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`I50
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`100
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`300
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`500
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`0
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`50
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`150
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`250
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`0
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`I30
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`I60
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`600
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`0
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`65
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`80
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`300
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`Te'°P“°"e (858)243-0029
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`Name (Pn'ntlTvpe) Jonathan -.-. glerA Date March 29,2005
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`NON-PROVISIONAL APPLICATION
`
`FOR UNITED STATES LETTERS PATENT
`
`SYSTEMS AND METHODS FOR SPINAL FUSION
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`By Inventors:
`
`MATTHEW CURRAN, a citizen of the United States
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`Residing in San Diego, California
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`MARK PETERSON, a citizen of the United States
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`Residing in Medford, Oregon
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`20
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`Filed:
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`March 29, 2005
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`3
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`SYSTEMS AND METHODS FOR SPINAL FUSION
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`CROSS-REFERENCE TO RELATED APPLICATION
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`This application claims the benefit of the filing date under 35 USC 1l9(e) of United
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`5
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`States Provisional Application entitled “Systems and Methods for Spinal Fusion,” serial No.
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`60/557,536 filed March 29, 2004, the entire contents of which are incorporated herein by
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`reference.
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`BACKGROUND OF THE INVENTION
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`10
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`1. Field of the Invention
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`The present invention relates generally to spinal surgery and, more particularly, to a
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`system and method for spinal fusion comprising a spinal fusion implant of non-bone construction
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`releasably coupled to an insertion instrument dimensioned to introduce the spinal fusion implant
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`into any of a variety of spinal target sites.
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`15
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`II. Discussion of the Prior Art
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`Currently there are nearly 500,000 spine lumbar and cervical fusion procedures
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`performed each year in the United States. Such procedures are commonly performed to correct
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`problems, such as chronic back or neck pain, which result from degenerated intervertebral discs
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`20
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`or trauma. Generally, spinal fusion procedures involve removing some or all of the diseased or
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`damaged disc, and inserting one or more intervertebral implants into the resulting disc space.
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`Introducing the intervertebral implant serves to restore the height between adjacent vertebrae
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`4
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`(“disc height”), which reduces if not eliminates neural impingement commonly associated with a
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`damaged or diseased disc.
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`Autologous bone grafts are widely used intervertebral implant for lumbar fusion.
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`Autologous bone grafts are obtained by harvesting a section of bone from the iliac crest of the
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`patient and thereafter implanting the article of autologous bone graft to effect fusion. While
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`generally effective, the use of autologous bone grafts suffers certain drawbacks. A primary
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`drawback is the morbidity associated with harvesting the autologous graft from the patient’s iliac
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`crest. Another related drawback is the added surgical time required to perform the bone-
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`10
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`harvesting.
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`Allograft bone grafts have been employed with increased regularity in an effort to
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`overcome the drawbacks of autologous bone grafts. Allograft bone grafts are harvested from
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`cadaveric specimens, machined, and sterilized for implantation. While allograft bone grafts
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`15
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`eliminate the morbidity associated with iliac crest bone harvesting, as well as decrease the overall
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`surgical time, they still suffer certain drawbacks. A primary drawback is supply constraint, in
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`that the tissue banks that process and produce allograft bone implants find it difficult to forecast
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`allograft given the inherent challenges in forecasting the receipt of cadavers. Another related
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`drawback is that it is difficult to manufacture the allograft with consistent shape and strength
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`20
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`characteristics given the variation from cadaver to cadaver.
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`The present invention is directed at overcoming, or at least improving upon, the
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`disadvantages of the prior art.
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`5
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`SUMMARY OF THE INVENTION
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`The present invention overcomes the drawbacks of the prior art by providing a spinal
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`fusion system and related methods involving the use of a spinal fusion implant of non-bone
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`construction. The non-bone construction of the spinal fusion implant of the present invention
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`overcomes the drawbacks of the prior art in that it is not supply limited (as with allograft) and
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`does not require harvesting bone from the patient (as with autograft). The spinal fusion implant
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`of the present invention may be comprised of any suitable non-bone composition, including but
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`not limited to polymer compositions (e.g. poly-ether-ether-ketone (PEEK) and/or po1y-ether-
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`ketone-ketone (PEKK)), ceramic, metal or any combination of these materials.
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`The spinal fusion implant of the present invention may be provided in any number of
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`suitable shapes and sizes depending upon the particular surgical procedure or need. The spinal
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`fusion implant of the present invention may be dimensioned for use in the cervical and/or lumbar
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`spine without departing from the scope of the present invention. For lumbar fusion, the spinal
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`fusion implant of the present invention may be dimensioned, by way of example only, having a
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`width ranging between 9 and 18 mm, a height ranging between 8 and 16 mm, and a length
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`10
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`15
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`ranging between 25 and 45 mm. For cervical fusion, the spinal fusion implant of the present
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`20
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`invention may be dimensioned, by way of example only, having a width about 11 mm, a height
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`ranging between 5 and 12 mm, and a length about 14 mm.
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`6
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`The spinal fusion implant of the present invention may be provided with any number of
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`additional features for promoting fusion, such as apertures extending between the upper and
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`lower vertebral bodies which allow a boney bridge to form through the spinal fusion implant of
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`the present invention. Such fusion-promoting apertures may be dimensioned to receive any
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`number of suitable osteoinductive agents, including but not limited to bone morphogenic protein
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`(BMP) and bio-resorbable polymers, including but not limited to any of a variety of poly (D,L-
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`lactide-co-glycolide) based polymers. The spinal fusion implant of the present invention is
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`preferably equipped with one or more lateral openings which aid it provides in visualization at
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`the time of implantation and at subsequent clinical evaluations.
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`10
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`15
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`The spinal fusion implant of the present invention may be provided with any number of
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`suitable anti-migration features to prevent spinal fusion implant from migrating or moving from
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`the disc space after implantation. Suitable anti-migration features may include, but are not
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`necessarily limited to, angled teeth formed along the upper and/or lower surfaces of the spinal
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`fusion implant and/or spike elements disposed partially within and partially outside the upper
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`and/or lower surfaces of the spinal fusion implant. Such anti-migration features provide the
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`additional benefit of increasing the overall surface area between the spinal fusion implant of the
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`present invention and the adjacent vertebrae, which promotes overall bone fusion rates.
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`The spinal fusion implant of the present invention may be provided with any number of
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`features for enhancing the visualization of the implant during and/or after implantation into a
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`spinal target site. According to one aspect of the present invention, such visualization
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`enhancement features may take the form of the spike elements used for anti-migration, which
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`may be manufactured from any of a variety of suitable materials, including but not limited to a
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`metal, ceramic, and/or polymer material, preferably having radiopaque characteristics. The spike
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`elements may also take any of a variety of suitable shapes, including but not limited to a
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`generally elongated element disposed within the implant such that the ends thereof extend
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`generally perpendicularly from the upper and/or lower surfaces of the implant. The spike
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`elements may each comprise a unitary element extending through upper and lower surfaces or,
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`alternatively, each spike element may comprise a shorter element which only extends through a
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`single surface (that is, does not extend through the entire height of the implant). In any event,
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`when the spike elements are provided having radiodense characteristics and the implant is
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`10
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`manufactured from a radiolucent material (such as, by way of example only, PEEK and/or
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`PEKK), the spike elements will be readily observable under X-ray or fluoroscopy such that a
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`surgeon may track the progress of the implant during implantation and/or the placement of the
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`implant after implantation.
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`15
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`The spinal implant of the present invention may be introduced into a spinal target site
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`through the use of any of a variety of suitable instruments having the capability to releasably
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`engage the spinal implant. In a preferred embodiment, the insertion instrument permits quick,
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`direct, accurate placement of the spinal implant of the present invention into the intervertebral
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`space. According to one embodiment, the insertion instrument includes a threaded engagement
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`20
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`element dimensioned to threadably engage into a receiving aperture formed in the spinal fusion
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`implant of the present invention. According to another embodiment, the insertion instrument
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`includes an elongate fork member and a generally tubular lock member.
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`8
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`Many advantages of the present invention will be apparent to those skilled in the art with
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`a reading of this specification in conjunction with the attached drawings, wherein like reference
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`numerals are applied to like elements and wherein:
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`Figure 1 is a perspective view of a spinal fusion system of the present invention,
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`including a lumbar fusion implant releasably coupled to an insertion instrument according to one
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`embodiment of the present invention;
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`10
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`Figure 2 is a perspective view of the lumbar fusion implant of FIG. 1, illustrating (among
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`other things) fusion apertures extending between top and bottom surfaces, a plurality of
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`visualization apertures extending through the side walls, and a variety of anti-migration features
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`according to one embodiment of the present invention;
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`15
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`Figure 3 is a top view of the lumbar fusion implant of FIG. 1, illustrating (among other
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`things) the fusion apertures and the anti-migration features according to one embodiment of the
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`present invention;
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`Figure 4 is a side view of the lumbar fusion implant of FIG. 1, illustrating (among other
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`20
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`things) the visualization apertures, the anti-migration feature, and a receiving aperture for
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`releasably engaging the insertion instrument of FIG. 1 according to one embodiment of the
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`present invention;
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`9
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`\\
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`Figure 5 is an end view of the lumbar fusion implant of FIG. 1, illustrating (among other
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`things) the receiving aperture formed in the proximal end, the anti-migration features, and the
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`visualization apertures according to one embodiment of the present invention;
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`Figure 6 is an enlarged side view of the lumbar fusion implant of FIG. 1 releasably
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`coupled to the distal end of the insertion instrument of FIG. 1 according to one embodiment of
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`the present invention;
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`Figure 7 is a perspective view of the insertion instrument of FIG. 1 in a fully assembled
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`10
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`form according to one embodiment of the present invention;
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`Figure 8 is an enlarged perspective view of the distal region of the insertion instrument of
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`FIG. 1 according to one embodiment of the present invention;
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`15
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`Figure 9 is a perspective exploded view of the insertion instrument of FIG. 1, illustrating
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`the component parts of the insertion instrument according to one embodiment of the present
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`invention;
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`Figure 10 is a perspective view of a spinal fusion system of the present invention,
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`20
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`including a cervical fusion implant releasably coupled to a cervical insertion instrument
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`according to one embodiment of the present invention;
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`10
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`10
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`Figure 11 is a perspective view of the proximal side of the cervical fusion implant of FIG.
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`10, illustrating (among other things) fusion apertures extending between top and bottom surfaces,
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`a plurality of visualization apertures extending through the lateral walls, a plurality of receiving
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`apertures, and a variety of anti-migration features according to one embodiment of the present
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`invention;
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`Figure 12 is a perspective view of the distal side cervical fusion implant of FIG. 10,
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`illustrating (among other things) the visualization apertures and anti-migration features;
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`10
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`15
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`Figure 13 is a top view of the cervical fusion implant of FIG. 10, illustrating (among
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`other things) the fusion apertures and anti-migration features according to one embodiment of the
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`present invention;
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`Figure 14 is a side view of the cervical fusion implant of FIG. 10, illustrating (among
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`other things) the visualization apertures, the anti-migration features, and one of two receiving
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`apertures provided in the proximal end for releasably engaging the cervical insertion instrument
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`of FIG. 10 according to one embodiment of the present invention;
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`Figure 15 is a perspective view of the cervical fusion implant of the present invention just
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`20
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`prior to attachment to the cervical insertion device according to one embodiment of the present
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`invention;
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`11
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`11
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`Figure 16 is a perspective view of the insertion instrument of FIG. 10 in a fully assembled
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`form according to one embodiment of the present invention;
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`Figure 17 is a perspective exploded view of the insertion instrument of FIG. 10,
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`illustrating the component parts of the insertion instrument according to one embodiment of the
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`present invention;
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`Figures 18 and 19 are perspective and side views, respectively, illustrating the “enhanced
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`visua1ization” feature of the present invention as employed within a lumbar fusion implant
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`10
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`according to one embodiment of the present invention;
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`15
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`20
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`Figures 20 and 21 are perspective and side views, respectively, illustrating the “enhanced
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`visualization” feature of the present invention as employed within a lumbar fusion implant
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`according to one embodiment of the present invention; and
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`Figures 22 and 23 are perspective and side views, respectively, illustrating the “enhanced
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`visualization” feature of the present invention as employed within a cervical fusion implant
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`according to one embodiment of the present invention.
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`DESCRIPTION OF THE PREFERRED EMBODIMENTS
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`lllustrative embodiments of the invention are described below. In the interest of clarity,
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`not all features of an actual implementation are described in this specification. It will of course
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`be appreciated that in the development of any such actual embodiment, numerous
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`10
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`12
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`12
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`implementation-specific decisions must be made to achieve the developers’ specific goals, such
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`as compliance with system-related and business—related constraints, which will vary from one
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`implementation to another. Moreover, it will be appreciated that such a development effort
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`might be complex and time-consurning, but would nevertheless be a routine undertaking for
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`those of ordinary skill in the art having the benefit of this disclosure. The system to facilitate
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`bone fusion and related methods disclosed herein boasts a variety of inventive features and
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`components that warrant patent protection, both individually and in combination.
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`FIG. 1 illustrates, by way of example only, a spinal fusion system 5 for performing spinal
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`10
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`15
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`fusion between adjacent lumbar vertebrae, including an exemplary spinal fusion implant 10 and
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`an exemplary insertion instrument 20 provided in accordance with the present invention. The
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`spinal fusion implant 10 may be comprised of any suitable non-bone composition having suitable
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`radiolucent characteristics, including but not limited to polymer compositions (e.g. poly-ether-
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`ether—ketone (PEEK) and/or poly-ether-ketone-ketone (PEKK)) or any combination of PEEK and
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`PEKK. The spinal fusion implant 10 of the present invention may be dimensioned, by way of
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`example only, having a width ranging between 9 and 18 mm, a height ranging between 8 and 16
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`mm, and a length ranging between 25 and 45 mm.
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`As will be described in detail below, the insertion instrument 20 is configured to
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`20
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`releasably maintain the exemplary spinal fusion implant 10 in the proper orientation during
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`insertion into a lumbar disc space and thereafter released to deposit the implant 10. The
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`exemplary spinal fusion implant 10, having been deposited in the disc space, facilitates spinal
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`fusion over time by maintaining a restored disc height as natural bone growth occurs through
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`11
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`13
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`13
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`and/or past the implant 10, resulting in the formation of a boney bridge extending between the
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`adjacent vertebral bodies. The implant 10 is particularly suited for introduction into the disc
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`space via a lateral (trans-psoas) approach to the spine, but may be introduced in any of a variety
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`of approaches, such as posterior, anterior, antero-lateral, and postero-lateral, without departing
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`from the scope of the present invention (depending upon the sizing of the implant 10).
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`The spinal fusion implant 10 of the present invention may be provided with any number
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`of additional features for promoting fusion, such as apertures 2 extending between the upper and
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`lower vertebral bodies which allow a boney bridge to form through the spinal fusion implant 10.
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`According to a still further aspect of the present invention, this fusion may be facilitated or
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`augmented by introducing or positioning various osteoinductive materials within the apertures 2
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`and/or adjacent to the spinal fusion implant 10. Such osteoinductive materials may be introduced
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`before, during, or after the insertion of the exemplary spinal fusion implant 10, and may include
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`(but are not necessarily limited to) autologous bone harvested from the patient receiving the
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`spinal fusion implant 10, bone allograft, bone xenograft, any number of non-bone implants (e.g.
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`ceramic, metallic, polymer), bone morphogenic protein, and bio-resorbable compositions,
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`including but not limited to any of a variety of poly (D,L-lactide-co-glycolide) based polymers.
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`10
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`15
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`The spinal fusion implant 10 of the present invention is preferably equipped with one or
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`20
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`more visualization apertures 4 situated along the lateral sides, which aid in visualization at the
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`time of implantation and at subsequent clinical evaluations. More specifically, based on the
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`generally radiolucent nature of the implant 10, the visualization apertures 4 provide the ability to
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`visualize the interior of the implant 10 during X-ray and/or other suitable imaging techniques
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`12
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`14
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`14
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`which are undertaken from the side (or “lateral”) perspective of the implant 10. If fusion has
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`taken place, the visualization apertures 4 will provide a method for the surgeon to make follow
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`up assessments as to the degree of fusion without any visual interference from the spinal fusion
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`implant 10. Further, the visualization apertures 4 will provide an avenue for cellular migration to
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`the exterior of the spinal fusion implant 10. Thus the spinal fusion implant 10 will serve as
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`additional scaffolding for bone fusion on the exterior of the spinal fusion implant 10.
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`10
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`15
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`20
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`FIGS. 2-5 depict various embodiments of the exemplary spinal fusion implant 10. Some
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`common attributes are shared among the various embodiments. More specifically, each spinal
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`fusion implant 10 has a top surface 31, a bottom surface 33, lateral sides 14, a proximal side 22,
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`and a distal side 16.
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`In one embodiment, the top and bottom surfaces 31, 33 are generally
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`parallel. It can be appreciated by one skilled in the art that although the surfaces 31, 33 are
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`generally parallel to one another, they may be provided in any number of suitable shapes,
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`including but not limited to concave and/or convex. When provided as convex shapes, the top
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`and bottom surfaces 31, 33 may-better match the natural contours of the vertebral end plates.
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`Although not shown, it will be appreciated that the top and bottom surfaces 31, 33 may be angled
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`relative to one another to better match the natural lordosis of the lumbar and cervical spine or the
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`natural kyphosis of the thoracic spine.
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`The exemplary spinal fusion implant 10 also preferably includes anti-migration features
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`designed to increase the friction between the spinal fusion implant 10 and the adjacent contacting
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`surfaces of the vertebral bodies so as to prohibit migration of the spinal fusion implant 10 after
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`implantation. Such anti-rnigration features may include ridges 6 provided along the top surface
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`13
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`15
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`15
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`31 and/or bottom surface 33. Additional anti-migration features may also include a pair of spike
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`elements 7 disposed within the proximal region of the implant 10, a pair of spike elements 8
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`disposed within the distal region of the implant 10, and a pair of spike elements 9 disposed
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`within the central region of the implant 10. Spike elements 7, 8, 9 may extend from the top
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`surface 31 and/or bottom surface 33 within the respective proximal, distal and central regions of
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`the implant 10. The spike elements 7, 8, 9 may be manufactured from any of a variety of suitable
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`materials, including but not limited to a metal, ceramic, and/or polymer material, preferably
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`having radiopaque characteristics. The spike elements 7, 8, 9 may also take any of a variety of
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`suitable shapes, including but not limited to a generally elongated element disposed within the
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`implant 10 such that the ends thereof extend generally perpendicularly from the upper and/or
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`lower surfaces 31, 33 of the implant 10. As best appreciated in FIG. 4, the spike elements 7, 8, 9
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`may each comprise a unitary element extending through upper and lower surfaces 31, 33.
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`Alternatively, each spike element 7, 8, 9 may comprise a shorter element which only extends
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`through a single surface 31, 33 (that is, does not extend through the entire height of the implant
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`10). In any event, when the spike elements 7, 8, 9 are provided having radiodense characteristics
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`and the implant 10 is manufactured from a radiolucent material (such as, by way of example
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`only, PEEK and/or PEKK), the spike elements 7, 8, 9 will be readily observable under X-ray or
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`fluoroscopy such that a surgeon may track the progress of the implant 10 during implantation
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`and/or the placement of the implant 10 after implantation.
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`10
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`15
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`20
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`The spinal fusion implant 10 has two large fusion apertures 2, separated by a medial
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`support 50, extending in a vertical fashion through the top surface 31 and bottom surface 33.
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`The fusion apertures 2 function primarily as an avenue for bony fusion between adjacent
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`l4
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`l6
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`16
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`vertebrae. The fusion apertures 2 may be provided in any of a variety of suitable shapes,
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`including but not limited to the generally rectangular shape best viewed in FIG. 3, or a generally
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`circular, oblong and/or triangular shape or any combination thereof. The spinal fusion implant
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`10 may have a plurality of visualization apertures 4 which allow a clinician to make visual
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`observations of the degree of bony fusion un-obscured by the lateral side 14 to facilitate further
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`diagnosis and treatment. The visualization apertures 4 may be provided in any of a variety of
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`suitable shapes, including but not limited to the generally oblong shape best viewed in FIG. 4, or
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`a generally circular, rectangular and/or triangular shape or any combination thereof.
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`10
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`15
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`The spinal fusion implant 10 may be provided with any number of suitable features for
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`engaging the insertion instrument 20 without departing from the scope of the present invention.
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`As best viewed in FIGS. 4-6, one engagement mechanism involves providing a threaded
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`receiving aperture 12 in the proximal sidewall 22 of the spinal fusion implant 10 of the present
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`invention. The threaded receiving aperture 12 is dimensioned to threadably receive a threaded
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`connector 24 on the insertion instrument 20 (as will be described in greater detail below). The
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`receiving aperture 12 extends inwardly from the proximal side 22 in a generally perpendicular
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`fashion relative to the proximal side 22. Although shown as having a generally circular cross-
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`section, it will be appreciated that the receiving aperture 12 may be provided having any number
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`of suitable shapes or cross-sections, including but not 1in1ited to rectangular or triangular. In
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`20
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`addition to the receiving aperture 12, the spinal fusion implant 10 is preferably equipped with a
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`pair of grooved purchase regions 60, 61 extending generally horizontally from either side of the
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`receiving aperture 12. The grooved purchase regions 60, 61 are dimensioned to receive
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`corresponding distal head ridges 62, 63 on the insertion instrument 20 (as will be described in
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`15
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`17
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`17
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`greater detail below), which collectively provide an enhanced engagement between the implant
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`10 and instrument 20.
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`FIGS. 6-9 detail the exemplary insertion instrument 20 according to one embodiment of
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`the invention. The exemplary insertion instrument 20 includes an elongate tubular element 28
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`and an inserter shaft 44. The elongate tubular element 28 is constructed with a distal head 26 at
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`its