U.S. patent application number 13/012626 was filed with the patent office on 2011-05-19 for intervertebral implant.
Invention is credited to Christopher Marden John Cain, Claude Mathieu.
Application Number | 20110118843 13/012626 |
Document ID | / |
Family ID | 27740041 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110118843 |
Kind Code |
A1 |
Mathieu; Claude ; et
al. |
May 19, 2011 |
INTERVERTEBRAL IMPLANT
Abstract
The intervertebral implant is in the form of a three-dimensional
structure (10) comprising (a) a top side (1) and an underside (2)
which are designed to rest against the end plates of two adjacent
vertebras, (b) a left side face (3) and a right side face (4), (c)
a front face (5) and a rear face (6), (d) a horizontal center plane
situated between the top side (1) and the underside (2), (e) a
vertical center plane (8) situated between the left side face (3)
and the right side face (8) and (f) a plurality of boreholes (9)
passing through the implant structure (10) that are designed to
receive longitudinal affixation elements (20), the axes (19) of
said elements intersecting the horizontal center plane (7). At
least one of the boreholes (9) is designed in a manner that the
affixation element (10) received in it can be rigidly connected to
the intervertebral implant. Said connection is implemented using a
thread or by matching conical surfaces.
Inventors: |
Mathieu; Claude; (Zuerich,
CH) ; Cain; Christopher Marden John; (Eastwood,
AU) |
Family ID: |
27740041 |
Appl. No.: |
13/012626 |
Filed: |
January 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12574222 |
Oct 6, 2009 |
7875076 |
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13012626 |
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11751757 |
May 22, 2007 |
7618456 |
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12574222 |
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10923534 |
Aug 19, 2004 |
7232464 |
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11751757 |
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PCT/CH02/00099 |
Feb 19, 2002 |
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10923534 |
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Current U.S.
Class: |
623/17.11 |
Current CPC
Class: |
A61F 2002/30777
20130101; A61F 2310/00011 20130101; A61F 2002/30774 20130101; A61F
2002/30004 20130101; A61B 17/86 20130101; A61F 2250/0014 20130101;
A61F 2/447 20130101; A61F 2002/3079 20130101; A61F 2/4465 20130101;
A61B 17/8052 20130101; A61F 2002/30593 20130101; A61F 2002/30841
20130101; A61F 2/442 20130101; A61F 2/4455 20130101 |
Class at
Publication: |
623/17.11 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. A bone stabilizing system for stabilizing first and second
vertebrae in a spinal column comprising: a plurality of bone screws
having a threaded shaft and a head, the shaft having a longitudinal
central axis; a three dimensional body configured for insertion
between the endplates of vertebrae, the three dimensional body
having an upper surface for abutting the endplate of the first
vertebrae, a lower surface for abutting the endplate of the second
vertebrae, a front surface, and a horizontal center plane between
the upper and lower surface; and a front plate having a top surface
and a bottom surface, the plate coupleable to the body such that
the bottom surface is adjacent to and at least partially overlies
the front surface, the plate having a plurality of screw holes for
receiving the shafts of the screws, the screw holes extending
through the plate and having a central axis, at least two screw
holes extending through the plate at an angle such that the central
axis of the screw hole ranges from about 25.degree. to about
70.degree. with respect to the horizontal center plane or a plane
parallel to the horizontal center plane.
2. The system of claim 1, wherein the three dimensional body has a
plurality of boreholes, the boreholes extending from the front
surface to at least one of the upper surface and the lower
surface.
3. The system of claim 2, wherein, when the plate is coupled to the
three-dimensional body, the three-dimensional body and at least one
of the angled screw holes in the front plate is configured and
oriented such that one of the screws inserted into that angled
screw hole pierces at least partially at least one of the upper
surface and the lower surface of the three-dimensional body.
4. The system of claim 1, wherein, when the front plate is secured
to the three-dimensional body, the central axis of at least one of
the angled screw holes extends toward the upper surface of the
three-dimensional body and the axis of at least one of the angled
screw holes extends toward the lower surface of the
three-dimensional body.
5. The system of claim 1, wherein the three-dimensional body is
made from a non-metallic material.
6. The system of claim 5, wherein the front plate is formed of a
metallic material.
7. The system of claim 1 wherein the front plate has a superior
surface and an inferior surface and a height between the superior
surface and the inferior surface and wherein the front surface of
the three-dimensional body has a height between the upper surface
and lower surface that is substantially equal to the height of the
front plate.
8. The system of claim 1, wherein the first plate has a superior
surface and an inferior surface and a height between the superior
surface and the inferior surface and the three-dimensional body has
a height between the upper surface and lower surface, wherein the
maximum height of the three-dimensional body is substantially equal
to or greater than the height of the front plate.
9. The system of claim 1, wherein the three-dimensional body
further includes at least one borehole in communication with the
front surface and one of the upper surface or the lower surface and
the front plate is couplable with the three dimensional body so
that at least one of the angled screw holes formed in the front
plate aligns with the at least one borehole in the
three-dimensional body so that one of the bone screws is insertable
through the angled screw hole formed in the plate, through the
recess formed in the three dimensional bodies and into one of the
vertebrae.
10. The system of claim 1, wherein the three dimensional body
includes at least one through hole extending from the upper surface
to the lower surface.
11. The system of claim 1, wherein at least one of the angled screw
holes formed in the front plate is conically shaped such that it
tapers conically towards the front plate's bottom surface.
12. The system of claim 1, wherein one of the angled screw holes in
the front plate includes internal threads, and at least a portion
of the head of one of the bone screws has external threads for
engaging the internal thread of the angled screw hole.
13. The system of claim 1, wherein at least one the angled screw
holes in the front plate has internal threads and that threaded
portion is conically tapered and wherein a plurality of the bone
screws have at least a portion of their heads externally
threaded.
14. The system of claim 1, wherein one of the upper and lower
surfaces of the three-dimensional body is convex.
15. The system of claim 1, wherein the front plate has a plurality
of angular screw holes and the three-dimensional body has a
plurality of boreholes for alignment with the angular screw holes
wherein the angular screw holes when aligned with the boreholes
form passages for the screws that diverge as the passages extend
away from the front surface into the three-dimensional body.
16. The system of claim 1, wherein the front plate has a plurality
of angular screw holes and the three-dimensional body has a
plurality of boreholes for alignment with the angular screw holes,
wherein the angular screw holes when aligned with the boreholes
form passages for the screws that are parallel as they extend away
from the front surface into the three-dimensional body.
17. The system of claim 1, wherein the three dimensional body
further has a convex left side surface, a convex right side surface
and a back surface.
18. The system of claim 2, wherein the three-dimensional body
further includes a left-side surface, a convex right side surface
and a back surface, and the three-dimensional body does not have
boreholes to receive screws that pass through either the left side
or the right side.
19. The system of claim 1, wherein the three-dimensional body has
angular boreholes that extend from the front face to at least one
of the upper surface and the lower surface and the boreholes do not
cross the horizontal plane.
20. A spine stabilizing system for stabilizing first and second
vertebrae in a spinal column comprising: a plurality of bone screws
having a threaded shaft and a head, the shaft having a longitudinal
central axis; a three dimensional body formed of plastic configured
for insertion between endplates of the first and second vertebrae,
the three dimensional body having an upper surface for abutting the
endplate of a first vertebrae, a lower surface for abutting the
endplate of a second vertebrae, a front surface, and a horizontal
center plane between the upper and lower surface; and a front plate
formed of a metallic material having a top surface, a bottom
surface, a superior surface and an inferior surface, the plate
couplable to the three dimensional body such that the bottom
surface overlies the front surface, the plate having a plurality of
screw holes for receiving there through the shaft of the screws,
the screw holes having a central axis and extending through the
plate at an angle such that the central axis of the screw hole
ranges from about 25.degree. to about 70.degree. with respect to
the horizontal center plane or a plane parallel to the horizontal
center plane, wherein a first angled screw hole is angled in the
front plate toward the superior surface of the front plate and the
second angled screw hole is angled in the front plate toward the
inferior surface of the front plate.
21. The system of claim 20, wherein at least one of the angled
screw holes includes internal threads.
22. The system of claim 20, wherein at least one of the screws
includes external threading at least partially on its head.
23. The system of claim 20, wherein the height of the front plate
is substantially equal to the height of the front surface of the
three-dimensional body.
24. The system of claim 20, wherein the three dimensional body has
a horizontal middle plane between the upper surface and the lower
surface, and the front plate is coupleable to the three dimensional
body such that the axis of at least two angled screw holes define
an angle ranging from about 25.degree. to about 70.degree. with the
horizontal middle plane.
25. A spine stabilizing system for stabilizing first and second
vertebrae in a spinal column comprising: a plurality of bone screws
having a threaded shaft and a head, the shaft having a longitudinal
central axis; a three dimensional body configured for insertion
between endplates of the first and second vertebrae, the three
dimensional body having an upper surface for abutting the endplate
of a first vertebrae, a lower surface for abutting the endplate of
a second vertebrae, a left side surface and a right side surface, a
front surface and a back surface, the three dimensional body having
a horizontal central plane between the upper and lower surface, the
three-dimensional body having a plurality of boreholes for
receiving there through the screws, at least one borehole extending
from the front surface to the upper surface of the three
dimensional body and at least one borehole extending from the front
surface to the lower surface of the three dimensional body, each
borehole having a central axis wherein each central axis is at an
angle in the range of about 25.degree. to about 70.degree. relative
to the horizontal middle plane of the body.
26. The system of claim 25, wherein the plurality of bore holes are
aligned in the front surface in a horizontal line.
27. The system of claim 25, further comprising: a front plate
having a top surface, a bottom surface, a superior surface and an
inferior surface, the plate couplable to the three dimensional body
such that the bottom surface overlies the front surface, the plate
having a plurality of screw holes for receiving there through the
shaft of the screws, the screw holes having a central axis, at
least two of the plurality of screw holes extending through the
front plate so that the axis of the screw hole is at an angle that
is substantially equal to the angle of the boreholes in the
three-dimensional body, wherein the position and orientation of the
front plate is such that the at least two angled boreholes in the
three dimensional body are aligned with the at least two angled
screw holes in the front plate so that the screws are insertable in
the front plate so that its shaft extends out of respective upper
and lower surfaces of the three-dimensional body.
28. The system of claim 27, wherein when the plate is coupled to
the three-dimensional body, the three-dimensional body and at least
one of the screw holes in the front plate are configured and
oriented such that one of the screws inserted into the angled screw
hole pierces at least partially one of the upper or lower surfaces
of the three-dimensional body.
29. The system of claim 25, wherein the three dimensional body is
formed of a non-metallic material.
30. The system of claim 25, wherein the three dimensional body
includes at least one through hole extending from the upper surface
to the lower surface.
31. The system of claim 27, wherein at least one of the angled
screw holes formed in the front plate is conically shaped.
32. The system of claim 25, wherein one of the upper and lower
surfaces of the three-dimensional body is convex.
33. The system of claim 25, wherein at least one of the upper
surface and the lower surface includes one of the group of grooves,
ribs, teeth and roughened surface portion to improve anchoring of
the three-dimensional body with the vertebrae.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/574,222, filed Oct. 6, 2009, which is a
continuation of U.S. patent application Ser. No. 11/751,757, filed
May 22, 2007, now U.S. Pat. No. 7,618,456, which is a continuation
of U.S. patent application Ser. No. 10/923,534, filed Aug. 19,
2004, now U.S. Pat. No. 7,232,464, which is a continuation of
International Application No. PCT/CH02/00099, filed Feb. 19, 2002.
The entire contents of these applications are expressly
incorporated herein by reference thereto.
FIELD OF THE INVENTION
[0002] The present invention relates to an intervertebral
implant.
BACKGROUND OF THE INVENTION
[0003] Such an intervertebral implant is known from the British
patent document 2,207,607 A which discloses a horseshoe implant
structure having a plurality of cylindrical holes. These holes are
fitted with inner, smooth surfaces and comprise only one stop for
the heads of the bone screws to be inserted into them. This design
incurs the drawback that the inserted affixation screws may be
anchored into the bone only by their shanks, a rigid connection
with the horseshoe shaped intervertebral implant being lacking. As
soon as the anchoring of the bone screw in the bone is weakened,
the intervertebral implant becomes displaceable relative to the
screw and the bone screws may then migrate while endangering the
blood vessels. Moreover the loosening of the intervertebral implant
may entail pseudoarthrosis.
[0004] The above cited state of the art is intended merely to
elucidate the background of the present invention but it does imply
that the cited state of the art had actually been made public or
was publicly known at the time of this application or at the time
of its priority.
BRIEF SUMMARY OF THE INVENTION
[0005] The objective of the present invention is palliation. This
invention creates an intervertebral implant which is able to
rigidly connect to bone affixation means in a manner that even in
the event of bone structure weakening, loosening between the
intervertebral implant and the bone affixation means shall be
precluded.
[0006] The above problem is solved in the present invention by an
intervertebral implant exhibiting the features of claim 1.
[0007] The advantages offered by the present invention
substantially are attained by the rigid, that is by the firm
connection between the intervertebral implant and the longitudinal
affixing elements. Basically two different embodiment modes are
available to attain said rigid connection.
[0008] In a first embodiment mode, at least one of the boreholes
shall be internally threaded. In this case a matching bone screw
fitted with a thread head may be rigidly screwed into the
implant.
[0009] As regards a second embodiment mode, a front plate is
mounted at the front surface of the three dimensional (3D) implant
structure so as to be configured vertically to the horizontal
center plane of the intervertebral implant, said boreholes passing
through said front plate and receiving the anchored longitudinal
affixation elements. Compared to the state of the art of a two-part
implant, wherein a front plate is implanted in a separate
operational step, the above design of the present invention offers
the advantage that the intervertebral implant shall be implanted in
a single step and hence in a simple and quicker manner. The
invention offers a further advantage in that the intervertebral
implant shall be affixed as frontally to the vertebra as possible,
namely at a place where good bone material may be expected to be.
As a result anterior displacement is restricted without thereby
incurring greater danger to the surrounding structures than when
using a state of the art intervertebral implant. The load still is
being borne by the compressed vertebral implant, not by the front
plate or the affixation screws.
[0010] In yet another embodiment mode of the present invention, the
front plate is displaceably configured in the 3D implant structure
in order that it may move vertically relative to this 3D implant
structure. "Stress shielding" is attained in this manner (namely
protection from or neutralization of mechanical stresses), and as a
result the end plates may gradually match the intervertebral
implant during the healing process.
[0011] As regards a further embodiment, the front plate is made of
a material different from that of the 3D implant structure.
[0012] As regards a further embodiment of the present invention, at
least one borehole tapers conically towards its underside and as a
result a bone screw fitted with a matching conical head may be
rigidly anchored in said borehole. Preferably the conical borehole
exhibits a cone angle smaller than the resultant angle of friction.
Appropriately the borehole's conicity shall be 1:3.75 to 1:20,
preferably 1:5 to 1:15.
[0013] As regards a further embodiment mode of the present
invention, the intervertebral implant side faces shall all be
substantially convex.
[0014] Appropriately the intervertebral implant's top and/or
undersides are not planar but convex. In this manner better
matching to the end plates of the adjacent vertebras may be
attained.
[0015] The boreholes preferably shall not pass through the left and
right intervertebral implant side faces. Preferably again no
borehole shall run through the front surface.
[0016] As regards a further preferred embodiment mode of the
present invention, at least two boreholes shall be mutually
parallel. This features facilitates inserting the vertebral implant
during implantation.
[0017] As regards another preferred embodiment mode of the present
invention, at least two boreholes shall run in mutually divergent
manner as seen from the front side. As a result the bone screws
shall move into a vertebral region offering better bone quality
than found at the vertebra's center. Appropriately the borehole
axes subtend an angle of 25 degrees to 70 degrees, preferably 35
degrees to 55 degrees with the horizontal center plane. This
feature offers improved access for screw insertion.
[0018] As regards a further embodiment mode of the present
invention, the boreholes shall not cross the horizontal center
plane.
[0019] Depending on circumstance, two, three, four or even more
longitudinal affixation elements may rigidly connected to the
intervertebral implant; appropriately at least one affixation
element shall pass through the top side and at least one affixation
element shall pass through the intervertebral implant side.
[0020] Preferably the longitudinal affixation elements shall be
bone screws comprising a head and a shank, said head preferably
being fitted with an external thread that matches the inner thread
of the intervertebral implant's borehole. As regards a second
appropriate connection, preferably a bone screw shall be used of
which the head tapers conically in the direction of the shank, the
head's conicity corresponding to that of the intervertebral
implant's borehole.
[0021] Regarding a further embodiment mode, at least two
longitudinal affixation elements pass through the top side and at
least two longitudinal affixation elements pass through the
underside. In this manner the intervertebral implant is optimally
anchored into the adjacent vertebras.
[0022] Preferably the screw-shaped longitudinal affixation elements
exhibit a self-boring and self-tapping external thread. The
longitudinal affixation elements also may be designed as unthreaded
cylindrical pins fitted with a boring tip, preferably in the form
of a trocar.
[0023] In another embodiment variation, the longitudinal affixation
elements are spiral springs; lastly said longitudinal affixation
elements also may be designed as single or multi-wing spiral
blades.
[0024] In a further embodiment mode of the present invention, the
longitudinal affixation element tip may be anchored in the
structure of the intervertebral implant, as a result of which the
head of the longitudinal affixation element may be anchored in the
adjacent vertebra.
[0025] In a further embodiment mode of the present invention, the
longitudinal affixation element head exhibits a widened diameter;
also a support disk is provided for said head to rest against the
vertebra.
[0026] The intervertebral implant may be made of any
physiologically compatible material, though appropriately the
implant structure shall consist of a physiologically compatible
plastic, preferably an unreinforced plastic. The advantage offered
by the invention over the already known, fiber-reinforced plastics
used in implantology is that no reinforcing fibers will be
bared--an eventuality that would be clinically disadvantageous.
Appropriately bone screws consisting of non-reinforced plastic of
which the external threads exhibit load bevels of 11 degrees to 14
degrees, preferably 12 degrees to 13 degrees, may be used in such
an implant structure. The relatively small slope of the load bevel
implements high clamping forces, as a result of which radial
elongation and danger of cracking of the plastic are reduced.
Appropriately the bone screws' external thread exhibits the bones
at an angular pitch of 6 degrees to 10 degrees, preferably 7
degrees to 9 degrees. This particular angular pitch produces thread
self-locking and prevents the bone screw from loosening on its
own.
[0027] The borehole may be in the form of a metal bush fitted with
an inner thread for the purpose of improving anchoring the bone
screw in the plastic implant structure. The intervertebral implant
also may consist partly of plastic and, in the borehole zones, of
metal. This design offers improved guidance and anchoring of the
bone screw in the intervertebral implant.
[0028] As regards a further preferred embodiment mode, the inside
borehole walls are smooth, the thread head of a metallic,
longitudinal affixation element cutting or tapping into said smooth
wall.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0029] The present invention and further embodiment modes of it are
elucidated below in relation to the partly schematic representation
of two illustrative embodiments.
[0030] FIG. 1 is a perspective view including a partial section of
the intervertebral implant with inserted bone screws,
[0031] FIG. 2 is a front view of the intervertebral implant of FIG.
1,
[0032] FIG. 3 is a side view of the intervertebral implant of FIG.
1,
[0033] FIG. 4 is a top view of the intervertebral implant of FIG.
1,
[0034] FIG. 5 is a front view of the intervertebral implant with a
front insert, in partial section,
[0035] FIG. 6 is a vertical, longitudinal section of the
intervertebral implant of FIG. 5, and
[0036] FIG. 7 is a horizontal cross-section of the intervertebral
implant of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The intervertebral implant of FIGS. 1 through 4 consists of
a 3D structure 10 exhibiting both a convex top side 1 and a convex
underside 2, the two sides each being designed to rest against the
end plates of two adjacent vertebras. To attain improved anchoring,
the top side 1 and the underside 2 may be topographically shaped
and be fitted with grooves, ribs or teeth, or their surfaces may be
merely roughened.
[0038] The 3D implant structure 10 moreover comprises a left side
face 3 and a right side face 4, also a front face 5 and a rear face
6. The implant structure 10 also may be hollow and its outer
surface may comprise perforations.
[0039] The implant structure 10 comprises a plurality of boreholes
9 passing through it and receiving longitudinal affixation elements
20. Preferably four such boreholes 9 shall be provided.
[0040] At least one of the boreholes 9 is designed in a way that
the longitudinal affixation element 20 received therein may be
rigidly connected to the intervertebral implant. The boreholes 9
are conical for that purpose.
[0041] Preferably the affixation elements 20 are bone screws having
a head 21 and a tip 22. The head 21 conically tapers toward the
shank 23, the conicity of the head 21 corresponding to the conicity
of the borehole 9. Moreover the four boreholes 9 may be fitted with
inner threads 11.
[0042] As regards the embodiment variation shown in FIGS. 5 through
7, the 3D structure 10 is fitted at its front face 5 with a
preferably metallic insert 8 into which the affixation elements 20
may be anchored. The insert 8 is mounted in vertically displaceable
manner in the 3D structure 10.
[0043] While the invention has been shown and described herein with
reference to particular embodiments, it is to be understood that
the various additions, substitutions, or modifications of form,
structure, arrangement, proportions, materials, and components and
otherwise, used in the practice and which are particularly adapted
to specific environments and operative requirements, may be made to
the described embodiments without departing from the spirit and
scope of the present invention. Accordingly, it should be
understood that the embodiments disclosed herein are merely
illustrative of the principles of the invention. Various other
modifications may be made by those skilled in the art which will
embody the principles of the invention and fall within the spirit
and the scope thereof.
* * * * *