Bone fixation plate

• US 20050234455A1
• Filed: 04/19/2004
• Published: 10/20/2005
• Est. Priority Date: 04/19/2004
• Status: Active Grant

• Current Assignee: Globus Medical, Inc.
• Original Assignee: Globus Medical, Inc.
• Inventors: Binder, Lawrence, Hansen, Matthew
• Granted Patent: US 7,963,981 B2
• Time in Patent Office: Days
• US Class Current: 606/294
• CPC Class Codes: A61B 17/1728 for holes for bone plates or plate screws
• CPC Class Codes: A61B 17/8033 having indirect contact with screw heads, or having contact with screw heads maintained with the aid of additional components, e.g. nuts, wedges or head covers
• CPC Class Codes: A61B 17/8038 the additional component being inserted in the screw head
• CPC Class Codes: A61B 17/8042 the additional component being a cover over the screw head
• 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 17/8052 immobilised relative to screws by interlocking form of the heads and plate holes, e.g. conical or threaded
• CPC Class Codes: A61B 17/844 with expandable anchors or anchors having movable parts
• CPC Class Codes: A61B 17/861 specially shaped for gripping driver
• CPC Class Codes: A61B 2017/8655 with special features for locking in the bone

Abstract

An apparatus for reducing the profile of a bone fixation plate while preventing backing out of screws is disclosed. The apparatus includes at least one section of relief and sections of engagement. The plate has at least two openings though which two screws can pass through bony tissue. As the screw is tightened, it will begin to lag the plate to the bone. When the screw head interferes with the plate at the interference point, there is a slight resistance that insertion forces can overcome. When the screw is advanced further, it snaps into the sliding fit area and is allowed to move freely. The forces that cause the screw to back out from the plate are preferably not strong enough to pass the screw head back past the interference section. It may be desirable to include a set screw to help prevent backout.

Claims

1. An apparatus for fixing a plate to bony material, comprising:

a plate having at least one opening having a spherical curvature extending at least partially through the thickness of the plate; and

at least one fastener having a head that interferes with the plate at an interference point;

wherein the head is capable of engaging with and passing the interference point to communicate with the spherical curvature.

2. The apparatus according to claim 1, wherein the interference point includes at least one engagement area and at least one relief area.

3. The apparatus according to claim 1, wherein tangents from the outer most portion of the spherical curvature of the plate intersect.

4. The apparatus according to claim 3, wherein the angle of intersection of the tangents is between about 1 and about 5 degrees.

5. The apparatus according to claim 3, wherein the angle of intersection of the tangents is between about 1 and about 3 degrees.

6. The apparatus according to claim 2, wherein the at least one relief area comprises less than about 40% of the interference point.

7. The apparatus according to claim 2, wherein the at least one relief area comprises less than about 30% of the interference point.

8. The apparatus according to claim 1, wherein the fastener head comprises a partially spherical outer surface corresponding approximately to the spherical surface of the plate opening, at least one slit located on the fastener head to permit outward expansion of the fastener head, and a locking screw capable of being received in a receptacle formed in the fastener head.

9. An apparatus for stabilizing at least two bony structures, comprising:

a plate wherein more than one aperture is configured and adapted to include an interference area integrally formed therein to prevent a fastener from backing out of the interference area.

10. The apparatus according to claim 9, further comprising a fastener having a head capable of engaging with and passing through the interference area.

11. The apparatus according to claim 9, wherein the interference area is included in a spherical curvature having at least one engagement area and at least one relief area.

12. The apparatus according to claim 11, wherein tangents to the spherical curvature intersect.

13. The apparatus according to claim 12, wherein the angle of intersection of the tangents is between about 1 and 5 degrees.

14. The apparatus according to claim 9, further comprising an opening selectively positioned to increase the magnitude of interference at the interference point.

15. The apparatus according to claim 14, wherein the opening is configured and adapted to pass a wedge shaped screw.

16. The apparatus according to claim 9, wherein the fastener has a fastener head comprising a partially spherical outer surface corresponding approximately to the spherical surface of the plate opening, at least one slit located on the fastener head to permit outward expansion of the fastener head, and a locking screw capable of being received in a receptacle formed in the fastener head.

17. An apparatus for fixing a plate to bony material, consisting essentially of:

a plate comprising at least one opening having a spherical curvature; and

at least one fastener having a head capable of engaging with and passing through an interference point of the spherical curvature;

wherein the fastener is prevented from backing out of the opening by the interference point.

18. The apparatus according to claim 17, further comprising another opening selectively positioned to increase the magnitude of interference at the interference point.

19. The apparatus according to claim 17, wherein tangents to the spherical curvature intersect.

20. The apparatus according to claim 17, wherein the fastener head comprises a partially spherical outer surface corresponding approximately to the spherical surface of the plate opening, at least one slit located on the fastener head to permit outward expansion of the fastener head, and a locking screw capable of being received in a receptacle formed in the fastener head.

21. A fastener for mounting an implant to bone comprising:

an elongate fastener body having a longitudinal axis, a proximal end, and a distal end;

a threaded portion disposed on the distal end of the fastener, wherein said threaded portion is capable of screwing into bone;

a fastener head portion disposed on the proximal end of the fastener, wherein the fastener head comprises;

a partially spherical outer surface;

in interior surface defining a receptacle for receiving a locking fastener; and

at least one slit extending between the outer surface and interior surface of the fastener head to permit outward expansion of the fastener head; and

a locking fastener capable of being received in the receptacle of the fastener head.

22. The fastener of claim 21, further comprising:

a plate having at least one aperture configured and adapted to include an interference area integrally formed therein to prevent the fastener from backing out of the interference area.

23. The fastener of claim 21, further comprising:

a plate having at least one opening having a spherical curvature extending at least partially through the thickness of the plate, wherein insertion of the fastener head interferes with the plate at an interference point, and wherein the fastener head is capable of engaging with and passing the interference point to communicate with the spherical curvature.

24. The fastener of claim 21, wherein the fastener head comprises two or more slits extending between the outer surface and interior surface of the fastener head to permit outward expansion of the fastener head.

25. The fastener of claim 24, wherein the fastener head comprises four or more slits extending between the outer surface and interior surface of the fastener head to permit outward expansion of the fastener head.