Expandable interbody fusion device

• US 20060058807A1
• Filed: 08/25/2005
• Published: 03/16/2006
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Spine Wave Incorporated
• Original Assignee: Spine Wave Incorporated
• Inventors: Wysocki, Steve, Landry, Michael
• Granted Patent: US 7,931,688 B2
• Time in Patent Office: Days
• US Class Current: 606/90
• CPC Class Codes: A61B 2017/0256 for the spine
• 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 2/4465 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 2002/30383 made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove
• CPC Class Codes: A61F 2002/30476 locked by an additional locking mechanism
• CPC Class Codes: A61F 2002/30492 using a locking pin
• CPC Class Codes: A61F 2002/3052 unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30599 stackable
• CPC Class Codes: A61F 2002/30601 telescopic
• 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 2250/0009 for adjusting thickness
• CPC Class Codes: A61F 2250/0063 Nested prosthetic parts

Abstract

An expandable interbody fusion device includes superior and inferior plates that are configured to receive a sequentially inserted stack of expansion members or wafers. The superior and inferior plates include features that at least initially interlock the two plates until the superior plate is dislodged by pressure from the growing wafer stack. The wafers include features on their top and bottom surfaces that interlock the wafers in multiple degrees of freedom so that the wafer stack is not disrupted when the fusion device is fully expanded. Each wafer also includes features that interlock with the inferior plate until the wafer id dislodged by sequential introduction of another wafer.

Claims

1. A device for distracting a body tissue space between opposing tissue surfaces, comprising:

an upper plate having an outer surface configured to contact one of the opposing surfaces;

a lower plate having an outer surface configured to contact the other of the opposing surfaces, said lower plate having opposite side walls configured to removably support said upper plate thereon;

said upper and lower plates defining a cavity when said upper plate is supported on said lower plate,

said lower plate defining a support surface for supporting at least one expansion member within said cavity, and a channel communicating with said cavity and configured to receive an expansion member conveyed therethrough for placement on said surface of said lower plate;

said upper plate defining a contact surface for contacting an uppermost expansion member within said cavity to displace said upper plate from said lower plate as additional expansion members are conveyed along said channel, said contact surface having a mating interface for interlocking engagement with a complementary mating interface on said uppermost expansion member; and

a releasable engagement feature between said upper plate and said lower plate configured to hold said upper and lower plates together until said upper plate is displaced by the uppermost expansion member.

2. The device of claim 1, wherein said releasable engagement feature includes at least one male element and corresponding mating female element defined between said upper plate and said lower plate.

3. The device of claim 2, wherein said male element is a rib and said female element is a corresponding recess.

4. The device of claim 2, wherein said rib is defined on each side wall of said lower plate and said corresponding recess is defined in said upper plate.

5. The device of claim 4, wherein:

said upper plate includes a hub sized to fit between said side walls of said lower plate; and

said corresponding recess includes at least one groove defined on opposite sides of said hub and configured for releasable engagement with a rib on a corresponding side wall.

6. The device of claim 5, wherein said corresponding recess includes at least two grooves offset from each other on opposite sides of said hub, each of said grooves configured for releasable engagement with a rib on a corresponding side wall.

7. The device of claim 4, wherein at least a pair of ribs is defined on each side wall, each of said pair of ribs arranged for releasable engagement with said at least one groove.

8. The device of claim 1, further comprising a wafer sized to be conveyed through the channel and to be supported on the support surface of the lower plate, said wafer having opposite side walls configured to form part of a releasable engagement feature between said wafer and the lower plate.

9. The device of claim 4, further comprising a wafer sized to be conveyed through the channel and to be supported on the support surface of the lower plate, said wafer having opposite side walls each defining a mating recess configured for releasable engagement with the rib defined on each side wall of the lower plate.

10. An expansion member for sequential insertion into a space between opposing tissue surfaces to be distracted, comprising:

an elongated body having an upper surface and an opposite lower surface, and an insertion end and an opposite trailing end;

a female feature defined on one of said upper and lower surface, said female feature having an opening at said trailing end; and

a male feature defined on the other of said upper and lower surface and configured for insertion through said opening; and

resilient interlocking features defined between said female and male features for resiliently interlocking adjacent elongated bodies when the male feature of one body is inserted into said female feature through said opening.

11. The expansion member of claim 10, wherein:

said female feature is an elongated recess;

said male feature is an elongated boss configured to be received within said recess; and

said resilient interlocking features include;

at least one latch element and indentation adjacent said latch element defined at opposite sides of said recess; and

at least one corresponding mating indentation and mating latch element adjacent said mating indentation defined at opposite sides of said boss and arranged so that said latch element is received in said mating indentation and said mating latch element is received in said indentation when said elongated boss is received in said elongated recess.

12. The expansion member of claim 11, wherein said resilient interlocking features includes three of said latch elements and indentations spaced along the length of said elongated recess, and three of said corresponding mating indentations and mating latch elements comparably spaced along the length of said boss.

13. The expansion member of claim 12, wherein said latch elements on said opposite sides of said elongated recess define a width therebetween, said width decreasing between successive ones of said latch elements.

14. The expansion member of claim 13, wherein said mating latch elements on said opposite sides of said elongated boss define a width therebetween, said width decreasing between successive ones of said mating latch elements.

15. The expansion member of claim 11, wherein said resilient interlocking features includes a slot defined through said wafer extending along at least a portion of the length of said elongated boss and disposed between said mating indentation and said mating latch element on said opposite sides of said boss.

16. The expansion member of claim 15, wherein said slot is a closed slot extending along substantially the entire length of said recess.

17. The expansion member of claim 10, wherein:

said female feature is an elongated recess including said opening at one end and an end wall at end opposite said opening, said end wall defining a recess undercut; and

said male feature is an elongated boss configured to be received within said recess and having a leading boss defining a boss undercut arranged to interlock with said recess undercut when said boss is within said recess.

18. The expansion member of claim 17, wherein:

said elongated recess defines recess side undercuts in opposite sides of said recess adjacent said opening; and

said elongated boss defines boss side undercuts at opposite sides of said boss and arranged to interlock with said recess side undercuts when said boss is within said recess.

19. The expansion member of claim 10, wherein said insertion end is beveled.

20. The expansion member of claim 19, wherein said trailing end is beveled to coincide with the bevel of said insertion end when one expansion member is inserted into the tissue space beneath another expansion member.

21. An expansion member for sequential insertion into a space between opposing tissue surfaces to be distracted, comprising:

an elongated body having an upper surface and an opposite lower surface, and an insertion end and an opposite trailing end;

a female feature defined on one of said upper and lower surface, said female feature having an opening at said trailing end; and

a male feature defined on the other of said upper and lower surface and configured for insertion through said opening; and

a locking feature defined between said female and male features for locking adjacent elongated bodies against relative movement along the length of the bodies when the male feature of one body is inserted into said female feature through said opening.

22. The expansion member of claim 21, wherein said locking feature includes resiliently deformable elements defined on said female and male features.

23. The expansion member of claim 22, wherein:

said female feature is an elongated recess;

said male feature is an elongated boss configured to be received within said recess; and

said resiliently deformable elements include;

at least one latch element and indentation adjacent said latch element defined at opposite sides of said recess; and

at least one corresponding mating indentation and mating latch element adjacent said mating indentation defined at opposite sides of said boss and arranged so that said latch element is received in said mating indentation and said mating latch element is received in said indentation when said elongated boss is received in said elongated recess.

24. The expansion member of claim 21, further comprising an interlocking feature defined between said female and male features for interlocking adjacent elongated bodies against relative movement perpendicular to the length of the bodies when the male feature of one body is inserted into said female feature through said opening.

25. The expansion member of claim 24, wherein:

said female feature is an elongated recess including said opening at one end and an end wall at end opposite said opening, said end wall defining a recess undercut; and

said male feature is an elongated boss configured to be received within said recess and having a leading boss defining a boss undercut arranged to interlock with said recess undercut when said boss is within said recess.

26. The expansion member of claim 25, wherein:

said elongated recess defines recess side undercuts in opposite sides of said recess adjacent said opening; and

said elongated boss defines boss side undercuts at opposite sides of said boss and arranged to interlock with said recess side undercuts when said boss is within said recess.

27. An expansion member for sequential insertion into a space between opposing tissue surfaces to be distracted, comprising:

an elongated body having an upper surface, an opposite lower surface, an insertion end and an opposite trailing end;

said body including a leading boss projecting above said upper surface adjacent said insertion end and a recess defined in said lower surface beneath said boss, said leading boss defining a rear undercut opposite said insertion end;

said body further defining a slot therethrough terminating at one end beneath said rear undercut and including at its opposite end a flexible arm extending into said slot toward said boss and having an end positioned beneath said undercut,

whereby when two of said expansion members are coupled, said boss of a lowermost expansion member fits within said recess of the uppermost expansion member, and said flexible arm of the uppermost expansion member is trapped between said undercut of said boss of the uppermost member and said boss of the lowermost expansion member.

28. The expansion member of claim 27, wherein said recess defines a recess undercut and said boss defines a leading undercut configured to engage said recess undercut when two expansion members are coupled.

29. The expansion member of claim 27, further comprising:

a rear boss projecting above said upper surface, said rear boss defining a forward undercut; and

a rear recess defined in said lower surface beneath said rear boss, said rear recess defining a rear recess undercut configured to engage said forward undercut when two expansion members are coupled.

30. An expandable interbody fusion device for implantation into the intradiscal space between two opposing vertebral bodies of a spine, comprising:

a superior endplate member having an outer surface for engaging a superior vertebral body in a spine;

an inferior endplate member having an outer surface for engaging an inferior vertebral body in said spine, said superior endplate member and said inferior endplate member being releasably coupled and defining a cavity therebetween;

at least one expansion member configured to be introduced into said cavity to move said endplate and said inferior endplate member relatively apart upon introduction and to thereby decouple said superior endplate member and said inferior endplate member; and

an interlocking interface defined by complementary mating configurations on said expansion member and a surface on one of said superior endplate member or said inferior endplate member to provide interlocking engagement therebetween.

31. The fusion device of claim 30, wherein said interlocking interface is defined between a surface on said superior endplate member and said expansion member.

32. The fusion device of claim 31, wherein said expansion member is defined by a generally flat wafer having an upper surface and an opposing lower surface.

33. The fusion device of claim 32, wherein the complementary mating configuration on said superior endplate member is defined by a slot formed into a lower surface of said superior endplate member and said complementary mating configuration on said wafer is defined by at least one boss projecting from the upper surface of said wafer and configured for complementary sliding fit within said slot.

34. The fusion device of claim 33, wherein said boss is formed to provide a flexible latch operable upon insertion into said slot.

35. The fusion device of claim 34, wherein said complementary mating configuration on said superior endplate member is defined by a first undercut surface and said complementary mating configuration on said wafer is defined by a second undercut surface configured to engage said first undercut surface upon insertion of said boss into said slot.

36. An expandable interbody fusion device for implantation into the intradiscal space between the opposing vertebral bodies in a spine, comprising:

an upper plate having an outer surface configured to contact an upper vertebral body;

a lower plate having an outer surface configured to contact a lower vertebral body;

said upper plate and said lower plate configured to be releasably engaged and defining a cavity therebetween when engaged;

at least one expansion member sized to be received into said cavity and upon receipt therein to disengage said upper and lower plates;

said expansion member being configured to form an interlocking interface with said upper plate; and

said expansion member being configured to provide a releasable engagement with said lower plate upon receipt of a further expansion member into said cavity.

37. The fusion device of claim 36, wherein said lower plate has a pair of opposing spaced apart sidewalls.

38. The fusion device of claim 37, wherein said upper plate and said lower plate are releasably engaged by a groove on said upper plate and a corresponding rib on at least one of said sidewalls.

39. The fusion device of claim 38, wherein said expansion member is defined by a generally flat wafer having an upper surface and an opposing lower surface with side edges therebetween.

40. The fusion device of claim 39, wherein said wafer and said lower plate are releasably engaged by a recess formed into a side edge of said wafer and said rib on at least one of said sidewalls of said lower plate.

41. The fusion device of claim 40, wherein said lower plate further includes a front end wall and a spaced opposing rear end wall that together with said sidewalls form said cavity fully bounded thereby.

42. The fusion device of claim 41, wherein said interlocking interface is defined by a mating configuration on a lower surface of said upper plate and a complementary mating configuration on the upper surface of said wafer.

43. The fusion device of claim 42, comprising at least one further wafer received between said at least one wafer and said further wafer defining an interlocking interface therebetween, said further wafer being contained within the sidewalls and the front and rear end walls of said lower member.

44. An expandable interbody fusion device for implantation into the intradiscal space between the opposing vertebral bodies in a spine, comprising:

an upper plate having an outer surface configured to contact an upper vertebral body;

a lower plate having an outer surface configured to contact a lower vertebral body, a support surface and an opening communicating with said support surface;

said upper plate and said lower plate configured to be releasably engaged and defining a cavity between said upper plate and said support surface;

at least two expansion members sized to be sequentially received through said opening onto said support surface, one expansion member beneath an immediately prior expansion member to raise said immediately prior expansion member; and

a releasable engagement defined between said lower plate and each of said expansion members, said releasable engagement operable to engage said immediately prior expansion member raised by said one expansion member.

45. The fusion device of claim 44, wherein:

said lower plate includes side walls at opposite sides of said cavity;

each of said expansion members includes opposite side edges positioned adjacent said opposite sides when said expansion members are within said cavity; and

said releasable engagement includes a recess formed in at least one side edge of said expansion member and a mating rib projecting from at least one of said side walls of said lower plate.