Expandable intervertebral implant cage

• US 20040162618A1
• Filed: 10/14/2003
• Published: 08/19/2004
• Est. Priority Date: 02/14/2003
• Status: Active Grant

• Current Assignee: Zimmer Biomet Spine, Inc. (Zimvie Incorporated)
• Original Assignee: Centerpulse Orthopedics Incorporated
• Inventors: Mujwid, James R., Bentley, Ishmael
• Granted Patent: US 7,094,257 B2
• Time in Patent Office: Days
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2002/30487 Circumferential cooperating grooves and beads on cooperating lateral surfaces of a mainly longitudinal connection
• CPC Class Codes: A61F 2002/3052 unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30522 releasable, e.g. using a releasable ratchet
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• 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 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2250/0009 for adjusting thickness
• 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 2310/00173 Graphite

Abstract

An expandable intervertebral implant having an external member and an internal member. The implant includes a locking arrangement having a first interlocking teeth structure formed on the external member and a second interlocking teeth structure formed on the internal member. The interlocking teeth structures of the external and internal members have engagement surfaces arranged in a non-perpendicular orientation relative to the direction of implant expansion. The locking arrangement is configured such that walls of the internal member are pulled or flexed toward the walls of the external member when compressive forces are applied to the implant.

Claims

1. An expandable intervertebral implant, the implant comprising:

a) an external member and an internal member;

b) interlocking teeth structure formed on each of the external and internal members, the interlocking teeth structure arranged to permit expansion of the intervertebral implant;

i) the interlocking teeth structure formed on the external and internal members including external and internal engagement surfaces, the external and internal engagement surfaces configured to engage one another to lock the implant in an expanded configuration;

1) wherein the external and internal engagement surfaces are arranged in a non-perpendicular orientation relative to the direction of implant expansion.

2. An expandable intervertebral implant, the implant comprising:

a) an external member and an internal member, each of the members including at least a first wall;

b) interlocking teeth structure formed on the first walls of the external and internal members, the interlocking teeth structure arranged to permit expansion of the intervertebral implant;

i) the interlocking teeth structure formed on the external member having an engagement surface that engages an engagement surface on the internal member to lock the implant in an expanded configuration; and

1) the engagement surfaces of the interlocking teeth structures being arranged in a non-perpendicular orientation relative to the first walls of the external and internal members.

3. The implant of claim 2, wherein the engagement surfaces of the interlocking teeth structure formed on the external member are raked upwardly about 4 degrees.

4. The implant of claim 3, wherein the engagement surfaces of the interlocking teeth structure formed on the internal member are raked downwardly about 4 degrees.

5. The implant of claim 2, wherein each of the engagement surfaces of the interlocking teeth structure formed on the internal and external members is angled approximately 94 degrees relative to the respective first wall.

6. The implant of claim 2, wherein the first walls of the external and internal members have an inside wall surface and an outside wall surface, the interlocking teeth structure being formed only on the inside wall surface of the external member, and only on the outside wall surface of the internal member.

7. The implant of claim 2, wherein the first wall of the internal member is positioned within the first wall of the external member, the interlocking teeth structure formed on the first walls being configured to flex the first wall of the internal member outward toward the first wall of the external member.

8. The implant of claim 7, wherein the external member is a rigid construction configured to prevent flexure of the first wall of the external member during expansion of the intervertebral implant.

9. The implant of claim 8, wherein the internal member is a flexible construction configured to permit flexure of the first wall of the internal member during expansion of the intervertebral implant.

10. The implant of claim 9, wherein the internal member includes a slot formed adjacent to an end of the first wall to permit flexure of the first wall of the internal member during expansion of the intervertebral implant.

11. The implant of claim 9, wherein the first wall of the external member has an external wall thickness, the external wall thickness being greater than an internal wall thickness of the internal member, wherein the external wall thickness of the external member prevents flexure of the first external wall and the internal wall thickness of the internal member permits flexure of the first internal wall.

12. An expandable intervertebral implant, the implant comprising:

a) an external member including;

i) a external base wall, and first and second external walls extending from the external base wall;

b) an internal member including;

i) an internal base wall, and first and second internal walls extending from the internal base wall;

ii) the first and second internal walls positioned within the first and second external walls;

c) a locking arrangement configured to lock the implant in an expanded position, the locking arrangement including;

i) a first configuration of teeth formed on each of the first and second external walls, the first configuration of teeth being raked in an upwardly direction; and

ii) a second configuration of teeth formed on each of the first and second internal walls, the second configuration of teeth being raked in a downwardly direction.

13. The implant of claim 12, wherein each of the upwardly and downwardly raked configuration of teeth of the external and internal members have a rake angle of between 1 degree and 8 degrees relative to the first and second walls of the external and internal members.

14. The implant of claim 12, wherein the first upwardly raked configuration of teeth are angled approximately 4 degrees relative to the first and second external walls of the external member.

15. The implant of claim 12, wherein the second downwardly raked configuration of teeth are angled approximately 4 degrees relative to the first and second internal walls of the internal member.

16. The implant of claim 12, wherein the first and second configurations of teeth are configured to deflect the internal walls of the internal member outward toward the external walls of the external member when compressive force are applied to the base walls of the external and internal members.

17. An expandable intervertebral implant, the implant comprising:

a) an first member having a first base portion and walls extending from the first base portion;

b) a second member having a second base portion and walls extending from the second base portion; and

c) interlocking structure formed on each of the first and second members, the interlocking structure being configured to secure the implant in an expanded configuration;

d) wherein the interlocking structure formed on the first and second members is configured to flex the walls of the second member toward the walls of the first member when compressive forces are applied to the base portions of the first and second members.

18. The implant of claim 17, wherein the interlocking structure include ratchet teeth configured to permit linear expansion from a non-expanded configuration to the expanded configuration.

19. The implant of claim 18, wherein only the walls of the second member are configured to ratchet during expansion, and only the walls of the second member are configured to flex when compressive forces are applied to the base portions of the first and second members.

20. An expandable intervertebral implant, comprising:

a) a first member and a second member configured to expand between a first position and a second position along an expansion axis of the implant;

b) an engagement structure interlocking the first and second members, the engagement structure including at least one engaging surface having a non-perpendicular orientation relative to the expansion axis of the implant.