US008613769B2
`
`(12) Ulllted States Patent
`Sears et a].
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 8,613,769 B2
`Dec. 24, 2013
`
`(54) APPARATUS AND METHOD FOR
`SUPPORTING VERTEBRAL BODIES
`
`.
`.
`.
`(75) Inventors: William Sears, Klllara (AU); B.
`Thomas Barker, Bartlett, TN (Us)
`
`(73) Assignee: Warsaw Orthopedic, Inc., Warsaw, IN
`(Us)
`
`( * ) Notice:
`
`Subject' to any disclaimer, the term of this
`patent 1s extended or adjusted under 35
`U.S.C. 154(b) by 99 days.
`
`.
`(21) Appl' NO" 13/100’614
`
`(22) Filed:
`
`May 4, 2011
`
`2/ 1990 Dove et a1.
`4,904,261 A
`5,062,850 A 11/1991 MacMillan et a1.
`5,108,395 A *
`4/1992 Laurain ..................... .. 606/86 B
`5,192,327 A
`3/1993 Branti an
`5,336,223 A
`8/1994 Roger?
`5,413,602 A
`5/1995 MetZ-Stavenhagen
`5,571,190 A 11/1996 Ulrich et a1.
`5,620,458 A
`4/ 1997 Green et a1~
`5,645,084 A
`7/1997 McKay
`6,086,613 A
`7/2000 Camino et al.
`2
`ggggliegfait 31'
`6,193,720 B1
`2/2001 Yuan et a1,
`6,235,034 B1
`5/2001 Bray
`6,296,665 B1
`10/2001 Strnad et al.
`6,299,644 B1
`10/2001 Vanderschot
`6,375,681 B1
`4/2002 Truscott
`
`(Continued)
`
`(65)
`
`Prior Publication Data
`
`FOREIGN PATENT DOCUMENTS
`
`US 2011/0208314 A1
`
`Aug. 25, 2011
`
`Related US. Application Data
`
`(63) Continuation of application No. 12/321,186, ?led on
`Jan. 16, 2009, noW Pat. NO. 8,012,213, which is a
`continuation of application No. 10/407,010, ?led on
`Apr. 3, 2003, noW Pat. NO. 7,563,281.
`
`(2006-01)
`
`(51) Int- Cl-
`A61F 2/44
`(52) U-S- Cl-
`USPC ................................... .. 623/1714; 623/1711
`(58) Field of Classi?cation Search
`USPC ................... .. 623/ 17.11*17.16; 606/248i249
`See application ?le for complete search history.
`
`(56)
`
`References Cited
`
`US. PATENT DOCUMENTS
`
`4,554,914 A 11/1985 Kapp et a1.
`4,599,086 A
`7/1986 Doty
`4,636,217 A
`1/1987 Ogilvie et 211.
`4,759,769 A
`7/1988 Hedman et a1.
`
`DE
`EP
`FR
`
`9413 778 U1
`1 080 703 A3
`2636227 A1
`
`2/1996
`1/2002
`3/1990
`
`P 1’ Wary Exam/7'19" * Thomas J Sweet
`AsslslanlExammeriChnswpherD Prone
`
`ABSTRACT
`(57)
`An apparatus and method for supporting upper and loWer
`vertebral bodies, including ?rst and second end members
`adapted for engagement With the vertebral bodies, and at least
`one elongate support member coupled betWeen the end mem
`berg to maintain an axial space between the vertebral bodies,
`In one aspect of the invention, each of the end members has a
`parametrical or horseshoe-shaped con?guration extending
`about an open inner region and de?ning a lateral passage
`communicating With the open inner region to facilitate inser
`tion of the apparatus or the individual end members into the
`intervertebral space via a posterior surgical approach. In a
`further aspect of the invention, a fusion member is positioned
`Within the axial space to promote bony fusion betWeen the
`upper and loWer vertebral bodies.
`
`6 Claims, 10 Drawing Sheets
`
` 1
`
`NUVASIVE 1056
`NuVasive, Inc. v. Warsaw Orthopedic, Inc.
`IPR2013-00206
`IPR2013-00208
`
`

`

`US 8,613,769 B2
`Page 2
`
`(56)
`
`References Cited
`
`US. PATENT DOCUMENTS
`
`6,375,683 B1
`6,626,943 B2
`
`4/2002 CroZet et a1.
`9/2003 Eberlein et a1.
`
`1/2006 Errico et 31.
`6,989,032 B2
`1/2008 Bernstein
`7,320,708 B1
`4/2002 Fuss et a1.
`2002/0045904 A1
`2002/0169508 A1* 11/2002 Songer et a1. ............ .. 623/17.11
`_
`_
`* clted by examlner
`
`
`
` 2
`
`

`

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`US. Patent
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`Dec. 24, 2013
`Dec. 24, 2013
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`US 8,613,769 B2
`
`1
`APPARATUS AND METHOD FOR
`SUPPORTING VERTEBRAL BODIES
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`
`The present application is a continuation of US. patent
`application Ser. No. 12/321,186, ?led Jan. 16, 2009 and noW
`issued as US. Pat. No. 8,012,213, Which is a continuation of
`US. patent application Ser. No. 10/407,010 ?ledApr. 3, 2003
`and noW issued as US. Pat. No. 7,563,281. The contents of
`each application is hereby incorporated by reference in its
`entirety.
`
`FIELD OF THE INVENTION
`
`The present invention generally relates to spinal implants,
`and more particularly relates to an apparatus and method for
`supporting an axial space betWeen vertebral bodies following
`a vertebrectomy.
`
`BACKGROUND
`
`Various portions of the spinal column may become dis
`placed or damaged due to trauma, disease or aging. Treatment
`procedures may involve removal of at least a portion of one or
`more vertebral bodies and/or intervertebral disc tissue. Sev
`eral techniques are currently available for restoring and main
`taining the axial space betWeen tWo vertebral bodies folloW
`ing removal of vertebral bone and/or tissue from the area
`betWeen the vertebral bodies. Restoration and support of the
`axial space is sometimes accomplished by attaching one or
`more plates and/or rods to outer surfaces of the vertebral
`bodies to bridge the intervertebral space. In other instances,
`an implant is inserted into the intervertebral space to provide
`the requisite amount of axial support. Additionally, a bone
`groWth inducing material is sometimes introduced into the
`intervertebral space to facilitate the formation of a solid bony
`connection betWeen the vertebral bodies. For example, pre
`vious vertebral body replacement implants include allograft,
`silicone tubing ?lled With cement, cages and other types of
`fusion devices or materials. HoWever, adjustability is a fea
`ture that most of these to techniques fail to provide. Subsid
`ence into the adjacent vertebral bodies is also a draWback
`prevalent in previous vertebrectomy options.
`Access to a displaced or damaged portion of the spinal
`column may be accomplished via several approaches. One
`approach is to gain access to the anterior portion of the spine
`through the patient’s chest or abdomen. HoWever, signi?cant
`morbidity may ensue and many vertebral levels are not
`readily accessible via an anterior approach, particularly With
`regard to the upper thoracic or upper lumbar vertebral levels.
`A posterior approach may also be used and provides a number
`of advantages, but may be associated With considerable dif
`?culty in the reconstruction of the spinal column. In particu
`lar, the presence of the spinal cord and the inherent risks
`associated With retraction and manipulation of this structure
`limits access to the intervertebral space that lies anterior to the
`spinal cord. While it is desirable that implants should distrib
`ute the loads of the spinal column evenly and Widely across
`the vertebral endplates, the introduction of currently available
`implants requires considerable retraction and/or manipula
`tion of the spinal cord, thereby increasing the potential for
`complications.
`Thus, there is a general need in the industry to provide an
`improved apparatus and method for supporting vertebral bod
`
`20
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`55
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`2
`ies folloWing a vertebrectomy. The present invention meets
`this need and provides other bene?ts and advantages in a
`novel and unobvious manner.
`
`BRIEF DESCRIPTION OF THE FIGURES
`
`FIG. 1 is an end elevational vieW of a cage assembly
`according to one embodiment of the present invention.
`FIG. 2 is a side perspective vieW of an end member accord
`ing to one embodiment of the present invention for use in
`association With the cage assembly illustrated in FIG. 1.
`FIG. 3 is a top plan vieW, partially in section, of the end
`member illustrated in FIG. 2.
`FIG. 4 is a side elevational vieW of the cage assembly
`illustrated in FIG. 1, as positioned betWeen upper and loWer
`vertebral bodies.
`FIG. 5 is a cross sectional vieW of the cage assembly
`illustrated in FIG. 4, as vieWed along line 5-5 of FIG. 4.
`FIGS. 6A-6C are illustrations of a method according to one
`embodiment of the present invention for inserting the cage
`assembly illustrated in FIG. 1 betWeen the upper and loWer
`vertebral bodies using a posterior surgical approach.
`FIG. 7 is a perspective elevational vieW of a cage assembly
`according to another embodiment of the present invention, as
`positioned betWeen upper and loWer vertebral bodies and
`With a ?bular strut augmented Within an interior region of the
`cage assembly for promoting bone groWth betWeen the upper
`and loWer vertebral bodies.
`FIG. 8 is a perspective elevational vieW of a cage assembly
`according to another embodiment of the present invention, as
`positioned betWeen upper and loWer vertebral bodies and
`With a holloW mesh cage member positioned Within an inte
`rior region of the cage assembly for promoting bone groWth
`betWeen the upper and loWer vertebral bodies.
`FIG. 9 is a perspective elevational vieW of a cage assembly
`according to another embodiment of the present invention, as
`positioned betWeen upper and loWer vertebral bodies and
`With graft material contained by a resorbable ?lm positioned
`Within an interior region of the cage assembly for promoting
`bone groWth betWeen the upper and loWer vertebral bodies.
`FIG. 10 is a cross-sectional vieW of the cage assembly
`illustrated in FIG. 9.
`FIG. 11 is a side vieW of a distractor instrument according
`to one embodiment of the present invention for use in asso
`ciation With the cage assembly illustrated in FIG. 1.
`FIG. 12 is a top plan vieW of the distractor instrument
`illustrated in FIG. 11.
`FIG. 13a is a side elevational vieW of the distal end portions
`of the distractor instrument illustrated in FIG. 11, as engaged
`With the upper and loWer end members of the cage assembly
`illustrated in FIG. 1 to distract the upper and loWer vertebral
`bodies.
`FIG. 13b is a cross-sectional vieW of the distal end portions
`of the distractor instrument as engaged With the cage assem
`bly illustrated in FIG. 1311, as vieWed along line 1319-1319 of
`FIG. 13a.
`FIG. 14 is an exploded posterior elevational vieW of a cage
`assembly according to another embodiment of the present
`invention having a multi-axial con?guration.
`FIG. 15 is a top plan vieW, partially in section, of a multi
`axial end member according to one embodiment of the inven
`tion for use in association With the cage assembly illustrated
`in FIG. 14, as vieWed along line 15-15 of FIG. 14.
`FIG. 16 is a cross sectional vieW of the multi-axial end
`member illustrated in FIG. 15, as vieWed along line 16-16 of
`FIG. 15.
`
`
`
`13
`
`

`

`US 8,613,769 B2
`
`3
`FIG. 17 is an exploded posterior elevational vieW of a cage
`assembly according to another embodiment of the present
`invention having a mono-axial con?guration.
`FIG. 18 is a top plan vieW, partially in section, of a mono
`axial end member according to one embodiment of the inven
`tion for use in association With the cage assembly illustrated
`in FIG. 17, as vieWed along line 18-18 of FIG. 17.
`FIG. 19 is a cross sectional vieW of the mono-axial end
`member illustrated in FIG. 18, as vieWed along line 19-19 of
`FIG. 18.
`
`SUMMARY OF THE INVENTION
`
`According to one form of the present invention, an appa
`ratus is provided for supporting vertebral bodies, including a
`?rst end member adapted to engage a loWer endplate of a ?rst
`vertebral body, a second end member adapted to engage an
`upper endplate of a second vertebral body, and at least one
`elongate support member coupled betWeen the ?rst and sec
`ond end members to maintain an axial space betWeen the ?rst
`and second vertebral bodies. Each of the ?rst and second end
`members has a parametrical con?guration extending about an
`open inner region and de?ning a lateral passage communi
`cating With the open inner region.
`According to another form of the present invention, an
`apparatus is provided for supporting vertebral bodies, includ
`ing a ?rst horseshoe-shaped member adapted to engage a ?rst
`vertebral body, a second horseshoe-shaped member adapted
`to engage a second vertebral body, and at least one elongate
`support member coupled betWeen the ?rst and second horse
`shoe-shaped members to maintain an axial space betWeen the
`?rst and second vertebral bodies.
`According to another form of the present invention, an
`apparatus is provided for supporting vertebral bodies, includ
`ing a ?rst end member adapted to engage a ?rst vertebral
`body, a second end member adapted to engage a second
`vertebral body, at least one elongate support member coupled
`betWeen the ?rst and second end members to maintain an
`axial space betWeen the ?rst and second vertebral bodies, and
`a fusion member positioned Within the axial space to promote
`bony fusion betWeen the ?rst and second vertebral bodies.
`According to another form of the present invention, a
`method for supporting vertebral bodies of a spinal column is
`provided, including providing ?rst and second end members
`each having a parametrical con?guration extending about an
`open inner region and de?ning a lateral passage communi
`cating With the open inner region, and providing at least one
`elongate support member. The method further includes posi
`tioning the ?rst end member adjacent a ?rst vertebral body,
`positioning the second end member adjacent a second verte
`bral body, and coupling the elongate support member
`betWeen the ?rst and second end members to maintain an
`axial space betWeen the ?rst and second vertebral bodies.
`According to another form of the present invention, a
`method for supporting vertebral bodies of a spinal column is
`provided, including providing ?rst and second end members
`each including an axial passage extending therethrough, pro
`viding at least one elongate support member, and providing
`fusion material. The method further includes positioning the
`?rst end member in the axial space and adjacent an endplate
`of the ?rst vertebral body With the axial passage of the ?rst
`end member arranged along the sagittal plane of the spinal
`column, positioning the second end member in the axial space
`and adjacent an endplate of the second vertebral body With the
`axial passage of the second end member arranged along the
`sagittal plane of the spinal column, coupling the elongate
`support member betWeen the ?rst and second end members to
`
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`maintain the axial space betWeen the ?rst and second verte
`bral bodies, and positioning the fusion material Within the
`axial space adjacent the axial passages of the ?rst and second
`end members to promote bony fusion betWeen the endplates
`of the ?rst and second vertebral bodies.
`It is one object of the present invention to provide an
`improved apparatus and method for supporting vertebral bod
`1es.
`Further objects, features, advantages, bene?ts, and further
`aspects of the present invention Will become apparent from
`the draWings and description contained herein.
`
`DESCRIPTION OF THE ILLUSTRATED
`EMBODIMENTS
`
`For the purposes of promoting an understanding of the
`principles of the invention, reference Will noW be made to the
`embodiments illustrated in the draWings and speci?c lan
`guage Will be used to describe the same. It Will nevertheless
`be understood that no limitation on the scope of the invention
`is hereby intended, such alterations and further modi?cations
`in the illustrated devices and methods, and such further appli
`cations of the principles of the invention as illustrated herein
`being contemplated as Would normally occur to one skilled in
`the art to Which the invention relates.
`Referring to FIG. 1, shoWn therein is an apparatus 20 for
`supporting vertebral bodies according to one form of the
`present invention. In one embodiment, the apparatus 20 is a
`modular vertebrectomy cage assembly positionable Within an
`intervertebral space to span one or more vertebral levels along
`the longitudinal axis of the spinal column. Although the illus
`trated embodiment of the cage assembly 20 spans three ver
`tebral levels (FIG. 4), it should be understood that the cage
`assembly 20 may be con?gured to span a single vertebral
`level, tWo vertebral levels, or four or more vertebral levels.
`The cage assembly 20 is generally comprised of a ?rst end
`member 22, a second end member 24, and one or more elon
`gate support members or rods 26 coupled betWeen the ?rst
`and second end members 22, 24. Although the cage assembly
`20 has been illustrated as including a pair of support rods 26,
`it should be understood that any number of support rods may
`be used, including a single support rod or three or more
`support rods. In one embodiment of the invention, the support
`rods 26 have a solid con?guration and a generally cylindrical
`shape. HoWever, it should be understood that other shapes and
`con?gurations of the support rods 26 are also contemplated.
`For example, in other embodiments of the invention, the
`support rods 26 may be con?gured as holloW tubes. In further
`embodiments, the support rods 26 may take on other cross
`sectional shapes, such as, for example, rectangular, hexago
`nal or elliptical cross-sectional shapes, or any other cross
`sectional shape that Would occur to one of skill in the art.
`The end members 22, 24 are adapted to engage the end
`plates of upper and loWer vertebral bodies VU, VL (FIG. 4).
`The support rods 26 are engaged betWeen the end members
`22, 24 to maintain an intervertebral axial space S betWeen the
`upper and loWer vertebral bodies VU, VL folloWing the
`removal of one or more vertebral levels (shoWn in phantom).
`In one embodiment of the invention, the support rods 26 are
`engaged to the end members 22, 24 via a number of fasteners,
`such as, for example, set screWs 28. HoWever, as Will be
`discussed in greater detail beloW, it should be understood that
`other means for engaging the support rods 26 to the end
`members 22, 24 are also contemplated as falling Within the
`scope of the present invention.
`In one embodiment of the invention, the end members 22,
`24 are formed of a radiolucent material, such as, for example,
`
`
`
`14
`
`

`

`US 8,613,769 B2
`
`5
`a carbon ?ber material. In this manner, x-ray vieWing of the
`intervertebral space S and the vertebral endplates subsequent
`to implantation of the cage assembly 20 Will be relatively
`unobstructed. In further embodiments of the invention, the
`end members 22, 24 may be formed of other suitable mate
`rials, such as, for example, stainless steel, titanium or other
`biocompatible materials. In another embodiment of the
`invention, the support rods 26 are formed of stainless steel,
`titanium or other biocompatible materials. In further embodi
`ments, the support rods 26 and/or any other component of the
`cage assembly 20 may be formed of a radiolucent material,
`such as, for example, a carbon ?ber material.
`Referring noW to FIGS. 2 and 3, shoWn therein are further
`details regarding the end members 22, 24. With speci?c
`regard to the cage assembly 20, the end members 22, 24 are
`con?gured identical to one another. HoWever, it should be
`understood that in other embodiments of the invention, the
`end members 22, 24 can take on different con?gurations,
`examples of Which Will be illustrated and described beloW.
`In a preferred embodiment of the invention, each of the end
`members 22, 24 has a parametrical con?guration extending
`about an open inner region 30 and de?ning a lateral passage
`32 communicating With open inner region 30. In one embodi
`ment, the end members 22, 24 are generally horseshoe
`shaped. In other embodiments, the end members 22, 24 could
`also be described as being U-shaped, C-shaped, V-shaped,
`semi-circular shaped, semi-oval shaped, or other terms that
`could be used to describe a shaped element de?ning an open
`inner region and a lateral passage communicating thereWith.
`In further embodiments of the invention, the end members 22,
`24 may take on other types of holloW con?gurations, such as,
`for example, a circular shape, semi-oval shape, kidney shape,
`D-shape, or any other shape that Would occur to one of skill in
`the art. In still other embodiments of the invention, the end
`members 22, 24 may take on substantially solid con?gura
`tions, such as, for example, block-like or plate-like con?gu
`rations that do not de?ne an open inner region.
`It should further be appreciated that the siZe and/or con
`?guration of the end members 22, 24 may be speci?cally
`designed to accommodate any particular region of the spinal
`column and/ or any particular vertebral level. For example, in
`embodiments of the invention associated With the upper tho
`racic or cervical region of the spine, the end members 22, 24
`may be designed to have a D-shaped con?guration, Whereas
`embodiments of the invention associated With the lumbar
`region of the spine may be con?gured to have a horseshoe
`shape, a U- shape, or other types of open-sided con?gurations.
`In one embodiment of the invention, the end members 22,
`24 have a lateral pro?le that is substantially complementary to
`the siZe and shape of the peripheral portion or outlying region
`of the vertebral bodies, such as the cortical rim or the apo
`physeal ring of the vertebral endplates. For example, as illus
`trated in FIG. 5, the outer perimeter of the end member 24 is
`preferably disposed generally above the inner edge of the
`cortical rim R of the loWer vertebral body VL. In this manner,
`at least a portion of the end members 22, 24 is engaged against
`the cortical region of the vertebral endplates, thereby mini
`miZing the likelihood of subsidence into the relatively softer
`cancellous region of the upper and loWer vertebral bodies V U,
`VL folloWing implantation of the cage assembly 20 Within the
`intervertebral space S. Additionally, the parametrical con
`?guration of the end members 22, 24 in combination With the
`relatively large surface area of the end members 22, 24
`engaged against the vertebral endplates enhances the overall
`stability of the cage assembly 20. Moreover, the open inner
`region 30 de?ned by each of the end member 22, 24 provides
`signi?cant exposure of the vertebral endplates to enhance
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`bony fusion betWeen the upper and loWer vertebral bodies V U,
`VL, the details of Which Will be discussed beloW.
`In one embodiment of the invention, the end members 22,
`24 include a main body or base portion 40 and a pair of
`oppositely disposed Wings or side portions 42a, 42b extend
`ing from the base portion 40. The base portion 40 and the side
`portions 42a, 42b cooperate to de?ne the open inner region
`30, With the distal ends of the side portions 42a, 42b de?ning
`the lateral passage 32 therebetWeen. The lateral surface of the
`base portion 40 facing the open inner region 30 de?nes a
`recessed area 43 to eliminate the presence of sharp corners
`and Which also serves to provide for a slightly larger open
`inner region 30 Which correspondingly increases exposure of
`the vertebral endplates to enhance fusion capabilities.
`In one embodiment, the upper/loWer engaging surface 44
`of the end members 22, 24 is substantially planar and de?nes
`surface features and/ or a number of anchor elements adapted
`for engagement With the vertebral endplates to inhibit move
`ment of the end members 22, 24 relative to the upper and
`loWer vertebral bodies VU, VL. For example, in one embodi
`ment, the upper/loWer engaging surfaces 44 may be rough
`ened, such as, for example, by knurling and/or etching (e. g.,
`photochemical etching). In other embodiments, various types
`of projections or protrusions may extend from the upper/
`loWer engaging surfaces 44, such as, for example, a number of
`spikes, ridges, teeth, axial grooves, checkerboard-type
`grooves, or any other type of anchoring element that Would
`occur to one of skill in the art. Although the upper/loWer
`engaging surfaces 44 of the end members 22, 24 are illus
`trated as being arranged substantially parallel to one another
`When the cage assembly 20 is fully assembled (FIG. 1), it
`should be understood that the upper/lower engaging surfaces
`44 may be tapered relative to one another to more closely
`conform With the anatomical curvature of the spine at the
`surgical site (e. g., the angle of lordosis or kyphosis). It should
`also be understood that the support rods 26 may be bent
`and/or provided With a predetermined curvature to more
`closely match the con?guration of the cage assembly 20 With
`the anatomical curvature of the spine at the surgical site.
`The base portion 40 of the end members 22, 24 de?nes a
`pair of sockets or receptacles 46a, 46b siZed to receive end
`portions of respective support rods 26 therein. It should be
`understood, hoWever, that the base portion 40 may de?ne any
`number of sockets or receptacles for receiving a correspond
`ing number of support rods, including a single socket or three
`or more sockets. In one embodiment of the invention, the
`sockets 46a, 46b each de?ne a lateral opening 48 siZed to
`receive the end portion of a corresponding support rod 26
`therethrough. In this manner, the end portions of the support
`rods 26 may be laterally inserted into the sockets 46a, 46b via
`a side-loading technique, preferably from a posterior direc
`tion. Lateral insertion of the support rods 26 may be particu
`larly advantageous When assembling the cage assembly 20 in
`situ Within the intervertebral space S. The lateral openings 48
`are preferably general aligned With the lateral passage 32
`de?ned betWeen the side portions 42a, 42b to further enhance
`the ability to laterally insert the support rods 26 into the
`sockets 46a, 46b. In a further embodiment of the invention,
`the sockets 46a, 46b each de?ne a thru-opening 50 extending
`axially through the end members 22, 24 and siZed to slidably
`receive the end portion of a corresponding support rod 26
`therethrough. This embodiment of the invention may also be
`particularly advantageous When assembling the cage assem
`bly 20 in situ Within the intervertebral space S.
`Although a speci?c embodiment of the sockets 46a, 46b
`has been illustrated and described herein, it should be under
`stood that sockets 46a, 46b may take on other alternative
`
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`15
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`

`

`US 8,613,769 B2
`
`7
`con?gurations. For example, as illustrated in FIGS. 7 and 8,
`the end members 122, 124 associated With the cage assembly
`100 de?ne sockets that do not de?ne lateral openings, but
`instead de?ne a closed con?guration. As should be appreci
`ated, in this embodiment, engagement of the support rods 126
`With the end members 122, 124 Would occur via axial inser
`tion of the end portions of the support rods 126 into the
`sockets of the end members 122, 124. Similarly, as illustrated
`in FIGS. 9 and 10, the end members 222, 224 associated With
`the cage assembly 200 also de?ne a closed con?guration.
`Additionally, although the sockets 46a, 46b have been illus
`trated as de?ning an axial thru-opening 50, in other embodi
`ments of the invention, the sockets 46a, 46b may alternative
`de?ne a closed or blind bottom con?guration.
`In the illustrated embodiment of the invention, the sockets
`46a, 46b each de?ne a laterally-extending threaded aperture
`52 that is adapted to threadingly receive a corresponding set
`screW 28 therein (FIG. 1). Once the end portions of the sup
`port members 26 are inserted into the sockets 46a, 46b, the set
`screWs 28 are threaded into the apertures 52 and into engage
`ment With the end portions of the support rods 26 to securely
`couple the end members 22, 24 thereto. The threaded aper
`tures 52 are preferably generally aligned With the lateral
`passage 32 de?ned betWeen the side portions 42a, 42b to
`provide substantially uninhibited access to the set screWs 28
`to facilitate tightening of the set screWs 28 into the end mem
`bers 22, 24. Once again, this setup may be particularly advan
`tageous When assembling the cage assembly 20 in situ Within
`the intervertebral space S.
`In one embodiment, the threaded aperture 52 extend along
`axes 54a, 54b that are outWardly tapered relative to one
`another and to the sagittal plane P extending along the spinal
`column When the cage assembly 20 is positioned Within the
`intervertebral space S (FIG. 5). Arrangement of the set screW
`axes 54a, 54b in a diverging relationship tends to enhance the
`accessibility of the set screWs 28. In one embodiment of the
`invention, the set screW axes 54a, 54b are arranged to de?ne
`an included angle [3 of about ten (10) to tWenty (20) degrees.
`In a speci?c embodiment, the included angle [3 is about six
`teen (16) degrees. HoWever, it should be understood that other
`arrangements of the axes 54a, 54b are also contemplated as
`falling Within the scope of the present invention, including
`parallel arrangements.
`In one embodiment of the invention, the set screWs 28 are
`of the break-off type, including a head portion that is selec
`tively removable from a threaded shank portion, the details of
`Which Will be discussed beloW. HoWever, it should be under
`stood that other types and con?gurations of set screWs are also
`contemplated. It should also be understood that although set
`screWs have been illustrated and described as the preferred
`means for coupling the support rods 26 to the end members
`22, 24, other elements or devices may alternatively be used,
`such as, for example, various types of fasteners, snap rings,
`collets, collars, Wedges, or any other type of element or device
`capable of coupling the support rods 26 to the end members
`22, 24. Alternatively, either or both end portions of each
`support rod 26 may be threadingly engaged With a corre
`sponding threaded portion de?ned by each of the end mem
`bers 22, 24.
`In a further aspect of the invention, the end members 22, 24
`each de?ne a tool receiving aperture 56. The tool receiving
`apertures 56 are siZed and shaped to receive a corresponding
`end portion of a tool or instrument therein to facilitate inser
`tion of the cage assembly 20 into the intervertebral space S,
`manipulation of the end members 22, 24 relative to the sup
`port rods 26, and/or distraction of the intervertebral space S.
`Although the tool receiving apertures 56 are illustrated as
`
`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`8
`having a generally circular con?guration, other shapes and
`con?gurations are also contemplated, such as, for example,
`hexagonal or rectangular con?gurations. In the illustrated
`embodiment of the invention, the tool receiving apertures 56
`are formed in the base portion 40 of the end members 22, 24
`through an inWardly facing surface 58 (the surface opposite
`the outer engaging surface 44). HoWever, it should be under
`stood that the tool receiving apertures 56 may be formed in
`other portions of the end members 22, 24, including the side
`portions 42a, 42b (see FIGS. 9 and 10), and through other
`surfaces, such as the laterally extending surfaces of the end
`members 22, 24.
`In the illustrated embodiment of the invention, the sockets
`46a, 46b associated With the end members 22, 24 have been
`depicted as having an axially extending cylindrical con?gu
`ration adapted to receive a correspondingly shaped end por
`tion of a support rod 26 therein. In this manner, When the
`support rods 26 are properly positioned Within the sockets
`46a, 46b, the support rods 26 Will be arranged at a predeter
`mined angular orientation relative to the end members 22, 24,
`Which in turn arranges the end members 22, 24 at predeter
`mined angular orientations relative to one another. HoWever,
`it should be understood that the sockets 46a, 46b and/or the
`end portions of the support rods 26 may be con?gured such
`that the angular orientation of the support rods 2