Orthopaedic rod/plate locking mechanisms and surgical methods

• US 20020049446A1
• Filed: 04/17/2001
• Published: 04/25/2002
• Est. Priority Date: 08/08/2000
• Status: Active Grant

• Current Assignee: Depuy Acromed Incorporated (Johnson & Johnson)
• Original Assignee: Depuy Acromed Incorporated (Johnson & Johnson)
• Inventors: Doherty, Thomas V., Selvitelli, David M., Harkey, Haynes Louis III, Reynolds, Martin A., Currier, Bradford
• Granted Patent: US 6,547,790 B2
• Time in Patent Office: Days
• US Class Current: 606/70
• CPC Class Codes: A61B 17/7044 also having plates, staples or washers bearing on the vertebrae
• CPC Class Codes: A61B 17/7053 with parts attached to bones or to each other by flexible wires, straps, sutures or cables
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull

Abstract

An orthopaedic method and anchor assemblies for anchoring a linkage such as a rod or cable used for fixation or reduction. One assembly includes an anchor plate and a slotted anchor bolt that captures the plate in a one-piece assembly for convenient installation. The base of the anchor bolt lies below the plate, and a cap or nut tightens down to secure a linking member, e.g., a rod or cable, in the slot, simultaneously clamping the bolt to fix both its position and its orientation on the plate. One occipital plate has lateral arms that hold the anchor bolts, and a Y-shaped embodiment is mounted in an inverted orientation to position the anchor bolts well down in soft tissue for more effective wound closure. A cable connector is used together with an anchor plate, vertebra anchor screws and fixation rods to secure ends of a cable at the level of one or more vertebrae, providing a versatile and highly stable system for alignment, fixation and fusing of the cervical and thoracic spine. The cable connectors have an open-sided channel that fits onto and securely clamps to an already-positioned fixation rod, with an eyelet or other structure providing a rigid and fixed securing point for a cable that is threaded about the vertebrae under tension. Methods of fixation are described.

Claims

1. An anchor assembly for spinal fixation, comprising

an anchor plate configured to anchor centrally on a skull below the external occipital protuberance and having first and second arms extending to sides thereof, and

at least one bolt having a slot configured to capture and clamp a fixation member,

the bolt being affixed to an arm forming a unitary and non-separating assembly with said anchor plate for one piece installation, the bolt being freely rotatable before clamping for positioning to receive the fixation member.

2. The anchor assembly according to claim 1, wherein the anchor plate is a Y-shaped plate comprising a central trunk portion and a pair of angled arm portions, wherein the bolt is affixed to one of said arms.

3. The anchor assembly according to claim 2, wherein a bolt is affixed to each arm.

4. The anchor assembly according to claim 1, wherein the plate has an elongated aperture through which the bolt fits from one side and extends through the other side, the bolt being adjustably positionable along the length of the elongated aperture before clamping.

5. The anchor assembly according to claim 4, wherein the aperture is elongated along a longitudinal axis of said arm.

6. The anchor assembly according to claim 1, wherein the bolt is affixed to the anchor plate by a support platform configured to fit about the bolt and having a support surface alignable with the slot of the bolt, the bolt and support platform together capturing the plate therebetween to form a unitary assembly with the bolt being movable in said plate to define an angular orientation of the slot.

7. The anchor assembly of claim 6, wherein said support platform includes a sleeve portion that fits into an aperture in the plate.

8. The anchor assembly of claim 6, wherein the bolt has a base with an upper surface and at least one of said upper surface and a lower surface of the support platform is textured for preventing movement against the plate when the bolt is under tension.

10. The anchor assembly of claim 2, wherein the plate has a stepped slot along which the bolt slides to a position aligned for receiving a fixation rod.

11. The anchor assembly of claim 6, wherein said support platform is a split washer having a seating surface for supporting the fixation member, and a catch or detent for capturing the bolt.

13. The spinal fixation system of claim 12, wherein the occipital plate is a T-plate.

14. The spinal fixation system of claim 12, wherein the occipital plate is a Y-plate.

15. The spinal fixation system of claim 14, wherein the Y-plate is configured to mount in an inverted Y orientation.

9. The anchor assembly of 7, wherein said support platform sleeve portion extends partially through said plate.

12. A spinal fixation system comprising

a first anchor element in the form of an occipital plate having at least one anchor screw hole disposed therein and at least one bolt-receiving aperture disposed therein;

at least one anchor bolt adapted to seat in the bolt-receiving aperture of the first anchor element, the anchor bolt having a slot extending transversely through a portion thereof;

a linking member having a proximal end portion clamped in said slot and having a distal end anchored to a vertebra; and

at least one cable connector fastened to the linking member at a selected position between said proximal and said distal end portions,

said cable connector including an eyelet defining a connection point to secure a spinal fixation cable at said selected position.

16. A cable connector, said cable connector comprising

a body having a generally elongated channel extending therethrough sized to receive a fixation rod therein, said channel being open sided such that the body may be placed from a side onto a fixation rod at a selected position while the rod is at least partly anchored in position;

the body further having an eyelet portion adapted to receive a cable; and

a clamping screw fitted in said body adjacent said channel such that the clamping screw locks the fixation rod, securely fixing position of the cable connector on the rod

whereby the eyelet secures the cable at said selected position.