POLYAXIAL FACET FIXATION SCREW SYSTEM WITH FIXATION AUGMENTATION

• US 20110313472A1
• Filed: 06/22/2011
• Published: 12/22/2011
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: Wenzel Spine, Inc.
• Original Assignee: Osteomed L.P. (Berkshire Hathaway Incorporated)
• Inventors: Yap, Marc, Fauth, Andrew R., Helgerson, Joel R., Dickerman, Rob D., Bennett, Matthew T., Forton, Charles R., Marigowda, Shresta
• Granted Patent: US 8,998,966 B2
• Time in Patent Office: Days
• US Class Current: 606/305
• CPC Class Codes: A61B 17/686 Plugs, i.e. elements forming interface between bone hole and implant or fastener, e.g. screw
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/8047 wherein the additional element surrounds the screw head in the plate hole A61B17/8052 takes precedence
• CPC Class Codes: A61B 17/8625 Shanks, i.e. parts contacting bone tissue
• CPC Class Codes: A61B 17/8685 comprising multiple separate parts
• CPC Class Codes: A61B 17/8695 Washers surrounding screw head in plate hole A61B17/8047, between bone plate and bone A61B17/8028
• CPC Class Codes: A61B 2017/8655 with special features for locking in the bone

Abstract

A screw system includes a screw and a washer assembly captive to the screw. The washer assembly is polyaxially pivotable relative to the screw. The screw may be freely rotated in one direction relative to the washer assembly, but frictionally binds with the washer assembly when rotated in a second direction. Various auxiliary fixation features are disclosed.

Claims

1. A system, comprising:

a screw, wherein the screw comprises a spherical head and a shaft extending from the head, wherein the shaft comprises a threaded portion and an auxiliary fixation feature, wherein the threaded portion extends along a distal portion of the shaft,

wherein the system has an insertion configuration and a deployed configuration, wherein the auxiliary fixation feature is substantially contained within the shaft in the insertion configuration, wherein at least a portion of the auxiliary fixation feature protrudes beyond the shaft in the deployed configuration, wherein the system is transformable between the insertion configuration and the deployed configuration; and

a washer around the head, wherein the washer comprises a socket, wherein the socket receives the head to form a ball-and-socket joint, wherein the screw is freely rotatable relative to the washer when the head rotates in a first direction, wherein the screw and washer assembly become locked together when the head rotates in a second direction, wherein the second direction is opposite the first direction.

2. The system of claim 1, wherein the auxiliary fixation feature is in the proximal, non-threaded portion of the shaft.

3. The system of claim 1, wherein the auxiliary fixation feature comprises a cylindrical center portion and at least one fin, wherein the cylindrical center portion comprises a longitudinal, central axis, wherein the fin extends outwardly from the central axis.

4. The system of claim 3, wherein the fin can protrude beyond the shaft when the fin is aligned with an aperture in the shaft.

5. The system of claim 3, wherein the fin is hinged to the cylindrical center portion.

6. The system of claim 3, wherein the fin is formed separately from the screw.

7. The system of claim 1, wherein the auxiliary fixation feature is spring-biased to protrude beyond the shaft in the deployed configuration, wherein the bias is temporarily overcome in the insertion configuration so that the auxiliary fixation feature is substantially contained within the shaft.

8. A system, comprising:

a fixation element, wherein the fixation element comprises a screw and a washer, wherein the screw comprises a spherical head and a shaft extending from the head, wherein the shaft comprises a distal threaded portion,

wherein the washer comprises a socket, wherein the socket receives the head to form a ball-and-socket joint, wherein the screw is freely rotatable relative to the washer when the head rotates in a first direction, wherein the screw and washer assembly become locked together when the head rotates in a second direction, wherein the second direction is opposite the first direction; and

an auxiliary fixation element, wherein the auxiliary fixation element is substantially contained within the fixation element, wherein when an axial actuation force is applied, the auxiliary fixation element becomes actuated so that it protrudes from the fixation element.

9. The system of claim 8, wherein the auxiliary fixation feature is in the proximal, non-threaded portion of the shaft.

10. The system of claim 8, wherein the auxiliary fixation feature comprises a cylindrical center portion and at least one fin, wherein the cylindrical center portion comprises a longitudinal, central axis, wherein the fin extends outwardly from the central axis.

11. The system of claim 10, wherein the fin can protrude beyond the shaft when the fin is aligned with an aperture in the shaft.

12. The system of claim 10, wherein the fin is integrally formed with the cylindrical center portion.

13. The system of claim 10, wherein the fin is integrally formed with the screw.

14. The system of claim 8, wherein the auxiliary fixation feature is spring-biased to protrude beyond the shaft in the deployed configuration, wherein the bias is temporarily overcome in the insertion configuration so that the auxiliary fixation feature is substantially contained within the shaft.

15. A bone fastener, comprising:

a fixation element, wherein the fixation element comprises a screw and a washer, wherein the screw comprises spherical head and a shaft extending from the head, wherein the shaft comprises a distal threaded portion, wherein the washer comprises a socket, wherein the socket receives the head to form a ball-and-socket joint, wherein the screw is freely rotatable relative to the washer when the head rotates in a first direction, wherein the screw and washer assembly become locked together when the head rotates in a second direction, wherein the second direction is opposite the first direction; and

an auxiliary fixation element, wherein the auxiliary fixation element provides no resistance to insertion of the fastener, wherein the auxiliary fixation element is actuatable after insertion so that the auxiliary fixation element provides resistance to removal of the fastener.

16. The system of claim 15, wherein the auxiliary fixation feature is substantially contained within the shaft during insertion of the fastener, wherein at least a portion of the auxiliary fixation feature protrudes beyond the shaft after insertion of the fastener.

17. The system of claim 15, wherein the auxiliary fixation feature is in the proximal, non-threaded portion of the shaft.

18. The system of claim 15, wherein the auxiliary fixation feature comprises a cylindrical center portion and at least one fin, wherein the cylindrical center portion comprises a longitudinal, central axis, wherein the fin extends outwardly from the central axis.

19. The system of claim 18, wherein the fin can protrude beyond the shaft when the fin is aligned with an aperture in the shaft.

20. The system of claim 18, wherein the fin is formed separately from the cylindrical center portion.