Tightening device for spine surgery

1. A system for tightening a locking cap onto at least a portion of a pedicle screw during spinal surgery, the system comprising:

a torque-generating body having a proximal end and an opposing distal end and defining a longitudinal axis extending therebetween, the distal end coupled to a handle;

a drive shaft rotatably driven by the torque-generating body, the drive shaft having a proximal end, an opposing distal end and a longitudinal axis extending therebetween, the proximal end of the drive shaft being operatively engaged to the distal end of the torque-generating body, the opposing distal end of the drive shaft engaging at least a portion of one of a locking cap and the pedicle screw, wherein rotation of said handle about the longitudinal axis of the drive shaft causes the drive shaft to rotate;

a gearbox operatively coupled to the torque-generating body and the drive shaft;

an anti-torque device comprised of an elongated and generally hollow member, the anti-torque device having a proximal end and an opposing distal end, the proximal end of the anti-torque device being fixed from rotating relative to at least a portion of the torque-generating body; and

an end member provided at a distal end of the gearbox, the end member having a non-circular curvilinear shape in cross section including at least one generally planar surface, where the drive shaft is rotatably received within a central opening of the end member,

wherein the proximal end of the anti-torque device comprises a longitudinally extending keyed interface which is slidably engaged to a corresponding longitudinally extending receiving face provided on the planar surface of the end member,

wherein neither the end member nor the anti-torque device include a threaded engagement feature such that engagement between an outer surface of the end member and the longitudinally extending keyed interface of the anti-torque device couples the end member to the anti-torque device and fixes the end member from rotating relative to the anti-torque device.

2. The system of claim 1 , wherein the distal end of the anti-torque device is fixed from rotating relative to at least a portion of one of the pedicle screw and a fixation rod.

3. The system of claim 1 , wherein the anti-torque device and torque-generating body cooperate to create a generally balanced reaction between a locking torque T L generated by the torque-generating body and an opposite reaction torque TR generated by the anti-torque device.

4. The system of claim 3 , wherein the torque T L generated by the torque-generating body is provided to one of the locking cap and the pedicle screw, and the opposite reaction torque T R generated by the anti-torque device is provided to one of the locking cap, the pedicle screw and a fixation rod.

5. The system of claim 1 , wherein the torque-generating body is one of a motorized power tool, a pressurized fluid or a hand-actuated screwdriver.

6. The system of claim 1 , wherein the anti-torque device is removably attached to the torque-generating body.

7. The system of claim 1 , wherein the anti-torque device comprises an opening formed on a side wall proximate a connection point between the distal end of the drive shaft and at least a portion of one of a locking cap and the pedicle screw,

wherein the anti-torque device comprises radially spaced-apart archways that extend radially inwardly from the distal end of the anti-torque device, the archways radially spaced-apart from the opening.

8. The system of claim 7 , wherein a portion of one of the archways engages at least a portion of a fixation rod to maintain the distal end of the anti-torque device stationary.

9. The system of claim 1 , wherein an interior surface of the distal end of the anti-torque device includes at least one of a recess and a protrusion sized and configured to engage the portion of the one of the locking cap, the pedicle screw and the fixation rod.

10. The system of claim 1 , wherein the gearbox receives input torque from the torque-generating body and increases output torque of the drive shaft.

11. The system of claim 1 , wherein the gearbox comprises a first gear operatively coupled to the distal end of the torque-generating body, and a first spur gear that operatively engages the first gear,

wherein the first spur gear has a greater number of gear teeth than a number of gear teeth of the first gear.

12. The system of claim 11 , wherein the first spur gear has twice the number of gear teeth as the first gear.

13. The system of claim 11 , wherein the gear box further comprises a second spur gear,

wherein a spur of the first spur gear operatively engages the second spur gear,

wherein the second spur gear has a greater number of gear teeth then a number of gear teeth of the spur.

14. The system of claim 13 , wherein the second spur gear has twice the number of gear teeth as the spur of the first spur gear.

15. The method of claim 13 , wherein a proximal end of the drive shaft is operatively engaged with the second spur gear.

16. The method of claim 15 , wherein at least a portion of the proximal end of the drive shaft extends through at least a central portion of the second spur gear and is fixedly connected thereto.

17. The system of claim 1 , wherein the keyed interface of the anti-torque device is provided on a surface of a central opening extending through the anti-torque device,

wherein the central opening of the anti-torque device has a non-circular shape in cross-section corresponding to the cross-sectional shape of the end member and including at least one generally planar surface,

wherein the keyed interface of the anti-torque device is provided the planar surface of the central opening.

18. The system of claim 17 , wherein the end member is slidably received within the central opening of the anti-torque device.