Abstract:
Spinal implants have cooperating suture anchors. The devices include: (a) a spinal implant; and (b) at least one suture anchor comprising a threaded bone anchor holding at least one suture extending outwardly therefrom. In position, the at least one suture extends outward from the threaded bone anchor and attaches to the spinal implant while the threaded anchor is anchored in a vertebral body.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. Provisional Application Ser. No. 60/765,984, filed Feb. 7, 2006, the content of which is hereby incorporated herein by reference as if recited in full herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to spinal implants.  
       BACKGROUND OF THE INVENTION  
       [0003]     The vertebrate spine is made of bony structures called vertebral bodies that are separated by relatively soft tissue structures called intervertebral discs. The intervertebral disc is commonly referred to as a spinal disc. The spinal disc primarily serves as a mechanical cushion between the vertebral bones, permitting controlled motions between vertebral segments of the axial skeleton. The disc acts as a joint and allows physiologic degrees of flexion, extension, lateral bending, and axial rotation. The disc must have sufficient flexibility to allow these motions and have sufficient mechanical properties to resist the external forces and torsional moments caused by the vertebral bones.  
         [0004]     The normal disc is a mixed avascular structure having two vertebral end plates (“end plates”), an annulus fibrosis (“annulus”) and a nucleus pulposus (“nucleus”). Typically, about 30-50% of the cross sectional area of the disc corresponds to the nucleus. Generally described, the end plates are composed of thin cartilage overlying a thin layer of hard, cortical bone that attaches to the spongy cancellous bone of the vertebral body. The end plates act to attach adjacent vertebrae to the disc.  
         [0005]     The annulus of the disc is a relatively tough, outer fibrous ring. For certain discs, particularly for discs at lower lumbar levels, the annulus can be about 10 to 15 millimeters in height and about 10 to 15 millimeters in thickness, recognizing that cervical discs are smaller.  
         [0006]     Inside the annulus is a gel-like nucleus with high water content. The nucleus acts as a liquid to equalize pressures within the annulus, transmitting the compressive force on the disc into tensile force on the fibers of the annulus. Together, the annulus and nucleus support the spine by flexing with forces produced by the adjacent vertebral bodies during bending, lifting, etc.  
         [0007]     The compressive load on the disc changes with posture. When the human body is supine, the compressive load on the third lumbar disc can be, for example, about 200 Newtons (N), which can rise rather dramatically (for example, to about 800 N) when an upright stance is assumed. The noted load values may vary in different medical references, typically by about ±100 to 200 N. The compressive load may increase, yet again, for example, to about 1200 N, when the body is bent forward by only 20 degrees.  
         [0008]     The spinal disc may be displaced or damaged due to trauma or a degenerative process. A disc herniation occurs when the annulus fibers are weakened or torn and the inner material of the nucleus becomes permanently bulged, distended, or extruded out of its normal, internal annular confines. The mass of a herniated or “slipped” nucleus tissue can compress a spinal nerve, resulting in leg pain, loss of muscle strength and control, and even paralysis. Alternatively, with discal degeneration, the nucleus loses its water binding ability and deflates with subsequent loss in disc height. Subsequently, the volume of the nucleus decreases, causing the annulus to buckle in areas where the laminated plies are loosely bonded. As these overlapping plies of the annulus buckle and separate, either circumferential or radial annular tears may occur, potentially resulting in persistent and disabling back pain. Adjacent, ancillary facet joints will also be forced into an overriding position, which may cause additional back pain. The most frequent site of occurrence of a herniated disc is in the lower lumbar region. The cervical spinal disks are also commonly affected.  
         [0009]     There are several types of treatment currently being used for treating herniated or degenerated discs: conservative care, discectomy, nucleus replacement, fusion and prosthesis total disc replacement (TDR). It is believed that many patients with lower back pain will get better with conservative treatment of bed rest. For others, more aggressive treatments may be desirable.  
         [0010]     Discectomy can provide good short-term results. However, a discectomy is typically not desirable from a long-term biomechanical point of view. Whenever the disc is herniated or removed by surgery, the disc space will narrow and may lose much of its normal stability. The disc height loss may cause osteo-arthritis changes in the facet joints and/or compression of nerve roots over time. The normal flexibility of the joint is lost, creating higher stresses in adjacent discs. At times, it may be necessary to restore normal disc height after the damaged disc has collapsed.  
         [0011]     Fusion is a treatment by which two vertebral bodies are fixed to each other by a scaffold. The scaffold may be a rigid piece of metal, often including screws and plates, or allo or auto grafts. Current treatment is to maintain disc space by placement of rigid metal devices and bone chips that fuse two vertebral bodies. The devices are similar to mending plates with screws to fix one vertebral body to another one. Alternatively, hollow metal cylinders filled with bone chips can be placed in the intervertebral space to fuse the vertebral bodies together (e.g., LT-Cage™ from Sofamor-Danek or Lumbar I/F CAGE™ from DePuy). These devices have disadvantages to the patient in that the bones are fused into a rigid mass with limited, if any, flexible motion or shock absorption that would normally occur with a natural spinal disc. Fusion may generally eliminate symptoms of pain and stabilize the joint. However, because the fused segment is fixed, the range of motion and forces on the adjoining vertebral discs can be increased, possibly enhancing their degenerative processes.  
         [0012]     Some recent TDR devices have attempted to allow for motion between the vertebral bodies through articulating implants that allow some relative slippage between parts (e.g., ProDisc®, Charite™). See, e.g., U.S. Pat. Nos. 5,314,477, 4,759,766, 5,401,269 and 5,556,431. As an alternative to the metallic-plate, multi-component TDR (total disc replacement) designs, a flexible solid elastomeric spinal disc implant that is configured to simulate natural disc action (i.e., can provide shock absorption and elastic tensile and compressive deformation) is described in U.S. Patent Application Publication No. 2005/0055099 to Ku, the contents of which are hereby incorporated by reference as if recited in full herein.  
         [0013]     Other parts of the spine may also deteriorate and/or need repair and implants for various portions of the spine may be desirable.  
       SUMMARY OF EMBODIMENTS OF THE INVENTION  
       [0014]     Embodiments of the present invention are directed to anchoring spinal implants in bone using suture anchors.  
         [0015]     Some embodiments are directed to spinal implants with cooperating suture anchors. The devices include a spinal implant and at least one suture anchor comprising a threaded bone anchor holding at least one suture. In position, the at least one suture extends outwardly from the threaded bone anchor and attaches to the spinal implant while the threaded bone anchor is anchored in a vertebral body.  
         [0016]     Other embodiments are directed to medical spinal implant kits. The kits include; (a) a total disc replacement (TDR) spinal implant comprising a bone attachment material; and (b) a plurality of suture anchors configured to define suture knots against an outer surface of the bone attachment material with the threaded anchors configured and sized to reside in at least one vertebral body above or below the TDR implant to secure the TDR implant in position.  
         [0017]     Still other embodiments are directed to methods of attaching a total disc replacement (TDR) implant to at least one vertebral body. The methods include: (a) implanting a TDR; (b) anchoring at least one bone anchor in at least one vertebral body proximate the TDR; and (c) tying at least one suture set attached to the bone anchor to the TDR to thereby secure the TDR in position in the body.  
         [0018]     Some embodiments are directed to TDR implants. The implants include: (a) a flexible implant body; and (b) a bone attachment member with at least one outwardly extending plug configured and sized to reside in a cavity formed in a vertebral body.  
         [0019]     The TDR implant may optionally include at least one threaded bone anchor with at least one suture set attached to the bone attachment member. A single anchor can be sized and configured to reside in the vertebral cavity with a respective plug.  
         [0020]     Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the embodiments that follow, such description being merely illustrative of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is an anterior view of an implantable spinal disc prosthesis with cooperating suture anchors according to embodiments of the present invention,  
         [0022]      FIG. 2A  is an anterior view of another implantable spinal disc prosthesis with cooperating suture anchors according to embodiments of the present invention.  
         [0023]      FIG. 2B  is an anterior view of another implantable spinal disc prosthesis with cooperating suture anchors according to embodiments of the present invention.  
         [0024]      FIG. 3  is an anterior view of a vertebral body with exemplary locations for suture anchors according to embodiments of the present invention.  
         [0025]      FIGS. 4A and 4B  are lateral views of a portion of a suture anchor held in vertebral bone according to embodiments of the present invention.  
         [0026]      FIG. 5  is a side view of an exemplary suture anchor with a plurality of suture sets according to some embodiments of the present invention.  
         [0027]      FIG. 6  is an exploded anterior view of a suture anchor with two suture sets and an implant according to embodiments of the present invention.  
         [0028]      FIG. 7A-7E  are sequential views of implantation steps that can be used to anchor a spinal implant according to embodiments of the present invention.  FIGS. 7A-7C  and  7 E are lateral views and  FIG. 7D  is an anterior exploded view.  
         [0029]      FIG. 8  is an anterior view of implantable spinal discs using several exemplary different suture anchor configurations according to embodiments of the present invention.  
         [0030]      FIG. 9  is a schematic illustration of a medical kit according to embodiments of the present invention.  
         [0031]      FIG. 10A  is a lateral view of a bone attachment material comprising a plug configuration according to embodiments of the present invention.  
         [0032]      FIG. 10B  is a side perspective view of an exemplary bone cavity plug according to embodiments of the invention.  
         [0033]      FIG. 11A  is a lateral view of a spinal implant with bone attachment material comprising plugs or inserts according to embodiments of the present invention.  
         [0034]      FIG. 11B  is an anterior view of the device shown in  FIG. 11A .  
         [0035]      FIG. 12  is a side perspective view of a spinal implant with keels according to some embodiments of the present invention.  
         [0036]      FIG. 13A  is a side view of a portion of the spine illustrating an implant on a spinous process with a cooperating suture anchor according to embodiments of the present invention.  
         [0037]      FIG. 13B  is a side view of an exemplary spinous process cuff suitable for use with cooperating suture anchors according to some embodiments of the present invention.  
         [0038]      FIG. 14  is a side view of a spine illustrating a wide range facet prosthesis secured using a cooperating suture anchor according to some embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0039]     The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.  
         [0040]     Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise.  
         [0041]     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.” 
         [0042]     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.  
         [0043]     It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.  
         [0044]     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. The sequence of operations (or steps) is not limited to the order presented in the claims or figures unless specifically indicated otherwise.  
         [0045]     The terms “spinal disc implant” and “spinal disc prosthesis” are used interchangeably herein to designate total disc replacements using an implantable total disc replacement (TDR) prosthesis (rather than a nucleus only) and as such are configured to replace the natural spinal disc of a mammalian subject (for veterinary or medical (human) applications). In contrast, the term “spinal implant” refers to both TDR spinal disc implants and alternative spinal implants, such as, for example, a spinal annulus implant, a spinal nucleus implant, a facet implant, and a spinous process implant as well as implants for other portions of the spine.  
         [0046]     The term “keel” means an implant component, feature or member that is configured to be received in a recess or mortise in an adjacent bone to facilitate short and/or long-term fixation and/or to provide twist or torsion resistance in situ.  
         [0047]     The term “flexible” means that the member can be flexed or bent. In some embodiments, the implant can include a keel, which may be flexible but has sufficient rigidity to be substantially self-supporting so as to be able to substantially maintain a desired configuration outside of the body. If flexible, the keel can include reinforcement to increase its rigidity.  
         [0048]     The term “mesh” means any flexible material in any form including, for example, knotted, braided, extruded, stamped, knitted, woven or otherwise, and may include a material with a substantially regular foramination pattern and/or irregular foramination patterns.  
         [0049]     The term “macropores” refers to apertures having at least about a 1 mm diameter or width size, typically a diameter or width that is between about 1 mm to about 3 mm, and more typically a diameter or width that is between about 1 mm to about 1.5 mm (the width dimension referring to non-circular apertures). Where mesh keels are used, the macropores are larger than the openings or foramina of the mesh substrate. The macropores may promote bony through-growth for increased fixation and/or stabilization over time.  
         [0050]     The term “loop” refers to a shape in the affected material that has a closed or nearly closed turn or figure. For example, the loop can have its uppermost portion merge into two contacting lower portions or into two proximately spaced apart lower portions. The term “fold” means to bend and the bend of the fold may have a sharp or rounded edge. The terms “pleat” or “fold” refer to doubling material on itself (with or without sharp edges). The term “attachment point” and derivatives thereof refers to a common attachment location and is not meant to restrict the attachment to a geometric point.  
         [0051]     Referring now to the figures,  FIG. 1  illustrates an example of a spinal implant  10  with cooperating suture anchors  20 . The suture anchors  20  include at least one suture  22  that is attached to a bone anchor  20   b  ( FIGS. 4A, 4B ). Typically, the suture  22  is provided as a suture set  22   s , in which each leg of the set is tied together such as using a knot  22   t  to secure the spinal implant  10  in location. The knot  22   t  can reside proximate to and/or against the outer surface of the implant  10 . It is also noted that in lieu of, or with, the knot  22   t , the ends of the sutures  22  may be attached to the implant  10  via other attachment means. For example, the two end portions of the suture  22  can be separately or jointly adhesively attached to the implant  10  such with an adhesive, heat-melt process, staple, clip or other anchor member.  
         [0052]     The implant  10  can include a bone attachment member or material  11  that receives the suture  22 . As shown, the bone attachment material  11  can reside above and below the primary body of the implant  10 . However, the bone attachment material  11  may be configured to reside only above, only below, or to be substantially coextensive with the primary implant body (not shown). Each suture set  22   s  can be closed so that the respective knot  22   t  resides against or proximate an exterior surface of the bone attachment material  11 , above or below the primary body of the implant  10 . In some embodiments a unitary layer of bone attachment material can form a skirt that defines both an upper and lower bone attachment material  11 . The bone attachment material  11  can comprise any biocompatible material suitable to provide the attachment and/or stabilization. The bone attachment material  11  may comprise a flexible substrate. In some embodiments, the bone attachment material  11  comprises a mesh substrate. The mesh can be metallic, fabric, polymeric or comprise combinations of materials.  
         [0053]     The bone attachment material  11  can include one or more relatively small preformed apertures (not shown) at the respective target indicia markings  122  that can be sized and configured to receive the needle  23  and suture  22 . The preformed apertures may be molded in or introduced at a manufacturing site to reduce clinician preparation time. Alternatively, the substrate can be configured to allow the needle to be inserted through the substrate in the target attachment regions in situ without using preformed apertures.  
         [0054]     The bone attachment material  11  is typically between about 0.25 mm to about 20 mm thick, and is more typically between about 0.5 mm to about 5 mm thick. In some embodiments, the mesh comprises a DACRON mesh of about 0.7 mm thick available as Fablok Mills Mesh #9464 from Fablok Mills, Inc., located in Murray Hill, N.J. The mesh may comprise cryogel material to increase rigidity.  
         [0055]      FIG. 1  illustrates that the implant  10  is secured using a plurality of suture anchors  20 , some above and some below the implant  10 . Although shown as four suture anchors  20 , additional or lesser numbers of the suture anchors  20  may be used. Further, although the suture anchors  20  are shown as being substantially aligned (side to side and vertically) in proximate vertebral bone and in the bone attachment material  11 , the suture anchors  20  may be arranged asymmetrically. In addition, bone screws or other devices may be used with one or more of the suture anchors  20  (not shown). The implant  10  can be attached to bone  25  using the cooperating suture anchors  20  in a manner that allows substantially normal, or at least not unduly restrictive, spinal movement.  
         [0056]      FIG. 2A  illustrates that the bone attachment material  11  can be configured with discrete tabs lit spaced apart laterally; each tab lit can engage at least one suture set  22   s .  FIG. 2A  also illustrates that the bone anchor  20   b  can reside under (behind) the bone attachment material  11 , rather than above or below as shown in  FIG. 1 .  FIG. 2B  illustrates that the upper bone attachment material  11  may be configured differently from the lower bone attachment material.  FIG. 2B  also illustrates that the bone anchor  20   b  ( FIG. 4A ) may reside above the bone attachment material  11  while the lower bone anchors  20   b  ( FIG. 4A ) may reside substantially behind the bone attachment material  11 . The mounting configuration can also be reversed with the lower bone screws  20   b  below the material  11  and the upper bone anchor  20   b  behind the material  11 .  
         [0057]      FIG. 3  illustrates a vertebral bone  25  with a mortise or keel recess  26  formed therein. The mortise or recess  26  can be formed into the vertebral bone  25  to accept fins or keels of implants (shown for example as feature  50  in  FIG. 12 ).  FIG. 3  illustrates exemplary bore locations  120   a ,  120   b  that can be used and/or formed by bone anchors  20   b  relative to the mortise  26 . An implant  10  may employ bone anchors  20   b  at one or more of the bore locations. The bore locations  120   a  typically reside behind the bone attachment material  11  (shown in broken line) while the bore locations  120   b  typically reside above (or below) the material  11 .  
         [0058]      FIG. 4A  illustrates a threaded bone anchor  20   b  with an attached suture set  22   s  in position in a vertebral body  25 . As shown, a suture  22  is held by a head portion  20   h  of the bone anchor  20   b . The head  20   h  can be recessed into or be substantially flush with the natural boundary of the vertebral bone  25 . For recessed configurations, bone chips or other void filling (bone growth) material  325  ( FIG. 9 ) may be inserted in the cavity between the material  11  and the bone anchor head  20   h . The material  325  can be provided as part of a medical kit  500  ( FIG. 9 ). Typically, the head  20   h  includes an aperture  21  and a length of suture  22  is threaded through the aperture  21  to form a suture set  22   s  with a pair of legs  22 L. The opposing end portions of the suture legs  22 L (the end portion away from the head  21 ) can include/merge into a needle  23  ( FIG. 6 ). In use, after inserting the needle  23  through the bone attachment material  11 , the corresponding suture leg  22 L can be pulled through the material  11  and the suture set  22   s  can be tied or stitched together proximate an outside surface of the material  11 .  
         [0059]      FIG. 4B  illustrates that the bone anchor  20   b  can be inserted through the cortical layer such that at least a tip portion thereof resides in cancellous bone. It is contemplated that the bone anchor  20   b  may have improved pullout strength if the threads of the bone anchor  20   b  bear on cortical bone. As shown, the bone anchor  20   b  can angularly reside in the bone  25  (rather than be substantially horizontal as shown in  FIG. 4A ). Combinations of these and other orientations may also be used.  
         [0060]      FIG. 5  illustrates that the bone anchor  20   b  may be configured to hold a plurality of suture sets  22   1 ,  22   2 ,  22   3 . Although shown as holding three, one or more of the bone anchors  20   b  may hold lesser or greater numbers of suture sets  22   s . Each suture set  22   1 ,  22   2 ,  22   3  may be formed so that the respective sutures legs  22 L have a different color or pattern for matching to allow easier alignment and/or attachment in situ. A template  300  ( FIG. 9 ) may also be provided to help a clinician mark locations on vertebral bodies for the bone anchor  20   b  to help provide proper seating and alignment. The bone attachment material  11  may also include needle insertion indicia  122  ( FIG. 9 ) to provide visual references that a clinician can use to attach the suture  22  to the implant  10 . The indicia  122  may also be color coded to the suture for that location.  
         [0061]     Also, although not shown, the bone anchor  20   b  may include a single suture leg rather than a suture set  22   s . A first end portion can be integrally attached to the head of the bone anchor  20   h  with the other end portion including the needle  23 . To attach to the bone attachment material  11 , the single suture leg can be tied to another single leg or suture set or a discrete anchor member can be attached after the needle  23  is pulled through the material  11 , or the single leg can be adhesively attached, stapled and/or clipped to the outer surface of the bone attachment material  11  (not shown).  
         [0062]     The bone anchor  20   b  can be self-tapping and/or self-drilling. The bone anchor  20   b  may be implanted into a prior formed bore. The threads of the bone anchor  20   b  can be adapted to the porosity of the vertebral cancellous bone (which may be less dense than in other regions). The bone anchor  20   b  may have a largest diameter of between about 3-10 mm, typically between about 5-8 mm. The bone anchor  20   b  may have a length between about 8-30 mm, typically between about 10-20 mm.  
         [0063]      FIG. 9  illustrates an alternate configuration of a bone anchor  20   b . In this embodiment, the suture attachment region (aperture)  21  is recessed into the head  20   h  so that the threads extend substantially the entire length of the bone anchor body  20   b . The threads can bear on the cortical layer of the vertebral body while still being substantially flush or slightly recessed with the outer layer of the vertebral body. This configuration may increase pull-out strength.  
         [0064]      FIG. 6  illustrates that a first suture set  22   1  may be provided in a different length than a second suture set  22   2 . Also, although shown as being attached to different corner portions of the bone material, the two suture sets  22   1 ,  22   2  may be attached adjacent each other in a common corner (side by side or one above the other) or one can be attached at a corner and the other at a medial portion. Other configurations may also be used.  
         [0065]     The suture  22  and/or the bone anchor  20   b  may comprise a resorbable or non-resorbable biocompatible material.  
         [0066]     As shown in  FIG. 6 , the needle  23  may be swaged, threaded or otherwise attached to the suture  22 . The needle  23  may be straight or curved. As shown, the needle  23  is curved and may also include a substantially blunt tip  23   b . Where a mesh is used to form the material  11 , the blunt tip  23   b  may inhibit damage to mesh or other sensitive or susceptible fibers when suturing mesh material  11  to the bone. The suture legs  22 L can have lengths between about 5-20 cm with the needles  23  on one end and the aperture or loop  21  of the head  20   h  at the other. The needle  23  is typically removed from the suture leg  22 L after pulling the suture leg through the bone attachment material  11 , and the suture leg  22 L can be tied or otherwise secured to the material  11  and the surplus lengths thereof can be removed (cut).  
         [0067]      FIGS. 7A-7E  illustrate a sequence of steps that can be used to attach a spinal implant to cooperating suture anchors  20  in situ. As shown in  FIG. 7A , the primary implant body  10   b  can be positioned in an intervertebral space. The bone attachment material  11  can be pulled, pushed or folded back as shown in  FIG. 7B . Then, as shown in  FIG. 7C , the bone anchor  20   b  can be introduced into the target vertebral bone  25  proximate the implant  10 . The bone can be “pre-drilled”, then the bone anchor inserted, or the bone anchor can be inserted without requiring pre-drilling. In other embodiments, the bone anchor(s)  20   b  can be introduced before the implant  10  and/or material  11 . In still other embodiments, the bone attachment material  11  can be attached to the implant after the implant is in the body and/or after the bone anchor(s) is in position. As shown in  FIG. 7D , in an exploded view for clarity, a suture set  22   s  can be pulled through the material  11 . That is, the needles  23  can be inserted from one side of the material (i.e., flexible skirt) from the posterior (inner) to the anterior (outer) side. The suture set  22   s  can be pulled substantially taut and tied together to form a knot  22   t  against the outer surface of the material  11  while the bone anchor  20   b  remains in the vertebral bone  25  to tighten the material  11  against the vertebral body  25 . The incision can then be closed with the knot  22   t  inside the incision (not pulled through the skin).  
         [0068]      FIG. 8  illustrates three different exemplary mounting configurations for a suture anchor  20  that may be used to attach to spinal implants  10 . As shown, two TDR implants  10  are in position in respective intevertebral spaces. The upper implant  10   1  includes a single level multi-attachment point suture anchor  20   sm . The lower portion of the upper implant  10   1  and the upper portion of the lower implant  10   2  illustrate a double level multi-attachment point suture anchor  10   dm . That is, sutures  22  from respective bone anchors  20   b  extend to different levels (above and below the bone anchors  20   b ). The lower level of the second implant  10   2  illustrates a single level, single attachment point suture anchor  20   ss.    
         [0069]      FIG. 9  illustrates a medical kit  500  that can provide the suture anchors  20 . The kit  500  can include at least one implant  10  and a plurality of suture anchors  20 . The kit  500  can also include the void filler  325  and at least one surgical template  300 . The template  300  can include indicia for the bone anchor entry location  301  and may optionally include needle indicia  322  that can align with indicia on an interior surface of the bone attachment material  11  proximate the indicia  122  that can be placed on the outside surface of the material  11  (for indicating a target needle exit location). The template  300  may be configured so that each target bone anchor  20   b  location  301  is color-coded to bone anchors  20   b  and/or suture sets  22   s  and a location on material  11 . A similar or different template  300  can be provided for attachment to a lower location or an upper location, or a combination template can be provided with both sets of alignment/target location indicia (not shown).  
         [0070]      FIG. 10A  illustrates that the bone anchor  20   b  can reside in a cavity  25   c .  FIGS. 10A, 11A  and  11 B illustrate that the attachment material  11  can include at least one plug  111  that is sized and shaped to enter the cavity  25   c  and reside between the bone anchor  20   b  and the outer perimeter of the bone and/or outer surface of material  11 . The plug  111  can be attached to the attachment material  11  or be a separate component.  FIG. 10B  illustrates one exemplary shape of the plug  111 . The plug  111  can comprise a metal, polymer or other suitable material. In some embodiments, the plug  111  is a mesh plug. The mesh plug  111  may comprise polyester fibers, such as DACRON and/or a polyvinylalcohol (PVA) cryogel. As shown in  FIGS. 10A, 10B  and  11 A, the plug  111  can include macropores  111   p . The plug  111  is typically a single one plug that has through holes  111   p  for bone to grow into. The bone growing in those through holes  111   p  can provide a solid long-term fixation of the plug  111  to the bone. The plug  111  can be integrally attached to the material  111  and/or the implant body  10 . In some embodiments, the plug  111  is integrally attached to the skirt or tab material  11  and each may comprise a mesh fabric that is molded to the implant body  10   b .  FIG. 11A  illustrates that the plug  111  faces into the bone and  FIG. 11B  illustrates the plug  111  can extend inward from a rear primary surface of the external attachment member (e.g., skirt or tab and the like).  FIG. 10A  illustrates that the bone anchor resides furthermost in the bone cavity with the plug(s)  111  residing between the external bone attachment member and the bone anchor  20   b.    
         [0071]     Referring to  FIG. 12 , in some embodiments, the shape of the implant  10  can be described as a three-dimensional structure that provides a desired anatomical shape, shock absorbency and mechanical support. In some embodiments, the anatomical shape can have an irregular solid volume to fill a target intervertebral disc space. The coordinates of the body can be described using the anatomic directions of superior (toward the head), inferior (toward the feet), lateral (away from the midline), medial (toward the midline), posterior (toward the back), and anterior (toward the front). From a superior view, the implanted device has a kidney shape with the hilum toward the posterior direction. The margins of the device in sagittal section are generally contained within the vertebral column dimensions. The term “primary surface” refers to one of the superior or inferior surfaces.  
         [0072]      FIG. 12  illustrates one embodiment of spinal disc implant  10 . The implant  10  can include at least one keel  50  on at least one primary surface. As shown, the implant  10  includes at least one flexible keel  50 . In this embodiment, the flexible keel  15  is an anterior/posterior keel. In the embodiment shown in  FIG. 12 , the implant  10  includes both upper and lower keels  50  on respective superior and inferior primary surfaces. In other embodiments, the keel  50  can be oriented to extend substantially laterally. The keel  50  can be defined by a fold in a unitary layer of flexible material.  
         [0073]     The size of the prosthetic spinal disc  10  can vary for different individuals. A typical size of an adult lumbar disc is 3-5 cm in the minor axis, 5 cm in the major axis, and 1.5 cm in thickness, but each of these dimensions can vary. It is contemplated that the implant  10  can be provided in a range of predetermined sizes to allow a clinician to choose an appropriate size for the patient. That is, the implant  10  can be provided in at least two different sizes with substantially the same shape. In some embodiments, the implant  10  can be provided in small, medium and large sizes. Further, the sizes can be configured according to the implant position—i.e., an L3-L4 implant may have a different size from an L4-L5 implant. In some embodiments, an implant  10  can be customized (sized) for each respective patient.  
         [0074]     The implant  10  can be configured as a flexible elastomeric MRI and CT compatible implant of a shape generally similar to that of a spinal intervertebral disc. The implant  10  can have a solid elastomeric body with mechanical compressive and/or tensile elasticity that is typically less than about 100 MPa (and typically greater than 1 MPa), with an ultimate strength in tension generally greater than about 100 kPa, that can exhibit the flexibility to allow at least 2 degrees of rotation between the top and bottom faces with torsions greater than 0.01 N-m without failing. The implant  10  can be configured to withstand a compressive load greater than about 1 MPa.  
         [0075]     The implant  10  can be made from any suitable elastomer capable of providing the desired shape, elasticity, biocompatibility, and strength parameters. The implant  10  can be configured with a single, uniform average durometer material and/or may have non-linear elasticity (i.e., it is not constant). The implant  10  may optionally be configured with a plurality of durometers, such as a dual durometer implant. The implant  10  can be configured to be stiffer in the middle, or stiffer on the outside perimeter. In some embodiments, the implant  10  can be configured to have a continuous stiffness change, instead of two distinct durometers. A lower durometer corresponds to a lower stiffness than the higher durometer area. For example, one region may have a compressive modulus that is between about 11-100 MPa, while the other region may have a compressive modulus that is between 1-10 MPa.  
         [0076]     The implant  10  can have a tangent modulus of elasticity that is about 1-10 MPa, typically about 3-5 MPa, and a water content of between about 30-60%, typically about 50%.  
         [0077]     Some embodiments of the implantable spinal disc  10  can comprise polyurethane, silicone, hydrogels, collagens, hyalurons, proteins and other synthetic polymers that are configured to have a desired range of elastomeric mechanical properties, such as a suitable compressive elastic stiffness and/or elastic modulus. Polymers such as silicone and polyurethane are generally known to have (compressive strength) elastic modulus values of less than 100 MPa. Hydrogels and collagens can also be made with compressive elasticity values less than 20 MPa and greater than 1.0 MPa. Silicone, polyurethane and some cryogels typically have an ultimate tensile strength greater than about 100 or 200 kiloPascals. Materials of this type can typically withstand torsions greater than 0.01 N-m without failing.  
         [0078]     As shown in  FIG. 12 , the spinal disc body  10  may have a circumferential surface  11 , a superior surface  12 , and an inferior surface  13 . The superior and inferior surfaces  11 ,  12  may be substantially convex to mate with concave vertebral bones. One or more of the surfaces may also be substantially planar or concave. The circumferential surface  11  of spinal disc body  10  corresponds to the annulus fibrosis (“annulus”) of the natural disc and can be described as the annulus surface  11 . The superior surface  12  and the inferior surface  13  of spinal disc body  10  correspond to vertebral end plates (“end plates”) in the natural disc. The medial interior of spinal disc body  10  corresponds to the nucleus pulposus (“nucleus”) of the natural disc.  
         [0079]     The implant  10  can include a porous covering, typically a mesh material layer,  12   c ,  13   c  on each of the superior and inferior primary surfaces  12 ,  13 , respectively. As shown, the implant  10  can also include a porous, typically mesh, material layer  14   c  on the annulus surface  14 . The annulus cover layer  14   c  can be formed as a continuous or seamed ring to inhibit lateral expansion. In other embodiments, the annulus cover layer  14   c  can be discontinuous. As also shown, the three coverings  12   c ,  13   c ,  14   c  can meet at respective edges thereof to encase the implant body  10 . In other embodiments, the coverings  12   c ,  13   c ,  14   c  may not meet or may cover only a portion of their respective surfaces  12 , 13 ,  14 .  
         [0080]      FIG. 12  illustrates that the annulus cover  14   c , the superior cover  12   c , and or the inferior cover  13   c  can be oversized to extend beyond the bounds of the implant body  10   b  above or below an anterior portion of the implant body  10   b  to define the attachment material  11  that can cooperate with bone anchors  20   b  and sutures  22 . The material  11  can extend above or below the body  10   b  with a height between about 2-35 mm, typically 5-15 mm.  
         [0081]     The implant  10  may be configured to allow vertical passive expansion or growth of between about 1-40% in situ as the implant  10  absorbs or intakes liquid due to the presence of body fluids. The passive growth can be measured outside the body by placing an implant in saline at room temperature and pressure for 5-7 days, while held in a simulated spinal column in an intervertebrate space between two simulated vertebrates. It is noted that the passive expansion can vary depending, for example, on the type of covering or mesh employed and the implant material. For example, in some embodiments, the mesh coverings  14   c ,  12   c ,  13   c  along with a weight percentage of (PVA) used to form the implant body are configured to have between about 1-5% expansion in situ.  
         [0082]     In addition, in some embodiments, the mesh may comprise a biocompatible coating or additional material on an outer and/or inner surface that can increase the stiffness. The stiffening coating or material can include PVA cryogel. The annulus cover  14 C (also described as a “skirt”) can be a continuous skirt that defines the bone attachment material  11  and may include stiffening or reinforcement means.  
         [0083]     Some embodiments of the spinal disc implant  10  are configured so that they can mechanically function as a substantially normal (natural) spinal disc and can attach to endplates of the adjacent vertebral bodies. As shown in  FIG. 12 , the spinal disc body  10   b  is generally of kidney shape when observed from the superior, or top, view, having an extended oval surface and an indented portion. The anterior portion of spinal disc  10  can have greater height than the posterior portion  10   p  of spinal disc  10  in the sagittal plane. The implant  10  can be configured with a mechanical compressive modulus of elasticity of about 1.0 MPa, ultimate stretch of greater than 15%, and ultimate strength of about 5 MPa. The device can support over 1200 N of force. Further description of an exemplary flexible implant is described in co-pending U.S. Patent Application Publication No. 20050055099, the contents of which are hereby incorporated by reference as if recited in full herein.  
         [0084]     Elastomers useful in the practice of the invention include silicone rubber, polyurethane, polyvinyl alcohol (PVA) hydrogels, polyvinyl pyrrolidone, poly HEMA, HYPAN™ and Salubria® biomaterial. Methods for preparation of these polymers and copolymers are well known to the art. Examples of known processes for fabricating elastomeric cryogel material is described in U.S. Pat. Nos. 5,981,826 and 6,231,605, the contents of which are hereby incorporated by reference. See also, Peppas, Poly(vinyl alcohol)hydrogels prepared by freezing-thawing cyclic processing. Polymer, v. 33, pp. 3932-3936 (1992); Shauna R. Stauffer and Nikolaos A. Peppas.  
         [0085]     In some embodiments, the implant body  10  is a substantially solid PVA hydrogel having a unitary body shaped to correspond to a natural spinal disc. An exemplary hydrogel suitable for forming a spinal implant is (highly) hydrolyzed crystalline poly(vinyl alcohol) (PVA). PVA cryogels may be prepared from commercially available PVA material, typically comprising powder, crystals or pellets, by any suitable methods known to those of skill in the art. Other materials may also be used, depending, for example, on the application and desired functionality. Additional reinforcing materials or coverings, radiopaque markers, calcium salt or other materials or components can be molded on and/or into the molded body. Alternatively, the implant can consist essentially of only the molded PVA body.  
         [0086]     In some embodiments, the attachment material  11  is integrally attached to a moldable implant material via a molding process. The moldable primary implant material can be placed in a mold. The moldable material comprises an irrigant and/or solvent and about 20 to 70% (by weight) PVA powder crystals. The PVA powder crystals can have a MW of between about 124,000 to about 165,000, with about a 99.3-100% hydrolysis. The irrigant or solvent can be a solution of about 0.9% sodium chloride. The PVA crystals can be placed in the mold before the irrigant (no pre-mixing is required). The mold has the desired 3-D implant body shape. A lid can be used to close the mold. The closed mold can be evacuated or otherwise processed to remove air bubbles from the interior cavity. For example, the irrigant can be overfilled such that, when the lid is placed on (clamped or secured to) the mold, the excess liquid is forced out thereby removing air bubbles. In other embodiments, a vacuum can be in fluid communication with the mold cavity to lower the pressure in the chamber and remove the air bubbles. The PVA crystals and irrigant can be mixed once in the mold before and/or after the lid is closed. Alternatively, the mixing can occur naturally without active mechanical action during the heating process.  
         [0087]     Typically, the mold with the moldable material is heated to a temperature of between about 80° C. to about 200° C. for a time sufficient to form a solid molded body. The temperature of the mold can be measured on an external surface. The mold can be heated to at least about 80-200° C. for at least about 5 minutes and less than about 8 hours, typically between about 10 minutes to about 4 hours. The (average or max and min) temperature can be measured in several external mold locations. The mold can also be placed in an oven and held in the oven for a desired time at a temperature sufficient to bring the mold and the moldable material to suitable temperatures. In some embodiments, the mold(s) can be held in an oven at about 100-200° C. for about 2-6 hours; the higher range may be used when several molds are placed therein, but different times and temperatures may be used depending on the heat source, such as the oven, the oven temperature, the configuration of the mold, and the number of items being heated.  
         [0088]     The liners  14   c ,  12   c ,  13   c  can be placed in the mold to integrally attach to the molded implant body during the molding process. In some embodiments, osteoconductive material, such as, for example, calcium salt can be placed on the inner or outer surfaces of the covering layers  14   c ,  12   c ,  13   c , and/or the inner mold surfaces (wall, ceiling, floor) to coat and/or impregnate the mesh material to provide osteoconductive, tissue-growth promoting coatings.  
         [0089]     After heating, the implant body can be cooled passively or actively and/or frozen and thawed a plurality of times until a solid crystalline implant is formed with the desired mechanical properties. The molded implant body can be removed from the mold prior to the freezing and thawing or the freezing and thawing can be carried out with the implant in the mold. Alternatively, some of the freeze and thaw steps (such as, but not limited to, between about 0-10 cycles) can be carried out while the implant is in the mold, then others (such as, but not limited to, between about 5-20 cycles) can be carried out with the implant out of the mold.  
         [0090]     Before, during and/or after freezing and thawing (but typically after demolding), the molded implant can be placed in water or saline (or both or, in some embodiments, neither). The device can be partially or completely dehydrated for implantation. The resulting prosthesis can have an elastic modulus of at least about 2 MPa and a mechanical ultimate strength in tension and compression of at least 1 MPa, preferably about 10 MPa, and under about 100 MPa. The prosthesis may allow for between about 1-10 degrees of rotation between the top and bottom faces with torsions of at least about 1 N-m without failing. The implant can be a single solid elastomeric material that is biocompatible by cytotoxicity and sensitivity testing specified by ISO (ISO 10993-5 1999: Biological evaluation of medical devices—Part 5: Tests for in vitro cytotoxicity and ISO 10993-10 2002: Biological Evaluation of medical devices—Part 10: Tests for irritation and delayed-type hypersensitivity).  
         [0091]     The testing parameters used to evaluate the compressive tangential modulus of a material specimen can include:  
         [0092]     Test type: unconfined compression  
         [0093]     Fixtures: flat platens, at least 30 mm diameter  
         [0094]     Rate: 25.4 mm/sec to 40% strain  
         [0095]     Temperature: room temp (˜22° C.)  
         [0096]     Bath: samples stored in saline or water until immediately before test  
         [0097]     Samples: cylinders, 9.8±0.1 mm height, 9.05±0.03 mm diameter  
         [0098]     Compressive Tangential Modulus calculated at 15, 20, and 35% strain  
         [0099]     Embodiments of the instant invention employ anchors  20  to attach any suitable prosthesis and the present invention is not limited to spinal implants. In some embodiments, the suture anchors can be used to attach or affix implants comprising PVA cryogel material. The PVA cryogel implants can be manufactured to be mechanically strong, or to possess various levels of strength among other physical properties with a high water content, which provides desirable properties in numerous applications. For example, the cryogel tissue replacement construct is especially useful in surgical and other medical applications as an artificial material for replacing and reconstructing soft tissues or as orthopedic implants in humans and other mammals.  
         [0100]      FIGS. 13A and 13B  illustrate that suture anchors  20  can be used to secure other implants in the body. As shown in  FIG. 13A , a spinous process sleeve or cuff implant  210  is in position on the spinous process  35  in the body. The suture anchor  20  is attached to the implant  210 . That is, the bone anchor  20   b  resides in the spinous process  35  while the suture set  22   s is tied  22   t to the implant  210 .  FIG. 13B  illustrates that attachment extensions  211  (such as tabs or a skirt) can be used to secure the sutures  22 . The extensions  211  can include the needle indicia  122 .  FIG. 13A  illustrates that the sutures  22  may be attached directly to the cuff body. The cuff body may include reinforced regions (i.e., PVA cryogel with polymeric mesh fabric, laminated layers of mesh fabric and the like) with increased rigidity or strength that inhibits tearing that define the attachment zones.  
         [0101]      FIG. 14  illustrates a synthetic wide range facet implant  310  secured in position in the spine using a cooperating suture anchor  20 . The implant  310  is configured as a “spinal facet joint” or joint surface. This term refers to the location at which vertebral bodies meet at a rear portion of the spine. The shape of facet joints change along the length of the spine. The facet joint includes bone, cartilage, synovial tissue, and menisci. The implant  310  can be an elastic body that is configured to substantially conformably reside on an outer surface of the bone in a manner that allows a relatively wide range of motion between the bones forming the joint. Also, as shown in  FIG. 14 , the suture knots can be recessed within the implant  310  device (such as in a small cylindrical recess or well for example) so that the knots are inhibited from rubbing against the opposite articulating surface of the facet joint.  
         [0102]     The implants  310  and  210  can be substantially “conformal” so as to have sufficient flexibility to substantially conform to a target structure&#39;s shape. The facet implant or prosthesis can be applied to one surface (one side) of the facet joint (the bone is resurfaced by the implant) or to both surfaces of the joint, and/or may reside therebetween as a spacer to compress in response to loads introduced by the cooperating bones at the facet joint and still allow motion therebetween. The implant may be an elastic body that is configured to conformably reside on an outer surface of the bone in a manner that allows a relatively wide range of motion between the bones forming the joint. A facet implant or prosthesis can be applied to one surface (one side) of the facet joint (the bone is resurfaced by the implant) or to both surfaces of the joint, and/or may reside therebetween as a spacer to compress in response to loads introduced by the cooperating bones at the facet joint and still allow motion therebetween.  
         [0103]     The spinal facet joint implant  310  can be configured to provide “wide range motion”; this phrase refers to the substantially natural motion of the bones in the facet joint which typically include all ranges of motion (torsion, lateral and vertical). The term “wide range motion” refers to substantially natural motion of the bones in the facet joint, which typically include the three motions associated with a functional spine unit, flexion/extension, lateral bending, and axial rotation. The motions translate differently in the disc compared to the facets but these motions are a good reference as far as range of motion. A facet joint sees sliding motions (along the joint surface) as well as compression and tension (in which case the facets are not in contact and the load is taken by the ligament only (capsular ligament)). The term “compact” means that the device is small with a low profile and suitable for surgical introduction into the spine. The term “thin” means that the device has a thickness that is less than about 6 mm, typically between about 0.001-3 mm, and may be between about 0.01 mm to about 0.5 mm. The term “conformal” means that the implant material or member is sufficiently flexible to conform to a target structure&#39;s shape. The target structure&#39;s shape can be either the upper portion of the lower bone or the lower portion of the upper bone (one of the two vertebral bones) that meet at the rear of the spine or both.  
         [0104]     The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.