Extension ready spinal support systems
An “extension ready” spinal support system that enables the extension to be accomplished with minimal disturbance to an existing spinal support structure to which the extension system is coupled. In some embodiments, the existing spinal support rod and pedicle screws can remain intact while extension subassemblies are mounted directly to the existing base rod receptacles. The extension subassemblies include a skirt portion that surrounds and engages the existing base receptacle to prevent splaying of the base receptacle. Additional resistance to splaying may be provided by a canted thread arrangement between the skirt and the base receptacle. In some embodiments, the extension receptacle is provided with a low profile (i.e., shortened axial length from the base rod receptacle) by providing a monoaxial rotation structure that rotates about but does not pitch relative to the extension axis and is shorter relative to polyaxial rotation structures.
1. A spinal support system, comprising:
a first rod receptacle for mounting to a pedicle screw, said first rod receptacle having a first side wall defining a first pair of diametrically opposed slots that extend axially along said first side wall and are open at a proximal end of said first rod receptacle; and
an extension assembly including a second rod receptacle mounted to a base portion, said second rod receptacle including an internal flange having an interior face and defining an axial thickness, said base portion including a mounting platform, said second rod receptacle having a second side wall defining a second pair of diametrically opposed slots that extend axially along said second side wall and are open at a proximal end of said second rod receptacle, said extension assembly including a pivot member that includes a head portion and a shaft portion, said shaft portion being in fixed relationship with said mounting platform to define an axial gap dimension between said head portion and said mounting platform, said internal flange of said second rod receptacle being captured between said head portion and said mounting platform, said axial gap dimension being greater than said axial thickness of said internal flange to enable rotation of said extension rod receptacle about said head portion,
wherein said interior face of said internal flange of said second rod receptacle conforms to said head portion to limit said rotation of said extension rod receptacle about said head portion to a substantially monoaxial rotation.
2. The spinal support system of claim 1 , wherein said shaft portion includes a stop that cooperates with said base portion to define said axial gap dimension.
3. The spinal support system of claim 2 , wherein said stop engages said mounting platform to define said axial gap dimension.
4. The spinal support system of claim 1 , wherein said head portion is flat.
5. The spinal support system of claim 1 , wherein said axial gap dimension is predetermined.
6. The spinal support system of claim 1 , wherein:
said first side wall includes a first interior surface and a first exterior surface, said first interior surface defining first interior threads, said first exterior surface defining first exterior threads; and
said second side wall includes a second interior surface and a second exterior surface, said second interior surface defining second interior threads.
7. The spinal support system of claim 6 , wherein said base portion includes a skirt portion that extends from said mounting platform, said skirt portion including interior threads for mating with said first exterior threads of said first side wall.
8. The spinal support system of claim 1 , wherein said shaft portion is one of welded and swaged to said base portion.
9. The spinal support system of claim 1 , wherein a set screw portion is integral with and extends from a distal face of said mounting platform, said set screw portion including threads configured to mate with said first interior threads of said first rod receptacle.
10. The spinal support system of claim 9 , wherein said threads of said set screw portion and said first interior threads of said first rod receptacle define canted cantilever profiles configured to threadably engage each other.
11. The spinal support system of claim 10 , wherein said canted cantilever profiles extend radially and in a distal direction.
12. The spinal support system of claim 1 , comprising a pedicle screw coupled to a distal end portion of said first rod receptacle.
13. A spinal rod support system, comprising:
a base rod receptacle;
an extension rod receptacle including an internal flange at a distal end, said internal flange defining an axial thickness;
a base portion including a mounting platform;
means for coupling said base portion to said base rod receptacle;
a pivot member including a head portion and a shaft portion, said shaft portion being in a fixed relationship with a proximal face of said mounting platform to define an axial gap dimension between said head portion and said mounting platform that is greater than said axial thickness of said internal flange of said extension rod receptacle; and
means for coupling said pivot member to said base portion,
wherein said internal flange of said extension rod receptacle is captured between said head portion of said pivot member and said proximal face of said mounting platform, said axial thickness of said internal flange limiting a rotation of said extension rod receptacle about said head portion to a substantially monoaxial rotation.
14. The spinal rod support system of claim 13 , wherein said means for coupling said extension rod receptacle to said base portion includes said pivot member threadably engaged with said mounting platform.
15. The spinal rod support system of claim 13 , wherein said means for coupling said extension rod receptacle to said base portion includes said pivot member swaged to said mounting platform.
16. The spinal rod support system of claim 13 , wherein said means for coupling said extension rod receptacle to said base portion includes said pivot member fused to said mounting platform.
17. The spinal rod support system of claim 13 , wherein said pivot member is welded to a distal face of said base portion.
18. The spinal rod support system of claim 13 , wherein:
said base portion includes a skirt portion; and
said means for coupling said base portion to said base rod receptacle includes threaded engagement of said skirt portion to said base rod receptacle.
19. The spinal rod support system of claim 18 , wherein:
said base portion includes a set screw portion that is unitary with and extends from a distal face of said mounting platform; and
said means for coupling said base portion to said base rod receptacle includes threaded engagement of said set screw portion to said base rod receptacle.