterior axial bore;    aligning the curved spinal implant body with the curvature of the curved posterior axial bore; and    inserting the curved spinal implant into the curved posterior axial bore seating the cephalad spinal implant body end within a cephalad end portion of the curved posterior axial bore traversing a cephalad vertebrae and a caudal spinal implant body portion within a caudal end portion of the curved anterior axial bore traversing a caudal vertebrae, whereby the elongated spinal implant fits within the curved posterior axial bore and extends cephalad and axially through the vertebral bodies of the series of adjacent vertebrae and any intervening spinal discs.    
     
     
         2 . The method of  claim 1 , further comprising the step of engaging at least a portion of the spinal implant body with vertebral bone exposed by the curved posterior axial bore to assist in retaining the elongated spinal implant body within the curved posterior axial bore.  
     
     
         3 . The method of  claim 2 , wherein the bone engaging step further comprises the step of providing at least one circumferential, outwardly extending, flange having a leading, in the direction of insertion, conical surface and trailing flange that engages the bone of the vertebral bodies surrounding a spinal implant body portion and inhibits caudal retraction of the spinal implant from the curved posterior axial bore through bone ingrowth about the flange within the axial bore.  
     
     
         4 . The method of  claim 3 , wherein the bone engaging step further comprises the step of providing a plurality of said circumferential, outwardly extending flanges spaced apart along the length of the spinal implant body portion.  
     
     
         5 . The method of  claim 2 , wherein the bone engaging step further comprises the step of providing an external surface configuration of the spinal implant body that is adapted to engage the vertebral body along at least a portion of the length of the spinal implant body.  
     
     
         6 . The method of  claim 2 , wherein the bone engaging step further comprises the step of providing at least one radially and outwardly extending, barb having a leading, in the direction of insertion, tapered surface and a trailing barb tip that bites into the bone of the vertebral bodies surrounding the spinal implant body portion to inhibit caudal retraction of the spinal implant from the curved posterior axial bore.  
     
     
         7 . The method of  claim 6 , wherein the bone engaging step further comprises the step of providing a plurality of said radially and outwardly extending barbs spaced apart about the spinal implant body.  
     
     
         8 . The method of  claim 2 , wherein the bone engaging step further comprises the step of providing an external surface configuration of the spinal implant body comprising a porous surface formed of a bio-compatible material having pores that accommodate bone growth into the pores to adhere the spinal implant body with vertebral bone to inhibit retraction of the spinal implant body from the curved posterior axial bore.  
     
     
         9 . The method of  claim 2 , wherein the bone engaging step further comprises the step of providing a plurality of outwardly extending, elongated flutes extending lengthwise along the spinal implant body that bite into the bone of the vertebral bodies surrounding the spinal implant body to inhibit retraction of the spinal implant body from the curved posterior axial bore.  
     
     
         10 . The method of  claim 2 , wherein the bone engaging step further comprises the step of providing at least one circumferential, outwardly extending, screw thread that engages the bone of the vertebral bodies surrounding the spinal implant body and inhibits caudal retraction of the spinal implant from the curved posterior axial bore through bone ingrowth about the screw thread within the axial bore.  
     
     
         11 . The method of  claim 1 , wherein the providing step further comprises forming the spinal implant body of a shape memory alloy extending between said cephalad spinal implant body end and said caudal spinal implant body portion that is curved along its length at an implantation temperature that facilitates its insertion into the curved posterior axial bore and that assumes a curvature upon acclimatization of the shape memory material to body temperature that tends to apply force laterally to the vertebral bodies traversed by the curved posterior axial bore to inhibit retraction of the spinal implant body from the curved posterior axial bore to effect fixation to and/or re-alignment of the vertebral bodies.  
     
     
         12 . The method of  claim 11 , wherein the providing step further comprises forming an external surface configuration of the spinal implant body that is adapted to engage the vertebral body along at least a portion of the length of the posterior axial bore extending through the series of vertebral bodies upon assumption of the second curvature after advancement of said spinal implant into the curved posterior axial bore.  
     
     
         13 . The method of  claim 11 , further comprising the step of engaging at least a portion of the spinal implant body with vertebral bone exposed by the anterior axial bore to assist in retaining the elongated spinal implant body within the curved posterior axial bore.  
     
     
         14 . The method of  claim 13 , wherein the engaging step further comprises forming an external surface configuration of the spinal implant body that is adapted to engage the vertebral body along at least a portion of the length of the curved posterior axial bore extending through the series of vertebral bodies.  
     
     
         15 . Apparatus for effecting an implantation of a spinal implant through a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising: 
 means operable from an accessed sacral position of a sacral vertebra for boring a trans-sacral axial bore extending along a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies to be fused, the trans-sacral axial bore having a caudal axial bore opening through the sacrum and extending cephalad through at least two vertebral bodies, comprising at least cephalad and caudal vertebral bodies, and any intervening spinal discs, to a cephalad bore end, the axial bore having a curvature following the curvature of the spine cephalad from the caudal axial bore opening and maintaining the curved axial bore within the sacral and vertebral bodies;    an elongated spinal implant formed of a bio-compatible material having a spinal implant body that extends between a cephalad spinal implant body end and a caudal spinal implant body end, the spinal implant body dimensioned and configured with a curvature that enables insertion into the curved axial bore through said caudal axial bore opening and advancement in the cephalad direction to seat a cephalad spinal implant body portion in the cephalad bore end and to dispose a caudal spinal implant body portion in the axial bore traversing the caudal vertebral body; and    means for inserting said elongated spinal implant into said axial bore to extend cephalad and axially through the vertebral bodies of the series of adjacent vertebrae and any intervening spinal discs.    
     
     
         16 . The apparatus of  claim 15 , wherein said spinal implant further comprises means for effecting lateral engagement of said spinal implant body with vertebral bone of at least portions of the vertebral bodies traversed by the curved axial bore.  
     
     
         17 . The apparatus of  claim 15 , wherein said spinal implant further comprises bone engaging means for engaging the vertebral bone of at least the caudal vertebral body or the cephalad vertebral body to maintain the elongated spinal implant body within the axial bore.  
     
     
         18 . The apparatus of  claim 17 , wherein the bone engaging means further comprises an external surface configuration of the caudal spinal implant body portion that is adapted to engage the caudal vertebral body along at least a portion of the length of the caudal vertebral body.  
     
     
         19 . The apparatus of  claim 15 , wherein the spinal implant body further comprises at least one circumferential, outwardly extending, screw thread that bites into the bone of the vertebral body inhibits caudal retraction of the spinal implant from the axial bore.  
     
     
         20 . The apparatus of  claim 15 , wherein the spinal implant body further comprises at least one circumferential, outwardly extending, flange having a leading, in the direction of insertion, conical surface and trailing flange that engages with the bone of the vertebral body through bone ingrowth about the flange within the axial bore and inhibits caudal retraction of the spinal implant from the axial bore.  
     
     
         21 . The apparatus of  claim 15 , wherein the spinal implant body further comprises a plurality of circumferential, outwardly extending, flanges disposed along the vertebral body, each flange having a leading, in the direction of insertion, conical surface and trailing flange that engages with the bone of the vertebral body through bone ingrowth about the flanges within the axial bore and inhibits caudal retraction of the spinal implant from the axial bore.  
     
     
         22 . The apparatus of  claim 15 , wherein the spinal implant body further comprises at least one radially and outwardly extending, barb having a leading, in the direction of insertion, tapered surface and a trailing barb tip that bites into the bone of the vertebral bodies surrounding the spinal implant body to inhibit caudal retraction of the spinal implant from the axial bore.  
     
     
         23 . The apparatus of  claim 22 , wherein the spinal implant body further comprises a plurality of radially and outwardly extending barbs disposed along the vertebral body, each barb having a leading, in the direction of insertion, tapered surface and a trailing barb tip that bites into the bone of the vertebral bodies surrounding the spinal implant body to inhibit caudal retraction of the spinal implant from the axial bore.  
     
     
         24 . The apparatus of  claim 15 , wherein the spinal implant body comprises a porous surface formed of a bio-compatible material having pores that accommodate bone growth into the pores to adhere the spinal implant body with the bone of the vertebral body and inhibit caudal retraction of the spinal implant from the axial bore.  
     
     
         25 . The apparatus of  claim 15 , wherein the spinal implant body further comprises a plurality of outwardly extending, elongated flutes extending lengthwise along at least a portion of the spinal implant body that bite into the bone of the vertebral bodies surrounding the spinal implant body portion to inhibit caudal retraction of the spinal implant from the axial bore.  
     
     
         26 . The apparatus of  claim 15 , wherein said elongated spinal implant body is formed of a shape memory alloy and possesses a first curvature at a temperature other than body temperature and a second curvature within a physiologic body temperature range to effect fixation to and/or re-alignment of the vertebral bodies.  
     
     
         27 . The apparatus of  claim 15 , wherein said elongated spinal implant body comprises an elongated rod formed of a shape memory alloy that is curved along the length or the elongated rod to a first curvature at a pre-implantation temperature that facilitates insertion of the elongated rod into the curved axial bore and that assumes a second curvature upon acclimatization of the shape memory material to body temperature that tends to apply force laterally to the vertebral bodies contacted by the elongated rod to effect fixation to and/or re-alignment of the vertebral bodies.  
     
     
         28 . The apparatus of  claim 27 , wherein the elongated rod has an external surface configuration that is adapted to engage the vertebral body along at least a portion of the length of the axial bore extending through the series of vertebral bodies upon assumption of the second curvature after advancement of said spinal implant into the curved axial bore.  
     
     
         29 . The apparatus of  claim 15 , wherein the curved axial bore extends in the cephalad direction following the curvature of the spine cephalad from a caudal axial bore opening at a posterior sacral position cephalad to the cephalad axial bore end within a lumbar vertebral body.  
     
     
         30 . The apparatus of  claim 15 , wherein the curved axial bore extends in the cephalad direction following the curvature of the spine cephalad from a caudal axial bore opening at an anterior sacral position cephalad to the cephalad axial bore end within a lumbar vertebral body.