`
`WORLD INTELLECTUAL PROPE
`International Bi
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER
`«
`.
`.
`Pp.
`wo
`(51) International
`Patent Classification
`(11) In
`«og:
`.
`A61B 17/70
`(43) International Publication Date:
`
`6 :
`
`9608205A1
`21 March 1996 (21.03.96)
`
`(22) International Filing Date:
`
`8 September 1995 (08.09.95)
`
`cage (20) is introduced through an anterior procedure and ma.i.tains or increases the lordosis between adjacent vertebral bone structures.
`
`A fusion cage (20) for anterior vertebral body fusion is conically shaped and includes a rounded distal end (24). A thread (40) is
`formed as part of the external conical surface of the fusion cage (20). The thread (40) defines one or more flutes (52) which enhance the
`ability of the fusion cage (20) to be self-tapping. Apertures (54, 206, 322) are defined through the fusion cage in order to provide for
`contact between the engaged vertebral bone structures and bone growth inducing substances packed within the fusion cage. The fusion
`
`(21) International Application Number:
`PCT/US95/11281|(81) Designated States: AM, AT, AU, BB, BG, BR, BY, CA, CH,
`CN, CZ, DE, DK, EE, ES, FI, GB, GE, HU, IS, JP, KE,
`KG, KP, KR, KZ, LK, LR, LT, LU, LV, MD, MG, MK,
`MN, MW,MX, NO, NZ, PL, PT, RO, RU,SD, SE, SG,SI,
`SK, TJ, TM, TT, UA, UG, UZ, VN, European patent (AT,
`BE, CH, DE, DK, ES, FR, GB, GR, IF, IT, LU, MC, NL,
`PT, SE), OAPI patent (BF, BJ, CF, CG, CI, CM, GA, GN,
`ML, MR, NE, SN, TD, TG), ARIPO patent (KE, MW, SD,
`SZ, UG).
`
`(30) Priority Data:
`08/306,879
`
`1S September 1994 (15.09.94)
`
`US
`
`INC. [US/US]; 2575
`(71) Applicant: SURGICAL DYNAMICS,
`Stanwell Drive, Concord, CA 94520 (US).
`
`(72) Inventors: PAVLOV, M., D., Paul, W.; Sint Maartenskliniek,
`Orthopedic, Hengstdal 3, NL-6522 JV Nijmegan (NL).
`WINSLOW,Charles, J.; 25 Hilton Court, Walnut Creek, CA
`94595 (US). JAYNE,Kirk; 785 Pacific Avenue, Alameda,
`CA 94501 (US). KLYCE, Henry, A.; 231 Sandringham
`Road, Piedmont, CA 94611 (US).
`
`(74) Agent: MEYER, Sheldon, R.; Fliesler, Dubb, Meyer and Love-
`joy, Suite 400, Four Embarcadero Center, San Francisco,
`CA 94111-4156 (US).
`
`Published
`With international search report.
`
`(54) Title: CONICALLY-SHAPED ANTERIOR FUSION CAGE AND METHOD OF IMPLANTATION
`
`(57) Abstract
`
`
`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international
`applications under the PCT.
`
`Viet Nam
`
`United Kingdom
`Georgia
`Guinea
`Greece
`Hungary
`Ireland
`laly
`Japan
`Kenya
`Kyrgystan
`Democratic People's Republic
`of Korea
`Republic of Korea
`Kazakhstan
`Liechtenstein
`Sri Lanka
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`Mali
`Mongolia
`
`Austria
`Australia
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`Cé&e dIvoire
`Cameroon
`China
`Czechoslovakia
`Czech Republic
`Germany
`Denmark
`Spain
`Finland
`France
`Gabon
`
`
`
`~&SASERERGBARNS
`
`Mauritania
`Malawi
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Slovenia
`Slovakia
`Senegal
`Chad
`Togo
`Tajikistan
`Trinidad and Tobago
`Ukraine
`United States of America
`Uzbekistan
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-l1-
`
`CONICALLY-SHAPED ANTERIOR FUSION CAGE
`
`AND METHOD OF IMPLANTATION
`
`BACKGROUND
`
`Field of the Invention
`
`The present
`
`invention is directed to devices and methods for
`
`facilitating the fusing of bone structures and more particularly the fusing
`
`together of adjacent vertebral bodies or bone structures.
`
`10
`
`Background of the Invention
`
`Technica! literature and patent documents disclose a number of
`
`devices and methods for fusing bones together. One such device which
`
`has proven to be successful is disclosed in U.S. Patent 4,961,740, entitled
`
`"V-THREAD FUSION CAGE AND METHOD OF FUSING A BONE JOINT,”
`
`which patent has been assigned the present assignee and which patentis
`
`incorporated herein by reference. The referenced patent discloses a fusion
`
`cage which is preferably cylindrical and has a thread formed as part of the
`
`external cylindrical surface. The fusion cage defines an internal cavity and
`
`apertures through the wall of the cage which communicate the external
`
`cylindrical surface with the internal cavity. The apertures are formed in
`
`the valleys of the thread. Normally two such cages are used to stabilized
`
`and fuse together adjacent vertebral bodies or bone structures.
`
`in practice, using a posterior approach, a patient’s vertebral bone
`
`structures are exposed and degenerate disk material located between the
`
`vertebral bone structures is removed. A threaded tap is used to tap a
`
`complementary thread in the upper and lower vertebral bone structures
`
`preparatory to the insertion of the above fusion cage. Once such tapping
`
`has been accomplished, using an introd':ction tool, the fusion cage is
`
`screwed into the space between the adjacent vertebral bone structures.
`
`The thread bites into the bone of the upper and lower vertebral bone
`
`structures, stabilizing the bone structures, and preventing the fusion cage
`
`from working out of this position due to patient movement. Generally two
`
`15
`
`20
`
`25
`
`30
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-2-
`
`such fusion cagesare applied using this technique. Once the two implants
`
`have been positioned, then bone growth inducing substances, such as
`
`bone chips, are packed into the internal cavity of the fusion cages. These
`
`bone growth inducing substances come into immediate contact with the
`
`bone from the vertebral bone structures which project into the internal
`
`cavity through the apertures. Such projection of bone is due to the fact
`
`that the apertures are formed in the valleys of the external thread of the
`
`fusion cage. Such immediate bone to bone contact between the vertebral
`
`bone structures and the bone pack within the fusion cages results in more
`
`rapid propagation of bone cells between the adjacent vertebral bone
`
`structures and thus a more rapid fusion of the adjacent vertebral bone
`
`structures.
`
`Summary of the Invention
`
`The present invention is directed to a fusion cage which has been
`
`designed to be implanted using an anterior approach to the vertebral bone
`
`structures.
`
`In a first embodiment of the present invention, the fusion cage
`includes a conically-shaped cage body having a proximal end and a distal
`
`end, said distal end having a diameter which is smaller than the diameter
`
`of the proximal end. The distal end further is rounded with for example
`a bull nose in order to facilitate the insertion of the cage body relative to
`
`The conically-shaped cage body is
`one or more bone structures.
`particularly advantageous for use with an anterior approach to vertebra!
`bone structure fusion. This is due to the fact that the norma! lordosis of
`
`the vertebral bone structures defines a wedged-shape spacefor a vertebral
`disk between, for example, lumbar vertebrae. Accordingly, the conically-
`shaped body cage can be sized and selected in order to maintain or
`
`enlarge upon the normal lordosis.
`
`In a second embodiment of the present invention, a fusion cage
`includes a conically-shaped cage body having a proximal end and a distal
`
`end with the distal end having a diameter which is smaller than the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-3-
`
`diameter of the proximal end. The conically-shaped cage body has a
`
`conically-shaped outer surface and at
`
`least one flute formed in the
`
`conicaily-shaped outer surface. The flute acts as a relief much as the flute
`
`placed on self-tapping screws in order to facilitate the insertion of the
`
`fusion cage using a
`
`twisting motion between two vertebral bone
`
`structures.
`
`in a third embodiment of the invention, a fusion cage includes a
`
`conically-shaped cage body having a proximal end and a distal end, the
`
`distal end having a diameter which is smaller than the diameter of the
`
`10
`
`proximal end. The conically-shaped cage body has a conically-shaped
`
`outer surface and a thread formed as part of the conically-shaped outer
`
`surface. The thread allows the cage body to be inserted using an anterior
`
`approach. Due to the fact that the cage body is conically-shaped, the
`
`requirement for pretapping the vertebral bone structures to receive the
`
`is
`
`fusion cage is eliminated with the fusion cage being self-tapping. Also the
`
`20
`
`25
`
`cage gradually spreads apart the vertebral bone structures as the cage is
`
`inserted in order to regain or enlarge the natural lordosis of the adjacent
`
`vertebral bone structures. As with other embodiments of the present
`
`invention, flutes can be provided through the thread in order to allow for
`
`enhanced thread tapping by the cage and for a smoother insertion of the
`
`fusion cage between the vertebral bone structures. Preferably two or
`
`three flutes would be formed spaced about the fusion cage in order that
`
`one flute would be engaging with or adjacent to an upper vertebra! bone
`
`structures with another flute being engaging with or adjacent to a lower
`vertebral bone structure. Such a relationship maintains alignment of the
`
`fusion cage and prevent wandering as the fusion cage is introduced
`
`between the twovertebral bone structures. Without two or more flutes,
`
`wandering might occur due to the fact that the thread is only substantially
`
`engaged with the vertebral bone structures and not with the disk material
`
`30
`
`between the vertebral bone structures, which disk material does not
`
`provide support to the thread.
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-4-
`
`in a further aspect of the invention, any of the above embodiments
`
`can be provided with a plurality of apertures through the fusion cage and
`
`an internal cavity with the apertures communicating between the internal
`
`cavity and the external surface of the fusion cage. Bone growth inducing
`
`substances, such as bone chips, can be packed into the internal cavity
`
`either before the fusion cage is inserted or after the fusion cage has
`
`reacheda final insertion position. The bone chips come in contact with
`
`the vertebral bone structures through the apertures in order to facilitate
`
`fusion between the adjacent vertebra! bone structures.
`
`in another aspect of the invention which can be included in any of
`
`the above embodiments, the cage body can have a round or bull nose
`
`distal end with one or more fiutes formed in the round or bull nose distal
`
`end in order to enhance theself-tapping nature of the fusion cage.
`
`In yet another aspect of the invention, introduction tools allow the
`
`fusion cage to be accurately positioned between the vertebral bone
`
`structures.
`
`The method of the present invention affords access to adjacent
`vertebral bone structures using an anterior approach and procedure. Such
`
`anterior
`
`approach
`
`and
`
`procedure
`
`can
`
`be
`
`preferably
`
`performed
`
`laparoscopically using an introduction set
`
`including a cannula.
`
`A
`
`laparoscopic procedure is minimally invasive as the abdomen muscle tissue
`
`can be spread using a set of cannula of increasing size and a small
`opening thereby developed through which a fusion cage can beinserted.
`
`Such a procedureis less traumatic to the tissue than an alternate anterior
`approach and procedure, also known as an anterior lumbar interbody
`fusion, where anincision, perhaps upto five inches long is made, through
`the abdomen muscle tissue.
`It is to be understood howeverthat either
`
`anterior approach and procedure can be used with the fusion cage andfall
`
`within the scope of the invention.
`
`After such access, using preferably a laparoscopic technique,
`
`degenerate disk material can be removed and, using a cannula and
`
`insertion tool, an appropriately shaped fusion cage can be screwed into
`
`10
`
`1s
`
`20
`
`25
`
`30
`
`
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-5-
`
`place between the vertebral bone structures in order to stabilize the
`
`vertebral bone structures and allow for fusion. Either preparatory to
`
`insertion of the fusion cage or after it has been inserted, bone chips or
`
`other bone growth inducing substances can be inserted into the fusion
`
`cage to promote bone to bone contact and subsequentfusion.
`
`It is to be understood that although the above-embodiments have
`
`been described with respect to the fusion of adjacent vertebral bodies or
`
`bone structures, that the present invention can be used to fuse together
`
`a variety of bone structures,
`
`in addition to being fused to one bone
`
`structure and used as, for example, a base for an implant.
`
`Other objects and advantages of the invention can be obtained
`
`through a review of the specification and the figures.
`
`Brief Description of the Figure
`
`Figure 1
`
`is a partially sectional side view of an embodiment of the
`
`fusion cage of the invention.
`
`Figure 2 depicts a left end (distal end) view of the fusion cage of
`
`Figure 1.
`
`Figure 3 depicts a right end (proximal end) view of the fusion cage
`
`10
`
`15
`
`20
`
`of Figure 1.
`
`Figure 4 depicts a view through line 4-4 of the fusion cage of Figure
`
`Figure 5 depicts the fusion cage of Figure 1
`
`in conjunction with an
`
`introduction tool.
`
`Figure 6 depicts an alternative embodiment of the introduction tool.
`
`Figures 7, 8, and 9 depict the progressive stages in the method of
`
`inserting the fusion cage between adjacent vertebral bone structures.
`
`Figure 10 depicts a side view of an alternative embodiment of the
`
`fusion cage of the invention.
`
`Figure 11 depicts the left end (distal end) view of the fusion cage
`
`25
`
`30
`
`of Figure 10.
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-6-
`
`Figure 12 depicts the right end (proximal end) view of the fusion
`
`cage of Figure 10.
`
`Figure 13 depicts a side view of yet another embodiment of the
`
`fusion cage of the present invention.
`
`Figure 14 depicts a left distal end (distal end) view of the fusion
`
`cage of the invention of Figure 13.
`
`Figure 15 depicts a right end (proximal end) view of the fusion cage
`
`of the invention of Figure 13.
`
`Figure 16 depicts a sectional view taken through line 16-16 of
`
`10
`
`Figure 13.
`
`Detailed Description of the Preferred Embodiment
`
`With respect to the figures in a particular Figure 1, a side view of
`
`the preferred embodiment of the fusion cage 20 is depicted. Fusion cage
`
`20 includes a fusion cage body 22 which in this preferred embodimentis
`
`provided in the shape of a cone. Fusion cage 20 includes a distal end 24
`
`and a proximal end 26. The distal end 24 in a preferred embodimentis
`
`rounded or bull nosed in order to facilitate the insertion of the fusion cage
`
`20 relative to one or more bone structures. The proximal end 26 includes
`
`an opening 28 which communicates with an internal cavity 30 defined by
`
`the fusion cage 20. The opening 28 in a preferred embodiment
`
`is
`
`threaded so that it can receive an end cap or plug 32 (Figure 5). End cap
`32 is used to close off the proximal end 26 and retain bone growth
`
`inducing substances packed therein as described herein-below. As can be
`
`seen in Figure 5, end cap 32 includes a threaded bore 34 which is
`
`designed to receive an insertion tool. The threaded bore 34 has an initial
`
`unthreaded, hex-shaped section 35 which can be used with a socket
`
`wrench to tightly position end cap 32 in opening 28. The proximal end 26
`further define first and second peripheral indentations 36, 38. These
`
`peripheral indentations 36, 38 receive tangs from an insertion tool as
`
`described hereinbelow forfacilitating the insertion of the fusion cage 20.
`
`15
`
`20
`
`25
`
`30
`
`
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-7-
`
`A thread 40 is defined as part of the outer cylindrical surface 41 of
`
`the body 22.
`
`It is to be understood that the thread can be replaced with
`
`a plurality of discrete threads or a plurality of projections,
`
`ridges,
`
`protrusions, barbs, or spurs and be within the spirit and scope of the
`
`invention.
`
`The rounded distal end 24, and at least some of the turns of thread
`
`40 defined flutes or relief grooves 42, 44, and 46.
`
`(Figures 1, 2.)
`
`Ina
`
`preferred embodiment, flutes 42, 44, and 46 meetat a central point 48 of
`the distal end 24 on the longitudal axis 50 of the fusion cage 20.
`In other
`
`10
`
`embodiments the flutes can be smaller and not extend all the way to the
`
`15
`
`20
`
`25
`
`central point 48 on the longitude axis 50. Still in other embodiments, the
`
`flutes can be eliminated from the distal end 24 and such embodiments are
`
`still within the spirit and scope of the invention.
`
`The flutes extend from the distal end 24 toward the proximal end
`
`26 as shownin Figure 1 with respect to flute 42. These flutes are defined
`
`by the sections 52 which are removed from the thread.
`
`In a preferred
`
`embodiment, the flutes become narrower as they approach the proximal
`
`end 26 due to the fact that thread relief for purposes of self-tapping
`
`becomes less important as the cage reachesa final resting position. As
`
`shown in other embodiments, the flutes can be deeper and extend from
`
`the distal end completely to the proximal end.
`
`Still further in other
`
`embodiments the flutes can be confined to the first several turns of the
`
`thread adjacent to the distal end and/or to just the distal end.
`
`As can be seen in Figures 1, 4, a plurality of apertures 54 are
`provided through wall 56 of
`the fusion cage 20.
`In a preferred
`
`embodiment, these apertures 54 are formed by broaching grooves 58 in
`
`the internal surface 60 of the interna. cavity 30. The effect of such
`
`roaching is to remove material from the valleys between the turns of the
`
`thread 40, thus defining the aperture 54. The advantages of such an
`
`30
`
`arrangement are taught by the above-referenced U.S. Patent No.
`
`4,961,740, which patent is incorporated herein by reference and allows
`
`for immediate bone to bone contact between the vertebral bodies or bone
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-38-
`
`structures and the bone packed within the internal cavity 30 of the fusion
`
`cage 20.
`
`The apertures 54 in a preferred embodimentincrease in size from
`
`smaller apertures closer to the distal end 24 to a larger aperture closer to
`
`the proximal end 26. This increase in size allows for more bone to bone
`
`contact. Alternatively in the embodiment as shown in Figure 1, all the
`
`apertures are of the same size.
`
`As can be seen in Figure 4, the apertures are clustered about a
`
`transverse axis 51, both at the upper and lower end of the axis. This is
`
`10
`
`so that in position, the apertures come into contact with the upper and
`
`i5
`
`20
`
`25
`
`lower vertebral bone structures (Figure 9) to encourage bone growth
`
`through the fusion cage from the vertebral bone structures. The lateral
`
`section of the fusion cage found along the other transverse axis 53 do not
`
`have apertures in order to prevent growth of disk material which might
`
`interfere with the bone fusing process.
`
`A preferred embodiment of the conically-shaped fusion cage 20
`
`includes a fusion cage which is 23 millimeters in length having a distal end
`
`24 with a diameter of 14 millimeters and a proximal end 26 with a
`
`diameter of 18 millimeters. The cage body is a right circular cone. The
`
`thread has a pitch of 30° and there are ten turns per inch with a thread
`
`depth of .053 inches. Further the cage is made of a titanium material.
`
`Preferably this and the other disclosed fusion cages disclosed are
`
`machined. However, the processes such as molding can be used to
`
`accomplished formation of the fusion cages.
`The cage is inserted between vertebral bodies using an insertion
`
`tool 62 (Figure 5).
`
`Insertion tool 62 includes an inner handle 64 and an
`
`outer handle 66. The outer handle includes a bore 68 for receiving the
`
`inner handle 64. Handles 64, 66 include knobs 70, 72 respectively. The
`
`distal end of inner handle 64 defines a threaded shaft 74, having a reverse
`
`30
`
`thread to facilitate easy removal, and the distal end of handle 66 define a
`
`cylindrical disk 76 which has first and second tangs 78, 80, projecting
`
`from the peripheral edge of the cylindrical disk 76. These tangs 78, 80
`
`
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-9-
`
`are designed to mate with the peripheral! indentation 36, 38 of the fusion
`
`cage 20. For purposesof inserting the fusion cage between the vertebral
`
`bodies, the end cap 32 is inserted into the fusion cage 20 as shown in
`
`Figure 5. Then the threaded shaft 74 of the inner handle is introduced into
`
`the threaded bore 34 of the end cap 32. After this is accomplished, the
`
`outer handle 66 is slid over the inner handle 64 and the tangs 78, 80 are
`
`positioned into engagement with the indentations 36, 38.
`
`In this
`
`arrangement, the fusion cage 20 can be anteriorly inserted into the space
`
`between the vertebral body structure using the insertion tool 62.
`
`10
`
`An alternative embodiment of the insertion tool is shown in Figure
`
`6.
`
`In this figure, insertion tool 82 includes a handle 84 with a knob 86.
`
`At the end of the insertion tool 82 distal from the knob 86 is a cylindrical
`
`disk 88 which has first and second tangs 90, 92, which have the same
`
`function as the above tangs 78, 80. Extending from the center of the
`
`is
`
`cylindrical disk 88 along the centerline of the insertion tool 82 is a shaft
`
`94 which has a ball detent 96.
`
`For use with insertion tool 82,
`
`the
`
`20
`
`25
`
`threaded bore 34 of the end cap 32 would be replaced with a bore having
`
`a lip which could engage with the ball detent 96 of the insertion tool 82.
`
`The method for inserting the fusion cage 20 of Figure 1 using an
`
`anterior approach and procedure to the vertebral bodies is as follows.
`
`It
`
`is to be understood that although the focus of this discussion is on a
`
`laparoscopic procedure, that the anterior approach and procedure can also
`
`include a more invasive procedure where a long incision is made in the
`
`abdomen wall.
`With an anterior approach, using an introduction set such as
`described by way of example only,
`in U.S. Patent 4,863,430, entitled
`
`"INTRODUCTION SET WITH FLEXIBLE TROCAR WITH CURVED
`
`CANNULA,” which is incorporated by reference, but however with farger
`
`diameter instruments, an amount of disk material is removed between the
`
`30
`
`two vertebra! bodies or bone structures which are to be fused together.
`
`This procedure is accomplished through a cannula position adjacent to the
`
`vertebral bone structures. With the same or a larger diameter cannula, the
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-10-
`
`fusion cage 20 can be introduced adjacent
`
`to the vertebral bone
`
`structures.
`
`In a first procedure, the fusion cage is packed with bone
`
`growth substances and the end cap 32 is affixed to the fusion cage 20.
`
`insertion tool 62 is then secured to the fusion cage 20 and the fusion cage
`
`is guided through the cannula to a location adjacent to the upper and
`
`lower vertebra! body such as presented schematically in Figures 7, 8, 9,
`
`by upper body 98 and lower body 100.
`
`In the initial position as shown in
`
`Figure 7, the fusion cage 20 is adjacent to the anterior sections 102, 104
`
`of the vertebral bodies 98, 100. As the introduction too! is turned, the
`
`thread 40 of the fusion cage 20 bites into the vertebral bodies 98, 100.
`
`Further turning of the introduction tool causes the fusion cage to move
`
`through the position shownin Figure 8 to the final resting position shown
`
`in Figure 9, where the distal end 24 is moved adjacent to the posterior
`
`sections 106, 108 of the vertebral bone structures 98, 100.
`
`Asthis
`
`occurs, the fusion cage 20 increases the lordosis or spacing between the
`
`vertebral bodies, basically distracting the vertebral bodies and causing the
`
`vertebral bodies to pivot about the posterior sections 106, 108, with such
`
`posterior sections acting like a hinge.
`
`It
`
`is noted that most of
`
`the
`
`distraction occurs adjacent to the anterior sections, but that distractions
`
`also occur at the posterior sections where the hinged effect is exhibited.
`
`Preferably, the lordosis is increased over the normal lordosis in order to
`
`stabilize
`
`the vertebral bone
`
`structures prior
`
`to fusion occurring.
`
`Stabilization occurs due to the fact
`
`that
`
`increased lordosis places
`
`additional stress on the anterior longitudinal ligaments which are part of
`
`the anatomyholding the vertebral bodies in place.
`
`Oncethe fusion cage 20 is appropriately positioned, the handle 64
`
`of the insertion tool 62 is unscrewed from the cap 32 and the insertion
`
`tool 62 is pulled away from the fusion cage.
`
`An alternative embodiment of a fusion cage 200 is shownin Figures
`
`10, 11, and 12. Fusion cage 200 inciudes a distal end 202 and ana
`
`proximal end 204. Fusion cage 200 includes an internal cavity 206. End
`
`caps not shown can be used to close the ports 208, 210 of distal and
`
`10
`
`15
`
`20
`
`25
`
`30
`
`
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-ll-
`
`proximal ends 202, 204. A plurality of threads 212 is defined on the
`
`external conical surface 214 of the fusion cage 200. Defined by the
`
`thread 212 are first and second flutes 216, 218, which in this embodiment
`
`extend from the distal end 202 to the proximal end 204. These flutes
`
`provide thread relief allowing the fusion cage 200 to be self-tapping.
`
`The fusion cage 200 includesaplurality of elongated apertures 220
`
`which are formed through the side walls of a fusion cage 200. The
`
`elongated apertures 202 are formed in such a way thatthe internal conical
`
`surface 214 is spaced away from the internal surface 224 of the internal
`
`10
`
`cavity 206 by the thickness of the sidewall 222.
`
`A further embodiment of the invention is shown in Figures 13, 14,
`
`15 and 16.
`
`In Figure 16 the fusion cage 300 has distal and proximal ends
`
`302 and 304 respectively. The fusion cage 300 defines an internal cavity
`
`306, and ports 308 and 310 defined through the distal and proximal ends
`
`15
`
`302 and 304 respectfully. A thread 312 is defined as part of the external
`
`conical surface 314 of the fusion cage 200. First, second and third flutes
`
`316, 318, and 320, are defined in the thread 312 from the distal end 302
`
`to the proximal end 304. These flutes give the fusion cage 300 an
`
`enhanced self-tapping advantage. These flutes are equally spaced about
`
`20
`
`the fusion cage 300 in a manner similar to the flutes of the fusion cage
`
`embodiment 20 in Figure 1.
`
`A plurality of aperture 322 is provided through the external conical
`
`surface 314 of the fusion cage 300 and through the side wall 324 opening
`
`into the internal cavity 306. Accordingly, at the location of the aperture
`
`25
`
`322 the external surface 314 is held away from the internal surface 326
`
`by the Sickness of the side wall 324.
`
`industrial Applicability
`
`The present invention affords the advantages of a fusion cage
`
`30
`
`which can be introduced through an anterior approach in order to maintain
`
`or increase lordosis between adjacent vertebral bodies. The fusion cage
`
`has the advantage of being conically-shaped and self-tapping through the
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-12-
`
`use of external flutes. The flutes additionally assist in keeping the fusion
`
`cage aligned and centered as the cage is being inserted between the
`
`vertebral bone structures.
`
`Other advantages, aspects, and objects of the invention can be
`
`obtained through a review of the claims and the appended figures.
`
`It is to be understood that additional embodiments of the invention
`
`can be constructed and fall within the spirit and scope of the claims.
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`
`
`We claim:
`
`-13-
`
`I.
`
`A fusion cage for promoting fusion with one or more bone
`
`structures comprising:
`
`a conically-shaped cage body having a pro» nal end and a distal
`
`end, said distal end having a diameter which is smaller than a diameter of
`
`said proximal end; and
`
`said distal end be.1g rounded in order to facilitate insertion relative
`
`to one or more bone structures.
`
`2.
`
`The fusion cage of claim 1
`
`including:
`
`said conically-shaped cage body having a conically-shaped outer
`
`surface and at least one flute formed in the conically-shaped outer surface.
`
`3.
`
`The fusion cage of claim 2 including:
`
`said conically-shaped cage body wherein said flute extends from
`
`the distal end toward the proximal end.
`
`4.
`
`The fusion cage of claim 2 including:
`
`at least three flutes formed in the conically-shaped outer surface.
`
`5.
`
`The fusion cage of claim 4 including:
`
`said three flutes are equally spaced about said distal end.
`
`6.
`
`The fusion cage of claim 2 including:
`
`said flute being additionally formed in the rounded distal end.
`
`7.
`
`The fusion cage of claim 4 including:
`
`said three flutes being additionally formed in the rounded dista! end.
`
`8.
`
`The fusion cage of claim 1
`
`including:
`
`10
`
`15
`
`20
`
`25
`
`30
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-14-
`
`said conically-shaped cage body having a conically-shaped outer
`
`surface and a thread formed into said conically-shaped outer surface.
`
`9.
`
`The fusion cage of claim 8 including:
`
`at least one flute formed in the thread.
`
`10.
`
`The fusion cage of claim 8 including:
`
`said conically-shaped cage body having a conically-shaped outer
`
`surface and an internal cavity; and
`
`a plurality of apertures formed through the conically-shaped body
`
`which communicate said conically-shaped outer surface with said internal
`
`Cavity.
`
`11.
`
`The fusion cage of claim 1
`
`including:
`
`said conically-shaped cage body is a right circular cone.
`
`12.
`
`A fusion cage for promoting fusion with between two spaced
`
`apart vertebral bone structures which have posterior sections and anterior
`
`sections and with a posterior interspace defined between the posterior
`
`sections and an anterior interspace defined between the anterior sections,
`
`said fusion cage comprising:
`
`10
`
`15
`
`20
`
`a conically-shaped cage body having a proximal end and a distal
`
`end, said distal end having a diameter which is smaller than a diameter of
`
`said proximal end, with said distal end positionable in the posterior
`
`25
`
`interspace between the posterior sections of the vertebral bone structures
`
`and with said proximal end positionable in the anterior interspace between
`
`the anterior sections of said vertebral bone structures in order to maintain
`
`the height of the anterior interspace larger than the height of the posterior
`
`interspace; and
`
`30
`
`said conically-shaped cage body having a conically-shaped outer
`
`surface and a thread formed into said conically-shaped outer surface in
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-15-
`
`order to engage the vertebral bone structures as the cage body is inserted
`
`from the anterior interspace toward the posterior interspace.
`
`13.
`
`The fusion cage of claim 12 including:
`
`said distal end being rounded in order to facilitate insertion of the
`
`fusion
`
`cage between the vertebral bone structures, from the anterior
`
`intersp
`
`ace toward the posterior interspace.
`
`10
`
`15
`
`20
`
`14.
`
`The fusion cage of claim 12 inciuding:
`
`at least one flute formed in the thread.
`
`15.
`
`The fusion cage of claim 14 inciuding:
`
`said flute extends from the distal end toward the proximal end.
`
`16.
`
`The fusion cage of claim 12 including:
`
`at least three flutes formed in the thread.
`
`17.
`
`The fusion cage of claim 16 including:
`
`said three flutes are equally spaced about said distal end.
`
`18.
`
`The fusion cage of clam 13 including:
`
`at least one flute being formed in the rounded distal end.
`
`19.
`
`The fusion cage of claim 18 including:
`
`25
`
`three flutes being formed in the rounded distai end.
`
`20.+=The fusion cage of claim 12 including:
`
`said conically-shaped cage body having an internal cavity; and
`
`a plurality of apertures formed through the conically-shaped body
`
`30
`
`which communicate said conically-shaped outer surface with said internal
`
`cavity.
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`-16-
`
`21.
`
`The fusion cage of claim 12 including:
`
`said conically-shaped cage body is a right circular cone.
`
`22.
`
`A fusion cage for promoting fusion with one or more bone
`
`structures comprising:
`
`a conicaliy-shaped cage body having a proximal end and a distal
`
`end, said distal end having a diameter which is smaller than a diameter of
`
`said proximal end; and
`
`said conically-shaped cage body having a conically-shaped outer
`
`surface and at least one fiute formed in the conically-shaped outer surface.
`
`23.
`
`The fusion cage of claim 22 including:
`
`said distal end being rounded in orderto facilitate insertion relative
`
`to one or more bone structures.
`
`24.
`
`The fusion cage of claim 22 including:
`
`said conically-shaped cage body wherein said flute extends from
`
`the distal end toward the proximal end.
`
`25.
`
`The fusion cage of claim 22 including:
`
`at least three flutes formed in the conically-shaped outer surface.
`
`26.
`
`The fusion cage of claim 22 including:
`
`three flutes equally spaced about said distal end.
`
`27.
`
`The fusion cage of clam 23 including:
`
`a flute formed in the rounded distal end.
`
`28.
`
`The fusion cage of claim 25 including:
`
`said distal end being roundedin order to facilitate insertion relative
`
`to the one or more bone structures;
`
`and
`
`10
`
`15
`
`20
`
`25
`
`30
`
`
`
`WO 96/08205
`
`PCT/US95/11281
`
`
`
`-17-
`
`said three flutes being additionally formed in the rounded distal end.
`
`29.
`
`The fusion cage of claim 22 including:
`
`a thread formed into said conically-shaped outer surface.
`
`30.
`
`The fusion cag
![](/site_media/img/document_icon.png)
Accessing this document will incur an additional charge of $.
After purchase, you can access this document again without charge.
Accept $ ChargeStill Working On It
This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.
Give it another minute or two to complete, and then try the refresh button.
A few More Minutes ... Still Working
It can take up to 5 minutes for us to download a document if the court servers are running slowly.
Thank you for your continued patience.
![](/site_media/img/error_icon.png)
This document could not be displayed.
We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.
![](/site_media/img/error_icon.png)
Your account does not support viewing this document.
You need a Paid Account to view this document. Click here to change your account type.
![](/site_media/img/error_icon.png)
Your account does not support viewing this document.
Set your membership
status to view this document.
With a Docket Alarm membership, you'll
get a whole lot more, including:
- Up-to-date information for this case.
- Email alerts whenever there is an update.
- Full text search for other cases.
- Get email alerts whenever a new case matches your search.
![](/site_media/img/document_icon.png)
One Moment Please
The filing “” is large (MB) and is being downloaded.
Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.
![](/site_media/img/document_icon.png)
Your document is on its way!
If you do not receive the document in five minutes, contact support at support@docketalarm.com.
![](/site_media/img/error_icon.png)
Sealed Document
We are unable to display this document, it may be under a court ordered seal.
If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.
Access Government Site