Multiple set screw insertion instrument and methods
This disclosure relates generally to surgical instruments used to deliver locking or set screws to secure a rod or spinal fixation element relative to an implanted bone anchor or other spinal fixation construct during spine surgery. In one embodiment, the inserter instrument can include an inner driver shaft, a ratcheted outer sleeve, and a handle configured to receive the shafts therein. The inner driver shaft can receive a plurality of set screws on a distal end thereof. A side latch, pawl, or button can engage with the ratcheted outer sleeve to facilitate step-wise advancement of the sleeve relative to the driver shaft for set screw delivery. Step-wise advancement can be controlled using another button that causes movement of the side latch.
1. A surgical instrument, comprising:
a shaft with a distal portion configured to drive a set screw and seat a plurality of set screws stacked against one another on the shaft;
a handle coupled to the shaft;
a sleeve disposed over the shaft and configured to contact a proximal-most set screw stacked on the shaft;
a first button disposed in the handle and configured to advance the sleeve distally relative to the shaft by a first increment; and
a second button disposed in the handle and configured to permit retraction of the sleeve proximally.
2. The instrument of claim 1 , wherein the sleeve includes a plurality of ratchet teeth.
3. The instrument of claim 2 , wherein the first increment corresponds to a distance between two adjacent teeth of the plurality of ratchet teeth.
4. The instrument of claim 2 , further comprising a detent disposed in the handle that is configured to interface with the plurality of ratchet teeth to resist movement of the sleeve.
5. The instrument of claim 4 , wherein the detent is a spring-biased ball.
6. The instrument of claim 2 , wherein the second button is biased to contact a ratchet tooth of the plurality of ratchet teeth.
7. The instrument of claim 6 , wherein the second button permits proximal retraction of the sleeve when the bias of the second button is overcome.
8. The instrument of claim 1 , further comprising a spring clip disposed around a distal end of the shaft and configured to retain a set screw thereon by interference fit.
9. The instrument of claim 1 , wherein movement of the first button translates the second button distally.
10. The instrument of claim 9 , wherein the first button is biased proximally such that proximal movement of the first button moves the second button proximally relative to the sleeve.
11. The instrument of claim 1 , wherein an outer diameter of the plurality of set screws stacked on the shaft is substantially equal to an outer diameter of the sleeve disposed over the shaft.
12. The instrument of claim 1 , wherein the sleeve further comprises a retention mechanism thereon for preventing ejection of the sleeve from the handle.
13. The instrument of claim 12 , wherein the retention mechanism abuts the second button to retain the sleeve within the handle.
14. The instrument of claim 1 , wherein the first button is disposed on a proximal end of the handle and the second button is disposed on a side of the handle.