O
`5,607,424
`[11] Patent Number:
`[19]
`Unlted States Patent
`
`Tropiano
`[45] Date of Patent:
`Mar. 4, 1997
`
`lllllllllllllllll|l|||l||l|lll|llllllllllllllllllllllllllllllllllllllllllll
`USOOS607424A
`
`[54] DOMED CAGE
`
`[76]
`
`Inventor: Patrick Tropiano, 550, rue Paradis,
`Batiment Cl, 13 008 Marseille, France
`
`[21] App1.No.: 420,722
`[22] File(1‘
`A r 10 1995
`'
`p '
`’
`[51]
`Int. Cl.6 ..................................................... A61B 17/56
`[52] us, (:1, _________________________ 606/61; 606/17
`
`[58] Field of Search ........................... 606/61, 60; 623/17
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,932,969
`5,192,327
`5,458,638
`
`6/1990 Frey et a1.
`................................ 623/17
`
`3/1993 Brantigan ................ 623/17
`10/1995 Kuslich et a],
`........................... 623/17
`
`Primary Examineerichael Powell Buiz
`Assistant Examiner—Mark S. Leonardo
`
`Attorney, Agent, or Firm—John J. Byme
`
`ABSTRACT
`[57]
`A cage for use in a spinal repair system wherein a pair of
`inert, relatively open bone-graft contouring cages are dis—
`posed between adjacent vertebrae mounted to the honey
`structure of these vertebrae wherein the vertebrae will knit
`together and act as a single Imit- The upper and lower
`surfaces of the cages follow an arcuate path for increased
`contact with the abutting surfaces of the vertebrae them—
`selves.
`
`2 Claims, 1 Drawing Sheet
`
` 1
`
`NUVASIVE’I 104
`
`1
`
`

`

`US. Patent
`
`Mar. 4, 1997
`
`5,607,424
`
`
`
`2
`
`

`

`1
`DOMED CAGE
`
`5,607,424
`
`2
`
`BACKGROUND OF THE INVENTION
`
`One of the most troublesome and painful dysfunctions of
`the human body relates to the complicated but essential
`construction of the spinal column. As those skilled in the art,
`we are aware that the spinal column is comprised of a series
`of vertebrae that have flexible discs therebetween and an
`outgrowth of bones that include the dorsal and pedicle that
`serve, together with the vertebrae, to protect the spinal cord
`and, at the same time, provide spinal flexibility through
`slidable engagement with one another.
`These bone elements also provide openings through
`which various nerves and vessels can extend. When some—
`thing goes wrong with the spinal functions, the openings
`often pinch the nerve extending therethrough, causing a
`great deal of pain. One of the most common dysfunctions in
`the back is the rupture or a displacement of a disc between
`the vertebra. Modem medicine and science has not found a
`suitable disc replacement. Therefore, many spinal pains can
`be reduced or eliminated by fusing the adjacent vertebrae on
`either side of the injured disc. Although such a fusing
`reduces the degree of flexibility in the spinal column, such
`fusion is often the best medical procedure available for this
`condition. This invention relates generally to a cage appa—
`ratus that has arcuate upper and lower surfaces for enhanc—
`ing the medical procedure with which it is used.
`
`FIELD OF THE INVENTION
`
`One of the most costly health problems to society today
`involves back pain and pathology of the spine. This some-
`times devastating pathology can affect individuals at all
`stages in life and pull them from an active life at a relatively
`young age. Therefore, this pathology not only causes great
`suffering to the victims, it is also a burden to society which
`must provide for those who are removed from active life for
`decades. Thus, the cost of this pathology to society as a
`whole is considered to be in the billions of dollars each year.
`The spine is composed of bony vertebra with flexible
`discs therebetween in a resulting structure referred to as the
`vertebral colurrm. Because of its structure, it is capable of
`flexing and extending like a chain. Each vertebrae is com-
`posed of a body having two relatively large flat oblique-
`shaped surfaces into which the disc is attached. Extending
`out of the posterior aspect of the vertebral body are two tube
`like structures called the pedicels and attached to the
`pedicles are the lamina, facet joints and various processes
`referred to as the posterior elements. Together, two vertebrae
`with a disc and associated ligaments are called a vertebral
`motion segment. Therefore, an intact vertebral column is
`composed of several motion segments which are each com-
`posed of their corresponding vertebral bony, disc and liga-
`mentous structures. Combined, this structure functions as
`protection of the spinal cord, bears the load of the body and
`can bend. An intact vertebral column, with all of its posterior
`bony and soft
`tissue components, for a vertebral canal
`through which the spinal cord and its existing roots, as well
`as the vascular structures, may pass. The vertebral canal is
`divided into subdivisions which are of great important to the
`spine surgeon treating ailments because it is often here the
`pain generating pathology is found and the ailment
`is
`treated.
`
`The spine is subject to many pathologic and pain gener~
`ating changes which can occur in the disc, the posterior
`elements, and finally the vertebral body. These can be caused
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`by congenital deformities, traumatic injuries, degenerative
`changes at one or several motion segments at a time. Such
`changes can cause painful excessive motion, or collapse of
`a motion segment which contracts the spinal canal and
`compresses the neural structures to cause debilitating pain,
`paralysis, or both, which can cause nerve root compression,
`spinal stenosis, or excessive mobility which can be the
`source of severe pain. This can happen in one or several
`motion segments at the same time.
`For the surgeon treating this pathology, the ideal goal is to
`restore to degenerative motion segment and its spinal canal
`to their normal spatial relationship while assuring their
`normal functional movement and weight bearing capabili-
`ties. Unfortunately, no successful prothesis exist that satis-
`factorily replace the form and function of the disc, posterior
`elements and the vertebral body. The state of the art treat-
`ment remains an arthrodesis which means the fusion of 2 or
`more vertebral bodies of a motion segment together to make
`one solid bony segment. In the treatment described within
`the realm of this invention, the procedure with our invention
`can restore all of the normal functions except motion. That
`is, the surgeon can restore normal spatial relation between
`two vertebral bodies, assuring proper spinal alignment and
`balance, as well as restore the necessary openings for the
`neural and vascular structures to pass. Since the vertebrae
`are fused into one bone, painful motion is eliminated as well.
`Since a spine is composed of many motion segments,
`even with one segment fused for the relief of pain,
`the
`patient movement is minimally restricted in a manner that
`allows them to live a normal life. The current invention
`improves the reliability and precision of this procedure.
`The present invention relates to the surgical correction of
`spinal columns by fusion between adjacent vertebrae of a
`damaged disc. The invention provides
`specifically for
`unique, durable, cages that, although having considerable
`compressive strength, are open enough to contain a large
`amount of bone graft. The invention also relates to an
`arcuate structure that will stabilize the adjacent vertebrae.
`This structure will cause these generally concave surfaces to
`better mate with the generally convex surfaces of the adj a—
`cent vertebral surfaces.
`
`An objective of this invention is to provide an improved
`spinal support fixation and methodology which provide
`stability between adjacent vertebrae and the shape will help
`the cages stay in place.
`Another objective of the present invention is to provide
`apparatus which will aid in fixing appropriate elements in
`place until bone fusion occurs.
`Another very important objective of the invention is to
`provide cages that have arcuatc upper and lower surfaces,
`most of which are formed with large openings so that
`maximum bone graft material can be received and placed in
`contact with graft material outside the cage.
`A further objective of this invention is to provide unique
`cages for the fusion techniques involved which are entirely
`adaptable for use with the tooling with which physicians are
`currently skilled.
`Other objectives and advantages of this invention will be
`more apparent upon a reading of the following specification
`take together with the drawings.
`
`DISCUSSION OF THE PRIOR ART IN THE
`FIELD OF THIS INVENTION
`
`A good understanding of the cage—type fusion methodol-
`ogy can be obtained from Brantigan US. Pat. Nos. 4,743,
`
`3
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`

`

`3
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`5,607,424
`
`4
`
`256, 4,834,757 and 4,878,915; and in the co-pending appli-
`cation of Robert B. Lange, Jr., Ser. No. 08/235,943, filed
`May 2, 1994, now abandoned, my colleague. The Brantigan
`cages are of a type which this invention improves by
`providing an arcuate exterior surface and with adequate
`space bone graft material.
`Other advantages and features of the present invention
`will be apparent to those skilled in the art after reading the
`following specification with reference to the accompanying
`drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of the cage of this invention;
`FIG. 2 is a side elevation;
`FIG. 2a is an embodiment of the upper and lower surface
`edges;
`
`Note the imaginary arcuate lines 70, 72, 74 and 76. They
`are used to depict the front to rear dome-like shape of the
`cages along the upper and lower surfaces. Although the
`upper and lower edges of the struts are flat, they are in the
`curvilinear path so depicted.
`As seen in FIGS. 1 and 2, the upper and lower surfaces fall
`directly in the path of the arcuate planes defined by 70—72
`and 74—76, respectively. Note how the surfaces slant where
`necessary. As seen in FIG. 2a, the surfaces 50, 52, 54, 56,
`50', 52', 54' and 56' can also be flat with respect to the
`longitudinal axis of the cage but yet, as a group, fall in the
`arcuate planes.
`
`From the foregoing specification, it will be understood by
`those skilled in the art that this structure provides important
`contributions to spinal correction procedures by providing a
`synergism of elements between structure and bone that will
`permit the vertebrae to be knitted together with a balance
`and with a naturalness.
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`FIG. 3 is a top plan view of the cage as seen in FIG. 1;
`FIG. 4 is a diagrammatic plan showing the location of the
`cages with respect to the vertebrae; and
`
`20
`
`FIG. 5 is a diagrammatic elevation showing the generally
`convex shapes, somewhat exaggerated, of the vertebrae
`surfaces.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Refening now to the drawings wherein like elements
`indicate like parts, the cage of this invention is depicted by
`the numeral 10. The cage 10 has a pair of side surfaces 12
`and 14, a front surface 16, and a rear or posterior surface 18.
`The cage is completed by having a top 20 and a bottom 22.
`Intermediate the length of cage 10 are a pair of interior
`struts 24 and 26, which extend between sides 12 and 14 and
`engage the solid part of walls between the side openings.
`Side 12 has openings 28, 30 and 32, and side 14 has
`openings 34, 36 and 38. Surface 18 has a threaded opening
`39 to receive a positioning tool of a type well-known to
`those skilled in the art. Partitions or struts 24 and 26 divide
`the cage 10 into three compartments; namely, 40, 42 and 44.
`Note the smooth front surface of 16 and the other side walls.
`This provides surfaces which will not tear or mangle the
`delicate nerves and blood vessels near the site of the spinal
`cord.
`
`The upper edges 50, 52, 54 and 56 of the walls 16 and 18,
`and the struts 24 and 26 follow the curvilinear path defined
`by arcs 70 and 72. The lower edges thereof 50', 52', 54' and
`56' follow the curvilinear path defined by the arcs 74 and 76.
`In combination they form dome-like surfaces for the cage.
`These dome-like surfaces mate to some extent with the
`surfaces of the adjacent vertebrae. See FIG. 5. This is the
`essence of the improvement.
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`The embodiment disclosed is the invention as presently
`contemplated. However, the reader should understand that
`various changes and modifications can be made without
`departing from the spirit of
`the present
`invention as
`described in the following claim.
`I claim:
`
`1. In a spinal column where adjacent vertebrae have first
`and second opposed faces defining a space from which a disc
`has been removed, a device for replacing said disc compris-
`ing:
`a pair of inert cages each cage comprised of;
`first and second side walls respectively having first and
`second upper surfaces and first and second lower
`surfaces,
`a bottom surface extending between said first and
`second lower surfaces.
`a top surface extending between said first and second
`upper surfaces,
`an anterior plate at one end of said cage, and
`a posterior plate at the other end of said cage;
`said anterior and posterior plates being substantially solid
`except for a threaded opening in said posterior plate;
`a series of strut plates extending between said first and
`second side walls each of which have top and bottom
`edges and wherein said top edges form a portion of said
`top surface and wherein said bottom edges form a
`portion of said bottom surface;
`
`said bottom surface and bottom edges from forming an
`arcuate dome; and,
`
`said top surface and top edges forming a second arcuate
`dome.
`
`2. The cages of claim 1 wherein said domes are configured
`to follow the contours of their adjacent vertebrae surfaces.
`>l<
`*
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`*
`>1:
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`4
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`