U.S. patent application number 11/120639 was filed with the patent office on 2006-11-02 for systems and methods for augmenting intervertebral discs.
This patent application is currently assigned to The Board of Trustees of the Leland Stanford Junior University. Invention is credited to Daniel H. Kim.
Application Number | 20060247776 11/120639 |
Document ID | / |
Family ID | 37235504 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060247776 |
Kind Code |
A1 |
Kim; Daniel H. |
November 2, 2006 |
Systems and methods for augmenting intervertebral discs
Abstract
Systems, devices and methods are provided for augmenting
intervertebral discs. The systems include implantable annulus
repair and augmentation devices as well as implantable prosthetic
materials for replacing a portion of or augmenting the annulus
and/or the nucleus pulposus. The systems further include
instruments for implanting the subject devices and materials in a
minimally invasive manner. The methods are directed to the
minimally invasive implantation of one or more of the subject
annulus repair devices and the prosthetic materials
concurrently.
Inventors: |
Kim; Daniel H.; (Mountain
View, CA) |
Correspondence
Address: |
BOZICEVIC, FIELD & FRANCIS LLP
1900 UNIVERSITY AVENUE
SUITE 200
EAST PALO ALTO
CA
94303
US
|
Assignee: |
The Board of Trustees of the Leland
Stanford Junior University
|
Family ID: |
37235504 |
Appl. No.: |
11/120639 |
Filed: |
May 2, 2005 |
Current U.S.
Class: |
623/17.12 ;
606/75 |
Current CPC
Class: |
A61F 2002/4628 20130101;
A61F 2002/4435 20130101; A61F 2002/4627 20130101; A61B 17/8836
20130101; A61F 2002/30179 20130101; A61F 2230/0058 20130101; A61F
2/442 20130101; A61F 2/4611 20130101; A61F 2220/0075 20130101; A61F
2002/30242 20130101; A61F 2002/30785 20130101; A61F 2002/30841
20130101; A61B 2017/00867 20130101; A61F 2230/0071 20130101; A61F
2002/30462 20130101; A61B 17/06166 20130101; A61F 2002/30579
20130101; A61B 17/7095 20130101; A61F 2002/30904 20130101; A61B
17/0483 20130101; A61F 2002/444 20130101 |
Class at
Publication: |
623/017.12 ;
606/075 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61B 17/84 20060101 A61B017/84 |
Claims
1. An implantable intervertebral disc augmentation system wherein
the intervertebral disc has a nucleus and an annulus, the system
comprising: at least one structure sized for implantation within
the disc at a defect site, wherein at least a portion of the
structure is in contact with the annulus upon implantation; and at
least one prosthetic material deliverable to within the defect
site, wherein the at least one structure is configured to provide
passage of the prosthetic material from outside the disc to within
at least a portion of the defect.
2. The intervertebral disc augmentation system of claim 1, wherein
the at least one structure has a planar configuration.
3. The intervertebral disc augmentation system of claim 1, wherein
the at least one planar structure comprises apertures to provide
passage of the prosthetic material
4. The intervertebral disc augmentation system of claim 1, wherein
the at least one structure has a pin configuration.
5. The intervertebral disc augmentation system of claim 4,
comprising a plurality of said pin structures extending between two
end plates.
6. The intervertebral disc augmentation system of claim 1, wherein
the at least one structure has a clip configuration.
7. The intervertebral disc augmentation system of claim 1, wherein
the at least one structure has a cylindrical configuration.
8. The intervertebral disc implant of claim 1, wherein the at least
one structure has an expanded configuration and an unexpanded
configuration.
9. The intervertebral disc implant of claim 8, wherein the at least
one structure is self-expanding upon implantation.
10. The intervertebral disc implant of claim 8, wherein the at
least one structure is actively expandable upon implantation.
11. The intervertebral disc implant of claim 1, wherein the
intra-annular space is between two adjacent lamellae.
12. The intervertebral disc implant of claim 1, wherein the at
least one prosthetic material comprises a hyrdogel.
13. The intervertebral disc implant of claim 1, wherein the at
least one prosthetic material has an initial flowable form and is
curable to a more solid form.
14. The intervertebral disc implant of claim 1, wherein the at
least one prosthetic material comprises two prosthetic
materials.
15. The intervertebral disc implant of claim 1, wherein the at
least one structure comprises a scaffolding.
16. A method of treating an intervertebral disc wherein the disc
includes a void within at least an intra-annular space within the
annulus of the disc, the method comprising: providing the system of
claim 1; implanting the at least one structure within the
intra-annular space; and delivering the prosthetic material into
the void.
17. The method of claim 16, wherein the step of implanting the at
least one structure comprises positioning the at least one
structure between two adjacent lamellae of the annulus.
18. The method of claim 16, wherein the void is naturally
occurring.
19. The method of claim 16, wherein the void is surgically
formed.
20. The method of claim 16, wherein the void is in a posterior
portion of the annulus.
21. The method of claim 16, wherein the void further comprises a
space within the nucleus of the disc.
22. The method of 16, wherein the at least one structure applies a
compressive force on the annulus upon implantation.
23. The method of claim 16, further comprising the steps of:
providing a delivery tool having a proximal end and a distal end;
inserting the delivery tool into the patient's back such the distal
end is disposed at or within the intra-annular space; and wherein
implanting the at least one structure comprises utilizing the
delivery tool.
24. The method of claim 16, wherein implanting the at least one
structure comprises delivering the at least one structure to the
intra-annular space in a low profile condition and expanding the at
least one structure along its length dimension.
25. An implantable intervertebral disc augmentation device, wherein
the intervertebral disc has a nucleus and an annulus, the device
comprising: a scaffolding structure sized for implantation within
the disc at a defect site within the annulus.
26. The device of claim 25, wherein the scaffolding structure is
configured to provide passage of at least one flowable prosthetic
material from outside the disc to within at least a portion of the
defect.
27. The device of claim 25, wherein the scaffolding structure
comprises a plurality of apertures.
28. The device of claim 25, wherein the scaffolding structure
comprises a plurality of struts.
29. The device of claim 25, further comprising at least one anchor
for securing the scaffolding within the defect site.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed towards the minimally
invasive repair of intervertebral discs.
BACKGROUND OF THE INVENTION
[0002] The spinal column is formed from a number of bony vertebral
bodies separated by intervertebral discs which primarily serve as a
mechanical cushion between the vertebral bones, permitting
controlled motions (flexion, extension, lateral bending and axial
rotation) within vertebral segments. The normal, natural
intervertebral disc is comprised of three components: the nucleus
pulposus ("nucleus"), the annulus fibrosis ("annulus"), and two
opposing vertebral end plates.
[0003] The two vertebral end plates are each composed of thin
cartilage overlying a thin layer of hard, cortical bone which
attaches to the spongy, richly vascular, cancellous bone of the
vertebral body.
[0004] The nucleus is constituted of a gel-like substance having a
high (about 80-85%) water content, with the remainder made up
mostly of proteoglycan, type II collagen fibers and elastin fibers.
The proteoglycan functions to trap and hold the water, which is
what gives the nucleus its strength and resiliency.
[0005] The annulus is an outer fibrous ring of collagen fibers that
surrounds the nucleus and binds together adjacent vertebrae. The
fibers of the annulus consist of 15 to 25 overlapping collagen
sheets, called lamellae, which are held together by proteoglycans.
The collagen fibers that form each lamellae run parallel at about a
65.degree. angle to the sagittal plane; however, the fibers of
adjacent lamellae run in opposite directions from each other.
[0006] As such, half of the angulated fibers will tighten when the
vertebrae rotate in either direction. This configuration greatly
increases the shear strength of the annulus helping it to resist
torsional motion. The annulus has a height of about 10 to 15 mm and
a thickness of about 15 to 20 millimeters, occupying about 2/3 of
the intervertebral space.
[0007] With aging and continued stressing, the nucleus becomes
dehydrated and/or one or more rents or fissures may form in the
annulus of the disc. Such fissures may progress to larger tears
which allow the gelatinous material of the nucleus to migrate into
the outer aspects of the annulus which may cause a localized bulge
or herniation. In the event of annulus rupture, the nuclear
material may escape, causing chemical irritation and inflammation
of the nerve roots.
[0008] Posterior protrusions of intervertebral discs are
particularly problematic since the nerve roots are posteriorly
positioned relative to the intervertebral discs. Impingement or
irritation of the nerve roots not only results in pain in the
region of the back adjacent the disc, but may also cause radicular
pain such as sciatica. Nerve compression and inflammation may also
lead to numbness, weakness, and in late stages, paralysis and
muscle atrophy, and/or bladder and bowel incontinence.
[0009] The most common treatment for a disc protrusion or
herniation is discectomy. This procedure involves removal of the
protruding portion of the nucleus and, most often, the annular
defect does not get repaired. Typically, removal of the nucleus
material is accomplished through the herniation site or a weakened
portion of the annulus.
[0010] Discectomy procedures have an inherent risk since the
portion of the disc to be removed is immediately adjacent the nerve
root and any damage to the nerve root is clearly undesirable.
Further, the long-term success of discectomy procedures is not
always certain due to the loss of nucleus polposus which can lead
to a loss in disc height. Loss of disc height increases loading on
the facet joints which can result in deterioration of the joint and
lead to osteoarthritis and ultimately to foraminal stenosis,
pinching the nerve root. Loss of disc height also increases the
load on the annulus as well. As the annulus fibrosis has been shown
to have limited healing capacity subsequent to discectomy. A
compromised annulus may lead to accelerated disc degeneration which
may require spinal interbody fusion or total disc replacement.
[0011] If disc degeneration has not yet resulted in excessive
herniation or rupture of the annulus, it may be desirable to
perform a nucleus replacement procedure in which the degenerated
nucleus is supplemented or augmented with a prosthesis while
leaving the annulus intact. Advances have been made in materials
for prosthetic nuclear implants which are relatively small and
flexible (e.g., hydrogels), and are able to provide added height to
the disc while simulating the natural disc physiology and motion.
However, in order to implant a prosthesis within the nucleus
cavity, an appropriately sized passageway through the annulus
(i.e., an annulotomy) must be created. As with naturally-occurring
defects in the annulus, the resulting surgical annulus defect may
lead to post-implant complications. Currently accepted suturing
techniques are of minimal value in light of the forces normally
exerted on the annulus, including an inability to adequately resist
explant of the nuclear implant.
[0012] Various annular defect repair techniques have been developed
to occlude an aperture, whether surgically or naturally formed,
within the annulus, which attempt to address the shortcomings of
suturing. Many of these techniques include the implantation of
devices, such as patches, membranes, stents and the like, to form a
barrier across the annulus aperture in order to seal or occlude the
aperture and/or to prevent explant of native or prosthetic nuclear
material. While an improvement over conventional suturing, these
annulus implants and repair techniques are limited in their ability
to provide the extent of circumferential and radial competency to
the annulus for long-term success. Additionally, where the disc
repair procedure also involves the implantation of both annulus and
nucleus augmentation devices, the implants and the steps necessary
to implant both may counter-indicate each other.
[0013] Accordingly, it would be highly advantageous to be able to
repair a degenerating or ruptured disc in a manner which obviates
the inherent risks of discectomy procedures, and which augments the
nucleus and/or annulus in a way that reduces the risk of
re-herniation of the disc subsequent to repair. Additionally, it
would be highly beneficial to provide a technique which allows disc
repair in a minimally invasive requiring minimal steps and
instrumentation to perform both annuloplasty and/or nucleus
replacement procedures concurrently in a synergistic manner.
SUMMARY OF THE INVENTION
[0014] The present invention provides systems for repairing the
intervertebral disc. The systems include implantable disc
augmentation devices as well as implantable prosthetic materials
for filling a void within the disc. The subject augmentation
devices optionally provide a scaffolding which augments the disc
and which also enables passage of the prosthetic material from a
location outside the disc to within the void space, where the void
occupies at least a portion of the annulus and/or the nucleus. The
systems further include instruments for implanting the subject
devices and prosthetic materials in a minimally invasive manner.
The invention further includes methods directed to the minimally
invasive repair of intervertebral discs where the methods may
include one or more of the following procedures: implantation of
one or more of the subject augmentation devices and implantation of
prosthetic material within the annulus and/or nucleus. The
inventive systems and methods are particularly useful in treating
herniated or ruptured discs requiring both nuclear and annular
augmentation or repair.
[0015] These and other features, objects and advantages of the
invention will become apparent to those persons skilled in the art
upon reading the details of the invention as more fully described
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention is best understood from the following detailed
description when read in conjunction with the accompanying
drawings. It is emphasized that, according to common practice, the
various features of the drawings are not to-scale. On the contrary,
the dimensions of the various features are arbitrarily expanded or
reduced for clarity. Included in the drawings are the following
figures:
[0017] FIG. 1A shows a sagital cross-section of a spinal motion
segment;
[0018] FIG. 1B shows a top axial view of a portion of the inferior
vertebrae and the intervertebral disc of the spinal motion segment
of FIG. 1A;
[0019] FIG. 2A shows a perspective view of a spinal motion segment
having a herniation in the posterior portion of the disc;
[0020] FIG. 2B shows a perspective view of the spinal motion
segment of FIG. 2A after removal of the herniated segment;
[0021] FIGS. 3A and 3B show perspective and side views,
respectively, of an embodiment of a disc augmentation device of the
present invention having anchors in an undeployed state.
[0022] FIGS. 3C and 3D show perspective and side views,
respectively, of the disc augmentation device of FIGS. 3A and 3B
having anchors in a deployed state.
[0023] FIGS. 4A-4G illustrate various steps for implanting the disc
augmentation device of FIGS. 3A-3D and for implanting a prosthetic
material according to methods of the present invention.
[0024] FIGS. 5A and 5B show planar and perspective views,
respectively, of another disc augmentation device of the present
invention.
[0025] FIGS. 6A-6E illustrate various steps for implanting the disc
augmentation device of FIGS. 5A and 5B and for implanting a
prosthetic material according to methods of present invention.
[0026] FIGS. 7A and 7B illustrate perspective and side views,
respectively, of one side of another disc augmentation device of
the present invention.
[0027] FIG. 8 is a perspective view of one side of another disc
augmentation device of the present invention.
[0028] FIGS. 9A-9F illustrate various steps for implanting the disc
augmentation device of FIGS. 7A and 7B and for implanting a
prosthetic material according to methods of present invention.
[0029] FIGS. 10A-10C illustrate another disc augmentation device of
the present invention.
[0030] FIGS. 11A-11E illustrate various steps for implanting the
disc augmentation device of FIGS. 10A10C and for implanting a
prosthetic material according to methods of present invention.
[0031] FIGS. 12A-12C illustrate perspective and top views of
another disc augmentation device of the present invention in which
a plurality of the devices of FIGS. 3A-3D are assembled into an
integrated unit.
[0032] FIGS. 13A-13D illustrate various states of deployment of the
integrated device of FIGS. 12A-12C.
[0033] FIGS. 14A and 14B illustrate another disc augmentation
implant of the present invention.
[0034] FIGS. 15A and 15B illustrate an instrument for delivering
and implanting the implant of FIGS. 14A and 14B.
[0035] FIGS. 16A-16F illustrate various states of deployment of the
device of FIGS. 14A and 14B.
[0036] FIG. 17 illustrates another disc augmentation device of the
present invention which is usable with a plurality of such
devices.
[0037] FIG. 18 illustrates an instrument for delivering and
implanting the device of FIG. 17.
[0038] FIGS. 19A-19F illustrate various steps for implanting the
disc augmentation device of FIG. 17 utilizing the instrument of
FIG. 18 and for implanting a prosthetic material according to
methods of present invention.
[0039] FIGS. 20A and 20B illustrate another disc augmentation
device of the present invention provided in an assembled plurality
and operatively loaded within the distal end of a delivery device
of the present invention.
[0040] FIGS. 21A-21H illustrate various steps for implanting the
disc augmentation devices of FIGS. 20A and 20B and for implanting a
prosthetic material according to methods of the present
invention.
[0041] FIGS. 22A and 22B illustrate the assembled plurality of
devices of FIGS. 20A and 20B operatively loaded in the delivery
device but configured and positioned for implantation of its ends
within adjacent intervertebral endplates.
[0042] FIG. 23 illustrates another augmentation device including
assembly of pin members.
[0043] FIG. 24 is a perspective view of the distal end of a
delivery tool usable to deliver and implant the device of FIG.
23.
[0044] FIGS. 25A and 25B illustrate the device of FIG. 23
operatively loaded in the distal end of the delivery tool of FIG.
24.
[0045] FIGS. 26A-26F illustrate various steps for implanting the
disc augmentation device of FIG. 23 utilizing the delivery tool of
FIG. 24 and for implanting a prosthetic material according to
methods of the present invention.
[0046] FIG. 27 illustrates an augmentation device similar to the
device of FIG. 10A for implantation within a disc by way of a
transverse approach to the annulus.
[0047] FIGS. 28A-28G illustrate various steps for implanting the
disc augmentation device of FIG. 27 and for implanting a prosthetic
material according to methods of the present invention.
[0048] FIG. 29 illustrates a suture-based system of the present
invention for augmenting an intervertebral disc.
[0049] FIGS. 30A-30D illustrate various steps for augmenting a disc
using the system of FIG. 29 for implanting a prosthetic material
according to methods of the present invention.
[0050] FIG. 31A illustrates another augmentation device of the
present invention.
[0051] FIG. 31B illustrates a pair of the augmentation device of
FIG. 31A operatively implanted within an intervertebral disc.
[0052] FIG. 32A illustrates another augmentation device of the
present invention.
[0053] FIG. 32B illustrates a pair of the augmentation devices of
FIG. 31A operatively implanted within an intervertebral disc.
[0054] FIG. 33 a clamp-type disc augmentation device of the present
invention.
[0055] FIG. 34 a distal portion of a delivery tool for implanting
the device of FIG. 33.
[0056] FIGS. 35A-35H illustrate various steps for implanting the
disc augmentation device of FIG. 33 utilizing the delivery tool of
FIG. 34 and for implanting a prosthetic material according to the
methods of the present invention.
[0057] FIGS. 36A and 36B illustrate alternate clamp designs for
disc augmentation devices of the present invention.
[0058] FIG. 37 illustrates another clamp-type disc augmentation
device employing the clamp design of FIG. 36B.
[0059] FIGS. 38A-38F illustrate various steps for implanting the
disc augmentation device of FIG. 37 and for implanting a prosthetic
material according to the methods of the present invention.
[0060] FIG. 39A-39C show perspective and top views of a clip-type
embodiment of an augmentation device of the present invention.
[0061] FIGS. 40A-40D illustrate various steps for implanting the
disc augmentation device of FIGS. 39A-39C and for implanting a
prosthetic material according to methods of the present
invention.
[0062] FIG. 41 illustrates another clamp embodiment of an
augmentation device of the present invention.
[0063] FIGS. 42A-42F illustrate various steps for implanting the
disc augmentation device of FIG. 41 and for implanting a prosthetic
material according to methods of the present invention.
[0064] FIG. 43A illustrates another augmentation device of the
present invention.
[0065] FIG. 43B illustrates the augmentation device of FIG. 43A
operatively implanted within an intervertebral disc.
[0066] FIG. 44A illustrates another augmentation device of the
present invention.
[0067] FIG. 44B illustrates the augmentation device of FIG. 44A
operatively implanted within an intervertebral disc.
[0068] FIGS. 45A and 45B illustrate another clamp type augmentation
device of the present invention in undeployed and deployed states,
respectively.
[0069] FIGS. 46A-46F illustrate various steps for implanting the
disc augmentation device of FIGS. 45A and 45B and for implanting a
prosthetic material according to methods of the present
invention.
[0070] FIGS. 47A-47D illustrate another clamp type augmentation
device of the present invention.
[0071] FIG. 48 illustrates yet another clamp type augmentation
device of the present invention.
[0072] FIGS. 49A-49C illustrate several cylindrical clip type
augmentation devices of the present invention.
[0073] FIGS. 50A and 50B illustrate perspective and end views,
respectively, of another cylindrical clip type augmentation device
of the present invention.
[0074] FIGS. 51A and 51B illustrate operative deformation of the
device of FIGS. 50A and 50B upon implantation.
[0075] FIGS. 52A-52G illustrate various steps for implanting
another cylindrical type disc augmentation device of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0076] Before the subject devices, systems and methods are
described, it is to be understood that this invention is not
limited to particular embodiments described, as such may, of
course, vary. It is also to be understood that the terminology used
herein is for the purpose of describing particular embodiments
only, and is not intended to be limiting, since the scope of the
present invention will be limited only by the appended claims.
[0077] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. For
example, in this description and the following claims, the terms
"anterior", "posterior", "superior" and "inferior" are defined by
their standard usage in anatomy, i.e., anterior is a direction
toward the front (ventral) side of the body or spinal motion
segment; posterior is a direction toward the back (dorsal) side of
the body or functional spin unit; superior is upward toward the
head; and inferior is lower or toward the feet.
[0078] Referring now to FIGS. 1A and 1B, the general anatomy of a
spinal motion segment 10 is illustrated. Axis 2 shows the anterior
(A) and posterior (P) orientation of the spinal motion segment
within the anatomy. A spinal motion segment includes the bony
structures of two adjacent vertebrae (superior vertebral body 12
and inferior vertebral body 14), the intervertebral disc 16
(including the annulus fibrosis 18, the nucleus pulposus 20, and
endplates 22, 24 of the vertebrae), and the ligaments, musculature
and connective tissue (not shown) connected to the vertebrae.
Intervertebral disc 16 substantially fills the space between the
two vertebral bodies to support and cushion them, and permits
movement of the two vertebral bodies with respect to each other and
other adjacent spinal motion segments. Extending posteriorly from
each of vertebral bodies 12 and 14 are left and right transverse
spinous processes 30, 32 and a posterior spinous process 34, 34'.
The vertebral bodies also include facet joints 36 and pedicles 38,
38' that form the neural foramen 40.
[0079] As discussed above, progressive degeneration of the disc
results in disc height loss where the superior vertebral body 12
moves inferiorly relative to the inferior vertebral body 14.
Ultimately, this may result in herniation of the disc, as
illustrated by herniated segment 26, shown in FIG. 2A, which
protrudes beyond the posterior border of annulus 18. FIG. 2B
illustrates the disc defect or void 28 created by a discectomy
procedure in which the herniated portion of annulus 18 and nucleus
20 have been removed. Such a discectomy procedure may be performed,
but is not required to be performed, prior to use of the devices
and practice of the methods of the present invention.
[0080] The present invention is directed to augmenting the
intervertebral disc, including the annulus and/or the nucleus, for
treating or preventing degeneration and/or herniation of the
intervertebral disc. This is accomplished by implantation of one or
more augmentation devices within the disc, and most typically
within the annulus, i.e., within an intra-annular space (i.e.,
between two adjacent lamellae or an inter-lamellar space), or
within a sub-annular space (i.e., between the innermost lamella and
the outer aspect of the nucleus), or within a void in the annulus
but not necessarily within the annulus itself. If a significant
enough defect, e.g., a void, exists within the disc, either in the
nucleus, the annulus or both, one or more prosthetic materials may
be additionally implanted within the void within at least a portion
of the annulus and/or the nucleus of the affected disc.
[0081] Certain of the augmentation devices are configured to be
wholly implantable within a void within the annulus or within an
intra-annular space where no portion of the device extends beyond
the inner and outer aspects or borders of the annulus. Other
embodiments are configured to be partially implantable within an
intra-annular space while another portion of the device is
positioned within the nucleus, outside than annulus and or within
the intervertebral body upon implantation. More particularly, the
augmentation devices may be configured to have a portion thereof or
one or more components, struts or members which penetrate into an
intra-annular space. Still yet, other configurations do not
penetrate into any portion of the annulus or nucleus but rather
into one or more of the intervertebral bodies between which the
disc is situated.
[0082] The present invention provides various approaches to
implantation of the subject augmentation devices. In one approach,
at least a portion of an augmentation device is delivered to within
the annulus in a direction substantially parallel to or tangential
with a plane defined by the radius of curvature of the annulus
(referred to at times herein as a "inline" or "parallel" approach).
For example, a component of the device is aligned substantially
parallel with the orientation of the lamellar layers. In another
approach, at least a portion of an augmentation device is delivered
in a direction substantially transverse to a plane defined by the
radius of curvature of the annulus (referred to at times herein as
a "transverse" or "perpendicular" approach). For device embodiments
configured for penetration into an intervertebral body, one or more
portions or components of the implant may be implanted at any angle
relative to the annulus or lamellar planes, including at right
angles to the vertebral endplates.
[0083] The augmentation devices may have an unexpanded or
undeployed state to enable its minimally invasive delivery through
a delivery tool, such as catheter or cannula, to the intra-annular
or sub-annular implant site. Upon proper positioning of the
implantable device at the implant site, the device is expanded or
deployed. The transition from an undeployed state to a deployed
state may require an active step such as mechanical actuation.
Alternatively, the device may be configured to be self-expanding or
self-deploying whereby, upon release from the delivery tool, the
device achieves its expanded or deployed configuration within the
disc. As such, the devices are preferably made of an elastic or
superelastic material, e.g., nickel titanium alloy (Nitinol), or a
semi-rigid polymer.
[0084] The annular augmentation devices preferably have a
configuration with a length and height sufficient to bridge across
void 28. Typically, the length of a subject annular augmentation
device is in the range from about 3 mm to about 30 mm, and most
typically from about 5 mm to about 15 mm. Typically, the height of
a subject annular augmentation device is in the range from about 2
mm to about 28 mm.
[0085] Another feature of the subject disc augmentation devices is
that they have configurations which allow for the delivery and
implantation of a prosthetic material to within either or both the
annulus and nucleus subsequent to implantation of the augmentation
device(s) (although the devices and materials may be implanted in
any order). For example, the disc implants may provide a
scaffolding for promoting tissue in growth and/or allowing passage
of the prosthetic implant material to within the nucleus as well as
to within voids within the annulus not yet occupied by the disc
device implant. The scaffolding may take the form of a frame having
a planar configuration having apertures or which may be partially
or wholly porous, or may be configured as a mesh, webbing, fabric
or an arrangement of struts. Implanting the prosthetic material
after a disc augmentation device helps to retain the material
within the disc prior to and during solidification or curing of the
material. Without such a retaining structure, the prosthetic
material may seep or leak out of the disc prior to implantation of
the disc augmentation devices.
[0086] It is preferred that the implant materials exhibit
mechanical properties, swelling pressures and/or diffusion
capabilities similar to the natural tissue site, i.e., annulus or
nucleus, into which they are implanted. As such, more than one
prosthetic material or varying compositions of the same type of
material may be implanted where a first material is used to fill a
void in the nucleus and a second material is used to fill a void or
voids within the annulus. The different materials may be selected
to more closely mimic the physical characteristics of the host
tissue, e.g., the prosthetic material implanted in the annulus may
be more fibrous and resilient than that which is implanted in the
nucleus.
[0087] Alternatively, a single type of implant material may be used
where the void in the nucleus and in the annulus are filled by a
single injection application, where upon filling the nucleus, the
material is caused to back fill into the annulus. The curing
process may be modified such that the portion of the material
within the nucleus is caused to harden or solidified to a less
degree than that the portion of the material within the annulus.
This may occur without much intervention as the amount of UV
radiation reaching the nucleus will be less than the amount
reaching the annulus as the annulus serves to buffer the nucleus.
The same may be the case when diffusing a curing chemical into the
implanted material. Alternatively, the implantation and curing may
take place in a two phase process where the annulus is not filled
and cured until after the nucleus has been filled and separately
cured.
[0088] The prosthetic materials of the present invention may be
initially in the form of a solid or fluid. The solids may take the
form of beads, particles or a powder so as to be easily deliverable
through or within the implanted disc device(s). The fluids may be
in the form of a gel, liquid or other flowable material. In any of
these forms, the material is selectively delivered in an amount to
increase the disc volume, pressure and/or height. Subsequent to
delivery within the disc void(s), the prosthetic material(s) may
remain in the same form or take another form either by curing by
the application of heat or UV light, by absorption of surrounding
fluids, i.e., where the prosthesis material is hydrophilic, or by
the application of another substance or chemical which reacts with
the material in a way that changes its form.
[0089] Any suitable prosthetic materials may be used with the
present invention. Examples of suitable materials include but are
not limited to biocompatible materials such as hydrophilic
polymers, hydrogels, homopolymer hydrogels, copolymer hydrogels,
multi-polymer hydrogels, or interpenetrating hydrogels. The
materials may also include biologic material which are autologous,
allograft, zenograft, or bioengineered. Examples of such biologic
materials include but are not limited morselized or block bone,
hydroxy apetite, collagen or cross-linked collagen, muscle tissue,
fat, cellulose, keratin, cartilage, protein polymers, etc. which
may be transplanted or bioengineered materials.
[0090] The disc implant material(s) and/or disc implant device(s)
may be impregnated, coated or otherwise delivered with one or more
therapeutic agents, including but not limited to, drugs (e.g.,
analgesics, antibiotics, steroids, etc.), growth factors,
extracellular matrices (ECMs), etc. which may be dispersed in a
regulated or time-released fashion.
[0091] Various exemplary embodiments of the disc augmentation
systems and disc repair methods of the present invention are now
described in greater detail, however, such description is not
intended to be limiting but exemplary of the present invention. Any
combination of features, materials, functions and physical
characteristics described above may be applied to each of the
devices and/or materials of the present invention.
[0092] FIGS. 3A-3D illustrate one embodiment of a disc augmentation
device 40 of the present invention. Device 40 has a thin planar
structure 42 which is designed to be implantable within an
intra-annular space, e.g., inter-lamellarly (between two adjacent
lamellae), to bridge a disc defect or void 28. Typically, more than
one and as many as eight or more structures 42 are used
collectively in a stacked arrangement, where at least one lamella
lies between adjacently implanted structures. Depending on the
length of the device, it may be straight (shorter device segments)
or have a radius of curvature along its length (longer device
segments) which matches that of the intra-annular
circumference.
[0093] Each structure 42 has a central portion 45 flanked by end
portions 48 where central portion 45, when implanted, is positioned
within disc defect 28 and end portions extend substantially
laterally of disc defect 28. Central portion 45 has a mesh
configuration or includes a plurality of openings or apertures 46
which extend through the thickness of structure 42 to allow for
passage of an implant material as mentioned above. Each end portion
48 has one or more laterally extendable anchors 44. Anchors 44 may
be formed by cut outs within structure 42 which remain connected to
body 42 so as to be hinged at a distal end and flarable or biased
from body 42 at a proximal end, as illustrated in FIGS. 3C and 3D,
to function as barbs once operatively positioned within the
annulus. As with the entirety of structure 42, anchors 44 may be
fabricated from a super elastic memory material which is activated
by body temperature to achieve a flared condition subsequent to
implantation. The anchor cut-out and aperture patterns of device 40
may be formed by electro-discharge machining (EDM), laser cutting,
injection molding, photo-chemical etching (PCE), a casting process
or by other suitable means from a relatively thin sheet of
material, e.g., having a sheet thickness from about 0.1 mm to about
4 mm. As illustrated in FIG. 4B, device 40 is bendable or foldable
at central section 45 about an axis transverse to the length of
device 40 to reduce its profile for purposes of delivery through a
cannula or catheter.
[0094] Various steps of a method of implanting a plurality of
devices 40 are illustrated in FIGS. 4A-4G. A delivery tool 50 is
provided having an outer sheath 52, which may be a cannula or
catheter or the like. Housed within sheath 52 is a plurality of
devices 40 (not shown) which may be provided in a stacked or
sequential arrangement, such as within a pre-loaded cartridge,
which is loaded into delivery sheath 52. While sheath 52 is
illustrated having a square or rectangular cross-section so as to
best accommodate the structure of device 40, the sheath may have
any suitable cross-sectional shape to accommodate the disc
implants.
[0095] After surgical access is made, the distal end 56 of delivery
tool 50 is positioned within or at the outer aspect of disc void
28. As illustrated in FIG. 4A, rails or guide members 54 are
distally extended into disc void 28 to the most distal or internal
lamellar layer, e.g., between lamellae 18a and 18b, into which a
device 40 is to be implanted. Guide members 54 have outwardly
projecting feet 58 which are configured to be inserted between the
cut edges of adjacent lamellae and provide exit ramps to direct the
ends of a device 40 to within an intra-lamellar space. A plunger or
pusher (not shown) may be slidably engaged within sheath 52 or some
other actuator mechanism may be employed to distally advance a
device 40 in a folded or unexpanded configuration along guide
members 54, as illustrated in FIG. 4B. The ends of device 40 are
directed outwardly by feet 58 and guided between lamellar ends
18a', 18b' and 18a'', 18b'', respectively, as shown in FIG. 4C.
Upon achieving the necessary temperature, anchors 44 expand
outwardly to their flared condition, securing device 40 within the
intra-lamellar space. The process is repeated as necessary for the
selected number of implants 40, with each successive implant is
inserted in an inter-lamellar layer that is more proximal (towards
the outer circumference of the annulus) than the one before.
[0096] As shown in the perspective views of FIGS. 4D and 4E,
apertures 46 within each of the implanted plurality of devices 40
provide fluid communication between the devices and into disc void
28. This provides a pathway from outside the annulus 18 into disc
void 28 for delivery of the prosthetic implant material, as
described above. In one embodiment, an injector device 60, as
illustrated in FIG. 4F, having a syringe 62 containing an amount of
the prosthetic material is coupled to a tube 64 which is sized to
fit through the minimally invasive access site. The distal end of
the tube is positioned either at the outermost disc implant 40, or
if small enough, may be inserted through apertures 46 within one or
more of the implants. After tube 64 is properly positioned, plunger
66 may be advanced to extrude a sufficient amount of the prosthetic
material 68 to fill the portion of disc void 28 within nucleus 20
as well as within the intra-annular spaces partitioned by the disc
devices 40. Upon filling the entirety of the void 28, or
intermittently throughout the injection process, the injected
material 68 may be allowed to cure or be actively cured, if such is
necessary, as described generally above, to provide a plug or the
like that extends from the nucleus 20 to the outer aspect of the
annulus 18.
[0097] FIGS. 5A and 5B illustrate another embodiment of an disc
augmentation device 70 of the present invention which is similar to
device 40 of FIGS. 3 and 4 in that it has a thin planar
configuration, but instead of providing apertures, device 70 is
made of a mesh material. With such a configuration, a prosthetic
material may be impregnated within or coated on device 70, i.e.,
the smaller and more abundant apertures may be sized to hold solid
particles 72 of prosthetic material or another composition or agent
as listed above.
[0098] As with device 40, device 70 is made of a material (e.g.,
Nitinol) which is flexible or deformable, allowing it to be
foldable or bendable about a central portion to form a U-shaped
structure which can be delivered in a minimally invasive manner.
The U-shape allows a plurality of devices 70 to be provided in a
stacked arrangement, such as in a cartridge 80, which can be
pre-loaded into the barrel or sheath 76 of a delivery device 74, as
illustrated in FIG. 6A. Delivery device 74 is configured to enable
semi-automatic delivery and deployment of the plurality of devices
70 by means of an actuator or trigger mechanism 78. Distal end 82
of delivery device 74 may have a radially expandable portion to
provide a stable support against the outer aspect of the annulus
and to ensure alignment with defect 28.
[0099] In use, after insertion of barrel 76 into the access site
and abutment of the distal end 82 against the annulus at the defect
site 28, guide members 84 are distally extended from distal end 82
within void 28 to the most distal intra-lamellar layer into which a
device 70 is to be implanted. Guide members 84 have outwardly
extending feet 86 which may have a bladed configuration to
facilitate separation of cut ends 18a, 18b and 18a', 18b' of the
lamellar layers for insertion of a device 70. A first device 70 is
advanced through sheath 76 and guided by guide members 84 to the
target intra-lamellar layer. Because the ends of device 70 are
biased outwards, as they pass feet 86, they urge themselves to
within the intra-lamellar space. Feet 86 of guide members 84 are
then withdrawn from the intra-lamellar layer and retracted
proximally to the next intra-lamellar layer into which a device 70
is to be implanted, as illustrated in FIG. 6B. The process is
repeated until a desired number of devices 70 are implanted within
the annulus (see FIG. 6C).
[0100] Next, void 28 is filled with a prosthetic material, which
may be delivered through delivery device 74 or by means of another
instrument. As illustrated in FIG. 6D, solid particles or a powder
90 of a prosthetic material is delivered into at least the portion
of void 28 within nucleus 20. As mentioned above, the same
prosthetic material may be used to fill both the nucleus and the
annulus or different materials may be used to fill each. In either
case, the curing process may involve curing all of the implanted
material(s) at the same time or curing the material within the
nucleus first followed by filling and curing the material within
the annulus. Here, an amount of material 90 sufficient to fill only
the nucleus portion of void 28 is delivered and then cured by
exposure to UV radiation, as illustrated in FIG. 6E, or other
curing methods. The portion of void 28 within in annulus 18 may now
be filled with the same or a different material and cured, or
otherwise left alone to be filled in by the natural healing
process.
[0101] FIGS. 7A and 7B illustrate another implantable device 100
for augmenting the disc. Device 100 includes a planar structure 102
configured for insertion within an intra-lamellar space. A
plurality of flexible wire barbs 14 extend from structure 102 in an
angled fashion towards the proximal end 108 of structure 102, and a
plurality of sutures or wires extend from proximal end 108. FIG. 8
illustrates a device 110 which is a variation of the device 100
having a plurality of planar anchors 114 in place of barbs 104. As
illustrated in FIG. 9A, each of these devices is implanted within
an intra-lamellar plane on a side of an annular defect. Upon entry
into the lamellar plane, barbs 104 (or anchors 114) are compressed
against structure 102 (or structure 112) facilitating easy
insertion within between the adjacent lamellae. After insertion of
the device, barbs 104 will expand outwardly and resist backward
movement of structure 102. The process may repeated to implanted
any desired number of implants within annulus 18. For each device
100 implanted within one side of an annular defect, a second device
100 is implanted within the lamellar layer directly opposing the
first implanted device 100 as illustrated in FIG. 9C. As such, two
oppositely implanted devices 100 function in tandem as a pair to
close at least a portion of the annular defect.
[0102] When all of the devices 100 have been inserted, all of the
trailing proximal sutures 106 are collectively synched to pull
together opposing sides of annulus 18 and tied together with a knot
tie 105 or similar means as illustrated in FIG. 9D. The
collectively tied sutures 106 form a sort of webbing that allows
for the passage of one or more implantable materials 120, either in
liquid or solid form, to within defect 28, in both the nucleus and
annulus, as illustrated in FIG. 9E. The implanted material 120 is
then cured in one or more of the manners described above, as
illustrated in FIG. 9F.
[0103] FIG. 10A illustrates another component 130 of a disc
augmentation device to be used in a pair. Component 130 includes a
planar endplate or block 132 which has dimensions which has a
cross-sectional area and shape which substantially matches the
cross-sectional area and shape of a disc annulus into which it is
to be implanted. Extending from a distal end of end plate 132 is a
plurality of anchors 134 preferably arranged in columns (and rows)
and having barbs 138. As with the device described above, barbs 138
have a compressed configuration prior to insertion of anchors 134
into an annulus (see FIG. 10B) and expand upon insertion into the
annulus (see FIG. 10C). Extending from a proximal end of endplate
132 are sutures or wires 136.
[0104] As illustrated in FIG. 11A, device 130 is implanted within
an annulus 18 by way of penetrating or inserting anchors 134
parallel to the lamellar planes or layers, preferably such that
each of anchors 134 is positioned within an intra-lamellar space.
As such, the distal surface of endplate 132 contacts the cut or
free end of annulus or free ends of the lamellae and is positioned
transversely thereto. The insertion process is repeated with a
second device 130 which is positioned within the opposing free end
of annulus 18, as illustrated in FIG. 11B. Unlike the previously
described embodiments, a single integrated component is implanted
within each free end of annulus 18. Suture ends 136 are then
synched together and secured to each other with tie or knot 138, as
illustrated in FIG. 11C. A delivery tube 142 is then employed to
deliver prosthetic material 140 over the scaffolding formed by the
knotted sutures, as illustrated in FIG. 11D, where an amount of
material is injected sufficient to fill defect 28 within nucleus 20
and annulus 18. Curing instrument 144 is then employed to cure
prosthetic material 140, as illustrated in FIG. 11E.
[0105] FIGS. 12A-12C illustrate another annular augmentation device
150 which is an integrated assembly of inter-lamellar components
152 which are similar to the implants 46 of FIGS. 3A-3D. Each
component 152 has a planar structure sized and shaped to be
positioned within an inter-lamellar space. Components 152 are
bendable or foldable about a central portion having apertures 155.
The end portions have anchors 158 which are flarable after implant,
as illustrated on FIG. 12C. The distal ends 156 of component 152
may be tapered or have a sharp blade edge to facilitate separation
and penetration of structure between adjacent lamellae. Slotted
brackets 154 are positioned about the central portions of
structures 152 to hold and maintain them in a substantially
parallel, spaced relationship. A transverse member 162 positioned
parallely between brackets 154 also extends centrally through
structures 152 and is held thereto by proximal and distal hubs
164a, 164b where proximal hub 164a provides a slot for releasably
receiving the distal end of an insertion tool 160, as illustrated
in FIGS. 13A-13C.
[0106] FIGS. 13A-13D illustrate device 150 in various states of
deployment where manipulation of insertion tool 160 selectively
adjusts the profile of device 150. FIGS. 13A and 13A' illustrate
device 150 in its lowest profile state in which the distal portion
of structures 152 (i.e., the distal two structures) is folded
distally and the proximal portion of structures 152 (i.e., the
proximal two structures) is folded proximally to the maximum extent
where only the tips 156 of the structures extend from the slots of
brackets 154. In this configuration, device 150 is most easily
positioned within a void within the annulus with or without the
assistance of a delivery sheath or tube (not shown). After
insertion into the annulus, insertion tool 160 is manipulated to
compress the folded central portions toward each other and thereby
cause the end portions of structures 152 extend radially outward,
as illustrated in FIGS. 13B and 13B'. The compression structures
152 continues until they are fully straightened with their end
portions fully embedded within the intra-annular spaces, as
illustrated in FIGS. 13C and 13C'. At this point, insertion tool
160 is released from transverse member 162 which remains implanted
with device 150, as illustrated in FIG. 13D. As with the other
embodiments described above, a prosthetic material may then be
delivered through implanted device 150 to within void 28 and
cured.
[0107] FIGS. 14A and 15B illustrate another variation of an
implantable annular augmentation device 170. Here, device 170 is a
standalone elongated anchor 172 having flarable barbs 174 (shown in
undeployed and deployed conditions, respectively) at a distal or
leading end and a suture, filament or wire 176 at a proximal or
trailing end. A plurality of such devices 170, including at least
one device for implantation on each side of an annular defect,
either within an inter-lamellar space or within the nucleus or
healthy portion of the annulus, is employed to provide a
scaffolding structure which augments the annulus but may also serve
to support implantable prosthetic materials.
[0108] FIGS. 15A and 15B illustrate a delivery device 180 for the
simultaneous delivery and deployment of a plurality of anchors 170
to within an annulus. Delivery device 180 includes a shaft portion
182 which houses a plurality of pre-loaded implantable devices 170.
Delivery device 180 is configured to automatically fire a plurality
of devices 170 laterally outward from opposing sides 188 of shaft
182, as illustrated in FIG. 15B. One or more anchors 170 are
aligned with or channeled to exit ports 190 provided at the
laterally facing surfaces 188 of distal end such that the anchors
are caused to be deployed within intra-annular locations in an
array fashion. Delivery device 180 may be sized and configured to
deploy any number of anchors 170 simultaneously on one or both
sides of shaft 182.
[0109] For example, FIGS. 16A and 16B illustrate use of delivery
device 180 where a plurality of anchors 172 is deployed into one
side or cut end of annulus 18 at a time. After anchors 170 have
been delivered into both ends of annulus 18, the trailing suture
ends 176 are synched together, as illustrated in FIG. 16C, and
securely tied by a knot or other clip means 192, as illustrated in
FIG. 16D. Prosthetic material 198 is then injected by injection
tube 194 through the webbing defined by knotted strings 176 to fill
void 28 within nucleus 20 and annulus 18, as illustrated in FIG.
16E. The prosthetic material 198 is then cured by exposure to UV
light by way of UV light emitter 196, as illustrated in FIG.
16F.
[0110] FIG. 17 illustrates another variation of an implantable
annular augmentation device 190. In essence, device 190 is an
integration of two of the above-described devices 170 of FIGS. 14A
and 14B. Device 190 includes two elongated anchors 192a, 192b
having flarable barbs 194 (shown in an undeployed condition) and
bridged together by a suture, filament or wire 196 at proximal ends
of the anchors. The length of suture 196 is selected such that when
opposing anchors 192a, 192b are embedded within tissue, the suture
is at least somewhat taught and able to apply tension on the
tissue. As such, when a device 190, but more frequently a plurality
of such devices 190, is implanted within an inter-lamellar space or
within the nucleus or healthy portion of the annulus, a scaffolding
structure is established which augments the annulus but may also
serve to support implantable prosthetic materials.
[0111] FIG. 18 illustrates a device 200 for the automated delivery
of one or more devices 190. Delivery device 200 has a shaft 202
having an articulating distal end 204 which is insertable into and
moveable within a defect 28. Delivery device 200 may be further
equipped with a scope that facilitates visualization of the target
implantation area. A plurality of devices 190 is shown preloaded
within a cartridge 206 which is engaged with device 200. By
activation of a trigger mechanism 208, the preloaded devices 190
are individually transferred to shaft 202 and delivered to the
implantation site where leading or first anchor 192a is implanted
in a first location within or adjacent to defect 28 (shown within
the defect itself), as shown in FIG. 19A. The trailing or second
anchor 192b is then also deployed within or adjacent to defect 28
(shown within an anterior portion of the annulus) at a distance
from the first anchor 192a to create some tension between the two,
as illustrated in FIGS. 19B and 19C. Any number of devices 190 may
be implanted to create the necessary scaffolding structure within
defect 28 and/or across a void within the annulus 18, as
illustrated in FIG. 19D. After the scaffolding structure is
complete, a prosthetic material 210 may be injected into void 28
through the scaffolding formed by devices 190 and subsequently
cured, as illustrated in FIGS. 19E and 19F, respectively.
[0112] FIGS. 20A and 20B provide perspective views of an disc
augmentation assembly of doubled-ended pins or needles 220 loaded
within the distal end 228 of a delivery tool 230 (see FIG. 21A).
Pins 220 have barbed ends 222 and are preferably made of a
superelastic material to allow them to be folded or flexed about a
central portion 224 for loading into tool 230 and to provide a low
profile, illustrated in FIG. 20A, during delivery of the loaded
tool to the implant site. Delivery tool 230, shown in full in FIG.
21A, provides a narrow shaft 232 for further facilitating minimally
invasive delivery through an access site to the disc to be treated.
Upon delivery, distal end 228 with pins 220 in their low profile or
folded state is positioned within the annulus defect 28. Upon
optimizing the position of distal end 228, a trigger mechanism 236
on handle 234 of tool 230 is actuated, causing central portions 224
of pins 220 to be pushed or advanced distally until fully
straightened, whereby pin ends 222 are caused to extrude from
apertures 238 on the lateral sides of distal end 228 (see FIGS.
20B, 21C and 21D). When fully extended and deployed, the pins are
released from the distal end of the delivery tool through slots
(not shown) on the distally facing surface, and left behind to form
a scaffolding which bridges at least a portion of the defect region
28, including at least a portion of a void within the annulus 18
and/or within the nucleus, as illustrated in FIGS. 21E and 21F.
[0113] In a manner similar to that described above with respect to
FIGS. 4F and 4G, an injector device 60 is then used to inject or
extrude prosthetic material within void 28, as illustrated in FIG.
7C. In one embodiment, an injector device 60, as illustrated in
FIG. 4F, having a syringe 62 containing an amount of the prosthetic
material is coupled to a tube 64 which is sized to fit through the
minimally invasive access site, as illustrated in FIG. 21G. The
distal end of the tube 64 is positioned between pins 222, and
plunger 66 is advanced to extrude a sufficient amount of the
prosthetic material 238 to fill the portion of disc void 28 within
nucleus 20 as well as within the spaces between pins 222. Upon
filling the entirety of the void 28, or intermittently throughout
the injection process, as shown in FIG. 21H, the injected material
68 may be allowed to cure or be actively cured, if such is
necessary, as described generally above, to provide a plug or the
like that extends from the nucleus 20 to the outer aspect of the
annulus 18.
[0114] FIGS. 22A and 22B illustrate another assembled plurality of
pins 222 operatively loaded within distal end 228 of delivery tool
230, as discussed above, but alternately positioned within defect
28. Specifically, distal end 228 is rotationally oriented 90% from
the operative deployment position discussed above (see FIG. 21B)
where pin apertures 238 are facing opposing intervertebral
endplates 22, 24 rather than the free ends of annulus 18. The pin
delivery, deployment and release steps described above are similar
here, but pins 222 are anchored within the intervertebral bodies
thereby providing a scaffolding having vertically or transversely
placed pins rather than horizontally placed pins.
[0115] FIG. 23 provides another augmentation device 240 configured
for anchoring into the intervertebral endplates. Device 240, shown
in a fully expanded condition, includes an assembly of parallel
spaced pins 244 extending between and through brackets 242. The
ends of each pin 244 are capped with a barbed head 246 which is
slidable distally along pin 244 to a maximally extended and locked
position. Alternatively, pins 244 are made of a stretchable
material with barbed caps 246 fixed to the ends thereof to allow
extension of the device to span a defect within an annular
space.
[0116] FIG. 24 illustrates the distal end of a delivery tool 250
having opposing plates 252 which are movable in a pivoting or
scissor fashion with respect to each other. A number of slots 254
extend through the distal tips of plates 252 for receiving the
assembly of pins 240 of FIG. 23 in a transverse fashion, as
illustrated in FIGS. 25A and 25B. In this loaded position, caps 246
are in their retracted position on pins 244 or, in the alternate
embodiment, pins 244 are in their unstretched state.
[0117] FIGS. 26A-26F illustrate various steps of implanting device
240 by means of delivery tool 250. Initially, tool 250 is delivered
to the implant site within annulus 18 with plates 252 in their
closed position so as to maintain device 240 in an unextended or
undeployed state. Upon proper positioning at the implant site,
plates 252 are opened and are caused to abut against caps 246.
Continued opening of plates 252 drives barbed caps 246 into the
endplates 22, 24 of the subject intervertebral disc space, as
illustrated in FIG. 26C. Upon embedding the pin ends within the
vertebrae, tool 250 is retracted proximally and device 240 is
released from slots 254, as illustrated in FIG. 26D. Finally, as
illustrated in FIGS. 26E and 26F, a prosthetic material 258 is
delivered and cured as described above.
[0118] While various "inline" approaches have been described for
delivering and implanting various embodiments of disc augmentation
devices (primarily with respect to those illustrated in FIGS.
3-22), as mentioned above, the present invention also provides
devices which involve a "transverse" approach to augmenting the
disc where certain of the subject devices may be employed with
either approach.
[0119] For example, device 260 of FIG. 27, which is similarly
configured to the device of FIGS. 10A-10C having a planar endplate
or block 262 and a plurality of distally extending barbed anchors
264 and a plurality of trailing sutures or filaments 266, is
implantable by an inline approach as illustrated in FIGS. 11A-11E
as well as by the transverse approach illustrated in FIGS.
28A-2G.
[0120] A pair of devices 260 used in tandem is delivered and
implanted by means of delivery tool 270 which has opposing and
substantially parallel jaws 272 at a distal end thereof wherein at
least one jaw is movable relative to the other. Devices 260 are
held within the inner, opposing surfaces of jaws 272 with anchors
264 facing each other. The distal end of tool 270 is positioned
within defect or opening 28 within annulus 18 such that a cut or
free end of the annulus is positioned or sandwiched between the two
devices 260, as illustrated in FIG. 28A. Jaws 272 are moved
together thereby penetrating anchors 264 into and transverse to the
lamellar layers of clamped therebetween, where one device is
implanted at the outer aspect of annulus 18 and the other device is
implanted at the inner aspect of annulus 18. Tool 270 is removed
and the process is repeated with another pair of devices 260 which
is applied to the opposing free end of annulus 18, as illustrated
in FIGS. 28B and 28C. The trailing sutures 266a of the devices 260
positioned at the inner aspect of annulus 18 are collectively
synched and secured together by tie a tie or knot 265, as
illustrated in FIG. 28D. A plug or core 268 having a porous or mesh
construction so as to be permeable by a flowable prosthetic
material is then positioned within the void between the free ends
of annulus 18. The sutures or filaments 266b of the devices 260
positioned at the outer aspect of annulus 18 are then secured
together with a second tie or knot mechanism 265, as illustrated in
FIG. 28E. The combination of the implanted core 268 and the webs
formed by sutures 266 define a scaffolding for augmenting the
annulus and for receiving prosthetic material 274, as illustrated
in FIG. 28F. After filling void 28, which may extend into nucleus
20, prosthetic material 274 is cured, as illustrated in FIG.
28G.
[0121] FIG. 29 illustrates a system 280 of the present invention
for applying a plurality of sutures or filaments 288 to a disc
annulus in order to augment the disc as well as to provide a
scaffolding for receiving a flowable prosthetic material. System
280 includes a suture spool holder 282 having a plurality of
parallely aligned suture spools 284. System 280 also includes a
needle carrier or driver 286 having a plurality of parallely
aligned needles 290 configured for threadably receiving sutures
288. Needle driver 286 is automated such that it oscillates in much
the same way a needle driven by a sewing machine. As needles 290
are driven into tissue, each of sutures 288 is placed within the
tissue with a continuous length of suture material provided by
spools 284.
[0122] In use, system 289 is positioned at the outer aspect of
annulus 18 with needles 190 poised to penetrate the annulus in a
direction substantially transverse to the annulus layers. Needle
driver 286 is actuated causing needles 290 to oscillate in and out
of the annulus thereby placing the sutures in a selected pattern
across a desired area of the annulus. As illustrated in FIGS. 30A
and 30B, sutures 288 have been placed over a circumferential
portion of annulus 18 to bridge across a defect therein to form a
suture scaffolding 294. Sutures may be placed solely within the
outer layers of the annulus 18 or may be driven through the entire
thickness of the annulus to within the inner aspect so as to bridge
across the defect at both the inner and outer aspects whereby a
double layer of scaffolding is created. The loose, trailing ends of
sutures 288 are then synched to place tension on the scaffolding
and tied together with a knot or tie mechanism 296 to maintain the
tension. Prosthetic material 298 may then be delivered into defect
28 through scaffolding 294, and subsequently cured, as illustrated
in FIGS. 30C and 30D, respectively.
[0123] FIG. 31A illustrates another embodiment of an implantable
device 300 which is used in tandem with at least one other of the
same device to augment an intervertebral disc. Device 300 include a
base member 302 having a planar configuration and a plurality of
hooked anchors 304 extending from one edge of member 302 and a
plurality of trailing sutures 306 extending from an opposite edge
of base 302.
[0124] As can be seen in FIG. 31 B, a pair of devices 300 is hooked
into the outer aspect of free ends of annulus 18 with the trailing
sutures 306 of each device tied together by a tie or knot mechanism
308 in order to place tension on the annulus and provide a
scaffolding which bridges across void 28. An additional pair of
devices 200 may be similarly implanted at the inner aspect of
annulus 18 with their trailing sutures tied together either
separately from those of the pair of devices on the outer aspect or
together with them.
[0125] FIG. 32A illustrates another embodiment of an implantable
device 310 which may be used alone or in tandem with one other of
the same device to augment an intervertebral disc. Device 310
includes an elongated member 312 having hooked ends 314. Hooks 314
may be oppositely oriented to provide an "S" shape (as shown) or
may be oriented towards the same side of member 312 or in any other
orientation. In use, with the configuration of FIG. 32A, one hook
314 is placed through an outer aspect of annulus 18 on one side of
a defect 28 and the other hook 314 is placed in an inner aspect of
the other side of defect 28, as illustrated in FIG. 32B. FIG. 32B
shows two such devices 310 employed in tandem and placed conversely
of each other with members 312 crossing centrally within void 28 to
provide a scaffolding which bridges the void.
[0126] FIG. 33 illustrates an implantable clamp device 320 of the
present invention for augmenting an intervertebral disc. Implant
320 includes oppositely facing clamps 322, each defined by a back
plate 322a and two opposing sidewalls 322b, 322c, and a plurality
of parallel chords 324 extending transversely between back plates
322a. Clamps 322 each have a plurality of fingers 326 formed in
sidewalls 322b, 322c having inwardly extending teeth 328 for
anchoring into tissue.
[0127] FIG. 34 illustrates the distal end of an insertion tool 330
for use in delivering the device of 320 into a defect within a
disc. Tool 330 has opposing arms 332 which are pivotally coupled to
a handle and operate in a scissor-like fashion with respect to each
other. The distal end 334 of each arm 332 has a laterally extending
distal foot defining an L-shaped configuration and has a slot 335
extending centrally along the length of distal end 334 for
receiving chords 324 of clamp device 320. Proximally positioned of
distal feet 334 are laterally extending feet 336 which are
pivotally coupled to arms 332. The facing surfaces of distal and
proximal feet have top and bottom lip edges 338 to engage against
sidewalls 322b, 322c of clamp device 320 to retain the device upon
loading within tool 330, as illustrated in FIG. 35A.
[0128] Upon positioning the pre-loaded distal end of tool 330
within a void within a disc annulus (tool is shown outside implant
site for clarity in illustration), arms 332 are spread apart
thereby stretching or extending chords 324 of implant 320, as
illustrated in FIG. 35B. At the same time, proximal feet 336 may be
pivoted proximally or backwards so as to facilitate positioning of
the free ends of the annulus within clamp members 322. Next, as
illustrated in FIG. 35C, proximal feet 336 are pivoted distally or
forward to compress sidewalls 322b and 322c together thereby
anchoring clamp members 322 within the respective annulus ends.
Proximal feet 336 are then pivoted backwards again to release the
clamp members, while arms 332 are closed to the extent that the
back plates 322a are cleared, as illustrated in FIG. 35D. Tool 330
is then pulled from the access site, leaving device 320 behind
within the annulus, as illustrated in FIGS. 35E and 35F.
[0129] In a manner similar to that described various times above,
an injector device 60 is then used to inject or extrude prosthetic
material within void 28, as illustrated in FIG. 35G. The spacing
between the chords 324 of device 320 is sufficient to provide a
fluid pathway and allow filling of the intra-annular space with
prosthetic material 340 as shown in FIG. 35H.
[0130] Alternate clamp designs that are usable for clamp-type
augmentation devices of the present invention are illustrated in
FIGS. 36A and 36B. Clamp 350 includes a frame 352 having back plate
352a having apertures 356 for receiving chord ends and sidewalls
352b, 352c terminating in fingers 354 having inwardly extending
anchors 358a. As shown in FIG. 36B, additional anchors 358b may be
provided to ensure retention of the clamps on the annulus. FIG. 37
illustrates a clamp device 360 employing clamp mechanisms 350 of
FIG. 36B interconnected by chords 362.
[0131] As illustrated in FIG. 38A, the comers interconnecting the
sidewalls with the back plate of clamp members 350 may be flexible,
deformable or hinged to allow for straightening of frame 322 (or if
originally provided in a straightened configuration, then for
bending or folding frame 322 to form the configurations illustrated
in FIG. 37) for pre-loading onto a delivery tool 372 in a
low-profile state. Tool 372 is similar to tool 330 of FIG. 34 but
having pivoting distal fee 374 in addition to pivoting proximal
feet 376. A slot (not visible) is provided within distal feet 374
for receiving chords 362 of device 360. The low-profile state
facilitates minimally invasive delivery into an annular defect 28,
as illustrated in FIG. 38A'. Upon proper alignment of device 360
within annulus 18, both sets of feet 374, 376 are pivoted inward
thereby bending sidewalls 352b, 352c of frames 352 to close upon
the free ends of annulus 18, as illustrated in FIGS. 38B and 38B'.
Feet 374, 376 are further advanced toward each other thereby
penetrating anchors 358a, 358b into the annulus tissue as
illustrated in FIGS. 38C and 38C'. All feet are then pivoted apart
to release the clamp members 350, and tool 372 is then pulled from
the access site, leaving device 360 behind within the annulus, as
illustrated in FIGS. 38D.
[0132] In a manner similar to that described above, an injector
device 60 is then used to inject or extrude prosthetic material 360
within void 28, as illustrated in FIG. 38E. The spacing between the
chords 324 of device 320 is sufficient to provide a fluid pathway
and allow filling of the intra-annular space with prosthetic
material 340 as shown in FIG. 38F.
[0133] FIG. 39A-39C illustrates another disc augmentation device
390 having a clip configuration. Device 390 has a plurality of
laterally extending arm pairs 392-395, each arm pair being
pivotable about a central vertical core 396 between open (FIGS. 39A
and 39BA) and closed (FIG. 39C) positions. The arms on each side of
clip 390 may be independently movable of the arms on the opposite
side, or may be collectively movable as illustrated. Each arm may
be directly opposed to another arm on the same side such that they
appose each other when closed, or they may be interdigitated as
illustrated such that they cross when closed (see FIG. 39C),
resulting in a stacked arrangement on each side (i.e., from top to
bottom: 392a, 393a, 394a, 395a and 392b, 393b, 394b, 395b). The
inner sides of the arms may be provided with teeth 398 for
penetrating into engaged or captured tissue, e.g., the annulus,
held between the arms.
[0134] In FIGS. 39B and 39C, disc augmentation device is
operatively coupled to the distal end 402 of actuator rod 400 which
controls the motion of the arms. In an open configuration, clip 390
has a low profile relative to the axis of actuator rod for easy
delivery through delivery sheath 406, as illustrated in FIG. 40A.
Clip 390 is operatively positioned within the intervertebral disc
when its core 396 is substantially centrally positioned within and
along the lamellar planes of annulus 18 and the arms straddle the
opening across the entire thickness of the annulus. A pusher
mechanism 402, having a slot 408 for slidable translation over
actuator rod 400 in a transverse relationship, is advanced distally
against the outer surfaces of proximal arms 392b, 393a, 394b, 395a,
which may be biased open, thereby forcing the arms closed and
clamping or sandwiching the cut or bisected ends of annulus 18
therebetween, as illustrated in FIG. 40B. The arms may be
configured to lock upon achieving a sufficiently closed position or
may be locked in place by means of pusher mechanism 404 which is
left coupled to implanted clip 390.
[0135] In a manner similar to that described above, an injector
device 60 is then used to inject or extrude a prosthetic material
408 within void 28, as illustrated in FIG. 40C. The transverse and
axial spacing between the arms of clip 390 is sufficient to provide
a fluid pathway and allow filling of the intra-annular space with
prosthetic material 408 as shown in FIG. 40D.
[0136] FIG. 41 illustrates another clamp type disc augmentation
device 410 which is an integrated variation of the tandem use of
device 260 of FIG. 27. Device 410 has an endplate 414 and
transversely positioned side plates 412 which collectively form a
U-shaped configuration. A plurality of strands, sutures or
filaments 418 extends from the outer side of endplate 414 and a
plurality of barbed anchors 264 extend from the inside, facing
surfaces of sidewalls 412. The delivery tool 270 of FIGS. 28A and
28B may also be used to implant device 410.
[0137] Referring to FIG. 42A, with device 410 seated between jaws
272, the distal end of tool 270 is positioned within defect 28
within annulus 18 such that a cut or free end of the annulus is
sandwiched between sidewalls 412. Upon proper positioning, the jaws
are compressed thereby driving anchors 416 transversely into the
layers of the annulus 18. The process is repeated with a second
device 410 being clamped to the opposing free end of annulus 18, as
illustrated in FIGS. 42A and 42B. The trailing suture ends 418 of
both devices 410 are synched and tied together by knot mechanism
412, thereby forming a scaffolding between implants 412, as
illustrated in FIG. 42D. As described above, the scaffolding serves
to augment the annulus and allows for passage of a prosthetic
material 414 to within and throughout defect 28, as illustrated in
FIG. 42E. After filling void 28, which may extend into nucleus 20,
prosthetic material 414 is cured, as illustrated in FIG. 42F.
[0138] FIG. 43A illustrates another clamp embodiment of an
implantable device 420 which includes bi-lateral integrated clamps
424 having U-shaped configurations (each similar to the clamp
member of FIG. 41) which are bridged together on one side by bridge
member 422. A plurality of barbed anchors 426 extend from the
inwardly facing surfaces of the respective clamps 424. FIG. 43B
illustrates device 420 operatively implanted within a disc defect
28 and bridging across the portion of the defect within annulus
18.
[0139] FIG. 44A illustrates another clamp embodiment of an
implantable device 430 having two bowed plates 432a, 432b which are
interlocked with each other by a core member 434 extending
centrally between plates 432. The internally facing surfaces of the
ends of plates 432 have barbed anchors 436. A fixed hub or nut 440
is mounted on the distal side of core member 434 and abuts the
outside surface of plate 432. At the opposite end of core member
434 is a threaded hub or nut 438 which can be threaded along a
threaded proximal portion 442 of core member 434. As hub 440 is
threaded against plate 432a, the plates compress together. FIG. 44B
illustrates device 430 operatively implanted within a disc defect
28 and bridging across the portion of the defect within annulus
18.
[0140] FIGS. 45A and 45B illustrate another clamp type embodiment
of an augmentation device 450 which is self-clamping upon
deployment. Device 450 includes two intersecting plates 452 each of
which has two displaced parallel end portions 452a and a central
portion 452b angled therebetween. Opposing sides of end portions
452a have a plurality of barbed anchors 454 extending therefrom and
central portions 452b optionally have a plurality of apertures
formed therein. Plates 452 are preferably made of a superelastic
memory material whereby they can be inverted from a naturally
biased or deployed state (FIG. 45B) to a spring-loaded or
undeployed state (FIG. 45A) where device 450 obtains a low profile
for minimally invasive delivery.
[0141] As illustrated in FIGS. 45A and 46A, in an inverted, low
profile state, device 450 is deliverable through a cannula 460 to
within a void or defect 28 within the annulus wall 18 anchors 454.
As the distal end or pair of end portions 452b are advanced beyond
the distal end of cannula 460, the spring-load of the inverted
device forces distal end portions to spring apart from each other,
as illustrated in FIG. 46B, and impinge upon the inner aspect of
annulus 18, forcing anchors 454 to penetrate into the annulus wall.
Cannula 460 is then removed from the site, as illustrated in FIG.
46C, thereby releasing the proximal end portions of device 450
which in turn allows them to impinge upon the outer aspect of
annulus 18, as illustrated in FIG. 46D. The porous central portions
452b of device 450 allow for passage of a flowable prosthetic
material 462 to within and throughout defect 28, as illustrated in
FIG. 46E. After filling void 28, which may extend into nucleus 20,
prosthetic material 462 is cured, as illustrated in FIG. 46F.
[0142] FIGS. 47A-47D illustrate another clamp type augmentation
device 470 having annulus receiving portions or clamps 474 (only
one side is shown) extending from a bridging portion 472. While
clamp portion 474 may be deformable or compressible, it need not be
as the clamp has holes (not shown) within its sidewalls for
receiving a pin member transversely therethrough, as illustrated in
FIG. 47A, by which to secure the device to tissue received within
clamp portion 472. Pin member includes an outer sheath 476 and
inner core 478 which is slidable within the lumen of sheath 476.
The outer diameter of sheath 476 is sufficient such that it is
receivable within the holes of the sidewalls of clamps 474 and the
inner diameter of sheath 476 is tapered at a distal end 480
thereof. Inner core 478 has an enlarged distal end 482 which has a
diameter which is equal to or less than the inner diameter of
sheath 476 except at the tapered distal end 480, where the diameter
of end 482 is greater than that of the inner diameter of the
tapered distal end portion 480. Outer sheath 476 is splittable at
one or more circumferential locations along at least a distal
portion of its length against the outward radial force exerted on
the distal portion when inner core is driven therethrough. Here,
sheath 476 is splittable into a plurality of petals 488 as
illustrated in the end view of FIG. 47D. Enlarged distal end 482
has a proximal shoulder 484 which engages against petals 488 to
resists against removal of core 478 from outer sheath 476.
[0143] The augmentation device 490 of FIG. 48 has a configuration
similar to that of device 470 of FIGS. 47A-47D with the difference
being that the apertures 496 within the sidewalls of clamp portion
494 have a keyed configuration which correspond to the profile of a
key 498. After passage of key 498 through the second sidewall, it
can be turned about its axis and locked against the outer surface
of the side wall.
[0144] FIGS. 49A-49C illustrate other embodiments of augmentation
devices 500, 510 and 520, respectively, of the present invention
having a cylindrical or tubular configuration. Each device has a
central portion 502, 512 and 522, respectively, from which a
plurality of deformable or flexible fingers or petals 504, 514 and
524, respectively, extend on both sides of the central portion.
Petals 504 of device 500 extend about its entire circumference,
each having a rectangular configuration. Petals 514 of device 510
also extend about the entire circumference of device 510; however,
the petals have a tapered tip. Petals 524 have a rectangular
configuration and extend around only about half of the
circumference of device 520 where about half of the plurality of
petals is positioned opposite the other half.
[0145] FIGS. 50A and 50B illustrate another cylindrical embodiment
of an augmentation device 530 having a similar configuration to
that of device 530 of FIG. 49C, i.e., a central portion 532 and a
plurality of deformable or flexible fingers or petals 534 in two
oppositely positioned sets. Additionally, device 530 includes a
scaffolding structure within the lumen defined by central portion
532. Scaffolding structure includes one or more layers of a
plurality of diametrically extending members or struts 538, but may
have any configuration including any of the scaffolding
configurations, e.g., a plate with apertures, as described
above.
[0146] As illustrated in FIGS. 51A and 51B with respect to device
530, but which is also exemplary of each of the illustrated
cylindrical clip embodiments, each set of petals 534 is deformable
or malleable radially outward from central portion 532 towards the
set of petals positioned at the opposite but same side of central
portion 532.
[0147] A step-by-step implantation procedure of another cylindrical
augmentation device 540 of the present invention is provided in
FIGS. 52A-52F. Device 540 has a configuration similar to that of
device 530, having central portion 542 and two sets of a plurality
of fingers 544 separated by spaces 546. As illustrated in FIGS. 52A
and 52A', in an undeployed, low profile state, device 540 is
advancable to an implant site through a cannula 548 by a detachable
pusher member 552. Extending within pusher 552 is a finger
deployment actuator rod 554. Upon positioning device 540 within the
implant site, i.e., void 28 within annulus 18, cannula 548 may be
removed, as illustrated in FIGS. 52B and 52B'. Actuator rod 554 is
then actuated to commence deployment of fingers 554, as illustrated
in FIGS. 52C and 52C', and continue deployment until fingers 554
achieve a locked position and fully embrace both free ends of
annulus 18 therebetween, as illustrated in FIGS. 52D and 52D'. Upon
full deployment, pusher mechanism 552 is released from core 542
leaving device 540 within the disc defect, as illustrated in FIG.
52E. As described above, an injector tube 64 is positioned within
the scaffolding within device 540 and prosthetic material 558 is
injected therein and subsequently cured as illustrated in FIGS. 52F
and 52G.
[0148] It should be noted that any of the above-described steps or
procedures, including but not limited to cannulation of the target
area, removal of the affected portion of the disc, implantation of
the subject implants within the target implant site, adjustment or
readjustment of the implant, delivery of the prosthetic implant
material and curing of the same may be facilitated by way of a
scope delivered through a lumen of the delivery catheter and/or by
way of various visualization techniques including but not limited
to real time fluoroscopy, CT scanning or MR imaging, or a
combination of preoperative CT or MR images superimposed onto a
real time image tracking device, which are well known in the
surgical arts.
[0149] The subject devices and systems may be provided in the form
of a kit which includes at least one augmentation device of the
present invention. A plurality of such devices may be provided
where the devices have the same or varying sizes and shapes and are
made of the same or varying materials. The kits may further include
instruments and tools for implanting the subject devices, including
but not limited to those described above as well as cannulas,
trocars, scopes, sheaths, etc. Instructions for implanting the
subject systems and devices and for using the above-described
instrumentation may also be provided with the kits.
[0150] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a device" may include a plurality of such
devices and reference to "the prosthetic material" includes
reference to one or more prosthetic materials and equivalents
thereof known to those skilled in the art, and so forth.
[0151] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limits of that range is also specifically disclosed. Each
smaller range between any stated value or intervening value in a
stated range and any other stated or intervening value in that
stated range is encompassed within the invention. The upper and
lower limits of these smaller ranges may independently be included
or excluded in the range, and each range where either, neither or
both limits are included in the smaller ranges is also encompassed
within the invention, subject to any specifically excluded limit in
the stated range. Where the stated range includes one or both of
the limits, ranges excluding either or both of those included
limits are also included in the invention.
[0152] All publications mentioned herein are incorporated herein by
reference to disclose and describe the methods and/or materials in
connection with which the publications are cited. The publications
discussed herein are provided solely for their disclosure prior to
the filing date of the present application. Nothing herein is to be
construed as an admission that the present invention is not
entitled to antedate such publication by virtue of prior invention.
Further, the dates of publication provided may be different from
the actual publication dates which may need to be independently
confirmed.
[0153] The preceding merely illustrates the principles of the
invention. It will be appreciated that those skilled in the art
will be able to devise various arrangements which, although not
explicitly described or shown herein, embody the principles of the
invention and are included within its spirit and scope.
Furthermore, all examples and conditional language recited herein
are principally intended to aid the reader in understanding the
principles of the invention and the concepts contributed by the
inventors to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions. Moreover, all statements herein reciting principles,
aspects, and embodiments of the invention as well as specific
examples thereof, are intended to encompass both structural and
functional equivalents thereof. Additionally, it is intended that
such equivalents include both currently known equivalents and
equivalents developed in the future, i.e., any elements developed
that perform the same function, regardless of structure. The scope
of the present invention, therefore, is not intended to be limited
to the exemplary embodiments shown and described herein. Rather,
the scope and spirit of present invention is embodied by the
appended claims.
* * * * *