Expandable implant for inter-vertebral stabilization, and a method of stabilizing vertebrae

• US 6,520,991 B2
• Filed: 04/09/2001
• Issued: 02/18/2003
• Est. Priority Date: 05/11/1999
• Status: Expired due to Fees

• Current Assignee: Donald R. Huene
• Original Assignee: Donald R. Huene
• Inventors: Huene, Donald R.
• Primary Examiner(s): Willse, David H.
• Assistant Examiner(s): Blanco, Javier G.
• Application Number:
  US09/827,916
• Publication Number:
  US 20020022887A1
• Time in Patent Office: 680 Days
• Field of Search: 623/17-1-
• US Class Current: 623/17.11
• CPC Class Codes: A61F 2/30721 Accessories
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4601 for introducing bone substitute, for implanting bone graft implants or for compacting them in the bone cavity
• 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 2/4637 for connecting or disconnecting two parts of a prosthesis
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• 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 2002/30125 elliptical or oval
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30481 using a locking clip
• CPC Class Codes: A61F 2002/30495 using a locking ring
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30537 adjustable
• 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 2002/30604 : modular
• CPC Class Codes: A61F 2002/30772 : Apertures or holes, e.g. of circular cross section
• 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 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30886 : externally-threaded
• 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 2002/4627 : 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 2002/4638 : Tools for performing screwing, e.g. nut or screwdrivers, or particular adaptations therefor
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0008 : elliptical or oval
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0004 : adjustable
• 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

Abstract

An expandable intervertebral implant for stabilizing adjacent vertebrae includes first and second opposed and operatively connected shells. Each one of the shells has a plurality of engaging members that are interdigitated with a corresponding plurality of engaging members of another of the shells. The implant also includes at least one extrusion opening and a cavity for containing osteogenic material. As one shell is moved relative to the other shell with a threaded actuator operatively connecting the shells, a volume of the cavity decreases and osteogenic material is extruded through the extrusion opening. A cross section of the implant at one or both ends thereof has a curvalinear shoulder for improved support of the vertebrae during bony growth and fusion of the vertebrae.

Claims

1. An expandable intervertebral implant adapted to be inserted at least partially into vertebrae or in between two vertebrae, and adapted to be secured thereto by expansion, comprising:

a first shell having a first end and a plurality of engaging members extensible from the implant for engagement with cancellous bone tissue of a vertebra, said engaging members axially extending from said first end, a cross section of said first shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra;

a second shell operatively connected to said first shell and having a second end with at least one bearing surface engageable with said engaging members, a cross section of said second shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra, said first and second shells cooperating to form a cavity delimited by inner surfaces thereof; and

at least one extrusion opening in at least one of said first and second shells, wherein movement of said second shell with respect to said first shell causes expansion of the implant and at least partial extrusion of material contained in the cavity through said extrusion opening.

2. The implant according to claim 1, wherein:

said cavity has a volume that varies depending upon a position of said first shell with respect to said second shell.

3. The implant according to claim 1, further comprising:

an actuator adapted to move said second shell with respect to said first shell.

4. The implant according to claim 3, wherein:

said actuator has a third end threadedly connected to at least one of said first and second shells, said actuator being responsive to torque applied in a first predetermined direction to move said second shell toward said first shell and expand the implant thereby at least partially extruding material contained within said cavity.

5. The implant according to claim 4, wherein:

said actuator is responsive to torque in a second predetermined direction to cause said second shell to move away from said first shell and radially contract the implant.

6. The implant according to claim 1, wherein:

an osteogenic material is contained within said cavity and is extruded during expansion of the implant.

7. The implant according to claim 1, wherein:

said at least one bearing surface engages said engaging members and urges said engaging members radially outward to effect expansion of the implant and extrusion of the material contained within said cavity when said second shell is moved with respect to said first shell.

8. The implant according to claim 1, wherein:

said first shell includes a plurality of bearing surfaces on said first end.

9. The implant according to claim 8, wherein:

said second shell includes a plurality of engaging members axially extending from said second end, said engaging members of said first shell being interdigitated with said engaging members of said second shell.

10. The implant according to claim 9, wherein:

said at least one bearing surface of said second shell urges said engaging members of said first shell radially outward and said plurality of bearing surfaces of said first shell urge said engaging members of said second shell radially outward to effect expansion of the implant when said second shell is moved with respect to said first shell.

11. The implant according to claim 10, wherein said engaging members of said first and second shells are circumferentially spaced about a first axis extending from said first end to said second end.

12. The implant according to claim 9, wherein:

said engaging members of said first and second shells have a common length.

13. The implant according to claim 10, wherein:

each of said engaging members of said first and second shells has a beveled distal end.

14. The implant according to claim 13, wherein:

said bearing surfaces of said first and second shells are beveled so that movement of said second shell toward said first shell effects effects radially outward extension of said engaging members of said first and second shells.

15. An expandable intervertebral implant adapted to be inserted at least partially into vertebrae or in between two vertebrae, and adapted to be secured thereto by expansion, comprising:

a first shell having a first end and a plurality of engaging members extensible from the implant for engagement with cancellous bone tissue of a vertebra, said engaging members axially extending from said first end, a cross section of said first shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra;

a second shell operatively connected to said first shell and having a second end with at least one bearing surface engageable with said engaging members, cross section of said second shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra, said first and second shells cooperating to form a cavity delimited by inner surfaces thereof;

an actuator adapted to move said second shell with respect to said first shell, said actuator extending through a bore in one of said first and second shells and having a head and a third end, said head bearing against said one shell, said third end threadedly connected to another of said first and second shells; and

at least one extrusion opening in at least one of said first and second shells, wherein movement of said second shell with respect to said first shell causes expansion of the implant and at least partial extrusion of material contained in the cavity through said extrusion opening.

16. An expandable intervertebral implant adapted to be inserted at least partially into a bore drilled between two adjacent vertebrae to expose cancellous bone tissue within each of the two vertebrae, and adapted to be secured to the vertebrae by expansion, comprising:

a first shell having a first end and a plurality of engaging members extensible from the implant for engagement with cancellous bone tissue of a vertebra, said engaging members axially extending from said first end, a cross section of said first shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra;

a second shell operatively connected to said first shell and having a second end with at least one bearing surface engageable with said engaging members, cross section of said second shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra;

a first axis extending between said first and second ends;

a second axis extending perpendicularly to said first axis; and

a third axis extending perpendicularly to said first and second axes, wherein said second axis has a length greater than a diameter of the bore and said third axis has a length less than the diameter of the bore.

17. The implant according to claim 16, further comprising:

at least one extrusion opening in at least one of said first and second shells, said first and second shells cooperating to form a cavity delimited by inner surfaces thereof, wherein movement of said second shell with respect to said first shell effects expansion of the implant and at least partial extrusion of material contained in the cavity through said extrusion opening.

18. A method for stabilizing first and second vertebrae with respect to one another, said method comprising the steps of:

forming a bore between two vertebrae to expose cancellous bone tissue in at least one vertebra;

providing at least one expandable intervertebral implant containing osteogenic material, the implant having first, second and third axes and first and second opposed shells, a cross section of the implant having at least one curvalinear shoulder for supporting a periosteal membrane of one of the two adjacent vertebrae, the first axis extending between the ends, the second axis extending perpendicular to the first axis and having a length greater than a diameter of the bore, the third axis extending perpendicular to the first and second axes and having a length equal to or less than the diameter of the bore, at least one of the first and second shells having engaging members extensible from the implant for engagement with the cancellous bone tissue, the engaging members extending from an end of the at least one shell;

inserting the implant in the bore so that the curvalinear shoulder bears against and supports the periosteal membrane;

expanding the implant.

19. The method of claim 18, including the step of:

effecting expansion of the implant by moving the second shell with respect to the first shell and thereby extending the engaging members toward the cancellous bone tissue.

20. The method of claim 18, including the further step of:

extruding an osteogenic material from the implant during expansion thereof.

21. An expandable intervertebral implant adapted to be inserted at least partially into a bore drilled into an intervertebral disk space between two adjacent vertebra to expose cancellous bone tissue, and adapted to be secured to the vertebrae by expansion, comprising:

first and second opposed and operatively connected shells, each of said shells having an end, at least one of said shells have a plurality of engaging members engageable with the cancellous bone tissue, said engaging members axially extending from said at least one shell and being radially extensible from the implant, a cross section of at least one of said ends having a curvalinear shoulder for supporting a rigid portion of one of the vertebrae;

at least one extrusion opening in at least one of said shells, wherein movement of second shell with respect to said first shell effects radial extension of said engaging members and thereby at least partially extruding osteogenic material through said extrusion opening.

22. An expandable intervertebral implant adapted to be inserted at least partially into a bore drilled between two adjacent vertebrae to expose cancellous bone tissue within each of the two vertebrae, and adapted to be secured to the vertebrae by expansion, comprising:

a first shell having a first end, a plurality of engaging members radially extensible from the implant, said engaging members axially extending from said first end, said first end including a plurality of bearing surfaces, a cross section of said first shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra;

a second shell operatively connected to said first shell and having a second end and a plurality of engaging members, said second end having a plurality of bearing surfaces engageable with said engaging members of said first shell, said engaging members of said second shell engageable with said bearing surfaces of said first end, a cross section of said second shell including at least one curvalinear shoulder for supporting a periosteal surface of a vertebra;

a first axis extending between said first and second ends;

a second axis extending perpendicular to said first axis; and

a third axis extending perpendicular to said first and second axes, wherein said second axis has a length greater than a diameter of the bore and said third axis has a length less than the diameter of the bore, wherein said bearing surfaces of said first and second ends urge said engaging members of said second and first shells radially outward for contact with cancellous bone tissue.

23. An expandable intervertebral implant adapted to be inserted at least partially into a bore drilled into an intervertebral disk space between two adjacent vertebra to expose cancellous bone tissue, and adapted to be secured to the vertebrae by expansion, comprising:

first and second opposed and operatively connected shells, each of said shells having an end and a curvalinear outer surface axially extending therefrom, at least one of said curvalinear outer surfaces comprising a plurality of engaging members engageable with the cancellous bone tissue, said engaging members being extensible from the implant, said curvalinear outer surfaces cooperating to form an ellipsoid surface for supporting a rigid portion of one of the vertebrae;

at least one extrusion opening in at least one of said shells, wherein movement of second shell with respect to said first shell effects extension of said engaging members from the implant thereby expanding the implant and at least partially extruding osteogenic material contained within the implant through said extrusion opening.