U.S. patent application number 14/878929 was filed with the patent office on 2016-01-28 for expandable intervertebral cage assemblies.
The applicant listed for this patent is James C. Robinson. Invention is credited to James C. Robinson.
Application Number | 20160022434 14/878929 |
Document ID | / |
Family ID | 55165775 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160022434 |
Kind Code |
A1 |
Robinson; James C. |
January 28, 2016 |
EXPANDABLE INTERVERTEBRAL CAGE ASSEMBLIES
Abstract
An expandable assembly for insertion into an intervertebral
space is presented. The assembly, in particular aspects, includes
an elongate body comprising an upper portion and a lower portion,
wherein the elongate body defines an internal longitudinal channel
extending from a proximal opening to a distal cavity. The assembly
may include an expander that is sized and shaped for insertion into
the distal cavity, thereby selectively expanding the upper portion
away from the lower portion. The elongate body may also include one
or more bone graft windows a cap that is sized and shaped for
insertion into the proximal opening.
Inventors: |
Robinson; James C.;
(Atlanta, GA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Robinson; James C. |
Atlanta |
GA |
US |
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|
Family ID: |
55165775 |
Appl. No.: |
14/878929 |
Filed: |
October 8, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14561214 |
Dec 4, 2014 |
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14878929 |
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13962879 |
Aug 8, 2013 |
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14561214 |
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61787744 |
Mar 15, 2013 |
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61680729 |
Aug 8, 2012 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61F 2002/30736
20130101; A61F 2002/30507 20130101; A61F 2002/30624 20130101; A61F
2002/30579 20130101; A61F 2002/30594 20130101; A61F 2002/30492
20130101; A61F 2/447 20130101; A61F 2/4611 20130101; A61F
2002/30827 20130101; A61F 2002/4627 20130101; A61F 2002/30451
20130101; A61F 2002/30448 20130101; A61F 2002/30471 20130101; A61F
2002/30515 20130101; A61F 2002/30331 20130101 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61F 2/30 20060101 A61F002/30; A61F 2/46 20060101
A61F002/46 |
Claims
1. An expandable cage for insertion into an intervertebral space,
comprising: a cage body having a leading end, a trailing end, an
upper portion and a lower portion, the upper portion having a an
upper bone contact surface and an upper portion lower surface, the
lower portion having a lower bone contact surface and a lower
portion upper surface, wherein the upper portion and lower portion
are connected and wherein the upper portion lower surface and lower
portion upper surface define an internal space; an elongate
expander positioned at least partially therein the internal space,
wherein a proximal portion of the elongate expander defines an
aperture in communication with the internal space wherein
translation of the elongate expander proximally toward the trailing
end of the cage body moves the cage body into an expanded position
by separating at least a portion of the upper portion of the cage
body from at least a portion of the lower portion of the cage body;
and an actuating screw positioned within the aperture engaged with
the proximal portion of the expander and having a screw head,
wherein rotation of the actuating screw in a first direction moves
the elongate expander proximally, and rotation of the elongate
screw in a second direction moves the elongate expander distally;
wherein, the cage body comprises a shoulder substantially adjacent
the trailing end, the shoulder defining an orifice configured for
receipt of the actuating screw, whereby rotating the actuating
screw in the first direction until the cage body is in the expanded
position, sandwiches at least a portion of the shoulder between
portions of the screw head and the proximal portion of the elongate
expander.
2. The expandable cage of claim 1, wherein an upper portion of the
shoulder is integral with the upper portion of the cage body.
3. The expandable cage of claim 1, wherein the upper portion has an
upper portion inner surface and the lower portion has a lower
portion inner surface, and wherein portions of the distal portion
of the expander are complimentarily shaped with at least one of the
upper portion inner surface and the lower portion inner surface,
whereby pulling the expander proximally cams the distal portion of
the expander against the at least one of the upper portion inner
surface and the lower portion inner surface to expand the cage
body.
4. An expandable cage for insertion into an intervertebral space,
comprising: a cage body having a leading end, a trailing end, an
upper portion and a lower portion, the upper portion having a an
upper bone contact surface and an upper portion lower surface, the
lower portion having a lower bone contact surface and a lower
portion upper surface, wherein the upper portion and lower portion
are connected and wherein the upper portion lower surface and lower
portion upper surface define an internal space; an elongate
expander positioned at least partially within the internal space,
wherein a proximal portion of the elongate expander defines an
aperture in communication with the internal space wherein
translation of the elongate expander proximally toward the trailing
end of the cage body moves the cage body into an expanded position
by separating at least a portion of the upper portion of the cage
body from at least a portion of the lower portion of the cage body,
wherein a portion of the upper portion of the cage body
substantially adjacent the trailing end defines a first trough and
a portion of the lower portion of the cage body substantially
adjacent the trailing end defines a second trough; an actuating
screw positioned within the aperture; and a first shim positioned
within the first trough and a second shim positioned within the
second trough, the first and second shims forming a shoulder,
wherein the first and second shims define an orifice substantially
coaxial with the aperture.
5. The expandable cage of claim 4, wherein the actuating screw
comprises a head having a head diameter, and wherein the orifice
has an orifice diameter, and wherein the orifice diameter is
smaller than the head diameter.
6. The expandable cage of claim 5, wherein, when the elongate
expander is pulled proximately the first and second shims are
sandwiched between the elongate expander and the head of the
actuating screw.
7. The expandable cage of claim 6, wherein an insertion tool moves
the expander from the first position to the second position by
pulling the expander proximally.
8. The expandable cage of claim 4, wherein the first shim and the
cage body comprises a first material and the first and second shim
comprise a second material, wherein the second material is harder
than the first material.
9. The expandable cage of claim 8, wherein the first material is
PEEK.
10. The expandable cage of claim 9, wherein the second material is
Titanium.
11. A system comprising: an expandable cage comprising: a cage body
having a leading end, a trailing end, an upper portion and a lower
portion, the upper portion having a an upper bone contact surface
and an upper portion lower surface, the lower portion having a
lower bone contact surface and a lower portion upper surface,
wherein the upper portion and lower portion are connected and
wherein the upper portion lower surface and lower portion upper
surface define an internal space; an elongate expander positioned
at least partially within the internal space, wherein a proximal
portion of the elongate expander defines an aperture in
communication with the internal space wherein translation of the
elongate expander proximally toward the trailing end of the cage
body moves the cage body into an expanded position by separating at
least a portion of the upper portion of the cage body from at least
a portion of the lower portion of the cage body; an actuating screw
positioned within the aperture engaged with the proximal portion of
the expander and having a screw head, wherein rotation of the
actuating screw in a first direction moves the elongate expander
proximally, and rotation of the elongate screw in a second
direction moves the elongate expander distally, and wherein, the
cage body comprises a shoulder substantially adjacent the trailing
end, the shoulder defining an orifice configured for receipt of the
actuating screw, whereby rotating the actuating screw in the first
direction until the cage body is in the expanded position,
sandwiches at least a portion of the shoulder between portions of
the screw head and the proximal portion of the elongate expander;
and an insertion tool for inserting the expandable cage between two
adjacent vertebrae, the insertion tool being cannulated and
defining an internal chamber.
12. The system of claim 11, wherein the insertion tool comprises an
outer sleeve defining the internal chamber and a drive rod
positioned within the internal chamber, and wherein a distal
portion of the outer sleeve is configured for releasable engagement
with a portion of the trailing end of the expandable cage.
13. The system of claim 11, wherein a distal end of the drive rod
is configured to engage a portion of the actuating screw to enable
rotation thereof.
Description
CONTINUITY
[0001] This application claims the benefit of, priority to, and is
a continuation-in-part of U.S. application Ser. No. 13/962,879,
titled EXPANDABLE INTERVERTEBRAL CAGE ASSEMBLIES AND METHODS, filed
on Aug. 8, 2013, which claims priority to and the benefit of U.S.
Application No. 61/680,729, titled EXPANDABLE INTERVERTEBRAL CAGE
ASSEMBLIES AND METHODS, filed on Aug. 8, 2012; and U.S. Application
No. 61/787,744, titled EXPANDABLE INTERVERTEBRAL CAGE ASSEMBLIES
AND METHODS, filed on Mar. 15, 2013; all of which are incorporated
herein in their entirety.
BACKGROUND
[0002] The following disclosure relates generally to medical
devices, systems and methods, including, for example, systems and
methods for lumbar interbody fusion.
[0003] Surgical implantation of disc replacement material is
typically used to provide support along the spinal column in cases
where a portion of the patient's intervertebral anatomy has become
weakened, diseased, or destroyed. Such support systems are also
commonly used following a discectomy, where an intervertebral disc
is surgically removed.
[0004] Most commonly, existing support systems typically operate by
inhibiting normal movement between the adjacent vertebrae, thereby
holding these vertebrae at fixed positions relative to one another,
with the mechanical body of the supporting structure providing the
needed support along the patient's spinal column. Such supporting
systems are typically made of stainless steel, titanium, polymer
(e.g., an organic polymer thermoplastic such as polyether ether
ketone (PEEK)), carbon fiber, or ceramic and they are designed to
permanently remain within the patient's body.
[0005] It is beneficial, in addition to fixation, to try to
stimulate bone growth between the adjacent vertebrae. To do so,
spine surgeons use bone graft material in addition to fixation
devices. Bone graft doesn't heal or fuse the spine immediately;
instead, bone graft provides a foundation or scaffold for the
patient's body to grow new bone. Bone graft can stimulate new bone
production. When new bone grows and solidifies, fusion occurs.
Although instrumentation (e.g., screws, rods) is often used for
initial stabilization (post-operative), it is the healing of bone
that welds vertebrae together to create long-term stability. There
are two general types of bone grafts: real bone and bone graft
substitutes. Real bone can come from the patient (autograft) or
from a donor bone (allograft). Also used in these types of surgery
are bone substitute, osteoinductive agent, and bone cement.
[0006] There is a need for improved systems and methods for lumbar
interbody fusion.
SUMMARY
[0007] An expandable assembly for insertion into an intervertebral
space is disclosed. The assembly, in particular aspects, includes
an elongate body comprising an upper portion and a lower portion,
wherein the elongate body defines an internal longitudinal channel
extending from a proximal opening to a distal cavity. The assembly
may include an expander that is sized and shaped for insertion into
the distal cavity, thereby selectively expanding the upper portion
away from the lower portion. The elongate body may also include one
or more bone graft windows a cap that is sized and shaped for
insertion into the proximal opening.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] These and other features of the preferred embodiments of the
present invention will become more apparent in the detailed
description in which reference is made to the appended drawings
wherein:
[0009] FIG. 1A is a perspective view of one aspect of an expandable
cage for insertion into an intervertebral space in an unexpanded
position;
[0010] FIG. 1B is a perspective view of the expandable cage of FIG.
1A in an expanded position;
[0011] FIG. 2A is a side elevational view of the expandable cage of
FIG. 1A in the unexpanded position;
[0012] FIG. 2B is a side elevational view of the expandable cage of
FIG. 1A in the expanded position;
[0013] FIG. 3A is a proximal end elevational view of the expandable
cage of FIG. 1A in the unexpanded position;
[0014] FIG. 3B is a proximal end elevational view of the expandable
cage of FIG. 1A in the expanded position;
[0015] FIG. 4A is a side elevational cut away view of the
expandable cage of FIG. 1A in the unexpanded position, cut along
line 4A-4A in FIG. 3A;
[0016] FIG. 4B is a side elevational cut away view of the
expandable cage of FIG. 1A in the expanded position, cut along line
4B-4B in FIG. 3B;
[0017] FIG. 5A is a top plan view of the expandable cage of FIG. 1A
in the unexpanded position;
[0018] FIG. 5B is a top plan view of the expandable cage of FIG. 1A
in the expanded position;
[0019] FIG. 6A is a side elevational view of an expandable cage in
an unexpanded position associated with an insertion tool;
[0020] FIG. 6B is a side elevational view of an expandable cage in
an expanded position associated with an insertion tool;
[0021] FIG. 7 is a perspective view of an expander for use in an
expandable cage;
[0022] FIG. 8A is a perspective view of one aspect of an expandable
cage in the unexpanded position;
[0023] FIG. 8B is a perspective view of the expandable cage of FIG.
8A in the expanded position, showing at least one tongue in the
distal end of the upper and lower portions for complimentary fit
into a recess defined therein the expander;
[0024] FIG. 9A is a partially transparent perspective view of FIG.
8A;
[0025] FIG. 9B is a partially transparent perspective view of FIG.
8B;
[0026] FIG. 10 is a perspective view of the expander of FIGS. 8A
and 8B;
[0027] FIG. 11 is a perspective view of the upper portion of FIGS.
8A and 8B;
[0028] FIG. 12 is a perspective view of the lower portion of FIGS.
8A and 8B;
[0029] FIG. 13A is a perspective view of one aspect of an
expandable cage in the expandable position, showing at least one
hook positioned on the inner surface of the upper and lower
portions configured for complimentary receipt into a recess defined
in the distal portion of the expander;
[0030] FIG. 13B is a perspective view of the expandable cage of
FIG. 13A in the unexpanded position;
[0031] FIG. 14 is a partially transparent perspective view of one
aspect of an expandable cage for insertion into an intervertebral
space in an expanded position, showing an insertable locking
plate;
[0032] FIG. 15 is a cut-away perspective view of the expandable
cage of FIG. 14, cut along line 15-15 in FIG. 14;
[0033] FIG. 16 is a perspective view of the upper portion of the
expandable cage of FIG. 14;
[0034] FIG. 17 is a perspective view of the lower portion of the
expandable cage of FIG. 14;
[0035] FIG. 18 is a side elevational view of one aspect of an
expandable cage for insertion for insertion into an intervertebral
space in a partially expanded position;
[0036] FIG. 19 is a perspective view of the expandable cage of FIG.
18;
[0037] FIG. 20 is a perspective view of a lower portion of the
expandable cage of FIG. 18, showing an integral locking plate;
[0038] FIG. 21 is a perspective view of an upper portion of the
expandable cage of FIG. 18;
[0039] FIG. 22 is a rear perspective view of the expandable cage of
FIG. 18; and
[0040] FIG. 23 is a perspective view of an actuating screw for use
in the expandable cage of FIG. 18.
DETAILED DESCRIPTION
[0041] The present systems and apparatuses and methods are
understood more readily by reference to the following detailed
description, examples, drawing, and claims, and their previous and
following description. However, before the present devices,
systems, and/or methods are disclosed and described, it is to be
understood that this invention is not limited to the specific
devices, systems, and/or methods disclosed unless otherwise
specified, as such can, of course, vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular aspects only and is not intended to be
limiting.
[0042] The following description of the invention is provided as an
enabling teaching of the invention. To this end, those skilled in
the relevant art will recognize and appreciate that many changes
can be made to the various aspects of the invention described
herein, while still obtaining the beneficial results of the present
invention. It will also be apparent that some of the desired
benefits of the present invention can be obtained by selecting some
of the features of the present invention without utilizing other
features. Accordingly, those who work in the art will recognize
that many modifications and adaptations to the present invention
are possible and can even be desirable in certain circumstances and
are a part of the present invention. Thus, the following
description is provided as illustrative of the principles of the
present invention and not in limitation thereof.
[0043] As used throughout, the singular forms "a," "an" and "the"
include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to "a" component can
include two or more such components unless the context indicates
otherwise. Also, the words "proximal" and "distal" are used to
describe items or portions of items that are situated closer to and
away from, respectively, a user or operator such as a surgeon.
Thus, for example, the tip or free end of a device may be referred
to as the distal end, whereas the generally opposing end or handle
may be referred to as the proximal end.
[0044] Ranges can be expressed herein as from "about" one
particular value, and/or to "about" another particular value. When
such a range is expressed, another aspect includes from the one
particular value and/or to the other particular value. Similarly,
when values are expressed as approximations, by use of the
antecedent "about," it will be understood that the particular value
forms another aspect. It will be further understood that the
endpoints of each of the ranges are significant both in relation to
the other endpoint, and independently of the other endpoint.
[0045] As used herein, the terms "optional" or "optionally" mean
that the subsequently described event or circumstance may or may
not occur, and that the description includes instances where said
event or circumstance occurs and instances where it does not.
[0046] Presented herein are systems, tools, and methods for
supporting adjacent vertebrae of the spine, for example, as part of
interbody spinal fusion surgery. Although the systems, tools, and
methods are presented herein in the context of posterior lumbar
interbody fusion (PLIF), direct lateral interbody fusion (DLIF),
and transforaminal lumbar interbody fusion (TLIF), the assemblies
and techniques may be useful in a variety of therapeutic
contexts.
[0047] In one aspect, a cage assembly for the stabilization of an
intervertebral space during a spinal fusion procedure is presented.
As described herein, the cage assembly may comprise an expander
such as an expansion screw or a shim which, when inserted,
selectively expands the body of the cage assembly to a desired
size. The cage assembly may include one or more openings or windows
for receiving bone fusion material. The bone fusion material may
comprise, for example and without limitation, autologous bone,
allograft bone, bone substitute, osteoinductive agent, and/or bone
cement. The cage assembly may also include a plug or cap to contain
the bone fusion material and to add strength to the trailing side
of the cage in weight bearing.
[0048] In one aspect, a cage assembly 1000 may include a generally
elongate cage body 1010, an expander 1032, and an insertion tool
1060, as shown in FIG. 1A.
[0049] The cage body 1010 may be generally rectangular in
cross-section. The body 1010 may include an upper portion 1012 and
a lower portion 1018. The outer surfaces of the two portions 1012,
1018 may be ridged or grooved, laterally, as shown. The two
portions 1012, 1018 may be joined together by a pin-in-slot joint
or another type of hinge 1070 near the proximal end. The space
between the two portions 1012, 1018 may form an internal cavity,
space, or channel 1020 that extends lengthwise through the cage
body 1010. The cage body 1010 may also include one or more openings
or windows 1050 for receiving bone fusion material.
[0050] As illustrated in FIG. 1A and FIG. 1B, the expander 1032 may
be a keyed shim. Referring to the perspective view in FIG. 1A, the
shim has "key" on its distal portion. In this particular aspect,
the key is generally conical in cross-section with a rectangular or
square end, like the head of a bolt, and tapered on both sides. The
key shape on the distal portion may be sized and shaped to fit
within a distal cavity 1030, as shown in Section A-A. In one
aspect, the expander 1032 may include a set of keyed shims, each
key having a discrete size and shape. The cage body 1010 may also
include a number of cage bodies, each with a distal cavity 1030
having a different size and shape. The size and shape of the key,
together with its matching distal cavity 1030, may be used to
create a cage body 1010 that opens to a desired height and angular
orientation.
[0051] Referring again to the perspective view in FIG. 1A, the
proximal end of the keyed shim may include a proximal portion 1078,
which can be seen through the window 1050 in the upper portion
1012. The proximal portion 1078 of the shim may include a socket or
other feature for receiving the distal end of an insertion tool
1060. The tool may be used to pull the keyed shim 1032 proximally
until the key slides into the distal cavity. One aspect of a keyed
shim 1032 is also illustrated in FIG. 2. As shown, the proximal
portion 1078 may be generally cylindrical in shape and may be
suitable for grasping by the distal end of an insertion tool. The
keyed shim 1032, as shown, may also include side rails that are
sized and shaped to engage with interior portions of the cage body
1010.
[0052] The insertion tool 1060, as shown in FIG. 1B, may include a
cannula 1062 and a drive rod 1068. The distal end of the drive rod
1068 may include a specialized head or other tool for grasping or
otherwise engaging the proximal portion 1078 of the keyed shim;
e.g., a threaded portion. Once engaged, the drive rod 1068 may be
used to pull the keyed shim proximally, or push it distally, into a
desired position. Alternatively, the threaded rod may be rotated in
order to actuate a change in the position of the expander 1032 to
the desired position.
[0053] As shown in FIG. 1B, the expander 1032 or keyed shim, when
pulled proximally and into the distal cavity 1030, will cause the
two portions 1012, 1018 of the cage body 1010 to expand or spread
open. The pin-in-slot joint or hinge 1070 may allow the two
portions 1012, 1018 to expand or move vertically relative to one
another, while also allowing the two portions 1012, 1018 to rotate
about the hinge 1070 thereby changing the angle of the upper
portion 1012 and the bottom portion 1018 of the body. In this
aspect, the keyed shim 1032 may induce an angular relationship in
which the distal, or leading end of the cage body 1010 becomes more
open than the proximal, or trailing end. The cage body 1010, as
shown, may also include a set screw 1042 for insertion into the
proximal portion 1078 of the keyed shim. The drive rod 1068 or
another tool inserted through the cannula 1062 may be used to
rotate or otherwise drive the set screw 1042 into position. The set
screw 1042, in one aspect, may be sized and shaped to retain the
expander 1032 firmly within its final position, such that the
expander 1032 will not retreat or otherwise "back out" unless
purposely driven by a tool, also aiding in containment of the
fusion material within the cage assembly and strengthening the
proximal wall of the construct.
[0054] In use, the cage assembly 1000 may be inserted using an
insertion tool 1060 into an intervertebral space; for example, in
the lumbar region of the spine. A drive rod 1068 or other tool may
be used to grasp or otherwise engage with a proximal portion 1078
of the expander 1032, and pull the expander 1032 proximally until
its distal "key" is seated within a distal cavity 1030. Section B-B
of FIG. 1B shows the key of the expander 1042 seated within the
distal cavity 1030.
[0055] In certain exemplified aspects, the cage assembly 1000
comprises means to prevent the separation of the upper portion 1012
and the lower portion 1018 prior to expansion. In one aspect, the
distal portion 1080 of the expander 1032 defines at least one
substantially longitudinal slot, groove, or recess 1082. As shown
in the figures, the distal portion of the expander can define a
slot, groove, or recess on either side surface 1084. In this
aspect, the distal end 1113 of the upper portion 1012 and the
distal end 1119 of the lower portion 1018 each comprise a tongue
1120, 1122 sized such that both tongues can slide into and be
retained within one of the recesses 1082 defined in the distal
portion of the expander. The upper and lower portion can also have
bilateral tongues, as shown in the figures. Referring to FIGS. 5
and 6, in the unexpanded position, the tongues from both the upper
and lower portion are retained within the recess(es) by portions of
the expander. This permits insertion of the cage without the
potential of the premature separation of the upper and lower
portions. As the expander is moved proximately, the recess is moved
proximately, while the tongues remain unmoved, essentially
disengaging the tongues and recesses. Once the expander is moved
sufficiently, the tongues disengage from the recess, enabling the
upper and lower portions to expand as designed.
[0056] In another exemplified aspect, as illustrated in FIGS. 10
and 11, the upper and lower portions can comprise a tongue, pin, or
hook 1120, 1122 positioned on each of their inner surfaces 1114,
1117. In this aspect, the distal portion of the expander defines a
recess, slot, or hollow corresponding to each tongue, pin or hook
such that, when the cage is in the unexpanded position, the hooks
of the upper and lower portions are retained within the slots in
the distal portion of the expander. As the expander is moved
proximately, the slots are also moved proximately, while the hooks
remain unmoved, essentially disengaging the hooks and slots and
permitting expansion of the upper and lower portions.
[0057] In still another aspect, the upper and lower portions may be
bonded together in a temporary fashion so they do not splay during
insertion. For instance, a portion of the lower portion may be
ultrasonically welded, glued, or otherwise bonded to a portion of
the upper portion. Then, after insertion, the bond can be broken
during and by the expansion of the upper and lower portions. It is
also contemplated that the bond can be between the upper and/or
lower portion and the insert.
[0058] Bone fusion material may be inserted into the one or more
windows 1050 into the cage body 1010 as well as through the
aperture in the proximal end 1078 of the expander, and thereby into
the proximity of the surrounding bony structures, in order to
promote fusion and to further secure the cage assembly 1000 in
place.
[0059] Either before or after placement of the bone fusion
material, a cap or set screw 1042 may be inserted (using a drive
rod 1068 or another tool inserted through the cannula 1062) into
the proximal portion 1078 of the expander. The set screw 1042 helps
contain the bone fusion material and also strengthens the proximal
end wall of the cage body 1010.
[0060] In another aspect of the invention, as shown in FIGS. 15-23,
the expandable cage comprises a cage body 1010 having an upper
portion 1012 and a lower portion 1018. The upper portion and lower
portion are connected and define an internal space 1030. In this
aspect, the trailing end of the elongate expander defines an
aperture 1034 in communication with the internal space.
[0061] In this exemplified aspect, the elongate expander is
positioned at least partially within the internal space 1030 such
that translation of the elongate expander proximally toward the
trailing end expands the cage body by separating the at least a
portion of the upper portion from at least a portion of the lower
portion. In one aspect, the trailing end of the elongate expander
is cannulated and has internal threads. The internal threads are
configured to engage the external threads of an actuating screw
1090. The actuating screw 1090 engages the proximal portion of the
elongate expander. Rotation of the actuating screw in a first
direction moves the elongate expander proximally and rotation of
the actuating screw in a second direction moves the elongate
expander distally.
[0062] In another aspect, the cage body comprises a shoulder 1100
substantially adjacent the trailing end. In an exemplified aspect,
the shoulder defines an orifice 1110 configured for receipt of the
actuating screw 1090. The actuating screw comprises a head 1095
having a head diameter 1096 that is larger than the orifice
diameter 1115. It is understood that the term shoulder can me a
unitary structure or a plurality of shoulders. In this aspect,
rotating the actuating screw in the first direction until the cage
body is in the expanded position sandwiches at least a portion of
the shoulder between portions of the screw head and the proximal
portion of the elongate expander. This action substantially locks
the expander and the upper and lower portions of the cage body into
position.
[0063] The materials of the expandable cage can comprise stainless
steel, titanium, polymer (e.g., an organic polymer thermoplastic
such as polyether ether ketone (PEEK)), carbon fiber, or ceramic,
or other bio-compatible and sufficiently rigid material.
[0064] In one aspect, a portion of the upper portion of the cage
body substantially adjacent the trailing, or proximal end defines a
first trough 1106 and a portion of the lower portion of the cage
body substantially adjacent the trailing end defines a second
trough 1108. In this aspect, the actuating screw is positioned
within the aperture 1034.
[0065] In an exemplified aspect, the shoulder discussed above can
be formed by a first shim 1102 positioned within the first trough
and a second shim 1104 positioned within the second trough. In this
aspect, the first and second shims define an orifice 1110 having a
diameter 1115 and is substantially coaxial with the internal
passageway.
[0066] In one aspect, the cage body comprises a first material and
the first and second shim comprise a second material. In this
aspect, the second material is harder than the first material. In
one aspect, the first material is PEEK and the second material is
Titanium, although numerous combinations of materials are
contemplated.
[0067] Also presented herein is a method for inserting and
expanding a cage assembly within an intervertebral space in the
spine.
[0068] In use, the cage assembly 1000 may be inserted into an
intervertebral space; for example, in the lumbar region of the
spine. An expander 1032 may be inserted through the proximal
opening in the body 1010. The expander 1032 may be driven by a tool
so that it drives apart the two portions 1012, 1018 of the body
1010. In one aspect, the body 1010 is selectively expandable
because the expander 1032 may be inserted and/or counter-inserted
until the body 1010 achieves the size and shape desired by the
surgeon.
[0069] Bone fusion material may be inserted into the one or more
windows 1050 into the body 1010, and thereby into the proximity of
the surrounding bony structures, in order to further secure the
cage assembly 1000 in place. In the aspect having a cannulated
actuation screw, the bone fusion material may be inserted post
expansion via the internal passageway of the actuating screw.
[0070] In another aspect, a cap 1042 such as the cap screw shown in
FIG. 2B may be inserted into the proximal end of the body 1010. The
cap 1042 helps contain the bone fusion material and also
strengthens the proximal end wall of the cage body 1010.
[0071] Although several aspects of the invention have been
disclosed in the foregoing specification, it is understood by those
skilled in the art that many modifications and other aspects of the
invention will come to mind to which the invention pertains, having
the benefit of the teaching presented in the foregoing description
and associated drawings. It is thus understood that the invention
is not limited to the specific aspects disclosed herein above, and
that many modifications and other aspects are intended to be
included within the scope of the appended claims. Moreover,
although specific terms are employed herein, as well as in the
claims which follow, they are used only in a generic and
descriptive sense, and not for the purposes of limiting the
described invention, nor the claims which follow.
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