U.S. patent application number 11/128962 was filed with the patent office on 2006-11-30 for pedicle screw based vertebral body stabilization apparatus.
Invention is credited to Jeffery Thramann.
Application Number | 20060271048 11/128962 |
Document ID | / |
Family ID | 38694732 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060271048 |
Kind Code |
A1 |
Thramann; Jeffery |
November 30, 2006 |
Pedicle screw based vertebral body stabilization apparatus
Abstract
A pedicle screw stabilization device comprises a superior and
inferior pedicle screw anchor with a shaped memory alloy spacer
therebetween.
Inventors: |
Thramann; Jeffery;
(Longmont, CO) |
Correspondence
Address: |
HOLLAND & HART, LLP
P.O BOX 8749
DENVER
CO
80201
US
|
Family ID: |
38694732 |
Appl. No.: |
11/128962 |
Filed: |
May 12, 2005 |
Current U.S.
Class: |
606/255 ;
606/254; 606/263; 606/909; 606/911 |
Current CPC
Class: |
A61B 17/7022 20130101;
A61B 17/7011 20130101; A61B 2017/00867 20130101; A61B 17/7026
20130101; A61B 17/7031 20130101; A61B 17/7032 20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Claims
1. A pedicle screw based spinal stabilization device, comprising: a
superior pedicle screw; an inferior pedicle screw; and a spacer
coupled to the superior pedicle screw and inferior pedicle screw,
the spacer allows compression and expansion of the vertebral bodies
and comprises an elastic portion that dampens compression and
expansion of the spacer to provide a relatively gentle stop to
motion.
2. The device of claim 1, wherein the spacer is constructed from
shaped memory alloy.
3. The device of claim 1, wherein the elastic portion comprises an
accordion shape.
4. The device of claim 1, wherein the superior pedicle screw and
the inferior pedicle screw each comprise an anchor, wherein the
anchor includes a bone engaging surface and a top opposite the bone
engaging surface, a channel resides in the anchor extending from
the top towards the bone engaging surface, the channel being sized
to fit the spacer, and a setscrew is threaded into the channel to
lock the spacer in the channel.
5. The device of claim 1, wherein the superior pedicle screw and
inferior pedicle screw are separated by multiple vertebrae.
6. The device of claim 2, wherein the shaped memory alloy is
nickel-titanium.
7. The device of claim 2, wherein the shaped memory alloy has a
first shape and a second shape, the first shape providing a first
amount of support and the second shape providing a second amount of
support.
8. The device of claim 1, wherein the elastic portion spans the
entire spacer.
9. The device of claim 1 wherein, the elastic portion is located
substantially midway between the superior pedicle screw and the
inferior pedicle screw.
10. A pedicle screw based spinal stabilization device, comprising:
a superior pedicle screw; an inferior pedicle screw; and a spacer
coupled to the superior pedicle screw and inferior pedicle screw,
at least a portion of the spacer comprising shaped memory alloy
that allows expansion and compression of vertebral bodies.
11. The device of claim 10, wherein the portion provides motion
dampening in both a compression direction and a tension
direction.
12. The device of claim 11, wherein the portion has an accordion
shape.
13. The device of claim 10, wherein the portion comprises the
entire spacer.
14. The device of claim 10, wherein the portion comprises a
plurality of portions.
15. The device of claim 14, wherein the plurality of portions
comprises at least a first portion to dampen compressive motion and
at least a second portion to dampen expansive motion.
16. The device of claim 15, wherein the first portion and the
second portion are different.
17. The device of claim 1, further comprising a band coupled to the
vertebral bodies.
18. The device of claim 1, further comprising a band wherein the
band is coupled to the vertebral bodies through the superior
pedicle screw and the inferior pedicle screw.
19. The device of claim 18, wherein the band comprises shaped
memory alloys.
20. The device of claim 1, wherein the superior pedicle screw
carries a bone growth material.
21. The device of claim 20, wherein the inferior pedicle screw
carries the bone growth material.
22. The device of claim 1, wherein the superior pedicle screw
comprises at least one bone growth channel.
23. The device of claim 22, wherein the inferior pedicle screw
comprises at least one bone growth channel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to vertebral body
stabilization and support and, more particularly, to a pedicle
screw based system providing flex restrictions on vertebral
bodies.
BACKGROUND OF THE INVENTION
[0002] Surgical techniques to correct or address spinal problems
are turning more and more to non-fusion technologies. One type
technology involves spinous process stabilization. Spinous process
stabilization is further explained in U.S. patent application Ser.
No. 10/______ filed, May 12, 2005, titled SPINAL STABILIZATION,
which application is incorporated herein as if set out in full.
Another similar technology comprises using conventional pedicle
screws.
[0003] One conventional pedicle based stabilization system includes
a pedicle screw platform threaded into at least a superior and
inferior pedicle. Stabilizing cords a placed and spacers inserted
between sets of pedicle screws. Once everything is placed, the
cords are tightened.
[0004] Conventional pedicle based systems, such as the one
explained above, provide adequate support, however, any flex of the
system is abruptly stopped by either the cord or the spacer. Even
if the spacer provides for some flex, the cord provides an abrupt
stop in the opposite direction.
[0005] Instead of the screw, spacer cord based systems, some
pedicle screw stabilization devices provide tracks to allow some
movement. For example, the spacer may have elongated slots or
tracks on the superior and/or inferior end the spacer to move
relative to the pedicle screw, which allows for some relative
movement between the superior and inferior vertebrae. The track
provides more flex than the spacer/cord systems, but provides
abrupt stops in both directions.
[0006] Thus, it would be desirous to develop a pedicle screw based
spinal stabilization apparatus that provide a dampened stop.
SUMMARY OF THE INVENTION
[0007] To attain the advantages and in accordance with the purpose
of the invention, as embodied and broadly described herein, a
pedicle screw based spinal stabilization apparatus is provided. The
apparatus uses materials specifically designed to dampen the
movement to provide a gentle stop. The apparatus comprises a
superior pedicle screw and an inferior pedicle screw. A spacer
coupled to the superior pedicle screw and inferior pedicle screw
allows compression and expansion of the vertebral bodies. At least
a part of the spacer comprises elastic portion that dampens
compression and expansion of the spacer to provide a relatively
gentle stop to motion
[0008] The foregoing and other features, utilities and advantages
of the invention will be apparent from the following more
particular description of a preferred embodiment of the invention
as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0009] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the present invention, and together with the description, serve to
explain the principles thereof. Like items in the drawings are
referred to using the same numerical reference.
[0010] FIG. 1 shows a superior view of a vertebral body;
[0011] FIG. 2 shows an elevation view of the vertebral body of FIG.
1;
[0012] FIG. 3 shows a superior vertebral body and an inferior
vertebral body with a pedicle screw based spacer consistent with an
embodiment of the present invention;
[0013] FIG. 4 shows a pedicle screw and anchor consistent with an
embodiment of the present invention; and
[0014] FIG. 5 shows a possible shape of a portion of the spacer of
FIG. 3.
DETAILED DESCRIPTION
[0015] The present invention will now be described with reference
to FIGS. 1 to 5. Referring first to FIGS. 1 and 2, a vertebral body
100 is shown for reference. FIG. 1 shows a superior view of a
vertebral body 100 (i.e., looking down the spinal column). The
vertebral body 100 comprises, among other parts, the pedicles 102,
the facets 104, the lamina 106, and the spinous process 108. FIG. 2
shows a side elevation view of vertebral body 100 with a pedicle
102, the facet 104, lamina 106, and spinal process 106.
[0016] FIG. 3 shows a side elevation view of a superior vertebral
body 302 and an inferior vertebral body 304 (not shown to scale and
slightly exploded for ease of reference) with a pedicle screw
stabilization device 300. For reference, vertebral bodies 302 and
304 comprise the superior pedicle 306 and the inferior pedicle 308.
An intervertebral disk 310 typically exists in intervertebral space
312, but may be removed and/or replace by artificial discs, grafts,
or the like.
[0017] Device 300 comprises a superior pedicle screw 320 and an
inferior pedicle screw 322. A spacer 324 is coupled to the pedicle
screws. Spacer 324 includes a elastic/damper portion 326 that
allows some expansion and contraction between the vertebral bodies.
While shown as a single piece, spacer 324 could be multiple pieces.
When multiple pieces are provided, parts may provide dampening in
one or both directions as desired. Portion 326 is shown centrally
located on spacer 324, but could be located elsewhere and/or be the
entire spacer 324. In either direction, the resistance to the
motion would increase to provide a relatively gentle stop to the
motion instead of the abrupt stop associated with conventional
stabilization devices. Spacer 324 could be made our of polymers or
other biocompatible material, but it is preferred to construct
spacer 324 from shaped memory alloys because of their bone like,
elastic qualities at conventional body temperatures. Spacer 324
could be attached to pedicle screws 320 and 322 in any conventional
manner. Moreover, while show as a single level stabilization,
device 300 could be used for multiple level stabilization.
[0018] Optionally, a band 330 can be used to further inhibit flex
of the spine. Band 330 can be wrapped about superior pedicle screw
320 and inferior pedicle screw 322. Alternatively, band 330 can be
wrapped about other parts of the vertebral body. For example, band
330 could be wrapped about the spinous process of superior
vertebral body 302 and the spinous process of the inferior
vertebral body 304 as shown in phantom. Band 330 could be any
conventional biocompatible material, such as, for example, metals,
shaped memory alloys, polymers, PEEK, or the like. Band 330 could
be a circular, elliptical, or other shape band or attach similar to
a "C" clamp or the like such that band 330 only has a single
side.
[0019] FIG. 4 shows a top and side view of pedicle screw 400 and
anchor 402 to which a spacer 324 may be attached. Anchor 402 has a
bone engaging surface 404 and a top 406 opposite the bone engaging
404. A bore 405 extends from the top 406 to the bone engaging
surface 404. A channel 408 extends from the top 406 towards bone
engaging surface 404. Channel 408 is designed to fit spacer 324.
Channel 408 may be open on two sides of anchor 402, similar to a
spinal rod system, or open on a single side of anchor 402 (as
shown). A setscrew 410 having first threads 412 it threaded onto
corresponding threads 414 in bore 405 to couple spacer 324 to
pedicle screw 400 and anchor 402. To facilitate the pedicle screws
being permanently threaded into pedicles, thread 450 may be coated
with bone growth materials 452, as those materials are
conventionally understood in the art. Moreover, the pedicle screws
may include bone growth channels 454 to promote bone growth through
the pedicle screws. Channels 454 may be coated and/or packed with
bone growth material. As one of skill in the art would now
recognize, the pedicle screws may be similar to bone growth cages.
The bone growth should prompt fusing the pedicle screw to the
bone.
[0020] As mentioned above, spacer 324 and/or portion 326 could be
constructed out of a number of materials to provide elastic
movement in multiple directions. FIG. 5 shows an optional and
possible construction of spacer 324 and/or portion 326 to
facilitate expansion and compression of spacer 324. FIG. 5 shows an
accordion shape section 500. Section 500 can expand in direction A
on application of tension. Section 500 can compress in direction B
on application of compression. Using an accordion shape, as section
500 becomes more elongated and/or more compact, the force resisting
movement increases to provide a dampening effect. The dampening
effect provides a more gentle stop than conventional pedicle screw
based stabilization devices.
[0021] While the invention has been particularly shown and
described with reference to an embodiment thereof, it will be
understood by those skilled in the art that various other changes
in the form and details may be made without departing from the
spirit and scope of the invention.
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