Abstract:
Systems and methods for ligament reconstruction provides an implant configured to position ligaments in the anatomic positions to thereby to restore the native anatomy and function of the reconstructed area. The implant includes a sheath, a first ledge, a second ledge, a first anchor and a second anchor. The sheath has an exterior surface and an interior surface, wherein the interior surface of the sheath forms a lumen configured to receive a sheath expander. The first ledge and the second are configured to separate the ligaments and acts as an anchor for the sheath in the bone tunnel. The first anchor and the second anchor are configured to engage the ligaments and be expandable outwards away from the lumen to provide fixation in a bone tunnel. When the implant receives the sheath expander, the ligaments can be separated, positioned, and secured in the bone tunnel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/407,296, filed Oct. 27, 2010, and entitled “Single Tunnel, Double Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Grafts,” which is hereby incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       FIELD OF THE INVENTION 
       [0003]    The present invention generally relates to a system and method for ligament reconstruction in a joint. More particularly, the present invention relates to a method of and an implant for performing a single-tunnel, double-bundle reconstruction in a joint. 
       BACKGROUND OF THE INVENTION 
       [0004]    The anterior cruciate ligament (“ACL”) is one of the major ligaments in the knee that connects the thigh bone (“femur”) to the shin bone (“tibia”). The ACL is critical to the stability of knee during daily and sports activities. The ACL consists of two functional bundles named for the place where they attach on tibia. Specifically, the two bundles are the anteromedial (“AM”) bundle, which inserts more anterior (towards the front) and medial (towards the inside) of tibia, and the posterolateral (“PL”) bundle, which inserts most posterior (towards the back) and lateral (towards the outside) of tibia. The AM bundle is the primary restraint to anterior tibial translation throughout the knee flexion. The PL bundle also contributes to the anterior tibial stability at low flexion angles and primarily provides rotational stability to the joint. Although the two bundles have slightly different functions, the bundles do not work independently, but work together to keep the knee stable while still allowing jumping, running, and the like. 
         [0005]    There is a high prevalence of ACL injuries both in athletic and non-athletic population. ACL reconstruction is commonly performed to replace an injured ACL. The goal of ACL reconstruction is to restore the native anatomy and function of the ACL. However, osteoarthritis has been reported among patients who had an ACL reconstruction surgery. Improving ACL reconstruction techniques that may restore normal knee stability and prevent joint degeneration remains a subject of continuing debate in sports medicine research. 
         [0006]    Currently there are three types of methods and corresponding implants that have been used in ACL reconstruction surgery. The three types are the single-bundle reconstruction, the double-tunnel, double-bundle reconstruction, and the single-tunnel, double-bundle reconstruction. 
         [0007]    In a single-bundle reconstruction, the ACL is restored using one graft bundle. Two tunnels (one on tibia and one on femur) are drilled through the knee to house the one graft bundle. One tunnel can be drilled in the center of the attachment of the old ACL on the tibia, right between the AM and PL bundle. The other tunnel can be drilled in the center of the attachment of the old ACL on the femur. Since single-bundle constructions emphasize only on one bundle, typically the AM bundle, it can not recreate the two functional bundles of ACL. Studies have shown that single-bundle ACL reconstruction fails to restore tibial rotation to the intact level. Patients continue to report a feeling of rotational instability and have developed degenerative changes in the knee joint. These observations are attributed to the limitation of using single-bundle ACL reconstruction to reproduce both functional bundles of ACL. 
         [0008]    In order to improve on single-bundle ACL reconstruction, especially to provide a better rotational stability, double-tunnel, double-bundle ACL reconstruction was introduced, where ACL is restored using two graft bundles. Compared to single-bundle reconstruction, there are some benefits of a double-bundle reconstruction. Since double-tunnel, double-bundle reconstruction restores both of the AM and PL bundles, it can better restore knee stability compared to single-bundle reconstruction. Nevertheless, double-tunnel, double-bundle reconstruction is a technically challenging procedure. For example, instead of drilling two tunnels for one graft bundle, as in single-bundle reconstruction, double-tunnel, double-bundle reconstruction requires that four tunnels be drilled. The four tunnels include two tibial and two femoral tunnels, for housing two bundles. By drilling two more tunnels, there is an elevated risk of damage to the bone bridge between the two tunnels and an excessive loss of bone. Furthermore, double-tunnel, double-bundle reconstruction is also associated with an increase in the duration of surgery and higher cost compared to the single bundle reconstruction. These limitations in the current designs of the ACL reconstruction techniques leave a large scope for an improvement in the surgery. 
         [0009]    To address the deficiency in double-tunnel, double-bundle ACL reconstruction, single-tunnel, double-bundle ACL reconstruction was introduced. Single-tunnel, double-bundle reconstruction uses a single femoral and tibial tunnel and an implant that separates the graft into AM and PL bundles. This reconstruction not only allows the reconstruction of the two functional bundles of the ACL in a single tibial and femoral tunnel to provide superior stability than single-bundle ACL reconstruction, but also is technically less demanding, and decreases operative time. Currently there are two types of implants designed for single-tunnel, double-bundle ACL reconstruction. These implants include the AperFix and Femoral INTRAFIX implants. AperFix is a registered trademark of Cayenne Medical, Inc. of Scottsdale Ariz. INTRAFIX is a registered trademark of Johnson &amp; Johnson of New Brunswick, N.J. There is evidence that neither of these implants can restore normal knee biomechanics. 
         [0010]    Therefore, it would be desirable to have an improved system and method for ligament reconstruction, which can better restore the native anatomy and function of the ligament or ligaments in a joint. 
       SUMMARY OF INVENTION 
       [0011]    The present invention overcomes the aforementioned deficiencies by providing a method and implant for single-tunnel, double-bundle reconstruction in a joint. The implant can readily arrange two graft bundles in the anatomic positions of, for example, AM and PL bundles in a single-tunnel, double-bundle ACL reconstruction, thereby to restore the native anatomy and function of the ACL. 
         [0012]    In accordance with one aspect of the invention, a surgical implant for implementing a ligament reconstruction in a subject using a first ligament and a second ligament as graft is provided. The implant includes a sheath, a first ledge, a second ledge, a first anchor, and a second anchor. The sheath extends along a length from a first end to a second end to form an exterior surface and an interior surface. The interior surface of the sheath forms a lumen configured to receive a sheath expander. The first ledge and the second ledge are formed on the exterior surface of the sheath and extend along the length of the sheath. The two ledges are formed in a spaced relationship to each other in order to form a first space and a second space extending along the exterior surface of the sheath between the first ledge and the second ledge. The first anchor and the second anchor are formed on the exterior surface of the sheath in the first space and the second space, respectively, and extend along the length of the sheath. 
         [0013]    When a first ligament and a second ligament are engaged with an implant in accordance with the present invention and implanted in a bone tunnel of a joint, a first ledge and a second ledge of the implant cause the ligaments to engage with the first anchor and the second anchor, respectively. That is the first ledge and the second ledge of the implant are configured to separate the first ligament and the second ligament and also to penetrate into the bone tunnel to anchor the sheath in it. Furthermore, the first anchor and the second anchor are configured to move from a retracted position to an extended position in response to a sheath expander extending through a lumen formed by a sheath upon which the first and second anchor and the first and second ledge are formed. The first ligament and the second ligament can be readily arranged and secured in a bone tunnel. Therefore, the implant is capable of separating, arranging, and securing the first ligament and the second ligament in the anatomic positions of, for example, AM and PL bundles in a single-tunnel, double-bundle reconstruction. 
         [0014]    In accordance with another aspect of the invention, a method for using an implant includes forming a bone tunnel in a joint, such as the knee, to reconstruct the joint, for example, to repair an injured ACL. A K-wire can be inserted through the bone tunnel extending through opposing sides of the joint. A first ligament and a second ligament, along with the implant are passed through the tunnels. The first ligament and the second ligament are rotated in one tunnel until they are positioned. A sheath expander is inserted into the lumen of the implant. The sheath expander firmly engages the first ligament and the second ligament onto the inner surface of the tunnel. After the ligaments are secured in one tunnel, the other end of the ligaments can be oriented in the anatomical bundle footprints, giving rise to the desired bundles. Thereafter, the above-described process for positioning and securing the implant and ligaments is repeated in the other tunnel. 
         [0015]    The foregoing and other aspects and advantages of the invention will be made apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of a knee joint having an implant utilized in a single-tunnel, double-bundle ACL reconstruction in accordance with embodiments of the present invention. 
           [0017]      FIG. 2  is a perspective view of the implant of  FIG. 1  and a sheath expander for use with the implant, in accordance with embodiments of the present invention. 
           [0018]      FIG. 3  is a perspective view of an alternative embodiment of the implant of  FIG. 1  and a sheath expander for use with the implant, in accordance with embodiments of the present invention. 
           [0019]      FIG. 4  is a top view of the implant of  FIG. 3 . 
           [0020]      FIG. 5  is a side view of the implant of  FIG. 3 . 
           [0021]      FIGS. 6   a - 6   d  are perspective views of the implant of  FIG. 1  and sheath expander in various stages of implantation in an associated tunnel, in accordance with embodiments of the present invention. 
           [0022]      FIG. 7  is a flow chart setting forth the steps of a method of performing an embodiment of a single tunnel, double bundle ACL reconstruction, in accordance with embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Referring to  FIG. 1 , a representative joint  100  is shown. The joint  100  is formed at the meeting of a femur  102 , tibia  104 , and fibula  106 . Formed in the femur  102  is a first, femoral, bone tunnel  108  and formed in the tibia  104  is a second, tibial, bone tunnel  110 . Arranged in the bone tunnels  108 ,  110 , are a pair of implants  112 ,  114  configured for implementing a single-tunnel, double-bundle ACL reconstruction, in accordance with one embodiment of the present invention. Specifically, a first ligament graft  116  and a second ligament graft  118  are formed to be a graft bundle for AM bundle and PL bundle. Hamstring tendon autografts and allografts are preferred graft material used as the first ligament  116  and the second ligament  118 . Other graft materials, such as achilles tendon, quadriceps tendon, and tibialis tendon can also be used according to the present invention. 
         [0024]    Although  FIG. 1  and the description of the invention is given with respect to ACL reconstruction, the present invention can be used for, but not limited to, posterior cruciate ligament (“PCL”) and medial collateral ligament (“MCL”) reconstruction, and other ligament reconstructions in various joints, such as, but not limited to, shoulder, elbow and ankle joints, for example. ACL reconstruction using the present invention can readily be accomplished by surgeons who are familiar with single bundle reconstruction. 
         [0025]    The first implant  112  is engaged with a first end (not shown to allow full view of the first implant  112 ) of the first ligament  116  and a first end (not shown to allow full view of the first implant  112 ) of the second ligament  118  into the femoral tunnel  108 . The second implant  114  is engaged with a second end  120  of the first ligament  116  and the second ligament  118 . As will be described in further detail, the first ligament  116  and the second ligament  118  are separately engaged with the implants  112 ,  114  in a spaced relationship. As will also be described in further detail, a first sheath expander  122  is engaged with the first implant  112  to secure the first ligament  116  and the second ligament  118  into the femoral tunnel  108 . Likewise, a second sheath expander  124  is engaged with the second implant  114  to secure the first ligament  116  and the second ligament  118  into the tibial femoral tunnel  110 . 
         [0026]      FIG. 2  shows a perspective view of the implant  112  and the sheath expander  122  as shown in  FIG. 1 , in accordance with the present invention. Since the first implant  112  and the second implant  114 , the first sheath expander  122  and the second sheath expander  124  have substantially identical structure, the implant  112  and the sheath expander  122  are discussed as an example representing both the first implant  112 , the second implant  114 , the first sheath expander  122  and the second sheath expander  124 , respectively. 
         [0027]    Referring now to  FIG. 2 , an implant, for illustrative purposes the first implant  112  of  FIG. 1 , is shown. It is noted that, for purposes of implementing a single-tunnel, double-bundle reconstruction in accordance with the present invention, the first implant  112  and the second implant  114  of  FIG. 1  may be substantially similar. In this case, for purposes of clarity, the description of the implants  112 ,  114 , will focus on the design of the first implant  112 . 
         [0028]    The implant  112  includes a sheath  200  that extends along a length of the implant  112  illustrated by arrow  202  between a first end  204  and a second end  206 . Located at the first end  204  of the sheath is an opening  208  providing access to a lumen  210  formed by an interior surface  212  of the sheath  200  that runs substantially parallel to an exterior surface  214  of the sheath  200 . The second end  206  of the sheath  200  may form a taper  216  designed to facilitate insertion into a bone tunnel  108 ,  110  of  FIG. 1 . 
         [0029]    Formed on the exterior surface  214  of the sheath  200  is a first ledge  218  and a second ledge  220  that extend along the length  202  of the sheath  200 . The first ledge  218  and the second ledge  220  are formed in a spaced relationship on the exterior surface  214  of the sheath  200  to form a first space  222  and a second space  224 . This planar or flat area  223  formed in the first space  222  and the second space  224  facilitates contact between the ledges  218 ,  220 , ligament grafts  116 ,  118  and a bone tunnel when arranged in a bone tunnel, thereby, providing strong fixation therein. 
         [0030]    In the first space  222 , a first anchor  226  is formed on the exterior surface  214  of the sheath  200  and extending along the length  202  of the sheath  200 . In the second space  224 , though not visible in  FIG. 2  is a second anchor that is substantially opposite and substantially similar to the first anchor  226 . The first anchor  226  includes a first furrow  228  and the second anchor includes a second furrow. The furrows  228  form a V-shape extending into the lumen  210 . Arranged within the furrow  228  are a plurality of ridges  230 . As will be described, the ridges  230  serve to prevent slippage between the ligament grafts  116  and  118  and the implants  112  and  114  and bone tunnels  108  and  110 . 
         [0031]    The interior surface  212  of the sheath  200  may include threading  231  to facilitate extension of the sheath expander  122  through the lumen  210  when received through the opening  208  of the sheath  200 . Accordingly, the sheath expander  122  may include reciprocal threading  232  extending between opposing first and second ends  234 ,  236 . In addition the sheath expander  122  may include a taper  238  arranged at the first end  234  and head  240  formed at the second end  236 . In this arrangement, the head  240  may include a socket or other engagement mechanism  242  for accepting a reciprocal driving mechanism. 
         [0032]    Referring to  FIGS. 3 ,  4  and  5 , an alternative embodiment of the implant  112  is shown. The implant  312  includes a sheath  300  that extends along a length of the implant  312  illustrated by arrow  302  between a first end  304  and a second end  306 . Located at the first end  304  of the sheath is an opening  308  providing access to a lumen  310  formed by an interior surface  312  of the sheath  300  that runs substantially parallel to an exterior surface  314  of the sheath  300 . The second end  306  of the sheath  300  may form a taper  316  designed to facilitate insertion into a bone tunnel  108 ,  110  of  FIG. 1 , for example. 
         [0033]    Formed on the exterior surface  314  of the sheath  300  is a first ledge  318  and a second ledge  320  that extend along the length  302  of the sheath  300 . The first ledge  318  and the second ledge  320  are formed in a spaced relationship on the exterior surface  314  of the sheath  300  to form a first space  322  and a second space  324  (not visible). A plurality of ribs  325  may be added on one or both ledges  318 ,  320  of the sheath  300 . These ribs  325  may be provided to provide additional contact and prevent the slippage between the sheath  300  and a bone tunnel when arranged in a bone tunnel. The planar or flat area  323  formed in the first space  322  and the second space  324  also facilitates contact between the ledges  318 ,  320 , ligament grafts  116 ,  118  and a bone tunnel when arranged in a bone tunnel, thereby, providing strong fixation therein. 
         [0034]    Longitudinal slots  327  at the vertex of the first space  322  and the second space  324  on one or both sides of the implant may be included. The longitudinal slots may include one or more connection points  329 . The longitudinal slots  327  and connection points  329  can facilitate a controlled radial expansion of the sheath  300  when the sheath expander  122  is inserted into the lumen  310 , and hence prevent sheath fracture at undesirable locations. 
         [0035]    In the first space  322 , a first anchor  326  is formed on the exterior surface  314  of the sheath  300  and extending along the length  302  of the sheath  300 . In the second space  324 , though not visible in  FIG. 3 , is a second anchor that is substantially opposite and substantially similar to the first anchor  326 . The first anchor  326  includes a first furrow  328  and the second anchor includes a second furrow. The furrows  328  form a V-shape extending into the lumen  310 . Arranged within the furrow  328  are a plurality of ridges  330 . As will be described, the ridges  330  serve to prevent slippage between the ligament grafts  116  and  118  and the implant  312  and a bone tunnel. 
         [0036]    The interior surface  312  of the sheath  300  may include threading  331  to facilitate easy insertion and advancement of the sheath expander  122  (see  FIG. 2 ) into and through the lumen  310  when received through the opening  308  of the sheath  300 . Accordingly, the sheath expander  122  may include reciprocal threading  232  extending between opposing first and second ends  234 ,  236 . In addition the sheath expander  122  may include a taper  238  arranged at the first end  234  and head  240  formed at the second end  236 . In this arrangement, the head  240  may include a socket or other engagement mechanism  242  for accepting a reciprocal driving mechanism. In some embodiments, the first end may include a diameter smaller that the diameter of the second end. 
         [0037]    Referring now to  FIGS. 6   a - 6   d , the operation and configuration of the implants  112 ,  114 ,  312  for performing a single-tunnel, double bundle reconstruction will be described. It is noted that, for purposes of implementing the reconstruction in accordance with the present invention, operation of the implants  112 ,  114 ,  312  may be substantially similar. In this case, for purposes of clarity, the description of the operation of implants  112 ,  114 ,  312  will focus on the design of the first implant  112 . For the purpose of clearly showing the implant  112 , the first ligament  116  and the second ligament  118  are ignored in  FIG. 6   a - 6   d . As illustrated in  FIG. 6   a , use of the sheath  200  begins with the sheath  200  being free of additional components. As illustrated in  FIGS. 1 and 6   b , the implant  112  is arranged in a bone tunnel  108 . Again, as described with respect to  FIG. 2 , the second end  206  of the sheath  200  may include the taper  216  to further facilitate placement. However, as best illustrated in  FIG. 6   b , the bone tunnel  108  will generally include a diameter sufficient to receive the first and second ledges  218 ,  220 , and ribs  325  in the case of implant  312 , that extend along the exterior of the sheath  200  thereby further delineating the first space  222  and second space  224 , such that the first and second ligament  116 ,  118  can be readily arranged in the first space  222  and second space  224 , respectively. In this regard, the first and second ligament  116 ,  118  are separated by the first and second ledges  218 ,  220  and arranged in the first furrow  228  and the second furrow (obscured in view). 
         [0038]    Within this configuration, as best illustrated in  FIGS. 2 and 6   c , the sheath expander  122  may be extended into the sheath  200 . As the sheath expander  122  extends through the opening  208  and into the lumen  210  of the sheath  200 , the threading  232  of the sheath expander  122  engages the threading  231  and anchors  226  and associated furrows  228  that, by default are in a retracted position extending into the lumen  210 . In this regard, the sheath expander  122  forces the anchors  226  and, particularly, the furrow  228  to extend outward away from the lumen  210  of the sheath  200  into an extended position. That is, the anchors  226  gradually move or deform from a concave form to a convex form extending away from the lumen  210 . In this regard, with the furrow  228  extended outward, the anchors  226  thereby serve a plurality of functions. First, the anchors  226  engage the bone tunnel  108  to anchor the sheath  200  in the bone tunnel  108 . Second, since the ligaments  116 ,  118  are arranged in the first and second space  222 ,  224 , respectively, they are likewise engaged by the anchors  226  as they move the furrows  228  into the extended position to lock the ligaments  116 ,  118  in the first and second space  222 ,  224 , respectively. 
         [0039]    Referring to  FIG. 6   d , as the sheath expander  122  is fully received by the implant  112 , the first anchor  226  and the second anchor are in the extended position. In the extended position, the ridges  230  on the furrow  228  provide desired interference fixation between the first ligament  116  and the tunnel  108 , and between the second ligament  118  and the tunnel  108 . As a result, this interference fixation can prevent the first ligament  116  and the second ligament  118  from slippage past the sheath  200  and bone. Additionally or alternatively, one or more ridges  230  may be replaced or partially replaced by openings  209 ,  309  configured to allow the threading  232  of the sheath expander  122  to pass therethrough when engaged with the sheath  200  to thereby engage the ligaments  116 ,  118  and, in some configurations, even engage the bone tunnel  108 . Furthermore, as the sheath expander  122  is inserted into the implant  112 , the sheath expander  122  also push the first ledge  218  and the second ledge  220  towards and into the bone tunnel  108 . As a result, the first ledge  218  and the second ledge  220 , and ribs  325  in the case of implant  312 , bite into the bone tunnel  108  and further counter forces that could cause the implant  112  to rotate in the bone tunnel  108  due to torques applied to the implant  112  during engagement with the sheath expander  122 . This is at least partially achieved by the opposing configuration of the ledges  218 ,  220  and the fact that, despite the large spaces  222 ,  224  that facilitate the placement of substantial bundles, such as used in double-bundle, single-tunnel reconstruction, the design of, for example, only two ledges  218 ,  220 , and ribs  325  in the case of implant  312 , arranged in opposition and expanded radially outward away from one another when receiving the sheath expander  122  provides the forces desired to secure the implant in the bone tunnel. It is noted that the implant  112  may continue to be a single continues piece even after the sheath expander  122  or screw is completely inserted, reducing the risk of relative motion of the two plates formed by the ledges  218 ,  220 . In the case of implant  312 , after the sheath expander  122  or screw is completely inserted, the implant remains as a single piece, yet the implant includes the one or more longitudinal slots  327  and connection points  329  to allow for a controlled expansion. 
         [0040]    This anterior cruciate ligament reconstruction is a minimally invasive surgery that can be performed arthroscopically. Referring to  FIG. 7 , an exemplary flow chart is provided for a single-tunnel, double-bundle ACL reconstruction using embodiments of the present invention. It is to be appreciated that although described with respect to ACL reconstruction, one of ordinary skill in the art can extend these concepts to other joint/ligament reconstruction. 
         [0041]    To perform a reconstruction with the implant, a tibial tunnel can reamed through the anteromedial surface of the tibia at the level of tibial tubercle passing through the landmarks of the center of ACL remnant, as illustrated by process block  400 . A K-wire can be inserted through the tibial tunnel aimed at 2 or 10 o&#39;clock position, for example, on the intercondylar clock and 7 mm, or more or less, anterior from the posterior bony edge of the intercondylar wall of the femur, as illustrated by process block  402 . At process block  404 , a femoral tunnel can be reamed through the tibial tunnel or through a portal independent of the tibial tunnel using a cannulated reamer. The first ligament and the second ligament, along with the implant can be passed through the tibia tunnel or through a portal independent of the tibial tunnel into the femoral tunnel, as represented by process block  406 . The first ligament and the second ligament can be rotated in the femoral tunnel until they are positioned in the native AM and PL bundle configuration. At process block  408 , a sheath expander can then be inserted clockwise into the lumen of the implant. The sheath expander can firmly engage the first ligament and the second ligament onto the inner surface of the femoral tunnel. After the ligaments are secured at the femoral end, the distal end of the ligaments can be oriented in the anatomical AM and PL bundle footprints, giving rise to the AM and PL bundles. As represented by process block  410 , similar to the femoral tunnel, implant and sheath expander can be used to fix the tibial end of the graft. 
         [0042]    It is worth noting that the above-described design includes a number of features that are particularly advantageous for facilitating certain surgical procedures. For example, the ledges  218 ,  220  are advantageously designed to provide large spaces  222 ,  224  therebetween, while still separating ligaments arranged therebetween and securing the implant. Specifically, the first ledge  218  and the second ledge  220 , and ribs  325  in the case of implant  312 , bite into the bone tunnel  108  and counter forces that could cause the implant  112  to rotate or move in the bone tunnel  108  due to torques applied to the implant  112  during engagement with the sheath expander  122  or other forces. This is at least partially achieved by the opposing configuration of the ledges  218 ,  220  and the fact that, despite the large spaces  222 ,  224  that facilitate the placement of substantial bundles, such as used in double-bundle, single-tunnel reconstruction, the design of, for example, only two ledges  218 ,  220  arranged in opposition and expanded radially outward away from one another when receiving the sheath expander  122  provides the forces desired to secure the implant in the bone tunnel. Also, by providing substantial spaces  222 ,  224  and arranging the anchors  226  and associated furrows  228  therein, the anchors  226  are configured to advantageously move between a first position to a second position in response to the sheath expander  122  extending through the lumen of the sheath to thereby engage the anchors  226  with a ligament arranged in the spaces and secure it within the reconstruction. Other configurations with reduced spaces  222 ,  224  or other such geometries do not achieve the similar ability of the anchors  226  to move between a first position to a second position in response to the sheath expander  122  extending through the lumen and, thus, do not achieve a similar ability to receiving a ligament or ligament bundle, secure the ligament, position/space the ligaments, and protect against movement or undesired forces placed upon the implant. 
         [0043]    The detailed description is provided for an implant system and method for using the same in accordance with the present invention. Embodiments are used herein to describe the principles and modes of carrying out the present invention. The above description of embodiments are only to help understand the systems and methods of the present invention. Those skilled in the art may modify modes of carrying out and application scope of the present invention according to the spirit thereof. In summary, the contents of the specification may not be construed as restrictive to the present invention.