Band tensioning system
A band tensioner includes a shank, a head, and a tensioning mechanism disposed within the head. The shank is configured to secure the band tensioner to a first bony element and the head is secured to an end of the shank. The tensioning mechanism is configured to lengthen and shorten a flexible implant relative to the head of the band tensioner.
1. A band tensioner comprising:
a shank configured to secure the band tensioner to a first bony element;
a head secured to an end of the shank; and
a tensioning mechanism disposed within the head and configured to lengthen and shorten a flexible implant relative to the head of the band tensioner, the tensioning mechanism including a band shaft and a drive gear,
wherein the tensioning mechanism includes a retainer that is received within the head and engaged with the band shaft and the drive gear such that the retainer receives the drive gear to secure the band shaft and the drive gear within the head.
2. The band tensioner according to claim 1 , wherein;
the band shaft defines a shaft axis and a slot therethrough, the slot is configured to receive a portion of the flexible implant such that the flexible implant is wound around the band shaft in response to rotation of the band shaft about the shaft axis in a first direction and is unwound from about the shaft in response to rotation of the band shaft about the shaft axis in a second direction opposite the first direction.
3. The band tensioner according to claim 2 , wherein;
the drive gear defines a drive axis, the drive gear operably associated with the band shaft such that rotation of the drive gear in a first drive direction about the drive axis rotates the band shaft in the first direction and rotation of the drive gear in a second drive direction opposite the first drive direction rotates the band shaft in the second direction.
4. The band tensioner according to claim 3 , wherein the drive axis is perpendicular to the shaft axis.
5. The band tensioner according to claim 2 , wherein;
the shank defines a longitudinal axis of the band tensioner, the shaft axis perpendicular to the longitudinal axis.
6. The band tensioner according to claim 1 , wherein;
the shank defines a channel that passes therethrough, the shank configured to pass entirely through a bony element such that the channel is defined entirely through the bony element.
7. A spinal construct comprising:
a flexible implant; and
a band tensioner including:
a shank configured to secure the band tensioner to a bony element;
a head secured to an end of the shank; and
a tensioning mechanism disposed within the head and configured to lengthen and shorten the flexible implant relative to the head of the band tensioner, the tensioning mechanism including a band shaft and a drive gear,
wherein the tensioning mechanism includes a retainer that is received within the head and engaged with the band shaft and the drive gear such that the retainer receives the drive gear to secure the band shaft and the drive gear within the head.
8. The spinal construct according to claim 7 , wherein;
the a band shaft defines a shaft axis and a slot therethrough, the slot receiving a portion of the flexible implant such that the flexible implant is wound around the band shaft in response to rotation of the band shaft about the shaft axis in a first direction and is unwound from about the shaft in response to rotation of the band shaft about the shaft axis in a second direction opposite the first direction.
9. The spinal construct according to claim 8 , wherein;
the drive gear defines a drive axis, the drive gear operably associated with the band shaft such that rotation of the drive gear in a first drive direction about the drive axis rotates the band shaft in the first direction and rotation of the drive gear in a second drive direction opposite the first drive direction rotates the band shaft in the second direction.
10. The spinal construct according to claim 9 , wherein;
the drive axis is perpendicular to the shaft axis.
11. The spinal construct according to claim 7 , wherein;
the shank defines a channel that passes therethrough, the shank configured to pass entirely through a bony element such that the channel is defined entirely through the bony element.
12. A method of correcting a defect of a spine, the method comprising:
securing a shank of a band tensioner to a vertebra of the spine;
securing a flexible implant within a tensioning mechanism of the band tensioner; and
tensioning the flexible implant with the tensioning mechanism,
wherein the tensioning mechanism includes a band shaft, a drive gear and a retainer received within a head of the band tensioner, wherein the retainer receives the drive gear to secure the band shaft and the drive gear within the head, and tensioning the flexible implant with the tensioning mechanism includes engaging the retainer with the band shaft and the drive gear.
13. The method according to claim 12 , wherein;
securing the band tensioner to the vertebra includes passing the shank of the band tensioner through the vertebra.
14. The method according to claim 13 , wherein;
securing the flexible implant within the tensioning mechanism includes passing the flexible implant through a channel defined by the shank such that the flexible implant passes entirely through the vertebra.
15. The method according to claim 12 , wherein;
securing the flexible implant within the tensioning mechanism includes passing the flexible implant through a slot defined in a band shaft of the tensioning mechanism.
16. The method according to claim 15 , wherein;
tensioning the flexible implant includes rotating the band shaft about a shaft axis such that the flexible implant is wound around the band shaft.
17. The method according to claim 12 , wherein;
securing the band tensioner to the vertebra includes passing a tip of a driver through a first opening in the head of the band tensioner to rotate the band tensioner about a longitudinal axis thereof to thread the shank of the band tensioner into the vertebra.
18. The method according to claim 17 , wherein;
tensioning the flexible implant includes passing the tip of the driver through a second opening in the head of the band tensioner which is offset from the first opening to rotate the drive gear of the tensioning mechanism.
19. The method according to claim 12 , wherein;
tensioning the flexible implant includes engaging an opening in the head with a tip of an alignment tool to rotatably fix the band tensioner about a longitudinal axis thereof and passing a driver through a driver channel of the alignment tool such that a tip of the driver passes through the tip of the alignment tool to engage the drive gear of the tensioning mechanism.