Patent Publication Number: US-2019175233-A1

Title: Monofix Nail

Description:
PRIORITY CLAIM 
     The present application is a Divisional Application of pending U.S. patent application Ser. No. 13/523,227 filed on Jun. 14, 2012; which claims priority to U.S. Provisional Application Ser. No. 61/500,284 filed on Jun. 23, 2011 and U.S. Provisional Application Ser. No. 61/531,417 filed on Sep. 6, 2011. The disclosure of the above applications is incorporated herein by reference. 
    
    
     BACKGROUND 
     Intramedullary nails are inserted into medullary canals of long bones to fix fractures thereof. Once inserted into a medullary canal, an intramedullary nail is generally fixed therein by inserting one or more bone fixation elements through locking holes extending transversely through the nail. The curvature of a medullary canal often deviates from the initial curvature along which the nail extends so that the nail is deformed during insertion. This deformation moves the transverse locking holes away from their expected position making it difficult to drill the holes required to insert the locking screws therein. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an intramedullary device, which includes an intramedullary nail extending along a longitudinal axis from a proximal end to a distal end, the nail including a channel extending longitudinally therethrough and an opening extending laterally through a wall thereof proximate the distal end, the channel including a ramped surface along a distal portion thereof opposite the opening, and a wire extending along a longitudinal axis from a proximal end to a distal end, the wire sized and shaped to be inserted into the channel of the nail such that the distal end engages the ramped surface to extend through the opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of a device according to an exemplary embodiment of the present invention; 
         FIG. 2  shows a longitudinal cross-sectional view of the device according to  FIG. 1 ; 
         FIG. 3  shows a longitudinal cross-sectional view of a portion of an intramedullary nail of the device according  FIG. 1 ; 
         FIG. 4  shows a longitudinal cross-sectional view of a distal portion of the device according to  FIG. 1 ; 
         FIG. 5  shows an enlarged perspective view of a distal end of a fixation wire extending out of a distal hole of the intramedullary nail, according to the device of  FIG. 1 ; 
         FIG. 6  shows a perspective view of a distal end of a fixation wire according to an alternate embodiment of the present invention; 
         FIG. 7A  shows a longitudinal cross-sectional view of a driving tool coupled to the fixation wire according to the device of  FIG. 1 ; 
         FIG. 7B  shows a longitudinal cross-sectional view of a removal tool coupled to the fixation wire according to the device of  FIG. 1 ; 
         FIG. 8  shows a longitudinal cross-sectional view of a proximal portion of the intramedullary device of  FIG. 1 ; 
         FIG. 9A  shows a longitudinal cross-sectional view of the proximal portion of an intramedullary device including an alternate embodiment of an end cap; 
         FIG. 9B  shows a perspective view of a first alternate embodiment of the proximal portion of an intramedullary device; 
         FIG. 9C  shows a perspective view of a first alternate embodiment of the proximal portion of an intramedullary device; 
         FIG. 9D  shows a perspective view of a first alternate embodiment of the proximal portion of an intramedullary device; 
         FIG. 10  shows a longitudinal cross-sectional view of a proximal portion of an intramedullary device according to a further exemplary embodiment of the present invention; and 
         FIG. 11  shows a longitudinal cross-sectional view of a proximal portion of an intramedullary device according to another exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention relates to bone treatment devices and, in particular, relates to an intramedullary device. Exemplary embodiments of the present invention describe an intramedullary device including an intramedullary nail and a fixation wire inserted into a channel of the nail such that a distal end of the wire extends out of a distal hole of the nail. Thus, the intramedullary nail may be fixed to the bone from within the nail via the wire such that additional incisions and bone drilling are not required. It should be noted that the terms “proximal” and “distal,” as used herein refer to a direction toward (proximal) and away from (distal) a surgeon or other user of the device. 
     As shown in  FIGS. 1-9 , an intramedullary device  100  comprises an intramedullary nail  102  and a fixation wire  104 , which is passed through the intramedullary nail  102  to a distal hole  106  including a ramped surface angled to engage a wire and pass it out of the nail  102  as will be described in more detail below to fix the nail  102  at a desired location within a bone. The intramedullary nail  102  includes a channel  108  longitudinally therethrough such that the distal hole  106  extends through a transverse wall  110  of the nail  102  from an interior of the nail  102  defined by the channel  108  to an exterior of the nail  102 . A distal surface of the distal hole  106  is ramped as described below to engage the distal end of the wire  104  and guide the wire  104  away from the longitudinal axis of the nail  102  out of the distal hole  106 . Thus, the fixation wire  104  passes through the channel  108  with a distal end  112  of the wire  104  exiting the nail  102  via the distal hole  106  angled relative to a longitudinal axis of the nail  102  to penetrate bone adjacent to the transverse surface of the nail  102  fixing the nail  102  within the bone. The wire  104  may include a self tapping end so that the nail  102  may be fixed to the bone from within the nail  102  (i.e., without requiring the predrilling of a hole to receive the wire). Thus, a location of the distal hole  106  after insertion of the nail  102  into the bone does not need to be identified and drilled from outside the body. 
     A shown in  FIGS. 1-4 , the intramedullary nail  102  extends along a longitudinal axis from a proximal end  114  to a distal end  116  and includes the channel  108  extending therethrough along the longitudinal axis. The distal hole  106  extends transversely through the wall  110  proximate the distal end  116 . The channel  108  includes a ramped surface  118  extending along a portion thereof corresponding to a position of the distal hole  106  such that when the fixation wire  104  passes through the channel  108 , the distal end  112  of the wire  104  slides along the ramped surface  118  and is guided through the distal hole  106  to an exterior of the nail  102 . The distal hole  106  may be elongated along a length of the nail  102  such that the distal end  112  of the wire  104  may easily pass transversely therethrough while also providing sufficient access for manufacturing (e.g., milling) the ramped surface  118 . A distal portion  120  of the channel  108  distal of the ramped surface  118  and the distal hole  106  may have a smaller diameter than a proximal portion  122  of the channel  108  proximal of the ramped surface  118  such that the channel  108  may still accommodate a guide wire therethrough. In addition, a portion  142  of the channel  108  extending about the distal hole  106  may also have a slightly larger cross-section than the proximal portion  122  such that the distal end  112  of the wire  104  does not come into contact therewith as it is being driven (e.g., rotated) into the bone. In other words, a portion of the wall  110  surrounding the distal hole  106  may have a smaller thickness that a remaining portion of the wall  110 . 
     The channel  108  may also include a shoulder  154  distally of a proximal opening  152  thereof. The shoulder  154  extends radially inward such that a diameter of the channel  108  proximal of the shoulder  154  is larger than a diameter distal of the shoulder  154 . Thus, as will be described in further detail below, the shoulder  154  may engage a portion of the wire  104  and/or a portion of a driving tool to prevent the wire  104  from being inserted any further distally through the channel  108 . 
     The nail  102  according to this embodiment of the invention includes a proximal locking hole  124  extending through the wall  110  proximate the proximal end  114  of the nail  102 . The proximal locking hole  124  extends through the wall  110  along a central axis angled with respect to the longitudinal axis of the nail  102 . The proximal locking hole  124  opens to a chamber formed at a proximal end of the nail  102  so that it is accessible from a proximal opening  152  of the channel  108  at the proximal end  114  so that a bone fixation element  126  may be through the proximal locking hole  124  via the proximal opening  152  so that a shaft  128  of the bone fixation element  126  extends into the bone surrounding the channel  108 . Thus, the shaft  128  of the bone fixation element  126  extends out of the nail  102  into the bone along the central axis of the proximal locking hole  124 , at an angle relative to the longitudinal axis of the nail  102 . An interior surface of the proximal locking hole  124  may be threaded to engage a threading of a head portion of the bone fixation element  126  to lock the bone fixation element  126  in a desired position in the nail  102  as would be understood by those skilled in the art. 
     The nail  102  may additionally include conventional locking holes extending transversely through the nail  102  to receive additional bone fixation elements therethrough. For example, the nail  102  may include a conventional locking hole  130  extending transversely through a proximal or distal portion of the nail  102 . The conventional locking holes  130  may be located using conventional aiming arms known in the art so that a corresponding hole may be pre-drilled into the bone for the insertion of additional bone fixation elements therethrough, as would be understood by those of skill in the art. It will also be understood by those of skill in the art, that a hole may also be pre-drilled into the bone to correspond to the proximal locking hole  124 . Alternatively, the bone fixation element  126  may include a self-drilling tip. 
     The intramedullary device  100  may further comprise an end cap  150  couplable to the proximal end  114  of the intramedullary nail  102  to close the proximal opening  152  of the channel  108 . The end cap  150  may be received within the proximal opening  152  and threadedly engaged or otherwise locked therein. The end cap  150  may thus include an engagement structure such as, for example, a hexagonal recess, for engaging an instrument which drives the end cap  150  into the proximal opening  152 . In a further embodiment, as shown in  FIG. 9A , an end cap  150 ′ may be substantially similar to the end cap  150  but further includes a distally extending portion  151 ′ such that when the end cap  151 ′ is received within the proximal opening  152 , the portion  151 ′ prevents the wire  104  from moving proximally relative to the nail  102 . 
     The wire  104  extends through the opening  152  into the channel  108  and passes therethrough along the longitudinal axis of the nail  102 . The ramped portion  118  of the channel  108  is formed on a side of the channel  108  opposite the distal hole  106  and angled toward the distal hole  106  so that, as the distal end  112  engages the ramped portion  118 , the distal end of the wire  104  passes into the distal hole  106 . As indicated above, the distal end  112  may include a self-drilling tip  134  (shown in  FIG. 5 ) so that as the wire  104  passes out of the nail  102 , the self-drilling tip  126  permits the distal end  112  to be inserted into the surrounding bone. A diameter of the distal end  112  of the wire  104  may be larger than a diameter of a remaining length of the wire  104  such that a natural inflection point is formed along the wire  104  at the place where the distal end  112  meets the remaining length of the wire  104 . For example, the distal end  112  may have a diameter of approximately 4.0 mm while the remaining length of the wire  104  has a diameter of approximately 3.2 mm. Thus, when the distal end  112  comes into contact with the ramped portion  118 , the distal end  112  bends at this inflection point so that it is angled toward the distal hole  106  such that the distal end  112  extends through the hole  106  and into the surrounding bone. In another embodiment, as shown in  FIG. 6 , a wire  104 ′ has a distal end  112 ′ including a threaded conical tip  136 ′ in addition to a self-drilling portion  134 ′ immediately proximal thereto to provide improved engagement with the bone and increase a fixation stability thereof. 
     As shown in  FIG. 7A , the proximal end  132  of the wire  104  according to this embodiment includes an engagement portion  138  sized and shaped to engage a portion of a driving tool  145  which may be used to rotate the wire  104  to drive the distal end  112  of the wire  104  distally through the distal hole  106  and into bone. The engagement portion  138  may be, for example, hexagonal to engage a corresponding hexagonal portion of the driving tool  145  or may have any other shape which will non-rotatably mate with an end of the driving tool, as would be understood by those skilled in the art. As shown in  FIG. 7B , the proximal end  132  may also include a threaded portion  140  distally of the engagement portion  138  to engage a removal tool  146 . The threaded portion  140  includes threading along an outer surface of the wire  102  configured to engage corresponding threading  144  along a portion of the removal tool  146 . The removal tool  146  may be, for example, a longitudinal element including threads  144  along an interior surface of a distal end  148  thereof for coupling to the threaded portion  138  of the wire  104  such that, once the removal tool  146  and the wire  104  are coupled, the removal tool  146  may be both rotated to rotate the wire  104  and pulled proximally to draw the wire  104  proximally. If the self-drilling tip  126  of the wire  104  extends along the distal end  112  in a right side orientation (i.e., requiring a right side rotation to be drilled into the bone) the threads along the threaded portion  140  will be in a left orientation such that upon threadedly engaging the removal tool  146  to the threaded portion  140 , the user may continue to rotate the removal tool  146  to the left side to disengage the distal end  112  from the bone. Once the distal end  112  is disengaged from bone, the user may pull the removal tool  146  proximally to draw the wire  104  out of the channel  108 . 
     In one exemplary embodiment, a portion of a driving tool engaging the engagement portion  138  may be sized and shaped to engage the shoulder  154  of the channel  108  such that when the driving tool abuts the shoulder  154 , the driving tool and thereby the wire  104  is prevented from being moved any further distally relative to the nail  102 . In another embodiment, as shown in  FIGS. 8 and 9A , the wire  104  may include a stop  156  proximal of the engagement portion  138  and the threaded portion  140 , which extends radially outward and is sized and shaped to engage the shoulder  154 . Thus, when the stop  156  abuts the shoulder  154 , the wire  104  is prevented from moving any further distally relative to the nail  102 . 
     As shown in  FIG. 10 , an intramedullary device  200  according to a further embodiment of the present invention is substantially similar to the intramedullary device  100 , but further comprises an insert  260  which may be inserted into a channel  208  of an intramedullary nail  202  to prevent a wire  204  passed therethrough from migrating proximally once it has been inserted into the nail  202  to fix the nail  202  within a bone. The insert  260  may be sized and shaped to engage the channel  208 . For example, the insert  260  may threadedly engage the proximal end of the channel  208 . The insert  260  may further include a groove  262  extending therealong from a proximal end  264  thereof sized and shaped to permit a bone fixation element  226  to be inserted through a proximal locking hole  224  of the nail  202  after insertion of the insert  260  in the channel  208 . Upon positioning of the wire  204  within the channel  208 , as desired, the insert  260  is inserted into the channel  208  proximally of the wire and positioned therein such that the groove  262  is aligned with the proximal locking hole  224  of the nail  202 . The insert  260  prevents the wire  204  from moving proximally relative to the nail  202  while also permitting the bone fixation element  226  to be inserted through the proximal locking hole  224 . An end cap  250 , which may be substantially similar to the end cap  150 , may then engage the proximal end of the channel  208  to prevent bone ingrowth within the channel  208 . 
     As shown in  FIG. 11 , an intramedullary device  300  according to another embodiment of the present invention is substantially similar to the intramedullary device  200  described above except that the device  300  comprises an insert  360  which does not include a groove. Rather, a length of the insert  360  is selected so that, once inserted into a channel  308  of an intramedullary nail  302 , it does not interfere with a proximal locking hole  324  thereof. Thus, the insert  360  may be inserted into the channel  308  proximally of a wire  304  while still permitting a bone fixation element to be inserted through the proximal locking hole  324 , if desired. An end cap  350 , which may be substantially similar to the end caps  150 ,  250 , may then be inserted into the proximal end of the channel  308  to prevent bone ingrowth within the channel  308 . 
     According to a surgical technique using the intramedullary device  100 , the intramedullary nail  102  is inserted into a medullary canal of a bone along a guide wire inserted into the medullary canal of the bone and received within the channel  108  as would be understood by those skilled in the art. Once the intramedullary nail  102  has been positioned within the medullary canal as desired, the guide wire may be removed and the nail  102  is fixed within the bone by inserting the wire  104  into the channel  108 . As described above, the wire  104  is inserted distally into the channel  108  until the distal end  112  comes into contact with the ramped surface  118  and is directed laterally out of the distal hole  106 . As the distal end  112  passes through the distal hole  106  and comes into contact with the bone, the wire  104  may be rotated, for example, using a driving tool engaging the engagement portion  138  of the wire  104 . As described above, the wire  104  is inserted into the channel  108  until a portion of the driving tool or the stop  156  abuts the shoulder  154 , preventing the wire  104  from being moved any further distally relative to the nail  102 . Thus, the distal end  112  is prevented from penetrating the cortical wall. The self drilling tip  134  of the wire  104  permits the distal end  112  to extend into the bone, thereby fixing the nail  102  and the wire  104  relative thereto. It will be understood by those of skill in the wire  104 ′ may be used in a substantially similar manner as the wire  104 . 
     Once the distal end  112  has been inserted into the bone, the bone fixation element  126  is inserted through the proximal opening  152  into the proximal locking hole  124  to extend out of the nail  102  and engage the surrounding bone, fixing the proximal end  114  of the nail  102  in a desired position relative to the bone. As described above, the bone fixation element  126  is inserted into the proximal hole  124  along the central axis thereof such that the shaft  128  of the bone fixation element  126  extends at an angle relative to the longitudinal axis of the nail  102 . Where there are additional locking holes along the nail  102 , additional bone fixation elements may be guided and inserted therethrough using a conventional aiming arm attached to the proximal end  114  of the nail  102 . Once the intramedullary nail  102  has been fixed within the bone, the end cap  150  may be coupled to the proximal end  114  of the nail  102 . The end cap  150  may be received within the proximal opening  152  and rotated relative thereto to threadedly engage the proximal end  114  and close the proximal opening  152 , thus preventing bone ingrowth therein. In addition, as shown in  FIG. 8 , a bone fixation element  158  may be inserted through a proximal locking hole of the nail  102  positioned proximally of the proximal end  132  of the wire  104  to prevent the wire  104  from migrating proximally relative to the nail  102  once inserted to the desired position relative thereto. In another embodiment, as shown in  FIG. 9 , the end cap  150 ′ may be received within the proximal opening  152  such that the portion  151 ′ extends distally into the channel  108  proximally of the proximal end  132  of the wire  104 . The portion  151 ′ thus prevents the wire  104  from migrating proximally within the channel  108  once inserted therein in the desired position. The end cap  150 ′ may, for example, be utilized when only distal locking is required. 
     If, at any point, subsequent to the fixation the patient requires removal of the intramedullary nail  102 , the end cap  150  may be disengaged from the nail  102  and the bone fixation element  126  and/or the bone fixation element  158  removed from the proximal hole  124 . The distal end  148  of the removal tool  146  may be inserted into the channel  108  to engage the threaded portion  140  of the wire  104 . Once the removal tool  146  and the wire  104  have been coupled, the removal tool  146  may be rotated, in an opposite direction required for driving the wire  104 , to disengage the distal end  112  from the bone. The removal tool  146  may then be drawn proximally relative to the nail  102  to pull the wire  104  out of the channel  108  so that the nail  102  may be removed from the bone. It will be understood by those of skill in the art, however, that the distal end  112  of the wire  104  is only required to be drawn within the channel  108  to permit the intramedullary device  100  to be removed from the bone. A diameter of the distal end  112  is smaller than a diameter of the channel  108  such that distal end  112  does not contact the channel  108  as it is drawn therein facilitating this withdrawal. 
     The intramedullay device  200  may be used in a manner substantially similarly to the device  100 , as described above. However, prior to insertion of the bone fixation element  226  through the proximal locking hole  224  and after insertion of the wire  204  in the desired position, the insert  260  is inserted into the channel  208  proximally of the wire  204  to prevent the wire  204  from moving proximally relative to the nail  202 . The insert  260  is positioned such that the groove  262  is aligned with the proximal locking hole  224  to permit the bone fixation element  226  to be inserted therethrough. Upon insertion of the bone fixation element  226 , the end cap  250  may be coupled to the proximal end of the channel  208 . The intramedullary device  300  may be utilized in a substantially similar manner to the intramedullary device  200 , but does not require the insert  360  to be positioned in any particular orientation, as a length thereof is particularly selected such that the insert  360  does not interfere with the proximal locking hole  324 . 
     It will be apparent to those of skill in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. For example, any number of different distal holes and corresponding ramped surfaces may be provided (limited by the space in the channel  108 ) to accommodate multiple wires  104  and, similarly, a plurality of proximal holes  124  may be included separated from one another circumferentially about the longitudinal axis and/or along the longitudinal axis as desired to accommodate a plurality of bone fixation elements  126 . Thus, it is intended that the present invention cover the modifications and variations of the invention provided that they come within the scope of the appended claims and their equivalents.