Snap fit rod and fastener system

Patent metadata

Field	Value
Publication number	US-9339305-B2
Application number	US-201113235949-A
Country	US
Kind code	B2
Filing date	Sep 19, 2011
Priority date	Sep 19, 2011
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

Implementations of the present disclosure provide a snap fit rod and fastener system including one or more fasteners for securing one or more rods to secure a spine or other anatomical structure. The fasteners include a fixation shaft, a clamp and a connector. The fixation shaft (for example a pedicle screw) is configured to frictionally engage a bone (vertebra) or other workpiece. The clamp has a pressure responsive portion that defines an opening configured to receive a rod. The connector is configured to connect the clamp to the fixation shaft and exert pressure on the clamp to modify the opening and secure the rod. A bias mechanism, such as a washer spring may be included to urge against the pressure responsive portion and which can be overcome by pressure on the rod for the “snap fit” effect. For additional adjustability, the clamp may be pivotally mounted on the fixation shaft.

First claim

That which is claimed:

1. A fastener for engaging a workpiece opening, the fastener comprising:
a fixation shaft configured to frictionally engage the workpiece opening the fixation shaft including an at least partially spherical head at a proximal end; and
a clamp including:
an upper body and a main body that define an opening that extends in a direction perpendicular to a longitudinal axis of the clamp, wherein the opening does not intersect the longitudinal axis of the clamp, the upper body including a sloped surface and the main body including a complementary sloped surface, the sloped surfaces defining a pressure-responsive portion such that the sloped surface of the upper body moves along the sloped surface of the main body and modifies a size of the opening in response to pressure;
an axial opening extending through the upper body and the main body along the longitudinal axis of the clamp for receiving at least a portion of a connector, the axial opening extending through at least a portion of the sloped surfaces of the upper and main bodies;
a collet having a skirt defining a semi-spherical opening and a shaft extending from the skirt and configured to extend into the axial opening, the collet configured to compress the spherical head within the semi-spherical opening for locking engagement;
the connector being secured to the shaft of the collet to connect the clamp to the fixation shaft and exert pressure on the pressure-responsive portion of the clamp to modify the opening;

wherein the clamp is configured to pivotally engage a proximal end of the fixation shaft, and further wherein the clamp is offset from a longitudinal axis of the fixation shaft.

2. A fastener of claim 1 , wherein the upper body includes an arc member and the main body includes an arc member and the arc members are configured to define the opening of the clamp.

3. A fastener of claim 2 , wherein the opening of the clamp is a cylindrical opening.

4. A fastener of claim 3 , wherein sloped surfaces result in both lateral and vertical movement of the upper body with respect to the main body upon exertion of pressure by the connector.

5. A fastener of claim 3 , wherein the arc member of the upper body is shorter than the arc member of the main body so as to define an upwardly directed slot accessing the opening of the clamp.

6. A fastener of claim 3 , wherein the arc member of the main body is shorter than the arc member of the main body so as to define a downwardly directed slot accessing the opening of the clamp.

7. A fastener of claim 4 , wherein the lateral movement shortens a distance between free ends of the arc members.

8. A fastener of claim 7 , further comprising a spring extending between the upper body and the connector.

9. A fastener of claim 8 , wherein the spring is configured to assume a fully deformed condition upon tightening of the connector.

10. A fastener of claim 8 , wherein the spring is deformed by external pressure urging the free ends of the arc members apart.

11. A fastener of claim 10 , wherein the free ends of the arc members define cam surfaces.

12. A fastener of claim 1 , wherein the connector is configured to connect to the shaft of the collet to compress the body of the clamp therebetween.

13. A fastener of claim 12 , wherein compression of the body deforms the skirt to lock onto the spherical head.

14. A fastener of claim 13 , wherein the connector includes a threaded nut configured to engage a plurality of threads on the shaft of the collet.

15. A fastener of claim 14 , wherein the shaft of the collet defines an axial opening and the threaded nut defines an axial opening configured to align with the axial opening of the shaft when engaged thereto.

16. A fastener of claim 14 , wherein the skirt is configured to allow at least plus or minus degrees of tilt of the clamp with respect to a plane orthogonal to an axis of the fixation shaft.

17. A fastener of claim 15 , wherein the skirt defines at least one radial relief cut configured to facilitate deformation of the skirt about the spherical head.

18. A fastener of claim 17 , further comprising a spring washer configured for placement between the threaded nut and the body of the clamp.

19. A fastener of claim 1 , wherein the pressure-responsive portion is configured to decrease the size of the opening in response to pressure applied thereto.

20. A fastener of claim 19 , wherein the clamp is configured for locking engagement with the proximal end of the fixation shaft in response to pressure applied by the connector.

21. A fastener of claim 1 , wherein relative movement of the upper body and main body is locked upon tightening of the connector.

Assignees

• Rathbun David
• Depuy Synthes Products Inc

Inventors

• Rathbun David

Classifications

• Y10T29/49863

  with prestressing of part · CPC title

• A61B17/7041 Primary

  with single longitudinal rod offset laterally from single row of screws or hooks (A61B17/7044 takes precedence) · CPC title

• A61B17/7037

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

• Y10T29/49826

  Assembling or joining · CPC title