Patent Publication Number: US-2007118130-A1

Title: Implant fixation methods and apparatus

Description:
BACKGROUND OF THE INVENTION  
      Disease, advancing age, and trauma can lead to changes in various bones, discs, joints, and ligaments of the body. Some changes and trauma often manifest themselves in the form of damage or degeneration to a spinal disc. This condition often results in chronic back pain, which can be anywhere from mild to severe. This pain can sometimes be eliminated by removing the disc tissue between adjacent vertebral bodies and replacing it with a prosthetic device.  
      One type of procedure is spinal fusion, in which two adjacent vertebral bodies are jointed together after removing the intervening intervertebral disc. A prosthetic device is usually placed between the two adjacent vertebral bodies, in place of the removed disc, to fill the space left by the removed disc and to allow bone to grow between the two vertebral bodies. Alternatively, proposals have been made to replace the defective disc with an artificial disc that preserves the natural mobility between adjacent vertebral bodies. For example, such prostheses can include first and second plates for fixing to adjacent vertebral bodies, the plates having low friction contact surfaces that allow articulation.  
      As part of the surgical procedure to replace a disc, the soft tissue connecting adjacent vertebral bodies is at least partially cut-away. This can cause a loss of stability, particular where a mobility retaining prosthesis is utilized. To replace the function of the connective tissue, a tissue implant can be implanted. For example, a tissue implant can fixed at a first end to a first vertebral body and fixed at a second end to second vertebral body. To fix the tissue implants to bone, a surgeon can drive a screw or staple through the tissue implant and into the native tissue.  
      One drawback of such procedures is that the tissue implant can be weakened by the fixation procedure. When the screw or staple is driven through the implant it can create a weak spot, which may tear under load. For example, the screw or staple could be pulled through the tissue implant when tension is applied.  
      Accordingly, there remains a need for improved tissue implant constructs and devices for fixing tissue implants, particularly, methods and devices that can fix tissue while causing a minimum weakening of the implant.  
     SUMMARY OF THE INVENTION  
      Described herein are methods and devices for fixing implants to bone. Unlike traditional fixation devices, such as bone screws or staples, the device described herein can include a large surface area for holding an implant in place. In addition, in at least one embodiment, the device is adapted to hold an implant without penetrating the implant. For example, an implant can be fixed in place between two surfaces of the device, between two devices, and/or between the device and a native tissue surface.  
      In one embodiment, the device includes a tissue fixation anchor having an elongate body with a longitudinal axis extending from a proximal end to a distal end. The body includes at least one opening for receiving a tissue implant and an aperture for receiving an expander. In one aspect, at least a portion of the aperture is coextensive with the tissue implant receiving opening and adapted to receive both a tissue implant and an expander. A tissue implant can be fixed within the implant receiving opening by positioning an expander within the aperture.  
      In one aspect, a tissue implant can be inserted into the tissue receiving opening and an expander can be inserted into the aperture such that the expander fixes tissue between an inner surface of the device and the expander. Alternatively, or additionally, the expander can radially expand the body of the device to fix tissue between an outer surface of the device and a native tissue surface.  
      The tissue receiving opening can extend through the body along an axis perpendicular to the longitudinal axis. For example, the opening can be defined by a transverse slot. In one aspect, the opening is positioned at the distal end of the body and extends to the distal end of the body. The aperture adapted to receive an expander can extend along the longitudinal axis of the body. In one aspect, the aperture can extend from the proximal end of the body to the tissue receiving opening.  
      In another embodiment described herein, a system for fixing a tissue implant to native tissue is provided. The system can include an anchor having an elongate body with a longitudinal axis extending from a proximal end to a distal end and an expander adapted for radial expansion. The body can include an opening for receiving a tissue implant and an aperture for receiving the expander. The body can also include an interior portion adapted to receive the expander and a tissue implant. In one aspect, the interior portion is positioned at the intersection of the opening and the aperture. When the expander is inserted into the device it can fix an implant positioned within the interior portion.  
      In yet another embodiment, a two-part tissue fixation device is provided. The device includes a first body having a generally wedge shape and at least one tissue implant receiving opening and a second body having a generally wedge shape with a proximal and distal end. The proximal end of the second body can include a slot adapted for receiving the first body. In one aspect, the first body is adapted to receive at least a portion of a tissue implant and the second body is adapted for receiving the first body, such that implanting the second body within native tissue fixes the tissue implant within the first body.  
      In yet another embodiment, A soft tissue implant is provided. The implant can include a longitudinally extending tissue implant having a body defined by a superior and inferior end, at least one of the superior and inferior ends including a recess adapted to receive an anchor. The implant body can be formed of a pliable, biocompatible material such that an anchor positioned within the at least one recess can be implanted in an aperture formed in a hard tissue surface without contacting the native tissue.  
      A method for fixing a tissue implant is also provided. In one embodiment, the method includes the steps of providing a pliable, biocompatible tissue implant having a longitudinally extending body and providing a tissue anchor. The body of the tissue implant can include a recess adapted to receiving a tissue anchor. The method further includes the step of positioning the tissue implant on a hard tissue surface having an aperture and implanting the tissue anchor through the tissue implant and into the aperture in the hard tissue surface. In one aspect, the anchor is implanted within the hard tissue surface without contacting native tissue.  
      Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the following detailed description of the drawings and the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:  
       FIG. 1A  is an anterior view of a vertebral column with a disc prosthesis positioned between adjacent vertebral bodies;  
       FIG. 1B  is a side view of the vertebral column of  FIG. 1A  with one embodiment of a device described herein partially inserted into bone holes within the vertebral bodies;  
       FIG. 2A  is a side view of another embodiment of a device described herein;  
       FIG. 2B  is a perspective view of the device of  FIG. 2A  with a tissue implant positioned therein;  
       FIG. 3A  is a front view of yet another embodiment of a device described herein;  
       FIG. 3B  is a front view of another embodiment of the device illustrated in  FIG. 3A ;  
       FIG. 4A  is a perspective view of another embodiment of a device described herein;  
       FIG. 4B  is another perspective view of the device of  FIG. 4A ;  
       FIG. 4C  is a side view of the device of  FIG. 4A  with an implant positioned therein;  
       FIG. 5  is a perspective view of another embodiment of a device described herein;  
       FIG. 6  is a perspective view of yet another embodiment of a device described herein;  
       FIG. 7A  is a perspective view of still another embodiment of a device described herein;  
       FIG. 7B  is a perspective view of the device of  FIG. 7A  with an implant disposed in a portion thereof;  
       FIG. 8A  is a perspective view of another embodiment of the device of  FIG. 7A ;  
       FIG. 8B  is a side view of the device of  FIG. 8A ;  
       FIG. 9  is a perspective view of another embodiment of the device of  FIG. 7A ;  
       FIG. 10  is a schematic of another embodiment of a device described herein;  
       FIG. 11A  is a side view of a vertebral column and one embodiment of a device described herein; and  
       FIG. 11B  is an anterior view of a vertebral column showing the device of  FIG. 11A  implanted thereon. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention  
      Various exemplary methods and devices are provided for fixing an implant to native tissue, such as bone. One such device includes a body extending along a longitudinal axis from a proximal end to a distal end, the body including at least one opening for receiving a tissue implant. The body provides a large contact area for fixing the tissue implant to bone, such that the implant can be securely held in position when the device is implanted. In one embodiment, the body can include at least one aperture for receiving a fixation device, such as an expander. A tissue implant can be positioned in the implant receiving opening and then fixed to bone by implanting an expander in the at least one aperture. For example, the tissue implant can be held between the expander and the body and/or between the body and a tissue surface. In an alternative embodiment, the tissue fixation device described herein includes two bodies that can be used together to fix a tissue implant in place. For example, a first body can include at least one implant receiving opening and the second body can include a slot for receiving the first body. A tissue implant can be fixed to native tissue by positioning the implant within the implant receiving slot of the first body, positioning the first body within the second body, and then implanting the first and second bodies. In yet another embodiment, a tissue implant is provided. The tissue implant can be adapted to receive a fixation device (e.g., a tissue anchor), such that the fixation device can be implanted through the implant and into an aperture within hard tissue. In one aspect, the fixation device can fix the implant in place in such a way that the fixation device does not contact native tissue.  
      Unlike conventional devices, such as bone screws, the apparatus described herein can fix a tissue implant to bone without penetrating the implant. Conventional tissue implant fixation procedures can have the potential to weaken a tissue implant, specifically in the region where the implant is penetrated. In addition, the devices described herein provide a large surface area, which can join the tissue implant to bone and provide additional securement. Thus, even if an implant is penetrated by a device of the type described herein, the implant contacting surfaces of the device can help to prevent tearing of the tissue implant when tension is applied to the implant.  
       FIGS. 1A and 1B  illustrate a vertebral column with superior vertebral body  2  and inferior vertebral body  4  and a disc prosthesis  6  positioned therebetween. To replace connective tissue cut away during implantation of disc prosthesis  6 , a tissue implant  8  can be fixed to vertebral bodies  2 ,  4  with tissue implant fixation device  10 . For example, vertebral bodies  2 ,  4  can include bone holes  12  adapted to receive device  10 . Device  10  can mate with tissue implant  8  and be implanted in bone hole  12  to provide secure fixation of implant  8 . While device  10  is described with respect to implantation on a vertebral body, one skilled in the art will appreciate that device  10  can be implanted on a variety of native tissue surfaces for fixing a variety of tissue implants. Exemplary tissue surfaces include the variety of hard tissue surfaces that may or may not be covered with soft tissue. In particular, the terms “hard tissue surface,” “bone,” and “vertebral body” do not exclude structures having a native soft tissue coating or layer that may, for example, include cartilage, tendons, ligaments, meniscus, or other soft tissue structures.  
       FIGS. 2A through 6  illustrate exemplary embodiments of device  10  including a body  14  having a generally elongate shape extending along a longitudinal axis from a proximal end  16  to a distal end  18 . Body  14  can include an implant receiving opening  20  for receiving an implant and a aperture  22  for receiving a fixation device. In use, tissue implant  8  can be positioned in opening  20  and fixed in place by implanting device  10  into hole  12  in native tissue, such as, for example a vertebral body. Tissue implant  8  can be fixed between body  14  and expander  24  and/or between body  14  and a native tissue surface.  
      Body  14  can have a variety of shapes and sizes that are adapted for receipt within a bone hole. For example, body  14  can have a generally rectangular, cylindrical, triangular, or irregular shape.  FIGS. 2A and 2B  illustrate one embodiment of body  14  having a generally rectangular shape, while  FIG. 5  illustrates a generally cylindrical body. To facilitate insertion into a bone hole, body  14  can include a rounded distal tip. Body  14  can be, in one embodiment, flexible or semi-rigid and/or deformable, such that device  10  will conform to the tissue in which it is implanted, thereby enhancing contact and securement between native tissue and the tissue implant. Alternatively, body  14  can be rigid and/or non-deformable. One skilled in the art will appreciate that body  14  can be produced from the variety of materials used in orthopaedic or implantable devices, such as, for example metals, polymers, ceramics, synthetics, and/or natural materials. Examples include Ti64, CoCr, resorbable and non-resorbable polymers, allografts, autografts, xenografts, and combinations thereof.  
      Opening  20  can be positioned within body  14  in a variety of locations. In one embodiment, opening  20  is positioned toward distal end  18  of body  14  as shown in  FIG. 2A and 2B . For example, opening  20  can extend through the entire width of the distal portion of body  14  such that opening  20  defines a slot that extends through body  14  from a first side to a second side. In one aspect, opening  20  extends to the distal end of body  14  such that an implant can be inserted into device  10  from distal end  18 .  
      Opening  20  can have a size and shaped adapted for receiving a variety of tissue implants.  FIG. 2B  illustrates body  14  with a generally planar implant  8  positioned within implant receiving opening  20 . In one aspect opening  20  is sized such that it is larger than the thickness of an implant and the implant can be folded to accommodate the size of implant receiving opening. One skilled in the art will appreciate that a variety of alternatively shaped implants, such as implants having a circular cross-section, can be positioned in opening  20 .  
      In one aspect, opening  20  extends through body  14  and defines first and second body segments  26 ,  28  ( FIGS. 2A and 2B ). Body  14  can be formed of flexible or malleable materials such that implant  8  forms a friction fit with body segments  26 ,  28 . For example, implant  8  (or folded implant  8 ) can have a width that is slightly larger than the width W of opening  20 . When implant is positioned in opening  20 , body segments  26 ,  28  retain implant  8  in opening  20  with a friction fit.  
      Opening  20  can have a variety of alternative configurations, including a “closed” configuration.  FIGS. 3A and 3B  illustrate device  10  with opening  20  extending through a central portion of body  14  between proximal and distal ends  16 ,  18 . An implant can be threaded through opening  20  to position the implant in device  10 .  FIG. 3A  illustrates body  14  having an opening  20  having a generally “V” shape and  FIG. 3B  illustrates opening  20  having a generally “U” shape. An implant, such as an implant having a planar shape, can be bent or folded such that it has a shape corresponding to opening  20 . The implant can then be threaded through opening  20 .  
      In another embodiment, opening  20  has a larger width and a body extension portion  30  positioned therein. An implant can be threaded through opening  20  and around the body extension portions  30 . One such embodiment is illustrated in  FIGS. 4A through 4C  and includes two extension portions  30  that are defined by prongs that extend distally into opening  20 . An implant can be threaded between one side of extension portions  30  and the wall of the opening. Alternatively, as shown in  FIG. 4C , an implant can extended around the extension portions  30 .  
      In one embodiment, opening  20  can be designed to retain an implant when the implant is positioned in opening  20 . For example, an implant can be held in a friction fit as described above with respect to  FIGS. 2A and 2B . Alternatively, an implant is loosely held in opening  20  and can be fixed in place with a fixation device (e.g., an expander) by pinning the implant between the fixation device and the inner wall of opening  20 . For example, opening  20  can intersect aperture  22  such that an expander inserted into aperture  22  will contact an implant positioned within opening  20 . The expander can be inserted into device  10  and expand body  14  to pin an implant between the expander and the wall of the opening  20 . In yet another embodiment, an implant can be held in place by pinning the implant between the outer surface of body  14  and the wall of a bone hole when device  10  is implanted. For example, at least a portion the implant can be positioned between the outer surface of body  14  and the walls of bone hole  12  when device  10  is inserted into bone hole  12 . Radially expanding body  14  with the expander will secure the implant between device  10  and the wall of the bone hole.  
      By fixing an implant between an expander and device  10  and/or between device  10  and native tissue, an implant can be fixed in place without penetrating the implant. In addition, the large contact areas between body  14  (i.e., the inner and/or outer surface of the device) and the implant provide greater securement than traditional devices (i.e., bone screws or staples).  
      A variety of fixation devices can be used with device  10  to fix device  10  within a bone hole. In one embodiment, the fixation device is an expander which increases the diameter of device  10  when it is inserted into aperture  22 . For example, when device  10  is positioned within a bone hole, expander  24  can be inserted into aperture  22  to expand at least a portion of body  14  positioned within a bone hole. The expanded body  14  is thereby fixed in position, along with a tissue implant.  
      As shown in  FIG. 5 , body  14  can include an aperture  22  for receiving expander  24 . In one aspect, aperture extends from the proximal portion of body  14  and extends along longitudinal axis L. Aperture  22  can intersect opening  20  such that they are coextensive in at least one portion of body  14 . In the embodiment illustrated in  FIGS. 2A and 2B , aperture  22  extends distally until it intersects opening  20  which is positioned transversely with respect to longitudinal axis L. When expander  24  is inserted into aperture  22 , it can push body segments  26 ,  28  outward, fixing device  10  in a bone hole. Expander  24  can also fix an implant between an inner surface of body  14  and expander  24 , such as for example between the inner wall of opening  20  and the expander.  
      In one embodiment, device  10  can include at least one proximal slot that allows body  14  to expand. In one embodiment, illustrated in  FIG. 5 , body  14  includes two proximal slots  34 ,  36  that define upper body segments  38 ,  40  and which intersect aperture  22 . When expander  24  is positioned within aperture  22 , the upper portion of body  14 , particularly upper body segments  38 ,  40 , are forced outward into contact with the walls of a bone hole. If driven far enough into aperture  22 , expander  24  can also expand the distal portion of body  14 , particularly lower body segments  26 ,  28 .  
      As an alternative to slots, body  14  can be formed from a material which allows body  14  to expand when an expander is inserted into aperture  22 . For example, body  14  can be formed from a pliable or flexible material that allows body  14  to increase in diameter when expander  24  is inserted therein.  
      As part of the procedure for fixing the implant within bone holes  12 , the implant can be tensioned to provide improved tissue remodeling of the implant in the orientation of tensioning. For example, body  14 , bone hole  12 , and/or expander  24  can be can be configured such that expansion of device  10  and/or insertion of device  10  into bone hole  12  can be adjusted to tension the implant.  
      To assist with insertion of expander  24  into aperture  22 , device  10  and/or expander  24  can include mating features  42 . For example, the outer surface of expander  24  and the inner surface of aperture  22  can include threads, and the expander  24  can be screwed into aperture  22 . In another exemplary embodiment, expander  24  can mate with aperture  22  in body  14  via a snap-fit.  FIG. 6  illustrates device  10  with expander  24  positioned in aperture  22 . Aperture  22  includes a proximal slot that can extend from the proximal end of body  14  into implant receiving opening  20 . Expander  24  has a shape that corresponds to aperture  20  and opening  20 . For example, the expander can have a “T” shaped cross-section with a planar proximal portion adapted to sit between segments  38 ,  40  and a distal portion adapted to mate with opening  20 . Expander  24  can be positioned with the wider distal portion fitted within opening  20 , such that proximal movement of the expander is prevented. The proximal portion of expander  24  can be positioned within aperture  22  such that upper body segments  38 ,  40  are expanded radially. In use, the device of  FIG. 6  pins the implant between the outer surface of body  14  and the walls of a bone hole. One skilled in the art will appreciate that a variety of alternative expanders having a variety of mating features can be used to implant device  10  within a bone hole.  
      Body  14  can include a variety of features to assist with implantation/securement and/or tissue in-growth. In one aspect, outer surface  44  of body  14  includes surface features  46  that will contact native tissue when device  10  is implanted. Such surface features can include, for example, barbs, tines, fins, ribs, securement ridges, textured patterns, etchings, porous beading, and/or other coatings/treatments that promote soft or boney tissue apposition, integration, and/or resporbtion. In addition, or alternatively, surface features  46  can be adapted to resist movement out of a bone hole into which the device is implanted. For example, the surface features can be configured such that they will dig into bone if the device moves out of a bone hole. In one embodiment, shown in  FIGS. 2A and 2B , transverse ridges  47  can encircle the outer surface  44  of body  14 . The ridges have a distal-to-proximal slope and can include a bone penetrating proximal surface, such that the ridges do not resist implantation, but resist retropulsion.  
      In addition, surface features can be positioned on the inner surfaces of body  14  such that they contact an implant positioned within opening  20 . For example, such surface features can be positioned on the inner surface of opening  20  and/or aperture  22 .  
      In another embodiment described herein, device  100  is provided for fixing and implanting a tissue implant. In one aspect, device  100  includes a first body and a second body that work together to pin an implant therebetween and fix the implant to native tissue. The first body can be defined by a fixation device such as an expander that is adapted to receive at least a portion of a tissue implant and that is adapted to be inserted into the second body.  
       FIGS. 7A through 9  illustrate one exemplary embodiment of device  100  including first body  114   a  and second body  114   b . First body  114   a  can include at least one tissue receiving opening  120  and has a size and shape such that when first body  114   a  is inserted into second body  114   b , the second body is expanded. The second body  114   b  can include aperture  122  for receiving first body  114   a . In one aspect, the aperture  122  of second body  114   b  is defined by a proximal slot that can be expanded when first body is inserted therein.  
      First and second bodies  114   a ,  114   b  can have a variety of shapes and sizes. In one embodiment, the first and second bodies are adapted for implantation in hard tissue, such as a vertebral body or other bone structure. First body  114   a  can have a wedge-type shape that extends from a proximal end  116   a  to a distal end  118   a  such that the thickness of body  114   a  decreases from the proximal to the distal direction. In one aspect body  114   a  is shaped and sized such that it can be received in aperture  122  of body  114   b . As body  114   a  is forced into body  114   b  it causes the width of body  114   b  to expand, thereby fixing device  100  in place with hard tissue.  
      The proximal end of body  114   a  can have a variety of configurations, and in one embodiment illustrated in  FIGS. 7A and 7B , the proximal end of body  114   a  can be defined by cover  152 . Cover  152  can provide a surface for applying pressure to or for striking or impacting device  100  during the implantation procedure.  
      Between the proximal end  116   a  and distal end  118   a , first body  114   a  can include any number of tissue receiving openings, including none, one, two, or more than two. In the embodiment illustrated in  FIGS. 7A through 8B , first body  114   a  includes two openings  120   a ,  120   b , through which an implant can be threaded.  FIG. 7B  illustrates body  114   a  with implant  8  threaded through opening  120   a , through opening  120   b , around the distal end  118   a  of body  114   a , and then back through opening  120   a . When first body  114   a  is inserted into second body  114   b , implant  8  is held in place. In the embodiment illustrated in  FIG. 9 , body  114   a  has no implant receiving openings. However, an implant can be placed between body  114   a  and body  114   b , and upon inserting body  114   a  into body  114   b  the implant will be fixed between the bodies when the device  100  is implanted.  
      Second body  114   b  can have a variety of shapes and sizes adapted for implanting in a hard tissue surface. In one embodiment, second body  114   b  also has a generally wedge-type shape with a proximal end  116   b  and a distal end  118   b . Proximal end  116   b  can include aperture  122  for receiving body  114   a . Distal end  118   b  can be defined by a bone penetrating point that facilitates driving device  100  into a hard tissue surface. One skilled in the art will appreciate that depending on the tissue into which device  100  will be implanted and the preparation provided (i.e., bone hole), second body  114   b  can have a variety of different shapes, such as, wedge, rectangular, oval, and irregular.  
      As mentioned above, devices  10  and  100  can be used to fix a variety of implants. In one embodiment, the implant is a soft tissue implant formed from materials, such as, for example resorbable and non-resorbable polymers, allografts, autografts, xenografts, and combinations thereof. In one aspect, the implant is formed from graft materials, such as, for example tendenous, cartilaginous, ligamentous, protein or collagen based materials, extra-cellular matrices (ECMs), or other synthetic resorbable or non-resorbable graft materials. In yet another embodiment, the implant is formed from small intestine submucosa (SIS). The implant can also be reinforced/enhanced with a variety of materials to augment its natural properties and/or promote tissue growth. In one aspect, the implant can include a coating or laminate of resorbable polymers and/or be treated or coated with a variety of growth factors, anti-coagulants and/or lubricants. In addition, or alternatively, the implant can be oriented to minimize local soft tissue adhesion by positioning the implant such that the treated or luminal side (if ECM) is oriented toward local soft tissue.  
      Fixation of the implant can also be augmented with materials to enhance securement, apposition, integration, and/or to fill voids created by a device/implant recessed within a bone hole. Exemplary augmentation materials can include adhesives (e.g., fibrin, polymeric glues, etc.), bone void fillers (e.g., hydroxyapatite, tricalcium phosphate, DBM putty, bone cement, and combinations thereof, etc.), injectable bone substitutes (e.g., collagen, BMP, etc.), growth factor delivery systems (e.g., osteoconductive matrix formulations (Healos), recombinant human growth/differentiation factor-5 (MP52), etc.), and combinations thereof. Augmentation can also be in the form of sutures wrapped around the implant and/or device. An alternative method of augmentation can include a plug or a second bone anchor that can fill voids between, above, or below the implanted device.  
      In another embodiment described herein, a tissue implant  200  is provided which is adapted to receive a fixation device therein. Instead of device, such as devices  10 ,  100  described above that receive an implant, the tissue implant includes buckets or recesses that are adapted to receive a fixation device. The fixation device is inserted into the bucket or recess of the implant to secure the implant within a bone hole. In one aspect, the fixation device can be implanted in the bone hole without penetrating the implant and without contacting the native tissue surfaces of the bone hole.  
      One embodiment of the tissue implant  200  is illustrated in  FIG. 10 , in which implant  200  includes an elongate body  214  that extends from an inferior end  216  to a superior end  218 . Tissue implant  200  can include at least one recess  260  that is sized and shaped to receive a fixation device  224 . In one embodiment, tissue implant  200  is adapted to receive a fixation device  224  that can be expanded radially. Alternatively, fixation device  224  can be implanted in bone hole  12  with a friction fit. One skilled in the art will appreciate that the variety of known fixation devices, including radially expanding tissue anchors, can be used with tissue implant  200 .  
      In one aspect, tissue implant  200  is sized and shaped for spanning adjacent vertebral bodies. The tissue implant  200  can include recesses  260  in the inferior end  216  and superior end  218  for receiving fixation devices. As shown in  FIG. 10 , the fixation device can be implanted into bone holes  12  on adjacent vertebral bodies with the tissue implant  200  positioned between the fixation devices and the inner surfaces of the bone holes. In another embodiment, illustrated in  FIGS. 11A and 11B , device  200  can include multiple recesses  260  at inferior and superior ends  216 ,  218 .  
      Body  214  can be formed of a biocompatible material that is in one embodiment flexible or pliable. When fixation devices  224  are implanted, they can be radially expanded such that they expand the recess  260  and fix device  200  in place. In an alternative embodiment, recesses  260  can be sized such that they are at least as wide as bone holes. Fixation devices  224  can be radially expanded without stretching body  214 . In one embodiment, fixation devices are adapted to fix tissue implant  200  to bone without penetrating the tissue implant. For example, tissue implant  200  can be fixed between fixation device  224  and native tissue without fixation device  224  contacting the walls of bone hole  12 .  
      Exemplary materials from which body  214  can be formed include metals, ceramics, polymers, synthetic and/or natural materials. Examples include, resorbable and non-resorbable polymers, allografts, autografts, xenografts, and combinations thereof. In one exemplary embodiment, body  214  is formed from tendenous, cartilaginous, ligamentous, protein or collagen based materials, extra-cellular matrices (ECMs), or other synthetic resorbable or non-resorbable graft materials. In yet another embodiment, body  214  is formed from small intestine submucosa (SIS). In addition, body  214  can include the various materials described above to enhance and/or augment implantation.  
      One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.