Polyaxial bone anchors with pop-on shank, fully constrained friction fit retainer and lock and release insert

Patent metadata

Field	Value
Publication number	US-8998959-B2
Application number	US-201113317387-A
Country	US
Kind code	B2
Filing date	Oct 19, 2011
Priority date	Jun 15, 2009
Publication date	Apr 7, 2015
Grant date	Apr 7, 2015

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. The receiver can have crimp tabs, but is devoid of spring tabs and collet-like flexible structures. A down-loadable compression insert (some with lock and release feature), a down-loadable friction fit split retaining ring having super structure for temporary friction fit with an up-loadable 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.

First claim

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

1. In a polyaxial bone anchor, the improvement comprising:
a) a receiver defining a chamber communicating with a channel, the channel sized and shaped for receiving a portion of a longitudinal connecting member, the chamber communicating with a lower opening and further comprising an aperture defined by a first inner surface;
b) a shank having a body and an upper curved portion having a hemisphere, the shank body extending through the receiver lower opening; and
c) a resilient open retainer located in the chamber, the retainer having a base and an upper structure, the base expandable in the chamber about the shank upper portion and receiving the shank upper portion therethrough to capture the upper portion in the chamber, the retainer upper structure having a top surface that is located on the top of the retainer and being disposed in the aperture in the chamber of the receiver and the retainer base being fixed against a cylindrical portion of the chamber of the receiver when the shank is in a locked position with respect to the receiver, the shank upper portion being pressed against the retainer base and being in spaced relation with the receiver when in the locked position.

2. The improvement of claim 1 further comprising:
an insert in engagement with the shank upper portion and located between the shank upper portion and the portion of the longitudinal connecting member located in the receiver channel.

3. The improvement of claim 2 wherein the insert has an outer surface releasably frictionally locked against the receiver.

4. The improvement of claim 2 wherein the receiver channel is a first channel and the insert has a second channel, the insert being top loaded into the receiver and then rotated into a position above the retainer with the second channel aligned with the first channel.

5. The improvement of claim 4 wherein the receiver has a crimped wall surface pressed into the insert.

6. The improvement of claim 1 wherein the retainer base has a first planar surface seated on a second planar surface partially defining the receiver chamber.

7. The improvement of claim 1 wherein the retainer base has a first outer non-tapered surface in engagement with a second surface partially defining the receiver chamber.

8. The improvement of claim 1 wherein the retainer upper structure comprises a plurality of resilient inwardly facing panels in temporary frictional engagement with the shank upper portion.

9. The improvement of claim 8 wherein the panel surfaces are concave.

10. The improvement of claim 1 wherein the retainer upper structure comprises a pair of opposed outwardly extending resilient tabs comprising the top surface, the tabs in temporary frictional engagement with the receiver when the shank upper portion is received through the retainer base with the tabs being in a compressed state and holding the retainer in an upper portion of the receiver chamber during assembly with the shank upper portion.

11. The improvement of claim 10 wherein the retainer base has a first planar surface and the receiver has a second aperature opposed to the aperature and a second planar surface partially defining the receiver chamber and wherein after the shank upper portion is received through the retainer base, the retainer base first planar surface is seated on the receiver second surface and the resilient tabs expand to a neutral state and are captured within the receiver apertures.

12. The improvement of claim 10 , wherein the tabs being in frictional engagement with a bottom portion of the insert.

13. In a polyaxial bone anchor, the improvement comprising:
a) a receiver defining a chamber communicating with a channel, the channel sized and shaped for receiving a portion of a longitudinal connecting member, the chamber having an inner surface further comprising an aperture defined by a first surface formed therein and a second seating surface located near a bottom opening of the receiver, the chamber communicating with the bottom opening;
b) a shank having a body and a curved upper portion, the shank body extending through the receiver bottom opening; and
c) a resilient open retainer located in the chamber, the retainer having a base and an upper structure having a resilient outwardly extending tab having a top surface that is located on the top of the retainer, the retainer having two positions, a shank loading position and a shank restraining position, while in the shank loading position, the base being expandable in the chamber about the shank upper portion and receiving the shank upper portion therethrough to capture the shank upper portion in the chamber, the tab engaging the first surface of the aperture, and in the shank restraining position, the shank and retainer in combination are lowered in the chamber such that the retainer base is seated on the receiver second seating surface, and the tab expands outwardly through the aperture with the retainer being restrained by the first surface with respect to upward, downward, and rotational movement with respect to the receiver by the tab, the shank being able to be manipulated in a polyaxial direction with respect to the receiver when the retainer is in either the shank loading or shank restraining positions.

14. The improvement of claim 13 wherein the aperture in the receiver first surface is a pair of opposed apertures and the retainer tab is a pair of opposed resilient tabs, each one of the tabs being received in one of the apertures.

15. The improvement of claim 13 wherein the retainer upper structure further comprises a plurality of inwardly facing panels, the panels being in temporary frictional engagement with the shank upper portion prior to locking of the shank in a final position with respect to the receiver.

16. The improvement of claim 13 further comprising an insert located partially in the chamber, the insert having a surface frictionally engaging the shank upper portion when the retainer and the shank are in a locked engagement.

17. The improvement of claim 16 wherein the insert has a lock and release feature in engagement with the receiver.

18. The improvement of claim 16 wherein the insert having a surface frictionally engaging the retainer upper structure so as to lock a position of the shank with respect to the receiver.

19. A medical implant comprising:
a) a receiver having a base with an inner cavity and a pair of upstanding opposed arms partially defining a longitudinal connecting member receiving channel, the inner cavity defined in part by a cylindrical lower seating portion and an upper expansion chamber, the upper expansion chamber comprising an aperture defined by a first inner surface, the lower seating portion communicating with a bottom opening of the receiver base and the upper expansion chamber communicating with the rod receiving channel;
b) a bone screw shank having an upper portion sized for up-loading through the receiver bottom opening;
c) an open, resilient retaining member having a base and an upper structure, the base sized and shaped for expanding about the shank upper portion when the retaining member base is located in the receiver upper expansion chamber, the retainer upper structure having a top surface that is located on the top of the retainer and being disposed in the aperture in the chamber of the receiver and the retaining member base engaging the cylindrical receiver lower seating portion when the shank is in a locked position with respect to the receiver; and
d

Assignees

• Jackson Roger P
• Surber James L

Inventors

• Jackson Roger P
• Surber James L

Classifications

• A61B17/7032

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

• A61B17/7037 Primary

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