Bone anchor assemblies with orientation indicator

Patent metadata

Field	Value
Publication number	US-9833263-B2
Application number	US-201514685431-A
Country	US
Kind code	B2
Filing date	Apr 13, 2015
Priority date	Apr 13, 2015
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

Bone anchor assemblies are disclosed herein that include one or more features for indicating the relative positioning of the receiver member and the shank, or for selectively maintaining the receiver member and the shank in a fixed relative position. For example, the head of the shank can include a surface feature that interacts with a drag ring to provide tactile or audible feedback when the shank is positioned at a particular orientation with respect to the receiver member. By way of further example, the head of the shank and a compression cap disposed in the receiver member can each include engagement features that cooperate to allow for selective locking of the orientation of the shank with respect to the receiver member.

First claim

The invention claimed is:

1. A bone anchor assembly, comprising:
a bone anchor having a proximal head and a distal shank; and
a receiver member having a seat formed therein configured to movably seat the head of the bone anchor such that the shank of the bone anchor can be positioned at a plurality of angles with respect to the receiver member;
wherein the head of the bone anchor includes an orientation indication feature that engages an orientation indication feature of the receiver member to provide feedback when the shank is positioned in a predetermined orientation with respect to the receiver member,
wherein the indication feature of the head comprises a groove formed in the head, and wherein the indication feature of the receiver member comprises a drag ring configured to engage the groove when the shank is positioned in the predetermined orientation.

2. The assembly of claim 1 , wherein the groove extends circumferentially around the head, perpendicular to a longitudinal axis of the bone anchor.

3. The assembly of claim 1 , wherein the drag ring is seated within the groove only when the bone anchor is positioned at the predetermined orientation with respect to the receiver member.

4. The assembly of claim 1 , wherein the indication feature of the receiver member comprises a groove formed in the seat of the receiver member and wherein the indication feature of the head comprises a drag ring configured to engage the groove when the shank is positioned in the predetermined orientation.

5. The assembly of claim 1 , wherein the predetermined orientation is one in which the bone anchor is positioned at a maximum angle with respect to the receiver member.

6. The assembly of claim 1 , wherein the head includes a plurality of orientation indication features, each of the plurality of orientation indication features being configured to engage an orientation indication feature of the receiver member to provide feedback when the shank is positioned in a corresponding one of a plurality of predetermined orientations with respect to the receiver member.

7. A bone anchor assembly, comprising:
a bone anchor having a proximal head and a distal shank; and
a receiver member having a seat formed therein configured to movably seat the head of the bone anchor such that the shank of the bone anchor can be positioned at a plurality of angles with respect to the receiver member;
wherein the head of the bone anchor includes an orientation indication feature that engages an orientation indication feature of the receiver member to provide feedback when the shank is positioned in a predetermined orientation with respect to the receiver member, and
wherein the indication feature of the head comprises first and second radial protrusions formed on the head and wherein the indication feature of the receiver member comprises a drag ring configured to sit between the first and second radial protrusions when the shank is positioned in the predetermined orientation.

8. The assembly of claim 7 , wherein the first and second radial protrusions extend circumferentially around the head, perpendicular to a longitudinal axis of the bone anchor.

9. A bone anchor assembly, comprising:
a bone anchor having a proximal head and a distal shank; and
a receiver member having a seat formed therein configured to movably seat the head of the bone anchor such that the shank of the bone anchor can be positioned at a plurality of angles with respect to the receiver member;
wherein the head of the bone anchor includes an orientation indication feature that engages an orientation indication feature of the receiver member to provide feedback when the shank is positioned in a predetermined orientation with respect to the receiver member,
wherein the indication feature of the receiver member comprises first and second radial protrusions formed on the seat of the receiver member and wherein the indication feature of the head comprises a drag ring configured to sit between the first and second radial protrusions when the shank is positioned in the predetermined orientation.

10. A bone anchor assembly, comprising:
a bone anchor having a proximal head and a distal shank; and
a receiver member having a seat formed therein configured to movably seat the head of the bone anchor such that the shank of the bone anchor can be positioned at a plurality of angles with respect to the receiver member;
wherein the head of the bone anchor includes an orientation indication feature that engages an orientation indication feature of the receiver member to provide feedback when the shank is positioned in a predetermined orientation with respect to the receiver member, and
wherein the predetermined orientation is one in which a longitudinal axis of the bone anchor is parallel to a longitudinal axis of the receiver member.

11. A bone anchor assembly, comprising:
a bone anchor having a proximal head and a distal shank; and
a receiver member having a seat formed therein configured to movably seat the head of the bone anchor such that the shank of the bone anchor can be positioned at a plurality of angles with respect to the receiver member;
wherein the head of the bone anchor includes an orientation indication feature that engages an orientation indication feature of the receiver member to provide feedback when the shank is positioned in a predetermined orientation with respect to the receiver member, and
wherein the predetermined orientation is one in which the bone anchor is positioned normal to an obliquely-angled distal-facing surface of the receiver member.

12. A bone anchor assembly, comprising:
a bone anchor having a proximal head and a distal shank, the proximal head including a planar surface and a spherical surface;
a receiver member having a polyaxial seat formed in a distal end thereof and configured to polyaxially seat the head of the bone anchor; and
a compression member disposed within the receiver member and having a distal end that engages the proximal head of the bone anchor, the distal end including a planar surface;
wherein the assembly is positionable in a first locked configuration in which the planar surface of the head and the planar surface of the compression member are parallel to and engaged with one another to lock an orientation of the shank relative to the receiver member; and
wherein the planar surface of the head comprises a proximal-facing surface of a groove formed in the head at a location distal to a proximal-most end of the bone anchor.

13. The assembly of claim 12 , wherein the assembly is positionable in a second locked configuration in which the planar surface of the head and the planar surface of the compression member are not parallel to one another and in which the compression member engages the head to lock an orientation of the shank relative to the receiver member.

14. The assembly of claim 12 , wherein the planar surface of the compression member comprises a distal-facing surface of an annular ridge formed on the compression member.

15. The assembly of claim 12 , wherein the assembly is biased towards the first locked configuration.

16. A surgical method, comprising:
advancing a distal shank of a bone anchor into a bone while a proximal head of the bone anchor is seated in a receiver member;
adjusting an angle of the receiver member with respect to the bone anchor until an orientation indication feature of the head engages an orientation indication feature of the receiver member to generate feedback indicative of a relative positioning between the bone anchor and the receiver member; and
determining a tr

Assignees

• Medos Int Sarl

Inventors

• Chandanson Thibault
• Spratt Frank
• Quintanilha Ernest
• Cormier Philip

Classifications

• A61B17/8605

  Heads, i.e. proximal ends projecting from bone · CPC title

• A61B17/7037 Primary

  wherein pivoting is blocked when the rod is clamped · CPC title

• A61B2017/00115

  with audible or visual output · CPC title

• A61B17/7032

  Screws or hooks with U-shaped head or back through which longitudinal rods pass · CPC title