Zero profile spinal fusion cage

• US 9,526,620 B2
• Filed: 03/30/2009
• Issued: 12/27/2016
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Original Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Inventors: Slivka, Michael A., Grinberg, Alexander, Voellmicke, John, Hawkins, John Riley
• Primary Examiner(s): Sevilla, Christian
• Assistant Examiner(s): Mathew, Seema
• Application Number:
  US12/414,532
• Publication Number:
  US 20100249935A1
• Time in Patent Office: 2,829 Days
• Field of Search: 623/17.11, 623 1715- 1716
• US Class Current: 1/1
• CPC Class Codes: A61B 17/8042 the additional component being a cover over the screw head
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• 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 2/4425 made of articulated components
• 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 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• 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 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• 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 2002/3079 Stepped or enlarged apertures, e.g. having discrete diameter changes
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2002/4622 having the shape of a forceps or a clamp
• 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 2002/4628 with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• 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 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00059 : Chromium or Cr-based alloys
• CPC Class Codes: A61F 2310/00161 : Carbon; Graphite
• CPC Class Codes: A61F 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite

Abstract

An interbody fusion cage having upper and lower canals for receiving the heads of bone screws that have been pre-installed in opposing vertebral body endplates. The proximal wall of the cage preferably has a vertical slot that communicates with each canal and is adapted to allow access by a screwdriver and tightening of the screws.

Claims

1. An intervertebral fusion cage comprising:

a distal wall and a proximal wall spaced from the distal wall in a proximal direction;

first and second side walls connecting the proximal and distal walls;

an upper bearing surface adapted for gripping an upper vertebral endplate, and a lower bearing surface adapted for gripping a lower vertebral endplate, the upper bearing surface defining at least one upper opening therethrough adapted to promote bony fusion, and the lower bearing surface defining at least one lower opening therethrough adapted to promote bony fusion, the upper and lower openings together forming a throughhole,

wherein the intervertebral fusion cage defines a first guide surface canal that

     1) extends into the at least one of the upper and lower bearing surfaces,

     2) extends through the distal wall so as to define a distal opening in the distal wall, and

     3) defines a first guide surface, and

wherein the intervertebral fusion cage is configured to receive a head of a bone screw through the distal opening in the proximal direction, such that the head is translatably received in the first guide surface canal and is guided within the first guide surface canal in the proximal direction toward the proximal wall.

2. The cage of claim 1 wherein the first guide surface canal is elongate along the proximal direction, and has a cross-section along a plane perpendicular to the proximal direction that is semi-circular.

3. The cage of claim 1 wherein the first guide surface canal extends substantially along a centerline of the cage.

4. The cage of claim 1 wherein the first guide surface canal includes an outwardly extending bump adapted to limit translational movement of the interbody cage with respect to the screw.

5. The cage of claim 1 wherein the first guide surface canal comprises a distal recess and a proximal recess, each recess having a depth, wherein the proximal recess depth is greater than the distal recess depth.

6. The cage of claim 5 wherein the distal recess is formed from a polymeric material and the proximal recess is formed from a metallic material.

7. The cage of claim 1 wherein the proximal wall has an opening that communicates with the head of the bone screw and is adapted to provide access by a screwdriver.

8. The cage of claim 1 further comprising:

a second guide surface canal formed in another of the upper and lower bearing surfaces and extending substantially from the proximal wall to the distal wall, the second guide surface canal adapted for distal reception of a second screw head.

9. The cage of claim 8, wherein:

the first and second guide surface canals are elongate along the proximal direction; and

the second guide surface canal is aligned with the first guide surface canal along a direction, perpendicular to the proximal direction.

10. The cage of claim 9, wherein the proximal wall defines a slot that extends from the first guide surface canal to the second guide surface canal such that a proximal end of the first guide surface canal is open to a proximal end of the second guide surface canal.

11. The cage of claim 1 wherein the first guide surface canal is discontinuous.

12. The cage of claim 1 wherein the first guide surface canal has the head of the bone screw received therein.

13. The cage of claim 1 wherein the first guide surface canal comprises a proximal process.

14. The cage of claim 1, wherein the first guide surface is smooth as it extends from the proximal wall to the distal wall.

15. The cage of claim 1, wherein the first guide surface is configured to contact the head of the bone screw as the head translates in the proximal direction.

16. The cage of claim 1, wherein:

the first guide surface canal is elongate along the proximal direction and defines a width along a direction, perpendicular to the proximal direction; and

the width decreases from the upper bearing surface toward the lower bearing surface.

17. The cage of claim 1, comprising at least one protrusion that extends over the first guide surface canal at the proximal wall and terminates before the distal wall, wherein the at least one protrusion is configured to lock the head of the bone screw in the first guide surface canal at the proximal wall.

18. The cage of claim 17, wherein:

the first guide surface canal is elongate along the proximal direction and defines a maximum dimension along a second direction, perpendicular to the proximal direction; and

the at least one protrusion comprises a first protrusion, and a second protrusion spaced from the first protrusion along the second direction by a dimension that is less than the maximum dimension.

19. The cage of claim 1, wherein the first guide surface canal extends through the proximal wall so as to define a proximal opening, and the first guide surface canal slidably receives the head of the bone screw such that the head is received in the proximal opening.

20. A spinal assembly, comprising:

the cage of claim 1; and

a first bone anchor that includes the head of the bone screw and a shaft extending from the head.

21. The spinal assembly of claim 20, wherein the head of the bone screw has a shape that conforms to a shape of the first guide surface canal.

22. The spinal assembly of claim 21, wherein the head of the bone screw is substantially spherical.

23. An intervertebral fusion cage comprising:

a proximal end and a distal end, the proximal and distal ends spaced from each other along a first direction;

a first side and a second side, the first and second sides spaced from each other along a second direction that is perpendicular to the first direction;

an upper bearing surface configured to engage an upper vertebral endplate;

a lower bearing surface configured to engage a lower vertebral endplate, the upper and lower bearing surfaces spaced from each other along a third direction that is perpendicular to both the first and second directions; and

a first guide surface that at least partially defines a first guide surface canal that

     1) is elongate along the first direction,

     2) extends through the distal end, and

     3) extends into at least one of the upper and lower bearing surfaces to the first guide surface, the first guide surface canal configured to translatably receive a first bone screw head at the distal end such that the first bone screw head translates within the first guide surface canal in the first direction toward the proximal end until the first bone screw head is captured at the proximal end,

wherein the first guide surface canal defines a width along the second direction, and the width decreases from the upper bearing surface toward the lower bearing surface along the third direction.

24. The cage of claim 23, wherein the first guide surface canal has a cross-section along a plane perpendicular to the first direction that is semi-circular.

25. The cage of claim 23, further comprising a second guide surface canal formed in another of the upper and lower bearing surfaces and extending substantially from the proximal end to the distal end, the second guide surface canal adapted for distal reception of a second bone screw head.

26. The cage of claim 25, wherein the second guide surface canal is aligned with the first guide surface canal along the third direction.

27. The cage of claim 23, wherein the first guide surface is smooth as it extends from the proximal end to the distal end.