Self-retaining driver for a bone screw

Patent metadata

Field	Value
Publication number	US-9931149-B2
Application number	US-201615148190-A
Country	US
Kind code	B2
Filing date	May 6, 2016
Priority date	Jul 25, 2013
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A driver instrument for engaging and transferring rotational torque to a bone anchor already screwed into a bony structure. The driver instrument may be advanced through an incision while disengaged from the bone anchor and thereafter engaged in a driver socket of the bone anchor. The driver instrument includes an elongate shaft extending distally from a handle, a tapered distal tip, and a driver engagement feature located proximally of the tapered distal tip. The tapered distal tip and the driver engagement feature are configured such that the longitudinal rotational axis of the driver instrument automatically moves into parallel alignment with the longitudinal rotational axis of the bone anchor as the driver engagement feature of the driver instrument is advanced into the driver socket of the bone anchor.

First claim

What is claimed is:

1. A medical device system comprising:
a bone anchor comprising:
a bone screw having a first longitudinal axis;
a driver socket located at an end of the bone screw; and
a housing pivotally coupled to the end of the bone screw, the housing having a second longitudinal axis that can be rotated up to a first angle from the first longitudinal axis of the bone screw such that the housing at least partially obstructs the driver socket of the bone screw, the housing comprising:
a pair of legs defining a channel therebetween, the channel having a first portion adjacent the bone screw configured to receive an elongate stabilization member and a second portion adjacent the first portion configured to receive a locking member; and

a first driver instrument comprising:
a shaft having a third longitudinal axis;
a driver engagement feature disposed at an end of the shaft; and
a distal tip disposed at an end of the driver engagement feature;

wherein the distal tip is tapered at a second angle relative to the third longitudinal axis of the shaft such that the distal tip is able to enter the driver socket even when the housing is displaced at the first angle.

2. The medical device system of claim 1 , wherein the bone screw further comprises a head at the end of the bone screw, wherein the driver socket is disposed in the head and the housing is pivotally coupled to the head.

3. The medical device system of claim 1 , wherein the bone screw can be rotationally advanced while the second longitudinal axis of the housing is aligned with the first longitudinal axis of the bone screw.

4. The medical device system of claim 1 , wherein the distal tip is angled to allow the first driver to engage the driver socket when the housing is non-coaxially aligned with the driver socket.

5. The medical device system of claim 1 , wherein the second angle is less than the first angle.

6. The medical device system of claim 1 , wherein the second angle is in the range of about twenty five degrees to about seventy five degrees.

7. The medical device system of claim 1 , wherein the driver engagement feature comprises a plurality of planar engagement surfaces disposed in a nonparallel orientation in reference to the third longitudinal axis of the first driver instrument.

8. The medical device system of claim 7 , wherein the plurality of planar engagement surfaces facilitate parallel alignment of the first driver instrument and the bone anchor.

9. The medical device system of claim 7 , wherein the driver socket includes six engagement surfaces and the driver engagement feature of the first driver instrument is a hexalobular internal driving feature having six engagement surfaces configured to engage the six engagement surfaces of the driver socket.

10. The medical device system of claim 1 , wherein, an opening into the driver socket includes a beveled rim to facilitate advancement of the distal tip into the driver socket.

11. The medical device system of claim 1 , further comprising a sleeve disposed along the shaft that maintains the second longitudinal axis of the housing aligned with the first longitudinal axis of the bone screw when the driver engagement feature is inserted in the driver socket.

12. The medical device system of claim 1 , further comprising a second driver instrument having a distal tip different than the distal tip of the first driver instrument.

13. A method of engaging a driver instrument with a bone anchor, the method comprising:
advancing a driver instrument toward a housing of a bone screw while a first longitudinal axis of the housing is offset from a second longitudinal axis of the bone screw such that the housing at least partially obstructs a driver socket of the bone screw;
while the housing at least partially obstructs the driver socket of the bone screw a tapered distal tip of the driver instrument into the driver socket of the bone screw to align a driver engagement feature of the driver instrument with the driver socket; and
advancing the driver engagement feature of the driver instrument into the driver socket of the bone screw to align the first longitudinal axis of the housing with the second longitudinal axis of the bone screw.

14. The method of claim 13 , further comprising rotating the bone anchor relative to a bony structure with the driver instrument.

15. The method of claim 13 , further comprising removing the bone anchor from a surgical tray with the driver instrument.

16. The method of claim 13 , further comprising engaging the tapered distal tip of the driver instrument with a beveled edge of the driver socket to advance the tapered distal tip of the driver instrument in to the driver socket of the bone screw.

17. The method of claim 13 , further comprising advancing the tapered distal tip of the driver instrument into the driver socket when the first longitudinal axis of the housing is displaced at a maximum angle from the second longitudinal axis of the bone screw.

18. The method of claim 14 , wherein the tapered distal tip is tapered at a first angle relative to a third longitudinal axis of the driver instrument, the first angle being less than a maximum angle.

19. The method of claim 18 , further comprising engaging a sleeve of the driver instrument with the housing of the bone screw to facilitate alignment of the first longitudinal axis of the housing and the third longitudinal axis of the driver instrument.

20. The method of claim 18 , wherein the driver engagement feature comprises a plurality of planar engagement surfaces disposed nonparallel to the third longitudinal axis of the driver instrument.

21. The method of claim 13 , further comprising:
initially installing the bone screw into a boney structure located internal to an incision using the driver instrument while the tapered distal tip is extended through the housing;
withdrawing the distal tip from the housing and the incision; and
allowing the first longitudinal axis of the housing to become offset from the second longitudinal axis of the bone screw so that the housing at least partially obstructs the driver socket of the bone screw.

Assignees

• Zimmer Spine Inc

Inventors

• Jerke Eric P

Classifications

• A61B17/8883

  the driver bit acting on the periphery of the screw head · CPC title

• A61B17/888 Primary

  the driver bit acting on the central region of the screw head · CPC title

• A61B17/8891

  at its periphery · CPC title

• A61B17/8886

  holding the screw head · CPC title

• A61B17/8888

  at its central region · CPC title