Expandable intervertebral spacer

• US 7,621,950 B1
• Filed: 01/27/2000
• Issued: 11/24/2009
• Est. Priority Date: 01/27/1999
• Status: Expired due to Fees

• Current Assignee: Kyphon SARL (Medtronic Plc)
• Original Assignee: Kyphon SARL (Medtronic Plc)
• Inventors: Shenhav, Boaz, Globerman, Oren, Shavit, Ronen
• Primary Examiner(s): PREBILIC, PAUL B
• Application Number:
  US09/890,172
• Time in Patent Office: 3,589 Days
• Field of Search: 623/1.1, 623/1.2, 623/1.15, 623/17.11, 623/17.16, 623/23.44, 623/23.45, 623/23.47, 606/237, 606/594, 411/32, 411/33, 411/34, 411/37, 411/38
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/00234 for minimally invasive surgery A61B17/0218, A61B17/0469, A61B17/12013, A61B17/1285, A61B17/29, A61B17/320016 take precedence
• CPC Class Codes: A61B 17/1637 Hollow drills or saws producing a curved cut, e.g. cylindrical A61B10/025, A61B17/1695 take precedence
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/22032 having inflatable gripping elements balloon catheters A61M25/10
• CPC Class Codes: A61B 17/7266 with fingers moving radially outwardly
• CPC Class Codes: A61B 2017/00261 Discectomy
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61B 2017/22034 for gripping the obstruction or the tissue part from inside
• CPC Class Codes: A61B 2017/320004 abrasive
• CPC Class Codes: A61B 2017/320008 Scrapers
• CPC Class Codes: A61B 2017/320048 Balloon dissectors
• CPC Class Codes: A61F 2/02 Prostheses implantable into the body closure means for urethra or rectum or for artificial body openings therefor A61F2/0004
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• 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 2/446 : having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4603 : for insertion or extraction of endoprosthetic joints or of accessories thereof
• CPC Class Codes: A61F 2/4611 : of spinal prostheses
• CPC Class Codes: A61F 2/4657 : Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2/48 : Operating or control means, e.g. from outside the body, control of sphincters
• CPC Class Codes: A61F 2002/0086 : for preferentially controlling or promoting the growth of specific types of cells or tissues of bone tissue onto implantable joints A61F2002/3093
• CPC Class Codes: A61F 2002/009 : for hindering or preventing attachment of biological tissue of bone tissue onto implantable joints A61F2002/30932
• CPC Class Codes: A61F 2002/2817 : Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• 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 2002/30004 : the prosthesis being made from materials having different values of a given property at different locations within the same prosthesis
• CPC Class Codes: A61F 2002/30014 : differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2002/30052 : differing in electric or magnetic properties
• CPC Class Codes: A61F 2002/30079 : magnetic
• CPC Class Codes: A61F 2002/30082 : radioactive
• CPC Class Codes: A61F 2002/30092 : using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/30113 : circular
• CPC Class Codes: A61F 2002/3013 : figure-"8"- or hourglass-shaped
• CPC Class Codes: A61F 2002/30131 : horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30136 : undulated or wavy, e.g. serpentine-shaped or zigzag-shaped
• CPC Class Codes: A61F 2002/30153 : rectangular
• CPC Class Codes: A61F 2002/30154 : square
• CPC Class Codes: A61F 2002/30156 : triangular
• CPC Class Codes: A61F 2002/30158 : trapezoidal
• CPC Class Codes: A61F 2002/30224 : cylindrical
• CPC Class Codes: A61F 2002/30235 : tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30291 : spirally-coiled, i.e. having a 2D spiral cross-section
• CPC Class Codes: A61F 2002/30324 : differing in thickness
• CPC Class Codes: A61F 2002/30326 : differing in height or in length
• CPC Class Codes: A61F 2002/30327 : differing in diameter
• CPC Class Codes: A61F 2002/30329 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30405 : made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30451 : soldered or brazed or welded
• CPC Class Codes: A61F 2002/30462 : retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2002/30484 : Mechanically expandable devices located on the first prosthetic part for locking into or onto the second prosthetic part
• CPC Class Codes: A61F 2002/30485 : plastically deformable
• CPC Class Codes: A61F 2002/30495 : using a locking ring
• CPC Class Codes: A61F 2002/305 : Snap connection
• CPC Class Codes: A61F 2002/30507 : using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/3052 : unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30545 : for adjusting a diameter
• CPC Class Codes: A61F 2002/30546 : for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2002/3055 : for adjusting length
• CPC Class Codes: A61F 2002/30579 : with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30594 : slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30617 : Visible markings for adjusting, locating or measuring
• CPC Class Codes: A61F 2002/30668 : Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61F 2002/3067 : for data transfer
• 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 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30892 : parallel
• CPC Class Codes: A61F 2002/30906 : shot- sand- or grit-blasted
• CPC Class Codes: A61F 2002/3093 : for promoting ingrowth of bone tissue
• CPC Class Codes: A61F 2002/30932 : for retarding or preventing ingrowth of bone tissue
• CPC Class Codes: A61F 2002/30971 : Laminates, i.e. layered products
• CPC Class Codes: A61F 2002/4415 : elements of the prosthesis being arranged in a chain like manner
• 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 2002/4485 : comprising three or more adjacent spinal implants
• CPC Class Codes: A61F 2002/4619 : for extraction
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4635 : using minimally invasive surgery
• CPC Class Codes: A61F 2002/4638 : Tools for performing screwing, e.g. nut or screwdrivers, or particular adaptations therefor
• CPC Class Codes: A61F 2002/4649 : Bone graft or bone dowel harvest sites
• CPC Class Codes: A61F 2002/4658 : for measuring dimensions, e.g. length
• CPC Class Codes: A61F 2002/4677 : using a guide wire
• CPC Class Codes: A61F 2210/0019 : operated at only one temperature whilst inside or touching the human body, e.g. constrained in a non-operative shape during surgery, another temperature only occurring before the operation
• CPC Class Codes: A61F 2210/0028 : cooled
• CPC Class Codes: A61F 2210/009 : magnetic
• CPC Class Codes: A61F 2210/0095 : radioactive
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2220/0075 : sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2230/0004 : Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0006 : circular
• CPC Class Codes: A61F 2230/001 : Figure-8-shaped, e.g. hourglass-shaped
• CPC Class Codes: A61F 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0021 : square
• CPC Class Codes: A61F 2230/0023 : triangular
• CPC Class Codes: A61F 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0091 : helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section
• CPC Class Codes: A61F 2240/001 : Designing or manufacturing processes
• CPC Class Codes: A61F 2250/0001 : Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61F 2250/0002 : for data transfer
• CPC Class Codes: A61F 2250/0007 : for adjusting length
• CPC Class Codes: A61F 2250/001 : for adjusting a diameter
• CPC Class Codes: A61F 2250/0012 : for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2250/0014 : having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
• CPC Class Codes: A61F 2250/0018 : differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2250/0036 : differing in thickness
• CPC Class Codes: A61F 2250/0037 : differing in height or in length
• CPC Class Codes: A61F 2250/0039 : differing in diameter
• CPC Class Codes: A61F 2250/0043 : differing in electric properties, e.g. in electrical conductivity, in galvanic properties
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• CPC Class Codes: A61F 2250/0097 : Visible markings, e.g. indicia
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: C25F 3/22 : of heavy metals
• CPC Class Codes: Y10S 606/91 : Polymer

Abstract

An expandable spacer, comprising: an axial tube having a surface, a proximal end and a distal end and a length, wherein, said surface defines a plurality of slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said surface and define a geometry of an expanded spacer. Preferably the spacer is adapted to be inserted between two spinal vertebrae of a human.

Claims

1. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein a trans-axial cross-section diameter of said expanded geometry varies along an axis of said expanded geometry; and

wherein said cross-section is rectangular and wherein said cross-section diameter increases along said expanded geometry axis.

2. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, said spacer further comprising a ratchet mechanism to maintain said spacer in an expanded configuration.

3. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, said spacer further comprising at least one portion of said spacer that prevents axial contraction of said spacer, wherein said at least one portion comprises a strip that folds and forms a thickness between two opposing sides of said spacer, preventing the opposing sides from meeting.

4. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is formed of a combination of distinct zones of different materials.

5. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is formed of a super-elastic material, which is super-elastically deformed by an extension deformation.

6. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is adapted to axially deform only under axial forces of over 20 Kg force.

7. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is adapted to axially deform only under axial forces of over 30 Kg force.

8. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is adapted to axially deform only under axial forces of over 50 Kg force.

9. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is adapted to axially deform only under axial forces of over 70 Kg force.

10. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two axially displaced extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer is adapted to axially deform only under axial forces of over 90 Kg force.

11. An expandable spacer, comprising:

an axial tube having a surface provided along an initial contour, a proximal end, a distal end and a length,

wherein, said surface defines a plurality of axially displaced slits, said plurality of slits defining at least two extensions, such that when said tube is axially compressed, said extensions extend out of said initial contour and define a geometry of an expanded spacer;

wherein when the tube is axially compressed, the at least two extensions have respective peaks farthest radially from the tube, the peaks of the extensions being separated from each other along the tube axis by portions of said surface situated radially inwards of said peaks in the axially compressed configuration;

wherein said spacer is adapted for support of two vertebral plates on either side of the spacer, and

wherein said spacer comprises at least one portion that prevents axial contraction of said spacer, the at least one portion including a pair of tabs that abut when the spacer is axially contracted or a strip that folds and forms a thickness between two opposing sides of said spacer, preventing the opposing sides from meeting.

12. A spacer according to claim 11, wherein said at least two extensions comprises at least three extensions, which three extensions extend in at least three different directions from said tube.

13. A spacer according to claim 11, wherein said at least two extensions comprises at least four extensions, which four extensions extend in at least four different directions from said tube.

14. A spacer according to claim 11, wherein said slits are straight.

15. A spacer according to claim 11, wherein said slits are curved.

16. A spacer according to claim 11, wherein said slits are narrow.

17. A spacer according to claim 11, wherein said slits are substantially parallel to said tube axis.

18. A spacer according to claim 11, wherein said slits are not parallel to said tube axis.

19. A spacer according to claim 11, wherein said slits are arranged in pairs of same length.

20. A spacer according to claim 11, wherein slits associated with one extension axially overlap slits associated with a second, axially displaced, extension.

21. A spacer according to claim 11, wherein said proximal end of said tube defines a proximal end-cap, which end-cap extends outside of a volume defined by the geometry of said extended extensions.

22. A spacer according to claim 11, wherein said distal end of said tube defines a distal end-cap, which end-cap extends outside of a volume defined by the geometry of said extended extensions.

23. A spacer according to claim 21, wherein at least one of said extensions is flush with said proximal end of said tube.

24. A spacer according to claim 21, wherein at least one of said extensions is flush with said distal end of said tube.

25. A spacer according to claim 11, further comprising at least one spur axially extending from said spacer, to engage tissue adjacent said spacer.

26. A spacer according to claim 25, wherein said at least one spur comprises at least two spurs axially extending from said spacer.

27. A spacer according to claim 11, further comprising an inner bolt.

28. A spacer according to claim 27, wherein said inner bolt has a smooth exterior.

29. A spacer according to claim 27, wherein said inner bolt has a threaded exterior.

30. A spacer according to claim 27, wherein said bolt has a head, which head locks against at least one end of said tube, to prevent axial expansion of said tube, wherein said head comprises at least one protrusion extending from said head toward said tube, to engage said tube.

31. A spacer according to claim 11, wherein at least one of the extensions is designed to carry greater stress and has an increased strength over another extension, wherein said spacer comprises a plurality of segments, each segment defining one or more extensions that extend from said spacer;

and

wherein said segments comprises at least two segment types, each segment type defining extensions that extend in different directions relative to said tube, wherein said two segment types comprise a horizontal segment defining two extensions that extend along a line and a segment defining four extensions that extend at about ±

45°

to said two extensions.

32. A spacer according to claim 11, wherein a trans-axial cross-section diameter of said expanded geometry varies along an axis of said expanded geometry;

and

wherein said cross-section is rectangular and wherein said cross-section diameter increases along said expanded geometry axis.

33. A spacer according to claim 11, wherein said spacer further comprising a ratchet mechanism to maintain said spacer in an expanded configuration.

34. A spacer according to claim 11, wherein said spacer further comprising at least one protrusion on at least one of said extensions, to prevent collapsing of said extension.

35. A spacer according to claim 11, wherein the at least one portion includes at least one pair of tabs that prevent axial contraction.

36. A spacer according to claim 11, wherein said spacer is adapted to axially deform only under axial forces of over 20 Kg force.

37. A spacer according to claim 11, wherein said spacer is adapted to axially deform only under axial forces of over 30 Kg force.

38. A spacer according to claim 11, wherein said spacer is adapted to axially deform only under axial forces of over 50 Kg force.

39. A spacer according to claim 11, wherein said spacer is adapted to axially deform only under axial forces of over 70 Kg force.

40. A spacer according to claim 11, wherein said spacer is adapted to axially deform only under axial forces of over 90 Kg force.

41. A spacer according to claim 11, wherein said spacer is adapted to remain expanded in a vertebra of an active human, when placed with the tube axis perpendicular to a spine of said human.

42. A spacer according to claim 11, wherein said spacer is coated with a bio-active coating.

43. A spacer according to claim 42, wherein said bio-active coating retards bone ingrowth.

44. A spacer according to claim 42, wherein said bio-active coating promotes bone ingrowth.

45. A spacer according to claim 11, wherein said spacer comprises at least one protrusion on at least one of said extensions, to prevent collapsing of said extension.

46. A spacer according to claim 11, wherein said spacer is formed of a super-elastic material, which is super-elastically deformed by an extension deformation.

47. A spacer according to claim 11, wherein said spacer is formed of a combination of distinct zones of different materials.

48. A spacer according to claim 11, wherein a plurality of annealed locations are provided on said spacer to assist in expansion of said spacer.

49. A spacer according to claim 11, wherein at least one of said extensions comprises at least four legs that are coupled by an extension top.

50. A spacer according to claim 11, said spacer further comprising at least one protrusion on at least one of said extensions, to interlock said at least two extensions.

51. A spacer according to 11, wherein said slits are arranged in pairs of different lengths.