Occipital plate and rod system

• US 20030153913A1
• Filed: 02/05/2003
• Published: 08/14/2003
• Est. Priority Date: 02/13/2002
• Status: Active Grant

• Current Assignee: Zimmer Biomet Spine, Inc. (Zimvie Incorporated)
• Original Assignee: EBI LP (Zimvie Incorporated)
• Inventors: Altarac, Moti, Mellinger, Philip A.
• Granted Patent: US 7,232,441 B2
• Time in Patent Office: Days
• US Class Current: 606/61
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7044 also having plates, staples or washers bearing on the vertebrae
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull

Abstract

The present invention has a plate and rod assembly for implantation in the cervical region of the spine which includes an occipital plate having an angled anchor bridging area that is attached to the lower posterior curve of the skull. On either side the bridging area is connected to offset legs which join flanged areas that include tethered rod anchors having rod-receiving channels. Specifically, the flanged areas have a high friction surface, which is preferably knurled, to bite into the surface of the rod that is received in the channels. These flanges include undercut slots that capture the side plates integral to the open U-shaped members including the rod-receiving channels. The side plates extend longer in the direction of the longitudinal axis of the rod when it is in the channel. These side plates can thus be lowered into the slot and rotated by 90 degrees to capture the channels in the flanges since the undercut slots are not as wide as they are long. The channels are closed by a capnut which has a bottom annular flange that also helps to lock the rod in place. The angle of the rod-receiving flanges relative to the plate bridging area allows the rods to be positioned close to the cervical vertebrae so that they can also be attached to the cervical vertebrae using vertebral anchors. The capnut is self-aligning as it includes an internal projection that cooperates with the internal recess of the rod-receiving channel members in the direction of the longitudinal axis of the attachment screw. Further, the capnut includes a visual alignment cue that helps to inhibit cross threading by indicating the proper side for starting the capnut on the threads of the channel. Three debossed dots show the alignment relative to a similarly placed set of dots on the proper side of the rod-receiving channel.

Claims

1. A spinal rod assembly comprising a rod and an attachment plate having at least one tethered rod anchor having a rod-receiving channel.

2. A spinal rod assembly as set forth in claim 1 wherein the rod anchor is a U-shaped member having two upright legs and having an outwardly extending side plate, the attachment plate including a recess that retains the side plate of the rod-receiving channel.

3. A spinal rod assembly as set forth in claim 2 wherein the recess is formed in a flange of the attachment plate that has an upper surface that is a high friction surface.

4. A spinal implant assembly as set forth in claim 3 wherein the high friction surface includes points.

5. A spinal implant assembly as set forth in claim 4 wherein the high friction surface is knurled.

6. A spinal implant assembly as set forth in claim 1 wherein the attachment plate includes a bridge area having screw holes and two flanges each of which receive an rod anchor member, and wherein the flanges independently define their own planes neither of which are in the same plane as the bridge area.

7. A spinal rod assembly including a rod, a rod anchor and a plate for attachment to an occipital portion of a skull wherein the anchor has a U-shaped member with a central vertical axis and which defines a channel for the rod and has a member extending in one direction transverse to the central vertical axis, the plate including a slot which surrounds the rod anchor wherein the anchor has a dimension smaller than the slot in one dimension but the extension has a dimension larger than the slot so that the anchor can be inserted into the plate from the top and rotated to capture the anchor in the slot by means of the extension.

8. A spinal rod assembly as set forth in claim 7 wherein the extension is a side plate.

9. A spinal rod assembly as set forth in claim 8 wherein the rod anchor includes two opposing side plates.

10. A spinal rod assembly as set forth in claim 9 wherein the rod anchor includes threads and a compression member that holds the rod in place in the rod-receiving channel.

11. A spinal rod assembly as set forth in claim 9 wherein the threads are external threads and the compression member is a cap or a nut or a capnut.

12. A spinal rod assembly as set forth in claim 10 wherein the slot includes two recesses which are defined by undercut areas along the sides of the slot.

13. A spinal rod assembly as set forth in claim 11 wherein the rod anchor has a bottom surface which includes a boss that helps to limit the movement of the rod anchor relative to the slot.

14. A spinal rod assembly as set forth in claim 13 wherein the plate has a flange which includes the slot and a bridging area with through bores for attachment to the skull, and wherein the bridging area is upward on the skull relative to the flange.

15. A spinal implant assembly comprising a rod, and at least one bone anchor having a rod-receiving channel which has two threaded upright legs, and a threaded locking member that cooperates with the threads on the legs to hold the rod in the channel, and wherein the locking member and the channel each have a visual indication for the proper starting alignment of the locking member.

16. A spinal implant as set forth in claim 15 wherein the channel includes external threads and the locking member includes internal threads.

17. A spinal implant assembly as set forth in claim 16 wherein the visual indication comprises a debossed dot.

18. A spinal implant assembly as set forth in claim 17 wherein the visual indication comprises a series of dots.