In-situ formed intervertebral fusion device and method

1. An intervertebral fusion device comprising:

first and second vertically-disposed telescopically expandable supporting elements, each supporting element having an upper end and a lower end;

a first rigid bar connecting the upper ends of the telescopically expandable supporting elements;

a second rigid bar connecting the lower ends of the telescopically expandable supporting elements;

an upper surface comprising the first rigid bar and defining a first opening; and

a lower surface comprising the second rigid bar and defining a second opening.

2. The device of claim 1 , wherein the upper and lower surfaces define a natural angle between adjacent vertebrae.

3. The device of claim 1 , wherein the upper and lower surfaces and the supporting elements at least partially define an open cavity.

4. The device of claim 1 , wherein a window is disposed between the first and second rigid bars and between the upper and lower surfaces.

5. The device of claim 1 , further comprising a plurality of outward projections formed on at least one of the upper and lower surfaces.

6. The device of claim 1 , further comprising:

a first fluid communication means configured to direct a fluid under pressure into the first and second telescopically expandable supporting elements to increase a height of the first and second telescopically expandable supporting elements; and

a second fluid communication means containing an osteobiologic.

7. An intervertebral fusion device comprising:

a first telescopically expandable component; and

a second telescopically expandable component;

wherein the first and second telescopically expandable components are coupled to one another by upper and lower bars such that the first telescopically expandable component, the second telescopically expandable component, the upper bar, and the lower bar define an opening therebetween;

wherein the fusion device is configured to move from a collapsed to an expanded configuration by injection of fluid into the first and second telescopically expandable components.

8. The device of claim 7 , wherein an anterior height of the fusion device differs from a posterior height of the fusion device when the fusion device is in the expanded configuration.

9. The device of claim 8 , wherein the anterior and posterior heights are selected to restore a natural angle between adjacent vertebrae.

10. The device of claim 7 , further comprising at least one fluid communication means configured to direct a fluid under pressure into the first and second telescopically expandable components to move the fusion device from the collapsed to the expanded configuration.

11. The device of claim 7 , wherein the first and second telescopically expandable components at least partially define an open cavity when the fusion device is in the expanded configuration.

12. The device of claim 7 , further comprising:

a first fluid communication means configured to direct a fluid under pressure into the first and second telescopically expandable components to move the fusion device from the collapsed to the expanded configuration; and

a second fluid communication means containing an osteobiologic.

13. A spacer for insertion into an intervertebral disc space, the spacer comprising:

an outer wall comprising a metal and defining a cranial margin and a caudal margin, the outer wall being arcuate along its length;

an inner wall comprising a metal and defining a cranial margin and a caudal margin, the inner wall being arcuate along its length; and

an intermediate expandable compartment,

wherein filling of the intermediate expandable compartment with a fluid causes the compartment to expand in a cranial direction away from the cranial margins of the inner and outer walls, thereby providing distraction of the disc space.

14. The spacer of claim 13 , wherein the spacer is configured to expand to a wedge shape to thereby restore a natural angle between adjacent vertebrae.

15. The spacer of claim 13 , further comprising a syringe pump configured to inject fluid into the expandable compartment.

16. The spacer of claim 13 , wherein a thickness of the spacer remains constant as the expandable compartment is filled with fluid to increase a height of the spacer.

17. The spacer of claim 13 , wherein the footprints of the inner and outer walls represent substantially equal arcs of two concentric circumferences.

18. A method for intervertebral fusion comprising:

inserting a fusion device into an intervertebral space in a collapsed configuration in which the fusion device has a first height; and

after inserting the fusion device, distracting the intervertebral space by injecting fluid into first and second telescopically expandable components of the fusion device, the first and second telescopically expandable components being disposed within the intervertebral space, to cause the device to expand to an expanded configuration in which the fusion device has a second height that is greater than the first height.

19. The method of claim 18 , wherein the fusion device restores a natural angle between adjacent vertebrae when in the expanded configuration.

20. The method of claim 18 , further comprising injecting an osteogenic component into an open cavity defined by the expanded fusion device.

21. The method of claim 16 , wherein rigid upper and lower rims extending between the first and second telescopically expandable components engage vertebral endplates adjacent to the intervertebral space when the fusion device is in the expanded configuration.

22. The method of claim 18 , wherein the fluid is injected through a first fluid communication means and wherein the method further comprises injecting an osteobiologic through a second fluid communication means.