U.S. patent application number 11/347548 was filed with the patent office on 2006-07-06 for device for connecting a longitudinal bar to a pedicle screw.
This patent application is currently assigned to Synthes (USA). Invention is credited to Thomas Amrein, Martin Hess.
Application Number | 20060149244 11/347548 |
Document ID | / |
Family ID | 4550856 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060149244 |
Kind Code |
A1 |
Amrein; Thomas ; et
al. |
July 6, 2006 |
Device for connecting a longitudinal bar to a pedicle screw
Abstract
A device for connecting a longitudinal bar to a pedicle screw
for fixation of the spine includes a body having an axis, an upper
end, a lower end, a hole coaxial with the axis, and a through hole
positioned perpendicular to the axis. The device also includes a
collet chuck slidably disposed within the hole. The collet chuck
includes a through hole substantially aligned with the through hole
of the body for receiving the longitudinal bar. The collet chuck
also includes a chamber defined by elastic tongues for receiving
the head of the pedicle screw.
Inventors: |
Amrein; Thomas; (Horw,
CH) ; Hess; Martin; (Holstein, CH) |
Correspondence
Address: |
JONES DAY
222 EAST 41ST STREET
NEW YORK
NY
10017-6702
US
|
Assignee: |
Synthes (USA)
|
Family ID: |
4550856 |
Appl. No.: |
11/347548 |
Filed: |
February 2, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10122405 |
Apr 16, 2002 |
7022122 |
|
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11347548 |
Feb 2, 2006 |
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09341963 |
Sep 22, 1999 |
6371957 |
|
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PCT/CH97/00019 |
Jan 22, 1997 |
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10122405 |
Apr 16, 2002 |
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Current U.S.
Class: |
606/264 ;
606/266; 606/278 |
Current CPC
Class: |
A61B 17/7037 20130101;
A61B 17/7035 20130101; A61B 17/7034 20130101; A61B 17/7032
20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Claims
1. A spinal fixation system comprising: a longitudinal member; a
fastener having a head, the fastener being configured and
dimensioned for engaging vertebrae; and a connector for coupling
the fastener and longitudinal member comprising: a body having a
through hole extending from a top surface to a bottom surface, and
a first opening in a side surface for receiving the longitudinal
member; a collet chuck with at least a portion slidably received in
the through hole of the body, the collet chuck having external
threads and having a second opening for receiving the longitudinal
member, the second opening being alignable with the first opening,
and a plurality of resilient tongues defining a chamber for
receiving the fastener head therein; and a locking element
threadably associated with the external threads of the collet chuck
for releasably locking movement of the longitudinal member with
respect to the collet chuck; wherein engagement of the body with
the tongues of the collet chuck moves the tongues inward to secure
the fastener at a surgeon selected angle.
2. The spinal fixation system of claim 1 wherein the body comprises
top and bottom portions, the bottom portion having a sufficient
height so that the longitudinal member is in contact with the
bottom portion when secured in the first and second openings.
3. The spinal fixation system of claim 1 wherein the second opening
comprises a U-shaped portion.
4. The spinal fixation system of claim 3 wherein the second opening
communicates with the chamber.
5. The spinal fixation system of claim 1 wherein the body and
collet chuck are disposed about a central axis.
6. The spinal fixation system of claim 5 wherein the collet chuck
has upper and lower ends and an outside surface defined there
between, with the second opening extending through the outside
surface transverse to the central axis.
7. The spinal fixation system of claim 6 wherein the second opening
is remote from the upper and lower ends.
8. The spinal fixation system of claim 5 wherein the collet chuck
has upper and lower ends, and the second opening extends along the
central axis through the upper end.
9. A spinal fixation system comprising: a longitudinal member; a
fastener having a head and a threaded end for engaging a vertebra;
and a connector for connecting the fastener and the longitudinal
member comprising: a body having top, bottom, and side surfaces, a
first opening in the side surface for receiving the longitudinal
member, and a second opening extending from the top surface to the
bottom surface; a collet chuck configured and dimensioned to be
slidably received in the second opening of the body and having
upper and lower ends, a third opening in the upper end with
threading, a fourth opening alignable with the first opening of the
body for receiving the longitudinal member, a plurality of
resilient tongues, and a chamber defined by the tongues configured
and dimensioned to receive the fastener head; and a threaded
locking element for releasably fixing movement of the longitudinal
member with respect to the first and fourth openings, wherein
flexing of the tongues permits the fastener head to be received and
retained in the chamber, and threading of the locking element with
the threading of the collet chuck causes translation of the collet
chuck and body with respect to each other.
10. The spinal fixation system of claim 9 wherein a portion of the
locking element abuts the body when the locking element is
threadably associated with the threads of the collet chuck.
11. The spinal fixation system of claim 9 wherein the fourth
opening comprises a U-shaped portion.
12. A spinal fixation element system comprising: a spinal rod; a
bone fastener having a head and an end portion for engaging a
vertebra; and a connector for coupling the bone fastener to the
spinal rod, the connector including: a first member having a first
end, a second end, a through hole extending therebetween, and a
first rod receiving channel; a second member at least partially
slidably received in the through hole of the first member, the
second member includes a top end, a second rod receiving channel
substantially aligned with the first rod receiving channel when the
second member is partially disposed within the first member, and a
resilient bottom end defining a chamber for receiving the head of
the bone fastener; and clamping securing means associated with the
top end of the second member for releasably fixing the position of
the spinal rod with respect to the second member and for moving the
second member with respect to the first member without the securing
means directly engaging the first member; wherein movement of the
second member with respect to the first member causes the inward
movement of the bottom end of the second member so that the
position of the bone fastener is fixed with respect to the second
member.
13. The system of claim 12 wherein the first member includes a
bottom portion and a top portion, the bottom portion having a
sufficient height so that the spinal rod is in contact with the
bottom portion when secured in the first and second rod receiving
channels.
14. The system of claim 12 wherein the clamping means includes an
externally threaded surface formed adjacent the top end of the
second member for threadably engaging an internally threaded
nut.
15. The system of claim 12 wherein the clamping means includes an
inner threaded surface and an external threaded surface formed
adjacent the top end of the second member for threadably engaging
an externally threaded set screw and an internally threaded nut,
respectively.
16. The system of claim 15 wherein rotation of the internally
threaded nut fixes the position of the bone fastener with respect
to the second member while rotation of the externally threaded set
screw fixes the position of the spinal rod with respect to the
second member.
17. The system of claim 12 wherein the clamping means includes an
inner threaded surface formed adjacent the top end of the second
member for engaging an externally threaded locking screw, the
locking screw further including an internally threaded surface for
engaging an externally threaded set screw.
18. The system of claim 17 wherein rotation of the externally
threaded locking screw fixes the position of the bone fastener with
respect to the second member while rotation of the externally
threaded set screw fixes the position of the spinal rod with
respect to the second member.
19. The system of claim 12 wherein the rod receiving channel of the
second member is opened towards a side thereof so that the spinal
rod is side-loading.
20. The system of claim 19 wherein the rod receiving channel of the
first member is opened towards a side thereof.
21. The system of claim 12 wherein the rod receiving channel of the
second member is opened towards the top end so that the second rod
receiving channel is U-shaped.
22. The system of claim 21 wherein the rod receiving channel of the
first member is opened towards the top end so that the first rod
receiving channel is U-shaped.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a division of U.S. patent application Ser. No.
10/122,405, filed Apr. 16, 2002, now U.S. Pat. No. ______, which is
a continuation of U.S. patent application Ser. No. 09/341,963, now
U.S. Pat. No. 6,371,957, which is a national stage of PCT
International Application No. PCT/CH97/00019, filed Jan. 22, 1997,
all of which are hereby incorporated by reference in their
entireties.
FIELD OF THE INVENTION
[0002] The invention concerns a device for connecting a
longitudinal bar to a pedicle screw.
BACKGROUND OF THE INVENTION
[0003] From the related art, a large number of pedicle screws for
fixation of the spinal column are already known; these known
pedicle screws have the advantage that the individual pedicle screw
can be attached to or removed from the longitudinal bar at any time
without having to dismantle the entire fixation system. Such a
pedicle screw is known from European Patent No. 330,881 B, for
example.
[0004] The disadvantage of this and similar pedicle screws is the
relatively complicated locking mechanisms for securing the
longitudinal bar inserted into the open pedicle screw head.
Furthermore, in most cases the head of the screw can be aligned
with the position of the longitudinal bar only to a limited extent,
necessitating complicated bending of the longitudinal bar to
correct the angle.
SUMMARY OF THE INVENTION
[0005] The invention will provide a remedy in this regard and is
based on the problem of creating a device for connecting a
longitudinal bar to a pedicle screw, the device being easy to
handle and permitting bending of the pedicle screw within a certain
range.
[0006] The invention relates to a spinal fixation system including
a longitudinal member positionable along the spinal column, a
fastener for engaging a vertebra, and a connector for connecting
the fastener and the longitudinal member. One part of the connector
is a body having a through hole for receiving the longitudinal
member and an opening in the bottom surface leading to the interior
of the body. Another part of the connector is a collet chuck
configured and dimensioned to be slidably received in the interior
of the body. The collet chuck has a through hole alignable with the
body's through hole for insertion of the longitudinal member in the
connector. The collet chuck also has a plurality of resilient
tongues and a chamber defined by inner surfaces of the tongues. The
chamber is configured and dimensioned to receive the fastener head.
The tongues flex outward for receiving the fastener head in the
chamber and flex back inward for retaining the fastener head in the
chamber. The connector also includes a locking element for securing
the longitudinal member in the body and collet chuck through holes.
Engagement of the locking element causes inward movement of the
tongue and thereby secures the fastener at a surgeon selected
angle.
[0007] In one embodiment, the desired number of devices according
to the invention can be aligned on a longitudinal bar and can be
simply snapped onto the pedicle screw with a spherical head already
implanted in the vertebrae, so that a primary connection between
the longitudinal bar and the pedicle screw is established. Other
embodiments of the device according to the invention permit
subsequent insertion of the longitudinal bar from the side or from
above. By screwing the set screw into the fixation device, the
longitudinal bar is locked axially and rotationally in the device
at the same time, and the device is secured in a stable angular
position. The set screw presses on the longitudinal bar inserted
into the device, and the longitudinal bar presses on the bushing of
the fixation device, and the bushing braces the collet chuck on the
preferably spherical head of the pedicle screw by way of
corresponding, preferably conical inside surfaces of the bushing
and outside surfaces of the collet chuck.
[0008] Other embodiments permit sequential and independent locking
of the longitudinal bar and rotation of the device with respect to
the pedicle screw.
[0009] Thus, in comparison with known devices, the device according
to the invention offers the advantage that the pedicle screws
cannot only be secured exactly perpendicular to the longitudinal
bar, but also permit an angle bend of up to .+-.25.degree.. This is
especially important when the longitudinal bar has not been bent
accurately, which leads to major problems in assembly with
traditional systems.
[0010] A preferred refinement of the device according to the
invention also includes a pedicle screw with a preferably spherical
head. The head of the pedicle screw is preferably provided with
structuring in the form of transverse grooves or transverse ribs to
achieve better fixation (bracing against the collet chuck). To be
able to screw these pedicle screws into the bone, they are
preferably provided with a hexagon socket in the spherical
head.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The detailed description will be better understood in
conjunction with the accompanying drawings, in which like reference
characters represent like elements, as follows:
[0012] FIG. 1 is an exploded perspective view of the device with a
longitudinal bar, a pedicle screw with a spherical head, and a set
screw;
[0013] FIG. 2 shows a slotted longitudinal section through the
device as shown in the plane of FIG. 1;
[0014] FIG. 3 is a perspective view of the device of FIG. 1 in the
mounted state after locking the longitudinal bar and the pedicle
screw by means of the set screw;
[0015] FIG. 4 is an exploded perspective view of another embodiment
of the device shown in FIG. 1 with an adjusting nut and a divided
bushing;
[0016] FIG. 5 is an exploded perspective view of another embodiment
of the device shown in FIG. 4 with a channel on the collet chuck
that is open at the top and with a securing pin;
[0017] FIG. 6 is an exploded perspective view of another embodiment
of the device shown in FIG. 1 with an adjusting nut for securing
the spherical head of the pedicle screw and a set screw for locking
the longitudinal bar;
[0018] FIG. 7 shows a longitudinal section through another
embodiment of the device illustrated in FIG. 6 with a set screw
integrated into a locking screw;
[0019] FIG. 8 is an exploded perspective view of another embodiment
of the device shown in FIG. 5 with a collet chuck that is open at
the side to accommodate the longitudinal bar and an adjusting nut
as a chucking means for locking the longitudinal bar while at the
same time securing the spherical head of the pedicle screw;
[0020] FIG. 9 is an exploded perspective view of the device shown
in FIG. 5 without a securing pin;
[0021] FIG. 10 is an exploded perspective view of another
embodiment of the device shown in FIG. 5 with a set screw and an
inside thread in the collet chuck;
[0022] FIG. 11 is an exploded perspective view of another
embodiment of the device shown in FIG. 8 with an adjusting nut for
securing the spherical head of the pedicle screw and with a set
screw for locking the longitudinal bar;
[0023] FIG. 12 is an exploded perspective view of another
embodiment of the device shown in FIG. 11 with a collet chuck that
is open at the top;
[0024] FIG. 13 is an exploded perspective view of another
embodiment of the device shown in FIG. 11 with a through hole in
the bushing which is open at the side; and
[0025] FIG. 14 is an exploded perspective view of another
embodiment of the device shown in FIG. 12 with a through hole in
the bushing which is open at the top.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The device according to the invention illustrated in FIGS. 1
and 2 generally includes a body 3 in the form of a hollow
cylindrical bushing with an axis 4 (axis of the hollow cylinder)
and a hollow cylindrical collet chuck 7 arranged coaxially so it
can slide in the interior of body 3.
[0027] Body 3 has a through hole 6 running across axis 4 that
intersects the cylindrical surface of the hollow cylinder at two
points symmetrically with axis 4. Collet chuck 7 also has a through
hole 17 running across axis 4. Insertion of a longitudinal bar 1
running across axis 4 is made possible by the aligned arrangement
of through holes 6 and 17 as illustrated in FIG. 2.
[0028] In its upper part, collet chuck 7 is secured within (hollow
cylindrical) body 3 by a press fit and can be displaced axially
with respect to body 3 when the relatively high force of the press
fit is overcome.
[0029] Hollow cylindrical body 3 and collet chuck 7 are preferably
in a rotationally locked arrangement relative to one another, e.g.,
by means of suitable groove/channel guides running axially. Collet
chuck 7 is designed with tongues 8 that are spring mounted against
cylinder axis 4 and point downward. The spherical head 9 of a
pedicle screw 2 can be snapped from below with a spring action into
the chamber formed by these tongues.
[0030] A hole 10 with an inside thread 11 is provided in the upper
part of collet chuck 7 to accommodate a set screw 12 with a
hexagonal socket head 20 which can exert a force on a longitudinal
bar 1 inserted into the device, so the longitudinal bar 1 is locked
axially and rotationally with respect to body 3, as indicated in
FIG. 3. Collet chuck 7 is designed at its lower end such that screw
shaft 13 of pedicle screw 2 connected to spherical head 9 can be
locked at an angle .alpha. of -25.degree. to +25.degree. with
respect to axis 4.
[0031] At its lower end 24, body 3 has a conical inside surface 14
which becomes wider toward the lower end and can come into sliding
contact with a suitably designed conical outside surface 18 of the
free ends of tongues 8 of collet chuck 7. As soon as set screw 12
abuts against longitudinal bar 1 inserted into the device, collet
chuck 7 begins to push upward against body 3. This process is
illustrated in FIG. 2, where the left half of the FIG. shows the
condition before pushing collet chuck 7 upward, and the right half
shows the conical surfaces 14 and 18 slipping past one another as
collet chuck 7 is pushed upward with tongues 8. Tongues 8 are
designed with a spring action due to slot 22 being pushed toward
cylinder axis 4 such that hollow spherical cavity 19 is reduced in
size and head 9 of pedicle screw 2 inserted into it is gripped
securely. To optimize the locking of head 9, it is provided with a
structuring 15, preferably in the form of transverse grooves or
transverse ribs. Otherwise, pedicle screw 2 corresponds to known
screw designs and is expediently provided with a hexagonal socket
head 16.
[0032] Hollow spherical cavity 19 may in turn be provided with a
structuring 21, preferably in the form of transverse grooves or
transverse ribs. A combination of structuring 21 and structuring 15
is possible to further improve the fixation effect of head 9 in
hollow spherical cavity 19.
[0033] Hollow spherical cavity 19 is preferably designed with a
shape complementary to that of head 9 of pedicle screw 2 so the
head can be accommodated in the cavity.
[0034] The embodiment of the device shown in FIG. 4 illustrates the
use of a body 3, which is divided into a bottom part 52 and a top
part 53 across axis 4 in the middle of through hole 6, in
combination with an adjusting nut 26. The bottom part 52 of body 3
should be tall enough that longitudinal bar 1 is always in contact
with bottom part 52.
[0035] Collet chuck 71 differs from collet chuck 7 shown in FIG. 1
only in that the inside thread 11 on the upper end has been
replaced by an outside thread 27 for use by an adjusting nut 26.
When tightened, adjusting nut 26 presses on top part 53 of body 3,
which subsequently presses directly on longitudinal bar 1.
Longitudinal bar 1 is subsequently pressed against bottom part 52
of body 3, and then locks spherical head 9, as shown in FIG. 2.
[0036] The embodiment of the device shown in FIG. 5 differs from
the embodiment illustrated in FIG. 9 only in that a peg 55 prevents
collet chuck 72, which has been weakened by channel 54, from
collapsing when adjusting nut 26 is tightened. To prevent this peg
55 from falling out, it is advantageously provided with an outside
thread and screwed in.
[0037] The embodiment of the device shown in FIG. 6 differs from
the embodiment illustrated in FIG. 4 only in that:
[0038] a) collet chuck 73 has an inside thread 11 in addition to
outside thread 27, and
[0039] b) body 3 (which is one piece) and through hole 6 are
positioned with respect to through hole 17 so that only spherical
head 9 is locked when adjusting nut 26 is tightened. This permits
distraction or compression with a stable angular position.
Adjusting nut 26 presses on body 3, and the resulting bracing of
body 3 with collet chuck 73 ensures fixation of spherical head 9 of
pedicle screw 2 without locking longitudinal bar 1. Longitudinal
bar 1 is pressed separately with the help of set screw 12 against
the lower edge of through hole 6 of body 3. Therefore, body 3 is
further wedged with collet chuck 73, which leads to a greater
clamping effect on spherical head 9. Through hole 6 should be
positioned in body 3 so that longitudinal bar 1 also rests on the
lower edge of through hole 6 after tightening adjusting nut 26.
[0040] The embodiment of the device illustrated in FIG. 7 differs
from the device illustrated in FIGS. 1-3 only in the design of
locking screw 91 and the positioning of through hole 6 with respect
to through hole 17. Collet chuck 7 is provided with an inside
thread 11. A locking screw 91, which is screwed into inside thread
11, and a set screw 12, which is integrated into locking screw 91,
serve to lock spherical head 9 and longitudinal bar 1. Body 3,
which is designed in one piece by analogy with FIGS. 1-3, is
provided with a turning 94 at the top, accommodating the shoulder
93 of locking screw 91. Through hole 6 is positioned in body 3 with
respect to through hole 17 in collet chuck 7 in such a way that
only spherical head 9 is locked when locking screw 91 is tightened.
Longitudinal bar 1 is secured afterwards by means of set screw 12.
As long as this set screw 12 is screwed completely into locking
screw 91, and locking screw 91 has been screwed back to the extent
that longitudinal bar 1 touches the lower edge of through hole 6 in
body 3, spherical head 9 can be secured or removed. Furthermore,
collet chuck 7 is released again from the tightened state when
locking screw 91 is screwed back. To accommodate longitudinal bar
1, collet chuck 7 may be provided with a through hole 17 according
to FIG. 4, with a channel 54 that is open at the top according to
FIG. 9, or with a channel 42 which is open at the side according to
FIG. 8. In these latter two cases, either a two-piece design of
body 3 or a design according to FIGS. 11 and 12 is advantageous to
facilitate insertion of the longitudinal bar. However, with the
two-piece design, the two parts of body 3 must be designed so that
top part 53 presses directly on bottom part 52 and not on
longitudinal bar 1 even after bracing.
[0041] The embodiment of the device shown in FIG. 8 differs from
the embodiment illustrated in FIG. 4 only in that, in contrast with
collet chuck 71, collet chuck 74 has a channel 42 that is open at
the side instead of having a through hole 17 to accommodate
longitudinal bar 1, but slot 22 does not extend into this open
channel.
[0042] The embodiment of the device shown in FIG. 9 differs from
the embodiment illustrated in FIG. 4 only in that, in contrast with
collet chuck 71, collet chuck 72 has a channel 54 that is open at
the top instead of having a through hole 17 to accommodate
longitudinal bar 1, and slot 22 does not extend into this open
channel. To prevent collet chuck 72 from collapsing when adjusting
nut 26 is tightened, the thread should be designed so that
negligible radial forces occur in tightening. A sawtooth thread,
for example, would meet this requirement.
[0043] The embodiment of the device shown in FIG. 10 illustrates
the use of a collet chuck 75, which is provided with an inside
thread 11 instead of an outside thread 27, in contrast with collet
chuck 72 illustrated in FIGS. 5 and 9. A set screw 56 with an
outside thread 57 and a flange 58 serves as the clamping means.
When tightened, set screw 56 presses against longitudinal bar 1,
which in turn presses on bottom part 52 of body 3. This bracing of
bottom part 52 and collet chuck 75 locks spherical head 9 of
pedicle screw 2, as illustrated in FIG. 2. Top part 53 of body 3
prevents widening of collet chuck 75 when set screw 56 is
tightened. Top part 53 rests on shoulder 63.
[0044] The embodiment of the device shown in FIG. 11 differs from
the embodiment illustrated in FIG. 6 only in that collet chuck 76,
in contrast with collet chuck 73, has a channel 42 that is open at
the side instead of having a through hole 17, and slots 22 do not
extend into the channel.
[0045] According to FIG. 13, through hole 6 in body 3 is preferably
open at side 80 to permit unhindered insertion of longitudinal bar
1.
[0046] The embodiment of the device shown in FIG. 12 differs from
the embodiment illustrated in FIG. 11 only in that, in contrast
with collet chuck 76, collet chuck 77 has a channel 54 that is open
at the top to accommodate longitudinal bar 1. According to FIG. 14,
through hole 6 in body 3 is open toward top 81 for unhindered
insertion of longitudinal bar 1.
[0047] The embodiment of the device shown in FIG. 13 differs from
the embodiment illustrated in FIG. 11 only in that a through hole
80 which is open at the side is provided in body 3.
[0048] The embodiment of the device shown in FIG. 14 differs from
the embodiment illustrated in FIG. 12 only in that a through hole
81 which is open at the top is provided in body 3.
* * * * *