Patent Publication Number: US-11642224-B2

Title: Implant and method for ankle syndemosis treatment

Description:
This application is a continuation of patent application Ser. No. 15/586,694, filed May 4, 2017, the entirety of which is incorporated herein by reference. 
    
    
     FIELD 
     This disclosure relates to implants for treatment of ankle syndesmosis injuries. 
     BACKGROUND 
     A syndesmosis is a joint where two bones are held together by thick connective ligaments. For example, the lower ends of the tibia and fibula are connected by the ankle syndesmosis. An ankle syndesmosis injury (high ankle sprain) involves one or more of the ligaments connecting the bottom ends of the tibia and fibula. A high ankle sprain stretches or tears one of these ligaments. A syndesmosis injury involves a stretching or tear in one of the ligaments in the ankle syndesmosis and can lead to ankle instability. In severe tears of the ligaments, the ends of the tibia and fibula can spread apart. Syndesmosis injuries that cause ankle instability may require surgery. Surgical methods can include implantation of syndesmosis screws or tensioned sutures through the fibula and tibia to reduce the syndesmosis. 
     SUMMARY 
     In some embodiments, an implant, comprises a curved first plate section having a curvature about a longitudinal axis extending in a longitudinal direction. The curved first plate section has a first hole and a second hole. The first hole and the second hole are positioned to receive respective bone screws for attaching the implant to a first curved surface of a bone having a syndesmosis. A second plate section extends continuously from the curved first plate section. The second plate section has at least a third hole offset in a direction that is anterior or posterior from the first hole and the second hole in a case where the longitudinal axis is aligned along a superior-inferior direction. The third hole is configured to receive at least one screw or at least one button for holding a suture at a position offset in the posterior direction from the first line hole and the second hole, for reducing the syndesmosis. 
     In some embodiments, an implant system comprises: a bone plate comprising a curved first plate section having a curvature about a longitudinal axis extending in a longitudinal direction. The curved first plate section subtends an angle from 5 degrees to 45 degrees. The curved first plate section has a first hole and a second hole arranged along a first line segment parallel to the longitudinal axis. The first hole and the second hole are positioned to receive respective bone screws for attaching the implant to a curved surface of a fibula that extends to an ankle having a syndesmosis. A second plate section extends continuously from the curved first plate section. The second plate section has a third hole offset from the first line segment in a direction that is anterior or posterior from the first hole and the second hole in a case where the longitudinal axis is aligned along a superior-inferior direction. The third hole is configured to receive at least one bone screw or button for holding a suture. A third plate section is located adjacent the second hole and having a concave region shaped to conform to a lateral malleolus of the fibula. The third plate section has at least a fourth hole positioned to receive an additional bone screw. The system also includes at least one suture and at least one fastener including a bone screw or a button for positioning the at least one suture at a lateral apex of the fibula for reducing the syndesmosis. 
     In some embodiments, a method comprises: implanting a bone plate on an anterolateral side of a fibula having a syndesmosis, the bone plate having: a curved plate section having a curvature about a longitudinal axis extending in a longitudinal direction, the curved plate section having a first superior hole and a first inferior hole, the first superior hole and the first inferior hole positioned to receive respective bone screws for attaching the implant to an anterolateral surface of a fibula that extends to an ankle, and a lateral plate section extending continuously from the curved plate section, the lateral plate section having at least one syndesmosis hole offset in a posterior direction from the first superior hole and a first inferior hole, the at least one syndesmosis hole configured to receive at least one screw or button for holding at least one suture at a lateral apex of the fibula; inserting the at least one suture through the at least one syndesmosis hole, the fibula, and a centroid of a tibia adjacent the fibula; and tensioning the suture to reduce the syndesmosis. 
     In some embodiments, an implant, comprises a curved first plate section having a curvature about a longitudinal axis extending in a longitudinal direction. The curved first plate section has a first hole and a second hole. The first hole and the second hole are positioned to receive respective bone screws for attaching the implant to a first curved surface of a bone having a syndesmosis. A second plate section extends continuously from the curved first plate section. The second plate section has at least a third hole offset in a tangential direction from the first hole and the second hole, wherein the tangential direction is orthogonal to the longitudinal direction and a radial direction. The third hole is configured to receive at least one screw or button for holding a suture at a position offset in the tangential direction from the first line hole and the second hole, for reducing the syndesmosis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an anterolateral view of an embodiment of a syndesmosis plate. 
         FIG.  2    is an anterior edge view of the syndesmosis plate of  FIG.  1   . 
         FIG.  3    is a medial view of the syndesmosis plate of  FIG.  1   . 
         FIG.  4    is a cross-sectional view of the implant of  FIG.  1   , taken across section line  4 - 4  of  FIG.  1   . 
         FIG.  5    is a superior end view of the syndesmosis plate of  FIG.  1   . 
         FIG.  6    is a lateral view of the syndesmosis plate of  FIG.  1   . 
         FIG.  7    is a cross-sectional view of the implant of  FIG.  5   , taken across section line  7 - 7  of  FIG.  5   . 
         FIG.  8    is a cross-sectional view of the implant of  FIG.  6   , taken across section line  8 - 8  of  FIG.  6   . 
         FIG.  9    is a lateral view of a variation of the syndesmosis plate of  FIG.  1   . 
         FIG.  10    is an edge view of an embodiment of a fibula fracture plate. 
         FIG.  11    is a lateral view of the fibula fracture plate of  FIG.  10   . 
         FIG.  12    is a medial view of the fibula fracture plate of  FIG.  10   . 
         FIG.  13    is an inferior view of the fibula fracture plate of  FIG.  10   . 
         FIG.  14    is a cross-sectional view of the implant of  FIG.  11   , taken across section line  14 - 14  of  FIG.  11   . 
         FIG.  15    is a superior cross-sectional view of an ankle with the syndesmosis plate of  FIG.  1    implanted thereon. 
         FIG.  16    is a posterior view of the ankle and implant of  FIG.  15   . 
         FIG.  17    is an anterior view of an ankle with the fibula fracture plate of  FIG.  10    implanted thereon with a suture for syndesmosis reduction. 
         FIG.  18    is a lateral view of an ankle with the fibula fracture plate of  FIG.  10    implanted thereon with screws for syndesmosis reduction. 
     
    
    
     DETAILED DESCRIPTION 
     This 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,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative 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. 
     Surgical treatments for syndesmosis injuries can include implanting a bone plate on the lateral side of the fibula and inserting a fastener (e.g., a syndesmosis screw and/or a button-suture system, such as the “ENDOBUTTON”™ suture sold by Smith &amp; Nephew of Andover, Mass.) through the bone plate, the fibula and the tibia. By tightening the fastener, the surgeon can reduce the syndesmosis. 
     The bone plate can have a column of holes, including at least two screw-receiving holes and at least one syndesmosis hole, through which the syndesmosis screw or suture is passed. In some cases, the syndesmosis injury is accompanied by a tibia fracture. For treating a combination of syndesmosis and fracture, the implant can be extended in superior and inferior directions to provide bone fixation as well as syndesmosis reduction. 
     Ideally, when the syndesmosis screw or suture is used, it should be inserted parallel to the tibial plafond in the coronal plane, and thirty degrees relative to the coronal plane of the ankle. This position applies forces to the tibia and fibula, such that a force vector is approximately along a line segment connecting the area centroid of the tibia with an area centroid of the fibular (where the area centroid is determined in a plane parallel to the tibial plafond). This trajectory returns the tibia and fibula to their normal stable relationship. The line passing through the area centroids of the tibia and fibula exits the fibula at the lateral fibular apex, which is just posterior to the anterolateral border of the fibula. 
     Surgeons generally implant syndesmosis plates on the anterolateral border of the fibula, which is about 20-30 degrees anterior of the lateral fibular apex. This is a position where the plate will not protrude or cause discomfort for the patient. To obtain good syndesmosis reduction, the screws inserted on the anterolateral surface are angulated to point toward the centroid of the tibia, which is about 20-30 degrees from perpendicular to the anterolateral surface. Syndesmosis screws and sutures inserted at this 20-30 degree offset from the lateral fibular apex may provide less stability than similar screws or sutures along the line connecting the area centroids of the tibia and fibula. Also, a screw entering the anterolateral surface and directed toward the centroid of the tibia will be oriented at an angle with respect to the anterolateral surface, so the head of the screw may protrude in an area with little soft tissue covering it. Should the head protrude and cause discomfort to the patient, the surgeon may need to remove the screw. 
     This disclosure describes examples of syndesmosis plates and fibula fracture plates that allow the surgeon to implant the plates with bone screws on the anterolateral border of the fibula, and insert syndesmosis screws or sutures along the line connecting the centroids (and passing through the lateral fibular apex). The implants make it easier for the surgeon to position and affix the implant to the fibula, while achieving a desired syndesmosis screw or suture alignment for stabile reduction of the syndesmosis. 
       FIGS.  1 - 8    show a first exemplary embodiment of a syndesmosis plate  100 .  FIG.  1    is a lateral view of an embodiment of the syndesmosis plate  100 .  FIG.  2    is an anterior edge view of the syndesmosis plate  100 .  FIG.  3    is a medial view of the syndesmosis plate  100 .  FIG.  4    is a cross sectional view of the syndesmosis plate  100  taken along section line  4 - 4  of  FIG.  1   .  FIG.  5    is a superior end view of the syndesmosis plate  100 .  FIG.  6    is a posterolateral view of the syndesmosis plate  100 .  FIG.  7    is a cross-sectional view of the syndesmosis plate  100  taken along section line  7 - 7  in  FIG.  5   .  FIG.  8    is a cross-sectional view of the syndesmosis plate  100  taken along section line  8 - 8  in  FIG.  6   .  FIG.  16    is a superior view of a fibula  302  and tibia  304 , with the syndesmosis plate  100  implanted on the tibia, and a bone screw or suture  320   s  and button  320  assembly. 
     Referring to  FIGS.  1 ,  5  and  6   , the syndesmosis plate  100  includes a curved first plate section  102 . The curved plate section  102  can have a cross-sectional shape that is circular, elliptical, oval, parabolic, hyperbolic, or logarithmic in shape, or have another curvature. In some embodiments, the curved plate section  102  has circular cross-section with a radius of curvature R 1  (shown in  FIG.  5   ) about a longitudinal axis A L  ( FIGS.  1  and  5   ) extending in a longitudinal direction L. In some embodiments, the radius R 1  is about 0.5 inch (e.g., 0.4 inch to 0.6 inch), subtending an arc of about 0.25″ (e.g., 0.2″ to 0.3″), and the longitudinal length of plate section  102  is about 1.5″ (e.g., 1.4″ to 1.6″). In some embodiments, not shown, the curved plate section  102  is radially offset outward from the non-curved, second plate section  104 . In alternate embodiments (not shown), the curved plate section  102  may be disposed on an interior plate portion having a first radius of curvature, with either a non-curved section or a second curved section (having a second, different radius of curvature), extending therefrom. The curved first plate section  102  subtends an angle θ ( FIG.  16   ) from 5 degrees to 45 degrees and is curved to conform to the shape of the lateral surface of the fibula. In some embodiments, the angle θ subtends an angle from 15 to 35 degrees. In some embodiments, the angle θ subtends an angle from 20 to 30 degrees. In other embodiments (not shown), the angle θ is greater than 45 degrees, and the second plate section is shaped to conform to the ridge of the lateral fibular apex. Referring again to  FIGS.  1  and  6   , the curved first plate section  102  has a first hole  106  and a second hole  107  along a first line segment  111  ( FIG.  16   ) parallel to the longitudinal axis A L . The first hole  106  and the second hole  107  are positioned to receive respective bone screws  322 ,  323  ( FIG.  17   ) for attaching the syndesmosis plate  100  to a first curved surface of a bone (e.g., fibula)  302  ( FIGS.  16 ,  17   ) having a syndesmosis. Alternately, the first hole  106  and the second hole  107  may be disposed along a first line segment and a second line segment, wherein the first line segment and the second line segment are both parallel to the longitudinal axis, and the second line segment is offset in a tangential direction—orthogonal to the radial direction—from the first line segment. The syndesmosis includes the posterior talofibular ligament  306  and anterior talofibular ligament  308  ( FIG.  16   ). In some embodiments, the first hole  106  and the second hole  107  are locking screw holes for receiving bone screws to secure the syndesmosis plate  100  on the lateral surface of the fibula  302 . 
     Referring again to  FIGS.  1  and  6   , a second plate section  104  extends continuously from the curved first plate section  102 . The second plate section  104  has at least a third hole  108  offset from the first line segment  111   FIG.  16   ). The third hole  108  is configured to receive at least one (locking or non-locking) screw or button  320  ( FIG.  17   ) for holding a suture  320   s  at a position offset from the first line segment by the angle θ, for reducing the syndesmosis. In some embodiment, the third hole  108  is positioned to be offset in a direction that is anterior or posterior from the first hole  106  and the second hole  107  in a case where the longitudinal axis A L  is aligned along a superior-inferior direction of the fibula. Some embodiments include one or more additional holes  109  in the second plate section  104 . In some embodiments, the third hole  108  and fourth hole  109  are non-locking holes for receiving a non-locking screw or a suture system, such as a button  320  and suture  320   s . In some embodiments, the third hole  108  and fourth hole  109  are locking holes for receiving syndesmosis screws. In some embodiments, the locking or non-locking holes  108 ,  109  have a counterbore about 0.010 inch to 0.015 inch deep for seating the head of the screw or button  320 . 
     In some embodiments, the second plate section  104  is flat and extends for a length  312 , as shown in  FIGS.  5  and  8   . For example, the length  312  can be about 0.13 inch (e.g., from 0.12 to 0.14 inch). In some embodiments (not shown), the second plate section  104  is curved with a circular cross-section and has the same radius of curvature as the first plate section. In other embodiments (not shown), the second plate section  104  extends from a second outer plate edge, inward/medially, towards the first plate section  102 . In other embodiments (not shown), the second plate section is curved to conform to the lateral fibular apex. In other embodiments (not shown), the second plate section has a notch or rib to accommodate the posterior ridge of the fibula. 
     In some embodiments, as shown in  FIGS.  1  and  6   , the syndesmosis plate  100  has a first edge with a convex portion  104   e , and the third hole  108  is located adjacent the convex portion  104   e  of the first edge. 
     In some embodiments, as shown in  FIGS.  1  and  6   , the syndesmosis plate  100  has a second edge with a concave portion  110 , and the first hole  106  and the second hole  107  are located adjacent the end portions of the second edge excluding the concave portion  110 . In some embodiments, the concave edge has a radius from about 1.5 inch to about 3 inch. 
       FIG.  16    is a superior cross-sectional view of the fibula  302  and tibia  304  taken in a plane parallel to the tibial plafond.  FIG.  17    is a cross-sectional view taken along section line  17 - 17  of  FIG.  16   . The syndesmosis plate  100  is secured to the anterolateral surface of the fibula by bone screws  322  through the holes  106 ,  107  along the line segment  111 . The surgeon drills holes  313  which is aligned with the syndesmosis hole  108  and passes through the centroid  310  of the fibula  302  and the centroid  311  of the tibia  304 . The syndesmosis hole  108  is offset from the screws  322  by the angle θ, so the syndesmosis holes are aligned with the lateral apex of the fibula  302 . The surgeon inserts a button  320  and suture  320   s  assembly with a retainer  330  through the hole drilled through the fibula  302  and tibia  304 . In other embodiments (not shown), the surgeon inserts a syndesmosis screw through each syndesmosis hole  108 ,  109 , the fibula  302  and the tibia  304 . 
     In  FIGS.  16  and  17   , the syndesmosis plate  100  is positioned with the first plate section  102  on the anterolateral surface of the fibula  302 , and the second plate section  104  extending in the posterior direction to the lateral face. The same syndesmosis plate  100  can also be flipped and positioned with the first plate section  102  on the posterolateral surface of the fibula  302 , and the second plate section  104  extending in the anterior direction to the lateral face. 
       FIG.  9    is a lateral view of a variation of the syndesmosis plate. The general form of the plate  150  is the same as syndesmosis plate  100  of  FIGS.  1 - 8   , except that plate  150  has a straight edge  160  instead of a curved edge  110  (as shown in  FIGS.  1 - 8   ). The shape of the edges can be varied. 
       FIGS.  10 - 15  and  18    show an embodiment of a fibula fracture plate  200 . The implant system has a bone plate  200  comprising a curved first plate section  202  ( FIG.  12   ) having a radius of curvature R 3  about a longitudinal axis A L1  ( FIG.  14   ), extending in a longitudinal direction, the curved first plate section  202  subtends an angle θ1 ( FIG.  14   ) from 5 degrees to 45 degrees, e.g., from 25-35 degrees. The curved first plate section  202  has a first hole  206  and a second hole  207  arranged along a first line segment  211  parallel to the longitudinal axis A L1 . The first hole  206  and the second hole  207  are positioned to receive respective bone screws  324 - 327  (see  FIG.  18   ) for attaching the implant  200  to a curved surface of a fibula  302  that extends to an ankle having a syndesmosis. In some embodiments, the first hole and the second hole are locking screw holes, and the third hole and the fourth hole are non-locking holes. 
     A second plate section  204  ( FIG.  12   ) extends continuously from the curved first plate section  202 . In some embodiments, the second plate section  204  of the implant  200  has a first edge  241  with a convex portion, and the third hole  208  and the fourth hole  209  are each located adjacent the convex portion of the first edge  241 . The second plate section has a third hole  208  offset from the first line segment  211 . In some embodiment, the third hole  208  is positioned to be offset in a direction that is anterior or posterior from the first hole  206  and the second hole  207  in a case where the longitudinal axis A L  is aligned along a superior-inferior direction of the fibula. The third hole  208  is configured to receive at least one (locking or non-locking) bone screw or button for holding a suture  320   s . In some embodiments, the third hole  208  and fourth hole  209  are non-locking holes for receiving a non-locking screw or a suture system, such as a button  320  and suture  320   s . In some embodiments, the third hole  208  and fourth hole  209  are locking holes for receiving syndesmosis screws. In some embodiments, the third hole  208  is configured to receive the bone screw or a button for positioning the at least one suture  320   s  at a lateral apex of the fibula (at the same location shown for syndesmosis plate  100  in  FIG.  16   ) for reducing the syndesmosis. In some embodiments, the holes  208 ,  209  have a counterbore about 0.010 inch to 0.015 inch deep for seating the head of the screw or button  320 . In some embodiments, the implant  200  has a second edge with a concave portion  239 , and the first hole  206  and the second hole  207  are located adjacent portions of the second edge excluding the concave portion  239 . 
     The fibula fracture plate  200  has a third plate section  252  ( FIG.  12   ) located adjacent the second hole  207  and having a concave region shaped to conform to a lateral malleolus  303  ( FIG.  18   ) of the fibula  302 . In some embodiments, as shown in  FIG.  13   , the third plate section  252  is offset from the curved first plate section  202  and the second plate section  204  in the radial direction, to accommodate the lateral malleolus  303 . The third plate section  252  has at least n additional hole  232 - 235  ( FIGS.  11 ,  12   ), positioned to receive an additional bone screw(s)  324 - 327 . In some embodiments, the third plate section has one or more additional holes positioned to receive one or more additional bone screws adjacent a plurality of locations on the lateral malleolus. In some embodiments, the fibula fracture plate has a superior section opposite the third section. The superior section can include additional screw holes  221 ,  222  and provides additional support and fixation for a fibula fracture. 
     The number of syndesmosis holes  208 ,  209  is not limited to two, and can be at least one or more holes. The number and configuration of screw holes in the fibula fracture plate are not limited to the configuration of  FIGS.  11 - 12    and can be varied. Additionally, the shape of the perimeter of the fibula fracture plate  200  can be varied. For example, the perimeter in near the screw holes  221 ,  222  has an undulating shape with a neck  203 , which allows a surgeon to drive a screw into the fibula adjacent to the implant  200  in the scallop (neck)  203  at a different angle for additional fixation and/or enhanced stability. For example, the surgeon can insert the screws so that the distal ends of the screws (opposite the heads) diverge from each other. The scallops (necks) also allow for the surgeon to contour or bend the plate about a tangential axis—orthogonal to the radial and longitudinal axes—to follow the shape of the lateral malleolus of the fibula, for example. In some embodiments, the third plate section  252  has one or more additional undulating curves to provide additional sites at which the surgeon can optionally drive additional screws if appropriate for a particular injury. Further, the shape of plate edges may vary. The plate edges may be rounded, rectangular with rounded corners, or plate edges may have defined corners. 
     As shown in  FIG.  18   , at least one syndesmosis screw or suture  320   s  is inserted through a lateral-medial hole through the fibula  302  and tibia  304 . The syndesmosis screw or suture  320   s  performs the same function in the fracture plate  200  as discussed above with respect to the syndesmosis plate  100 , and is not repeated, for brevity. 
       FIGS.  16 - 17    show a method of using the syndesmosis plate  100 , and  FIG.  18    shows a method of using the fibula fracture plate  200 . 
     As shown in  FIGS.  16 - 17   , the method includes positioning a bone plate (e.g., syndesmosis plate  100 ) on an anterolateral side of a fibula  302  having a syndesmosis  306 ,  308 . The syndesmosis plate  100  has a curved first plate section  102  (anterolateral plate section) having a radius of curvature R 1  about a longitudinal axis A L  extending in a longitudinal direction L. The curved first plate section  102  subtends an angle θ from 5 degrees to 45 degrees. The curved first plate section has a first superior hole  106  and a first inferior hole  107  along a first line segment  111  parallel to the longitudinal axis A L . The first superior hole  106  and the first inferior hole  107  are positioned to receive respective bone screws  322  for attaching the syndesmosis plate  100  to an anterolateral surface of the fibula  302 . 
     The syndesmosis plate  100  is positioned so that a lateral plate section (e.g., second plate section  104 ), extending continuously from the curved first plate section  102 , has at least one syndesmosis hole  108 ,  109  offset in a posterior direction from the first line segment  111 . The positioning is performed so the lateral plate section does not overhang a posterior ridge of the fibula, to avoid patient discomfort. The at least one syndesmosis hole  108 ,  109  is configured to receive at least one screw or button  320  for holding at least one suture  320   s  at a lateral apex of the fibula  302 . If the implant is a fibula fracture plate  200 , then the implant  200  is positioned so that an inferior plate section (third plate section  252 ) is located inferior to the first inferior hole  208  and the concave region  239  conforms to the lateral malleolus  303  of the fibula  302 . 
     The surgeon drills through the holes  106 ,  107  for implanting the syndesmosis plate  100  and inserts bone screws to hold the plate in place. If the fibula fracture plate  200  ( FIG.  18   ) is being implanted, then additional bone screws  323 - 327  are inserted at this time. Then the surgeon can partially pre-drill the syndesmosis holes (e.g., about 1″ into the bone) with a k-wire and check the trajectory of the syndesmosis hole by fluoroscope. If the trajectory is not correct, the surgeon re-drills the syndesmosis hole to change the trajectory, and checks using another X-ray or fluoroscopic image. If the trajectory is proper, the surgeon completes the pre-drilling, including drilling the syndesmosis holes through the fibula and tibia. 
     Once the syndesmosis holes are drilled, the surgeon drives the bone screws or suture into the syndesmosis holes to reduce the syndesmosis. 
     As shown in  FIG.  17   , the surgeon then inserts the at least one syndesmosis screw or suture through the at least one syndesmosis hole, the fibula, and a centroid of a tibia adjacent the fibula. If a button-suture system is used, the surgeon inserts the suture through the holes in the fibular and tibia, and attaches the suture to the retaining device  330  on the medial side of the tibia. 
     The surgeon then reduces the syndesmosis by advancing the syndesmosis screw or tensioning the suture to reduce the syndesmosis. 
     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.