Methods and apparatus for forming shaped axial bores through spinal vertebrae

• US 6,740,090 B1
• Filed: 11/10/2000
• Issued: 05/25/2004
• Est. Priority Date: 02/16/2000
• Status: Expired due to Term

• Current Assignee: Mis Ip Holdings LLC
• Original Assignee: TranS1 Incorporated (Baxano Surgical, Inc.)
• Inventors: Cragg, Andrew H., Kagan, Jonathan
• Primary Examiner(s): Woo, Julian W.
• Application Number:
  US09/710,369
• Time in Patent Office: 1,292 Days
• Field of Search: 606/159, 606/170, 606/180, 606/80, 606/61, 606/79, 606/82, 408/127, 407/36-38, 128/898
• US Class Current: 606/79
• CPC Class Codes: A61B 17/1617 with mobile or detachable parts
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/32002 with continuously rotating, oscillating or reciprocating cutting instruments
• CPC Class Codes: A61B 17/320725 with radially expandable cutting or abrading elements A61B17/32075 takes precedence
• CPC Class Codes: A61B 17/320758 with a rotating cutting instrument, e.g. motor driven A61B17/320725, A61B17/32075 and A61B17/320783 take precedence; for removing intra-ocular material A61F9/00763; endoscopic rotatable cutting instruments A61B17/32002
• CPC Class Codes: A61B 17/66 Alignment, compression or distraction mechanisms
• CPC Class Codes: A61B 17/70 Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull
• CPC Class Codes: A61B 17/8805 for introducing fluid filler into bone or extracting it A61B17/7097, A61B17/8833 take precedence
• CPC Class Codes: A61B 2017/00261 Discectomy
• CPC Class Codes: A61B 2017/00734 battery operated
• CPC Class Codes: A61B 2017/00867 shape memory effect
• CPC Class Codes: A61B 2017/2905 flexible
• CPC Class Codes: A61B 2017/320733 with a flexible cutting or scraping element, e.g. with a whip-like distal filament member
• CPC Class Codes: A61F 2/441 made of inflatable pockets or chambers filled with fluid, e.g. with hydrogel
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4601 for introducing bone substitute, for implanting bone graft implants or for compacting them in the bone cavity
• CPC Class Codes: A61F 2/4611 : of spinal prostheses
• CPC Class Codes: A61F 2002/2821 : Bone stimulation by electromagnetic fields or electric current for enhancing ossification
• CPC Class Codes: A61F 2002/2835 : Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30092 : using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/30291 : spirally-coiled, i.e. having a 2D spiral cross-section
• CPC Class Codes: A61F 2002/3055 : for adjusting length
• CPC Class Codes: A61F 2002/30563 : having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30566 : Helical springs
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30677 : Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30879 : Ribs
• CPC Class Codes: A61F 2002/30884 : Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30892 : parallel
• CPC Class Codes: A61F 2002/30925 : etched
• CPC Class Codes: A61F 2002/3097 : using laser
• CPC Class Codes: A61F 2002/448 : comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2210/0014 : using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2230/0091 : helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section
• CPC Class Codes: A61F 2310/00353 : Bone cement, e.g. polymethylmethacrylate or PMMA
• CPC Class Codes: A61N 5/1027 : Interstitial radiation therapy
• CPC Class Codes: Y10S 606/914 : Toolkit for installing or removing spinal positioner or stabilizer

Abstract

One or more shaped axial bore extending from an accessed posterior or anterior target point are formed in the cephalad direction through vertebral bodies and intervening discs, if present, in general alignment with a visualized, trans-sacral axial instrumentation/fusion (TASIF) line in a minimally invasive, low trauma, manner. An anterior axial instrumentation/fusion line (AAIFL) or a posterior axial instrumentation/fusion line (PAIFL) that extends from the anterior or posterior target point, respectively, in the cephalad direction following the spinal curvature through one or more vertebral body is visualized by radiographic or fluoroscopic equipment. Preferably, curved anterior or posterior TASIF axial bores are formed in axial or parallel or diverging alignment with the visualized AAIFL or PAIFL, respectively, employing bore forming tools that can be manipulated from proximal portions thereof that are located outside the patient'"'"'s body to adjust the curvature of the anterior or posterior TASIF axial bores as they are formed in the cephalad direction. Further bore enlarging tools are employed to enlarge one or more selected section of the anterior or posterior TASIF axial bore(s), e.g., the cephalad bore end or a disc space, so as to provide a recess therein that can be employed for various purposes, e.g., to provide anchoring surfaces for spinal implants inserted into the anterior or posterior TASIF axial bore(s).

Claims

1. A method for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the method comprising the steps of:

from the accessed sacral target point, boring a trans-sacral axial bore in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs;

providing a bore enlarging tool sized to fit within the trans-sacral axial bore;

from the accessed sacral target point, inserting the bore enlarging tool to a selected location along the trans-sacral axial bore; and

operating the bore enlarging tool to enlarge a section of the trans-sacral axial bore traversing a vertebral body or intervertebral disc space to form at least one recess.

2. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, whereby the cutting head and cutting head drive shaft are rotatable by operation of the cutting head motor, and deployment means for deploying the cutting head from a retracted position within the trans-sacral axial bore to a deployed position against vertebral bone or an intervertebral disc;

the inserting step further comprises advancing the cutting head in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting head from the retracted position within the trans-sacral axial bore to the deployed position against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate the cutting head and cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

3. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising a thin, flexible tube extending distally from the cutting drive shaft distal end, the tube slit lengthwise into one or more elongated cutting tool band having a cutting band edge, and deployment means extending through said cutting head drive shaft lumen to said cutting head for deflecting said one or more cutting tool band outward from a retracted position within the trans-sacral axial bore to a deployed position applying the cutting band edge against vertebral bone or an intervertebral disc to cut away vertebral bone or disc material as the cutting head is rotated;

the inserting step further comprises advancing the cutting head in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting band from the retracted position within the trans-sacral axial bore to the deployed position applying the cutting band edge against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate the cutting head and cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

4. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising a thin, flexible tube extending distally from the cutting drive shaft distal end, the tube slit lengthwise into one or more elongated cutting tool band having a cutting band edge, and a pull wire extending from a pull wire proximal end through said cutting head drive shaft lumen and through said cutting head to a pull wire distal end attached to a cutting head distal end;

the inserting step further comprises advancing the cutting head in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting head from the retracted position within the trans-sacral axial bore to the deployed position against vertebral bone or an intervertebral disc by pulling on the pull wire at or near the pull wire proximal end for expanding said one or more cutting tool band outward from its straight retracted position within the trans-sacral axial bore to a deployed position applying the cutting band edge against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate said cutting head such that the cutting band edge cuts away vertebral bone or intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess.

5. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head extending distally from the cutting drive shaft distal end to a cutting head distal end and further comprising a thin, flexible, tubular member and an elongated cutting wire extending between a cutting wire proximal end and a cutting wire distal end, the cutting wire proximal and distal ends extending into the flexible tubular member, and deployment means extending through said cutting head drive shaft lumen to said cutting head for deflecting said cutting wire outward from a retracted position within or alongside said cutting head to a deployed position extending outward from said tubular member;

the inserting step further comprises advancing the cutting head with the cutting wire in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting wire from the retracted position outward to the deployed position against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate the outwardly extending cutting wire to cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

6. The method of claim 5, wherein said thin, flexible, tubular member is slit lengthwise to form an elongated gap through the tubular member side wall, said cutting wire extends the length of the gap, the cutting wire proximal and distal ends extending into the flexible tubular member, and the deployment means is coupled with at least one of the cutting wire proximal and distal ends to effect deployment of the cutting wire outward through the gap to the deployed position.

7. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head extending distally from the cutting drive shaft distal end to a cutting head distal end and further comprising a thin, flexible, tubular member and an elongated cutting wire extending between a cutting wire proximal end and a cutting wire distal end, the cutting wire proximal and distal ends extending into the flexible tubular member, and a manipulator wire extending between manipulator wire proximal and distal ends and through said drive shaft lumen, the manipulator wire distal end coupled to said cutting wire, whereby, the manipulator wire adapted to be manipulated from at or near the manipulator wire proximal end to deploy the cutting wire outward from a retracted position within or alongside said cutting head to a deployed position extending outward from said tubular member;

the inserting step further comprises advancing the cutting head with the cutting wire in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises manipulating the manipulator wire to deploy the cutting wire from the retracted position outward to the deployed position against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate the outwardly extending cutting wire to cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

8. The method of claim 7, wherein said thin, flexible, tubular member is slit lengthwise to form an elongated gap through the tubular member side wall, said cutting wire extends the length of the gap, the cutting wire proximal and distal ends extending into the flexible tubular member, and the manipulator wire is coupled with at least one of the cutting wire proximal and distal ends to effect deployment of the cutting wire outward through the gap to the deployed position.

9. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head extending distally from the cutting drive shaft distal end to a cutting head distal end and further comprising at least one abrading cable attached to the drive shaft distal end, and means for restraining said at least one abrading cable in a restrained configuration during passage through a curved trans-sacral axial bore;

the inserting step further comprises advancing the cutting head with the restraining means restraining the at least one abrading cable in the restrained position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises releasing the abrading cable from the restraining means and operating the cutting head motor to rotate the unrestrained abrading cable against vertebral bone or an intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess.

10. The method of claim 9, wherein the at least one abrading cable is formed of a length of woven or braided metal or fabric tending to spring outward when unrestrained from a cable attachment end attached to the cutting tool distal end to a cable free end and having an abrasive surface at least at the cable free end.

11. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head extending distally from the cutting drive shaft distal end to a cutting head distal end and further comprising at least one abrading cable attached to the drive shaft distal end, and an elongated, flexible, restraining sheath having a sheath lumen extending from a sheath proximal end to a sheath distal end through which said cutting head drive shaft extends and within which said at least one abrading cable is enclosed in a restrained configuration during passage through a curved trans-sacral axial bore;

the inserting step further comprises advancing the cutting head with the at least one abrading cable retracted within the sheath lumen from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises retracting the restraining sheath proximally over the cutting tool drive shaft to expose the abrading cable and operating the cutting head motor to rotate the unrestrained abrading cable against vertebral bone or an intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess.

12. The method of claim 11, wherein the at least one abrading cable is formed of a length of woven or braided metal or fabric tending to spring outward when unrestrained from a cable attachment end attached to the cutting tool distal end to a cable free end and having an abrasive surface at least at the cable free end.

13. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising an elongated tool housing extending axially and distally from the cutting drive shaft distal end to a tool housing distal end and having a cross-bore extending diametrically through the axis of the elongated tool housing, at least one cutting blade having a cutting edge mounted within the cross-bore, and means for effecting movement of the cutting blade between a retracted position of the cross-bore with the cutting edge retracted and an a deployed position of the cross-bore with the cutting edge extended outwardly from the cutting tool drive shaft;

the inserting step further comprises advancing the cutting head with the cutting blade in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting blade from the retracted position to the deployed position thereby applying the cutting edge against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate the cutting blade and cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

14. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising an elongated housing extending axially and distally from the cutting drive shaft distal end to a housing distal end and having a cross-bore extending diametrically through the axis of the elongated housing, a pair of cutting blades each having a cutting edge, the cutting blades mounted in said cross-bore with the cutting edges disposed in opposed radial directions, and means for effecting movement of the cutting blades between retracted positions of the cross-bore with the cutting edges retracted and deployed positions of the cross-bore with the cutting edges extended outwardly from the cutting tool housing;

the inserting step further comprises advancing the cutting head with the cutting blades maintained in the retracted position frorn the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting blades outward from the retracted positions to apply the cutting edges against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate said cutting blades such that the cutting blade edges cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

15. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising an elongated cutting head housing extending axially and distally from the cutting drive shaft distal end to a housing distal end and having a cross-bore extending diametrically through the axis of the elongated housing, a pair of cutting blades each having a cutting edge, the cutting blades mounted in said cross-bore with the cutting edges disposed in opposed radial directions, means for supporting the cutting blade within the cross-bore; and

a twist wire extending from a twist wire proximal end through said cutting head drive shaft lumen and through said cutting head housing to a twist wire distal end attached to the cutting blades;

the inserting step further comprises advancing the cutting head with the cutting blades maintained in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting blades outward from the retracted positions to the deployed positions to apply the cutting edges against vertebral bone or an intervertebral disc by twisting on the twist wire at or near the twist wire proximal end and operating the cutting head motor to rotate said cutting blade such that the cutting blade edge cuts away vertebral bone or intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess.

16. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising a cutting head housing extending distally from the cutting drive shaft distal end, a cutting blade having a terminal cutting edge and a blade proximal portion mounted to the housing by a distal hinge mechanism enabling movement of the cutting blade between an axially aligned retracted position and a pivoted position, and means coupled to said blade proximal portion for effecting movement of the cutting blade about the hinge mechanism between the axially aligned retracted position and the pivoted position;

the inserting step further comprises advancing the cutting head with the cutting blade in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises pivoting the cutting blade about the hinge mechanism from the retracted position to the deployed position to apply the cutting edge against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate said cutting head such that the cutting band edge cuts away vertebral bone or intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess.

17. The method of claim 16, wherein the providing step further comprises:

providing an elongated, flexible, sheath having a sheath lumen extending from a sheath proximal end to a sheath distal end through which said cutting head drive shaft extends and within which said cutting blade is enclosed in a protective configuration during passage through a curved trans-sacral axial bore.

18. The method of claim 1, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft having a drive shaft lumen extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, the cutting head further comprising a cutting head housing extending distally from the cutting drive shaft distal end, a cutting blade having a terminal cutting edge and a blade proximal portion mounted to the cutting head housing by a distal hinge mechanism enabling movement of the cutting blade between an axially aligned retracted position and a pivoted position, and a tip deflection wire extending through said drive shaft lumen to a proximal tip deflection wire end and a distal tip deflection wire end coupled to said blade proximal portion for effecting movement of the cutting blade about the hinge mechanism between the axially aligned retracted position and the pivoted position;

the inserting step further comprises advancing the cutting head with the cutting blade in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises pushing said tip deflection wire at or near the tip deflection wire proximal end to pivot the cutting blade about the hinge mechanism from the retracted position to the deployed position to apply the cutting edge against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate said cutting head such that the cutting band edge cuts away vertebral bone or intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess.

19. The method of claim 18, wherein the providing step further comprises:

providing an elongated, flexible, restraining sheath having a sheath lumen extending from a sheath proximal end to a sheath distal end through which said cutting head drive shaft extends and within which said cutting blade is enclosed in a restrained configuration during passage through a curved trans-sacral axial bore.

20. The method of claim 1, wherein the boring step further comprises the steps of:

providing a boring assembly comprising a boring head capable of being imaged at the distal end of a flexible boring drive shaft and a directional control mechanism for adjusting a boring angle of the boring head;

imaging the boring head and the vertebrae;

while observing the imaged boring head and vertebrae, advancing the boring head from the point of penetration in alignment with the axial instrumentation/fusion line through the vertebral bodies and any intervening discs; and

during advancement, adjusting the boring angle of the boring head to follow the curvature of the axial instrumentation/fusion line to form a curved trans-sacral axial bore.

21. The method of claim 20, wherein:

the providing step further comprises providing a counterboring tool assembly comprising an elongated, flexible, cutting head drive shaft capable of bending to follow the curved trans-sacral axial bore extending between cutting head drive shaft proximal and distal ends, a cutting head capable of being imaged extending distally from the cutting head drive shaft distal end;

a cutting head motor coupled to the cutting head drive shaft proximal end, whereby the cutting head and cutting head drive shaft are rotatable by operation of the cutting head motor, and deployment means for deploying the cutting head from a retracted position within the trans-sacral axial bore to a deployed position against vertebral bone or an intervertebral disc;

the inserting step further comprises advancing the cutting head in the retracted position from the point of insertion through the trans-sacral axial bore to a selected location along the trans-sacral axial bore; and

the operating step further comprises deploying the cutting head from the retracted position within the trans-sacral axial bore to the deployed position against vertebral bone or an intervertebral disc and operating the cutting head motor to rotate the cutting head and cut away vertebral bone or disc material to enlarge the section of the trans-sacral axial bore to form at least one recess.

22. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged;

deployment means for deploying the cutting head from a retracted position fitting within the trans-sacral axial bore to a deployed position against vertebral bone or an intervertebral disc;

an elongated flexible cutting head drive shaft extending between a drive shaft proximal end and a drive shaft distal end, the cutting head mounted to the drive shaft distal end, the deployment means enabling advancement of the drive shaft with the cutting head in the retracted position from the point of insertion through the trans-sacral axial bore to the selected location along the trans-sacral axial bore; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the deployed cutting head to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess;

wherein;

the cutting head further comprises a thin, flexible tube extending distally from the cutting drive shaft distal end, the tube slit lengthwise into at least one elongated cutting tool band having a cutting band edge; and

the deployment means extending through said cutting head drive shaft lumen to said cutting head deflects said one or more cutting tool band outward from a retracted position within the trans-sacral axial bore to a deployed position applying the cutting band edge against vertebral bone or an intervertebral disc to cut away vertebral bone or disc material as the cutting head is rotated.

23. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising a thin, flexible, tube extending distally from the cutting drive shaft distal end to a cutting head distal end, the tube slit lengthwise into one or more elongated cutting tool band having a cutting band edge;

a pull wire extending from a pull wire proximal end through said cutting head drive shaft lumen and through said cutting head to a pull wire distal end attached to the cutting head distal end that expands said one or more cutting tool band outward from its straight retracted position within the trans-sacral axial bore to a deployed position applying the cutting band edge against vertebral bone or an intervertebral disc when the pull wire is pulled proximally at or near the pull wire proximal end; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the cutting edge of the outwardly expanded band to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

24. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising a thin, flexible, tubular member extending distally from the cutting drive shaft distal end to a cutting head distal end and an elongated cutting wire extending between a cutting wire proximal end and a cutting wire distal end, the cutting wire proximal and distal ends extending into the flexible tubular member;

deployment means extending through said cutting head drive shaft lumen to said cutting head for deploying said cutting wire outward from a retracted position within or alongside said cutting head to a deployed position extending outward from said tubular member; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting wire to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

25. The apparatus of claim 24, wherein said thin, flexible, tubular member is slit lengthwise to form an elongated gap through the tubular member side wall, said cutting wire extends the length of the gap, the cutting wire proximal and distal ends extending into the flexible tubular member, and the deployment means is coupled with at least one of the cutting wire proximal and distal ends to effect deployment of the cutting wire outward through the gap to the deployed position.

26. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising a thin, flexible, tubular member extending distally from the cutting drive shaft distal end to a cutting head distal end and an elongated cutting wire extending between a cutting wire proximal end and a cutting wire distal end, the cutting wire proximal and distal ends extending into the flexible tubular member;

a manipulator wire extending between manipulator wire proximal and distal ends and through said drive shaft lumen, the manipulator wire distal end coupled to said cutting wire, whereby, the manipulator wire adapted to be manipulated from at or near the manipulator wire proximal end to deploy the cutting wire outward from a retracted position within or alongside said cutting head to a deployed position extending outward from said tubular member; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting wire to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

27. The apparatus of claim 26, wherein said thin, flexible, tubular member is slit lengthwise to form an elongated gap through the tubular member side wall, said cutting wire extends the length of the gap, the cutting wire proximal and distal ends extending into the flexible tubular member, and the manipulator wire is coupled with at least one of the cutting wire proximal and distal ends to effect deployment of the cutting wire outward through the gap to the deployed position.

28. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising at least one abrading cable attached to the drive shaft distal end;

deployment means for restraining said at least one abrading cable in a restrained configuration during passage through a curved trans-sacral axial bore; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the unrestrained abrading cable against vertebral bone or an intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess;

wherein the at least one abrading cable is formed of a length of woven or braided metal or fabric tending to spring outward when unrestrained from a cable attachment end attached to the cutting tool distal end to a cable free end and having an abrasive surface at least at the cable free end.

29. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising at least one abrading cable attached to the drive shaft distal end;

an elongated, flexible, restraining sheath having a sheath lumen extending from a sheath proximal end to a sheath distal end through which said cutting head drive shaft extends and within which said at least one abrading cable is enclosed in a restrained configuration during passage through a trans-sacral axial bore; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the unrestrained abrading cable against vertebral bone or an intervertebral disc to enlarge the section of the trans-sacral axial bore to form at least one recess;

wherein the at least one abrading cable is formed of a length of woven or braided metal or fabric tending to spring outward when unrestrained from a cable attachment end attached to the cutting tool distal end to a cable free end and having an abrasive surface at least at the cable free end.

30. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising an elongated tool housing extending axially and distally from the cutting drive shaft distal end to a tool housing distal end and having a cross-bore extending diametrically through the axis of the elongated tool housing, at least one cutting blade having a cutting edge mounted within the cross-bore;

deployment means for effecting movement of the cutting blade between a retracted position of the cross-bore with the cutting edge retracted and an a deployed position of the cross-bore with the cutting edge extended outwardly from the cutting tool drive shaft; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting edge to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

31. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising an elongated tool housing extending axially and distally from the cutting drive shaft distal end to a tool housing distal end and having a cross-bore extending diametrically through the axis of the elongated tool housing, a pair of cutting blades each having a cutting edge, the cutting blades mounted in said cross-bore with the cutting edges disposed in opposed radial directions;

deployment means for effecting movement of the cutting blades between a retracted position of the cross-bore with the cutting edges retracted and an a deployed position of the cross-bore with the cutting edges extended outwardly from the cutting tool drive shaft; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting edges to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

32. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising an elongated tool housing extending axially and distally from the cutting drive shaft distal end to a tool housing distal end and having a cross-bore extending diametrically through the axis of the elongated tool housing, at least one cutting blade having a cutting edge mounted within the cross-bore;

a twist wire extending from a twist wire proximal end through said cutting head drive shaft lumen and through said cutting head housing to a twist wire distal end attached to the cutting blades for effecting movement of the cutting blade between a retracted position of the cross-bore with the cutting edge retracted and an a deployed position of the cross-bore with the cutting edge extended outwardly from the cutting tool drive shaft; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting edge to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

33. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature off the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising a cutting head housing extending distally from the cutting drive shaft distal end, a cutting blade having a terminal cutting edge and a blade proximal portion, and a distal hinge mechanism mounted between the housing and the blade proximal portion enabling movement of the cutting blade between an axially aligned retracted position and a pivoted position;

deployment means coupled to said blade proximal portion for effecting movement of the cutting blade about the hinge mechanism between the axially aligned retracted position and the pivoted position extending the cutting blade edge outwardly from the cutting tool drive shaft; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting blade edge to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

34. The apparatus of claim 33, further comprising an elongated, flexible, sheath having a sheath lumen extending from a sheath proximal end to a sheath distal end through which said cutting head drive shaft extends and within which said cutting blade is enclosed in a protective configuration during passage through the trans-sacral axial bore.

35. Apparatus for providing access to a series of adjacent vertebrae located within a human lumbar and sacral spine having an anterior aspect, a posterior aspect and an axial aspect from an anterior or posterior sacral target point of a sacral vertebra in alignment with a visualized, axial instrumentation/fusion line extending in said axial aspect through the series of adjacent vertebral bodies, wherein the axial aspect is curved in the posterior-anterior plane due to curvature of the spinal column, the vertebrae separated by intact or damaged spinal discs, the apparatus comprising:

boring means for boring a trans-sacral axial bore from the accessed sacral target point in alignment with said axial instrumentation/fusion line cephalad and axially through the vertebral bodies of said series of adjacent vertebrae and any intervertebral spinal discs; and

a bore enlarging tool sized to fit within the trans-sacral axial bore adapted to be inserted from the accessed sacral target point to a selected location along the trans-sacral axial bore, and operable to enlarge a section of the trans-sacral axial bore within a vertebral body to form at least one recess therein;

wherein the bore enlarging tool further comprises a counterboring tool assembly comprising;

an elongated flexible cutting head drive shaft having a drive shaft lumen extending between a drive shaft proximal end and a drive shaft distal end;

a cutting head capable of cutting away bone or intervertebral disc and being remotely imaged mounted to the drive shaft distal end, the cutting head further comprising a cutting head housing extending distally from the cutting drive shaft distal end, a cutting blade having a terminal cutting edge and a blade proximal portion, and a distal hinge mechanism mounted between the housing and the blade proximal portion enabling movement of the cutting blade between an axially aligned retracted position and a pivoted position;

a tip deflection wire extending through said drive shaft lumen to a proximal tip deflection wire end and a distal tip deflection wire end coupled to said blade proximal portion for effecting movement of the cutting blade about the hinge mechanism between the axially aligned retracted position and the pivoted position; and

a cutting head motor attached to the drive shaft proximal end operable to rotate the outwardly deployed cutting blade edge to cut away vertebral bone or disc material thereby enlarging the section of the trans-sacral axial bore and forming at least one recess.

36. The apparatus of claim 35, further comprising an elongated, flexible, restraining sheath having a sheath lumen extending from a sheath proximal end to a sheath distal end through which said cutting head drive shaft extends and within which said cutting blade is enclosed in a restrained configuration during passage through a curved trans-sacral axial bore.