US20100204797A1 - Anulus lesion repair - Google Patents

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.

Description

RELATED APPLICATIONS
• 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
• 1. Field of the Invention
• 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.
• 2. Description of the Related Art
• 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.
• 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.
• 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.
• 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.
• 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
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• In one embodiment, the curvilinear members comprise a metal alloy such as steel, nickel titanium, cobalt chrome, or combinations thereof.
• 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™), poly carbonate, carbon, graphite, or a combination thereof.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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
• 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.
• 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.
• FIG. 1B shows a sagittal cross section of a portion of a functional spine unit shown inFIG. 1A, in which two lumbar vertebrae and the intervertebral disc are visible.
• FIG. 1C shows partial disruption of the inner layers of an anulus fibrosis.
• FIG. 2A shows a transverse section of one aspect of the present invention prior to supporting a herniated segment, as shown in one embodiment.
• FIG. 2B shows a transverse section of the construct inFIG. 2A supporting the herniated segment.
• FIG. 3A shows a transverse section of another embodiment of the disclosed invention after placement of the device.
• FIG. 3B shows a transverse section of the construct inFIG. 3A after tension is applied to support the herniated segment.
• FIG. 4A shows a transverse view of an alternate embodiment of the invention.
• FIG. 4B shows a sagittal view of the alternate embodiment shown inFIG. 4A.
• FIG. 5A shows a transverse view of another aspect of the present invention, as shown in one embodiment.
• FIG. 5B shows the delivery tube ofFIG. 5A being used to displace the herniated segment to within its pre-herniated borders.
• FIG. 5C shows a one-piece embodiment of the invention in an anchored and supporting position.
• FIG. 6 shows one embodiment of the invention supporting a weakened posterior anulus fibrosis.
• 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.
• FIG. 7B shows a sagittal view of the invention shown inFIG. 7A.
• 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.
• 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.
• 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.
• FIG. 10A shows a transverse section of one aspect of the disclosed invention involving augmentation of the soft tissues of the disc.
• FIG. 10B shows the construct ofFIG. 10A after the augmentation material has been inserted into the disc.
• FIG. 11 illustrates a transverse section of a barrier mounted within an anulus.
• FIG. 12 shows a sagittal view of the barrier ofFIG. 11.
• FIG. 13 shows a transverse section of a barrier anchored within a disc.
• FIG. 14 illustrates a sagittal view of the barrier shown inFIG. 13.
• FIG. 15 illustrates the use of a second anchoring device for a barrier mounted within a disc.
• FIG. 16A is an transverse view of the intervertebral disc.
• FIG. 16B is a sagittal section along the midline of the intervertebral disc.
• 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.
• FIG. 18 illustrates a full sealing means placed on the interior aspect of a defect in anulus fibrosis.
• FIG. 19 depicts the sealing means ofFIG. 18 being secured to tissues surrounding the defect.
• FIG. 20 depicts the sealing means ofFIG. 19 after fixation means have been passed into surrounding tissues.
• FIG. 21A depicts an axial view of the sealing means ofFIG. 20 having enlarging means inserted into the interior cavity.
• FIG. 21B depicts the construct ofFIG. 21 in a sagittal section.
• FIG. 22A shows an alternative fixation scheme for the sealing means and enlarging means.
• FIG. 22B shows the construct ofFIG. 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.
• 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.
• FIG. 23B depicts an embodiment of the barrier means ofFIG. 23A secured to an anulus by two fixation darts wherein the fixation tool has been removed.
• FIGS. 24A and 24B depict a barrier means positioned between layers of the anulus fibrosis on either side of a defect.
• FIG. 25 depicts an axial cross section of a large version of a barrier means.
• FIG. 26 depicts an axial cross section of a barrier means in position across a defect following insertion of two augmentation devices.
• FIG. 27 depicts the barrier means as part of an elongated augmentation device.
• FIG. 28A depicts an axial section of an alternate configuration of the augmentation device ofFIG. 27.
• FIG. 28B depicts a sagittal section of an alternate configuration of the augmentation device ofFIG. 27.
• FIGS. 29A-D depict deployment of a barrier from an entry site remote from the defect in the anulus fibrosis.
• FIGS. 30A,30B,31A,31B,32A,32B,33A, and33B depict axial and sectional views, respectively, of various embodiments of the barrier.
• FIG. 34 shows a non-axisymmetric expansion means or frame.
• FIGS. 34B and 34C illustrate perspective views of a frame mounted within an intervertebral disc.
• FIGS. 35 and 36 illustrate alternate embodiments of the expansion means shown inFIG. 34.
• FIGS. 37A-C illustrate a front, side, and perspective view, respectively, of an alternate embodiment of the expansion means shown inFIG. 34.
• FIG. 38 shows an alternate expansion means to that shown inFIG. 37A.
• FIGS. 39A-D illustrate a tubular expansion means having a circular cross-section.
• FIGS. 40A-I illustrate tubular expansion means.FIGS. 40A-D illustrate a tubular expansion means having an oval shaped cross-section.FIGS. 40E,40F and401 illustrate a front, back and top view, respectively of the tubular expansion means ofFIG. 40A having a sealing means covering an exterior surface of an anulus face.FIGS. 40G and 40H show the tubular expansion means ofFIG. 40A having a sealing means covering an interior surface of an anulus face.
• FIGS. 41A-D illustrate a tubular expansion means having an egg-shaped cross-section.
• FIG. 42A-D depicts cross sections of a preferred embodiment of sealing and enlarging means.
• FIGS. 43A and 43B depict an alternative configuration of enlarging means.
• FIGS. 44A and 44B depict an alternative shape of the barrier means.
• FIG. 45 is a section of a device used to affix sealing means to tissues surrounding a defect.
• FIG. 46 depicts the use of a thermal device to heat and adhere sealing means to tissues surrounding a defect.
• FIG. 47 depicts an expandable thermal element that can be used to adhere sealing means to tissues surrounding a defect.
• FIG. 48 depicts an alternative embodiment to the thermal device ofFIG. 46.
• FIGS. 49A-G illustrate a method of implanting an intradiscal implant.
• FIGS. 50A-F show an alternate method of implanting an intradiscal implant.
• FIGS. 51A-C show another alternate method of implanting an intradiscal implant.
• FIGS. 52A and 52B illustrate an implant guide used with the intradiscal implant system.
• FIG. 53A illustrates a barrier having stiffening plate elements.
• FIG. 53B illustrates a sectional view of the barrier ofFIG. 53A.
• FIG. 54A shows a stiffening plate.
• FIG. 54B shows a sectional view of the stiffening plate ofFIG. 54A.
• FIG. 55A illustrates a barrier having stiffening rod elements.
• FIG. 55B illustrates a sectional view of the barrier ofFIG. 55A.
• FIG. 56A illustrates a stiffening rod.
• FIG. 56B illustrates a sectional view of the stiffening rod ofFIG. 56A.
• FIG. 57 shows an alternate configuration for the location of the fixation devices of the barrier ofFIG. 44A.
• FIGS. 58A and 58B illustrate a dissection device for an intervertebral disc.
• FIGS. 59A and 59B illustrate an alternate dissection device for an intervertebral disc.
• FIGS. 60A-C illustrate a dissector component.
• FIGS. 61A-D illustrate a method of inserting a disc implant within an intervertebral disc.
• 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.
• 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.
• 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.
• FIG. 65 illustrates a sagittal cross-sectional view of a barrier device connected to an inflatable nuclear augmentation device.
• 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.
• FIG. 67 shows an anulus augmentation device (such as a mesh) mesh having a series of curvilinear elements.
• 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.
• FIG. 69 shows one embodiment of a mesh with curvilinear elements implanted in an intervertebral disc.
• FIG. 70 shows a wire-type anulus augmentation device.
• FIGS. 71A-E show a frame (e.g., mesh) that has been encapsulated by a membrane or cover to produce an encapsulated mesh.
• FIGS. 72A-B show a mesh having a double-wishbone frame.
• FIGS. 73A-C shows embodiments of the end or natural hinge portion of the frame, including a looped terminus.
• FIGS. 74A-C show some embodiments of the central band or strut.
• 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.
• FIG. 76 shows an implant comprising a bow-like anterior projection that extends outwardly from a posterior support member.
• FIGS. 77A-H show various cross-sectional side views along a horizontal axis of an implant comprising a bow, band or projection.
• FIGS. 78A-J show various cross-sectional top views of implants along a vertical axis.
• FIGS. 79A-F show a frontal view of a portion of several embodiments of an implant projection.
• FIGS. 80A-D show various cross-sections of an implant projection.
• FIGS. 81A-D show looped or bent bow-type projections.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• 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.
• FIGS. 1A and 1B show the general anatomy of afunctional spine unit45. 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).
• FIG. 1A is an axial view along the transverse axis M of a vertebral body with theintervertebral disc15 superior to the vertebral body. Axis M shows the anterior (A) and posterior (P) orientation of the functional spine unit within the anatomy. Theintervertebral disc15 contains the anulus fibrosis (AF)10 which surrounds a central nucleus pulposus (NP)20. AHerniated segment30 is depicted by a dashed-line. The herniatedsegment30 protrudes beyond the pre-herniatedposterior border40 of the disc. Also shown in this figure are the left70 and right70′ transverse spinous processes and the posteriorspinous process80.
• FIG. 1B is a sagittal section along sagittal axis N through the midline of two adjacent vertebral bodies50 (superior) and50′ (inferior).Intervertebral disc space55 is formed between the two vertebral bodies and containsintervertebral disc15, 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.
• Intervertebral disc15 is comprised of theouter AF10 which normally surrounds and constrains theNP20 to be wholly within the borders of the intervertebral disc space. InFIGS. 1A and 1B, herniatedsegment30, represented by the dashed-line, has migrated posterior to thepre-herniated border40 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 joints60 and the superior90 and inferior90′ pedicle that form theneural foramen100. Disc height loss occurs when the superiorvertebral body50 moves inferiorly relative to the inferiorvertebral body50′.
• Partial disruption121 of the inner layers of theanulus10 without a true perforation has also been linked to chronic low back pain. Such adisruption4 is illustrated inFIG. 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.
• In one embodiment of the present invention, the discherniation constraining devices13 provide support for returning all or part of the herniatedsegment30 to a position substantially within itspre-herniated borders40. 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.
• FIGS. 2A and 2B depict one embodiment ofdevice13.FIG. 2A shows the elements of the constraining device in position to correct the herniated segment.Anchor1 is securely established in a location within the functional spine unit, such as the anterior AF shown in the figure.Support member2 is positioned in or posterior to herniatedsegment30. Leading from and connected to anchor1 isconnection member3, which serves to connectanchor1 to supportmember2. Depending on the location chosen forsupport member2, the connection member may traverse through all or part of the herniated segment.
• FIG. 2B shows the positions of the various elements of theherniation constraining device13 when thedevice13 is supporting the herniated segment. Tighteningconnection member2 allows it to transmit tensile forces along its length, which causes herniatedsegment30 to move anteriorly, i.e., in the direction of its pre-herniated borders. Once herniatedsegment30 is in the desired position,connection member3 is secured in a permanent fashion betweenanchor1 andsupport member2. This maintains tension betweenanchor1 andsupport member2 and restricts motion of the herniated segment to within thepre-herniated borders40 of the disc.Support member2 is used to anchor to herniatedsegment30, 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 herniatedsegment30.
• Anchor1 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.Anchor1 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,anchor1 should remain relatively stationary within the bone or tissue.
• Support member2 is also depicted in a representative format and shares the same flexibility in material and design asanchor1. 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 member2 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 member2 can be established securely to, within, or posterior to the herniated segment.
• 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.
• Connection member3 is also depicted in representative fashion.Member3 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.
• FIGS. 3A and 3B depict another embodiment ofdevice13. InFIG. 3A the elements of the herniation constraining device are shown in position prior to securing a herniated segment.Anchor1 is positioned in the AF andconnection member3 is attached toanchor1.Support member4 is positioned posterior to the posterior-most aspect of herniatedsegment30. In this way,support member4 does not need to be secured in herniatedsegment30 to cause herniatedsegment30 to move within thepre-herniated borders40 of the disc.Support member4 has the same flexibility in design and material asanchor1, 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 herniatedsegment30 or is simply in a form that is larger than any hole in the AF directly anterior to supportmember4.FIG. 3B shows the positions of the elements of the device when tension is applied betweenanchor1 andsupport member4 alongconnection member3. The herniated segment is displaced anteriorly, within thepre-herniated borders40 of the disc.
• FIGS. 4A and 4B show five examples of suitable anchoring sites within the FSU foranchor1.FIG. 4A shows an axial view ofanchor1 in various positions within the anterior and lateral AF.FIG. 4B similarly shows a sagittal view of the various acceptable anchoring sites foranchor1.Anchor1 is secured in the superiorvertebral body50, inferiorvertebral body50′ oranterior AF10, although any site that can withstand the tension betweenanchor1 andsupport member2 alongconnection member3 to support a herniated segment within itspre-herniated borders40 is acceptable.
• Generally, a suitable position for affixing one or more anchors is a location anterior to the herniated segment such that, when tension is applied alongconnection member3, herniatedsegment30 is returned to a site within the pre-herniated borders40. 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 inFIGS. 4A and 4B,anchor1 can be a single anchor in any of the shown locations, or there can bemultiple anchors1 affixed in various locations and connected to asupport member2 to support the herniated segment.Connection member3 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.
• 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.
• FIGS. 5A-C show an alternate embodiment of herniation constraining device13A. In this series of figures, device13A, a substantially one-piece construct, is delivered through a delivery tube6, although device13A could be delivered in a variety of ways including, but not limited to, by hand or by a hand held grasping instrument. InFIG. 5A, device13A in delivery tube6 is positioned against herniatedsegment30. InFIG. 5B, the herniated segment is displaced within itspre-herniated borders40 by device13A and/or delivery tube6 such that when, inFIG. 5C, device13A has been delivered through delivery tube6, and secured within a portion of the FSU, the device supports the displaced herniated segment within itspre-herniated border40. Herniation constraining device13A can be made of a variety of materials and have one of many possible forms so long as it allows support of the herniatedsegment30 within thepre-herniated borders40 of the disc. Device13A can anchor the herniatedsegment30 to any suitable anchoring site within the F SU, including, but not limited to the superior vertebral body, inferior vertebral body, or anterior AF. Device13A may be used additionally to close a defect in the AF of herniatedsegment30. Alternatively, any such defect may be left open or may be closed using another means.
• FIG. 6 depicts the substantially one-piece device13A supporting a weakenedsegment30′ of theposterior AF10′. Device13A is positioned in or posterior to the weakenedsegment30′ and secured to a portion of the FSU, such as the superiorvertebral body50, shown in the figure, or the inferiorvertebral body50′ or anterior or anterior-lateral anulus fibrosis10. 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.
• 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 ofdevice13 securing augmentation material in theintervertebral disc space55. In the left side ofFIG. 7A, anchors1 have been established in theanterior AF10.Augmentation material7 is in the process of being inserted into the disc space alongconnection member3 which, in this embodiment, haspassageway9.Support member2′ is shown ready to be attached toconnection member3 once theaugmentation material7 is properly situated. In this embodiment,connection member3 passes through anaperture11 insupport member2′, although many other methods ofaffixing support member2′ toconnection member3 are possible and within the scope of this invention.
• Augmentation material7 may have apassageway9, such as a channel, slit or the like, which allows it to slide along theconnection member3, oraugmentation material7 may be solid, andconnection member3 can be threaded through augmentation material by means such as needle or other puncturing device.Connection member3 is affixed at one end toanchor1 and terminated at its other end by asupport member2′, one embodiment of which is shown in the figure in a cap-like configuration.Support member2′ can be affixed toconnection member3 in a variety of ways, including, but not limited to, swagingsupport member2′ toconnection member3. In a preferred embodiment,support member2′ is in a cap configuration and has a dimension (diameter or length and width) larger than theoptional passageway9, which serves to preventaugmentation material7 from displacing posteriorly with respect toanchor1. The right half of the intervertebral disc ofFIG. 7A (axial view) andFIG. 7B (sagittal view)show augmentation material7 that has been implanted into thedisc space55 alongconnection member3 where it supports thevertebral bodies50 and50′.FIG. 7A shows an embodiment in whichsupport member2′ is affixed toconnection member3 and serves only to preventaugmentation material7 from moving offconnection member3. The augmentation device is free to move within the disc space.FIG. 7B shows an alternate embodiment in whichsupport member2′ is embedded in a site in the functional spine unit, such as a herniated segment or posterior anulus fibrosis, to further restrict the movement ofaugmentation material7 or spacer material within the disc space.
• 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.
• FIGS. 8,9A,9B and10A and10B depict further embodiments of the disc herniation constraining device13B in use for augmenting soft tissue, particularly tissue within the intervertebral space. In the embodiments shown inFIGS. 8 and 9A, device13B is secured within the intervertebral disc space providing additional support forNP20.Anchor1 is securely affixed in a portion of the FSU, (anterior AF10 in these figures).Connection member3 terminates atsupport member2, preventingaugmentation material7 from migrating generally posteriorly with respect toanchor1.Support member2 is depicted in these figures as established in various locations, such as theposterior AF10′ inFIG. 8, butsupport member2 may be anchored in any suitable location within the FSU, as described previously.Support member2 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 means1 and2 alongconnection member3.
• FIG. 9A depictsanchor1,connection member3,spacer material7 andsupport member2′ (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 inFIGS. 7 and 8 by reducing the number of steps to achieve implantation.Connection member3 is preferably relatively stiff in tension, but flexible against all other loads.Support member2′ is depicted as a bar element that is larger thanpassageway9 in at least one plane.
• FIG. 9B depicts a variation on the embodiment depicted inFIG. 9A.FIG. 9B shows substantially one-piece disc augmentation device13C, secured in the intervertebral disc space. Device13C hasanchor1,connection member3 andaugmentation material7.Augmentation material7 andanchor1 could be pre-assembled prior to insertion into thedisc space55 as a single construct. Alternatively,augmentation material7 could be inserted first into the disc space and then anchored to a portion of the FSU byanchor1.
• FIGS. 10A and 10B show yet another embodiment of the disclosed invention,13D. InFIG. 10A, twoconnection members3 and3′ are attached toanchor1. Two plugs ofaugmentation material7 and7′ are inserted into the disc space alongconnection members3 and3′.Connection members3 and3′ are then bound together (e.g., knotted together, fused, or the like). This formsloop3″ that serves to preventaugmentation materials7 and7′ from displacing posteriorly.FIG. 10B shows the position of theaugmentation material7 after it is secured by theloop3″ andanchor1. 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 fromanchor1 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.
• 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.
• 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 means12 into thedisc15. This procedure can accompany surgical discectomy. It can also be done without the removal of any portion of thedisc15 and further in combination with the insertion of an augmentation material or device into thedisc15.
• The method consists of inserting thebarrier12 into the interior of thedisc15 and positioning it proximate to the interior aspect of theanulus defect16. The barrier material is preferably considerably larger in area than the size of thedefect16, such that at least some portion of the barrier means12 abutshealthier anulus fibrosis10. The device acts to seal theanulus defect16, recreating the closed isobaric environment of ahealthy disc nucleus20. This closure can be achieved simply by an over-sizing of the implant relative to thedefect16. It can also be achieved by affixing the barrier means12 to tissues within the functional spinal unit. In one embodiment of the present invention, thebarrier12 is affixed to the anulus surrounding theanulus defect16. This can be achieved with sutures, staples, glues or other suitable fixation means orfixation device14. The barrier means12 can also be larger in area than thedefect16 and be affixed to a tissue or structure opposite thedefect16, e.g., anterior tissue in the case of a posterior defect.
• The barrier means12 is preferably flexible in nature. It can be constructed of a woven material such as Dacron™ or Nylon™, a synthetic polyamide or polyester, a polyethylene, and can further be an expanded material, such as expanded polytetrafluroethylene (e-PTFE), for example. The barrier means12 can also be a biologic material such as cross-linked collagen or cellulous.
• The barrier means12 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 thedisc15. 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.
• FIGS. 11 and 12 illustrate abarrier12 mounted within ananulus10 and covering ananulus defect16. Thebarrier12 can be secured to theanulus10 with a fixation mechanism or fixation means14. The fixation means14 can include a plurality of suture loops placed through thebarrier12 and theanulus10. Such fixation can prevent motion or slipping of thebarrier12 away from theanulus defect16.
• The barrier means12 can also be anchored to thedisc15 in multiple locations. In one preferred embodiment, shown inFIGS. 13 and 14, the barrier means12 can be affixed to theanulus tissue10 in or surrounding the defect and further affixed to a secondary fixation site opposite the defect, e.g. theanterior anulus10 in a posterior herniation, or the inferior50′ or superior50 vertebral body. For example, fixation means14 can be used to attach thebarrier12 to theanulus10 near thedefect16, while ananchoring mechanism18 can secure thebarrier12 to a secondary fixation site. Aconnector22 can attach thebarrier12 to theanchor18. Tension can be applied between the primary and secondary fixation sites through aconnector22 so as to move theanulus defect16 toward the secondary fixation site. This may be particularly beneficial in closingdefects16 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 theanulus10.
• The barrier means12 can further be integral to a fixation means such that the barrier means affixes itself to tissues within the functional spinal unit.
• Any of the methods described above can be augmented by the use of a second barrier or a second barrier means24 placed proximate to the outer aspect of thedefect16 as shown inFIG. 15. Thesecond barrier24 can further be affixed to the inner barrier means12 by the use of a fixation means14 such as suture material.
• FIGS. 16A and 16B depictintervertebral disc15 comprising nucleus pulposus20 andanulus fibrosis10.Nucleus pulposus20 forms a first anatomic region and extra-discal space500 (any space exterior to the disc) forms a second anatomic region wherein these regions are separated byanulus fibrosis10.
• FIG. 16A is an axial (transverse) view of the intervertebral disc. A posteriorlateral defect16 inanulus fibrosis10 has allowed asegment30 ofnucleus pulposus20 to herniate into an extradiscal space500.Interior aspect32 andexterior aspect34 are shown, as are the right70′ and left70 transverse processes andposterior process80.
• FIG. 16B is a sagittal section along the midline intervertebral disc.Superior pedicle90 andinferior pedicle90′ extend posteriorly from superior vertebral body95 and inferior vertebral body95′ respectively.
• To prevent further herniation of thenucleus20 and to repair any present herniation, in a preferred embodiment, a barrier or barrier means12 can be placed into a space between theanulus10 and thenucleus20 proximate to theinner aspect32 ofdefect16, as depicted inFIGS. 17 and 18. The space can be created by blunt dissection. Dissection can be achieved with a separate dissection instrument, with the barrier means12 itself, or a combined dissection/barrier delivery tool100. This space is preferably no larger than the barrier means such that the barrier means12 can be in contact with both anulus10 andnucleus20. This allows the barrier means12 to transfer load from thenucleus20 to theanulus10 when the disc is pressurized during activity.
• In position, the barrier means12 preferably spans thedefect16 and extends along theinterior aspect36 of theanulus10 until it contacts healthy tissues on all sides of thedefect16, 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 thedefect16, the contacted tissues can include theanulus10, cartilage overlying the vertebral endplates, and/or the endplates themselves.
• In the preferred embodiment, the barrier means12 comprises two components—a sealing means or sealingcomponent51 and an enlarging means or enlargingcomponent53, shown inFIGS. 21A and 21B.
• The sealing means51 forms the periphery of thebarrier12 and has aninterior cavity17. There is at least oneopening8 leading intocavity17 from the exterior of the sealing means51. Sealing means51 is preferably compressible or collapsible to a dimension that can readily be inserted into thedisc15 through a relatively small hole. This hole can be thedefect16 itself or a site remote from thedefect16. The sealing means51 is constructed from a material and is formed in such a manner as to resist the passage of fluids and other materials around sealing means51 and through thedefect16. The sealing means51 can be constructed from one or any number of a variety of materials including, but not limited to PTFE, e-PTFE, Nylon™, Marlex™, 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).
• The enlarging means53 can be sized to fit withincavity17 of sealing means51. It is preferably a single object of a dimension that can be inserted through thesame defect16 through which the sealing means51 was passed. The enlarging means53 can expand the sealing means51 to an expanded state as it is passed intocavity17. One purpose of enlargingmeans53 is to expand sealing means51 to a size greater than that of thedefect16 such that the assembledbarrier12 prevents passage of material through thedefect16. Theenlarger53 can further impart stiffness to thebarrier12 such that thebarrier12 resists the pressures withinnucleus pulposus20 and expulsion through thedefect16. The enlarging means53 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 fillingcavity17 within sealing means51.
• The sealing means51, enlargingmeans53, or the barrier means12 constructs can further be affixed to tissues either surrounding thedefect16 or remote from thedefect16. In the preferred embodiment, no aspect of a fixation means or fixation device or the barrier means12 nor its components extend posterior to thedisc15 or into theextradiscal region500, avoiding the risk of contacting and irritating the sensitive nerve tissues posterior to thedisc15.
• In a preferred embodiment, the sealing means51 is inserted into thedisc15 proximate theinterior aspect36 of the defect. The sealing means51 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 meanscavity17 as depicted inFIGS. 19 and 20. Afixation delivery instrument110 is delivered intocavity17 throughopening8 in the sealing means51.Fixation devices14 can then be deployed through a wall of the sealing means53 into surrounding tissues. Once the fixation means14 have been passed into surrounding tissue, thefixation delivery instrument110 can be removed from thedisc15. This method eliminates the need for a separate entryway into thedisc15 for delivery of fixation means14. It further minimizes the risk of material leaking through sealing means51 proximate to the fixation means14. One or more fixation means14 can be delivered into one or any number of surrounding tissues including the superior95 and inferior95′ vertebral bodies. Following fixation of the sealing means51, the enlarging means53 can be inserted intocavity17 of the sealing means51 to further expand the barrier means12 construct as well as increase its stiffness, as depicted inFIGS. 21A and 21B. Theopening8 into the sealing means51 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 means51 is achieved.
• Another method of securing thebarrier12 to tissues is to affix the enlarging means53 to tissues either surrounding or remote from thedefect16. The enlarging means53 can have anintegral fixation region4 that facilitates securing it to tissues as depicted inFIGS. 22A,22B,32A and43B. Thisfixation region4 can extend exterior to sealing means51 either throughopening8 or through a separate opening.Fixation region4 can have a hole through which a fixation means orfixation device14 can be passed. In a preferred embodiment, thebarrier12 is affixed to at least one of the surrounding vertebral bodies (95 and95′) proximate to the defect using abone anchor14′. Thebone anchor14′ can be deployed into thevertebral bodies50,50′ at some angle between 0° and 180° relative to a bone anchor deployment tool. As shown thebone anchor14′ is mounted at 90° relative to the bone anchor deployment tool. Alternatively, the enlarging means53 itself can have anintegral fixation device14 located at a site or sites along its length.
• Another method of securing the barrier means12 is to insert the barrier means12 through thedefect16 or another opening into thedisc15, position it proximate to theinterior aspect36 of thedefect16, and pass at least one fixation means14 through theanulus10 and into thebarrier12. In a preferred embodiment of this method, the fixation means14 can bedarts15 and are first passed partially intoanulus10 within afixation device120, such as a hollow needle. As depicted inFIGS. 23A and 23B, fixation means25 can be advanced into the barrier means12 andfixation device120 removed. Fixation means25 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 thebarrier12 andanulus fibrosis10 without any aspect of fixation means25 exterior to the disc in theextradiscal region500.
• In several embodiments of the present invention, the barrier (or “patch”)12 can be placed between twoneighboring layers33,37 (lamellae) of theanulus10 on either or both sides of thedefect16 as depicted inFIGS. 24A and 24B.FIG. 24A shows an axial view while24B shows a sagittal cross section. Such positioning spans thedefect16. The barrier means12 can be secured using the methods outlined.
• A dissecting tool can be used to form an opening extending circumferentially31 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 ofdefect16,annulotomy416, access hole417 or opening in the anulus. This process can make use of the naturally layered structure in the anulus in whichadjacent layers33,37 are defined by acircumferentially extending boundary35 between the layers.
• Another embodiment of thebarrier12 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. Abarrier12 having a length greater than its height is illustrated inFIG. 25. Thebarrier12 can be positioned across thedefect16 as well as the entirety of the posterior aspect of theanulus fibrosis10. Such dimensions of thebarrier12 can help to prevent thebarrier12 from slipping after insertion and can aid in distributing the pressure of thenucleus20 evenly along the posterior aspect of theanulus10.
• Thebarrier12 can be used in conjunction with anaugmentation device11 inserted within theanulus10. Theaugmentation device11 can includeseparate augmentation devices42 as shown inFIG. 26. Theaugmentation device11 can also be asingle augmentation device44 and can form part of thebarrier12 asbarrier region300, coiled within theanulus fibrosis10, as shown inFIG. 27. Either thebarrier12 orbarrier region300 can be secured to the tissues surrounding thedefect16 by fixation devices ordarts25, or be left unconstrained
• In another embodiment of the present invention, the barrier orpatch12 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 inFIG. 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 inFIGS. 27,28A and28B, the augmentation portion may comprise a length of elastic material that can be inserted linearly through a defect in the anulus. Aregion300 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 region300 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.
• FIGS. 28A and 28B illustrate axial and sagittal sections, respectively, of an alternate configuration of anaugmentation device38. In this embodiment,barrier region300 extends across thedefect16 and hasfixation region4 facilitating fixation of thedevice13 to superiorvertebral body50 withanchor14′.
• FIGS. 29A-D illustrate the deployment of abarrier12 from anentry site800 remote from the defect in theanulus fibrosis10.FIG. 29A showsinsertion instrument130 with a distal end positioned within the disc space occupied bynucleus pulposus20.FIG. 29B depictsdelivery catheter140 exiting the distal end ofinsertion instrument130 withbarrier12 on its distal end.Barrier12 is positioned across the interior aspect of thedefect16.FIG. 29C depicts the use of anexpandable barrier12′ whereindelivery catheter140 is used to expand thebarrier12′ withballoon150 on its distal end.Balloon150 may exploit heat to further adherebarrier12′ to surrounding tissue.FIG. 29D depicts removal ofballoon150 anddelivery catheter140 from the disc space leaving expanded barrier means12′ positioned acrossdefect16.
• Another method of securing the barrier means12 is to adhere it to surrounding tissues through the application of heat. In this embodiment, the barrier means12 includes a sealing means51 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 means51 can further comprise a separate structural material that adds strength to the thermally adherent material, such as a woven Nylon™ or Marlex™. This thermally adherent sealing means preferably has aninterior cavity17 and at least oneopening8 leading from the exterior of the barrier means intocavity17. A thermal device can be attached to the insertion instrument shown inFIGS. 29C and 29D. Theinsertion instrument130 having a thermal device can be inserted intocavity17 and used to heat sealing means51 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 aballoon150,150′, as shown inFIG. 47, capable of both heating and expanding the barrier means.Balloon150,150′ can either be inflated with a heated fluid or have electrodes located about its surface to heat the barrier means with RF energy.Balloon150,150′ 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 enlargingmeans53 can also be an integral component ofbarrier12 inserted within sealing means51. After the application of heat, a separate enlargingmeans53 can be inserted into the interior cavity of the barrier means to either enlarge thebarrier12 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.
• The barrier means12 shown inFIG. 25 preferably has a primary curvature or gentle curve along the length of the patch orbarrier12 that allows it to conform to the inner circumference of theAF10. This curvature may have a single radius R as shown inFIGS. 44A and 44B or may have multiple curvatures. The curvature can be fabricated into thebarrier12 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.
• The cross section of thebarrier12 can be any of a number of shapes. Each embodiment exploits a sealing means51 and an enlargingmeans53 that may further add stiffness to the overall barrier construct.FIGS. 30A and 30B show an elongated cylindrical embodiment with enlargingmeans53 located about the long axis of the device.FIGS. 31A and 31B depict a barrier means comprising an enlargingmeans53 with acentral cavity49.FIGS. 32A and 32B depict a barrier means comprising a non-axisymmetric sealing means51. In use, the longer section of sealing means51 as seen on the left side of this figure would extend between opposingvertebra50 and50′.FIGS. 33A and 33B depict a barrier means comprising a non-axisymmetric sealing means51 andenlarger53. The concave portion of the barrier means preferably faces nucleus pulposus20 while the convex surface faces thedefect16,annulotomy416, or access hole417 and the inner aspect of theanulus fibrosis10. This embodiment exploits pressure within the disc to compress sealing means51 against neighboringvertebral bodies50 and50′ to aid in sealing. The ‘C’ shape as shown inFIG. 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 orpatch12 serves to partially encapsulate thenucleus puposus20 by conforming to the gross morphology of the inner surface of theanulus10 and presenting a concave or cupping surface toward thenucleus20. 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.
• FIGS. 34 through 41 depict various enlarging orexpansion devices53 that can be employed to aid in expanding asealing element51 within theintervertebral disc15. Each embodiment can be covered by, coated with, or cover the sealingelement51. The sealing means51 can further be woven through the expansion means53. The sealingelement51 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.
• FIGS. 34 through 38 depict alternative patterns to that illustrated inFIG. 33A.FIG. 33A shows theexpansion devices53 within the sealing means51. The sealing means can alternatively be secured to one or another face (concave or convex) of the expansion means53. This can have advantages in reducing the overall volume of the barrier means12, simplifying insertion through a narrow cannula. It can also allow the barrier means12 to induce ingrowth of tissue on one face and not the other. The sealing means51 can be formed from a material that resists ingrowth such as expanded polytetraflouroethylene (e-PTFE). The expansion means53 can be constructed of a metal or polymer that encourages ingrowth. In several embodiments, if the e-PTFE sealing means51 is secured to the concave face of the expansion means53, tissue can grow into the expansion means53 from outside of thedisc15, helping to secure the barrier means12 in place and seal against egress of materials from within thedisc15.
• The expansion means53 shown inFIG. 33A can be inserted into the sealing means51 once the sealing means51 is within thedisc15. Alternatively, the expansion means53 and sealing means51 can be integral components of the barrier means12 that can be inserted as a unit into the disc.
• The patterns shown inFIGS. 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 means51 and surrounding vertebral endplates. The pattern may be Wire Electro-Discharge Machined, cut by laser, chemically etched, or formed by other suitable means.
• FIG. 34 shows an embodiment of anon-axisymmetric expander153 having asuperior edge166 and aninferior edge168. Theexpander153 can form a frame ofbarrier12. This embodiment comprises dissecting surfaces or ends160, radial elements orfingers162 and acentral strut164. The circular shape of the dissecting ends160 aids in dissecting through thenucleus pulposus20 and/or along or between an inner surface of theanulus fibrosis10. The distance between the left-most and right-most points on the dissecting ends is the expansion meanslength170. Thislength170 preferably lies along the inner perimeter of the posterior anulus following implantation. Theexpander length170 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 ends160 is preferably similar to or larger than the posterior disc height.
• This embodiment employs a multitude offingers162 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 meansheight172. Thisheight172 is preferably greater than the disc height at the inner surface of the posterior anulus. Thegreater height172 of theexpander153 allows thefingers162 to deflect along the superior and inferior vertebral endplates, enhancing the seal of the barrier means12 against egress of material from within thedisc15.
• The spacing between thefingers162 along theexpander length170 can be tailored to provide a desired stiffness of the expansion means153. Greater spacing between any two neighboringfingers162 can further be employed to insure that thefingers170 do not touch if the expansion means153 is required to take a bend along its length. Thecentral strut164 can connect the fingers and dissecting ends and preferably lies along the inner surface of theanulus10 when seated within thedisc15. Various embodiments may employstruts164 of greater or lesser heights and thicknesses to vary the stiffness of the overall expansion means153 along itslength170 andheight172.
• FIG. 35 depicts an alternative embodiment to theexpander153 ofFIG. 34. Openings orslots174 can be included along thecentral strut164. Theseslots174 promote bending of theexpander153 andfingers162 along a central line176 connecting the centers of the dissecting ends160. Such central flexibility has been found to aid against superior or inferior migration of the barrier means orbarrier12 when thebarrier12 has not been secured to surrounding tissues.
• FIGS. 34B and 34C depict different perspective views of a preferred embodiment of the expander/frame153 within anintervertebral disc15.Expander53 is in its expanded condition and lies along and/or within theposterior wall21 and extends around thelateral walls23 of theanulus fibrosis10. The superior166 and inferior168 facingfingers162 ofexpander153 extend along the vertebral endplates (not shown) and/or the cartilage overlying the endplates. Theframe153 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 thenucleus pulposus20.
• The bending stiffness ofexpander153 can resist migration of the implant from this preferred position within thedisc15. The principle behind this stiffness-based stability is to place the regions ofexpander153 with the greatest flexibility in the regions of thedisc153 with the greatest mobility or curvature. These flexible regions ofexpander153 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.
• For example, in order forexpander153 ofFIG. 34B to move around the inner circumference of anulus fibrosis10 (e.g., from theposterior wall21 onto the lateral23 and/or anterior27 wall), the stiff central region ofexpander153 spanning theposterior wall21 would have to bend around the acute curves of the posterior lateral corners ofanulus10. The stiffer this section ofexpander153 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 offingers162 away from the vertebral endplates: Theslots174 cut along the length ofexpander153 create a central flexibility that encouragesexpander153 to bend along an axis running through these slots as the posterior disc height increases and decreased during flexion and extension. In order for thefingers162 to migrate away from the endplate, this central flexible region must move away from theposterior anulus21 and toward an endplate. This motion is resisted by the greater stiffness ofexpander153 in the areas directly inferior and superior to this central flexible region.
• Theexpander153 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.
• FIG. 36 depicts an embodiment of theexpander153 ofFIG. 33A with an enlargedcentral strut164 and a plurality ofslots174. Thiscentral strut164 can have a uniform stiffness against superior-inferior166 and168 bending as shown in this embodiment. Thestrut164 can alternatively have a varying stiffness along itsheight178 to either promote or resist bending at a given location along the inner surface of theanulus10.
• FIGS. 37A-C depict a further embodiment of the frame orexpander153. This embodiment employs acentral lattice180 consisting of multiple, fineinterconnected struts182. Such alattice180 can provide a structure that minimizes bulging of the sealing means51 under intradiscal pressures. The orientation and location of thesestruts182 have been designed to give the barrier12 a bend-axis along the central area of theexpander height172. Thestruts182 support inferior168 and superior166fingers162 similar to previously described embodiments. However, thesefingers162 can have varying dimensions and stiffness along the length of thebarrier12.Such fingers162 can be useful for helping thesealer51 conform to uneven endplate geometries.FIG. 37B illustrates thecurved cross section184 of theexpander153 ofFIG. 37A. Thiscurve184 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 theexpander153 ofFIGS. 37A and 37B.
• The embodiment of theframe153 as shown inFIGS. 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 inFIGS. 37A-37C is between about 0.05 mm²(7.75×10⁻⁵in²) and about 0.75 mm²(1.16×10⁻³in²), 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 mm²(2.33×10⁻⁴in²). 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.
• FIG. 38 depicts anexpander153 similar to that ofFIG. 37A without fingers. Theexpander153 includes acentral lattice180 consisting ofmultiple struts182.
• FIGS. 39 through 41 depict another embodiment of theexpander153 of some embodiments of the present invention. These tubular expanders can be used in thebarrier12 embodiment depicted inFIG. 31A. Thesealer51 can cover theexpander153 as shown inFIG. 31A. Alternatively, thesealer51 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.
• FIG. 39 depicts an embodiment of atubular expander154. The superior166 andinferior surfaces168 of thetubular expander154 can deploy against the superior and inferior vertebral endplates, respectively. Thedistance186 between the superior166 and inferior168 surfaces of theexpander154 are preferably equal to or greater than the posterior disc height at the inner surface of theanulus10. This embodiment has ananulus face188 and nucleus face190 as shown inFIGS. 39B,39C and39D. Theanulus face188 can be covered by thesealer51 from the superior166 to inferior168 surface of theexpander154. Thisface188 lies against the inner surface of theanulus10 in its deployed position and can prevent egress of materials from within thedisc15. The primary purpose of thenucleus face190 is to prevent migration of theexpander154 within thedisc15. Thestruts192 that form thenucleus face190 can project anteriorly into thenucleus20 when thebarrier12 is positioned across the posterior wall of theanulus10. This anterior projection can resist rotation of the tubular expansion means154 about its long axis. By interacting with thenucleus20, thestruts192 can further prevent migration around the circumference of thedisc15.
• Thestruts192 can be spaced to providenuclear gaps194. Thesegaps194 can encourage the flow ofnucleus pulposus20 into the interior of theexpander154. This flow can insure full expansion of thebarrier12 within thedisc15 during deployment.
• The embodiments ofFIGS. 39,40 and41 vary by their cross-sectional shape.FIG. 39 has acircular cross section196 as seen inFIG. 39C. If the superior-inferior height186 of theexpander154 is greater than that of thedisc15, thiscircular cross section196 can deform into an oval when deployed, as the endplates of the vertebrae compress theexpander154. The embodiment of theexpander154 shown inFIG. 40 is preformed into anoval shape198 shown inFIG. 40C. Compression by the endplates can exaggerate theunstrained oval198. This oval198 can provide greater stability against rotation about a long axis of theexpander154. The embodiment ofFIGS. 41B,41C and41D depict an ‘egg-shaped’cross section202, as shown inFIG. 41C, that can allow congruity between the curvature of theexpander154 and the inner wall ofposterior anulus10. 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.
• FIGS. 40E,40F, and401 depict theexpander154 ofFIGS. 40A-D having a sealing means51 covering the exterior surface of theanulus face188. This sealing means51 can be held against the endplates and the inner surface of the posterior anulus by theexpander154 in its deployed state.
• FIGS. 40G and 40H depict theexpander154 ofFIG. 40B with asealer51 covering the interior surface of theanulus face188. This position of thesealer51 can allow theexpander154 to contact both the vertebral endplates and inner surface of the posterior anulus. This can promote ingrowth of tissue into theexpander154 from outside thedisc15. Combinations ofsealer51 that cover all or part of theexpander154 can also be employed without deviating from the scope of the present invention. Theexpander154 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.
• FIGS. 42A-D depict cross sections of a preferred embodiment of sealing means51 and enlargingmeans53. Sealing means51 hasinternal cavity17 andopening8 leading from its outer surface intointernal cavity17.Enlarger53 can be inserted throughopening8 and intointernal cavity17.
• FIGS. 43A and 43B depict an alternative configuration ofenlarger53.Fixation region4 extends throughopening8 in sealing means51.Fixation region4 has a through-hole that can facilitate fixation ofenlarger53 totissues surrounding defect16.
• FIGS. 44A and 44B depict an alternative shape of the barrier. In this embodiment, sealing means51,enlarger53, 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 ofanulus fibrosis10.
• FIG. 45 is a section of a device used to affix sealing means51 to tissues surrounding a defect. In this figure, sealing means51 would be positioned acrossinterior aspect50 ofdefect16. The distal end ofdevice110′ would be inserted throughdefect16 andopening8 into theinterior cavity17. On the right side of this figure,fixation dart25 has been passed fromdevice110′, through a wall of sealing means51 and into tissues surrounding sealing means51. On the right side of the figure,fixation dart25 is about to be passed through a wall of sealing means51 by advancingpusher111 relative todevice110′ in the direction of the arrow.
• FIG. 46 depicts the use ofthermal device200 to heat sealing means51 and adhere it to tissues surrounding a defect. In this figure, sealing means51 would be positioned across theinterior aspect36 of adefect16. The distal end ofthermal device200 would be inserted through the defect andopening8 intointerior cavity17. In this embodiment,thermal device200 employs at its distal endresistive heating element210 connected to a voltage source bywires220. Covering230 is a non-stick surface such as Teflon tubing that ensures the ability to removedevice200 frominterior cavity17. In this embodiment,device200 would be used to heat first one half, and then the other half of sealing means51.
• FIG. 47 depicts an expandable thermal element, such as a balloon, that can be used to adhere sealing means51 to tissues surrounding a defect. As inFIG. 18, the distal end ofdevice130 can be inserted through the defect andopening8 intointerior cavity17, withballoon150′ on thedistal end device130 in a collapsed state.Balloon150′ is then inflated to expandedstate150, expanding sealing means51.Expanded balloon150 can heat sealing means51 and surrounding tissues by inflating it with a heated fluid or by employing RF electrodes. In this embodiment,device130 can be used to expand and heat first one half, then the other half of sealing means51.
• FIG. 48 depicts an alternative embodiment todevice130. This device employs an elongated,flexible balloon150′ that can be inserted into and completely fillinternal cavity17 of sealing means51 prior to inflation to an expandedstate150. Using this embodiment, inflation and heating of sealing means51 can be performed in one step.
• FIGS. 49A through 49G illustrate a method of implanting an intradiscal implant. An intradiscal implant system consists of anintradiscal implant400, a delivery device orcannula402, anadvancer404 and at least onecontrol filament406. Theintradiscal implant400 is loaded into thedelivery cannula402 which has aproximal end408 and adistal end410.FIG. 49A illustrates thedistal end410 advanced into thedisc15 through anannulotomy416. Thisannulotomy416 can be through any portion of theanulus10, but is preferably at a site proximate to a desired, final implant location. Theimplant400 is then pushed into thedisc15 through thedistal end410 of thecannula402 in a direction that is generally away from the desired, final implant location as shown inFIG. 49B. Once theimplant400 is completely outside of thedelivery cannula402 and within thedisc15, theimplant400 can be pulled into the desired implant location by pulling on thecontrol filament406 as shown inFIG. 49C. Thecontrol filament406 can be secured to theimplant400 at any location on or within theimplant400, but is preferably secured at least at asite414 or sites on adistal portion412 of theimplant400, e.g., that portion that first exits thedelivery cannula402 when advanced into thedisc15. These site orsites414 are generally furthest from the desired, final implant location once the implant has been fully expelled from the interior of thedelivery cannula402.
• Pulling on thecontrol filament406 causes theimplant400 to move toward theannulotomy416. Thedistal end410 of thedelivery cannula402 can be used to direct theproximal end420 of the implant400 (that portion of theimplant400 that is last to be expelled from the delivery cannula402) away from theannulotomy416 and toward an inner aspect of theanulus10 nearest the desired implant location. Alternately, the advancer404 can be used to position the proximal end of the implant toward an inner aspect of theanulus20 near the implant location, as shown inFIG. 49E. Further pulling on thecontrol filament406 causes theproximal end426 of theimplant400 to dissect along the inner aspect of theanulus20 until theattachment site414 or sites of theguide filament406 to theimplant400 has been pulled to the inner aspect of theannulotomy416, as shown inFIG. 49D. In this way, theimplant400 will extend at least from theannulotomy416 and along the inner aspect of theanulus10 in the desired implant location, illustrated inFIG. 49F.
• Theimplant400 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. Theimplant400 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. Theimplant400 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. Theimplant400 can either resist or promote tissue ingrowth, whether fibrous or bony.
• Thecannula402 can be any tubular device capable of advancing theimplant400 at least partially through theanulus10. 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 itsdistal end410, but can have other openings in various locations along its length.
• The advancer404 can be rigid or flexible, and have one of a variety of cross sectional shapes either like or unlike thedelivery cannula402. It may be a solid or even a column of incompressible fluid, so long as it is stiff enough to advance theimplant400 into thedisc15. The advancer404 can be contained entirely within thecannula402 or can extend through a wall or end of the cannula to facilitate manipulation.
• Advancement of theimplant400 can be assisted by various levers, gears, screws and other secondary assist devices to minimize the force required by the surgeon to advance theimplant400. These secondary devices can further give the user greater control over the rate and extent of advancement into thedisc15.
• Theguide filament406 may be a string, rod, plate, or other elongate object that can be secured to and move with theimplant400 as it is advanced into thedisc15. 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 asecondary object418 or device at its end opposite that which is secured to theimplant400. Thissecondary device418 can include the advancer404 or other object or device that assists the user in manipulating the filament. Thefilament406 can be releasably secured to theimplant400, as shown inFIG. 49G or permanently affixed. Thefilament406 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 theimplant400. It may be bonded to theimplant400 using adhesive, welding, or a secondary securing means such as a screw, staple, dart, etc. Thefilament406 can further be an elongate extension of the implant material itself. If not removed following placement of the implant, thefilament406 can be used to secure theimplant400 to surrounding tissues such as the neighboringanulus10, vertebral endplates, or vertebral bodies either directly or through the use of a dart, screw, staple, or other suitable anchor.
• Multiple guide filaments can be secured to theimplant400 at various locations. In one preferred embodiment, a first or distal422 and a second or proximal424 guide filament are secured to anelongate implant400 at or near its distal412 and proximal420 ends atattachment sites426 and428, respectively. These ends412 and420 correspond to the first and last portions of theimplant400, respectively, to be expelled from thedelivery cannula402 when advanced into thedisc15. This double guide filament system allows theimplant400 to be positioned in the same manner described above in the single filament technique, and illustrated inFIGS. 50A-C. However, following completion of this first technique, the user may advance theproximal end420 of thedevice400 across theannulotomy416 by pulling on thesecond guide filament424, shown inFIG. 50D. This allows the user to controllably cover theannulotomy416. This has numerous advantages in various implantation procedures. This step may reduce the risk of herniation of either nucleus pulposus20 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.
• Both the first422 and second424 guide filaments can be simultaneously tensioned, as shown inFIG. 50E, to ensure proper positioning of theimplant400 within theanulus10. Once theimplant400 is placed across the annulotomy, the first422 and second424 guide filaments can be removed from theinput400, as shown inFIG. 50F. Additional control filaments and securing sites may further assist implantation and/or fixation of the intradiscal implants.
• In another embodiment of the present invention, as illustrated inFIGS. 51A-C, animplant guide430 may be employed to aid directing theimplant400 through theannulotomy416, through thenucleus pulposus10, and/or along the inner aspect of theanulus10. Thisimplant guide430 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. Theimplant guide430 can be affixed to either the advancer404 or theimplant406 themselves. In a preferred embodiment shown inFIGS. 52A and 52B, theimplant guide430 is secured to theimplant400 by the first424 and second426 guide filaments of the first426 and the second428 attachment sites, respectively. Theguide filaments424 and426 may pass through or around theimplant guide430. In this embodiment, theimplant guide430 may be a thin, flat sheet of biocompatible metal with holes passing through its surface proximate to the site orsites426 and428 at which theguide filaments422 and424 are secured to theimplant400. These holes allow passage of the securingfilament422 and424 through theimplant guide430. Such an elongated sheet may run along theimplant400 and extend beyond itsdistal end412. The distal end of theimplant guide430 may be shaped to help dissect through thenucleus10 and deflect off of theanulus10 as theimplant400 is advanced into thedisc15. When used with multiple guide filaments, such animplant guide430 can be used to control rotational stability of theimplant400. It may also be used to retract theimplant400 from thedisc15 should this become necessary. Theimplant guide430 may also extend beyond theproximal tip420 of theimplant400 to aid in dissecting across or through theanulus10 proximate to the desired implantation site.
• Theimplant guide430 is releasable from theimplant400 following or during implantation. This release may be coordinated with the release of theguide filaments422 and424. Theimplant guide430 may further be able to slide along theguide filaments422 and424 while these filaments are secured to theimplant400.
• Various embodiments of thebarrier12 orimplant400 can be secured to tissues within theintervertebral disc15 or surrounding vertebrae. It can be advantageous to secure the barrier means12 in a limited number of sites while still insuring that larger surfaces of thebarrier12 or implant juxtapose the tissue to which thebarrier12 is secured. This is particularly advantageous in forming a sealing engagement with surrounding tissues.
• FIGS. 53-57 illustratebarriers12 havingstiffening elements300. Thebarrier12 can incorporate stiffeningelements300 that run along a length of the implant required to be in sealing engagement. These stiffeningelements300 can be one of a variety of shapes including, but not limited to,plates302,rods304, or coils. These elements are preferably stiffer than the surroundingbarrier12 and can impart their stiffness to the surrounding barrier. These stiffeningelements300 can be located within an interior cavity formed by the barrier. They can further be imbedded in or secured to thebarrier12.
• Each stiffening element can aid in securing segments of thebarrier12 to surrounding tissues. The stiffening elements can have parts307, including through-holes, notches, or other indentations for example, to facilitate fixation of thestiffening element300 to surrounding tissues by any of a variety offixation devices306. Thesefixation devices306 can include screws, darts, dowels, or other suitable means capable of holding thebarrier12 to surrounding tissue. Thefixation devices306 can be connected either directly to thestiffening element300 or indirectly using an intervening length of suture, cable, or other filament for example. Thefixation device306 can further be secured to thebarrier12 near thestiffening element300 without direct contact with thestiffening element300.
• Thefixation device306 can be secured to or near thestiffening element300 at opposing ends of the length of thebarrier12 required to be in sealing engagement with surrounding tissues. Alternatively, one or a multitude offixation devices306 can be secured to or near thestiffening element300 at a readily accessible location that may not be at these ends. In anybarrier12 embodiment with aninterior cavity17 and anopening8 leading thereto, the fixation sites may be proximal to theopening8 to allow passage of thefixation device306 and various instruments that may be required for their implantation.
• FIGS. 53A and 53B illustrate one embodiment of abarrier12 incorporating the use of astiffening element300. Thebarrier12 can be a plate andscrew barrier320. In this embodiment, thestiffening element300 consists of two fixation plates, superior310 and inferior312, an example of which is illustrated inFIGS. 54A and 54B with twoparts308 passing through each plate. Theparts308 are located proximal to anopening8 leading into aninterior cavity17 of thebarrier12. Theseparts8 allow passage of afixation device306 such as a bone screw. These screws can be used to secure the barrier means12 to a superior50 and inferior50′ vertebra. As the screws are tightened against the vertebral endplate, thefixation plates310,312 compress the intervening sealing means against the endplate along the superior and inferior surfaces of thebarrier12. This can aid in creating a sealing engagement with the vertebral endplates and prevent egress of materials from within thedisc15. As illustrated inFIGS. 53A and 53B, only the superior screws have been placed in thesuperior plate310, creating a sealing engagement with the superior vertebra.
• FIGS. 55A and 55B illustrate another embodiment of abarrier12 havingstiffening elements300. Thebarrier12 can be an anchor androd barrier322. In this embodiment, the stiffeningelements300 consist of twofixation rods304, an example of which is shown inFIGS. 56A and 56B, imbedded within thebarrier12. Therods304 can include asuperior rod314 and aninferior rod316.Sutures318 can be passed around theserods314 and316 and through the barrier means10. Thesesutures318 can in turn, be secured to a bone anchor or othersuitable fixation device306 to draw thebarrier12 into sealing engagement with the superior and inferior vertebral endplates in a manner similar to that described above. Theopening8 andinterior cavity17 of thebarrier12 are not required elements of thebarrier12.
• FIG. 57 illustrates the anchor androd barrier322, described above, withfixation devices306 placed at opposing ends of eachfixation rod316 and318. Thesuture18 on the left side of thesuperior rod318 has yet to be tied.
• Various methods may be employed to decrease the forces necessary to maneuver thebarrier12 into a position along or within the lamellae of theanulus fibrosis10.FIGS. 58A,58B,59A and59B depict two preferred methods of clearing a path for thebarrier12.
• FIGS. 58A and 58B depict one such method and an associateddissector device454. In these figures, the assumed desired position of the implant is along theposterior anulus452. In order to clear a path for the implant, ahairpin dissector454 can be passed along the intended implantation site of the implant. Thehairpin dissector454 can have ahairpin dissector component460 having afree end458. The dissector can also have an advancer464 to position thedissector component460 within thedisc15. Thedissector454 can be inserted throughcannula456 into anopening462 in theanulus10 along an access path directed anteriorly or anterior-medially. Once a free-end458 of thedissector component460 is within thedisc15, the free-end458 moves slightly causing the hairpin to open, such that thedissector component460 resists returning into thecannula456. Thisopening462 can be caused by pre-forming the dissector to the opened state. Thehairpin dissector component460 can then be pulled posteriorly, causing thedissector component460 to open, further driving the free-end458 along theposterior anulus458. This motion clears a path for the insertion of any of the implants disclosed in the present invention. The body ofdissector component460 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.
• FIGS. 59A and 59B depict another method and associateddissector device466 suitable for clearing a path for implant insertion. Thedissector device466 is shown in cross section and consists of adissector component468, anouter cannula470 and an advancer orinner push rod472. A curved passage orslot474 is formed into anintradiscal tip476 ofouter cannula470. This passage or slot474 acts to deflect the tip ofdissector component468 in a path that is roughly parallel to the lamellae of theanulus fibrosis10 as thedissector component468 is advanced into thedisc15 by the advancer. Thedissector component468 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. Thedissector component468 can be formed from an elongated sheet, rods, wires or the like. It can be used to dissect between theanulus10 andnucleus20, or to dissect between layers of theanulus10.
• FIGS. 60A-C depict analternate dissector component480 ofFIGS. 59A and 59B. Only theintradiscal tip476 ofdevice460 and regions proximal thereto are shown in these figures. A push-rod472 similar to that shown inFIG. 59A can be employed to advancedissector480 into thedisc15.Dissector480 can include anelongated sheet482 with superiorly and inferiorly extending blades (or “wings”)484 and486, respectively. Thissheet482 is preferably formed from a metal with a large elastic strain range such as spring steel or nickel titanium alloy. Thesheet482 can have aproximal end488 and adistal end490. Thedistal end490 can have a flat portion which can be flexible. Astep portion494 can be located between thedistal end490 and theproximal end488. Theproximal end488 can have a curved shape. The proximal end can also includeblades484 and486.
• In the undeployed state depicted inFIGS. 60A and 60B,wings484 and486 are collapsed withinouter cannula470 whileelongated sheet482 is captured within deflecting passage orslot474. As thedissector component480 is advanced into adisc15, passage or slot478 directs thedissector component480 in a direction roughly parallel to the posterior anulus (90 degrees to the central axis ofsleeve470 in this case) in a manner similar to that described for the embodiment inFIGS. 59A and 59B.Wings484 and486 open as they exit the end ofsleeve470 and expand toward the vertebral endplates. Further advancement ofdissector component480 allows the expandedwings484 and486 to dissect through any connections ofnucleus20 oranulus10 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 ofdissector component480 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.
• FIGS. 61A-61D illustrate a method of implanting a disc implant. Adisc implant552 is inserted into adelivery device550. Thedelivery device550 has aproximal end556 and adistal end558. Thedistal end558 of thedelivery device550 is inserted into an annulotomy illustrated inFIG. 61A. The annulotomy is preferably located at a site within theanulus10 that is proximate to a desired,final implant552 location. Theimplant400 is then deployed by being inserted into thedisc15 through thedistal end558 of thedelivery device550. Preferably the implant is forced away from the final implant location, as shown inFIG. 61B. Animplant guide560 can be used to position theimplant400. Before, during or after deployment of theimplant400, anaugmentation material7 can be injected into thedisc15. Injection of augmentation after deployment is illustrated inFIG. 61C. Theaugmentation material7 can include a hydrogel or collagen, for example. In one embodiment, thedelivery device550 is removed from thedisc15 and a separate tube is inserted into the annulotomy to inject theflowable augmentation material7. Alternately, thedistal end558 of thedelivery device550 can remain within the annulotomy and thefluid augmentation material554 injected through thedelivery device550. Next, thedelivery device550 is removed from the annulotomy and theintradiscal implant400 is positioned over the annulotomy in the final implant location, as shown inFIG. 61D. Theimplant400 can be positioned using control filaments described above.
• Certain embodiments, as shown inFIGS. 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 materials7 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 thenucleus20 oraugmentation materials7 to healthier portions of theanulus10 or endplates. With the barrier-type anulus augmentation12 in place, as embodied in various aspects of the present invention,nuclear augmentation materials7 or devices can conform to healthy regions of theanulus10 while thebarrier12 shields weaker regions of theanulus10. Indeed, theanulus augmentation devices12 of several embodiments of the present invention are particularly advantageous because they enable the use of certain nuclear augmentation materials anddevices7 that may otherwise be undesirable in a disc with an injured anulus.
• FIG. 62 is a cross-sectional transverse view of ananulus barrier device12 implanted within adisc15 along the inner surface of alamella16. Implanted conformablenuclear augmentation7 is also shown in contact with thebarrier12. Thebarrier device12 is juxtapositioned to the innermost lamella of the anulus. Conformablenuclear augmentation material7 is inserted into the cavity which is closed by thebarrier12, in an amount sufficient to fill the disc space in an unloaded supine position. As shown, in one embodiment, fluidnuclear augmentation554, such as hyaluronic acid, is used.
• Fluidnuclear augmentation554 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. Fluidnuclear augmentation554 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, fluidnuclear augmentation materials554 used alone may perform poorly indiscs15 with a degenerated anulus because the material can flow back out throughanulus defects8 and pose a risk to surrounding structures. This limitation is overcome by several embodiments of the current invention because thebarrier12 shunts the pressure caused by thefluid augmentation554 away from the damagedanulus region8 and toward healthier regions, thus restoring function to thedisc15 and reducing risk of the extrusion ofnuclear augmentation materials7 andfluid augmentation material554.
• Exemplary fluidnuclear augmentation materials554 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.
• 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. Theaugmentation material554 may remain “fluid” after the infusion step, or may polymerize, cure, or otherwise harden to a less flowable or nonflowable state.
• Additional additives and components of the nucleus augmentation material are recited below. In general, the nature of thematerial554 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 thenucleus augmentation material554 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.
• FIG. 63 is a cross-sectional transverse view ofanulus barrier device12 implanted within adisc15 along an inner surface of alamella16. Implantednuclear augmentation7 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 devices7 may be formed from one or more materials, which are present in one or more phases.FIG. 63 shows a cylindrical flexible solid form ofnuclear augmentation7. 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.
• FIG. 63 depictsnuclear augmentation7 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 butdeformable augmentation materials7 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 theanulus10. Solidnuclear augmentation7 can also be sized substantially larger than theannulotomy416 ordefect8 to decrease the risk of extrusion. The use of solid materials ordevices7 alone is subject to certain limitations. The delivery ofsolid materials7 may require a large access hole417 in theanulus10, thereby decreasing the integrity of thedisc15 and creating a significant risk for extrusion of either theaugmentation material7 or ofnatural nucleus20 remaining within thedisc15. Solid materials ordevices7 can also overload the endplates causing endplate subsidence or apply point loads to theanulus10 from corners or edges that may cause pain or further deterioration of theanulus10. Several embodiments of the present invention overcome the limitations of solid materials and are particularly well-suited for use withliquid augmentation materials7. Thebarrier device12 of various embodiments of this invention effectively closes the access hole417 and can be adapted to partially encapsulate the augmented nucleus, thus mitigating the risks posed by solid materials.
• Solid or gelnuclear augmentation materials7 used in various embodiments of the current invention include single piece or multiple pieces. Thesolid materials7 may be cube-like, spheroid, disc-like, ellipsoid, rhombohedral, cylindrical, or amorphous in shape. Thesematerials7 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 materials7 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 orgel augmentation materials7 may be rigid, wholly or partially flexible, elastic or viscoelastic in nature. The augmentation device ormaterial7 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.
• In various embodiments of the present invention, the solid or gelnuclear augmentation material7, as depicted inFIG. 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 thenuclear augmentation material7. 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 theaugmentation material7 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 theanulus10 without resulting in complete fixation which might cause fusion and prohibit disc function.
• FIG. 64 is a cross-sectional transverse view ofanulus barrier device12 implanted within adisc15 along an inner surface of alamella16. Several types of implantednuclear augmentation7, including a solid cube, a composite cylindrical solid555, and a free flowing liquid554 are shown. The use of multiple types of nuclear augmentation with thebarrier12 is depicted inFIG. 64. Thebarrier device12 is shown in combination with fluidnuclear augmentation554, solidnuclear augmentation7, in the form of a cube, and a cross-linkedcollagen sponge composite555 soaked in a growth factor. In several embodiments of the present invention, a multiphase augmentation system, as shown inFIG. 64, is used. A combination of solids and liquids is used in a preferred embodiment.Nuclear augmentation7 comprising solids andliquids554 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 theanulus10 under excessive loading as thesolid augmentation7 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 across-linked collagen sponge555 soaked in a growth factor or combination of growth factors in liquid suspension.
• In one embodiment, the nuclear augmentation material ordevice7,554 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 oranulus augmentation device12 may be permanently implanted or used only temporarily until the desired phase change has occurred.
• In another embodiment, ananulus augmentation device12 that exploits the characteristics of nucleus augmentation devices or materials to improve its own performance is provided. Augmenting thenucleus20 pressurizes the intervertebral disc environment which can serve to fix or stabilize an anulus repair device in place. Thenucleus20 can be pressurized by inserting into thedisc15 an adequate amount ofaugmentation material7,554. In use, the pressurized disc tissue andaugmentation material7,554 applies force on the inwardly facing surface of theanulus augmentation device12. This pressure may be exploited by the design of the anulus prosthesis orbarrier12 to prevent it from dislodging or moving from its intended position. One exemplary method is to design the inwardly facing surface of theanulus prosthesis12 to expand upon the application of pressure. As theanulus prosthesis12 expands, it becomes less likely to be expelled from the disc. Theprosthesis12 may be formed with a concavity facing inward to promote such expansion.
• In several embodiments, theanulus augmentation device12 itself functions asnuclear augmentation7. In a preferred embodiment, thebarrier12 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.
• FIG. 65 depicts a sagittal cross-sectional view of the barrier device connected to an inflatablenuclear augmentation device455. Thebarrier device12 is shown connected via hollow delivery andsupport tube425 to annuclear augmentation sack455 suitable for containingfluid material554. Thetube425 has a delivery port orvalve450 that extends through the barrier device and can be accessed from the access hole417 after thebarrier device12 andaugmentation sack455 has been delivered. This nuclear and anulus augmentation combination is particularly advantageous because of the ease of deliverability, since thesack455 and thebarrier12 are readily compressed. The connection of thebarrier12 and theaugmentation sack455 also serves to stabilize the combination and prevent its extrusion from thedisc15. Thenuclear augmentation7 may be secured to theanulus augmentation prosthesis12 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 thenuclear prosthesis7 through theanulus prosthesis12 to the disc tissues. Thebarrier12 andaugmentation7 can be attached prior to, during, or after delivery of thebarrier12 into thedisc15. They may be secured to each other by an adhesive or by a flexible filament such as suture. Alternatively, thebarrier12 may have a surface facing theaugmentation material7 that bonds to theaugmentation material7 though a chemical reaction. This surface may additionally allow for a mechanical linkage to a surface of theaugmentation material7. This linkage could be achieved through a porous attachment surface of thebarrier12 that allows the inflow of afluid augmentation material7 that hardens or gels after implantation.
• Alternatively, theanulus augmentation device12 andnuclear augmentation material7 may be fabricated as a single device with abarrier12 region and anuclear augmentation region7. As an example, thebarrier12 may form at least a portion of the surface of anaugmentation sack455 or balloon. Thesack455 may be filled withsuitable augmentation materials7 once the barrier has been positioned along a weakened inner surface of theanulus10.
• The sequence of inserting thebarrier12 andnuclear augmentation7 in the disc can be varied according to thenuclear augmentation7 used or requirements of the surgical procedure. For example, thenuclear augmentation7 can be inserted first and then sealed in place by thebarrier device12. Alternatively, thedisc15 can be partially filled, then sealed with thebarrier device12, and then supplied withadditional material7. In a preferred embodiment, thebarrier device12 is inserted into thedisc15 followed by the addition ofnuclear augmentation material7 through or around thebarrier12. This allows for active pressurization. Adisc15 with a severely degenerated anulus can also be effectively treated in this manner.
• In an alternative embodiment, thenuclear augmentation material7 is delivered through a cannula inserted through an access hole417 in thedisc15 formed pathologically, e.g. ananular defect8, or iatrogenically, e.g. ananuulotomy416 that is distinct from the access hole417 that was used to implant thebarrier12. Also, the same or different surgical approach including transpsoas, presacral, transsacral, tranpedicular, translaminar, or anteriorly through the abdomen, may be used. Access hole417 can be located anywhere along the anulus surface or even through the vertebral endplates.
• In alternative embodiments, theanulus augmentation device12 includes features that facilitate the introduction ofaugmentation materials554 following placement. The augmentation delivery cannula may simply be forcibly driven into an access hole417 proximal to thebarrier12 at a slight angle so that the edge of thebarrier12 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 hole417 over (in the direction of the superior endplate) or under (in the direction of the inferior endplate) thebarrier12 or around an edge of thebarrier12 contiguous with theanulus15.
• In several embodiments, ports or valves are installed in thebarrier12 device that permit the flow of augmentation material into, but not out of, the disc space. One-way valves450 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 orports450 are present along thedevice12 to facilitate alignment with the access hole417 and delivery of augmentation material. Flow channels within or on thebarrier12 to direct the delivery of the material554 (e.g. to the ends of the barrier) can be machined, formed into or attached to thebarrier12 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.
• FIG. 66 is sagittal cross-sectional view of a functional spine unit containing thebarrier device unit12 connected to a wedge-shapednuclear augmentation7 device.FIG. 66 illustrates that the geometry of thenuclear augmentation7 can be adapted to improve the function of the barrier. By presentingnuclear augmentation7 with a wedge-shaped or hemicircular profile towards the interior of the intervertebral disc space, and attaching it in the middle of thebarrier device12 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 thedevice12. One skilled in the art will understand that thenuclear augmentation material7 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 theaugmentation7 to be either stiff at the interface with thebarrier12 and supple towards the center of the disc, or vice versa. Theaugmentation7 can also serve to rotationally stabilize thebarrier12. 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. Theaugmentation device7 of this embodiment can extend from the middle of thedisc15 to the opposite wall of the anulus.
• 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.
• 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.
• 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.
• 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™, 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.
• 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.
• 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.
• 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 mm². 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 mm²to about 0.75 mm²) 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.
• 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.
• 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).
• 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.
• 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.
• In one embodiment, as shown inFIG. 67, a mesh having a series ofcurvilinear elements602 is provided. In one embodiment, thecurvilinear elements602 are interconnected. One of skill in the art will understand that thecurvilinear elements602 can exist independently of each other, or only be partially connected. Theinterconnections602 can be distributed to form one or more contiguous horizontal bands, rails, members, struts, or axes604.FIG. 67 shows such a device with a centralhorizontal axis604 and “S” shapedcurvilinear elements602. In one embodiment, the “S” shapedelements602 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.
• In some embodiments, thecurvilinear elements602 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, thecurvilinear elements602 are substantially flat. Thecurvilinear elements602 can also be oriented at any angle (e.g., from about 1 degree to about 179 degrees) from the plane. Themesh600 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.
• FIG. 69 shows yet another embodiment of amesh600 implanted in an intervertebral disc. Here, thecurvilinear elements602 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.
• 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.
• 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 encapsulatedmesh606.FIG. 71C shows a top view cross-section wherein the mesh is elongated U shaped and71D through71F 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.
• In another embodiment, as shown inFIGS. 72A-B, amesh600 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 adefect16 in theanulus10 and placement of theframe600 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.
• In one embodiment, themesh600 can be implanted such that the midpoint of themesh frame600 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 themesh600 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.
• FIGS. 73A-C shows other embodiments for the end or natural hinge portion of the frame (e.g., mesh600), including a loop formation.
• FIGS. 74A-C show some embodiments of the central band or strut604.FIGS. 74A-B show acentral reinforcement band604 disposed between the ends or apexes of the frame (e.g., mesh). As shown inFIG. 74B, thecentral band604 can be positioned between the top rail (or wire)603 and bottom rail (or wire)605. As shown inFIG. 74C, thecentral band604 can be elongated to form a concave cross-section between the top and bottom rail or wire.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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 inFIGS. 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 implant610 (e.g., an annulus augmentation device such as a mesh) having one or more projections extending into the disc or into a defect.
• 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.
• FIG. 76 shows animplant610 according to one embodiment of the invention. Here, a bow-likeanterior projection612 extends outwardly from a posterior support member614 (e.g., a patch, barrier or mesh). Theprojection612 can be connected at each end of theposterior support member614 along its horizontal axis. Theprojection612 can be attached at any point along the vertical axis of the end including its midline, ends, or its entirety. Theprojection612 may be integral to theposterior support member614 such that theposterior support member614 is simply formed as a band or attached separately. As shown theimplant610 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.
• Various embodiments of the bow or arcurate member orprojection612 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 theprojection612 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 orstabilizer612 can also provide torsional resistance to thebarrier614. Finally, because the projection or bow612 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.
• The projection, bow orband portion612 of theimplant610 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 biocompatiblesupport member portion614 of theimplant610. Theprojection612 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 inFIG. 76, more than one bow-like projections may be used.
• 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. Thebow projection612 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.
• The stabilizingprojection612 can be made of the same material as the biocompatible support member614 (e.g., barrier, patch or mesh). In one embodiment, the stabilizingprojection612 is an off-angle projection of thebiocompatible support member614 and forms a continuous loop or band. In another embodiment, the stabilizingprojection612 can be made of a different biocompatible material, including polymers, metals, bio-materials, and grafts.
• FIGS. 77A-H show various cross-sectional side views of animplant610 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.
• FIGS. 78A-J show various cross-sectional top views ofimplants610 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.
• FIGS. 79A-F show a frontal view of a portion of various embodiments of projections according to one or more embodiments of the invention.
• FIGS. 80A-D show various cross-sections ofprojection612, according to some embodiments of the invention.
• FIGS. 81A-D show looped or bent bow-type projections612 that are contiguous or integral with, or are connected to thebiocompatible support member614 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.
• 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.
• 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.

Claims (20)

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 ofclaim 1, wherein the vertebral body is a superior vertebral body.

3. The method ofclaim 1, wherein the vertebral body is an inferior vertebral body.

4. The method ofclaim 1, wherein the anchor is positioned at a site substantially opposite said defect.

5. The method ofclaim 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 ofclaim 5, wherein returning at least part of the herniated segment to a pre-herniated position comprises tightening the connection member.

7. The method ofclaim 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 ofclaim 1, further comprising positioning said support member along an innermost layer of the anulus.

9. The method ofclaim 1, wherein said anchor comprises a bone anchor.

10. The method ofclaim 1, further comprising closing said defect in the anulus fibrosis.

11. The method ofclaim 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 ofclaim 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 ofclaim 12, wherein said anchor comprises a bone anchor.

15. The method ofclaim 12, wherein securely establishing said anchor comprises anchoring said anchor into the vertebral body adjacent said herniated segment.

16. The method ofclaim 15, wherein said vertebral body is a superior vertebral body.

17. The method ofclaim 15, wherein said vertebral body is an inferior vertebral body.

18. The method ofclaim 12, further comprising positioning said support member along an innermost layer of the anulus.

19. The method ofclaim 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 ofclaim 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.

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