Abstract:
The invention is a subtalar implantable to expand after implantation. The subtalar implant has two or more expansion segments or wings. In all forms, the expansion wings are hinged on the distal portion of the subtalar implant which causes only the proximal portion of the wing to expand relative to the midplane of the implant. The expansion wings and the entire subtalar implant are threaded to prevent the implant from backing out of the sinus tarsi once implanted. In one form, the subtalar implant includes an integral expansion screw that, when rotated, expands the expansion wings. In another form, the subtalar implant includes a separate expansion screw that, when rotated, expands the expansion wings. The integral and the separate expansion screw includes a socket that accepts a like driver tool for rotating the expansion screw and expanding the expansion wings.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This U.S. non-provisional patent application claims the benefit of and/or priority under 35 U.S.C. §119(e) to U.S. provisional patent application Ser. No. 62/214,883 filed Sep. 4, 2015 titled “Subtalar Implants,” and U.S. provisional patent application Ser. No. 62/259,938 filed Nov. 25, 2015, titled “Subtalar Implant,” the entire contents of each of which is specifically incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to orthopedic implants for the foot and, particularly, to subtalar implants. 
       BACKGROUND OF THE INVENTION 
       [0003]    There are various issues that can arise with respect to the bones of the foot. Such issues can be a congenital or acquired deformity or abnormality of one or more bones of the foot, a disease or trauma affecting one or more bones of the foot, or other foot bone issue. While some conditions or issues can be alleviated without surgery, other issues respond better to surgery. In some cases, surgery may include installing an orthopedic implant. 
         [0004]    Arthroereisis (also referred to as arthroisis) is a limitation of excessive movement across a bone joint of the foot. Subtalar arthroereisis is designed to correct excessive talar displacement and calcaneal eversion by reducing pronation across the subtalar joint. Extraosseous talotarsal stabilization is also being evaluated as a treatment of talotarsal joint dislocation. It is performed by placing an implant in the sinus tarsi, which is a canal located between the talus and the calcaneous. 
         [0005]    While numerous implants have been developed over the years to correct excessive talar displacement and calcaneal eversion, they are deficient in many respects. It is therefore an object of the present invention to provide a subtalar implant that overcomes the deficiencies of the prior art. 
       SUMMARY OF THE INVENTION 
       [0006]    The invention is a subtalar implant that is able to expand after implantation into the sinus tarsi in order to correct excessive talar displacement and calcaneal eversion. The present subtalar implant is used to treat a wide range of flat foot and other foot disorders. 
         [0007]    In one form, the subtalar implant has two expansion segments or wings. In this form, the two expansion segments are preferably, but not necessarily, situated 180° apart. In another form, the subtalar implant has four expansion segments or wings. In this form, the four expansion segment are preferably, but not necessarily, situated 90° apart. In both forms, other spacing of the expansion segments are contemplated. This can include equal and non-equal spacing. Additionally, subtalar implants having three expansion segments or more than four expansion segments are contemplated. 
         [0008]    In all forms, the expansion wings are hinged on the distal portion of the subtalar implant, which causes only the proximal portion of the wing to expand relative to the midplane of the implant. The expansion wings and the entire subtalar implant are threaded to prevent the implant from backing out of the sinus tarsi once implanted. 
         [0009]    In one form, the subtalar implant includes an integral expansion screw that, when rotated, expands the expansion wings. The integral expansion screw includes a hex (or other style) socket that accepts a like driver tool for engaging the hex socket and rotating the expansion screw. 
         [0010]    In one form, the subtalar implant includes a separate expansion screw that, when rotated, expands the expansion wings. The separate expansion screw includes a hexalobe (or other style) socket that accepts a like driver tool for engaging the hexalobe socket and rotating the expansion screw. 
         [0011]    In all forms, the subtalar implant has cutouts on the side of the implant body that allow an installer to grasp the implant and install it. An inner shaft of the implant has a hex socket that allows a hex driver to expand the wings of the implant after the implant is placed in the sinus tarsi. 
         [0012]    According to one method of use, the subtalar implant is inserted into the lateral aspect of the sinus tarsi using a driver to grasp the implant via its cutouts and rotating the subtalar implant clockwise. After the subtalar implant is placed into the lateral aspect of the sinus tarsi, a hex driver is then placed into the hex socket of the expansion screw in order to expand the implant to obtain the necessary height and prevent the implant from backing out. 
         [0013]    In another method of use, the subtalar implant is inserted into the lateral aspect of the sinus tarsi using a driver to grasp the implant via its cutouts and rotating the subtalar implant clockwise. After the subtalar implant is placed into the lateral aspect of the sinus tarsi, a separate expansion screw is inserted into the implant. A hex driver is then placed into a hex socket of the separate expansion screw in order to expand the implant to obtain the necessary height and prevent the implant from backing out. 
         [0014]    Further aspects of the present invention will become apparent from consideration of the drawings and the following description of forms of the invention. A person skilled in the art will realize that other forms of the invention are possible and that the details of the invention can be modified in a number of respects without departing from the inventive concept. The following drawings and description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The features of the invention will be better understood by reference to the accompanying drawings which illustrate forms of the present invention, wherein: 
           [0016]      FIG. 1  is a side view of one form of an expandable subtalar implant fashioned in accordance with the present principles, the expandable subtalar implant having two expansion segments that are in an unexpanded state; 
           [0017]      FIG. 2  is a front side isometric view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in the unexpanded state; 
           [0018]      FIG. 3  is a rear side isometric view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in the unexpanded state; 
           [0019]      FIG. 4  is a side view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in an expansion state; 
           [0020]      FIG. 5  is a rear side view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in an expansion state; 
           [0021]      FIG. 6  is a rear side view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in an expansion state; 
           [0022]      FIG. 7  is a side view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in an un-expanded state; 
           [0023]      FIG. 8  is a side view of the expandable subtalar implant of  FIG. 1  with the two expansion segments in an expanded state; 
           [0024]      FIG. 9  is a side rear view of another form of an expandable subtalar implant fashioned in accordance with the present principles, the expandable subtalar implant having four expansion segments that are in an unexpanded state; 
           [0025]      FIG. 10  is a rear isometric view of the expandable subtalar implant of  FIG. 9  with the four expansion segments in an expansion state; 
           [0026]      FIG. 11  is a front side isometric view of the expandable subtalar implant of  FIG. 9  with the four expansion segments in an expansion state; 
           [0027]      FIG. 12  is an exploded view of another form of an expandable subtalar implant fashioned in accordance with the present principles, the expandable subtalar implant having two expansion segments that are in an unexpanded state; 
           [0028]      FIG. 13  is a rear isometric view of the subtalar implant of  FIG. 12 , the two expansion segments in an unexpanded state; 
           [0029]      FIG. 14  is a rear isometric view of a component of the subtalar implant of  FIG. 12 ; 
           [0030]      FIG. 15  is a side view of the component of  FIG. 14 ; 
           [0031]      FIG. 16  is another side view of the component of  FIG. 14 ; 
           [0032]      FIG. 17  is an end view of the component of  FIG. 14  taken along line  17 - 17  of  FIG. 15 ; 
           [0033]      FIG. 18  is a sectional view of the component of  FIG. 14  taken along line  18 - 18  of  FIG. 15 ; 
           [0034]      FIG. 19  is a sectional view of the component of  FIG. 14  taken along line  19 - 19  of  FIG. 16 ; 
           [0035]      FIG. 20  is an isometric view of another component of the subtalar implant of  FIG. 12 ; 
           [0036]      FIG. 21  is a side view of the component of  FIG. 20 ; 
           [0037]      FIG. 22  is an end view of the component of  FIG. 20  taken along line  22 - 22  of  FIG. 21 ; 
           [0038]      FIG. 23  is a side view of the subtalar implant of  FIG. 12 ; 
           [0039]      FIG. 24  is another side view of the subtalar implant of  FIG. 12 ; 
           [0040]      FIG. 25  is an end view of the subtalar implant of  FIG. 12  taken along line  25 - 25  of  FIG. 23 ; 
           [0041]      FIG. 26  is a sectional view of the subtalar implant of  FIG. 12  taken along line  26 - 26  of  FIG. 24 ; 
           [0042]      FIG. 27  is a sectional view of the subtalar implant of  FIG. 12  taken along line  27 - 27  of  FIG. 23 ; 
           [0043]      FIG. 28  is a rear isometric view of the subtalar implant of  FIG. 12 , the two expansion segments in an expanded state; 
           [0044]      FIG. 29  is a side view of the expanded subtalar implant of  FIG. 28 ; 
           [0045]      FIG. 30  is another side view of the expanded subtalar implant of  FIG. 28 ; 
           [0046]      FIG. 31  is an end view of the expanded subtalar implant of  FIG. 28  taken along line  31 - 31  of  FIG. 29 ; 
           [0047]      FIG. 32  is a sectional view of the expanded subtalar implant of  FIG. 28  taken along line  32 - 32  of  FIG. 30 ; and 
           [0048]      FIG. 33  is a sectional view of the expanded subtalar implant of  FIG. 28  taken along line  33 - 33  of  FIG. 29 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0049]    Referring to  FIGS. 1-8 , there is depicted an exemplary form of the present subtalar implant, generally designated  10 . The subtalar implant  10  is made from a biocompatible material such as, but not limited to, titanium, stainless steel, an alloy of titanium or steel, or other. The subtalar implant is characterized by a body  12  in the general shape of an ogive, having a majority, if not all, of the outer surface thereof covered in threading, serrations or the like. The subtalar implant  10  includes an integral internal expansion mechanism as described below. 
         [0050]    The body  12  has a head  14  in the general shape of an arc at a distal end of the implant that aids in insertion of the implant  10 . A first wing or expansion segment  18  is provided along the outside surface of the body  12 , the first wing  18  having a long axis that is co-axial with a long axis of the body  12 . The distal end of the first wing  18  is hinged  19  to the body  12  such that the first wing  18  can expand, elevate or pivot from the body  12 . A second wing or expansion segment  20  is provided along the outside surface of the body  12 , the second wing  20  having a long axis that is co-axial with a long axis of the body  12 , the nomenclature first and second being arbitrary. The distal end of the second wing  20  is hinged  21  to the body  12  such that the second wing  20  can expand, elevate or pivot from the body  12 . In  FIGS. 1-3  the first and second wings  18 ,  20  are in an unexpanded or un-pivoted position (i.e. an unexpanded state) while in  FIGS. 4-8  the first and second wings  18 ,  20  are in expanded or pivoted positions (i.e. expanded states). The amount of expansion or pivoting of the first and second wings  18 ,  20 , and thus the amount of expansion of the implant  10  is controlled as described below. 
         [0051]    The implant  10  includes a screw drive that is internal to the body  12 . The screw drive incudes a threaded shaft  22  that is connected at an upper end thereof to an inside distal area of the body  12 . An expander  16  of the screw drive is situated inside the body  12 . The expander  16  is an externally threaded piece disposed generally at the proximate end of the body  12  and having an internally threaded boss  24  that is situated on the threaded shaft  22 . A socket  17  is provided in the end of the expander  16  for receipt of a drive tool (not shown) in order to rotate the expander  16 . While the socket  17  is shown as a hexagon (for receipt of a hex driver), other shapes and like drivers may be used. The expander  16  is rotatable on the threaded shaft  22  such that rotation in one direction advances the expander further into the body  12  while rotation in another direction regresses the expander out of the body  12 . 
         [0052]    The first wing  18  includes threading along its inside surface. The second wing  20  also includes threading along its inside surface. The external threading of the expander  16  meshes with the inside threading of the first and second wings  18 ,  20 . Rotation of the expander  16  to advance the expander  16  into the body  12  spreads or expands the first and second wings  18 ,  20  such that the first and second wings  18 ,  20  pivot outwardly at their hinges  19 ,  21  thereby expanding the implant  10 . The amount of expansion of the wings is dependent upon how far the expander  16  is advanced into the body  12 . Opposite rotation of the expander  16  regresses the expander  16  from the body  12  and allows the first and second wings  18 ,  20  to un-expand or collapse back into the body  12 . 
         [0053]    The expander  16  further includes first and second cutouts  26 ,  28  on an outside surface thereof, the nomenclature first and second being arbitrary. The first and second cutouts  26 ,  28  allow the user to grasp the implant  10  for implanting. 
         [0054]    Referring to  FIG. 9-11 , there is depicted another exemplary form of the present subtalar implant generally designated  40 . The subtalar implant  40  is made from a biocompatible material such as, but not limited to, titanium, stainless steel, an alloy of titanium or steel, or other. The subtalar implant is characterized by a body  42  in the general shape of an ogive, having a majority, if not all, of the outer surface thereof covered in threading, serrations or the like. 
         [0055]    The body  42  has a head  44  in the general shape of an arc at a distal end of the implant that aids in insertion of the implant  40 . A first wing or expansion segment  48  is provided along the outside surface of the body  42 , the first wing  48  having a long axis that is co-axial with a long axis of the body  42 . The distal end of the first wing  48  is hinged  58  to the body  42  such that the first wing  48  can expand, elevate or pivot from the body  42 . A second wing or expansion segment  49  is provided along the outside surface of the body  42 , the second wing  49  having a long axis that is co-axial with a long axis of the body  42 . The distal end of the second wing  49  is hinged  59  to the body  42  such that the second wing  49  can expand, elevate or pivot from the body  42 . A third wing or expansion segment  50  is provided along the outside surface of the body  42 , the third wing  50  having a long axis that is co-axial with a long axis of the body  42 . The distal end of the third wing  50  is hinged  60  to the body  42  such that the third wing  50  can expand, elevate or pivot from the body  42 . A fourth wing or expansion segment  51  is provided along the outside surface of the body  42 , the fourth wing  51  having a long axis that is co-axial with a long axis of the body  42 . The distal end of the fourth wing  51  is hinged  61  to the body  42  such that the fourth wing  51  can expand, elevate or pivot from the body  42 . The nomenclature first, second, third and fourth being arbitrary. The amount of expansion or pivoting of the first, second, third and fourth wings  48 ,  49 ,  50 ,  51 , and thus the amount of expansion of the implant  40  is controlled as described below. 
         [0056]    The implant  40  includes a screw drive that is internal to the body  42 . The screw drive incudes a threaded shaft that is connected at an upper end thereof to an inside distal area of the body  42 . An expander  46  of the screw drive is situated inside the body  42 . The expander  46  is an externally threaded piece disposed generally at the proximate end of the body  42  and having an internally threaded boss that is situated on the threaded shaft. A socket  47  is provided in the end of the expander  46  for receipt of a drive tool (not shown) in order to rotate the expander  46 . While the socket  47  is shown as a hexagon, hexalobe or the like (for receipt of a hex/hexalobe driver), other shapes and like drivers may be used. The expander  46  is rotatable on the threaded shaft such that rotation in one direction advances the expander further into the body  42  while rotation in another direction regresses the expander out of the body  42 . 
         [0057]    The first, second, third, and fourth wings  48 ,  49 ,  50 ,  51  include threading along their inside surface. The external threading of the expander  46  meshes with the inside threading of the first, second, third, and fourth wings  48 ,  49 ,  50 ,  51 . Rotation of the expander  46  to advance the expander  46  into the body  42  spreads or expands the first, second, third, and fourth wings  48 ,  49 ,  50 ,  51  such that the first, second, third, and fourth wings  48 ,  49 ,  50 ,  51  pivot outwardly at their hinges  58 ,  59 , 60 ,  61  thereby expanding the implant  40 . The amount of expansion of the wings is dependent upon how far the expander  46  is advanced into the body  42 . Opposite rotation of the expander  46  regresses the expander  46  from the body  42  and allows the first, second, third, and fourth wings  48 ,  49 ,  50 ,  51  to un-expand or collapse back into the body  42 . The expander  46  further includes first and second cutouts  54 ,  56  on an outside surface thereof, the nomenclature first and second being arbitrary. The first and second cutouts  54 ,  56  allow the user to grasp the implant  40  for implanting. 
         [0058]    Referring to  FIGS. 12-33 , there is depicted various views of another exemplary form of the present subtalar implant, generally designated  80  and its components. The subtalar implant  80  is made from a biocompatible material such as, but not limited to, titanium, stainless steel, an alloy of titanium or steel, or other. The subtalar implant is characterized by a first component  81  and a second component  82 . The first component  81  is in the general shape of an ogive and may be considered an implant body  81 . The second component  82  is a separate expansion mechanism or member and is embodied in this form as a screw  82 .  FIG. 12  shows the expansion screw  82  separate from the implant body  81 , the implant body in an unexpanded state.  FIG. 13  depicts the expansion screw  82  inserted in the implant body  81 , the implant body  81  in the unexpanded state. 
         [0059]    The implant body  81  of the subtalar implant  80  is more particularly shown in  FIGS. 14-19  in an unexpanded, normal or unbiased state before insertion of the expansion screw  82 . The implant body  81  has a generally conical or ogive configuration  90  having a nose or end  91 . A first portion or arm  92  extends from one side of the nose  91 , while a second portion or arm  93  extends from another side of the nose  91 , generally radially opposite one another, the nomenclature first and second being arbitrary. The first portion  92  extends along the configuration  90  and includes external ribbing, serrations, threading or the like  96  and terminates in a U member  97 . The U member  97  provides a means for receiving a driver or driving tool for implanting the configuration  90 . The second portion  93  extends along the configuration  90  and includes external ribbing, serrations, threading or the like  100  and terminates in a U member  101 . The U member  101 , along with U member  97 , provides a means for receiving a driver or driving tool for implanting the configuration  90 . 
         [0060]    The configuration  90  further includes first and second expansion members, wings or the like  94 ,  95  that extend from the nose  91 , the nomenclature first and second being arbitrary. A hinge  104  pivotally connects the first wing  94  to the nose  91 , while a hinge  106  connects the second wing  95  to the nose  91 . The hinges  104 ,  106  allow the wings  94 ,  95  to pivot relative to the remainder of the configuration  90 . Insertion of the screw  82  causes the wings  94 ,  95  to pivot or expand outwardly from the configuration (see e.g.,  FIGS. 28-33 ). While two wings are shown, the subtalar implant  80  may have more than two expansion wings. The hinges  104 ,  106  are preferably, but not necessarily, fashioned out of the implant body so as to be integral therewith. The first wing  94  includes external ribbing, serrations, threading or the like  105 , while the second wing  95  likewise includes external ribbing, serrations, threading or the like  107 . The external ribbing, serrations, threading or the like of the first and second arms  92 ,  93  and wings  94 ,  95  provides a gripping surface, allows insertion of the configuration  90 , and/or provides anti-back-out of the configuration  90 . A bore  99  is provided in the nose  91  and extends through the implant  81 . As seen in  FIG. 33 , the bore  99  provides communication with the internal bore or cannula  120  of the screw  82 . 
         [0061]    The second component (i.e. expansion screw or member)  82  is shown in particular in  FIGS. 20-22 . The expansion screw is characterized by a body  83  having an externally threaded shank or shaft  84  with a head  85  at one end of the threaded shank  84  and an end  89  at the other end of the shank  84 . The screw  82  is sized for reception in the implant body  81  as shown in other figures. The head  85  has a top  87  and transitions from the threaded shank  84  via an angled neck  86 , the angled neck  86  and head  85  providing gradual expansion of the wings  94 ,  95  of the implant body  81  as it is threadedly (rotatably) inserted therein (see e.g.,  FIGS. 28-33 ). 
         [0062]      FIGS. 26 and 27  provide sectional views of the subtalar implant  80  with the expansion screw  82  beginning to be inserted into the configuration  81 . At this point, the angled neck  86  of the head  85  of the expansion screw  82  has not yet reached the angled inside surfaces of the first and second wings  94 ,  95 . Therefore, the wings have not yet begun to expand.  FIGS. 32 and 33  provides sectional views of the subtalar implant  80  with the expansion screw  82  being threadedly received in the implant body  90 . At this point, the angled neck  86  of the head  85  of the expansion screw  82  contacts the angled inside surfaces of the first and second wings  94 ,  95 . Therefore, the wings expand. In all of the forms presented herein of a subtalar implant, the expansion segments, wings, portions or the like expand radially outwardly from the implant, particularly, but not necessarily from proximate a rear portion of the implant. Moreover, expansion is provided by either in internal, integral expansion mechanism or a separate device. 
         [0063]    The present subtalar implant is used with and/or for subtalar arthroereisis and is thus intended to assist in treating the hyperpronated foot by stabilizing the subtalar joint. It is intended to block forward, downward, and medial displacement of the talus, thereby limiting excessive eversion of the hindfoot. The subtalar implant may also be used as an adjunct in conjunction with other corrective procedures, including posterior tibial tendon reconstruction, FDL tendon transfers and the medial displacement calcaneal osteotomy. 
         [0064]    It should be appreciated that dimensions of the components, structures, and/or features of the present subtalar implants can be altered as desired.