Patent Publication Number: US-2021161676-A1

Title: Talar dome with angled holes

Description:
BACKGROUND 
     An ankle joint may become severely damaged and painful due to arthritis, prior ankle surgery, bone fracture, osteoarthritis, and/or one or more additional conditions. Options for treating the injured ankle have included anti-inflammatory and pain medications, braces, physical therapy, joint arthrodesis, and total ankle replacement. 
     Total ankle replacement generally comprises two components—one component coupled to the tibia and one component coupled to the talus. The components comprise articulation surfaces sized and configured to mimic the range of motion of the ankle joint. For example, the talar portion may comprise a component sized and configured to mimic the talar dome and the tibial portion may comprise an articulation surface configured to mimic articulation of the tibia. 
     SUMMARY 
     In various embodiments, a talar implant is disclosed. The talar implant includes a plate having an inferior surface configured for attachment to a talus. The plate has a post projecting from a superior surface of the plate and includes at least one threaded hole. A talar dome having an inferior surface is configured to face the plate and an opening in the inferior surface is shaped to receive the post. The talar dome includes at least one through hole having a threaded surface and a groove. The groove has a larger outer diameter than the threaded surface. At least one fastener is configured to engage the threaded hole of the post and the threaded surface of the through hole. The at least one fastener has a groove that is aligned with the groove of the through hole when the fastener is inserted in the talar dome and the post. At least one clip is configured to engage the groove of the through hole of the talar dome and the groove of the fastener. 
     In various embodiments, an ankle prosthesis is disclosed. The ankle prosthesis includes a tibial component configured for attachment to a tibia of a person, a plate having an inferior surface configured for attachment to a talus of the person, and a talar dome. The plate includes a post projecting from a superior surface of the plate and defines first and second threaded holes. The talar dome includes an articulating surface configured to face the tibial component, an inferior surface configured to face the plate, and an opening in the inferior surface shaped to receive the post. The talar dome defines first and second through holes having respective first and second threaded surfaces with a diameter and first and second grooves, respectively. The first and second grooves have an outer diameter larger than the diameter of the first and second threaded surfaces. First and second fasteners are configured to engage the first and second threaded holes, and the first and second threaded surfaces of the talar dome, respectively. The first and second fasteners each have a groove that is aligned with the first and second grooves of the talar dome, respectively, when the first and second fasteners are inserted in the talar dome and the post. First and second clips are configured to engage the first and second grooves of the first and second through holes and the first and second grooves of the first and second fasteners, respectively. 
     In various embodiments, a method of inserting a talar implant is disclosed. The method includes attaching a plate to a talus so that an inferior surface of the plate abuts the talus. The plate includes a post projecting from a superior surface of the plate. The post includes at least one threaded hole. The method further includes placing a talar dome over the plate, so that an inferior surface of the talar dome abuts the plate, and an opening in the inferior surface of the talar dome receives the post, the talar dome having at least one through hole. The through hole includes a threaded surface and a groove. At least one fastener is inserted through the threaded surface of the through hole to engage the threaded hole of the post. The fastener includes a groove. At least one clip is inserted in the through hole, so as to engage the groove of the through hole of the talar dome and the groove of the fastener. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the present invention will be more fully disclosed in, or rendered obvious by the following detailed description of the preferred embodiments, which are to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
         FIG. 1  illustrates an anatomic view of an ankle joint. 
         FIG. 2  illustrates one embodiment of an ankle joint having a total ankle replacement system therein, in accordance with some embodiments. 
         FIG. 3  illustrates a top view of a talar implant including a talar dome and a talar plate, in accordance with some embodiments. 
         FIG. 4  illustrates a side perspective view of the talar implant of  FIG. 3 , in accordance with some embodiments. 
         FIG. 5  illustrates a side view of the talar implant of  FIG. 3 , in accordance with some embodiments. 
         FIG. 6  illustrates a cross-sectional view of the talar implant taken along line  6 - 6  in  FIG. 5 , in accordance with some embodiments. 
         FIG. 7  illustrates a top perspective view of a talar dome defining at least one through hole, in accordance with some embodiments. 
         FIG. 8  illustrates a side view of the talar dome of  FIG. 7 , in accordance with some embodiments. 
         FIG. 9  illustrates a bottom view of the talar dome of  FIG. 7 , in accordance with some embodiments. 
         FIG. 10  illustrates a cross-sectional view of the talar dome taken along line  7 - 7  in  FIG. 9 , in accordance with some embodiments. 
         FIG. 11  illustrates a top view of a talar plate including a post configured to be coupled to a talar dome, in accordance with some embodiments. 
         FIG. 12  illustrates a side view of the plate of  FIG. 11 , in accordance with some embodiments. 
         FIG. 13  illustrates a fastener sized and configured to be inserted into a through hole of a talar dome, in accordance with some embodiments. 
         FIG. 14  illustrates a clip configured to be coupled to a fastener, in accordance with some embodiments. 
         FIG. 15  illustrates a cross-sectional view of the clip taken along line  15 - 15  in  FIG. 14 , in accordance with some embodiments. 
         FIG. 16  illustrates a C clip configured to be coupled to a fastener, in accordance with some embodiments. 
         FIG. 17  illustrates a cross-sectional view of a talar implant including a plate, talar dome, screw, and clip, in accordance with some embodiments. 
         FIG. 18  illustrates the talar implant of  FIG. 17  with the screw inserted into the talar dome and the post of the talar plate, in accordance with some embodiments. 
         FIG. 19  illustrates a method of installing a talar implant, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “proximal,” “distal,” “above,” “below,” “up,” “down,” “top” and “bottom,” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. 
     In various embodiments, a talar implant is disclosed. The talar implant includes a plate having an inferior surface configured for attachment to a talus. The plate has a post projecting from a superior surface of the plate and includes at least one threaded hole. A talar dome having an inferior surface is configured to face the plate and an opening in the inferior surface is shaped to receive the post. The talar dome includes at least one through hole having a threaded surface and a groove. The groove has a larger outer diameter than the threaded surface. At least one fastener is configured to engage the threaded hole of the post and the threaded surface of the through hole. The at least one fastener has a groove that is aligned with the groove of the through hole when the fastener is inserted in the talar dome and the post. At least one clip is configured to engage the groove of the through hole of the talar dome and the groove of the fastener. 
       FIG. 1  illustrates an anatomic view of an ankle joint  2 . The ankle joint  2  comprises a talus  4  in contact with a tibia  6  and a fibula  8 . A calcaneus  10  is located adjacent to the talus  4 . In total ankle replacements, the talus  4  and the tibia  6  may be resected, or cut, to allow insertion of a talar implant and a tibial implant.  FIG. 2  illustrates the ankle joint  2  of  FIG. 1  having a total ankle replacement system  12  inserted therein. 
     The total ankle replacement system  12  comprises a talar implant  14  and a tibial implant  18 . The talar implant  14  includes a talar dome having a body defining a talar articulation surface  16 . The talar implant  14  includes a plate coupled to the talus by one or more fasteners (not shown). The tibial implant  18  is sized and configured for installation into the tibia  6 . The tibial implant  18  comprises a body having an articulation surface  20  and, in some embodiments, a tibial stem  24  extending into the tibia  6  to anchor the tibial implant  18 . The talar joint surface  16  and the tibial joint surface  20  are mutually sized and configured to articulate. The joint surfaces  16 ,  20  replace the natural ankle joint surfaces, which are removed, to restore a range of motion that mimics the natural joint. One or more holes may be formed in the tibia and/or the talus prior to and during insertion of the tibial implant  18  or the talar implant  12 . For example, in some embodiments, a hole is drilled starting in the bottom of the talus, extending through the talus and into the tibia. The hole may comprise, for example, a 6 mm hole configured to receive the stem  24  of the tibial implant  18 . 
     The joint surfaces  16 ,  20  may be made of various materials, such as, for example, polyethylene, high molecular weight polyethylene (HMWPE), rubber, titanium, titanium alloys, chrome cobalt, surgical steel, and/or any other suitable metal, ceramic, sintered glass, artificial bone, and/or any combination thereof. The joint surfaces  16 ,  20  may comprise different materials. For example, the tibial joint surface  20  may comprise a plastic or other non-metallic material and the talar joint surface  16  may comprise a metal surface. Those skilled in the art will recognize that any suitable combination of materials may be used. 
       FIGS. 3-6  illustrate a talar implant  100  including a talar dome  110  and a talar plate  120 , in accordance with some embodiments. The talar plate  120  includes a body  122  extending between an inferior surface  124  and a superior surface  126  and defined by a perimeter wall  128 . The inferior surface  124  is sized and configured to contact a resected talus. For example, the inferior surface  124  may comprise a planar surface, a concave surface, and/or any desirably shaped surface configured to rest on the surface of a resected (or partially-resected) talus. In the illustrated embodiment, the inferior surface  124  includes a planar surface. 
       FIGS. 11-12  illustrate one embodiment of a talar plate  120   a,  in accordance with some embodiments. The body  122  defines a plurality of fastener holes  125  extending through the body  122  from the superior surface  126  to the inferior surface  124 . The fastener holes  125  are sized and configured to receive a fastener therethrough to couple the talar plate  120  to a resected talus. In some embodiments, the fastener holes  125  are configured to receive a fastener at a variable angle with respect to a central axis of each of the fastener holes  125 . In other embodiments, one or more fastener holes  125  are omitted and/or alternative or additional attachment mechanisms may be included, such as fixed pegs, spikes, and/or any other suitable attachment mechanism. 
     With reference now to  FIGS. 3-6 and 11-12 , in some embodiments, a post  130  extends from the superior surface  126  of the talar plate  120 . The post  130  extends a predetermined distance above the superior surface  126 . In the illustrated embodiment, the post  130  extends substantially perpendicular to the planar superior surface  126 , although it will be appreciated that the post  130  can extend from the superior surface  126  at any suitable angle, such as, for example, an angle substantially between  45  and  90  degrees. The post  130  can include any suitable shape, such as, for example, a geometric (e.g., circular, cuboid, hexagonal, octagonal, etc.) or non-geometric shape. The post  130  may be formed integrally with the talar plate  120  and/or may be coupled to the talar plate  120  using any suitable coupling mechanism, such as a screw, pin, or other fastener. 
     In some embodiments, the post  130  defines one or more fastener holes  132   a,    132   b  extending from an outer surface  134  of the post  130  at least partially into the post  130 . Each of the one or more fastener holes  132   a,    132   b  is sized and configured to receive a distal portion of a fastener, such as a screw, therein, as discussed in greater detail below. Each fastener hole  132   a ,  132   b  extends into the post  130  at a first angle with respect to a plane defined by one or more surfaces of the talar plate  120 , such as, for example, a plane defined by the inferior surface  124 , the superior surface  126 , a distal end of the post  130 , and/or any other suitable surface. 
     In some embodiments, the post  130  defines a central vertical axis  152  and each of the holes  132  extend into the post  130  such that a longitudinal axis of the hole  132  does not extend through the central vertical axis  152  of the post  130 . For example, in some embodiments, a longitudinal axis of each of the holes  132   a,    132   b  is offset or off-center within the post  130 . The combination of the first angle and the offset may be referred to herein as a compound angle. 
     In some embodiments, each of the fastener holes  132   a,    132   b  include an internal threading  136  configured to couple the post  130  to a distal portion of a threaded screw, as discussed in greater detail below. The fastener holes  132   a,    132   b  may have similar and/or different internal threading. In some embodiments, the internal threading  136  is omitted and a fastener is coupled to the post  130  using an additional and/or alternative coupling mechanism, such as a cross-pin, an adhesive, and/or any other suitable coupling mechanism. 
       FIGS. 7-10  illustrate one embodiment of a talar dome  110   a.  With reference now to  FIGS. 3-10 , the talar dome  110 ,  110   a  includes a body  112  extending between a superior articulation surface  114  and an inferior plate contact surface  116 . The body  112  has a predetermined thickness between the articulation surface  114  and the plate contact surface  116 . The predetermined thickness can be constant and/or variable. The articulation surface  114  is sized and configured to interface with an opposing articulation surface of an opposing implant and/or bone structure. For example, in one embodiment, the articulation surface  114  is sized and configured to interface with an articulation surface of a tibial implant, such as, for example, the tibial implant  18  shown in  FIG. 2 . In another example, the articulation surface  114  is sized and configured to interface with an articulation body located between a tibial implant  18  and the talar dome  110 ,  110   a,  such as, for example, a poly insert defining an articulation surface. 
     In some embodiments, the plate contact surface  116  comprises a surface configured to contact a superior surface  126  of the talar plate  120 . The plate contact surface  116  includes a surface complimentary to the superior surface  126  of the talar plate  120 , such as, for example, a planar surface, concave surface, convex surface, etc. For example, in the illustrated embodiment, the plate contact surface  116  and the superior surface  126  each include generally planar surface. In various embodiments, the plate contact surface  116  can include dimensions that are greater than, less than, or equal to the dimensions of the superior surface  126  of the talar plate  120 , such that the talar dome  110 ,  110   a  may extend less than, up to, and/or beyond the peripheral edge  128  of the talar plate  120 . 
     In some embodiments, the talar dome  110 ,  110   a  defines a post hole  118  extending from the plate contact surface  116  into the body  114  of the talar dome  110 ,  110   a.  The post hole  118  is sized and configured to receive the post  130  of the talar plate  120  therein. The post hole  118  has a complimentary cross-sectional shape with respect to the post  130 . For example, in some embodiments, post  130  defines a substantially geometric shape, such as, for example, a circle, square, hexagon, octagon, etc., and the post hole  118  defines a complimentary substantially geometric cross-section. In some embodiments, the post hole  118  and the post  130  include complimentary shapes configured to allow insertion of the post  130  into the post hole  118  only when the talar dome  110 ,  110   a  and the talar plate  120  are arranged in one or more predetermined alignments. For example, in some embodiments, the post  130  may define a trapezoidal shape such that the post  130  fits into the complimentary post hole  118  only when the short side of the post  130  is aligned with a short side of the post hole  118 . Although specific examples are discussed herein, it will be appreciated that the post hole  118  and/or the post  130  can have any suitable shape and are within the scope of this disclosure. 
     In some embodiments, the post hole  118  includes a depth sufficient to receive the entire post  130  therein such that the plate contact surface  116  of the talar dome  110 ,  110   a  sits flush against the superior surface  126  of the talar plate  120 . The post  130  may have a diameter such that a partial friction fit exists between the post hole  118  and the post  130  requires a force, such as a force applied by one or more fasteners to position the talar dome  110 ,  110   a  flush with the superior surface  126  of the talar plate  120 . 
     The talar dome  110 ,  110   a  includes one or more through holes  140   a,    140   b  each extending along a respective longitudinal axis  146   a,    146   b  from the articulation surface  114  through an interior wall  142  of the post hole  118 . The through holes  140   a,    140   b  are sized and configured to receive a fastener therein (see  FIG. 6 ). In some embodiments, each through hole  140   a,    140   b  includes an internal thread  144  extending over at least a portion of the through hole  140   a,    140   b.  The internal thread  144  is configured to couple a portion of a fastener, such as a screw, to the talar dome  110 . In some embodiments, the internal thread  144  is substantially similar to the internal thread  136  of one or more holes  132  formed in the post  130  such that a fastener having a single thread can interact with each of the threads  136 ,  144  in each of a through hole  140   a,    140   b  in a talar dome  110  and a fastener hole  132   a,    132   b  in a post  130 . 
     In some embodiments, the longitudinal axis  146   a,    146   b  of each of the through holes  140   a,    140   b  extends through the talar dome  110 ,  110   a  at an oblique angle with respect to the plate contact surface  116  of the talar dome  110  and/or an oblique angle with respect to an axis extending from an anterior edge  129   a  of the body  112  to a posterior edge  129   b  of the body  112 . For example, and as shown in  FIG. 9 , in some embodiments, each of the through holes  140   a,    140   b  have an opening  148   a,    148   b  in the articulation surface  114  that is offset in a posterior direction with respect to an opening  150   a,    150   b  formed in the interior wall  142  of the post hole  118 . Similarly, and as shown in  FIG. 10 , in some embodiments, the opening  148   a,    148   b  of each through hole  140   a,    140   b  formed in the articulation surface  114  is positioned in a superior direction with respect to the holes  150   a,    150   b  formed in the interior wall  142  of the post hole  118 . Although embodiments are discussed herein with specific positions of the openings  148   a ,  148   b,    150   a,    150   b,  it will be appreciated that the superior/inferior, anterior/posterior, and/or medial/lateral position of each of the through holes  140   a,    140   b  may be adjusted. 
     In some embodiments, each of the through holes  140   a,    140   b  includes a first portion  152   a,    152   b  having a first diameter and a second portion  154   a,    154   b  having a second diameter that is equal to or less than the first diameter. The first portion  152   a,    152   b  of each of the respective through holes  140   a,    140   b  is sized and configured to receive a head portion of a fastener and the second portion  154   a,    154   b  is sized and configured to receive a shaft or coupling portion of the fastener therein (as discussed in greater detail with respect to  FIGS. 17-18 ). 
     In some embodiments, each of the through holes  140   a,    140   b  defines a groove  156   a,    156   b  extending at least partially circumferentially about the respective through hole  140   a ,  140   b.  Each of the grooves  156   a,    156   b  includes an outer diameter larger than the first diameter and/or the second diameter of the through holes  140   a,    140   b.  In the illustrated embodiment, each of the grooves  156   a,    156   b  are positioned circumferentially about a first portion  152   a,    152   b  of each of the respective through holes  140   a,    140   b  and include an outer diameter greater than the first diameter of the through holes  140   a,    140   b,  although it will be appreciated that the grooves  156   a - 156   b  can be located circumferentially about the second portion  154   a,    154   b  of each through hole  140   a,    140   b  and can have a diameter greater than the second portion  154   a,    154   b  but less than the first portion  152   a,    152   b.  Each groove  156   a,    156   b  is sized and configured to receive a clip therein, as discussed in greater detail below. 
     The through holes  140   a,    140   b  in the talar dome  110 ,  110   a  are configured to align with the fastener holes  132   a,    132   b  formed in the post  130  when the post  130  is inserted into the post hole  118  and the talar dome  110 ,  110   a  is properly aligned with the talar plate  120 . For example, in some embodiments, a central longitudinal axis of each of the through holes  140   a ,  140   b  is aligned with a central longitudinal axis of each of the fastener holes  132   a,    132   b  in the post  130  when the post  130  is inserted into the post hole  118 . As discussed above, in some embodiments, the post hole  118  and/or the post  130  include a geometry configured to allow insertion of the post  130  into the post hole  118  only in a predetermined alignment. The predetermined alignment corresponds to the through holes  140   a,    140   b  and the post holes  132  being aligned. In other embodiments, the talar dome  110 ,  110   a  can rotate at least partially on the post  130  to allow the through holes  140   a,    140   b  to be brought into alignment with the fastener holes  132   a,    132   b.    
     As illustrated in  FIGS. 4-6 , in some embodiments, one or more fasteners  160   a ,  160   b  are sized and configured to be inserted into the through holes  140   a,    140   b  and the fastener holes  132   a,    132   b.    FIG. 13  illustrates one embodiment of a fastener  160   c,  in accordance with some embodiments. Each fastener  160   a - 160   c  is configured to engage the threads  136  of a respective fastener hole  132   a,    132   b  and/or the threads  144  of a respective through hole  140   a ,  140   b.    
     Each fastener  160   a - 160   c  includes a head  162  having a first diameter and a shaft  164  coupled to and extending from the head  162 . The shaft  164  extends substantially along a longitudinal axis from a first end  161   a  located adjacent to the head  162  to a second end  161   b  and has a second diameter. The first diameter of the head  162  may be greater than, less than, or equal to the second diameter of the shaft  164 . The first diameter of the head  162  may be substantially equal to or slightly smaller than the diameter of the first portion  152   a,    152   b  of the through holes  140   a,    140   b  and the second diameter may be substantially equal to or slightly smaller than diameter of the second portion  154   a,    154   b  of a through hole  140   a,    140   b.  In some embodiments, the head  162  defines a tool cavity  166  extending from the first end  161   a  into the head  162 . The tool cavity  166  is sized and configured to receive a driving tool therein. 
     In some embodiments, each fastener  160   a - 160   c  includes a groove  168  sized and configured to receive a clip therein. The groove  168  may be formed at least partially circumferentially about the head  162  of the fastener  160   a - 160   c.  Although embodiments are illustrated with a curved (or circular) circumferential groove  168 , it will be appreciated that the circumferential groove  168  can include any suitable shape, such as, for example, circular, hexagonal, etc. In some embodiments, the groove  168  is positioned on the head  162  such that the groove  168  is aligned with the groove  154   a,    154   b  of a respective through hole  140   a,    140   b  when the fastener  160   a - 160   c  is fully inserted into a through hole  140   a,    140   b  and a fastener hole  132   a,    132   b.    
     As illustrated in  FIGS. 4-6 , in some embodiments, a clip  180   a,    180   b  is coupled to each of the fasteners  160   a,    160   b.    FIGS. 14-15  illustrate one embodiment of a clip  180   c  including a retaining ring, in accordance with some embodiments.  FIG. 16  illustrates one embodiment of a C clip  180   d,  in accordance with some embodiments. Each clip  180   a - 180   d  is sized and configured to be received at least partially within a groove  168  of a fastener  160   a - 160   c  and/or a groove  156   a,    156   b  of a through hole  140   a,    140   b.    
     In some embodiments, a clip  180   a - 180   d  is configured to be coupled to a fastener  160   a - 160   c  prior to coupling the fastener  160   a - 160   c  to a talar implant  100 . The clip  180   a - 180   d  is inserted into the groove  166  formed in the head  162  of the fastener  160   a - 160   c.  In some embodiments, the clip  180   a - 180   d  includes at least one chamfer. For example, in some embodiments, a first side  182  of the clip can include a first chamfer configured to interact with a circumferential inner wall of a through hole  140   a,    140   b.  In some embodiments, a clip  180   d  can include a first chamfer on a top surface and a second chamfer on a bottom surface. As discussed in greater detail below, in some embodiments, the clip  180   a - 180   d  is configured to prevent removal of a fastener  160   a - 160   c  from a talar dome  110 ,  110   a.    
       FIGS. 17-18  illustrate a process of coupling a talar dome  110   b  to a talar plate  120   b  using a first fastener  160   d,  in accordance with some embodiments.  FIG. 19  is a flowchart illustrating a method  200  of inserting a talar implant  100   a,  in accordance with some embodiments. The talar dome  110   b,  talar plate  120   b,  and fastener  160   d  are similar to the talar domes  110 ,  110   a,  talar plates  120 ,  120   a,  and fasteners  160   a - 160   c  previously described and similar description is not repeated herein. 
     At step  202 , the talar plate  120   b  is attached to a talus. For example, in some embodiments, the talar plate  120   b  can be coupled to a talus having a resected surface formed specifically for insertion of the talar plate  120   b  and/or during a prior ankle revision surgery. The talar plate  120   b  is inserted such that the inferior surface  126  of the talar plate  120   b  abuts the talus. At step  204 , a talar dome  110   b  is placed over the talar plate  120   b.  The talar dome  110   b  is positioned such that the inferior surface  116  of the talar dome  110   b  abuts the superior surface  114  of the talar plate  120   b.  The post hole  118  formed in the inferior surface  116  of the talar dome  110   b  receives the post  130  of the talar plate  120   b.  In some embodiments, the talar dome  110   b  is positioned over the talar plate  120   b  without applying an impact force. 
     At step  206 , a clip  180   e  is coupled to a fastener  160   d.  The clip  180   e  is sized and configured to be received within a groove  166  defined about at least a portion of the circumference of the head  162  of the fastener  160   d.  In some embodiments, the clip  180   e  can include a C clip and/or a retaining ring. At step  208 , the fastener  160   d  is inserted into the through hole  140   a  to engage a threaded fastener hole  132   a  formed in the post  130  of the talar plate  120   b.  The threads  170  of the fastener  160   d  couple to the threads  136  of the fastener hole  132   a.  In some embodiments, the through hole  140   a  includes threads  146  configured to engage a portion of the threads  170  of the fastener  160   d.    
     At step  210 , the fastener  160   d  is fully inserted into the through hole  140   d  such that the head  162  of the fastener  160   d  is flush with and/or recessed beneath the articulation surface  114  of the talar dome  110   b.  When the fastener  160   d  is inserted into the through hole  140   a,  the clip  180   e  is compressed into the groove  168  by a force applied by the through hole  140   a.  In some embodiments, a chamfer formed on one or more surfaces of the clip  180   e  facilitate compression of the clip  180   e  by the wall of the through hole  140   a.  The clip  180   e  remains compressed in the groove  166  until the fastener  160   d  is fully inserted into the through hole  140   a.  At step  212 , when the groove  166  in the fastener  160   d  is aligned with the groove  156  in the through hole  140   a,  the clip  180   e  expands from a compressed state to a partially compressed and/or uncompressed state. A portion of the clip  180   e  is positioned in the groove  156  and a portion of the clip  180   e  remains in the groove  166  of the fastener  160   d.  The clip  180   e  applies an additional force to maintain the fastener  160   d  in a fixed position with respect to the talar dome  110   b  and the talar plate  120   b.    
     In some embodiments, and as discussed above, the through hole  140   a  and/or the fastener hole  132   a  can include longitudinal axes oriented at an oblique angle with respect to an inferior surface  116  of the talar dome  110   b  and/or can be offset from a central vertical axis of the post  130  such that the longitudinal axes do not extend through the central vertical axis of the post  130 . In such embodiments, when the fastener  160   d  is inserted into the through hole  140   a  and the fastner hole  132   a,  a longitudinal axis of the fastener  160   d  is oriented at an oblique angle with respect to the inferior surface  116  of the talar dome  110   b  and/or does not extend through the central vertical axis of the post  130 . Steps  206 - 210  may be repeated for one or more additional fasteners, although it will be appreciated that a single fastener  160   d  may be used in some embodiments. 
     Although the subject matter has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments, which may be made by those skilled in the art.