PCI‘
`
`International Bureau
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`
`
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(51) International Patent Classification 4 3
`
`(11) International Publication Number:
`
`W0 90/00037
`
`A611“ 2/44
`
`(43) International Publication Date:
`
`11 January 1990 (11.01.90)
`
`(21) International Application Number:
`
`PCT/USS9/02791 RO, SE, SE (European patent).
`
`(22) International Filing Date:
`
`28 June 1989 (28.06.89)
`
`(30) Priority data:
`212,480
`
`'
`
`28 June 1988 (28.06.88)
`
`US
`
`Published
`With international search report.
`
`(7l)(72) Applicant and Inventor: MICHELSON, Gary, Karlin
`[US/US]; 438 Sherman Canal, Venice, CA 90291 (US).
`
`(74) Agent: SCHELLIN, Eric, P.; Suite 704, Two Crystal Park,
`2121 Crystal Drive, Arlington, VA 22202 (US).
`
`(81) Designated States: AT (European patent), AU, BB, BE (Eu-
`ropean patent), BG, BR, CH (European patent), DE (Eu-
`ropean patent), DK, FI, FR (European patent), GB (Eu-
`ropean patent), HU, IT (European patent), JP, KP, KR,
`
`(54) Title: ARTIFICIAL SPINAL FUSION IMPLANTS
`
`LU (European patent), NL (European patent), NO,
`
`
`(57) Abstract
`
`A spinal implant (10) is disclosed which when placed within the spinal disc space stabilizes that spinal segment and mate-
`rially participates in, and is incorporated in the ensuing fusion.
`
`1
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`NUVASIVE 1008
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`United States of America
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international
`applications under the PCT.
`AT
`Austria
`AU
`Australia
`BB
`Barbados
`BE
`Belgium
`BF
`Burk'ma Fasso
`BG
`Bulgaria
`Benin
`BI
`BR
`Braznl
`CF
`Central Afrimn Republicr
`CG
`Congo
`CH
`Switzerland
`Cameroon
`CM
`DE
`Germany, Federal Republic of
`DK
`Denmark
`ES
`Spain
`
`K R
`
`UL
`
`K
`LU
`MC
`MG
`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`FI
`FR
`GA
`GB
`HU
`IT
`JP
`KP
`
`Finland
`France
`Gabon
`United Kingdom
`Hungary
`Italy
`Japan
`Democratic People‘s Republic
`of Korea
`Republic of Korea
`Liechtenstein
`Sri Lanka
`Luxembourg
`Monaco 7
`Madagasmr
`
`ML
`MR
`
`Mali
`Mauritania
`Malawi
`Netherlands
`Norway
`Romania
`Sudan
`Sweden
`Senegal
`Soviet Union
`Chad
`Togo
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`ARTIFICIAL SPINAL FUSION IMPLANTS
`
`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 spacea
`
`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
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`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:
`
`Patent No. 3,867,728 STUBSTAD - describing a
`flexible disc implant.
`
`Patent No. 4,349,921 KUNTZ — describing a
`
`flexible disc replacement with rope or file like surface
`
`projections to discourage device dislocation.,
`
`Patent 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.
`
`Patent No. 3,875,595 FRONING - describing a
`motion preserving bladder like disc replacement with two
`
`opposed stud like projections to resist dislocation.
`
`Patent No. 2,372,622 FRENCH (FAssrm‘ - 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 thy 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
`
`7
`
`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
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`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 procefure utilizing conventional technique. This
`
`group consisting of vertebral struts rather than disc
`
`10
`
`replacements would include the following:
`
`Patent No. 4,553,273 WU - describing a turnbuckle
`
`like vertebral strut.
`
`Patent No. 4,401,112 REZAIAN - describing a
`
`turnbuckle like vertebral strut with the addition of a long
`
`.15
`
`stabilizing staple that Spans the missing vertebral body.
`
`Patent 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).
`
`Patent 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
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`intrinsically participate in supplying osteogenic material
`for the fusion.
`7
`
`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:
`
`Patent 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.
`Patent 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 miximum weight back onto the patient's own
`disc.
`7
`
`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:
`
`Patents No. 4,636,526 (DORMAN), No. 4,634,720
`
`(DORMAN), No. 4,542,539 (ROWE), No. 4,405,319 (COSENTINO),
`
`No. 4,439,152 (SMALL), No. 4,168,326 (BROEMER), No.
`
`4,535,485 (ASHMAN), No. 3,987,499 (SCHARBACH), No.
`
`3,605,123 (HAHN), No. 4,655,777 (DUNN), No. 4,645,503
`
`(LIN), No. 4,547,390 (ASHMAN), No. 4,608,052 (VAN KAMPEN),
`
`No. 4,698,375 (DORMAN), No. 4,661,536 (DORMAN), No.
`
`3,952,334 (BOKROS), No. 3,905,047 (LONG), No. 4,693,721
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`(DUCHEYNE), No. 4,070,514 (ENTHERLY).
`
`However, while the present invention would
`
`utilize bone ingrowth technology, it would do so with
`
`conventional technology.
`
`The final area of related prior art to be
`
`considered is that of devices designed to be placed within
`
`the vertebral interspace following the removal of a damaged
`
`disc, and seeking to eliminate further motion at that
`location.
`
`Such a device is contained in Patent No.
`
`4,501,269 BAGBY describing an implantable device,
`
`limited
`
`instrumentation, and a method; whereby a hole is bored
`
`transversely across the joint and then a hollow metal
`
`basket of larger diameter is then pounded into the hole and
`
`then filled with the bone debris generated by the drilling.
`
`The present invention differs from the prior art devices in
`
`the following ways:
`
`1.
`
`UNIVERSAL APPLICABILITY WITHOUT CONTOURING OF
`
`THE INTERSPACE.
`
`The present device will fit any patient,
`
`anywhere throughout the spine,
`
`in any intervertebral disc
`
`space, and without alteration of that interspace regardless
`
`of its natural size or shape.
`
`2.
`
`RESTORATION AND PRESERVATION OF THE
`
`INTERSPACE.
`
`The present invention will restore the
`
`intervertebral space to its premorbid dimensions, and do so
`
`by having the implant fit the space rather than having to
`
`modify the interspace, by bone removal from the vertebrae,
`
`to accommodate the implant.
`
`END PLATE PRESERVATION. Preservation of the
`
`3.
`
`highly specialized weight bearing cortical bone is allowed
`
`and end plate perforation into the highly vascular
`
`cancellous bone marrow with its attendant bleeding is
`
`avoided.
`
`Such bleeding, when it occures, bears all the
`
`risks of blood loss (e.g. hypoglycemic shock,
`
`transfusion
`
`transmitted diseases such as hepatitis and acquired immune
`
`deficiency syndrome, etc.), and all the complications
`
`arising from the resultant impaired visualisation of the
`
`vital structures (e.g. nerves, blood vessels, and organs
`
`due to SUCh bleeding.
`
`4.
`
`TECHNIQUE.
`
`The technique for insertion of
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`
`these implants is consistent with the established methods
`
`of disc removal, and requires neither specialized
`
`instrumentation nor specialized surgical technique.
`5.
`EXTENT OF DISC REMOVAL.
`The extent of disc
`
`removal can be determined by the surgeon at the time
`
`surgery and can be individualized for each patient.
`
`6.
`
`NO DRILLING.
`
`No drilling is involved with
`
`the use of the present invention.
`ELIMINATION OF INCORRECT IMPLANT SIZE
`
`7.
`
`SELECTION.
`
`In those implant systems where a drill is used
`
`and significant bone is removed then an estimate of the
`
`implant size must first be made, and then, regardless of
`
`the fit, an implant at least as large as the space created
`
`by the drilling must be utilized, regardless of the quality
`
`of that fit. With the present invention no significant
`
`bone is removed, and the correct size implants are fitted
`
`directly to the interspace eliminating the need to guess at
`
`the correct implant size before the fact.
`
`8. MODULAR DESIGN.
`
`The present implants are
`
`available in varying lengths to accommodate the changing
`
`depths of the interspace from central to lateral.
`
`The
`
`devices are available in varying heights or are infinitely
`
`adjustable as to the height within the physiological range.
`
`The widths are standardized, and the various embodiments
`
`can be used in any combination (e.g.
`
`in the lumbar spine
`
`two auto-expanding implants could be used in conjunction
`
`with two anchor deploying implants to completely fill the
`
`interspace).
`
`9.
`
`
`AVOIDANCE 0F SIZE LIMITATIONS. Because in
`
`one embodiment the system is modular, component parts can
`
`be inserted through a very small opening until a much
`
`larger implant is reconstituted completely filling the
`
`'available interspace;
`
`and yet much larger when assembled
`
`than the opening through which the component modular
`
`sections were introduced.
`
`For example,
`
`in the lumbar spine
`
`four implants introduced one at a time and measuring 8mm in
`
`width, would when reconstituted within the interspace
`
`constitute a 32mm wide implant.
`
`Implantation of a single
`
`implant of those dimensions from a posterior approach in 40
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`the lumbar spine would otherwise be impossible because of
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`the presence of the dural sac and spinal nerves.
`10.
`THE AVOIDANCE OF INTERSPACE COLLAPSE.
`
`The
`
`device is many times stronger than bone and will not
`
`collapse.
`
`The implantation of the device allows
`
`preservation of the very strong vertebral cortex, which is
`
`resistant to compression preventing the migration of the
`
`implant into the vertebrae.
`
`The large surface area of the
`
`assembled modular implant, minimizes the load per unit
`
`10
`
`For example, a reconstituted lumbar implant of four
`area.
`modular components would have the weight distributed over
`
`approximately 8 sq. cm. per vertebral interface.
`
`11.
`
`REMOVABILITY. Because the present invention
`
`is an interspace implant and not a "through vertebrae"
`
`. cross interspace implant,
`
`removal of the implant, should
`
`that become necessary, would not result in iatrogenic
`
`destruction of the adjacent vertebrae.
`
`SELF-STABILIZING. The implant is
`
`12.
`
`self-stabilizing without the use of threads. All of the
`
`implants are surface configured to resist dislodgement and
`
`the preferred embodiments contain active, mechanical means
`
`to assure permanent anchoring.
`
`Long term stability begins
`
`with the above and is further enhanced by surface treating
`
`of the implant for bone ingrowth (by known conventional
`
`means) and”osteogenically loading the implants.
`
`l3.
`
`SPINE REDUCING. Various embodiments of the
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`present invention such as the ones with the 180 degree
`
`opposed ratcheted surface, and the auto-expanding type, are
`
`capable of reducing a vertebral listheses ( a forward or
`
`backward translation of one vertebrae upon another).k
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`
`capable
`
`l4.
`
`SPINAL STABILITY. These implants are
`
`of stabilizing a spial segment following disc removal, and
`
`do so without the use of threads (threads would be design
`
`need to violate the vertebrae themselves extensively).
`
`15.
`
`SAFETY.
`
`The entire procedure is performed
`
`under direct vision and with complete visualization of the
`
`adjacent vital structures (e.g. organs, neural structures
`and blood vessels).
`
`In summary then,
`
`the present invention is an
`
`interspace implant utilized to replace a damaged disc,
`
`which unlike an artificial disc, seeks to permanently
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`eliminate rather than to preserve spinal motion, and to do
`
`so by a bony fusion.
`
`The present invention is clearly an
`
`improvement over the prior art providing an interspace
`
`implant intrinsically participating in the fusion process,
`
`self-stabilizing, stabilizing to the spinal segment,
`
`consistent with conventional methods of discectomy, and
`
`uniquely consistent with the preservation of the integrity
`
`of the adjacent vertebrae.
`BRIEF SUMMARY OF THE PRESENT INVENTION
`
`The present invention comprises an artificial
`
`implant,
`
`the purpose of which is to participate in, and
`
`directly cause bone fusion across an intervertebral space
`
`following the excision of a damaged disc. Said implants
`
`are structurally load bearing devices, stronger than bone,
`
`capable of withstanding the substantial forces generated
`
`within the spinal interspace.
`
`Such devices have a
`
`plurality of macro sized cells and openings of 1~3mm, which
`
`can be loaded with fusion promoting materials, such as
`
`autogenous bone, for the purpose of materially influencing
`
`the adjacent vertebrae to perform a bony bond to the
`
`implants and to each other.
`
`The implant casing may be
`
`surface textured or otherwise treated by any of a number of
`
`known technologies to achieve a "bone ingrowth surface" to
`
`further enhance the stability of the implant and to
`
`expedite the fusion. Further, said devices are so
`
`configured and designed so as to promote their own
`
`stability within the vertebral interspace to resist
`
`dislodgement, and furthermore,
`vertebrae.
`
`to stabilize the adjacent
`
`To use the implant of the present invention a
`
`conventional discectomy is performed and the vertebral
`
`endplates scraped, but not perforated.
`
`The appropriately
`
`sized implants are loaded with autogenous bone and
`
`implanted within the interspace.
`
`For example for an anterior cervical device
`
`implantation, a short transverse incision is made across
`
`the front of the neck and to the right of the midline
`
`directly over the diseased disc.
`
`The platysma muscle is
`
`split, and the sternocleidomastoid muscle with is split,
`
`and the sternocleidomastoid muscle with the carotid sheath
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`The esophagus,
`is protected and retracted laterally.
`trachea and associated midline structures are protected and
`
`retracted medically,
`
`thus exposing the anterior aspect of
`
`the cervical spine.
`
`The diseased disc is identified and
`
`removed by conventional surgical methods.
`
`The adjacent
`
`vertebral endplates are gently scraped free of any
`
`remaining cartilage until diffuse fine punctuate
`
`decortication is achieved.
`
`The dimensions of the
`
`interspace are then measured in mild distraction, and the
`
`appropriate implant selected. Cancellous bone, obtained
`
`from the patient's iliac crest or the equivalent, is loaded
`
`into the implant.
`
`The safety driver is then utilized to
`
`insert the implant behind the anterior lips of the
`
`vertebrae.
`
`The wound is then closed in the routine manneriw
`./
`
`Objects of the Present Invention
`
`It is an object of the present invention to
`
`provide for means of achieving interspace fusion and
`
`stabilization as a single procedure by a means consistent
`
`with the conventional method of discectomy.
`
`It is another object of the present invention to
`
`provide for a means of achieving an interspace fusion and
`
`stabilization that is quicker, safer, and entails less
`
`blood loss than by any other known means.
`
`It is another object of the present invention to
`
`provide for means of achieving a one stage interspace
`
`fusion and stabilization without significant violation or
`
`removal of the adjacent vertebral bone stock.
`
`It is another object of the present invention to
`
`provide for method of intervertebral arthrodesis and
`
`stabilization of enhanced safety where the entire procedure
`
`is performed under direct vision.
`
`It is another object of the present invention to
`
`provide for a method of intervertebral arthrodesis and
`
`stabilization of greater simplicity and requiring minimal
`
`specialized instrumentation or technique not already
`
`possessed by those doing such procedures by conventional
`means.
`
`It is another object of the present invention to
`
`provide for modular prosthesis, allowing complimentary
`
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`W0 90/00037
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`PCI /USS9/02791
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`-10-
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`subunits to be inserted individually through a small
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`opening and to then be reassembled within the interspace,
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`so as to reconstitute an interspace occupying device much
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`larger than would be insertable as a whole.
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`It is another object of the present invention to
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`to provide for a modular impant system such that it is
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`possible to precisely fit the contours of any interspace
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`without the need to sacrifice any vertebral bone to
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`accommodate the prosthesis. These and other objects of the
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`present invention will be apparent from review of the
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`following specifications and the accompanying drawings.
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`Brief description of the Drawings
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`Figure l is a top right perspective view of the
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`implant (cervical type).
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`Figure la is a front View of the implant of Fig.
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`1.
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`1.
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`1.
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`1.
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`Figure lb is a rear view of the implant of Fig.
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`Figure lc is a top view Of the implant of Fig. 1.
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`Figure 1d is a side view of the implant of Fig.
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`Figure 1e is a bottom View of the implant of Fig.
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`Figure 2 is a side sectional view of the implant
`viewed along lines 2-2 of Fig.
`ld.
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`Figure 3 is the implant Figure 1 showing the
`attachment to the driver and driver.
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`Figure 4 is a front perspective view showing the
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`implant being driven into the disc space.
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`3O
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`Figure 4a is a front perspective View of the
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`implant located in the spine.
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`"
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`Figure 5 is a side View of the implant in the
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`spine'attached to the driver.
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`Figure 5a is a close up partial sectional View of
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`the implant and driver.
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`Figure 6 is a perspective View of a series of
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`implants placed in the cervical intervertebral space.
`Figure 6A is an alternative embodiment of a
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`rectangular solid implant.
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`W0 90/00037
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`PCI /US89/02791
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`-1]—
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`Figure 7 is a side sectional View of the
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`vertebrae and implant viewed along lines 7-7 of Figure 6.
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`Figure 7A is a side sectional view of the
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`vertebrae structure showing a third embodiment of the
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`rectangular solid implant in place.
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`Figure 8 is an exploded perspective view of
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`another embodiment of the present invention.
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`Figure 9 is a side sectional view of the
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`vertebrae structure and implant viewed along lines 9-9 of
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`Fig. 8.
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`Figure 10 is a side sectional view of the implant
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`of Figure 8,
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`in a contracted position.
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`Figure 11 is a side sectional view of the implant
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`of Figure 10,
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`in an expanded position.
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`Figure 12 is a perspective view of an alternative
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`embodiment of the implant of Figure 9.
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`Figure 13 is an alternative embodiment of a
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`hollow rectangular solid implant.
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`Figure 14 is a cross sectional View of the hollow
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`rectangular solid implant of Figure 13 viewed along lines
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`14-14 of Fig. 13.
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`Figure 15 is an alternative embodiment of an
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`expandable implant in its extended position.
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`Figure 16 is an expandable implant of Figure 15
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`in its retracted position.
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`Figure 17 is an expandable implant of Figure 16
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`located in the disc space.
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`Referring to Figures 1 through 5 an implant for
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`use in the disc space and associated apparatus used for
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`inserting the implant 10 is shown.
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`The implant 10 is shown
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`as a substantially rectangular hollow configuration, having
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`a tapered forward portion.
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`The implant 10 has an upper surface 12 and a
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`parallel lower surface 14.
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`The two side walls 16 and 18
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`are parallel to one another and have a series of small
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`sized Openings 20 of lmm-3mm through the side walls 16 and
`18.
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`The front wall 22 is slightly convex and has a
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`depressed portion 24 with a central threaded opening 26 for
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`40
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`receiving the engaging end 28 of a driving member 30.
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`‘4)
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`“u
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`W0 90/00037
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`-12-
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`PCI IU889/02791
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`The upper surface 12 has a threaded cap 32, which
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`has opening 33 there through, with a central allen wrench
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`opening 34 for engagement with an allen wrench A of Figure
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`3.
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`The cap 32 covers the opening into the hollow implant
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`19 and permits the insertion of autogenous bone material
`into the hollow portion of the implant 10.
`The cap 32 is
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`surrounded by a series of small sized openings 36 of 1mm to
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`3mm passing through the upper surface and into the central
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`hollow portion of the implant 10.
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`The rear wall 38 is convex so as to conform to
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`the rear of the disc space.
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`The driving member 30, shown in.figure 3,
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`comprises a substantially hollow tubular member 40 having a
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`long internal rod 42 having a turning knob 44 at one end
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`and a threaded portion 46 at the other end for threadably
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`engaging the threaded opening 26 of the implant 10.
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`The
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`engaging end 28 of the driving member 30 has a slightly
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`convex surface to complement the slightly convex surface of
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`the front wall 22.
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`The engaging end 28 has an extension 48
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`for fitting within the depressed portion 24 on the front
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`wall 22 of the implant 10.
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`The engaging end 28 also has
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`restriction members 47 and 49 to restrict the depth of
`penetration of the driver 30.
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`In use,
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`the cap 32 is removed from the implant 10
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`and autogenous bone material is inserted into the hollow
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`portion of the implant 10.
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`The cap is then replaced.
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`Various methods of packing the implant 10 with the
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`autogenous bone material may be used to obtain a completely
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`packed implant 10.
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`Referring to Figures 4, 4a,
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`5 and 5a,
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`the method
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`of inserting the implant is shown.
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`The threaded end 46 of
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`the internal rod 42 of the driving member 30 is attached to
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`the threaded opening 26 of the implant 10 by turning of the
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`knob 44. Once the engaging end 28 is in place,
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`the fitting
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`of the extended portion 48 into the depressed portion 24
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`prevents movement of the implant 10 in relationship to the
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`driving member 30.
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`The implant is then placed at the entrance to the
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`disc space between the two adjacent vertebrae V.
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`The knob
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`44 is then tapped with hammer H sufficiently hard enough to
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`W0 90/00037
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`PCT /USS9/02791
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`-13—
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`drive the implant 10 into the disc space.
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`The restriction
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`members 47 and 49 which are wider than the disc space,
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`prevent over penetration of the implant.
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`The size of the implant 10 is substantially the
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`same size as the disc space that it is replacing and thus
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`will be larger or smaller depending on the disc space in
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`which it is to be used.
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`In the preferred embodiment the
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`implant 10 is approximately 32mm wide.
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`shown in place in the disc space after removal of the
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`Referring to Figures 4A and 5 the implant 10 is
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`driving member once the implant was inserted in place.
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`The autogenous bone material that was packed
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`within the hollow portion of the implant 10 serves to
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`promote bone ingrowth between the implant and the adjacent
`vertebrae. Once the bone ingrowth occurs,
`the implant 10
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`will be a permanent fixture preventing dislodgement of the
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`implant as well as preventing any movement between the
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`adjacent vertebrae.
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`Referring to Figure 6 an alternative embodiment
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`The implant 61 comprises a
`of the implant is disclosed.
`substantially rectangular member having a series of ridges
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`62 on the upper and lower surfaces of the implant 60. One
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`or more grooves 64 are placed on the upper and lower
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`surfaces as well. As indicated in Figure 6, a series of
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`such implants 61 are used as the interbody spinal implant,
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`each placed closely adjacent one another to approximate the
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`size of the removed disc.
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`A series of micro sized opening
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`63 perforate the implant 61,
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`to promote bone ingrowth.
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`The implant of Figure 6 is inserted as follows:
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`the disc is substantially removed by conventional means.
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`The implants 61 are then inserted in the intervertebral
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`space between the two vertebrae.
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`The size of the implant 61 of Figure 6 is
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`approximately 26 millimeters in length and is wide enough
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`so that four of them will substantially fill the
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`intervertebral space, depending on which vertebras are
`fused.
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`In Figure 6a a "bullet nosed" implant 67 having a
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`Open front portion 69 to facilitate insertion of implant 67
`is shown.
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`W0 90/00037
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`PCT /USS9/02791
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`-14-
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`Referring to Figures 7 and 7a alternative
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`embodiments of the implant 61 of Figure 6~is shown in place
`between two vertebrae V.
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`In Figure 7 the implant 70 is shown with the
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`ridges 62 shown in the form of teeth facing the anterior.
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`These ridges serve to prevent the implant 60 from 'walking'
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`out of the space between the vertebrae.
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`In Figure 7a an embodiment of the implant 70 of
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`Figure 6 is shown having opposed ridges 72 and 74. This
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`serves to maintain the alignment of the vertebrae when the
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`two vertebrae V are improperly aligned with respect to one
`another.
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`Referring to Figure 8 an adjustable implant 81
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`having means for adjusting the width of the implant 81 is
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`shown.
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`The implant 81 comprises a lower member 82 and an
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`upper member 84 which when fitted together form an
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`essentially rectangular implant.
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`The upper member 84 and
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`the lower member 82 have hollow portions that face one
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`another and receive tapered wedges 86 and 88 that fit
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`within the hollow portion of the upper and lower members 82
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`and 84.
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`The wedges 82 and 84 are such that at their large
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`and they are higher than the combined hollow space between
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`the upper and lower members 84 and 82, and shallower at the
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`other and than the hollow space between the upper and lower
`members.
`7
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`The wedges 86 and 88 have a central threaded
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`opening 90 and 92 in alignment with each other for
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`receiving threaded screw 94. Deformable burrs 95 on the
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`head 98 of the screw 94 are used for locking the screw in
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`place.
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`The implant has a series of holes 100 throughout
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`the body of the implant to assist in the ingrowth process.
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`Referring to Figures 9 through 11 the expandable
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`implant 81 is shown positioned between the two vertebrae V.
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`7 In Figure 10 the expandable implant 81 is illustrated in
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`its contracted position.
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`The wedges 86 and 88 abutt the
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`interior sloped surfaces 104 of the upper and lower members
`82 and 84.
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`As the screw 94 is turned, as shown in Figure 11,
`the wedges 86 and 88 are drawn together, and the sloped
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`portions of the wedges force the upper member 82 away from
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`W0 90/00037
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`PCI /USS9/02791
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`-15_
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`the lower member 84. Once the screw 94 has been turned
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`the screw head 98 is hit, causing the
`sufficiently,
`deformable burrs to be crimped so as to prevent the reverse
`rotation of the screw 94.
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`In Figure 12, another alternative embodiment of
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`the expandable implant 81 is illustrated with spike
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`projections 106 extending from the top and bottom members
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`to dig into the vertebrae and assist in maintaining it in
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`place.
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`In use,
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`the disc is removed, and the implant 81
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`is placed between the vertebrae.
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`The screw 94 is then
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`turned expanding the implant.
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`In the preferred embodiment,
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`the width is from 8 millimeters to 18 millimeters.
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`alternative embodiment of the invention is shown in which
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`Referring to Figures 13 and 14, another
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`the implant 200 comprises a rectangular hollow member
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`having a slightly tapered forward section 202.
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`The cross
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`section,
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`shown in Figure 14, shows the rectangular
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`configuration of the implant.
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`In use of the implant the interior of the implant
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`is filled with a paste made of autogenous bone, and
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`inserted in the place of the former disc.
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`The strength of
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`the material used to make the implant is such that, even
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`though it is substantially hollow, it does have sufficient
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`strength to withstand the