U.S. patent application number 12/702228 was filed with the patent office on 2010-08-12 for anulus lesion repair.
This patent application is currently assigned to INTRINSIC THERAPEUTICS, INC.. Invention is credited to THOMAS BOYAJIAN, JACOB EINHORN, SEAN KAVANAUGH, GREGORY H. LAMBRECHT, ROBERT KEVIN MOORE, CHRIS TARAPATA.
Application Number | 20100204797 12/702228 |
Document ID | / |
Family ID | 46303125 |
Filed Date | 2010-08-12 |
United States Patent
Application |
20100204797 |
Kind Code |
A1 |
LAMBRECHT; GREGORY H. ; et
al. |
August 12, 2010 |
ANULUS LESION REPAIR
Abstract
Methods for repairing a damaged or weakened intervertebral disc
are disclosed. According to one or more embodiments, a method
comprises delivering a support member within an intervertebral disc
having an anular defect, anchoring an anchor to a vertebral body
adjacent the intervertebral disc, connecting the anchor to the
support member, and pulling the support member toward the anchor
using the connection.
Inventors: |
LAMBRECHT; GREGORY H.;
(NATICK, MA) ; MOORE; ROBERT KEVIN; (NATICK,
MA) ; EINHORN; JACOB; (BROOKLINE, MA) ;
KAVANAUGH; SEAN; (EASTHAM, MA) ; TARAPATA; CHRIS;
(NORTH ANDOVER, MA) ; BOYAJIAN; THOMAS;
(WILMINGTON, MA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
INTRINSIC THERAPEUTICS,
INC.
WOBURN
MA
|
Family ID: |
46303125 |
Appl. No.: |
12/702228 |
Filed: |
February 8, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10972106 |
Oct 22, 2004 |
7658765 |
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12702228 |
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10970589 |
Oct 21, 2004 |
7553329 |
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10972106 |
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10194428 |
Jul 10, 2002 |
6936072 |
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10970589 |
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10055504 |
Oct 25, 2001 |
7258700 |
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10194428 |
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09696636 |
Oct 25, 2000 |
6508839 |
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10055504 |
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09642450 |
Aug 18, 2000 |
6482235 |
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09696636 |
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09608797 |
Jun 30, 2000 |
6425919 |
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09642450 |
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60513437 |
Oct 22, 2003 |
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60613958 |
Sep 28, 2004 |
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60311586 |
Aug 10, 2001 |
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60149490 |
Aug 18, 1999 |
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60161085 |
Oct 25, 1999 |
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60172996 |
Dec 21, 1999 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61F 2002/30172
20130101; A61F 2002/30909 20130101; A61F 2230/0034 20130101; A61F
2230/0052 20130101; A61F 2310/00017 20130101; A61F 2002/30062
20130101; A61F 2/30723 20130101; A61F 2002/4627 20130101; A61F
2002/30971 20130101; A61F 2230/0056 20130101; A61F 2230/0065
20130101; A61F 2/4601 20130101; A61F 2/30907 20130101; A61F
2002/30228 20130101; A61F 2002/30785 20130101; A61F 2002/30601
20130101; A61F 2002/4661 20130101; A61F 2210/0085 20130101; A61F
2002/4435 20130101; A61F 2002/30131 20130101; A61F 2/4657 20130101;
A61F 2002/30187 20130101; A61F 2230/0004 20130101; A61F 2002/30289
20130101; A61F 2002/30075 20130101; A61F 2230/0082 20130101; A61F
2002/30014 20130101; A61F 2002/30092 20130101; A61F 2002/30166
20130101; A61F 2310/00161 20130101; A61F 2002/30576 20130101; A61F
2002/4662 20130101; A61F 2220/0075 20130101; A61F 2310/00029
20130101; A61F 2002/30589 20130101; A61F 2230/0013 20130101; A61F
2310/00976 20130101; A61F 2/2846 20130101; A61F 2002/30291
20130101; A61F 2002/30583 20130101; A61F 2002/2817 20130101; A61F
2002/30677 20130101; A61F 2250/0018 20130101; A61F 2002/30777
20130101; A61F 2002/30177 20130101; A61F 2002/444 20130101; A61B
2017/320044 20130101; A61F 2/441 20130101; A61F 2/442 20130101;
A61F 2002/302 20130101; A61F 2210/0014 20130101; A61F 2310/00293
20130101; A61B 2017/00261 20130101; A61F 2310/00365 20130101; A61B
2090/062 20160201; A61F 2002/30136 20130101; A61F 2002/30566
20130101; A61F 2002/30571 20130101; A61F 2002/448 20130101; A61F
2210/0004 20130101; A61B 17/320708 20130101; A61B 2017/22077
20130101; A61F 2230/0091 20130101; A61B 2090/061 20160201; A61B
2017/3445 20130101; A61F 2310/00023 20130101; A61F 2310/0097
20130101; A61B 5/4514 20130101; A61F 2002/30224 20130101; A61F
2002/4635 20130101; A61F 2002/4658 20130101; A61F 2210/0061
20130101; A61F 2230/0028 20130101; A61F 2/4611 20130101; A61B
5/1076 20130101; A61F 2002/30261 20130101; A61F 2002/30462
20130101; A61F 2230/0069 20130101 |
Class at
Publication: |
623/17.16 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. A method for repairing an anular lesion of an intervertebral
disc comprising: locating a defect in an anulus fibrosis, wherein
said defect is proximate a herniated segment, wherein the herniated
segment comprises anulus fibrosis tissue; delivering a support
member within the intervertebral disc, wherein the support member
comprises a plate or bar shaped device; securely establishing an
anchor to a vertebral body adjacent said intervertebral disc and
substantially opposite said defect with an anchor; connecting said
anchor to said support member; and returning at least part of the
herniated segment to a pre-herniated position substantially within
a pre-herniated border of the herniated segment by pulling the
support member towards the anchor.
2. The method of claim 1, wherein the vertebral body is a superior
vertebral body.
3. The method of claim 1, wherein the vertebral body is an inferior
vertebral body.
4. The method of claim 1, wherein the anchor is positioned at a
site substantially opposite said defect.
5. The method of claim 1, wherein connecting said anchor to said
support member comprises connecting said anchor to said support
member with a connection member, wherein the connection member is
configured for transmission of a tensile force along its length,
thereby causing the herniated segment to move in the direction of
its pre-herniated border.
6. The method of claim 5, wherein returning at least part of the
herniated segment to a pre-herniated position comprises tightening
the connection member.
7. The method of claim 6, further comprising maintaining tension
between the anchor and the support member with the connection
member once the herniated segment is returned to the pre-herniated
position, thereby restricting motion of the herniated segment to
within the pre-herniated border of the intervertebral disc.
8. The method of claim 1, further comprising positioning said
support member along an innermost layer of the anulus.
9. The method of claim 1, wherein said anchor comprises a bone
anchor.
10. The method of claim 1, further comprising closing said defect
in the anulus fibrosis.
11. The method of claim 1, wherein delivering a support member
within the intervertebral disc comprises delivering the support
member through the defect in the anulus fibrosis.
12. A method for reinforcing an intervertebral disc comprising:
locating a herniated segment in an anulus fibrosis in an
intervertebral disc; wherein the herniated segment comprises an
anulus fibrosis tissue that protrudes outside its pre-herniated
border; delivering a support member through said anulus fibrosis,
wherein the support member comprises a plate or bar shaped device;
securely establishing an anchor to a vertebral body adjacent said
intervertebral disc; connecting the support member and the anchor
with a connection member; tightening the connection member, thereby
returning at least part of the herniated segment to a position
substantially within said pre-herniated border by pulling the
support member towards the anchor.
13. The method of claim 12, wherein tightening the connection
member transmits a tensile force along the length of the connection
member, thereby causing the herniated segment to move in the
direction of its pre-herniated border.
14. The method of claim 12, wherein said anchor comprises a bone
anchor.
15. The method of claim 12, wherein securely establishing said
anchor comprises anchoring said anchor into the vertebral body
adjacent said herniated segment.
16. The method of claim 15, wherein said vertebral body is a
superior vertebral body.
17. The method of claim 15, wherein said vertebral body is an
inferior vertebral body.
18. The method of claim 12, further comprising positioning said
support member along an innermost layer of the anulus.
19. The method of claim 12, further comprising maintaining a
tensile force of the connection member once the at least part of
the herniated segment is retuned to the position substantially
within the pre-herniated border, thereby restricting motion of the
herniated segment to within the pre-herniated border of the
intervertebral disc.
20. The method of claim 12, wherein delivering a support member
through said anulus fibrosis comprises delivering the support
member through a defect in the anulus fibrosis proximate the
herniated segment.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/972,106, filed Oct. 22, 2004, which is a continuation of
U.S. patent application Ser. No. 10/970,589, filed Oct. 21, 2004,
now U.S. Pat. No. 7,553,329, which claims benefit to U.S.
Provisional Application No. 60/513,437, filed Oct. 22, 2003 and
U.S. Provisional Application No. 60/613,958, filed Sep. 28, 2004,
and is a continuation-in-part of U.S. application Ser. No.
10/194,428, filed Jul. 10, 2002, now U.S. Pat. No. 6,936,072, and
is a continuation-in-part of U.S. application Ser. No. 10/055,504,
filed Oct. 25, 2001, now U.S. Pat. No. 7,258,700, which is a
continuation-in-part of U.S. application Ser. No. 09/696,636 filed
on Oct. 25, 2000, now U.S. Pat. No. 6,508,839, which is a
continuation-in-part of U.S. application Ser. No. 09/642,450 filed
on Aug. 18, 2000, now U.S. Pat. No. 6,482,235, which is a
continuation-in-part of U.S. application Ser. No. 09/608,797 filed
on Jun. 30, 2000, now U.S. Pat. No. 6,425,919, and claims benefit
to U.S. Provisional Application No. 60/311,586 filed Aug. 10, 2001,
U.S. Provisional Application No. 60/149,490 filed Aug. 18, 1999,
U.S. Provisional Application No. 60/161,085 filed Oct. 25, 1999 and
U.S. Provisional Application No. 60/172,996 filed Dec. 21, 1999,
the entire teachings of these applications being incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to the surgical
treatment of intervertebral discs in the lumbar, cervical, or
thoracic spine that have suffered from tears in the anulus
fibrosis, herniation of the nucleus pulposus and/or significant
disc height loss.
[0004] 2. Description of the Related Art
[0005] The disc performs the important role of absorbing mechanical
loads while allowing for constrained flexibility of the spine. The
disc is composed of a soft, central nucleus pulposus (NP)
surrounded by a tough, woven anulus fibrosis (AF). Herniation is a
result of a weakening in the AF. Symptomatic herniations occur when
weakness in the AF allows the NP to bulge or leak posteriorly
toward the spinal cord and major nerve roots. The most common
resulting symptoms are pain radiating along a compressed nerve and
low back pain, both of which can be crippling for the patient. The
significance of this problem is increased by the low average age of
diagnosis, with over 80% of patients in the U.S. being under
59.
[0006] Since its original description by Mixter & Barr in 1934,
discectomy has been the most common surgical procedure for treating
intervertebral disc herniation. This procedure involves removal of
disc materials impinging on the nerve roots or spinal cord external
to the disc, generally posteriorly. Depending on the surgeon's
preference, varying amounts of NP are then removed from within the
disc space either through the herniation site or through an
incision in the AF. This removal of extra NP is commonly done to
minimize the risk of recurrent herniation.
[0007] Nevertheless, the most significant drawbacks of discectomy
are recurrence of herniation, recurrence of radicular symptoms, and
increasing low back pain. Re-herniation can occur in up to 21% of
cases. The site for re-herniation is most commonly the same level
and side as the previous herniation and can occur through the same
weakened site in the AF. Persistence or recurrence of radicular
symptoms happens in many patients and when not related to
re-herniation, tends to be linked to stenosis of the neural
foramina caused by a loss in height of the operated disc.
Debilitating low back pain occurs in roughly 14% of patients. All
of these failings are most directly related to the loss of NP
material and AF competence that results from herniation and
surgery.
[0008] Various implants, surgical meshes, patches, barriers, tissue
scaffolds and the like may be used to treat intervertebral discs
and are known in the art. Surgical repair meshes are used
throughout the body to treat and repair damaged tissue structures
such as intralinguinal hernias, herniated discs and to close
iatrogenic holes and incisions as may occur elsewhere. Certain
physiological environments present challenges to precise and
minimally invasive delivery.
[0009] An intervertebral disc provides a dynamic environment that
produces high loads and pressures. Typically implants designed for
this environment must be capable of enduring such conditions for
long periods of time. Also, the difficulty and danger of the
implantation procedure itself, due to the proximity of the spinal
cord, limits the size and ease of placement of the implant. One or
more further embodiments of the invention addresses the need for a
durable fatigue resistant repair mesh capable of withstanding the
dynamic environment generic to intervertebral discs.
SUMMARY OF THE INVENTION
[0010] Several embodiments of the present invention relate
generally to anulus augmentation devices, including, but not
limited to, surgical meshes, barriers, and patches for treatment or
augmentation of tissues within pathologic spinal discs. One or more
embodiments comprise resilient surgical meshes that may be
compressed for minimally invasive delivery and which are robust,
stable, and resist fatigue and stress. These meshes are
particularly well suited for intervertebral disc applications
because they are durable enough to withstand intense cyclical
loading and resist expulsion through a defect while not degrading
over time.
[0011] Several embodiments of the present invention seek to exploit
the individual characteristics of various anulus and nuclear
augmentation devices to optimize the performance of both within the
intervertebral disc. Accordingly, one or more of the embodiments of
the present invention provide minimally invasive and removable
devices for closing a defect in an anulus and augmenting the
nucleus. These devices may be permanent, semi-permanent, or
removable. One function of anulus augmentation devices is to
prevent or minimize the extrusion of materials from within the
space normally occupied by the nucleus pulposus and inner anulus
fibrosus. One function of nuclear augmentation devices is to at
least temporarily add material to restore diminished disc height
and pressure. Nuclear augmentation devices can also induce the
growth or formation of material within the nuclear space.
Accordingly, the inventive combination of these devices can create
a synergistic effect wherein the anulus and nuclear augmentation
devices serve to restore biomechanical function in a more natural
biomimetic way. Furthermore, in one embodiment, both devices may be
delivered more easily and less invasively. Also, in some
embodiments, the pressurized environment made possible through the
addition of nuclear augmentation material and closing of the anulus
serves both to restrain the nuclear augmentation and anchor the
anulus augmentation in place.
[0012] As used herein, the phrase "anulus augmentation device"
shall be given its ordinary meaning and shall also include devices
that at least partially cover, close or seal a defect in an
intervertebral disc, including, for example, barriers, meshes,
patches, membranes, sealing means or closure devices. Thus, in one
sense, the anulus augmentation device augments the anulus by
sealing a defect in the anulus. In some embodiments, one or more
barriers, meshes, patches, membranes, sealing means or closure
devices comprise a support member or frame. Thus, in one
embodiment, a barrier that comprises a membrane and a frame is
provided. As used herein, the terms augmenting or reinforcing (and
variations thereto) shall be given their ordinary meaning and shall
also mean supporting, covering, closing, patching, or sealing.
[0013] In one embodiment, one or more anulus augmentation devices
are provided with one or more nuclear augmentation devices. In some
embodiments, the anulus barrier is integral with the nucleus
augmentation. In other embodiments, at least a portion of the
barrier is separate from or independent of the nuclear
augmentation.
[0014] One or more of the embodiments of the present invention
additionally provide an anulus augmentation device that is adapted
for use with flowable nuclear augmentation material such that the
flowable material cannot escape from the anulus after the anulus
augmentation device has been implanted.
[0015] In one embodiment of the present invention, a disc
augmentation system configured to repair or rehabilitate an
intervertebral disc is provided. The system comprises at least one
anulus augmentation device, and at least one nuclear augmentation
material. The anulus augmentation device prevents or minimizes the
extrusion of materials from within the space normally occupied by
the nucleus pulposus and inner anulus fibrosus. In one application
of the invention, the anulus augmentation device is configured for
minimally invasive implantation and deployment. The anulus
augmentation device may either be a permanent implant, or it may
removable.
[0016] The nuclear augmentation material may restore diminished
disc height and/or pressure. It may include factors for inducing
the growth or formation of material within the nuclear space. It
may either be permanent, removable, or absorbable.
[0017] The nuclear augmentation material may be in the form of
liquids, gels, solids, or gases. In one embodiment, the nuclear
augmentation material comprises materials selected from the group
consisting of one or more of the following: steroids, antibiotics,
tissue necrosis factors, tissue necrosis factor antagonists,
analgesics, growth factors, genes, gene vectors, hyaluronic acid,
noncross-linked collagen, collagen, fibren, liquid fat, oils,
synthetic polymers, polyethylene glycol, liquid silicones,
synthetic oils, saline and hydrogel. The hydrogel may be selected
from the group consisting of one or more of the following:
acrylonitriles, acrylic acids, polyacrylimides, acrylimides,
acrylimidines, polyacryInitriles, and polyvinyl alcohols.
[0018] Solid form nuclear augmentation materials may be in the form
of geometric shapes such as cubes, spheroids, disc-like components,
ellipsoid, rhombohedral, cylindrical, or amorphous. The solid
material may be in powder form, and may be selected from the group
consisting of one or more of the following: titanium, stainless
steel, nitinol, cobalt, chrome, resorbable materials, polyurethane,
polyesther, PEEK, PET, FEP, PTFE, ePTFE, PMMA, nylon, carbon fiber,
Delrin, polyvinyl alcohol gels, polyglycolic acid, polyethylene
glycol, silicone gel, silicone rubber, vulcanized rubber,
gas-filled vesicles, bone, hydroxy apetite, collagen such as
cross-linked collagen, muscle tissue, fat, cellulose, keratin,
cartilage, protein polymers, transplanted nucleus pulposus,
bioengineered nucleus pulposus, transplanted anulus fibrosis, and
bioengineered anulus fibrosis. Structures may also be utilized,
such as inflatable balloons or other inflatable containers, and
spring-biased structures.
[0019] The nuclear augmentation material may additionally comprise
a biologically active compound. The compound may be selected from
the group consisting of one or more of the following: drug
carriers, genetic vectors, genes, therapeutic agents, growth
renewal agents, growth inhibitory agents, analgesics,
anti-infectious agents, and anti-inflammatory drugs.
[0020] In one embodiment, the anulus augmentation device comprises
materials selected from the group consisting of one or more of the
following: steroids, antibiotics, tissue necrosis factors, tissue
necrosis factor antagonists, analgesics, growth factors, genes,
gene vectors, hyaluronic acid, noncross-linked collagen, collagen,
fibren, liquid fat, oils, synthetic polymers, polyethylene glycol,
liquid silicones, synthetic oils, saline, hydrogel (e.g.,
acrylonitriles, acrylic acids, polyacrylimides, acrylimides,
acrylimidines, polyacryInitriles, and polyvinyl alcohols), and
other suitable materials.
[0021] In some embodiments, the anulus augmentation device is
constructed from one or more of the following materials: titanium,
stainless steel, nitinol, cobalt, chrome, resorbable materials,
polyurethane, polyesther, PEEK, PET, FEP, PTFE, ePTFE, PMMA, nylon,
carbon fiber, Delrin, polyvinyl alcohol gels, polyglycolic acid,
polyethylene glycol, silicone gel, silicone rubber, vulcanized
rubber, gas-filled vesicles, bone, hydroxy apetite, collagen such
as cross-linked collagen, muscle tissue, fat, cellulose, keratin,
cartilage, and protein polymers. Transplanted anulus fibrosis and
bioengineered anulus fibrosis may also be used to form the barrier,
sealing device, closing device or membrane. Inflatable balloons or
other inflatable containers, and spring-biased structures may also
be used.
[0022] The anulus augmentation device may comprise a biologically
active compound. The compound may be selected from the group
consisting of one or more of the following: drug carriers, genetic
vectors, genes, therapeutic agents, growth renewal agents, growth
inhibitory agents, analgesics, anti-infectious agents, and
anti-inflammatory drugs. In some embodiments, the biologically
active compound is coupled to the barrier, sealing device, closing
device or membrane. In some embodiments, the biologically active
compound coats the barrier, sealing device, closing device or
membrane.
[0023] In one embodiment, an anulus augmentation device for
reinforcing an intervertebral disc is provided. In one embodiment,
the anulus augmentation device comprises a mesh frame, wherein the
mesh frame comprises a plurality of flexible curvilinear members.
In one embodiment, the curvalinear elements are interconnected. The
interconnected curvilinear members are adapted to provide
flexibility and resilience to the mesh frame. In some embodiments,
the curvilinear members form a horizontal member or central strut.
In one embodiment, the curvilinear members are arranged in a
parallel configuration.
[0024] In one embodiment, the curvilinear members comprise a metal
alloy such as steel, nickel titanium, cobalt chrome, or
combinations thereof.
[0025] In some embodiments, the curvilinear members are constructed
of nylon, polyvinyl alcohol, polyethylene, polyurethane,
polypropylene, polycaprolactone, polyacrylate, ethylene-vinyl
acetate, polystyrene, polyvinyl oxide, polyvinyl fluoride,
polyvinyl imidazoles, chlorosulphonated polyolefin, polyethylene
oxide, polytetrafluoroethylene, acetal,
poly(p-phenyleneterephtalamide) (Kevlar.TM.), poly carbonate,
carbon, graphite, or a combination thereof.
[0026] In one embodiment, a membrane encapsulates, covers or coats
at least a portion of the mesh frame. In some embodiments, the
membrane is coupled to the frame.
[0027] The membrane of some embodiments is constructed of polymers,
elastomers, gels, elastin, albumin, collagen, fibrin, keratin, or a
combination thereof. In several embodiments, the membrane comprises
antibodies, antiseptics, genetic vectors, bone morphogenic
proteins, steroids, cortisones, growth factors, or a combination
thereof. The membrane may be a coating material.
[0028] In one embodiment, the mesh frame is concave along at least
a portion of at least one axis of said mesh frame. In one
embodiment, the mesh frame has a length in the range of about 0.5
cm to about 5 cm. One of skill in the art will understand that
other lengths can also be used. In some embodiments, the mesh frame
is sized to cover at least a portion of an interior surface of an
anulus lamella. In other embodiments, the mesh frame is adapted to
extend circumferentially along the entire surface of an anulus
lamella.
[0029] In one embodiment, an anulus augmentation device comprising
at least one projection that radiates from a mesh frame is
provided. In one embodiment, the mesh frame has a vertical
cross-section that is flat, concave, convex, or curvilinear. The
horizontal cross-section can be concave, convex, flat, or kidney
bean shaped. Other shapes can also be used.
[0030] In one embodiment of the present invention, an anulus
augmentation device for reinforcing an intervertebral disc
comprises a mesh frame having a horizontal axis and a vertical
axis. In one embodiment, the mesh frame is concave along at least a
portion the horizontal axis or the vertical axis. In one
embodiment, one or more projections radiate from the horizontal
axis or the vertical axis of the mesh frame. The projections are
adapted to stabilize the anulus augmentation device. In one
embodiment, a stabilizing projection has at least one dimension
that is larger than the mesh frame. In other embodiments, the
projection is smaller than the mesh frame.
[0031] In yet another embodiment of the present invention, an
intervertebral disc implant comprising a posterior support member
having a first terminus and a second terminus is provided. In one
embodiment, an anterior projection extends outwardly from the
posterior support member. The anterior projection is attached to at
least the first terminus or the second terminus of the posterior
support member.
[0032] In another embodiments, an intervertebral disc implant
comprising a posterior support member having a first terminus and a
second terminus and an anterior projection having a first end and a
second end is provided. The anterior projection extends outwardly
from the posterior support member. In one embodiment, the first end
of the anterior projection is coupled to the first terminus of the
posterior support member; and the second end of the anterior
projection is coupled to the second terminus of the posterior
support member, thereby substantially forming a bow-shaped implant.
The posterior support member and the anterior projection can be
constructed of any suitable material, including but not limited to
the materials described above for the mesh frame and the
membrane.
[0033] In a further embodiment of the present invention, a
fatigue-resistant surgical mesh comprising rails is provided. In
one embodiment, the mesh comprises a top rail, a bottom rail
coupled to the top rail, wherein the top rail and said bottom rail
are coupled to each other at a first end and second end. In one
embodiment, the top rail and the bottom rail extend to form a gap
that is defined between the rails along at least a portion of the
distance between the ends.
[0034] In one embodiment of the present invention, a spinal implant
for treatment of an intervertebral disc is provided. In one
embodiment, a barrier or patch with a volume corresponding to the
amount of material removed during a discectomy procedure is
implanted. In one embodiment, the implant has a volume in a range
of about 0.2 to about 2.0 cc.
[0035] In one embodiment of the invention, an intervertebral disc
implant comprising a barrier forming a contiguous band is provided.
In one embodiment, the band has variable heights or widths. In one
embodiment, the band has different degrees of flexibility along at
least one axis.
[0036] In another embodiment of the present invention, a method of
repairing or rehabilitating an intervertebral disc is provided. The
method comprises inserting at least one anulus augmentation device
into the disc, and inserting at least one nuclear augmentation
material, to be held within the disc by the anulus augmentation
device. The nuclear augmentation material may conform to a first,
healthy region of the anulus, while the anulus augmentation device
conforms to a second, weaker region of the anulus.
[0037] In a further embodiment, a method of repairing defective
regions within a spinal disc is provided. In one embodiment, the
method comprises providing a surgical mesh, implanting the surgical
mesh along an anulus surface, and positioning the surgical mesh at
least such that about 2 mm of the device spans beyond at least one
edge of the defective region of the disc.
[0038] Further features and advantages of embodiments of the
present invention will become apparent to those of skill in the art
in view of the detailed description of preferred embodiments which
follows, when taken together with the attached drawings and
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The foregoing and other objects, features and advantages of
the invention will be apparent from the following more particular
description of preferred embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating the principles of the invention.
[0040] FIG. 1A shows a transverse section of a portion of a
functional spine unit, in which part of a vertebra and
intervertebral disc are depicted.
[0041] FIG. 1B shows a sagittal cross section of a portion of a
functional spine unit shown in FIG. 1A, in which two lumbar
vertebrae and the intervertebral disc are visible.
[0042] FIG. 1C shows partial disruption of the inner layers of an
anulus fibrosis.
[0043] FIG. 2A shows a transverse section of one aspect of the
present invention prior to supporting a herniated segment, as shown
in one embodiment.
[0044] FIG. 2B shows a transverse section of the construct in FIG.
2A supporting the herniated segment.
[0045] FIG. 3A shows a transverse section of another embodiment of
the disclosed invention after placement of the device.
[0046] FIG. 3B shows a transverse section of the construct in FIG.
3A after tension is applied to support the herniated segment.
[0047] FIG. 4A shows a transverse view of an alternate embodiment
of the invention.
[0048] FIG. 4B shows a sagittal view of the alternate embodiment
shown in FIG. 4A.
[0049] FIG. 5A shows a transverse view of another aspect of the
present invention, as shown in one embodiment.
[0050] FIG. 5B shows the delivery tube of FIG. 5A being used to
displace the herniated segment to within its pre-herniated
borders.
[0051] FIG. 5C shows a one-piece embodiment of the invention in an
anchored and supporting position.
[0052] FIG. 6 shows one embodiment of the invention supporting a
weakened posterior anulus fibrosis.
[0053] FIG. 7A shows a transverse section of another aspect of the
disclosed invention demonstrating two stages involved in
augmentation of the soft tissues of the disc.
[0054] FIG. 7B shows a sagittal view of the invention shown in FIG.
7A.
[0055] FIG. 8 shows a transverse section of one aspect of the
disclosed invention involving augmentation of the soft tissues of
the disc and support/closure of the anulus fibrosis.
[0056] FIG. 9A shows a transverse section of one aspect of the
invention involving augmentation of the soft tissues of the disc
with the flexible augmentation material anchored to the anterior
lateral anulus fibrosis.
[0057] FIG. 9B shows a transverse section of one aspect of the
disclosed invention involving augmentation of the soft tissues of
the disc with the flexible augmentation material anchored to the
anulus fibrosis by a one-piece anchor.
[0058] FIG. 10A shows a transverse section of one aspect of the
disclosed invention involving augmentation of the soft tissues of
the disc.
[0059] FIG. 10B shows the construct of FIG. 10A after the
augmentation material has been inserted into the disc.
[0060] FIG. 11 illustrates a transverse section of a barrier
mounted within an anulus.
[0061] FIG. 12 shows a sagittal view of the barrier of FIG. 11.
[0062] FIG. 13 shows a transverse section of a barrier anchored
within a disc.
[0063] FIG. 14 illustrates a sagittal view of the barrier shown in
FIG. 13.
[0064] FIG. 15 illustrates the use of a second anchoring device for
a barrier mounted within a disc.
[0065] FIG. 16A is an transverse view of the intervertebral
disc.
[0066] FIG. 16B is a sagittal section along the midline of the
intervertebral disc.
[0067] FIG. 17 is an axial view of the intervertebral disc with the
right half of a sealing means of a barrier means being placed
against the interior aspect of a defect in anulus fibrosis by a
dissection/delivery tool.
[0068] FIG. 18 illustrates a full sealing means placed on the
interior aspect of a defect in anulus fibrosis.
[0069] FIG. 19 depicts the sealing means of FIG. 18 being secured
to tissues surrounding the defect.
[0070] FIG. 20 depicts the sealing means of FIG. 19 after fixation
means have been passed into surrounding tissues.
[0071] FIG. 21A depicts an axial view of the sealing means of FIG.
20 having enlarging means inserted into the interior cavity.
[0072] FIG. 21B depicts the construct of FIG. 21 in a sagittal
section.
[0073] FIG. 22A shows an alternative fixation scheme for the
sealing means and enlarging means.
[0074] FIG. 22B shows the construct of FIG. 22A in a sagittal
section with an anchor securing a fixation region of the enlarging
means to a superior vertebral body in a location proximate to the
defect.
[0075] FIG. 23A depicts an embodiment of the barrier means of the
present invention being secured to an anulus using fixation means,
as shown in one embodiment.
[0076] FIG. 23B depicts an embodiment of the barrier means of FIG.
23A secured to an anulus by two fixation darts wherein the fixation
tool has been removed.
[0077] FIGS. 24A and 24B depict a barrier means positioned between
layers of the anulus fibrosis on either side of a defect.
[0078] FIG. 25 depicts an axial cross section of a large version of
a barrier means.
[0079] FIG. 26 depicts an axial cross section of a barrier means in
position across a defect following insertion of two augmentation
devices.
[0080] FIG. 27 depicts the barrier means as part of an elongated
augmentation device.
[0081] FIG. 28A depicts an axial section of an alternate
configuration of the augmentation device of FIG. 27.
[0082] FIG. 28B depicts a sagittal section of an alternate
configuration of the augmentation device of FIG. 27.
[0083] FIGS. 29A-D depict deployment of a barrier from an entry
site remote from the defect in the anulus fibrosis.
[0084] FIGS. 30A, 30B, 31A, 31B, 32A, 32B, 33A, and 33B depict
axial and sectional views, respectively, of various embodiments of
the barrier.
[0085] FIG. 34 shows a non-axisymmetric expansion means or
frame.
[0086] FIGS. 34B and 34C illustrate perspective views of a frame
mounted within an intervertebral disc.
[0087] FIGS. 35 and 36 illustrate alternate embodiments of the
expansion means shown in FIG. 34.
[0088] FIGS. 37A-C illustrate a front, side, and perspective view,
respectively, of an alternate embodiment of the expansion means
shown in FIG. 34.
[0089] FIG. 38 shows an alternate expansion means to that shown in
FIG. 37A.
[0090] FIGS. 39A-D illustrate a tubular expansion means having a
circular cross-section.
[0091] FIGS. 40A-I illustrate tubular expansion means. FIGS. 40A-D
illustrate a tubular expansion means having an oval shaped
cross-section. FIGS. 40E, 40F and 401 illustrate a front, back and
top view, respectively of the tubular expansion means of FIG. 40A
having a sealing means covering an exterior surface of an anulus
face. FIGS. 40G and 40H show the tubular expansion means of FIG.
40A having a sealing means covering an interior surface of an
anulus face.
[0092] FIGS. 41A-D illustrate a tubular expansion means having an
egg-shaped cross-section.
[0093] FIG. 42A-D depicts cross sections of a preferred embodiment
of sealing and enlarging means.
[0094] FIGS. 43A and 43B depict an alternative configuration of
enlarging means.
[0095] FIGS. 44A and 44B depict an alternative shape of the barrier
means.
[0096] FIG. 45 is a section of a device used to affix sealing means
to tissues surrounding a defect.
[0097] FIG. 46 depicts the use of a thermal device to heat and
adhere sealing means to tissues surrounding a defect.
[0098] FIG. 47 depicts an expandable thermal element that can be
used to adhere sealing means to tissues surrounding a defect.
[0099] FIG. 48 depicts an alternative embodiment to the thermal
device of FIG. 46.
[0100] FIGS. 49A-G illustrate a method of implanting an intradiscal
implant.
[0101] FIGS. 50A-F show an alternate method of implanting an
intradiscal implant.
[0102] FIGS. 51A-C show another alternate method of implanting an
intradiscal implant.
[0103] FIGS. 52A and 52B illustrate an implant guide used with the
intradiscal implant system.
[0104] FIG. 53A illustrates a barrier having stiffening plate
elements.
[0105] FIG. 53B illustrates a sectional view of the barrier of FIG.
53A.
[0106] FIG. 54A shows a stiffening plate.
[0107] FIG. 54B shows a sectional view of the stiffening plate of
FIG. 54A.
[0108] FIG. 55A illustrates a barrier having stiffening rod
elements.
[0109] FIG. 55B illustrates a sectional view of the barrier of FIG.
55A.
[0110] FIG. 56A illustrates a stiffening rod.
[0111] FIG. 56B illustrates a sectional view of the stiffening rod
of FIG. 56A.
[0112] FIG. 57 shows an alternate configuration for the location of
the fixation devices of the barrier of FIG. 44A.
[0113] FIGS. 58A and 58B illustrate a dissection device for an
intervertebral disc.
[0114] FIGS. 59A and 59B illustrate an alternate dissection device
for an intervertebral disc.
[0115] FIGS. 60A-C illustrate a dissector component.
[0116] FIGS. 61A-D illustrate a method of inserting a disc implant
within an intervertebral disc.
[0117] FIG. 62 depicts a cross-sectional transverse view of a
barrier device implanted within a disc along the inner surface of a
lamella. Implanted conformable nuclear augmentation is also shown
in contact with the barrier.
[0118] FIG. 63 shows a cross-sectional transverse view of a barrier
device implanted within a disc along an inner surface of a lamella.
Implanted nuclear augmentation comprised of a hydrophilic flexible
solid is also shown.
[0119] FIG. 64 shows a cross-sectional transverse view of a barrier
device implanted within a disc along an inner surface of a lamella.
Several types of implanted nuclear augmentation including a solid
geometric shape, a composite solid, and a free flowing liquid are
also shown.
[0120] FIG. 65 illustrates a sagittal cross-sectional view of a
barrier device connected to an inflatable nuclear augmentation
device.
[0121] FIG. 66 depicts a sagittal cross-sectional view of a
functional spine unit containing a barrier device unit connected to
a wedge shaped nuclear augmentation device.
[0122] FIG. 67 shows an anulus augmentation device (such as a mesh)
mesh having a series of curvilinear elements.
[0123] FIGS. 68A-G show profiles and cross-sectional views of an
anulus augmentation device (such as a mesh), e.g., "U" shaped, "C"
shaped, curvilinear shaped, and "D" shaped to extend along and
cover the entire inner anulus surface, or portions.
[0124] FIG. 69 shows one embodiment of a mesh with curvilinear
elements implanted in an intervertebral disc.
[0125] FIG. 70 shows a wire-type anulus augmentation device.
[0126] FIGS. 71A-E show a frame (e.g., mesh) that has been
encapsulated by a membrane or cover to produce an encapsulated
mesh.
[0127] FIGS. 72A-B show a mesh having a double-wishbone frame.
[0128] FIGS. 73A-C shows embodiments of the end or natural hinge
portion of the frame, including a looped terminus.
[0129] FIGS. 74A-C show some embodiments of the central band or
strut.
[0130] FIGS. 75A-L show an implant an annulus augmentation device
such as a mesh having one or more projections extending into the
disc or into a defect.
[0131] FIG. 76 shows an implant comprising a bow-like anterior
projection that extends outwardly from a posterior support
member.
[0132] FIGS. 77A-H show various cross-sectional side views along a
horizontal axis of an implant comprising a bow, band or
projection.
[0133] FIGS. 78A-J show various cross-sectional top views of
implants along a vertical axis.
[0134] FIGS. 79A-F show a frontal view of a portion of several
embodiments of an implant projection.
[0135] FIGS. 80A-D show various cross-sections of an implant
projection.
[0136] FIGS. 81A-D show looped or bent bow-type projections.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0137] Several embodiments of the present invention provide for an
in vivo augmented functional spine unit. A functional spine unit
includes the bony structures of two adjacent vertebrae (or
vertebral bodies), the soft tissue (anulus fibrosis (AF), and
optionally nucleus pulposus (NP)) of the intervertebral disc, and
the ligaments, musculature and connective tissue connected to the
vertebrae. The intervertebral disc is substantially situated in the
intervertebral space formed between the adjacent vertebrae.
Augmentation of the functional spine unit can include repair of a
herniated disc segment, support of a weakened, torn or damaged
anulus fibrosis, or the addition of material to or replacement of
all or part of the nucleus pulposus. Augmentation of the functional
spine unit is provided by herniation constraining devices and disc
augmentation devices situated in the intervertebral disc space.
[0138] FIGS. 1A and 1B show the general anatomy of a functional
spine unit 45. In this description and the following claims, the
terms `anterior` and `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 organ,
posterior is a direction toward the back (dorsal) side of the body
or organ; superior is upward (toward the head) and inferior is
lower (toward the feet).
[0139] FIG. 1A is an axial view along the transverse axis M of a
vertebral body with the intervertebral disc 15 superior to the
vertebral body. Axis M shows the anterior (A) and posterior (P)
orientation of the functional spine unit within the anatomy. The
intervertebral disc 15 contains the anulus fibrosis (AF) 10 which
surrounds a central nucleus pulposus (NP) 20. A Herniated segment
30 is depicted by a dashed-line. The herniated segment 30 protrudes
beyond the pre-herniated posterior border 40 of the disc. Also
shown in this figure are the left 70 and right 70' transverse
spinous processes and the posterior spinous process 80.
[0140] FIG. 1B is a sagittal section along sagittal axis N through
the midline of two adjacent vertebral bodies 50 (superior) and 50'
(inferior). Intervertebral disc space 55 is formed between the two
vertebral bodies and contains intervertebral disc 15, which
supports and cushions the vertebral bodies and permits movement of
the two vertebral bodies with respect to each other and other
adjacent functional spine units.
[0141] Intervertebral disc 15 is comprised of the outer AF 10 which
normally surrounds and constrains the NP 20 to be wholly within the
borders of the intervertebral disc space. In FIGS. 1A and 1B,
herniated segment 30, represented by the dashed-line, has migrated
posterior to the pre-herniated border 40 of the posterior AF of the
disc. Axis M extends between the anterior (A) and posterior (P) of
the functional spine unit. The vertebral bodies also include facet
joints 60 and the superior 90 and inferior 90' pedicle that form
the neural foramen 100. Disc height loss occurs when the superior
vertebral body 50 moves inferiorly relative to the inferior
vertebral body 50'.
[0142] Partial disruption 121 of the inner layers of the anulus 10
without a true perforation has also been linked to chronic low back
pain. Such a disruption 4 is illustrated in FIG. 1C. It is thought
that weakness of these inner layers forces the sensitive outer
anulus lamellae to endure higher stresses. This increased stress
stimulates the small nerve fibers penetrating the outer anulus,
which results in both localized and referred pain.
[0143] In one embodiment of the present invention, the disc
herniation constraining devices 13 provide support for returning
all or part of the herniated segment 30 to a position substantially
within its pre-herniated borders 40. The disc herniation
constraining device includes an anchor which is positioned at a
site within the functional spine unit, such as the superior or
inferior vertebral body, or the anterior medial, or anterior
lateral anulus fibrosis. The anchor is used as a point against
which all or part of the herniated segment is tensioned so as to
return the herniated segment to its pre-herniated borders, and
thereby relieve pressure on otherwise compressed neural tissue and
structures. A support member is positioned in or posterior to the
herniated segment, and is connected to the anchor by a connecting
member. Sufficient tension is applied to the connecting member so
that the support member returns the herniated segment to a
pre-herniated position. In various embodiments, augmentation
material is secured within the intervertebral disc space, which
assists the NP in cushioning and supporting the inferior and
superior vertebral bodies. An anchor secured in a portion of the
functional spine unit and attached to the connection member and
augmentation material limits movement of the augmentation material
within the intervertebral disc space. A supporting member, located
opposite the anchor, may optionally provide a second point of
attachment for the connection member and further hinder the
movement of the augmentation material within the intervertebral
disc space.
[0144] FIGS. 2A and 2B depict one embodiment of device 13. FIG. 2A
shows the elements of the constraining device in position to
correct the herniated segment. Anchor 1 is securely established in
a location within the functional spine unit, such as the anterior
AF shown in the figure. Support member 2 is positioned in or
posterior to herniated segment 30. Leading from and connected to
anchor 1 is connection member 3, which serves to connect anchor 1
to support member 2. Depending on the location chosen for support
member 2, the connection member may traverse through all or part of
the herniated segment.
[0145] FIG. 2B shows the positions of the various elements of the
herniation constraining device 13 when the device 13 is supporting
the herniated segment. Tightening connection member 2 allows it to
transmit tensile forces along its length, which causes herniated
segment 30 to move anteriorly, i.e., in the direction of its
pre-herniated borders. Once herniated segment 30 is in the desired
position, connection member 3 is secured in a permanent fashion
between anchor 1 and support member 2. This maintains tension
between anchor 1 and support member 2 and restricts motion of the
herniated segment to within the pre-herniated borders 40 of the
disc. Support member 2 is used to anchor to herniated segment 30,
support a weakened AF in which no visual evidence of herniation is
apparent, and may also be used to close a defect in the AF in the
vicinity of herniated segment 30.
[0146] Anchor 1 is depicted in a representative form, as it can
take one of many suitable shapes, be made from one of a variety of
biocompatible materials, and be constructed so as to fall within a
range of stiffness. It can be a permanent device constructed of
durable plastic or metal or can be made from a resorbable material
such as polylactic acid (PLA) or polyglycolic acid (PGA). Specific
embodiments are not shown, but many possible designs would be
obvious to anyone skilled in the art. Embodiments include, but are
not limited to, a barbed anchor made of PLA or a metal coil that
can be screwed into the anterior AF. Anchor 1 can be securely
established within a portion of the functional spine unit in the
usual and customary manner for such devices and locations, such as
being screwed into bone, sutured into tissue or bone, or affixed to
tissue or bone using an adhesive method, such as cement, or other
suitable surgical adhesives. Once established within the bone or
tissue, anchor 1 should remain relatively stationary within the
bone or tissue.
[0147] Support member 2 is also depicted in a representative format
and shares the same flexibility in material and design as anchor 1.
Both device elements can be of the same design, or they can be of
different designs, each better suited to being established in
healthy and diseased tissue respectively. Alternatively, in other
forms, support member 2 can be a cap or a bead shape, which also
serves to secure a tear or puncture in the AF, or it can be bar or
plate shaped, with or without barbs to maintain secure contact with
the herniated segment. Support member 2 can be established securely
to, within, or posterior to the herniated segment.
[0148] The anchor and support member can include suture, bone
anchors, soft tissue anchors, tissue adhesives, and materials that
support tissue ingrowth although other forms and materials are
possible. They may be permanent devices or resorbable. Their
attachment to a portion of FSU and herniated segment must be strong
enough to resist the tensional forces that result from repair of
the hernia and the loads generated during daily activities.
[0149] Connection member 3 is also depicted in representative
fashion. Member 3 may be in the format of a flexible filament, such
as a single or multi-strand suture, wire, or perhaps a rigid rod or
broad band of material, for example. The connection member can
further include suture, wire, pins, and woven tubes or webs of
material. It can be constructed from a variety of materials, either
permanent or resorbable, and can be of any shape suitable to fit
within the confines of the intervertebral disc space. The material
chosen is preferably adapted to be relatively stiff while in
tension, and relatively flexible against all other loads. This
allows for maximal mobility of the herniated segment relative to
the anchor without the risk of the supported segment moving outside
of the pre-herniated borders of the disc. The connection member may
be an integral component of either the anchor or support member or
a separate component. For example, the connection member and
support member could be a length of non-resorbing suture that is
coupled to an anchor, tensioned against the anchor, and sewn to the
herniated segment.
[0150] FIGS. 3A and 3B depict another embodiment of device 13. In
FIG. 3A the elements of the herniation constraining device are
shown in position prior to securing a herniated segment. Anchor 1
is positioned in the AF and connection member 3 is attached to
anchor 1. Support member 4 is positioned posterior to the
posterior-most aspect of herniated segment 30. In this way, support
member 4 does not need to be secured in herniated segment 30 to
cause herniated segment 30 to move within the pre-herniated borders
40 of the disc. Support member 4 has the same flexibility in design
and material as anchor 1, and may further take the form of a
flexible patch or rigid plate or bar of material that is either
affixed to the posterior aspect of herniated segment 30 or is
simply in a form that is larger than any hole in the AF directly
anterior to support member 4. FIG. 3B shows the positions of the
elements of the device when tension is applied between anchor 1 and
support member 4 along connection member 3. The herniated segment
is displaced anteriorly, within the pre-herniated borders 40 of the
disc.
[0151] FIGS. 4A and 4B show five examples of suitable anchoring
sites within the FSU for anchor 1. FIG. 4A shows an axial view of
anchor 1 in various positions within the anterior and lateral AF.
FIG. 4B similarly shows a sagittal view of the various acceptable
anchoring sites for anchor 1. Anchor 1 is secured in the superior
vertebral body 50, inferior vertebral body 50' or anterior AF 10,
although any site that can withstand the tension between anchor 1
and support member 2 along connection member 3 to support a
herniated segment within its pre-herniated borders 40 is
acceptable.
[0152] Generally, a suitable position for affixing one or more
anchors is a location anterior to the herniated segment such that,
when tension is applied along connection member 3, herniated
segment 30 is returned to a site within the pre-herniated borders
40. The site chosen for the anchor should be able to withstand the
tensile forces applied to the anchor when the connection member is
brought under tension. Because most symptomatic herniations occur
in the posterior or posterior lateral directions, the preferable
site for anchor placement is anterior to the site of the
herniation. Any portion of the involved FSU is generally
acceptable, however the anterior, anterior medial, or anterior
lateral AF is preferable. These portions of the AF have been shown
to have considerably greater strength and stiffness than the
posterior or posterior lateral portions of the AF. As shown in
FIGS. 4A and 4B, anchor 1 can be a single anchor in any of the
shown locations, or there can be multiple anchors 1 affixed in
various locations and connected to a support member 2 to support
the herniated segment. Connection member 3 can be one continuous
length that is threaded through the sited anchors and the support
member, or it can be several individual strands of material each
terminated under tension between one or more anchors and one or
more support members.
[0153] In various forms of the invention, the anchor(s) and
connection member(s) may be introduced and implanted in the
patient, with the connection member under tension. Alternatively,
those elements may be installed, without introducing tension to the
connection member, but where the connection member is adapted to be
under tension when the patient is in a non-horizontal position,
e.g., resulting from loading in the intervertebral disc.
[0154] FIGS. 5A-C show an alternate embodiment of herniation
constraining device 13A. In this series of figures, device 13A, a
substantially one-piece construct, is delivered through a delivery
tube 6, although device 13A could be delivered in a variety of ways
including, but not limited to, by hand or by a hand held grasping
instrument. In FIG. 5A, device 13A in delivery tube 6 is positioned
against herniated segment 30. In FIG. 5B, the herniated segment is
displaced within its pre-herniated borders 40 by device 13A and/or
delivery tube 6 such that when, in FIG. 5C, device 13A has been
delivered through delivery tube 6, and secured within a portion of
the FSU, the device supports the displaced herniated segment within
its pre-herniated border 40. Herniation constraining device 13A can
be made of a variety of materials and have one of many possible
forms so long as it allows support of the herniated segment 30
within the pre-herniated borders 40 of the disc. Device 13A can
anchor the herniated segment 30 to any suitable anchoring site
within the F SU, including, but not limited to the superior
vertebral body, inferior vertebral body, or anterior AF. Device 13A
may be used additionally to close a defect in the AF of herniated
segment 30. Alternatively, any such defect may be left open or may
be closed using another means.
[0155] FIG. 6 depicts the substantially one-piece device 13A
supporting a weakened segment 30' of the posterior AF 10'. Device
13A is positioned in or posterior to the weakened segment 30' and
secured to a portion of the FSU, such as the superior vertebral
body 50, shown in the figure, or the inferior vertebral body 50' or
anterior or anterior-lateral anulus fibrosis 10. In certain
patients, there may be no obvious herniation found at surgery.
However, a weakened or torn AF that may not be protruding beyond
the pre-herniated borders of the disc may still induce the surgeon
to remove all or part of the NP in order to decrease the risk of
herniation. As an alternative to discectomy, any of the embodiments
of the invention may be used to support and perhaps close defects
in weakened segments of AF.
[0156] A further embodiment of the present invention involves
augmentation of the soft tissues of the intervertebral disc to
avoid or reverse disc height loss. FIGS. 7A and 7B show one
embodiment of device 13 securing augmentation material in the
intervertebral disc space 55. In the left side of FIG. 7A, anchors
1 have been established in the anterior AF 10. Augmentation
material 7 is in the process of being inserted into the disc space
along connection member 3 which, in this embodiment, has passageway
9. Support member 2' is shown ready to be attached to connection
member 3 once the augmentation material 7 is properly situated. In
this embodiment, connection member 3 passes through an aperture 11
in support member 2', although many other methods of affixing
support member 2' to connection member 3 are possible and within
the scope of this invention.
[0157] Augmentation material 7 may have a passageway 9, such as a
channel, slit or the like, which allows it to slide along the
connection member 3, or augmentation material 7 may be solid, and
connection member 3 can be threaded through augmentation material
by means such as needle or other puncturing device. Connection
member 3 is affixed at one end to anchor 1 and terminated at its
other end by a support member 2', one embodiment of which is shown
in the figure in a cap-like configuration. Support member 2' can be
affixed to connection member 3 in a variety of ways, including, but
not limited to, swaging support member 2' to connection member 3.
In a preferred embodiment, support member 2' is in a cap
configuration and has a dimension (diameter or length and width)
larger than the optional passageway 9, which serves to prevent
augmentation material 7 from displacing posteriorly with respect to
anchor 1. The right half of the intervertebral disc of FIG. 7A
(axial view) and FIG. 7B (sagittal view) show augmentation material
7 that has been implanted into the disc space 55 along connection
member 3 where it supports the vertebral bodies 50 and 50'. FIG. 7A
shows an embodiment in which support member 2' is affixed to
connection member 3 and serves only to prevent augmentation
material 7 from moving off connection member 3. The augmentation
device is free to move within the disc space. FIG. 7B shows an
alternate embodiment in which support member 2' is embedded in a
site in the functional spine unit, such as a herniated segment or
posterior anulus fibrosis, to further restrict the movement of
augmentation material 7 or spacer material within the disc
space.
[0158] Augmentation or spacer material can be made of any
biocompatible, preferably flexible, material. Such a flexible
material is preferably fibrous, like cellulose or bovine or
autologous collagen. The augmentation material can be plug or disc
shaped. It can further be cube-like, ellipsoid, spheroid or any
other suitable shape. The augmentation material can be secured
within the intervertebral space by a variety of methods, such as
but not limited to, a suture loop attached to, around, or through
the material, which is then passed to the anchor and support
member.
[0159] FIGS. 8, 9A, 9B and 10A and 10B depict further embodiments
of the disc herniation constraining device 13B in use for
augmenting soft tissue, particularly tissue within the
intervertebral space. In the embodiments shown in FIGS. 8 and 9A,
device 13B is secured within the intervertebral disc space
providing additional support for NP 20. Anchor 1 is securely
affixed in a portion of the FSU, (anterior AF 10 in these figures).
Connection member 3 terminates at support member 2, preventing
augmentation material 7 from migrating generally posteriorly with
respect to anchor 1. Support member 2 is depicted in these figures
as established in various locations, such as the posterior AF 10'
in FIG. 8, but support member 2 may be anchored in any suitable
location within the FSU, as described previously. Support member 2
may be used to close a defect in the posterior AF. It may also be
used to displace a herniated segment to within the pre-herniated
borders of the disc by applying tension between anchoring means 1
and 2 along connection member 3.
[0160] FIG. 9A depicts anchor 1, connection member 3, spacer
material 7 and support member 2' (shown in the "cap"-type
configuration) inserted as a single construct and anchored to a
site within the disc space, such as the inferior or superior
vertebral bodies. This configuration simplifies insertion of the
embodiments depicted in FIGS. 7 and 8 by reducing the number of
steps to achieve implantation. Connection member 3 is preferably
relatively stiff in tension, but flexible against all other loads.
Support member 2' is depicted as a bar element that is larger than
passageway 9 in at least one plane.
[0161] FIG. 9B depicts a variation on the embodiment depicted in
FIG. 9A. FIG. 9B shows substantially one-piece disc augmentation
device 13C, secured in the intervertebral disc space. Device 13C
has anchor 1, connection member 3 and augmentation material 7.
Augmentation material 7 and anchor 1 could be pre-assembled prior
to insertion into the disc space 55 as a single construct.
Alternatively, augmentation material 7 could be inserted first into
the disc space and then anchored to a portion of the FSU by anchor
1.
[0162] FIGS. 10A and 10B show yet another embodiment of the
disclosed invention, 13D. In FIG. 10A, two connection members 3 and
3' are attached to anchor 1. Two plugs of augmentation material 7
and 7' are inserted into the disc space along connection members 3
and 3'. Connection members 3 and 3' are then bound together (e.g.,
knotted together, fused, or the like). This forms loop 3'' that
serves to prevent augmentation materials 7 and 7' from displacing
posteriorly. FIG. 10B shows the position of the augmentation
material 7 after it is secured by the loop 3'' and anchor 1.
Various combinations of augmentation material, connecting members
and anchors can be used in this embodiment, such as using a single
plug of augmentation material, or two connection members leading
from anchor 1 with each of the connection members being bound to at
least one other connection member. It could further be accomplished
with more than one anchor with at least one connection member
leading from each anchor, and each of the connection members being
bound to at least one other connection member.
[0163] Any of the devices described herein can be used for closing
defects in the AF whether created surgically or during the
herniation event. Such methods may also involve the addition of
biocompatible material to either the AF or NP. This material could
include sequestered or extruded segments of the NP found outside
the pre-herniated borders of the disc.
[0164] FIGS. 11-15 illustrate devices used in and methods for
closing a defect in an anulus fibrosis. One method involves the
insertion of a barrier or barrier means 12 into the disc 15. This
procedure can accompany surgical discectomy. It can also be done
without the removal of any portion of the disc 15 and further in
combination with the insertion of an augmentation material or
device into the disc 15.
[0165] The method consists of inserting the barrier 12 into the
interior of the disc 15 and positioning it proximate to the
interior aspect of the anulus defect 16. The barrier material is
preferably considerably larger in area than the size of the defect
16, such that at least some portion of the barrier means 12 abuts
healthier anulus fibrosis 10. The device acts to seal the anulus
defect 16, recreating the closed isobaric environment of a healthy
disc nucleus 20. This closure can be achieved simply by an
over-sizing of the implant relative to the defect 16. It can also
be achieved by affixing the barrier means 12 to tissues within the
functional spinal unit. In one embodiment of the present invention,
the barrier 12 is affixed to the anulus surrounding the anulus
defect 16. This can be achieved with sutures, staples, glues or
other suitable fixation means or fixation device 14. The barrier
means 12 can also be larger in area than the defect 16 and be
affixed to a tissue or structure opposite the defect 16, e.g.,
anterior tissue in the case of a posterior defect.
[0166] The barrier means 12 is preferably flexible in nature. It
can be constructed of a woven material such as Dacron.TM. or
Nylon.TM., a synthetic polyamide or polyester, a polyethylene, and
can further be an expanded material, such as expanded
polytetrafluroethylene (e-PTFE), for example. The barrier means 12
can also be a biologic material such as cross-linked collagen or
cellulous.
[0167] The barrier means 12 can be a single piece of material. It
can have an expandable means or component that allows it to be
expanded from a compressed state after insertion into the interior
of the disc 15. This expandable means can be active, such as a
balloon, or passive, such as a hydrophilic material. The expandable
means can also be a self-expanding elastically deforming material,
for example.
[0168] FIGS. 11 and 12 illustrate a barrier 12 mounted within an
anulus 10 and covering an anulus defect 16. The barrier 12 can be
secured to the anulus 10 with a fixation mechanism or fixation
means 14. The fixation means 14 can include a plurality of suture
loops placed through the barrier 12 and the anulus 10. Such
fixation can prevent motion or slipping of the barrier 12 away from
the anulus defect 16.
[0169] The barrier means 12 can also be anchored to the disc 15 in
multiple locations. In one preferred embodiment, shown in FIGS. 13
and 14, the barrier means 12 can be affixed to the anulus tissue 10
in or surrounding the defect and further affixed to a secondary
fixation site opposite the defect, e.g. the anterior anulus 10 in a
posterior herniation, or the inferior 50' or superior 50 vertebral
body. For example, fixation means 14 can be used to attach the
barrier 12 to the anulus 10 near the defect 16, while an anchoring
mechanism 18 can secure the barrier 12 to a secondary fixation
site. A connector 22 can attach the barrier 12 to the anchor 18.
Tension can be applied between the primary and secondary fixation
sites through a connector 22 so as to move the anulus defect 16
toward the secondary fixation site. This may be particularly
beneficial in closing defects 16 that result in posterior
herniations. By using this technique, the herniation can be moved
and supported away from any posterior neural structures while
further closing any defect in the anulus 10.
[0170] The barrier means 12 can further be integral to a fixation
means such that the barrier means affixes itself to tissues within
the functional spinal unit.
[0171] Any of the methods described above can be augmented by the
use of a second barrier or a second barrier means 24 placed
proximate to the outer aspect of the defect 16 as shown in FIG. 15.
The second barrier 24 can further be affixed to the inner barrier
means 12 by the use of a fixation means 14 such as suture
material.
[0172] FIGS. 16A and 16B depict intervertebral disc 15 comprising
nucleus pulposus 20 and anulus fibrosis 10. Nucleus pulposus 20
forms a first anatomic region and extra-discal space 500 (any space
exterior to the disc) forms a second anatomic region wherein these
regions are separated by anulus fibrosis 10.
[0173] FIG. 16A is an axial (transverse) view of the intervertebral
disc. A posterior lateral defect 16 in anulus fibrosis 10 has
allowed a segment 30 of nucleus pulposus 20 to herniate into an
extra discal space 500. Interior aspect 32 and exterior aspect 34
are shown, as are the right 70' and left 70 transverse processes
and posterior process 80.
[0174] FIG. 16B is a sagittal section along the midline
intervertebral disc. Superior pedicle 90 and inferior pedicle 90'
extend posteriorly from superior vertebral body 95 and inferior
vertebral body 95' respectively.
[0175] To prevent further herniation of the nucleus 20 and to
repair any present herniation, in a preferred embodiment, a barrier
or barrier means 12 can be placed into a space between the anulus
10 and the nucleus 20 proximate to the inner aspect 32 of defect
16, as depicted in FIGS. 17 and 18. The space can be created by
blunt dissection. Dissection can be achieved with a separate
dissection instrument, with the barrier means 12 itself, or a
combined dissection/barrier delivery tool 100. This space is
preferably no larger than the barrier means such that the barrier
means 12 can be in contact with both anulus 10 and nucleus 20. This
allows the barrier means 12 to transfer load from the nucleus 20 to
the anulus 10 when the disc is pressurized during activity.
[0176] In position, the barrier means 12 preferably spans the
defect 16 and extends along the interior aspect 36 of the anulus 10
until it contacts healthy tissues on all sides of the defect 16, or
on a sufficient extent of adjacent healthy tissue to provide
adequate support under load. Healthy tissue may be non-diseased
tissue and/or load bearing tissue, which may be micro-perforated or
non-perforated. Depending on the extent of the defect 16, the
contacted tissues can include the anulus 10, cartilage overlying
the vertebral endplates, and/or the endplates themselves.
[0177] In the preferred embodiment, the barrier means 12 comprises
two components--a sealing means or sealing component 51 and an
enlarging means or enlarging component 53, shown in FIGS. 21A and
21B.
[0178] The sealing means 51 forms the periphery of the barrier 12
and has an interior cavity 17. There is at least one opening 8
leading into cavity 17 from the exterior of the sealing means 51.
Sealing means 51 is preferably compressible or collapsible to a
dimension that can readily be inserted into the disc 15 through a
relatively small hole. This hole can be the defect 16 itself or a
site remote from the defect 16. The sealing means 51 is constructed
from a material and is formed in such a manner as to resist the
passage of fluids and other materials around sealing means 51 and
through the defect 16. The sealing means 51 can be constructed from
one or any number of a variety of materials including, but not
limited to PTFE, e-PTFE, Nylon.TM., Marlex.TM., high-density
polyethylene, and/or collagen. The thickness of the sealing
component has been found to be optimal between about 0.001 inches
(0.127 mm) and 0.063 inches (1.6 mm).
[0179] The enlarging means 53 can be sized to fit within cavity 17
of sealing means 51. It is preferably a single object of a
dimension that can be inserted through the same defect 16 through
which the sealing means 51 was passed. The enlarging means 53 can
expand the sealing means 51 to an expanded state as it is passed
into cavity 17. One purpose of enlarging means 53 is to expand
sealing means 51 to a size greater than that of the defect 16 such
that the assembled barrier 12 prevents passage of material through
the defect 16. The enlarger 53 can further impart stiffness to the
barrier 12 such that the barrier 12 resists the pressures within
nucleus pulposus 20 and expulsion through the defect 16. The
enlarging means 53 can be constructed from one or any number of
materials including, but not limited to, silicon rubber, various
plastics, stainless steel, nickel titanium alloys, or other metals.
These materials may form a solid object, a hollow object, coiled
springs or other suitable forms capable of filling cavity 17 within
sealing means 51.
[0180] The sealing means 51, enlarging means 53, or the barrier
means 12 constructs can further be affixed to tissues either
surrounding the defect 16 or remote from the defect 16. In the
preferred embodiment, no aspect of a fixation means or fixation
device or the barrier means 12 nor its components extend posterior
to the disc 15 or into the extradiscal region 500, avoiding the
risk of contacting and irritating the sensitive nerve tissues
posterior to the disc 15.
[0181] In a preferred embodiment, the sealing means 51 is inserted
into the disc 15 proximate the interior aspect 36 of the defect.
The sealing means 51 is then affixed to the tissues surrounding the
defect using a suitable fixation means, such as suture or a
soft-tissue anchor. The fixation procedure is preferably performed
from the interior of the sealing means cavity 17 as depicted in
FIGS. 19 and 20. A fixation delivery instrument 110 is delivered
into cavity 17 through opening 8 in the sealing means 51. Fixation
devices 14 can then be deployed through a wall of the sealing means
53 into surrounding tissues. Once the fixation means 14 have been
passed into surrounding tissue, the fixation delivery instrument
110 can be removed from the disc 15. This method eliminates the
need for a separate entryway into the disc 15 for delivery of
fixation means 14. It further minimizes the risk of material
leaking through sealing means 51 proximate to the fixation means
14. One or more fixation means 14 can be delivered into one or any
number of surrounding tissues including the superior 95 and
inferior 95' vertebral bodies. Following fixation of the sealing
means 51, the enlarging means 53 can be inserted into cavity 17 of
the sealing means 51 to further expand the barrier means 12
construct as well as increase its stiffness, as depicted in FIGS.
21A and 21B. The opening 8 into the sealing means 51 can then be
closed by a suture or other means, although this is not a
requirement of the present invention. In certain cases, insertion
of a separate enlarging means may not be necessary if adequate
fixation of the sealing means 51 is achieved.
[0182] Another method of securing the barrier 12 to tissues is to
affix the enlarging means 53 to tissues either surrounding or
remote from the defect 16. The enlarging means 53 can have an
integral fixation region 4 that facilitates securing it to tissues
as depicted in FIGS. 22A, 22B, 32A and 43B. This fixation region 4
can extend exterior to sealing means 51 either through opening 8 or
through a separate opening. Fixation region 4 can have a hole
through which a fixation means or fixation device 14 can be passed.
In a preferred embodiment, the barrier 12 is affixed to at least
one of the surrounding vertebral bodies (95 and 95') proximate to
the defect using a bone anchor 14'. The bone anchor 14' can be
deployed into the vertebral bodies 50, 50' at some angle between
0.degree. and 180.degree. relative to a bone anchor deployment
tool. As shown the bone anchor 14' is mounted at 90.degree.
relative to the bone anchor deployment tool. Alternatively, the
enlarging means 53 itself can have an integral fixation device 14
located at a site or sites along its length.
[0183] Another method of securing the barrier means 12 is to insert
the barrier means 12 through the defect 16 or another opening into
the disc 15, position it proximate to the interior aspect 36 of the
defect 16, and pass at least one fixation means 14 through the
anulus 10 and into the barrier 12. In a preferred embodiment of
this method, the fixation means 14 can be darts 15 and are first
passed partially into anulus 10 within a fixation device 120, such
as a hollow needle. As depicted in FIGS. 23A and 23B, fixation
means 25 can be advanced into the barrier means 12 and fixation
device 120 removed. Fixation means 25 preferably have two ends,
each with a means to prevent movement of that end of the fixation
device. Using this method, the fixation means can be lodged in both
the barrier 12 and anulus fibrosis 10 without any aspect of
fixation means 25 exterior to the disc in the extradiscal region
500.
[0184] In several embodiments of the present invention, the barrier
(or "patch") 12 can be placed between two neighboring layers 33, 37
(lamellae) of the anulus 10 on either or both sides of the defect
16 as depicted in FIGS. 24A and 24B. FIG. 24A shows an axial view
while 24B shows a sagittal cross section. Such positioning spans
the defect 16. The barrier means 12 can be secured using the
methods outlined.
[0185] A dissecting tool can be used to form an opening extending
circumferentially 31 within the anulus fibrosis such that the
barrier can be inserted into the opening. Alternatively, the
barrier itself can have a dissecting edge such that it can be
driven at least partially into the sidewalls of defect 16,
annulotomy 416, access hole 417 or opening in the anulus. This
process can make use of the naturally layered structure in the
anulus in which adjacent layers 33, 37 are defined by a
circumferentially extending boundary 35 between the layers.
[0186] Another embodiment of the barrier 12 is a patch having a
length, oriented along the circumference of the disc, which is
substantially greater than its height, which is oriented along the
distance separating the surrounding vertebral bodies. A barrier 12
having a length greater than its height is illustrated in FIG. 25.
The barrier 12 can be positioned across the defect 16 as well as
the entirety of the posterior aspect of the anulus fibrosis 10.
Such dimensions of the barrier 12 can help to prevent the barrier
12 from slipping after insertion and can aid in distributing the
pressure of the nucleus 20 evenly along the posterior aspect of the
anulus 10.
[0187] The barrier 12 can be used in conjunction with an
augmentation device 11 inserted within the anulus 10. The
augmentation device 11 can include separate augmentation devices 42
as shown in FIG. 26. The augmentation device 11 can also be a
single augmentation device 44 and can form part of the barrier 12
as barrier region 300, coiled within the anulus fibrosis 10, as
shown in FIG. 27. Either the barrier 12 or barrier region 300 can
be secured to the tissues surrounding the defect 16 by fixation
devices or darts 25, or be left unconstrained
[0188] In another embodiment of the present invention, the barrier
or patch 12 may be used as part of a method to augment the
intervertebral disc. In one aspect of this method, augmentation
material or devices are inserted into the disc through a defect
(either naturally occurring or surgically generated). Many suitable
augmentation materials and devices are discussed above and in the
prior art. As depicted in FIG. 26, the barrier means is then
inserted to aid in closing the defect and/or to aid in transferring
load from the augmentation materials/devices to healthy tissues
surrounding the defect. In another aspect of this method, the
barrier means is an integral component to an augmentation device.
As shown in FIGS. 27, 28A and 28B, the augmentation portion may
comprise a length of elastic material that can be inserted linearly
through a defect in the anulus. A region 300 of the length forms
the barrier means of some embodiments of the present invention and
can be positioned proximate to the interior aspect of the defect
once the nuclear space is adequately filled. Barrier region 300 may
then be affixed to surrounding tissues such as the AF and/or the
neighboring vertebral bodies using any of the methods and devices
described above.
[0189] FIGS. 28A and 28B illustrate axial and sagittal sections,
respectively, of an alternate configuration of an augmentation
device 38. In this embodiment, barrier region 300 extends across
the defect 16 and has fixation region 4 facilitating fixation of
the device 13 to superior vertebral body 50 with anchor 14'.
[0190] FIGS. 29A-D illustrate the deployment of a barrier 12 from
an entry site 800 remote from the defect in the anulus fibrosis 10.
FIG. 29A shows insertion instrument 130 with a distal end
positioned within the disc space occupied by nucleus pulposus 20.
FIG. 29B depicts delivery catheter 140 exiting the distal end of
insertion instrument 130 with barrier 12 on its distal end. Barrier
12 is positioned across the interior aspect of the defect 16. FIG.
29C depicts the use of an expandable barrier 12' wherein delivery
catheter 140 is used to expand the barrier 12' with balloon 150 on
its distal end. Balloon 150 may exploit heat to further adhere
barrier 12' to surrounding tissue. FIG. 29D depicts removal of
balloon 150 and delivery catheter 140 from the disc space leaving
expanded barrier means 12' positioned across defect 16.
[0191] Another method of securing the barrier means 12 is to adhere
it to surrounding tissues through the application of heat. In this
embodiment, the barrier means 12 includes a sealing means 51
comprised of a thermally adherent material that adheres to
surrounding tissues upon the application of heat. The thermally
adherent material can include thermoplastic, collagen, or a similar
material. The sealing means 51 can further comprise a separate
structural material that adds strength to the thermally adherent
material, such as a woven Nylon.TM. or Marlex.TM.. This thermally
adherent sealing means preferably has an interior cavity 17 and at
least one opening 8 leading from the exterior of the barrier means
into cavity 17. A thermal device can be attached to the insertion
instrument shown in FIGS. 29C and 29D. The insertion instrument 130
having a thermal device can be inserted into cavity 17 and used to
heat sealing means 51 and surrounding tissues. This device can be a
simple thermal element, such as a resistive heating coil, rod or
wire. It can further be a number of electrodes capable of heating
the barrier means and surrounding tissue through the application of
radio frequency (RF) energy. The thermal device can further be a
balloon 150, 150', as shown in FIG. 47, capable of both heating and
expanding the barrier means. Balloon 150, 150' can either be
inflated with a heated fluid or have electrodes located about its
surface to heat the barrier means with RF energy. Balloon 150, 150'
is deflated and removed after heating the sealing means. These
thermal methods and devices achieve the goal of adhering the
sealing means to the AF and NP and potentially other surrounding
tissues. The application of heat can further aid the procedure by
killing small nerves within the AF, by causing the defect to
shrink, or by causing cross-linking and/or shrinking of surrounding
tissues. An expander or enlarging means 53 can also be an integral
component of barrier 12 inserted within sealing means 51. After the
application of heat, a separate enlarging means 53 can be inserted
into the interior cavity of the barrier means to either enlarge the
barrier 12 or add stiffness to its structure. Such an enlarging
means is preferably similar in make-up and design to those
described above. Use of an enlarging means may not be necessary in
some cases and is not a required component of this method.
[0192] The barrier means 12 shown in FIG. 25 preferably has a
primary curvature or gentle curve along the length of the patch or
barrier 12 that allows it to conform to the inner circumference of
the AF 10. This curvature may have a single radius R as shown in
FIGS. 44A and 44B or may have multiple curvatures. The curvature
can be fabricated into the barrier 12 and/or any of its components.
For example, the sealing means can be made without an inherent
curvature while the enlarging means can have a primary curvature
along its length. Once the enlarging means is placed within the
sealing means the overall barrier means assembly takes on the
primary curvature of the enlarging means. This modularity allows
enlarging means with specific curvatures to be fabricated for
defects occurring in various regions of the anulus fibrosis.
[0193] The cross section of the barrier 12 can be any of a number
of shapes. Each embodiment exploits a sealing means 51 and an
enlarging means 53 that may further add stiffness to the overall
barrier construct. FIGS. 30A and 30B show an elongated cylindrical
embodiment with enlarging means 53 located about the long axis of
the device. FIGS. 31A and 31B depict a barrier means comprising an
enlarging means 53 with a central cavity 49. FIGS. 32A and 32B
depict a barrier means comprising a non-axisymmetric sealing means
51. In use, the longer section of sealing means 51 as seen on the
left side of this figure would extend between opposing vertebra 50
and 50'. FIGS. 33A and 33B depict a barrier means comprising a
non-axisymmetric sealing means 51 and enlarger 53. The concave
portion of the barrier means preferably faces nucleus pulposus 20
while the convex surface faces the defect 16, annulotomy 416, or
access hole 417 and the inner aspect of the anulus fibrosis 10.
This embodiment exploits pressure within the disc to compress
sealing means 51 against neighboring vertebral bodies 50 and 50' to
aid in sealing. The `C` shape as shown in FIG. 33A is the preferred
shape of the barrier wherein the convex portion of the patch rests
against the interior aspect of the AF while the concave portion
faces the NP. Used in this manner, the barrier or patch 12 serves
to partially encapsulate the nucleus puposus 20 by conforming to
the gross morphology of the inner surface of the anulus 10 and
presenting a concave or cupping surface toward the nucleus 20. To
improve the sealing ability of such a patch, the upper and lower
portions of this `C` shaped barrier means are positioned against
the vertebral endplates or overlying cartilage. As the pressure
within the nucleus increases, these portions of the patch are
pressurized toward the endplates with an equivalent pressure,
preventing the passage of materials around the barrier means.
Dissecting a matching cavity prior to or during patch placement can
facilitate use of such a `C` shaped patch.
[0194] FIGS. 34 through 41 depict various enlarging or expansion
devices 53 that can be employed to aid in expanding a sealing
element 51 within the intervertebral disc 15. Each embodiment can
be covered by, coated with, or cover the sealing element 51. The
sealing means 51 can further be woven through the expansion means
53. The sealing element 51 or membrane can be a sealer which can
prevent flow of a material from within the anulus fibrosis of the
intervertebral disc through a defect in the anulus fibrosis. The
material within the anulus can include nucleus pulposus or a
prosthetic augmentation device, such as a hydrogel.
[0195] FIGS. 34 through 38 depict alternative patterns to that
illustrated in FIG. 33A. FIG. 33A shows the expansion devices 53
within the sealing means 51. The sealing means can alternatively be
secured to one or another face (concave or convex) of the expansion
means 53. This can have advantages in reducing the overall volume
of the barrier means 12, simplifying insertion through a narrow
cannula. It can also allow the barrier means 12 to induce ingrowth
of tissue on one face and not the other. The sealing means 51 can
be formed from a material that resists ingrowth such as expanded
polytetraflouroethylene (e-PTFE). The expansion means 53 can be
constructed of a metal or polymer that encourages ingrowth. In
several embodiments, if the e-PTFE sealing means 51 is secured to
the concave face of the expansion means 53, tissue can grow into
the expansion means 53 from outside of the disc 15, helping to
secure the barrier means 12 in place and seal against egress of
materials from within the disc 15.
[0196] The expansion means 53 shown in FIG. 33A can be inserted
into the sealing means 51 once the sealing means 51 is within the
disc 15. Alternatively, the expansion means 53 and sealing means 51
can be integral components of the barrier means 12 that can be
inserted as a unit into the disc.
[0197] The patterns shown in FIGS. 34 through 38 can preferably be
formed from a relatively thin sheet of material. The material may
be a polymer, metal, or gel, however, the superelastic properties
of nickel titanium alloy (NITINOL) makes this metal particularly
advantageous in this application. Sheet thickness can generally be
in a range of about 0.1 mm to about 0.6 mm and for certain
embodiments has been found to be optimal if between about 0.003''
to about 0.015'' (0.0762 mm to 0.381 mm), for the thickness to
provide adequate expansion force to maintain contact between the
sealing means 51 and surrounding vertebral endplates. The pattern
may be Wire Electro-Discharge Machined, cut by laser, chemically
etched, or formed by other suitable means.
[0198] FIG. 34 shows an embodiment of a non-axisymmetric expander
153 having a superior edge 166 and an inferior edge 168. The
expander 153 can form a frame of barrier 12. This embodiment
comprises dissecting surfaces or ends 160, radial elements or
fingers 162 and a central strut 164. The circular shape of the
dissecting ends 160 aids in dissecting through the nucleus pulposus
20 and/or along or between an inner surface of the anulus fibrosis
10. The distance between the left-most and right-most points on the
dissecting ends is the expansion means length 170. This length 170
preferably lies along the inner perimeter of the posterior anulus
following implantation. The expander length 170 can be as short as
about 3 mm and as long as the entire interior perimeter of the
anulus fibrosis. The superior-inferior height of these dissecting
ends 160 is preferably similar to or larger than the posterior disc
height.
[0199] This embodiment employs a multitude of fingers 162 to aid in
holding a flexible sealer or membrane against the superior and
inferior vertebral endplates. The distance between the
superior-most point of the superior finger and the inferior-most
point on the inferior finger is the expansion means height 172.
This height 172 is preferably greater than the disc height at the
inner surface of the posterior anulus. The greater height 172 of
the expander 153 allows the fingers 162 to deflect along the
superior and inferior vertebral endplates, enhancing the seal of
the barrier means 12 against egress of material from within the
disc 15.
[0200] The spacing between the fingers 162 along the expander
length 170 can be tailored to provide a desired stiffness of the
expansion means 153. Greater spacing between any two neighboring
fingers 162 can further be employed to insure that the fingers 170
do not touch if the expansion means 153 is required to take a bend
along its length. The central strut 164 can connect the fingers and
dissecting ends and preferably lies along the inner surface of the
anulus 10 when seated within the disc 15. Various embodiments may
employ struts 164 of greater or lesser heights and thicknesses to
vary the stiffness of the overall expansion means 153 along its
length 170 and height 172.
[0201] FIG. 35 depicts an alternative embodiment to the expander
153 of FIG. 34. Openings or slots 174 can be included along the
central strut 164. These slots 174 promote bending of the expander
153 and fingers 162 along a central line 176 connecting the centers
of the dissecting ends 160. Such central flexibility has been found
to aid against superior or inferior migration of the barrier means
or barrier 12 when the barrier 12 has not been secured to
surrounding tissues.
[0202] FIGS. 34B and 34C depict different perspective views of a
preferred embodiment of the expander/frame 153 within an
intervertebral disc 15. Expander 53 is in its expanded condition
and lies along and/or within the posterior wall 21 and extends
around the lateral walls 23 of the anulus fibrosis 10. The superior
166 and inferior 168 facing fingers 162 of expander 153 extend
along the vertebral endplates (not shown) and/or the cartilage
overlying the endplates. The frame 153 can take on a 3-D concave
shape in this preferred position with the concavity generally
directed toward the interior of the intervertebral disc and
specifically a region occupied by the nucleus pulposus 20.
[0203] The bending stiffness of expander 153 can resist migration
of the implant from this preferred position within the disc 15. The
principle behind this stiffness-based stability is to place the
regions of expander 153 with the greatest flexibility in the
regions of the disc 153 with the greatest mobility or curvature.
These flexible regions of expander 153 are surrounded by
significantly stiffer regions. Hence, in order for the implant to
migrate, a relatively stiff region of the expander must move into a
relatively curved or mobile region of the disc.
[0204] For example, in order for expander 153 of FIG. 34B to move
around the inner circumference of anulus fibrosis 10 (e.g., from
the posterior wall 21 onto the lateral 23 and/or anterior 27 wall),
the stiff central region of expander 153 spanning the posterior
wall 21 would have to bend around the acute curves of the posterior
lateral corners of anulus 10. The stiffer this section of expander
153 is, the higher the forces necessary to force it around these
corners and the less likely it is to migrate in this direction.
This principle was also used in this embodiment to resist migration
of fingers 162 away from the vertebral endplates: The slots 174 cut
along the length of expander 153 create a central flexibility that
encourages expander 153 to bend along an axis running through these
slots as the posterior disc height increases and decreased during
flexion and extension. In order for the fingers 162 to migrate away
from the endplate, this central flexible region must move away from
the posterior anulus 21 and toward an endplate. This motion is
resisted by the greater stiffness of expander 153 in the areas
directly inferior and superior to this central flexible region.
[0205] The expander 153 is preferably covered by a membrane that
acts to further restrict the movement of materials through the
frame and toward the outer periphery of the anulus fibrosis.
[0206] FIG. 36 depicts an embodiment of the expander 153 of FIG.
33A with an enlarged central strut 164 and a plurality of slots
174. This central strut 164 can have a uniform stiffness against
superior-inferior 166 and 168 bending as shown in this embodiment.
The strut 164 can alternatively have a varying stiffness along its
height 178 to either promote or resist bending at a given location
along the inner surface of the anulus 10.
[0207] FIGS. 37A-C depict a further embodiment of the frame or
expander 153. This embodiment employs a central lattice 180
consisting of multiple, fine interconnected struts 182. Such a
lattice 180 can provide a structure that minimizes bulging of the
sealing means 51 under intradiscal pressures. The orientation and
location of these struts 182 have been designed to give the barrier
12 a bend-axis along the central area of the expander height 172.
The struts 182 support inferior 168 and superior 166 fingers 162
similar to previously described embodiments. However, these fingers
162 can have varying dimensions and stiffness along the length of
the barrier 12. Such fingers 162 can be useful for helping the
sealer 51 conform to uneven endplate geometries. FIG. 37B
illustrates the curved cross section 184 of the expander 153 of
FIG. 37A. This curve 184 can be an arc segment of a circle as
shown. Alternatively, the cross section can be an ellipsoid segment
or have a multitude of arc segments of different radii and centers.
FIG. 37C is a perspective view showing the three dimensional shape
of the expander 153 of FIGS. 37A and 37B.
[0208] The embodiment of the frame 153 as shown in FIGS. 37A-C, can
also be employed without the use of a covering membrane. The
nucleus pulposus of many patients with low back pain or disc
herniation can degenerate to a state in which the material
properties of the nucleus cause it to behave much more like a solid
than a gel. As humans age, the water content of the nucleus
declines from roughly 88% to less than 75%. As this occurs, there
is an increase in the cross linking of collagen within the disc
resulting in a greater solidity of the nucleus. When the pore size
or the largest open area of any given gap in the lattice depicted
in FIGS. 37A-37C is between about 0.05 mm.sup.2
(7.75.times.10.sup.-5 in.sup.2) and about 0.75 mm.sup.2
(1.16.times.10.sup.-3 in.sup.2), the nucleus pulposus is unable to
extrude through the lattice at pressures generated within the disc
(between about 250 KPa and about 1.8 MPa). The preferred pore size
has been found to be approximately 0.15 mm.sup.2
(2.33.times.10.sup.-4 in.sup.2). This pore size can be used with
any of the disclosed embodiments of the expander or any other
expander that falls within the scope of embodiments of the
invention to prevent movement of nucleus toward the outer periphery
of the disc without the need for an additional membrane. The
membrane thickness is preferably in a range of about 0.025 mm to
about 2.5 mm.
[0209] FIG. 38 depicts an expander 153 similar to that of FIG. 37A
without fingers. The expander 153 includes a central lattice 180
consisting of multiple struts 182.
[0210] FIGS. 39 through 41 depict another embodiment of the
expander 153 of some embodiments of the present invention. These
tubular expanders can be used in the barrier 12 embodiment depicted
in FIG. 31A. The sealer 51 can cover the expander 153 as shown in
FIG. 31A. Alternatively, the sealer 51 can cover the interior
surface of the expander or an arc segment of the tube along its
length on either the interior or exterior surface.
[0211] FIG. 39 depicts an embodiment of a tubular expander 154. The
superior 166 and inferior surfaces 168 of the tubular expander 154
can deploy against the superior and inferior vertebral endplates,
respectively. The distance 186 between the superior 166 and
inferior 168 surfaces of the expander 154 are preferably equal to
or greater than the posterior disc height at the inner surface of
the anulus 10. This embodiment has an anulus face 188 and nucleus
face 190 as shown in FIGS. 39B, 39C and 39D. The anulus face 188
can be covered by the sealer 51 from the superior 166 to inferior
168 surface of the expander 154. This face 188 lies against the
inner surface of the anulus 10 in its deployed position and can
prevent egress of materials from within the disc 15. The primary
purpose of the nucleus face 190 is to prevent migration of the
expander 154 within the disc 15. The struts 192 that form the
nucleus face 190 can project anteriorly into the nucleus 20 when
the barrier 12 is positioned across the posterior wall of the
anulus 10. This anterior projection can resist rotation of the
tubular expansion means 154 about its long axis. By interacting
with the nucleus 20, the struts 192 can further prevent migration
around the circumference of the disc 15.
[0212] The struts 192 can be spaced to provide nuclear gaps 194.
These gaps 194 can encourage the flow of nucleus pulposus 20 into
the interior of the expander 154. This flow can insure full
expansion of the barrier 12 within the disc 15 during
deployment.
[0213] The embodiments of FIGS. 39, 40 and 41 vary by their
cross-sectional shape. FIG. 39 has a circular cross section 196 as
seen in FIG. 39C. If the superior-inferior height 186 of the
expander 154 is greater than that of the disc 15, this circular
cross section 196 can deform into an oval when deployed, as the
endplates of the vertebrae compress the expander 154. The
embodiment of the expander 154 shown in FIG. 40 is preformed into
an oval shape 198 shown in FIG. 40C. Compression by the endplates
can exaggerate the unstrained oval 198. This oval 198 can provide
greater stability against rotation about a long axis of the
expander 154. The embodiment of FIGS. 41B, 41C and 41D depict an
`egg-shaped` cross section 202, as shown in FIG. 41C, that can
allow congruity between the curvature of the expander 154 and the
inner wall of posterior anulus 10. Any of a variety of alternate
cross sectional shapes can be employed to obtain a desired fit or
expansion force without deviating from the spirit of the present
invention.
[0214] FIGS. 40E, 40F, and 401 depict the expander 154 of FIGS.
40A-D having a sealing means 51 covering the exterior surface of
the anulus face 188. This sealing means 51 can be held against the
endplates and the inner surface of the posterior anulus by the
expander 154 in its deployed state.
[0215] FIGS. 40G and 40H depict the expander 154 of FIG. 40B with a
sealer 51 covering the interior surface of the anulus face 188.
This position of the sealer 51 can allow the expander 154 to
contact both the vertebral endplates and inner surface of the
posterior anulus. This can promote ingrowth of tissue into the
expander 154 from outside the disc 15. Combinations of sealer 51
that cover all or part of the expander 154 can also be employed
without deviating from the scope of the present invention. The
expander 154 can also have a small pore size thereby allowing
retention of a material such as a nucleus pulposus, for example,
without the need for a sealer as a covering.
[0216] FIGS. 42A-D depict cross sections of a preferred embodiment
of sealing means 51 and enlarging means 53. Sealing means 51 has
internal cavity 17 and opening 8 leading from its outer surface
into internal cavity 17. Enlarger 53 can be inserted through
opening 8 and into internal cavity 17.
[0217] FIGS. 43A and 43B depict an alternative configuration of
enlarger 53. Fixation region 4 extends through opening 8 in sealing
means 51. Fixation region 4 has a through-hole that can facilitate
fixation of enlarger 53 to tissues surrounding defect 16.
[0218] FIGS. 44A and 44B depict an alternative shape of the
barrier. In this embodiment, sealing means 51, enlarger 53, or both
have a curvature with radius R. This curvature can be used in any
embodiment of the present invention and may aid in conforming to
the curved inner circumference of anulus fibrosis 10.
[0219] FIG. 45 is a section of a device used to affix sealing means
51 to tissues surrounding a defect. In this figure, sealing means
51 would be positioned across interior aspect 50 of defect 16. The
distal end of device 110' would be inserted through defect 16 and
opening 8 into the interior cavity 17. On the right side of this
figure, fixation dart 25 has been passed from device 110', through
a wall of sealing means 51 and into tissues surrounding sealing
means 51. On the right side of the figure, fixation dart 25 is
about to be passed through a wall of sealing means 51 by advancing
pusher 111 relative to device 110' in the direction of the
arrow.
[0220] FIG. 46 depicts the use of thermal device 200 to heat
sealing means 51 and adhere it to tissues surrounding a defect. In
this figure, sealing means 51 would be positioned across the
interior aspect 36 of a defect 16. The distal end of thermal device
200 would be inserted through the defect and opening 8 into
interior cavity 17. In this embodiment, thermal device 200 employs
at its distal end resistive heating element 210 connected to a
voltage source by wires 220. Covering 230 is a non-stick surface
such as Teflon tubing that ensures the ability to remove device 200
from interior cavity 17. In this embodiment, device 200 would be
used to heat first one half, and then the other half of sealing
means 51.
[0221] FIG. 47 depicts an expandable thermal element, such as a
balloon, that can be used to adhere sealing means 51 to tissues
surrounding a defect. As in FIG. 18, the distal end of device 130
can be inserted through the defect and opening 8 into interior
cavity 17, with balloon 150' on the distal end device 130 in a
collapsed state. Balloon 150' is then inflated to expanded state
150, expanding sealing means 51. Expanded balloon 150 can heat
sealing means 51 and surrounding tissues by inflating it with a
heated fluid or by employing RF electrodes. In this embodiment,
device 130 can be used to expand and heat first one half, then the
other half of sealing means 51.
[0222] FIG. 48 depicts an alternative embodiment to device 130.
This device employs an elongated, flexible balloon 150' that can be
inserted into and completely fill internal cavity 17 of sealing
means 51 prior to inflation to an expanded state 150. Using this
embodiment, inflation and heating of sealing means 51 can be
performed in one step.
[0223] FIGS. 49A through 49G illustrate a method of implanting an
intradiscal implant. An intradiscal implant system consists of an
intradiscal implant 400, a delivery device or cannula 402, an
advancer 404 and at least one control filament 406. The intradiscal
implant 400 is loaded into the delivery cannula 402 which has a
proximal end 408 and a distal end 410. FIG. 49A illustrates the
distal end 410 advanced into the disc 15 through an annulotomy 416.
This annulotomy 416 can be through any portion of the anulus 10,
but is preferably at a site proximate to a desired, final implant
location. The implant 400 is then pushed into the disc 15 through
the distal end 410 of the cannula 402 in a direction that is
generally away from the desired, final implant location as shown in
FIG. 49B. Once the implant 400 is completely outside of the
delivery cannula 402 and within the disc 15, the implant 400 can be
pulled into the desired implant location by pulling on the control
filament 406 as shown in FIG. 49C. The control filament 406 can be
secured to the implant 400 at any location on or within the implant
400, but is preferably secured at least at a site 414 or sites on a
distal portion 412 of the implant 400, e.g., that portion that
first exits the delivery cannula 402 when advanced into the disc
15. These site or sites 414 are generally furthest from the
desired, final implant location once the implant has been fully
expelled from the interior of the delivery cannula 402.
[0224] Pulling on the control filament 406 causes the implant 400
to move toward the annulotomy 416. The distal end 410 of the
delivery cannula 402 can be used to direct the proximal end 420 of
the implant 400 (that portion of the implant 400 that is last to be
expelled from the delivery cannula 402) away from the annulotomy
416 and toward an inner aspect of the anulus 10 nearest the desired
implant location. Alternately, the advancer 404 can be used to
position the proximal end of the implant toward an inner aspect of
the anulus 20 near the implant location, as shown in FIG. 49E.
Further pulling on the control filament 406 causes the proximal end
426 of the implant 400 to dissect along the inner aspect of the
anulus 20 until the attachment site 414 or sites of the guide
filament 406 to the implant 400 has been pulled to the inner aspect
of the annulotomy 416, as shown in FIG. 49D. In this way, the
implant 400 will extend at least from the annulotomy 416 and along
the inner aspect of the anulus 10 in the desired implant location,
illustrated in FIG. 49F.
[0225] The implant 400 can be any one of the following (including a
combination of two or more of the following): nucleus replacement
device, nucleus augmentation device, anulus augmentation device,
anulus replacement device, the barrier of the present invention or
any of its components, drug carrier device, carrier device seeded
with living cells, or a device that stimulates or supports fusion
of the surrounding vertebra. The implant 400 can be a membrane
which prevents the flow of a material from within the anulus
fibrosis of an intervertebral disc through a defect in the disc.
The material within the anulus fibrosis can be, for example, a
nucleus pulposus or a prosthetic augmentation device, such as
hydrogel. The membrane can be a sealer. The implant 400 can be
wholly or partially rigid or wholly or partially flexible. It can
have a solid portion or portions that contain a fluid material. It
can comprise a single or multitude of materials. These materials
can include metals, polymers, gels and can be in solid or woven
form. The implant 400 can either resist or promote tissue ingrowth,
whether fibrous or bony.
[0226] The cannula 402 can be any tubular device capable of
advancing the implant 400 at least partially through the anulus 10.
It can be made of any suitable biocompatible material including
various known metals and polymers. It can be wholly or partially
rigid or flexible. It can be circular, oval, polygonal, or
irregular in cross section. It must have an opening at least at its
distal end 410, but can have other openings in various locations
along its length.
[0227] The advancer 404 can be rigid or flexible, and have one of a
variety of cross sectional shapes either like or unlike the
delivery cannula 402. It may be a solid or even a column of
incompressible fluid, so long as it is stiff enough to advance the
implant 400 into the disc 15. The advancer 404 can be contained
entirely within the cannula 402 or can extend through a wall or end
of the cannula to facilitate manipulation.
[0228] Advancement of the implant 400 can be assisted by various
levers, gears, screws and other secondary assist devices to
minimize the force required by the surgeon to advance the implant
400. These secondary devices can further give the user greater
control over the rate and extent of advancement into the disc
15.
[0229] The guide filament 406 may be a string, rod, plate, or other
elongate object that can be secured to and move with the implant
400 as it is advanced into the disc 15. It can be constructed from
any of a variety of metals or polymers or combination thereof and
can be flexible or rigid along all or part of its length. It can be
secured to a secondary object 418 or device at its end opposite
that which is secured to the implant 400. This secondary device 418
can include the advancer 404 or other object or device that assists
the user in manipulating the filament. The filament 406 can be
releasably secured to the implant 400, as shown in FIG. 49G or
permanently affixed. The filament 406 can be looped around or
through the implant. Such a loop can either be cut or have one end
pulled until the other end of the loop releases the implant 400. It
may be bonded to the implant 400 using adhesive, welding, or a
secondary securing means such as a screw, staple, dart, etc. The
filament 406 can further be an elongate extension of the implant
material itself. If not removed following placement of the implant,
the filament 406 can be used to secure the implant 400 to
surrounding tissues such as the neighboring anulus 10, vertebral
endplates, or vertebral bodies either directly or through the use
of a dart, screw, staple, or other suitable anchor.
[0230] Multiple guide filaments can be secured to the implant 400
at various locations. In one preferred embodiment, a first or
distal 422 and a second or proximal 424 guide filament are secured
to an elongate implant 400 at or near its distal 412 and proximal
420 ends at attachment sites 426 and 428, respectively. These ends
412 and 420 correspond to the first and last portions of the
implant 400, respectively, to be expelled from the delivery cannula
402 when advanced into the disc 15. This double guide filament
system allows the implant 400 to be positioned in the same manner
described above in the single filament technique, and illustrated
in FIGS. 50A-C. However, following completion of this first
technique, the user may advance the proximal end 420 of the device
400 across the annulotomy 416 by pulling on the second guide
filament 424, shown in FIG. 50D. This allows the user to
controllably cover the annulotomy 416. This has numerous advantages
in various implantation procedures. This step may reduce the risk
of herniation of either nucleus pulposus 20 or the implant itself.
It may aid in sealing the disc, as well as preserving disc pressure
and the natural function of the disc. It may encourage ingrowth of
fibrous tissue from outside the disc into the implant. It may
further allow the distal end of the implant to rest against anulus
further from the defect created by the annulotomy. Finally, this
technique allows both ends of an elongate implant to be secured to
the disc or vertebral tissues.
[0231] Both the first 422 and second 424 guide filaments can be
simultaneously tensioned, as shown in FIG. 50E, to ensure proper
positioning of the implant 400 within the anulus 10. Once the
implant 400 is placed across the annulotomy, the first 422 and
second 424 guide filaments can be removed from the input 400, as
shown in FIG. 50F. Additional control filaments and securing sites
may further assist implantation and/or fixation of the intradiscal
implants.
[0232] In another embodiment of the present invention, as
illustrated in FIGS. 51A-C, an implant guide 430 may be employed to
aid directing the implant 400 through the annulotomy 416, through
the nucleus pulposus 10, and/or along the inner aspect of the
anulus 10. This implant guide 430 can aid in the procedure by
dissecting through tissue, adding stiffness to the implant
construct, reducing trauma to the anulus or other tissues that can
be caused by a stiff or abrasive implant, providing 3-D control of
the implants orientation during implantation, expanding an
expandable implant, or temporarily imparting a shape to the implant
that is beneficial during implantation. The implant guide 430 can
be affixed to either the advancer 404 or the implant 406
themselves. In a preferred embodiment shown in FIGS. 52A and 52B,
the implant guide 430 is secured to the implant 400 by the first
424 and second 426 guide filaments of the first 426 and the second
428 attachment sites, respectively. The guide filaments 424 and 426
may pass through or around the implant guide 430. In this
embodiment, the implant guide 430 may be a thin, flat sheet of
biocompatible metal with holes passing through its surface
proximate to the site or sites 426 and 428 at which the guide
filaments 422 and 424 are secured to the implant 400. These holes
allow passage of the securing filament 422 and 424 through the
implant guide 430. Such an elongated sheet may run along the
implant 400 and extend beyond its distal end 412. The distal end of
the implant guide 430 may be shaped to help dissect through the
nucleus 10 and deflect off of the anulus 10 as the implant 400 is
advanced into the disc 15. When used with multiple guide filaments,
such an implant guide 430 can be used to control rotational
stability of the implant 400. It may also be used to retract the
implant 400 from the disc 15 should this become necessary. The
implant guide 430 may also extend beyond the proximal tip 420 of
the implant 400 to aid in dissecting across or through the anulus
10 proximate to the desired implantation site.
[0233] The implant guide 430 is releasable from the implant 400
following or during implantation. This release may be coordinated
with the release of the guide filaments 422 and 424. The implant
guide 430 may further be able to slide along the guide filaments
422 and 424 while these filaments are secured to the implant
400.
[0234] Various embodiments of the barrier 12 or implant 400 can be
secured to tissues within the intervertebral disc 15 or surrounding
vertebrae. It can be advantageous to secure the barrier means 12 in
a limited number of sites while still insuring that larger surfaces
of the barrier 12 or implant juxtapose the tissue to which the
barrier 12 is secured. This is particularly advantageous in forming
a sealing engagement with surrounding tissues.
[0235] FIGS. 53-57 illustrate barriers 12 having stiffening
elements 300. The barrier 12 can incorporate stiffening elements
300 that run along a length of the implant required to be in
sealing engagement. These stiffening elements 300 can be one of a
variety of shapes including, but not limited to, plates 302, rods
304, or coils. These elements are preferably stiffer than the
surrounding barrier 12 and can impart their stiffness to the
surrounding barrier. These stiffening elements 300 can be located
within an interior cavity formed by the barrier. They can further
be imbedded in or secured to the barrier 12.
[0236] Each stiffening element can aid in securing segments of the
barrier 12 to surrounding tissues. The stiffening elements can have
parts 307, including through-holes, notches, or other indentations
for example, to facilitate fixation of the stiffening element 300
to surrounding tissues by any of a variety of fixation devices 306.
These fixation devices 306 can include screws, darts, dowels, or
other suitable means capable of holding the barrier 12 to
surrounding tissue. The fixation devices 306 can be connected
either directly to the stiffening element 300 or indirectly using
an intervening length of suture, cable, or other filament for
example. The fixation device 306 can further be secured to the
barrier 12 near the stiffening element 300 without direct contact
with the stiffening element 300.
[0237] The fixation device 306 can be secured to or near the
stiffening element 300 at opposing ends of the length of the
barrier 12 required to be in sealing engagement with surrounding
tissues. Alternatively, one or a multitude of fixation devices 306
can be secured to or near the stiffening element 300 at a readily
accessible location that may not be at these ends. In any barrier
12 embodiment with an interior cavity 17 and an opening 8 leading
thereto, the fixation sites may be proximal to the opening 8 to
allow passage of the fixation device 306 and various instruments
that may be required for their implantation.
[0238] FIGS. 53A and 53B illustrate one embodiment of a barrier 12
incorporating the use of a stiffening element 300. The barrier 12
can be a plate and screw barrier 320. In this embodiment, the
stiffening element 300 consists of two fixation plates, superior
310 and inferior 312, an example of which is illustrated in FIGS.
54A and 54B with two parts 308 passing through each plate. The
parts 308 are located proximal to an opening 8 leading into an
interior cavity 17 of the barrier 12. These parts 8 allow passage
of a fixation device 306 such as a bone screw. These screws can be
used to secure the barrier means 12 to a superior 50 and inferior
50' vertebra. As the screws are tightened against the vertebral
endplate, the fixation plates 310, 312 compress the intervening
sealing means against the endplate along the superior and inferior
surfaces of the barrier 12. This can aid in creating a sealing
engagement with the vertebral endplates and prevent egress of
materials from within the disc 15. As illustrated in FIGS. 53A and
53B, only the superior screws have been placed in the superior
plate 310, creating a sealing engagement with the superior
vertebra.
[0239] FIGS. 55A and 55B illustrate another embodiment of a barrier
12 having stiffening elements 300. The barrier 12 can be an anchor
and rod barrier 322. In this embodiment, the stiffening elements
300 consist of two fixation rods 304, an example of which is shown
in FIGS. 56A and 56B, imbedded within the barrier 12. The rods 304
can include a superior rod 314 and an inferior rod 316. Sutures 318
can be passed around these rods 314 and 316 and through the barrier
means 10. These sutures 318 can in turn, be secured to a bone
anchor or other suitable fixation device 306 to draw the barrier 12
into sealing engagement with the superior and inferior vertebral
endplates in a manner similar to that described above. The opening
8 and interior cavity 17 of the barrier 12 are not required
elements of the barrier 12.
[0240] FIG. 57 illustrates the anchor and rod barrier 322,
described above, with fixation devices 306 placed at opposing ends
of each fixation rod 316 and 318. The suture 18 on the left side of
the superior rod 318 has yet to be tied.
[0241] Various methods may be employed to decrease the forces
necessary to maneuver the barrier 12 into a position along or
within the lamellae of the anulus fibrosis 10. FIGS. 58A, 58B, 59A
and 59B depict two preferred methods of clearing a path for the
barrier 12.
[0242] FIGS. 58A and 58B depict one such method and an associated
dissector device 454. In these figures, the assumed desired
position of the implant is along the posterior anulus 452. In order
to clear a path for the implant, a hairpin dissector 454 can be
passed along the intended implantation site of the implant. The
hairpin dissector 454 can have a hairpin dissector component 460
having a free end 458. The dissector can also have an advancer 464
to position the dissector component 460 within the disc 15. The
dissector 454 can be inserted through cannula 456 into an opening
462 in the anulus 10 along an access path directed anteriorly or
anterior-medially. Once a free-end 458 of the dissector component
460 is within the disc 15, the free-end 458 moves slightly causing
the hairpin to open, such that the dissector component 460 resists
returning into the cannula 456. This opening 462 can be caused by
pre-forming the dissector to the opened state. The hairpin
dissector component 460 can then be pulled posteriorly, causing the
dissector component 460 to open, further driving the free-end 458
along the posterior anulus 458. This motion clears a path for the
insertion of any of the implants disclosed in the present
invention. The body of dissector component 460 is preferably formed
from an elongated sheet of metal. Suitable metals include various
spring steels or nickel titanium alloys. It can alternatively be
formed from wires or rods.
[0243] FIGS. 59A and 59B depict another method and associated
dissector device 466 suitable for clearing a path for implant
insertion. The dissector device 466 is shown in cross section and
consists of a dissector component 468, an outer cannula 470 and an
advancer or inner push rod 472. A curved passage or slot 474 is
formed into an intradiscal tip 476 of outer cannula 470. This
passage or slot 474 acts to deflect the tip of dissector component
468 in a path that is roughly parallel to the lamellae of the
anulus fibrosis 10 as the dissector component 468 is advanced into
the disc 15 by the advancer. The dissector component 468 is
preferably formed from a superelastic nickel titanium alloy, but
can be constructed of any material with suitable rigidity and
strain characteristics to allow such deflection without significant
plastic deformation. The dissector component 468 can be formed from
an elongated sheet, rods, wires or the like. It can be used to
dissect between the anulus 10 and nucleus 20, or to dissect between
layers of the anulus 10.
[0244] FIGS. 60A-C depict an alternate dissector component 480 of
FIGS. 59A and 59B. Only the intradiscal tip 476 of device 460 and
regions proximal thereto are shown in these figures. A push-rod 472
similar to that shown in FIG. 59A can be employed to advance
dissector 480 into the disc 15. Dissector 480 can include an
elongated sheet 482 with superiorly and inferiorly extending blades
(or "wings") 484 and 486, respectively. This sheet 482 is
preferably formed from a metal with a large elastic strain range
such as spring steel or nickel titanium alloy. The sheet 482 can
have a proximal end 488 and a distal end 490. The distal end 490
can have a flat portion which can be flexible. A step portion 494
can be located between the distal end 490 and the proximal end 488.
The proximal end 488 can have a curved shape. The proximal end can
also include blades 484 and 486.
[0245] In the undeployed state depicted in FIGS. 60A and 60B, wings
484 and 486 are collapsed within outer cannula 470 while elongated
sheet 482 is captured within deflecting passage or slot 474. As the
dissector component 480 is advanced into a disc 15, passage or slot
478 directs the dissector component 480 in a direction roughly
parallel to the posterior anulus (90 degrees to the central axis of
sleeve 470 in this case) in a manner similar to that described for
the embodiment in FIGS. 59A and 59B. Wings 484 and 486 open as they
exit the end of sleeve 470 and expand toward the vertebral
endplates. Further advancement of dissector component 480 allows
the expanded wings 484 and 486 to dissect through any connections
of nucleus 20 or anulus 10 to the endplates that may present an
obstruction to subsequent passage of the implants of the present
invention. When used to aid in the insertion of a barrier, the
dimensions of dissector component 480 should approximate those of
the barrier such that the minimal amount of tissue is disturbed
while reducing the forces necessary to position the barrier in the
desired location.
[0246] FIGS. 61A-61D illustrate a method of implanting a disc
implant. A disc implant 552 is inserted into a delivery device 550.
The delivery device 550 has a proximal end 556 and a distal end
558. The distal end 558 of the delivery device 550 is inserted into
an annulotomy illustrated in FIG. 61A. The annulotomy is preferably
located at a site within the anulus 10 that is proximate to a
desired, final implant 552 location. The implant 400 is then
deployed by being inserted into the disc 15 through the distal end
558 of the delivery device 550. Preferably the implant is forced
away from the final implant location, as shown in FIG. 61B. An
implant guide 560 can be used to position the implant 400. Before,
during or after deployment of the implant 400, an augmentation
material 7 can be injected into the disc 15. Injection of
augmentation after deployment is illustrated in FIG. 61C. The
augmentation material 7 can include a hydrogel or collagen, for
example. In one embodiment, the delivery device 550 is removed from
the disc 15 and a separate tube is inserted into the annulotomy to
inject the flowable augmentation material 7. Alternately, the
distal end 558 of the delivery device 550 can remain within the
annulotomy and the fluid augmentation material 554 injected through
the delivery device 550. Next, the delivery device 550 is removed
from the annulotomy and the intradiscal implant 400 is positioned
over the annulotomy in the final implant location, as shown in FIG.
61D. The implant 400 can be positioned using control filaments
described above.
[0247] Certain embodiments, as shown in FIGS. 62-66, depict anulus
and nuclear augmentation devices which are capable of working in
concert to restore the natural biomechanics of the disc. A disc
environment with a degenerated or lesioned anulus cannot generally
support the load transmission from either the native nucleus or
from prosthetic augmentation. In many cases, nuclear augmentation
materials 7 bulge through the anulus defects, extrude from the
disc, or apply pathologically high load to damaged regions of the
anulus. Accordingly, in one aspect of the current invention,
damaged areas of the anulus are protected by shunting the load from
the nucleus 20 or augmentation materials 7 to healthier portions of
the anulus 10 or endplates. With the barrier-type anulus
augmentation 12 in place, as embodied in various aspects of the
present invention, nuclear augmentation materials 7 or devices can
conform to healthy regions of the anulus 10 while the barrier 12
shields weaker regions of the anulus 10. Indeed, the anulus
augmentation devices 12 of several embodiments of the present
invention are particularly advantageous because they enable the use
of certain nuclear augmentation materials and devices 7 that may
otherwise be undesirable in a disc with an injured anulus.
[0248] FIG. 62 is a cross-sectional transverse view of an anulus
barrier device 12 implanted within a disc 15 along the inner
surface of a lamella 16. Implanted conformable nuclear augmentation
7 is also shown in contact with the barrier 12. The barrier device
12 is juxtapositioned to the innermost lamella of the anulus.
Conformable nuclear augmentation material 7 is inserted into the
cavity which is closed by the barrier 12, in an amount sufficient
to fill the disc space in an unloaded supine position. As shown, in
one embodiment, fluid nuclear augmentation 554, such as hyaluronic
acid, is used.
[0249] Fluid nuclear augmentation 554 is particularly well-suited
for use in various aspects of the current invention because it can
be delivered with minimal invasiveness and because it is able to
flow into and fill minute voids of the intervertebral disc space.
Fluid nuclear augmentation 554 is also uniquely suited for
maintaining a pressurized environment that evenly transfers the
force exerted by the endplates to the anulus augmentation device
and/or the anulus. However, fluid nuclear augmentation materials
554 used alone may perform poorly in discs 15 with a degenerated
anulus because the material can flow back out through anulus
defects 8 and pose a risk to surrounding structures. This
limitation is overcome by several embodiments of the current
invention because the barrier 12 shunts the pressure caused by the
fluid augmentation 554 away from the damaged anulus region 8 and
toward healthier regions, thus restoring function to the disc 15
and reducing risk of the extrusion of nuclear augmentation
materials 7 and fluid augmentation material 554.
[0250] Exemplary fluid nuclear augmentation materials 554 include,
but are not limited to, various pharmaceuticals (steroids,
antibiotics, tissue necrosis factor alpha or its antagonists,
analgesics); growth factors, genes or gene vectors in solution;
biologic materials (hyaluronic acid, non-crosslinked collagen,
fibrin, liquid fat or oils); synthetic polymers (polyethylene
glycol, liquid silicones, synthetic oils); and saline. One skilled
in the art will understand that any one of these materials may be
used alone or that a combination of two or more of these materials
may be used together to form the nuclear augmentation material.
[0251] Any of a variety of additional additives such as thickening
agents, carriers, polymerization initiators or inhibitors may also
be included, depending upon the desired infusion and long-term
performance characteristics. In general, "fluid" is used herein to
include any material which is sufficiently flowable at least during
the infusion process, to be infused through an infusion lumen in
the delivery device into the disc space. The augmentation material
554 may remain "fluid" after the infusion step, or may polymerize,
cure, or otherwise harden to a less flowable or nonflowable
state.
[0252] Additional additives and components of the nucleus
augmentation material are recited below. In general, the nature of
the material 554 may remain constant during the deployment and
post-deployment stages or may change, from a first infusion state
to a second, subsequent implanted state. For example, any of a
variety of materials may desirably be infused using a carrier such
as a solvent or fluid medium with a dispersion therein. The solvent
or liquid carrier may be absorbed by the body or otherwise
dissipate from the disc space post-implantation, leaving the
nucleus augmentation material 554 behind. For example, any of a
variety of the powders identified below may be carried using a
fluid carrier. In addition, hydrogels or other materials may be
implanted or deployed while in solution, with the solvent
dissipating post-deployment to leave the hydrogel or other media
behind. In this type of application, the disc space may be filled
under higher than ultimately desired pressure, taking into account
the absorption of a carrier volume. Additional specific materials
and considerations are disclosed in greater detail below.
[0253] FIG. 63 is a cross-sectional transverse view of anulus
barrier device 12 implanted within a disc 15 along an inner surface
of a lamella 16. Implanted nuclear augmentation 7 comprised of a
hydrophilic flexible solid is also shown. Nuclear augmentation
materials include, but are not limited to, liquids, gels, solids,
gases or combinations thereof. Nuclear augmentation devices 7 may
be formed from one or more materials, which are present in one or
more phases. FIG. 63 shows a cylindrical flexible solid form of
nuclear augmentation 7. Preferably, this flexible solid is composed
of a hydrogel, including, but not limited to, acrylonitrile,
acrylic acid, polyacrylimide, acrylimide, acrylimidine,
polyacrylonitrile, polyvinylalcohol, and the like.
[0254] FIG. 63 depicts nuclear augmentation 7 using a solid or gel
composition. If required, these materials can be designed to be
secured to surrounding tissues by mechanical means, such as glues,
screws, and anchors, or by biological means, such as glues and in
growth. Solid but deformable augmentation materials 7 may also be
designed to resist axial compression by the endplates rather than
flowing circumferentially outward toward the anulus. In this way,
less force is directed at the anulus 10. Solid nuclear augmentation
7 can also be sized substantially larger than the annulotomy 416 or
defect 8 to decrease the risk of extrusion. The use of solid
materials or devices 7 alone is subject to certain limitations. The
delivery of solid materials 7 may require a large access hole 417
in the anulus 10, thereby decreasing the integrity of the disc 15
and creating a significant risk for extrusion of either the
augmentation material 7 or of natural nucleus 20 remaining within
the disc 15. Solid materials or devices 7 can also overload the
endplates causing endplate subsidence or apply point loads to the
anulus 10 from corners or edges that may cause pain or further
deterioration of the anulus 10. Several embodiments of the present
invention overcome the limitations of solid materials and are
particularly well-suited for use with liquid augmentation materials
7. The barrier device 12 of various embodiments of this invention
effectively closes the access hole 417 and can be adapted to
partially encapsulate the augmented nucleus, thus mitigating the
risks posed by solid materials.
[0255] Solid or gel nuclear augmentation materials 7 used in
various embodiments of the current invention include single piece
or multiple pieces. The solid materials 7 may be cube-like,
spheroid, disc-like, ellipsoid, rhombohedral, cylindrical, or
amorphous in shape. These materials 7 may be in woven or non-woven
form. Other forms of solids including minute particles or even
powder can be considered when used in combination with the barrier
device. Candidate materials 7 include, but are not limited to:
metals, such as titanium, stainless steels, nitinol, cobalt chrome;
resorbable or non-resorbing synthetic polymers, such as
polyurethane, polyester, PEEK, PET, FEP, PTFE, ePTFE, Teflon, PMMA,
nylon, carbon fiber, Delrin, polyvinyl alcohol gels, polyglycolic
acid, polyethylene glycol; silicon gel or rubber, vulcanized rubber
or other elastomer; gas filled vesicles, biologic materials such as
morselized or block bone, hydroxy apetite, cross-linked collagen,
muscle tissue, fat, cellulose, keratin, cartilage, protein
polymers, transplanted or bioengineered nucleus pulposus or anulus
fibrosus; or various pharmacologically active agents in solid form.
The solid or gel augmentation materials 7 may be rigid, wholly or
partially flexible, elastic or viscoelastic in nature. The
augmentation device or material 7 may be hydrophilic or
hydrophobic. Hydrophilic materials, mimicking the physiology of the
nucleus, may be delivered into the disc in a hydrated or dehydrated
state. Biologic materials may be autologous, allograft, zenograft,
or bioengineered.
[0256] In various embodiments of the present invention, the solid
or gel nuclear augmentation material 7, as depicted in FIG. 63, are
impregnated or coated with various compounds. Preferably, a
biologically active compound is used. In one embodiment, one or
more drug carriers are used to impregnate or coat the nuclear
augmentation material 7. Genetic vectors, naked genes or other
therapeutic agents to renew growth, reduce pain, aid healing, and
reduce infection may be delivered in this manner. Tissue in-growth,
either fibrous (from the anulus) or bony (from the endplates),
within or around the augmentation material can be either encouraged
or discouraged depending on the augmentation used. Tissue in-growth
may be beneficial for fixation and can be encouraged via porosity
or surface chemistry. Surface in-growth or other methods of
fixation of the augmentation material 7 can be encouraged on a
single surface or aspect so as to not interfere with the normal
range of motion of the spinal unit. In this way, the material is
stabilized and safely contained within the anulus 10 without
resulting in complete fixation which might cause fusion and
prohibit disc function.
[0257] FIG. 64 is a cross-sectional transverse view of anulus
barrier device 12 implanted within a disc 15 along an inner surface
of a lamella 16. Several types of implanted nuclear augmentation 7,
including a solid cube, a composite cylindrical solid 555, and a
free flowing liquid 554 are shown. The use of multiple types of
nuclear augmentation with the barrier 12 is depicted in FIG. 64.
The barrier device 12 is shown in combination with fluid nuclear
augmentation 554, solid nuclear augmentation 7, in the form of a
cube, and a cross-linked collagen sponge composite 555 soaked in a
growth factor. In several embodiments of the present invention, a
multiphase augmentation system, as shown in FIG. 64, is used. A
combination of solids and liquids is used in a preferred
embodiment. Nuclear augmentation 7 comprising solids and liquids
554 can be designed to create primary and secondary levels of
flexibility within an intervertebral disc space. In use, the spine
will flex easily at first as the intervertebral disc pressure
increases and the liquids flows radially, loading the anulus. Then,
as the disc height decreases and the endplates begin to contact the
solid or gelatinous augmentation material, flexibility will
decrease. This combination can also prevent damage to the anulus 10
under excessive loading as the solid augmentation 7 can be designed
to resist further compression such that the fluid pressure on the
anulus is limited. In a preferred embodiment, use of multiphase
augmentation allows for the combination of fluid medications or
biologically active substances with solid or gelatinous carriers.
One example of such a preferable combination is a cross-linked
collagen sponge 555 soaked in a growth factor or combination of
growth factors in liquid suspension.
[0258] In one embodiment, the nuclear augmentation material or
device 7, 554 constructed therefrom is phase changing, e.g., from
liquid to solid, solid to liquid, or liquid to gel. In situ
polymerizing nuclear augmentation materials are well-known in the
art and are described in U.S. Pat. No. 6,187,048, herein
incorporated by reference. Phase changing augmentation preferably
changes from a liquid to a solid or gel. Such materials may change
phases in response to contact with air, increases or decreases in
temperature, contact with biologic liquids or by the mixture of
separate reactive constituents. These materials are advantageous
because they can be delivered through a small hole in the anulus or
down a tube or cannula placed percutaneously into the disc. Once
the materials have solidified or gelled, they can exhibit the
previously described advantages of a solid augmentation material.
In a preferred embodiment, the barrier device is used to seal and
pressurize a phase changing material to aid in its delivery by
forcing it into the voids of the disc space while minimizing the
risk of extrusion of the material while it is a fluid. In this
situation, the barrier or anulus augmentation device 12 may be
permanently implanted or used only temporarily until the desired
phase change has occurred.
[0259] In another embodiment, an anulus augmentation device 12 that
exploits the characteristics of nucleus augmentation devices or
materials to improve its own performance is provided. Augmenting
the nucleus 20 pressurizes the intervertebral disc environment
which can serve to fix or stabilize an anulus repair device in
place. The nucleus 20 can be pressurized by inserting into the disc
15 an adequate amount of augmentation material 7, 554. In use, the
pressurized disc tissue and augmentation material 7, 554 applies
force on the inwardly facing surface of the anulus augmentation
device 12. This pressure may be exploited by the design of the
anulus prosthesis or barrier 12 to prevent it from dislodging or
moving from its intended position. One exemplary method is to
design the inwardly facing surface of the anulus prosthesis 12 to
expand upon the application of pressure. As the anulus prosthesis
12 expands, it becomes less likely to be expelled from the disc.
The prosthesis 12 may be formed with a concavity facing inward to
promote such expansion.
[0260] In several embodiments, the anulus augmentation device 12
itself functions as nuclear augmentation 7. In a preferred
embodiment, the barrier 12 frame is encapsulated in ePTFE. This
construct typically displaces a volume of 0.6 cubic centimeters,
although thicker coatings of ePTFE or like materials may be used to
increase this volume to 3 cubic centimeters. Also, the anulus
augmentation device may be designed with differentially thickened
regions along its area.
[0261] FIG. 65 depicts a sagittal cross-sectional view of the
barrier device connected to an inflatable nuclear augmentation
device 455. The barrier device 12 is shown connected via hollow
delivery and support tube 425 to an nuclear augmentation sack 455
suitable for containing fluid material 554. The tube 425 has a
delivery port or valve 450 that extends through the barrier device
and can be accessed from the access hole 417 after the barrier
device 12 and augmentation sack 455 has been delivered. This
nuclear and anulus augmentation combination is particularly
advantageous because of the ease of deliverability, since the sack
455 and the barrier 12 are readily compressed. The connection of
the barrier 12 and the augmentation sack 455 also serves to
stabilize the combination and prevent its extrusion from the disc
15. The nuclear augmentation 7 may be secured to the anulus
augmentation prosthesis 12 to create a resistance to migration of
the overall construct. Such attachment may also be performed to
improve or direct the transfer of load from the nuclear prosthesis
7 through the anulus prosthesis 12 to the disc tissues. The barrier
12 and augmentation 7 can be attached prior to, during, or after
delivery of the barrier 12 into the disc 15. They may be secured to
each other by an adhesive or by a flexible filament such as suture.
Alternatively, the barrier 12 may have a surface facing the
augmentation material 7 that bonds to the augmentation material 7
though a chemical reaction. This surface may additionally allow for
a mechanical linkage to a surface of the augmentation material 7.
This linkage could be achieved through a porous attachment surface
of the barrier 12 that allows the inflow of a fluid augmentation
material 7 that hardens or gels after implantation.
[0262] Alternatively, the anulus augmentation device 12 and nuclear
augmentation material 7 may be fabricated as a single device with a
barrier 12 region and a nuclear augmentation region 7. As an
example, the barrier 12 may form at least a portion of the surface
of an augmentation sack 455 or balloon. The sack 455 may be filled
with suitable augmentation materials 7 once the barrier has been
positioned along a weakened inner surface of the anulus 10.
[0263] The sequence of inserting the barrier 12 and nuclear
augmentation 7 in the disc can be varied according to the nuclear
augmentation 7 used or requirements of the surgical procedure. For
example, the nuclear augmentation 7 can be inserted first and then
sealed in place by the barrier device 12. Alternatively, the disc
15 can be partially filled, then sealed with the barrier device 12,
and then supplied with additional material 7. In a preferred
embodiment, the barrier device 12 is inserted into the disc 15
followed by the addition of nuclear augmentation material 7 through
or around the barrier 12. This allows for active pressurization. A
disc 15 with a severely degenerated anulus can also be effectively
treated in this manner.
[0264] In an alternative embodiment, the nuclear augmentation
material 7 is delivered through a cannula inserted through an
access hole 417 in the disc 15 formed pathologically, e.g. an
anular defect 8, or iatrogenically, e.g. an anuulotomy 416 that is
distinct from the access hole 417 that was used to implant the
barrier 12. Also, the same or different surgical approach including
transpsoas, presacral, transsacral, tranpedicular, translaminar, or
anteriorly through the abdomen, may be used. Access hole 417 can be
located anywhere along the anulus surface or even through the
vertebral endplates.
[0265] In alternative embodiments, the anulus augmentation device
12 includes features that facilitate the introduction of
augmentation materials 554 following placement. The augmentation
delivery cannula may simply be forcibly driven into an access hole
417 proximal to the barrier 12 at a slight angle so that the edge
of the barrier 12 deforms and allows passage into the disc space.
Alternatively, a small, flexible or rigid curved delivery needle or
tube may be inserted through an access hole 417 over (in the
direction of the superior endplate) or under (in the direction of
the inferior endplate) the barrier 12 or around an edge of the
barrier 12 contiguous with the anulus 15.
[0266] In several embodiments, ports or valves are installed in the
barrier 12 device that permit the flow of augmentation material
into, but not out of, the disc space. One-way valves 450 or even
flaps of material held shut by the intervertebral pressure may be
used. A collapsible tubular valve may be fashioned along a length
of the barrier. In one embodiment, multiple valves or ports 450 are
present along the device 12 to facilitate alignment with the access
hole 417 and delivery of augmentation material. Flow channels
within or on the barrier 12 to direct the delivery of the material
554 (e.g. to the ends of the barrier) can be machined, formed into
or attached to the barrier 12 along its length. Alternatively,
small delivery apertures (e.g. caused by a needle) can be sealed
with a small amount of adhesive or sutured shut.
[0267] FIG. 66 is sagittal cross-sectional view of a functional
spine unit containing the barrier device unit 12 connected to a
wedge-shaped nuclear augmentation 7 device. FIG. 66 illustrates
that the geometry of the nuclear augmentation 7 can be adapted to
improve the function of the barrier. By presenting nuclear
augmentation 7 with a wedge-shaped or hemicircular profile towards
the interior of the intervertebral disc space, and attaching it in
the middle of the barrier device 12 between the flexible
finger-like edges of the barrier device, the force exerted by the
pressurized environment is focused in the direction of the edges of
the barrier device sealing them against the endplates. Accordingly,
this wedge-shaped feature improves the function of the device 12.
One skilled in the art will understand that the nuclear
augmentation material 7 may also be designed with various features
that improve its interaction with the barrier, such as exhibiting
different flexibility or viscosity throughout its volume. For
example, in certain applications, it may be preferable for the
augmentation 7 to be either stiff at the interface with the barrier
12 and supple towards the center of the disc, or vice versa. The
augmentation 7 can also serve to rotationally stabilize the barrier
12. In this embodiment, the augmentation is coupled to the inward
facing surface of the barrier and extends outward and medially into
the disc forming a lever arm and appearing as "T-shaped" unit. The
augmentation device 7 of this embodiment can extend from the middle
of the disc 15 to the opposite wall of the anulus.
[0268] In one embodiment, the anulus augmentation device comprises
a mesh. FIG. 67 shows one example of a meshed anulus augmentation
device. In one embodiment, a repair mesh that is resilient is
provided. In some embodiments, the mesh is particularly
advantageous because it can withstand millions of motion cycles
within the disc environment, and is resistant to fatigue. In
several embodiments, fatigue resistance is accomplished by material
properties, structural design, or a combination thereof. For a
given material, a fatigue resistant structure can be designed to
distribute the strain of deformation as evenly as possible over as
much material as possible so as to minimize stress concentrations
that could initiate fatigue cracks. For example, a coiled spring
may deform millions of times without failure or cracking because
the strain is distributed evenly over a length of metal. For an
anulus repair mesh, the same effect maybe achieved by means such
as, but not limited to, providing more material for a given
deformation site by having mesh members curved throughout their
lengths, alternating mesh curves in a sine-wave or zigzag pattern
to provide more material and distributed strains, or having longer
non linear members such that a given deformation results in less
material strain, or pre-shaping the implant to minimize strain at
the implantation site. The curvilinear, nonlinear, coiled, or
angled members can be interconnected, woven, networked, or emanate
from or be attached to rails or members to form a framework or
define a mesh or barrier.
[0269] In one embodiment, a mesh can be used in a variety of
locations in and around the intervertebral disc. It can be placed
on an external surface of the anulus, along an endplate, within the
anulus, between the anulus and nucleus, within the nucleus, or
within both the anulus and nucleus. The mesh can be held in place
via counteracting forces of the mesh as it flexes from its
unstressed shape to stressed shape or friction with disc tissue,
between disc and vertebral body tissue or between disc augmentation
material or another implant and disc tissue. The mesh can also have
a porosity or macrotexture including ridges, spikes or spirals to
increase bioincorporation and fixation. Fixation devices, including
but not limited to, sutures, glue, screws, and staples can be used
to permanently fix the mesh in place.
[0270] In one embodiment, the anulus augmentation device is a
barrier comprising a membrane and a frame. In some embodiments, the
frame is the mesh. In other embodiment, the mesh is coated with the
membrane. In another embodiment, the anulus augmentation device
comprises only a frame.
[0271] In one embodiment, the mesh or frame region of the implant
can preferably be formed from a relatively thin sheet of material.
The material may be a polymer (including in-situ polymerizing),
metal, or gel. However, as discuss infra, the superelastic
properties of nickel titanium alloy (NITINOL) makes this metal
particularly advantageous in this application. Other materials
suitable for this application include one or more of the following:
nylon, polyvinyl alcohol, polyethylene, polyurethane,
polypropylene, polycaprolactone, polyacrylate, ethylene-vinyl
acetates, polystyrene, polyvinyl oxide, polyvinyl fluoride,
polyvinyl imidazole, chlorosulphonated polyolefins, polyethylene
oxide, polytetrafluoroethylene and nylon, and copolymers and
combinations thereof, polycarbonate, Kevlar.TM., acetal, cobalt
chrome, carbon, graphite, metal matrix composites, stainless steel
and other metals, alloys and composites. Some materials may be
coated to achieve biocompatibility. These materials can also be
used for frames or support member that do not comprise meshes.
[0272] In some embodiments, the mesh or frame designs may have
sharp edges or have gaps that may allow for tissue transfer outside
of the disc. In one embodiment, a membrane may be secured to one or
more sides or portions of the mesh or frame in order to resist
transfer of particles across its periphery and outside of the disc
or to shield the body from the mesh's sharp edges. Also, a membrane
can prevent the flow of a material bounded by the anulus fibrosis
of the intervertebral disc through a defect in the anulus fibrosis
if the device is positioned across the defect.
[0273] In a preferred embodiment, the size of the mesh device is
dictated by the particular region of the functional spinal unit
sought to be treated. For example, In one embodiment, a mesh
intended for coverage the interior surface of the posterior lateral
anulus can be about 2 cm to about 4 cm in length and about 2 mm to
about 15 mm in height. Likewise, the mesh can be sized to cover the
entire exterior or interior surface of a disc. Also, if a defect or
weakened segment of the disc is pre-opertively identified, the size
of the mesh can be selected to adequately span it in more than one
direction. In one embodiment, the mesh is sized such that it spans
all directions by at least about 2 mm. The overlap provided by the
about 2 mm or more mesh, in some embodiments, provides mechanical
means by which the mesh resists extrusion through a defect. Where a
case dictates that a device is not available for full coverage of a
portion of the anulus, the surgeon can select a mesh, barrier, or
patch that is sized such that even if the barrier shifts along an
axis in either direction, the selected width ensures that there
remains about 2 mm or more of the device beyond the edge of the
defect in all positions along that portion of the anulus. In this
way a surgeon can determine a minimum implant size that will still
be efficacious.
[0274] In one embodiment, the anulus augmentation device, such as a
mesh or a membrane/frame combination, has a thickness in a range
between about 0.025 mm to about 3 mm. Nucleus pulposus particles
have been measured at around 0.8 mm.sup.2. Accordingly, in one
embodiment, the anulus augmentation device, such as a mesh or a
membrane/frame combination, has pores slightly smaller (e.g., about
0.05 mm.sup.2 to about 0.75 mm.sup.2) and still function as a means
to prevent extrusion of nuclear material from the disc.
Alternatively, one of ordinary skill in the art can through
experimentation determine the size of disc particles sought to be
contained by the mesh and size the pores slightly smaller. Such a
design affords the fluid transfer of other smaller particles and
especially water, blood, and other tissue fluids.
[0275] In several embodiments, the cross-section of the mesh can be
flat, concave, convex or hinged (or flexibly connected) along at
least a portion of one or more horizontal axes or vertical axes.
One of skill in the art will understand that other cross-sections
can also be used in accordance with several embodiments of the
invention.
[0276] It has been determined that in procedures wherein only a
limited amount of nucleus or anulus tissue is removed from a
pathologic disc, approximately 0.2 to about 2.0 cc of tissue is
typically removed. Accordingly, to replace this volume loss and
contribute to the biomechanical function of the spine, spinal
implants can be designed to replace this volume (about 0.2 to 2.0
cc) through selection of materials and their dimensions.
Accordingly, in one embodiment, an implant having a volume of about
0.2 to about 2.0 cc is provided. The implant can include an anulus
augmentation device, a nuclear augmentation device or an anulus
augmentation/nuclear augmentation combination device. Preferably, a
device having an overall volume of about 0.5 cc is provided because
this is the most typical volume removed. Also, greater volumes may
be used to further increase the volume of the disc in cases where
disc height has decreased over time and the fragments have been
metabolized (and thus do not require removal).
[0277] In one embodiment, an implant comprising a frame and a
membrane is provided. In other embodiments, the implant comprises
only one or more membranes. In one embodiment, the implant
comprises only one or more frames. The frame may be coated. The
membrane (or coating) can be comprised of any suitably durable and
flexible material including polymers, elastomers, hydrogels and
gels such as polyvinyl alcohol, polyethylene, polyurethane,
polypropylene, polycaprolactone, polyacrylate, ethylene-vinyl
acetates, polystyrene, polyvinyl oxides, polyvinyl fluorides,
polyvinyl imidazole, chlorosulphonated polyolefin, polyethylene
oxide, polytetrafluoroethylene, a nylon, silicone, rubber,
polylactide, polyglycolic acid, polylactide-co-glycolide,
polycaprolactone, polycarbonate, polyamide, polyanhydride,
polyamino acid, polyortho ester, polyacetal, polycyanoacrylate,
degradable polyurethane, copolymers and derivatives and
combinations thereof. Biological materials including keratin,
albumin collagen, elastin, prolamines, engineered protein polymers,
and derivatives and combinations thereof, may also be used.
[0278] In one embodiment, at least a portion of the anulus
augmentation device (e.g., the membrane, mesh, barrier, etc) can be
impregnated with, coated with, or designed to carry and deliver
diagnostic agents and/or therapeutic agents. Diagnostic agents
include, but are not limited to, radio-opaque materials suitable to
permit imaging by MRI or X-ray. Therapeutic agents include, but are
not limited to, steroids, genetic vectors, antibodies, antiseptics,
growth factors such as somatomedins, insulin-like growth factors,
fibroblast growth factors, bone morphogenic growth factors,
endothelial growth factors, transforming growth factors, platelet
derived growth factors, hepatocytic growth factors, keratinocyte
growth factors, angiogenic factors, immune system suppressors,
antibiotics, living cells such as fibroblasts, chondrocytes,
chondroblasts, osteocytes, mesenchymal cells, epithelial cells, and
endothelial cells, and cell-binding proteins and peptides. In other
embodiments, the nuclear augmentation device can be impregnated,
coated, or designed to carry diagnostic and/or therapeutic
agents.
[0279] In one embodiment, as shown in FIG. 67, a mesh having a
series of curvilinear elements 602 is provided. In one embodiment,
the curvilinear elements 602 are interconnected. One of skill in
the art will understand that the curvilinear elements 602 can exist
independently of each other, or only be partially connected. The
interconnections 602 can be distributed to form one or more
contiguous horizontal bands, rails, members, struts, or axes 604.
FIG. 67 shows such a device with a central horizontal axis 604 and
"S" shaped curvilinear elements 602. In one embodiment, the "S"
shaped elements 602 tend to distribute the stress generated under
compression over a larger area. In one embodiment, only portions of
the "S" move out of plane during loading providing stiffness. In
some embodiments, the curvilinear elements are particularly
advantageous because they provide flexibility, resilience and/or
rigidity.
[0280] In some embodiments, the curvilinear elements 602 can be
oriented about 90 degrees (curving in the ventral/dorsal axis) such
that the curves appear in the overall horizontal cross-section of
the implant. In other embodiments, the curvilinear elements 602 are
substantially flat. The curvilinear elements 602 can also be
oriented at any angle (e.g., from about 1 degree to about 179
degrees) from the plane. The mesh 600 can be straight, convex or
concave in cross-section. FIGS. 68A-G show the profile of a mesh
with various curvilinear elements. FIGS. 68D-G show top
cross-sectional views of the mesh being elongated "U" shaped, "C"
shaped, curvilinear shaped (like a typical posterior anulus
interior surface), and "D" shaped to extend along and cover the
entire inner anulus surface.
[0281] FIG. 69 shows yet another embodiment of a mesh 600 implanted
in an intervertebral disc. Here, the curvilinear elements 602
comprise springs, coils, or telescopic members that are adapted to
compress axially (like pneumatic pistons or coil springs) under
loading rather than bending and conforming to a tissue surface,
e.g. the inner surface of the anulus. One advantage of a spring or
coil-type mesh is that the mesh can be fairly rigid and resistant
to lateral or transverse force but is flexible enough to span
around the curvatures of the disc while maintaining contact with
the endplates under compression and expansion. Like other
curvilinear elements, the springs or coils can be interconnected,
linked in a loose or hinge-like arrangement, attached to a
horizontal band or axis, attached to a membrane, or encapsulated
within a membrane, or portions thereof.
[0282] In one embodiment, the mesh may also be configured (e.g.,
from wire or stock) in a pattern comprising a series of repeating
curved peaks and valleys oriented in a lateral manner. Two or more
curved wires may be superimposed out of phase such that one peak is
inferior to the adjacent wires valley. The two wires can be
independent, contiguous and formed from a single wire, connected at
one or more points, attached to a membrane, or encapsulated within
a membrane. FIG. 70 shows a wire-type anulus augmentation
device.
[0283] As discussed above, an annulus augmentation device can
comprise, for example, a frame, a membrane or a frame/membrane
combination. FIG. 70 shows just the frame, which can be, for
example, a wire or mesh-like device. FIGS. 71A-E show a mesh that
has been encapsulated by a membrane or cover to produce an
encapsulated mesh 606. FIG. 71C shows a top view cross-section
wherein the mesh is elongated U shaped and 71D through 71F show
various side view cross-sections wherein the mesh is straight or
possesses varying degrees of concavity. As with other barriers
disclosed herein, the membrane or encapsulation material may be of
substantial thickness or may be substantially thin. Indeed, the
encapsulation material may simply be a coating.
[0284] In another embodiment, as shown in FIGS. 72A-B, a mesh 600
having a double-wishbone frame with or without membrane cover is
provided. In some embodiments, this design is particularly
advantageous because it reduces the compression and stress
experienced by the implant under flexion, extension, and lateral
bending. FIG. 72A shows the frame without a membrane situated along
a posterior portion of the disc. The implant (e.g., the frame) can
also be placed on the outside of the anulus, within the anulus,
between the nucleus and anulus or within the nucleus. Also shown is
a defect 16 in the anulus 10 and placement of the frame 600 across
the defect and spanning beyond it in more than a single direction.
FIG. 72B shows the mesh in a perspective view outside of the disc.
The frame (e.g., mesh) can be flat or an elongated "U" shaped
corresponding to the inner surface of the posterior anulus. In one
embodiment, the frame can be a single continuous band or wire
forming two ends, a first end and a second end. In one embodiment,
each end functions as a living hinge and forms an apex which may be
in the form of a curve, a bend, or series of bends such that the
wire is generally redirected in the opposite direction.
Accordingly, if a load is applied along the vertical axis at the
midpoint of the frame, e.g., the midpoint of the top and bottom
(superior, inferior) rail, each corner or apex is loaded equally
and the wire rails act as levers.
[0285] In one embodiment, the mesh 600 can be implanted such that
the midpoint of the mesh frame 600 is in the posterior of the disc
and the ends reside medially or even in the anterior portion of the
disc. In this way the portion of the mesh 600 that undergoes the
greatest compression is furthest away from each end. Accordingly, a
relatively large range of motion can be traversed by the middle of
the device but this will only translate to limited motion at each
end or living hinge, thus reducing stress and fatigue. Also, by
placing each end (which has a relatively small profile) at opposing
sides at the midline of the disc (the center of rotation) it is
subjected to almost no direct loading under lateral bending,
flexion, extension, or compression by the endplates.
[0286] FIGS. 73A-C shows other embodiments for the end or natural
hinge portion of the frame (e.g., mesh 600), including a loop
formation.
[0287] FIGS. 74A-C show some embodiments of the central band or
strut 604. FIGS. 74A-B show a central reinforcement band 604
disposed between the ends or apexes of the frame (e.g., mesh). As
shown in FIG. 74B, the central band 604 can be positioned between
the top rail (or wire) 603 and bottom rail (or wire) 605. As shown
in FIG. 74C, the central band 604 can be elongated to form a
concave cross-section between the top and bottom rail or wire.
[0288] In several embodiments of the invention, an implant (e.g.,
an anulus augmentation device, such as a mesh) can exhibit
different mechanical properties along various axes. For example, an
implant can exhibit rigidity along a first axis and flexibility (or
less rigidity) along a second axis transverse or perpendicular to
the first. Such an implant might find particular utility along the
wall of an anulus between two adjacent vertebrae because such an
environment will subject the implant to vertical compression (e.g.,
along the superior/inferior axis) yet will not compress the implant
laterally. As such, the implant can retain its rigidity along its
horizontal axis. Rigidity along the horizontal axis of anulus
augmentation device is especially useful in some embodiments if the
implant is placed in front of a weakened or defective surface of
the anulus because a point load will like form at that region when
the disc is compressed under loading and could cause the implant to
bend and extrude. Accordingly, an implant having a certain degree
of rigidity along its lateral axis resists such bending and
extrusion. Moreover, because of the less rigid and more flexible
behavior of the implant along its vertical axis loads caused
flexion and extension of the spine will allow the implant to flex
naturally with the spine and not injure the endplates.
[0289] In some embodiments, to achieve the differences in
mechanical properties, any number of construction, material
selection or fabrication techniques known in the art can be used.
For example, the implant may be made thicker or thinner at points
along a particular axis or voids or patterns may be cut into the
material. Also, a composite implant having different material
sandwiched together can also be used. Struts, members, rails and
the like may be added to, secured to, or integral to the implant to
provide stiffness and rigidity. Further, such stiffening elements
can be added during the implantation procedure.
[0290] In one embodiment, the implant can also be corrugated along
an axis or otherwise be provided with bents or curves to provide
stiffness. A gentle curve or "C" shaped cross-section that could
also conform or correspond to the inner curved surface of an anulus
is also preferable for making a seal with the anulus and for
resisting bending along the implant horizontal axis e.g., the curve
would resist flattening out, flexing or bending laterally. Also, in
some embodiments the implant can be oversized such that it remains
in compression along one or more of its axes in its implanted state
such that even under flexion and extension of the spine the
corrugations or curved sections never flatten out and thus retain
rigidity (or less flexibility) along an axis perpendicular to the
curves.
[0291] One of skill in the art will understand that, in several
embodiments, the implant (e.g., an anulus augmentation device, such
as a mesh) can be more or less rigid or flexible, according to the
preference of the practitioner or disc environment. The degree of
desired rigidity and flexibility along each axis can be determined
based on factors such as defect size, intervertebral pressure,
implant deliverability, desired degree of compression and disc
height.
[0292] According to one embodiment of the invention, an implant has
a "C" cross-section, a central rail and top and bottom rails, and
curvilinear elements connect the rails. The frame or mesh can be
comprised of any of the suitable materials discussed herein, (e.g.
nickel titanium) and can also be coated, covered, bonded, or
coupled to a cover or membrane. In one embodiment, the implant is
more rigid along its lateral axis because of its "C" cross-section
or the rails and less rigid along its vertical axis because of the
void caused by the pattern and lack of corrugations or stiffening
elements.
[0293] Though some embodiments of the invention disclose a mesh
frame, patch, plate, biocompatible support member or barrier
adapted to extend along the inner circumference of an anulus
fibrosus, other embodiments contemplate partial coverage of the
anulus or tissue surface. For some embodiments that that cover less
than the entire inner surface of the anulus or that are not fully
anchored in place, and are susceptible to migration, one or more
projections extending outward from, or off-angle to the implant can
be configured to resist migration or movement of the implant within
the disc under cyclical loading and movement of the spine. One
advantage of such embodiments is that they can reduce or prevent
migration. Undesired migration may render the implant ineffective
or cause it to pathologically interfere with adjacent tissue
including the anulus, nucleus, endplates and spinal cord.
[0294] According to one embodiment, an implant can be stabilized
within an intervertebral disc by providing a support member or
patch with an off-angle projection functioning as a lever arm or
keel. In some embodiments, even a slightly angled projection (e.g.,
about 5 to about 10 degrees) can serve to reduce the tendency of
the device to rotate or migrate if it has sufficient surface area
and length (about 3 mm to about 30 mm). As shown previously in
FIGS. 25 and 34, one embodiment of an anulus augmentation device
can have one or more corners, sides or projections connected at the
opposing end of the devices midsection or middle portion. Such a
configuration is especially effective when implanted into an
intervertebral disc such that the midsection of the barrier is
inserted along the posterior anulus and the corners and side
projections are inserted along the posterio-lateral corners and
lateral anulus respectively. In one embodiment, the corner sections
extend away from the posterior anulus toward the anterior of the
disc. The projections that project away from the posterior anulus
at an angle (about 90 degrees or through a radius of curvature
resulting in an angle from about 30 to about 150 degrees) are
substantially parallel with or adjacent to the lateral anulus.
Thus, the projection portion of the implant in its implanted
orientation is at once off-angle to the posterior anulus or
midsection of the barrier and parallel to the lateral anulus.
Because the anulus defines a bounded area such a projection may
indeed collide with or be parallel with another adjacent or
opposing surface of the anulus but still function to stabilize the
device along the other surface. The device can also be designed
with one or more projections that are angled toward the medial,
anterior, posterior, or lateral portion of the disc such that the
projection contacts mostly or exclusively nucleus tissue or
endplate. For example, a looped projection connected at the top and
bottom and/or opposing ends of the support member, frame, or patch
can be configured to extend across the disc from about 3 mm to
about 30 mm and only contact nucleus tissue. In another embodiment,
one or more projections can be oriented into a defect in the anulus
and occupy less than or all of its volume. In another embodiment, a
projection situated within a defect may be anchored into an
endplate adjacent the defect. FIGS. 75A-L show an implant 610
(e.g., an annulus augmentation device such as a mesh) having one or
more projections extending into the disc or into a defect.
[0295] A stabilizing projection according to one or more
embodiments of the invention can be integral or affixed to the
surgical mesh, patch, plate, biocompatible support member or
barrier device. The stabilizing projection can also be independent
of or coupled to at least a portion of the frame or the membrane.
The stabilizing projection can be constructed from the same
material as the frame or the membrane, or it can be constructed
from different material. The stabilizing projection can extend from
any point or points along the device or device frame including its
opposing ends, mid-section, along the top edge or along the bottom
edge. The projection can also form a loop in one or more planes
including parallel and perpendicular to the face of the device. For
example, in one embodiment opposing end projections are connected
to, or are integral to, the barrier and extend out from the barrier
at an angle from about 0 to about 160 degrees. In another
embodiment, the projections are joined or are simply contiguous and
form a bow-shaped or curved projection extending away from the
barrier. In this embodiment, the barrier can be placed along a
portion of the anulus and the bow would extend medially into the
disc. In another embodiment, the barrier can be placed along at
least a portion of the posterior anulus and the bowed projection,
attached at the opposing ends of the barrier frame or membrane,
would extend toward the anterior of the disc.
[0296] FIG. 76 shows an implant 610 according to one embodiment of
the invention. Here, a bow-like anterior projection 612 extends
outwardly from a posterior support member 614 (e.g., a patch,
barrier or mesh). The projection 612 can be connected at each end
of the posterior support member 614 along its horizontal axis. The
projection 612 can be attached at any point along the vertical axis
of the end including its midline, ends, or its entirety. The
projection 612 may be integral to the posterior support member 614
such that the posterior support member 614 is simply formed as a
band or attached separately. As shown the implant 610 can be shaped
like a bow. The bow can be a gentle arc, curved, re-curved one or
more times, triangular, rectangular, octagonal, linked multiple
sided, oval or circular. Though in some embodiments, an arc or
smooth bow may be advantageous for transferring loads evenly, a
rigid mid-section portion or a comparatively flexible hinge-like
mid-section along the bow is also presented. The mid-section of the
bow projection can have a different height than the remainder of
the bow and be the same or different (less than or greater than)
height than the midsection patch or biocompatible support member
portion of the device.
[0297] Various embodiments of the bow or arcurate member or
projection 612 can act like a spring to aid in holding the ends of
the patch open and against the anulus wall. Similarly, in one
embodiment, the profile of the projection 612 can provide
resistance to anterior travel of the implant through the nucleus or
through the opposite wall of the anulus. In another embodiment of
the invention, the projection or stabilizer 612 can also provide
torsional resistance to the barrier 614. Finally, because the
projection or bow 612 extends across the endplates it creates an
elongated profile functioning as a lever arm and thus resists
rotation along the anulus wall within the disc.
[0298] The projection, bow or band portion 612 of the implant 610
can be tubular, wire-like, flat, mesh-like, curvilinear, bent,
comprised of one or more rails, or contain voids. The bow can
define concavities facing inward or outward and be opposite or the
same as the concavities defined by the biocompatible support member
portion 614 of the implant 610. The projection 612 can simply be
angled projections of the biocompatible support member and be made
of the same material and have the same properties. Alternatively
the projection can have different properties such as less
flexibility or more rigidity along one or more axes. Although one
projection is shown in FIG. 76, more than one bow-like projections
may be used.
[0299] Different bow or loop projection profiles may be useful for
retaining nucleus tissue within the area bounded by the implant,
soft anchoring to the nucleus or at least resisting travel through
or along the nucleus, or for mechanically displacing nucleus
tissue. Mechanical displacement (through pinching or pressing) of
the nucleus can increase disc height and serve to more uniformly
load the anulus and improve the performance of the implant. Also,
the gap within the disc created by the bow or projection can be
left vacant or filled in with suitable nucleus augmentation either
through, or around a periphery of the implant. The bow projection
612 can also act as a piston or shock absorber that deforms under
compressive loading of the disc relieving some of the load on the
anulus caused by the nucleus being compressed between the
endplates.
[0300] The stabilizing projection 612 can be made of the same
material as the biocompatible support member 614 (e.g., barrier,
patch or mesh). In one embodiment, the stabilizing projection 612
is an off-angle projection of the biocompatible support member 614
and forms a continuous loop or band. In another embodiment, the
stabilizing projection 612 can be made of a different biocompatible
material, including polymers, metals, bio-materials, and
grafts.
[0301] FIGS. 77A-H show various cross-sectional side views of an
implant 610 along a horizontal axis according to one or more
embodiments of the invention. Accordingly, a bow, band or
projection can be uniform in height or non-uniform. It can be the
same height, shorter or taller than the patch portion of the
implant. For example, in one embodiment, a projection is narrow at
the point where it connects to the posterior support member
component of the implant and then flairs near the midline of the
anterior bow until its height exceeds the posterior member height.
Such a configuration might be favorable between cupped or concave
vertebral endplates when the posterior member portion of the
implant is positioned against the posterior anulus. Further, in one
or more embodiments of the invention, a projection can have
different mechanical properties than the support member or patch
section of the implant. For example, in one embodiment, a
projection is more or less flexible along one or more axes compared
to the patch or biocompatible support member portion of the
implant. In another embodiments, a projection can be concave along
one or more axes, or can have variable regions of concavity along
the same axis.
[0302] FIGS. 78A-J show various cross-sectional top views of
implants 610 along a vertical axis according to some embodiments of
the invention. For example, FIG. 78G shows an implant (e.g., an
anulus augmentation device such as a mesh) that has a puckered
bow-like projection that is well-suited for disc morphology.
[0303] FIGS. 79A-F show a frontal view of a portion of various
embodiments of projections according to one or more embodiments of
the invention.
[0304] FIGS. 80A-D show various cross-sections of projection 612,
according to some embodiments of the invention.
[0305] FIGS. 81A-D show looped or bent bow-type projections 612
that are contiguous or integral with, or are connected to the
biocompatible support member 614 at two or more points along a
vertical or horizontal axis. FIG. 81A shows a criss-cross loop
projection. FIG. 81B shows a strap-like projection. FIG. 81C shows
a projection that is integral with the support member such that the
implant forms a circular band that serves to stabilize the device.
FIG. 81D shows a box-frame type projection.
[0306] One skilled in the art will appreciate that any of the above
procedures involving nuclear augmentation and/or anulus
augmentation may be performed with or without the removal of any or
all of the autologous nucleus. Further, the nuclear augmentation
materials and/or the anulus augmentation device may be designed to
be safely and efficiently removed from the intervertebral disc in
the event they are no longer required.
[0307] While this invention has been particularly shown and
described with references to preferred embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *