Two part intersomatic implant

• US 20020177898A1
• Filed: 07/10/2002
• Published: 11/28/2002
• Est. Priority Date: 04/25/1997
• Status: Active Grant

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker France S.A.
• Inventors: Crozet, Yves
• Granted Patent: US 7,056,341 B2
• Time in Patent Office: Days
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61B 17/861 specially shaped for gripping driver
• CPC Class Codes: A61B 17/8625 Shanks, i.e. parts contacting bone tissue
• CPC Class Codes: A61B 17/864 hollow, e.g. with socket or cannulated
• CPC Class Codes: A61B 17/8645 Headless screws, e.g. ligament interference screws
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches
• 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 2/442 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• 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 2002/30118 concentric circles
• CPC Class Codes: A61F 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30169 Pi-shaped
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30217 hollow cones, e.g. tubular-like cones
• CPC Class Codes: A61F 2002/30224 : cylindrical
• CPC Class Codes: A61F 2002/30233 : Stepped cylinders, i.e. having discrete diameter changes
• CPC Class Codes: A61F 2002/30235 : tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30261 : parallelepipedal
• CPC Class Codes: A61F 2002/30354 : Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
• CPC Class Codes: A61F 2002/30364 : Rotation about the common longitudinal axis
• CPC Class Codes: A61F 2002/30367 : with additional means for preventing said rotation
• CPC Class Codes: A61F 2002/30373 : with additional means for preventing said translation
• CPC Class Codes: A61F 2002/30405 : made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/305 : Snap connection
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30772 : Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30845 : with cutting edges
• 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 2002/30904 : serrated profile, i.e. saw-toothed
• 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 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0006 : circular
• CPC Class Codes: A61F 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0034 : D-shaped
• CPC Class Codes: A61F 2230/0047 : Pi-shaped
• CPC Class Codes: A61F 2230/0067 : conical
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• 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: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A spinal implant including a hollow body having a distal end, a proximal end, and a pair of lateral walls extending from the distal end to the proximal end, the lateral walls having concave, non-threaded interior surfaces for defining an at least partially cylindrical internal space between the lateral walls. The implant includes an anchoring member having bone anchoring projections including a screw thread on an exterior surface thereof, wherein the screw thread of the anchoring member is a self-tapping screw thread having a radial cross-section that transforms from a substantially triangular radial cross-section to a substantially square radial cross-section starting from a distal end of the thread, and wherein at least one of the lateral walls adjacent the proximal end of the hollow body includes a reentrant thread adapted to cooperate with the screw thread of the anchoring member when the anchoring element is rotated for enabling the anchoring member to be screwed into the internal space of the hollow body.

Claims

1. A spinal implant comprising:

a hollow body having a distal end, a proximal end, and a pair of lateral walls extending from said distal end to said proximal end, said lateral walls having concave, non-threaded interior surfaces for defining an at least partially cylindrical internal space between said lateral walls; and

an anchoring member having bone anchoring projections including a screw thread on an exterior surface thereof, wherein the screw thread of said anchoring member is a self-tapping screw thread having a radial cross-section that transforms from a substantially triangular radial cross-section to a substantially square radial cross-section starting from a distal end of said thread, and wherein at least one of said lateral walls adjacent the proximal end of said hollow body includes a reentrant thread adapted to cooperate with the screw thread of said anchoring member when said anchoring element is rotated for enabling said anchoring member to be screwed into the internal space of said hollow body.

2. The implant as claimed in claim 1, wherein said reentrant thread is provided on only one of said lateral walls.

3. The implant as claimed in claim 1, wherein said reentrant thread is the only part of said hollow body that threadably engages the screw thread of said anchoring member.

4. The implant as claimed in claim 1, wherein said reentrant thread includes a substantially rectilinear edge.

5. The implant as claimed in claim 1, wherein the lateral walls of said hollow body define a height of said hollow body.

6. The implant as claimed in claim 5, wherein the projections of said anchoring member have a diameter greater than the height of said hollow body.

7. The implant as claimed in claim 1, wherein said hollow body has upper and lower faces that are inclined relative to one another so that a distance between the upper and lower faces decreases from the proximal end to the distal end of said hollow body.

8. The implant as claimed in claim 1, wherein said hollow body has upper and lower faces that are inclined relative to one another, and wherein a distance between the upper and lower faces decreases from a first lateral side of said hollow body to a second lateral side of said hollow body opposite the first lateral side.

9. The implant as claimed in claim 8, wherein said lateral walls have first openings for permitting bone in-growth through said lateral walls.

10. The implant as claimed in claim 9, wherein the internal space of said hollow body is in communication with the first openings extending through said lateral walls.

11. The implant as claimed in claim 10, wherein said lateral walls have second openings extending therethrough between the upper and lower faces of said hollow body.

12. The implant as claimed in claim 11, wherein said second openings are in communication with said first openings.

13. The implant as claimed in claim 9, wherein said first openings are in communication with outer sides of said hollow body.

14. The implant as claimed in claim 1, wherein said hollow body has a distal end wall connecting said lateral walls, said distal end wall being rounded to facilitate insertion of said hollow body into an intervertebral space.

15. The implant as claimed in claim 1, wherein said anchoring member has a proximal end, a distal end, a major axis extending between the proximal and distal ends, an interior space, and a fork surrounding the interior space, said fork including branches extending along a major axis of said anchoring member, said branches having a frustoconical exterior surface with a diameter that decreases from the proximal end toward the distal end of said anchoring member, and wherein the screw thread comprises a helical band connected to said fork and encircling said fork and the interior space of said anchoring member.

16. The implant as claimed in claim 1, wherein said anchoring member is oriented obliquely relative to a sagittal plane of the spine.

17. The implant as claimed in claim 1, wherein said anchoring member is oriented at approximately 45°

relative to the sagittal plane of the spine.

18. The implant as claimed in claim 1, wherein said implant includes a substantially cylindrical plug insertable into an end opening at the proximal end of said anchoring member for preventing reverse rotation of said anchoring member relative to said hollow body.

19. The implant as claimed in claim 1, wherein a portion of the screw thread at the proximal end of said anchoring member is deformed, the deformed screw thread portion being engageable with said substantially cylindrical plug for preventing reverse rotation of said anchoring member.

20. The implant as claimed in claim 1, wherein said hollow body includes an intermediate wall between said pair of lateral walls to define a second internal space of said hollow body adjacent said first internal space, said first internal space being between a first one of the lateral walls and the intermediate wall and said second internal space being between a the intermediate wall and a second one of said lateral walls, wherein said anchoring member is threadable into said first internal space and a second anchoring member is threadable into said second internal space.

21. The implant as claimed in claim 20, wherein said second internal space is at least partially cylindrical in cross section and has concave, non-threaded interior surfaces.

22. The implant as claimed in claim 20, wherein said first and second anchoring members are substantially identical.

24. The method as claimed in claim 23, wherein said hollow body of said implant has at least one hole holes extending between upper and lower faces of said hollow body, the method further comprising filling the at least one hole with a substance that promotes bone growth before inserting said hollow body into said intervertebral space.

23. A method for positioning an implant in an intervertebral space of a vertebral column, said implant comprising a hollow body having a pair of lateral walls having concave, non-threaded interior surfaces defining an at least partially cylindrical internal space, and an anchoring member threadable into the internal space of said hollow body, said anchoring member having a self-tapping screw thread having a radial cross-section that transforms from a substantially triangular radial cross-section to a substantially square radial cross-section starting from a distal end of said thread, the method comprising:

filling said hollow body with a bone growth promoting substance;

inserting said hollow body into an intervertebral space so that the internal space of said hollow body is in communication with opposing vertebrae over and under said hollow body; and

screwing said bone anchoring member into said hollow body so that said projections cut into said opposing vertebrae for anchoring said hollow body in said intervertebral space.