Systems and techniques for intravertebral spinal stabilization with expandable devices

1. A system for intravertebral reduction, comprising:

a delivery instrument including a radially expandable element along an outside surface of a distal portion thereof;

an expandable device including a cavity, the expandable device being removably mountable to the expandable element with the expandable element in the cavity and each of the expandable device and the expandable element in an unexpanded condition, the expandable device including an external surface and an internal surface, said external surface having a first portion and a second portion movable away from one another upon expansion of the expandable element, the first portion defining a first linear outer surface and a second linear outer surface, the second portion defining a third linear outer surface and a fourth linear outer surface, said internal surface facing said cavity, wherein the expandable device is deliverable to an intravertebral space in the unexpanded condition and thereafter expandable with expansion of the expandable element to compress cancellous bone in the intravertebral space, wherein the first linear outer surface and the second linear outer surface define a first step, and the third linear outer surface and the fourth linear outer surface define a second step, such that the expandable device has a stepped cross-section configuration and such that in an expanded condition the first linear outer surface and the third linear outer surface are separated by a first height and the second linear outer surface and the fourth linear outer surface are separated by a second height greater than the first height; and

bone filler material positioned in the cavity between the first and second portions.

2. The system of claim 1 , wherein the expandable element includes a balloon structure with an interior for receiving an expansion fluid.

3. The system of claim 2 , wherein the expansion fluid is selectable from the group consisting of: saline solution, compressed air, and radio-contrast fluid.

4. The system of claim 2 , wherein the delivery instrument includes a shaft defining a lumen in fluid communication with the Interior of the expandable element,

5. The system of claim 1 , wherein the first and second portions are uni-directionally movable away from one another upon expansion of the expandable element.

6. The system of claim 1 , wherein the first and second portions are substantially rigid and the expandable element is non-rigid.

7. The system of claim 1 , wherein the first and second portions are structured to maintain an expanded configuration after removal of the expandable element from the cavity therebetween.

8. The system of claim 1 , wherein the bone filler material includes bone growth promoting material.

9. The system of claim 1 , wherein the cavity opens at a distal and at a proximal end of the expandable device.

10. The system of claim 1 , wherein said filler material Is bone growth material injected into said expandable element.

11. The system of claim 10 , wherein said bone growth material causes said expansion of the expandable element and expansion of said expandable device.

12. The system of claim 1 , wherein the first portion and the second portion are selectively movable relative to the other.

13. A system for intravertebral reduction, comprising:

a delivery instrument including a non-rigid radially expandable element along an outside surface of a distal portion thereof,

an expandable device including a cavity between substantially rigid first and second portions, the expandable device being structured for positioning in an intravertebral space, wherein the expandable element is expandable in the cavity to move the first and second portions away from one another and compress cancellous bone in the intravertebral space, the first portion defining a linear anterior outer surface and a linear posterior outer surface, the second portion defining a linear anterior outer surface and a linear posterior outer surface,

wherein the linear anterior outer surface and the linear posterior outer surface of the first portion define a first step, and the linear anterior outer surface and the linear posterior outer surface of the second portion define a second step, such that the expandable device has a stepped cross-section configuration such that in an expanded condition the linear anterior outer surface of the first portion and the linear anterior outer surface of the second portion are separated by a first height and the linear posterior outer surface of the first portion and the linear posterior outer surface of the second portion are separated by a second height greater than the first height; and

bone filler material positioned in said expandable element in the cavity between the first and second portions.

14. The system of claim 13 , wherein the first and second portions remain movably engaged with one another during expansion of the expandable element.

15. The system of claim 13 , wherein the first and second portions are structured to maintain an expanded configuration after removal of the expandable element from the cavity therebetween.

16. The system of claim 13 , wherein the expandable device is radially expandable.

17. The system of claim 13 , wherein the expandable device includes a width between opposite sides thereof, the width remaining substantially constant in the unexpanded and expanded conditions.

18. The system of claim 13 , wherein said expandable device includes an external surface and an internal surface, said internal surface facing said cavity, wherein no part of said external surface faces any part of said internal surface.

19. The system of claim 13 , wherein the first portion and the second portion are selectively movable relative to the other.

20. A system for intravertebral reduction, comprising:

a delivery instrument including a radially expandable element along an outside surface of a distal portion thereof;

an expandable device including a cavity, the expandable device being removably mountable to the expandable element with the expandable element in the cavity and each of the expandable device and the expandable element in an unexpanded condition, the expandable device including a first surface facing generally toward said cavity, and a second surface facing generally away from said cavity, said second surface having a first portion and a second portion movable away from one another upon expansion of the expandable element, the first portions defining a first linear outer surface and a second linear outer surface, the second portion defining a third linear outer surface and a fourth linear outer surface, wherein the expandable device is deliverable to an intravertebral space in the unexpanded condition and thereafter expandable with expansion of the expandable element to compress cancellous bone in the intravertebral space,

wherein the first linear outer surface and the second linear outer surface define a first step, and the third linear outer surface and the fourth linear outer surface define a second step, such that the expandable device has a stepped cross section configuration such that in an expanded condition the first linear outer surface of the first portion and the third linear outer surface of the second portion are separated by a first height and the second linear outer surface of the first portion and the fourth linear outer surface of the second portion are separated by a second height greater than the first height,

the first portion and the second portion being selectively movable relative to the other; and

filler material positioned in the cavity between the first and second portions.