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`vsoos192327A
`
`[19]
`United States Patent
`[45] Date of Patent: Mar. 9, 1993
`Brantigan
`
`[11] Patent Number:
`
`5,192,327
`
`
`
`[54] SURGICAL PROSTHETIC MPLANT FOR
`VERTEBRAE
`
`[76]
`
`Inventor:
`
`John W. Brantigan, 328 Overlook
`Brook Ct., Chagrin Falls, Ohio 44022
`
` [22] Filed: MarLZZ, 1991,,
`
`[21] Appl. No.: 673,474
`
`......... A61F 2/44
`[51]
`Int. Cl.5
`[52] US. Cl. ........................................ 623/17; 606/60;
`606/61
`[58] Field of Search ....................... 623/17; 606/60, 61
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`terior Instrumentation; Spine, vol. 9 No. 8, Nov.-Dec.
`84 by J. B. Lippincot Company.
`Robinson, R. A. et al.: The Results of Anterior Inter-
`body Fusion of the Cervical Spine; The Journal of Bone
`and Joint Surgery, 4A No 8 Dec. 1962.
`Simmons, E. H. et al.: Anterior Cervical Discectomy
`and Fusion; The Journal of Bone and Joint Surgery,
`SIB No. 2,.May 1969.
`Stanfier, R. N. et al.: Anterior Interbody Lumbar Spine
`Fusion; The Journal of Bone and Joint Surgery, 54A,
`No. 4, Jun. 1972.
`-
`White, A. B. et al.: Relief of Pain by Anterior Cer—
`vical—Spine Fusion for Spondylosis; The Journal of
`Bone and Joint Surgery, 55A No. 3 Apr. 1973.
`
`...................... 623/17
`
`2,677,369 5/1954 Knowles .
`3,848,601 11/1974 Ma et a].
`.
`3,867,728 2/1975 Stubstad et a1.
`4,309,777
`1/1982 Patil .
`4,349,921
`9/1982 Kuntz .
`4,553,273 11/1985 Wu .
`4,714,469 12/1987 Kenna .
`4,743,256
`5/1988 Brantigan.
`4,759,766 7/1988 Buettner-Janz et a1.
`4,834,757 5/1989 Brantigan.
`7
`4,878,915 11/1989 Brantigan.
`4,997,432
`3/1991 Keller ............................... 623/17X
`
`............. 623/17
`
`OTHER PUBLICATIONS
`
`Cloward, R. 13.: Vertebral Body Fusion for Ruptured
`Cervical Discs—Description of Instruments and Opera-
`tive Technique; Am. J. Surg 98, Nov. 1959; 722-727.
`Crock, H. V.: Practice of Spinal Surgery, Sprin-
`ger—Verlag, Wein, N.Y., 1983: pp. 35-92.
`Flesh, H. R. et al.: Harrington Instrumentation and
`Spine Fusion for Unstable Fracture and Fracture—Dis-
`locations of the Thoracic and Lumbar Spine The Jour-
`nal of Bone and Joint Surgery, American Volume, vol.
`59A, No. 2 Mar. 1977.
`Flynn, J. C. et al.: Anterior Fusion of the Lumbar
`Spine; Journal of Bone and Joint Surgery; vol. 61A No.
`8 Dec. 1979.
`Kaneda, K. et al.: Burst Fractures with Neurologic
`Deficits of the Thoracolumbar—Lumbar-Spine Results
`of Anterior Decompression and Stabilization with An—
`
`Primaiy Examiner~Randall L. Green
`Assistant Examiner—Dinh Nguyen
`
`[57]
`
`7
`
`ABSTRACT
`
`Surgicalprosthetic modular implants used singularly or
`stacked together are provided to support and fuse to-
`gether adjacent vertebrae or to totally or partially re-
`place one or more vertebrae in a vertebral column. The
`implants are rigid annular plugs, dimensionally similar
`to normal vertebral bodies, have simplified oval or
`hemi-oval shapes with ridged faces to engage, adjacent
`vertebral bodies to resist displacement and allow bone
`ingrowth and fusion and to interdigitate with the ridges
`of an adjacent plug for 'modular stacking to allow vari-
`ability of ultimate implant height. The implants can be
`provided in sets of different thicknesses and are inter-
`nally grooved to receive an upstanding connecting bar
`to bind together the individual stacked implants into a
`stable unit. Theannular implants have ample spaces to
`allow ingrowth of blood capillaries and packing of bone
`graft and are preferably made of a radiolucent material,
`preferably biocompatible carbon fiber reinforced poly-
`mers or are alternately made of traditional orthopaedic
`implant materials such as nickel, chromium, cobalt,
`stainless steel or titanium.
`.
`
`. 14 Claims, 3 Drawing Sheets
`
`
`
`NUVASIVE1006
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`US. Patent
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`Mar. 9, 1993
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`US. Patent
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`Mar. 9, 1993
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`1.
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`5,192,327
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`SURGICAL PROSTHETIC IMPLANT FOR
`VERTEBRAE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`This invention relates to inert'rigid vertebral pros-
`thetic devices and methods for implanting the devices
`between adjacent vertebrae to treat or prevent back or
`neck pain in patients with ruptured or degenerated
`intervertebral discs and for replacing vertebral bodies
`damaged by fracture, tumor or degenerative process.
`Specifically, the invention deals with ring-like pros-
`thetic plugs or discs used singly or stacked together
`between vertebrae to form support sturts in the spinal
`column and having rigid surfaces facilitating anchoring
`and providing valleys for bone ingrowth from adjoining
`vertebrae. The rings are bottomed on the opposing end
`faces of adjoining vertebrae, are preferably oval shaped
`with medial-lateral and anterior-posterior dimensions in
`the same ratio as normal vertebral bodies, are supplied
`in different heights to be used individually to replace a
`single damaged intervenebral disc, have ridges to bite
`into the vertebrae or to interdigitate to be securely
`stacked together to the exact height required at the time
`of surgery, have slots and hollow areas 'for packing
`bone graft material, tool receiving means, and are pref-
`erably radiolucent to allow visualization of thebone
`healing postoperatively.
`2. Description of the Prior Art
`While many types of vertebral prosthetic devices
`have been proposed, the 'success ratio has been very low
`and the surgical procedures have been very compli-
`cated and traumatic to the patient. The surgical implant
`devices and methods covered in my U.S. Pat. Nos.
`4,743,256; 4,834,757 and 4,878,915 have greatly im-
`proved the success rate and have simplified the surgical
`techniques in interbody vertebral fusion. In the proce-
`dures covered by these patents, biologically acceptable
`but completely inert strut plugs are bottomed in chan-
`nels or grooves of adjoining'vertebrae and receive bone
`ingrowth which quickly fuses the structure to the bone
`and forms a living bone bridge across the fusion area.
`The present invention now further improves this art
`of interbody fusion without cutting grooves or channels
`in the vertebrae and is especially well suited for anterior
`cervical and lumbar fusion. The invention provides
`ring-like prosthesis plugs or discs bottomed on end faces
`of adjoining vertebrae and constructed and arranged so
`that they can be used singly or stacked plurally to ac-
`commodate individual surgical requirements. The rings
`can replace excised discs and vertebrae and can also be
`mounted inside the fibrous disc column connecting
`adjoining vertebrae. The annular units are preferably
`ova] or partial oval shaped preferably hemi—oval, to
`conform with vertebral disc shapes, have ridged or
`peaked surfaces for biting into the vertebrae on which
`they are seated and for receiving bone ingrowth in
`valleys between the peaks. When stacked, an interior
`connecting bar can be provided to lock the components
`in fixed relation and cooperate with interfitting ridges.
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`SUMMARY OF THE INVENTION
`According to this invention, biologically acceptable,
`but inert rigid annular prosthesis units are provided to
`support and fuse with adjacent vertebrae in both the
`cervical, thoracic spine and lumbar portions of a human
`vertebral column. These ring-like prosthetic devices are
`
`65
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`2
`bottomed on the hard bone faces or end plates of adja-
`cent vertebrae and are generally oval shaped to con-
`form with the general outline perimeter of the verte-
`brae. They are also provided in partial (preferably hemi-
`oval) annular shape to accommodate those surgical
`procedures where only a portion of the vertebrae or
`disc is damaged. Two such hemioval rings can be used
`in the posterior lumbar area in side-by-side relation
`since the dural sac and nerve roots must be retracted to
`each side in turn as the implant is placed on the opposite
`side. In an anterior fusion since the entire front of the
`disc space is exposed, a single piece implant can be used
`making the oval an advantage in this area.
`The periphery of the oval ring is grooved to accom-
`modate ingrowth of blood capillaries and the open cen-
`tral portion of the ring is preferably packed with bone
`graft material to facilitate bone ingrowth. Bone graft
`can alsobe packed in the grooves.
`Each of the oval implants is sized to match the height
`of an average disc and thus, can vary from 10 to 15 mm
`for the lumbar area and from 7-11 mm for the cervical
`area.
`
`The oval shape simplifies the surgical procedure since
`it can be rotated or reversed and still fit the vertebrae.
`Further, the device stretches the disc tissue creating a
`tension which will cause the vertebrae to tightly grip
`the ring on which it is bottomed. If the disc columnar
`tissue is preserved, a cut, preferably “Z”-shaped, can be
`made in the columnar fibrous tissue, the interior pulpus
`material of the disc removed, and the ring implant in-
`serted through the cut to be bottomed on the adjoining
`vertebrae and surrounded by the disc tissue.
`To accommodate a myriad of different heights be—
`tween vertebrae on which the prosthesis ring is to be
`bottomed, the rings can be supplied in sets of different
`heights to be stacked to the exact height required for a
`particular surgical implant. For example, in the cervical
`spine, cervical corpectomy is often required for cervical
`myelopathies in which large bone spurs cause spinal
`cord pressure. An average grafting height is 30 mm
`after corpectomy and this can be achieved by stacking,
`for exar'nple, three 10 mm high oval implants.
`In the treatment of thora columbar fractures, hemi-
`corpectomy is often done followed by grafting. Place-
`ment of stacked hemi-oval implants in the hemi-Corpec-
`tomy area provides solid structural weight bearing. The
`re-sected vertebral bone is packed into the implant so
`that harvesting of additional bone grafting can be
`avoided. ‘
`In the treatment of vertebral tumors, the stacked oval
`implants can achieve solid bony fusion across the entire
`re-sected area providing a permanent mechanically
`secure repair with living tissue.
`The invention now provides vertebral prosthetic
`implant devices suitable for anterior, posterior or lateral
`placement in any‘ area of the spine requiring replace-
`ment of disc or vertebral body. Since the implants are
`intended to. bottom out on adjacent vertebral end faces,
`which preferably have been prepared by flattening with
`a burr drill,
`removing cartilaginous material and
`stretching the annular fibrosis so that the vertebrae can
`tightly grip the plug, the plugs can be inserted either
`anteriorly, posteriorly or laterally into the vertebral
`column while mounted on the end of an insertion tool.
`
`The ring devices have ridged surfaces providing mul-
`tiple purposes of gripping the vertebrae to resist expul-
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`3
`sion, forming valleys to facilitate bone ingrowth, and to
`matching interdigitate with each other for stacking.
`An upstanding longitudinal connecting member fits
`in interior grooves in the ring and cooperates with the
`ridges to prevent separation of stacked implants in
`every direction except in longitudinal height. Since the
`implants are placed in compression between the verte-
`bral bodies, they cannot come apart after implantation.
`The implants are preferably made of radiolucent ma-
`terial such as carbon fiber reinforced polymers known
`commercially as “Peek”, (polyetherether ketone) or
`“U'ltrapek” (polyether ketone, ether ketone, ketone).
`Alternately, polycarbonate, polyprophylene, polyethel-
`yene and polysulfone type plastics material filled with
`glass or carbon fibers can be used. Such materials are
`supplied by 101 Industries of Wilmington, Del.; Fiber-
`Rite Corporation of Winona, Minn. or BASF Corpora-
`tion.
`Preferred best mode embodiments of the invention
`are illustrated in the attached drawings in which:
`FIG. 1 is a top and side perspective view of a full oval
`prosthetic device according to this invention;
`FIG. 2 is a top and side perspective view of a hemi-
`oval prosthetic device of this invention;
`FIG. Sis a top and side perspective view of a con-
`necting bar fitting the illustrated grooves in the devices
`of FIGS. 1- and 2 to hold a plurality of the devices in
`stacked relation;
`FIG. 4 is a top and side perspective view of a stack of
`the devices of FIG. 1 with the connecting bar of FIG.
`3 in place;
`FIG. 5 is a top and side perspective view of a stack of
`the devices of FIG. 2 with a connecting bar like FIG. 3
`in place;
`FIG. 6 is a view similar to FIG. 1 but illustrating a
`modified device with an integral cross bar;
`FIG. 7 is a side view showing a tapered device of this
`invention,
`FIG. 81s a side view of the stack of devices of FIG.
`4 showing how the ridges interdigitate when stacked;
`FIG. 9'rs a view similar to FIG. 8 but showing a stack
`of tapered devices of FIG. 7 with the center device
`rotated 180° to form a vertical stack with end faces
`tapered in the same direction.
`FIG. 10 is an elevational view of a portion of a verte-
`brae column showing a‘ two stack assembly in an ex-
`cised disc’space betWeen adjacent vertebrae and the
`manner in which a disc can be cut to receive a device of
`this invention.
`
`FIG. 11 is a sectional view along the line XI—XI of
`FIG. 10;
`FIG. 12 is a longitudinal view of a portion of a verte-
`bral column, with parts in section and broken away to
`show the manner in which a stack of the devices is used
`to replace partially damaged discs and an intermediate
`vertebrae portion;
`FIG. 13 is side diagrammatic view showing the inser-
`tion of a device of this invention in a disc space with the
`aid of a mounting tool.
`FIG. 14 is a view similar to FIG. 13 illustrating the
`manner in which a fork-like tool can have tines mounted
`in a pair of holes in the device.
`FIG. 15 is a line diagram illustrating the manner in
`which the ridges of the plugs have side walls diverging
`at the same angles from the peaks to provide interdigi-
`tating or complimentary mating or nesting projections.
`As shown on the drawings:
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`In FIG. 1, the reference numeral 10 designates gener-
`ally a vertebrae prosthesis device of this invention com-
`posed of rigid biologically acceptable and inactive ma-
`terial, preferably a radiolucent plastics material, inert
`metal and the like as described above. The device 10 is
`an oval ring plug 11 generally shaped and sized to con-
`form with the disc space between adjoining vertebrae in
`a vertebral column. The plug 11 has opposed sides 11a
`and ends 11b, flat, ridged top and bottom faces 11c and
`a central upstanding aperture 11d therethrough. The
`ends 11b have relatively wide and long horizontal pe-
`ripheral slots lle therethrough preferably extending
`into the sides Ila and communicating with the central
`aperture 11d.
`Ridges 12 are formed longitudinally across the end
`faces 11c. These ridges 12 have inclined side walls 12a
`merging in sharp peaks 12b and provide valleys 12c
`between the side walls. The valleys 12c open at the ends
`11b of the oval ring plug 11.
`One side wall 11a of the plug 11 has an internally
`threaded hole 13 extending partially through the wall
`for receiving a mounting tool as hereinafter described.
`' The interior faces of the side walls 11a also have
`upstanding open ended vertical grooves 14 preferably
`of fragmental cylindrical configuration. These grooves
`are provided for mounting a rectangular connecting bar
`15 shown in FIG. 3. This bar 15 has flat side faces 15a,
`rounded side edges 15b to snugly fit the grooves 14 and
`top and bottom end edges 15c which are provided with
`ridges 16 that conform with the ridges 12 of the plug 10.
`Thus, these ridges 16 have oppositely inclined sides 16a
`converging to peaks 16b and providing valleys 16c
`therebetween. The peaks and valleys of the ridges on
`the ends of the connecting bar 15 are aligned with the
`peaks and valleys of the ridges on the top and bottom
`faces 11c of the plug 11 when the barrs seatedin place
`in the grooves 14.
`The connecting bar 15 has a height conforming with
`the total height of a stack 17 of plugs 11 shownin FIG.
`404 or with only a single plug 11 if a stack of plugs is not
`necessary. As shown in FIG. 4 three plugs 11 are
`stacked together with the ridges 12 of the intermediate
`plug nested in and interdigitating with the ridges of top
`and bottom plugs. These ridges interfrt to provide a
`stable stack and the connecting bar 15 seated in the
`aligned grooves 14 of the three plugs will prevent shift-
`ing of the stack. The end faces of the bars 15 will then .
`have their ridges 16 aligned with the ridges 12 in the
`exposed end'faces of the top and bottom plugs 11.
`The central aperture 11d of each plug 11 is separated
`by the bar 15 into two side-by-side chambers which are
`easily packed with bone graft material to expedite the
`fusion of the prosthesis device in the spinal column. In
`addition, the slots 11a in the ends 11b of the plugs can
`receive bone graft material and also provide free spaces
`for blood flow to speed up the fusion process.
`A modified hemi-oval device 20rs illustratedin FIG.
`2 for usage in partial corpectomy operations and also
`for use in spaced side-by-side relation when an interme-
`diate nerve space is nwded. The device 20 is a one-piece
`plastics material or metal plug 21 of generally hemi-oval
`shape with opposed side walls 214, a rounded oval end
`wall 21b, a flat opposite end wall 21: and a central
`aperture 21:]. The top and bottom faces 21e of the plug
`21 are ridged in the same manner as the plug 11 thus
`providing longitudinal ridges 22 with inclined side walls
`22a, peaks 22b and valleys 22c. The end walls 21b and
`21c have the same slots 21fas the slots lie of the plug 11
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`and an end wall 21a has the same tool receiving recess
`23 as the plug 11.
`Internal grooves 24 are provided in the inner faces of
`the end walls 21b and 21c of the plug 21 to receive a
`connecting bar such as 15. This bar however will divide 5
`the central aperture of the plug 21 in a longitudinal
`instead of a transverse direction as illustrated for the
`plugs 11.
`As shown in FIG. 5 the plugs 21 form a stack 25, in
`the same manner as the plugs 11 in the stack 17 of FIG. 10
`4 with the same type of connecting bar 15.
`' The plugs'll and 21 of FIGS. 1 to 5 may vary in
`thickness or height to suit conditions and in the stacks of
`FIGS. 4 and 5, plugs of different thicknesses or heights
`can be stacked together to provide the desired overall 15
`height for each operation. Sets of these plugs may thus
`be supplied so that the surgeon can easily end up with a
`stack of the required height to fit the patient. The
`lengths or heights of the connecting bars 15 can also be
`varied to suit conditions or can be ground down at the 20
`time of the operation to match the stack.
`The ridges on the exposed end faces of the stacks of
`plugs will bottom on the hard end faces or end plates of
`adjacent vertebrae and the apices or peaks 21b and 22g
`of these ridges will firmly engage and bite into these 25
`faces to prevent slippage. In addition, the valleys 12c
`and 22c between the ridges serve as gaps or troughs to
`freely receive bone ingrowth from the adjacent verte-
`brae.
`
`6
`brae are wider at one end than at the other. The use of
`the tapered plugs eliminates some of the grinding of the
`end faces of the vertebrae that may be needed for a
`good matching of the ridges with the vertebrae faces.
`As shown in FIG. 10, a portion of a human vertebral
`column 50 has adjoining vertebrae 51 and 52 fused to-
`gether by a two-unit stack 53 composed of the plugs 11
`illustrated in detail in FIGS. 1, 4 and 8. This stack 53 fits
`the disc space 54 between the vertebrae 51 and 52 and
`the top ridges 12 of the stack are bottomed on and bite
`into the bottom face or hard end plate of the upper
`vertebrae 51 while the bottom ridges 12 of the stack are
`bottomed on and bite into the upper face or hand end
`plate 52a. The peaks 12b of the ridges 12 firmly anchor
`the stack to the vertebrae butdo not penetrate through
`the hard faces 510 and 52a of the vertebrae. The valleys
`12c are exposed to the vertebrae faces and receive bone
`ingrth from the vertebrae during the post-operative
`fusion.
`As shown all of the disc has been removed from the
`disc space 54 and the stack 53 maintains the disc space
`at its normal height.
`As shown in FIGS. 10 and 11, a vertebral disc 55 fills
`the disc space 56 between the vertebrae 52 and a lower
`vertebrae 57 of the vertebral column 50. A Z-shaped cut
`58 through the tubular fibrous portion of the disc 55
`provides access to the interior pulpus portion of the disc
`permitting its removal to receive a single plug 11 form-
`ing a rigid strut inside of the column of disc fibers 55a
`which remain attached to the bottom face 52b of the
`upper vertebrae 52 and the top face 57a of the lower
`vertebrae 57. As illustrated, the peaks 12b of the ridges
`12 on the top and bottom faces of the plug 11 bite into
`the faces 52b and 57a and the valleys 12c between the
`peaks are openly exposed to these faces of the verte-
`brae.
`As better shown in FIG. 11, the hollow interior 11d
`and the slots lle of the plug 11 are packed with bone
`graft material 58 which can be conveniently harvested
`from the iliac crests of the patient’s pelvic bone.
`FIG. 12 illustrates a cervical portion 60 of a human
`vertebral column having an upper vertebrae 61, a mid-
`dle vertebrae 62 and a bottom vertebrae 63 with a stack
`25 like FIG. 5 but composed of four plugs 21 implanted
`to support the column. As shown, the t0p and bottom
`vertebrae 63 remain intact while the middle vertebrae
`62 has been partially excised. The four hemi—oval plug
`units 21 are interdigitated together through their ridges
`22 and a bar 15 such as shown in FIG. 5 can hold the
`units in an upright column. Discs 64 and 65 have also
`been partially excised to receive the stack 25 but their
`remaining tissue is anchored to their adjacent vertebrae.
`The bottom face 61a of the upper vertebrae 61 and
`the top face 630 of the bottom vertebrae 63 are partially
`penetrated by the peaks of the ridges of the top and
`bottom plugs 21 to function as described above. Also,
`the hollow interiors of the hemi—oval plugs 21 and their
`slots 21:: are filled with bone graft material 66.
`During surgery, the spinal column is stretched to
`regain any lost disc space caused by herniation of the
`discs. This stretches the remaining disc tissue and as
`illustrated in FIGS. 13 and 14, the plugs of this inven-
`tion such as the plugs 11 or a stack of the plugs, are
`inserted into the opened up disc space such as 70 be-
`tween adjacent vertebrae 71 and 72, either anteriorly,
`laterally or posteriorly while mounted on a tool 73
`having a’single end 73a threaded into the internally
`threaded hole 13 of the plug 11 as illustrated in FIG. 13.
`
`35
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`The individual plugs or the stack of plugs can be 30
`introduced anteriorly, laterally or posteriorly depend-
`ing upon conditions and the tool receiving recesses 13
`and 23 of the plugs 11 and 21 can thus be positioned to
`meet the particular type of insertion into the vertebral
`column.
`Instead of providing a separate bar or plate 15, as
`shown in FIG. 6, a modified device 30 of this invention
`is a plug 31 of the same oval shape as the plug 11 of
`FIGS. 1 and 4 but the reinforcing bar 32 of this plug is
`integral with its side walls 310. The hollow interior 23 40
`of the plug 31 is thus bisected by an integral internal
`partition 32 forming a pair of side-by-side apertures
`through the plug adapted to receive bone graft material.
`A plug similar to 30 can also be provided in a hemi-
`oval shape. The plugs with the integral dividing barare 45
`preferably used singly but also can be stacked and inter-
`digitated by their ridges.
`The plugs 11, 21 and 31 of FIGS. 1, 2 and 6 are uni-
`form in thickness or height across their length.
`In a further modified device 40 shown in FIG. 7, the 50
`plug 41 is tapered to be higher or thicker at its anterior
`end than at its posterior end. The plug 41 has ridged top
`and bottom faces 42, the same as the plugs of FIGS. 1-6
`and a tool receiving recess 43 is provided in its higher or
`trailing end. By way of an example, the trailing end 55
`could be 12 mm in height while the leading end reduced
`to 9 mm in height.
`In the stacking of plugs, each of which have uniform
`height or thickness such as shown at 11, 21, and 31, the
`holes for the mounting tool'can all be aligned on one 60
`side of the stack as illustrated in FIG. 8 but, as shown in
`FIG. 9, the forming of a stack 44 of tapered plugs 41
`requires displacement of the central or middle plug 180°
`from the‘end plugs in order that the stack will have a
`vertical column contour. The ridged faces 42 of the 65
`tapered plugs 41 will interdigitate and the exposed end
`faces of these ridges will be inclined or tapered to suit
`surgical application in spaces where the adjacent verte-
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`Alternately, the plug 11, as illustrated in FIG. 14 may
`have a pair of side-by-side holes 13a receiving the tine
`end 74 of a modified tool 75.
`Tools such as 73 and 75 may also be replaced with
`other gripping tools which do not require amounting 5
`apertures in the end faces of the plugs.
`As better shown in the line diagram of FIG. 15 the
`ridged faces such as 12 of twos stacked plugs such as 11
`of FIG. 1 have equally inclined side walls 12a diverging
`from sharp peaks 12b at a relatively wide angle A to
`prevent formation of thin narrow fingers or teeth that
`could break off and narrow valleys that could block
`bone ingrowth. An angle of at least 30°-45' is preferred
`to provide wide ridges and open valleys.
`_
`From the above descriptions, it will understood that
`this invention now advances the art of vertebral column
`surgery and provides prosthetic devices used singly or
`stacked to desired heights, which fit the disc'spaces
`between adjacent vertebrae, bottom on and bite into the
`' vertebrae faces without penetrating the hard surfaces
`thereof and have ample chambers for ingrowth of blood
`capillaries and bone graft material to expedite bone
`ingrowth during a post-operative period. The devices
`do not require anchoring screws or penetration through 4
`the hard faces of the vertebrae and can be mounted
`inside the vertebral disc or along the side of a partially
`excised disc, or in the disc space of a completely excised
`disc.
`
`height effective to provide a strut between the verte-
`brae maintaining a desired disc space.
`8. A surgical prosthetic device adapted for fusing
`together adjoining vertebrae in a vertebral column
`which comprises a rigid inert annular plug sized and
`shaped to fit opposed end faces of vertebrae in a verte-
`bral column and having top and bottom faces with
`peaks adapted to bite into the end faces of the adjoining
`vertebrae and valleys between the peaks to receive bone
`ingrowth; said plug having a height effective to provide
`a strut between the vertebrae maintaining a desired disc
`space, and said height of the annular plug being suffi-
`cient to stretch a annulus fibrosis tissue of a disc con-
`necting the adjoining vertebrae to maintain a desired
`disc height and provide snug gripping of the plug with
`the and faces of the adjoining vertebrae.
`9. The surgical prosthetic device of claim 8 wherein
`the top and bottom faces of the plug have diverging
`equally sloping side walls converging to sharp peaks
`,and relatively wide valleys between the peaks and said
`side walls adapted to nest together to hold adjacent
`plugs in alignment.
`10. A surgical prosthetic device adapted for fusing
`together adjoining vertebrae in a vertebral column
`which comprises a rigid inert annular plug having an
`interior and sized and shaped to fit opposed end faces of
`vertebrae in a vertebral column and having top and
`bottom faces with peaks adapted to bite into the end
`faces of the adjoining vertebrae and valleys between the
`peaks to receive bone growth, said plug having a height
`effective to provide a strut between the vertebrae main-
`taining a desired disc space, and said plug having a bar
`intersecting the interior of the plug.
`11. The surgical prosthetic device of claim 10 having
`diametrically opposed upstanding internal grooves
`adapted to receive said bar.
`12. A prosthetic device seating on hard end plates of
`vertebrae in a vertebral column while preserving
`healthy disc tissue between the vertebrae which com-
`prises a rigid inert annular plug generally conforming in
`shape and size with opposing hard end plates of verte-
`brae on which it is to be seated, said plug having periph-
`eral side and end walls, top and bottom faces, a central
`aperture therethrough between the faces, and a periph-
`eral slot therein, said end faces having raised ridges with
`side walls converging to peaks and valleys between the
`side walls, said peaks adapted to be bottomed on and
`bite into the hard end plate faces of vertebrae, tool
`mounting means in a peripheral wall of the plug, said
`aperture and slot in the plug adapted to be packed with
`bone graft material, and said plug being composed of a
`radiolucent plastics material.
`13. A prosthetic device seating on hard end plates of
`vertebrae in a vertebral column while preserving
`healthy disc tissue between the vertebrae which com-
`prises a rigid inert annular plug generally conforming in
`shape and size with opposing hard end plates of verte-
`brae on which it is to be seated, said plug having periph-
`eral side and end walls, top and bottom faces, a central
`aperture therethrough between the faces, and a periph-
`eral slot in each end wall therein, said end faces having
`raised ridges with side walls converging to peaks and
`valleys between the side walls, said peaks adapted to be
`bottomed on and bite into the hard end plate faces of
`vertebrae, tool mounting means in a peripheral wall of
`the plug, and said aperture and slot in the plug adapted
`to be packed with bone graft material.
`
`20
`
`25
`
`30
`
`pl claim as my invention:
`1. A prosthetic device to integrate with and support
`vertebrae in a vertebral column which comprises a
`plurality of inert generally oval shaped rings conform-
`ing in shape and size with hard end plates of vertebrae
`on which it is to be seated, each of said rings having
`ridged top and bottom faces adapted to selectively in- 35
`terdigitate with surfaces of adjacent rings to form a
`stack and having peaks to bite into the end plates of
`adjoining vertebrae together with valleys between the
`peaks to receive bone ingrowth from the vertebrae for
`fusing the vertebrae together through the rings.
`2. The device of claim 1, wherein the peaks have side
`walls diverging at an angle of not substantially less than
`about 30°.
`
`40
`
`3. The device of claim 1, wherein the top and bottom
`faces of the rings fully mate together when the rings are 45
`used in a stack.
`.
`4. A prosthetic device for vertebral fusion which
`comprises a stack of annular rigid inert plugs having
`interiors and interdigitated ridged faces holding the
`plugs against displacement in the stack and ridged ex- 50
`posed‘end faces for bottoming on adjoining vertebrae,
`and a connecting bar extending through the stack hold-
`ing the plugs in aligned position in the stack.
`5. The prosthetic device of claim 4, wherein each of
`the plugs have diametrically opposed internal upstand- 55
`ing grooves receiving the connecting bar.
`6. The prosthetic device of claim 4, wherein the plugs
`have an internal connecting bar divides the interiors of
`the annular plugs into side by side compartments.
`7. A surgical prosthetic device adapted for fusing 60
`together adjoining vertebrae in a vertebral column
`which comprises a rigid inert annular plug sized and
`shaped to fit opposed end faces of vertebrae in a verte-
`bral column and having top and bottom faces with
`peaks adapted to bite into the end faces of the adjoining 65
`vertebrae and valleys between the peaks to receive bone
`ingrowth, said plug selected from the group consisting
`of oval and hemi-oval rings, and said plug having a
`
`8
`
`

`

`5,192,327
`
`9
`14. A prosthetic device seating on hard end plates of
`vertebrae in a vertebral column while preserving
`healthy disc tissue between the vertebrae which com-
`prises a rigid inert annular plug generally conforming in
`shape and size with opposing hard end plates of verte-
`brae on which it is to be seated, said plug having periph-
`eral side and end walls, top and bottom faces, a central
`aperture therethrough between the faces, and a periph-
`eral slot therein, said end faces having raised ridges with
`side walls converging to peaks and valleys between the
`
`10
`' side walls, said peaks adapted to be bottomed on and
`bite into the hard end plate faces of vertebrae, tool
`mounting means in a peripheral wall of the plug, said
`aperture and slot in the plug adapted to be packed with
`bone graft material and said plug having an anterior
`portion higher than the p