WO2022232639A1

WO2022232639A1 - Intervertebral disc implant utilizing self-healing polymers

Info

Publication number: WO2022232639A1
Application number: PCT/US2022/027125
Authority: WO
Inventors: Aaron M. KUSHNER; Timothy J. BORTREE
Original assignee: Kushner Aaron M; Bortree Timothy J
Priority date: 2021-04-29
Filing date: 2022-04-29
Publication date: 2022-11-03

Abstract

Disclosed are intervertebral disc implants utilizing self-healing polymers. Preferred embodiments include a resilient body configured to be, when implanted, positioned between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space. Preferably, the resilient body has a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates. Preferably, the resilient body, when implanted, has an upper surface fixed relative to the superior endplate and a lower surface fixed relative to the inferior endplate. As the endplates move relative to one another during articulation of the spine, the resilient body experiences damage. Preferably, when the resilient body is subjected to spinal forces within anatomically healthy limits, the damage results in no compromise to the structural integrity.

Description

INTERVERTEBRAL DISC IMPLANT UTILIZING SELF-HEALING POLYMERS

FIELD OF THE INVENTION

[0001] The present invention relates generally to medical devices, and more particularly to intervertebral disc implants utilizing self-healing polymers.

CROSS-REFERENCE TO RELATED APPLICATIONS [0002] This application claims the benefit of U.S. Provisional Patent Application No. 63/181,926, filed April 29, 2021, the contents of which are hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0003] Spinal fusion is the “gold standard” treatment to address mild and severe degenerative disc disease (DDD), caused by degradation of the intervertebral disc that separates the vertebra and allows for flexibility and energy dissipation. However, this treatment option results in substantial loss of mobility and accelerated degeneration of adjacent spinal discs, often requires revision and/or additional surgery, and suffers from a high “return-to-pain” rate.

[0004] To provide an alternative to spinal fusion, total disc replacement (TDR) implants were developed. The first generation TDR implants used metal and rigid polymers. While offering somewhat improved post-operative mobility, a lack of significant improvement as compared with spinal fusion led to a low rate of adoption and the majority of these impalnts being approved for use only in the cervical spine, which has a lower performance requirement. [0005] In an effort to develop a product that offers a more substantial improvement in efficacy, a second generation of TDR devices were designed to more closely mimic the structure of the natural disc. These utilized a bio-inspired design with flexible commercial polymers. They typically feature a tough elastic damping pad to mimic the soft hydrated nucleus pulposus (NP) and a weave of hard plastic fibers surrounding the pad to mimic the strong and tough fibrous laminate structure of the annulus fibrosus (AF). The designs seek to improve post-operative mobility and achieve a more natural load distribution. In addition, based on the recognition that DDD begins with loss of function in the NP due to biodegradation of the biopolymer blend, standalone NP replacement by a soft synthetic polymer balloon or pad has been developed to treat earlier stage DDD. [0006] However, these strategies have struggled to obtain regulatory approval and/or take significant market share away from spinal fusion. These difficulties have spurred recent research and development efforts fueling a third generation of implants that not only mimic the macroscopic architecture of the natural intervertebral disc, but also the chemical and nanoscale structures.

[0007] In the three decades since pioneers began to explore the possibility of TDR implants as an alternative to fusion, modem polymer chemistry tools have been developed that afford polymer chemists unprecedented precision in chemical and structural control, unlocking a new paradigm in macromolecular engineering. While an order of magnitude more flexible and tunable than conventional polymers, designs employing these new techniques are nonetheless an order of magnitude less precise than biological polymer systems, such as enzymatic synthesis polyamino acids with momomer-level sequence precision. However, the nanoarchitectural and chemical composition flexibility enabled by a monomer chemistry toolset has allowed macromolecular engineers to design bio-inspired and bio-mimetic polymers that have been quite successful in capturing some of the multifunctionality that makes biological polymer materials so exceptional. Nature’s ability to synthesize materials that spontaneously heal themselves is one of the functions that polymer materials scientists and chemists have sought to imbue in petrochemical-based polymers. Impressive strides have been made using modem polymer chemistry, in particular by using a bioinspired approach. However, the obvious applications for self-healing materials, such as corrosion prevention, have failed to materialize, due to volume/margin considerations in those markets.

[0008] While the development of a “soft” polymer disc implant would have many benefits as discussed above, their soft nature means a compromise of the impressive mechanical damage and wear resistance characteristics of hard synthetic engineering materials. Conventional soft polymeric materials do not have mechanisms to heal themselves from wear and tear, such as is experienced by the intravertebral disc over millions of loading cycles.

[0009] The present invention addresses these problems and the need for improved intervertebral disc implants.

SUMMARY OF THE INVENTION

[0010] The present invention provides intervertebral disc implants utilizing self-healing polymers. [0011] Preferred embodiments include a resilient body configured to be, when implanted, positioned between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space. Preferably, the resilient body has a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates. Preferably, the resilient body, when implanted, has an upper surface fixed relative to the superior endplate and a lower surface fixed relative to the inferior endplate. As the endplates move relative to one another during articulation of the spine, the resilient body experiences damage. Preferably, when the resilient body is subjected to spinal forces within anatomically healthy limits, the damage results in no compromise to the structural integrity. Preferably, when the resilient body is subjected to spinal forces exceeding the limits, the damage results in compromise to the structural integrity, but the resilient body automatically repairs the damage to maintain or restore the structural integrity.

[0012] The present invention further provides methods of implanting intervertebral disc implants utilizing self-healing polymers.

[0013] Preferred embodiments include a method of implanting an intervertebral disc assembly, including the steps of: positioning an upper fusion plate of the intervertebral disc assembly adjacent a superior vertebral body of an intervertebral space of a spine; positioning a lower fusion plate of the intervertebral disc assembly adjacent an inferior vertebral body of an intervertebral space of a spine; fixing the upper fusion plate relative to the superior endplate by at least one of bone growth into the upper fusion plate, and bone screws; and fixing the lower fusion plate relative to the inferior endplate by at least one of bone growth into the lower fusion plate, and bone screws. The intervertebral disc assembly preferably includes a resilient body having, when implanted, an upper surface fixed relative to the upper fusion plate and a lower surface fixed relative to the lower fusion plate. The resilient body preferably further has, when implanted, a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates. As the endplates move relative to one another during articulation of the spine, the resilient body experiences damage. Preferably, the resilient body is configured such that when the resilient body is subjected to spinal forces within anatomically healthy limits the damage results in no compromise to the structural integrity. Further preferably, when the resilient body is subjected to spinal forces exceeding the limits the damage results in compromise to the structural integrity, the resilient body is configured to automatically repair the damage to maintain or restore the structural integrity.

[0014] Other preferred embodiments include a method of implanting an intervertebral disc assembly, including the steps of: positioning a resilient body of the intervertebral disc assembly between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space; maintaining an upper surface of the resilient body adjacent the superior endplate for an effective period of time for fixation of the upper surface relative to the superior endplate; and maintaining a lower surface of the resilient body adjacent the inferior endplate for an effective period of time for fixation of the lower surface relative to the inferior endplate. Preferably, one or both of the relative fixations are effected by one or more of chemical interactions between, mechanical interlocking of, diffusion into, and electrostatic adhesion of the respective surface and the corresponding respective endplate.

[0015] Other aspects, features, and advantages of the present invention will be apparent to one skilled in the art from the description herein taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS [0016] For the purposes of illustration, there are forms shown in the drawings that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. It should further be understood that in the drawings, like numerals indicate like elements.

[0017] FIG. 1 illustrates examples of self-healing polymers used in the resilient body of preferred embodiments of the present invention are illustrated.

[0018] FIG. 2 illustrates examples of pendant non-covalent dynamically interacting motifs used in polymers of the resilient body of preferred embodiments of the present invention.

[0019] FIG. 3 illustrates certain embodiments of intervertebral disc implants of the present invention.

DETAILED DESCRIPTION OF THE INVENTION [0020] The present invention provides intervertebral disc implants utilizing self-healing polymers, and methods of implanting the same. [0021] The present invention utilizes bioinspired polymer and composite materials, such as, for example without limitation, self-healing materials, that are assembled or otherwise incorporated into devices for use in synthetic intervertebral disc implants (full or partial), in order to obtain multi-functional, multimaterial, laminate, bioinspired, and/or biomimetic assemblies that meet or exceed the performance of the natural intervertebral disc.

[0022] The utilization of these materials is accomplished by the present invention using modern controlled polymerization techniques that enable fine control of the chemical and nanostructural properties of the polymers.

[0023] In preferred embodiments, an intervertebral disc assembly of the present invention includes a resilient body configured to be, when implanted, positioned between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space.

[0024] Preferably, the resilient body has a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates.

[0025] Preferably, the resilient body, when implanted, has an upper surface fixed relative to the superior endplate and a lower surface fixed relative to the inferior endplate.

[0026] As the endplates move relative to one another during articulation of the spine, the resilient body experiences damage. Preferably, when the resilient body is subjected to spinal forces within anatomically healthy limits, the damage results in no compromise to the structural integrity. Further preferably, when the resilient body is subjected to spinal forces exceeding the limits, the damage results in compromise to the structural integrity, but the resilient body automatically repairs the damage to maintain or restore the structural integrity. [0027] In preferred embodiments of the present invention, the resilient body includes a self-assembling polymer that effects the automatic repair of the damage.

[0028] Referring now to FIG. 1, examples of self-healing polymers (e.g., self-assembling polymers) used in the resilient body of preferred embodiments of the present invention are illustrated.

[0029] In FIG. 1, the asterisks denote pendant non-covalent, dynamically interacting motifs. Identified by element number 100A is a linear block co-polymer with a small minority block. Identified by element number 100B is a brush co-polymer. Identified by element number lOOC is a linear block co-polymer with a larger minority block. Identified by element number 100D is a two-phase spheroidal microstructure into which polymers 100 A and 100B self-assemble. In the two-phase spheroidal microstructure 100D, the continuous phase has a network of non-covalent bonds. Identified by element number 100E is a cylindrical two-phase microstructure into which polymer lOOC self-assembles. In the cylindrical two-phase microstructure, the continuous phase has a network of non-covalent bonds.

[0030] These and other examples of polymers used in the resilient body of preferred embodiments of the present invention are described in greater detail in U.S. Patent Number 9,938,368, issued April 4, 2018, and U.S. Patent Number 11,111,330, issued September 7, 2021, both of which are hereby incorporated by reference herein.

[0031] In preferred embodiments of the present invention, the resilient body includes, and repairs the damage within, a reversibly bonded polymer network. Preferably, the damage is repaired completely. Preferably, the network is a non-covalent polymer network. Further preferably, the network includes at least one of the following non-covalent supramolecular attractive interactions between pendant motifs presented along the length of some or all of the polymer chains: (1) hydrogen-bonding; (2) p - p stacking; (3) Van der Waals; (4) Debye, structural or physical such as, for example, entanglement inducing; and (5) ionic. Preferably, ionic includes at least one of (1) oppositely charged fixed charges on separate polymer chains, and (2) mediated similarly charged fixed charges in which non-covalent bonding is mediated by a non-fixed ion.

[0032] Referring now to FIG. 2, examples of pendant non-covalent dynamically interacting motifs used in the resilient body of preferred embodiments of the present invention are illustrated.

[0033] In FIG. 2, squiggly lines represent connection to a polymer structure. Identified by element number 200A is an ionic bond consisting of two pendant ions of the same polarity connected by an oppositely charged dianion. Identified by element number 200B is a pendant hydrogen bonding motif. Identified by element number 200C is an oppositely charged pendant ionic non-covalent bond. Identified by element number 200D is a p - p stacking non- covalent attractive interaction. Identified by element number 200E is a Debye type non- covalent interaction. Identified by element number 200F is a combination of structural and Van der Waals non-covalent interaction.

[0034] In preferred embodiments of the present invention, the resilient body includes a polymer that includes a conjugate that self-assembles into a hard-soft microphase-separated multiphase supramolecular thermoplastic elastomer when in a bulk dehydrated and/or hydrated form, and the conjugate is at least one of a polymer-polymer conjugate or a polymer- nanoparticle conjugate.

[0035] For example, in certain embodiments, the self-healing polymer or polymers of the resilient body are conjugates.

[0036] Preferably, hard-soft is defined with respect to hard as having a T_g above body temperature (or that is insoluble at body temperature) when in the bulk dehydrated and/or hydrated form, and is defined with respect to soft as having a T_g below body temperature when in the bulk dehydrated and/or hydrated form.

[0037] Examples of conjugates include, but are not limited to, a linear block co-polymer of a hydrophobic block conjugated to a hydrophilic block. For example, the hydrophobic block can be “hard” and the hydrophilic block can be “soft”. For example, the hydrophobic block can be covalently bonded to the hydrophilic block. In certain embodiments, the hard block is the minority block. In some of those and certain other embodiments, there are multiple blocks.

[0038] Other examples of conjugates include, but are not limited to, a linear block co polymer of a hydrophilic block conjugated to a hydrophilic block. For example, the first hydrophilic block can be “hard” and the second hydrophilic block can be “soft”. For example, the first hydrophilic block can be covalently bonded to the second hydrophilic block. In certain embodiments, the hard block is the minority block. In some of those and certain other embodiments, there are multiple blocks.

[0039] Other examples of conjugates include, but are not limited to, a brush co-polymer with a hydrophobic backbone and hydrophilic brushes conjugated and/or grafted to the backbone. For example, the brush co-polymer can have a hydrophobic block that is hard, with hydrophilic grafts that are soft, and the hydrophobic backbone and hydrophilic brushes are conjugated and/or grafted to the backbone.

[0040] Other examples of conjugates include, but are not limited to, a brush co-polymer with a hydrophobic backbone and hydrophilic brushes conjugated and/or grafted to the backbone. For example, the brush co-polymer can have a hydrophobic block that is hard, with hydrophilic grafts that are soft, and the hydrophobic backbone and hydrophilic brushes are conjugated and/or grafted to the backbone. Or, for example, the brush co-polymer can have a hydrophilic block that is hard, with hydrophilic grafts that are soft, and the hydrophobic backbone and hydrophilic brushes are conjugated and/or grafted to the backbone. [0041] Other examples of conjugates include, but are not limited to, a bottlebrush co polymer with a hydrophobic backbone and hydrophilic brushes conjugated and/or grafted to the backbone. For example, the bottlebrush co-polymer can have a hydrophobic block that is hard, with hydrophilic grafts that are soft, and the hydrophobic backbone and hydrophilic brushes are conjugated and/or grafted to the backbone. Or, for example, the bottlebrush co polymer can have a hydrophilic block that is hard, with hydrophilic grafts that are soft, and the hydrophobic backbone and hydrophilic brushes are conjugated and/or grafted to the backbone.

[0042] Other examples of conjugates include, but are not limited to, a covalently conjugated structure containing a combination of the above block and brush and/or bottlebrush structures.

[0043] Other examples of conjugates include, but are not limited to, a linear, block, brush, bottlebrush, or combination of these, connected or grafted to a nanoparticle or nano-object polymer.

[0044] Other examples of conjugates include, but are not limited to, any and all blends, permutations, or combinations of the above structures.

[0045] Other examples of conjugates include, but are not limited to, some of all of the structures described above, but in which the blocks and/or brushes contain pendant or main- chain reversibly bonding motifs.

[0046] Some or all of the conjugates described herein can optionally include monomers incorporated in the polymers. Suitable monomers include, but are not limited to, monomers considered hydrophilic-inducing, monomers considered hydrophobic-inducing, and monomers considered amphiphilic.

[0047] Monomers considered hydrophillic-inducing include, for example without limitation, 2-propenamide, methacrylamide, acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate (all hydroxy (meth)acrylates), 2-hydroxyethyl methacrylate, N- (ethoxymethyl)acrylamide, N-[Tris(hydroxymethyl)methyl]acrylamide, N-vinyl acetamide, [2-(Methacryloyloxy)ethyl]trimethylammonium chloride, 2-acrylamido-2-methylpropane sulfonic acid, sodium salt, 3-sulfopropyl acrylate, potassium salt, carboxybetaine acrylamide, carboxybetaine acrylate, acrylate ethers including methoxy and mPEG acrylates, N- acetalmethacrylamide, aminopropylsiloxane, vinyl alcohols, norbornene alcohols, norbomene carboxylic acids, 4-styrene sulfonic acid, [3- (methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium, 2-methacryloyloxyethyl phosphorylcholine, and l-(3-sulfopropyl)-2-vinylpyridinium (norbornene).

[0048] Monomers considered hydrophobic-inducing include, for example without limitation, acrylates and their meth versions (such as but not limited to benzyl acrylate, butyl acrylate, 4-chlorophenyl acrylate, 2-cyanoethyl acrylate, cyanomethyl acrylate, cyclohexyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, isobutyl acrylate, isopropyl acrylate, methyl acrylate, octyl acrylate, propyl acrylate, sec-butyl acrylate, stearyl acrylate tert-butyl acrylate), acrylonitrile, methacrylonitrile, Styrenes (such as but not limited to 2- methoxystyrene, a-methyl styrene, 2-methylstyrene, 3 -methyl styrene, 4-methylstyrene, styrene 4-tert-butyl styrene, 4-vinylphenol, 2-vinylpyridine, 4-vinylpyridine), siloxanes (including but not limited to diethylsiloxane, dimethyl siloxane methylphenylsiloxane, diphenylsiloxane), norbornene, and norbornene imide.

[0049] Monomers considered amphiphilic include, for example without limitation, N- isopropyl acrylamide, N,N-Dimethyl acrylamide, N-octyl acrylamide, N-tert-butyl acrylamide, N-phenyl acrylamide, N-sec-butyl acrylamide, N-vinyl-pyrolidinone, N-vinyl imidazole, where hydrophilicity/hydrophobicity may be a function of being above or below a critical temperature.

[0050] Preferably, in certain embodiments, the conjugates self-assemble into a hard-soft microphase-separated multiphase material when in the bulk- dehydrated or hydrated state. In some of these and other certain embodiments, the hard phase is discontinuous.

[0051] Preferably, in certain embodiments, the bulk hydrated or de-hydrated forms of the conjugates self-heal to recovery of stress-strain behavior after deformation, as distinct from scission, at least to the yield point, without the input of additional stimulus within 24 hours at body temperature.

[0052] Preferably, in certain embodiments, additives are blended in parts or all of the assembly, such as, for example without limitation, particles, nanoparticles, nanoobjects, or molecules such as, for example without limitation, antibiotics, commercially available or synthetic polymers, and radiocontrast agents.

[0053] Referring now to FIG. 3, certain embodiments of intervertebral disc implants of the present invention are illustrated. Preferably, the intervertebral disc implants mimic the mechanical behavior of the natural intervertebral disc.

[0054] In FIG. 3, various examples of intervertebral disc implants are identified by element numbers 300A-C. [0055] In preferred embodiments of the present invention, the resilient body has a central nucleus surrounded by an annulus, the nucleus having biomechanical properties of a nucleus pulposus of an intervertebral disc, the annulus having biomechanical properties of an annulus fibrosis of the intervertebral disc. Preferably, the anatomically appropriate spacing maintained by the resilient body is one or more of 5.6 ± 1.1 mm for men and 4.8 ± 0.8 mm for women at the T 12/Ll disc space, 6.9 ± 1.3 mm for men and 5.8 ± 0.9 mm for women at the Ll/2 disc space, 8.1 ± 1.4 mm for men and 6 9 ± 1.1 mm for women at the L2/3 disc space, 8.7 ± 1.5 mm for men and 7.6 ± 1.2 mm for women at the L3/4 disc space, 9.2 ± 1 .6 mm for men and 8.5 ± 1.6 mm for women at the L4/5 disc space, and 8.8 ± 1.6 mm for men and 8.6 ± 1 .8 m for women at the L5/S1 disc space. Preferably, during the articulation of the endplates, the resilient body maintains a sagittal plane diameter of the resilient body that avoids contact between the resilient body and a spinal cord passing through the intervertebral bodies.

[0056] In preferred embodiments, the resilient body includes a softer core and a stiffer outer ring, to mimic the structure of the natural intervertebral disc. Preferably, one or both of the core and the ring contain one or more self-healing polymers (e.g., those discussed herein). In certain embodiments, the resilient body includes multiple ring laminates of various compositions. Preferably, one or more of the rings includes one or more self-healing polymers (e.g., those discussed herein).

[0057] Identified by element number 300A is a design characterized by a central softer core 310A and an outer stiffer ring 320A, both of which preferably include one or more self- healing polymers discussed herein.

[0058] With regard to the assemblies identified by element numbers 300B and 300C, in preferred embodiments, the resilient body, when implanted, has an upper surface fixed relative to the superior endplate and a lower surface fixed relative to the inferior endplate. Such fixation can be accomplished in any suitable manner.

[0059] As one example, identified by element number 300B is a design characterized by the assembly (e.g., the assembly of 300A, or any other assemblies) being capped with layers 330B designed to fix the assembly to adjacent vertebral endplates. For example, the layers 330B can include a permanently bonded adhesive.

[0060] As another example, identified by element number 300C is a design characterized by the assembly (e.g., the assembly of 300A, or any other assemblies) being capped with structures 340C designed to fix the assembly to adjacent vertebral endplates. For example, the structures 340C can be capped to the assembly by a permanently bonded adhesive. For example, the structures can be metallic structures commonly used to fix artificial intervertebral disc implants to adjacent vertebral endplates.

[0061] Fixation is not limited to the above examples.

[0062] In some embodiments, one or both of the relative fixations are effected by one or more of chemical interactions between, mechanical interlocking of, diffusion into, and electrostatic adhesion of, either the respective surface and the corresponding respective endplate or the respective surface and a corresponding respective fusion plate fixed relative to the corresponding respective endplate.

[0063] In some of these and other embodiments, one or both of the upper and lower surfaces have properties more effective, for fixation to one or more of the endplates and the fusion plates, than interior portions of the resilient body.

[0064] In some of these and other embodiments, one or both of the relative fixations are effected by forming permanent covalent bonds with molecules of the endplates. In some of these and other embodiments, one or both of the relative fixations are effected by reacting with high strength elastomer monomers to form a network of, for example without limitation, at least one of polyurea and polyurethane. In some of these and other embodiments, one or both of the relative fixations are effected by facilitating growth of bone into a polymer. [0065] In some of these and other embodiments, one or both of the relative fixations are effected by application of a material that diffuses into the respective surface and diffuses into either the corresponding respective endplate or the corresponding respective fusion plate fixed relative to the corresponding respective endplate.

[0066] In some of these and other embodiments, one or more of the diffusions are effected by application of heat to the material.

[0067] Further with regard to the fixation, certain preferred embodiment also include an upper fusion plate fixed relative to the upper surface of the resilient body and fixed relative to the superior endplate, and a lower fusion plate fixed relative to the lower surface of the resilient body and fixed relative to the inferior endplate. In some of these and other embodiments, at least one of the fusion plates is fixed relative to the corresponding respective endplate by at least one of bone growth into the at least one fusion plate, and bone screws. [0068] The present invention further provides methods of implanting intervertebral disc implants utilizing self-healing polymers. [0069] In some preferred embodiments, a method of implanting an intervertebral disc assembly includes the steps of: positioning an upper fusion plate of the intervertebral disc assembly adjacent a superior vertebral body of an intervertebral space of a spine; positioning a lower fusion plate of the intervertebral disc assembly adjacent an inferior vertebral body of an intervertebral space of a spine; fixing the upper fusion plate relative to the superior endplate by at least one of bone growth into the upper fusion plate, and bone screws; and fixing the lower fusion plate relative to the inferior endplate by at least one of bone growth into the lower fusion plate, and bone screws.

[0070] Preferably, the intervertebral disc assembly comprises a resilient body having, when implanted, an upper surface fixed relative to the upper fusion plate and a lower surface fixed relative to the lower fusion plate. Preferably, the resilient body further has, when implanted, a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates.

[0071] As the endplates move relative to one another during articulation of the spine, the resilient body experiences damage. Preferably, the resilient body is configured such that when the resilient body is subjected to spinal forces within anatomically healthy limits, the damage results in no compromise to the structural integrity and when the resilient body is subjected to spinal forces exceeding the limits, the damage results in compromise to the structural integrity. Preferably, the resilient body is configured to automatically repair the damage to maintain or restore the structural integrity.

[0072] In some of these and other preferred embodiments, a method of implanting an intervertebral disc assembly includes the steps of: positioning a resilient body of the intervertebral disc assembly between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space; maintaining an upper surface of the resilient body adjacent the superior endplate for an effective period of time for fixation of the upper surface relative to the superior endplate; and maintaining a lower surface of the resilient body adjacent the inferior endplate for an effective period of time for fixation of the lower surface relative to the inferior endplate. Preferablt, one or both of the relative fixations are effected by one or more of chemical interactions between, mechanical interlocking of, diffusion into, and electrostatic adhesion of the respective surface and the corresponding respective endplate.

[0073] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

REFERENCES INCORPORATED BY REFERENCE [0074] The disclosures of the following publications and any other documents or publications cited or otherwise discussed herein, and any file wrappers (e.g., including but not limited to case histories) of any patents or patent applications cited or otherwise discussed herein, and patents or patent applications related thereto and their file wrappers, are hereby incorporated by reference in their entirety into the subject application to more fully describe the art to which the subject invention pertains.

[0075] (1) Yang, M.; Xiang, D.; Chen, Y.; Cui, Y.; Wang, S.; Liu, W. An Artificial Disc

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[0076] (2) Newell, N.; Little, J.P.; Christou, A.; Adams, M.A.; Adam, C.J.; Masouros,

S.D. Biomechanics of the human intervertebral disc: A review of testing techniques and results, Journal of the Mechanical Behavior of Biomedical Materials 2017, 69, 420-434. [0077] (3) Cortes, D.; Elliott, D., The Intervertebral Disc: Overview of Disc Mechanics.

The Intervertebral Disc: Molecular and Structural Studies of the Disc in Health and Disease 2014, 17-31.

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Kamigaito, M.; Boyer, C.; Qiao, G. G., Progress and Perspectives Beyond Traditional RAFT Polymerization. Advanced Science 2020, 7 (20).

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Claims

WHAT IS CLAIMED IS:

1. An intervertebral disc assembly, comprising: a resilient body configured to be, when implanted, positioned between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space, the resilient body having a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates; wherein the resilient body, when implanted, has an upper surface fixed relative to the superior endplate and a lower surface fixed relative to the inferior endplate; as the endplates move relative to one another during articulation of the spine, the resilient body experiences damage; when the resilient body is subjected to spinal forces within anatomically healthy limits, the damage results in no compromise to the structural integrity; when the resilient body is subjected to spinal forces exceeding the limits, the damage results in compromise to the structural integrity; and the resilient body automatically repairs the damage to maintain or restore the structural integrity.

2. The intervertebral disc assembly of claim 1, wherein the resilient body includes, and repairs the damage within, a reversibly bonded polymer network.

3. The intervertebral disc assembly of claim 2, wherein the network is a non-covalent polymer network.

4. The intervertebral disc assembly of claim 3, wherein the network includes at least one of hydrogen-bonding, p - p stacking, van der Waals, Debye, and ionic; and ionic includes at least one of oppositely charged fixed charges on separate polymer chains, and mediated similarly charged fixed charges in which non-covalent bonding is mediated by a non-fixed ion.

5. The intervertebral disc assembly of claim 1, wherein the resilient body includes a polymer that includes a conjugate that self-assembles into a hard-soft microphase-separated multiphase supramolecular thermoplastic elastomer when in a bulk dehydrated and/or hydrated form; and the conjugate is at least one of a polymer-polymer conjugate or a polymer- nanoparticle conjugate.

6. The intervertebral disc assembly of claim 1, wherein one or both of the relative fixations are effected by one or more of chemical interactions between, mechanical interlocking of, diffusion into, and electrostatic adhesion of, either the respective surface and the corresponding respective endplate or the respective surface and a corresponding respective fusion plate fixed relative to the corresponding respective endplate.

7. The intervertebral disc assembly of claim 6, wherein one or both of the upper and lower surfaces have properties more effective, for fixation to one or more of the endplates and the fusion plates, than interior portions of the resilient body.

8. The intervertebral disc assembly of claim 6, wherein one or both of the relative fixations are effected by at least one of forming permanent covalent bonds with molecules of the endplates, reacting with high strength elastomer monomers to form a network of at least one of polyurea and polyurethane, and facilitating growth of bone into a polymer.

9. The intervertebral disc assembly of claim 6, wherein one or both of the relative fixations are effected by application of a material that diffuses into the respective surface and diffuses into either the corresponding respective endplate or the corresponding respective fusion plate fixed relative to the corresponding respective endplate.

10. The intervertebral disc assembly of claim 6, wherein one or more of the diffusions are effected by application of heat to the material.

11. The intervertebral disc assembly of claim 6, further comprising: an upper fusion plate fixed relative to the upper surface of the resilient body and fixed relative to the superior endplate; and a lower fusion plate fixed relative to the lower surface of the resilient body and fixed relative to the inferior endplate.

12. The intervertebral disc assembly of claim 11, wherein at least one of the fusion plates is fixed relative to the corresponding respective endplate by at least one of bone growth into the at least one fusion plate, and bone screws.

13. The intervertebral disc assembly of claim 1, wherein the resilient body has a central nucleus surrounded by an annulus, the nucleus having biomechanical properties of a nucleus pulposus of an intervertebral disc, the annulus having biomechanical properties of an annulus fibrosis of the intervertebral disc.

14. The intervertebral disc assembly of claim 1, wherein the anatomically appropriate spacing is one or more of

5.6 ± 1.1 mm for men and 4.8 ± 0.8 mm for women at T 12/Ll,

6.9 ± 1.3 m for men and 5.8 ± 0.9 mm for women at Ll/2,

8.1 ± 1.4 mm for men and 6.9 ± 1.1 mm for women at L2/3,

8.7 ± 1.5 mm for men and 7.6 ± 1 2 mm for women at L3/4,

9.2 ± 1.6 mm for men and 8.5 ± 1.6 mm for women at L4/5, and

8.8 ± 1.6 mm for men and 8.6 ± 1.8 mm for women at L5/S1.

15. The intervertebral disc assembly of claim 1, wherein during the articulation the resilient body maintains a sagittal plane diameter of the resilient body that avoids contact between the resilient body and a spinal cord passing through the intervertebral bodies.

16. A method of implanting an intervertebral disc assembly, comprising the steps of: positioning an upper fusion plate of the intervertebral disc assembly adjacent a superior vertebral body of an intervertebral space of a spine; positioning a lower fusion plate of the intervertebral disc assembly adjacent an inferior vertebral body of an intervertebral space of a spine; fixing the upper fusion plate relative to the superior endplate by at least one of bone growth into the upper fusion plate, and bone screws; and fixing the lower fusion plate relative to the inferior endplate by at least one of bone growth into the lower fusion plate, and bone screws; wherein the intervertebral disc assembly comprises a resilient body having, when implanted, an upper surface fixed relative to the upper fusion plate and a lower surface fixed relative to the lower fusion plate, the resilient body having, when implanted, a structural integrity that supports relative movement of the endplates while maintaining anatomically appropriate spacing between the endplates; as the endplates move relative to one another during articulation of the spine, the resilient body experiences damage; the resilient body is configured such that when the resilient body is subjected to spinal forces within anatomically healthy limits, the damage results in no compromise to the structural integrity and when the resilient body is subjected to spinal forces exceeding the limits, the damage results in compromise to the structural integrity; and the resilient body is configured to automatically repair the damage to maintain or restore the structural integrity.

17. The method of claim 16, wherein the resilient body is configured to repair the damage within a reversible polymer network.

18. The intervertebral disc assembly of claim 17, wherein the network is a non-covalent polymer network.

19. The intervertebral disc assembly of claim 18, wherein the network includes at least one of hydrogen-bonding, p - p stacking, van der Waals, Debye, and ionic; and ionic includes at least one of oppositely charged fixed charges on separate polymer chains, or mediated similarly charged fixed charges in which non-covalent bonding is mediated by a non-fixed ion.

20. A method of implanting an intervertebral disc assembly, comprising the steps of: positioning a resilient body of the intervertebral disc assembly between an endplate of a superior vertebral body of an intervertebral space of a spine and an endplate of an inferior vertebral body of the intervertebral space; maintaining an upper surface of the resilient body adjacent the superior endplate for an effective period of time for fixation of the upper surface relative to the superior endplate; and maintaining a lower surface of the resilient body adjacent the inferior endplate for an effective period of time for fixation of the lower surface relative to the inferior endplate; wherein one or both of the relative fixations are effected by one or more of chemical interactions between, mechanical interlocking of, diffusion into, and electrostatic adhesion of the respective surface and the corresponding respective endplate.