U.S. patent application number 14/869598 was filed with the patent office on 2016-01-21 for expandable trial with telescopic stabilizers.
The applicant listed for this patent is OUROBOROS MEDICAL, INC.. Invention is credited to Praveen Gopal Rao, John To.
Application Number | 20160015530 14/869598 |
Document ID | / |
Family ID | 52626316 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160015530 |
Kind Code |
A1 |
To; John ; et al. |
January 21, 2016 |
EXPANDABLE TRIAL WITH TELESCOPIC STABILIZERS
Abstract
Systems and methods for distracting an intervertebral disc space
are provided. The systems use an expandable trial with telescopic
stabilizers. The systems and methods of distracting an
intervertebral space are provided in a manner that addresses the
problem of subsidence. The method includes inserting the trial into
the intervertebral space in a collapsed state and, once inserted,
the trial is then used for distracting the intervertebral space
using an expansion that includes a first stage and a second stage.
The first stage includes expanding the trial laterally toward the
peripheral zones of the top vertebral plate and the bottom
vertebral plate, and the second stage includes expanding the trial
vertically to distract the intervertebral space.
Inventors: |
To; John; (Newark, CA)
; Rao; Praveen Gopal; (Newark, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OUROBOROS MEDICAL, INC. |
Fremont |
CA |
US |
|
|
Family ID: |
52626316 |
Appl. No.: |
14/869598 |
Filed: |
September 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14164158 |
Jan 25, 2014 |
9186259 |
|
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14869598 |
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61875688 |
Sep 9, 2013 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61F 2/4455 20130101;
A61F 2/4425 20130101; A61F 2/4684 20130101; A61F 2002/30556
20130101; A61B 2017/0256 20130101; A61F 2002/30154 20130101; A61F
2002/30179 20130101; A61F 2/442 20130101; A61F 2002/30563 20130101;
A61F 2002/30014 20130101; A61F 2/4611 20130101; A61F 2002/3055
20130101; A61B 17/025 20130101; A61F 2002/30565 20130101; A61F
2002/30266 20130101; A61F 2002/30579 20130101; A61F 2002/30545
20130101 |
International
Class: |
A61F 2/46 20060101
A61F002/46; A61B 17/02 20060101 A61B017/02; A61F 2/44 20060101
A61F002/44 |
Claims
1. An expandable trial for an intervertebral space, including an
expandable shell having a proximal region with an end, a
mid-region, a distal region with an end, and a lumen; the proximal
region having a slider-guide; the distal region having an
expandable head with a top subhead and a bottom subhead between
which a telescopic stabilizer is operably attached to (i) slidably
translate and (ii) stabilize and/or align the relationship between
the top subhead and the bottom subhead during operation of the
expandable shell; wherein, the shell has a collapsed state and an
expanded state; wherein, the head has a proximal portion having an
end; a distal portion having an end; and, a central shell axis of
the expanded state; the head configured for expanding in vivo
following placement of the trial in the intervertebral space
through an annular opening.
2. The trial of claim 1, wherein the head has a transverse
cross-section in the collapsed state having a maximum dimension
ranging from 5 mm to 18 mm for placing the frame in an
intervertebral space through an annular opening for expansion in
the intervertebral space; and, a transverse cross-section in the
expanded state having a maximum dimension ranging from 6.5 to 28 mm
in the intervertebral space.
3. The trial of claim 1, wherein the shell is a single-unit formed
from a single body of material, and the slider-guide and head are
monolithically integral.
4. The trial of claim 1, wherein the proximal end of a shim is
configured to receive an axial proximal-to-distal force through an
actuation bar for an axial translation of the shim into the shell,
the actuation bar having a proximal portion with a proximal end, a
distal portion with a distal end, and configured to transfer the
axial proximal-to-distal force to the shim through the
slider-guide.
5. The trial of claim 1, wherein the trial has 4 telescopic
stabilizers.
6. A system for distracting an intervertebral space, the system
comprising an expandable shell having a proximal region with an
end, a mid-region, a distal region with an end, and a lumen; the
proximal region having a slider-guide; the distal region having an
expandable head with a top subhead and a bottom subhead between
which a telescopic stabilizer is operably attached to (i) slidably
translate and (ii) stabilize and/or align the relationship between
the top subhead and the bottom subhead during operation of the
expandable shell; wherein, the shell has a collapsed state and an
expanded state; and, a vertical expansion component that induces a
vertical expansion of the head in an intervertebral space having a
top vertebral endplate, a bottom vertebral endplate, and an
annulus; wherein, the head has a proximal portion having an end; a
distal portion having an end; and, a central shell axis of the
expanded state; the head configured for expanding in vivo following
placement of the trial in the intervertebral space through an
annular opening.
7. The system of claim 6, further comprising a retractable
retention plunger configured for retaining the trial in the
collapsed state and releasing the trial for expansion into the
expanded state.
8. The system of claim 6, further comprising an actuation component
having a proximal end and a distal end that is operably connected
to the vertical expansion component, the actuation component
configured to receive an axial proximal-to-distal force from an
actuation screw that is operably attached to the proximal end of
the actuation bar and transfers the force to the vertical expansion
component through the distal end of the actuation bar.
9. The system of claim 6, wherein the head has a transverse
cross-section in the collapsed state having a maximum dimension
ranging from 5 mm to 18 mm for placing the frame in an
intervertebral space through an annular opening for expansion in
the intervertebral space; and, a transverse cross-section in the
expanded state having a maximum dimension ranging from 6.5 to 28 mm
in the intervertebral space.
10. The system of claim 6, wherein the vertical expansion component
includes vertical wedge configured to vertically-expand the
trial.
11. The system of claim 6, wherein the vertical expansion component
includes a vertical-expansion wedge with angle .theta..sub.V
ranging from 30.degree. to 50.degree..
12. The system of claim 6, wherein the vertical expansion component
includes a vertical-expansion wedge with angle .theta..sub.V
ranging from 10.degree. to 90.degree..
13. The system of claim 6, wherein the shell is a single-unit
formed from a single body of material, and the slider-guide and
head are monolithically integral.
14. The system of claim 6, wherein the trial has at least 2
telescopic stabilizers.
15. A method of distracting an intervertebral space using the trial
of claim 1, the method comprising: creating a point of entry into
an intervertebral disc, the intervertebral disc having a nucleus
pulposus surrounded by an annulus fibrosis, and the point of entry
having the maximum lateral dimension created through the annulus
fibrosis; removing the nucleus pulposus from within the
intervertebral disc through the point of entry, leaving the
intervertebral space for expansion of the head of the trial of
claim 1 within the annulus fibrosis, the intervertebral space
having the top vertebral plate and the bottom vertebral plate;
inserting the head in the collapsed state through the point of
entry into the intervertebral space; and, distracting the
intervertebral space, the distracting including slidably
translating the telescopic stabilizer in the expansion of the head
to the expanded state.
16. The method of claim 15, further comprising retaining the trial
with a retractable retention plunger and retracting the plunger to
expand the trial.
17. The method of claim 15, wherein the lateral dimension of the
point of entry ranges from about 5 mm to about 18 mm.
18. The method of claim 15, wherein the distracting includes
selecting an amount of vertical expansion.
19. The method of claim 15, wherein the distracting includes
selecting a vertical expansion component that includes a
vertical-expansion wedge with angle .theta..sub.V ranging from
30.degree. to 50.degree..
20. The method of claim 18, wherein the distracting includes
selecting a vertical expansion component that includes a
vertical-expansion wedge with angle .theta..sub.V ranging from
10.degree. to 90.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/164,158, filed Jan. 25, 2014, which claims the benefit of
U.S. Application No. 61/875,688, filed Sep. 9, 2013, each of which
is hereby incorporated herein by reference in its entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The teachings herein are directed to systems and methods for
distracting an intervertebral disc space.
[0004] 2. Description of the Related Art
[0005] Bone grafts are used in spinal fusion, for example, which is
a technique used to stabilize the spinal bones, or vertebrae, and a
goal is to create a solid bridge of bone between two or more
vertebrae. The fusion process includes "arthrodesis", which can be
thought of as the mending or welding together of two bones in a
spinal joint space, much like a broken arm or leg healing in a
cast. Spinal fusion may be recommended for a variety of conditions
that might include, for example, a spondylolisthesis, a
degenerative disc disease, a recurrent disc herniation, or perhaps
to correct a prior surgery.
[0006] Bone graft material is introduced for fusion and a fusion
cage can be inserted to help support the disc space during the
fusion process. In fact, fusion cages are frequently used in such
procedures to support and stabilize the disc space until bone graft
unites the bone of the opposing vertebral endplates in the disc
space. A transforaminal lumbar interbody fusion (TLIF), for
example, involves placement of posterior instrumentation (screws
and rods) into the spine, and the fusion cage loaded with bone
graft can be inserted into the disc space. Bone graft material can
be pre-packed in the disc space or packed after the cage is
inserted. TLIF can be used to facilitate stability in the front and
back parts of the lumbar spine promoting interbody fusion in the
anterior portion of the spine. Fusion in this region can be
beneficial, because the anterior interbody space includes an
increased area for bone to heal, as well as to handle increased
forces that are distributed through this area.
[0007] Unfortunately, therein lies a problem solved by the
teachings provided herein. Currently available systems can be
problematic in that the methods of introducing the fusion cage and
bone graft material creates "subsidence" of the cage into the
adjoining vertebrae, resulting in a narrowing of the formerly
distracted disc space. This is because the cage is inserted near
the middle of the endplate area which is softer than the areas at
or near the peripheral zone of the endplate, and when it distracts,
the cage actually sinks into the endplate creating the subsidence
problem. The problem remains with state-of-the-art distraction
instruments, such as the Medtronic SCISSOR JACK, paddle trials, or
oversized trial shims (metallic wedges). Each of these
state-of-the-art procedures introduce the distraction means
narrowly (no wider than width of annulotomy) and then distract the
intervertebral space with a narrow foot print that ranges from
about 8 mm to about 11 mm wide.
[0008] Accordingly, and for at least the above reasons, those of
skill in the art will appreciate distraction systems that
facilitate an improved placement of distraction stresses across the
verterbral endplates that define the distracted intervertebral
space. Such systems are provided herein, the systems configured to
(i) effectively and selectively place the distraction stresses in
areas that include areas at or near the peripheral zones of the
vertebral endplates to reduce the incidence of subsidence; (ii)
reduce or eliminate the problem of failures resulting from
subsidence; (iii) have a small maximum dimension of the trial in a
collapsed state for a low-profile insertion into the annulus in a
minimally-invasive manner, whether using only a unilateral approach
or a bilateral approach; (iv) laterally expand within the
intervertebral space to facilitate the effective and selective
distribution of distraction stresses on the vertebral endplates;
(v) vertically expand for distraction of the intervertebral space;
(vi) provide an expansion in the intervertebral space without
contracting the system in length to maintain a large footprint
during the distraction process, distributing load over a larger
area, including areas at or near the peripheral zones of the
vertebral endplates; and, (vii) serve as a measuring device for the
size of the intervebral space to facilitate selection of the size
of the cage.
SUMMARY
[0009] The teachings herein are directed to systems and methods for
distracting an intervertebral disc space using a staged,
bilaterally expandable trial. Generally, the teachings are directed
to a method of distracting an intervertebral space in a manner that
addresses the problem of subsidence. The teachings include
obtaining a bilaterally expandable trial that is configured to
first expand laterally and then expand vertically to distract an
intervertebral space having a top vertebral plate and a bottom
vertebral plate. The trial is then inserted into the intervertebral
space in a collapsed state. Once inserted, the trial then used for
distracting the intervertebral space using a staged, bilateral
expansion, the distracting including a first stage and a second
stage. The first stage includes expanding the trial laterally
toward the peripheral zones of the top vertebral plate and the
bottom vertebral plate, and the second stage includes expanding the
trial vertically to distract the intervertebral space.
[0010] As such, a staged, bilaterally-expandable trial for an
intervertebral space is provided. In some embodiments, the trial
comprises a bilaterally-expandable shell having a proximal region
with an end, a mid-region, a distal region with an end, and a
lumen. The proximal region can have a slider-guide, and the distal
region can have a bilaterally-expandable head with 4 subheads that
include a first top beam, a second top beam, a first bottom beam,
and a second bottom beam. The mid-region can have 4 flex rods that
include a first top flex rod, a second top flex rod, a first bottom
flex rod, and a second bottom flex rod, each of which operably
attaches the slider-guide to it's respective subhead.
[0011] One or more beam stabilizers can be included stabilize
and/or align the subheads during operation of the device. A beam
stabilizer, for example, can slidably translate, such that it is
telescopic with respect to one or both subheads between which it is
operably attached to stabilize and/or align the relationship
between the subheads during operation of the device. In some
embodiments, the beams can be stabilized with translatable,
telescopic linear guides, such that the linear guide can telescope
within itself. For example, the first top beam can be operably
connected to the second top beam with a top telescopic beam
stabilizer, the first top beam can be operably connected to the
second top beam with a top telescopic beam stabilizer, the first
top beam can be operably connected to the first bottom beam with a
first side telescopic beam stabilizer, the second top beam can be
operably connected to the second bottom beam with a second side
telescopic beam stabilizer, and the first bottom beam can be
operably connected to the second bottom beam with a bottom
telescopic beam stabilizer. The beam stabilizer, or at least a
portion thereof, can be fixably attached, or monolithically
integral to, one or both beams between which it is operably
connected or positioned in either a fixed or translatable
configuration in the trial.
[0012] The trial can be expanded first laterally, and then
vertically, using any means known to one of skill. For example, the
trial can also comprise a shim having a proximal region with an
end; a mid-region; a distal region with an end; a central axis; a
top surface with a first top-lateral surface and a second
top-lateral surface; a bottom surface with a first bottom-lateral
surface and a second bottom-lateral surface; a first side surface
with a first top-side surface and a first bottom-side surface; and,
a second side surface with a second top-side surface and a second
bottom-side surface. The shim can be configured for a
proximal-to-distal axial translation in the lumen of the shell that
induces a lateral force on the 4 subheads followed by a vertical
force on the 4 subheads for a staged, bilateral expansion in vivo
that includes a lateral expansion of the head followed by a
vertical expansion of the head in an intervertebral space having a
top vertebral endplate, a bottom vertebral endplate, and an
annulus.
[0013] The head of the trial can be configured with a proximal
portion having an end; a distal portion having an end; and, a
central shell axis of the expanded state; the head adapted for
slidably-engaging with the shim in vivo following placement of the
trial in the intervertebral space through the annular opening, the
slidably-engaging including axially-translating the shim in the
lumen of the shell from the proximal end of the lumen toward the
distal end of the lumen in vivo; the translating including keeping
the central shim axis at least substantially coincident with the
central shell axis during the translating.
[0014] The teachings are also directed to systems that include
means for applying an axial proximal-to-distal force on a shim that
expands the trial. In some embodiments, the proximal end of the
shim can be configured to receive the axial proximal-to-distal
force through an actuation bar for the axial translation, the
actuation bar having a proximal portion with a proximal end, a
distal portion with a distal end, and configured to transfer the
axial proximal-to-distal force to the shim through the
slider-guide.
[0015] The systems can include an actuation means operably attached
to the proximal end of the actuation bar to transfer the axial
proximal-to-distal force to the shim through the distal end of the
actuation bar. In some embodiments, the actuation bar receives the
axial proximal-to-distal force from an actuation screw that can be
operably attached to the proximal end of the actuation bar to
transfer the force to the shim through the distal end of the
actuation bar. The systems can further comprise a retractable
retention plunger configured for retaining the trial in the
collapsed state and releasing the trial for expansion into the
expanded state.
[0016] The head of the trial can have a collapsed dimension that
facilitates insertion to the intervertebral space and an expanded
dimension that facilitates the desired lateral expansion and
vertical expansion in the intervertebral space. In some
embodiments, the head of the trial can have a collapsed state with
a transverse cross-section having a maximum dimension ranging from
5 mm to 18 mm for placing the frame in an intervertebral space
through an annular opening for expansion in the intervertebral
space. And, in some embodiments, the head of the trial can have an
expanded state with a transverse cross-section having a maximum
dimension ranging from 6.5 mm to 28 mm, 7.5 mm to 28 mm, 8.5 mm to
28 mm, 6.5 mm to 27 mm, 6.5 mm to 25 mm, 6.5 mm to 23 mm, 6.5 mm to
21 mm, 6.5 mm to 19 mm, 6.5 mm to 18 mm, or any range therein in
increments of 1 mm, in the intervertebral space. In some
embodiments, the shim can have a transverse cross-section with a
maximum dimension ranging from 5 mm to 18 mm, 6 mm to 18 mm, 7 mm
to 18 mm, 5 mm to 15 mm, 5 mm to 16 mm, 5 mm to 17 mm, or any range
therein in increments of 1 mm, for translating the shim in the
lumen of the shell.
[0017] In some embodiments, the shim can have a horizontal wedge
configured to laterally-expand the trial, and a vertical wedge
configured to vertically-expand the trial. In some embodiments, the
shim can have a top wedge configured to laterally-expand the first
top beam away from the second top beam, a bottom wedge configured
to laterally-expand the first bottom beam away from the second
bottom beam, a first side wedge configured to vertically-expand the
first top beam away from the first bottom beam, and a second side
wedge configured to vertically-expand the second top beam away from
the second bottom beam. In some embodiments, the proximal portion
of the first top beam and the proximal portion of the second top
beam can be configured to complement the top wedge at the onset of
the lateral expansion during the proximal-to-distal axial
translation; and, the proximal portion of the first bottom beam and
the proximal portion of the second bottom beam can be configured to
complement the bottom wedge at the onset of the lateral expansion
during the proximal-to-distal axial translation. In some
embodiments, the distance, D.sub.STAGING, between the onset of the
lateral expansion and the onset of the vertical translation can
range from 2 mm to 10 mm.
[0018] In some embodiments, the proximal portion of the first top
beam and the proximal portion of the first bottom beam can be
configured to complement the first side wedge during the
proximal-to-distal axial translation for the vertical expansion;
and, the proximal portion of the second top beam and the proximal
portion of the second bottom beam can be configured to complement
the second side wedge during the proximal-to-distal axial
translation for the vertical expansion.
[0019] In some embodiments, the first top beam can include a
proximal portion having an end, a distal portion having an end, and
a central axis; the first top beam configured for contacting a
first top chamfer of the shim in the expanded state, the central
axis of the first top beam at least substantially on (i) a top
plane containing the central axis of the first top beam and the
central axis of a second top beam and (ii) a first side plane
containing the central axis of the first top beam and the central
axis of a first bottom beam. Likewise, the second top beam can
include a proximal portion having an end, a distal portion having
an end, and a central axis; the second top beam configured for
contacting a second top chamfer of the shim in the expanded state,
the central axis of the second top beam at least substantially on
(i) the top plane and (ii) a second side plane containing the
central axis of the second top beam and the central axis of a
second bottom beam. Likewise, the first bottom beam can include a
proximal portion having an end, a distal portion having an end, and
a central axis; the first bottom beam configured for contacting a
first bottom chamfer of the shim in the expanded state, the central
axis of the first bottom beam at least substantially on (i) a
bottom plane containing the central axis of the first bottom beam
and the central axis of a second top beam and (ii) the first side
plane. Moreover, the second bottom beam can include a proximal
portion having an end, a distal portion having an end, and a
central axis; the second bottom beam configured for contacting a
second bottom chamfer of the shim in the expanded state, the
central axis of the second bottom beam being at least substantially
on (i) the bottom plane and (ii) a second side plane containing the
central axis of the second bottom beam and the second top beam.
[0020] In some embodiments, the first top beam can include a
proximal portion having an end, a distal portion having an end, and
a central axis; the first top beam configured for contacting a
first top-lateral surface of the shim and a first top-side surface
of the shim in the expanded state, the central axis of the first
top beam at least substantially on (i) a top plane containing the
central axis of the first top beam and the central axis of a second
top beam and (ii) a first side plane containing the central axis of
the first top beam and the central axis of a first bottom beam.
Likewise, the second top beam can include a proximal portion having
an end, a distal portion having an end, and a central axis; the
second top beam configured for contacting the second top-lateral
surface of the shim and the second top-side surface of the shim in
the expanded state, the central axis of the second top beam at
least substantially on (i) the top plane and (ii) a second side
plane containing the central axis of the second top beam and the
central axis of a second bottom beam. Likewise, the first bottom
beam can include a proximal portion having an end, a distal portion
having an end, and a central axis; the first bottom beam configured
for contacting the first bottom-lateral surface of the shim and the
first bottom-side surface of the shim in the expanded state, the
central axis of the first bottom beam at least substantially on (i)
a bottom plane containing the central axis of the first bottom beam
and the central axis of a second top beam and (ii) the first side
plane. Moreover, the second bottom beam can include a proximal
portion having an end, a distal portion having an end, and a
central axis; the second bottom beam configured for contacting the
second bottom-lateral surface of the shim and the second
bottom-side surface of the shim in the expanded state, the central
axis of the second bottom beam being at least substantially on (i)
the bottom plane and (ii) a second side plane containing the
central axis of the second bottom beam and the second top beam.
[0021] In some embodiments, the shim can comprise a
lateral-expansion wedge with angle .theta..sub.L ranging from
10.degree. to 30.degree. and a vertical-expansion wedge with angle
.theta..sub.V ranging from 30.degree. to 50.degree., the apex of
the lateral-expansion wedge and the apex of the vertical-expansion
wedge each at least substantially on a single plane that is
orthogonal to the central axis of the shim, and the ratio of
.theta..sub.V:.theta..sub.L ranges from 1:1.25 to 1:4 to stage the
bilateral expansion of the head.
[0022] In some embodiments, the shim can comprise a
lateral-expansion wedge with angle .theta..sub.L ranging from
10.degree. to 90.degree. and a vertical-expansion wedge with angle
.theta..sub.V ranging from 10.degree. to 90.degree., the apex of
the lateral-expansion wedge on a first plane and the apex of the
vertical expansion wedge on a second plane, both the first plane
and the second plane being orthogonal to the central axis of the
shim and separated on the central axis at a distance ranging from 2
mm to 10 mm to stage the bilateral expansion of the head.
[0023] The shell can be formed using any method of construction
known to one of skill, for example, multi-component or single unit.
In some embodiments, the shell can be a single-unit formed from a
single body of material, and the slider-guide, head, and flex rods
can be monolithically integral.
[0024] Accordingly, the teachings include a method of distracting
an intervertebral space using the trials taught herein. In some
embodiments, the method can comprise creating a point of entry into
an intervertebral disc, the intervertebral disc having a nucleus
pulposus surrounded by an annulus fibrosis, and the point of entry
having the maximum lateral dimension created through the annulus
fibrosis. The methods can include removing the nucleus pulposus
from within the intervertebral disc through the point of entry,
leaving the intervertebral space for expansion of the head of the
trial within the annulus fibrosis, the intervertebral space having
the top vertebral plate and the bottom vertebral plate. The methods
can include inserting the head in the collapsed state through the
point of entry into the intervertebral space; and, distracting the
intervertebral space using a staged, bilateral expansion that
includes a first stage and a second stage. The distracting can
include a first stage and a second stage, the first stage including
expanding the head laterally toward the peripheral zones of the top
vertebral plate and the bottom vertebral plate; and, the second
stage including expanding the head vertically to distract the
intervertebral space, the pressure for the expansion occurring
preferably, and at least primarily, at or near the peripheral zones
of the top vertebral plate and the bottom vertebral plate. In some
embodiments, the lateral dimension of the point of entry ranges
from about 5 mm to 18 mm, 6 mm to 18 mm, 7 mm to 18 mm, 5 mm to 15
mm, 5 mm to 16 mm, 5 mm to 17 mm, or any range therein in
increments of 1 mm.
[0025] In some embodiments, the distracting includes selecting an
amount of lateral expansion independent of an amount of vertical
expansion. And, in some embodiments, the distracting includes
measuring the amount of lateral expansion independent of the amount
of vertical expansion.
[0026] In some embodiments, the distracting includes as a first
stage of lateral expansion, inserting a top wedge into the head
between the first top beam and the second top beam, the top wedge
composing a portion of the shim and configured to laterally-expand
the first top beam away from the second top beam; and, inserting a
bottom wedge into the head between the first bottom beam and the
second bottom beam, the bottom wedge configured to laterally-expand
the first bottom beam away from the second bottom beam. And, as a
second stage of expansion, inserting a first side wedge into the
head between the first top beam and the first bottom beam, the
first side wedge configured to laterally-expand the first top beam
away from the first bottom beam; and, inserting a second side wedge
into the head between the second top beam and the second bottom
beam, the second side wedge configured to laterally-expand the
second top beam away from the second bottom beam.
[0027] In some embodiments, the distracting includes selecting a
shim having a lateral-expansion wedge with angle .theta..sub.L
ranging from 10.degree. to 30.degree. and a vertical-expansion
wedge with angle .theta..sub.V ranging from 30.degree. to
50.degree., the apex of the lateral-expansion wedge and the apex of
the vertical-expansion wedge each at least substantially on a
single plane that is orthogonal to the central axis of the shim,
and the ratio of .theta..sub.V:.theta..sub.L ranges from 1:1.25 to
1:4 to stage the bilateral expansion of the head.
[0028] In some embodiments, the distracting includes selecting a
shim having a lateral-expansion wedge with angle .theta..sub.L
ranging from 10.degree. to 90.degree. and a vertical-expansion
wedge with angle .theta..sub.V ranging from 10.degree. to
90.degree., the apex of the lateral-expansion wedge on a first
plane and the apex of the vertical expansion wedge on a second
plane, both the first plane and the second plane being orthogonal
to the central axis of the shim and separated on the central axis
at a distance ranging from 2 mm to 10 mm to stage the bilateral
expansion of the head.
BRIEF DESCRIPTION OF THE FIGURES
[0029] FIGS. 1A and 1B illustrate a sketch of an endplate of a
vertebral body and a representative photograph of an intervertebral
space using a cadaver intervertebral body and disc, according to
some embodiments.
[0030] FIG. 2 illustrates a process of using a staged,
bilaterally-expandable trial for distracting an intervertebral
space, according to some embodiments.
[0031] FIGS. 3A-3D illustrate a staged, bilaterally-expandable
trial, according to some embodiments.
[0032] FIGS. 4A-4D illustrate a shim for the staged, bilaterally
expanding trial, according to some embodiments.
[0033] FIG. 5 illustrates the concept of the staged, bilateral
expansion of the trial, according to some embodiments.
[0034] FIG. 6 illustrates a trial system for a staged, bilateral
expansion of the trial in an intervertebral space, according to
some embodiments.
[0035] FIGS. 7A and 7B illustrate a trial system with an expansion
gauge and a retractable retention plunger for retaining the trial
prior to a staged, bilateral expansion of the trial in an
intervertebral space, according to some embodiments.
[0036] FIGS. 8A-8D illustrate a staged, bilaterally-expandable
trial with beam stabilizers that telescope within themselves,
according to some embodiments.
[0037] FIGS. 9A-9E illustrate a staged, bilaterally-expandable
trial with beam stabilizers that telescope with one or both
subheads having a counter-bore, according to some embodiments.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Systems and methods for distracting an intervertebral disc
space using a staged, bilaterally expandable trial are provided.
Generally speaking, a system for distracting an intervertebral disc
space using a staged, bilaterally expandable trial is provided.
Generally, the teachings are directed to a method of distracting an
intervertebral space in a manner that addresses the problem of
subsidence by selectively applying distraction forces to stronger
portions of the vertebral endplates of the intervertebral space. It
should be appreciated that the term "trial" can be used
interchangeably with the term "distractor" in many embodiments.
[0039] FIGS. 1A and 1B illustrate a sketch of an endplate of a
vertebral body and a representative photograph of an intervertebral
space using a cadaver intervertebral body and disc, according to
some embodiments. This illustration provides a reference to discuss
the state-of-the-art methods of introducing the fusion cage and
bone graft material which create "subsidence" of the cage into the
adjoining vertebrae, resulting in a narrowing of the formerly
distracted disc space. As shown in FIG. 1A, the vertebral body 100
has an endplate 105 with a mid-region 115 and a peripheral zone
125. The problem occurs because the cage is typically inserted at
or near the mid-region 115 which is softer than the areas at or
near the peripheral zone 125 of the endplate 105, and when it
distracts, the cage actually sinks into the endplate 105 creating
the subsidence problem. The problem remains with state-of-the-art
distraction instruments, such as the Medtronic SCISSOR JACK, paddle
trials, or oversized trial shims (metallic wedges). Each of these
state-of-the-art procedures introduce the distraction means
narrowly (no wider than width of annulotomy) and then distract the
intervertebral space with a narrow foot print that ranges, for
example, from about 8 mm to about 11 mm wide. FIG. 1B illustrates a
cadaver intervertebral body 150, and the annulus 153 that surrounds
the intervertebral space 155 that receives the trial.
[0040] In some embodiments, the phrase "at or near the peripheral
zone" of a vertebral endplate can be interpreted as meaning "at
least substantially away from the central portion of the area of
the vertebral endplate. A distraction pressure can be applied, for
example, at least substantially away from the central portion where
greater than 30%, greater than 35%, greater than 40%, greater than
45%, greater than 50%, greater than 55%, greater than 60%, greater
than 65%, greater than 70%, greater than 75%, greater than 80%,
greater than 85%, greater than 90%, greater than 95%, or more of
the surface area of a pair of subheads that is facing, or in some
embodiments in contact or potential contact with, their respective
endplate outside of the central portion. In some embodiments, the
"central portion" can be defined as a scaled-down area on the
surface of the endplate, and thus sharing a plane with the surface
of the endplate, sharing a center-point on the plane, and sharing
the same general shape as the total area of the endplate, albeit
scaled-down. As such, an overlay of the central portion that is
placed on the total area with the same orientation, and placed
carefully such that the center-point of the central portion is
shared/concentric with the center-point of the total area, leaves a
"remaining area" or "remainder" around the periphery of the total
area that can be defined, for example, as either a "peripheral
zone" in some embodiments, or "at-or-near the peripheral zone," in
some embodiments. The following table shows a hypothetical
relationship between the radius and the area of a hypothetical
endplate model using for simplicity a circular area having a
diameter of 25 mm.
TABLE-US-00001 scale (fraction of total diameter radius area area)
(mm) (mm) (mm){circumflex over ( )}2 total 1.00 25.00 12.50 490.88
area 0.70 10.46 343.62 Scaled 0.60 9.68 294.53 Scaled 0.50 8.84
245.44 Scaled 0.40 7.91 196.35 Scaled 0.30 6.85 147.26 Scaled 0.20
5.59 98.18 Scaled 0.10 3.95 49.09 Scaled
[0041] Interestingly, a central portion of the hypothetical
circular area having area based on a radius of 6.85 mm, which is
about 55% of the total radius provides only 30% of the total area.
As such, if the central portion amounts to only about 50% of the
total area, it uses about two-thirds of the radius of the total
area, leaving a radial dimension for the peripheral zone that is
about 3.66 mm wide for the hypothetical endplate having the
diameter of 25 mm. In some embodiments, the central portion can be
10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or
any percentage therein increments of 1%, of the total area. In some
embodiments, the peripheral zone can have a radial dimension, or
radial width, that is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or
any 0.1 mm increment therein. It should be appreciated that the
radial dimension, or radial width, is the thickness of the
peripheral zone area that circumscribes the periphery of the
endplate as shown in FIG. 1, 125, and further described above
qualitatively with respect to the remainder of the overlay of the
central portion on the total area. One of skill will appreciate
that a peripheral zone does not have to be uniform, and that the
teachings provided herein to define the peripheral zone, or the
area at-or-near the peripheral zone, are taught to further clarify
boundaries of some embodiments by distinguishing both a
configuration and function of the trials and systems taught herein
from the current state-of-the-art. As such, it should be
appreciated that the trials can be further configured to have a
contour, whether laterally, vertically, or both laterally and
vertically, that is at least substantially complementary to the
areas within the peripheral zone, or at-or-near the peripheral
zone, during operation of the trials provided herein. For example,
the trial can have a linear, curved, or curvalinear lateral
surface; a flat or convex vertical surface; or, some combination
thereof, upon expansion to provide a shape that is at least
substantially complementary to the peripheral zone of the endplates
upon expansion.
[0042] FIG. 2 illustrates a process of using a staged,
bilaterally-expandable trial for distracting an intervertebral
space, according to some embodiments. The method 200 of distracting
an intervertebral space can include, for example, obtaining a
bilaterally expandable trial that is configured to first expand
laterally and then expand vertically to distract an intervertebral
space having a top vertebral plate and a bottom vertebral plate.
The method 200 includes creating 205 a point of entry into an
intervertebral disc and removing 210 the nucleus pulposus from
within the intervertebral disc to create an intervertebral space.
The method further includes inserting 215 the trial into the
intervertebral space in a collapsed state. Once inserted, the trial
then used for distracting 220 the intervertebral space using a
staged, bilateral expansion, the distracting including a first
stage and a second stage. The first stage includes laterally
expanding 225 the trial to a position at or near the peripheral
zones of the top vertebral plate and the bottom vertebral plate,
and the second stage includes vertically expanding 230 the trial at
or near the peripheral zones of the top vertebral plate and the
bottom vertebral plate to distract the intervertebral space while
avoid the problem of subsidence.
[0043] FIGS. 3A-3D illustrate a staged, bilaterally-expandable
trial, according to some embodiments. As shown in FIG. 3A, a top
view of the trial 300, the trial 300 comprises a
bilaterally-expandable shell having a proximal region 301 with an
end 302, a mid-region 303, a distal region 305 with an end 306, and
a lumen 307. As shown in FIG. 3B, the proximal region 301 can have
a slider-guide 310, and the distal region 305 can have a
bilaterally-expandable head 315 with 4 subheads 316,317,318,319
that include a first top beam 316, a second top beam 317, a first
bottom beam 318, and a second bottom beam 319. The mid-region can
have 4 flex rods 321,322,323,324 that include a first top flex rod
321, a second top flex rod 322, a first bottom flex rod 323, and a
second bottom flex rod 324, each of which operably attaches the
slider-guide 310 to it's respective subhead. As shown in FIG. 3C,
the end 306 of the distal region can be tapered or otherwise round,
configured in the collapsed state in some embodiments, for example,
as a bullet-nosed tip to avoid damage to the inner annulus during
the distraction procedure. As shown in FIG. 3D, a side view of the
trial 300, and comparing to FIG. 3A, the ratio of .theta..sub.V to
.theta..sub.L is 1:2 in this embodiment for a staged bilateral
expansion of the trial. The example dimensions shown in FIGS. 3A-3D
are in inches.
[0044] In some embodiments, the rods can range from 2 cm to 4 cm in
length and 0.5 mm to 2 mm in thickness. In some embodiments, the
rods can be 1 mm wide by 1 mm thick and have a length of 2.5
cm.
[0045] In some embodiments, the shell can be wider at the head than
the region proximal to the head. In some embodiments, the shell can
be taller at the head than the region proximal to the head.
[0046] The trial can be expanded first laterally, and then
vertically, using any means known to one of skill. FIGS. 4A-4D
illustrate a shim for the staged, bilaterally expanding trial,
according to some embodiments. As shown in FIGS. 4A and 4B, the
trial can also comprise a shim 400 having a proximal region 401
with an end 402; a mid-region 403; a distal region 405 with an end
406; a central axis 409; a top surface 411 with a first top-lateral
surface 412 and a second top-lateral surface 413; a bottom surface
415 with a first bottom-lateral surface 416 and a second
bottom-lateral surface 417; a first side surface 419 with a first
top-side surface 420 and a first bottom-side surface 421; and, a
second side surface 425 with a second top-side surface 426 and a
second bottom-side surface 427. The shim can be configured for a
proximal-to-distal axial translation 444 in the lumen of the shell
that induces a lateral force on the 4 subheads followed by a
vertical force on the 4 subheads for a staged, bilateral expansion
in vivo that includes a lateral expansion of the head followed by a
vertical expansion of the head in an intervertebral space having a
top vertebral endplate, a bottom vertebral endplate, and an
annulus.
[0047] The head of the trial can be configured with a proximal
portion having an end; a distal portion having an end; and, a
central shell axis of the expanded state; the head adapted for
slidably-engaging with the shim in vivo following placement of the
trial in the intervertebral space through the annular opening, the
slidably-engaging including axially-translating the shim in the
lumen of the shell from the proximal end of the lumen toward the
distal end of the lumen in vivo; the translating including keeping
the central shim axis at least substantially coincident with the
central shell axis during the translating.
[0048] In some embodiments, the shim has a cross-shaped
cross-section which is formed by the crossing of a vertical wedge
and a lateral wedge. Both wedges can taper down to an edge at the
distal end. When the shim slides distally relative to the shell, it
can push against the inner chamfers on the subheads to move the
subheads away from each other to expand the shell head. When the
head expands, the subheads are pushed outward and flex the
respective rods outward. When the shim is pulled back, the head
collapses because the rods flex back in. Additionally, a coil
spring can be wrapped around an outer transverse groove on the head
to further help to pull the subheads together when the shim is
pulled back. An elastic band (silicone) can be used rather than
coil spring. The shell-shim assembly can be designed such that the
lateral expansion wedge engages with the chamfers on the subheads
before the vertical expansion wedge engages so that the head
expands laterally before it expands vertically. In some
embodiments, this can be achieved by having the lateral expansion
chamfers (angled relative to vertical plane along long axis of
device) angled more from the long axis than the vertical expansion
chamfers. In one embodiment, the lateral expansion chamfers are 20
degrees from long axis and the vertical expansion chamfers are 10
degrees from the axis. In one embodiment, the bevels on the wedges
are parallel to the chamfers on the subheads. In some embodiments,
the bevels on the lateral expansion wedge can be advanced beyond
the lateral expansion chamfers before the vertical expansion wedge
engages the vertical expansion chamfers on the subheads. Once the
bevels on the lateral expansion wedge is advanced beyond the
chamfer, there is no more head expansion as the shim is advanced
further distally. As such, the shim can continue to be advanced
distally to expand the head vertically without further lateral
expansion.
[0049] In some embodiments, the subheads can be 4.5 mm thick
laterally and the lateral expansion wedge tapers up to 4 mm wide to
allow for lateral expansion from 9 mm to 13 mm. The collapsed
thickness of the head in any direction can be the sum of the
thicknesses of the subheads in that direction, and the maximum
amount of expansion can be the maximum thickness of the wedge. In
some embodiments, the subheads can be 3.35 mm in the vertical
direction and the vertical expansion wedges can be 4.3 mm tall to
allow for vertical expansion from 6.7 mm to 11 mm. In some
embodiments, the subheads can be 4 mm tall in the vertical
direction and the vertical expansion wedges can be 6 mm tall to
allow for vertical expansion from 8 mm to 14 mm.
[0050] In some embodiments, the shim can have a tail that extends 2
cm to 4 cm long proximal from the wedge part and a rectangular
cross section that is 2 mm to 5 mm thick. The tail can be
configured to slide along a rectangular hole in the slider guide.
This construct can be adapted to limit the movement of the wedges
to the long axis direction. In some embodiments, the shell rods can
be flush with a groove formed by an intersection between the
vertical and lateral wedges to help keep the assembly stable for
insertion into the disc. In some embodiments, the vertical wedges
can be flush with the vertical chamfers on the subheads in the
collapsed state to further stabilize the subheads from movement in
the lateral direction for insertion into the disc space.
[0051] One of skill will also appreciate having a method of
designing the shape of the head upon expansion. In some
embodiments, for example, it may be beneficial for the distal
expansion of the head to be larger than the proximal expansion of
the head to account for a lordosis in the subject. Or, in some
embodiments, for example, it may be considered beneficial for the
expanded head to have a convexity in the subheads that applies a
pressure to either endplate. As such, in some embodiments, the
expanding includes selecting a shim configured to vertically expand
the distal end of the cage more than the proximal end of the cage.
Or, in some embodiments, the expanding includes selecting a shim
configured to create a convex surface on the top surface of the top
wall, for example, to at least substantially complement the
concavity of the respective top vertebral plate, and/or the bottom
surface of the bottom wall to at least substantially complement the
concavity of the respective bottom vertebral plate. Or, in some
embodiments, the expanding includes selecting a shim configured to
laterally expand the distal end of the cage more than the proximal
end of the cage.
[0052] One of skill will appreciate that the trial or the shim can
be fabricated using any desirable material having the requisite
material characteristics of strength, flexibility,
biocompatibility, and the like. In some embodiments, the shell and
the shim can be fabricated from stainless steel but can be made of
any metal or hard plastics such as ULTEM and PEEK.
[0053] The head of the trial can have a collapsed dimension that
facilitates insertion to the intervertebral space and an expanded
dimension that facilitates the desired lateral expansion and
vertical expansion in the intervertebral space. In some
embodiments, the head of the trial can have a collapsed state with
a transverse cross-section having a maximum dimension ranging from
5 mm to 18 mm, 6 mm to 18 mm, 7 mm to 18 mm, 5 mm to 15 mm, 5 mm to
16 mm, 5 mm to 17 mm, or any range therein in increments of 1 mm,
for placing the frame in an intervertebral space through an annular
opening for expansion in the intervertebral space. And, in some
embodiments, the head of the trial can have an expanded state with
a transverse cross-section having a maximum dimension ranging from
6.5 mm to 28 mm, 7.5 mm to 28 mm, 8.5 mm to 28 mm, 6.5 mm to 27 mm,
6.5 mm to 25 mm, 6.5 mm to 23 mm, 6.5 mm to 21 mm, 6.5 mm to 19 mm,
6.5 mm to 18 mm, or any range therein in increments of 1 mm, in the
intervertebral space. In some embodiments, the shim can have a
transverse cross-section with a maximum dimension ranging from 5 mm
to 18 mm for translating the shim in the lumen of the shell.
[0054] In some embodiments, the shim can have a horizontal wedge,
HW, configured to laterally-expand the trial, and a vertical wedge,
VW, configured to vertically-expand the trial. In some embodiments,
the shim can have a top wedge configured to laterally-expand the
first top beam away from the second top beam, a bottom wedge
configured to laterally-expand the first bottom beam away from the
second bottom beam, a first side wedge configured to
vertically-expand the first top beam away from the first bottom
beam, and a second side wedge configured to vertically-expand the
second top beam away from the second bottom beam. In some
embodiments, the proximal portion of the first top beam and the
proximal portion of the second top beam can be configured to
complement the top wedge at the onset of the lateral expansion
during the proximal-to-distal axial translation; and, the proximal
portion of the first bottom beam and the proximal portion of the
second bottom beam can be configured to complement the bottom wedge
at the onset of the lateral expansion during the proximal-to-distal
axial translation.
[0055] FIG. 5 illustrates the concept of the staged, bilateral
expansion of the trial, according to some embodiments. As shown in
FIG. 5, the distance, D.sub.STAGING, between the onset of the
lateral expansion 533 and the onset of the vertical expansion 543
can range from 2 mm to 10 mm, and is the axial proximal-to-distal
distance traveled by the shim in the staged expansion.
[0056] In some embodiments, the proximal portion of the first top
beam and the proximal portion of the first bottom beam can be
configured to complement the first side wedge during the
proximal-to-distal axial translation for the vertical expansion;
and, the proximal portion of the second top beam and the proximal
portion of the second bottom beam can be configured to complement
the second side wedge during the proximal-to-distal axial
translation for the vertical expansion.
[0057] In some embodiments, the first top beam 516 can include a
proximal portion having an end, a distal portion having an end, and
a central axis 516a; the first top beam 516 configured for
contacting a first top chamfer 555 (lateral and vertical) of the
shim in the expanded state, the central axis 516a of the first top
beam 516 at least substantially on (i) a top plane containing the
central axis 516a of the first top beam 516 and the central axis
517a of a second top beam 517 and (ii) a first side plane
containing the central axis 516a of the first top beam 516 and the
central axis 518a of a first bottom beam 518. Likewise, the second
top beam 517 can include a proximal portion having an end, a distal
portion having an end, and a central axis 517a; the second top beam
517 configured for contacting a second top chamfer 566 (lateral
shown, vertical not shown) of the shim in the expanded state, the
central axis 517a of the second top beam 517 at least substantially
on (i) the top plane and (ii) a second side plane containing the
central axis 517a of the second top beam 517 and the central axis
519a of a second bottom beam 519. Likewise, the first bottom beam
518 can include a proximal portion having an end, a distal portion
having an end, and a central axis 518a; the first bottom beam 518
configured for contacting a first bottom chamfer 577 (vertical
shown, lateral not shown) of the shim in the expanded state, the
central axis 518a of the first bottom beam 518 at least
substantially on (i) a bottom plane containing the central axis
518a of the first bottom beam 518 and the central axis 517a of a
second top beam 517 and (ii) the first side plane. Moreover, the
second bottom beam 519 (not shown) can include a proximal portion
having an end, a distal portion having an end, and a central axis
519a; the second bottom beam 519 configured for contacting a second
bottom chamfer (not shown) of the shim in the expanded state, the
central axis 519a of the second bottom beam 519 being at least
substantially on (i) the bottom plane and (ii) a second side plane
containing the central axis 519a of the second bottom beam 519 and
the central axis 517a of the second top beam 517.
[0058] In some embodiments, the first top beam can include a
proximal portion having an end, a distal portion having an end, and
a central axis; the first top beam configured for contacting a
first top-lateral surface of the shim and a first top-side surface
of the shim in the expanded state, the central axis of the first
top beam at least substantially on (i) a top plane containing the
central axis of the first top beam and the central axis of a second
top beam and (ii) a first side plane containing the central axis of
the first top beam and the central axis of a first bottom beam.
Likewise, the second top beam can include a proximal portion having
an end, a distal portion having an end, and a central axis; the
second top beam configured for contacting the second top-lateral
surface of the shim and the second top-side surface of the shim in
the expanded state, the central axis of the second top beam at
least substantially on (i) the top plane and (ii) a second side
plane containing the central axis of the second top beam and the
central axis of a second bottom beam. Likewise, the first bottom
beam can include a proximal portion having an end, a distal portion
having an end, and a central axis; the first bottom beam configured
for contacting the first bottom-lateral surface of the shim and the
first bottom-side surface of the shim in the expanded state, the
central axis of the first bottom beam at least substantially on (i)
a bottom plane containing the central axis of the first bottom beam
and the central axis of a second top beam and (ii) the first side
plane. Moreover, the second bottom beam can include a proximal
portion having an end, a distal portion having an end, and a
central axis; the second bottom beam configured for contacting the
second bottom-lateral surface of the shim and the second
bottom-side surface of the shim in the expanded state, the central
axis of the second bottom beam being at least substantially on (i)
the bottom plane and (ii) a second side plane containing the
central axis of the second bottom beam and the second top beam.
[0059] The selection and arrangement of the wedges and angles can
be selected to stage the expansion of the trial in the lateral and
vertical directions. In some embodiments, the shim can comprise a
lateral-expansion wedge with angle .theta..sub.L ranging from
10.degree. to 30.degree. and a vertical-expansion wedge with angle
.theta..sub.V ranging from 30.degree. to 50.degree., the apex of
the lateral-expansion wedge and the apex of the vertical-expansion
wedge each at least substantially on a single plane that is
orthogonal to the central axis of the shim, and the ratio of
.theta..sub.V:.theta..sub.L ranges from 1:1.25 to 1:4 to stage the
bilateral expansion of the head.
[0060] In some embodiments, the shim can comprise a
lateral-expansion wedge with angle .theta..sub.L ranging from
10.degree. to 90.degree. and a vertical-expansion wedge with angle
.theta..sub.V ranging from 10.degree. to 90.degree., the apex of
the lateral-expansion wedge on a first plane and the apex of the
vertical expansion wedge on a second plane, both the first plane
and the second plane being orthogonal to the central axis of the
shim and separated on the central axis at a distance ranging from 2
mm to 10 mm to stage the bilateral expansion of the head.
[0061] The shell can be formed using any method of construction
known to one of skill, for example, multi-component or single unit.
In some embodiments, the shell can be a single-unit formed from a
single body of material, and the slider-guide, head, and flex rods
can be monolithically integral.
[0062] In some embodiments, each subhead can have a shape of a
rectangular bar with a tapered tip on the outside surface and
chamfers on the inner surfaces. The subheads can be located near
the corners of the distal end of the trial. When collapsed for
insertion, the head can be 6 mm to 9 mm in height by 6 mm to 10 mm
in width, in some embodiments. Moreover, the head can expand in
some embodiments to 16 mm in height to 16 mm in width. In some
embodiments, the head can expand from 6.7 mm to 11 mm in height and
from 9 mm 13 mm in width. In some embodiments, the head can expand
from 8 mm to 14 mm height and from 9 mm to 13 mm in width. In some
embodiments, the length of the head can range from 20 mm to 60 mm,
20 mm to 50 mm, 20 mm to 40 mm, 25 mm to 45 mm, 25 mm to 55 mm, or
any range therein increments of 1 mm.
[0063] In some embodiments, the trial can have a means for
retaining the collapsed state, such as an elastic means. The
elastic means can be, for example, a coil spring or an elastic
silicone band. The means for retaining can circumscribe the outer
circumference of the subheads, and can be further affixed to the
assembly using a transverse groove, helping to pull the subheads
together when the shim is pulled in the distal-to-proximal
direction.
[0064] FIG. 6 illustrates a trial system for a staged, bilateral
expansion of the trial in an intervertebral space, according to
some embodiments. The trial system 600 includes the trial 605, the
shim 610, a guide tube or barrel 615 to help guide the trial 605
into the intervertebral space, an actuation bar 620, a threaded
connector 625, a handle 630, an actuator screw 635, an actuator
knob 640 to actuate the actuator screw 635 to apply the axial
proximal-to-distal force, F.sub.PD, and a stop block 645 to hold
the actuator knob in place against the counter force,
-F.sub.PD.
[0065] It should be appreciated that the systems can also include
any known means for applying an axial proximal-to-distal force on a
shim that expands the trial. In some embodiments, the proximal end
of the shim can be configured to receive the axial
proximal-to-distal force through the actuation bar for the axial
translation, the actuation bar having a proximal portion with a
proximal end, a distal portion with a distal end, and configured to
transfer the axial proximal-to-distal force to the shim through the
slider-guide.
[0066] The systems can include such an actuation means operably
attached to the proximal end of the actuation bar 620 to transfer
the axial proximal-to-distal force F.sub.PD to the shim 610 through
the distal end of the actuation bar 620. In some embodiments, the
actuation bar 620 receives the axial proximal-to-distal force from
the actuator screw 635 that can be operably attached to the
proximal end of the actuation bar 620 to transfer the force to the
shim 619 through the distal end of the actuation bar 620.
[0067] FIGS. 7A and 7B illustrate a trial system with an expansion
gauge and a retractable retention plunger for retaining the trial
prior to a staged, bilateral expansion of the trial in an
intervertebral space, according to some embodiments. FIG. 7A
provides an exploded view of the assembly of the system 700. The
system 700 includes the trial 705, the shim 710, a guide tube or
barrel 715 to help guide the trial 705 into the intervertebral
space. The system 700 also includes an actuation bar 720, a push
rod 727, a handle 730, an actuator screw 735, an actuator knob 740
to actuate the actuator screw 635 to apply the axial
proximal-to-distal force, F.sub.PD, and a stop block 745 to hold
the actuator knob 740 in place against the counter force,
-F.sub.PD. The trial 705
[0068] The systems can further comprise a retractable retention
plunger configured for retaining the trial in the collapsed state
and releasing the trial for expansion into the expanded state. A
retractable retention plunger 760, for example, can also be
included with a handle 763 and a retainer 767 for retaining the
trial 705 in a collapsed state, the plunger functioning to retain
the trial 705 by moving it proximal-to-distal 771PD; and, to
release the trial 705 by moving it distal-to-proximal 771DP. The
system can also include an expansion gauge 750 to provide a measure
of intervertebral expansion and contraction realized when turning
777 the actuator knob 740 clockwise or counterclockwise. The
expansion occurs, for example, through an axial proximal-to-distal
movement 779PD of the shim 710 into the trial 705. FIG. 7B shows
the system assembled with the plunger 760 function to retain the
trial 705 in the collapsed state. The trial 705 can be expanded,
for example, by pulling the plunger handle 763 in a
distal-to-proximal direction for a distal-to-proximal movement 771
DP of the retainer 767 to release the trial 705 for the expansion.
The expansion is then obtained by turning the knob 740 to obtain
the axial proximal-to-distal movement 779PD of the shim 710 into
the trial 705.
[0069] One or more beam stabilizers can be included stabilize
and/or align the subheads during operation of the device. A beam
stabilizer, for example, can slidably translate, such that it is
telescopic with respect to one or both subheads between which it is
operably attached to stabilize and/or align the relationship
between the subheads during operation of the device. In some
embodiments, the beams can be stabilized with translatable,
telescopic linear guides, such that the linear guide can telescope
within itself. For example, the first top beam can be operably
connected to the second top beam with a top telescopic beam
stabilizer, the first top beam can be operably connected to the
second top beam with a top telescopic beam stabilizer, the first
top beam can be operably connected to the first bottom beam with a
first side telescopic beam stabilizer, the second top beam can be
operably connected to the second bottom beam with a second side
telescopic beam stabilizer, and the first bottom beam can be
operably connected to the second bottom beam with a bottom
telescopic beam stabilizer. The beam stabilizer, or at least a
portion thereof, can be fixably attached, or monolithically
integral to, one or both beams between which it is operably
connected or positioned in either a fixed or translatable
configuration in the trial.
[0070] Given the teachings provided herein, one of skill will
appreciate that each subhead can be designed/adapted/configured for
an operable connection with interlocking and interconnecting
structures that serve to provide alignment and stability between
the subhead and a second subhead during expansion and/or collapse
of the trial. The transverse interconnection structures are
intended to provide stability to the head assembly while at least
substantially limiting the movement of the heads to the direction
of expansion and/or collapse, such that the relative stability
between beams in the trial system during expansion or collapse is
improved by at least 10%, 20%, 30%, 40%, 50%, 60%, or 70% over the
relative stability between beams in a comparison trial system
having the same structure in the absence of the beam stabilizer
configuration. For example, both the system and the comparison
trial system can each have the same configuration of 4 subheads
that include a first top beam, a second top beam, a first bottom
beam, and a second bottom beam, each of the beams having a central
axis. The desired, stabilized and/or aligned configuration can be,
for example, that the central axis of the first top beam is at
least substantially on (i) a top plane containing the central axis
of the first top beam and the central axis of a second top beam and
(ii) a first side plane containing the central axis of the first
top beam and the central axis of a first bottom beam. If the
comparison trial system deviates from the desired stabilized and/or
aligned configuration by, for example, 30.degree., measured as the
deviation as the deflection of a beam's central axis from the
desired configuration, then an improvement of at least 10% would
represent a deflection of 27.degree. or less, an improvement of at
least 20% would represent a deflection of 24.degree. or less, an
improvement of at least 30% would represent a deflection of
21.degree. or less, an improvement of at least 40% would represent
a deflection of 18.degree. or less, an improvement of at least 50%
would represent a deflection of 15.degree. or less, an improvement
of at least 60% would represent a deflection of 12.degree. or less,
an improvement of at least 70% would represent a deflection of
9.degree. or less, an improvement of at least 80% would represent a
deflection of 6.degree. or less, an improvement of at least 90%
would represent a deflection of 3.degree. or less, an improvement
of at least 95% would represent a deflection of 1.5.degree. or
less, in some embodiments. One of skill will appreciate that this
is merely an example of how the % improvement can be calculated.
The same, or any similar, approach can be used as a relative
measure of improvement due to configurations that include one or
more beam stabilizers.
[0071] In some embodiments, the beam stabilizer can be a
telescoping male/female relationship between two bosses, a male
boss configured on a first beam and a female boss configured on a
second beam. In these embodiments, the male boss is monolithically
integral to the first beam, and the female boss is monolithically
integral to the second beam, the male boss slidably translating
with the female boss to at least substantially confining movement
between the first beam and the second beam to the transverse
movement of expansion and collapse between the beams.
[0072] FIGS. 8A-8D illustrate a staged, bilaterally-expandable
trial with beam stabilizers, according to some embodiments. As
shown in FIG. 8A, a system such as system 700 can be used, having
the guide tube or barrel 815, plunger 860, and retainer 867, the
trial 805 being in the expanded state by turning the knob 840 to
obtain the axial proximal-to-distal movement 879PD of the shim 810
into the trial 805. As shown in FIGS. 8B and 8C, a beam stabilizer
880 can be used to provide a means for an increased relative
stability between beams that frame the top, bottom, first side, and
second side of the trial 805. Such means for providing the
increased relative stability between beams can be, for example, a
telescopic linear guide configuration having a guide 882 and slider
884. The shim 810 is forced to enter the trial 805 through
proximal-to-distal axial movement 879PD, and the beam stabilizers
880 increase the relative stability of the trial during the
distraction procedure.
[0073] In some embodiments, the telescopic linear guide comprises a
slider and a guide. In some embodiments, the slider can be a plate,
and the guide can be a rail. In some embodiments, the slider can be
plate, and the guide can be a member that at least partially
circumscribes the plate. In some embodiments, the slider can be a
plate, and the guide can be a cylinder. It should be appreciated
that the guide can be a circular cylinder, an elliptical cylinder,
a square cylinder, a rectangular cylinder, a triangular cylinder, a
pentagonal cylinder, or hexagonal cylinder. Likewise the slider can
be any complementary rigid structure, such as a cylindrical rod, an
elliptical rod, a square rod, a rectangular rod, a triangular rod,
a pentagonal rod, or a hexagonal rod. In some embodiments, the beam
stabilizer is an assembly that telescopes to facilitate the
expansion and the collapse of the trial. In some embodiments, the
slider and the guide translate relative to one another to provide
the telescopic movement for expansion and collapse of the trial
without a relative rotary motion between the guide and slider.
[0074] As shown in FIGS. 8B-8D, the system trial 805 can have a
bilaterally-expandable system of 4 subheads 816,817,818,819 that
include a first top beam 816, a second top beam 817, a first bottom
beam 818, and a second bottom beam 819. The mid-region can have 4
flex rods 821,822,823,824 that include a first top flex rod 821, a
second top flex rod 822, a first bottom flex rod 823, and a second
bottom flex rod 824, each of which operably attaches a slider-guide
not shown (see, for example, FIG. 3, 310; and FIG. 7, 701) to it's
respective subhead. As shown in FIG. 8C, each end 806 of the 4
subheads 816,817,818,819 can be tapered or otherwise round,
configured in the collapsed state in some embodiments, for example,
as a bullet-nosed tip to avoid damage to the inner annulus during
the distraction procedure.
[0075] In some embodiments, a pin can be rigidly connected to each
of two subheads but telescoping within itself, for example, a first
portion of the pin can be hollow to guide a second portion of the
pin to slidably translate the second portion as a slider within the
guide of the first portion. In some embodiments, the telescoping
arrangement of the beam stabilizers can include a linear connector
pin, or other single unit linear member (cylindrical rod,
elliptical rod, triangular rod, square rod, rectangular rod,
trapezoidal rod, pentagonal rod, hexagonal rod, heptagonal rod,
octagonal rod, and any other polygonal rod or cylinder) having two
ends, each end of which is adapted for operably connecting to a
counter-bore hole in one of two subheads between which the pin is
positioned and/or connected.
[0076] FIGS. 9A-9E illustrate a staged, bilaterally-expandable
trial with beam stabilizers that telescope with one or both
subheads having a counter-bore, according to some embodiments. As
shown in FIGS. 9A (collapsed configuration) and 9B (expanded
configuration), the system trial 905 can have a
bilaterally-expandable system of 4 subheads 916,917,918,919 that
include a first top beam 916, a second top beam 917, a first bottom
beam 918, and a second bottom beam 919. The mid-region can have 4
flex rods 921,922,923,924 that include a first top flex rod 921, a
second top flex rod 922, a first bottom flex rod 923, and a second
bottom flex rod 924, each of which operably attaches a slider-guide
901 to it's respective subhead. As shown in FIG. 9C (head-only,
expanded), each end 906 of the 4 subheads 916,917,918,919 can be
tapered or otherwise round, configured in the collapsed state in
some embodiments, for example, as a bullet-nosed tip to avoid
damage to the inner annulus during the distraction procedure.
[0077] As the head expands as shown in FIGS. 9A-9E, the subhead of
trial 905 can slide on a pin 990 transversely while limited in
movement by a means (not visible) of stopping the translational
expansion. For example, as shown in FIGS. 9D and 9E each end of the
pin 990 can have a retention head, or pinhead 997 that is retained
in the counter-bore 991 of each subhead of trial 905 by a cap 993
that covers the counter-bore (not visible) to retain the pin 990
upon expansion 905e and collapse 905c of the trial 905. One of
skill will appreciate that in order for the pin 990 to translate in
the subhead of the trial 905 and be retained, (i) the outer
diameter, or transverse dimension, of the pin 990 is less than the
inner diameter, or transverse dimension, of the counter-bore pin
guide 995; and (ii) the outer diameter, or transverse dimension, of
the pinhead 997 is greater than the inner diameter, or transverse
dimension, of the counter-bore pin guide 995. It should also be
appreciated that the pinhead 997 can be a cap, a flange, or any
other configuration that results in the pinhead 997 having a larger
diameter or transverse dimension than the pin 990 and the inner
diameter, or transverse dimension, of the counter-bore pin guide
995.
[0078] Accordingly, a method of distracting an intervertebral space
using the trials is provided. In some embodiments, the method can
comprise creating a point of entry into an intervertebral disc, the
intervertebral disc having a nucleus pulposus surrounded by an
annulus fibrosis, and the point of entry having the maximum lateral
dimension created through the annulus fibrosis. The methods can
include removing the nucleus pulposus from within the
intervertebral disc through the point of entry, leaving the
intervertebral space for expansion of the head of the trial within
the annulus fibrosis, the intervertebral space having the top
vertebral plate and the bottom vertebral plate. The methods can
include inserting the head in the collapsed state through the point
of entry into the intervertebral space; and, distracting the
intervertebral space using a staged, bilateral expansion that
includes a first stage and a second stage. The distracting can
include a first stage and a second stage, the first stage including
expanding the head laterally toward the peripheral zones of the top
vertebral plate and the bottom vertebral plate; and, the second
stage including expanding the head vertically to distract the
intervertebral space, the pressure for the expansion occurring
preferably, and at least primarily, at or near the peripheral zones
of the top vertebral plate and the bottom vertebral plate. In some
embodiments, the lateral dimension of the point of entry ranges
from about 5 mm to 18 mm, 6 mm to 18 mm, 7 mm to 18 mm, 5 mm to 15
mm, 5 mm to 16 mm, 5 mm to 17 mm, or any range therein in
increments of 1 mm.
[0079] In some embodiments, the distracting includes selecting an
amount of lateral expansion independent of an amount of vertical
expansion. And, in some embodiments, the distracting includes
measuring the amount of lateral expansion independent of the amount
of vertical expansion.
[0080] In some embodiments, the distracting includes as a first
stage of lateral expansion, inserting a top wedge into the head
between the first top beam and the second top beam, the top wedge
composing a portion of the shim and configured to laterally-expand
the first top beam away from the second top beam; and, inserting a
bottom wedge into the head between the first bottom beam and the
second bottom beam, the bottom wedge configured to laterally-expand
the first bottom beam away from the second bottom beam. And, as a
second stage of expansion, inserting a first side wedge into the
head between the first top beam and the first bottom beam, the
first side wedge configured to laterally-expand the first top beam
away from the first bottom beam; and, inserting a second side wedge
into the head between the second top beam and the second bottom
beam, the second side wedge configured to laterally-expand the
second top beam away from the second bottom beam.
[0081] In some embodiments, the distracting includes selecting a
shim having a lateral-expansion wedge with angle .theta..sub.L
ranging from 10.degree. to 30.degree. and a vertical-expansion
wedge with angle .theta..sub.V ranging from 30.degree. to
50.degree., the apex of the lateral-expansion wedge and the apex of
the vertical-expansion wedge each at least substantially on a
single plane that is orthogonal to the central axis of the shim,
and the ratio of .theta..sub.V:.theta..sub.L ranges from 1:1.25 to
1:4 to stage the bilateral expansion of the head.
[0082] In some embodiments, the distracting includes selecting a
shim having a lateral-expansion wedge with angle .theta..sub.L
ranging from 10.degree. to 90.degree. and a vertical-expansion
wedge with angle .theta..sub.V ranging from 10.degree. to
90.degree., the apex of the lateral-expansion wedge on a first
plane and the apex of the vertical expansion wedge on a second
plane, both the first plane and the second plane being orthogonal
to the central axis of the shim and separated on the central axis
at a distance ranging from 2 mm to 10 mm to stage the bilateral
expansion of the head.
[0083] In some embodiments, the head of the trial can also be used
as a "trial shim" for a bilaterally expandable cage by expanding
the trial bilaterally and measuring the size of the expanded head
to obtain a measure of the width and the height of the
intervertebral space.
[0084] One of skill will appreciate that the teachings provided
herein are directed to basic concepts that can extend beyond any
particular embodiment, embodiments, figure, or figures. As such,
there are several equivalents that can be contemplated having
substantially the same function, performed in substantially the
same way, for substantially the same result. As such, it should be
appreciated that any examples are for purposes of illustration and
are not to be construed as otherwise limiting to the teachings. For
example, it should be appreciated that the devices provided herein
can also be used in other areas of the body, and can have slightly
varying configurations and adaptations. The devices provided herein
can be used, for example, in intravertebral body procedures to
distract intervertebral bodies in operations that may include the
repair of, for example, collapsed, damaged or unstable vertebral
bodies suffering from disease or injury.
* * * * *