Artificial disk

• US 5,246,458 A
• Filed: 10/07/1992
• Issued: 09/21/1993
• Est. Priority Date: 10/07/1992
• Status: Expired due to Term

• Current Assignee: Donald V. Graham
• Original Assignee: Donald V. Graham
• Inventors: Graham, Donald V.
• Primary Examiner(s): ISABELLA, DAVID J
• Application Number:
  US07/957,144
• Time in Patent Office: 349 Days
• Field of Search: 623/16, 623/17, 623/18, 606/60, 606/61, 606/69, 606/70, 606/71, 606/72, 606/79, 606/80, 606/86, 606/87, 606/96
• US Class Current: 623/17.14
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30329 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30649 Ball-and-socket joints
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: Y10S 606/907 Composed of particular material or coated
• CPC Class Codes: Y10S 606/91 Polymer

Abstract

An artificial intervertebral disk for replacing a damaged human disk between two adjacent vertebrae in a human spinal column is disclosed. The invention comprises a pair of cylindrically shaped members in a vertical stacked relationship and a flexible spacer therebetween. The cylindrically shaped members are joined together in a ball and socket relationship which provides full rotational movement thereof. The flexible spacer therebetween provides the resilient compressive strength necessary to maintain the vertical separation of the adjacent vertebrae. The flexible resilient spacer completely surrounds the ball and socket portions of the cylindrically shaped members. Each cylindrically shaped member is fastened to the bone in the adjacent vertebrae with an arcuate plate and is secured with a fastener that engages the bone in the adjacent vertebrae and a threaded recess in the cylindrically shaped member. A cavity is routed out of the adjacent vertebrae by a routing guide tool and the invention is implanted in the patient by a special alignment and holding tool that allows the surgeon to drill through channels in the bone in the adjacent vertebrae in perfect alignment with threadable recesses in the cylindrically shaped members. An

sized fastener is inserted through an aperture in the arcuate plate and engages the bone material and a threaded portion the recess in the cylindrically shaped member.

Claims

1. An artificial intervertebral disk system for replacing a damaged human disk between two adjacent vertebrae in a spinal column and preserving the full range of motion and functionality of the spinal column comprising in combination;

paired cylindrically shaped members in a vertical, stacked, mated relationship and a flexible spacer therebetween, the paired cylindrically shaped members having an upper member having a top end and a bottom end having a downwardly depending stem with a spherical socket on a distal end thereof and further having a lower member having a bottom end and a top end having an upwardly depending stem with a spherical ball on a distal end thereof adapted for rotational mating with the spherical socket, the flexible spacer completely surrounding the spherical socket and the spherical ball for maintaining the separation distance between the adjacent vertebrae and preserving the full functionality of the spinal column;

a plurality of arcuate plates for urging securement of the paired cylindrically shaped members to the two adjacent vertebrae;

a plurality of fasteners for threadably attaching the artificial disk and the plurality of arcuate plates through the two adjacent vertebrae on the spinal column;

fixture means to hold the paired cylindrically shaped members in a fixed position for urging drilling of a plurality of channels through the two adjacent vertebrae for allowing threadable engagement of each one of the plurality of fasteners with the adjacent vertebrae; and

second fixture means for temporarily holding the adjacent vertebrae in a steady motionless state for urging routing of a cavity in the adjacent vertebrae sufficiently sized to accept the paired cylindrically shaped members.

2. An artificial intervertebral disk system as recited in claim 1 wherein the upper member further includes a plurality of recesses, each recess being threadably adapted to receive one of the fasteners.

3. An artificial intervertebral disk system as recited in claim 1 wherein the lower member further includes a second plurality of recesses, each recess being threadably adapted to receive one of the fasteners.

4. An artificial intervertebral disk system as recited in claim 1 wherein the paired cylindrically shaped members are made from stainless steel.

5. An artificial intervertebral disk system as recited in claim 1 wherein the paired cylindrically shaped members are made from a titanium alloy.

6. An artificial intervertebral disk system as recited in claim 1 wherein the flexible spacer is made from a silicone elastomer.

7. An artificial intervertebral disk system as recited in claim 1 wherein the flexible spacer is made from a silicone rubber.

8. An artificial intervertebral disk system as recited in claim 1 wherein the fixture means further includes a plurality of alignment and holding tools for fixturing the paired cylindrically paired shaped members in a steady, fixed relationship to the two adjacent vertebrae for urging drilling of the plurality of channels in the two adjacent vertebrae, each channel being in a coaxial alignment with one of the recesses threadably adapted to receive one of the fasteners.

9. An artificial intervertebral disk system as recited in claim 1 wherein each arcuate plate further includes a plurality of apertures, each aperture for urging communication between one of the threadable recesses and one of the fasteners.

10. An artificial intervertebral disk system as recited in claim 8 wherein the alignment and holding tool further includes a open-ended tube on an end for urging coaxial alignment between one of the apertures on the arcuate plate and one of the threaded recesses, a fixturing member on another end for securely engaging a middle portion of the stem of the ball or socket member for urging motionless alignment of the ball and socket with the two adjacent vertebrae, and a handle therebetween for a surgeon to grasp.

11. An artificial intervertebral disk system as recited in claim 10 wherein the open-ended tube and the fixturing member of the alignment and holding tool are coplanar and the handle is disposed transversely to the open-ended tube and the fixturing member.

12. An artificial intervertebral disk system as recited in claim 10 wherein the alignment and holding tool is fabricated from a surgical quality stainless steel.

13. An artificial intervertebral disk system as recited in claim 1 wherein each fastener further has a slotted head on a first end and a shank with a machine thread on a distal end for threadably mating to one of the threadable recesses in the cylindrically shaped member, and a middle portion therebetween, the middle portion having a cancellous thread for secure engagement with the bone in the two adjacent vertebrae, and a screwdriver for engaging the slotted head for rotating the fastener for threadably engaging an inner surface of one of the channels drilled in the bone and one of the threaded recesses in the cylindrically shaped member.

14. An artificial intervertebral disk system as recited in claim 13 and further including a plurality of washers for lockable communication between the threaded fasteners and the cylindrically shaped member, each washer having a first end with a flat surface for coplanar engagement with a transverse surface of one of the threaded fasteners and a second end with an arcuate shaped surface for continuous lockable engagement with an outer periphery of one of the cylindrically shaped members.

15. An artificial intervertebral disk system as recited in claim 13 wherein the machine thread and the cancellous thread on the middle portion have the same pitch.

16. An artificial intervertebral disk system as recited in claim 1 wherein the paired cylindrically shaped members in the vertical, stacked relationship have their respective cylinders reversed in relation to each other, the spherical ball depending downwardly from the downwardly depending stem and the spherical socket depending upwardly from the upwardly depending stem.

17. An artificial intervertebral disk system as recited in claim 1 wherein the arcuate plates further include a section surrounding each one of the apertures on an outer surface for urging the slotted head of the fastener to a final co-aligned position with the outer surface of the arcuate plates.

18. An artificial intervertebral disk system as recited in claim 1 wherein the paired cylindrically shaped members, the arcuate plates, the fasteners, and the washers all have a surface shaped to encourage adherence to the surrounding vertebral bone.

19. An artificial intervertebral disk system as recited in claim 1 wherein the second fixture means further includes a flat plate having a first side adapted with mini-spikes for temporary securement to the adjacent vertebrae and a second side having a plurality of parallel disposed channels and further having a plurality of positioners for maintaining a space between the adjacent vertebrae, the second side also having a upper end and a lower end adapted for adjustably limiting the length of the cavity and a router bit aperture therebetween adapted for slidable engagement with the parallel disposed channels.

20. A method of replacing a damaged human disk between two adjacent vertebrae in a spinal column with an artificial intervertebral disk for preserving the full range of motion and functionality of the spinal column comprising the steps of:

exposing the anterior portion of the spinal column and removing the damaged disk from between the two adjacent vertebrae;

attaching a routing guide to the adjacent vertebrae;

routing out a cavity in the two adjacent vertebrae to a size sufficient to accept the artificial disk;

removing the routing guide;

implanting the artificial disk in the cavity;

fixturing the artificial disk in a steady, motionless state with the alignment and holding tool;

drilling a plurality of channels through the bone in the two adjacent vertebrae with a stop on the drill bit at about between 10 to 20 millimeters in depth;

measuring the depth of each channel drilled through the bone with a depth gage and selecting the proper length fastener to threadably engage the interior surface of each channel and one of the recesses in the cylindrically shaped member;

packing the cavity with a cortico cancellous bone graft;

removing the alignment and holding tool;

attaching one of the arcuate plates to the cylindrically shaped members and threadably engaging the interior surface of each one of the channels through one of the apertures in the arcuate plates with one of the fasteners;

rotating each fastener with a screwdriver to threadably engage one of the recesses in the cylindrically shaped member; and

closing up the anterior portion of the spinal column.