United States Patent (19)
`Michelson
`
`(54) LORDOTIC INTERBODY SPINAL FUSION
`MPLANTS
`
`76 Inventor: Gary K. Michelson, 438 Sherman
`Canal, Venice, Calif. 90291
`
`I63
`
`21 Appl. No.: 482,146
`22 Filed:
`Jun. 7, 1995
`Related U.S. Application Data
`Continuation-in-part of Ser. No. 263,952, Jun. 22, 1994,
`abandoned, which is a continuation of Ser. No. 52,211, Apr.
`22, 1993, abandoned, which is a continuation of Ser. No.
`546,849, Jul. 2, 1990, abandoned, which is a continuation of
`Ser. No. 212,480, Jun. 28, 1988, abandoned.
`(51) Int. Cl." ................................................ A61F 2/44
`52 U.S. Cl. ....................
`... 623/17; 606/61
`58 Field of Search ................................. 623/17; 606/60,
`606/61
`
`56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,867,728 2/1975 Stubstad et al. .......................... 623/17
`4,501,269 2/1985 Bagby ....................................... 606/61
`4,834,757 5/1989 Brantigan .................................. 62.3/7
`5,306,309 4/1994 Wagner et al. ........................... 623/17
`FOREIGN PATENT DOCUMENTS
`5994.19 6/1994 European Pat. Off. ................. 62.3/7
`
`
`
`121
`
`IIIHIIII
`USOO5609635A
`11
`Patent Number:
`5,609,635
`45) Date of Patent:
`Mar 11, 1997
`
`Primary Examiner-Randy O. Shay
`Attorney, Agent, or Firm-Lewis Anten, Esq.; Amedeo
`Ferraro, Esq.
`
`ABSTRACT
`57)
`The present invention is directed to interbody spinal fusion
`implants having a structural configuration that provides for
`the maintaining and creating of the normal anatomic angular
`relationship of two adjacent vertebrae of the spine to main
`tain and create spinal lordosis. The spinal fusion implants of
`the present invention are sized to fit within the disc space
`created by the removal of disc material between two adja
`cent vertebrae and conform wholly or in part to the disc
`space created. The spinal fusion implants of the present
`invention have upper and lower surfaces that form a support
`structure for bearing against the end plates of the adjacent
`vertebrae. The upper and lower surfaces are disposed in a
`converging angular relationship to each other such that the
`implants of the present invention have an overall "wedged
`shape' in an elevational side view. The angular relationship
`of the upper and lower surfaces places and maintains the
`vertebrae adjacent to those surfaces in an angular relation
`ship to each other, creating and maintaining the desired
`lordosis.
`
`51 Claims, 10 Drawing Sheets
`
`136
`
`Exhibit 1036
`LIFE SPINE, INC.
`IPR2022-01602
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`000001
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`

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`U.S. Patent
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`Mar 11, 1997
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`Sheet 1 of 10
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`5,609,635
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`000002
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`U.S. Patent
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`Mar. 11, 1997
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`Sheet 2 of 10
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`U.S. Patent
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`Mar 11, 1997
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`Sheet 3 of 10
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`Mar 11, 1997
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`Mar 11, 1997
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`U.S. Patent
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`Mar 11, 1997
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`Sheet 6 of 10
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`U.S. Patent
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`Mar 11, 1997
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`Sheet 8 of 10
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`U.S. Patent
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`Mar 11, 1997
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`Sheet 9 of 10
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`FIG 31
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`U.S. Patent
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`Mar 11, 1997
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`Sheet 10 of 10
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`5,609,635
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`5,609,635
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`1.
`LORDOTIC INTERBODY SPINAL FUSION
`MPLANTS
`
`BACKGROUND OF THE INVENTION
`
`RELATED APPLICATION
`This application is a continuation in part of U.S. appli
`cation Ser. No. 08/263,952 filed on Jun. 22, 1994, now
`abandoned, which is a continuation of application Ser. No.
`08/052,211 filed on Apr. 22, 1993, now abandoned which is
`a continuation of application Ser. No. 07/546,849, filed on
`Jul. 2, 1990, now abandoned, which is a continuation of
`application Ser. No. 07/212,480 filed on Jun. 28, 1988, now
`abandoned.
`
`FIELD OF THE INVENTION
`The present invention relates generally to interbody spinal
`fusion implants, and in particular to spinal fusion implants
`configured to restore and maintain two adjacent vertebrae of
`the spine in correct anatomical angular relationship.
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`the adjacent vertebrae. In the preferred embodiments, the
`upper and lower surfaces are disposed in a converging
`angular relationship to each other such that the implants of
`the present invention have an overall "wedged-shape' in an
`elevational side view. The angular relationship of the upper
`and lower surfaces places and maintains the vertebrae adja
`cent to those surfaces in an angular relationship to each
`other, creating and maintaining the desired lordosis.
`The implants of the present invention may have surface
`irregularities to increase their surface area, and/or to further
`engage the adjacent vertebrae and to enhance stability. The
`lordotic implants of the present invention may have surface
`irregularities that are uniform in height along the longitudi
`nal axis of the upper and lower vertebrae engaging surfaces,
`or may increase in height from one end of the implant to the
`other. That is, the implant body and the surface formed and
`the projections may be similarly wedged. The outer contour
`of the surface projections may be more or less rectangular
`while the underlying implant may be wedge-shaped; or the
`reverse wherein the underlying implant body is more or less
`rectangular while the contour of the surface projections are
`wedge-shaped from one end of the implant to the other,
`The implants of the present invention have various faces
`which may be curved so as to conform to the shape of the
`vertebral surfaces adjacent to the area of the disc removal.
`Specifically the upper and/or lower surfaces may be convex,
`and/or the front and/or rear surfaces may be convex. The
`surfaces of the implants of the present invention may have
`openings which may or may not pass all the way through
`them, and a central chamber in communication to the Surface
`through holes. The openings may be of random sizes, and/or
`shapes, and/or distributions. The implants themselves may
`be composed of materials, and/or have surface treatments, to
`encourage microscopic bone ingrowth into the implants.
`In the performing of a posterior lumbar interbody fusion,
`it is not possible to replace the removed portions of the disc,
`if a total nuclear discectomy has been performed, with a
`single large implant as the delicate dural sac containing the
`spinal cord, and the nerve roots cover at all times at least
`some portion of the posterior disc space. As set forth in the
`Parent Application, the use of "modular implants' is appro
`priate in such cases. The modular implants being approxi
`mately as long as the depth of the disc material removed, but
`being considerably narrower, such that they can be intro
`duced into the disc space from the posterior aspect to either
`side of the dural sac, and then aligned side to side within the
`disc space so that a number of them each having a length
`consistent with the depth of the disc removed in that area
`would in combination have a width equal to the width of the
`disc material removed.
`The modular implants of the present invention may be
`generally wedge-shaped and may have upper and lower
`surfaces conforming to the contours of the vertebral end
`plates, which contours include but are not limited to being
`relatively flat or convex. As the disc spaces in the lumbar
`spine are generally lordotic, said implants in the preferred
`embodiment would be taller anteriorly, that is at the
`implants insertion end, and less tall posteriorly, that is at the
`implant's trailing end. To introduce an implant that is taller
`at its insertion end than the space available at the posterior
`aspect of the disc space, even when that disc space is
`optimally distracted, is problematic.
`The modular implants of the present invention provide
`two solutions to the problem. In the first embodiment, the
`modular implants may have a reduced size at their insertion
`end, including but not limited to a bullet nose, a convexity,
`
`DESCRIPTION OF THE RELATED ART
`Both the cervical and lumbar areas of the human spine
`are, in a healthy state, lordotic such that they are curved
`convex forward. It is not uncommon that in degenerative
`conditions of the spine that lordosis is lost. This effectively
`shortens the spinal canal which decreases its capacity. Fur
`ther, the absence of lordosis moves the spinal cord anteriorly
`where it may be compressed against the posteriorportions of
`the vertebral bodies and discs. Finally, such a loss of lordosis
`disturbs the overall mechanics of the spine which may cause
`cascading degenerative changes throughout the adjacent
`spinal segments.
`The surgical treatment of those degenerative conditions of
`the spine in which the spinal discs are in various states of
`collapse, and out of lordosis, commonly involves spinal
`fusion. That is the joining together of adjacent vertebrae
`through an area of shared bone. When the shared bone is in
`the area previously occupied by the intervertebral disc that
`is referred to as an interbody fusion. Further history in this
`regard is provided in application Ser. No. 08/263,952
`entitled Artificial Spinal Fusion Implants ("Parent Applica
`tion”) incorporated herein by reference.
`The Parent Application taught the use of artificial spinal
`fusion implants that were capable of being placed between
`adjacent vertebrae, and which implants were capable of
`containing and providing fusion promoting substances
`including bone at the fusion site. These devices were further
`capable of restoring the height of the disc space and of
`supporting the spine, and were self-stabilizing as well as
`being stabilizing to the spinal area where implanted.
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`SUMMARY OF THE INVENTION
`The present invention is directed to interbody spinal
`fusion implants having a structural configuration that pro
`vides for the maintaining and creating of the normal ana
`tomic angular relationship of two adjacent vertebrae of the
`spine to maintain and create spinal lordosis. The spinal
`fusion implants of the present invention are sized to fit
`within the disc space created by the removal of disc material
`between two adjacent vertebrae and conform wholly or in
`part to the disc space created. The spinal fusion implants of
`the present invention have upper and lower surfaces that
`form a support structure for bearing against the end plates of
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`and a chamfer to a smaller front surface. This then provides
`that the implant has an area small enough to be introduced
`into the posterior aspect of the disc space when the disc
`space is adequately distracted and the contour of that spe
`cialized leading portion of the implant is such that it then
`allows for a ramping up of the adjacent vertebrae relative to
`the implant as the implant is advanced forward into the disc
`Space.
`The implants of the present invention provide a second
`solution to this same problem. In the preferred embodiment
`of the modular implant, the implant is again wedge-shaped
`in the side elevational view and is taller at its insertion end
`than at its trailing end. However, the implant incorporates at
`its trailing end a means for engaging insertion instrumenta
`tion such as the box and threaded opening configuration
`disclosed in the Parent Application. Since in the preferred
`embodiment these implants are wedge-shaped in the side
`elevational view when upright but are generally rectangular
`when viewed from the top plan view, these implants are
`therefore designed to be introduced into the disc space on
`their side such that the side walls of the implants are adjacent
`to the end plates of the adjacent vertebrae. The implants have
`a side-to-side dimension that is less than the dimension
`through the insertion end of the implant when upright. It is
`possible to easily insert these implants with them on their
`side and then to use the insertion instrument engaged to the
`implant to rotate the implants ninety degrees into the fully
`upright position, once they have been fully inserted. Once
`inserted, the upper and lower surfaces are adjacent to the
`endplates of the adjacent vertebrae and create and maintain
`the desired angular relationship of the adjacent vertebrae as
`the upper and lower walls are angled with respect to each
`other.
`In an alternative embodiment of the present invention, a
`mechanical implant which may be inserted in a collapsed
`position and which may then be adjusted to increase in
`height so as to provide for the optimal restoration of the
`height of the space between the adjacent vertebrae is dis
`closed. The mechanical implant may be wedge-shaped, and
`have upper and lower surfaces, the contours of which
`generally conform to the contacted areas of the adjacent
`vertebral endplates and which contours may include but are
`not limited to being relatively flat, or convex. Further, the
`mechanical implant may be wedge-shaped or generally
`rectangular, but capable of increasing in both height and the
`extent of wedging when adjusted. This may easily be
`achieved by having one of the two wedge mechanisms
`employed in the example given being larger, or steeper than
`the other. Alternatively, a single wedge may be utilized, and
`if it is desired to achieved increased height at one end of the
`implant while restricting the height at the other, then the end
`of the implant may incorporate a hinge means and the height
`expansion at the other end achieved by drawing a wedge
`member, bar, ball, or other means from the far end toward
`the hinged end so as to drive said upper and lower surfaces
`apart in a wedged fashion.
`In an alternative embodiment of the present invention, an
`implant having a mechanically deployable bone engaging
`means is taught. Such an implant is generally wedge-shaped
`in the side elevational view and has upper and lower surfaces
`generally conforming to the contour of the vertebral end
`plates where contacted by the implant, and which upper and
`lower surfaces may be but are not limited to being either flat
`or convex. The use of such deployable bone engaging means
`are particularly of value in that the largest possible implant
`may be inserted into a disc space and the vertebral engaging
`means, which if fixed to the surface would have blocked the
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`insertion of the implant, may then be deployed after the
`insertion such that the distance from the tip of the upper and
`lower bone engagement means exceeds the height of the
`space available for insertion. Such a feature is of particular
`value when the implant itself is wedge-shaped as the con
`siderable compressive loads across the lumbar spine would
`tend to drive a wedge-shaped implant out of the disc space.
`
`OBJECTS OF THE PRESENT INVENTION
`It is an object of the present invention to provide a spinal
`fusion implant that is easily inserted into the spine, having
`a tapered leading end;
`It is another object of the present invention to provide a
`spinal fusion implant that tapers in height from one end to
`the other consistent with the taper of a normal spinal disc;
`It is yet another object of the present invention to provide
`a spinal fusion implant that is capable of maintaining
`anatomic alignment and lordosis of two adjacent vertebrae
`during the spinal fusion process;
`It is still another object of the present invention to provide
`a spinal fusion implant that is self stabilizing within the
`spine;
`It is yet another object of the present invention to provide
`a spinal fusion implant that is capable of providing stability
`between adjacent vertebrae when inserted;
`It is further another object of the present invention to
`provide a spinal fusion implant that is capable of spacing
`apart and supporting adjacent vertebrae in an angular rela
`tionship during the spinal fusion process;
`It is still further another object of the present invention to
`provide a spinal fusion implant that fits between to adjacent
`vertebrae and preserves the end plants of those vertebrae;
`and
`It is another object of the present invention to provide a
`spinal fusion implant having a shape which conforms to the
`endplates of the adjacent vertebrae; and
`These and other objects of the present invention will
`become apparent from a review of the accompanying draw
`ings and the detailed description of the drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a perspective view of the lordotic interbody
`spinal fusion implant of the present invention with a slidable
`door shown in a partially open position providing access to
`the internal chamber of the implant.
`FIG. 2 is a top plan view of the lordotic interbody spinal
`fusion implant of the present invention.
`FIG. 3 is a left side elevational view of the lordotic
`interbody spinal fusion implant of the present invention.
`FIG. 4 is a right side elevational view of the lordotic
`interbody spinal fusion implant of the present invention.
`FIG. 5 is a front end view of the lordotic interbody spinal
`fusion implant of the present invention showing the slidable
`door in a partially open position.
`FIG. 6 is a rear end view of the lordotic interbody spinal
`fusion implant of the present invention showing the means
`for engaging insertion instrumentation.
`FIG. 7 is an enlarged fragmentary view along line 7 of
`FIG. 2 illustrating the bone engaging surface configuration
`of the lordotic interbody spinal fusion implant of the present
`invention.
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`FIG. 7A is an elevational side view of a segment of the
`spinal column having the lordotic implant of the present
`invention inserted in the disc space at different disc levels
`between adjacent vertebrae to restore and maintain the
`correct anatomical alignment of the adjacent vertebrae.
`FIG. 8 is a top plan view of an alternative embodiment of
`the lordotic interbody spinal fusion implant of the present
`invention.
`FIG. 9 is a left side elevational view of the lordotic
`interbody spinal fusion implant of FIG. 8.
`FIG. 10 is a frontend view of the lordotic interbody spinal
`fusion implant of FIG. 8.
`FIG. 11 is a rear end view of the lordotic interbody spinal
`fusion implant of FIG. 8 showing the means for engaging
`insertion instrumentation.
`FIG. 12 is an enlarged fragmentary view along line 12 of
`FIG. 8 illustrating the surface configuration the lordotic
`interbody spinal fusion implant of the present invention.
`FIG. 13 is a top plan view of an alternative embodiment
`of the lordotic interbody spinal fusion implant of the present
`invention made of a mesh-like material.
`FIG. 14 is a left side elevational view of the lordotic
`interbody spinal fusion implant of FIG. 13.
`FIG. 15 is a frontend view of the lordotic interbody spinal
`fusion implant of FIG. 13.
`FIG. 16 is a rear end view of the lordotic interbody spinal
`fusion implant of FIG. 13 showing the means for engaging
`insertion instrumentation.
`FIG. 17 is an enlarged fragmentary view along line 17 of
`FIG. 13 illustrating the surface configuration of the lordotic
`interbody spinal fusion implant of the present invention.
`FIG. 18 is a perspective view of an alternative embodi
`ment of the lordotic interbody spinal fusion implant of the
`present invention.
`FIG. 19 is a top plan view of the lordotic interbody spinal
`fusion implant of FIG. 18.
`FIG. 20 is a left side elevational view of the lordotic
`interbody spinal fusion implant of FIG. 18.
`FIG. 21 is a rear end view of the lordotic interbody spinal
`fusion implant of FIG. 18.
`FIG.22 is afrontend view of the lordotic interbody spinal
`fusion implant of FIG. 18.
`FIG. 23 is an enlarged fragmentary view along line 23 of
`FIG. 18 illustrating the surface configuration the lordotic
`interbody spinal fusion implant of the present invention.
`FIG. 24 is a top pian view of an alternative embodiment
`of the lordotic interbody spinal fusion implant of the present
`invention.
`FIG. 25 is a left side elevational view of the ordiotic
`interbody spinal fusion implant of FIG. 24.
`FIG. 26 is a rear end view of the lordotic interbody spinal
`fusion implant of FIG. 24.
`FIG.27 is a frontend view of the lordotic interbody spinal
`fusion implant of FIG. 24.
`FIG. 28 is an enlarged fragmentary view along line 28 of
`the lordotic interbody spinal fusion implant of FIG. 24
`illustrating the surface configuration of the lordotic inter
`body spinal fusion implant of the present invention.
`FIG. 29 is a sectional view along lines 29-29 of FIG. 28
`the lordotic interbody spinal fusion implant of the present
`invention.
`FIG. 30 is a side elevational view of a segment of the
`human spinal column shown with an alternative embodi
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`ment of the lordotic spinal fusion implant of the present
`invention that is adjustable and expandable shown in sec
`tional view inserted in the disc space levels to restore and
`maintain the correct anatomical alignment of the adjacent
`vertebrae.
`FIG. 31 is a side cross sectional view of an alternative
`embodiment of the lordotic implant of the present invention
`having movable projections, in the form of spikes 708,
`which are movable from a first position within the implant
`700 to a second position extending to the exterior of the
`implant.
`FIG. 32 is a perspective view of the implant of FIG. 31.
`
`DETALED DESCRIPTION OF THE DRAWINGS
`Referring to FIGS. 1 through 7 the lordotic interbody
`spinal fusion implant of the present invention for use in the
`disc space between two adjacent vertebrae, generally
`referred to by the numeral 100, is shown. The implant 100
`has a generally rectangular configuration, having an upper
`surface 112 and a lower surface 114. In the preferred
`embodiment, the upper and lower surfaces 112 and 114 of
`implant 100 are disposed in a converging angular relation
`ship toward each other such that the implant 100 appears
`"wedge-shaped' from a side elevational view as shown in
`FIGS. 3 and 4. The upper and lower surfaces 112 and 114
`have an interior surface which form a support structure for
`bearing against the endplates of the adjacent vertebrae
`between which the implant 100 is inserted. The angular
`relationship of the upper and lower surfaces 112 and 114
`places and maintains the vertebrae adjacent to those surfaces
`in an angular relationship, creating and maintaining the
`desired lordosis of the spine.
`The upper and lower surfaces 112 and 114 of the implant
`100 may be flat or curved to conform to the shape of the end
`plates of the adjacent vertebrae between which the implant
`100 is inserted. The implant 100 conforms to the shape of the
`nucleus pulposus and a portion of the annulus fibrosus
`removed from the vertebrae. The upper and lower surfaces
`112 and 114 comprise surface roughenings that provide a
`surface suitable for engaging the adjacent vertebrae to
`stabilize the implant 100 within the disc space once surgi
`cally implanted. The surface roughenings of the upper and
`lower surfaces 112 and 114 comprise a surface knurling 121.
`Referring to FIG. 7, an enlarged fragmentary view of the
`surface knurling 121 of the implant 100 is shown as a
`diamond-shaped bone engaging pattern. The implant 100
`may have surface knurling 121 throughout the entire upper
`and lower surfaces 112 and 114, throughout only a portion
`of the upper and lower surfaces 112 and 114, or any
`combination thereof, without departing from the scope of
`the present invention. It is also appreciated that the surface
`knurling 121 may have various configuration other than the
`configuration shown.
`In this embodiment, the implant 100 is hollow and com
`prises a plurality of openings 115 of passing through the
`upper and lower surfaces 112 and 114 and into a central
`hollow chamber 116. The openings 115 provide for bone
`growth to occur from the vertebrae through the openings 115
`to the internal chamber 116. While the openings 115 have
`been shown in the drawings as being circular, it is appreci
`ated that the openings 115 may have any shape, size,
`configuration or distribution suitable for use in a spinal
`implant without departing from the scope of the present
`invention. For example, the openings may have a tear-drop
`configuration as shown in opening 115a in FIGS. 1 and 2.
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`The upper and lower surfaces 112 and 114 of the implant 100
`are supported and spaced apart by a side wall 118, which
`may also comprise a plurality of openings 122.
`The implant 100 has an insertion end 120 and a trailing
`end 130 both of which may be curved or flat. The trailing
`end 130 of the implant may be convex to conform to the
`curvature of the vertebrae and has a means for engaging an
`implant insertion instrument comprising a depressed portion
`124 with a central threaded opening 126 for receiving the
`engaging end of a driving instrument. The insertion end 120
`of the implant 100 comprises an access opening 132 and a
`slidable door 134 which closes the opening 132. The slidable
`door 134 covers the opening 132 into the chamber 116 and
`permits the insertion of autogenous bone material into the
`chamber 116.
`In use, the slidable door 134 is placed in the open position
`for loading material into the chamber 116. The slideable
`door 134 has a depression 136 for facilitating the opening
`and closing of the door 134. The internal chamber 116 can
`be filled and hold any natural or artificial osteoconductive,
`osteoinductive, osteogenic, or other fusion enhancing mate
`rial. Some examples of such materials are bone harvested
`from the patient, or bone growth inducing material such as,
`but not limited to, hydroxyapatite, hydroxyapatite tricalcium
`phosphate; or bone morphogenic protein. The implant 100
`itself is made of material appropriate for human implanta
`tion such as titanium and/or may be made of, and/or filled
`and/or coated with a bone ingrowth inducing material such
`as, but not limited to, hydroxyapatite or hydroxyapatite
`tricalcium phosphate or any other osteoconductive, osteoin
`ductive, osteogenic, or other fusion enhancing material.
`The fusion enhancing material that is packed within the
`chamber 116 of the implant 10 serves to promote bone
`ingrowth between the implant 100 and the adjacent verte
`brae. Once the bone ingrowth occurs, the implant 100 will
`be a permanent fixture preventing dislodgement of the
`implant as well as preventing any movement between the
`adjacent vertebrae.
`The slidable door 134 is then closed prior to implantation.
`In the closed position, the slideable door conforms to the
`curvature of the insertion end 120 of the implant 100.
`Various methods of packing the implant 100 with the
`autogenous bone material may be used to obtain a com
`pletely packed implant 100.
`45
`The method of inserting the implant 100 is set forth in
`detail in application Ser. No. 08/263,952, incorporated
`herein by reference. The threaded end of a driving instru
`ment is attached to the threaded opening 126 in the trailing
`end 120 of the implant 100 and the fitting of the driving
`50
`instrument into the depressed portion 124 prevents move
`ment of the implant 100 in relationship to the driving
`instrument. The implant 100 is then placed at the entrance to
`the disc space between the two adjacent vertebrae V. The
`driver instrument is then tapped with a hammer sufficiently
`hard enough to drive the implant 100 into the disc space.
`The size of the implant 100 is substantially the same size
`as the disc material that it is replacing and thus will be larger
`or smaller depending on the amount of disc material
`removed to create the disc space in which it is to be used. In
`the preferred embodiment in regard to the lumbar spine the
`implant 100 is approximately 28–48 mm wide, approxi
`mately 36mm being preferred. The implant 100 has a height
`conforming to the restoration of the anatomic height of the
`disc space the average height would range from 8-16 mm,
`with 10-12 of which being the preferred average height. The
`depth would at its maximum range from 20 to 34 mm with
`
`65
`
`30
`
`35
`
`55
`
`60
`
`5,609,635
`
`10
`
`15
`
`20
`
`25
`
`8
`26 to 32 being the preferred maximum depth. In the cervical
`spine the width of the implant is in the range of approxi
`mately 14-28 mm, with the preferred width being 18-22
`mm. The implant has a height in the range of approximately
`5-10 mm with the preferred height being 6-8 mm. The
`implant has a depth in the range of approximately 11-21 mm
`with the preferred depth being 11-13 mm.
`Referring to FIG. 7A, a side elevational view of the lateral
`aspect of a segment of the spinal column S is shown with the
`implant 100 inserted in the disc space D between two
`adjacent vertebrae V, and V. The implant 100 is inserted in
`the direction of arrow Ainto the disc space D and maintains
`the two vertebrae V and V in angular relationship to each
`other such that the natural lordosis of that segment of the
`spinal column S is restored. The forward advancement of the
`implant 100 is blocked by the natural bone processes B in
`the endplates of the vertebrae V and V. Backing out of the
`implant 100 is prevented by the bone engaging surface
`knurling 121 of the upper and lower surfaces 112 and 114.
`Referring to FIGS. 8-12, an alternative embodiment of
`the lordotic interbody spinal fusion implant of the present
`invention, generally referred to by the numeral 200, is
`shown. The implant 200 has a similar overall configuration
`as the implant 100 described above. In the preferred embodi
`ment, the implant 200 is solid and comprises a plurality of
`channels 215 passing from the upper surface 212 to the
`lower surface 214 through the implant 200. The channels
`215 provide for bone ingrowth and facilitate the incorpora
`tion of the implant 200 into the spinal fusion mass. The
`channels may also be loaded with fusion promoting mate
`rials such as those described above, prior to implantation. It
`is appreciated that the channels 215 need not pass all the way
`through the implant 200, but can have a configuration
`similar to wells, which may hold fusion promoting materials
`and permit bone ingrowth into the upper and lower surfaces
`212 and 214 of the implant 200.
`In addition to the channels 215, the implant 200 may have
`small openings 222 on the side wall 218 which may or may
`not pass through the entire implant200. The same openings
`222 may be in communication with the channels 215 such
`that bone ingrowth may occur from the openings 222 to the
`channels 215 to lock the implant 200 into the fusion mass.
`If the openings 222 do not pass through the entire implant
`200, the may function as small wells for holding fusion
`promoting materials or described above.
`In the preferred embodiment of implant 200, the channels
`215 have a diameter in the range of 0.1 mm to 6 mm, with
`2-3 mm being the preferred diameter. The openings 222
`have a diameter in the range of 0.1 mm to 6 mm, with 1-3
`mm being the preferred diameterrange. It is appreciated that
`although the channels 215 and openings 222 are shown
`having a generally rounded configuration, it is within the
`scope of the present invention that the channels 215 and
`openings 222 may have any size, shape, configuration, and
`distribution suitable for the intended purpose.
`The implant 200, has a plurality of ratchetings 250 on the
`upper and lower surface 212 and 214 for engaging the bone
`of the adjacent vertebrae. The ratchetings 250 comprise a
`bone engaging edge 252 and angled segment 254.
`Referring specifically to FIG. 9, the implant 200 has a
`wedge-shaped elevational side view in which the trailing
`end 230 is taller than the insertion end 220. The plurality of
`ratchetings 250 are oriented in the direction of the insertion
`end 220 to provide for a one-way insertion of the implant
`200 as the bone engaging edge 252 engages the vertebrae
`and prevents the implant from backing out once implanted.
`
`000015
`
`

`

`20
`
`25
`
`Alternatively, the trailing end ratchetings could be of a lessor
`height such that the overall shape of the ratchetings as a
`group is convex.
`Referring to FIG. 11, the trailing end 230 of implant 200
`has means for engaging insertion instrumentation compris
`ing a thread opening 226 as described above for impla