Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
2000-08-22
2002-09-10
McDermott, Corrine (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S017110
Reexamination Certificate
active
06447547
ABSTRACT:
BACKGROUND
The present invention relates to an artificial fusion implant to be placed into the intervertebral space left after the removal of a damaged spinal disc.
The purpose of the present invention is to provide an implant to be placed within the intervertebral disc space and provide for the permanent elimination of all motion at that location. To do so, the device is space occupying within the disc space, rigid, self-stabilizing to resist dislodgement, stabilizing to the adjacent spinal vertebrae to eliminate local motion, and able to intrinsically participate in a vertebra to vertebra bony fusion so as to assure the permanency of the result.
At present, following the removal of a damaged disc, either bone or nothing is placed into the space left. If nothing is placed in the space the space may collapse which may result in damage to the nerves; or the space may fill with scar tissue and eventually lead to a reherniation. The use of bone is less than optimal in that the bone obtained from the patient requires additional surgery and is of limited availability in its most useful form, and if obtained elsewhere, lacks living bone cells, carries a significant risk of infection, and is also limited in supply as it is usually obtained elsewhere, lacks living bone cells, carries a significant risk of infection, and is also limited in supply as it is usually obtained from young accident victims. Furthermore, regardless of the source of the bone, it is only marginal structurally and lacks a means to either stabilize itself, against dislodgement, or to stabilize the adjacent vertebrae.
A review of all possibly related prior art will demonstrate the novelty of the present invention.
There have been an extensive number of attempts to develop an acceptable disc prothesis (an artificial disc). Such devices by design would be used to replace a damaged disc and seek to restore the height of the interspace and to restore the normal motion of that spinal joint. No such device has been found that is medically acceptable. This group of prosthetic or artificial disc replacements seeking to preserve spinal motion which are different from the present invention include:
U.S. Pat. No. 3,867,728 STUBSTAD—describing a flexible disc implant.
U.S. Pat. No. 4,349,921 KUNTZ—describing a flexible disc replacement with rope or file like surface projections to discourage device dislocation.
U.S. Pat. No. 4,309,777 PATIL—describing motion preserving implant with spike outer surfaces to resist dislocation and containing a series of springs to urge the vertebrae away from each other.
U.S. Pat. No. 3,875,595 FRONING—describing a motion preserving bladder like disc replacement with two opposed stud like projections to resist dislocation.
U.S. Pat. No. 2,372,622 FRENCH (FASSIO)—describing a motion preserving implant-comprising complimentary opposed convex and concave surfaces.
In summary then, these and other similar devices resemble the present invention only in that they are placed within the intervertebral space following the removal of a damaged disc. In that they seek to preserve spinal motion, they are diametrically different from the present invention which seeks to permanently eliminate all motion at that spinal segment.
A second related area of prior art includes those devices utilized to replace essentially wholly removed vertebrae. Such removal is generally necessitated by extensive vertebral fractures, or tumors, and is not associated with the treatment of disc disease, or therefore related to the present invention. While the present invention is to be placed within the disc space, these prior devices cannot be placed within the disc space as at least one vertebrae has already been removed and there no longer remains a “disc space.” Furthermore, all of these devices are limited in that they seek to perform as temporary structural members mechanically replacing the removed vertebrae (not a removed disc), and do not intrinsically participate in supplying osteogenic material to achieve cross vertebrae bony fusion. Therefore, again unlike the present invention which provides for a source of osteogenesis, use of this group of devices must be accompanied by a further surgery consisting of a bone fusion procedure utilizing conventional technique. This group consisting of vertebral struts rather than disc replacements would include the following:
U.S. Pat. No. 4,553,273 WU —describing a turnbuckle like vertebral strut.
U.S. Pat. No. 4,401,112 REZAIAN—describing a turnbuckle like vertebral strut with the addition of a long stabilizing staple that spans the missing vertebral body.
U.S. Pat. No. 4,554,914 KAPP—describing a large distractible spike that elongates with a screw mechanism to span the gap left by the removal of a entire vertebrae and to serve as an anchor for acrylic cement which is then used to replace the missing bone (vertebrae).
U.S. Pat. No. 4,636,217 OGILVIE—describing a vertebral strut mechanism that can be implanted after at least one vertebrae has been removed and which device consists of a mechanism for causing the engagement of screws into the vertebrae above the vertebrae below the one removed.
In summary then, this group of devices differs from the present invention in that they are vertebral replacements struts, do not intrinsically participate in the bony fusion, can only be inserted in the limited circumstances where an entire vertebrae has been removed from the anterior approach, and are not designed for, or intended to be used for the treatment of disc disease.
A third area of prior art related to the present invention includes all devices designed to be applied to one of the surfaces of the spine. Such devices include all types of plates, struts, and rods which are attached by hooks, wires, and screws. These devices differ significantly from the present invention in that they are not inserted within the disc space, and furthermore do not intrinsically participate in supplying osteogenic material for the fusion.
Therefore, with these devices where permanent spinal immobilization is desired an additional surgery consisting of a spinal fusion performed by conventional means or the use of supplemental methylmethacrylate cement is required. Such devices, applied to the spine but not within the disc space, would include the following:
U.S. Pat. No. 4,604,995—STEPHENS—describing a “U” shaped metal rod attached to the posterior elements of the spine with wires to stabilize the spine over a large number of segments.
U.S. Pat. No. 2,677,369—KNOWLES—describing a metal column device to be placed posteriorly along the lumbar spine to be held in position by its shape alone and to block pressure across the posterior portions of the spinal column by locking the spine in full flexion thereby shifting the maximum weight back onto the patient's own disc.
Other devices are simply variations on the use of rods (e.g. Harrington, Luque, Cotrel-Dubosset, Zielke), wires or cables (Dwyer), plates and screws (Steffee), or struts (Dunn, Knowles).
In summary, none of these devices are designed for or can be used within the disc space, do not replace a damaged disc, and do not intrinsically participate in the generation of a bony fusion.
Other prior art possibly related to the present invention and therefore, to be considered related to “Bony Ingrowth”. Patents related to this feature describe either methods of producing materials or devices to achieve the same. Such patents would include:
U.S. Pat. No. 4,636,526 (DORMAN), U.S. Pat. No. 4,634,720 (DORMAN), U.S. Pat. No. 4,542,539 (ROWE), U.S. Pat. No. 4,405,319 (COSENTINO), U.S. Pat. No. 4,439,152 (SMALL), U.S. Pat. No. 4,168,326 (BROEMER), U.S. Pat. No. 4,535,485 (ASHMAN), U.S. Pat. No. 3,987,499 (SCHIARBACH), U.S. Pat. No. 3,605,123 (hIAHN), U.S. Pat. No. 4,655,777 (DUNN), U.S. Pat. No. 4,645,503 (LIN), U.S. Pat. No. 4,547,390 (ASHMAN), U.S. Pat. No. 4,608,052 (VAN KAMPEN), U.S. Pat. No. 4,698,375 (DORMAN), U.S. Pat. No. 4,661,536 (DORMAN); U.S. Pat. No. 3,952,334 (BOKROS), U.S. Pat. No. 3,905,047 (LONG), U.S. Pat. No. 4,693,721 (DUCHEYNE), U.S. Pat. N
Barrett Thomas
Martin & Ferraro LLP
McDermott Corrine
Sofamor Danek Group, Inc.
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