Ulllted States Patent [19]
`Henderson et al.
`
`[54] FUSION STABILIZATION CHAMBER
`
`[76] Inventors: Fraser C. Henderson; Rebecca
`Sasscer Henderson, both of 6705 S.
`Osborne Rd., Upper Marlboro, Md.
`20772' John W. Newman 27 Paper
`M111 Rd» NeWtOWn Square’ Pa- 19073
`
`.
`
`’
`
`’
`
`US006066175A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,066,175
`May 23, 2000
`
`5,059,193 10/1991 Kuslich .
`5,236,460
`8/1993 Barber .
`5,281,226
`1/1994 Da‘_’_Yd°V -
`572907312
`3/1994 Kollmoto et a1- -
`5397364 3/1995 Kozak et a1‘ '
`?efn?elrson et a1‘ '
`3/1999 Bray ........................................ .. 623/17
`
`,
`
`,
`
`5,888,223
`
`ic e son .
`
`[21] App] NO; 09/095,418
`
`[22]
`
`Filed:
`
`Jun_ 9 1998
`’
`
`.
`.
`Related U‘S‘ Apphcatlon Data
`
`[63]
`
`Continuation-in-part of application No. 08/891,513, Jul. 11, 1997, abandoned, Which is a continuation of application No.
`
`08/539,600, Oct. 5, 1995, abandoned, Which is a continua-
`tion_in_part of application I\IO~ 08/328’585’ Oct‘ 24’ 1994’
`abandoned, Which is a division of application No. 08/018,
`373, Feb. 16, 1993, Pat. No. 5,405,391.
`
`FOREIGN PATENT DOCUMENTS
`
`0179695 4/1986 European Pat. Off. .
`0322334 6/1989 European Pat. Off. .
`0526682 2/1993 European Pat. Off. .
`0 563 503 A1 10/1993 European Pat. Off. ............... .. 623/22
`
`
`
`"
`g 2 727 005 A1 5 1996 F 112222: """"""" " """"""""""""""""""" " 623 17
`
`
`/
`rance """"""""""""""""""" "
`/
`32 05 526 A1 9/1983 Germany ............................... .. 623/22
`4114644 4/1992 Japan -
`2004218 C1 12/1993 Russian Federation ............... .. 623/17
`1175464 8/1985 U.S.S.R. .
`
`. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
`
`U'S'S'R~ '
`
`[52] US. Cl. ......................................................... .. 623/17.11
`[58] Field of Search ............................................... .. 623/17
`
`8707827 12/1987 WIPO .
`9501763
`1/1995 WIPO -
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`1,357,714 11/1920 Lane.
`2,454,680 11/1948 Stephens.
`2,638,302
`5/1953 Reed.
`3,947,191
`3/1976 Milner .
`4,309,777
`1/1982 Patil .
`4,484,570 11/1984 Sutter et al. .
`4,501,269
`2/1985 Bagby .
`4,553,273 11/1985 Wu .
`4,554,914 11/1985 Kapp et al. .
`4,599,086
`7/1986 Doty.
`4,636,217
`1/1987 Ogilvie et al. .
`4,657,550
`4/1987 Daher.
`4,743,256
`5/1988 Brantigan .
`4,820,305
`4/1989 Harms et al. .
`4,863,476
`9/1989 Shepperd .
`4,878,915 11/1989 Brantigan .
`4,932,975
`6/1990 Main et al. .
`4,955,908
`9/1990 Frey et al. .
`4,961,740 10/1990 Ray et al. .
`5,002,576
`3/1991 Fuhrmann et al. .
`5,015,247
`5/1991 Michelson .
`
`OTHER PUBLICATIONS
`
`“Modular Segmental Spinal—Instrumentation” distr. by
`Fehling Medizintechnik GmbH.
`
`Primary Examiner—David H. Willse
`Attorney, Agent, or Firm—William H. Eilberg
`
`ABSTRACT
`
`[57]
`Afusion stabilization chamber stabilizes the spine following
`removal of one or more vertebrae, and facilitates bone
`growth. The chamber includes tWo holloW members, pref
`erably having slightly trapezoidal cross-sections, Which
`slide relative to each other in a telescoping manner. The
`holloW members preferably have Walls made of a metal
`mesh. Barrel vaults attached to the holloW members form
`guides for screWs Which can attach the chamber to the
`vertebrae adjacent the corpectomy site. Because of its
`adjustability, the chamber can ?t a Wide variety of corpec
`tomy sites. One can ?ll the chamber With bone material,
`Which can eventually fuse to the adjacent bone. A pair of
`stabilizing plates prevents the surgeon from pushing the
`chamber too far toWards the spinal cord. The chamber
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`1 of 20
`
`

`
`6,066,175
`Page 2
`
`eliminates the need to maintain a large and costly inventory
`of screws, and neurosurgeons can learn to use it quickly and
`easily. In another embodiment, the device is formed in one
`non-telescoping piece. An end portion of the holloW member
`includes a curved ?ange Which corresponds to the curvature
`of adjacent bone, and a notch Which facilitates engagement
`
`With such bone. The device can be made in different siZes,
`so that it can replace relatively large vertebral bodies, as Well
`as relatively small intervertebral discs.
`
`6 Claims, 11 Drawing Sheets
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`2 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 1 0f 11
`
`6,066,175
`
`FIGI
`
`FIGZ
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`3 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 2 0f 11
`
`6,066,175
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`4 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 3 0f 11
`
`6,066,175
`
`11
`
`{
`
`FIG.6
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`5 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 4 0f 11
`
`6,066,175
`
`FIG. 7
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`6 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 5 0f 11
`
`6,066,175
`
`7 .1541 ;
`4\/Q// / .
`
`FIGB
`
`FIG.9
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`7 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 6 0f 11
`
`6,066,175
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`8 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 7 0f 11
`
`6,066,175
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`9 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 8 0f 11
`
`6,066,175
`
`10]
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`10 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 9 0f 11
`
`6,066,175
`
`FIG.I4
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`11 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 10 0f 11
`
`6,066,175
`
`I19
`
`F I615
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`12 of 20
`
`

`
`U.S. Patent
`
`May 23, 2000
`
`Sheet 11 0f 11
`
`6,066,175
`
`FIG.I6
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`13 of 20
`
`

`
`1
`FUSION STABILIZATION CHAMBER
`
`CROSS-REFERENCE TO PRIOR APPLICATION
`
`This is a continuation-in-part of Ser. No. 08/891,513, ?led
`Jul. 11, 1997, noW abandoned, Which is a continuation of
`Ser. No. 08/539,600, ?led Oct. 5, 1995, noW abandoned,
`Which is a continuation-in-part of Us. patent application
`Ser. No. 08/328,585, ?led Oct. 24, 1994, noW abandoned,
`Which is a division of Ser. No. 08/018,373, ?led Feb. 16,
`1993, now US. Pat. No. 5,405,391.
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to the ?eld of neurosurgery,
`and provides a device Which facilitates the implantation of
`bone into the spine following removal of vertebrae, and
`Which also facilitates the fusion of the implanted bone With
`the surrounding bone. The invention also includes a method
`of performing spinal surgery, and in particular, of stabiliZing
`the spine folloWing removal of one or more vertebrae.
`Cancer or trauma or degenerative changes can cause parts
`of the human vertebrae to develop outgroWths or ridges that
`can touch the spinal cord and cause pain and/or paralysis.
`Neurosurgeons have developed means of treating such
`conditions, by removing part of the vertebrae, and, Where
`appropriate, replacing the removed bone With something
`else. The removal of all or part of a vertebra is called a
`“corpectomy” or a “vertebrectomy”. In some cases, one can
`replace the bone removed by corpectomy With bone taken
`from another site on the body of the patient; in other cases,
`one can obtain bone from a “bone bank”. Given the right
`conditions, the neW bone material Will fuse to the bone
`surrounding the corpectomy site, and can become for prac
`tical purposes a part of the patient’s body. To achieve the
`desired fusion, one must stabiliZe the spine so that the bone
`has time to fuse. The fusion process can take from six Weeks
`to six months.
`In performing spinal surgery, one can approach the spine
`either from the front (anterior) or rear (posterior) sides. The
`posterior approach has the disadvantage that since the ver
`tebrae lie on the anterior side of the spinal cord, the surgeon
`must navigate past the spinal cord before reaching the
`vertebrae, and must take special care not to disturb the spinal
`cord. Conversely, With the anterior approach, the surgeon
`does not encounter the spinal cord While en route to the
`vertebrae. The present invention concerns the anterior
`approach.
`The prior art contains many systems for stabiliZing vari
`ous parts of the spine folloWing surgery. The development of
`such systems has made it possible to treat certain lesions of
`the spine aggressively, instead of simply immobilizing them
`in a brace. The typical external immobilizing device of the
`prior art comprises the halo vest. The typical internal immo
`biliZing device comprises the Caspar plate, described beloW.
`The Caspar plate system, named after Dr. Wolfhard
`Caspar, comprises a means for stabiliZing the spine after
`anterior spinal surgery. The Caspar system includes a set of
`plates Which one attaches to the remaining vertebrae sur
`rounding the corpectomy site. In the Caspar procedure, one
`screWs a plate directly onto the spine, the screWs approach
`ing Within about one or tWo millimeters of the spinal cord.
`The Caspar system provides immediate stabiliZation of the
`spine folloWing a corpectomy, and in other cases Where the
`spine has become unstable folloWing an accident. The
`Caspar system also eliminates the need for Wearing the very
`cumbersome halo vest, and eliminates the need to undergo
`a separate surgical procedure from the rear.
`
`10
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`
`65
`
`6,066,175
`
`2
`HoWever, the Caspar system also has disadvantages. It
`requires a large inventory of expensive equipment, including
`screWs and plates of all siZes. The latter expense can
`represent a formidable obstacle to many medical institu
`tions. Also, one needs to insert the screWs through the spine,
`engaging the posterior cortex. Although one can monitor the
`position of the screWs With an appropriate real-time vieWing
`apparatus, the procedure carries the potential risk of spinal
`cord injury or laceration of the vertebral artery. When a
`competent surgeon performs the procedure, these complica
`tions rarely occur, but other complications such as loosening
`of the screWs and persistent instability may develop.
`Moreover, the dif?culty of the procedure discourages many
`surgeons from even attempting the anterior plating proce
`dure.
`The Synthes cervical spine locking plate constitutes
`another anterior plating system of the prior art. In the
`Synthes system, one inserts a second screW into the head of
`the anchor screW, thus creating a second af?xation of the
`plate to the vertebrae. Many regard the Synthes system as
`easier, safer, and faster to use than the Caspar plate system,
`because the anchor screW does not penetrate the posterior
`cortex and because one therefore does not need to monitor
`the precise position of the screW during insertion. HoWever,
`the Synthes locking plate has less versatility than the Caspar
`plate, as it provides the ability to fuse only tWo to three
`levels of the cervical spine.
`Both the Caspar and Synthes systems also have the
`disadvantage that they do not Work Well in patients With
`osteoporosis, rheumatoid arthritis, ankylosing spondylitis,
`and other conditions of poor bone groWth or metabolic bone
`disease.
`Both the Caspar and Synthes systems have additional
`disadvantages inherent With the use of screWs. First, as
`mentioned above, screWs do become loose. If one uses the
`screWs as the primary means of af?xing the stabiliZing
`device to the spine of the patient, loosening of the screWs
`represents a major problem. Moreover, the use of screWs
`presents a technical challenge to the surgeon. Correct screW
`placement requires experience, as Well as a large inventory
`of expensive equipment, as Well as imaging devices for
`monitoring the position of such screWs. Also, With screW
`based systems of the prior art, the surgeon must create a
`large opening in the patient, so as to vieW the screW along
`its shaft. Such an opening creates additional risks to the
`patient, such as the risk of injury to vascular structure and to
`nearby nerves.
`In addition to the problem of hoW to stabiliZe the spine
`immediately after performing a corpectomy, vertebral sur
`gery poses problems relating to the replacement of the
`removed bone. Some systems of the prior art require the use
`of a bone strut to replace the diseased bone segments
`removed in surgery. This bone grafting material costs a great
`deal, and sometimes one cannot obtain enough material
`When performing multiple vertebrectomies. Furthermore,
`bone graft material, usually taken from cadavers, has typi
`cally been steriliZed by radiation, a process believed to
`Weaken or destroy the strength and osteoconductive prop
`erties of bone. While it is possible to use other means of
`steriliZation, such as ethylene oxide or freeZe drying, it
`usually turns out that the best bone graft material comes
`from the patient, because the patient’s oWn bone Will likely
`fuse more rapidly than bone obtained elseWhere.
`Unfortunately, harvesting such bone consumes substantial
`time, involves substantial pain to the patient, and presents
`other risks, such as risk of infection at the harvest site,
`hemorrhage, and peripheral nerve injury.
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`14 of 20
`
`

`
`3
`The present invention overcomes the disadvantages of the
`prior art systems described above. First, the invention pro
`vides a device Which surgeons can learn to use very easily,
`and Which they can insert Without intraoperative ?uoroscopy
`or other means of accurately monitoring the position of a
`device Within the body. Most neurosurgeons can use the
`device of the present invention With instruments already in
`their possession.
`Secondly, the invention provides an adjustable device
`Which can ?t a large range of patients. This feature elimi
`nates the need to keep a large inventory of parts in order to
`accommodate every possible patient.
`Thirdly, the device alloWs one to use the patient’s oWn
`cancellous bone Which one removes during the
`vertebrectomy, possibly With the addition of further cancel
`lous bone material from an eXternal source. In any event, the
`invention reduces or eliminates the need to obtain a pelvic
`bone autograft from the patient.
`The device of the present invention also reduces or
`eliminates the problem of loosening of screWs, Which can
`occur With the plating systems of the prior art, and Which
`clearly can cause substantial pain and eXpense.
`
`10
`
`15
`
`SUMMARY OF THE INVENTION
`The fusion stabiliZation chamber of the present invention
`includes a pair of holloW members, both of Which may have
`a rectangular or slightly trapeZoidal cross-section. One of the
`holloW members slides Within the other. Thus, the chamber
`comprises tWo telescoping holloW members. Each holloW
`member includes at least one barrel vault at one end, each
`barrel vault comprising threaded means for receiving a
`screW. The barrel vaults are arranged in a mutually oblique
`manner, such that the screWs inserted into the vaults also lie
`along mutually oblique lines. The holloW members prefer
`ably comprise enclosures de?ned by four Walls formed of a
`metal mesh. The holloW members may also include means
`for locking the members in a desired position relative to each
`other.
`In using the stabiliZation chamber described above, the
`surgeon ?rst removes the diseased portion of vertebra in the
`usual manner. The surgeon measures the length of the
`corpectomy site (the length of the space to be ?lled), and
`adjusts the length of the chamber accordingly. One may
`fasten the locking means so that the telescoping chamber
`maintains its desired position. Then, the surgeon ?lls the
`chamber With bone material, such as bone chips obtained
`from the corpectomy operation itself, or bone material from
`other sources, and inserts the chamber into the corpectomy
`site. The surgeon gently taps the device into place, so that it
`?lls most of the corpectomy site, i.e. the space formerly
`occupied by the removed vertebra. The chamber does not
`eXtend all of the Way toWards the spinal cord, due to the
`retaining action of a pair of stabiliZing plates.
`The surgeon then drills holes in the surrounding bone,
`using the barrel vaults as guides for the drill bit. The surgeon
`then inserts the screWs through the barrel vaults and fastens
`them to the bone. Due to the orientation of the barrel vaults,
`the screWs lie along mutually oblique paths, reducing the
`likelihood that the device Will become dislodged.
`In an alternative embodiment, one can provide threaded
`holes in the stabiliZing plates also, so that additional screWs
`can pass directly through the stabiliZing plates and into the
`surrounding bone.
`In another alternative embodiment, the fusion stabiliZa
`tion chamber includes a single member and does not tele
`scope. Like the ?rst embodiment, the single member has an
`
`25
`
`35
`
`45
`
`55
`
`65
`
`6,066,175
`
`4
`open mesh structure Which is ?lled With bone chips or any
`bone substitute or bone morphogenetic protein. This
`embodiment is especially suited for use in ?lling the space
`created after removal of an intervertebral disc. The mesh
`structure also includes ?anges Which serve to anchor the
`device and attach it to adjacent vertebrae, and prevent it
`from contacting the spinal cord, and barrel vaults to facilitate
`attachment and stabiliZation of the device. The device can
`also include a separate top plate Which is af?Xed to the top
`of the chamber by screWs.
`In another embodiment, the chamber comprises a single,
`non-telescoping member Which includes an end portion
`having ?anges and screW holes. The ?anges are preferably
`curved so that they correspond to the curvature of the
`surrounding bone. Also, the ?anges and the chamber
`together de?ne notches Which engage edges of adjacent
`vertebrae When the device is in use. An access hole in the
`end portion facilitates the ?lling of the interior of the
`chamber With bone fragments. The chamber has a trapeZoi
`dal cross-section When vieWed in each of at least tWo
`mutually-orthogonal directions.
`The present invention therefore has the primary object of
`providing an improved method and apparatus for performing
`spinal surgery, and in particular, for stabiliZing the spine
`folloWing removal of one or more vertebrae.
`The invention has the further object of providing a device
`Which promotes bone fusion in addition to providing stabi
`liZation of the spine.
`The invention has the further object of simplifying the
`surgical process of stabiliZing the spine after performing a
`corpectomy.
`The invention has the further object of reducing the cost
`and complexity of the equipment needed to practice spinal
`surgery.
`The invention has the further object of reducing the time
`required for a surgeon to learn to stabiliZe the spine folloW
`ing a corpectomy.
`The invention has the further object of providing an
`apparatus and method for promoting fusion of bone in a
`space betWeen adjacent vertebrae, folloWing removal of an
`intervertebral disc.
`Persons skilled in the art Will recogniZe other objects and
`advantages of the invention, from a reading of the folloWing
`brief description of the draWings, the detailed description of
`the invention, and the appended claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 provides a side elevational vieW of the fusion
`stabiliZation chamber of the present invention.
`FIG. 2 shoWs an end vieW of the stabiliZation chamber of
`the present invention.
`FIG. 3 provides a perspective vieW of the fusion stabili
`Zation chamber.
`FIG. 4 shoWs a top vieW of the stabiliZation chamber.
`FIG. 5 provides a diagrammatic vieW shoWing the fusion
`stabiliZation chamber inserted into a corpectomy site.
`FIG. 6 provides a perspective vieW of an alternative
`embodiment of the invention, Wherein additional screWs
`pass directly through the stabiliZing plates.
`FIG. 7 provides a perspective vieW, similar to that of FIG.
`3, shoWing an embodiment in Which the fusion stabiliZation
`chamber is curved to ?t the curvature of the spine.
`FIG. 8 provides a cross-sectional side elevational vieW of
`another alternative embodiment of the present invention.
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`15 of 20
`
`

`
`6,066,175
`
`5
`FIG. 9 provides a top vieW of the device shown in FIG.
`
`8.
`
`FIG. 10 provides an exploded perspective vieW of a
`non-telescoping fusion stabilization chamber having a sepa
`rate top plate, according to the present invention.
`FIG. 11 provides a perspective vieW of a non-telescoping
`device having a separate top plate, Which device is intended
`for use in ?lling the space betWeen vertebrae, folloWing
`removal of an intervertebral disc.
`FIG. 12 provides a perspective vieW of a fusion stabili
`zation chamber made according to another embodiment of
`the present invention.
`FIG. 13a provides an end vieW of the fusion stabilization
`chamber of FIG. 12.
`FIG. 13b provides a side vieW of the fusion stabilization
`chamber of FIG. 12.
`FIG. 13c provides a top vieW of the fusion stabilization
`chamber of FIG. 12.
`FIG. 14 provides a coronal, or antero-posterior vieW of
`the fusion stabilization chamber of FIG. 12 inserted betWeen
`vertebrae.
`FIG. 15 provides a sagittal vieW of the fusion stabilization
`chamber of FIG. 12 inserted betWeen vertebrae.
`FIG. 16 provides an axial cross-sectional vieW shoWing
`the fusion stabilization chamber of FIG. 12 inserted betWeen
`vertebra.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`FIGS. 1—4 shoW the physical structure of the fusion
`stabilization chamber of the present invention. The chamber
`includes ?rst holloW member 1 and second holloW member
`3. Both holloW members have a slightly trapezoidal cross
`section, as illustrated in the end vieW of FIG. 2. FIG. 2
`exaggerates the trapezoidal shape of the cross-section: in
`practice, the Width of the member might increase by one
`millimeter for each 15 mm of depth, but one could use other
`dimensions. Thus, by “slightly trapezoidal”, one means that
`the members are nearly rectangular in cross-section, except
`for the variation in Width described above. The trapezoidal
`cross-section helps to maintain the chamber in position
`Within the corpectomy site. One inserts the narroWer portion
`of the holloW member into the body cavity ?rst, With the
`Wider portion oriented toWards the outside. Thus, the cham
`ber tends to become Wedged in its place Within the corpec
`tomy site; once pushed in, it becomes dif?cult to pull out.
`Although the preferred embodiment includes the trapezoidal
`cross-section, one can also form the chamber With a per
`fectly rectangular cross-section, Within the scope of the
`invention.
`The ?rst holloW member 1 slides Within the second
`holloW member 3. The members 1 and 3 preferably have
`Walls formed of metal mesh 5. One prefers Walls having
`openings Which permit bone groWth from the adjacent
`vertebrae, through the interior of the chamber. HoWever, the
`Walls can have a different construction. They can even
`comprise solid metal, as bone can fuse to metal. In the latter
`case, the chamber could be empty.
`In the preferred embodiment, the chamber has tWo pairs
`of barrel vaults 7, arranged at the opposite ends of the holloW
`members. One can vary the number of barrel vaults, Within
`the scope of the invention. The barrel vaults comprise
`threaded cylinders through Which screWs 9 pass. FIG. 1
`shoWs that the screWs form an angle of about 30° relative to
`the top longitudinal axis of the chamber. FIG. 4 shoWs that
`
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`
`40
`
`45
`
`55
`
`60
`
`65
`
`6
`the screWs also form an angle of about 10° relative to the
`sides of the chamber. One can vary these angles; one should
`not consider the invention limited to particular angles. In
`general, one selects angles Which enable the screWs to pass
`through the greatest possible thickness of bone, above and
`beloW the corpectomy site, and to provide an angle Which,
`from the perspective of the surgeon, facilitates insertion of
`the screWs Without the need to make a larger or additional
`incision.
`As shoWn in the Figures, the barrel vaults comprise
`mutually oblique members. The screWs become self-locking
`in the barrel vaults. One can also provide an adjustable
`hexagonal head screWdriver to facilitate tightening of the
`screWs from any angle.
`Locking screW 11 holds the ?rst and second holloW
`members in place. The locking screW thus permits adjust
`ment of the size of the chamber. One slides the holloW
`members until the chamber has the desired length, and then
`?xes the selected length by tightening the locking screW.
`FIG. 5 provides a diagram of the fusion stabilization
`chamber inserted into a corpectomy site. The ?gure shoWs
`vertebrae 15, the spaces 17 betWeen adjacent vertebrae
`representing intervertebral discs. Each vertebra includes an
`outer bony layer, or cortex 27, Which surrounds cancellous
`material 29 inside. FIG. 5 also shoWs spinal cord 19, and the
`structures adjoining the spinal cord, including the posterior
`longitudinal ligament 21, the ligamentum ?avum 23, and the
`posterior spinous processes 25. As shoWn in the ?gure, one
`has removed several vertebrae, and has inserted the chamber
`into the resulting empty space.
`Stabilizing plates 13 extend from both holloW members,
`as shoWn in the Figures. The stabilizing plates serve several
`purposes. First, as illustrated in FIG. 5, the stabilizing plates
`keep the chamber at an appropriate depth, preventing the
`chamber from touching spinal cord 19 or the ligaments
`surrounding it. By making the depth of the chamber less than
`the depth of the adjacent vertebrae, one prevents the cham
`ber from coming too close to the spinal cord.
`Secondly, the stabilizing plates tend to distribute the
`bending loads experienced by the chamber, and divert part
`of these loads aWay from the screWs. As the vertebrae ?ex
`back and forth, the stabilizing plates tend to oppose some of
`the vertebral movement, and absorb some of the tension,
`thereby tending to prevent the screWs from loosening or
`breaking.
`Thirdly, the stabilizing plates help to rigidify the joints
`formed betWeen the ends of the chamber and the respective
`adjacent vertebrae. Keeping these joints rigid facilitates the
`groWth of blood vessels from the adjacent vertebrae, through
`the holes in the chamber Walls, and into the bone material
`Within the chamber.
`FIG. 6 shoWs, in a perspective vieW, an alternative
`embodiment Wherein a third screW passes through a
`threaded hole in each stabilizing plate, in addition to the pair
`of screWs inserted through the associated barrel vaults. FIG.
`6 shoWs additional screW 10 inserted through the stabilizing
`plate on the right-hand side. The ?gure does not shoW the
`corresponding additional screW on the other side, in order to
`shoW the hole in the stabilizing plate, but in practice a
`similar additional screW 10 Would normally be provided.
`HoWever, one should consider each screW as optional, since
`it is possible to af?x the chamber to the adjacent bone using
`feWer than all of the available screWs.
`One Would use the embodiment of FIG. 6 in cases Where
`the bone has become Weakened. In rare cases, one might
`even attach the chamber only With the stabilizing plate
`
`DePuy Synthes Sales, Inc. & Depuy Synthes Sales, Inc.
`Exhibit 1007
`16 of 20
`
`

`
`6,066,175
`
`7
`screws, Without any barrel vault screws. In all of the
`embodiments Wherein one provides a threaded hole in the
`stabilizing plate, the holes should have loW “pro?les”, so
`that the material de?ning the plate does not project signi?
`cantly beyond the plane of the plate.
`In using the chamber of the present invention, the surgeon
`begins by performing a corpectomy in the conventional
`manner. Immediately after removal of one or more
`vertebrae, the surgeon measures the length of the corpec
`tomy site With calipers, and adjusts the length of the cham
`ber to make it conform to the length of the corpectomy site.
`One adjusts the length of the chamber by pulling the holloW
`members 1 and 3 aWay from each other or pushing them
`together, as needed. Then one tightens the locking screW 11
`to ?x the length (and thus the volume) of the chamber.
`Next, the surgeon ?lls the chamber With bone. The bone
`can comprise bone chips obtained from the vertebrae
`removed in the corpectomy procedure, or it can comprise
`cancellous bone obtained from another site. One might also
`use a biocompatible osteogenic polymer.
`In a variation of the latter step, the surgeon may place
`bone chips, obtained from the corpectomy, into the chamber,
`While the corpectomy progresses. HoWever, in this case, one
`Would still need to adjust the chamber to ?t the corpectomy
`site, and one Would also need to insure that the bone has
`substantially ?lled the volume of the chamber after adjust
`ment of the siZe of the chamber.
`The surgeon then inserts the bone-?lled chamber into the
`corpectomy site, and gently taps it into place, such that the
`stabiliZation plates 13 come to rest on the vertebrae imme
`diately adjacent to the corpectomy site. The chamber should
`?t tightly Within the corpectomy site. One may take a lateral
`spine X-ray to insure that the chamber has seated itself
`properly in the corpectomy site.
`Next, the surgeon drills holes into the adjacent vertebrae,
`using an appropriate drill, such as a 2 mm tWist drill. The
`barrel vaults 7 form guides for the drill bit, and thereby
`determine the direction of the holes. The orientation of the
`barrel vaults unambiguously determines the orientation of
`the holes. The holes therefore make the same angles as the
`barrel vaults, relative to the axes of the chamber.
`The surgeon then threads the screWs 9 into the barrel
`vaults 7. The barrel vaults direct the screWs along the correct
`path. Due to the interaction of the heads of screWs 9 With the
`barrel vaults, the barrel vaults also insure that the screWs 9
`become inserted to the correct depth. When tightened, the
`screWs 9 tend to draW the adjacent vertebrae toWards the
`chamber. Note also that the screWs pass tWice through the
`cortex of the vertebrae. In other Words, each screW has a
`length suf?cient to pass through the cortex 27 at one surface
`of the vertebra, then through the cancellous material 29 at
`the core of the vertebra, and again through the cortex as the
`screW exits the vertebra. Fastening the screWs in this manner
`minimiZes the likelihood that the screWs Will become dis
`lodged.
`FolloWing the tightening of the screWs, one can take a
`lateral X-ray to verify proper placement of the screWs. If all
`is correct, one can then close the Wound in the conventional
`manner.
`The present invention has many advantages, as outlined
`beloW:
`1. The fusion stabiliZation chamber does not rely on
`screWs as the sole means of stabiliZing the spine folloWing
`surgery. Due to the trapeZoidal cross-section of the chamber,
`the chamber becomes ?rmly Wedged Within the corpectomy
`site even before attachment of the screws.
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`8
`2. The surgeon can learn to insert the fusion stabiliZation
`chamber much more quickly than devices of the prior art.
`Since the barrel vaults automatically determine the direction
`and depth of the screWs, the surgeon Will be less likely to
`make mistakes While using the present invention, and the
`invention therefore is less intimidating to the surgeon than
`devices of the prior art. In particular, the oblique direction of
`the screWs lessens the potential damage to the spinal cord.
`Moreover, most neurosurgeons can use the fusion stabiliZa
`tion chamber With instruments already in their possession.
`3. The oblique direction of the screWs has the added
`bene?t that it increases the compression effect, by draWing
`vertebrae above and beloW the chamber into ?rm contact
`With the chamber. Such compression speeds fusion of the
`bone.
`4. The oblique direction of the screWs has the additional
`advantage of reducing the required siZe of the surgical
`incision, because the surgeon can reach deeply into adjacent
`vertebrae, using the screWs, Without exposing those verte
`brae.
`5. Because of the ease and manner of insertion of the
`device, the surgeon need not use intraoperative ?uoroscopy,
`or other monitoring means, While inserting the device.
`6. The present invention eliminates the need for a large
`inventory of stabiliZation plates and screWs for ?tting dif
`ferent siZes of verteb