Transpedicular intervertebral disk access methods and devices
Methods and devices for treating diseases and conditions that change the spacial relationship between the vertebral bodies and the intervertebral disks, or that cause instability of the vertebral column, or both, and a method and devices that allow the surgeon to access the intervertebral space to restore a more normal three-dimensional configuration of the space, with or without additionally fusing two adjacent vertebrae.
1. A cutting device for use in percutaneous procedures, the device comprising:
a shaft extending along a longitudinal axis between a proximal portion and a distal portion, the shaft comprising a flexible section adjacent the distal portion;
a cutting head extending from the distal portion of the shaft, the cutting head comprising:
a first blade extending from a central portion of the cutting head, the first blade movable between a first insertion configuration and a first cutting configuration, wherein the first blade extends generally along the longitudinal axis of the shaft in the first insertion configuration and extends generally perpendicular to the longitudinal axis in the first cutting configuration;
a second blade extending from the central portion of the cutting head, the second blade movable between a second insertion configuration and a second cutting configuration, wherein the second blade extends generally along the longitudinal axis of the shaft in the second insertion configuration and extends generally perpendicular to the longitudinal axis opposite the first blade in the second cutting configuration;
a first wing extending from a distal end of the first blade at a first oblique angle relative to the first blade such that the first wing extends at an oblique angle with respect to the longitudinal axis of the shaft when the first blade is in both the first insertion configuration and the first cutting configuration, the first wing extending distally beyond the distal end of the first blade and having a distal most tip pointing inwardly toward the longitudinal axis when the first blade is in the first insertion configuration;
a second wing extending from a distal end of the second blade at a second oblique angle relative to the second blade such that the second wing extends at an oblique angle with respect to the longitudinal axis of the shaft when the second blade is in both the second insertion configuration and the second cutting configuration, the second wing extending distally beyond the distal end of the second blade and having a distal most tip pointing inwardly toward the longitudinal axis when the second blade is in the second insertion configuration;
a first transition portion defined by a first interface between the distal end of the first blade and a proximal end of the first wing, the first transition portion being an arcuate bend such that the distal end of the first blade, the first transition portion, and the proximal end of the first wing have a substantially constant thickness; and
a second transition portion defined by a second interface between the distal end of the second blade and a proximal end of the second wing, the second transition portion being an arcuate bend such that the distal end of the second blade, the second transition portion, and the proximal end of the second wing have a substantially constant thickness;
wherein the first and second wings facilitate passage of the cutting head through an access sheath;
a retracting assembly movably coupled to the shaft, the retracting assembly movable along the longitudinal axis relative to the cutting head for selectively moving the first and second blades between the first and second insertion configurations and the first and second cutting configuration, the retracting assembly comprising a hypo-tube for selectively receiving and enclosing the first and second blades to hold the first and second blades in the first and second insertion configurations; and
a bearing assembly adjacent the proximal portion of the shaft, the bearing assembly comprising a pair of bearings positioned within at least one housing, the bearings engaging a collet attached to the shaft, the collet sized and shaped for attachment to a motive source.
2. The device of claim 1 wherein the shaft, the first and second blades, and the first and second wings are integrally formed from a resiliently flexible material.
3. The device of claim 2 , wherein the resiliently flexible material comprises nitinol.
4. The device of claim 3 , wherein the first oblique angle is between about 130° and about 140° .
5. The device of claim 4 , wherein the second oblique angle is between about 130° and about 140° .
6. The device of claim 5 , wherein the flexible section of the shaft comprises a plurality of slots formed in the shaft.
7. The device of claim 1 , wherein the first and second blades are biased towards the first and second cutting configurations.
8. The device of claim 7 , wherein the first and second blades are substantially symmetrical about the longitudinal axis.
9. The device of claim 1 , wherein the first and second blades are asymmetrical about the longitudinal axis.
10. The device of claim 1 , wherein the flexible section of the shaft comprises a coil.
11. A cutting device for use in percutaneous procedures, the device comprising:
a shaft extending along a longitudinal axis between a proximal portion and a distal portion, the shaft comprising a flexible section adjacent the distal portion, at least the flexible section of the shaft having an outer diameter sized to allow the shaft to be translated through an access sheath having a curve of at least 75° relative to the longitudinal axis;
a cutting head extending from the distal portion of the shaft, the cutting head comprising:
a first blade having a main portion adjacent the shaft and a wing portion extending from the main portion and spaced from the shaft, the first blade having a bend between the main portion and the wing portion such that the wing portion extends at an oblique angle relative to the main portion, the first blade having opposing planar surfaces and a constant thickness between the opposing planar surfaces across the main and wing portions;
a second blade having a main portion adjacent the shaft and a wing portion extending from the main portion and spaced from the shaft, the second blade having a bend between the main portion and the wing portion such that the wing portion extends at an oblique angle relative to the main portion, the second blade having opposing planar surfaces and a constant thickness between the opposing planar surfaces across the main and wing portions;
the first and second blades movable between an insertion configuration and a cutting configuration, where the first and second blades extend generally along the longitudinal axis of the shaft in the insertion configuration and extend generally perpendicular to the longitudinal axis in the cutting configuration;
wherein the first and second blades comprise a resiliently flexible material biased towards the cutting configuration;
wherein the wing portions of the first and second blades each have a distal most tip pointing inwardly toward the longitudinal axis when the first and seconds blade are in the insertion configuration; and
a retracting assembly movably coupled to the shaft, the retracting assembly movable along the longitudinal axis relative to the cutting head for selectively moving the first and second blades between the insertion configuration and the cutting configuration, the retracting assembly comprising a hypo-tube for selectively receiving and enclosing the first and second blades to hold the first and second blades in the insertion configurations.
12. The device of claim 11 , wherein the first and second blades extend substantially symmetrically relative to the longitudinal axis.
13. The device of claim 12 , wherein the wing portions of the first and second blades extend at an oblique angle between about 130° and about 140° relative to the main portions of the first and second blades, respectively.
14. The device of claim 13 , wherein the shaft and the cutting head are integrally formed.
15. The device of claim 14 , wherein the resiliently flexible material is nitinol.
16. The device of claim 15 , wherein the flexible section of the shaft comprises a plurality of slots formed in the shaft.
17. The device of claim 16 , further comprising:
a bearing assembly surrounding at least part of the proximal portion of the shaft, the bearing assembly comprising a pair of bearings positioned within at least one housing, the bearings engaging a collet attached to the shaft, the collet sized and shaped for attachment to a motive source.
18. The device of claim 17 , wherein the retracting assembly is attachable to a handle portion of the device when the first and second blades are in the cutting position.
19. The device of claim 11 , wherein a majority of the first blade has a constant width across the main and wing portions in a direction perpendicular to the thickness between the opposing planar surfaces.