Patent Publication Number: US-2019183544-A1

Title: Distal radius nail

Description:
PRIORITY CLAIM 
     The present application is a Divisional Application of pending U.S. patent application Ser. No. 15/466,105 filed on Mar. 22, 2017. The disclosure of the above applications is incorporated herein by reference. 
    
    
     BACKGROUND 
     A distal radius fracture may be treated using an intramedullary nail inserted into a medullary canal of the radius. Screws may be inserted through laterally extending openings in the intramedullary nail to fix the nail relative to the bone and stabilize the fracture. An insertion instrument is generally used for the insertion of an intramedullary nail to bring the intramedullary nail to an entry point of the bone. Insertion instruments may also be used for guiding screws or other fixation elements into laterally extending openings of the nail. Thus, solutions for the treatment of distal radius fractures are often judged based on how well the insertion device works with the intramedullary nail. 
     SUMMARY 
     The present embodiments are directed to a system for treating a bone fracture comprising an intramedullary nail sized and shaped to be inserted through a medullary canal of a bone to extend across a fracture site of the bone, the intramedullary device extending from a first end including a head portion to a second end, a shaft of the intramedullary device extending from the head portion to the second end, the intramedullary device including a plurality of openings extending laterally therethrough, the openings sized and shaped to receive bone fixation elements therethrough and an insertion device including a base portion and a handle portion extending therefrom, the base portion integrally formed with the intramedullary nail and connected thereto via a plurality of connection points which, when a force is exerted thereon, break to disconnect the insertion device from the intramedullary nail, the base portion including a plurality of guide channels extending therethrough, each of the guide channels being aligned with a corresponding one of the openings of the intramedullary nail. 
     The present embodiments are also directed to a method for treating a distal radius bone, the method comprising drilling an entry hole through a styloid process of a distal radius bone, inserting an intramedullary nail through the entry hole using an insertion device integrally formed with the intramedullary nail until a shaft portion of the intramedullary nail is passed into a medullary canal of the bone and a head portion of the intramedullary nail resides within an end of the bone, the intramedullary nail connected to the insertion device via a plurality of connection points, drilling holes into the bone via guide channels of the insertion device which are in alignment with openings of the intramedullary nail, inserting bone fixation elements through drilled holes of the bone and into a corresponding one of the openings, and snapping off the insertion device to disconnect the insertion device from the intramedullary nail by breaking the connection points connecting the insertion device and the intramedullary nail. 
    
    
     
       BRIEF DESCRIPTION 
         FIG. 1  shows a side view of a system according to an exemplary embodiment; 
         FIG. 2  shows a perspective view of the system of  FIG. 1 ; 
         FIG. 3  shows another side view of the system of  FIG. 1 ; 
         FIG. 4  shows an enlarged perspective view of the system of  FIG. 1 ; and 
         FIG. 5  shows a perspective view of an intramedullary nail of a system according to another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present embodiments may be understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present embodiment relates to the treatment of bone and, in particular, relates to treatments using an intramedullary nail. Exemplary embodiments describe a system comprising an intramedullary nail and insertion device that are integrally formed with one another so that, upon insertion of the intramedullary nail into, for example, a distal radius, the insertion device may be “snapped” off, leaving the intramedullary nail within the bone. Although the exemplary embodiments describe the system as being used to treat the distal radius, it will be understood by those of skill in the art that the system of the embodiments may also be used to treat other bones such as, for example, the fibula. 
     As shown in  FIGS. 1-4 , a bone fixation system  100  according to an exemplary embodiment comprises an intramedullary nail  102  and an insertion device  104  integrally formed and connected to one another via a plurality of connection points  106  for the treatment of a fractured bone such as, for example, a fracture of the distal radius. The insertion device  104  includes a plurality of guide channels  108  extending therethrough, each of the guide channels  108  being aligned with a corresponding opening  110  extending laterally through the intramedullary nail  102 , so that drill guides (not shown) may be received within the guide channels  108  and the openings  110 . Upon insertion of the intramedullary nail  102  into the bone, a drilling device may be inserted through the drill guides to drill holes into the bone, so that bone fixation elements  112  may be inserted through the holes and into the openings  110  of the intramedullary nail  102  to fix the intramedullary nail  102  relative to the bone and to stabilize a fracture of the bone. In particular, a fixation element  112  is inserted through one of the openings  110  so that a shaft thereof locks into the bone. The fixation elements  112  are capable of angular stability relative to the intramedullary nail  102  by deforming a material of the intramedullary nail  102 . Once the intramedullary nail  102  has been fixed in the bone, the insertion device  104  may be “snapped” off without the use of tools, breaking the connection points  106  and leaving the intramedullary nail  102  implanted in the bone, as will be described in further detail below. 
     The intramedullary nail  102  is sized and shaped to be inserted into a medullary canal of, for example, the distal radius. The intramedullary nail  102  may, for example, be particularly suited for treating extra-articular fractures of the distal radius so that, when inserted into the medullary canal of the bone, the intramedullary nail  102  extends across the fracture to fix the separated or fractured portions of bone relative to one another. The intramedullary nail  102  extends longitudinally from a first end  114  to a second end  116  and includes a head portion  118  at the first end  114  and a shaft portion  120  extending longitudinally therefrom toward the second end  116 . The shaft portion  120  may extend along a curve to facilitate insertion of the intramedullary nail  102  into the medullary canal of the bone via a hole drilled through, for example, a styloid process of the bone. 
     The intramedullary nail  102  includes a plurality of openings  110  extending laterally therethrough, the openings  110  configured to receive bone fixation elements  112  therein for fixing the intramedullary nail  102  relative to the bone. In one exemplary embodiment, the intramedullary nail  102  may have three openings  110  extending laterally through the head portion  118  of the intramedullary nail  102 . A first and second one of the openings  110  may extend along first and second axes  111   a ,  111   b , respectively, that are angled and distanced from one another about and along a longitudinal axis of the intramedullary nail  102  to fix the intramedullary nail  102  relative to the bone. Thus, when the intramedullary nail  102  is used to fix a distal radius, first and second bone fixation elements  112   a ,  112   b  inserted along the first and second axes  111   a ,  111   b  through the first and second openings  110  extend through a distal end of the bone. A third one of the openings  110  is distanced from the first and second openings along the longitudinal axis of the intramedullary nail  102  and extends along a third axis  111   c  which extends across a fracture of the bone. Thus, when a third bone fixation element  112   c  is inserted along the third axis  111   c  through the third opening  110 , the third bone fixation element  112   c  extends across the fracture to provide further stabilization of the fracture. Although the exemplary embodiment shows and describes a specific configuration of openings  110 , it will be understood by those of skill in the art that the intramedullary nail  102  may have any number of openings  110  extending therethrough in any of a variety of configurations. 
     Current bone fixation systems include an intramedullary nail that is attached, for insertion, to a separate insertion device via screws which are removed upon insertion of the intramedullary nail into the bone so that the insertion device may be separated from the nail and removed from the body. The intramedullary nail  102  of the system  100  of the present embodiment, however, includes an insertion device  104  integrally formed with the nail  102  to simplify the insertion of the nail  102  and the removal of the insertion device  104  from the nail  102 . The fixation system  100  may be formed of a material such as, for example, PEEK, and may be injection molded together so that the connection points  106  are formed by a flow of material between the intramedullary nail  102  and the insertion device  104  during the molding process. 
     The insertion device  104  includes a base portion  122  and a handle member  124  extending therefrom. The guide channels  108  extend through the base portion  122  in alignment with the openings  110  of the intramedullary nail  102 . In other words, each of the guide channels  108  extends along an axis which is coaxial with the axis of a corresponding one of the openings  110  of the intramedullary nail  102 . In the embodiment shown, the insertion device  104  includes three guide channels  108 —an axis of a first channel  108   a  is aligned with the first axis  111   a  of the first opening  110   a , an axis of a second channel  108   b  is aligned with the second axis  111   b  of the second opening  110   b  and an axis of a third channel  108   c  is aligned with the third axis  111   c  of the third opening  110   c . It will be understood by those of skill in the art, however, that the insertion device  104  may have any number of guide channels  108  so long as the number of guide channels  108  corresponds to the number of openings  110  of the intramedullary nail  102 . 
     In a further embodiment, the insertion device  104  includes a stop element  140  extending from a portion thereof. In one exemplary embodiment, as shown in  FIGS. 1 and 3 , the stop element  140  is configured as a fin-shaped protrusion extending from a portion of the insertion device  104  substantially opposing the handle member  124 . The stop element  140  may be shaped such that a bone-facing surface  142  thereof extends substantially parallel to the insertion device facing surface  128  of the intramedullary nail  102 . 
     The base portion  122  of the insertion device  104  is connected to the head portion  120  of the intramedullary nail  102  at a plurality of connection points  106 . The base portion  122  is connected to the head portion  120  of the intramedullary nail  102  such that an intramedullary nail facing surface  126  of the base portion  122  is separated from an insertion device facing surface  128  of the head portion of the intramedullary nail  102  by a gap of a predetermined distance. In one exemplary embodiment, the nail facing surface  126  may be separated from the insertion device facing surface  128  by a distance of between approximately 0.8 mm and 1.0 mm. It will be understood by those of skill in the art, however, that this distance is exemplary only, and that the distance between the nail facing surface  126  and the insertion device facing surface  128  may vary depending on a desired length of the connection points  106 . A size of the gap may, for example, be determined by a desired nail insertion depth. Additional factors for determining the size of the gap may include material properties and manufacturing techniques (e.g., mold design and capabilities). 
     The system  100  may include any number of connection points  106  connecting the insertion device  104  and the intramedullary nail  102 . In a preferred embodiment, however, the system  100  includes two or three connection points  106  at which the base portion  122  is connected to the head portion  120  of the intramedullary nail  102 . The connection points  106  in this embodiment extend from an outermost edge of the insertion device facing surface  128  to the nail facing surface  126  of the base portion  122  of the insertion device  104  so that the connection points  106  do not interfere with the guide channels  108  and the openings  110  of the insertion device  104  and the intramedullary nail  102 , respectively. It will be understood by those of skill in the art, however, that the configuration of the connection points  106  described above is exemplary only may vary depending on the manufacturing process and material properties. 
     The connection points  106  are sized and shaped so that, upon implantation of the intramedullary nail  102  into the bone, the connection points  106  may be broken by pulling the insertion device  104  toward a user of the device while angling, rotating or otherwise moving the insertion device  104  relative to the intramedullary nail  102 . In one exemplary embodiment, a cross-sectional thickness of a portion of the connection points  106  to be broken may range from between 0.4 mm to 1.2 mm. The connection points  106  may have any of a variety of sizes and dimensions, however, so long as the connection points  106  are configured to facilitate manual breakage thereof by a user once the insertion procedure has been completed. In one exemplary embodiment, a distance between the insertion device facing surface  128  and the nail facing surface  126  and the structure of the connection points  106  is defined via notches  130  formed between the base portion  122  of the insertion device  104  and the head portion  118  of the intramedullary nail  102 . The notches  120  are sized and shaped to define the distance between the surfaces  128 ,  126  and to define the size and shape of the connection points  106  to facilitate breakage of the connection points  106  at a desired point therealong when subjected to a predetermined force. For example, as shown in  FIG. 4 , the notches  130  are formed so that the connection points  106  are more robust (thicker) on the side of the base portion  122  of the insertion device  104  than on the side of the intramedullary nail  102 . Thus, the connection points are configured to break closer to the intramedullary nail  102  than to the insertion device  104 . Thus, as will be understood by those of skill in the art, the size and shape of the notches  130  and/or the connection points  106  predetermines a breaking point of the connection points  106 . In one exemplary embodiment, as described above, the notches  130  and the connection points  106  are sized and shaped to facilitate breakage of the connection points  106  so that, upon breakage, no portion of the intramedullary nail  102 , and/or portions of the connection points  106  that remain connected thereto, protrudes beyond an exterior surface of the bone. Also, as would be understood by those skilled in the art, any small protrusion from the nail  102  remaining at a connection point  106  may be filed down or otherwise removed or smoothed as desired. 
     Due to the breakable (e.g., “fragile”) nature of the connection points  106 , the intramedullary nail  102  may be inserted into the bone with drill guides inserted into the guide channels  108  and the openings  110  of the insertion device  104  and the intramedullary nail  102 , respectively. In this exemplary embodiment, the fixation system  100  may be pre-assembled with the drill guides inserted through the first and second guide channels  108   a ,  108   b  and the openings  110 . Insertion of the drill guides in these channels  108   a ,  108   b  and their corresponding openings  110  does not interfere with the implantation of the intramedullary nail  102 . The guide channel  108   c  may be left open during the initial implantation of the intramedullary nail  102 . When the drill guides are inserted into the guide channels  108   a ,  108   b  and the corresponding openings  110 , the drill guides extend across the space between the insertion device facing surface  128  and the nail facing surface  126 , restricting movement between the insertion device  104  and the nail  102  and preventing breakage of the connection points  106 . 
     According to an exemplary surgical technique for fixing a fracture of a bone, such as the distal radius, using the system  100 , an entry hole is drilled through the styloid process of the radius using known methods in the art. For example, a guide may be placed over the radial styloid and a guide wire may be inserted therethrough. A cannulated drill may be slid over the guide wire to drill the entry hole. Once the entry hole has been created, the shaft portion  120  of the intramedullary nail  102  is inserted through the entry hole and moved into the medullary canal of the bone by gripping the handle member  124  of the insertion device  104 . As described above, to provide additional stability between the insertion device  104  and the intramedullary nail  102 , the intramedullary nail  102  is inserted into the bone with the drill guides inserted into the guide channels  108  and the openings  110  of the insertion device  104  and the intramedullary nail  102 , respectively. As would be understood by those skilled in the art, the curvature of the intramedullary nail  102  is selected to facilitate insertion of the intramedullary nail  102  into the medullary canal via the entry hole in the styloid process. 
     The intramedullary nail  102  is inserted into the bone until the base portion  122  of the insertion device contacts an exterior surface of the bone and/or the stop element  140  of the insertion device  104  contacts the exterior surface of the bone. A drill is then passed through the drill guides in the first and second drill channels  108   a ,  108   b  to drill holes in the bone, in alignment with the openings  110   a ,  110   b . Once the holes have been drilled, the drill guides are removed and bone fixation elements (e.g., bone screws) are inserted through the guide channels  108   a ,  108   b  until head portions of the bone fixation elements engage the openings  110   a ,  110   b  and shaft portions of the bone fixation elements extend through the drilled holes into the bone. Upon fixing the intramedullary nail  102  relative to the bone via the bone fixation elements in the first and second openings  110   a ,  110   b , a drill guide may be inserted through the third guide channel  108   c  and the third hole  110   c  in alignment with the axis of the third hole  110   c . The drill guide may then be removed from the third guide channel  108   e  and a bone fixation element inserted through the third opening  110   c  so that the bone fixation element extends across the fracture site of the bone, providing further stability to the fracture fixation. In one exemplary embodiment, the bone fixation elements may be locking screws having threaded head portions that thread themselves into the material (e.g., PEEK) of the openings  110  to lock the screws relative thereto. 
     It will be understood by those of skill in the art that the above described steps regarding the drilling of holes in the bone and the insertion of bone fixation elements through the drilled holes is exemplary only and may differ according a number and position/orientation of openings  110  through the intramedullary nail  102 . Once bone fixation elements have been inserted through a desired number of openings  110  in a desired configuration, the insertion device  104  is manually removed by breaking the connection points  106 . In particular, the connection points  106  may be broken by angling, rotating or otherwise moving the insertion device  104  relative to the intramedullary nail  102 . The insertion device  104  thus “snaps off” of the intramedullary nail  102  so that the insertion device  104  is decoupled from the intramedullary nail  102 , leaving the intramedullary nail  102  implanted within the medullary canal of the bone. As described above, notches along a desired portion of the connection points  106  may facilitate breaking of the connection points  106  at a desired point therealong to prevent protrusion of any portion of the intramedullary nail  102  and/or connection point  106  beyond an exterior surface of the bone and damage to any surrounding tissue. 
     As shown in  FIG. 5 , a bone fixation system  200  according to another exemplary embodiment may be substantially similar to the system  100  described above, comprising an intramedullary nail  202  integrally formed with an insertion device (not shown) and connected to one another via connection points (not shown). The connection points may be formed substantially as described above with respect to the system  100 . Similarly to the intramedullary nail  102 , the intramedullary nail  202  may include a head portion  218  and a shaft portion  220 . The shaft portion  220 , however, is not formed of the same material as the remainder of the system (e.g., PEEK) but may be formed of a wire  232  extending therefrom. In one exemplary embodiment, the wire  232  may be formed of a stainless steel, the wire  232  extending from a first end  234  embedded within the head portion  218  toward a second end  236 . In another embodiment, during manufacturing of the system  100 , the wire  232  may be immersed in PEEK so that the wire is coated with the PEEK material. 
     The insertion device may be substantially similar to the insertion device  104  described above, comprising a base portion and handle extending therefrom. The base portion includes a plurality of guide channels extending therethrough to align with openings of the connected intramedullary nail  202 . In one exemplary embodiment, axes of the guide channels are aligned with a corresponding one of a first axis  211   a  of a first opening  210 , a second axis  211   b  of a second opening  210  and a third axis  211   c  of a third opening  210  so that holes corresponding to the openings  210  of the intramedullary nail  202  may be drilled via a drill inserted through the guide channels. The openings  210  may be configured in a manner substantially similar to the openings  110  of the system  100 . 
     The system  200  may be used in a manner substantially similar to the system  100 . Thus, when the system  200  is used to treat a fracture of the distal radius, the second end  236  of the wire  232  may be inserted through an entry hole drilled in the styloid process until the wire  232  is inserted into a medullary canal of the distal radius. As discussed above, in regard to the system  100 , once implanted, the head portion  218  of the intramedullary nail  202  may extend through the distal end of the bone (e.g., distal radius) and the wire  232  may extend toward a proximal end of the bone. Holes may be drilled into the bone along axes  211   a - 211   c  so that bone fixation elements  212  may be inserted therealong into the bone, fixing the intramedullary nail  202  to the bone and/or providing further stabilization of the bone fracture. Upon implantation and fixation of the intramedullary nail  202 , the insertion device is “snapped off” by breaking the connection points. 
     It will be understood by those of skill in the art that modifications and variations may be made in the structure and methodology of the present embodiment, without departing from the spirit or scope of the embodiments. Thus, it is intended that the present embodiments cover the modifications and variations of these embodiments provided that they come within the cops of the appended claims and their equivalents.