Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2022/PCT CA 02538105 2006-03-08
4.9.2003
English translation of the specification of the International Patent
Application No.
PCT/CH03/00605 "Longitudinal support" in the name of Mathys Medizinaltechnik
AG
Longitudinal support
The invention concerns a longitudinal support element according to the
preamble
of patent claim 1, a longitudinal support to stabilise bones, particularly
bodies of
the vertebra according to patent claim 5 and a device to stabilise bones,
particularly bodies of the vertebra, according to patent claim 14.
The current treatment of damaged or tumorous bodies of the vertebra comprises
usually the implanting of a rigid longitudinal support, anchored on the bodies
of
the vertebra by bone anchoring means or a rigid bone plate. The purpose of
these devices is to prevent, by means of the rigid implants, the movement of
the
bodies of the vertebra stabilised in this manner relative to one another and
to
promote the fusion of adjacent bodies of the vertebra.
A device to stabilise the bodies of the vertebra using a multi-segmented
longitudinal support that can be fixed in a desirable form, is known from FR 2
796
828 Jammet. By using this, the longitudinal support, comprising a plurality of
axial
segments and intended for the stabilisation, can be joined with the head
segments of the pedicle screws or pedicle hooks, which for the purpose of
stabilisation are screwed into the pedicle of the corresponding body of the
vertebra, and can be adapted without using great force to suit the form
specified
by the positions of the pedicle screws. It is a disadvantage of this prior
known
device, that the longitudinal support elements can be fastened individually on
the
head segments of the pedicle screws or pedicle hooks and cannot be joined with
one another, so that each longitudinal support element has to be individually
inserted and placed into the body of the patient, representing to the surgeon
a
tedious and time-consuming step of the operation.
This is where the invention wants to provide remedy. The object of the
invention
is to produce a longitudinal support element with an articulated socket, in
the
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cavity of which a complementary articulated head of a further longitudinal
support
element can be elastically snapped in, so that a longitudinal support,
comprising
a plurality of longitudinal support elements, can be pre-assembled outside of
the
patient's body.
This objective is achieved by the invention with a longitudinal support
element
having the features of claim 1, with a longitudinal support to stabilise
bones,
particularly bodies of the vertebra, that has the features of claim 4 and with
a
device to stabilise bones, particularly bodies of the vertebra, that has the
features
of claim 14.
The advantages achieved by the invention are basically that as a result of the
longitudinal support element according to the invention
~ a longitudinal support, comprising a plurality of longitudinal support
elements
which can be joined with one another, can be pre-assembled,
~ the longitudinal support can be adapted in-situ to suit the desired geometry
without using any force,
~ the implanting of the longitudinal support can be considerably simplified.
In the preferred embodiment the articulated socket can be made from a nickel
titanium alloy (Nitinol), wherein 45%<Ni<55%, 45%<Ti<55% and x + y = 100%.
Such a material is biocompatible and highly elastic.
In another embodiment the articulated socket has an external spherical convex
construction, thus achieving the advantage of a polyaxially pivotable
accommodation of the articulated socket in, for example, a bone anchoring
means constructed as a tulip screw.
In yet another embodiment the first connecting segment of the longitudinal
support element comprises an outside thread.
The advantages of the longitudinal support according to the invention are
basically that
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~ a first longitudinal support element, having an articulated socket, can be
polyaxially pivotably joined with a second longitudinal support element having
a
complementary articulated head, and
~ the longitudinal support can be shaped to suit the anatomy.
In a preferred embodiment the connection between a first connecting segment of
a first longitudinal support element and a first connecting segment of a
second
longitudinal support element can be axially lengthened or shortened, so that a
first longitudinal support element can be coaxially joined with a second
longitudinal support element and the length of the longitudinal support
segment
formed by the two longitudinal support elements can be adjusted.
This longitudinally adjustable connection between the two longitudinal support
elements can telescope or be realised as a screw joint. For this purpose the
first
connecting segment can be constructed as a coaxial shaft on the first
longitudinal
support element and the thread be constructed as an outside thread and the
first
connecting segment constructed as a sleeve on the second longitudinal support
element, the sleeve comprising a central bore with an inside thread that
complements the outside thread.
In a further embodiment the articulated head has a spherical convex design and
the cavity of the articulated socket is complementary to it.
In another embodiment the articulated head and the articulated socket can be
elastically snapped into one another. This will bring the advantage, that a
simple
pre-assembly of a longitudinal support, comprising a plurality of longitudinal
support segments, is possible.
In yet another embodiment the longitudinal support comprises an end-piece with
an articulated head that can be snapped into an articulated socket. This has
the
advantage that an articulated socket, provided at the end of the longitudinal
support, will not be compressed when mounted in the receptacle on the head of
a
pedicle screw. The longitudinal support preferably comprises a second end-
piece
with an articulated socket.
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The device according to the invention to stabilise bodies of the vertebra
essentially comprises a longitudinal support according to one of the above
illustrated embodiment and
A) at least two bone anchoring means each with a central axis, an anchoring
segment each to fix the bone anchoring means on a bone, in particular on a
body of the vertebra and a head segment each with means to accommodate
the articulated socket, and
B) fixing means to fix the articulated sockets in the means to accommodate the
articulated socket.
In a preferred embodiment the means to accommodate the articulated socket are
constructed as a concave spherical recess, that complements the articulated
socket.
In another embodiment the fixing means comprise a tightening screw, that can
be
screwed into an inside thread in the head of the bone anchoring means, so that
an articulated socket can be secured in the bone anchoring means using the
fixing means.
In yet another embodiment the fixing means comprise an elastically expandable
clamp, that can be placed over the articulated socket and can be snapped onto
the head segment of the bone fixing means, while after the assembly of the
clamp the articulated socket is compressed by the clamp. This will bring with
it
the advantage, that due to the compressing of the second articulated part the
articulation is locked between the two longitudinal support segments on the
one
hand and on the other hand the longitudinal support is fixed on this bone
anchoring means.
The clamp has preferably a lug on each of its free end, that can be snapped
onto
the head segment of the bone anchoring means. For a better acceptance of the
lugs notches, complementing the lugs, may be provided on the head segment.
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The invention and developments of the invention are explained below in detail
based on the partly schematic illustrations of several embodiments. They show
in:
5 Fig.1 - a side view of an embodiment of the longitudinal support according
to the
invention, with type A and type B longitudinal support elements provided
alternating behind one another,
Fig.2a - a longitudinal section through an embodiment of the device according
to
the invention,
Fig.2 b - a cross-section through the embodiment of the device according to
the
invention and illustrated in Fig.2a, and
Fig.3 - a cross-section through another embodiment of the device according to
the invention.
Fig.1 illustrates an embodiment of the longitudinal support 20 with type A and
type B longitudinal support elements 7, 8 provided alternating behind one
another
and with an end-piece 18, 21 at each end. The connecting segments 9, 10, 12,
13 of both longitudinal support elements 7, 8 are so constructed, that a first
connecting segment 9 of a first longitudinal support element 7 (type A) forms
with
a second longitudinal support element 8 (type B) a coaxial connection, that
can
be adjusted only axially longitudinally, while a second connecting element 10
of a
first longitudinal support element 7 (type A) with a second connecting element
13
of a second longitudinal support element 8 (type B) allows a polyaxially
pivotable
connection of the two longitudinal support elements 7, 8. In this case the
first two
connecting segments 9, 12 can be particularly joined by a thread connection
42,
in such a manner that the first longitudinal axis 23 of the longitudinal
support
element 7 (type A) and the second longitudinal axis 24 of the longitudinal
support
element 8 (type B) are arranged coaxially. In this case the thread connection
42
is so constructed, that the first connecting segment 9 of the first
longitudinal
support element 7 (type A) comprises a shaft 31 with an outside thread 11 and
the first connecting segment 12 of the second longitudinal support element 8
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(type B) comprises a sleeve 32 with a central bore 42 having an inside thread
34
that complements the outside thread 11. The construction of the threaded bore
42 could be constructed by interchanging the connecting segments 9, 12.
The longitudinal support element 7 (type A) comprises two connecting segments
9, 10, which are coaxial with the first longitudinal axis 23 and are provided
behind
one another and at the ends a first and a second end 14, 15. In this
conjunction
the first connecting element 9 of the longitudinal support element 7 (type A)
is
constructed as a cylindrical shaft 31 with a thread 11. The second connecting
segment 10 of the longitudinal support element 7 (type A) comprises an
articulated socket 28 with a hollow spherical segment-like, coaxial cavity 30,
said
socket can be elastically deformed transversely to the first longitudinal axis
23,
while said cavity at the second end 15 of the longitudinal support element 7
has
an opening 16 that is concentric with the first longitudinal axis 23. An
articulated
head 29, which has a construction comalementina the cavity 30. can hp
introduced into the cavity 30 through the opening 16, so that the articulated
head
29 and the articulated socket 28 form a ball and socket joint. The two
longitudinal
support elements 7, 8 (types A and B), connected in this manner, are then
displaceable relative one another in such a manner, that the first and the
second
longitudinal axis 23, 24 can pivot relative one another about the centre of
the
articulate joint. Furthermore, the cavity 30 has a diameter D, that is greater
than
the diameter d of the opening 16, so that an articulated head 29, introduced
into
the cavity 30, is axially enclosed by more than 180°. In addition, the
articulated
socket 28 is provided with four slots 22 which are parallel to the
longitudinal axis
23 and pass through from the outside to the cavity 30 and allow a radial
elastic
deformation of the articulated socket 28.
The longitudinal support element 8 (type B) comprises also two connecting
segments 12, 13 provided coaxially with its longitudinal axis 24 behind one
another, as well as a first and a second end 25, 26 at its ends. The first
connecting element 12 of the longitudinal support element 8 (type B) is
constructed as a sleeve 32 that is coaxial with the second longitudinal axis
24
and has a central bore 33, while the central bore 33 is provided with an
inside
thread 34, that is complementary to the thread 11. The second connecting
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element 13 of the longitudinal support element 8 (type B) is constructed as a
spherical articulated head 29, that is complementary to the articulated socket
28.
The first end-piece 18 has an analogous construction with the articulated head
29, while the second end-piece 21 has an analogous construction with the
articulated socket 28. The two end-pieces 18, 21 allow to accommodate the
articulated socket 28 and the articulated head 29, respectively, in, for
example, a
commercially available pedicle screw or pedicle hook with a spherical concave
recess 36 (Fig.2).
In Figs.2a and 2b a detail of an embodiment of the device 1 to stabilise
bodies of
the vertebra with a longitudinal support 20 according to Fig.1 are illustrated
with
two bone anchoring means 3, connected by the longitudinal support 20, while
the
bone anchoring means 3 are constructed in this case as pedicle screws. The
longitudinal support 20 comprises several longitudinal support elements 7, 8
(type
A and type B) provided alternating behind one another, wherein in the detail
illustrated here two longitudinal support elements 7 (type A) are articulately
connected. via their first connecting segments 9 with the first connecting
segments 12 of two longitudinal support elements 8 (type B) and the
longitudinal
support element 7 (type A) is connected with the longitudinal support element
8
(type B) via its second connecting segment 10 in such a manner that it can be
only axially displaceable. The articulated heads 29 of the second longitudinal
support elements 8 (type B) are snapped into the articulated sockets 28 of the
adjacent first longitudinal support elements 7 (type A). To connect the head
segments 6 of the bone anchoring means 3 with the articulated sockets 29,
channels 50 are provided on the head segments 6, with channel axes 53
extending transversely to the central axis 3 of the bone anchoring means 3.
The
channels 50 pass through the head segments 6 of the bone anchoring means 3
transversely to the central axis 3 and are open to the free end 52 of the head
segment 6. For a polyaxially pivotable mounting of the articulated sockets 28
in
the channels 50, they have spherical recesses 36 at the bottom of the channels
50, which complement the articulated sockets 28. The head segments 6 further
comprise bores 55, penetrating from the free end 52, with inside threads 54.
The
fixing means 27 to fix the articulated sockets 28 are constructed in this case
as
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tightening screws 37, which can be screwed into the inside thread 54 from the
free end 52 of the head segment 6, so that the articulated sockets 28, placed
into
the channels 50, together with the snapped-in articulated heads 29, can be
fixed
in the channels 50 by tightening the tightening screws 37. When fixing the
articulated sockets 28, they are compressed transversely to the longitudinal
axes
23 of the first longitudinal support elements 7 (type A), due to which the
snapped-
in articulated heads 29 of the second longitudinal support elements 8 (type B)
are
blocked in the articulated sockets 28.
The embodiment of the device 1 illustrated in Fig.3 differs from that
illustrated in
Figs.2a and 2b only by that the fixing means 27 is constructed as a clamp 38,
the
legs 43 of which can be elastically expanded, so that he clamp 38 can be
guided
over the articulated socket 28 and can be snapped onto the head segment 6 of
the bone fixing means 3 by its elastic spring-back in such a manner, that
after
being assembled the articulated socket 28 is compressed by the clamp 38. Thus
the articulated socket 28 is secured in the head segment 6 of the bone
anchoring
means 3 first by virtue of the clamp 38 and, in addition, by compressing the
articulated socket 28 the articulated head 29 snapped in the articulated
socket 28
is locked in the head segment 6 of the bone anchoring means 3. To fasten the
clamp 38 on the head segment 6, the clamp 38 has at the free ends 39 of both
legs 43 an inward directed lug 40, that can snap into the complementary
notches
41, arranged at the fixed end 51 of the head segment.
Description of the operation:
First of all the bone anchoring means 3, in particular the pedicle screws or
pedicle
hooks are placed by the surgeon onto the pedicles of the bodies of the
vertebra
to be fixed. After this the longitudinal support elements 7, 8 (type A and
type B)
are joined alternating together outside of the patient's body, until the
longitudinal
support 20 has the desired length and contains the desired number of joints.
The
assembled longitudinal support 20 is then introduced into the patient's body
by a
minimally invasive incision and placed below the soft tissue surrounding the
body
of the vertebra to be fixed and bent at the articulated joints until it has
the desired
shape and the articulated heads 29 are introduced into the means 35 to
accommodate the articulated heads 29 on the bone anchoring means 3.
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Following this the fixing means 27 are pre-assembled on the head segments 6 of
the bone anchoring means 3, i.e. not yet locked, so that the longitudinal
support
20 can still be adjusted. At this stage the shape of the longitudinal support
20, as
well as the distances of the individual longitudinal support elements 7, 8 are
still
flexibly adjustable. As soon as the desired shape of the longitudinal support
20 is
set, the fixing means 27 are locked and consequently the entire fixing device
is
fixed.
