Devices for treating the spine

1. A pre-assembled tissue distraction device comprising:

an upper tissue-engaging member;

a lower tissue-engaging member; and

an augmenting member at least partially positioned between the upper and lower tissue-engaging members in an orientation that is substantially perpendicular to a direction extending between the upper and lower tissue-engaging members, wherein

the pre-assembled tissue distraction device is configured to be inserted in a generally linear configuration between adjacent tissue layers of a spine and articulated from the generally linear configuration to a generally less linear configuration, and

the augmenting member is operable while the pre-assembled tissue distraction device is in the generally less linear configuration to spread at least a portion of the upper and lower tissue-engaging members to place at least a portion of the upper tissue-engaging member into engagement with one of said adjacent tissue layers of the spine and to place at least a portion of the lower tissue-engaging member into engagement with another one of said adjacent tissue layers of the spine, with the augmenting member being configured to remain in an orientation that is substantially perpendicular to said direction extending between the upper and lower tissue-engaging members.

2. The pre-assembled tissue distraction device of claim 1 , wherein the augmenting member is configured to be manipulated by application of a force applied in a direction that is different from a direction extending between the portions of the tissue-engaging members configured to engage said adjacent tissue layers of the spine.

3. The pre-assembled tissue distraction device of claim 1 , wherein

at least one of the upper and lower tissue-engaging members includes an inclined surface, and

at least a portion of the augmenting member has a wedge shape configured to engage the inclined surface to spread said at least a portion of the upper and lower tissue-engaging members.

4. The pre-assembled tissue distraction device of claim 1 , wherein

each of the upper and lower tissue-engaging members includes an inclined surface, and

at least a portion of the augmenting member has a wedge shape configured to engage the inclined surfaces to spread said at least a portion of the upper and lower tissue-engaging members.

5. The pre-assembled tissue distraction device of claim 1 , wherein the augmenting member extends between proximal and distal ends and is operable to spread said at least a portion of the upper and lower tissue-engaging members by application of a force to one of the ends.

6. A method of distracting adjacent tissue layers of a spine, comprising:

providing a pre-assembled distraction device including an upper tissue-engaging member, a lower tissue-engaging member, and an augmenting member at least partially positioned between the upper and lower tissue-engaging members;

inserting the pre-assembled distraction device in a generally linear configuration between adjacent tissue layers of a spine;

articulating the pre-assembled distraction device from the generally linear configuration to a generally less linear configuration; and

operating the augmenting member while the pre-assembled distraction device is in the generally less linear configuration to spread at least a portion of the upper and lower tissue-engaging members to place at least a portion of the upper tissue-engaging member into engagement with one of said adjacent tissue layers of the spine and to place at least a portion of the lower tissue-engaging member into engagement with another one of said adjacent tissue layers of the spine, wherein

at least one of the upper and lower tissue-engaging members includes an inclined surface,

at least a portion of the augmenting member has a wedge shape, and

said operating the augmenting member includes moving the wedge shape portion of the augmenting member into engagement with the inclined surface to spread said at least a portion of the upper and lower tissue-engaging members.

7. The method of claim 6 , wherein said operating the augmenting member includes applying a force to the augmenting member in a direction that is different from a direction extending between the portions of the tissue-engaging members placed into engagement with said adjacent tissue layers of the spine.

8. The method of claim 6 , wherein

each of the upper and lower tissue-engaging members includes an inclined surface,

and

said operating the augmenting member includes moving the wedge shape portion of the augmenting member into engagement with the inclined surfaces to spread said at least a portion of the upper and lower tissue-engaging members.

9. The method of claim 6 , wherein

the augmenting member extends between proximal and distal ends, and

said operating the augmenting member includes applying a force to one of the ends.

10. A tissue distraction device comprising:

first and second elongated members insertable between adjacent tissue layers of a spine;

an augmenting elongated member at least partially positionable in a selected position between and in contact with the first and second elongated members; and

first and second radiopaque markers substantially aligned with each other in a direction extending between the adjacent tissue layers of the spine when the augmenting elongated member is in the selected position, wherein the first radiopaque marker is associated with the augmenting elongated member and the second radiopaque marker is associated with a different one of the elongated members.

11. The tissue distraction device of claim 10 , wherein the augmenting elongated member is movable with respect to the first and second elongated members from a first position in which the radiopaque markers are not substantially aligned with each other in said direction extending between the adjacent tissue layers of the spine to the selected position in which the radiopaque markers are substantially aligned with each other in said direction extending between the adjacent tissue layers of the spine.

12. The tissue distraction device of claim 10 , wherein the radiopaque markers have a substantially circular cross-sectional shape.

13. The tissue distraction device of claim 10 , further comprising a third radiopaque marker, wherein each of the first, second, and third radiopaque markers is associated with a different one of the elongated members.

14. The tissue distraction device of claim 10 , wherein the first and second radiopaque markers are substantially identical.

15. The tissue distraction device of claim 10 , wherein

each of the elongated members extends between proximal and distal ends, and

the radiopaque markers are positioned adjacent to the distal end of the associated elongated member.

16. The tissue distraction device of claim 15 , wherein at least one of the elongated members is associated with one of the radiopaque markers and with a proximal radiopaque marker positioned adjacent to the proximal end of said at least one of the elongated members.

17. The tissue distraction device of claim 10 , wherein at least one of the elongated members is associated with one of the radiopaque markers and with a differently shaped additional radiopaque marker.

18. A method of distracting adjacent tissue layers of a spine, comprising:

providing a first elongated member, a second elongated member, and an augmenting elongated member, with a first radiopaque marker associated with the augmenting elongated member and a second radiopaque marker associated with a different one of the elongated members;

inserting the first and second elongated members between adjacent tissue layers of a spine; and

moving the augmenting elongated member from a first position to a selected position between and in contact with the first and second elongated members, wherein the first and second radiopaque markers are substantially aligned with each other in a direction extending between the adjacent tissue layers of the spine when the augmenting elongated member is in the selected position.

19. The method of claim 18 , wherein the radiopaque markers have a substantially circular cross-sectional shape.

20. The method of claim 18 , wherein said providing the first elongated member, the second elongated member, and the augmenting elongated member includes providing a third radiopaque marker, with each of the radiopaque markers being associated with a different one of the elongated members.

21. The method of claim 18 , wherein the first and second radiopaque markers are substantially identical.

22. The method of claim 18 , wherein

each of the elongated members extends between proximal and distal ends, and

the radiopaque markers are positioned adjacent to the distal end of the associated elongated member.

23. The method of claim 22 , wherein at least one of the elongated members is associated with one of the radiopaque markers and with a proximal radiopaque marker positioned adjacent to the proximal end of said at least one of the elongated members.

24. The method of claim 18 , wherein at least one of the elongated members is associated with one of the radiopaque markers and with a differently shaped additional radiopaque marker.