Spinal fixation system

Patent metadata

Field	Value
Publication number	US-11612417-B2
Application number	US-201916686703-A
Country	US
Kind code	B2
Filing date	Nov 18, 2019
Priority date	Aug 20, 2010
Publication date	Mar 28, 2023
Grant date	Mar 28, 2023

Abstract

A polyaxial pedicle screw includes a housing, a bone screw member, and an anvil. The bone screw member includes a head and a threaded shaft extending from the head. The head is selectively securable within the housing. The anvil is positionable within the housing adjacent to the head of the bone screw member when the anvil and the head of the bone screw member are positioned within the housing. The anvil may define one or more grooves in an outer surface of the anvil. The groove defines a flap that is flexibly attached to the anvil to enable the anvil to flex an amount sufficient to maintain the head of the bone screw in constant contact with the anvil when the bone screw member is moved relative to the anvil. A rod reducer may be secured to the polyaxial pedicle screw to secure a spinal rod within the housing.

First claim

The invention claimed is:

1. A polyaxial pedicle screw comprising:
a bone screw member having a head and a threaded shaft extending from the head along a shaft axis; and
a housing positionable on the head of the bone screw member, the housing extending along a longitudinal axis between a proximal portion and a distal portion, the proximal portion having a channel adapted to receive a spinal rod therein in an orientation transverse to the longitudinal axis, and the distal portion defining a distal opening,
wherein the head of the bone screw member is shaped such that the head defines a first outer profile along a plane perpendicular to the longitudinal axis when the bone screw member is in a first orientation, in which the shaft axis defines a first angle with respect to the longitudinal axis, and wherein the head of the bone screw member defines a second outer profile along the plane perpendicular to the longitudinal axis when the bone screw member is in a second orientation, in which the shaft axis defines a second angle with respect to the longitudinal axis, the second angle being different from the first angle, wherein the first outer profile is shaped to be receivable through the distal opening of the housing when the bone screw member is in the first orientation, and wherein the second outer profile is shaped to prevent the head from passing through the distal opening when the bone screw member is in the second orientation.

2. The polyaxial pedicle screw of claim 1 , wherein the distal opening of the housing and the first outer profile of the head of the bone screw member have circular shapes, with a diameter of the first outer profile being smaller than a diameter of the distal opening.

3. The polyaxial pedicle screw of claim 1 , wherein the distal opening of the housing and the first outer profile of the head of the bone screw member have circular shapes, with a diameter of the second outer profile being larger than a diameter of the distal opening.

4. The polyaxial pedicle screw of claim 1 , wherein the first angle of the first orientation of the bone screw member is substantially 90°, and wherein the second angle of the second orientation of the bone screw member is substantially 180°.

5. The polyaxial pedicle screw of claim 1 , wherein the head of the bone screw member has a substantially spherical shape with a cylindrical portion formed therein, such that the first outer profile is defined by the cylindrical portion.

6. The polyaxial pedicle screw of claim 1 , wherein the housing includes a recess positioned to receive a portion of the threaded shaft of the bone screw member when the first outer profile of the head of the bone screw member is received through the distal opening of the housing in the first orientation.

7. The polyaxial pedicle screw of claim 6 , wherein the housing includes a collar extending from the distal portion of the housing, the collar defining the recess therein, and wherein the portion of the threaded shaft of the bone screw member receivable in the recess is a neck of the threaded shaft disposed between the head and a threaded portion of the threaded shaft.

8. The polyaxial pedicle screw of claim 6 , further comprising a cap securable to the housing so as to cover the recess.

9. The polyaxial pedicle screw of claim 1 , further comprising an anvil positionable within the housing adjacent to the head of the bone screw member when the anvil and the head of the bone screw member are positioned within the housing, the anvil defining a groove in an outer surface thereof, the groove defining a flap, the flap extending over the groove and being flexibly attached to the anvil to enable the anvil to flex an amount sufficient to maintain the head of the bone screw member in constant contact with the anvil.

10. The polyaxial pedicle screw of claim 9 , wherein the anvil defines a cavity having a surface with a plurality of radii of curvature to accommodate variously sized rod members.

11. The polyaxial pedicle screw of claim 10 , wherein the surface of the cavity defines a first section with a first radius of curvature, a second section with a second radius of curvature, and a third section with a third radius of curvature, such that the plurality of radii of curvature define a compound curve that provides at least two lines of contact on a plurality of different diameter rod members.

12. The polyaxial pedicle screw of claim 9 , wherein, when the anvil is positioned within the housing, the outer surface of the anvil defines a non-circular shape in a cross sectional plane extending orthogonal to the longitudinal axis of the housing, so as to prevent the anvil from rotating with respect to the housing about the longitudinal axis.

13. The polyaxial pedicle screw of claim 12 , wherein the non-circular shape is defined by a protuberance on the outer surface of the anvil, and wherein the housing defines a slot on an inner surface thereof, the protuberance and the slot being engageable to prevent the anvil from rotating with respect to the housing about the longitudinal axis.

14. The polyaxial pedicle screw of claim 1 , further comprising a cap securable to the housing to prevent the bone screw member from reorienting to the first orientation.

15. The polyaxial pedicle screw of claim 1 , wherein the first outer profile of the head of the bone screw member is defined by a portion of the head having a roughened surface texture, and wherein the second outer profile of the head of the bone screw member is defined by a portion of the head having a smooth surface.

16. A polyaxial pedicle screw comprising:
a bone screw member having a head and a threaded shaft extending from the head along a shaft axis, the head including a first outer surface region having a partially spherical shape defined by a first radius of curvature, and the head including a second outer surface region having a partially cylindrical shape defined by a second radius of curvature from a center of curvature defined along an axis of the partially cylindrical shape, the axis of the partially cylindrical shape extending transverse to the shaft axis, and the second radius of curvature being smaller than the first radius of curvature; and
a housing extending along a longitudinal axis between a proximal portion and a distal portion, the proximal portion having a channel adapted to receive a spinal rod therein in an orientation transverse to the longitudinal axis, and the distal portion defining a distal opening configured to receive the head of the bone screw member therethrough.

17. The polyaxial pedicle screw of claim 16 , wherein the distal opening of the housing has a circular shape defined by a radius that is larger than the second radius of curvature and smaller than the first radius of curvature.

18. The polyaxial pedicle screw of claim 16 , wherein the first outer surface region of the head of the bone screw member has a roughened surface texture, and wherein the second outer surface region of the head of the bone screw member has a smooth surface.

Assignees

• K2M Inc

Inventors

• Jones Scott A
• Boachie-Adjei Oheneba
• Mcclintock Larry E
• Strauss Kevin
• Carbone John

Classifications

• A61B17/7037 Primary

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

• A61B17/8625

  Shanks, i.e. parts contacting bone tissue · CPC title

• A61B2017/0046

  with a releasable handle; with handle and operating part separable · CPC title

• A61B17/7086

  Rod reducers, i.e. devices providing a mechanical advantage to allow a user to force a rod into or onto an anchor head other than by means of a rod-to-bone anchor locking element; rod removers · CPC title