System and methods for performing spinal fusion surgery

1. A sequential dilation system, comprising:

a first cannula having a first wall, a second wall, and opposing sidewalls each extending from a proximal end to a distal end and together having an oblong cross-section, the first cannula further having a first lumen extending from sidewall to sidewall and from the proximal end to the distal end, wherein the distal end of the first cannula includes a wedge, the distal end of the wedge comprising extensions of the first and second walls such that the first cannula has a first length dimension at a center that is greater than a second length dimension adjacent the sidewalls, the proximal end of the wedge having a pair of convergent tapered surfaces extending proximally into the first lumen and intersecting at an edge, thereby bifurcating the first lumen into a pair of distal channels at the distal end; and

a second cannula having a first wall, a second wall, and opposing sidewalls each extending from a proximal end to a distal end, and a lumen extending from sidewall to sidewall and from the proximal end to the distal end and a second lumen extending longitudinally therethrough, the second lumen having a length dimension, a width dimension, and an oblong cross-section taken across the width dimension, the second lumen dimensioned to slideably receive the first cannula therein.

2. The sequential dilation system of claim 1 , wherein the first cannula further comprises a pair of apertures at the distal end, the apertures in communication with the first lumen.

3. The sequential dilation system of claim 1 , wherein the second cannula has a first outer surface and a second outer surface opposite the first outer surface, wherein the first outer surface is curved and the second outer surface is planar.

4. The sequential dilation system of claim 3 , further comprising a first width extender configured to mate with the second cannula at the second surface to expand the width of the assembled sequential dilation system.

5. The sequential dilation system of claim 4 , further comprising a second width extender configured to mate with the first width extender to expand the width of the assembled sequential dilation system.

6. A sequential dilation system, comprising:

a first cannula having a first wall, a second wall, and opposing sidewalls each extending from a proximal end to a distal end and together having an oblong cross-section, the first cannula further having a first lumen extending from sidewall to sidewall and from the proximal end to the distal end, the first cannula further having a pair of distal openings at the distal end, the first cannula further having a lead element between the distal openings, wherein the lead element is tapered in a distal direction from the first and second walls of the first cannula; and

a second cannula having a first wall, a second Wall, and opposing sidewalls each extending from a proximal end to a distal end and a lumen extending from sidewall to sidewall and from the proximal end to the distal end, the lumen dimensioned to pass the first cannula therethrough, the first wall having a curved outer surface and the second wall having a planar outer surface.

7. The sequential dilation system of claim 6 , comprising a first width extender configured to slideably mate with the second planar wall of the second cannula and expand the width of the assembled sequential dilation system in a single direction.

8. The sequential dilation system of claim 6 , further comprising a second width extender configured to mate with the first width extender to further expand the width of the assembled sequential dilation system in the single direction.

9. A sequential dilation system, comprising:

a first cannula having a first wall, a second wall, and opposing sidewalls each extending from a proximal end to a distal end and together having an oblong cross-section, the first cannula further having a first lumen extending from sidewall to sidewall and from the proximal end to the distal end; and

a second cannula having a first wall, a second wall, and opposing sidewalls each extending from a proximal end to a distal end and a lumen extending from sidewall to sidewall and from the proximal end to the distal end, the lumen dimensioned to pass the first cannula therethrough, the first wall having a curved outer surface and the second wall having a planar outer surface, the second wall planar outer surface having an elongate engagement feature extending from the proximal end towards the distal end.

10. The sequential dilation system of claim 9 , wherein the elongate engagement feature is a recess extending through the proximal end towards the distal end.

11. The sequential dilation system of claim 9 , further comprising a first expander having an elongate raised protrusion that is configured and dimensioned to engage the elongate engagement feature.

12. The sequential dilation system of claim 9 , further comprising a first expander having a first side with a recess therein and a second side with a protrusion thereon, wherein the second side of the first expander is configured to mate with the second wall of the second cannula.

13. The sequential dilation system of claim 9 , further comprising:

a first expander having a first side and a second side, wherein the second side of the first expander is mateable with the second wall of the second cannula; and

a second expander mateable with the first side of the first expander.

14. The sequential dilation system of claim 9 , further comprising:

a first expander having an elongate recess extending from a proximal end towards a distal end of the first expander, wherein the first expander is mateable with the second wall of the second cannula; and

a second expander having an elongate raised protrusion that is configured and dimensioned to engage the elongate recess.