Abstract:
An implantable bone anchor assembly comprises an outer anchor tube and a tubular insert. The outer anchor tube defines a longitudinal axis of the bone anchor assembly and a longitudinal channel. The outer anchor tube has a first portion including a first end, and a plurality of fingers circumferentially spaced from one another about the longitudinal axis. Each of the fingers extends from the first portion and has a free end, wherein the fingers are configured to project laterally at an oblique angle relative to the longitudinal axis, and are further configured to be deflectable radially inward to allow the anchor tube to be disposed within a tubular cannula for deployment. The tubular insert has a head having an opening therein, a shank extending from the head having an open end, and a longitudinal bore extending from the opening in the head to the open end of the shank. The longitudinal bore is configured to receive a portion of a suture assembly for an orthopedic treatment. The shank is sized to be received in the longitudinal channel, and the outer anchor tube and the tubular insert are configured to be locked together upon complete insertion of the shank into the longitudinal channel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/596,804, filed Feb. 9, 2012, which is herein incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to implants and instrumentation for surgical procedures. More specifically, the invention relates to a bone anchor and related suture assemblies and method of using the foregoing. 
       BACKGROUND 
       [0003]    Various conventional bone anchors are known for use in orthopedic repair procedures. There is a continuing need for improved bone anchors and related instrumentation. 
       SUMMARY 
       [0004]    In Example 1, an embodiment of the present invention is an implantable bone anchor assembly comprising an outer anchor tube and a tubular insert. The outer anchor tube defines a longitudinal axis of the bone anchor assembly and a longitudinal channel. The outer anchor tube has a first portion including a first end, and a plurality of fingers circumferentially spaced from one another about the longitudinal axis, each of the fingers extending from the first portion and having a free end. The fingers are configured to project laterally at an oblique angle relative to the longitudinal axis, and are further configured to be deflectable radially inward to allow the anchor tube to be disposed within a tubular cannula for deployment. The tubular insert has a head including an opening therein, a shank extending from the head having an open end, and a longitudinal bore extending from the opening in the head to the open end of the shank, the shank sized to be received in the longitudinal channel. The outer anchor tube and the tubular insert are configured to be secured together upon complete insertion of the shank into the longitudinal channel. 
         [0005]    In Example 2, the bone anchor assembly of Example 1, wherein the opening in the head and the open end of the shank are defined by radiused or chamfered edges. 
         [0006]    In Example 3, the bone anchor assembly of either of Examples 1 or 2, wherein the head of the insert has a radial shoulder that abuts the first end of the outer anchor tube when the shank is fully inserted into the longitudinal channel of the outer anchor tube. 
         [0007]    In Example 4, the bone anchor assembly of any of Examples 1-3, wherein the anchor tube includes a plurality of tabs configured to engage the insert to couple the insert and the outer anchor tube together when the shank is fully inserted into the longitudinal channel. 
         [0008]    In Example 5, the bone anchor assembly of any of Examples 1-4, wherein the outer anchor tube is made from a shape memory alloy. 
         [0009]    In Example 6, the bone anchor assembly of any of Examples 1-5, wherein the fingers of the outer anchor tube are configured to engage bone when implanted. 
         [0010]    In Example 7, the bone anchor assembly of any of Examples 1-6, further comprising an adjustable suture assembly including a first portion extending within the bore of the insert and configured to engage the insert to resist withdrawal of the first portion from the bore of the insert after implantation. 
         [0011]    In Example 8, the bone anchor assembly of any of Examples 1-7, wherein the outer anchor tube is a first outer anchor tube, and further comprising a second outer anchor tube having a longitudinal channel, and a plurality of fingers circumferentially spaced from one another about the longitudinal axis, each of the fingers of the second outer anchor tube having a free end and being configured to project laterally at an oblique angle relative to the longitudinal axis of the second outer anchor tube and to be deflectable radially inward to allow the second anchor tube to be disposed within a tubular cannula for deployment, wherein the shank of the insert is sized to be received within the longitudinal channel of the second outer anchor tube. 
         [0012]    In Example 9, the bone anchor assembly of Example 8, wherein the shank includes a plurality of serrations along a portion of its length, each serration including a first surface extending at an oblique angle with respect to the longitudinal axis of the bone anchor assembly and a second surface extending generally orthogonal to the longitudinal axis and oriented generally toward the head of the insert, wherein the second outer anchor tube is disposed along a portion of the shank including the serrations, and wherein the serrations and the second outer anchor tube cooperate to permit relative translation of the insert and the second outer anchor tube in a first direction, and to inhibit relative translation of the insert and the second outer anchor tube in a second direction opposite the first direction. 
         [0013]    In Example 10, the present invention is a fixation element for an orthopedic procedure, the fixation element comprising a bone anchor assembly and a suture assembly coupled to the bone anchor assembly. The bone anchor assembly includes an outer anchor tube and a tubular insert. The outer anchor tube defines a longitudinal axis of the bone anchor assembly and a longitudinal channel, and has a first portion including a first end, and a plurality of fingers circumferentially spaced from one another about the longitudinal axis. Each of the fingers extends from the first portion and has a free end, wherein the fingers are configured to project laterally at an oblique angle relative to the longitudinal axis, and are further configured to be deflectable radially inward to allow the anchor tube to be disposed within a tubular cannula for deployment. The tubular insert has a head including an opening therein, a shank extending from the head having an open end, and a longitudinal bore extending from the opening in the head to the open end of the shank, the shank sized to be received in the longitudinal channel. The outer anchor tube and the tubular insert are configured to be secured together upon complete insertion of the shank into the longitudinal channel. The suture assembly includes an adjustable suture loop and a knot configured for facilitating tightening of the suture loop. The bone anchor assembly is coupled to the adjustable suture loop. 
         [0014]    In Example 11, the fixation element of Example 10, wherein the bone anchor assembly is slidably coupled to the suture loop. 
         [0015]    In Example 12, the fixation element of either of Examples 10 or 11, further comprising a suture element connected to the bone anchor assembly and extending at least partially within the longitudinal bore of the insert, wherein the suture element is formed as a loop and is configured to slidably couple the bone anchor assembly to the adjustable suture loop. 
         [0016]    In Example 13, the fixation element of any of Examples 10-12, further comprising a second bone anchor assembly including an outer anchor tube and a tubular insert, the outer anchor tube of the second bone anchor assembly defining a longitudinal axis of the second bone anchor assembly and a longitudinal channel, and having a first portion including a first end, and a plurality of fingers circumferentially spaced from one another about the longitudinal axis, each of the fingers extending from the first portion and having a free end, wherein the fingers are configured to project laterally at an oblique angle relative to the longitudinal axis, and are further configured to be deflectable radially inward to allow the anchor tube to be disposed within a tubular cannula for deployment. The tubular insert of the second bone anchor assembly has a head including an opening therein, a shank extending from the head having an open end, and a longitudinal bore extending from the opening in the head to the open end of the shank, the shank sized to be received in the longitudinal channel. The outer anchor tube and the tubular insert of the second bone anchor assembly are configured to be secured together upon complete insertion of the shank into the longitudinal channel. The second bone anchor assembly is coupled to the adjustable suture loop. 
         [0017]    In Example 14, the fixation element of Example 13, wherein the bone anchor assembly and the second bone anchor assembly are slidably coupled to the adjustable suture loop. 
         [0018]    In Example 15, the fixation element of either of Examples 13 or 14, wherein one of the bone anchor assembly and the second bone anchor assembly is slidably coupled to the adjustable suture loop, and wherein the other of the bone anchor assembly and the second bone anchor assembly is fixedly coupled to the adjustable suture loop. 
         [0019]    In Example 16, the fixation element of Example 10, further comprising a tissue anchor coupled to the adjustable suture loop. 
         [0020]    In Example 17, the fixation element of Example 16, wherein the tissue anchor is formed from a length of suture material, and wherein the adjustable suture loop passes through the length of suture material of the tissue anchor at a plurality of locations therein. 
         [0021]    In Example 18, a method of deploying a fixation element for use in an orthopedic repair procedure. The method comprises forming a first bore within a first bone proximate tissue to be repaired, and positioning a cannula within the bore, the cannula releasably receiving at least a portion of a fixation element. The fixation element includes an outer anchor tube and a tubular insert. The outer anchor tube defines a longitudinal axis of the bone anchor assembly and a longitudinal channel, the outer anchor tube having a first portion including a first end, and a plurality of fingers circumferentially spaced from one another about the longitudinal axis, each of the fingers extending from the first portion and having a free end, wherein the fingers are configured to project laterally at an oblique angle relative to the longitudinal axis, and are further configured to be deflectable radially inward, wherein the cannula retains the fingers in the inward deflected configuration for delivery. The tubular insert has a head including an opening therein, a shank extending from the head having an open end, and a longitudinal bore extending from the opening in the head to the open end of the shank, the longitudinal bore configured to receive a portion of a suture assembly for an orthopedic treatment. The shank is sized to be received in the longitudinal channel, wherein the outer anchor tube and the tubular insert are configured to be locked together upon complete insertion of the shank into the longitudinal channel. The method further comprises removing the cannula while leaving the bone anchor assembly within the bore, wherein removing the cannula allows the fingers to project radially outward at an oblique angle to engage a surface within the bore. 
         [0022]    In Example 19, the method of Example 18, wherein the fixation element further includes an adjustable suture assembly including a first portion extending at least partially within the longitudinal bore of the insert coupled to the insert, and a second portion extending from or coupled to the first portion and including an adjustable suture loop. 
         [0023]    In Example 20, the method of either of Examples 18 or 19, wherein the fixation element further includes a second bone anchor assembly, and wherein the bone anchor assembly and the second bone anchor assembly are pre-loaded into the cannula prior to deployment of the bone anchor assembly and the second bone anchor assembly. 
         [0024]    In Example 21, the method of claim  20 , further comprising forming a second bore within the first bone or a second bone proximate tissue to be repaired, positioning the cannula into the second bore through the cannula, removing the cannula while leaving the second bone anchor assembly in the second bore. 
         [0025]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is an elevation view of a bone anchor assembly according to one embodiment of the present invention. 
           [0027]      FIG. 2  is a cross-sectional elevation view of the bone anchor assembly of  FIG. 1  according to one embodiment of the present invention. 
           [0028]      FIGS. 3-4  are elevation views showing the bone anchor assembly of  FIG. 1  during implantation, according to one embodiment of the present invention. 
           [0029]    FIGS.  5 - 10 A/B are schematic illustrations of various bone anchor/suture assembly combinations according to various exemplary embodiments of the present invention. 
           [0030]      FIGS. 11-13  are schematic illustrations of various bone anchor assemblies according to additional exemplary embodiments of the invention. 
           [0031]      FIG. 14  is a schematic illustration of the skeletal system of a human hand showing exemplary therapeutic applications of various embodiments of the present invention. 
           [0032]      FIG. 15  is a schematic illustration of the skeletal system of a human foot illustrating exemplary therapeutic applications of various embodiments of the present invention. 
       
    
    
       [0033]    While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0034]      FIGS. 1 and 2  are outer and cross-sectional elevation views of a bone anchor assembly  10  and a suture element  15  according to one embodiment of the present invention. The bone anchor assembly  10  and suture element  15  are, in the various embodiments, particularly suited for orthopedic repair procedures such as, for example, crossover toe, hallux valgus, hammertoe, carpometacarpal arthroplasty, Bankart repair, intervertebral disc repair procedures, or other general orthopedic procedures. As such, the suture element  15  is connected to the bone anchor assembly  10 , which when implanted in bone proximate the desired treatment site provides a firm anchoring point to resist tension applied to the suture element  15  both acutely during implantation and chronically after the procedure is complete. In various embodiments, the suture element  15  may include a pre-formed, adjustable suture loop (not shown) that can be interconnected with other suture elements or bone or soft tissue anchors depending on the desired repair technique. 
         [0035]    As shown in  FIGS. 1 and 2 , the bone anchor assembly  10  includes an outer anchor tube  20  and an insert  25 . As further shown, the outer anchor tube  20  defines a longitudinal axis  30  of the bone anchor assembly  10 , and its tubular shape defines a longitudinal channel  35 . In the illustrated embodiment, the outer anchor tube  20  includes a first portion  40  having a first end  42 , and a plurality of fingers  45  extending from the first portion  40  generally away from the first end  42 . As can be seen in  FIGS. 1 and 2 , the fingers  45  each have a free end  50  opposite the first portion  40  and terminate in a tip  52  and include edges  54  that are configured to engage bone at the implantation site for securing the bone anchor assembly  10  thereto. Additionally, the first portion  40  includes a plurality of cutouts  55  just proximal to each finger  45  (only one cutout  55  is visible in  FIGS. 1 and 2 ) and a plurality of U-shaped cutouts each forming a tab  57  between the cutouts  55  and the first end  42 . 
         [0036]    As further shown in  FIGS. 1 and 2 , each of the fingers  45  is configured to project laterally at an oblique angle relative to the longitudinal axis  30 . In addition, the fingers  45  are configured to be deflectable radially inward (i.e., the free ends  50  can be urged toward the longitudinal axis  30 ) to allow the anchor tube  20  to be disposed within, for example, a tubular cannula during implantation into bone. In the illustrated embodiment, the cutouts  55  operate to provide strain relief in the zone of deflection of the fingers  45 . In the illustrated embodiment, four (4) fingers  45  are utilized, although in other embodiments more or fewer than 4 fingers  45  can be present. It will be appreciated that in the various embodiments, the anchor tube  20  includes at least one cutout  55  for each finger  45 . 
         [0037]    In the illustrated embodiment, the insert  25  includes a head  58  and a shank  60  extending longitudinally from the head  58 . As further shown, the insert  25  has a first opening  65  in the head  58 , which further includes a radial shoulder  68 , a second opening  70  in the shank  60 , and a bore  75  extending from the first opening  65  through the second opening  70 . In the illustrated embodiment, the first opening  65  is bordered by a chamfered or radiused edge  80 , and the second opening  70  is bordered by a chamfered or radiused edge  85 . 
         [0038]    As shown, the shank  60  is sized so that it can be inserted into the longitudinal channel  35  of the anchor tube  20 , with the radial shoulder  68  abutting the first end  42  of the anchor tube  20  first portion  40  when fully inserted. In various embodiments, the fit between the shank  60  and the inner surface of the channel  35  is selected to be sufficiently tight to resist movement of the insert  25  relative to the anchor tube  20 . In addition, in the illustrated embodiment, the tabs  57  further operate to engage the insert  25  to further enhance the connection between the insert  25  and the anchor tube  20 . 
         [0039]    As further shown, the bore  75  is configured to receive the suture element  15 , which is configured to be connected to the insert  25 . In the illustrated embodiment, the suture element  15  includes a portion  90  disposed within the bore  75  that further includes a pledget  95  having a diameter greater than the diameter of the bore  75  of the insert, such that the suture element  15  cannot readily be pulled proximately through the bore  75  and separated from the bone anchor assembly  10 . It is emphasized, however, that the particular technique or structure for connecting the suture element  15  to the insert  25  or the bone anchor assembly  10  is not critical to any of the embodiments of the present invention. For example, in lieu of or in addition to the pledget  95 , in various embodiments, a knot, adhesive, or other type of mechanical joining element or technique can be utilized. 
         [0040]    The anchor tube  20  and the insert  25  can be made of any number of structurally suitable biocompatible materials. In various embodiments, the anchor tube  20  can be made of a biocompatible alloy or polymeric material. In various embodiments, the anchor tube  20  is made of a superelastic material such as a nickel titanium alloy (e.g., nitinol). Other exemplary materials include titanium, stainless steel, polyetheretherketone, polycarbonate, and combinations thereof. Similarly, the insert  25 , in various embodiments, can be made of any number of biocompatible, rigid alloys or polymeric materials, such as titanium, stainless steel, polyetheretherketone, polycarbonate, and combinations thereof. In one embodiment, the anchor tube  20  is made of nitinol, and the insert  25  is made of polyetheretherketone. Various other material combinations can be utilized within the scope of the various embodiments. 
         [0041]      FIGS. 3-4  are elevation views showing implantation of the bone anchor assembly  10  using a cannula  96 , according to one embodiment of the present invention. As shown in  FIG. 3 , in one embodiment, the distal end of the cannula  96 , with the bone anchor assembly  10  and suture element  15  disposed therein, is positioned as desired within a bore  98  into the bone  97  at the implantation site. As further shown, when disposed within the cannula  96 , the fingers  45  of the anchor tube  20  are deflected radially inward toward the longitudinal axis  30 . The bore  98  can be formed by any suitable means, e.g., by use of a bone awl or drill. 
         [0042]    As can be seen in  FIG. 4 , the cannula  96  can then be withdrawn proximally to release the bone anchor assembly  10  therefrom. For example, a second delivery cannula or push tube  99  can be inserted into the cannula  96  to abut the bone anchor assembly  10  and hold the bone anchor assembly  10  in position while the cannula  96  is withdrawn proximally from the bore  98 . As further shown in  FIG. 4 , once released from the cannula  96 , the fingers  45  of the anchor tube  20  self-expand radially outwardly to bear against and engage the bone forming the wall of the bore  98  to secure the bone anchor assembly  10  therein (the engagement of the free end  50 , the tip  52  and the edges  54  of the fingers  45  is shown in  FIG. 4 ). Although in  FIGS. 3 and 4  a single bone anchor assembly  10  is shown, in various embodiments, as discussed in greater detail below, additional bone anchor assemblies  10  can be disposed serially within the cannula  96  (or other delivery device). In such embodiments, the plurality of bone anchor assemblies  10  can be incorporated into pre-assembled suture assemblies that can take on a variety of configurations for use in various orthopedic procedures. FIGS.  5 - 10 A&amp;B are schematic illustrations of various fixation element constructs according to various exemplary embodiments of the present invention. 
         [0043]      FIG. 5  is a schematic illustration of a fixation element  100  according to one embodiment. As shown, the fixation element  100  includes a suture assembly  105 , which includes an adjustable suture loop  110 , an adjustable knot  114 , and a proximal suture length  116  used to tighten the suture loop  110 . As further shown, a single bone anchor assembly  10  is slidably coupled to the suture loop  110  by the suture element  15  which is connected to the bone anchor assembly  10  in the manner described above. In the illustrated embodiment, the suture element  15  is in the form of a loop through which the suture material forming the suture loop  110  is passed, thus allowing the bone anchor assembly  10  and suture element  15  to slide along the suture loop  110  as the suture loop is tightened during the particular orthopedic procedure. 
         [0044]      FIG. 6  is a schematic illustration of a fixation element  125 , which as shown includes a suture assembly  130  having an adjustable suture loop  135 , an adjustable knot  140 , and a proximal suture length  142 . As further shown, a pair of bone anchor assemblies  10  are slidably coupled to the suture loop  135  by respective suture elements  15 . Aside from the addition of a second bone anchor assembly  10 , the fixation element  125 , and its constituent components, operates and is constructed in substantially the same or an identical manner as the fixation element  100 . As discussed previously, the fixation element  125  can be pre-loaded into a delivery tool (not shown) with the bone anchor assemblies  10  disposed serially within a delivery cannula, in the manner discussed above with respect to  FIGS. 3 and 4 . 
         [0045]      FIG. 7  is a schematic illustration of an alternative fixation element  150 . In the illustrated embodiment, the fixation element  150  includes a pair of bone anchors  10  and corresponding suture elements  15  similar or identical to those discussed previously herein. As further shown, the fixation element  150  includes three suture assemblies  152 ,  154 ,  156  each including, respectively, adjustable suture loops  160 ,  162  and  164 , which can each be constructed in substantially the same or a similar manner as the suture loops  110  and  130  discussed above. In the illustrated embodiments, the bone anchor assemblies  10  are slidably coupled to the combined suture loops  160 ,  162 ,  164  by their respective suture elements  15 . The combination of the three suture assemblies  152 ,  154 ,  156  provides a robust, high-strength suture construct. 
         [0046]      FIG. 8  is a schematic illustration of another fixation element  175  according to yet another embodiment. As shown in  FIG. 8 , the fixation element  175  includes a suture assembly  180  and bone anchor assemblies  10   a ,  10   b . In the illustrated embodiment, the suture assembly  180  includes an adjustable suture loop  185  and a proximal suture length  190 , which as discussed previously with respect to similar features on other embodiments, can be manipulated to tighten the suture loop  185 . The bone anchor assembly  10   a  is slidably coupled to the suture loop  185 , while the anchor assembly  10   b  is fixedly connected to the suture material making up the suture loop  185  (i.e., cannot slide relative to the suture loop  185 ). In various embodiments, the bone anchor assemblies  10   a ,  10   b  may be disposed, respectively, distally and proximally within a delivery cannula, such that the adjustable bone anchor assembly  10   a  will be deployed first followed by the fixed bone anchor assembly  10   b . In other embodiments, the fixed bone anchor assembly  10   b  will be disposed distally of the slidable bone anchor assembly  10   a  in the delivery tool. The specific configuration and orientation of the respective bone anchor assemblies  10   a ,  10   b  can be varied depending on the particular orthopedic procedure in which the fixation element  175  is used. 
         [0047]      FIG. 9  is a schematic illustration of a fixation element  200  according to one embodiment. As shown, the fixation element  200  includes a suture assembly  205 , which includes an adjustable suture loop  210 , an adjustable knot  214 , and a proximal suture length  216  used to tighten the suture loop  210 . As further shown, a single bone anchor assembly  10  is slidably coupled to the suture loop  210  by the suture element  15  which is connected to the bone anchor assembly  10  in the manner described above. As further shown, the fixation element  200  includes a tissue anchor assembly  218  coupled to the suture loop  210 . In the illustrated embodiment, the tissue anchor assembly  218  includes a tissue anchor  220  and a suture element  222 , which as shown is in the form of a loop through which the suture material forming the suture loop  210  is passed, thus allowing the tissue anchor assembly  218  to slide along the suture loop  210  as it is tightened. In various embodiments, either the bone anchor assembly  10  or the tissue anchor assembly  218  can be fixedly connected to the suture loop  210  in lieu of the slidable coupling arrangement shown. The tissue anchor assembly  218  is configured to be secured to soft tissues (e.g., connective tissue, muscle, or fascia). In various embodiments, the tissue anchor  220  can be formed by a variety of suitable, rigid or semi-rigid polymeric or metallic materials (e.g., polyetheretherketone, PET, titanium, and the like). 
         [0048]      FIGS. 10A-10B  are schematic illustrations of a fixation element  225  according to yet another embodiment of the present invention. As shown, the fixation element  225  includes a suture assembly  230 , which includes an adjustable suture loop  235  and an adjustable knot  240 . A bone anchor assembly  10  is slidably coupled to the suture loop  235 , and a tissue anchor  250  is coupled to the suture loop  235  opposite the adjustable knot  240 . The tissue anchor  250  is constructed of suture material, and is formed by passing the suture material forming the suture loop  235  through the suture material of the tissue anchor  250  at multiple locations along the length of the tissue anchor  250 . In use, when the suture loop  235  is tightened with the tissue anchor  250  bearing against the tissue to which it is to be secured, the tissue anchor  250  will tend to bunch up and laterally expand, thereby assuming a deployed configuration in which it will bear against the tissue without passing therethrough.  FIG. 10A  shows the tissue anchor  250  in its initial, undeployed state, while  FIG. 10B  shows the tissue anchor  250  in its laterally expanded deployed state. 
         [0049]      FIG. 11  is an alternative bone anchor assembly  300  according to yet another embodiment of the present invention. As shown in  FIG. 11 , the bone anchor assembly  300  includes a pair of anchor tubes  310   a ,  310   b  oriented in opposite directions from one another. Each of the anchor tubes  310   a ,  310   b  can be configured in substantially the same or an identical way to the anchor tube  20  of the bone anchor assembly  10 . As such, the anchor tube  310   a  includes at least one tab  315   a  and plurality of radially deflectable fingers  320   a , corresponding to the tab  57  and the fingers  45  of the anchor tube  20 . Similarly, the anchor tube  310   b  includes at least one tab  315   b  and a plurality of deflectable fingers  320   b , also corresponding to the tab  57  and the fingers  45  of the anchor tube  20 . As further shown, the bone anchor assembly  300  includes an elongated insert  325  having a head  330 , a shank  332  extending longitudinally from the head  330 , and a plurality of serrations  335  on a portion of the shank  332 . As further shown, shank  332  is disposed within the tubular anchor tubes  310   a ,  310   b . In the illustrated embodiment, the anchor tube  310   a  is slidable along the shank  332  with the head  330  of the shank  332  delimiting movement of the anchor tube  310   a  due to the diameter of the head  330  being greater than the inner diameter of the anchor tube  310   a.    
         [0050]    As further shown, the anchor tube  310   b  is disposed along the length of the shank  332  including the serrations  335 , and is oriented with its fingers  320   b  facing the fingers  320   a  of the anchor tube  310   a . As can be seen in  FIG. 11 , each serration includes a surface extending at an oblique angle with respect to the longitudinal axis of the bone anchor assembly  300 , and another surface extending generally orthogonal to the longitudinal axis and oriented generally toward the head  330  of the insert  325 . Due to the relative orientations of the anchor tubes  310   a ,  310   b , the shank  332  can be pulled through the anchor tube  310   b  so as to urge the anchor tubes  310   a ,  310   b  toward one another (thus applying tension between two bones or bone regions in which the anchor tubes  310   a ,  310   b  are embedded. At the same time, reverse movement of the shank  332  is inhibited by engagement of the tab(s)  315   b  with the serration surface oriented orthogonally to the longitudinal axis. This arrangement allows a desired amount of tension to be maintained between the bones or bone regions to which the anchor tubes  310   a ,  310   b  are secured. In the various embodiments, the anchor tubes  310   a ,  310   b  and the shank  332  can be made of substantially the same or identical materials as the anchor tube  20  and the insert  25  of the bone anchor assembly  10 . 
         [0051]      FIG. 12  is an alternative bone anchor assembly  350  according to yet another embodiment of the present invention. As shown in  FIG. 12 , the bone anchor assembly  350  includes a pair of anchor tubes  360   a ,  360   b  oriented in opposite directions from one another and each including, respectively, at least one tab  365   a ,  365   b , and a plurality of deflectable fingers  362   a ,  362   b  disposed such that the fingers  362   a  are oriented toward the fingers  362   b . As further shown, in the illustrated embodiment, the anchor tube  360   b  further includes a plurality of deflectable fingers  363   b  positioned opposite the fingers  362   b , and thus oriented in the same general direction as the fingers  362   a  of the anchor tube  360   a . The bone anchor assembly  350  further includes an insert  370  having a head  375  and a shank including a plurality of serrations  380 . The insert  370  extends through the anchor tubes  360   a ,  360   b , and the head  375  and the serrations operate in the same manner as the corresponding features of the bone anchor assembly  300  discussed previously. 
         [0052]      FIG. 13  is a schematic illustration of a bone anchor assembly  400  according to another embodiment of the present invention. As shown, the bone anchor assembly  400  includes a pair of anchor tubes  410   a ,  410   b  oriented in opposite directions from one another. Each of the anchor tubes  410   a ,  410   b  can be configured in substantially the same or an identical way to the anchor tube  20  of the bone anchor assembly  10 . As such, the anchor tube  410   a  includes at least one tab  415   a  and plurality of radially deflectable fingers  420   a , corresponding to the tab  57  and the fingers  45  of the anchor tube  20 . Similarly, the anchor tube  410   b  includes at least one tab  415   b  and a plurality of deflectable fingers  420   b , also corresponding to the tab  57  and the fingers  45  of the anchor tube  20 . As further shown, the bone anchor assembly  400  includes an elongated insert  425  having a head  428 , and a shank extending longitudinally from the head  428 . The particular shank shown includes a bend  430  at a predetermined location along its length. The bend  430  in the shank provides enhanced flexibility in orienting the bone anchor assembly  400  to provide the desired effect. In various embodiments, the insert  425  can also include serrations (not shown) along its length, similar or identical to the inserts of the bone anchor assemblies previously described. In addition, in some embodiments, the anchor tube  410   b  can be configured in substantially the same or an identical manner as the anchor tube  360   b  discussed above (e.g., with two arrangements of deflectable fingers extending in opposite directions from one another). 
         [0053]      FIG. 14  is a schematic illustration of a model of the skeletal system of a human hand  500  showing exemplary therapeutic applications of various embodiments of the present invention. As shown in  FIG. 14  at  510 , in one exemplary embodiment, a bone anchor assembly  350  can be deployed in combination with a bone anchor/suture assembly—in this case the fixation element  225 , in a procedure to repair the carpal metacarpal (CMC) joint. In such an embodiment, a plurality of bone bores can be formed into or through the bones and the bone anchor assembly  360  and the fixation element  225  can be deployed through such bone bores using a suitable delivery tools and techniques, and thereafter tightened to complete the desired orthopedic procedure. 
         [0054]    In another example, as further shown in  FIG. 14 , one of the bone anchor assemblies  350  can also be utilized to accomplish or facilitate fusion of the metacarpophalangeal (MCP) joint  520 , the proximal interphalangeal (PIP) joint  530  and/or the distal interphalangeal (DIP) joint  540 . In these embodiments, a bone bore can be formed across the respective joints  520 ,  530 ,  540  and the bone anchor assembly  350  deployed across the joint through this bore as shown in  FIG. 14 . In various embodiments, once the bone anchor assembly  350  is inserted into and across the respective joint  520 ,  530 ,  540  and the corresponding anchor tubes embedded in the respective bone masses, the insert of the bone anchor assembly  350  can be pulled proximally so as to urge the anchor tubes toward one another thereby accomplishing or aiding in fixation of the joint  520 ,  530  or  540 . It will be appreciated that, in other embodiments, one or more of the additional bone anchor assemblies and/or fixation elements described herein can also be advantageously in the same or similar orthopedic procedures. 
         [0055]      FIG. 15  is a schematic illustration of a model of the skeletal system of a human foot  600  illustrating additional exemplary therapeutic applications of various embodiments of the present invention. As shown in  FIG. 15  at  610 , one or more bone anchor assemblies  350  can be deployed in the bones of the foot  600  in combination with one or more additional anchor/suture assemblies, in this case, the fixation element  225 , in hallux valgus and/or hammertoe repair procedures. As further shown in  FIG. 15 , the bone anchor assembly  350  can also be utilized to accomplish or facilitate fusion of the proximal interphalangeal (PIP) joint  620  and/or the distal interphalangeal (DIP) joint  630  of the foot  600 . In these embodiments, a bone bore can be formed across the respective joints  620 ,  630  and the bone anchor assembly  350  deployed across the joint through this bore. In various embodiments, once the bone anchor assembly  350  is inserted into and across the respective joint  620 ,  630  and the corresponding anchor tubes embedded in the respective bone masses, the insert of the bone anchor assembly  350  can be pulled proximally so as to urge the anchor tubes toward one another thereby accomplishing or aiding in fixation of the joint  620  or  630 , as the case may be. It will be appreciated that, in other embodiments, one or more of the additional bone anchor assemblies and/or fixation elements described herein can also be advantageously in the same or similar orthopedic procedures. 
         [0056]    Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.