(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2003/0028249 A1
`(43) Pub. Date:
`Feb. 6, 2003
`Baccelli et al.
`
`US 20030O28249A1
`
`INTERVERTEBRALIMPLANT WITH
`TOOTHED FACES
`
`Inventors: Christian Baccelli, Ayguemorte Les
`Graves (FR); Jacques Senegas,
`Merignac (FR); Evan Zeiger,
`Birmingham, AL (US); Tarcisio Barros,
`Sao Paolo SP (BR); Dietmar Salger,
`Retgendorf (DE); Franck Van Den
`Eeden, Massenar (NL)
`Correspondence Address:
`LERNER, DAVID, LITTENBERG,
`KRUMHOLZ & MENTLIK
`600 SOUTHAVENUE WEST
`WESTFIELD, NJ 07090 (US)
`Assignee: Stryker Spine, Cestas (FR)
`Appl. No.:
`10/124,153
`Filed:
`Apr. 17, 2002
`
`Related U.S. Application Data
`(63) Continuation-in-part of application No. PCT/FR00/
`02899, filed on Oct. 18, 2000.
`Foreign Application Priority Data
`
`(30)
`
`Oct. 18, 1999 (FR)............................................ 99/12951
`Publication Classification
`
`(51) Int. Cl. .................................................... A61F 2/44
`(52) U.S. Cl. .......................................................... 623/17.11
`
`(57)
`
`ABSTRACT
`
`The intervertebral implant has two mutually opposite main
`faces (8, 10), at least one of which faces (8) has mutually
`parallel shaped teeth (12). The general shape of the profile
`of Said toothed face (8) in at least one plane extending
`transversely to Said face, is not rectilinear.
`
`(54)
`
`(75)
`
`(73)
`(21)
`(22)
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`ALPHATEC HOLDINGS, INC., ALPHATEC SPINE INC.
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`Patent Application Publication
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`Feb. 6, 2003 Sheet 1 of 4
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`US 2003/0028249 A1
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`Patent Application Publication
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`Feb. 6, 2003 Sheet 2 of 4
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`US 2003/0028249 A1
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`Patent Application Publication
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`Feb. 6, 2003 Sheet 3 of 4
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`US 2003/0028249 A1
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`ALPHATEC HOLDINGS, INC., ALPHATEC SPINE INC.
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`Patent Application Publication
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`Feb. 6, 2003. Sheet 4 of 4
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`US 2003/0028249 A1
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`ALPHATEC HOLDINGS, INC., ALPHATEC SPINE INC.
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`US 2003/0028249 A1
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`Feb. 6, 2003
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`INTERVERTEBRAL MPLANT WITH TOOTHED
`FACES
`0001. The invention relates to intervertebral implant.
`0002 Intervertebral implant are known that have mutu
`ally parallel elongate teeth on both main faces. Such teeth
`Serve to anchor the prosthesis between the vertebrae adja
`cent to the disk Space occupied by the implant.
`0003. An object of the invention is to provide an implant
`that ensures even better anchoring.
`0004.
`In order to achieve this object, the invention pro
`vides an intervertebral implant having two mutually oppo
`Site main faces, at least one of these faces having mutually
`parallel shaped teeth, in which the general shape of the
`profile of the toothed face in at least one plane extending
`transversely to Said face is not rectilinear.
`0005 Thus, the profile of the toothed face can be selected
`So as to be as complementary as possible to that of the
`vertebral plate with which said face is to come into contact.
`Whereas the prior art implants could require the face of the
`vertebral plate to be prepared by modifying its shape in order
`to improve contact with the implant, Such preparation is
`usually pointless with the toothed face of the implant of the
`invention. This reduces the duration of the Surgical operation
`required for installing the implant. The toothed and plate
`shaped face makes it possible to achieve very high quality
`anchoring against the vertebral plate.
`0006 Advantageously, the profile of the toothed face
`presents two Segments of generally rectilinear shape that are
`inclined relative to each other.
`0007 Such a face is particularly adapted to the shapes of
`the plates of certain vertebrae.
`0008 Advantageously, one of the two segments is at least
`twice as long as the other Segment.
`0009. The face thus has an airplane-wing profile corre
`sponding very closely to the shape of certain vertebral
`plates.
`Advantageously, the toothed face has a Zone that
`0.010
`forms one of the Segments, and that has no teeth.
`0.011) Advantageously, the toothed face has a Zone that is
`without teeth and that is contiguous with an edge of the face.
`0012 Advantageously, the implant has a central hole
`extending from one of the main faces to the other.
`0013 Such a hole can, for example, receive the graft that
`facilitates vertebral bone integration.
`0.014
`Advantageously, the implant has a side wall pre
`Senting at least one orifice extending from an outer face of
`the wall to the central hole.
`0.015 Thus, this orifice increases the vascularization of
`the graft housed in the hole.
`0016 Advantageously, the implant has a side face con
`Stituted by a first cylindrical portion extending over more
`than 180 about a cylinder axis, and a second cylindrical
`portion of greater radius than the first portion.
`0017 Such a shape enables the implant to occupy the
`major portion of the area of the vertebral plates.
`
`0018 Advantageously, the teeth have a profile that slopes
`towards the same Side of the implant.
`0019. This shape facilitates insertion of the implant
`between the plates, but it constitutes a brake on withdrawing
`it.
`0020 Advantageously, the implant has at least one spike
`projecting from one of its main faces, in particular from its
`toothed face.
`0021. Thus, the spike digs into the vertebral plate and
`further increases the quality of the anchoring.
`0022 Advantageously, the implant has a tapped orifice.
`0023 This orifice can co-operate with a tool for position
`ing the implant, by enabling the tool to be fixed to the
`implant. It can also be used to connect the implant to a
`prosthetic plate fixed laterally on the vertebral bodies.
`0024 Advantageously, the implant is a cervical implant.
`0025 Advantageously, the implant is made of bioresorb
`able material.
`0026. The invention also provides a kit comprising an
`implant of the invention and a tool for positioning it.
`0027 Advantageously, the implant and the tool have
`fixing means for fixing the implant to the tool in a prede
`termined relative position, and keying means organized to
`ensure that there is only one Such position.
`0028. Other characteristics and advantages of the inven
`tion appear further from the following description of a
`preferred embodiment and of a variant given as non-limiting
`examples. In the accompanying drawings:
`0029 FIGS. 1 to 5 are respectively a perspective view, a
`plan view, a face View, a rear view, and a right-hand View of
`an implant constituting a preferred embodiment of the
`invention;
`0030 FIGS. 6 and 7 are section views of a cervical
`vertebra respectively in the Sagittal and the frontal mid
`planes;
`0031 FIGS. 8 and 9 are perspective views of the FIG.
`1 implant together with its fitting tool; and
`0032 FIG. 10 is a fragmentary view analogous to FIG.
`4 showing a variant embodiment.
`0033. With reference to FIGS. 1 to 5, the implant 2 is
`constituted by a cage having a wall 4 that is generally
`annular about an axis 6.
`0034.
`In plan view, the wall has a first portion 4a that is
`horseshoe shaped. The portion 4a is cylindrical about the
`axis 6. It extends over about 250 around the axis 6. The wall
`has a Second portion 4b that is also cylindrical in Shape,
`extending over about 20 about its own axis, which is not the
`axis 6 but is an axis parallel thereto. The radius of the Second
`portion 4b is much greater than that of the first portion 4a.
`The ends of the first portion are joined to the ends of the
`Second portion. In plan View, the cage is thus in the form of
`a ring that is somewhat flattened on a side 4b which in this
`case is the anterior or front Side of the cage. This wall 4
`defines a hole 7 in the center of the cage.
`0035. The cage has two main faces, a Superior main face
`8 and an inferior main face 10 that are opposite to each other
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`and that extend generally in planes that are mutually parallel
`and perpendicular to the axis 6. The hole 7 extends between
`both faces 8 and 10.
`0.036 The inferior face 10 in this case is precisely per
`pendicular to the axis 6. In a Sagittal plane, i.e. parallel to the
`axis 6 and perpendicular to the front wall 4b, it presents a
`toothed profile forming mutually parallel elongate teeth 12
`parallel to the front wall 4b. All of the teeth 12 are identical
`to one another and in particular they are all of the same
`height. All of the teeth slope forwards. Each of them has a
`front flank parallel to the axis 6 and a rear flank that slopes.
`0037. In the above-specified Sagittal plane, the Superior
`face 8 has a profile that is made up of two Segments 14 and
`16 of generally rectilinear shape that are inclined relative to
`each other So as to give the profile a shape that is convex.
`The rear Segment 16 is the longer of the two Segments. In
`this plane, it extends over about 80% of the length of the
`cage. The Segment has a profile that is toothed. All of the
`teeth 12 are identical to one another, and in particular they
`all have the same height. They slope forwards like the teeth
`of the inferior face 10. The segment 16 slopes slightly
`towards the rear of the cage. It is therefore Slightly inclined
`relative to the inferior face 10.
`0.038. The front segment 14 is inclined towards the front
`of the cage more Steeply than the rear Segment is inclined
`towards the rear. Its length is equal to about one-fourth the
`length of the rear Segment 16. The front Segment 14 is
`Smooth. It corresponds to the portion of the Superior face
`that extends over the front wall 4b. The two segments 14 and
`16 give the top face 8 a profile that is similar to that of an
`airplane Wing.
`0.039 The cage has a threaded assembly and fixing orifice
`18 extending in the Sagittal midplane of the implant, in the
`front wall 4b, and putting the outside face thereof into
`communication with the central hole 7. On one side of this
`orifice 18, e.g. on the right Side thereof, the Outer face of the
`front wall has a hemispherical cavity 20 which is used for
`keying purposes, as described below.
`0040. On the rearmost portion of the wall, the cage has
`two orifices 22 also putting the outer face into communica
`tion with the central hole 7. The two orifices 22 are disposed
`Symmetrically about the Sagittal midplane of the cage.
`0041. The cage has spikes 24, in this case four such
`Spikes, i.e. two associated with each of the main faces 8 and
`10. Each Spike has a pointed end and it projects from the
`asSociated main face. The two Spikes on each face are
`disposed symmetrically to each other about the Sagittal
`midplane. In addition, they extend in the frontal midplane
`containing the axis 6. Each Spike on one face extends in
`register with a Spike on the other face.
`0042. The cage as described above is particularly adapted
`to occupying a cervical intervertebral space. FIGS. 6 and 7
`show a vertebral body 31 of a cervical vertebra 30. In section
`on the Sagittal midplane of FIG. 6, the Superior plate 32 of
`the vertebra has a profile that is substantially horizontal and
`rectilinear while the inferior plate 34 has a profile that is
`concave, matching the profile of an airplane wing, and
`complementary to the convex profile of the Superior face 8
`of the cage. In Section on a front midplane, as shown in FIG.
`7, the inferior plate 34 has a profile that is substantially
`
`horizontal and rectilinear, while the Superior plate 32 has a
`concave curved profile whose high points are the incuS 36.
`0043. When the cage is inserted between two cervical
`vertebrae 31, the main faces 8 and 9 of the cage thus fit very
`closely to the shape of the plates 32 and 34 with which they
`come into contact.
`0044) To put the cage into place, it is advantageous to use
`a fitting tool 40 such as the tool shown in FIGS. 8 and 9.
`This tool comprises a body 42 having a head 44 with a front
`face 46 of rectangular shape, whose shape and height are
`close to those of the front face of the cage 2. The tool has a
`threaded endpiece 48 emerging from the center of the face
`46 of the head and movable relative thereto, being drivable
`from the other end of the tool. This endpiece is suitable for
`threaded engagement with the mounting orifice 18 of the
`cage. The front face 46 of the head has a Spherical projection
`47 suitable for penetrating in the front spherical cavity 20 of
`the cage when the endpiece 48 is connected to the orifice 18.
`The projection 47 and the cavity 20 together constitute
`keying means. Because of them, there is only one position
`in which the tool 40 can be fixed to the cage 2 with the
`outlines of the front face of the cage coinciding with those
`of the head 44 of the tool.
`004.5 To put the cage into position between the vertebrae,
`the vertebrae are moved apart by appropriate means So as to
`increase the height of the disk gap between the Vertebrae.
`The Superior plate 32 of the inferior vertebra 10 is prepared
`so as to come close to the shape of the inferior face 10 of the
`cage. Prior to mounting, the hole 7 receives a bone graft or
`any other Substance for enabling bone growth. With the cage
`mounted on the tool, the cage is put into place between the
`vertebrae from behind. The vertebrae are then allowed to
`move back towards each other. The vertebral plates 32 and
`34 thus bear against the main faces 8 and 9 of the cage. The
`Spikes 24 anchor themselves in the plates. After facilitating
`insertion of the cage, the orientation of the teeth 12 limits the
`ability of the cage to move forwards from its position. The
`cage does not require the inferior plate 34 of the Superior
`vertebra to be prepared.
`0046) In a variant embodiment shown in FIG. 10, the
`inferior face of the cage, is still toothed (although that is not
`shown) and its shape in Section parallel to the frontal plane
`is a convex circularly arcuate curve. Such a cage does not
`require the Superior plate 32 of the inferior vertebra to be
`prepared and as a result there is no need to prepare any
`vertebral plate. Such a cage is therefore well adapted to the
`anatomy of the intervertebral Space.
`0047 The mounting orifice 18 can be used to fix the cage
`to an anchor System, e.g. an anterior prosthetic plate
`anchored elsewhere in the lateral faces of the vertebral
`bodies 31.
`0048. The three orifices 18 and 22 facilitate vasculariza
`tion of the graft received in the hole 7.
`0049. To further improve the keying, the head 44 of the
`tool can carry a mark 45 indicating the Superior face 8 of the
`cage when the cage is properly fixed to the tool.
`0050. The cage can be made of a material that is trans
`parent to X-rays, e.g. Out of poly-ether-ether-ketone
`(PEEK). In which case, the cage can have one or more
`markers 47 included therein and Serving, because they are
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`opaque to X-rays, to identify the position and/or the pres
`ence of the implant when X-rays are taken during or after the
`operation. They could be made of titanium or of titanium
`alloy. In this case, there are two markerS 47 and they are
`constituted by wires inserted in rectilinear ducts parallel to
`the axis 6 and formed in the wall of the cage. One of the
`ducts extends at the rear in the Sagittal midplane, while the
`other extends at the left end of the front wall.
`0051. The spikes 24 can be inserted and fixed rigidly in
`the ducts formed in the cage. They too can be made of a
`material that is opaque to X-rayS.
`0.052
`In another embodiment, the cage can be made of a
`material that is bioresorbable.
`1/ An intervertebral implant (2) having two mutually
`opposite Superior (8) and inferior (10) main faces, at least
`the Superior face (8) having mutually parallel shaped teeth
`(12), the implant being characterized in that the general
`shape of the profile of the Superior toothed face (8) in at least
`one plane extending transversely to Said face is not recti
`linear.
`2/ An implant according to claim 1, characterized in that
`the profile of the toothed face (8) presents two segments (14,
`16) of generally rectilinear shape that are inclined relative to
`each other.
`3/. An implant according to claim 2, characterized in that
`one of the two segments (16) is at least twice as long as the
`other segment (14).
`4/ An implant according to claim 2 or 3, characterized in
`that the toothed face has a Zone (14) that forms one of the
`Segments, and that has no teeth.
`5/ An implant according to any one of claims 1 to 4,
`characterized in that the toothed face (8) has a Zone (14) that
`is without teeth and that is contiguous with an edge of the
`face.
`
`6/ An implant according to any one of claims 1 to 5,
`characterized in that it has a central hole (7) extending from
`one of the main faces (8, 10) to the other.
`7/ An implant according to claim 6, characterized in that
`it has a side wall presenting at least one orifice (18, 22)
`extending from an outer face of the wall to the central hole
`(7).
`8/ An implant according to any one of claims 1 to 7,
`characterized in that it has a side face (4) constituted by a
`first cylindrical portion (4a) extending over more than 180°
`about a cylinder axis (6), and a second cylindrical portion
`(4b) of greater radius than the first portion (4a).
`9/ An implant according to any one of claims 1 to 8,
`characterized in that the teeth (12) have a profile that slopes
`towards the same Side of the implant.
`10/ An implant according to any one of claims 1 to 9,
`characterized in that it has at least one spike (24) projecting
`from one of its main faces (8, 10), in particular from its
`toothed face.
`11/ An implant according to any one of claims 1 to 10,
`characterized in that it has a tapped orifice (18).
`12/ An implant according to any one of claims 1 to 11,
`characterized in that it is a cervical implant.
`13/ An implant according to anyone of claims 1 to 12,
`characterized in that it is made of bioresorbable material.
`14/A kit, characterized in that it comprises an implant (2)
`according to any one of claims 1 to 13, and a tool (40) for
`fitting Said implant.
`15/ A kit according to claim 14, characterized in that the
`implant (2) and the tool (40) have fixing means (18,48) for
`fixing the implant to the tool in a predetermined relative
`position, and keying means (20, 47) organized to ensure that
`there is only one Such position.
`
`k
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`k
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`k
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`k
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`k
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