_
`.
`Umted States Patent
`
`[19]
`
`Usoos443514A
`[11] Patent Number:
`
`5,443,514
`
`Steffee
`
`[45] Date of Patent:
`
`Aug. 22, 1995
`
`[54] METHOD FOR USING SPINAL INPLANTS
`[75]
`Inventor: Arthur D. Steffee, Novelty, Ohio
`
`[73] ASSIgnee: AcroMed Corporation, Cleveland,
`Ohio
`'
`[21] Appl No _ 130 288
`
`'
`
`OCt' 1’ 1993
`
`[22] Flled:
`A61F 2/44
`[51]
`Int Cl 6
`.
` i221 Eesldilf. Search""" =
`
`623/1g331/21236C82918
`"""""623/66606/60—64- 128/89§
`’
`’
`
`[56]
`
`.
`References Clted
`U-S- PATENT DOCUMENTS
`4,834,757 5/1989 Brantigan .............................. 623/17
`5,015,247
`5/1991 Michelson
`. 623/17
`
`5,306,309 4/1994 Wagner et a1.
`.. 623/17
`..
`
`FOREIGN PATENT DOCUMENTS
`0560141
`9/1993 European Pat. Off.
`.............. 623/17
`1107854 8/1984 U.S.S.R. ................................ 623/17
`
`Primary Examiner—Randall L. Green
`Assistant Examiner—Rob Clarke
`Attorney, Agent, or Firm—Tarolli, Sundheim & Covell
`[57]
`'
`ABSTRACT
`A method of fusing together the adjacent vertebrae
`using the spinal implant includes removing at least a
`portion of the spinal disc between the adjacent verte-
`brae. The spinal implant is inserted between the adja-
`cent vertebrae Wlth the first and second parallel Side
`surfaces facing the adjacent vertebrae. The spinal im-
`plant is rotated into a position in which the parallel side
`surfaces extend from one of the adjacent vertebrae to
`the other adjacent vertebrae and the upper and lower
`surfaces engage the adjacent vertebrae-
`
`7 Claims, 3 Drawing Sheets
`
`
`
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`US. Patent
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`Aug. 22, 1995
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`Sheet 1 of 3
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`5,443,514
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`Aug. 22, 1995
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`US. Patent
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`Aug. 22, 1995
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`Sheet 3 of 3
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`5,443,514
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`1
`
`5,443,514
`
`METHOD FOR USING SPINAL INPLANTS
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to a spinal implant, and
`to a method of using the Spinal implant to fuse together
`adjacent vertebrae of a spinal column.
`A known spinal implant has a rectangular shape and
`a tapered front end. The spinal implant includes nubs to
`grip adjacent vertebrae. The nubs have inclined front
`faces that accommodate forward sliding movement of
`the spinal implant into channels cut in the adjacent
`vertebrae. This known spinal implant is described in
`US Pat. No. 4,834,757. By cutting channels into the
`vertebrae for receiving the spinal implant nerve roots
`are put at risk.
`SUMMARY OF THE INVENTION
`
`The present invention provides a new and improved
`spinal implant and method of using the spinal implant to
`fuse together adjacent vertebrae of a spinal column. The
`spinal implant of the present invention includes first and
`second side surfaces extending substantially parallel to
`each other. Upper and lower surface means for engag—
`ing the adjacent vertebrae extend between the first and
`second side surfaces and extend from a first end portion
`to a second end portion of the spinal implant. Recesses
`in the first and second side surfaces receive an instru-
`ment for rotating the spinal implant when the implant is
`located between the adjacent vertebrae.
`The method of using the Spinal implant to fuse to—
`gether the adjacent vertebrae of a spinal column in-
`cludes removing at least a portion of the spinal disc
`between the adjacent vertebrae. The spinal implant is
`inserted between the adjacent vertebrae with the first
`and second substantially parallel side surfaces facing the
`adjacent vertebrae. The spinal implant is rotated into a
`position in which the parallel side surfaces extend from
`one of the adjacent vertebrae to the other of the adja—
`cent vertebrae and the upper and lower surface means
`engage the adjacent vertebrae. There are no channels
`cut in the adjacent vertebrae. Thus, the operation takes
`less time and lessens the risks to the patient.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other features of the present in—
`vention will become more apparent to one skilled in the
`art upon reading the following description of the pres-
`ent
`invention with reference to the accompanying
`drawings, wherein:
`FIG. 1 is an elevation view of a human spinal column
`having a spinal implant in accordance with that of the
`present invention placed therein;
`FIG. 2 is a perspective view of the spinal implant of
`FIG. 1;
`FIG. 3 is an enlarged plan View looking at a portion
`of the spinal implant of FIG. 2 from the side;
`FIG. 4 is a sectional view of an instrument for hold-
`ing the spinal implant of FIG. 2 to facilitate inserting the
`' spinal implant between adjacent vertebrae and rotating
`the spinal implant;
`FIG. 5 is a sectional view of an intermediate portion
`of the instrument of FIG. 4;
`FIG. 6 is a plan view of a handle of the instrument of
`FIG. 4;
`FIG. 7 is a sectional view of a clamp portion of the
`instrument of FIG. 4;
`
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`FIG. 8 is a plan view of the clamp portion of FIG. 7
`taken along the line 8—8 of FIG. ’7;
`FIG. 9 is a view showing a method of inserting spinal
`implants in a side-by-side relationship between adjacent
`vertebrae;
`FIG. 10 is a view similar to FIG. 9 further showing
`the method of inserting the spinal implants between the
`adjacent vertebrae;
`FIG. 11 is a view similar to FIG. 10 further showing
`the method of inserting the spinal implants between the
`adjacent vertebrae; and
`FIG. 12 is a view similar to FIG. 11 further showing
`the method of inserting the spinal
`implants between
`adjacent vertebrae.
`DESCRIPTION OF A PREFERRED
`EMBODIMENT
`
`One or a pair of substantially rigid spinal implants 10
`(one of which is shown in FIG. 1) are placed between
`adjacent vertebrae 12 and 14 of a spinal column 16 in a
`side-by-side relationship to fuse together the adjacent
`vertebrae. Preferably, the spinal implants 10 are made
`by injection molding a chopped carbon fiber reinforced
`polymer. However, the spinal implants 10 can be made
`of other suitable implantable materials such as stainless
`steel or titanium. Also, preferably, the ultimate tensile
`strength of the material used to make the spinal implants
`10 is higher than 10,000 psi so that the spinal implants
`will prevent relative movement between the adjacent
`vertebrae 12 and 14 and will support the compressive
`load of the spinal column.
`Each of the spinal implants 10 (FIG. 2) has parallel
`side surfaces 20 and 22. An upper surface 24 and a lower
`surface 26 for engaging the adjacent vertebrae 12 and 14
`extend between the side surfaces 20 and 22. The upper
`and lower surfaces 24 and 26 adjacent a first end portion
`30 of the spinal implant 10 are spaced apart by a first
`distance. The upper and lower surfaces 24 and 26 adja-
`cent a second end portion 32 of the spinal implant 10 are
`spaced apart a second distance. The second distance is
`preferably greater than the first distance to give the
`spinal implant a wedge shape for use in portions of the
`spine with a lordotic curve.
`The upper and lower surfaces 24 and 26 include a
`plurality of triangular-shaped teeth 36 that extend from
`the side surface 20 to the side surface 22 for engaging
`the vertebrae 12 and 14. Each tooth 36 (FIG. 3) includes
`a surface 40 facing toward the end portion 30. A surface
`42 of the tooth 36 faces the end portion 32 of the spinal
`implant 10. The surfaces 40 and 42 of the tooth 36 inter-
`sect each other to form an edge 44. The surfaces 40 and
`42 of adjacent teeth 36 intersect to form edges 46. The
`edges 46 are parallel to each other and lie in a plane 48.
`The surface 40 of the tooth 36 extends at an acute
`angle x to the plane 48. The surface 42 of the tooth 36
`extends at an acute angle y to the plane 48. Preferably,
`the angles x and y are equal and have a value of 45° so
`that surfaces 40 and 42 extend perpendicular to each
`other. Therefore, the teeth 36 are not preferential. The
`teeth 36 prevent the spinal implant 10 from moving
`toward the anterior portion of the spinal column 16 as
`much as they prevent the spinal implant from moving
`toward the posterior portion of the spinal column 16.
`A plurality of openings 56 and 58 extend from the
`side surface 20 to the side surface 22 to provide for
`blood flow and bone growth from one side of the im-
`plant 10 to the other side of the implant. The openings
`58 are located near the end portion 30 of the implant.
`
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`3
`The openings 56 and 58 extend perpendicular to the side
`surfaces 20 and 22. Preferably, there are five openings
`56 and two openings 58 extending between the sides 20
`and 22. The openings 56 have diameters larger than the
`diameters of the openings 58. The sizes of the diameters
`of the openings 56 and 58 may be any size that allows
`tissue ingrowth and blood flow between the side sur-
`faces 20 and 22 of the implant 10.
`The side surface 20 includes a recess 60 and the side
`surface 22 includes a recess 62. The openings 58 are
`located in the recesses 60 and 62. Each of the recesses 60
`and 62 includes a planar bottom surface 64. The recesses
`60 and 62 also include parallel side surfaces 66 and 68
`extending perpendicular to the bottom surface 64 and
`from the end portion 30 of the spinal implant 10 toward
`the end portion 32. An arcuate side surface 70 extends
`between the parallel side surfaces 66 and 68. The reces-
`ses 60 and 62 in the side surfaces 20 and 22 are for re—
`ceiving an instrument 80 (FIG. 4) that holds the spinal
`implant 10 to facilitate insertion of the spinal implant
`between the adjacent vertebrae 12 and 14 and rotation
`of the spinal implant once between the adjacent verte-
`brae.
`Any instrument that firmly holds the implant and
`permits the implant to be rotated into position can be
`used. One such instrument 80 (FIG. 4) includes an inter-
`mediate portion 82 (FIG. 5), a handle 84 (FIG. 6) and a
`clamp portion 86 (FIGS. 7 and 8).
`The intermediate portion 82 (FIG. 5) is generally
`cylindrical and includes an opening 92 extending along
`the axis of the intermediate portion. The opening 92
`includes a first cylindrical portion 94 extending from an
`end portion 96 of the intermediate portion 82 to a cen-
`tral portion 98. A second cylindrical portion 100 of the
`opening 92 extends from the first cylindrical portion 94
`to a tapered portion 102 of the opening 92. The second
`cylindrical portion 100 of the Opening 92 has a diameter
`larger than the diameter of the first cylindrical portion
`94. The tapered portion 102 of the opening 92 tapers
`from a small diameter adjacent the portion 100 to a
`larger diameter adjacent an end portion 104 of the inter-
`mediate portion 82.
`The intermediate portion 82 includes a large outer
`diameter portion 108 that extends from the end portion
`96 to the central portion 98. The portion 108 tapers
`from a large outer diameter to a small outer diameter
`portion 110 which extends from the portion 108 to the
`end portion 104. The outer surface of the portion 108 is
`preferably knurled to provide for easy gripping of the
`intermediate portion 82 by a surgeon. The end portion
`96 has a diameter which is smaller than the portions 108
`and 110.
`The handle 84 (FIG. 6) has a large diameter knurled
`portion 116. A small diameter shaft 118 extends from
`the knurled portion 116. The shaft 118 has a threaded
`end 120 for threadably engaging the clamp portion 86.
`The clamp portion 86 (FIGS. 7 and 8) includes a stem
`126 with an internally threaded opening 128 for receiv-
`ing the threaded end 120 of the handle 84. A pair of
`clamp halves 130 are spaced apart and extend from the
`stem 126. The clamp halves 130 have outwardly taper-
`ing surfaces 132. The surfaces 132 taper from the stern
`126 to a groove 134.
`The clamp halves 130 include extensions 136 which
`are received in the recesses 60 and 62 in the side surfaces
`20 and 22 of the spinal implant 10. The extensions 136
`include planar inner surfaces 138 (FIG. 7) for engaging
`the bottom planar surfaces 64 of the recesses 60 and 62.
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`Parallel side surfaces 140 and 142 (FIG. 8) of the exten-
`sions 136 engage side surfaces 66 and 68 of the recesses
`60 and 62 when the instrument 80 is used to hold the
`spinal implant 10. Arcuate side surface 144 for engaging
`the side surface 70 extends between the side surfaces 140
`and 142.
`The shaft 118 of the handle 84 extends into the open-
`ing 92 in the intermediate portion 82 and threadably
`engages the stem 126 of the clamp portion 86 (FIG. 4).
`As the handle 84 is threaded into the opening 128 of the
`clamp portion 86, the clamp portion is drawn into the
`opening 92 in the intermediate portion 82. The tapered
`surfaces 132 of the clamp halves 130 engage the tapered
`portion 102 of the opening 92. As the clamp portion 86
`is drawn into the opening 92, the clamp halves 130 are
`forced toward each other by the tapered portion 102 of
`the opening 92 to clamp the spinal implant 10 between
`the extensions 136.
`The method of placing the spinal implants 10 between
`the adjacent vertebrae 12 and 14 to fuse together the
`adjacent vertebrae will now be described. Most of the
`spinal disc located between the vertebrae 12 and 14 is
`removed. The facing surfaces of the vertebrae 12 and 14
`are cleaned with a disc shaver and rongeurs. Preferably,
`an annulus of the spinal disc is left between the verte—
`brae 12 and 14.
`The instrument 80 is used to hold a spinal implant 10.
`The spinal implant 10 is inserted posteriorly or anteri-
`orly between the vertebrae 12 and 14 with the parallel
`sides surfaces 20 and 22 facing the adjacent vertebrae 12
`and 14 (FIG. 9). The spinal implant 10 is inserted so that
`the end portion 32 is near the anterior side of the spinal
`column 16 and the end portion 30 is near the posterior
`side of the spinal column. The spinal implant 10 is ro—
`tated 90° to the position shown in FIG. 10 so that the
`teeth 36 on the upper and lower surfaces 24 and 26
`engage the vertebrae 12 and 14 and the side surfaces 20
`and 22 extend from the vertebra 12 to the vertebra 14.
`The wedge shape of the spinal implant 10 alleviates the
`need to distract the posterior portion of the spine seg-
`ment a large distance and then compress the posterior
`portion to achieve the required lordosis. The posterior
`portion only needs to be distracted to the desired inter-
`discal height.
`A second spinal implant 10 is inserted between the
`vertebra 12 and 14 in a side-by-side relationship with the
`spinal implant. The second spinal implant 10 is inserted
`in a similar manner as the first implant. The instrument
`80 is used to hold the spinal implant 10. The spinal
`implant 10 is inserted with the parallel side surfaces 20
`and 22 facing the vertebrae 12 and 14 (FIG. 11). The
`second spinal implant 10 is then rotated 90° to the posi-
`tion shown in FIG. 12 so that the teeth 36 of the upper
`and lower surfaces 24 and 26 engage the vertebrae 12
`and 14.
`The remaining space between the spinal implants 10
`and the adjacent vertebrae 12 and 14 is packed with
`autograft or allograft bone. An apparatus for maintain-
`ing the vertebrae 12 and 14 in a desired spatial relation-
`ship such as that disclosed in US. Pat. No. 4,696,290 is
`attached to the spinal column 16 until the vertebrae 12
`and 14 have completely fused together. The apparatus
`for maintaining the vertebrae 12 and 14 in the desired
`spatial relationship prevents the spinal implants 10 from
`moving out of position and the bone graft from falling
`out of the spaces between the Spinal implants and the
`vertebrae 12 and 14.
`
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`5,443,514
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`the following is
`
`5
`From the above description of the invention, those
`skilled in the art will perceive improvements, changes
`and modifications. Such improvements, changes and
`modifications within the skill of the art are intended to
`be covered by the appended claims.
`Having described the invention,
`claimed:
`1. A method of fusing together adjacent vertebrae of
`a spinal column comprising the steps of:
`removing at least a portion of the disc between the
`adjacent vertebrae;
`providing a spinal implant with first and second side
`surfaces substantially parallel to each other and
`upper and lower surface means extending between
`the first and second side surfaces;
`inserting the spinal
`implant between the adjacent
`vertebrae with the first and second substantially
`parallel side surfaces of the spinal implant facing
`the adjacent vertebrae; and
`rotating the spinal implant into a position in which
`the parallel side surfaces of the spinal implant ex-
`tend from one of the adjacent vertebrae to the
`other adjacent vertebrae and the upper and lower
`surface means engage the adjacent vertebrae.
`2. A method as set forth in claim 1 further including
`providing the spinal implant with first and second end
`portions wherein the upper and lower surface means are
`
`6
`spaced apart by a first distance adjacent the first end
`portion and are spaced apart by a second distance
`greater than the first distance adjacent the second end
`portion.
`3. A method as set forth in claim 2 wherein said step
`of inserting the spinal implant includes inserting the
`spinal implant from the posterior side of the spinal col-
`umn into a position in which the first end portion of the
`spinal implant is located adjacent the posterior side of
`the spinal column and the second end portion of the
`spinal implant is located adjacent the anterior side of the
`spinal column.
`4. A method as set forth in claim 1 wherein said step
`of inserting the spinal implant includes inserting two
`spinal implants in a side-by—side relationship.
`5. A method as set forth in claim 1 further including
`the step of packing bone graft around the spinal implant
`after said step of rotating the spinal implant.
`6. A method as set forth in claim 1 further including
`the step of attaching an apparatus to the spinal column
`for maintaining a desired spatial relationship of the adja-
`cent vertebrae.
`7. A method as set forth in claim 1 wherein said step
`of removing at least a portion of the spinal disc includes
`leaving an annulus of the disc around the peripheries of
`the adjacent vertebrae.
`it
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