Patent Description:
An estimated <NUM> million Americans suffer from intervertebral disc disorders or low-back disabilities. Although the cause of low-back pain is multifactorial, defects in intervertebral discs are generally considered to be a primary source or an initiating factor that leads to altered spinal biomechanical function and non-physiologic stress in the surrounding tissues.

The intervertebral disc consists of three distinct parts: the nucleus pulposus; the annulus fibrosus; and the cartilaginous endplates. The nucleus pulposus is a viscous, mucoprotein gel centrally located within the disc and contains sulfated glycosaxninoglycans in a loose network of type II collagen fibers. The water content of the nucleus pulposus, approximately <NUM>% at birth, gradually decreases with age and contributes to the degeneration of the disc as part of the aging process. The annulus fibrosus is the portion of the intervertebral disc that forms the outer boundary of the intervertebral disc, and is made up of coarse type I collagen fibers oriented obliquely and arranged in lamellae which attach the adjacent vertebral bodies. The type I collagen fibers extend in the same direction within a given lamella, but opposite to those in adjacent lamellae. The overall collagen content of the intervertebral disc steadily increases from the center of the nucleus pulposus to the outer layers of the annulus fibrosus, where collagen can reach <NUM>% or more of the dry weight of the intervertebral disc. The cartilaginous vertebral end plates, which contain hyaline cartilage, cover the end surfaces of the vertebral bodies and serve as the cranial and caudal surfaces of the intervertebral disc.

The ability of the intervertebral disc to attract and retain water gives it unique structural properties. For example, the proteoglycans of the nucleus pulposus attract water osmotically, exerting a swelling pressure that enables the intervertebral disc to support compressive loads. The pressurized nucleus pulposus also creates significant tensile pre- stress within the annulus fibrosus and ligamentous structures surrounding the intervertebral disc. This results in an annular architecture where the collagen fibers are oriented approximately <NUM>° relative to the longitudinal axis of the spine to optimally support the tensile stresses developed within the spine. This tissue pre-stress, and maintaining the integrity of the annulus fibrosus, contributes significantly to normal kinematics and mechanical response of the human spine.

When the physical stress placed on the spine exceeds the nuclear swelling pressure, water is expressed from the intervertebral disc through the semipermeable cartilaginous end plates. This loss of nuclear water negatively affects the load distribution internal to the intervertebral disc. In a healthy disc under compressive loading, circumferential hoop stress is carried mainly by the annulus fibrosus. After extended compressive loading, pressure distribution changes such that the highest axial compressive stress occurs in the posterior annulus fibrosus. Similar pressure distribution changes have been noted in degenerated and denucleated intervertebral discs as well. This reversal in the state of annular stress demonstrates that nuclear dehydration significantly alters stress distributions within the intervertebral disc as well as its biomechanical response to loading.

Chemical changes are also observed with degeneration, particularly the loss of proteoglycan and water. This dehydration contributes to the loss of intervertebral disc height. Secondary changes in the annulus fibrosus include fibrocartilage production with disorganization of the lamellar architecture and increases in type II collagen.

Currently, there are few clinical options to offer patients who suffer from these conditions. The typical clinical options include conservative therapy with physical rehabilitation and surgical intervention with possible disc removal and spinal fusion for those who have failed more conservative therapy. Further, the existing techniques for forming a nuclear prosthesis in situ have not achieved convincing clinical acceptance or commercial success. One problem identified by the present disclosure is the substantial difference in the modulus of elasticity between the vertebral bony elements, including the vertebral end plates, and the annulus fibrosus on the one hand, and the implanted elements on the other. The high modulus of elasticity of the implanted material is disadvantageous since it does not dampen impacts or sudden increases in intra-discal pressure during extreme bending or torsion, especially during high loading peaks. The large difference in the modulus of elasticity between implanted disc materials and adjacent tissues can also lead to softening of the vertebral end plates and adjacent bone (spongeosus), resulting in subsidence of the nuclear implant. Migration and expulsion of the implant can also occur, particularly when there are defects in the annulus fibrosus. Confirmation of the proper size and orientation of the implant can also pose difficulty when replacing the nucleus pulposus with a nuclear prosthesis formed in situ.

Therefore, there is a need for an improved treatment for repairing or replacing degenerated discs. The present disclosure satisfies that need, as well as others, and overcomes the deficiencies associated with prior implants and treatment methods. <CIT> discloses a nuclear disc implant with an inner fillable enclosure and an outer fillable enclosure. <CIT> discloses a replacement intervertebral disc with a distensible sack which is inflated with hardenable material. <CIT> disclose an intervertebral prothesis for percutaneous deployment with an expandable annular enclosure and an expandable nuclear enclosure. <CIT> discloses a prosthesis for implantation in a de-nucleated disc which has a fiber ring-like layer enclosing a polymeric layer to create an annular space. <CIT> discloses a multi-chamber balloon for a nuclear implant with an elastomeric membrane defining inner and outer chambers integral with a valve body.

The invention is defined by the claims in which there is required a kit for implanting a nuclear prosthesis, the kit comprising: a spinal implant device comprising: a flexible body defining: an outer fillable enclosure defining an outer chamber having a body aperture; and an inner fillable enclosure defining an inner chamber such that the outer fillable enclosure at least partially surrounds the inner fillable enclosure, the inner fillable enclosure having an opening in fluid communication with the inner chamber; a proximal plug configured to be coupled to the inner fillable enclosure such that the proximal plug controls fluid communication through the opening, the proximal plug defines a receptacle including a plug aperture and including a re-sealable membrane to control fluid communication through a proximal opening of the inner chamber, the receptacle configured to couple with a retaining element of an inflation stylet, wherein the plug aperture is positioned between the retaining element and the re-sealable membrane when the proximal plug is mated with the inflation stylet and is configured to enable fluid communication to the outer fillable enclosure; the inflation stylet configured to mate with the proximal plug and extend at least partially through the proximal plug, the inflation stylet comprising: a first lumen configured to deliver a fluid to and remove a fluid from the inner chamber; a second lumen at least partially surrounding the first lumen and configured to deliver a fluid to the outer chamber; and the retaining element configured to control insertion depth of the inflation stylet and to secure the inflation stylet to the proximal plug.

A selection of optional features is set out in the dependent claims.

The following drawings illustrate by way of example and not limitation. For the sake of brevity and clarity, every feature of a given structure is not always labeled in every figure in which that structure appears. Identical reference numbers do not necessarily indicate an identical structure. Rather, the same reference number may be used to indicate a similar feature or a feature with similar functionality, as may non-identical reference numbers. The figures are drawn to scale (unless otherwise noted), meaning the sizes of the depicted elements are accurate relative to each other for at least the configurations depicted in the figures.

Referring now to the drawings, and more particularly to <FIG>, a spinal implant device <NUM> includes a flexible body <NUM> defining an outer fillable enclosure <NUM> defining an outer chamber <NUM> having a body aperture <NUM>; an inner fillable enclosure <NUM> defining an inner chamber <NUM> such that the outer fillable enclosure <NUM> at least partially surrounds the inner fillable enclosure <NUM>. The inner fillable enclosure <NUM> has an opening <NUM>, as best shown in <FIG>, in fluid communication with the inner chamber <NUM>. A proximal plug <NUM> is configured to be coupled to the inner fillable enclosure <NUM> such that the proximal plug <NUM> controls fluid communication through the opening <NUM>. In some configurations, the proximal plug <NUM> controls fluid communication through a re-sealable membrane <NUM> that can serve as a one-way valve and prevent any backflow of fluid from the inner chamber <NUM> into the outer chamber <NUM> when a fluid is delivered into the inner chamber <NUM>. In this way, an inflation stylet <NUM>, described in more detail below, can be configured to communicate with the inner chamber <NUM> and the outer chamber <NUM> through a single opening and without the contents of each chamber mixing together. Proximal plug <NUM> may be made of silicone or another material which is compatible with enclosures <NUM>, <NUM>, and may be manufactured using conventional manufacturing techniques, such as injection molding.

In some configurations, such as the one shown in <FIG>, outer fillable enclosure <NUM> has a first (or proximal) end 108a and a second (or distal) end 108b. Inner fillable enclosure <NUM> has a first (or proximal) end 116a coupled to a proximal neck 118a. A second (or distal) end 116b of inner fillable enclosure <NUM> is coupled to a distal neck 118b. An end portion 119a of proximal neck 118a is coupled to proximal end 108a of outer fillable enclosure <NUM>, and an end portion 119b of distal neck 118b is coupled to distal end 108b of outer fillable enclosure <NUM>. As best shown in <FIG>, end portion 119a of proximal neck 118a is coupled to proximal end 108a of outer fillable enclosure <NUM> by forming them together as a unitary piece during the manufacturing process, as will be described in more detail below. Distal end 108b of outer fillable enclosure <NUM> is inverted and bonded to end portion 119b of distal neck 118b to form a substantially fluid tight seal. Coupling the enclosures together in this manner forms a substantially fluid tight outer chamber <NUM>. Spinal implant device <NUM> is preferably sized so that it can be inserted using minimally invasive surgery techniques or percutaneously into an enucleated intervertebral disc cavity while deflated and then filled to fill the enucleated intervertebral disc cavity. In some configurations, the exterior of unfilled spinal implant device <NUM> is approximately <NUM> in length, <NUM> in width, and <NUM> in height, and the inner fillable enclosure <NUM> is approximately <NUM> long, <NUM> in diameter, and <NUM> thick. In some configurations, the wall thickness of the outer fillable enclosure <NUM> and inner fillable enclosure <NUM> may be formed to have varying wall thicknesses effective to achieve certain desired properties and/or functions. For example, the inner fillable enclosure <NUM> may have a wall thickness less than the outer fillable enclosure <NUM> to allow easier filling and expansion of the inner chamber <NUM> relative to the outer chamber <NUM>. In some configurations, the inner chamber <NUM> can be configured to provide pressure feedback when the outer chamber <NUM> is filled, as will be described below. In some configurations, spinal implant device <NUM> can have a durometer between Shore 10A and Shore 100A. In this way, the spinal implant device <NUM>, when combined with a curable medium described below, can exhibit an elastic modulus capable of dampening impacts or sudden increases in intra-discal pressure during bending, torsion, and/or other high loading peak movements. In at least this configuration, the spinal implant device <NUM> can further prevent spongeosus of adjacent bone and subsidence of the implant over time, thus mitigating migration and/or expulsion of the spinal implant device. In some configurations, the flexible body <NUM> includes a coating containing one or more ingredients selected from the list of ingredients consisting of: drugs, bioactives, and/or stem cells. The flexible body <NUM> can also include a lubricious coating to aid in the delivery of the spinal implant device <NUM>. Other ingredients may be chosen to achieve certain desired properties and/or functions. In this way, the spinal implant device <NUM> can further enhance repair and/or restoration of physiologic function of the intervertebral disc. In some configurations, the overall dimensions of unfilled spinal implant device <NUM> can be sized to be particularly suited for minimally invasive surgery, percutaneous surgery, robotic surgery, and/or robotics-assisted surgery. In some configurations, the outer chamber <NUM> does not expand significantly when it is filled (i.e., it is non-compliant or semi-compliant). In other configurations, the spinal implant device <NUM> is filled so that the spinal implant device <NUM> expands by approximately <NUM>% (i.e., doubles in size) when implanted. In other configurations, the spinal implant device <NUM> is filled so that the spinal implant device <NUM> expands by more than <NUM>% when implanted.

In some configurations, the outer and inner fillable enclosures <NUM>, <NUM> comprise a unitary piece of material. In some configurations, such as the ones shown in <FIG>, the inner chamber <NUM> has a proximal end <NUM> with a proximal opening <NUM> and a distal end <NUM> with a distal opening <NUM>. Although <FIG> show a distal end <NUM> with a distal opening <NUM>, other configurations of spinal implant device <NUM> may omit one or more features, such as a distal end <NUM> with a distal opening <NUM>.

In some configurations, as best shown in <FIG>, the outer fillable enclosure <NUM> and inner fillable enclosure <NUM> are axially symmetric around a longitudinal axis <NUM>. In this way, the spinal implant device <NUM> will have a proper orientation in any direction when inserting the spinal implant device <NUM> into an enucleated intervertebral disc cavity. Further, the axially symmetric shape of the outer fillable enclosure <NUM> and inner fillable enclosure <NUM> allows the spinal implant device <NUM> to expand, when combined with a curable medium (e.g., curable silicone containing <NUM>% barium sulfate), circumferentially around the longitudinal axis <NUM> to fill the entire enucleated space by accounting for the expansion behavior of the curable medium.

The flexible body <NUM> may further define a proximal opening <NUM> in fluid communication with the inner chamber <NUM>. The flexible body <NUM> may further define a distal opening <NUM> in fluid communication with the inner chamber <NUM>. A proximal plug <NUM> defines a receptacle <NUM> configured to receive a portion of an inflation stylet <NUM> for delivering a fluid to the inner chamber <NUM> and outer chamber <NUM>. A plug aperture <NUM> is in fluid communication with the outer chamber <NUM> when aligned with the body aperture <NUM>. Proximal neck 118a may have features, such as grooves, for mating with matching features on proximal plug <NUM> to assist in locating proximal plug <NUM>. Proximal plug <NUM> may be inserted into and bonded with proximal neck 118a. Proximal plug <NUM> can be configured to be coupled to an inflation tip <NUM> of an inflation stylet <NUM>. In some configurations, the receptacle <NUM> has a diameter between <NUM> and <NUM> at a widest diameter, a diameter between <NUM> and <NUM> at a narrowest diameter, and a length between <NUM> and <NUM>. In some configurations, proximal plug <NUM> has a length between <NUM> and <NUM> and an outside diameter between <NUM> and <NUM>.

In some configurations, the inflation stylet <NUM> includes an inflation tip <NUM> for delivering the fluid to the outer chamber <NUM>, the inflation tip <NUM> configured to be coupled to a distal end <NUM> of the inflation stylet <NUM>. Although <FIG> shows inflation stylet <NUM> coupled to an inflation tip <NUM>, some configurations of the inflation stylet <NUM> may omit one or more features, such as the inflation tip <NUM>, and still achieve similar functions. For example, distal end <NUM> of inflation stylet <NUM> can be configured to be coupled to the proximal plug <NUM>.

In some configurations, the proximal plug <NUM> includes a re-sealable membrane <NUM> to control fluid communication through the proximal opening <NUM> of the inner chamber <NUM>. In some configurations, the re-sealable membrane <NUM> has a thickness of between <NUM> and <NUM>. In this way, the re-sealable membrane prevents fluid from flowing around the first (contrast) lumen <NUM> and into the outer chamber <NUM>. The re-sealable membrane <NUM> can also serve as a one-way valve and prevent any backflow of fluid from the inner chamber <NUM> into the outer chamber <NUM> when a fluid is delivered into the inner chamber <NUM>. In this way, an inflation stylet <NUM>, described in more detail below, can be configured to communicate with the inner chamber <NUM> and the outer chamber <NUM> through a single opening and without the contents of each chamber mixing together.

In some configurations, as shown in <FIG>, the spinal implant device <NUM> further includes a distal plug <NUM> disposed in distal neck 118b to seal the distal opening <NUM>. Distal plug <NUM> may define a proximal cylindrical recess 186a at a proximal end of distal plug <NUM> for receiving a distal end 260b of the first (contrast) lumen <NUM> of inflation stylet <NUM>, and a distal cylindrical recess 186b at a distal end of distal plug <NUM>. Distal plug <NUM> may be made of silicone or another material that is compatible with enclosures <NUM>, <NUM>, and may be manufactured using conventional manufacturing techniques, such as injection molding. In some configurations, distal plug <NUM> has an outside diameter between <NUM> and <NUM>, and a length between <NUM> and <NUM>. In some configurations, the proximal cylindrical recess 186a has a diameter between <NUM> and <NUM>, and a length between <NUM> and <NUM>. In some configurations, the distal cylindrical recess 186b has a diameter between <NUM> and <NUM>, and a length between <NUM> and <NUM>. Although <FIG> show a distal plug <NUM>, one or more configurations of spinal implant device <NUM> may omit one or more features, such as the distal plug <NUM>.

In some configurations, such as the one shown in <FIG>, the spinal implant device <NUM> further includes a first radiopaque marker (e.g., tantalum marker bead) 188a coupled to either the distal plug <NUM> or a portion of the flexible body <NUM> that is closer to the distal opening <NUM> of the inner chamber <NUM> than to the proximal opening <NUM> of the inner chamber <NUM>. Although <FIG> shows a first radiopaque marker 188a, one or more configurations of spinal implant device <NUM> (e.g., <FIG>) may omit one or more features, such as the first radiopaque marker 188a.

In some configurations, such as the one shown in <FIG>, the spinal implant device <NUM> further includes a second radiopaque marker (e.g., tantalum marker bead) 188b coupled to either the proximal plug <NUM> or a portion of the flexible body <NUM> that is closer to the proximal opening <NUM> of the inner chamber <NUM> than to the distal opening <NUM> of the inner chamber <NUM>. Although <FIG> shows a second radiopaque marker 188b, one or more configurations of spinal implant device <NUM> (e.g., <FIG>) may omit one or more features, such as the second radiopaque marker 188b. In some configurations, the outer chamber <NUM> is filled with a curable medium <NUM> (e.g., curable silicone material). In some configurations, the curable medium <NUM> contains a radiographic material <NUM> (identified as the black dots within outer chamber <NUM> in <FIG>). In some configurations, the radiographic material <NUM> contains <NUM> to <NUM> wt. % of barium sulfate. In some configurations, the curable medium <NUM> substantially cures within ten minutes. In some configurations, the curable medium <NUM> is substantially de-gassed prior to delivery into the outer chamber <NUM>. In some configurations, a retaining element <NUM> for retaining the spinal implant device <NUM> on the inflation stylet <NUM> is provided.

Referring now to <FIG>, in some configurations inflation stylet <NUM> may be used in conjunction with a delivery sheath <NUM> to deliver and deploy spinal implant device <NUM>. Inflation stylet <NUM> includes a shaft <NUM> with a proximal end <NUM> and a distal end <NUM>. A first (contrast) lumen <NUM> and a second (silicone) lumen <NUM> extend through shaft <NUM>. The distal ends of first and second lumens <NUM>, <NUM> can be coupled to an inflation tip <NUM> that can be configured to mate with proximal plug <NUM>. For example, as shown in <FIG>, <FIG>, and <FIG>, the inflation tip <NUM> can be configured to include a retaining element <NUM> (e.g., key or groove) that can aid in physically preventing improper installation of inflation stylet <NUM>. In this way, retaining element <NUM> may be used to control the insertion depth of inflation tip <NUM>. In some embodiments, retaining element <NUM> can be used as a locking feature to help prevent inadvertent dislodgment of inflation stylet <NUM> from proximal plug <NUM>. For example, as best shown in <FIG>, proximal plug <NUM> may be configured with receptacle <NUM> adapted to mate with retaining element <NUM> on inflation tip <NUM> such that inflation tip is prevented from dislodging out of the proximal plug <NUM> prior to deployment. In some configurations, retaining element <NUM> can have a diameter between <NUM> and <NUM> at a widest point.

In some configurations, inflation tip <NUM> comprises stainless steel (e.g., <NUM> stainless steel). In some configurations, inflation tip <NUM> defines a proximal tip opening <NUM> that aligns with first (contrast) lumen <NUM> when coupled to distal end <NUM> of inflation stylet <NUM>. In some configurations, proximal tip opening <NUM> has a diameter between <NUM> to <NUM>.

Referring now to <FIG> and <FIG>, first (contrast) lumen <NUM> extends from proximal end <NUM> of inflation stylet <NUM> to distal end <NUM> of inflation tip <NUM>. First (contrast) lumen <NUM> extends out the proximal end of inflation stylet <NUM>. In some configurations, first (contrast) lumen <NUM> can be independently movable with respect to inflation stylet <NUM> so that the position of the distal end 260b of first (contrast) lumen <NUM> may be extended and withdrawn with respect to the distal end <NUM> of inflation stylet <NUM>. For delivery prior to implantation, first (contrast) lumen <NUM> can extend through re-sealable membrane <NUM> and the distal end 260b of first (contrast) lumen <NUM> can be positioned within the inner chamber <NUM> to deliver fluidic medium <NUM> (e.g., contrast medium). First (contrast) lumen <NUM> can be used to both deliver and remove fluids from inner chamber <NUM>. In some configurations, distal end 260b of first (contrast) lumen <NUM> can be pre-formed using shape memory material into a shape that allows easier delivery and/or removal of fluid from inner chamber <NUM>. For example, in one specific configuration, first (contrast) lumen <NUM> can be pre-formed into a curved shape that allows easier access to the bottom (or top) of inner chamber <NUM>. The curved shape, combined with the ability to extend and withdraw first (contrast) lumen <NUM> allows it to be adjusted when used to withdraw fluid from inner chamber <NUM>. It should be understood that as used herein, "first (contrast) lumen" should be understood to mean a lumen for delivery of any desired fluid to inner chamber <NUM>, and can encompass materials other than contrast medium. Contrast medium may be used to ensure visibility under imaging, such as fluoroscopy.

As best shown in <FIG>, when inflation stylet <NUM> is mated with proximal plug <NUM>, the inflation tip aperture 172a is in fluid communication with the distal end 264b of second (silicone) lumen <NUM> and coincident with plug aperture <NUM> of proximal plug <NUM> to allow fluid communication between the outer chamber <NUM> and second (silicone) lumen <NUM> through the body aperture <NUM> of outer chamber <NUM>. When inflation tip <NUM> is coupled to distal end <NUM> of inflation stylet <NUM>, curable silicone material <NUM> can be delivered through inflation tip aperture 172a when plug aperture <NUM> and body aperture <NUM> are aligned. In some configurations, inflation tip aperture 172a has a diameter between <NUM> and <NUM>. Proximal end 260a of first (contrast) lumen <NUM> and proximal end 264a of second (silicone) lumen is provided with a connector <NUM> (e.g., luer connector) for connection to common inflation tools (e.g., syringes) known to those of skill in the art.

In some configurations, as best shown in <FIG>, inflation stylet <NUM> further includes a vent lumen <NUM> in fluid communication with the second (silicone) lumen <NUM>. In this way, vent lumen <NUM> may be provided to allow air to exit second (silicone) lumen <NUM> when silicone or another suitable material is delivered to outer chamber <NUM>. Vent lumen <NUM> may be configured to be large enough to allow air to freely move through it, while resisting more viscous fluids such as curable silicone (e.g., <NUM>). In some configurations, the curable silicone material <NUM> is substantially de-gassed prior to delivery into the outer chamber <NUM>. It should be understood that as used herein, "second (silicone) lumen" means a lumen for delivery of any desired fluid to outer chamber <NUM>, and can encompass materials other than silicone or curable silicone, including, but not limited to, curable silicone blends containing barium sulfate. Vent lumen <NUM> preferably extends through shaft <NUM> to vent to atmosphere at the proximal end <NUM> of inflation stylet <NUM>.

Referring now to <FIG>, a delivery sheath <NUM> includes a lumen <NUM> sized to fit over shaft <NUM> of inflation stylet <NUM>. To deliver spinal implant device <NUM>, the spinal implant device <NUM> is coupled to inflation tip <NUM>, and the assembled bodies are withdrawn into the distal end of delivery sheath <NUM>.

Referring to <FIG> and <FIG>, spinal implant device <NUM> may be formed by forming an elastomeric spinal implant blank <NUM>, which comprises outer fillable enclosure <NUM> coupled to inner fillable enclosure <NUM>. Spinal implant blank <NUM> may be manufactured using conventional manufacturing techniques, such as, but not limited to, injection molding or dip molding. In some implementations, a multi-piece mandrel can be used to form the spinal implant blank <NUM>. In some implementations, the wall thickness of the outer fillable enclosure <NUM> and inner fillable enclosure <NUM> may be formed using the multi-piece mandrel to have varying wall thicknesses effective to achieve certain desired properties and/or functions. The multi-piece mandrel may be configured to have varying thicknesses and geometries to achieve the desired properties and/or functions for the spinal implant device <NUM>. For example, the inner fillable enclosure <NUM> may be formed to have a wall thickness less than the outer fillable enclosure <NUM> to allow easier filling and expansion of the inner chamber <NUM> relative to the outer chamber <NUM>. After spinal implant blank <NUM> is formed, spinal implant blank <NUM> is partially inverted, as shown in <FIG>, to place inner fillable enclosure <NUM> into the interior of outer fillable enclosure <NUM>. Distal plug <NUM> can then be inserted into distal neck 118b, and proximal plug <NUM> can then be inserted into proximal neck 118a. Inflation tip <NUM> can then be coupled to the proximal plug <NUM> and a guidewire inserted into inflation tip <NUM> and extending through inflation tip aperture 172a to pierce an opening to form body aperture <NUM>. In some configurations, spinal implant blank <NUM> includes a proximal neck 118a having a diameter between <NUM> and <NUM>; a distal neck 118b having a diameter between <NUM> and <NUM>; an inner fillable enclosure having a diameter of between <NUM> and <NUM> at a widest diameter around a longitudinal axis <NUM>; and an outer fillable enclosure having a diameter between <NUM> and <NUM> at a widest diameter around the longitudinal axis <NUM>. In some configurations, spinal implant blank <NUM> has a total length between <NUM> and <NUM>. In some configurations, the thickness of the outer wall of proximal neck 118a is between <NUM> and <NUM>. In some configurations, the thickness of the outer wall of distal neck 118b is between <NUM> and <NUM>.

Additional details regarding one example of a manufacturing technique are disclosed in co-pending application <CIT>. In some implementations of the method of manufacturing, the spinal implant blank <NUM> may be stripped from the mandrel by separating the multi-piece mandrel to prevent tearing of the spinal implant blank <NUM> as the blank is removed from the mandrel.

Referring now to <FIG>, in some implementations, a method (not claimed) of replacing a nucleus pulposus <NUM> of an intervertebral disc <NUM> with a spinal implant device (e.g., <NUM>) comprises dilating the annulus fibrosus <NUM> to gain access to an intervertebral disc <NUM> while leaving annulus fibrosus <NUM> substantially intact. Preferably, accessing the intervertebral disc <NUM> is performed using minimally invasive surgical techniques, such as percutaneous techniques, which uses an access cannula <NUM> to access the intervertebral disc cavity <NUM> through a small opening in annulus fibrosus <NUM>. In some implementations, the intervertebral disc cavity <NUM> is accessed using a posterolateral approach through Kambin's triangle using a lateral transpsoas open surgical approach to the L5-S1 lumbar spinal disc nucleus pulposus <NUM>. In some implementations, an anterior approach may also be used. In some implementations, the intervertebral disc cavity <NUM> is access using a lateral transpsoas open surgical approach to the L1-L5 lumbar spinal disc nucleus pulposus <NUM> (when anatomy permits), and a retroperitoneal (i.e., anterolateral) open surgical approach to the L5-S1 lumbar spinal disc nucleus pulposus <NUM>.

As best shown in <FIG>, to preserve the integrity of the annulus fibrosus <NUM> as much as possible, access through the annulus fibrosus <NUM> may be created by controlled dilation of the annulus fibrosus <NUM> by inserting a guide pin (e.g., a K-wire) and then a series of increasing diameter dilators <NUM> placed over the guide pin (not shown). Once the desired diameter is obtained, the access cannula <NUM> is placed over the largest diameter dilator <NUM>, and the dilator set <NUM> is removed. In some configurations, the intervertebral disc access system can include a first dilator having an outside diameter of about <NUM>; a second dilator having an outside diameter of about <NUM>; a third dilator having an outside diameter of about <NUM>; and, a fourth dilator having an outside diameter of about <NUM>. In some configurations, the disc access system can include dilators sized to be particularly suited for a surgical technique (e.g., minimally invasive surgery, percutaneous surgery, robotic surgery, and/or robotics-assisted surgery). The tip of the first dilator is placed on the midpoint of the craniocaudal dimension of the annulus fibrosus <NUM>. Fluoroscopy can be used to ensure good position of the dilator (e.g., when access starts at the midpoint of the craniocaudal dimension of the intervertebral disc margin, parallel to the vertebral end plates <NUM> and with a trajectory that will facilitate total nucleus pulposus <NUM> removal). Dilation of the annulus fibrosus <NUM> is then started by advancing the first dilator, as shown in <FIG>, with a gentle rotation of the dilator, and confirmation of position can be obtained with fluoroscopy. The second, third, and fourth dilators can be advanced similarly (<FIG>, respectively) and confirmed under fluoroscopy to ensure that the dilators <NUM> are not advanced beyond the margin of the inner annulus fibrosus <NUM> opposite the access site. Once the largest dilator is in place, the dilators <NUM> may be removed in its entirety to allow for the passage of conventional surgical instruments (e.g., rongeurs) for removal of the nucleus pulposus <NUM>. To ensure safety of subsequent steps, access cannula <NUM> may be advanced over the largest dilator prior to dilator removal to secure the access into the intervertebral disc cavity <NUM>. Access cannula <NUM> should not be placed further than the midline of the intervertebral disc space. This procedure gradually spreads the fibrous bands of the annulus fibrosus <NUM> to create access to the nucleus pulposus <NUM> without excising (i.e., removing, tearing, or otherwise harming) any tissue, which aids in the healing process and successful deployment of the implantable nuclear prosthesis.

Once the nucleus pulposus <NUM> is reached, a nuclectomy is then performed with any suitable surgical instrument (e.g., rongeurs) to create an enucleated intervertebral disc cavity <NUM>. Once the existing nucleus pulposus <NUM> has been removed to the satisfaction of the physician, annulus fibrosus <NUM> and vertebral end plates <NUM> form a substantially empty enucleated intervertebral disc cavity <NUM> as shown in <FIG>.

Referring now to <FIG>, any one of the configurations of present spinal implant devices (e.g., <NUM>), including configurations of a dual-chambered spinal implant device, can then be inserted into the enucleated intervertebral disc cavity <NUM>. The dual- chambered spinal implant device can have an inner chamber that is at least partially surrounded by an outer chamber, and configured such that the inner chamber provides pressure feedback when the outer chamber is filled. The spinal implant device <NUM>, which is loaded into a delivery sheath <NUM>, is placed into enucleated disc cavity <NUM> through access cannula <NUM>, as shown in <FIG>. Typically, the spinal implant device <NUM> will be delivered to the far end of the enucleated intervertebral disc cavity <NUM>. The delivery sheath <NUM> is then withdrawn to expose the spinal implant device <NUM> inside the enucleated intervertebral disc cavity <NUM>.

As shown in <FIG>, the inflation stylet <NUM> is then used to fill the inner chamber <NUM> with a fluidic medium <NUM> (e.g., contrast medium). Inner chamber <NUM> can be filled with a threshold volume (e.g., <NUM> of contrast medium), or until the inner chamber <NUM> reaches a threshold volume sufficient to provide pressure feedback. In some implementations, a substantially incompressible fluid is used, such as a contrast medium. Prior to inflating the inner chamber <NUM>, air should be purged from the system using, for example, a vacuum locking syringe. Fluidic medium <NUM> (e.g., contrast medium) is then delivered through first (contrast) lumen <NUM> of inflation stylet <NUM>. In some implementations, the inner chamber <NUM> is filled with contrast medium to a threshold volume between <NUM> to <NUM>.

As shown in <FIG>, inflation stylet <NUM> is then used to deliver a curable medium <NUM> to outer chamber <NUM>, thereby inflating the outer chamber <NUM> to a threshold pressure (e.g., 276kPA (<NUM> psi)). The pressure applied from the outer chamber <NUM> to the inner chamber <NUM> during delivery of the curable medium <NUM> is monitored as pressure feedback to ensure the threshold pressure is not exceeded. Curable medium <NUM> is preferably an elastomeric material, such as silicone rubber containing a radiopaque material (e.g., barium sulfate). In some implementations, the curable medium <NUM> contains silicone and an effective amount of a radiopaque material making the curable medium <NUM> radiopaque and having a viscosity that permits flow into the outer chamber. In some implementations, the curable medium <NUM> contains silicone and <NUM> to <NUM> wt. % of barium sulfate. In some implementations, delivery of curable medium <NUM> to outer chamber <NUM> is performed under continuous fluoroscopic control and delivered slowly to permit intermittent verification of the exit of the curable medium <NUM> into the outer chamber <NUM>, monitoring of delivery pressure to ensure delivery pressure does not exceed a threshold pressure (e.g., <NUM> kPa (<NUM> psi)), monitoring distribution of curable medium <NUM> and checking for any possible extra-discal diffusion. In some implementations, the threshold pressure can be between <NUM> kPa (<NUM> psi) to <NUM> kPa (<NUM> psi). Inflation pressure can be monitored with a pressure monitoring device such as, for example, the QL° inflation device (ATRION° Medical). In some implementations, it is not necessary to evacuate air from the outer chamber <NUM> because of the presence of the vent lumen <NUM>. Curable medium <NUM> may be chosen so that it polymerizes with the material of outer and inner fillable enclosures <NUM>, <NUM> to form a unitary member. The modulus of elasticity and other characteristics of curable medium <NUM> can be selected based upon patient specific parameters. For example, younger, more active patients may require a firmer material than less mobile geriatric patients.

As shown in <FIG>, once outer chamber <NUM> is filled to a threshold pressure, curable medium <NUM> is allowed to cure. In some implementations, the curable medium <NUM> contains curable silicone which substantially cures in a short period of time, for example, about <NUM> minutes or less. The use of shorter curing periods may help prevent the dissolution of solvent from the curable medium <NUM> to the fillable enclosures which may occur with longer curing mediums. Such leaching of solvents may adversely affect the structural integrity of the fillable enclosures.

After curable medium <NUM> is allowed to cure, the fluidic medium <NUM> (e.g., contrast medium) from the inner chamber <NUM> is removed using first (contrast) lumen <NUM>. As previously discussed, first (contrast) lumen <NUM> may be moved and/or manipulated to remove as much contrast medium as is desired. Preferably, substantially all of the contrast medium is removed; however, some contrast medium will likely remain and it is not necessary to remove all of the contrast medium. In some configurations, the inner fillable enclosure <NUM> is then left vented so that fluids may enter and exit the inner fillable enclosure <NUM>. Once contrast medium has been removed and curable medium <NUM> is sufficiently cured, inflation stylet <NUM> can be rotated up to <NUM> degrees to de-couple the spinal implant device <NUM> from the inflation stylet <NUM>. The inflation stylet <NUM> can then be withdrawn through access cannula <NUM>, and access cannula <NUM> can subsequently be removed.

As shown in <FIG>, in the implanted state, the spinal implant device <NUM> comprises an annular ring of cured material <NUM> surrounding hollow inner chamber <NUM>. This structure allows for vertical and horizontal load stresses placed on the intervertebral disc space to be redirected inward, centrally toward inner chamber <NUM> (see direction arrows of <FIG>) instead of outward. Moreover, the expansion ability of spinal implant device <NUM> as the outer chamber <NUM> is filled allows spinal implant device <NUM> to effectively bridge any defects in the annulus fibrosus <NUM>. Upon removal of access cannula <NUM>, the fibers of the annulus fibrosus <NUM> realign to preserve annulus fibrosus integrity.

In some implementations, as shown in <FIG>, after performing the nuclectomy, an imaging balloon (e.g., a first imaging balloon 228a) is inserted into the enucleated intervertebral disc cavity <NUM> and inflated with a radiopaque fluid <NUM> to assess completeness of the nuclectomy. The nuclectomy is repeated as needed to remove any remaining nucleus pulposus <NUM>. The inflating and nuclectomy steps are repeated until the enucleated intervertebral disc cavity <NUM> has been sufficiently enucleated. In some implementations, first imaging balloon 228a can include an inflatable elastomeric material having a durometer of between Shore 10A to Shore 100A (e.g., Shore 20A). First imaging balloon 228a can be inserted into access cannula <NUM> and advanced to position the first imaging balloon 228a within the enucleated intervertebral disc cavity <NUM>. Radiopaque fluid <NUM> (e.g., contrast medium) can be delivered through the first (contrast) lumen <NUM> to inflate first imaging balloon 228a to a threshold pressure (e.g., <NUM> kPa (<NUM> psi)). In some implementations, the threshold pressure is not to exceed <NUM> kPa (<NUM> psi) for repeated imaging to assess the nuclectomy. Inflation pressure can be monitored with a pressure monitoring device such as, for example, the QL° inflation device (ATRION° Medical). Assessment of the completeness of the nuclectomy can then be performed under fluoroscopic guidance and repeated until a satisfactory total nucleus removal has been accomplished.

In some implementations, as shown in <FIG>, the first imaging balloon 228a is inflated with a radiopaque fluid <NUM> to interrogate the enucleated intervertebral disc cavity <NUM> for defects and/or contraindications <NUM> (e.g., tear(s) in the annulus fibrosus, herniations, Schmorl's node, or other end plate defects). As shown in <FIG>, first imaging balloon 228a has identified a small tear during the interrogation step. As shown in <FIG>, first imaging balloon has identified a herniation and has expanded to extend between and through the herniation during the interrogation step. Once the user determines whether there are any defects and/or contraindications <NUM> for implanting the spinal implant device <NUM>, the first imaging balloon 228a is removed. In some configurations, first imaging balloon 228a can include an inflatable elastomeric material having a durometer of between Shore 10A to Shore 60A (e.g., Shore 20A). First imaging balloon 228a can be inserted into access cannula <NUM> and advanced to position the first imaging balloon 228a within the enucleated intervertebral disc cavity <NUM>. Radiopaque fluid <NUM> (e.g., contrast medium) can be delivered through the first (contrast) lumen <NUM> to inflate first imaging balloon 228a to a threshold pressure (e.g., <NUM> kPa (<NUM> psi)). The radiopaque fluid <NUM> can be a substantially incompressible fluid. In some implementations, the threshold pressure is not to exceed <NUM> kPa (<NUM> psi) for confirmation of the integrity of the annulus fibrosus <NUM>. Inflation pressure can be monitored with a pressure monitoring device such as, for example, the QL° inflation device (ATRION° Medical).

In some implementations, as shown in <FIG>, if there are no defects and/or contraindications <NUM>, the method proceeds by inserting a second imaging balloon 228b having a durometer corresponding to a durometer of the spinal implant device <NUM> or a durometer greater than the durometer of the first imaging balloon 228a; inflating the second imaging balloon 228b with a radiopaque fluid <NUM> to a threshold pressure; monitoring a volume of the radiopaque fluid <NUM> to determine an approximate fill volume for the spinal implant device <NUM>; imaging the second imaging balloon 228b to determine a size for the spinal implant device <NUM>; and removing the second imaging balloon 228b. In some configurations, second imaging balloon 228b can include an inflatable elastomeric material having a durometer of between Shore 45A to Shore 55A (e.g., Shore 50A). Second imaging balloon 228b can be inserted into access cannula <NUM> and advanced to position the second imaging balloon 228b within the enucleated intervertebral disc cavity <NUM>. Radiopaque fluid <NUM> (e.g., contrast medium) can be delivered through the first (contrast) lumen <NUM> to inflate second imaging balloon 228b to a threshold pressure (e.g., <NUM> kPa (<NUM> psi)). In some implementations, the threshold pressure is not to exceed <NUM> KPa (<NUM> psi) for using the second imaging balloon 228b as a cross reference during the fill of spinal implant device <NUM>. Inflation pressure can be monitored with a pressure monitoring device such as, for example, the QL° inflation device (ATRION° Medical). In some implementations, the same imaging balloon can be used for assessing the nuclectomy, interrogating the enucleated intervertebral disc cavity <NUM> for defects and/or contraindications <NUM>, and determining a size and fill volume for the spinal implant device <NUM>. The imaging balloon can have a durometer between Shore 10A and Shore 100A.

In some implementations, the method includes imaging one or more views of the inflated imaging balloon; imaging one or more views of the spinal implant device corresponding to the one or more views imaged of the inflated imaging balloon; and, comparing the one or more views of the spinal implant device with the one or more views of the inflated imaging balloon to assess the spinal implant device. The one or more views of the inflated imaging balloon may be taken in a series of specified views. The one or more views of the imaging balloon and/or the one or more views of the spinal implant device may comprise indicia to quantify congruency between two of the same views. In this way, the position, orientation, and size of the spinal implant device can be confirmed manually. The imaging and comparing steps may also be performed electronically, and may include the step of automatically determining a percentage of overlap between two views. In this way, the position, orientation, and size of the spinal implant device can be confirmed automatically with software suited for determining the percentage of overlap between two views. Using software to automatically image and compare can provide certain advantages such as reduced surgical time and a more effective deployment of the spinal implant device. Further, automatically determining a percentage of overlap between two views can be particularly suited for use with robotic surgery and/or robotics-assisted surgery to insert the spinal implant device. A three-dimensional model may be generated from the first set of views of the imaging balloon and/or the second set of views of the spinal implant device. The three-dimensional model of the imaging balloon and/or the three-dimensional model of the spinal implant device may be used to estimate a fill volume for the spinal implant device. The three-dimensional model of the imaging balloon and/or the three-dimensional model of the spinal implant device may be used to determine a percentage of overlap.

At least some of the present configurations also include a kit for implanting a nuclear prosthesis. The kit can include any configuration of the present spinal implant devices, inflation stylets, plugs, inflation tips, imaging balloons, delivery sheaths, curable materials, spinal disc access devices, spinal implant fill devices, dispenser guns, dual-syringe barrels, mixing tips, and inflation pressure gauges; or, the kit can include any combination of each of the foregoing configurations.

For example, in some configurations a dispenser gun can be configured to couple to the proximal end of the inflation stylet for delivery of a two-part curable silicone material. In some configurations, the curable silicone material <NUM> is substantially de-gassed prior to delivery into the outer chamber <NUM>. In some configurations, the dispenser gun is a manually activated dispenser providing separated cartridge outlets and mixer inlets, for the delivery of volumetric ratios of material. In this way, the dispenser gun can prevent cross-contamination and premature curing of the curable silicone material <NUM> in the outlet/inlet area. In some configurations, the dispenser gun is configured to accept a dual-syringe cartridge that contains a first part of a curable medium (e.g., Part A) in a first cartridge and a second part (e.g., Part B) of a curable medium in a second cartridge. In some configurations, a mixing tip can be coupled to the dual-syringe cartridge. In this way, mixing tip can aid in ensuring even mixing of Part A and Part B of the two-part curable silicone material.

The above specification and examples provide a complete description of the structure and use of exemplary configurations. Although certain configurations have been described above with a certain degree of particularity, or with reference to one or more individual configurations, those skilled in the art could make numerous alterations to the disclosed configurations without departing from the scope of this invention. As such, the various illustrative configurations of the present devices, apparatuses, kits, and methods (not claimed) are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and configurations other than the one shown may include some or all of the features of the depicted configuration. For example, components may be combined as a unitary structure, and/or connections may be substituted. Similarly, it will be understood that the benefits and advantages described above may relate to one configuration or may relate to several configurations.

Claim 1:
A kit for implanting a nuclear prosthesis, the kit comprising:
a spinal implant device (<NUM>) comprising:
a flexible body (<NUM>) defining:
an outer fillable enclosure (<NUM>) defining an outer chamber (<NUM>) having a body aperture (<NUM>); and
an inner fillable enclosure (<NUM>) defining an inner chamber (<NUM>) such that the outer fillable enclosure (<NUM>) at least partially surrounds the inner fillable enclosure (<NUM>), the inner fillable enclosure (<NUM>) having an opening (<NUM>) in fluid communication with the inner chamber (<NUM>);
a proximal plug (<NUM>) configured to be coupled to the inner fillable enclosure (<NUM>) such that the proximal plug (<NUM>) controls fluid communication through the opening (<NUM>), the proximal plug (<NUM>) defines a receptacle (<NUM>) including a plug aperture (<NUM>) and including a re-sealable membrane (<NUM>) to control fluid communication through a proximal opening (<NUM>) of the inner chamber (<NUM>), the receptacle (<NUM>) configured to couple with a retaining element (<NUM>) of an inflation stylet (<NUM>), wherein the plug aperture (<NUM>) is positioned between the retaining element (<NUM>) and the re-sealable membrane (<NUM>) when the proximal plug (<NUM>) is mated with the inflation stylet (<NUM>) and is configured to enable fluid communication to the outer fillable enclosure (<NUM>);
the inflation stylet (<NUM>) configured to mate with the proximal plug (<NUM>) and extend at least partially through the proximal plug (<NUM>), the inflation stylet (<NUM>) comprising:
a first lumen (<NUM>) configured to deliver a fluid (<NUM>) to and remove a fluid (<NUM>) from the inner chamber (<NUM>);
a second lumen (<NUM>) at least partially surrounding the first lumen (<NUM>) and configured to deliver a fluid (<NUM>) to the outer chamber (<NUM>); and
the retaining element (<NUM>) configured to control insertion depth of the inflation stylet (<NUM>) and to secure the inflation stylet (<NUM>) to the proximal plug (<NUM>).