PCT
`
`International Bureau
`WORLD INTELLECTUAL PROPERTY ORGANIZATION
`
`
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`(51) International Patent Classification 4 =
`(11) International Publication Number:
`W0 89/ 09035
`
`A61F 2I44
`
`(43) International publication Date:
`
`5 October 1989 (05.10.89)
`
`(21) International Application Number:
`
`PCT/U889/00905
`
`SD, SE, SN (OAPI patent), SU, TD (OAPI patent),
`TG (OAPI patent).
`
`(22) International Filing Date:
`
`10 March 1989 (10.03.89)
`
`(31) Priority Application Number:
`
`Published
`With international search report.
`
`173,928
`
`(32) Priority Date:
`
`28 March 1988 (28.03.88)
`
`(33) Priority Country:
`
`US
`
`(71x72) Applicant and Inventor: BRANTIGAN, John, W.
`[US/US]; 2108 Bramblewood Lane, Fremont, NE
`68025 (US).
`
`(74) Agent: LEHMAN, Edward, A.; Hill, Van Santen,
`Steadman & Simpson, 70th Floor, Sears Tower, Chi—
`cago, IL 60606 (US).
`
`(81) Designated States: AU, BB, BG, B.) (OAPI patent), BR,
`CF (OAPI patent), CG (OAPI patent), CM (OAPI pa-
`tent), DK, F1, GA (OAPI patent), HU, JP, KP, KR,
`LK, LU, MC, MG, ML (OAPI patent), MR (OAPI pa—
`tent), MW, NL, NO, R0,
`
`1 N
`
`54) Title: SURGICAL PROSTHETIC IMPLANT FACILITATING VERTEBRAL INTERBODY FUSION
`
`(57) Abstract
`
`Prosthesis plug implants (11, 31-34, 111) forming side—by—side transverse struts between adjacent vertebrae have
`roughened surfaces (1 lb, 31b, 32b, 34d, 122) receiving bone ingrowth to fuse the plugs on prepared surface sites (15, 115)
`on opposed faces of adjacent vertebrae and have end faces (11a, 31a, 34a, lllc) with tool receiving recesses (19, 111d) sec-
`uring the plug on a tool (24, 120) for insertion on the prepared sites of the vertebrae and for removing the tool from the
`plug without disturbing its position on the sites. These sites can be prepared by feeding a drill (21) through a guide (22)
`fixed to posterior or anterior sides of adjacent vertebrae to form the prepared sites including cortex bone (18, 118) in the
`opposed faces of the adjacent vertebrae and terminating the drilling in advance of the opposite sides of the vertebrae (l6,
`1 16). Gauge blocks (119) may be used to stretch collapsed disc tissue (1 12a) between the vertebrae to reclaim normal disc
`space between the vertebrae. A preferred implant (111) is rectangular, has nubs (122) on the sidewalls thereof, slots
`(124-125) receiving bone graft material (26) and is formed of radiolucent material.
`
`UVASIVE1005
`
`1
`
`

`

`FOR THE PURPOSES OFINFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages ofpamphlets publishing international appli-
`cations under the PCT.
`'
`
`I
`
`AT Austria
`AU Australia
`BB Barbados
`BE Belgium
`BG Bulgaria
`BJ ' Benin
`BR Brazil
`CF Central African Republic
`CG Congo
`CH Switzerland
`CM Cameroon
`DE Germany, Federal Republic of
`DK Denmark
`Fl
`Finland
`
`FR
`
`,
`
`,
`
`7
`
`France
`Gabon
`United Kingdom
`Hungary
`Italy
`Japan
`Democratic People‘s Republic
`of Korea
`Republic of Korea
`Liechtenstein
`Sri Lanka
`Luxembou
`Monaco
`Madagascar
`
`'
`
`ML Mali
`MR Mauritania
`MW Malawi
`NL Netherlands
`N0 Norway
`R0 Romania
`SD Sudan
`SE
`Sweden
`SN Senegal
`SU Soviet Union
`TD Chad
`TG Togo
`US United States of America
`
`2
`
`

`

`wo 89/09035
`
`PCT[USS9/00905
`
`"SURGICAL PROSTHETIC IMPLANT FACILITATING
`
`VERTEBRAL INTERBODY FUSION"
`
`This invention relates to the art of
`
`prosthetic devices inserted transversely in a
`
`vertebral column on prepared sites of the opposed
`
`faces of adjacent vertebrae forming struts which are
`
`fused into the vertebrae to maintain a normal disc
`
`space between the vertebrae. These devices are in the
`
`form of rigid inert plugs spanning the disc space in
`
`side-by—side relation and having roughened surfaces
`
`facilitating ingrowth of bone tissue.
`
`The plugs are mounted endwise on a tool
`
`to
`
`facilitate insertion between the adjacent vertebrae,
`
`have a height that will reclaim the normal disc space
`
`and will stretch remaining tissue of a collapsed
`
`damaged disc. Preferred plugs have barbs biting into
`
`the vertebrae, slots for carrying bone graft material,
`
`tapered leading ends facilitating insertion between
`
`the vertebrae and are formed from a radiolucent
`
`10
`
`15
`
`20
`
`material.
`
`As pointed out in my United States Patent
`
`4,743,256,
`
`issued May 10, 1988,
`
`the leading cause of
`
`low backpain arises from rupture or degeneration of
`
`lumbar intervertebral discs.
`
`Pain in the lower
`
`extremeties of the back (sciatica) is caused by
`
`compression of spinal nerve roots by damaged discs
`
`between the vertebrae and low back pain is caused by
`
`collapse of the disc and the adverse effects of
`
`bearing the majority of the body weight through a
`
`damaged unstable vertebral joint. Surgical treatments
`
`for relief of the sciatic pain and lower back pain
`
`generally include the following:
`
`25
`
`30
`
`3
`
`

`

`wo 89109035
`
`PCT[USS9/00905
`
`l.)'
`
`Excision Of The Ruptured Soft Disc
`
`This procedure removes the portion of the
`
`disc compressing the spinal nerve and is generally
`
`successful in relieving the sciatic leg pain but in
`
`more than half of the cases,
`
`there is a recurrence of
`
`' back pain. Over a period of time the disc gradually
`
`loses height due to the rupture and this loss of
`
`height causes the posterior facet joints of the
`
`'10
`
`vertebrae to fit incorrectly resulting in arthritic
`change in all elements of the spinal segment.
`
`15
`
`2O
`
`25
`
`30
`
`Recurrent nerve root compression due to bony
`The
`encroachment (spinal stenosis) also develops.
`continuing and recurring back pain from this source
`has created a leading source of pain and disability.
`2.)
`Disc Excision With Posterior Fusion
`
`Traditional posterior fusion, creating
`
`bone growth between the bony laminae, or
`
`postero-lateral fusion between the transverse
`
`processes prevents motion between the adjacent
`
`vertebrae but does not alter the fact that
`
`approximately 90% of the body weight must be
`transmitted through degenerated discs causing pain.
`
`Further, posterior fusion tends to cause bony
`
`overgrowth leading to nerve root compression by spinal
`
`stenosis.r
`Disc Excision With Anterior Interbody Fusion
`3.)
`Interbody fusion techniques,
`in which the
`soft disc is completely excised and replaced with
`
`either the patient's own bone (autologous bone) or
`
`with tranSplant banked bone (homologous bone) are
`
`generally successful if solid.fusion can be obtained
`
`between adjacent vertebrae bodies. Unfortunately,
`success rate has only been about 50%.
`
`the
`
`4
`
`

`

`WO 89/09035
`
`PCT/US89/00905
`
`4.)
`
`Disc Excision With Posterior Lumbar
`
`Intervertebral Fusion (PLIF)
`
`.
`
`This procedure reconstructs the normal
`
`anatomic relationships between the bony and the neural
`
`structures and has many advantages. Weight bearing
`
`through a solid bony fusion mass between vertebral
`
`bodies relieves the mechanical pain of the traditional
`
`unstable degenerative disc and generally prevents long
`
`term disc collapse or further degenerative changes.
`
`10
`
`The complete disc excision prevents recurrent
`
`15
`
`20
`
`25
`
`30
`
`herniation of the same degenerated disc.
`
`However,
`
`this PLIF procedure has several
`
`serious disadvantages in that it is technically very
`
`difficult, and,
`
`therefore, not as successful or widely
`
`used as it might be.
`
`It entails large amounts of
`
`blood loss in a small deep hole causing physiological
`
`stress to the patient and psychological distress to
`
`the surgeon. Further,
`
`the use of autologous bone
`
`graft from the patient's own iliac crests extends the
`
`operation and creates a second painful operative site.
`
`Because it is difficult to obtain a large enough
`
`quantity of autogenous bone with sufficient strength,
`
`homologous bank bone is generally used.
`
`Interbody bone grafting involves the
`
`problems of strength and that of bone incorporation.
`
`Strong cortex bone (the outer layer) is required as a
`
`strut in the interbody position to prevent collapse of
`
`the disc space while healing occurs.
`
`The surgeon has
`
`the unfortunate requirement of having to fashion the
`
`required struts with handheld tools during the
`
`operation and these cortex bone struts are not wide
`
`enough for optimum load bearing and they anchor
`
`themselves by healing process that occurs very slowly
`
`5
`
`

`

`wo 89/09035
`
`PCT/USB9/00905
`
`over a matter of years. Further, soft cancellous
`
`bone, which heals more reliably over a matter of 12 to
`
`18 months, is also required for a traditional
`
`interbody fusion.
`
`5
`
`It is well understood in orthopaedic
`
`surgery, that grafted bone heals by a process called
`"creeping substitution" in which blood capillaries
`
`first grow into the grafted bone,
`
`the grafted bone is
`
`reabsorbed, and then new bone cells are laid down
`
`10
`
`along the bony matrix of the graft. During the time
`that the structural bone grafts struts are being
`
`reabsorbed, motion must still be prevented in the
`
`involved segments and although a brace or cast is
`
`often used,
`
`the entire process has proven less
`
`15
`
`reliable than desired. Homologous bank bone, being
`
`more "foreign", requires a much longer time to grow
`
`together and has a higher failure rate estimated at
`three times the failure as with the patient's own
`
`bone.
`
`In effect, neither source of bone is optimum
`
`20
`
`for the fusion procedure.
`
`My prior aforesaid U. S. Patent
`
`4,743,256, discloses an improved surgical procedure
`
`for eliminating spinal back pain caused by ruptured or
`
`degenerated vertebral discs by spanning the disc space
`between adjacent vertebrae with rigid implants having
`
`25
`
`surfaces facilitating bone ingrowth and bottomed on
`
`prepared sites of the vertebrae to integrate the
`
`implant with the vertebrae and to provide a permanent
`
`weight supporting strut maintaining the disc space.
`
`30
`
`The present invention now further
`
`improves the art by providing the rigid implants with
`
`tool receiving end faces facilitating their insertion
`
`onto the prepared sites and having geometric patterns
`
`6
`
`

`

`WO 89/09035
`
`PCT/U589/00905
`
`of roughened surfaces on the peripheries of the
`
`implants enhancing bone ingrowth. This invention also
`
`still further improves the art by refining the implant
`
`method with novel tools.
`
`According to the invention rigid plugs of
`
`the type generally disclosed in my aforesaid U.S.
`
`Patent 4,743,256 are further improved by providing end
`
`faces thereon with tool receiving recesses
`
`facilitating insertion of the plugs into place on the
`
`prepared sites of adjacent vertebrae and having
`
`roughened peripheral surfaces with patterns
`
`facilitating placement between the vertebrae, and
`
`enhancing bone ingrowth.
`
`The preferred plugs have one
`
`end thereof provded with an internally threaded axial
`
`hole and wings or slots radiating from this hole in
`
`the end face.
`
`An insertion tool is threaded into the
`
`hole and is surrounded by a sleeve fitted into the
`
`slot recess.
`
`The plug, supported endwise on the tool
`
`10
`
`15
`
`is inserted in prepared sites of the adjacent
`
`20‘
`
`vertebrae and when properly positioned,
`
`the sleeve is
`
`held against rotation and the tool unthreaded from the
`
`plug without shifting the plug.
`
`The sites are preferably formed by a
`
`drill surrounded by a drill guard with projecting
`
`25
`
`teeth embedded in the posterior ends of adjacent
`
`vertebrae to correctly position the drill for forming
`
`channels in the opposed faces of adjacent vertebrae.
`
`The channels are sufficiently wide and long to include
`
`hard cortex bone but preferably do not extend
`
`30
`
`completely through the anterior side of the vertebrae.
`
`Conversely, if the drill is inserted from the anterior
`
`site of the vertebrae,
`
`the drilling operation is
`
`stopped short of the posterior side.
`
`7
`
`

`

`WO 89/09035
`
`r
`
`PCT/USS9/00905
`
`As disclosed in my aforesaid Patent
`
`the plugs are made of an inert rigid metal,
`4,743,256,
`such as stainless Steel, cobalt—chromium-molybdenum
`
`alloys,
`
`titanium or the like. According to this
`
`invention, however,
`the peripheral surface of these
`plugs need not have a porous coating of metal
`particles, such as disclosed in my prior application,
`but can be provided with roughened surfaces forming
`pits, prongs, bristles, nubs, or the like
`
`10
`
`irregularities for anchoring bone ingrowth. These
`
`roughened surfaces can be part of the plug body or a
`coating on the body, such as a resin polymer. Bristle
`
`or prong surfaces can be rigid or flexible and, if
`
`desired, shaped to facilitate insertion and resist
`
`15
`
`retraction.
`
`A preferred threaded hole in the end face
`
`of the plug terminates less than one half the length
`
`of the plug and has a diameter of less than 1/3 the
`
`20
`
`diameter of the plug.
`The wing or slot radiates
`diametrically from the hole in the end face of the
`
`plug, but terminates inwardly from the periphery of-
`
`25
`
`30
`
`the plug.
`
`A preferred polymer coating to form the
`'
`'
`roughened surface is nylon, a poly-olefin, a vinyl, or
`the like resin resistent to deterioration in the
`
`environment of the implant.
`
`The present invention now also provides
`
`rectangular vertebral prosthesis implant plugs or
`blocks fitting rectangular transverse or perpendicular
`
`channels or grooves cut in the adjoining faces of
`
`vertebral bodies having heights that will stretch the
`remaining annulus tissue of the discs therebetween
`still connecting the vertebrae. Flat-sided
`
`8
`
`

`

`WO 89/09035
`
`PCT/USS9/00905
`
`rectangular or square blocks or plugs are provided to
`
`fit these transverse rectangular channels or slots and
`
`have beveled or tapered leading ends easily inserted
`
`into the open ends of the transverse slots to spread
`
`the vertebrae apart so that the top and bottOm faces
`
`of each block or plug are tightly bottomed in the slot
`
`with the stretched disc tissues causing the vertebrae
`
`to grip the plugs.
`
`These plugs are inserted laterally
`
`or transversely of the vertebral column into the slots
`
`while mounted on the end of an insertion tool, have
`
`roughened surfaces to facilitate the bone ingrowth and
`
`also have vertical or horizontal slots therethrough or
`
`intersecting vertical and horizontal slots, packed
`
`with bone graft material, such as strips of bone
`
`excised from the iliac crest of the pelvis. This
`
`implant material provides a block of livng bone that
`
`grows all around and through the implant plug into the
`bone of the vertebrae.
`
`Also, according to this invention,
`
`the blocks or
`
`plugs instead of being made of an inert metal, can be
`
`made of a radiolucent material, such as a plastic of
`
`the nylon, polycarbonate, polypropylene, polyacetal,
`
`polyethylene, and polysulfone type, preferably filled
`
`with glass or carbon fibers. These plastics can be
`
`injection molded, are light in weight, have great load
`
`carrying strength and provide improved x-ray
`
`visualisation of bone healing. Fiber reinforced
`
`plastics composed of such materials filled with glass
`
`or carbon fibers are also desirable. Suitable carbon
`
`fiber composites are supplied under the tradename
`
`"VICTREX P.E.S." which is polyether sulfone filled
`
`with carbon fibers. Suitable grades are "4101
`
`G.L.-30" which is a 30 percent fiber glass filled and
`
`10
`
`15
`
`20
`
`25
`
`30
`
`9
`
`

`

`wo 39109035
`
`,
`
`PCT/USS9/00905
`
`"450 C.A.—30" which isra 30 percent carbon fiber
`
`filled. These materials are supplied from ICI
`
`Industries of Wilmington, Delaware. Carbon-carbon
`
`fiber plastics of the type sold by Fiber-Rite
`
`S
`
`Corporation of Winona, Minnesota, are useful.
`
`Preferred embodiments of the invention are
`
`illustrated in the annexed drawings in which:
`
`FIG.
`
`1 is a side elevational view of the
`
`lower portion of a human vertebral column with parts
`
`10
`
`broken away and shown in section to illustrate
`
`prosthetic implants of this invention inserted between
`
`several of the lower vertebrae.
`
`FIG. 2 is a posterior elevational view of
`a portion of FIGURE 1 taken along the line 11—11 of
`FIGURE 1 .
`7
`
`15
`
`FIG. 3 is a cross-sectional view with
`
`parts in elevation and broken away in section along
`the line III-III of FIGURE 2.
`
`FIG- 4 is an enlarged fragmentary side
`elevational View with parts shown in vertical section
`
`20
`
`illustrating the manner in which the implant receiving
`
`sites of adjacent vertebrae are prepared.
`
`FIG. 5 is a View similar to FIGURE 4
`
`illustrating the manner in which an implant is
`
`25
`
`inserted in position on prepared sites of adjacent
`vertebrae.
`
`' FIG.
`
`6 is a perspective View of one form
`
`of a prosthetic plug of this invention having a
`
`30
`
`knurled periphery and shOwing the tool receiving
`recesses in an end therof.
`FIG. 7 isra perspective view of another
`
`form of implant plug of this invention having a pitted
`
`periphery.
`
`1O
`
`10
`
`

`

`WO 89/09035
`
`PCT/USS9/00905
`
`FIG.
`
`8 is a side elevational view with
`
`parts broken away and showing an axial section of a
`
`prosthetic plug of this invention with deflectable
`
`locking prongs on the periphery thereof.
`
`FIG.
`
`9 is a perspective View similar to
`
`FIGURE 6 illustrating a threaded periphery on the plug
`
`providing roughened surfaces.
`
`FIG. 10 is a perspective view of a
`
`prosthetic plug of this invention with a resin coating
`
`10
`
`thereof having radiating bristles.
`
`FIG. 11 is a transverse sectional View
`
`along the line XI—XI of FIGURE 10.
`
`FIG. 12 is a side-elevational view of the
`
`15
`
`20
`
`25
`
`30
`
`lower portion of a human vertebrae column with parts
`
`broken away and shown in section to illustrate
`
`flat-sided rectangular prosthetic implant plugs or
`
`blocks of this invention inserted in rectangular
`
`grooves or channels in the opposed faces of adjacent
`
`vertebrae to support the vertebrae in place of the
`
`human disc therebetween which has been partially
`
`excised to remove damaged and herniated tissue.
`
`FIG. 13 is a posterior elevational view
`
`of a portion of FIGURE 12 taken along the line
`
`XIII-XIII of FIGURE 12.
`
`FIG. 14 is a transverse sectional View,
`
`with parts in elevation and broken away in section,
`
`along the line XIV-XIV of FIGURE 13.
`
`FIG. 15 is an enlarged fragmentary side
`
`elevational view, with parts broken away and shown in
`
`vertical section, illustrating the manner in which a
`
`trial or gauge plug or block of this invention is
`
`inserted in position in the transverse rectangular
`
`slots of adjoining vertebrae to stretch the remaining
`
`11
`
`11
`
`

`

`wo 89/09035
`
`PCT/USS9/00905
`
`, _ 10 _
`
`interposed disc tissue connected to these vertebrae
`
`and to gauge the sites for receiving a proper sized
`
`permanent implant.
`
`FIG. 16 is a plan view of a vertebrae
`
`disc with the interior pulp removed and with disc
`
`tissue partially excised to provide gaps or slots
`
`aligned with channels cit in the vertebrae to receive
`the plugs therethrough.
`
`FIG. 17 is a perspective view of a smooth
`
`faced trial or gauge plug or block for use as shown in
`FIGURE 15.
`
`7
`
`FIG. 18 is a perspective view of a
`
`preferred form of permanent implant plug or block of
`this invention.
`
`FIG. 19 is a longitudinal vertical
`
`sectional view of the plug of FIGURE 18 taken along
`the line XIX-XIX of FIGURE 18.
`
`In FIGURES 1-5 the reference numeral 10
`
`illustrates generally the lower portion of a human
`
`vertebral column with adjacent vertebrae supported on
`prosthetic implants of this invention or illustrating
`the manner in which sites are prepared for the implant
`and the manner in which an implant is inserted on the
`
`prepared sites.
`
`7
`
`In FIGURE 1,
`
`the vertebral column 10
`
`shows the five lower vertebrae numbered 1—5. Adjacent
`
`vertebrae Nos. 2 and 3 and adjacent vertebrae Nos. 3
`
`and 4 are separated by and supported on prosthetic
`
`implants ll of this invention. Vertebrae Nos.
`
`1 and 2
`
`and vertebrae Nos. 4 and 5 are illustrated as
`
`supported on and separated by healthy or undamaged
`
`human discs 12 maintaining a disc space 13 between the
`
`adjoining vertebrae.
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`12'
`
`12
`
`

`

`WO 89/09035
`
`PCT/US89/00905
`
`The natural human discs have been excised
`from between discs Nos.
`2 and 3 and Nos. 3 and 4 with
`
`the disc spaces 14 being maintained by the implants
`
`11.
`
`The opposed faces of adjoining vertebrae have
`
`5
`
`prepared sites or channels 15 formed therein generally
`
`transversely of the axis of the column 10 to snugly
`
`receive cylindrical opposite faces of the implants 11.
`
`These transverse sites 15 are sufficiently wide and
`
`deep to span the central soft cancellous bone and
`
`10
`
`inlude the hard cortex bone of the adjacent vertebrae.
`
`However,
`
`the sites have blind ends 16 to bottom the
`
`implants 11.
`
`As shown in FIGURES 2 and 3,
`
`the implants
`
`11 are in the form of a pair of side—byjside
`
`15
`
`cylindrical plugs inserted endwise on the transverse
`
`sites 15 which are fragmental cylindrical to receive
`
`and mate with opposite faces of these plugs.
`
`The soft cancellous bone of the vertebrae
`
`is illustrated at 17 in FIGURE 3 and is surrounded by
`
`20_
`
`the hard cortex bone 18 of the vertebrae No. 3.
`
`The
`
`prepared sites 15 include portions of this hard cortex
`
`so that the implants ll span the softer cancellous
`
`bone 17 and rest on the hard cortex bone 18.
`
`25
`
`sites 15 and are bottomed on the blind ends 16 of
`
`The plugs 11 fit snugly in the prepared
`
`these sites.
`
`The plugs are rigid, preferably solid,
`
`and have roughened surfaces forming extensive anchor
`
`points or pores for bone ingrowth from the adjoining
`
`30
`
`vertebrae.
`
`They may be made of an inert metal, such
`
`as stainless steel, cobalt—chromium-molybdenum alloys,
`
`titanium, and the like.
`
`They may have many different
`
`shapes and peripheral surface configurations.
`
`They
`
`13
`
`13
`
`

`

`wo 89/09035 '
`
`PCI/Uss9/00905
`
`- 12 _
`
`have an end face with tool receiving recesses So as to
`be mounted on the tool for insertion on the prepared
`
`site and for removal of the tool without disturbing
`
`the mounting. These tool receiving recesses are
`
`illustrated in the form of an internally threaded
`
`circular hole 19 tapped into one end face 11a of the
`
`plug.
`
`A radial slot 20 diametrically intersecting the
`
`tapped hole 19 is also provided in the end face 11a
`
`thus forming wings radiating from the tapped hole 19.
`
`The hole l9 extends axially inward from the end face
`
`lla for a relatively short distance sufficient to
`
`provide a number of thread turns to be firmly anchored
`
`on the threaded end of an insertion tool.
`
`As shown in FIGURE 4,
`
`the sites 15 of the
`
`adjoining vertebrae Nos. 2 and 3 are easily prepared
`
`by a rotary drill or burr 21 slidable through a drill
`
`guard 22 with teeth or prongs 23 penetrating and
`
`anchored in the posterior side of both vertebrae.
`
`The
`
`drill is advanced through the sleeve 22 through the
`posterior sides of the vertebrae, but the drilling
`operation stops short of the anterior sides of these
`
`vertebrae so as to provide the blind ends 16 on the
`
`prepared sites.
`
`While the sites 15 are easily prepared
`
`with the drilling apparatus illustrated in FIGURE 4 it
`
`should be understood that sites of different shapes
`
`can be prepared with a mortise cutter or chisel shaped
`
`to conform with the shape of the implant to be
`inserted.
`7
`7
`
`As shown in FIGURE 5 the implant 11 is
`
`’l‘
`
`easily inserted on the prepared sites 15 from the
`
`'posterior side of the vertebrae Nos. 2 and 3 by means
`of a tool assembly 24 having a stem 25 with a threaded
`O.
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`14-
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`10
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`15
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`25
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`_ 13 _
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`end 26 mating with the tapped hole 19 in the end face
`
`11a of the implant 11 and mounted in an easily grasped
`
`handle 27 at the opposite end.
`
`A sleeve 28 is
`
`slidably mounted on the stem 25 and has diametrically
`
`opposite keys or lugs 25 on its forward end fitting
`
`the radial slot 20.
`
`A knurled head 30 is provided on
`
`the opposite end of the sleeve.
`
`The tool 24 with the sleeve 28 retracted
`
`on the stem 25 to expose the threaded end 26 of the
`
`stem is threaded into the tapped hole 19 and bottomed
`
`on the blind end thereof.
`
`The plug 11 is thus firmly
`
`mounted on the tool and the tool is manipulated to
`
`seat the plug on the prepared sites to be bottomed on
`
`the blind ends 16 of the sites 15. After positioning
`
`of the plug on the sites,
`
`the sleeve 28 is advanced on
`
`the stem 25 to bottom the prongs 29 in the slot 20 and
`
`the stem is unthreaded with the knurled head 30 of the
`
`sleeve being firmly held to prevent rotation of the
`
`sleeve and plug.
`
`The plug 11 is illustrated in detail in
`
`FIGURE 6 as having a solid cylindrical rod
`
`configuration with its circular end face lla having
`
`the internally threaded hole 19 extending axially
`
`inward therefrom and with the diametric intersecting
`
`radial slot 20 providing the wings for receiving the
`
`prongs 29 of the sleeve 28.
`
`The cylindrical rod 11
`
`has a knurled roughened peripheral surface llb forming
`
`pyramid—like pits 11c for facilitating bone ingrowth.
`
`The plug is dimensioned to snugly fit on the prepared
`
`sites between the posterior and anterior side of the
`
`vertebrae.
`
`Its dimensions may vary widely to suit
`
`conditions and plug sizes of about 5/8" in diameter
`
`and abOut 1" in length are useful.
`
`The tapped hole 19
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`3O
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`15
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`15
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`WO 89/09035
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`PCT/USS9/00905
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`_ l4 _
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`a.
`
`in the end face lla of such a plug need only be about
`1/8" in diameter and 1/4" in depth;
`The slot should
`terminate short of the periphery and need only be
`about 1/8" deep.
`
`Another suitable form of prosthetic
`implant of this invention is illustrated in FIGURE 7
`where the device 31 has a square rectangular shape
`with an end face 31a having the tapped hole 19 and
`
`groove or slot 20.
`
`The device 31 has a pitted
`
`10
`
`periphery 31b forming a myriad of small pores to
`
`facilitate bone ingrowth.
`
`Another form of prosthetic device 32 is
`
`illustrated in FIGURE 8 in the form of a cylindrical
`
`15
`
`plug 32 with an end face 32a containing the tapped
`hole 19 and slot 20.
`The periphery of the cylindrical
`
`plug has longitudinally spaced circular ribs 32b.
`
`These ribs form dish-like prongs or barbs tilted
`
`toward the threaded end of the plug so that they will
`deflect to slide into the prepared sites but will bite
`
`into the bone to resist retraction from the sites. As
`
`illustrated the ribs have convex leading faces 32c and
`
`concave trailing faces 32d.
`
`Such configuration
`
`assists deflection when the plug is pushed into
`
`position but will spring back to resist reverse
`
`If desired the ribs can be
`retraction or rotation.
`axially slotted to provide a myriad of barbs.
`In the embodiment 33 of fIGURE 9 the
`
`implant is in the form of a solid cylindrical rod with
`
`an end face 33a containing the tapped hole 19 and slot
`
`20 and with the cylindrical periphery being externally
`threaded, as illustrated at 33b.
`The thread will
`
`advance the plug into the prepared sites when the plug
`
`20
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`WO 89/09035
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`is rotated in a clockwise direction.
`
`The threads can
`
`have sharp edges to bite into the bone structure.
`
`The implant plug 34 of FIGURES 10 and 11
`
`has the same end face 343 as the other plugs with the
`
`tapped hole 19 and slot 20, however, it has a solid
`
`rigid circular rod core 34b with a polymeric resin
`
`cover 340 with the peripheral surface of the cover
`
`having upright projecting bristles 34d. These
`
`bristles form extended surfaces facilitating bone
`
`10
`
`ingrowth.
`
`Many other types of rough or irregular
`
`surfaces can be provided on the devices of this
`
`invention including porous metal coatings composed of
`
`metal balls and beads sintered on a rigid metal
`
`15
`
`substrate as further dislosed in the aforesaid Patent
`
`20
`
`25
`
`No. 4,743,256.
`
`The prosthetic implants are shown on the
`
`drawings as mounted in side-by-side parallel relation
`
`forming a pair of struts which maintain the disc space
`
`being snugly seated on hard cortex bone to carry the
`
`laod. These implants have surfaces facilitating rapid
`
`bone ingrowth which will fuse the implants to the
`
`adjacent vertebrae in a relatively short growth
`
`period.
`
`In FIGURES 12—14,
`
`the reference numeral
`
`100 illustrates generally the lower portion of a human
`
`vertebral column with adjacent vertebrae supported on
`
`prosthetic implant blocks or plugs 111 of this
`
`invention.
`
`30
`
`FIG. 15 shows the manner in which
`
`adjacent vertebrae are spread apart to stretch
`
`collapsed intervening disc tissue as a gauge or trial
`
`17
`
`17
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`

`wo 89/09035
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`7
`
`7
`
`PCT/Uss9/009os
`
`_ 15 _
`
`'l
`
`block of this invention is inserted laterally into
`
`transverse rectangular slots of adjoining vertebrae.
`,
`IanlGURE 12,
`the vertebral column 100
`
`shows the five lower vertebrae Nos. 1—5. Adjacent
`vertebrae Nos. 2 and 3 and adjacent vertebrae Nos. 3
`and 4 are separated by and supported on the prosthetic
`
`implant blocks or plugs 111 of this invention.
`
`Vertebrae Nos.
`
`1 and 2 and vertebrae Nos. 4 and 5 are
`
`illustrated as supported on and separated by healthy
`
`or undamaged human discs 112 maintaining a normal disc
`
`space 113 between the adjoining vertebrae.
`
`Damaged portions of the natural human
`7
`discs 112 have been excised from the vertebrae Nos. 2
`
`and 3 and Nos. 3 and 4 with the disc spaces 114 being
`maintained by the implant blocks or plugs 111.
`It is
`preferred to retain as much as possible of the healthy
`annulus tissue of the discs 112 between the vertebrae
`'so that the remaining disc tissue 112a will at least
`
`partially surround the implants and will be held under
`
`tension by these implants. However,
`
`some of the
`
`remaining annulus disc tissue may have to be excised
`
`'to open up spaces for the implant plugs 111.
`
`The opposed faces of adjoining vertebrae
`
`have aligned flat-sided rectangular channels or
`
`grooves 115 out therein transversely of the axis of
`
`column 100 to first snugly receive test blocks or
`
`plugs of this invention for determining the proper
`sizes for the permanent implants 111. These
`
`10
`
`15
`
`20
`
`25
`
`30
`
`transverse channels 115 are sufficiently wide and deep
`to span the central soft cancellous bone and include
`
`the hard cortex bone of the adjacent vertebrae.
`
`The
`
`undamaged human disc tissue 112a remaining between the
`I
`vertebrae is also cut or trimmed to receive the
`
`18
`
`18
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`

`WO 89/09035
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`PCT/USS9/00905
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`- 17 _
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`implants 111 so that as much healthy annulus fibrous
`
`tissue as is available will surround the implants.
`
`The preferred flat-sided rectangular
`
`channels 115 have blind ends 116 to be abutted by the
`implants 111.
`
`As shown in FIGURES l3 and 14,
`
`the
`
`implants 111 are in the form of a pair of side—by-side
`
`rectangular plugs inserted endwise into the transverse
`
`channels 115. These channels have flat bottoms and
`
`sidewalls to snugly embrace the top and bottom ends
`
`and side faces of the rectangular plugs.
`
`The soft
`
`cancellous bone of the vertebrae is illustrated at 117
`
`in FIGURE 14 and is surrounded by the hard cortex bone
`
`118.
`
`The channels 115 include portions of this hard
`
`cortex bone so that the implants 111 span the softer
`
`cancellous bone and rest on the hard cortex bone 118.
`
`The channels 115 can be formed by a
`
`mortise cutting chisel tool and in the event disc
`
`10
`
`15
`
`tissue 112a blocks the paths for the plugs 111,
`
`tissue
`
`20.
`
`can be trimmed or spread apart to open up the paths.
`
`The implant plugs of blocks 111, as shown
`
`in FIGURES 18 and 19, are rigid,
`
`inert, solid,
`
`flat-sided rectangles, higher than wide and longer
`
`than high.
`
`They are used in cooperation with trial or
`
`gauge blocks, such as 119,
`
`shown in FIGURE 17. These
`
`blocks 119 have flat, smooth sides and ends with flat
`
`top and bottoms 119a, flat sides 119b, a flat front
`
`end wall 119c, and a flat back end wall 119d.
`
`The
`
`front wall 119C is beveled to a reduced rectangular
`
`nose surrounded by flat-sided tapered walls 119e with
`
`rounded corners 119f.
`
`25
`
`30
`
`19
`
`19
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`

`

`WO 89/09035
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`- 18 _
`
`'1!
`
`The back end wall 119d has an internally
`
`threaded blind axial hole 119g at the center of the
`wall;
`
`The gauge blocks 119,
`
`in typical surgical
`
`operations, will have a length of about 25 mm, a width
`of about 11 mm and will vary in height from say, 13 to
`17 mm, although it should be understood that these
`parameters may vary greatly and may depend on the size
`
`of the spinal column of the recipient.
`
`The tapers
`
`ll9e are preferably about 30 degrees.
`
`The rounded
`
`corners 119i of the bevels eliminate sharp corners
`
`between the top, bottom and sides of the beveled
`
`faces;
`
`7
`
`As shown in FIGURE 15, a trial or gauge
`
`block 119 is selected for force-fitting into the
`
`channels 115 while mounted on a tool 120 threaded into
`the hole 119g.
`The beveled front end 1190 of the
`
`block will pass through any portion of the disc tissue
`112a covering the entrance mouths of the channels 115
`
`by either cutting holes through the remaining tissue
`
`or by spreading apart the fibers of the disc to accept
`the gauge blocks 119.
`
`the remaining
`As shown in FIGURE 16,
`healthy disc tissue 112a of a disc 112 between the
`channel cut vertebrae is trimmed to open up slots 121
`
`Cpermitting access of the gauge blocks 119 to the
`channels 115. These slots register with the channels
`115 and can have open front ends 121a and blind back
`
`ends 121b.
`
`It is preferred to remove the nucleus
`
`pulposus from the damaged disc 112 leaving an annulus
`of fibrous tissue connecting the adjoining vertebrae
`
`ml
`
`and surrounding the inserted blocks.
`
`20
`
`10
`
`15
`
`20
`
`25
`
`