Abstract:
Implants and methods aimed at safely repairing and/or reconstructing the facet joint so as to provide the required flexibility and elasticity to support continued motion after the implant has been implanted in a facet joint.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application is an international patent application claiming the benefit of priority from U.S. Provisional Application Ser. No. 60/937,872, filed on Jun. 29, 2007, U.S. Provisional Application Ser. No. 60/964,627, filed on Aug. 13, 2007, and U.S. Provisional Application Ser. No. 60/967,487, filed on Sep. 4, 2007, the entire contents of which are hereby expressly incorporated by reference into this disclosure as if set forth fully herein. The present application also incorporates by reference the following commonly owned publications in their entireties: PCT Application Serial No. PCT/US2006/021814, entitled “Improvements Relating In and To Surgical Implants,” filed on Jun. 5, 2006; PCT Application Serial No. PCT/US2008/060944, entitled “Textile-Based Surgical Implant and Related Methods, filed Apr. 18, 2008; and U.S. Pat. No. 6,093,205, entitled “Surgical Implant,” issued Jul. 25, 2000. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    I. Field of the Invention 
         [0003]    The present invention relates to implants and methods generally aimed at surgery and, more particularly, to implants and methods aimed at safely repairing and/or reconstructing the facet joint. 
         [0004]    II. Discussion of the Prior Art 
         [0005]    Zygapophyseal joints (referred to hereafter as “facet joints”) are located between facets of the interior and superior articular processes of adjacent vertebra. Facet joints provide stability in the spine and prevent excessive torsion, while permitting a small amount of flexion, extension and lateral bending. Since facet joints are in almost constant motion with the spine, erosion of the articular processes can occur, causing spinal disorders such as degenerative spondylolisthesis or spinal stenosis. 
         [0006]    In order to decrease the mechanical stress on the intervertebral disc due to the degenerative facet joints and stop the narrowing of the foraminal space and compressing of the spinal cord and nerves, surgeons can perform decompression and fusion. However, patients treated with decompression alone may have a risk of progressive degenerative process which can lead to further vertebral slip and/or eventual mechanical lower back pain. Although spinal fusion may reestablish stability after decompression, fusion eliminates motion altogether. 
         [0007]    The present invention is directed at overcoming, or at least improving upon, the disadvantages of the prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention accomplishes this goal by providing a motion preserving implant that, in some instances, allows for tissue and/or bony ingrowth. An implant according to the present invention is suitable for use in a variety of surgical applications, including but not limited to spine surgery. When applied to spinal surgery and implanted into a facet joint, the implant repairs/reconstructs the degenerative joint and restores the foraminal space, while advantageously preserving the natural motion of the spine. The compliant nature of the implant provides the required flexibility and elasticity to support the full range of physiological movements, as opposed to fusion surgery. In addition, the porosity and biocompatibility of the implant may facilitate tissue and/or bony ingrowth throughout part or all of the implant (if desired), which helps to secure and encapsulate the implant in the facet joint. 
         [0009]    The implant of the present invention may be constructed in any number of suitable fashions without departing from the scope of the present invention. The implant may include a spacer and a mechanism or method for attaching the spacer within the facet joint. According to a first embodiment of the present invention, the implant includes a spacer disposed within an encapsulating jacket having a plurality of attachment flanges. To repair/reconstruct the facet joint, the spacer is positioned between a superior articular facet of an inferior vertebra and an inferior articular facet of a superior vertebra to prevent bone-on-bone contact. 
         [0010]    A variety of materials can be used to form the spacer and/or encapsulating jacket of the implant. The spacer is preferably formed of biocompatible material. In one preferred embodiment, the spacer is formed of a textile/fabric material throughout. The spacer may be constructed from any of a variety of fibrous materials, for example including but not limited to polyester fiber, polypropylene, polyethylene, ultra high molecular weight polyethylene (UHMWPe), poly-ether-ether-ketone (PEEK), carbon fiber, glass, glass fiber, polyaramide, metal, copolymers, polyglycolic acid, polylactic acid, biodegradable fibers, silk, cellulosic and polycaprolactone fibers. The spacer may be manufactured via any number of textile processing techniques (e.g. embroidery, weaving, three-dimensional weaving, knitting, three-dimensional knitting, injection molding, compression molding, cutting woven or knitted fabrics, etc.). In another preferred embodiment, the spacer is comprised of an elastomeric component (e.g. silicon) encapsulated in fabric. In all cases, it will be understood that the spacer reduces the risk of progressive slip and the onset of lower back pain by alleviating the mechanical stress on the facet joint. Furthermore, the spacer may be provided in any number of suitable dimensions depending upon the surgical application and patient pathology. 
         [0011]    The jacket may be constructed from any of a variety of fibrous materials, for example including but not limited to polyester fiber, polypropylene, polyethylene, ultra high molecular weight polyethylene (UHMWPe), poly-ether-ether-ketone (PEEK), carbon fiber, glass, glass fiber, polyaramide, metal, copolymers, polyglycolic acid, polylactic acid, biodegradable fibers, silk, cellulosic and polycaprolactone fibers. The jacket may be manufactured via any number of textile processing techniques (e.g. embroidery, weaving, three-dimensional weaving, knitting, three-dimensional knitting, injection molding, compression molding, cutting woven or knitted fabrics, etc.). The jacket may encapsulate the spacer fully (i.e. disposed about all surfaces of the spacer) or partially (i.e. with one or more apertures formed in the jacket allowing direct access to the spacer). The various layers and/or components of the spacer may be attached or unattached to the encapsulating jacket. The jacket may optionally include one or more fixation elements for retaining the jacket in position after implantation, including but to limited to one or more flanges extending from or otherwise coupled to the jacket and screws or other affixation elements (e.g. nails, staples sutures, tacks, adhesives, etc.) to secure the flange to an adjacent anatomical structure (e.g. vertebral body). This may be facilitated by providing one or more apertures within the flange dimensioned to receive the screws or other fixation elements. 
         [0012]    The materials selected to form the spacer and/or jacket may be specifically selected depending upon the target location/use within the body (e.g. spinal, general orthopedic, and/or general surgical). For example in many instances it may be preferable to select UHMWPe fibers in order to generate a specific tissue response, such as limited tissue and/or bony ingrowth. In some instances it may be desirable to modify the specific fibers used, such as providing a surface modification to change or enhance a desired tissue response. 
         [0013]    Once the spacer is implanted between the articular facets of the facet joint, attachment flanges secure the implant in situ. The attachment flanges wrap around the adjacent vertebrae and affixation elements (e.g. screws, nails, staples, sutures, buttons, bone anchors, etc.) fasten the attachment flanges to the adjacent vertebrae. The attachment flanges may be attached to any suitable portion of the vertebrae, including but not limited to the vertebral body, spinous process, pedicle, lamina, superior and/or inferior articular facet, articular process, and/or any combination thereof. It will be appreciated that any number of attachment flanges and affixation elements may be used to secure the implant in situ without departing from the scope of the present invention. In all instances, the attachment flanges (or flange) result in the implant being secured into place within the facet joint. 
         [0014]    Although described above as having an encapsulating jacket, the implant may be presented without an encapsulating jacket. According to a second embodiment, the implant comprises a spacer with attachment flanges that are directly connected to the spacer (instead of being connected to an encapsulating jacket). In this embodiment, the spacer may also have a centrally located attachment flange. A bore is drilled completely through the superior articular process of the inferior vertebra. The centrally located attachment flange on the spacer passes through the bore in the superior articular process of the inferior vertebra and is then secured into position on the outer surface of the articular process by a fixation element(s). The attachment flanges may then be fastened to the adjacent vertebrae by affixation elements. The attachment flanges and centrally located attachment flange may be attached to any suitable portion of the vertebrae, including but not limited to the vertebral body, spinous process, pedicle, lamina, superior and/or inferior articular facet, articular process, and/or any combination thereof. 
         [0015]    Although described herein largely in terms of attaching the spacer to the superior articular process of the inferior vertebra, it will be understood that the spacer may be attached to the inferior articular process of the superior vertebra. In all instances, the implant is situated in the facet joint and will result in the repair/reconstruction of the degenerative joint. 
         [0016]    Any number of attachment flanges, centrally located attachment flanges or affixation elements may be used to affix the implant in situ. According to a variation of the second embodiment of the present invention, the implant may be comprised solely of the centrally located attachment flange connected to the spacer. In another variation of the second embodiment, the implant may be comprised solely of attachment flanges connected to the spacer without a centrally located attachment flange. In all instances, the implant is secured into place within the facet joint. 
         [0017]    According to a variation of the second embodiment of the present invention, a clamping mechanism may be used to affix the spacer to the superior articular facet of the inferior vertebra. After the centrally located attachment flange of the spacer is passed through the bore in the superior articular process of the inferior vertebra, the centrally located attachment flange is passed through a hole in the middle of the clamping mechanism. The clamping mechanism slides up the centrally located attachment flange until it is pressed firmly against the outer surface of the articular process. The bolt in the clamping mechanism is then tightened to securely hold the centrally located attachment flange into place. This, in turn, anchors the implant within the facet joint. Additionally, the attachment flanges may then be fastened to the adjacent vertebrae by affixation elements. 
         [0018]    As previously mentioned, the number of attachment flanges may be increased or decreased without departing from the scope of the present invention. Furthermore, it will be appreciated that the clamping mechanism is not limited to the second embodiment of the present invention and may be used with any embodiment of the implant described herein without departing from the scope of the present invention. 
         [0019]    According to a third embodiment of the present invention, the implant comprises a spacer with directly attached tie cords. A bore (or bores) is drilled completely through the superior articular process of the inferior vertebra. The spacer is inserted in the facet joint while the tie cords pass through the bore in the superior articular process and are secured on the outer surface of the articular process. The tie cords may be secured through various methods, such as by way of example only, tied through a button, sutured, anchored, screwed, crimped, or any other affixation element. 
         [0020]    Various features may be incorporated into the spacer to support the full range of physiological movements and/or limit or prevent tissue and/or bony ingrowth, for example including but not limited to an internal metal plate, a low adhesion layer (e.g. polyethylene suture thread), and/or a densely-packed substrate layer (e.g. tightly-woven nonsoluble microfibre polyester or dense embroidery). The internal metal plate of the spacer may serve to stiffen the spacer and may also serve as a radio-opaque marker, which is advantageous when tracking the implant post-surgery. In addition, the metal plate may be placed on the joint bearing surface of the spacer to help preserve motion within the facet joint by inhibiting tissue and/or bony ingrowth (as desired) due to the metallic properties. The effect of inhibiting tissue and/or bony ingrowth on the joint bearing surface is desirable and advantageous because it facilitates the free range of motion within the facet joint between the spacer and the articular facet opposite fixation. More specifically, the spacer is not attached to both articular facets thereby leaving space between the implant and one articular facet for free movement within the facet joint. 
         [0021]    A low adhesion layer of polyethylene suture thread (or any other type of low adhesion material) may also be added to the joint bearing surface of the spacer opposite fixation. Another feature may consist of adding a non-soluble substrate layer of microfibre woven polyester (or any other non-soluble substrate material) to the joint bearing surface of the spacer opposite fixation. All of these features, whether used alone or in combination, inhibit tissue and/or bony ingrowth on the joint bearing surface due to the low adhesion and/or non-soluble aspects of the material. This effect of inhibiting tissue and/or bony ingrowth on the joint bearing surface is desirable and advantageous because it facilitates the free range of motion within the facet joint between the spacer and the articular facet opposite fixation. More specifically, the spacer is not attached to both articular facets thereby leaving space between the implant and one articular facet for free movement within the facet joint. 
         [0022]    In addition to having tie cords, other features may be added to the spacer to help secure the implant in situ. For example, an adhesive or fusion-promoting layer (e.g. calcium hydroxyapatite, bone morphogenic protein, demineralized bone matrix, Formagraft®, stem cell material, etc.) may be added to the spacer on the surface of fixation. This adhesive layer of calcium hydroxyapatite (or any other type of adhesive material) bonds the spacer to the articular facet of fixation by facilitating tissue and/or bony ingrowth through the surface of fixation on the spacer. This effect of tissue and/or bony ingrowth on the surface of fixation is desirable and advantageous because it secures and encapsulates the implant to the inside of the facet joint. 
         [0023]    It will be appreciated that the spacer may incorporate one or more or all of the features described above and any combination thereof without departing from the scope of the invention. It will also be appreciated that the features described above can be applied to any of the embodiments disclosed herein. 
         [0024]    According to a fourth embodiment of the present invention, the implant may include a spacer with a guide funnel that facilitates a toggle element with tie cords. A bore (or bores) is drilled completely through the superior articular process of the inferior vertebra. The spacer is inserted in the facet joint with the guide funnel of the spacer lining up with the bore in the superior articular process. A pusher wire then pushes the toggle element through the bore in the superior articular process and next through the guide funnel of the spacer via a guide tube. 
         [0025]    Once passed through the bore and guide funnel, the pusher wire deploys the toggle element from the guide tube to lock the spacer into position within the facet joint. The tie cords, which are attached to the toggle element, are tensioned and secured externally on the outer surface of the superior articular process of the inferior vertebra. This may be achieved by various methods, such as by way of example only, tied through a button, sutured, anchored, screwed, crimped, or any other affixation element. As a result, the toggle element and tie cords (affixed to the outer surface of the articular facet) hold the spacer securely into place within the facet joint. 
         [0026]    According to a fifth embodiment of the present invention, the implant may include a push-on locking cap and spacer with a serrated stem (or stems). By way of example only, the stem may be made of metal or a polymer. Both the stem and push-on locking cap have serrations to facilitate secure attachment of the implant to the facet joint. Next, a bore (or bores) is drilled completely through the superior articular process of the inferior vertebra. The stem is passed through the bore in the superior articular process of the inferior vertebra, and the connected spacer is inserted between the articular facets of the facet joint. 
         [0027]    Once the spacer and stem are placed within the facet joint, the push-on locking cap engages the stem. Due to the serrations on the inside of the push-on locking cap and the serrations on the outside of the stem, the cap can be pushed onto the stem and locked into place on the outer surface of the superior articular process of the inferior vertebra. The manner of locking the push-on cap onto the serrated stem is similar to that used in a cable tie. This may be done with a tool, such as a metal sleeve. The stem may also be trimmed to length with the excess stem being trimmed off. In all instances, the serrated stem and push-on locking cap result in the implant being secured into place within the facet joint. 
         [0028]    According to a sixth embodiment of the present invention, the implant may include a screw-on locking cap and a spacer with a threaded stem (or stems). The screw-on locking cap may have an attached screw sleeve. By way of example only, the stem, screw-on locking cap, and screw sleeve may be made of metal or a polymer. Next, a bore (or bores) is drilled completely through the superior articular process of the inferior vertebra. The bore may be sized to fit the screw sleeve. The stem is passed through the bore in the superior articular process of the inferior vertebra, and the connected spacer is inserted between the articular facets of the facet joint. 
         [0029]    Once the spacer and stem are placed within the facet joint, the screw-on locking cap is screwed onto the threaded stem and fixated to the outer surface of the superior articular facet of the inferior vertebra. The stem may then be trimmed to length. In addition, the base of the cap may have barbs to help facilitate fixation to the bone on the outer surface of the articular process. The barbs may be placed circumferentially in one direction. This is advantageous because it helps ensure the barbs grip to the bone surface. It will be appreciated that the feature of the barbs are not limited to this sixth embodiment and may be included in the other embodiments described herein without departing from the scope of the present invention. In all instances, the threaded stem and push-on locking cap result in the implant being secured into place within the facet joint. 
         [0030]    According to a seventh embodiment of the present invention, the implant may include a screw and a spacer. The spacer may include a radio opaque washer plate, screw hole and cover flap. The spacer is inserted between the articular facets of the facet joint. Once implanted, the spacer is screwed directly into position in the facet joint. The screw passes through the screw hole in the spacer and is drilled into the superior articular process of the inferior vertebra. The screw is then tightened against the radio opaque washer plate in the spacer. 
         [0031]    Once the screw secures the spacer into place, the cover flap is then folded to encapsulate the screw head. The cover flap provides additional padding and protection on the spacer between the screw and the superior articular facet of the inferior vertebra so that there is no contact between the rigid surfaces of the screw and the bone. The cover flap may include a screw hole filler that fills in the gap from the screw head to the height of the spacer. The feature of a cover flap is not limited to this embodiment only and may be included in the other embodiments of the implant described herein without departing from the scope of the present invention. 
         [0032]    According to an eighth embodiment of the present invention, the implant may include a screw and a spacer with a screw hole, reinforced fixation hole, and mesh cover. The spacer is inserted between the articular facets of the facet joint. Once implanted, the spacer is screwed directly into position in the facet joint. The screw passes through the mesh cover and screw hole in the spacer. The screw is drilled into the superior articular process of the inferior vertebra. The screw is then tightened against the reinforced fixation hole in the spacer and the implant is secured in the facet joint. 
         [0033]    The reinforced fixation hole in the spacer is designed to provide reinforcement in the spacer to ensure that the screw does not tear through the spacer. The mesh cover in the spacer is designed to allow the entire screw and screw head to pass through and close over it. The mesh cover then encapsulates the screw head. Although the reinforced fixation hole and mesh cover are described in this particular embodiment, it will be appreciated that these features are not limited to this embodiment and can be applied to any other embodiment described herein without departing from the scope of the present invention. 
         [0034]    As previously described, the spacer may be formed of a textile/fabric material. By way of example only, a base textile structure may be used to form the spacer. The base textile structure is preferably manufactured via an embroidery process well known in the art using any number of biocompatible filament materials (including but not limited to polyester thread). The base textile structure may be comprised of a plurality of hinged embroidered layer regions. The mesh cover layer, which is an outer layer region of the base textile structure, is loosely constructed to allow an entire screw and screw head to pass through it. The other layer regions have screw holes to facilitate the screw fixation of the spacer into the bone. Furthermore, the base layer contains the reinforced fixation hole, which is densely embroidered to provide reinforcement in the spacer so that the screw does not tear through the spacer. 
         [0035]    The layer regions of the base textile structure are connected together in side-by-side relation and separated by a distance to form a plurality of hinge regions between the layer regions. Then the base textile structure is then folded to form the spacer. The layer regions are folded at the hinge regions such that the layer regions are stacked together. The folding process may be performed in any number of manners as long as the mesh cover layer is placed on one outside surface of the spacer and the base layer is placed on the other outside surface of the spacer after being stacked together. It will be appreciated that any number of layer regions may be used to create the base textile structure and form the spacer without departing from the scope of the present invention. This may be done for any number of different purposes, including but not limited to varying the thickness of the spacer. 
         [0036]    According to a ninth embodiment of the invention the implant comprises a pin element and a spacer including an attached centrally located attachment flange. Insertion of the implant is achieved by inserting the spacer within the facet joint, passing the centrally located attachment flange through an aperture spanning the targeted articular process, and finally inserting a pin element through an aperture in the central attachment flange. The central attachment flange is disposed with multiple pin element receiving apertures. Provision of multiple apertures within the central attachment flange affords the clinician the ability to select and preserve preferential central attachment flange tension and positioning, thereby preserving optimal implant positioning. Preferential spacer positioning is achieved by pulling the central attachment flange distally from the articular process, thereby exposing successive central attachment flange apertures near the articular process surface while pulling the spacer against the targeted articular facet. Once proper implant tension and positioning has been achieved, the pin element is inserted into the aperture immediately proximate to the articular process, thereby preventing central attachment flange egress into the articular process aperture, thus sustaining spacer positioning within the facet joint. 
         [0037]    According to a tenth embodiment of the invention, the implant comprises an anchoring element and a spacer comprising an attached fixation bracket and anchorage member. Insertion of the implant begins with insertion of the spacer within the facet joint and passing the anchorage member through an aperture in the targeted articular process. Subsequently the fixation bracket is aligned with the targeted articular process and the anchorage member is inserted through a fixation bracket aperture. Preferential spacer positioning is achieved by pulling the anchorage member distally from the articular process and spacer to establish tension along the anchorage member, thereby pulling the spacer against the targeted articular facet. Anchorage member tension and spacer positioning are finally preserved through attachment of an anchoring element to the anchorage member immediately proximate to the fixation bracket thereby preventing anchorage member egress into the articular process aperture. 
         [0038]    According to an eleventh embodiment of the present invention, the implant includes a spacer which may or may not include an encapsulating jacket as described above. Preferably, the spacer may be of textile construction (e.g. embroidered or woven), however other materials are possible, such as for example metals, plastics, glass, etc. The spacer is secured in place using a tie cord and fixation screw. The screw includes a head and a threaded shaft. The head includes a shaped engagement element dimensioned to engage an insertion device and an aperture dimensioned to allow passage of the tie cord therethrough. 
         [0039]    In use, the tie cords function not only to secure the facet implant within the facet joint, but also to deliver the implant to the facet joint. To accomplish this, a bore is first formed through the facet surface of the superior articular process of the inferior vertebra. The tie cord is threaded through aperture of screw, and the screw is then threadedly inserted into the bore. Once the screw has been seated within the superior articular process, the tie cords are passed approximately through the middle of implant. The implant is then advanced along the tie cords into the facet joint. Once the implant has been preferentially seated within the facet joint, the tie cords may be tied to secure the implant in place, and excess tie cord may then be severed and removed. 
         [0040]    According to a twelfth embodiment of the present invention, the implant includes a spacer and encapsulating jacket. The jacket includes a body portion having an additional pad that includes a fusion-inducing biologic agent, such as bone morphogenic protein (BMP), stem cell based material, calcium hydroxyapatite, demineralized bone matrix, or Formagraft® offered by NuVasive. The pad including the biologic agent may be provided on either side or both sides of the body portion. 
         [0041]    In use, the implant is inserted into the facet joint such that the pads are in contact with articular processes forming the facet joint. Providing the pad on both sides encourages fusion of the implant with the facet joint. The degree of fusion that occurs may be controlled depending on the needs of the user, as described in relation to several of the examples presented above. Fusion may be achieved at least with the encapsulating jacket such that any facet motion that occurs is within the implant. 
         [0042]    According to one embodiment of the present invention, a spacer may provided that allows for internal movement within a facet implant such as any of the examples discussed above. The spacer may be provided with or without an encapsulating jacket. The spacer is similar to those shown and described in the above-referenced &#39;944 PCT Application. The spacer is comprised of a plurality of textile layers coupled by a plurality of hinge regions and assembled in an accordion-like manner. Other assemblies are possible, however, for example including but not limited to a plurality of individual textile layers consecutively stacked upon one another and/or a single continuous textile sheet folded upon itself to form a plurality of stacked textile layer regions. Upon assembling the spacer will comprise a pair of “outside” textile layers separated by a number of “interior” textile layers. A supplemental stitching may provided through the various textile layers to tether the layers together and increase stability of the implant. 
         [0043]    The textile layers may be provided in any number and configuration without departing from the scope of the present invention. For example, the interior textile layers may be untreated or in the alternative treated with an anti-fusion agent in order to prevent any tissue and/or bony ingrowth through those layers. Furthermore, the layers may be chemically treated or manufactured such that they are capable of moving relative to one another. The outside textile layers are formed from or treated with fusion-inducing materials to cause tissue and/or bony ingrowth between the bone and the specific outside textile layers. The result is a facet implant including a layered spacer that achieves a textile-bone fusion interface with the facet surface of the superior articular process of a first vertebra and a textile-bone fusion interface with the facet surface of the inferior articular process of a second vertebra. However, facet motion is retained due to the capability of the interior layers to move or slide relative to one another in response to movement of the articular processes. As such, the spacer allows for a “controlled slippage” of the interior textile layers such that at least partial motion within the facet joint may be preserved. Movement of the layers is controlled due to the hinge regions and supplemental stitching as well as an encapsulating jacket (if provided), all of which function to limit the range of motion of the textile layer regions. 
         [0044]    Many of the facet implant examples described above encourage at least some tissue and/or bony ingrowth in order to either secure the implant in place or promote complete fusion of the facet joint. Upon successful tissue and/or bony ingrowth, biodegradation, bioresorbtion, bioabsorbtion, bioabsorption, and/or bioerosion of the implant or portions thereof may be encouraged depending upon the desired motion preservation characteristics of the facet joint. For the purposes of this disclosure, bioresorbtion is meant to include any biological process (including those delineated above) in which at least a portion of the fabric component of the implant disappears or becomes detached from the rest of the implant. 
         [0045]    According to a fourteenth embodiment of the present invention, the implant includes a spacer and encapsulating having a body portion and a plurality of attachment flanges. The encapsulating fabric of the implant includes a portion (e.g. a strip) of bioresorbable fabric on each flange adjacent to the body portion. As such, over time the bioresorbable fabric will disappear, causing the body portion and flanges to become detached from one another. The flanges may be secured to the relevant bone portions using any suitable means of attachment, for example including but not limited to bone screws, staples, sutures, nails, buttons, anchors, and/or adhesives. 
         [0046]    Alternatively, according to a fifteenth embodiment of the present invention, the implant as described above includes portions of the encapsulating fabric forming the flanges which are entirely bioresorbable, and after resorbtion only the spacer is left within the facet joint. 
         [0047]    According to one embodiment of the present invention, an inserter assembly may be used to insert an implant into a facet joint. In this embodiment, the inserter assembly is designed to releasably maintain the implant in the proper orientation for insertion. The implant may be introduced into a facet joint while engaged with the inserter and thereafter released. Preferably, the inserter may include a distal engagement region and an elongated handling member. The inserter may be composed of any material suitable for inserting an implant into a facet joint, including but not limited to metal (e.g. titanium), ceramic, and/or polymer compositions. According to this particular embodiment, the distal engagement region is comprised of an insertion plate. The insertion plate is generally planar rectangular in shape, but may take the form of any geometric shape necessary to interact with the implant, including but not limited to generally oval, square, and triangular. The handling member is generally cylindrical in shape. The handling member allows a clinician to manipulate the tool during an implant insertion procedure. 
         [0048]    In order to facilitate engagement with the inserter, the spacer of the implant may include a pocket. By way of example only, the pocket may be an extra layer of embroidered fabric attached to three of the four sides of the spacer, leaving an opening for insertion of the insertion plate. The insertion plate engages with the implant by sliding into the pocket. Although slideable engagement is described herein, any suitable means of engagement may be used to engage the insertion plate with the implant, including but not limited to a threaded engagement, snapped engagement, hooks, and/or compressive force. Once the insertion plate is fit into place within the pocket of the implant, the inserter releasably maintains the implant in the proper orientation for insertion. The implant may then be introduced into a facet joint while engaged with the inserter and thereafter released. The implant, having been deposited in the facet joint, facilitates improved spinal functionality over time by maintaining a restored foraminal space (due to the structural and load-bearing capabilities of the implant) as well as enabling a desired range of motion (e.g. physiologic motion, current motion, improved motion, reduced motion, restricted motion, zero motion and/or no restriction to motion). 
         [0049]    According to another embodiment of the present invention, an inserter assembly may include a distal engagement region comprised of two insertion prongs. Preferably, the insertion prongs are generally cylindrical in shape, but may take the form of any geometric shape necessary to interact with the implant. In order to facilitate engagement with the insertion prongs, the spacer of the implant may have attached side pockets. By way of example only, the side pockets may be made of embroidered fabric attached to each side of the spacer with openings for insertion of the insertion prongs. 
         [0050]    The insertion prongs engage with the implant by sliding into the side pockets. Although slideable engagement is described herein, any suitable means of engagement may be used to engage the insertion prongs with the implant, including but not limited to a threaded engagement, snapped engagement, hooks, and/or compressive force. Once the insertion prongs are fit inside the side pockets of the implant, the inserter releasably maintains the implant in the proper orientation for insertion. The implant may then be introduced into a facet joint while engaged with the inserter and thereafter released. It will be appreciated that the number of insertion prongs is set forth by way of example only and may be increased or decreased without departing from the scope of the present invention. In all instances, the implant, having been deposited in the facet joint, facilitates improved spinal functionality over time by maintaining a restored foraminal space (due to the structural and load-bearing capabilities of the implant) as well as enabling a desired range of motion. 
         [0051]    It will be appreciated that the inserter assembly and added pockets may be used with any embodiment of the implant described herein without departing from the scope of the invention. Furthermore, the inserter of the present invention is not limited to interaction with the implant disclosed herein, but rather may be dimensioned to engage any surgical implant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0052]    Many advantages of the present invention will be apparent to those skilled in the art with a reading of this specification in conjunction with the attached drawings, wherein like reference numerals are applied to like elements and wherein: 
           [0053]      FIG. 1  is a perspective view of an example of a facet implant according to a first embodiment of the present invention; 
           [0054]      FIG. 2  is a perspective view of a spacer forming part of the implant of  FIG. 1 ; 
           [0055]      FIG. 3  is a perspective view of the implant of  FIG. 1  positioned within a damaged facet joint; 
           [0056]      FIG. 4  is a perspective view of two implants of  FIG. 1  positioned within adjacent facet joints in one level of the spine; 
           [0057]      FIG. 5  is a perspective view of the implant of  FIG. 1  positioned within a facet joint in the spine, showing the attachment flanges secured to the adjacent vertebrae with screws; 
           [0058]      FIG. 6  is a side view of an example of an alternative bone anchor that can be used to secure the attachment flanges of the implant of  FIG. 1  to adjacent vertebrae; 
           [0059]      FIG. 7  is a perspective view of the implant of  FIG. 1  positioned within a facet joint in the spine, showing the use of the bone anchors of  FIG. 6  to secure the attachment flanges to the adjacent vertebrae; 
           [0060]      FIG. 8  is a perspective view of the implant of  FIG. 1  positioned within a facet joint in the spine, showing the attachment flanges secured to the adjacent vertebrae with the bone anchors of  FIG. 6 ; 
           [0061]      FIG. 9  is a perspective view of the implant of  FIG. 1  having two attachment flanges positioned within a facet joint in the spine and secured with screws; 
           [0062]      FIG. 10  is a perspective view of an example of a facet implant according to a second embodiment of the present invention, having a centrally located attachment flange and without an encapsulating jacket; 
           [0063]      FIG. 11  is a perspective view of the implant of  FIG. 10  positioned within a facet joint in the spine, showing the attachment flanges secured to the adjacent vertebrae with bone anchors of  FIG. 6  and the centrally located attachment flange secured with a screw; 
           [0064]      FIG. 12  is a perspective view of the implant of  FIG. 10  having a single centrally located attachment flange, according to an alternate embodiment of the implant of  FIG. 10 ; 
           [0065]      FIG. 13  is a perspective view of the implant of  FIG. 12  positioned within a facet joint in the spine, showing the single centrally located attachment flange secured with a screw; 
           [0066]      FIG. 14  is a perspective view of the implant of  FIG. 10  in use with a clamping mechanism, according to another embodiment of the implant of  FIG. 10 ; 
           [0067]      FIG. 15  is a perspective view of the implant of  FIG. 14  positioned within a facet joint in the spine, showing two attachment flanges secured to the adjacent vertebra with bone anchors and the single centrally located attachment flange secured with a clamping mechanism; 
           [0068]      FIG. 16  is a perspective view of an example of a facet implant according to a third embodiment of the present invention, having tie cords in use with a button; 
           [0069]      FIG. 17  is a side cross-sectional view of the implant of  FIG. 16  positioned within a facet joint; 
           [0070]      FIG. 18  is a perspective view of the implant of  FIG. 16  positioned within a facet joint in the spine, showing the tie cords secured to the superior articular facet of the inferior vertebra with a button; 
           [0071]      FIG. 19  is a perspective view of the implant of  FIG. 16 ; 
           [0072]      FIG. 20  is a side cross-sectional view of the implant of  FIG. 19 , showing various features of an internal metal plate, a low adhesion layer, a non-soluble substrate layer, and an adhesive layer that are part of the spacer; 
           [0073]      FIG. 21  is a perspective view of an example of a facet implant according to fourth embodiment of the present invention, having a toggle element; 
           [0074]      FIG. 22  is a side cross-sectional view of the implant of  FIG. 21  positioned within a facet joint, showing the deployed toggle element; 
           [0075]      FIG. 23  is a perspective view of the implant of  FIG. 21  positioned within a facet joint in the spine, showing the deployed toggle element used to secure the implant to the superior articular facet of the inferior vertebra; 
           [0076]      FIG. 24  is a perspective view of an example of a facet implant according to a fifth embodiment of the present invention, having a serrated stem and a push-on locking cap; 
           [0077]      FIG. 25  is a side cross-sectional view of the implant of  FIG. 24  positioned within a facet joint, showing the push-on locking cap secured on the stem of the spacer to the outside of the articular facet; 
           [0078]      FIG. 26  is a perspective view of the implant of  FIG. 24  positioned within a facet joint in the spine, showing the push-on locking cap and stem securing the implant to the superior articular facet of the inferior vertebra; 
           [0079]      FIG. 27  is a perspective view of an example of a facet implant according to a sixth embodiment of the present invention, having a threaded stem and a screw-on locking cap; 
           [0080]      FIG. 28  is a side cross-sectional view of the implant of  FIG. 27  positioned within a facet joint; 
           [0081]      FIG. 29  is a perspective view of the implant of  FIG. 27  positioned within a facet joint in the spine, showing the screw-on locking cap and stem securing the implant to the superior articular facet of the inferior vertebra; 
           [0082]      FIG. 30  is a side view of the screw-on locking cap from the implant of  FIG. 27  having the added feature of barbs on the base of the cap; 
           [0083]      FIG. 31  is a bottom plan view of the screw-on locking cap of  FIG. 30 , showing the barbs placed circumferentially in one direction; 
           [0084]      FIG. 32  is a side view of a single barb on the screw-on locking cap of  FIG. 31 ; 
           [0085]      FIG. 33  is a perspective view of an example of a facet implant according to a seventh embodiment of the present invention, including a screw and a spacer with a cover flap; 
           [0086]      FIG. 34  is a side cross-sectional view of the implant of  FIG. 33  positioned within a facet joint; 
           [0087]      FIG. 35  is a perspective view of the implant of  FIG. 33  positioned within a facet joint in the spine, showing the screw directly securing the spacer to the inferior articular facet of the superior vertebra; 
           [0088]      FIG. 36  is a perspective view of an example of a facet implant according to an eighth embodiment of the present invention, including a screw and a spacer with a mesh cover; 
           [0089]      FIG. 37  is a perspective view of the implant of  FIG. 36  illustrating how the screw passes through the mesh cover of the spacer; 
           [0090]      FIG. 38  is a side cross-sectional view of the implant of  FIG. 36  positioned within a facet joint, showing the screw directly securing the spacer to the inside of the articular facet; 
           [0091]      FIG. 39  is a top plan view of a base textile structure used to form a spacer having five layer regions, one outer layer region being a mesh cover and the other outer layer region containing a reinforced fixation hole; 
           [0092]      FIG. 40  is a top view of an inserter assembly and an implant with a pocket to facilitate engagement with the inserter assembly, according to one embodiment of the present invention for insertion of an implant into a facet joint; 
           [0093]      FIG. 41  is top view of the inserter assembly and implant of  FIG. 40  in an engaged relationship; 
           [0094]      FIG. 42  is a top view of an inserter assembly having two prongs and an implant with side pockets to facilitate engagement with the inserter assembly, according to another embodiment of the present invention for insertion of an implant into a facet joint; 
           [0095]      FIG. 43  is a top view of the inserter assembly and implant of  FIG. 42  in an engaged relationship; 
           [0096]      FIG. 44  is a perspective view of an example of a facet implant according to a ninth embodiment of the present invention; 
           [0097]      FIGS. 45-46  are side partial cross-sectional views of the facet implant of  FIG. 44 , inserted within a facet joint and attached to the superior facet; 
           [0098]      FIG. 47  is a perspective view of the facet implant of  FIG. 44  in use with an alternate pin element; 
           [0099]      FIG. 48  is a plan view of the pin element of  FIG. 47 ; 
           [0100]      FIG. 49  is a perspective view of the facet implant of  FIG. 44  in use with another alternate pin element; 
           [0101]      FIGS. 50-51  are plan views of the pin element of  FIG. 49 , in unassembled and assembled states, respectively; 
           [0102]      FIG. 52  is a perspective view of an example of a facet implant according to a tenth embodiment of the present invention; 
           [0103]      FIG. 53  is a side cross-sectional view of the facet implant of  FIG. 52  inserted within a facet joint and attached to the superior facet; 
           [0104]      FIG. 54  is a perspective view of the facet implant of  FIG. 52  inserted within a facet joint of a spine; 
           [0105]      FIGS. 55-57  are perspective views of an example of an anchoring element used to secure the implant of  FIG. 52  to the facet; 
           [0106]      FIGS. 58-60  are perspective views of an example of an alternate anchoring element of used to secure the implant of  FIG. 52  to the facet; 
           [0107]      FIG. 61  is a perspective view of an example of a facet implant according to an eleventh embodiment of the present invention, being inserted into a facet joint; 
           [0108]      FIGS. 62-63  are perspective views of alternative examples of anchoring elements used to secure the implant of  FIG. 61  to the facet; 
           [0109]      FIG. 64  is a plan view of the implant of  FIG. 61 ; 
           [0110]      FIG. 65  is a perspective view of the implant of  FIG. 61  inserted within a spine; 
           [0111]      FIG. 66  is a perspective view of an example of a facet implant according to a twelfth embodiment of the present invention; 
           [0112]      FIG. 67  is a perspective view of the implant of  FIG. 66  inserted within a facet joint; 
           [0113]      FIG. 68  is a side view of the implant of  FIG. 66  inserted within a facet joint, before fusion with the bone has occurred; 
           [0114]      FIG. 69  is a side view of the implant of  FIG. 66  inserted within a facet joint, after fusion with the bone has occurred; 
           [0115]      FIG. 70  is a perspective view of the implant of  FIG. 66  inserted within a spine after fusion has occurred; 
           [0116]      FIG. 71  is a perspective view of an example of an unfolded spacer forming part of a facet implant according to a thirteenth embodiment of the present invention; 
           [0117]      FIG. 72  is a side view of the spacer of  FIG. 71  in a folded state; 
           [0118]      FIG. 72  is a side view of the spacer of  FIG. 71  including additional stitching through the various layers to secure the spacer together; 
           [0119]      FIGS. 74-75  are side and sectional views, respectively, of a facet implant including the spacer of  FIG. 71  implanted within a facet joint, showing disposition of the various layers during flexion; 
           [0120]      FIGS. 76-77  are side and sectional views, respectively, of a facet implant including the spacer of  FIG. 71  implanted within a facet joint, showing disposition of the various layers during extension; 
           [0121]      FIG. 78  is a perspective view of an example of a facet implant according to a fourteenth embodiment of the present invention, including flanges having biodegradable fabric portions; 
           [0122]      FIG. 79  is a perspective view of the implant of  FIG. 78  inserted within a facet joint; 
           [0123]      FIG. 80  is a perspective view of the implant of  FIG. 79  inserted with a facet joint with flanges secured to adjacent bone tissue, before degradation of the biodegradable fabric portions; 
           [0124]      FIG. 81  is a perspective view of the implant of  FIG. 80  inserted with a facet joint with flanges secured to adjacent bone tissue, after degradation of the biodegradable fabric portions; 
           [0125]      FIG. 82  is a perspective view of an example of a facet implant including a biodegradable fabric jacket according to a fifteenth embodiment of the present invention, the facet implant inserted into a facet joint and before degradation of the biodegradable fabric jacket; and 
           [0126]      FIG. 83  is a perspective view of the facet implant of  FIG. 82  after degradation of the fabric jacket. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0127]    Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The systems disclosed herein boast a variety of inventive features and components that warrant patent protection, both individually and in combination. 
         [0128]    A variety of embodiments may be used to construct the implant of the present invention. Generally, the implant disclosed herein comprises a spacer provided with or without an encapsulating jacket. Examples of specific embodiments of the implant are described in detail below. The implant disclosed herein is suitable for use in a variety of surgical applications, including but not limited to spine surgery. When applied to spinal surgery and implanted within a facet joint, the implant repairs/reconstructs a degenerative facet joint, thereby restoring the foraminal space and preserving the natural motion of the spine. To repair/reconstruct a facet joint, the implant is positioned between a superior articular facet (of an inferior vertebra) and an inferior articular facet (of a superior vertebra) to prevent bone-on-bone contact. The compliant nature of the implant provides the required flexibility and elasticity to advantageously support the full range of physiological movements, as opposed to fusion surgery which forms a boney bridge between adjacent articular processes. In addition, the porosity and biocompatibility of the implant may facilitate tissue and/or bony ingrowth throughout part or all of the implant (if desired), which helps to secure and encapsulate the implant in a facet joint. 
         [0129]    A variety of materials can be used to form the spacer and/or encapsulating jacket of the implant. The spacer is preferably formed of biocompatible material. In one embodiment, the spacer is formed of a textile/fabric material throughout, similar to that shown and described in commonly owned and co-pending PCT Application Serial No. PCT/US2008/060944 entitled “Textile-Based Surgical Implant and Related Methods, filed Apr. 18, 2008, the entire contents of which are hereby incorporated by reference into this disclosure as if set forth fully herein. The textile/fabric spacer may be constructed from any of a variety of natural or synthetic fibrous materials, for example including but not limited to polyester fiber, polypropylene, polyethylene, ultra high molecular weight polyethylene (UHMWPe), poly-ether-ether-ketone (PEEK), carbon fiber, glass, glass fiber, polyaramide, metal, copolymers, polyglycolic acid, polylactic acid, biodegradable fibers, nylon, silk, cellulosic and polycaprolactone fibers. The spacer may be manufactured via any number of textile processing techniques (e.g. embroidery, weaving, three-dimensional weaving, knitting, three-dimensional knitting, injection molding, compression molding, cutting woven or knitted fabrics, etc.). For the purposes of this disclosure, “textile” is meant to include any fibrous material (including but not limited to those delineated above) processed by any textile processing technique (including but not limited to those delineated above). In another embodiment, the spacer comprises at least one of an elastomer (e.g. silicon), hydrogel, hydrogel beads, plastic mesh, plastic constructs, injectable fluids, curable fluids, hair and hair constructs encapsulated in fabric, similar to that shown and described in commonly owned U.S. Pat. No. 6,093,205 entitled “Surgical Implant,” issued Jul. 25, 2000, the entire contents of which are hereby incorporated by reference into this disclosure as if set forth fully herein. 
         [0130]    The encapsulating jacket may be constructed from any of a variety of natural or synthetic fibrous materials, for example including but not limited to polyester fiber, polypropylene, polyethylene, ultra high molecular weight polyethylene (UHMWPe), poly-ether-ether-ketone (PEEK), carbon fiber, glass, glass fiber, polyaramide, metal, copolymers, polyglycolic acid, polylactic acid, biodegradable fibers, nylon, silk, cellulosic and polycaprolactone fibers. The jacket may be manufactured via any number of textile processing techniques (e.g. embroidery, weaving, three-dimensional weaving, knitting, three-dimensional knitting, injection molding, compression molding, cutting woven or knitted fabrics, etc.). The jacket may encapsulate the spacer fully (i.e. disposed about all surfaces of the spacer) or partially (i.e. with one or more apertures formed in the jacket allowing direct access to the spacer). The various layers and/or components of the spacer may be attached or unattached to the encapsulating jacket. The jacket may optionally include one or more fixation elements for retaining the jacket in position after implantation, including but to limited to at least one flange extending from or otherwise coupled to the jacket and screws or other affixation elements (e.g. nails, staples, sutures, adhesives, tacks, etc.) to secure the flange to an adjacent anatomical structure (e.g. vertebral body). This may be facilitated by providing one or more apertures within the flange(s) dimensioned to receive the screws or other fixation elements. 
         [0131]    The materials selected to form the spacer and/or jacket may be specifically selected depending upon the target location/use within the body (e.g. spinal, general orthopedic, and/or general surgical). For example in many instances it may be preferable to select UHMWPe fibers in order to generate a specific tissue response, such as limited tissue and/or bony ingrowth. In some instances it may be desirable to modify the specific fibers used, such as providing a surface modification to change or enhance a desired tissue response. 
         [0132]    In all cases, it will be understood that the spacer disclosed herein reduces the risk of progressive slip and the onset of lower back pain by alleviating the mechanical stress on the facet joint. Furthermore, although shown in many of the examples described below as having a generally rectangular shape, the spacer may be provided in any number of suitable dimensions depending upon the surgical application and patient pathology. Furthermore, use of the implant disclosed herein is not limited to a single facet joint, but rather can be used in multiple joints at multiple levels within the spine, as needed.  FIG. 4  illustrates, by way of example only, the use of two implants  10  placed in the adjacent facet joints  18  at one level of the spine. 
         [0133]      FIGS. 1-9  illustrate an example of a facet implant  10  according to a first embodiment of the present invention. Implant  10  includes a spacer  12  (shown by itself in  FIG. 2 ) disposed within an encapsulating jacket  14  having a plurality of attachment flanges  16 . In the example shown in  FIG. 1 , the jacket  14  includes a body portion  15  that at least partially surrounds the spacer  12 . The attachment flanges  16  extend from one end of the body portion  15  such that upon insertion within a facet joint, the flanges  16  will all extend outside the joint in a similar manner. To repair/reconstruct a facet joint  18 , the implant  10  is positioned between a superior articular facet  21  (of an inferior vertebra  26 ) and an inferior articular facet  23  (of a superior vertebra  28 ) to prevent bone-on-bone contact, as shown in  FIG. 3 . 
         [0134]    Once the spacer  12  is implanted between the articular facets  21 ,  23  of the facet joint  18 , attachment flanges  16  secure the implant  10  in situ, as shown in  FIGS. 5 &amp; 8 . The attachment flanges  16  may be constructed from any of a variety of material (e.g. polyester) via any number of techniques (e.g. embroidery). As shown in  FIGS. 5 &amp; 8  by way of example only, two attachment flanges  16  wrap around the adjacent inferior vertebra  26 , and two attachment flanges  16  wrap around the adjacent superior vertebra  28 . The attachment flanges  16  are then fastened to the adjacent vertebrae  26 ,  28  by screws  30 , as shown in  FIG. 5 , or other affixation elements (e.g. nails, staples, sutures, buttons, anchors, etc.). The attachment flanges  16  may be attached to any suitable portion of the vertebrae, including but not limited to the vertebral body, spinous process, pedicle, lamina, superior and/or inferior articular facet, articular process, and/or any combination thereof. Any number of screws  30  or screw holes  32  in the attachment flanges  16  may be used to affix the implant  10  in situ. In a preferred embodiment, the attachment flanges  16  comprise an embroidered textile material provided with load-bearing reinforced holes  32  that are resistant to tearing under stress. 
         [0135]    As shown in  FIG. 8 , alternative bone anchors  34  may be used to affix the attachment flanges  16  to the adjacent vertebrae  26 ,  28 .  FIG. 6  shows a single alternative bone anchor  34  with a metal portion  36  and sutures  38  extending therefrom. The metal portion  36  includes a proximal head region  37   a,  a shaft region  37   b,  and a distal tip  37   c.  The head region  37   a  includes an engagement element (not shown) dimensioned to engage a suitable insertion element. Examples of engagement elements include a recess, protrusion, clip, etc. The head region  37   a  further includes an attachment element (not shown) for facilitating attachment of the sutures  38  which extend proximally therefrom, including but not limited to (for example) a loop, clip, and/or adhesive. The shaft region  37   b  is preferably threaded to allow purchase within the facet bone. The distal tip  37   c  includes a pointed tip to allow for initial penetration into the bone. Referring to  FIG. 7 , the metal portion  36  of the bone anchor  34  is drilled into the vertebra  28 . The sutures  38  of the bone anchor  34  slide through the attachment flanges  16  and the sutures  38  are then knotted (or tied, etc.) to secure the attachment flanges  16  to the adjacent vertebrae  26 ,  28 . 
         [0136]    Although the implant  10  is shown in  FIGS. 1-8  as having four attachment flanges  16 , it will be appreciated that this is set forth by way of example only and that the number of attachment flanges may be increased or decreased without departing from the scope of the present invention. For example in  FIG. 9 , only two attachment flanges  16  are used to affix the implant  10  in situ. In all instances, the attachment flange(s)  16  results in the implant  10  being secured into place within the facet joint  18 . 
         [0137]    Although described above as having an encapsulating jacket  14 , the facet implant of the present invention may be provided without an encapsulating jacket. For example,  FIGS. 10 &amp; 11  illustrate an example of a facet implant  10   a  according to a second embodiment of the present invention. The implant  10   a  comprises a spacer  12  with attachment flanges  16  that are directly connected to the spacer  12  (instead of being connected to an encapsulating jacket). In this embodiment, the spacer  12  may also have a centrally located attachment flange  40 . A bore  42  is drilled completely through the superior articular process  20  of the inferior vertebra  26 . The centrally located attachment flange  40  on the spacer  12  passes through the bore  42  in the superior articular process  20  of the inferior vertebra  26  and is then secured into position on the outer surface of the articular process by a screw  30  or any other fixation element (e.g. nails, staples, sutures, buttons, anchors, etc.). The attachment flanges  16  may then be fastened to the adjacent vertebrae  26 ,  28  by bone anchors  34  or other previously mentioned fixation elements. The attachment flanges  16  and centrally located attachment flange  40  may be attached to any suitable portion of the vertebrae, including but not limited to the vertebral body, spinous process, pedicle, lamina, superior and/or inferior articular facet, articular process, and/or any combination thereof. 
         [0138]    Although described in all embodiments herein largely in terms of attaching the spacer  12  to the superior articular process  20  of the inferior vertebra  26 , it will be understood that the spacer  12  may be attached to the inferior articular process  22  of the superior vertebra  28  without departing from the scope of the present invention. In all instances, the implant  10  is situated in the facet joint  18  and will result in the repair/reconstruction of the degenerative joint. 
         [0139]    Any number of attachment flanges  16 , centrally located attachment flanges  40 , screw holes  32 , and screws  30  or other fixation elements may be used to affix the implant  10   a  in situ. Although the implant  10   a  is shown in  FIGS. 10 &amp; 11  as having four attachment flanges  16 , it will be appreciated that this number is set forth by way of example only and that the number of attachment flanges may be increased or decreased without departing from the scope of the present invention. According to a further embodiment of the present invention, as shown in  FIGS. 12 &amp; 13 , the implant  10   a  may be comprised solely of the centrally located attachment flange  40  connected to the spacer  12 . In another embodiment, the implant  10   a  may be comprised solely of attachment flanges  16  connected to the spacer  12  without a centrally located attachment flange  40 . In all instances, the attachment flanges  16 ,  40  result in the implant  10   a  being secured into place within the facet joint  18 . 
         [0140]    As shown in  FIGS. 14 &amp; 15  by way of example only, a clamping mechanism  44  may be used to affix the spacer  12  to the superior articular process  20  of the inferior vertebra  26 . After the centrally located attachment flange  40  of the spacer  12  is passed through the bore  42  in the superior articular process  20  of the inferior vertebra  26 , the centrally located attachment flange  40  is passed through the hole  46  in the middle of the clamping mechanism  44 . The clamping mechanism  44  slides up the centrally located attachment flange  40  until it is pressed firmly against the outer surface of the articular process  20 . The bolt  48  in the clamping mechanism  44  is then tightened to securely hold the centrally located attachment flange  40  into place. This, in turn, anchors the implant within the facet joint  18 . Additionally, the attachment flanges  16  may then be fastened to the adjacent vertebrae  26 ,  28  by bone anchors  34  or other previously mentioned fixation elements. 
         [0141]    Referring to  FIG. 15 , the implant  10   a  is shown having only two attachment flanges. As previously mentioned, the number of attachment flanges may be increased or decreased without departing from the scope of the present invention. Furthermore, it will be appreciated that the clamping mechanism  44  is not limited to the second embodiment of the present invention (describing implant  10   a ) and may be used with any embodiment of the facet implant described herein without departing from the scope of the present invention. 
         [0142]      FIGS. 16-20  collectively illustrate an example of a facet implant  10   b  according to a third embodiment of the present invention. According to this embodiment, the implant  10   b  comprises a spacer  12  with directly attached tie cords  116 . Tie cords  116  are preferably attached to and/or protrude from approximately the middle of one side of the spacer  12 . At least one bore  42  is drilled completely through the superior articular process  20  of the inferior vertebra  26 . The spacer  12  is inserted in the facet joint  18  and the tie cords  116  are manipulated to pass through the bore  42  in the superior articular process  20 . The tie cords  116  are then secured on the outer surface of the articular process  20 . In the example shown, the tie cords  116  are secured to the outer surface of the articular process  20  using a button  130 . Button  130  includes a pair of centrally positioned apertures  132  extending therethrough, the apertures  132  dimensioned to allow passage of the tie cords  116 . The tie cords  116  may then be tied together to form a knot  133  with the button positioned in between the knot and the outer surface of the articular process  20 . The button further includes a bone-contacting surface  134  that are provided with anti-migration elements  136  to prevent the button from shifting relative to the bone once the knot  133  is formed. By way of example only, anti-migration features  136  may include spikes, ridges, indentations, roughness, and/or adhesives. Although shown using a button  130 , the tie cords  116  may be secured through any suitable method, for example including but not limited sutures, anchors, screws, crimps, adhesives, and/or any other fixation element. 
         [0143]    As shown in  FIG. 18 , the tie cords  116  are tied into a knot  133  after passage through apertures  132  in the button  130 . The button  130  may be composed of any kind of material, such as metal (e.g. titanium), a polymer (e.g. a barium loaded polyester), or fabric (e.g. a densely embroidered textile plate). A metal or polymer button  130  may be roughened or spiked on its rear surface to engage with the facet bone, as shown in  FIG. 17 . It may also be coated with calcium hydroxyapatite to further lock to the bone. In all instances, the tie cords  116  and button  130  (or other fixation element) result in the implant  10   b  being secured into place within the facet joint  18 . 
         [0144]    Referring to  FIGS. 19 &amp; 20 , various features may be incorporated into the spacer  12  to support the full range of physiological movements and/or prevent tissue and/or bony ingrowth, for example including but not limited to an internal metal plate  50 , a low adhesion layer  52  (e.g. polyethylene suture thread), a densely-packed substrate layer  54  (e.g. tightly-woven nonsoluble microfibre polyester or dense embroidery), and/or an adhesive layer  56  (e.g. calcium hydroxyapatite). The spacer  12  may contain an internal metal plate  50  which serves to stiffen the spacer and doubles as a radio-opaque marker, which is advantageous when tracking the implant  10   b  post-surgery. The metal plate  50  may be placed on the joint bearing surface of the spacer  12  to help preserve motion within the facet joint by inhibiting tissue and/or bony ingrowth (if desired) due to the metallic properties. The effect of inhibiting tissue and/or bony ingrowth on the joint bearing surface is desirable and advantageous because it facilitates the free range of motion within the facet joint between the spacer and the articular process opposite fixation. More specifically, the spacer is not attached to both articular processes thereby leaving space between the implant and one articular facet for free movement within the facet joint. 
         [0145]    By way of example only in  FIG. 20 , a low adhesion layer  52  of polyethylene suture thread (or any other type of low adhesion material) may also be added to the joint bearing surface of the spacer opposite fixation. Another feature may consist of adding a densely-packed substrate layer  54  such as a tightly woven nonsoluble microfibre polyester (or any other densely-packed non-soluble substrate material such as a dense embroidery) to the joint bearing surface of the spacer opposite fixation. Both of these features, whether used alone or in combination, inhibit tissue and/or bony ingrowth on the joint bearing surface due to the low adhesion and/or density aspects of the material. This effect of inhibiting tissue and/or bony ingrowth on the joint bearing surface is desirable and advantageous because it facilitates the free range of motion within the facet joint between the spacer and the articular process opposite fixation. More specifically, the spacer is not attached to both articular processes thereby leaving space between the implant and one articular facet for free movement within the facet joint. 
         [0146]    Other features affecting the degree of tissue and/or bony ingrowth are possible. For example, the surface  51  of the outer textile layer may be treated with a material that completely inhibits tissue and/or bony ingrowth such that the articulation of the implant within the joint has a textile-on-bone interface. Alternatively, any combination of the above features may be employed to encourage slight tissue and/or bony ingrowth, for example only a surface coating of tissue that is not bonded to the opposite bone, such that the articulation of the implant within the joint has a tissue-on-bone interface. Furthermore, the above features may be employed to encourage a more extensive tissue and/or bony ingrowth of tissue that is attached to the opposite articular process such that a ligament-like interface is created, with movement achieved through deformation of the tissue rather than articulation of the implant against the bone. 
         [0147]    In addition to having tie cords  116 , other features may be added to the spacer  12  to help secure the implant  10  in situ. For example as shown in  FIG. 20 , an adhesive layer  56  (e.g. of calcium hydroxyapatite) may be added to the spacer  12  on the surface of fixation. This adhesive layer  56  of calcium hydroxyapatite (or any other type of adhesive and/or fusion-promoting material, for example such as bone morphogenic protein, demineralized bone matrix, stem cell material, Formagraft®, etc.) bonds the spacer  12  to the facet surfaces of the articular process of fixation by facilitating tissue and/or bony ingrowth through the surface of fixation on the spacer  12 . This effect of tissue and/or bony ingrowth on the surface of fixation is desirable and advantageous because it secures and encapsulates the implant  10  to the inside of the facet joint. 
         [0148]    While  FIG. 20  shows spacer  12  as including each of the features described above (i.e. metal plate  50 , low adhesion layer  52 , non-soluble substrate layer  54 , and adhesive layer  56 ), it will be appreciated that the spacer  12  may incorporate one or more or all of the features, and any combination thereof without departing from the scope of the invention. Although the implant  10   b  shown in  FIG. 20  has tie cords  116  as set forth in the third embodiment, it will be appreciated that the additional features described above can be applied to any of the embodiments described throughout this disclosure. 
         [0149]      FIGS. 21-23  collectively illustrate an example of a facet implant  10   c  according to a fourth embodiment of the present invention. In the example shown, the spacer  12  has a generally rectangular cross-section and a fixation aperture  201  extending therethrough positioned approximately in the center thereof. The spacer  12  further includes a radio-opaque plate  50  embedded therein and a guide funnel  200  extending through aperture  201 . Tie cords  116  are attached to a toggle element  202  are provided to secure the facet implant to the facet joint  18 . The guide funnel  200  is configured to facilitate insertion of toggle element  202  with attached tie cords  116  through fixation aperture  201  during the securing process. The toggle element  202  is configured to toggle between an axial configuration and a normal configuration, as will be described in detail below. The radio-opaque plate  50  is included to provide intra-operative and post-operative visibility to ensure proper positioning of the facet implant  10   c  within the facet joint  18 . 
         [0150]    In use, at least one bore  42  is drilled completely through the superior articular process  20  of the inferior vertebra  26 . The spacer  12  is inserted in the facet joint  18  with the guide funnel  200  of the spacer  12  lining up with the bore  42 . An insertion device  203  consisting of a generally cylindrical elongated hollow guide tube  204  and a generally rigid pusher wire  206  is provided to facilitate insertion of the toggle element  202  and tie cords  116  through aperture  201 . The toggle element  202  (with attached tie cords  116 ) is initially provided in an axial configuration (i.e. in axial alignment with the tie cords  116 ) such that the toggle element  202  may be advanced through the guide tube  204 , bore  42 , and ultimately aperture  201 . The pusher wire  206  is provided to facilitate such advancement of the toggle element  202 . 
         [0151]    Once passed through the bore  42  and guide funnel  200 , the pusher wire  204  deploys the toggle element  202  from the guide tube  204  to lock the spacer  12  into position within the facet joint  18 . As the toggle element  202  emerges from the aperture  201  on the opposite side of the facet implant  10   c  from bore  42 , the toggle element  202  will encounter the facet surface of the inferior articular process  22  of the superior vertebra  28 , which will cause the toggle element  202  to toggle into a generally normal configuration (i.e. in a generally normal alignment relative to the tie cords  116 ).  FIGS. 22 &amp; 23  show the toggle element  202  in the deployed and locked position. Finally, the tie cords  116 , which are attached to the toggle element  202 , are tensioned and secured externally on the outer surface of the superior articular process  20  of the inferior vertebra  26 . This may be achieved by various methods described throughout this disclosure, for example such as a button, suture, anchor, screw, crimp, or any other suitable fixation element. As a result, the toggle element  202  and tie cords  116  (affixed to the outer surface of the articular facet  20 ) hold the spacer  12  securely into place within the facet joint  18 . 
         [0152]      FIGS. 24-26  collectively illustrate an example of a facet implant  10   d  according to a fifth embodiment of the present invention. In the example shown, the implant  10   d  includes a spacer  12  having a generally rectangular cross-section and a radio-opaque plate  50  embedded therein. The radio-opaque plate  50  has a serrated stem (or stems)  340  extending generally orthogonally therefrom through the spacer  12 . A push-on locking cap  330  is provided to engage the stem  340  and secure the implant  10   d  in position within the facet joint  18 , as described below. By way of example only, the stem  340  may be made of metal or a polymer. Both the stem  340  and push-on locking cap  330  have serrations  344  that interact with one another to facilitate secure attachment of the implant  10   d  to the facet joint  18 . 
         [0153]    In use, a bore (or bores)  42  is drilled completely through the superior articular process  20  of the inferior vertebra  26 . The stem  340  is passed through the bore  42  from the facet surface of the superior articular process  20  to the outside surface of the articular process  20 . As a result of inserting the stem  340  through the bore  42 , and because the stem  340  is attached to the radio-opaque plate  50  embedded within the spacer  12 , the spacer  12  is inserted between the articular facets  21 ,  23  of the facet joint  18 . 
         [0154]    Once the spacer  12  and stem  340  have been inserted within the facet joint  18  as described above, the stem  340  will be protruding from the bore  42  on the outside surface of the superior articular process  20 . The push-on locking cap  330  is advanced over the stem  340  to engage the outer surface of the superior articular process  20 . Due to the serrations  344  on the inside of the push-on locking cap  330  and the serrations  344  on the outside of the stem  340 , the cap  330  can be pushed onto the stem  340  and locked into place on the outer surface of the superior articular process  20  of the inferior vertebra  26 . The manner of locking the push-on cap  330  onto the serrated stem  340  is similar to that used in a cable tie. This may be done with a tool, such as a metal sleeve. Any excess stem  340  may be trimmed to a desired length. In all instances, the serrated stem  340  and push-on locking cap  330  result in the implant  10   d  being secured into place within the facet joint  18 . 
         [0155]      FIGS. 27-29  collectively illustrate an example of a facet implant  10   e  according to a sixth embodiment of the present invention. In this example, the implant  10   e  includes a spacer  12  having a generally rectangular cross-section and a radio-opaque plate  50  embedded therein. The radio-opaque plate  50  has a threaded stem (or stems)  440  extending generally orthogonally therefrom through the spacer  12 . A screw-on locking cap  430  is provided to engage the threaded stem  440  and secure the implant  10   e  within the facet joint  10 , as described below. The screw-on locking cap  430  has an attached screw sleeve  432 . By way of example only, the stem  440 , screw-on locking cap  430 , and screw sleeve  432  may be made of metal or a polymer. 
         [0156]    In use, a bore (or bores)  42  is drilled completely through the superior articular process  20  of the inferior vertebra  26 . The bore  42  may be sized to fit the screw sleeve  432 , as shown in  FIG. 28 . The stem  440  is passed through the bore  42  from the facet surface of the superior articular process  20  to the outside surface of the articular process  20 . As a result of inserting the stem  440  through the bore  42 , and because the stem  440  is attached to the radio-opaque plate  50  embedded within the spacer  12 , the spacer  12  is inserted between the articular facets  21 ,  23  of the facet joint  18 . 
         [0157]    Once the spacer  12  and stem  440  have been inserted within the facet joint  18  as described above, the screw-on locking cap  430  is threadedly advanced onto the threaded stem  440  and fixed to the outer surface of the superior articular process  20  of the inferior vertebra  26 . Excess stem  440  may then be trimmed to length. As shown in  FIG. 30-32 , the base of the cap  430  may have barbs  444  to help facilitate engagement with the bone on the outer surface of the articular process  20 . The barbs  444  may be placed circumferentially in one direction, as shown in  FIG. 31 . This is advantageous because it helps ensure the barbs  444  grip to the bone surface. It will be appreciated that the feature of the barbs  444  are not limited to this sixth embodiment and may be included in the other embodiments described herein without departing from the scope of the present invention. In all instances, the threaded stem  440  and push-on locking cap  430  result in the implant  10  being secured into place within the facet joint  18 . 
         [0158]      FIGS. 33-35  collectively illustrate an example of a facet implant  10   f  according to a seventh embodiment of the present invention. In the example shown, the implant  10   f  includes a spacer  12  having a generally rectangular cross-section and a screw  530  configured to attach the implant  10   f  to an articular process. The spacer  12  includes a radio-opaque washer plate  50  embedded therein, a screw hole  532  extending therethrough, and cover flap  544 . The spacer  12  is inserted between the articular facets  21 ,  23  of the facet joint  18 . Once implanted, the spacer  12  is screwed directly into position in the facet joint  18 . The screw  530  passes through the screw hole  532  in the spacer  12  and is drilled into the inferior articular process  22  of the superior vertebra  28 , as shown in  FIG. 34 . The screw  530  is then tightened against the radio opaque washer plate  50  in the spacer  12 . 
         [0159]    Once the screw  530  secures the spacer  12  into place, the cover flap  544  is then folded to encapsulate the screw head  534 . The cover flap  544  provides additional padding and protection on the spacer  12  between the screw  530  and the inferior articular process  22  of the superior vertebra  28  so that there is no contact between the rigid surfaces of the screw and the bone. The cover flap  544  includes a screw hole filler  542  that fills in the gap from the screw head  534  to the height of the spacer  12 . The feature of a cover flap  544  is not limited to this embodiment only and may be included in the other embodiments of the implant  10  described herein without departing from the scope of the present invention. 
         [0160]    As previously described, the spacer  12  may also be attached to the superior articular process  20  of the inferior vertebra  26  without departing from the scope of the present invention. This may apply to any embodiment of the implant  10   f  described herein. It is understood that whether the spacer  12  is attached to the superior articular process  20  of the inferior vertebra  26  or if the spacer  12  is attached to the inferior articular process  22  of the superior vertebra  28 , the implant  10   f  will be situated in the facet joint  18  either way and will result in the repair/reconstruction of the degenerative joint. 
         [0161]      FIGS. 36-38  collectively illustrate an example of a facet implant  10   g  according to an eighth embodiment of the present invention. In the example shown, the implant  10   g  may include a screw  630  (or any other affixation element) and a spacer  12  with a screw hole  632 , reinforced fixation hole  636 , and mesh cover  644 . The spacer  12  has a generally rectangular cross-section and is inserted between the facet surfaces  21 ,  23  (on articular processes  20 ,  22 ) of the facet joint  18 . Once implanted, the spacer  12  is screwed directly into position in the facet joint  18 . The screw  630  passes through the mesh cover  644  and screw hole  632  in the spacer  12 . The screw  630  is drilled into the superior articular process  20  of the inferior vertebra  26 . The screw  630  is then tightened against the reinforced fixation hole  636  in the spacer  12  and the implant  10   g  is secured in the facet joint  18 . 
         [0162]    The reinforced fixation hole  636  in the spacer  12  is designed to provide reinforcement in the spacer  12  to ensure that the screw does not tear through the spacer. The mesh cover  644  in the spacer  12  is designed to allow the entire screw  630  and screw head  634  to pass through and close over it. The mesh cover  644  then encapsulates the screw head  634 , as shown in  FIG. 37 . Although the reinforced fixation hole  636  and mesh cover  644  are described in this particular embodiment, it will be appreciated that these features are not limited to this embodiment and can be applied to any other embodiment described herein without departing from the scope of the present invention. 
         [0163]    As previously described, the spacer  12  may be formed of a textile/fabric material. By way of example only,  FIG. 39  illustrates a base textile structure  650  used to form the spacer  12 . The base textile structure  650  is preferably manufactured via an embroidery process using any number of biocompatible filament materials (including but not limited to polyester thread). Base textile structure  650  is comprised of a plurality of hinged embroidered layer regions  644 ,  652 - 658 . The mesh cover layer  644 , which is an outer layer region of the base textile structure  650 , is loosely constructed to allow an entire screw and screw head to pass through it. Layer regions  652 - 658  have screw holes  632  to facilitate the screw fixation of the spacer  12  into the bone. Furthermore, the base layer  658  contains the reinforced fixation hole  636 , which is densely embroidered to provide reinforcement in the spacer  12  so that the screw does not tear through the spacer. 
         [0164]    The layer regions  644 ,  652 - 658  of the base textile structure  650  are connected together in side-by-side relation and separated by a distance to form a plurality of hinge regions  660   a - 660   d  between the layer regions  644 ,  652 - 658 , respectively. Then the base textile structure  650  is then folded to form the spacer  12 . The layer regions  644 ,  652 - 658  are folded at the hinge regions  660   a - 660   d  such that layer regions  644 ,  652 - 658  are stacked together. The folding process may be performed in any number of manners as long as the mesh cover layer  644  is placed on one outside surface of the spacer  12  and the base layer  658  is placed on the other outside surface of the spacer  12  after being stacked together. It will be appreciated that the number of layer regions  644 ,  652 - 658  shown in  FIG. 39  is set forth by way of example only and that the number may be increased or decreased without departing from the scope of the present invention. This may be done for any number of different purposes, including but not limited to varying the thickness of the spacer  12 . 
         [0165]      FIGS. 40 &amp; 41  illustrate an example of an inserter assembly  70  used for inserting an implant  10  into a facet joint according to one embodiment of the present invention. The inserter assembly  70  is designed to releasably maintain the implant  10  in the proper orientation for insertion. The implant  10  may be introduced into a facet joint while engaged with the inserter  70  and thereafter released. Preferably, the inserter  70  includes a distal engagement region  72  and an elongated handling member  74 . The inserter  70  may be composed of any material suitable for inserting an implant  10  into a facet joint, including but not limited to metal (e.g. titanium), ceramic, and/or polymer compositions. According to this particular embodiment, the distal engagement region  72  is comprised of an insertion plate  76 . The insertion plate  76  is generally planar rectangular in shape, but may take the form of any geometric shape necessary to interact with the implant  10 , including but not limited to generally oval, square, and triangular. The handling member  74  is generally cylindrical in shape. The handling member  74  allows a clinician to manipulate the tool during an implant insertion procedure. 
         [0166]    In order to facilitate engagement with the inserter  70 , the spacer  12  of the implant  10  includes a pocket  78 . By way of example only, the pocket  78  is formed from an extra layer of embroidered fabric attached to three of the four sides of the spacer  12 , leaving an opening  80  for insertion of the insertion plate  76 . The insertion plate  76  engages with the implant  10  by sliding into the pocket  78 . Although slideable engagement is described herein, any suitable means of engagement may be used to engage the insertion plate  76  with the implant  10 , including but not limited to a threaded engagement, snapped engagement, hooks, and/or compressive force. Once the insertion plate  76  is fit into place within the pocket  78  of the implant  10 , the inserter  70  releasably maintains the implant  10  in the proper orientation for insertion. The implant  10  may then be introduced into a facet joint while engaged with the inserter  70  and thereafter released. The implant  10 , having been deposited in the facet joint  18 , facilitates improved spinal functionality over time by maintaining a restored foraminal space (due to the structural and load-bearing capabilities of the implant  10 ) as well as enabling a desired range of motion (e.g. physiologic motion, current motion, improved motion, reduced motion, restricted motion, zero motion and/or no restriction to motion). 
         [0167]      FIGS. 42 &amp; 43  illustrate an example of an inserter assembly  70   a  used for inserting an implant  10  into a facet joint according to an alternate embodiment of the present invention. The inserter  70   a  may include a distal engagement region  72   a  and an elongated handling member  74   a,  however in this embodiment, the distal engagement region  72   a  is comprised of, by way of example only, two insertion prongs  86 . Preferably, the insertion prongs  86  are generally cylindrical in shape, but may take the form of any geometric shape necessary to interact with the implant  10 . In order to facilitate the insertion prongs  86 , the spacer  12  of the implant  10  may have attached side pockets  88 . By way of example only, the side pockets  88  may be made of embroidered fabric attached to each side of the spacer  12  with openings  90  for insertion of the insertion prongs  86 . 
         [0168]    The insertion prongs  86  engage with the implant  10  by sliding into the side pockets  88 . Although slideable engagement is described herein, any suitable means of engagement may be used to engage the insertion prongs  86  with the implant  10 , including but not limited to a threaded engagement, snapped engagement, hooks, and/or compressive force. Once the insertion prongs  86  are inside the side pockets  88  of the implant  10 , the inserter  70   a  releasably maintains the implant  10  in the proper orientation for insertion. The implant  10  may then be introduced into a facet joint while engaged with the inserter  70   a  and thereafter released. It will be appreciated that the number of insertion prongs  86  is set forth by way of example only and may be increased or decreased without departing from the scope of the present invention. In all instances, the implant  10 , having been deposited in the facet joint  18 , facilitates improved spinal functionality over time by maintaining a restored foraminal space (due to the structural and load-bearing capabilities of the implant  10 ) as well as enabling a desired range of motion (e.g. physiologic motion, current motion, improved motion, reduced motion, restricted motion, zero motion and/or no restriction to motion). 
         [0169]    It will be appreciated that although in  FIGS. 40-43  the inserter assemblies  70 ,  70   a  is shown in use with the implant  10  having an encapsulating jacket and attachment flanges (as described above in the first embodiment for the implant  10 ), the inserter assemblies  70 ,  70   a  and added pockets  78 ,  88  may be used with any embodiment of the implant  10  described herein without departing from the scope of the invention. Furthermore, the inserters  70 ,  70   a  of the present invention is not limited to interaction with the implant  10  disclosed herein, but rather may be dimensioned to engage any surgical implant. 
         [0170]      FIGS. 44-51  illustrate an example of a facet implant  10   h  according to a ninth embodiment of the present invention. In the example shown, implant  10   h  includes a spacer  12  having an attachment flange  40  extending from approximately the middle of the spacer  12 , and a pin element  810  configured to secure the implant  10   h  in position as described below. The attachment flange  40  includes a plurality of apertures  32  through which the pin element  810  may be inserted to fix the implant in place. 
         [0171]    Insertion of the implant  10   h  is achieved through placement of the spacer  12  between the superior and inferior articular facets  21 ,  23  of the facet joint  18  and passing the central attachment flange  40  through a bore  42  formed through the superior articular process  20 . Once inserted through the bore  42 , the attachment flange  40  is pulled to apply the required tension to establish preferential seating of the spacer  12 . Finally, a pin element  810  is inserted and affixed within the aperture  32  residing closest to the superior articular process  20 . Properly inserted, the pin element  810  acts in conjunction with the spacer  12  to maintain a desired degree of tension on the attachment flange  40 , preventing movement of the flange  40  and thereby preserving the positioning of the spacer  12  within the facet joint  18 . After insertion of the pin element  810 , the clinician may choose to remove any extraneous portion of the attachment flange  40  distal to the pin element  810 . For example, this may be accomplished by cutting the attachment flange  40  at any number of positions including but not limited to L 1 , L 2 , L 3  ( FIG. 46 ). Although presently described as inserted through the superior articular process  20  of the inferior vertebra, implantation of the implant  10   h  can be alternatively achieved via insertion of the attachment flange  40  through the inferior articular process  22  of the superior vertebra. 
         [0172]    By way of example only, the attachment flange  40  extends generally orthogonally from the surface of the spacer  12 . Although not shown in the attached Figures, the flange  40  may be attached to a radio-opaque plate or marker provided within the spacer  12  as described in relation to several embodiments above, and thus the flange  40  would then protrude out of the surface of the spacer  12 . Alternatively, the flange  40  may be an integral extension of an encapsulating jacket provided around the spacer  12 . The attachment flange  40  may be composed of any material suitable to sustain pin element  810  and spacer  12  orientations including but not limited to metal, textiles, wire, plastics, synthetic fibers and the like of any degree of flexibility. In a preferred embodiment, the attachment flange  40  comprises an embroidered textile material provided with load-bearing reinforced apertures  32  that are resistant to tearing under stress. Furthermore it can be appreciated that the attachment flange  40  may comprise any suitable dimension to afford insertion into the bore  42  while providing a sufficiently sized substrate capable of supporting an array of apertures  32  from which the clinician can choose to customize the implantation as required by the targeted insertion tissues. 
         [0173]    The apertures  32  are distributed generally linearly along the attachment flange  40  and are dimensioned to receive the pin element  810 . It can be appreciated that any number of apertures  32  may be disposed in any pattern within the attachment flange  40  which might align with preferential receiving tissue. Furthermore, the apertures  32  may be either reinforced or not reinforced dependent upon the likely compositional interactions between the pin element  810  and attachment flange  40 . 
         [0174]    The pin element  810  may comprise any configuration and composition suitable to sustain pin element  810  positioning within the aperture  32  while also sustaining proper spacer  12  positioning within the facet joint  18 . Examples of suitable configurations of pin element  810  include but are not limited to crimps, textile or wire ties, male/female coupler elements, snaps, screws and the like which might be detachably or permanently inserted into the aperture  32 . Furthermore it can be appreciated that the pin element  810  may be composed of any suitable material capable of preserving preferential implant  10  positioning within the facet joint  18  including but not limited to metal, plastic, textiles, synthetic fibers and the like. 
         [0175]    Moreover, while pin element  810  shown in  FIGS. 44-46  is a single piece, generally rigid construct, other configurations of pin elements are possible. For example,  FIGS. 47-48  disclose an example of a bendable pin element  812 , and  FIGS. 49-51  illustrate an example of a multi-piece pin element  818 . Referring first to  FIGS. 47-48 , pin element  812  is shown in use with a facet implant  10   h  as described above. Pin element  812  is generally elongated and may have any cross-sectional shape, including but not limited to circular, ovoid, square, rectangular, triangular, etc. Pin element  812  includes a pair of end portions  814   a,    814   b  separated by a bendable central portion  816 . The pin element  812  is initially provided in an unbended, linear configuration as shown in  FIG. 48 . After spacer  12  of implant  10   h  has been inserted into the facet joint as described above, pin element  812  is inserted through an aperture  32  provided within attachment flange  40 . When the central portion  816  is aligned with the opening of the aperture  32 , the central portion  816  is bent such that the end portions  814   a,    814   b  are no longer in a linear relationship to one another. Central portion  814  may be bent to any degree desirable. The bending of the pin element  812  helps ensure that the pin element  812  remains in place within aperture  32  and consequently that adequate tension is maintained on flange  40  to keep spacer  12  in position within the facet joint. 
         [0176]    Referring to  FIGS. 49-51 , an example of an alternative pin element  818  is described. In this example, pin element  818  comprises a first pin element  820  and a second pin element  822 . Pin elements  820 ,  822  are generally elongated, generally rigid, and may have any cross-sectional shape, including but not limited to circular, ovoid, square, rectangular, triangular, etc. First pin element  822  includes a post  824  projecting axially from one end. Second pin element  824  includes a recess  826  formed within one end, the recess  826  being of a shape complementary to that of the post  824 , and further dimensioned to securely receive the post  824  in order to create a locked relationship relative to one another. Such a locked relationship may be accomplished through a threaded interaction, friction fit, and/or adhesive material. Upon mating of the first and second pin elements  820 ,  822 , a portion of the post  824  remains exposed ( FIG. 51 ) to account for the thickness of the attachment flange  40 . In use, the pin element  818  is initially provided as separate first and second pin elements  820 ,  822 . After spacer  12  of implant  10   h  has been inserted into the facet joint as described above, post  824  of first pin element  820  is inserted through an aperture  32  provided within attachment flange  40 . Recess  826  of pin element  822  is then aligned with and advanced over post  824  until the first and second pin elements  820 ,  822  are suitably locked together. The result is a generally rigid pin element  818  functioning similarly to pin element  810  described above. One benefit to a multi-piece pin element  818  as described is that the apertures  32  need only be large enough to permit passage of post  824  therethrough, thus potentially increasing the load-bearing capacity of the flange  40 , or conversely reducing the amount of material necessary for flange  40  construction. 
         [0177]      FIGS. 52-60  illustrate an example of a facet implant  10   i  according to a tenth embodiment of the present invention. Facet implant  10   i  comprises an anchoring element  854  and a spacer  12 , as previously presented herein, including an attached fixation bracket  850  and anchorage member  852 . The fixation bracket  850  is attached to the spacer  12  and configured to extend around an extent of the superior articular process  20  to at least fractionally engage the outer surface of the superior articular process  20 . Additionally the fixation bracket  850  includes at least one aperture  851  dimensioned to receive the anchorage member  852  therethrough. Proper insertion of the implant  10   i  is achieved through insertion of the spacer  12  within the facet joint  18 , and passing the anchorage member  852  through a bore  42  which extends through the superior articular process  20 . Implantation is completed by positioning the fixation bracket  850  over an extent of the superior articular process  20  such that the relevant aperture  851  is in general alignment with bore  42 , passing the anchorage member  852  through the aperture  851 , applying the desired tension to the anchorage member  852 , and finally affixing an anchoring element  854  to the anchorage member  852  at some point proximate to the fixation bracket  850 . Preferably, the anchoring element  854  is cinched into a snug interaction with the fixation bracket  850 . Subsequent to attaching the anchorage element  854 , the anchorage member  852  may be trimmed at any point distal to the anchorage element  854 , as indicated in  FIG. 54 . Although presently described as inserted through the superior articular process  20  of the inferior vertebra, it can be appreciated that implantation of the implant  10  can be alternatively achieved via insertion of the anchorage member  852  through the inferior articular process  22  of the superior vertebra. 
         [0178]    The fixation bracket  850  is dimensioned to extend around an extent of and engage the outer surface of the superior articular process  20 . The fixation bracket  850  may comprise one or more apertures  851  disposed in any number of configurations sufficient to provide a clinician the opportunity to preferentially orient the fixation bracket  850  with the inserted anchorage member  852 . Therefore it can be appreciated that the fixation bracket  850  of the present invention may comprise any suitable dimension which will afford optimal engagement of the superior articular process  20  while also providing a sufficiently sized substrate capable of supporting one or more apertures  851 . Moreover the fixation bracket  850  may comprise any suitable material of sufficient strength and flexibility with which to support spacer  12  and anchorage member  852  positioning including but not limited to pliable or inflexible metal, textile, plastic, synthetic materials and the like. In a preferred embodiment, the fixation bracket  850  comprises an embroidered textile material provided with load-bearing reinforced apertures  851  that are resistant to tearing under stress. 
         [0179]    The anchorage member  852  of the present embodiment comprises a generally pliable shaft extending from the surface of the spacer  12  and dimensioned to pass through apertures  42  and  851  and the anchoring element  854 . Although described as generally pliable, the anchorage member  852  may be composed of material exhibiting any degree of flexibility while being of suitable strength to hold the implant  10  in place including but not limited to pliable or inflexible metal, textile, plastic, synthetic fibers (e.g. woven or embroidered) and the like. Furthermore the anchorage member  852  may be of any suitable length which provides clinicians with the ability to customize insertion and positioning of the implant  10  as directed by the structure of the receiving tissues. Additionally the anchorage member  852  may constitute any dimension and/or surface structures including but not limited to textures and/or treatments, to provide for optimal anchoring element  854  engagement with the anchorage member  852 . 
         [0180]      FIGS. 55-58  illustrate one example of an anchoring element  854 . Anchoring element  854  includes a textured lumen  860  into which the anchorage member  852  is introduced. Lumen  860  has a cross-sectional shape generally corresponding to the shape of the anchorage member  852 . Texture  866  on the interior of lumen  860  may comprise (for example) a plurality of ridges, threads, protrusions, etc. Once anchorage member  852  is introduced through lumen  860 , it is secured via compression of outer anchoring element surfaces  868 ,  869 , as shown in  FIG. 57 . Generally optimal implant placement is achieved by tensioning the anchorage element  852  to create preferential engagement of the spacer  12  with the superior articular facet  21  ( FIG. 53 ), and then affixing the anchoring element  854  to the anchorage member  852  and against the surface of the fixation bracket  850 , thereby securing the position of spacer  12  within the facet joint  18 . Anchoring element  854  may further include a plurality of engagement features  862  on the leading end, dimensioned to engage the fixation bracket  850  to ensure minimal relative movement between anchoring element  854  and fixation bracket  850 . 
         [0181]      FIGS. 58-60  illustrate an example of an alternative anchoring element  854   a.  Anchoring element  854   a  has the same features of anchoring element  854  except that it includes a break  870  in the side to enable the anchorage member  852  to pass through and enter the lumen  860 . As with anchoring element  854 , anchoring element  854   a  includes texture  866  on the interior of lumen  860 , which may comprise (for example) a plurality of ridges, threads, protrusions, etc. Once anchorage member  852  is introduced through lumen  860 , it is secured via compression of outer anchoring element surfaces  868 ,  869 , as shown in  FIG. 60 . Although not shown, anchoring element  854   a  may include a plurality of engagement features on the leading end, dimensioned to engage the fixation bracket  850  to ensure minimal relative movement between anchoring element  854  and fixation bracket  850 . 
         [0182]    Although illustrated as having a crimp-like configuration, the anchoring element  854  may comprise any number of suitable configurations including but not limited to detachably or permanently applied screws, ratcheting rivet assemblies and other suitable devices for engaging the anchorage member  852  while restricting anchoring member  854  movement. Furthermore, the anchoring element  854  may be composed of any suitable material capable of engaging and sustaining anchorage member  852  positioning therein including but not limited to metal, textile, plastic, synthetic fibers and the like. 
         [0183]      FIGS. 61-65  illustrate an example of a facet implant  10   j  according to an eleventh embodiment of the present invention. Facet implant  10   j  includes a spacer  12  which may or may not include an encapsulating jacket as described above. Preferably, spacer  12  may be of textile construction (e.g. embroidered or woven), however other materials such as those described above are possible. Facet implant  10   j  is has a generally rectangular cross-section and is dimensioned to be inserted within a facet joint  18  between a superior articular process  20  of a first vertebra and an inferior articular process  22  of a second vertebra. Spacer  12  is secured in place using a tie cord  900  and fixation screw  902 . As illustrated in  FIG. 62 , screw  902  includes head  904  and a threaded shaft  906 . Head  904  includes a shaped engagement element  908  dimensioned to engage an insertion device (not shown) and an aperture  910  dimensioned to allow passage of the tie cord  900  therethrough. An alternative example of a screw  902   a  is provided in  FIG. 63 . Screw  902   a  is similar to screw  902 , except that the head  904  includes a shaped recess  908   a  dimensioned to receive an insertion device (not shown), such as a screw driver. 
         [0184]    As illustrated by way of example only in  FIG. 64 , spacer  12  is generally rectangular in shape and has a pair of apertures  912  and a recess  914 . Apertures  912  extend completely through the spacer  12  and are dimensioned to receive the tie cords  900  therethrough. The recess  914  is positioned in the middle of the spacer  12  and is dimensioned to at least partially receive the head  904  of the screw  902  upon implantation in the facet joint  18 . 
         [0185]    In use, tie cords  900  function not only to secure the facet implant  10   j  within the facet joint  18 , but also to deliver the implant  10   j  to the facet joint. To accomplish this, a bore  916  is first formed through the facet surface  21  of the superior articular process  20  of the inferior vertebra. The tie cord is threaded through aperture  910  of screw  902 , and the screw  902  is then threadedly inserted into the bore  916 . The screw  902  is dimensioned such that the shaped engagement element  908  remains outside the bore  916  when the screw  902  has been fully seated. Once screw  902  has been seated within the superior articular process  20 , the tie cords  900  are passed through apertures  912  of implant  10   j.  The implant  10   j  is then advanced along the tie cords  900  into the facet joint  18 . When the implant  10   j  has been fully inserted within the facet joint  18 , the shaped engagement element  908  of the screw  902  is nestled within the recess  914  of the spacer  12 . Once the implant  10   j  has been preferentially seated within the facet joint  18 , the tie cords  900  may be tied to secure the implant  10   j  in place, and excess tie cord  900  may then be severed and removed.  FIG. 65  illustrates the implant  10   j  after implantation within the facet joint  18 . 
         [0186]      FIGS. 66-70  illustrate an example of a facet implant  10   k  according to a twelfth embodiment of the present invention. Implant  10   k  is similar to implant  10  of  FIG. 1 , and includes a spacer  12  and encapsulating jacket  14 . In the example shown in  FIG. 66 , the jacket  14  includes a body portion  15  that at least partially surrounds the spacer  12 . The attachment flanges  16  extend from one end of the body portion  15  such that upon insertion within a facet joint, the flanges  16  will all extend outside the joint in a similar manner. The body portion  15  includes an additional pad  950  that includes a fusion-inducing biologic agent, such as bone morphogenic protein (BMP), stem cell based material, calcium hydroxyapatite, demineralized bone matrix, or Formagraft® offered by NuVasive. Pad  950  including the biologic agent may be provided on either side or both sides of body portion  15 . 
         [0187]    As shown in  FIGS. 67-68 , the implant  10   k  is inserted into the facet joint  18  such that the pads  950  are in contact with articular processes  20 ,  22  forming the facet joint  18 . Providing the pad  950  on both sides, as shown by example in  FIGS. 66-70 , encourages fusion of the implant with the facet joint. The degree of fusion that occurs may be controlled depending on the needs of the user, as described in relation to several of the examples presented above. As shown in  FIG. 69 , fusion may be achieved at least with the encapsulating jacket  14  such that any facet motion that occurs is within the implant  10   k.    
         [0188]      FIGS. 71-77  illustrate an example of a spacer  960  that provides for internal movement within a facet implant such as any of the examples discussed above. The spacer  960  may be provided with or without an encapsulating jacket. The spacer  960  is similar to those shown and described in the above-referenced &#39;944 PCT Application. The spacer  960  is comprised of a plurality of textile layers, for example six layers  962   a - 962   f  coupled by a plurality of hinge regions  964 . Spacer  960  is provided by example as assembling in an accordion-like manner, however other assemblies are possible. For example, the spacer  960  may be formed from a plurality of individual textile layers consecutively stacked upon one another and/or a single continuous textile sheet folded upon itself to form a plurality of stacked textile layer regions. As shown in  FIG. 72 , upon assembling the spacer  960  will comprise a pair of “outside” textile layers  962   a,    962   f  separated by a number of “interior” textile layers  962   b - 962   e.  As shown in  FIG. 73 , a supplemental stitching  966  may provided through the various textile layers  962   a - 962   f  to tether the layers together and increase stability of the implant. 
         [0189]    Textile layers  962   a - 962   f  may be provided in any number and configuration without departing from the scope of the present invention. In the present example, interior textile layers  962   b - 962   e  may be untreated or in the alternative treated with an anti-fusion agent in order to prevent any tissue and/or bony ingrowth through those layers. Furthermore, the layers  962   b - 962   e  may be chemically treated or manufactured such that they are capable of moving relative to one another. The outside textile layers  962   a,    962   f  are formed from or treated with fusion-inducing materials to cause tissue and/or bony ingrowth between the bone and the specific outside textile layers  962   a,    962   f.  The result is a facet implant  101  including a layered spacer  960  that achieves a textile-bone fusion interface with the facet surface of the superior articular process  20  of a first vertebra and a textile-bone fusion interface with the facet surface of the inferior articular process  22  of a second vertebra. However, facet motion is retained due to the capability of the interior layers  962   b - 962   e  to move or slide relative to one another in response to movement of the articular processes  20 ,  22 . For example,  FIGS. 74-75  show the motion of the spine ( FIG. 74 ) and corresponding movement of the spacer  960  ( FIG. 75 ) during spinal flexion.  FIGS. 76-77  show the motion of the spine ( FIG. 76 ) and corresponding movement of the spacer  960  ( FIG. 77 ) during spinal extension. In either case, the spacer  960  allows for a “controlled slippage” of the interior textile layers  962   b - 962   e  such that at least partial motion within the facet joint may be preserved. Movement of the layers  962   b - 962   e  is controlled due to the hinge regions  964  and supplemental stitching  966  as well as an encapsulating jacket  14  (if provided), all of which function to limit the range of motion of the textile layer regions  962   b - 962   e.    
         [0190]    Many of the facet implant examples described above encourage at least some tissue and/or bony ingrowth in order to either secure the implant in place or promote complete fusion of the facet joint. Upon successful tissue and/or bony ingrowth, biodegradation, bioresorbtion, bioabsorbtion, bioabsorption, and/or bioerosion of the implant or portions thereof may be encouraged depending upon the desired motion preservation characteristics of the facet joint. For the purposes of this disclosure, bioresorbtion is meant to include any biological process (including those delineated above) in which at least a portion of the fabric component of the implant disappears or becomes detached from the rest of the implant. 
         [0191]      FIGS. 78-81  illustrate an example of a facet implant  10   m  according to a fourteenth embodiment of the present invention. Implant  10   m  is similar to implant  10  of  FIG. 1 , and includes a spacer  12  and encapsulating jacket  14 . In the example shown in  FIG. 78 , the jacket  14  includes a body portion  15  that at least partially surrounds the spacer  12 . The attachment flanges  16  extend from one end of the body portion  15  such that upon insertion within a facet joint, the flanges  16  will all extend outside the joint in a similar manner. The encapsulating fabric  14  of the implant  10   m  includes a portion (e.g. a strip) of bioresorbable fabric  970  on each flange  16  adjacent to the body portion  15 . As such, over time the bioresorbable fabric  970  will disappear, causing the body portion  15  and flanges  16  to become detached from one another. The flanges  16  may be secured to the relevant bone portions using any suitable means of attachment, for example including but not limited to bone screws, staples, sutures, nails, buttons, anchors, and/or adhesives. 
         [0192]      FIG. 79  illustrates the implant  10   m  including bioresorbable portions  970  inserted between a superior articular process  20  and inferior articular process  22  of adjacent vertebrae before the flanges  16  have been attached to the bone.  FIG. 80  illustrates the implant  10   m  after the flanges  16  have been secured to bone with sutures  34 .  FIG. 81  illustrates the implant  10   m  in position after resorbtion of the bioresorbable fabric portions  970  has occurred. The spacer  12  is thus detached from the flanges  16  and left within the facet joint. 
         [0193]      FIGS. 82-83  illustrate an example of a facet implant  10   n  according to a fifteenth embodiment of the present invention. Implant  10   n  is similar to implant  10  of  FIG. 1 , and includes a spacer  12  and encapsulating jacket  14 . In the example shown in  FIG. 82 , the jacket  14  includes a body portion  15  that at least partially surrounds the spacer  12 . The attachment flanges  16  extend from one end of the body portion  15  such that upon insertion within a facet joint, the flanges  16  will all extend outside the joint in a similar manner. In this example, the portions of the encapsulating fabric  14  forming the flanges  16  are entirely bioresorbable, and after resorbtion only the spacer  12  is left within the facet joint ( FIG. 83 ). 
         [0194]    Regarding the methods of using all examples of facet implants disclosed herein, it will be understood that several method steps are inherent to performing surgery, and thus have been omitted from each description of use above. However, these steps may be integral in the use of the devices disclosed herein, including but not limited to creating an incision in a patient&#39;s skin, distracting and retracting tissue to establish an operative corridor to the surgical target site, advancing the implant through the operative corridor to the surgical target site, removing instrumentation from the operative corridor upon insertion of the implant into the target facet joint, and closing the surgical wound. 
         [0195]    Although described with respect to specific examples of the different embodiments, any features of the facet implants disclosed herein by way of example only may be applied to any of the embodiments without departing from the scope of the present invention. Furthermore, procedures described for example only involving specific structure (e.g. superior articular process) may be applied to another structure (e.g. inferior articular process) without departing from the scope of the present invention. 
         [0196]    While this invention has been described in terms of a best mode for achieving this invention&#39;s objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the invention.