Patent Description:
Traumatic, inflammatory, and degenerative disorders of the spine can lead to severe pain and loss of mobility. One source of back and spine pain is related to degeneration of the facets of the spine or facet arthritis. Bony contact or grinding of degenerated facet joint surfaces can play a role in some pain syndromes. While many technological advances have focused on the intervertebral disc and artificial replacement or repair of the intervertebral disc, little advancement in facet repair has been made. Facet joint and disc degeneration frequently occur together. Thus, a need exists to address the clinical concerns raised by degenerative facet joints.

The current standard of care to address the degenerative problems with the facet joints is to fuse the two adjacent vertebrae. By performing this surgical procedure, the relative motion between the two adjacent vertebrae is stopped, thus stopping motion of the facets and any potential pain generated as a result thereof. Procedures to fuse two adjacent vertebrae often involve fixation and/or stabilization of the two adjacent vertebrae until the two adjacent vertebrae fuse.

Injuries and/or surgical procedure on and/or effecting other bones can also result in the desire to fixate and/or stabilize a bone until the bone, or bone portions, can fuse, for example, to stabilize a sternum after heart surgery, to stabilize a rib after a break, etc. Current procedures to fixate and/or stabilize adjacent vertebrae and/or other bones can be slow and/or complex.

Accordingly, a need exists for an apparatus and a procedure to quickly and/or easily stabilize and/or fixate a bone.

The present invention relates to a vertebral facet joint fusion implant and a kit comprising the implant and a fastener as claimed hereafter. Preferred embodiments of the invention are set forth in the dependent claims. Associated methods are also described herein to aid understanding of the invention, but these do not form part of the claimed invention.

The invention is illustrated in the <FIG>, <FIG> and <FIG>. The remaining figures illustrate examples that are useful for understanding the invention.

In some examples, a not claimed method comprises disposing an implant into contact with a first bone portion and into contact with a second bone portion, the implant having (<NUM>) a first interface configured to receive a restraining member, and (<NUM>) a second interface. The method further comprises inserting a portion of the fastener member into the first interface. The method further comprises securing the fastener member such that the first bone portion and the second bone portion are fixed to each other, at least in part by a substance after the securing, at least a portion of the substance disposed through the second interface.

In some embodiments an apparatus includes an implant having a face, a first interface, and a second interface. The face is shaped to substantially compliment a shape of a first bone portion, the first interface is configured to receive a fastener member, and the second interface configured to receive a substance. The implant is configured to be secured with the fastener member such that the first bone portion and a second bone portion are fused to each other, at least in part by the substance after the implant is secured by the fastener member. At least a portion of the substance disposed through the second interface.

In some embodiments a kit includes a fastener member, a substance, and an implant. The implant can include a first interface configured to receive a the fastener member, and a second interface configured to receive a the substance. The implant is configured to be secured with the fastener member such that a first bone portion and a second bone portion are fused to each other, at least in part by the substance after being secured, at least a portion of the substance disposed through the second interface. The fastener member is configured to secure the implant to the first bone portion and to the second bone portion. The substance configured to fuse the first bone portion to the second bone portion through the second interface.

As used in this specification, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, the term "a ratchet" is intended to mean a single ratchet or a combination of ratchets. As used in this specification, a substance can include any biologic and/or chemical substance, including, but not limited to, medicine, adhesives, etc, and/or a bone graft, including, but not limited to, autograft, allograft, xenograft, alloplastic graft, a synthetic graft, and/or combinations of grafts, medicines, and/or adhesives. While exemplary references are made with respect to vertebra, in some embodiments another bone can be involved. While specific reference may be made to a specific vertebra and/or subset and/or grouping of vertebrae, it is understood that any vertebra and/or subset and/or grouping, or combination of vertebrae can be used.

As shown in <FIG>, the vertebral column <NUM> comprises a series of alternating vertebrae <NUM> and fibrous discs <NUM> that provide axial support and movement to the upper portions of the body. The vertebral column <NUM> typically comprises thirty-three vertebrae <NUM>, with seven cervical (C1-C7), twelve thoracic (T1-T12), five lumbar (L1-<NUM>), five fused sacral (S1-S5) and four fused coccygeal vertebrae. <FIG> depict a typical thoracic vertebra. Each vertebra includes an anterior body <NUM> with a posterior arch <NUM>. The posterior arch <NUM> comprises two pedicles <NUM> and two laminae <NUM> that join posteriorly to form a spinous process <NUM>. Projecting from each side of the posterior arch <NUM> is a transverse <NUM>, superior <NUM> and inferior articular process <NUM>. The facets <NUM>, <NUM> of the superior <NUM> and inferior articular processes <NUM> form facet joints <NUM> with the articular processes of the adjacent vertebrae (see <FIG>). The facet joints are true synovial joints with cartilaginous surfaces and a joint capsule.

The orientation of the facet joints vary, depending on the level of the vertebral column. In the C1 and C2 vertebrae, for example the facet joints are parallel to the transverse plane. <FIG> depict examples of the orientations of the facet joints at different levels of the vertebral column. In the C3 to C7 vertebrae examples shown in <FIG>, the facets are oriented at a <NUM>-degree angle to the transverse plane <NUM> and parallel to the frontal plane <NUM>, respectively. This orientation allows the facet joints of the cervical vertebrae to flex, extend, lateral flex and rotate. At a <NUM>-degree angle in the transverse plane <NUM>, the facet joints of the cervical spine can guide, but do not limit, the movement of the cervical vertebrae. <FIG> depict examples of the thoracic vertebrae, where the facets are oriented at a <NUM>-degree angle to the transverse plane <NUM> and a <NUM>-degree angle to the frontal plane <NUM>, respectively. This orientation is capable of providing lateral flexion and rotation, but only limited flexion and extension. <FIG> illustrate examples of the lumbar region, where the facet joints are oriented at <NUM>-degree angles to the transverse plane <NUM> and a <NUM>-degree angle to the frontal plane <NUM>, respectively. The lumbar vertebrae are capable of flexion, extension and lateral flexion, but little, if any, rotation because of the <NUM>-degree orientation of the facet joints in the transverse plane. The actual range of motion along the vertebral column can vary considerably with each individual vertebra.

In addition to guiding movement of the vertebrae, the facet joints also contribute to the load-bearing ability of the vertebral column. One study by <NPL>, found facet joint load-bearing as high as <NUM>% in some positions of the vertebral column. The facet joints may also play a role in resisting shear stresses between the vertebrae. Over time, these forces acting on the facet joints can cause degeneration and arthritis.

In some embodiments described herein, a vertebral facet joint implant can be used to stabilize, fixate, and/or fuse a first vertebra to a second vertebra to reduce pain, to reduce further degradation of a spine, or of a specific vertebra of a spine, and/or until the first vertebra and the second vertebra have fused. In some embodiments, the vertebral facet joint implant can be implanted and deployed to restore the space between facets of a superior articular process of a first vertebra and an inferior articular process of an adjacent vertebra. In some embodiments, the vertebral facet joint implant can be implanted and deployed to help stabilize adjacent vertebrae with adhesives, and/or can be implanted and deployed to deliver a medication. <FIG> depicts a block diagram of a vertebral facet joint implant ("implant") <NUM>. Implant <NUM> includes a first side <NUM>, a second side <NUM>, a fastener interface <NUM>, and a substance interface <NUM>. <FIG> depict implants and fasteners according to different examples.

As shown in <FIG>, implant <NUM> can be, for example, substantially disc shaped. First side <NUM> and/or second side <NUM> can be, for example, convex, concave, or flat. Said another way, first side <NUM> can be concave, convex, or flat, and second side <NUM> can be concave, convex, or flat; for example, first side <NUM> can be concave and second side <NUM> can be concave, first side <NUM> can be concave and second side <NUM> can be convex, etc. In such embodiments, the shape can be determined based on a shape of a bone portion that the first side <NUM> and/or the second side <NUM> is configured to contact. Said another way, the first side <NUM> and/or the second side <NUM> is shaped to substantially compliment the shape of a bone portion. On other words, the first side <NUM> or the second side <NUM> need not exactly match the shape of the corresponding bone portion, but instead can have a concave shape for a bone portion with a generally convex shape where the contact with the implant is to occur or can have a convex shape for a bone portion with a generally concave shape where the contact with the implant is to occur. Implant <NUM> can include any biocompatible material, e.g., stainless steel, titanium, PEEK, nylon, etc..

Implant <NUM> includes fastener interface <NUM>. Fastener interface <NUM> can be configured to retain implant <NUM> in substantially the same position. Specifically, fastener interface <NUM> can be configured to accept a fastener member (not shown) to substantially prevent movement of implant <NUM>. Fastener interface <NUM> can include an aperture and/or other opening. Fastener interface <NUM> can extend through implant <NUM>, e.g. can extend from first side <NUM> and through to second side <NUM>. In some embodiments, fastener interface <NUM> can extend through only a portion of implant <NUM>, e.g. can extend from first side <NUM> and through less than half of a width (not shown) of implant <NUM>. Fastener interface <NUM> can be disposed on and/or through first side <NUM>, second side <NUM>, and/or both first side <NUM> and second side <NUM>. Fastener interface <NUM> can be disposed through a center (not shown) of implant <NUM>. In other embodiments, fastener interface <NUM> can be disposed anywhere on and/or through implant <NUM>, e.g., offset from center. Fastener interface <NUM> can be substantially circular (cylindrical). In other embodiments, fastener interface <NUM> can be other shapes and/or can be shaped based on a shape of the fastener member, for example, rectangular (cuboid). In some embodiments. fastener interface <NUM> can be a irregular shape, based at least in part in the location of fastener interface <NUM>, see, e.g. <FIG>, and/or partial shapes, see, e.g. <FIG>. Fastener interface <NUM> can include a substantially smooth inner surface (not shown) to allow the fastener member to easily pass through and/or into fastener interface <NUM>, and/or can include a threaded inner surface to allow the fastener member to thread into fastener interface <NUM>. While depicted in <FIG> as including one fastener interface, implant <NUM> can include more than one fastener interface <NUM>.

Implant <NUM> includes substance interface <NUM>. Substance interface can be configured to retain, carry and/or otherwise deliver a substance to aid in fusion, such as, for example, medicines, adhesives, bone graft, and/or combinations of substances. Substance interface <NUM> can include an aperture and/or other opening. Substance interface <NUM> can extend through implant <NUM>, e.g. can extend from first side <NUM> and through to second side <NUM>. In some embodiments, fastener interface can extend through only a portion of implant <NUM>, e.g. can extend from first side <NUM> and through less than half of a width (not shown) of implant <NUM>. Substance interface <NUM> can be disposed on and/or through first side <NUM>, second side <NUM>, and/or both first side <NUM> and second side <NUM>. Substance interface <NUM> can be disposed through a center (not shown) of implant <NUM>. In other embodiments, substance interface <NUM> can be disposed anywhere on and/or through implant <NUM>, e.g., offset from center. Substance interface <NUM> can be substantially circular (cylindrical). In other embodiments, substance interface <NUM> can be other shapes and/or can be shaped based on a shape of the fastener member, for example, rectangular (cuboid). In some embodiments. substance interface <NUM> can be an irregular shape, based at least in part in the location of substance interface <NUM>. While depicted in <FIG> as including one substance interface, implant <NUM> can include more than one substance interface <NUM>. The location, size, shape, and/or number of substance interface(s) <NUM> can be determined based on the location, size, shape, and/or number of fastener interface(s) <NUM>.

In one example, a device for restoring the spacing between two facets of a facet joint is provided. As shown in <FIG>, the device comprises a implant <NUM> with a least two faces, a first face <NUM> adapted to contact the articular surface of one facet of the facet joint and a second face <NUM> adapted to contact the articular surface of the other facet. In one embodiment, the implant <NUM> has a generally circular profile and is sized to fit generally within the joint capsule of the facet joint <NUM>. <FIG> illustrates the implant <NUM> of <FIG> positioned in a facet joint. The implant can have any of a variety of profiles, including but not limited to square, rectangle, oval, star, polygon or combination thereof. An octagonal implant is shown in <FIG>. An implant having the desired shape is selected from an array of prostheses after radiographic visualization of the articular processes and/or by radio-contrast injection into the facet joint to visualize the joint capsule. The implant has a diameter of about <NUM> to about <NUM>. In another example, the implant has a diameter of about <NUM> to about <NUM>. In still another example, the implant has a diameter of about <NUM> to about <NUM>. In one example, the implant has a cross-sectional area of about <NUM><NUM> to about <NUM><NUM>. In another example, the implant has a cross-sectional area of about <NUM><NUM> to about <NUM><NUM>. In still another example, the implant has a cross-sectional area of about <NUM><NUM> to about <NUM><NUM>, or about <NUM><NUM>to about <NUM><NUM>.

The implant has a thickness generally equal to about the anatomic spacing between two facets of a facet joint. The implant generally has a thickness within the range of about <NUM> to about <NUM>. In certain examples, the implant has a thickness of about <NUM> to about <NUM>. In one preferred example, the implant has a thickness of about <NUM> to about <NUM>. In one example, the thickness of the implant is nonuniform within the same implant. For example, in <FIG>, the thickness of the implant <NUM> is increased around the entire outer edge <NUM>, along at least one and, as illustrated, both faces <NUM>, <NUM>. In <FIG>, only a portion of the edge <NUM> on one face <NUM> of the implant <NUM> has a thickness that is greater than the thickness of a central region, and, optionally, also thicker than the typical anatomic spacing between two facets of a facet joint. An increased edge thickness may resist lateral displacement of the implant out of the facet joint.

In some examples, the implant is configured to provide an improved fit with the articular process and/or joint capsule. For example, in <FIG>, the implant <NUM> has a bend, angle or curve <NUM> to generally match the natural shape of an articular facet. <FIG> depicts the implant of <FIG> positioned in a facet joint. The implant may be rigid with a preformed bend. Alternatively, the implant may be sufficiently malleable that it will conform post implantation to the unique configuration of the adjacent facet face. Certain examples, such as those depicted in <FIG> and <FIG>, the implant is configured to be implanted between the articular processes and/or within the joint capsule of the facet joint, without securing of the implant to any bony structures. Such embodiments can thus be used without invasion or disruption of the vertebral bone and/or structure, thereby maintaining the integrity of the vertebral bone and/or structure.

In one example, at least a portion of one surface of the implant is highly polished. A highly polished portion of the implant may reduce the surface friction and/or wear in that portion of the implant as it contacts bone, cartilage or another surface of the implant. A highly polished surface on the implant may also decrease the risk of the implant wedging between the articular surfaces of the facet joint, which can cause pain and locking of the facet joint.

In one example, shown in <FIG>, at least a portion of one surface of the implant <NUM> has a roughened surface <NUM>. A roughened surface may be advantageous when in contact with a bone or tissue surface because it may prevent slippage of the implant <NUM> against the bone and aid in maintaining the implant <NUM> in the joint. In one example, shown in <FIG>, at least a portion of one surface of the implant <NUM> has a porous surface <NUM>. A porous surface <NUM> can be created in any a variety of ways known in the art, such as by applying sintered beads or spraying plasma onto the implant surface. A porous surface <NUM> can allow bone to grow into or attach to the surface of the implant <NUM>, thus securing the implant <NUM> to the bone. In one example, an adhesive or sealant, such as a cyanoacrylate, polymethylmethacrylate, or other adhesive known in the art, is used to bond one face of the implant to an articular surface.

In one example, one surface of the implant is roughened or porous and a second surface that is highly polished. The first surface contacts or engages one facet of the facet joint and aids in maintaining the implant between the articular surfaces. The second surface of the implant is highly polished and contacts the other facet of the facet joint to provide movement at that facet joint. <FIG> represent one example of the implant comprising a curved or bent disc <NUM> with a roughened surface <NUM> on the greater face <NUM> of the disc and a highly polished surface <NUM> on the lesser face <NUM>. <FIG> depicts the implant of <FIG> positioned in a facet joint. The implant generally maintains a fixed position relative to the facet contacting the roughened surface while the movement of the facet joint is preserved between the other facet and the highly polished lesser face of the implant.

<FIG> show one example, where the implant <NUM> comprises two separate discs <NUM>, each disc comprising a first face <NUM> that articulates with the complementary first face <NUM> of the other disc, and a second face <NUM> adapted to secure the disc to the adjacent bone or cartilage of one facet of the facet joint <NUM>. In one example, the thickness of one disc will generally be about half of the anatomic spacing between two facets of the facet joint. In other examples, the implant comprises three or more discs. In one example the total thickness of all the discs is generally about <NUM>% to about <NUM>% of the anatomic spacing between the two facets. In another example, the total thickness of the discs is generally about <NUM>% to about <NUM>% of the anatomic spacing. In still another example, the total thickness of the discs is about <NUM>% to about <NUM>% of the anatomic spacing. Each disc of the two-part implant can otherwise also have features similar to those of a single-disc implant, including but not limited to curved or bent configurations, highly polished or roughened surfaces, and other feature mentioned below. The two discs need not have the same size, thickness, configuration or features. <FIG> depicts a two-part implant <NUM> positioned within a facet joint <NUM>.

The implant can be manufactured from any of a variety of materials known in the art, including but not limited to a polymer such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyethylene, fluoropolymer, hydrogel, or elastomer; a ceramic such as zirconia, alumina, or silicon nitride; a metal such as titanium, titanium alloy, cobalt chromium or stainless steel; or any combination of the above materials.

In one example, the implant is maintained between the two facets of the facet joint by taking advantage of the joint capsule and/or other body tissue surrounding the facet joint to limit the migration of the implant out of the facet joint. In some examples, the shape of the implant itself is capable of resisting displacement of the implant from its position generally between the facet joint surfaces. In one example, a concave or biconcave configuration resists displacement of the implant by providing an increased thickness at the periphery of the implant that requires a larger force and/or greater distraction of facet joint surfaces in order to cause displacement. In other examples, surface treatments or texturing are used to maintain the implant against a facet of the facet joint, as described previously. In some examples, a combination of disc configuration, surface texturing and existing body tissue or structures are used to maintain the position of the implant.

Bone growth facilitators, electrical current, or other known techniques may be used to accelerate osteoincorporation of textured or microporous anchoring surfaces.

The implant may be configured with a fastener interface to engage ("secure") a fastener member that facilitates retention of the implant within the joint capsule of the facet joint. Use of a fastener member may be advantageous for preventing migration of the implant over time use or with the extreme ranges of vertebral movement that may distract the articular surfaces sufficiently to allow the implant to slip out.

In <FIG>, the fastener member comprises a wire or cable <NUM> with a portion <NUM> that engages the implant <NUM> at a fastener interface <NUM>, and at least one other portion <NUM> that engages or anchors to the bone or soft tissue surrounding the facet joint. The wire or cable may be solid, braided or multi-filamented. The fastener member in this example will be described primarily as a cable or wire, but it is to be understood that any of a variety of elongate structures capable of extending through a central aperture will also work, including pins, screws, and single strand or multi strand polymeric strings or weaves, polymeric meshes and fabric and other structures that will be apparent to those of skill in the art in view of the disclosure herein.

The cross-sectional shape of the fastener member can be any of a variety of shapes, including but not limited to circles, ovals, squares, rectangles, other polygons or any other shape. The wire or cable generally has a diameter of about <NUM> to about <NUM> and a length of about <NUM> to about <NUM>. In other examples, wire or cable has a diameter of about <NUM> to about <NUM>, or about <NUM> to about <NUM>. The diameter of the wire or cable may vary along the length of the wire or cable. In one embodiment, the wire or cable has a length of about <NUM> to about <NUM>. In another example, the wire or cable has a length of about <NUM> to about <NUM>.

In <FIG>, the fastener interface <NUM> of the implant <NUM> is a conduit between the two faces <NUM>, <NUM> of the implant <NUM>, forming an aperture <NUM>. In one example, the aperture <NUM> has a diameter larger than the diameter of the wire or cable <NUM>, to provide the implant <NUM> with a range of motion as the facet joint moves. The aperture <NUM> inside diameter may be at least about <NUM>%, often at least about <NUM>% and in certain examples at least about <NUM>% or <NUM>% or greater of the outside diameter or corresponding dimension of the fastener member in the vicinity of the engagement portion <NUM>. The cross-sectional shape of the aperture <NUM> can match or not match the cross sectional shape of the wire or cable used.

In another example, the fastener interface <NUM> extends only partially through the implant <NUM>. The fastener interface <NUM> may be located generally in the center of the implant, or it may be located eccentrically, as depicted in <FIG>. In one example, shown in <FIG>, the fastener interface <NUM> is located at the edge <NUM> of the implant <NUM> such that the interior surface of the hole <NUM> is contiguous with the outer edge of the implant. This configuration of the fastener interface <NUM> does not require the cable <NUM> to be threaded through the fastener interface <NUM> and may facilitate engagement of the fastener member with the implant. <FIG> depict an example comprising a two-part implant <NUM>. Either a single cable or two separate cables may be used retain both discs within the facet joint. <FIG> depict another example comprising a curved implant <NUM> with a fastener interface <NUM> adapted to accept a cable.

In <FIG>, the wire or cable <NUM> is secured to the articular processes <NUM>, <NUM> by tying one or more knots <NUM> in the cable <NUM> that can resist pulling of the wire or cable through the articular process. In another embodiment, one or both ends of the wire or cable are provided with an anchor to resist migration of the implants. As shown in <FIG>, one or both ends of the wire or cable <NUM> may be threaded such that a nut <NUM> can be tightened on the wire or cable <NUM> to secure the wire or cable to the articular processes <NUM>, <NUM>. <FIG> depicts the attachment of a nut onto a threaded end of a cable. The threaded portion <NUM> of the wire or cable can be secured to the cable by pressing, crimping or twisting the threaded <NUM> portion onto the cable <NUM>. In one embodiment, the threaded portion <NUM> is made from titanium, titanium alloy, cobalt chromium, stainless steel, or any combination thereof.

In one example, the wire or cable has two threaded ends <NUM> for engaging the bony or cartilaginous tissue, one portion for each facet of the facet joint.

In <FIG>, the wire or cable is secured to the articular process with fastener rings <NUM>. As depicted in <FIG>, the fastener rings <NUM> comprise a ring <NUM> with a central lumen <NUM> and a locking element to facilitate locking the ring <NUM> to a fastener member. The central lumen <NUM> is adapted to accept insertion of a wire or cable through it. The illustrated locking element is in the form of a side lumen <NUM> which is threaded and configured to accept a rotatable screw <NUM> with a proximal end <NUM>, a threaded body <NUM> and a distal end <NUM>. The threaded body <NUM> is complementary to the threads of the side lumen <NUM> so that when the screw <NUM> is rotated at its distal end <NUM>, the proximal end <NUM> of the screw <NUM> moves further into the central lumen <NUM> and is capable of applying increasing force to a wire or cable inserted through the central lumen <NUM>. In one embodiment, the force on the wire or cable is capable of creating a friction fit or a mechanical interfit to resist movement between the wire or cable and the fastener ring <NUM>, thereby securing the wire or cable to the articular process <NUM> or <NUM>. As shown in <FIG>, the distal end <NUM> of the screw <NUM> can be configured to engage the wire or cable in any of a variety designs, including but no limited to a blunt tip <NUM>, curved tip <NUM> and piercing tip <NUM>.

In <FIG>, the wire or cable is securable to the articular process with a fastener ring <NUM> have radially inward biased projections <NUM> defining a central lumen <NUM>. The central lumen has a cross-sectional shape smaller than that of the wire or cable but is capable of enlargement when the inward projections <NUM> are bent away, as shown in <FIG>. The inward projections <NUM> apply increasing force to the wire or cable within the central lumen <NUM> as the projections <NUM> are bent, thereby creating a friction fit.

In one example, one end of the wire or cable fastener member is preformed with a retainer for engaging the articular process. The retainer may be a preformed ring, bulb, flared end, T-bar end, or any of a variety of shapes having a greater cross sectional area than the other portions of the wire or cable fastener member. This configuration of the wire or cable fastener member is adapted to engage an articular process by passing the free end of a wire or cable fastener member through an articular process such that the end with the preformed retainer can engage the articular process.

In one example, the wire or cable fastener member is secured to the articular processes with sufficient laxity or length between the secured ends or between the implant and one secured end so that the two articular processes are not fixed in position relative to each other and remain capable of performing movements such as flexion, extension, lateral flexion and/or rotation. In one example, the fastener member comprises a cable of braided polymer, including but not limited to a braided polymer such as PEEK or PEKK, or a braided metal, such as braided cobalt chromium or titanium. The cable can be selected with different degrees of flexibility to provide different degrees of movement at that facet joint. The cable has a first segment capable of engaging the implant at its fastener interface to limit the movement.

In <FIG>, the fastener member comprises a screw or bolt <NUM> with a proximal end <NUM>, body <NUM> and distal end <NUM>. The distal end <NUM> of the screw or bolt is capable of forming a mechanical interfit with a complementary fastener interface <NUM> on the implant or spacer <NUM>. The distal end <NUM> typically comprises threads, but other configurations may be used to form a mechanical interfit. The complementary fastener interface <NUM> on the implant <NUM> could be a threaded through hole or, a close-ended hole. The proximal end <NUM> of the screw or bolt <NUM> has a hex or other type of interface known in the art, capable of engaging a rotating tool to manipulate the screw or bolt <NUM>. The body of the screw or bolt <NUM> has a length sufficient to at least span the length of the hole or conduit created through the articular process for securing the implant. In <FIG>, the fastener member further comprises a pivotable washer <NUM> with a pivot surface <NUM> that articulates with the proximal end <NUM> of the screw <NUM>. In one example, the pivotable washer <NUM> is capable of a range of positions relative to the screw <NUM> and provides the screw <NUM> with a better surface area contact with the bone.

<FIG> is a cross-sectional view of a facet joint <NUM> with a spacer <NUM> bolted to one articular process <NUM> of a facet joint <NUM>. The spacer <NUM> position is fixed relative to one facet <NUM> of the joint <NUM>, but provides for spacing and movement of the other facet <NUM> with respect to the spacer <NUM>. In examples comprising a two-part implant, shown in <FIG>, each disc may have its own screw or bolt fastener member. <FIG> depicts a flat two-part implant <NUM> and <FIG> depicts a curved two-part implant <NUM>.

In <FIG>, the fastener member is integral with or attached to the implant and comprises a projection <NUM> from the implant <NUM> that is adapted to engage the adjacent articular process or surrounding tissue. In one example, the projection comprises at least one spike <NUM> or hook projecting from one face of the implant <NUM>. In one example, the spike <NUM> or hook can be ribbed, barbed or threaded to resist separation after insertion into bone or tissue. <FIG> depicts the implant <NUM> of <FIG> engaged to a facet <NUM> of the facet joint <NUM>. In one example comprising a two-part implant <NUM>, shown in <FIG>, each disc <NUM> may have its own projection-fastener member <NUM>. In <FIG>, more than one projection <NUM> is provided on the implant <NUM>. <FIG> illustrates the implant of <FIG> placed in a facet joint <NUM>. The projections <NUM> may be angled with respect to the implant <NUM> to resist dislodgement by the movement at the joint.

<FIG> illustrate examples where the fastener member comprises a projection <NUM> extending laterally such as from the side of the implant <NUM>, and adapted to engage the soft tissue surrounding the facet joint, rather than a bony or cartilaginous articular process. In one example, the implant of <FIG> could be inserted into a facet joint through an incision made in the joint capsule, but the integrity of the joint capsule opposite the incision site is maintained and used as an anchoring site for the implant. The orientation of the projection can be fixed as in <FIG>, or flexible. <FIG> depicts a flexible tether such as a wire <NUM> with its proximal end <NUM> embedded in or otherwise attached to the implant and one or more barbs which may be attached to its distal end <NUM>. A flexible projection may provide greater selection of soft tissue anchoring sites for the implant.

In one example, the joint capsule is closed after placement of the implant. Closure may be performed using adhesives, suturing, stapling or any of a variety of closure mechanisms known in the art.

<FIG> depict an implant <NUM> according to an embodiment. Specifically, <FIG> is a front perspective view of implant <NUM>, <FIG> is a side view of implant <NUM>, and <FIG> is a cross-sectional side view of implant <NUM>. Implant <NUM> can be similar to, and have similar elements and uses as implant <NUM> described above. By way of example, a fastener interface <NUM> of implant <NUM> can be similar to fastener interface <NUM> of implant <NUM>. Implant <NUM> includes a concave first face <NUM>, a convex second face <NUM>, a centrally disposed circular fastener interface <NUM>, and four irregular shaped substance interfaces <NUM>.

<FIG> show posterior perspective views of a portion of the vertebral column during a method for fusing adjacent vertebrae using an implant <NUM> according to an embodiment. As shown in <FIG>, implant <NUM> and a fastener member <NUM> can be used to fuse a vertebra V1 and vertebra V2 via the inferior articular process IAP1A of vertebra V1 and the superior articular process SAP2A of vertebra V2. Any fastener member can include any biocompatible material, e.g., stainless steel, titanium, PEEK, nylon, etc. Also as shown in <FIG>, an implant <NUM> and a fastener member <NUM> are used to fuse a vertebra V1 and vertebra V2 via the inferior articular process IAP1B of vertebra V1 and the superior articular process SAP2B of vertebra V2. In some embodiments, vertebra V1 and/or vertebra V2 are fused using only one of implant <NUM> or implant <NUM>. In some such embodiments, one of implant <NUM> and fastener member <NUM> or implant <NUM> and fastener member <NUM> can be used to stabilize vertebra V1 and/or vertebra V2 via one of via the inferior articular process IAP1A of vertebra V1 and the superior articular process SAP2A of vertebra V2, or, via the inferior articular process IAP1B of vertebra V1 and the superior articular process SAP2B of vertebra V2. In other such embodiments, one of fastener member <NUM> or fastener member <NUM> can be used to stabilize vertebra V1 and/or vertebra V2 via both of the inferior articular process IAP1A of vertebra V1 and the superior articular process SAP2A of vertebra V2 (for example, in combination with implant <NUM>), and, the inferior articular process IAP1B of vertebra V1 and the superior articular process SAP2B of vertebra V2 (for example, in combination with implant <NUM>).

<FIG> depicts a flow chart illustrating a method <NUM> of using implant <NUM> with fastener member <NUM> and/or implant <NUM> with fastener member <NUM>. Prior to use of implant <NUM> and/or implant <NUM>, a patient can be prepared for surgery, at <NUM>. Some examples of preparations for surgery are described in <CIT>, and titled "Vertebral Facet Joint Drill and Method of Use" (referred to as "the '<NUM> application). In addition to those procedures described in the '<NUM> application, the surgical procedure can include direct visualization of the vertebra(e) to be stabilized. Said another way, the medical practitioner can perform the operation without the use of fluoroscopy. This direct visualization can be possible due to the small incision necessary for implantation of the implant, for example, less than about <NUM>, and due to the ease of implanting and deploying the implant. The surgical procedure used can include forming an opening in body tissue substantially equidistant between a first articular process of the first vertebra and a second articular process of the first vertebra. A cannula (not shown) can be inserted through the opening and a proximal end of the cannula can be positioned near the superior articular process SAP2A of vertebra V2. The surgical procedure can include preparing the area near and/or around the vertebra V2 by, for example, removing all or a portion of ligaments, cartilage, and/or other tissue. For example, the area near and/or around a facet joint can be prepared by removing all or a portion of the facet joint capsule.

A drill or other device can be used to form a lumen in superior articular process SAP2A of vertebra V2 and inferior articular process IAP1A of vertebra V1, at <NUM>. Specifically, the drill can be used to form the lumen in a facet of superior articular process SAP2A of vertebra V2 and to form the lumen in a facet of inferior articular process IAP1A of vertebra V1. Methods and devices for forming lumens in vertebra are described in the '<NUM> application. A portion of the surface of the facet of SAP2A and IAP1A can be prepared for fusion, at <NUM>. Specifically, a portion of the surface of the facet can be ground, scored, roughened, sanded, etc, such that the surface of the facet can better adhere to any substances to aid in fusion and/or otherwise fuse more readily to the implant. The fastener member <NUM> can be positioned within the cannula and can be advanced through the cannula until a proximal end portion <NUM> of fastener member <NUM> is positioned near the lumen of superior articular process SAP2A of vertebra V2. The proximal end of the cannula can have a bend to direct the proximal end portion <NUM> of fastener member <NUM> into the lumen of superior articular process SAP2A of vertebra V2. The proximal end portion <NUM> of fastener member <NUM> is inserted into the lumen of superior articular process SAP2A of vertebra V2, at <NUM>. A substance can be disposed in a substance interface <NUM> of implant <NUM>, at <NUM>. Implant <NUM> can have a substance disposed in substance interface <NUM> prior to a surgical procedure, for example, during manufacturing of implant <NUM>, post-manufacturing, and/or as part of a kit. Implant <NUM> is inserted between the superior articular process SAP2A of vertebra V2 and inferior articular process IAP1A of vertebra V1, at <NUM>.

The proximal end portion <NUM> of fastener member <NUM> is inserted into the lumen of inferior articular process IAP1A of vertebra V1, at <NUM>. The fastener member can be secured, at <NUM>. Securing the fastener member <NUM> can be based on the type of fastener member used. By way of example, securing a fastener member similar to a flexible fastener band as depicted in <FIG>, can include inserting the proximal end portion <NUM> into a fastening mechanism of a distal end portion <NUM> of the fastener member <NUM>, and advancing the proximal end portion <NUM> through the fastening mechanism to secure the fastening mechanism. Fastener member can be secured by tying a first portion the fastener member to a second portion of the fastener member, by screwing the fastener member into a threaded fastener interface, threading a fastener onto a threaded end of a fastener member disposed through a fastener interface, combinations of above, etc. Implant <NUM> can be disposed prior to inserting the proximal end portion of the fastener member <NUM> into the lumen of superior articular process SAP2A of vertebra V2. The cannula can be removed and/or reinserted at various points during the method <NUM>, including, for example, after the proximal end portion <NUM> of fastener member <NUM> is inserted into the lumen formed within the superior articular process SAP2A of vertebra V2, after vertebra V1 and/or Vertebra V2 has been stabilized, or at other points during method <NUM>.

After the fastener member is secured, superior articular process SAP2A of vertebra V2 can fuse to inferior articular process IAP1A of vertebra V1. Fusing can include one or more of bone material from superior articular process SAP2A of vertebra V2, bone material from inferior articular process IAP1A of vertebra V1, and the substance that fuses articular process SAP2A of vertebra V2 to inferior articular process IAP1A of vertebra V1 through substance interface <NUM>. In some examples, after superior articular process SAP2A of vertebra V2 is fused to inferior articular process IAP1A of vertebra V1, the fastener member <NUM> is not removed. In some other examples, after superior articular process SAP2A of vertebra V2 is fused to inferior articular process IAP1A of vertebra V1, all or a portion of the fastener member <NUM> can be removed. In other examples, fastener member <NUM> can be removed after fusion of superior articular process SAP2A of vertebra V2 to inferior articular process IAP1A of vertebra V1 has started, but has not finished.

In addition to the fastener members shown above, such as, for example, fastener member <NUM>, <FIG> show fastener members according to other embodiments.

<FIG> depicts views of a fastener member <NUM>. Fastener member <NUM> can be a flexible fastening band ("band") <NUM>, <FIG> depicts a view of a portion of band <NUM> can be similar to band <NUM> described above and can include similar components. By way of example, band <NUM> includes a proximal end portion <NUM>, a first portion <NUM>, a second portion <NUM>, and a distal end portion <NUM> including a fastening mechanism <NUM>. In contrast to band <NUM>, band <NUM> includes a cylindrical second portion <NUM> and each includes a third portion <NUM>. As depicted in <FIG>, third portion <NUM> is substantially the same shape as first portion <NUM>. As shown in <FIG> and <FIG>, band <NUM> includes a gear rack <NUM> and gears <NUM>. Each of gears <NUM> can be wedge shaped to allow each of gears <NUM> to displace the ratchet of fastening mechanism <NUM> in only one direction. In some embodiments, gears <NUM> can be other shapes, such as blocks, etc..

<FIG> is a side view and <FIG> is a top view of a fastener member <NUM>. Fastener member <NUM> can be a flexible fastening band ("band") <NUM> according to another embodiment. Band <NUM> can be similar to band <NUM> and band <NUM> described above and can include similar components. By way of example, band <NUM> includes a proximal end portion <NUM>, a first portion <NUM> including a gear rack <NUM>, a second portion <NUM>, and a distal end portion <NUM> including a fastening mechanism <NUM> and a ratchet <NUM>. In contrast to gear rack <NUM>, a cross sectional area of each gear <NUM> of gear rack <NUM> is rectangular in shape instead of wedge shaped. Furthermore, in contrast to first portion <NUM>, first portion <NUM> is cylindrical in shape instead of cuboidal in shape. In this manner, the lumen <NUM> of the fastening mechanism <NUM> is cylindrical in shape. A band according to this embodiment may be particularly useful in deployments where a single band in used to stabilize adjacent vertebrae. In this manner, the second portion can be disposed within the lumen of the first articular process of the first vertebra and a portion of the first portion can be disposed within the lumen of the second articular process of the first vertebra. In these embodiments the portion of the band within the first articular process of the first vertebra and the portion of the band within in the second articular process of the first vertebra can both have substantially the same shape as the lumen in the first articular process of the first vertebra and the lumen in the second articular process of the first vertebra. In this manner, and as described above regarding band <NUM>, the amount of open space within the lumens can be minimized, the amount of surface area of the first portion and/or second portion of the band in contact with the lumens can increase, and subsequently the movement of the first vertebra and/or the second vertebra can be reduced or minimized. Furthermore, when movement of the first vertebra and/or the second vertebra does occur, forces acting against the band can be more equally distributed throughout the first portion and/or the second portion, due at least to the increased surface area of the band in contact with the lumens.

<FIG> is a side view a fastener member <NUM>. Fastener member <NUM> can be a flexible fastening band ("band") <NUM> according to an embodiment. Band <NUM> can be similar to band <NUM>, band <NUM>, and band <NUM> described above and can include similar components. By way of example, band <NUM> includes a proximal end portion <NUM>, a first portion <NUM> including a gear rack <NUM>, a second portion <NUM>, and a distal end portion <NUM> including a fastening mechanism <NUM>. Similar to gear rack <NUM>, a cross sectional area of each gear <NUM> of gear rack <NUM> is rectangular in shape. In contrast to gear rack <NUM>, each of gears <NUM> extend the entire circumference of first portion <NUM> instead of only a portion of the circumference of first portion <NUM>. Furthermore, in contrast to first portion <NUM>, but similar to first portion <NUM>, first portion <NUM> is cylindrical in shape instead of cuboidal in shape. In this manner, the lumen <NUM> of the fastening mechanism <NUM> is cylindrical in shape. A band according to this embodiment may be particularly useful in deployments where the movement and repositioning of the band after implantation may be difficult. In this manner, because each of the gears can be the entire circumference of the first portion and/or the second portion, the first portion and/or the second portion can enter the fastening mechanism in any radial orientation and still engage the ratchet.

<FIG> are views of a fastener member <NUM>. Fastener member <NUM> can be a flexible fastening band ("band") <NUM> according to another embodiment. <FIG> is a perspective view and <FIG> is a cross-sectional side view of band <NUM>. <FIG> is a cross-sectional view of band <NUM> taken along line XXIII. <FIG> is a cross-sectional top view of band <NUM> in a first configuration and <FIG> is a cross-sectional top view of band <NUM> in a second configuration. Band <NUM> can be similar to band <NUM> and band <NUM> described above and can include similar components. By way of example, band <NUM> includes a proximal end portion (not shown), a first portion <NUM> including a gear rack <NUM> (see <FIG>), a second portion <NUM>, and a distal end portion <NUM> including a fastening mechanism <NUM> and a ratchet <NUM>. In contrast to band <NUM> and band <NUM>, band <NUM> includes a reinforcement piece <NUM>.

Reinforcement piece <NUM> can include any of the materials described above for a fastener member. In some embodiments, reinforcement piece <NUM> can include a material stronger than second portion <NUM> and/or first portion <NUM>, for example, first portion <NUM> and second portion <NUM> can include PEEK and reinforcement piece <NUM> can include titanium. As shown in <FIG>, reinforcement piece <NUM> can be disposed within band <NUM> approximately along the entire length of second portion <NUM>, and a portion of reinforcement piece <NUM> can be disposed within the distal end portion <NUM>. In some embodiments, reinforcement piece can include a length along at least a portion of the length of second portion <NUM> and/or first portion <NUM> but not the distal end portion. In some embodiments, reinforcement piece <NUM> can be disposed only within second portion <NUM>. Reinforcement piece <NUM> can have a length in first dimension (length), a length in a second dimension (width), and a length in a third dimension (height). As described herein, a reinforcement piece be different shapes that can include more or fewer dimensions.

The reinforcement piece can be molded within the band. Said another way, in embodiments where the first portion, the second portion, and or the distal end portion are moldable materials, the reinforcement piece can be placed in the mold and the moldable materials can be injected or otherwise put in the mold around the reinforcement piece. In other embodiments, each portion of the band (for example, the proximal end portion, the first portion, the second portion, the third portion, and/or the distal end portion) around the reinforcement piece can have a top half and a bottom half, and each of the top half and the bottom half can be placed around the reinforcement piece, and sealed. As shown in <FIG>, reinforcement piece <NUM> includes support members <NUM>. While <FIG> shows reinforcement piece <NUM> including four support members <NUM>, in some embodiments, more or fewer support members <NUM> can be used. Support members <NUM> can maintain the position of reinforcement piece <NUM> during the molding and/or assembly process of band <NUM>. As shown in <FIG>, support members <NUM> are removed before band <NUM> is used.

As shown in <FIG>, reinforcement piece <NUM> can has a substantially uniform cuboidal shape. In other embodiments, reinforcement piece <NUM> can have other shapes. The shape of the reinforcement piece can be selected depending on the desired bending and/or torsion characteristics of the material chosen. By way of example, a substantially planar cuboidal shape can provide a greater increase in bending strength while providing a lesser increase in torsion strength, a cylindrical shape can provide an increase in bending strength while providing very little increase in torsion strength, a substantially square and/or tubular cuboidal shape can provide similar bending and torsion increases. Any shape can be selected to achieve the desired bending and torsion strength. Combinations of materials and shapes can also be considered. For example, a material having higher torsion strength may be combined with a shape having a lower torsion strength to combine for the desired torsion strength. As shown in <FIG> and <FIG>, reinforcement piece <NUM> includes holes <NUM> distributed along the length of the first dimension. While <FIG> and <FIG> shows band <NUM> including many holes <NUM>, in some embodiments, more or fewer holes <NUM> can be used. <FIG> and <FIG> depict holes <NUM> distributed substantially equally along the length of the first dimension, in some embodiments, the holes can be distributed differently or along different dimensions depending on the shape and/or material chosen, and/or whether the reinforcement piece is solid or hollow. Holes <NUM> can be configured to reduce the weight of reinforcement piece <NUM> while still provided band <NUM> additional strength. Holes <NUM> can be round, oval, square, or any other shape.

<FIG> is an exploded view, <FIG> is a perspective view, and <FIG> is a cross-sectional view of a fastener member <NUM>. Fastener member <NUM> can be a flexible fastening band ("band") <NUM> according to another embodiment. Band <NUM> can be similar to band <NUM> and band <NUM> described above and can include similar components. By way of example, band <NUM> includes a proximal end portion <NUM>, a first portion <NUM>, a second portion <NUM> including a gear rack <NUM>, a distal end portion <NUM>, a fastening mechanism <NUM> and a ratchet <NUM>. In contrast to band <NUM> and band <NUM>, the fastening mechanism <NUM> of band <NUM> is separately formed from distal portion <NUM> of band <NUM>. While second portion <NUM> of band <NUM> is shown in <FIG> as having a substantially cuboidal shape, in some embodiments, second portion <NUM> can be substantially cylindrical in shape or any other appropriate shape discussed herein. As shown in <FIG> and <FIG>, band <NUM> includes a gear rack <NUM> and gears <NUM>. Each of gears <NUM> can be wedge shaped to allow each of gears <NUM> to displace a ratchet <NUM> of fastening mechanism <NUM> in only one direction. In some embodiments, gears <NUM> can be other shapes, such as blocks, or any other appropriate shape discussed herein. As shown in <FIG>, distal end portion <NUM> can be substantially circular in shape and can have a diameter greater than a width of second portion <NUM>. In other embodiments, distal portion <NUM> can have other shapes, for example, oval, rectangular, square, etc..

In addition to the implants shown above, such as, for example, implant <NUM>, <FIG> show implants according to other embodiments.

<FIG> depict an implant <NUM> according to an embodiment. Specifically, <FIG> is a front perspective view of implant <NUM>, <FIG> is a rear perspective view of implant <NUM>, <FIG> is a side view of implant <NUM>, and <FIG> is a cross-sectional side view of implant <NUM>. Implant <NUM> can be similar to, and have similar elements and uses as implant <NUM> and implant <NUM> described above. By way of example, a fastener interface <NUM> of implant <NUM> can be similar to fastener interface <NUM> of implant <NUM>, and similar to fastener interface <NUM> of implant <NUM>. Implant <NUM> includes a concave first face <NUM>, a convex second face <NUM>, a centrally-disposed substantially-circular fastener interface <NUM>, and six substantially-circular shaped substance interfaces <NUM>.

<FIG> depict an implant <NUM> according to an embodiment. Specifically, <FIG> is a front perspective view of implant <NUM>, <FIG> is a rear perspective view of implant <NUM>, <FIG> is a side view of implant <NUM>, and <FIG> is a cross-sectional side view of implant <NUM>. Implant <NUM> can be similar to, and have similar elements and uses as implant <NUM> and implant <NUM> described above. By way of example, a fastener interface <NUM> of implant <NUM> can be similar to fastener interface <NUM> of implant <NUM>, and similar to fastener interface <NUM> of implant <NUM>. Implant <NUM> includes a concave first face <NUM>, a convex second face <NUM>, a centrally-disposed substantially-circular fastener interface <NUM>, and five rounded rectangular shaped substance interfaces <NUM>.

<FIG> depict an implant <NUM> according to an embodiment. Specifically, <FIG> is a front perspective view of implant <NUM>, <FIG> is a rear perspective view of implant <NUM>, <FIG> is a side view of implant <NUM>, and <FIG> is a cross-sectional side view of implant <NUM>. Implant <NUM> can be similar to, and have similar elements and uses as implant <NUM> and implant <NUM> described above. By way of example, a fastener interface <NUM> of implant <NUM> can be similar to fastener interface <NUM> of implant <NUM>, and similar to fastener interface <NUM> of implant <NUM>. Implant <NUM> includes a concave first face <NUM>, a convex second face <NUM>, a centrally-disposed substantially-circular fastener interface <NUM>, and several substantially-circular shaped and variably-sized substance interfaces <NUM>.

<FIG> depict an implant <NUM> according to an embodiment. Specifically, <FIG> is a front perspective view of implant <NUM>, <FIG> is a rear perspective view of implant <NUM>, <FIG> is a side view of implant <NUM>, and <FIG> is a cross-sectional side view of implant <NUM>. Implant <NUM> can be similar to, and have similar elements and uses as implant <NUM> and implant <NUM> described above. By way of example, a fastener interface <NUM> of implant <NUM> can be similar to fastener interface <NUM> of implant <NUM>, and similar to fastener interface <NUM> of implant <NUM>. Implant <NUM> includes a concave first face <NUM>, a convex second face <NUM>, a centrally-disposed substantially-circular fastener interface <NUM>, four irregular shaped substance interfaces <NUM>, and four projections <NUM>. Each of the four projections <NUM> can engage, or other wise dig, latch, lock, or hook into or onto, a bone portion to prevent or reduce movement of the implant <NUM>, such as, for example, rotation of implant <NUM>, longitudinal movement of implant <NUM>, and/or lateral movement of implant <NUM>. In this manner, the projections <NUM> can secure implant <NUM> to a bone portion during a fusion procedure. In some embodiments, projections <NUM> can substantially maintain a position of implant <NUM> after a fastener member is removed.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, not limitation, and various changes in form and details may be made.

Claim 1:
A vertebral facet joint fusion implant (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), comprising:
an implant disc shaped having a face (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), a second face (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), an interface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), and a second interface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>),
the face shaped to compliment a shape of a first bone portion, the interface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) configured to receive a fastener member, wherein the interface defines a first aperture,
wherein the second interface (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) defines a second aperture extending from the first face to the second face, the second aperture having a different shape or size than the first aperture,
the implant configured to be secured with the fastener member such that the first bone portion and a second bone portion are fused to each other after the implant is secured by the fastener member.