U.S. patent application number 13/414876 was filed with the patent office on 2012-09-27 for expandable interbody spacer.
This patent application is currently assigned to Alphatec Spine, Inc.. Invention is credited to William Reimels.
Application Number | 20120245691 13/414876 |
Document ID | / |
Family ID | 46877997 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120245691 |
Kind Code |
A1 |
Reimels; William |
September 27, 2012 |
EXPANDABLE INTERBODY SPACER
Abstract
An expandable intervertebral spacer includes a body, a proximal
end, and a distal end. The body includes quadrants that form a
substantially cylindrical shape in a first configuration and a
substantially cuboidal shape in a second configuration. Each
quadrant includes a ramp portion with a ramp and a landing and a
sliding portion with a sliding side and a foot. The ramp portion of
a first quadrant engages the sliding portion of a second quadrant.
The proximal end and the distal end couple with the plurality of
quadrants and transfer an actuating force to expand the body from
the first configuration to the second configuration.
Inventors: |
Reimels; William;
(Oceanside, CA) |
Assignee: |
Alphatec Spine, Inc.
Carlsbad
CA
|
Family ID: |
46877997 |
Appl. No.: |
13/414876 |
Filed: |
March 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61466729 |
Mar 23, 2011 |
|
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|
Current U.S.
Class: |
623/17.16 ;
606/86A |
Current CPC
Class: |
A61F 2/4611 20130101;
A61F 2002/30263 20130101; A61F 2002/30235 20130101; A61F 2002/30774
20130101; A61F 2002/30553 20130101; A61F 2002/30593 20130101; A61F
2002/30019 20130101; A61F 2/4465 20130101; A61F 2002/30545
20130101; A61F 2002/3097 20130101; A61F 2002/30224 20130101; A61F
2002/30579 20130101; A61F 2002/30873 20130101; A61F 2/446
20130101 |
Class at
Publication: |
623/17.16 ;
606/86.A |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61B 17/88 20060101 A61B017/88 |
Claims
1. An expandable intervertebral spacer, comprising: a body having
quadrants that form a substantially cylindrical shape in a first
configuration and a substantially cuboidal shape in a second
configuration, wherein each quadrant includes a ramp portion with a
ramp and a landing; and a sliding portion with a sliding side and a
foot; wherein the ramp portion of a first quadrant engages the
sliding portion of a second quadrant, and a proximal end and a
distal end coupled with the quadrants and configured to transfer an
actuating force to expand the body from the first configuration to
the second configuration.
2. The spacer of claim 1, wherein the quadrants are integrally
formed within the body.
3. The spacer of claim 1, wherein the ramp of the first quadrant
engages a sliding side of the second quadrant in the first
configuration.
4. The spacer of claim 1, wherein the landing of the first quadrant
engages a foot of the second quadrant in the second
configuration.
5. The spacer of claim 1, further comprising a plurality of
integral linking members coupling the proximal and distal ends with
the body.
6. The spacer of claim 1, further comprising a plurality of
integral linking members that conform to the cylindrical shape in
the first configuration and plastically deform when the body
transforms to the second configuration.
7. The spacer of claim 1, further comprising a tension member
coupling the first quadrant and the second quadrant.
8. The spacer of claim 1, further comprising a tension member
within the body having a first length in the first configuration
and a second length greater than the first length in the second
configuration.
9. The spacer of claim 1, further comprising an integral tension
member within the body that provides tension between the first
quadrant with the second quadrant as the body expands from the
first configuration to the second configuration.
10. The spacer of claim 1, further comprising a threaded aperture
within at least one of the proximal end and the distal end.
11. An apparatus for expanding an intervertebral space, comprising:
a plurality of interlocking sections integrally formed in a body
and configurable between a first geometry and a second geometry;
and a proximal end and a distal end integrally formed in the body
and configured to transfer an applied force to configure the body
between the first geometry and the second geometry.
12. The apparatus of claim 11, wherein a first of the interlocking
sections slidably engages a second of the interlocking sections as
the body transforms from the first geometry to the second
geometry.
13. The apparatus of claim 11, wherein the plurality of
interlocking sections includes four quadrants that form a
cylindrical arrangement in the first geometry and a cuboidal
arrangement in the second geometry.
14. The apparatus of claim 11, wherein at least one of the
interlocking sections includes a sliding quadrant and at least one
of the interlocking sections includes a ramp quadrant.
15. The apparatus of claim 11, wherein a sliding side of a first
interlocking section slides along a ramp of an adjacent second
interlocking section as the applied force compresses the proximal
and distal ends.
16. The apparatus of claim 11, wherein a first of the interlocking
sections includes a first sliding quadrant linked to a first ramp
quadrant by a first bridge.
17. The apparatus of claim 11, further comprising a tension member
integrally formed in the body links two of the interlocking
sections.
18. The apparatus of claim 11, wherein the first geometry fills a
first volume and the second geometry fills a second volume greater
than the first volume.
19. The apparatus of claim 11, wherein one of the proximal and
distal ends includes an attachment feature and the other of the
proximal and distal ends includes an anti-rotation feature.
20. The apparatus of claim 11, further comprising a tension member
linking two of the interlocking sections that plastically deforms
when the interlocking sections transform from the first
configuration to the second configuration.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/466,729, filed Mar. 23, 2011, and is
incorporated herein by reference in its entirety.
FIELD
[0002] The present disclosure generally relates to the field of
spinal orthopedics, and more particularly to intervertebral
implants and interbody devices.
BACKGROUND
[0003] The spine is a flexible column formed of a plurality of
bones called vertebrae. The vertebrae are hollow and stacked one
upon the other, forming a strong hollow column for support of the
cranium and trunk. The hollow core of the spine houses and protects
the nerves of the spinal cord. The different vertebrae are
connected to one another by means of articular processes and
intervertebral, fibrocartilaginous bodies. Various spinal disorders
may cause the spine to become misaligned, curved, and/or twisted or
result in fractured and/or compressed vertebrae. It is often
necessary to surgically correct these spinal disorders.
[0004] The intervertebral fibro-cartilages are also known as
intervertebral discs and are made of a fibrous ring filled with
pulpy material. The discs function as spinal shock absorbers and
also cooperate with synovial joints to facilitate movement and
maintain flexibility of the spine. When one or more discs
degenerate through accident or disease, nerves passing near the
affected area may be compressed and are consequently irritated. The
result may be chronic and/or debilitating back pain. Various
methods and apparatus have been designed to relieve such back pain,
including spinal fusion using an interbody spacer or suitable graft
using techniques such as Anterior Lumbar Interbody Fusion (ALIF),
Posterior Lumbar Interbody Fusion (PLIF), or Transforaminal Lumbar
Interbody Fusion (TLIF) surgical techniques. The implants used
in-these techniques, also commonly referred to as interbody
spacers, are placed in the inter-discal space between adjacent
vertebrae of the spine. Many times an exterior plate is used in
conjunction with the interbody spacer to hold the adjacent
vertebrae while the fusion occurs.
[0005] Ideally, the interbody spacer should stabilize the
intervertebral space and allow fusion of the adjacent vertebrae.
Moreover, during the time it takes for fusion to occur, the
interbody spacer should have sufficient structural integrity to
withstand the stress of maintaining the space without substantially
degrading or deforming and have sufficient stability to remain
securely in place prior to actual bone fusion.
[0006] Interbody spacers have been used successfully to fuse
adjoining vertebral bodies to restore anatomical positioning and
eliminate pain caused by a bulging disc. Spacers fit into the disc
space and support the vertebral bodies allowing bone fusion to
occur between the joint surfaces. The primary technical advances in
this market have been in the methods of minimally invasive
interbody delivery. Anterior delivery and more recently medial
delivery have reduced morbidity and allowed faster patient
rehabilitation.
[0007] One major obstacle remaining in perfecting these procedures
is reducing the displacement of soft tissue structures and the size
of tissue dissections to place the relatively large interbodies
necessary to properly support the spinal column during the bone
remodeling process. Large interbodies also require extensive site
preparation and sizing prior to placement. This site prep can cause
increased trauma to surrounding structures as instrumentation is
manipulated in the disc space.
SUMMARY
[0008] An expandable intervertebral spacer includes a body, a
proximal end, and a distal end. The body includes quadrants that
form a substantially cylindrical shape in a first configuration and
a substantially cuboidal shape in a second configuration. Each
quadrant includes a ramp portion with a ramp and a landing and a
sliding portion with a sliding side and a foot. The ramp portion of
a first quadrant engages the sliding portion of a second quadrant.
The proximal end and the distal end couple with the quadrants and
transfer an actuating force to expand the body from the first
configuration to the second configuration.
[0009] In other features, the quadrants are integrally formed
within the body. The ramp of the first quadrant engages a sliding
side of the second quadrant in the first configuration. The landing
of the first quadrant engages a foot of the second quadrant in the
second configuration. A plurality of integral linking members
couple the proximal and distal ends with the body. A plurality of
integral linking members conform to the cylindrical shape in the
first configuration and plastically deform when the body transforms
to the second configuration. A tension member couples the first
quadrant and the second quadrant. A tension member within the body
includes a first length in the first configuration and a second
length greater than the first length in the second configuration.
An integral tension member within the body provides tension between
the first quadrant with the second quadrant as the body expands
from the first configuration to the second configuration. A
threaded aperture is disposed within at least one of the proximal
end and the distal end.
[0010] An apparatus for expanding an intervertebral space includes
a plurality of interlocking sections, a proximal end, and a distal
end all integrally formed in a body. The plurality of interlocking
sections integrally formed in the body is configurable between a
first geometry and a second geometry. The proximal end and the
distal end integrally formed in the body are configured to transfer
an applied force to configure the body between the first geometry
and the second geometry.
[0011] In other features, a first of the interlocking sections
slidably engages a second of the interlocking sections as the body
transforms from the first geometry to the second geometry. The
plurality of interlocking sections includes four quadrants that
form a cylindrical arrangement in the first geometry and a cuboidal
arrangement in the second geometry. At least one of the
interlocking sections includes a sliding quadrant and at least one
of the interlocking sections includes a ramp quadrant. A sliding
side of a first interlocking section slides along a ramp of an
adjacent second interlocking section as the applied force
compresses the proximal and distal ends. A first of the
interlocking sections includes a first sliding quadrant linked to a
first ramp quadrant by a first bridge. A tension member integrally
formed in the body links two of the interlocking sections. The
first geometry fills a first volume and the second geometry fills a
second volume greater than the first volume. One of the proximal
and distal ends includes an attachment feature and the other of the
proximal and distal ends includes an anti-rotation feature. A
tension member linking two of the interlocking sections plastically
deforms when the interlocking sections transform from the first
configuration to the second configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of an expandable interbody
spacer in a first configuration according to the principles of the
present disclosure.
[0013] FIG. 2 is a perspective view of the expandable interbody
spacer begins to expand from the first configuration to a second
configuration according to the principles of the present
disclosure.
[0014] FIG. 3 is a perspective view of the expandable interbody
spacer prior to full expansion in the second configuration
according to the principles of the present disclosure.
[0015] FIG. 4 is a perspective view of the expandable interbody
spacer in the second configuration according to the principles of
the present disclosure.
[0016] FIG. 5 is an elevational side view of the expandable
interbody spacer in the second configuration according to the
principles of the present disclosure.
[0017] FIG. 6 is an elevational side view of the expandable
interbody spacer illustrating deformation of a tension member of
the interbody spacer according to the principles of the present
disclosure.
[0018] FIG. 7 is an elevational side view of the proximal end of
the expandable interbody spacer in the first configuration
according to the principles of the present disclosure.
[0019] FIG. 8 is an elevational side view of the proximal end of
the expandable interbody spacer in the second configuration
according to the principles of the present disclosure.
DETAILED DESCRIPTION
[0020] The use of a smaller interbody which may be expanded in-situ
allows the possibility of performing the surgery percutaneously
with minimal disruption to tissues surrounding the surgical site
and intervening soft tissue structures. The expandable interbody
spacer of the present disclosure includes features that reduce
displacement of soft tissue and structures during placement of the
interbody while providing support to the vertebrae while bone
fusion occurs. The spacer includes a first configuration that may
be a substantially cylindrical geometry with dimensions that allow
percutaneous insertion of the spacer between the vertebrae. Once
the spacer is positioned in a desired location between the
vertebrae, the spacer may be expanded to a second configuration.
The second configuration may be a substantially cuboidal geometry
with dimensions that allow the spacer to fill the disc space and
provide support to the adjacent vertebrae while bone fusion occurs.
The second configuration provides rigid support between the
adjacent vertebrae that withstands compressive forces.
[0021] The expandable interbody spacer includes a system and method
of expanding a compact cylindrical form into a cuboidal shaped
implant which has the necessary structural integrity to support the
load of the spinal column during bone remodeling and fusion. This
design uses positive cam action of sections or quadrants as they
slide pass one another to expand the implant. The use of cam action
allows the precise control of the rate of expansion and ensures
each segment deploys evenly.
[0022] Embodiments of the invention will now be described with
reference to the Figures, wherein like numerals reflect like
elements throughout. The terminology used in the description
presented herein is not intended to be interpreted in any limited
or restrictive way, simply because it is being utilized in
conjunction with detailed description of certain specific
embodiments of the invention. Furthermore, embodiments of the
invention may include several novel features, no single one of
which is solely responsible for its desirable attributes or which
is essential to practicing the invention described herein. The
words proximal and distal are applied herein to denote specific
ends of components of the instrument described herein. A proximal
end refers to the end of an instrument nearer to an operator of the
instrument when the instrument is being used. A distal end refers
to the end of a component further from the operator and extending
towards the surgical area of a patient and/or the implant.
[0023] Referring now to FIGS. 1-8, an expandable interbody spacer
100 of the present disclosure includes a system of sections or
quadrants and linking members that expand from a substantially
cylindrical shape in a first configuration to a substantially
cuboidal shape in a second configuration. The quadrants may be
substantially rigid in construction and the linking members may be
semi-rigid, flexible, and/or plastically deformable. The spacer 100
may include a substantially cylindrical shape to enable insertion
through a circular, percutaneous surgical opening in a patient. For
example, the spacer 100 may include a proximal end 102 having a
circular profile, a cylindrical body 104, and a distal end 106 also
having a circular profile. The body 104 may be segmented into the
system of quadrants and linking members as described herein. The
quadrants and linking members may be formed in the body 104 from a
unitary construction. That is, the quadrants and linking members
may be integral and continuous with the body 104. For example, the
quadrants and linking members may be cut using laser cutting
techniques or other methods in order to retain a unitary
construction. In other examples, the quadrants and linking members
may be joined together by other methods.
[0024] FIG. 1 illustrates the spacer 100 in the first configuration
prior to percutaneous insertion into the patient. The body 104 of
the spacer 100 may be described with reference to multiple sections
or quadrants, each of which includes similar subsections or
components. For example, a first quadrant of the body 104 includes
a first sliding portion 108 coupled with a first ramp portion 110
that together extend the length of the body 104. The first sliding
portion 108 and the first ramp portion 110 include curved outer
surfaces corresponding to the overall cylindrical shape of the
spacer 100 when in the first configuration. The first ramp portion
110 includes a ramp 112, a landing 114, and a compressive side 116.
The first ramp portion 110 may include additional sides to form a
substantially irregular pentagonal shape. The ramp 112 may include
an angle 117 relative to the circumference of the body 104. The
landing 114 extends from the ramp 112 and substantially parallel to
a longitudinal axis 115 of the body 104. The compressive side 116
extends from the landing 116 substantially parallel to the
circumference of the body 104. A compressive linking member 118 may
flexibly couple the compressive side 116 to the distal end 106 of
the spacer 100. Various tabs 120 may also extend from the
compressive side 116 and towards the distal end 106.
[0025] The first sliding portion 108 includes a sliding side 122, a
foot 124, and a central side 126. The first sliding portion 108 may
include additional sides that may also form a substantially
irregular pentagonal or hexagonal shape. The sliding side 122
includes the same angle 117 relative to the circumference of the
body 104 and is substantially parallel to the ramp 112. The foot
124 extends from the sliding side 122 substantially parallel to the
axis 115 of the body 104. The central side 126 extends from the
foot 124 towards a first bridge 128. The first bridge 128 may link
the first sliding quadrant 108 to the first ramp portion 110. The
first bridge 128 may be substantially rigid to withstand
compressive forces applied to the compressive side 116 of the first
ramp portion 110 so as not to buckle between the first sliding
portion 108 and the first ramp portion 110. The first bridge 128
may be integral and continuous with the first sliding portion 108
and the first ramp portion 110.
[0026] Continuing with FIG. 1, a second quadrant of the body 104
includes a second sliding portion 208 coupled with a second ramp
portion 210 that together extend the length of the body 104. The
second sliding portion 208 and the second ramp portion 210 include
curved outer surfaces corresponding to the overall cylindrical
shape of the spacer 100. The second ramp portion 210 includes a
ramp 212, a landing 214, and a compressive side 216. The second
ramp portion 210 may include additional sides and feet that may
form a substantially irregular pentagonal shape. The ramp 212
extends along the surface of the body 104 at a similar angle as the
angle 117 relative to the circumference of the body 104. The
landing 214 extends from the ramp 212 substantially parallel to the
axis 115 of the body 114. The compressive side 216 extends from the
landing 214 substantially parallel to the circumference of the body
214. A compressive member 118 couples the compressive side 216 to
the proximal end 102 of the spacer 100. Various tabs 120 may also
extend from the compressive side 216 and towards the proximal end
102.
[0027] The second sliding portion 208 includes a sliding side 222,
a foot 224, and a central side 226. The second sliding portion 208
may include additional sides that may also form a substantially
irregular pentagonal or hexagonal shape. The sliding side 222
extends along the surface of the body 104 at an angle similar to
the angle 117 and substantially parallel to the ramp 112. The
sliding side 222 is configured to slide relative to the ramp 112
when the spacer 100 transforms from the first configuration to the
second configuration. The foot 224 extends from the sliding side
222 substantially parallel to the longitudinal axis 115 of the body
104. The central side 226 extends from the foot 224 towards a
second bridge 228. The second bridge 228 may link the second
sliding portion 208 to the second ramp portion 210. The second
bridge 228 may be substantially rigid to withstand compressive
forces applied to the compressive side 216 of the second ramp
portion 210 so as not to buckle between the second sliding portion
208 and the second ramp portion 210. The second bridge 228 may be
integral and continuous with the second sliding portion 208 and the
second ramp portion 210.
[0028] A first tension member 130 extends from the first bridge 128
to the second bridge 228 and couples the first quadrant and the
second quadrant of the body 104. The tension member 130 may be
formed by the central sides 126 and 226 of the first sliding
portion 108 and the second sliding portion 208 respectively. The
tension member 130 may include flexible or semi-rigid regions that
enable the tension member 130 to elastically deflect, stretch, or
bend as the spacer 100 transforms from the first configuration to
the second configuration as illustrated in FIGS. 2-4. The tension
member 130 may provide resistive force or tension that provides an
interference fit between the landings and feet as described herein.
Once in the second configuration, the tension member 130 may
include rigid characteristics to withstand compressive forces
associated with placement in the intervertebral disc space in the
second configuration. For example, plastic deformation of the
tension member 130 may alter the physical characteristics of the
constituent material and increase rigidity.
[0029] The body 104 may include additional quadrants having sliding
portions and ramp portions similar to the first and second
quadrants described above, such as a third quadrant and a fourth
quadrant, that are substantially identical to and/or mirror images
of the first and second quadrants. Each adjacent quadrant is linked
by an additional tension member that extends from the bridge of one
quadrant to the bridge of another quadrant. In the present example,
four quadrants that each includes a sliding portion, a ramp
portion, and a bridge may be linked by four tension members to
expand from the cylindrical first configuration as illustrated in
FIGS. 1 and 7 to form a substantially cuboidal second configuration
as illustrated in FIGS. 4 and 8. Generally, the first
configuration, such as the cylindrical arrangement, includes a
first volume corresponding to the diameter D2 and length of the
cylinder. The second configuration, such as the cuboidal
arrangement, includes a second volume corresponding to the length
of the spacer 100 and an expanded width W and height H. The second
volume is greater than the first volume.
[0030] For purposes of expediency and clarity, actuation of the
spacer 100 will be described with reference to the first and second
quadrants only. However, one skilled in the art may appreciate that
the same interaction between sliding portions and ramp portions
applies to the additional third and fourth quadrants. Furthermore,
one skilled in the art may appreciate that any suitable number of
sections may be included in the spacer 100 to achieve various
geometric configurations.
[0031] Referring back to FIG. 1, in the first configuration, the
first ramp portion 110 and the second sliding portion 208 are
adjacent to one another and the second ramp portion 210 and the
first sliding portion 108 are adjacent to one another. The outer
surface of the body 104 may be substantially uniform as the sides
of all the sections are substantially in alignment. The proximal
end 102 of the spacer 100 may include a first aperture 132 for
insertion of a deployment tool, such as the exemplary deployment
tool provided in U.S. Publication No. 2009/0318928, incorporated
herein by reference. The deployment tool may pass through the
center of the spacer 100 and exit through the distal end 106 via a
second aperture 136. Various attachment features of the deployment
tool may couple with the proximal end 102 and or the distal end 106
to enable percutaneous insertion into the patient. For example,
threads 138 on the proximal end and threads 140 on the distal end
104 may provide for attachment of the deployment tool. Once the
spacer 100 has been inserted and positioned within the
intervertebral space between two vertebrae, the deployment tool may
actuate to deploy and expand the spacer 100 by applying a
compressive force F1 to either or both ends of the spacer 100 as
shown in FIGS. 2 and 3.
[0032] Continuing now with FIG. 2, as the force F1 acts on the ends
102 and 106 of the spacer 100, each of the compressive members 118
begins to push against the first and second compressive sides 116
and 216 of the first and second ramp portions 110 and 210
respectively. The ramp 112 of the first ramp portion 110 slidably
engages with the sliding side 222 of the second sliding portion
208. Likewise, the ramp 212 of the second ramp portion 210 slidably
engages with the sliding side 122 of the first sliding portion 108.
The compressive force F1 forces the ends 102 and 106 towards each
other and the sliding engagement of the sliding portions and ramp
portions guides the movement of the first and second sections
relative to each other. Thus, the second section begins to move
away from the first section causing the spacer 100 to expand. The
tension member 130 may begin to elastically bend near the first
bridge 128 and the second bridge 228. The foot 224 of the second
sliding portion 208 begins to move away from the first bridge 128
and the foot 124 of the first sliding portion 108 begins to move
away from the second bridge 228.
[0033] Continuing now with FIG. 3, as the foot 124 of the first
sliding portion 108 approaches the landing 214 of the second ramp
portion 210, the tension member 130 continues to deform. The
tension member may provide some counterforce F2 that pulls the
first sliding portion 108 and the second ramp portion 210 together.
The counterforce F2 may cause some interference between the foot
124 of the first sliding portion 108 and the landing 214 of the
second ramp portion 210 as the spacer 100 expands to the second
configuration. For example, the tension member 130 may elastically
stretch while also resisting the movement of the second ramp
portion 210 away from the first sliding portion 108. Similarly, as
the foot 224 of the second sliding portion 208 approaches the
landing 114 of the first ramp portion 110, the counterforce F2 may
pull the second sliding portion 208 and the first ramp portion 110
together. The counterforce F2 may cause some interference between
the foot 224 of the second sliding portion 208 and the landing 114
of the first ramp portion 110. For example, the interference
between each foot and landing interface may require an increase in
the force F1 applied to the proximal end 102 and distal end 106 of
the spacer 100 in order to fully deploy the spacer 100. The
interference may provide tactile feedback to the surgeon as
indication of full deployment.
[0034] Referring now to FIG. 4, as the feet 124 and 224 of each
sliding portion 108 and 208 clear the landings 114 and 214 of each
ramp portion 110 and 210, the first and second sections of the body
104 may be fully expanded in the second configuration. Thus, the
feet 124 and 224 and landings 114 and 214 mate to create a stable,
4-sided expanded structure in the second configuration. The
alignment of each portion to a corresponding ramp portion provides
stability and support to withstand compressive forces associated
with inter-vertebral implantation. The supporting members 130 may
provide additional support to the spacer 100 in the second
configuration.
[0035] Referring now to FIG. 5, a side view of the spacer 100 in
the second configuration illustrates additional features of the
third and fourth quadrants of the spacer 100. The third section of
the spacer 100 includes a third sliding portion 308 coupled with a
third ramp portion 310 by a third bridge 328. The fourth section
includes a fourth sliding portion 408 coupled with a fourth ramp
portion 410 by a fourth bridge 428. A foot 424 of the fourth
sliding portion 408 contacts a landing 314 of the third ramp
portion 310. A foot 324 of the third sliding portion 308 contacts a
landing 414 of the fourth ramp portion 410. Contact between each
pair of feet and landings provides rigid support to adjacent
vertebrae after deployment within the intervertebral disc space. A
tension member 330 links the third bridge 328 with the fourth
bridge 428 and may provide additional support. Additional tension
members 230 and 430 link the second bridge 228 (not shown) with the
third bridge 328 and the fourth bridge 428 with the first bridge
128 (not shown). In FIG. 6, another side view of the spacer in the
second configuration illustrates how another tension member 330'
may deform during transition from the first configuration to the
second configuration. For example, the tension member 330' may flex
more than the tension members illustrated in FIGS. 1-5 and begin to
resemble an "S" shape.
[0036] Referring now to FIGS. 7 and 8, side views looking into the
proximal end 102 of the spacer 100 illustrate the cylindrical first
configuration and the expanded cuboidal second configuration in
greater detail. In FIG. 7, the spacer 100 is shown in the
non-deployed first configuration. Thus, the proximal end 102 and
the aperture 132 are the only visible features of the spacer 100.
The aperture 132 may include an inner diameter D1. The inner
diameter D1 may be configured for attachment of the deployment tool
or other suitable device. The spacer 100 may include an outer
diameter D2 prior to deployment that is suitable for percutaneous
insertion into the patient. Once the spacer 100 has been inserted
into the intervertebral disc space, the deployment tool (not shown)
or other suitable device may be used to apply the force F1 as
illustrated in FIGS. 2 and 3. In FIG. 8, the spacer 100 expands to
the deployed second configuration, and the sliding portions 108 and
308 and ramp portions 210 and 410 thus radially expand away from
the axial center of the spacer 100. Once the sliding portions 108
and 308 and ramp portions 210 and 410 reach the second
configuration, the spacer 100 may include a width W and a height H
that are greater than the outer diameter D2 of the spacer 100.
[0037] In operation, the spacer 100 may be inserted into the
intervertebral disc space between two vertebrae using a deployment
tool. An exemplary deployment tool may be found in commonly
assigned U.S. Pub. No. 2010/0228301, entitled "Attachment Device
and Methods of Use," to Greenhalgh et al. which is incorporated
herein by reference. In some cases, the disc space may include a
degenerated disc or other disorder that may require a partial or
complete discectomy prior to insertion of the spacer 100. The
deployment tool may engage with the proximal end 102 and the distal
end 106 of the spacer 100. For example, the deployment tool may
engage with the threads 138 and 140 on at least one of the proximal
end 102 and the distal end 106 respectively. At one end, such as
the distal end 106, the deployment tool may prevent rotation of the
spacer 100. At the other end, such as the proximal end 102, the
deployment tool may engage the thread 138 to pull the proximal end
102 and distal end 106 together. As the deployment instrument
applies the force F1, the spacer 100 gradually expands as described
above. The deployment instrument may increase the amount of force
F1 as interference between each foot and landing resists expansion
of the spacer 100. The increase in the force F1 may provide tactile
feedback to the surgeon indicating near complete deployment of the
spacer 100. As each foot snaps onto its respective landing, the
force F1 may decrease quickly providing additional feedback that
the spacer 100 is fully deployed and structurally rigid.
[0038] Example embodiments of the methods and systems of the
present invention have been described herein. As noted elsewhere,
these example embodiments have been described for illustrative
purposes only, and are not limiting. Other embodiments are possible
and are covered by the invention. Such embodiments will be apparent
to persons skilled in the relevant art(s) based on the teachings
contained herein. Thus, the breadth and scope of the present
invention should not be limited by any of the above-described
exemplary embodiments, but should be defined only in accordance
with the following claims and their equivalents.
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