pivotal anchor with snap-in-place insert having rotation blocking extensions

Patent metadata

Field	Value
Publication number	US-9980753-B2
Application number	US-201113374439-A
Country	US
Kind code	B2
Filing date	Dec 29, 2011
Priority date	Jun 15, 2009
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A friction fit compression insert (some with lock and release feature), a planar split retaining ring and a shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled and the receiver and insert may include aligned tool receiving apertures for lock and release of the polyaxial mechanism.

First claim

What is claimed and desired to be secured by Letters Patent is as follows:

1. A bone anchor assembly for securing a longitudinal connecting member to a bone, the bone anchor assembly comprising:
a receiver having a through bore around a central vertical axis, the receiver including a lower body with a bottom opening and an internal cavity communicating with an upper portion having a pair of opposed arms defining a first channel therebetween opening onto a top thereof, the first channel having opposed inner surfaces and a transverse axis perpendicular to the central vertical axis, the first channel sized and shaped for receiving a portion of the longitudinal connecting member, the arms having a discontinuous helically wound guide and advancement structure thereon, and the receiver including interior opposed recesses having downwardly-facing top surfaces located entirely below the helically wound guide and advancement structure;
a bone attachment structure having a body and an upper head portion having a substantially spherical surface above a hemisphere thereof, the body extending through the receiver bottom opening and pivotal with respect to the receiver; and
an insert having a body with upright arms forming a second channel therebetween, the second channel being alienable with the receiver transverse axis to receive the portion of the longitudinal connecting member, the upright arms having uppermost top surfaces, the insert body further including a central through-and-through tool receiving opening and oppositely-directed opposed radial extending portions with outer surfaces in the direction of the receiver transverse axis engageable with the receiver first channel inner surfaces to inhibit rotation between the receiver and the insert, the opposed radial extending portions having top surfaces that extend radially outward and underneath a most bottom surface of the portion of the longitudinal connecting member positioned within the receiver first channel,
wherein when the uppermost top surfaces of the upright arms of the insert are snapped under and engaging the downwardly-facing top surfaces of the receiver opposed recesses, the bone attachment structure has a non-floppy relationship with respect to the receiver, and the insert is prevented from moving back up within the receiver prior to the longitudinal connecting member being positioned within the receiver and the insert first and second channels and locked by a closure structure.

2. The bone anchor assembly of claim 1 , wherein the insert upright arms further include upper portions projecting radially outward near the uppermost top surfaces thereof, with the top surfaces of the radially-projecting upper portions defining the uppermost top surfaces of the insert.

3. The bone anchor assembly of claim 1 , wherein the bone attachment structure upper head portion is held in the receiver cavity by a separate retainer.

4. The bone anchor assembly of claim 1 , wherein the insert body is above the bone attachment structure upper head portion so as to cooperate in providing a friction fit between the bone attachment structure and the receiver.

5. The bone anchor assembly of claim 1 , wherein the bone attachment structure is positioned within the receiver prior to the insert uppermost top surfaces being snapped under the downwardly-facing top surfaces of the receiver opposed recesses.

6. The bone anchor assembly of claim 3 , wherein the retainer is non-pivoting with respect to the receiver.

7. The bone anchor assembly of claim 1 , wherein the insert further includes a lower extending portion in the direction of the bone attachment structure upper head portion so as to provide a friction fit with respect to the bone attachment structure and the receiver.

8. The bone anchor assembly of claim 1 , wherein the closure structure has a corresponding continuous helically wound structure engageable with the discontinuous helically wound guide and advancement structure.

9. The bone anchor assembly of claim 8 , wherein the closure structure is configured to abut the longitudinal connecting member positioned in the receiver first channel.

10. The bone anchor assembly of claim 8 , wherein the closure structure corresponding continuous helically wound structure is threadably engagable with the discontinuous helically wound guide and advancement structure, thereby advancing the closure structure into the receiver first channel upon rotation of the closure structure relative to the receiver.

11. The bone anchor assembly of claim 8 , wherein the closure structure remains spaced apart from the insert when the bone anchor assembly is in a locked configuration.

12. The bone anchor assembly of claim 1 , wherein the receiver discontinuous helically wound guide and advancement structure inhibits the receiver arms from splaying open at the top thereof.

13. The bone anchor assembly of claim 1 , wherein a width of the insert second channel at the level of the uppermost top surfaces of the insert upright arms, as measured perpendicular to both the transverse axis and the central vertical axis, is greater than a diameter of the longitudinal connecting member.

14. The bone anchor assembly of claim 1 , wherein a length of the insert second channel between outer ends of the opposed radial extending portions, as measured along the transverse axis, is greater than the greatest width between inner surfaces of the insert upright arms forming the second channel therebetween, as measured perpendicular to both the transverse axis and the central vertical axis.

15. The bone anchor assembly of claim 1 , wherein the insert uppermost top surfaces do not extend above a top of the longitudinal connecting member positioned within the receiver first channel and the insert second channel when the bone anchor assembly is in a locked configuration.

16. The bone anchor assembly of claim 1 ,
wherein the insert body and upright arms together form a saddle surface that defines a lower limit of the insert second channel, and
wherein top surfaces of the opposed radial extending portions extend the saddle surface in the direction of the transverse axis so as to be underneath the portion of the longitudinal connecting member positioned within the insert second channel.

17. The bone anchor assembly of claim 1 , wherein the insert has a non-snap-fit engagement with the portion of the longitudinal connecting member positioned within the insert second channel.

18. The bone anchor assembly of claim 1 , wherein bottom surfaces of the insert opposed radial extending portions overlie a receiver channel surface defined by an upper edge of the receiver body extending between the receiver arms.

19. The bone anchor assembly of claim 1 , wherein the insert upright arms are snapped into the receiver opposed recesses after the bone attachment structure upper head portion is disposed within the receiver internal cavity.

20. The bone anchor assembly of claim 1 , wherein the insert upright arms further include upper portions that flair radially outward and vertically upward, with the top surfaces of the upper portions defining the uppermost top surfaces of the insert.

21. The bone anchor assembly of claim 1 , wherein the insert opposed radial extending portions top surfaces are opposite a lower most bottom facing surface of the portion of the longitudinal connecting member positioned within the receiver first channel.

22. The bone anchor assembly of claim 1 , wherein the insert upright arms have exterior surfaces wit

Assignees

• Jackson Roger P
• Surber James L

Inventors

• Jackson Roger P
• Surber James L

Classifications

• A61B17/7032 Primary

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

• A61B17/7076

  for driving, positioning or assembling spinal clamps or bone anchors specially adapted for spinal fixation · CPC title

• A61B17/7008

  with parts of, or attached to, the longitudinal elements, bearing against an outside of the screw or hook heads, e.g. nuts on threaded rods (A61B17/7007 takes precedence) · CPC title

• A61B17/7037

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