U.S. patent application number 12/248320 was filed with the patent office on 2009-01-29 for veretebra stabilizing assembly.
Invention is credited to Jean Taylor.
Application Number | 20090030523 12/248320 |
Document ID | / |
Family ID | 8866385 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090030523 |
Kind Code |
A1 |
Taylor; Jean |
January 29, 2009 |
Veretebra Stabilizing Assembly
Abstract
An implant assembly for implantation between upper and lower
spinous processes includes an interspinous implant and a removable
clip. The implant may have an interspinous portion having upper and
lower surfaces for engagement with the respective upper and lower
spinous process, and a thickness therebetween sufficient to restore
anatomical tension to the supra-spinous posterior ligament. Upper
and lower pairs of lugs extend from the interspinous portion for
interfacing with the respective spinous processes. One or more of
the lugs of each pair is movable between an insertion configuration
and a retention configuration substantially perpendicular to the
retention configuration. The removable clip engages the relevant
lugs to selectively retain the same in the insertion
configuration.
Inventors: |
Taylor; Jean; (Cannes,
FR) |
Correspondence
Address: |
COATS & BENNETT/MEDTRONIC
1400 CRESCENT GREEN, SUITE 300
CARY
NC
27518
US
|
Family ID: |
8866385 |
Appl. No.: |
12/248320 |
Filed: |
October 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10486046 |
Jul 2, 2004 |
7445637 |
|
|
12248320 |
|
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Current U.S.
Class: |
623/17.16 ;
623/17.11 |
Current CPC
Class: |
A61F 2002/30131
20130101; A61F 2002/4635 20130101; A61F 2002/4627 20130101; A61F
2/441 20130101; A61F 2230/0045 20130101; A61F 2230/0015 20130101;
A61F 2230/0028 20130101; A61B 17/7062 20130101; A61F 2230/0013
20130101; A61F 2002/30197 20130101; A61F 2002/30133 20130101; A61F
2002/30563 20130101; A61F 2/4611 20130101; A61F 2002/30166
20130101; A61F 2/442 20130101 |
Class at
Publication: |
623/17.16 ;
623/17.11 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2001 |
FR |
FR0110604 |
Aug 8, 2002 |
FR |
PCT/FR02/02834 |
Claims
1. An implant assembly for implantation between upper and lower
spinous processes, the spinous processes having a supra-spinous
posterior ligament extending therebetween; the implant assembly
comprising: an interspinous implant comprising: an interspinous
portion having an upper surface for engagement with the upper
spinous process and a lower surface for engagement with the lower
spinous process; the interspinous portion having a thickness
between the upper surface and the lower surface sufficient to
restore anatomical tension to the supra-spinous posterior ligament;
an upper pair of lugs extending from the interspinous portion for
interfacing with the upper spinous process; a lower pair of lugs
extending from the interspinous portion in a direction
substantially opposite from the upper pair of lugs, the lower pair
of lugs for interfacing with the lower spinous process; wherein at
least one of the upper pair of lugs and at least one of the lower
pair of lugs is movable between an insertion configuration and an
retention configuration; wherein the insertion configuration for
the at least one of the upper and lower lugs is substantially
perpendicular to the retention configuration; a removable clip for
engagement with the at least one of the upper pair of lugs and at
least one of the lower pair of lugs to selectively retain the same
in the insertion configuration.
2. The implant assembly of claim 1 wherein the interspinous implant
comprises a flexible, resilient material to allow motion between
the spinous processes and to allow the at least one of the upper
and lower lugs to resiliently return to the retention configuration
from the implantation configuration.
3. The implant assembly of claim 2 wherein the implant comprises a
casing substantially surrounding the flexible, resilient
material.
4. The implant assembly of claim 3 wherein the casing is a woven
casing.
5. The implant assembly of claim 1 wherein the at least one of the
upper pair of lugs and at least one of the lower pair of lugs are
resiliently biased toward their retention configuration.
6. An interspinous implant for implantation between adjacent
spinous processes, the implant comprising: a central spacer portion
having first and second generally opposite lateral sides and a
longitudinal axis extending therebetween; a first flange connected
to said spacer portion and disposed transverse thereto on the first
lateral side thereof; a second flange connected to said spacer
portion and disposed on the second lateral side thereof; the second
flange having a proximal portion nearer the spacer portion and a
distal portion farther from the spacer portion; a third flange
connected to said spacer portion and disposed on the second lateral
side thereof; the third flange having a proximal portion nearer the
spacer portion and a distal portion farther from the spacer
portion; the second and third flanges changeable from a first
configuration to a second configuration; wherein, in the first
configuration: the distal portions are disposed relatively farther
apart and; the first and second flanges and the spacer section form
a first saddle for receiving a spinous process; the first and third
flanges and the spacer section form a second saddle for receiving a
spinous process; wherein, in the second configuration, the distal
portions are disposed relatively closer together; a retainer
selectively engageable with the distal portions to retain the
second and third flanges in the second configuration.
7. The implant of claim 6 wherein the second and third flanges are
biased toward their first configuration.
8. The implant of claim 6 wherein the first saddle is adapted to
receive one of the adjacent spinous processes when the implant is
disposed between the adjacent spinous processes with the
longitudinal axis of the spacer extending through a sagittal plane
defined by the adjacent spinous processes.
9. The implant of claim 6 wherein the first flange comprises a
first section and a second section; the first section corresponding
to the first saddle and the second section corresponding to the
second saddle.
10. The implant of claim 6 wherein said first, second, and third
flanges, and the spacer portion, are flexible.
11. The implant of claim 6 wherein the retainer comprises a
clip.
12. The implant of claim 6 wherein the spacer portion has a
cross-section perpendicular to the longitudinal axis; wherein the
second and third flanges, in the second configuration, fit within
that cross-section when viewed along the longitudinal axis.
13. The implant assembly of claim 6 wherein the second and third
flanges are deflectable between their first and second
configurations.
14. The implant assembly of claim 6 wherein said second and third
flanges, in their second configurations, are spaced from each
other.
15. An interspinous implant comprising: a central spacer portion
having first and second generally opposite lateral sides and a
longitudinal axis extending therebetween; a first flange connected
to said spacer portion and disposed transverse thereto on the first
lateral side thereof; a second flange connected to said spacer
portion and disposed on the second lateral side thereof; the second
flange comprising a first section and a second section; said first
and second sections movable relative to the spacer portion between
second more transverse positions and first more parallel positions
relative to the spacer portion's longitudinal axis; a retainer
selectively engageable with the first and second sections to retain
the first and second sections in the first position; wherein, in
the second positions, the first and second sections of the second
flange form first and second saddles, respectively, with the spacer
section and the first flange; the saddles adapted to receive
respective adjacent spinous processes when the implant is disposed
between the adjacent spinous processes with the longitudinal axis
of the spacer extending through a sagittal plane defined by the
adjacent spinous processes; wherein the first and second sections
of the second flange have a combined height perpendicular to the
longitudinal axis in the first positions that is less than in the
second positions.
16. The implant of claim 15 wherein the first position is generally
parallel to the longitudinal axis.
17. The implant of claim 15 wherein the retainer comprises a
C-shaped clip.
Description
[0001] This application is a continuation of prior U.S. patent
application Ser. No. 10/486,046, filed 2 Jul. 2004, which claims
the benefit of PCT/FR02/02834, filed 8 Aug. 2002, which claims
benefit of French application FR 01.10604, filed 8 Aug. 2001. The
above referenced applications are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an assembly for stabilizing
vertebrae, in particular lumbar vertebrae. This assembly can be
defined as a relief prosthesis having a dual effect, as will be
appreciated below.
[0003] It is known that the mobility of two adjacent vertebrae, in
particular in the lumbar region, is dependent on the intervertebral
disc at the anterior side and pairs of articular surfaces at the
posterior side.
[0004] The arrangement of the disc and articular surfaces ensures
auto-limitation of movements both in the plane perpendicular to the
vertebral column, during torsion, and in a sagittal plane, during
flexions and extensions of the vertebral column.
[0005] The shape, the structure and the height of the disc confer
on it additional functions of maintaining lordosis, absorbing
shocks and distributing stresses. At the rear, the articular
surfaces guide the movements and act as hinges.
[0006] The ageing process of the subject leads to disturbances in
this anterior/posterior equilibrium involving the discs and the
surfaces. Generally, the degeneration of the discs precedes that of
the surfaces. Collapse and instability of the discs leads to a
partial transfer of the stresses to the posterior columns which are
formed by the surfaces, which brings about a loss in the surface
congruence and a slackening of the ligaments. This results in
deterioration of the articular surfaces, which leads to various
pathologies having implications of a mechanical and neurological
nature.
[0007] In order to treat these pathologies, an anterior arthrodesis
has been proposed, by insertion of a graft between the plates of
the two vertebrae in question. This graft is usually contained in a
rigid cage, known as a "fusion cage".
[0008] However, this technique does not prevent rotational
instability which can compromise, in the medium term, the
anticipated antalgic result, and it has now been established that
the anterior arthrodesis must be complemented by a posterior
arthrodesis.
[0009] An intervention of this type has limits and disadvantages.
It is aimed at severe pathologies which are at an advanced stage
and is not without risks, given that the patients are often treated
at a relatively late stage in the pathological development.
Intervention can further have consequences which are detrimental to
adjacent articulations in the medium-term and long-term.
[0010] For these reasons, techniques known as "non-fusion"
techniques have been developed and relate to the early and
palliative treatment of degenerative disc/surface phenomena.
[0011] With regard to the disc space, there have been developed
various shock-absorbent implants, which are intended to replace the
nucleus pulposus, in the form of pairs of pads or elliptical or
spiral elements.
[0012] These implants are introduced either via an anterior access
point, which has the disadvantage of damaging the anterior common
vertebral ligament, or via a posterior access point, which has the
disadvantage of leading to the sacrifice of a large amount of bone,
owing to the space requirement of the implants.
[0013] Techniques involving percutaneous injection of a colloid
which can be polymerised in situ have also been proposed, as have
techniques using solid, disc-like prostheses in the form of two
metal plates which enclose a shock-absorbent material and which
rest on each of the vertebral plates which are adjacent to the
disc.
[0014] These techniques are not completely satisfactory as regards
the treatment of disc degeneration combined with wear of the
surfaces and/or ligament distension.
[0015] Devices intended to limit the articular play of the surfaces
have also been proposed. A device of this type comprises in
particular a continuous woven ligament which is positioned between
the spinous processes or along the articular surfaces by means of
pedicle screws, and/or a shock-absorbent dividing element which is
positioned at the lamina/spinous process junction so as to
alleviate the surface play while at the same time stretching the
posterior capsule/ligament elements.
[0016] It has been found that these techniques are also not
completely satisfactory with regard to the above-mentioned
treatment.
[0017] The object of the present invention is to overcome this
fundamental disadvantage by providing an assembly for stabilizing
two adjacent vertebrae which sustain both disc degeneration with
ligament distension, as well as possibly wear of the surfaces, this
assembly further having to be relatively simple to implant and, in
addition, relatively non-invasive.
SUMMARY OF THE INVENTION
[0018] In one embodiment, the present invention provides an implant
assembly for implantation between upper and lower spinous processes
that advantageously restores the anatomical tension to a
supra-spinous posterior ligament extending between the spinous
processes. The implant assembly comprises an interspinous implant
and a removable clip. The interspinous implant comprises an
interspinous portion having an upper surface for engagement with
the upper spinous process and a lower surface for engagement with
the lower spinous process. The interspinous portion has a thickness
between the upper surface and the lower surface sufficient to
restore anatomical tension to the supra-spinous posterior ligament.
The implant also comprises an upper pair of lugs extending from the
interspinous portion for interfacing with the upper spinous process
and a lower pair of lugs extending from the interspinous portion in
a direction substantially opposite from the upper pair of lugs, the
lower pair of lugs for interfacing with the lower spinous process.
At least one of the upper pair of lugs and at least one of the
lower pair of lugs is movable between an insertion configuration
and an retention configuration. The insertion configuration is
substantially perpendicular to the retention configuration. The
removable clip is for engagement with the relevant lugs to
selectively retain the same in the insertion configuration. The
implant may comprise a flexible, resilient material to allow motion
between the spinous processes and to allow the at least one of the
upper and lower lugs to resiliently return to the retention
configuration from the implantation configuration. The implant may
comprise a casing substantially surrounding the flexible, resilient
material, which may advantageously be a woven casing. The relevant
lugs are advantageously resiliently biased toward their retention
configuration.
[0019] In another embodiment, the invention provides an implant
assembly for implantation between first and second adjacent spinous
processes. The assembly comprises an interspinous implant and a
clip. The interspinous implant comprises a central body having
first and second lateral portions. First and second arms extend
from the first lateral portion and third and fourth arms flexibly
extend from the second lateral portion. The third arm is moveable
relative to the central body between a first position and a second
position, and the fourth arm is moveable relative to the central
body between a first position and a second position. The third and
fourth arms include respective base portions proximate the central
body and end portions distal therefrom; wherein the end portions of
the third and fourth arms are closer together when the third and
fourth arms are in their first positions than in their second
positions. The first arm, central body, and third arm form a first
saddle for receiving the first spinous process with the third arm
in the second position. Likewise, the second arm, central body, and
fourth arm form a second saddle for receiving the second spinous
process with the fourth arm in the second position. The clip is a
retaining clip removably coupled to the implant so as to
selectively retain the third and fourth arms in their first
positions. The third and fourth arms are advantageously biased
toward their second positions. With reference to an axis of the
central body, the third and fourth arms, in their first positions,
fit within the vertical cross-sectional area of the central body
projected onto a plane normal to the axis; but extend outside the
vertical cross-sectional area of the central body when in their
second positions.
[0020] Other features and aspects of the inventions(s) are
disclosed below. These features and aspects may be used alone or in
combination, as is desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a side view of two pathological vertebrae which
are to be treated by this assembly.
[0022] FIG. 2 is a perspective view of a posterior implant, which
this assembly comprises, according to one embodiment.
[0023] FIG. 3 is a perspective view of an inter-corporeal implant,
which this assembly can comprise, according to one embodiment.
[0024] FIGS. 4 and 5 are top views of this inter-corporeal implant,
during the introduction thereof between the vertebral bodies, by
means of an instrument provided to this end, and after being
positioned between these vertebral bodies, respectively.
[0025] FIG. 6 is a side view of the two vertebrae after the two
implants have been positioned.
[0026] FIG. 7 is a view similar to FIG. 5 of an inter-corporeal
implant according to another embodiment.
[0027] FIG. 8 is a sectioned view of an inter-corporeal implant
according to yet another embodiment.
[0028] FIG. 9 is a view of a posterior implant, which this assembly
comprises, according to another embodiment, and of two vertebrae,
on which this implant is to be positioned.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] In some embodiments, the assembly comprises a posterior
implant and at least one inter-corporeal implant. The
shock-absorbent posterior implant is formed to be positioned, via
the lateral route, at the lamina/spinous process junction of the
two adjacent vertebrae being treated, without resection of the
supra-spinous posterior ligament. This posterior implant
advantageously has a height such that, when it is positioned, it
allows the supra-spinous posterior ligament to be reset at
anatomical tension. The shock-absorbent inter-corporeal implant is
formed to be inserted between the adjacent vertebral plates of the
two vertebrae being treated via the same posterior/lateral route as
that used during a dissectomy. This implant advantageously has a
height such that, when it is positioned, it allows the anatomical
height of the intervertebral disc to be restored and the anterior
common ligament to be reset at anatomical tension. In this manner,
the assembly not only allows the anatomical spacing of the
vertebrae, both between the surfaces and between the vertebral
plates, to be re-established, but also allows the anterior common
ligament and the supra-spinous posterior ligament to be reset at
anatomical tension while preserving the same. The effect of this
tensioning is to restore the anatomical ligament "balance" which
exists between these ligaments, while at the same time giving back
to the disc and the surfaces the anatomical functions thereof such
as absorbing shocks with regard to the disc and acting as hinges
and of posterior balancing with regard to the surfaces.
[0030] The posterior implant is positioned directly behind the
surfaces at the site of the inter-spinous ligament complex, and can
be stressed in terms of both compression and extension. The
inter-corporeal implant is itself positioned, preferably as far
forwards as possible, along the circumference of the vertebral
plates. In this manner, it is positioned where the stresses are at
a maximum. The maximum spacing thereof from the posterior implant
allows the anterior/posterior ligament balance to be optimally
re-established.
[0031] Therefore, the posterior implant and the inter-corporeal
implant have the function of absorbing the stresses, in terms of
both compression and extension, which are generated during flexion
movements of the vertebral column forwards and backwards. When the
vertebral column flexes forwards, the supra-spinous posterior
ligament, which is reset at functional tension by the posterior
implant, ensures the anatomical function thereof of limiting the
movement, which function is optimized and reinforced owing to the
relief and the control brought about by the posterior implant,
owing to the progressive extension which limits it. At the same
time, the inter-corporeal implant provides relief to the defective
disc by absorbing the stresses applied in terms of pressure by the
superior vertebral body to the lower vertebral body and attenuates
the so-called "creep" phenomenon, that is to say, the depression of
the disc under the application of pressure. This inter-corporeal
implant jointly provides limiting relief which limits the effect of
extension which is undergone by the posterior flexible structures.
When the vertebral column flexes backwards, the anterior vertebral
ligament, which is reset at functional tension by the
inter-corporeal implant, ensures the anatomical function thereof of
progressively limiting the movement, which function is assisted and
reinforced by the extended shock-absorbent implant. At the same
time, the posterior implant is compressed and optimizes the play of
the surfaces in terms of the function thereof as hinges and of
posterior balancing.
[0032] The action of each implant is consequently advantageously
combined with the action of the other implant. Extension of one of
the implants is met with compression of the other implant, owing to
an interdependent auto-limiting effect.
[0033] The use of a single access route further allows the
intervention to be greatly simplified and the assembly according to
the invention to be made extremely non-invasive.
[0034] Securing means are advantageously provided in order to
ensure the continuity of the posterior implant in position,
relative to the spinous processes. These securing means can
comprise a suitable form of the posterior implant, defining opposed
recesses for receiving the spinous processes and conferring on the
posterior implant a "diabolo" or "H"-like shape, and/or means for
fixing the posterior implant to the spinous processes, such as two
independent cords or rigid anchoring pieces, which do not limit the
deformability of the implant.
[0035] The posterior implant can be constituted as a single piece
or can be in two parts which can be assembled and which are each
brought via one side of the inter-spinous space and are assembled
together in this space. When the posterior implant is of a
"diabolo" or "H"-like shape and when it is in a single piece, the
assembly can comprise a piece which keeps this implant in a
deformed state, in which two lateral lugs, which the implant
comprises, are brought closer towards each other, in order to allow
lateral insertion of the implant between the spinous processes of
the vertebrae being treated.
[0036] The inter-corporeal implant may be formed so as to extend in
the anterior lateral zones of the vertebral plates in order to
reinforce the lateral stability of the vertebrae and to allow
relief of the peripheral annulus fibrosus. It can then have, in
particular, a curved shape, in the form of a portion of a ring.
[0037] The assembly according to the invention may also comprise an
inter-corporeal implant which is provided to replace and/or assist
the nucleus. This implant can then be of a general "bean" or
"omega"-like shape, with a central portion which is extended by two
lateral lobes protruding at the posterior side. It can also be in
the form of a sphere.
[0038] The inter-corporeal implant(s) may have a triangular or
trapezoidal cross-section and is intended to be implanted with the
largest lateral side thereof directed towards the anterior side.
This implant, formed in this manner, corresponds to the anatomical
inclination of the disc.
[0039] The inter-corporeal implant(s) can comprise means for
ensuring the securing thereof between the vertebral plates. In
particular, these means comprise a form of the inter-corporeal
implant, which form is adapted to the shape of the vertebral plates
and which can secure this inter-corporeal implant between these
plates. When the inter-corporeal implant is in the form of a
sphere, it can comprise an equatorial lip which reduces the risk of
displacement thereof.
[0040] The posterior implant can comprise a core of shock-absorbent
material, such as a silicone, a polyurethane, a hydrophilic
polymer, a polycarbonate, or a piece of shape-memory metal, and a
casing which surrounds the core. This casing allows the core or the
piece to be advantageously protected from friction. The casing can
be formed from woven fibers. The inter-corporeal implant can have
an identical structure.
[0041] The positioning of this inter-corporeal implant can be
carried out, in particular, by means of an introduction guide tube
which is provided with a piston, the implant being engaged, with
compression, in the introduction tube and being able to be expelled
therefrom by means of the piston.
[0042] The introduction tube temporarily compresses the implant.
This reduction in volume, that is to say, in the space requirement
of the implant, makes only surgical access similar to that of a
dissectomy necessary, avoiding any destabilizing sacrifice of bone.
The tube is introduced into the disc space via the transligamentary
posterior/lateral route (LVCP). A semi-rigid guide directs and
controls the correct positioning of the inter-corporeal implant
before being withdrawn by being passed back through the
introduction guide tube.
[0043] With reference to the non-limiting illustrated embodiments,
FIG. 1 shows two vertebrae 2, 3, the intervertebral disc 4 of which
has collapsed. This collapse leads to a distension of the
supra-spinous posterior ligament 5 and the anterior common ligament
6, excessive stresses on the surfaces 8 in terms of pressure, which
can produce lesions thereto, and a risk of contact of the vertebral
bodies 7, 9 against each other at the anterior side. In order to
treat this pathology, an assembly of two implants 10, 11 acting
jointly may be used. For example, a posterior implant 10, which can
be seen in FIG. 2, and an inter-corporeal implant 11, which can be
seen in FIG. 3, may be used.
[0044] The posterior implant 10 is formed by a core of silicone
which is surrounded by a woven casing, in particular of polyester
fibers, which ensures the protection of this core. It has an
inter-spinous portion 15 and two pairs of lateral lugs 16 which
protrude longitudinally at one side and the other of this portion
15.
[0045] The portion 15 has a thickness slightly greater than the
anatomical inter-spinous space when the vertebrae 2, 3 are in
lordosis, so that the portion 15 is slightly compressed by the
spinous processes 17 when the implant 10 is positioned at the
lamina/spinous process junction. The implant 10 thereby allows, in
this position, the supra-spinous posterior ligament 5 to be reset
at anatomical tension.
[0046] The portion 15 is perforated by two transverse channels 20
which are intended to receive, as shown in FIG. 6, two independent
cords 21. These cords 21 serve to connect the implant 10 securely
to the processes 17. Each cord 21 can be constituted by a braid,
one end of which is crimped to the end of a curved insertion needle
and the other end of which comprises a ring which is to be crimped
to the cord 21 after the cord has been secured tightly to the
corresponding process 17.
[0047] The lugs 16 have substantial heights relative to the total
height of the implant 10 in the order of, for the upper and lower
lugs, 33% and 40% of the total height, respectively. The internal
faces of two lugs 16 of the same pair of lugs are inclined so as to
converge towards each other in the direction towards the base of
the recess which they together delimit. The lugs 16 further have a
relatively large mean thickness relative to the mean width of the
implant 10 in the order of, for the upper and lower lugs, 27% and
30% of this mean width, respectively. These lugs 16 allow the
securing of the implant 10 between the processes 17 to be ensured
in spite of the relative movements of the vertebrae 2,3, in
particular the pivoting movements about the axis of the vertebral
column.
[0048] The inter-corporeal implant 11 is also formed by a core of
silicone which is surrounded by a woven casing, in particular of
polyester fibers, ensuring the protection of this core. It has a
curved shape, in the form of a portion of a ring, and is sized so
as to extend, after positioning, along a wide anterior portion of
the peripheral edges of the vertebral bodies 7, 9. It has a height
such that it allows, when it is positioned, the anatomical height
of the disc 4 to be restored and the anterior common ligament 6 to
be reset at anatomical tension.
[0049] In practice, an ablation of the inter-spinous ligament
complex is carried out via the lateral access route, then the
vertebrae 2, 3 are separated and the posterior implant 10 is
positioned between the spinous processes 17, directly behind the
surfaces 8, that is to say, at the lamina/spinous process junction.
The flexibility of the lugs 16 does not inhibit this insertion. The
two lugs 16 which are located at the side at which the implant 10
is inserted can be secured in a position turned towards each other
in order to facilitate the insertion of the implant 10. Each cord
21 is then engaged through the ring which it comprises and is
secured tightly around the corresponding process 17 by sliding
through this ring. The ring is then crimped to the cord 21 in order
to keep the cord in a position for securing the process 17. The
implant 10, being secured in this manner, can be stressed in terms
of both compression and extension.
[0050] The implant 11 is itself inserted between the vertebral
plates of the two vertebrae 2, 3 via the same posterior/lateral
access route as that used during a dissectomy. As shown by FIG. 4,
the positioning of this implant 11 is carried out by means of an
instrument 25 which comprises an introduction tube 26 which is
provided with a piston 27 and a piston rod 28. The implant 11 is
engaged, with compression, in this introduction tube and is
expelled therefrom at the moment when it is positioned, by means of
the piston 27.
[0051] The implants 10 and 11 jointly allow the anatomical spacing
of the vertebrae 2, 3 to be re-established both between the
surfaces 8 and between the vertebral plates, but also allow the
anterior common ligament 6 and the supra-spinous posterior ligament
5 to be conserved, with these ligaments being placed at anatomical
tension.
[0052] When the vertebral column flexes forwards, the supra-spinous
posterior ligament 5 can then once more ensure the anatomical
function thereof of limiting the movement. The implant 10 allows,
owing to its ability to be extended, the action of this ligament to
be assisted and controlled. Simultaneously, the implant 11 restores
the shock-absorbent function of the disc 4 and takes up the
stresses applied in terms of pressure by the superior vertebral
body 7 on the inferior vertebral body 9, with relief being provided
for the peripheral annulus fibrosus. In this manner, it provides
progressive absorption of shocks for this superior vertebral body
7, with any risk of contact between the vertebral bodies 7,9 being
prevented.
[0053] When the vertebral column flexes backwards, the anterior
vertebral ligament 6 can again ensure the anatomical function
thereof of progressively limiting the movement. Simultaneously, the
implant 10 is compressed and then assists the surfaces 8 in the
function thereof as hinges and of posterior balancing.
[0054] FIGS. 7 and 8 show that the inter-corporeal implant 11 can
also, instead of or in addition to an inter-corporeal implant 11 as
illustrated in FIGS. 1 to 6, be provided to replace and/or assist
the nucleus. As shown in FIG. 7, it can then have a general "bean"
or "omega"-like shape, with a central portion which is extended by
two lateral lobes protruding at the posterior side or, as shown in
FIG. 8, be in the form of a sphere which is provided with an
equatorial lip which reduces the risk of displacement thereof. In
the second case, the implant 11 comprises the sphere 11a and a ring
11b which forms the lip, the opening of this ring 11b having a
diameter less than that of the sphere 11a and the sphere 11a being
engaged with deformation through this opening, then being fixed to
the ring 11b.
[0055] FIG. 9 shows that the posterior implant 10 can have an
"H"-like shape and comprise a clip 30 which secures two lateral
lugs 10a of this-implant in a deformed state, in which the lugs 10a
are brought closer towards each other. The clip 30 thereby allows
easier lateral insertion of the implant 10 between the spinous
processes 17 of the vertebrae 2, 3 being treated, until the
non-deformed lugs are brought against the processes 17, and the
clip 30 is then withdrawn in order to deploy the lugs 10a and, in
this manner, secure the implant in position.
[0056] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only some embodiments have been shown and
described and that all changes and modifications that come within
the meaning and equivalency range of the appended claims are
intended to be embraced therein.
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