Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SPINAL IMPLANT APPARATUS
This application claims priority under 35 U.S.C. 119 to France Patent
Application
No. 04 05691, filed May 26, 2004, and to France Patent Application No. 04
05692, filed
May 26, 2004.
BACKGROUND
Apparatus and systems for correcting deformations of the spine often comprise
one
or more rods extending along a portion of the spine. In the exainple of the
sacral region of
the spine, such rod(s) are usually fixed to the sacrum of the patient by way
of a plate
which, for instance, may straddle vertebrae S 1 and S2 and bear a protrusion
on which
apparatus such as a slotted connector is fitted and immobilized. Such a
slotted connector
may be itself traversed by a rod and immobilize the latter by a wedging
action. An
example of such a plate is described in document WO-A-02/38061, for example.
It is also known to provide a plate which is fixed not on two vertebrae such
as S 1
and S2, but on one vertebra (for example S 1) and on iliac bone of the
patient. For this
purpose, the plate may include, at one of its ends, a lateral extension
provided with an
orifice for the passage of a bone anchoring screw. This lateral extension is
oriented in the
direction of an iliac bone and is thus situated outside the plane of the
plate, with which it
normally forins an angle of the order of 50 degrees. In this way, the iliac
bone can be
connected to the rod. Different sizes of these sacral plates with iliac
extension are
available and are used in accordance with the morphology of the patient.
However, the
adaptation of the plate to the exact morphology of the patient is often only
approximate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of an embodiment of an implant.
FIG. 2 shows a plan view of the einbodiment of FIG. 1 mounted on the sacrum
and
iliac bone of a patient.
FIG. 3 shows a perspective view of a portion of the embodiment of FIG. 1.
FIG. 4 shows a perspective view partially in section of a portion of the
embodiment of FIG. 1.
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FIG. 5 shows a side view partially in section of a portion of the embodiment
of
FIG. l .
FIG. 6 shows a perspective view of a portion of the embodiment of FIG. 1 with
embodiments of additional structure.
FIG. 7 shows a perspective view partially in section of the embodiments in
FIG. 6.
FIG. 8 shows a perspective view of a series of additional embodiments of part
of
the implant of FIG. 1.
FIG. 9 shows a perspective view of another embodiment of an implant mounted on
iliac bone and vertebra(e) of a patient.
FIG. 10 shows a perspective view of another embodiment of an implant.
FIG. 11 shows a partial cutaway view in perspective of a portion of the
embodiment of FIG. 10.
FIG. 12 shows a side view partially in section of a portion of the embodiment
of
FIG. 10.
FIG. 13 shows a perspective view of a portion of the einbodiment of FIG. 10
with
embodiments of additional structure.
FIG. 14 shows a perspective view partially in section of the embodiments in
FIG.
13.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
For the purposes of promoting an understanding of the principles of the
invention,
reference will now be made to the embodiment illustrated in the drawings and
specific
language will be used to describe the same. It will nevertheless be understood
that no
limitation of the scope of the invention is tliereby intended. Any such
alterations and
further modifications in the illustrated device, and any such further
applications of the
principles of the invention as illustrated herein, are contemplated as would
normally occur
to one skilled in the art to which the invention relates.
Referring first generally to FIGS. 1 to 7, an embodiment of an implant is
shown.
In the illustrated embodiment the implant has two parts. Plate 1 that may be
fixed on the
sacrum of a patient, for example on vertebra S 1. In the illustrated
embodiment, plate 1 is
oblong or elongated, and is fixed by means of a bone anchor 2, which may be a
bone
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screw. Plate 1 includes an aperture 3, and in a particular einbodiment
includes a hole 4
that at least slightly overlaps aperture 3 and may be threaded. Anchor 2
passes through
aperture 3 in plate 1 and into contact with bone. In embodiments having a
threaded hole 4,
a plug or screw (not shown) can be screwed in so as to immobilize the head of
screw 2 and
prevent it from migrating from its seat after placement. An upper surface 40
and a lower
surface 24 of plate 1 may be substantially flat.
The illustrated embodiment of plate 1 also has a protrusion or shaft 5 and a
dome
8. Shaft 5 has a longitudinal axis and is threaded in a particular embodiment,
and a
connector 6 can be fitted around at least a portion of shaft 5, as will be
further described
below. In the example shown, the lower part of protrusion 5 includes a
spherical surface
19 and is traversed by a slot 20 substantially perpendicular to protrusion 5.
As may be
seen in FIG. 5, the illustrated embodiment of slot 20 is delimited by an upper
surface 21 of
V shape whose point 22 is situated substantially on the axis of symmetry 23 of
protrusion
5. An upper part of shaft 5 includes a notch or line of lesser resistance 30
to enable shaft 5
to be relatively easily cut or broken, and a head portion 44. Head portion 44
may be
configured hexagonally, as in the illustrated embodiment, or may include
lobes, slots,
internal prints or other configurations to permit gripping, holding, turning,
and/or other
manipulations.
Dome 8, in the illustrated embodiment, extends above upper surface 40 of plate
1
and has an outer surface 46 that is curved, and in a particular embodiment may
forin part
of a sphere, and an inner surface 26 that is substantially conical in a
particular
embodiment. Dome 8 at least partially surrounds an orifice 25 that extends
through plate
1, e.g. from a top edge of dome 8 through to lower surface 24 of plate 1. One
or more
holes 48 may be placed througli dome 8, which holes 48 may extend from inner
surface 26
all the way through dome 8 to outer surface 46. As will be discussed further
below, shaft
5 is inserted into orifice 25 so that surface 19 of shaft 5 is adjacent to or
contacting inner
surface 26 of dome 8. In the illustrated embodiinent, a pin 27 is also
provided that is
inserted through hole(s) 48 in dome 8 after shaft 5 is inserted through
orifice 25. Pin 27
extends through slot 20 of shaft 5, and point 22 may be just above pin 27. In
one
particular embodiment, pin 27 has a diameter practically equal to the width of
slot 20 to
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prevent any significant rotation of protrusion 5 about axis 23. Pin 27
inhibits protrusion 5
from falling out of orifice 25.
Protrusion 5 can be fixed, for example substantially perpendicular to the
upper
surface of plate 1 or, as in the example shown, it can be pivotable and/or of
the type
referred to as "multi-axial," that is to say capable of being oriented inside
a cone whose
angle may be of the order of 30 degrees. The means ensuring this multi-axial
orientation
can be of various types, and the illustrated example will be described in more
detail below.
The illustrated embodiment of plate 1 also includes a longitudinal rod 10
extending
therefrom, and which may be directed toward the lower part of the sacrum. Rod
10 may
be substantially cylindrical and may be of any desired length or diameter
compatible with
spinal fixation. The einbodiment shown depicts rod 10 to have a length
comparable to or
somewhat less than the length of plate 1, and a diameter comparable to or
slightly larger
than the distance between surfaces 40 and 24 of plate 1.
Lateral extension plate 13 connects to plate 1. In the illustrated embodiment,
plate
13 includes a portion 50 having an orifice 12 sized and configured to
accommodate at least
part of rod 10 of plate 1, and an aperture 52 that intersects orifice 12.
Aperture 52 may be
threaded to accommodate a threaded plug or screw 11. Plate 13 also includes a
portion 54
with an aperture 14 for accommodating a bone screw 15. Portion 54 is intended,
in one
particular embodiment, to lie adjacent to or contact an iliac bone 16 of a
patient. Further,
the illustrated embodiment of portion 54 includes two subparts 54a and 54b,
each of which
lie substantially in a plane, which planes are angled with respect to each
other. The plane
of part 54a is also angled with respect to portion 50. Thus, rod 10 of plate 1
may be
inserted into orifice 12 of plate 13 and can be immobilized therein by
threaded plug or
screw 11 inserted through aperture 52. Aperture 14 of plate 13 permits
implantation of
screw 15 (FIG. 2) which penetrates into an iliac bone 16 of the patient in
such a way as to
fix plate 13 there.
The illustrated embodiment of connector 6 includes an upper portion 58 and a
lower portion 60 that are connected by ajoining portion 62. A slot 64
separates upper
portion 58 and lower portion 60 in the norinal or unstressed configuration. A
channel 66
passes through connector 6. Channel 66 is sized and configured to accommodate
at least a
portion of spinal rod 7. Holes 29 are also provided through upper portion 58
and lower
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portion 60, and may be coaxial in a particular embodiment. In one specific
embodiment,
the contact between a spherical outer surface 46 of dome 8 and connector 6 is
a sphere-to-
cone contact. To that end, as seen in FIG. 7, holes 29 may have a conical
internal surface
28. As will be discussed further below, connector 6 can be immobilized on dome
8,
5 carried by plate 1, by means of a nut 9, which also closes slot 64 of
connector 6 to allow
connector 6 to clamp rod 7. Nut 9 includes an upper portion 70 and a lower
portion 72
separated by a notch or line of lesser resistance 31.
To assemble the illustrated embodiment, protrusion 5 is engaged through the
lower
face 24 of plate 1 and is passed through an orifice 25 arranged at the summit
of dome 8.
Surface 19 of protrusion 5 thus comes into contact with inner surface 26 of
dome 8. Pin
27 may then be fitted, which passes through dome 8 and comes to lie in slot 20
traversing
the lower part of protrusion 5. As will be seen in FIG. 5, point 22 of the V-
shaped upper
surface delimiting slot 201ies above pin 27, permitting only very slight
vertical clearance
of the protrusion 5 inside the dome 8 in this embodiment. Protrusion 5 can
pivot around
pin 27 to the degree permitted by dome 8, and can pivot in the plane defined
by
longitudinal axis 23 of protrusion 5 and pin 27 to the degree permitted by the
depth of slot
20. The illustrated embodiment of pin 27 has a diameter practically equal to
the width of
slot 20, preventing any significant rotation of the protrusion 5 about its
axis 23. These
configurations of the lower part of the protrusion 5 and of the inner surface
of the dome 8
provide for a complete multi-axial orientation of the protrusion 5 (typically
inside a cone
with an angle of about 30 degrees).
Plate 1 is connected to plate 13 by inserting rod 10 into and/or through
orifice 12.
Prior to locking down plug 11, plate 1 can be rotated with respect to plate
13, as indicated
by arrows 17 (FIG. 1), and plate 1 can be translated longitudinally with
respect to plate 13,
as indicated by arrows 18 (FIG. 1). In this way, a particular relationship
between plate 1
and plate 13 in terms of angle and distance can be made. Plate 13 is attached
to bone, in a
particular embodiment iliac bone, by inserting screw 15 through aperture 14 in
plate 13
and into the bone. Plate 1 is attached to bone, in a particular embodiment
sacral bone such
as S 1, by inserting screw 2 through aperture 3 in plate 1 and into bone. In
embodiments
having hole 4, a plug is placed in hole 4 to cover at least a portion of screw
2 to inhibit
screw 2 from backing out, as previously noted.
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Connector 6 is placed over shaft 5 so that shaft 5 is at least partially
within holes
29 of connector 6. As has been discussed, in certain embodiments shaft 5 may
be pivoted
or otherwise moved to allow placement of comiector 6, or once connector 6 has
been
placed to enable completion of the construct, or for other purposes of the
surgeon. Nut 9
is threaded onto shaft 5 and tightened as the surgeon desires so that
connector 6 is
squeezed between nut 9 and dome 8 of plate 1. Such tightening causes connector
6 to
clamp spinal rod 7, and also holds connector 6 and plate 1 together. Depending
on the
configuration given to connector 6, it may be possible, after tightening nut
9, either to
return protrusion 5 automatically to an orientation substantially
perpendicular to plate 1
(e.g. the multi-axial nature of protrusion 5 will thus have served only during
implantation
of the corrective apparatus), or to retain protrusion 5 in an orientation not
perpendicular to
plate 1, as seen in one embodiment in FIG. 6.
After such apparatus has been fitted in place, the surgeon generally removes
those
parts of protrusion 5 and of nut 9 which are redundant. For exainple, in one
embodiment
torque may be applied until a break occurs at notch 30 and/or 31, or notches
30 and 31
could serve as markers to cut their respective pieces. It is also possible to
arrange such
lines of lesser resistance on longitudinal rod 10 of plate 1 so that, if
necessary, it is easy to
shorten the part of rod 10 extending beyond plate 13. However, care must be
taken to
ensure that these lines of lesser resistance do not significantly impair the
mechanical
strength of rod 10 during the stresses to which it is subjected after the
device has been
fitted.
Plate 13 may be provided in and chosen from several models with different
geometries and sizes, such as those shown in FIG. 8, which are shown fitted on
the same
rod 7. These examples, showing apertures 14 that range from substantial
elongation to
substantially circular and some of which include the angled portion of plate
13 described
above, are some of the configurations that might be provided so that the
geometry of the
implant can be optimally adapted to the particular morphology of the patient
and to the
exact site of fixation of the implant. With such models, it is possible to
achieve a whole
variety of implant geometries with the aid of a single model of plate 1.
In another embodiment, shown in FIG. 9, an implant is fixed on an iliac bone
16 by
a screw 15, including a lateral extension plate 13 substantially as described
above, in
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whose orifice 12 a spinal rod 7 is directly inserted. In the example shown,
rod 7 is fixed to
other parts of the spine by slotted connectors 6, mounted on protrusions
carried by bone
anchoring screws.
Turning now to FIGS. 10-14, a further embodiment of an implant including plate
101 is shown. Plate 101 may be a sacral plate, e.g. for implantation
straddling vertebrae
such as S 1 and S2 of the patient. Plate 101 is fixed to these by two bone
anchoring screws
(not shown) which pass through orifices 102, 103 each formed at a respective
end of plate
101. This embodiment of plate 101 includes a lateral extension 104 provided
with an
aperture 105 through which a bone anchoring screw (such as screw 15) may pass
and
penetrate into, for example, iliac bone of the patient. It must be understood,
however, that
the disclosure herein is applicable to any type of sacral plate, and generally
to any type of
element of a device for correcting spinal deformations which has a protrusion
on which a
connector can be fitted. It would in particular be applicable to a case where
the protrusion
is supported by a simple bone anchoring screw or by a hook.
Extension 104 is laterally positioned and integral with the remainder of plate
1 in
the illustrated embodiment, having a longitudinal direction that in one
particular
embodiment is substantially perpendicular to a longitudinal direction of the
remainder of
plate 1. Extension 104 has a first portion 104a and a second portion 104b. In
the
illustrated embodiment, first portion 104a is substantially planar, and second
portion 104b
is substantially planar, and there is an angle between the planes of portions
104a and 104b.
In addition, in the illustrated embodiment portion 104b is in a plane
substantially parallel
to upper surface 130 of plate 1, and aperture 105 is oblong or oval-shaped.
Plate 101 includes several aspects that are similar or identical to the
structures and
methods discussed above with respect to the embodiment of plate 1. Plate 101
includes a
protrusion 106 on which a connector 107 is to be fitted, which connector 107
is itself fitted
on the rod 108 of the corrective device, the outline of which is represented
in FIG. 4. The
connector 107 is clainped on a spherical outer surface of a dome 109 forined
on the upper
surf ace of the plate 101. This clamping is done witli the aid of a nut 110
screwed onto a
thread present on the protrusion 106. The illustrated embodiments of
protrusion 106,
connector 107, dome 109 and nut 110 are essentially the same as protrusion or
shaft 5,
connector 6, dome 8 and nut 9 described above.
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As with embodiments discussed above, protrusion 106 is engaged through the
lower face 116 of plate 101 and is passed through an orifice 117 arranged at
the summit of
dome 109. Surface 111 of protrusion 106 thus comes into contact with inner
surface 118
of dome 109. Pin 119 may then be fitted, which passes through dome 109 and
comes to
lie in slot 112 traversing the lower part of protrusion 106. As will be seen
in FIG. 12, point
114 of the V-shaped upper surface 113 delimiting slot 112 lies above pin 119,
permitting
only very slight vertical clearance of the protrusion 106 inside the dome 109
in this
embodiment. The illustrated embodiment of pin 119 has a diameter practically
equal to
the width of slot 112, preventing any significant rotation of the protrusion
106 about its
axis 115.
Extension 104 is attached to bone, in a particular embodiment iliac bone, by
inserting a screw (e.g. a bone screw such as screw 15 discussed above) through
aperture
105 in extension 104 and into the bone. Plate 101 is fui-ther attached to
bone, in a
particular embodiment sacral bone such as Sl, by inserting screws (e.g. bone
screws such
as screw 2 discussed above) through apertures 102 and 103 in plate 101 and
into bone. In
embodiments having hole 132 (similar or identical to hole 104 discussed
above), a plug is
placed in hole 132 to cover at least a portion of the screw in aperture 102 to
inhibit the
screw from backing out, as previously noted.
Connector 107 is placed over shaft 106 so that shaft 106 is at least partially
within
holes (e.g. holes 121 in FIG. 14) of connector 107. As has been discussed, in
certain
embodiments shaft 106 may be pivoted or otherwise moved to allow placement of
connector 107, or once connector 107 has been placed to enable completion of
the
construct, or for other purposes of the surgeon. Nut 110 is threaded onto
shaft 106 and
tightened as the surgeon desires so that connector 107 is squeezed between nut
110 and
dome 109 of plate 101. Such tightening causes connector 107 to clamp spinal
rod 108,
and also holds connector 107 and plate 101 together. For example, conical
surface(s) 120
of connector 107 may be pressed against spherical surface 111 of shaft 106.
Depending
on the configuration given to connector 107, it may be possible, after
tightening nut 110,
eitlier to return protrusion 106 automatically to an orientation substantially
perpendicular
to plate 101 (e.g. the multi-axial nature of protrusion 106 will thus have
served only during
implantation of the corrective apparatus), or to retain protrusion 106 in an
orientation not
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perpendicular to plate 101, as seen in one embodiment in FIG. 13. The multi-
axial nature
of protrusion 106, in the illustrated embodiment, is substantially the same as
that described
above with respect to protrusion 5.
After such apparatus has been fitted in place, the surgeon generally removes
those
parts of protrusion 106 and of nut 110 which are redundant, as discussed above
with
respect to protrusion 5 and nut 9. Other manipulations may also be made by the
surgeon,
as discussed above.
Various modifications to the subject matter described above are possible. For
example, for fixing the different parts of the implant on the spine or on an
iliac bone, it
would be possible to use means other than bone anchoring screws. As has been
stated, the
application of the invention is not limited to plates, but instead can also be
applied to any
element of an installation for correcting spinal deformations which comprises
a protrusion
for fitting a connector for which a teinporary or permanent multiaxial
orientation is
sought.
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 all changes and modifications that come
within the
spirit of the invention are desired to be protected.
