Expandable spinal implant

1. A surgical method, comprising:

providing an expandable spinal implant including a fixed base portion and four movable portions extending from the fixed base portion along a longitudinal axis and formed integral with the fixed base portion to define a unitary, single-piece implant body, each of the four movable portions having a substantially equal size and defining a rectangular-shaped cross section, the four movable portions cooperating to provide the implant body with an outer cross section having a first transverse dimension and a second transverse dimension, the movable portions defining first and second substantially planar surfaces disposed generally opposite one another;

inserting the implant body within an intervertebral space and positioning the first and second substantially planar surfaces adjacent respective first and second vertebral bodies; and

expanding the outer cross section of the implant body along each of the first and second transverse dimensions and engaging the first and second substantially planar surfaces against the respective first and second vertebral bodies, the expanding including flexible material deformation of the movable branch portions relative to the fixed base portion.

2. The method of claim 1 , wherein the movable portions cooperate to define an inner chamber extending along the longitudinal axis; and

further comprising positioning a bone growth promoting material within the inner chamber.

3. The method of claim 2 , wherein the bone growth promoting material comprises a bone morphogenic protein.

4. The method of claim 1 , wherein the movable portions cooperate to define an inner chamber extending along the longitudinal axis; and

wherein the expanding results from axially displacing an expansion member along the inner chamber.

5. The method of claim 4 , further comprising positioning a bone growth promoting material within the inner chamber.

6. The method of claim 1 , wherein the inserting comprises impacting the spinal implant into the intervertebral space.

7. The method of claim 1 , wherein the inserting comprises pushing the spinal implant into the intervertebral space.

8. The method of claim 1 , wherein the inserting comprises displacing the spinal implant generally along the longitudinal axis without rotating the spinal implant.

9. The method of claim 1 , wherein the expanding occurs along a height dimension of the intervertebral space and along a lateral dimension of the intervertebral space.

10. The method of claim 1 , wherein each of the four movable portions has a substantially equal height and width and cooperate to provide the implant body with a square-shaped cross section.

11. The method of claim 1 , wherein the implant body has a substantially parallelepiped configuration.

12. A surgical method, comprising:

providing an expandable spinal implant having a fixed base portion and four movable portions extending from the fixed base portion along a longitudinal axis and formed integral with the fixed base portion to define a unitary, single-piece implant body, each of the four movable portions having a substantially equal size and defining a rectangular-shaped cross section, the four movable portions cooperating to provide the implant body with an implant height and width that together define a non-threaded outer transverse cross section including first and second substantially planar surfaces disposed generally opposite one another and extending across the implant width;

inserting the implant body within an intervertebral space;

positioning the first and second substantially planar surfaces adjacent respective first and second vertebral bodies; and

expanding the implant body along both the implant height and the implant width, the expanding including flexible material deformation of the movable branch portions relative to the fixed base portion.

13. The method of claim 12 , wherein the implant defines an inner chamber extending along the longitudinal axis; and

further comprising positioning a bone growth promoting material within the inner chamber.

14. The method of claim 12 , wherein the movable portions cooperate to define the first and second substantially planar surfaces; and

wherein the expanding comprises displacing the movable portions along both the implant height and the implant width.

15. The method of claim 12 , wherein the movable portions cooperate to define an inner chamber extending along the longitudinal axis; and

wherein the expanding results from axially displacing an expansion member along the inner chamber.

16. The method of claim 12 , wherein each of the four movable portions has a substantially equal height and width and cooperate to provide the implant body with a square-shaped cross section.

17. A surgical method, comprising:

providing an expandable spinal implant having a fixed base portion and four movable portions extending from the fixed base portion along a longitudinal axis and formed integral with the fixed base portion to define a unitary, single-piece implant body, each of the four movable portions having a substantially equal size and defining a rectangular-shaped cross section, the four movable portions cooperating to provide the implant body with an implant height and width that together define a generally rectangular, non-threaded outer transverse cross section along the longitudinal axis;

inserting the implant body within an intervertebral space;

positioning the implant such that the implant width is arranged generally parallel with endplates of adjacent vertebral bodies; and

expanding the implant body along both the implant height and the implant width, the expanding including flexible material deformation of the movable branch portions relative to the fixed base portion.

18. The method of claim 17 , wherein the outer transverse cross section of the implant body includes first and second substantially planar surfaces disposed generally opposite one another and extending across the implant width; and

further comprising positioning the first and second substantially planar surfaces adjacent respective ones of the adjacent vertebral bodies prior to the expanding.

19. The method of claim 17 , wherein the movable portions cooperate to define an inner chamber extending along the longitudinal axis; and

wherein the expanding results from axially displacing an expansion member along the inner chamber.

20. The method of claim 17 , wherein each of the four movable portions has a substantially equal height and width and cooperate to provide the implant body with a square-shaped cross section.

21. A surgical method, comprising:

providing an expandable spinal implant having a fixed base portion and four movable portions extending from the fixed base portion along a longitudinal axis and formed integral with the fixed base portion to define a unitary, single-piece implant body, each of the four movable portions having a substantially equal size and defining a rectangular-shaped cross section, the four movable portions cooperating to provide the implant body with an implant height and width, each of the four movable portions of the implant body including substantially planar inner surfaces that cooperate to define an inner chamber having a rectangular inner transverse cross section along the longitudinal axis, the inner surfaces defining an inward taper along the longitudinal axis;

inserting the implant body within an intervertebral space;

expanding the implant body along both the implant height and the implant width by axially displacing an expansion member along the inner chamber, the displacing resulting in sliding engagement of substantially planar outer surfaces of the expansion member along the substantially planar inner surfaces of the implant, the expanding including flexible material deformation of the movable branch portions relative to the fixed base portion.

22. The method of claim 21 , wherein the implant height and width cooperate to provide the implant body with an outer transverse cross section including first and second substantially planar surfaces disposed generally opposite one another and extending across the implant width; and

further comprising positioning the first and second substantially planar surfaces adjacent respective first and second vertebral bodies prior to the expanding.

23. The method of claim 21 , further comprising positioning a bone growth promoting material within the inner chamber.

24. The method of claim 21 , wherein each of the four movable portions has a substantially equal height and width and cooperate to provide the implant body with a square-shaped cross section.