U.S. patent application number 12/976852 was filed with the patent office on 2011-04-21 for intervertebral implant with joint elements carried by universal joint.
Invention is credited to Max Aebi, Dominique Burkard, Robert Frigg, Beat Lechmann, Robert Mathys, JR., Paul Pavlov.
Application Number | 20110093077 12/976852 |
Document ID | / |
Family ID | 32514199 |
Filed Date | 2011-04-21 |
United States Patent
Application |
20110093077 |
Kind Code |
A1 |
Aebi; Max ; et al. |
April 21, 2011 |
INTERVERTEBRAL IMPLANT WITH JOINT ELEMENTS CARRIED BY UNIVERSAL
JOINT
Abstract
An intervertebral implant, specifically an artificial
intervertebral disk, with a central axis, an upper section,
suitable for laying onto the base plate of a vertebral body lying
on top and lower section, suitable for laying onto the cover plate
of a vertebral body lying below, wherein (A) the upper section is
provided with a ventral side area, a dorsal side area, two lateral
side areas, a top apposition surface and a bottom surface; (B) the
lower section is provided with a ventral side area, a dorsal side
area, two lateral side areas, a bottom apposition surface and a top
surface; (C) the two sections are moveable in relation to each
other by means of one joint arranged between the two sections,
wherein (D) the joint is a universal joint with two swivel axles
standing perpendicular to each other.
Inventors: |
Aebi; Max; (Bern, CH)
; Burkard; Dominique; (Gretzenbach, CH) ; Frigg;
Robert; (Bettlach, CH) ; Lechmann; Beat;
(Bettlach, CH) ; Mathys, JR.; Robert; (Bettlach,
CH) ; Pavlov; Paul; (Nijmegen, NL) |
Family ID: |
32514199 |
Appl. No.: |
12/976852 |
Filed: |
December 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10538542 |
Jun 8, 2007 |
7887591 |
|
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PCT/CH2002/000706 |
Dec 17, 2002 |
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12976852 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61F 2002/30362
20130101; A61F 2002/30515 20130101; A61F 2002/443 20130101; A61F
2002/30787 20130101; A61F 2002/3079 20130101; A61F 2220/0033
20130101; A61F 2/4455 20130101; A61F 2002/30785 20130101; A61F
2002/30632 20130101; A61F 2002/30604 20130101; A61B 17/863
20130101; A61F 2002/30774 20130101; A61F 2002/30635 20130101; A61F
2002/4635 20130101; A61F 2/4425 20130101; A61F 2002/30507 20130101;
A61F 2002/30528 20130101; A61F 2220/0025 20130101; A61F 2002/30843
20130101; A61F 2002/30517 20130101; A61F 2002/30492 20130101; A61F
2002/30634 20130101; A61F 2002/30387 20130101; A61B 17/86
20130101 |
Class at
Publication: |
623/17.16 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. An intervertebral implant system for stabilizing first and
second vertebrae in a spinal column comprising: a plurality of bone
fixation devices having a longitudinal central axis; and a three
dimensional body configured for insertion between endplates of the
first and second vertebrae and having a central axis, an upper
surface for contacting the first vertebrae, a lower surface for
contacting the second vertebrae, and ventral side areas, the three
dimensional body having a plurality of drill holes having
longitudinal axes, at least one drill hole extending from the
ventral side area and piercing the upper surface at a
non-orthogonal angle, at least one of the drill holes extending
from the ventral side area and piercing the lower surface at a
non-orthogonal angle, wherein the longitudinal axes of at least one
of the drill holes piercing the upper surface makes an angle
.gamma. with the central axis that lies in the range between 20
degrees and 65 degrees.
2. The intervertebral implant of claim 15 further comprising an
insert plate slideably attachable to the ventral side areas of the
three dimensional body.
3. The intervertebral implant of claim 2 wherein the height of the
insert plate is substantially equal to or less than the height of
the ventral side area where the insert plate is attachable to the
three-dimensional body.
4. The intervertebral implant of claim 1, wherein at least a
portion of the head of the bone screws has external threads and at
least a portion of at least one of the plurality of drill holes in
the three dimensional body have internal threads configured to mate
with the external threads of the head of the bone screw.
5. The intervertebral implant of claim 1 where in at least two of
the drill holes in the three dimensional body extend from the
ventral side area through the upper surface and at least two of the
drill holes in the three dimensional body extend from the ventral
side area through the lower surface.
6. The intervertebral implant of claim 1, wherein the axis of the
at least one drill hole that extends through the upper surface is
substantially perpendicular to the axis of the at least one drill
hole that extends through the lower surface.
7. The intervertebral implant of claim 2, wherein the insert plate
is insertable in a depression in the ventral side area of the three
dimensional body.
8. The intervertebral implant of claim 1, wherein the longitudinal
axes of at least one of the drill holes piercing the lower surface
makes an angle .gamma. with the central axis that lies in the range
between 20 degrees and 65 degrees.
9. The intervertebral implant of claim 1 wherein a plurality of the
drill holes have a conical shape.
10. The intervertebral implant of claim 1 further comprising a
joint which permits motion of the upper surface relative to the
lower surface.
11. The intervertebral implant of claim 10 having a first axle and
a second axle, the first axle arranged perpendicular to the second
axle.
12. The intervertebral implant of claim 11 wherein the movement of
the upper surface relative to the lower surface about the first
axle is limited within an angle of about 16 degrees.
13. The intervertebral implant of claim 12 wherein the movement of
the upper surface relative to the lower surface about the second
axle is limited within an angle of about 14 degrees.
14. The intervertebral implant of claim 2 wherein the insert plate
is configured to maintain the upper and lower surface at the front
side at a fixed distance from each other.
15. The intervertebral implant of claim 1 wherein the upper surface
and the lower surface have three-dimensional structures to assist
in engaging the vertebrae.
16. The intervertebral implant of claim 1 wherein the plurality of
bone fixation devices are bone screws having a threaded shaft and a
head, the shaft having a longitudinal central axis; and the
plurality of drill holes are configured to receive the bone
screws.
17. An intervertebral implant 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 and
having a central axis, an upper surface for contacting the first
vertebrae, a lower surface for contacting the second vertebrae, and
a ventral side area, the three dimensional body having a plurality
of drill holes having longitudinal axes, at least one drill hole
extending from the ventral side area and piercing the upper
surface, at least one of the drill holes extending from the ventral
side area and piercing the lower surface, wherein the longitudinal
axes of at least one of the drill holes piercing the upper surface
makes an angle .gamma. with the central axis that lies in the range
between 20 degrees and 65 degrees and the longitudinal axes of at
least one of the drill holes piercing the lower surface makes an
angle .gamma. with the central axis that lies in the range between
20 degrees and 65 degrees; and an insert plate slideably attachable
to the ventral side area of the three dimensional body, the height
of the insert plate being substantially equal to or less than the
height of the ventral side area where the insert plate is
attachable to the three-dimensional body.
18. The intervertebral implant of claim 17 where in at least two of
the drill holes in the three dimensional body extend from the
ventral side area through the upper surface and at least two of the
drill holes in the three dimensional body extend from the ventral
side area through the lower surface.
19. The intervertebral implant of claim 17, wherein the insert
plate is insertable in a depression in the ventral side area of the
three dimensional body.
20. The intervertebral implant of claim 17 wherein a plurality of
the drill holes have a conical shape.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/538,542, filed Jun. 8, 2007, entitled
"INTERVERTEBRAL IMPLANT WITH JOINT ELEMENTS CARRIED BY UNIVERSAL
JOINT" which claims the benefit of International Application No.
PCT/CH2002/000706, filed Dec. 17, 2002, the entire contents of
these applications is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to an intervertebral implant and to a
process for the replacement of a defect, natural intervertebral
disk by an intervertebral implant.
[0003] After removal of a damaged, natural intervertebral disk or a
damaged nucleus pulposus of an intervertebral disk, implants or
prostheses are inserted into the intervertebral space of two
neighbouring vertebral bodies. This suggests the idea of restoring
the situation as much as possible to a natural state, Le.
specifically to restore the original height of the intervertebral
disk and thus the original distance between the two neighbouring
vertebral bodies. Furthermore, the patient should be able to carry
out movements of the neighbouring vertebral bodies relative to each
other in the natural way, thereby incurring as little obstruction
as possible. This essential feature of this system is its ability
to retain the freedom of movement in forward/reverse inclination,
Le. flexion and extension of the vertebral bodies, and in lateral
bending of the vertebral bodies within the natural limits. The
natural sinews and muscles along the spinal column are in general
left intact so that they further stabilise the movements of a
mechanical intervertebral disk prosthesis.
[0004] A characteristic intervertebral disk endoprosthesis is state
of the art from DE-A 35 29 761 BUTTNER. This known intervertebral
disk endoprosthesis basically consists of two symmetric closing
plates with concave sliding surfaces facing each other, and each
having an external surface for laying on the base plate, or the
cover plate of the adjoining vertebral body, and a distance piece
positioned between the closing plates with convex sliding surfaces
arranged complementary to the concave sliding surfaces on the
closing plates. The sliding surfaces are designed in one embodiment
as section surfaces of a cylinder coat area, wherein the sliding
surfaces arranged on the two closing plates are provided
complementary to each of the adjoining sliding surfaces at the
distance piece, and two complementary sliding surfaces form the
articulation surfaces, which can be moved towards each other, of a
joint element rotating around a swivel axle. The joint comprises an
upper and a lower joint element, each of which has one swivel axle.
The two swivel axles are set at 90.degree. to each other. The
disadvantages of this known intervertebral disk endoprosthesis is
that
[0005] a) the arrangement of an intervertebral disk endoprosthesis
with only one fulcrum does not take sufficient account of the
overlaying swivel movements transferred by the natural
intervertebral disk, specifically in the case of anterior-posterior
and in lateral flexion, which in the natural intervertebral disk
are independent of each other;
[0006] b) the verterbral joint is put under strain by swivel
movements, specifically with translation in the anterior-posterior
direction (face joint), which could cause pain for the patient;
[0007] c) disadvantageous friction forces are generated by two
articulating surfaces sliding on each other. This also leads to
wear on the surfaces, including also abrasion and resistance in
movement of the joint elements. There is also the risk of the
"stick slip" effect;
[0008] d) a mechanical intervertebral disk prosthesis can scarcely
prevent the further degeneration of the affected movement segments.
Restoration of the original freedom of movement significantly
reduces pain, with the resulting improvement to the patient's
quality of life. A review of treatment will, however, have to be
undertaken if pain recommences. This will normally involve complete
removal of an intervertebral disk prosthesis of the standard model
and a stiffening of the movement segment. This operation represents
extreme discomfort and strain on the patient; and
[0009] e) the form of contact areas to the neighbouring vertebral
bodies is generally not taken into account. The conventional types
of intervertebral disk prosthesis implants have flat contact areas,
which are often supplemented with keel-type elevations.
BRIEF SUMMARY OF THE INVENTION
[0010] The invention is intended to remedy this situation. The
invention is based on the task of creating an intervertebral
implant that is provided with joints having with minimum friction
surfaces.
[0011] The invention solves the task with an intervertebral implant
and with a process for replacing a defect, natural intervertebral
disk by an intervertebral implant.
[0012] The advantages achieved by the invention can generally be
seen in that with the intervertebral implant according to the
invention [0013] the swivel movements in anterior-posterior and
lateral direction are independent of each other; [0014] no
translation movements of the vertebral bodies adjoining the implant
are permitted, which relieves strain on the face joints; and [0015]
the friction surfaces of the moved elements are restricted to small
cylindrical or polygon-shaped rotation bodies and are thus kept at
a minimum.
[0016] In a preferred embodiment of the intervertebral implant
according to the invention, the two joints comprise three joint
sections, wherein the central joint section is arranged as a frame
and this frame is connected on the one hand to the lower joint
section by means of two axles arranged coaxial to the first swivel
axle in a way that allows rotation around the first swivel axle,
and on the other hand connected to the upper joint section by means
of a further axle arranged coaxial to the second swivel axle in a
way that allows rotation around the second swivel axle. The swivel
axles can thereby be arranged in a warped manner or in a plane or
intersecting.
[0017] In a further embodiment of the intervertebral implant
according to the invention, the central joint section is arranged
as a cross.
[0018] In a further embodiment of the intervertebral implant
according to the invention the central joint section is arranged as
an angle. This means that only one axle coaxial to the relevant
swivel axle is necessary for each joint, by means of which the
advantage is achieved that the two joints are realized by fewer
components.
[0019] In a further embodiment of the intervertebral implant
according to the invention, a means can be attached to the two
sections from the ventral side areas which holds the two sections
ventral at a fixed distance relative to each other. This measure
provides the advantage that the two sections for insertion into the
intervertebral space can be brought to a position with fixed height
and can be moved around the joint after insertion into the
intervertebral space and can be placed on the base or cover plate
of the adjoining vertebral body.
[0020] In a further embodiment of the intervertebral implant
according to the invention, the means allows temporary blocking of
the mobility of the two sections around the joint. This measure
provides the advantage that the joint integrated in the
intervertebral space can be blocked by a minimum invasive
operation. This is particularly advantageous in cases where the
patient suffers from post-operative pain, i.e. where degeneration
of the affected spinal column segment continues and the surgeon is
considering a fusion of the affected vertebra. The means can
preferably be attached to the two ventral side areas of the two
sections. With this subsequent, secondary blocking of the mobility
of the two sections around the joint, the intervertebral implant is
stiffened and transferred to an arthrodesis implant (fusion
cage).
[0021] In a further embodiment of the intervertebral implant
according to the invention, the means for blocking the joint
comprises two insert pieces. The two insert pieces can be fixed by
means of screws on the lower joint sections parallel to the second
swivel axle. If the insert pieces are being used, the upper section
and the lower section will lean against each other so that there
can be no swivel movement of one of the sections in relation to the
other around the two swivel axles.
[0022] In a further embodiment of the intervertebral implant
according to the invention, the means comprises an insert, which
can be placed into each depression on the surfaces of the upper and
lower section opposite each other. These depressions are preferably
provided as dovetail guides that are open on the ventral side
areas, so that the ends of the insert arranged complementary to the
dovetail guides can be inserted from ventral into the dovetail
guides. This provides the advantage that the mobility of the two
sections around the joint is blocked due to the positioning of the
insert. The rigidity of the blocking can be increased when the
dovetail guides are designed so that they are reduced is size
towards the central axis of the intervertebral implant, which
creates additional wedging of the insert in the dovetail
guides.
[0023] In a further embodiment of the intervertebral implant
according to the invention, the means comprise two parallel inserts
that can be slid parallel to the lateral side surfaces between the
two sections and come to rest on the surfaces of the two sections
that face each other. Both inserts can be fixed at the lower
section of each by means of a screw.
[0024] In a further embodiment of the intervertebral implant
according to the invention, the two sections are provided with
drill holes for receiving the bone fixation means, specifically
bone screws, wherein the drill holes are provided with longitudinal
axes that stand perpendicular to the central axis. Preferably two
drill holes will pass through one of the two sections from the
ventral side area to the apposition surface. The longitudinal axes,
if only an axial fixing of the intervertebral implant is provided,
will then be able to stand only perpendicular to the central axis
from a lateral perspective, or, if fixing of the intervertebral
implant with stable angle is provided, will also from a lateral
perspective diverge from the inner surfaces of the two sections
against the apposition surfaces.
[0025] In a further embodiment of the intervertebral implant
according to the invention, the drill holes for receiving the bone
fixation means are provided with internal threads, which allows
additional, rigid fixing of the bone fixation means in the two
sections. The drill holes preferably have a conical shape so that a
stronger fixing of the bone fixation means to each of the two
sections can be achieved by the resulting conical thread
connections between the internal threads and the external threads
on the heads of the bone fixation means.
[0026] The process according to the invention is intended primarily
for replacing a defect, natural intervertebral disk by an
intervertebral implant and comprises the following steps: [0027] A)
blocking of the joint(s) of an intervertebral implant by means of a
special device placed in a certain position of the joint(s); [0028]
B) insertion of the intervertebral implant into the intervertebral
space to be treated; [0029] C) release and removal of the device
inserted into the intervertebral implant for blocking the joint(s).
Blocking the joint provides the advantage that the moveable
sections with the external apposition surfaces can be inserted more
easily into the intervertebral space to be treated.
[0030] In a further application of the process according to the
invention, this comprises the subsequent blocking of the joint(s)
on the implanted intervertebral implant by means of the device
intended for blocking the joint(s). This provides the advantage
that if the patient should suffer from post-operative pains or in
case of a further degeneration of the movement segment, the
joint(s) on the intervertebral implant are blocked postoperative by
the insertion of the means intended for this purpose. This
subsequent blocking can be achieved with an minimally invasive,
preferably a laparoscopic operation. The intervertebral implant
then assumes the function of a cage, so that the affected movement
segment of the spinal column can be stiffened.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The invention and refinements of the invention are described
in more detail below on the basis of a partially schematic
illustration of one embodiment.
[0032] FIG. 1 shows an explosion diagram of one embodiment of the
intervertebral implant according to the invention;
[0033] FIG. 2 shows a perspective view of the embodiment of the
intervertebral implant according to the invention shown in FIG. 1
in assembled state;
[0034] FIG. 3 shows a lateral view of a further embodiment of the
intervertebral implant according to the invention; and
[0035] FIG. 4 shows a perspective view of the embodiment according
to FIG. 3 from the ventral side.
DETAILED DESCRIPTION OF THE INVENTION
[0036] An embodiment of the intervertebral implant according to the
invention 1 is illustrated in FIG. 1 and comprises an upper section
10 with an upper apposition surface 15 arranged perpendicular to
the central axle 2 for laying onto the base plate of a neighbouring
vertebral body, a lower section 20 with a lower apposition surface
25 arranged perpendicular to the central axle 2 for laying onto the
cover plate of the neighbouring vertebral body and a joint 30. The
upper section 10 and the lower section 20 are linked in a way that
allows movement in relation to each other by means of the joint 30,
wherein the mobility of the upper section 10 relative to the lower
section 20 around a first swivel axle 3 arranged perpendicular to
the central axle 2 is limited within an angle range of between
+10.degree. and -60 and around a second swivel axle 4 arranged
perpendicular to the central axle 2 and vertical to the first
swivel axle 3 is limited within an angle range of
.+-.7.degree..
[0037] The joint 30 is arranged as a universal joint and comprises
a central joint section 32 arranged as a frame, which central joint
section 32 has a central joint section 32 with two axles 62
arranged coaxial to the first swivel axle 3, which in two
complementary drill holes 65 on the lower joint sections 33 are
carried in a way permitting rotation around the first swivel axle
3. A further axle 61 arranged coaxial to the second swivel axle 4
is attached to the central joint section 32 and placed in a
complementary drill hole (not shown in the illustration) at the
upper joint section 31 rotating around the second swivel axle 4.
The axles 61,62 can be provided with a circular or polygon-type
cross-section surface in the cross-section from a perspective
orthogonal to the swivel axle 3,4. The joint 30 in the embodiment
illustrated here is blocked by means 40, which comprises two insert
pieces 63 that are fixed parallel to the second swivel axle 4 on
the lower joint sections 33 by means of screws 64. If insert pieces
63 have been applied, the upper section 10 and the lower section 20
will be supported against each other so that neither a swivel
movement of one of the sections 10,20 relative to the other around
the first swivel axle 3, nor a swivel movement of one of the
sections 10,20 relative to the other around the second swivel axle
4 will be possible.
[0038] The two sections 10,20 and the central joint section 32 are
held together by the axles 61,62 fixed in the central joint section
32, which axles are carried in a way allowing rotation in the drill
holes 65 in the lower joint section 33 and a drill hole (not
illustrated) in the upper joint section 31 around the swivel axles
3,4.
[0039] The embodiment of the intervertebral implant according to
the invention illustrated in FIG. 2 differs from the embodiment
illustrated in FIG. 1 only in that the means 40 is designed
differently. The means 40 comprises in the embodiment described
here an insert 41 that can be slid in from the ventral side areas
11,21 of the two sections 10,20 perpendicular to the central axis 2
and parallel to the lateral side areas 13,14,23,24 of the two
sections 10,20. The insert 41 is slid in two depressions 42,43,
provided in the form of dovetail guides. The insert 41 is inserted
from the ventral side areas 11,21 of the two sections 10,20 into
the depressions 42,43 composed as dovetail guides and fitted to the
lower section 20 by means of a screw 44. The insert 41 is
furthermore arranged in the terminal state complementary to the
depressions 42,43, so that the two sections 10,20 with fitted
insert 41 are fixed relative to each other parallel to the central
axis 2.
[0040] FIG. 3 illustrates an embodiment of the intervertebral
implant 1 according to the invention, which differs from the
embodiment illustrated in FIG. 1 and FIG. 2 only in that the two
sections 10,20 also comprise drill holes 80 for receiving the bone
fixation means 81, whereby the bone fixation means 80 is provided
in this case as bone screws. The drill holes 80 are provided with
longitudinal axes 83 that form an angle .gamma. with the central
axis 2. In addition, each two drill holes 80 (FIG. 4) run trough
one of the two sections 10,20 from the ventral side area 11,21 to
the apposition surface 15,25. The longitudinal axes 83 of the drill
holes 80 are standing perpendicular to the central axis 2 both from
a lateral perspective (FIG. 3) and from a ventral perspective (FIG.
4). The drill holes 80 are furthermore provided in conical design
and tapering towards the apposition surfaces 15,25 and provided
with internal threads 82 that are used for screwing reception of
the screw heads 84 of the bone fixation device 81 realized here in
the form of bone screws and provided with complementary external
threads.
* * * * *