Anterior tether tensioner
A tether tensioner includes a handle assembly, an elongate member extending distally from the handle assembly, and an engaging portion. The handle assembly includes a stationary member, a trigger pivotably coupled to the stationary member, and a spool rotatably supported on the stationary member. The spool is configured to wrap a tether thereabout. The spool is operatively coupled with the trigger such that pivoting of the trigger relative to the stationary member causes rotation of the spool. The elongate member includes a channel configured to slidably receive a tether therethrough. The engaging portion is configured to receive a head portion of a bone screw such that a tether extends from the head portion disposed in the engaging portion to the spool through the channel of the elongate member.
1. A tether tensioner comprising:
a handle assembly including:
a stationary member;
a trigger pivotably coupled to the stationary member; and
a spool rotatably supported on the stationary member, the spool configured to wrap a tether thereabout, the spool operatively coupled with the trigger such that pivoting of the trigger relative to the stationary member causes rotation of the spool:
an elongate member extending distally from the handle assembly, the elongate member including a channel configured to slidably receive a tether therethrough; and
an engaging portion configured to receive a head portion of a bone screw such that a tether extends from the head portion disposed in the engaging portion to the spool through the channel of the elongate member, the tether configured to be locked within the engaging portion by compression between surfaces.
2. The tether tensioner according to claim 1 , wherein the handle assembly further includes a ratchet wheel operatively coupled with the spool for concomitant rotation therewith.
3. The tether tensioner according to claim 2 , wherein the trigger includes a rack including teeth to engage teeth of the ratchet wheel.
4. The tether tensioner according to claim 3 , wherein the handle assembly further includes a biasing member to urge the rack towards engagement with the ratchet wheel.
5. The tether tensioner according to claim 3 , wherein the handle assembly further includes a biasing member to urge the trigger away from the stationary member.
6. The tether tensioner according to claim 1 , wherein the spool of the handle assembly and the channel of the elongate member are axially aligned.
7. The tether tensioner according to claim 1 , wherein the engaging portion is disposed at a distal portion of the elongate member.
8. The tether tensioner according to claim 1 , wherein the elongate member is substantially parallel to the stationary member of the handle assembly.
9. The tether tensioner according to claim 1 , wherein the engaging portion includes a chamber defining an aperture to receive a head portion of a bone screw therethrough.
10. The tether tensioner according to claim 9 , wherein the elongate member defines a bore dimensioned to receive a tether therethrough, the bore in communication with the aperture of the chamber of the engaging portion.
11. The tether tensioner according to claim 9 , wherein the engaging portion is positioned with a tether receiving channel of the tensioner aligned with a tether receiving slot of the head of the bone screw.
12. The tether tensioner according to claim 9 , wherein the chamber includes an inner wall having threads to threadably secure a set screw of a bone screw thereto.
13. The tether tensioner according to claim 1 , wherein the elongate member defines a groove along a length thereof, the groove configured to receive a driver to drive a set screw of a bone screw, wherein the groove of the elongate member is aligned with the engaging portion.
14. A method of applying tension to a tether comprising:
securing a first end portion of a tether relative to a bone screw; and
passing a second end portion of the tether through a first slot in a bone screw and through a second slot defined in a distal end of an engaging portion of a tether tensioner;
extending the second end portion of the tether through a bore defined in an elongate member of the tether tensioner towards a handle assembly of the tether tensioner;
wrapping the second end portion of the tether around a spool of the handle assembly;
placing the engaging portion of the tether tensioner over a head portion of the bone screw such that the tether extends through the first slot defined in the head portion of the bone screw and the second slot of the engaging portion;
rotating the spool to provide tension in the tether; and securing the tether to the bone screw.
15. The method according to claim 14 , further comprising manipulating the tether to provide proper tension prior to rotating the spool.
16. The method according to claim 14 , further comprising partially securing the tether to the bone screw prior to rotating the spool.
17. The method according to claim 16 , wherein the step of securing the first end portion relative to the bone screw further comprises securing the first end portion of the tether to the bone screw and looping the tether around an anatomical structure before passing the second end portion of the tether through the first and second slots of the bone screw and the engaging portion.
18. The method according to claim 14 , further comprising feeding the second end portion of the tether through a channel of the elongate member and towards the handle assembly of the tether tensioner.
19. The method according to claim 14 , wherein securing the tether to the bone screw includes threadably coupling a set screw disposed in the engaging portion to the head portion of the bone screw to secure the tether therebetween.
20. The method of claim 19 , where the set screw includes a first non-planar surface and the first slot of the bone screw includes a second non-planar surface, the method further comprising tightening the set screw to apply a pressure between the first and second non-planar surfaces to lock the tether disposed therebetween and extending through the first slot.