Abstract:
An adjustable angle targeting device in one embodiment includes a holding member with a spherical upper surface and a lower surface, a first rotational alignment member for rotationally aligning an intramedullary nail with the holding member, a bore extending through the holding member and including a circular lower portion opening to the lower surface and a slot shaped upper portion opening to the upper surface, the slot having a length greater than the diameter of the circular lower portion, and a holding bolt for insertion through the bore and including (i) a shaft portion having a length greater than the length of the bore and a diameter less than the diameter of the circular lower portion, (ii) a coupling portion for coupling with the intramedullary nail and axially aligning the intramedullary nail, and (iii) a head with a bottom surface shaped complementary to the upper surface of the holding member.

Description:
FIELD  
       [0001]    The present invention relates to implantation and fixation of intramedullary nails and, more particularly, to a bone fastener targeting device and method of use for implantation and fixation of an intramedullary nail 
       BACKGROUND  
       [0002]    Intramedullary nails of the type used herein have two or more spaced holes or bores that extend diametrically across the intramedullary nail. These holes or bores are formed in the nail to accept or allow bone screws or fasteners to extend therethrough in order to fix the intramedullary nail to a bone or various bone fragments for the healing process. Since the fasteners are installed after the intramedullary nail has been inserted into the patient, such bone screw holes or bores are said to be “blind” in terms of bone-drilling alignment that must be achieved. Since the intramedullary nail is implanted into the patient, a problem exists with assuring correct alignment for drilling through the bone in order that a screw placed through the drilled hole also goes through a correct hole of the intramedullary nail. 
         [0003]    Because of this problem, many devices have been devised that aid in assuring correct alignment of bone screws and the intramedullary nail. It has been recognized by inventors of these devices that one method of determining where the intramedullary nail is located within the bone is to manufacture the device from radiolucent materials that allow radiographs to be made. In connection with this problem, other devices have been designed to pivot out of the way to allow radiographs to be made. Additionally, surgeons often also use external fixation devices to maintain alignment and length. 
         [0004]    In view of the above, what is thus needed is an improved system of targeting bone fasteners for alignment with holes in the intramedullary nail. 
       SUMMARY  
       [0005]    In one embodiment, an adjustable angle targeting device includes a holding member with a spherical upper surface and a lower surface, a first rotational alignment member for rotationally aligning an intramedullary nail with the holding member, a bore extending through the holding member and including a circular lower portion opening to the lower surface and a slot shaped upper portion opening to the upper surface, the slot having a length greater than the diameter of the circular lower portion, and a holding bolt for insertion through the bore and including (i) a shaft portion having a length greater than the length of the bore and a diameter less than the diameter of the circular lower portion, (ii) a coupling portion for coupling with the intramedullary nail and axially aligning the intramedullary nail, and (iii) a head with a bottom surface shaped complementary to the upper surface of the holding member. 
         [0006]    In another embodiment, an intramedullary nail targeting kit includes a frame, a holding member supported by the frame, the holding member including a bore with a slot portion and a circular portion, a coupling device configured to extend through the bore and to pivot with respect to the holding member within the slot portion and about the circular portion of the bore in a pivot plane, a drill guide supported by the frame and having a longitudinal axis extending within the pivot plane, and a plurality of intramedullary nails, each of the plurality of intramedullary nails including a coupling portion for coupling with the coupling device and a rotational alignment member for rotational alignment with the coupling device. 
         [0007]    In yet another embodiment a method of targeting an intramedullary nail includes selecting an intramedullary nail, rotationally aligning a bore axis of the intramedullary nail within a pivot plane defined by a slot portion and a circular portion of a bore in a holding member, positioning a portion of a coupling member within the slot portion and the circular portion of the bore, coupling the intramedullary nail with the positioned coupling member in a fixed axial relationship, rotationally fixing the rotationally aligned intramedullary nail with respect to the pivot plane, pivoting the coupled coupling member and intramedullary nail within the pivot plane, aligning the bore axis with a drill guide axis to target the intramedullary nail, and clamping the targeted intramedullary nail. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0008]      FIG. 1  depicts a perspective view of a targeting system including a targeting device, a coupler, a coupling member and two intramedullary nails having different nail angles in accordance with principles of the invention; 
           [0009]      FIG. 2  depicts a cross sectional view of the targeting device of  FIG. 1  showing a holder with a bore including a slot shaped upper portion opening to a spherically shaped upper surface and a circular lower portion, and a drill guide; 
           [0010]      FIGS. 3 and 4  depict partial perspective views of the targeting device of  FIG. 1  showing the holder with a slot shaped upper bore portion and circular lower bore portion with a key in the form of a flat surface; 
           [0011]      FIG. 5  depicts a cross sectional view of the coupling member of  FIG. 1  which in this embodiment is a bolt having a head with a spherically shaped lower surface, and a shaft with a threaded portion; 
           [0012]      FIG. 6  depicts a top perspective view of the coupler of  FIG. 1 , which is a component along with the holder of  FIGS. 3 and 4  of a holding member, with a slot shaped upper bore portion and a circular lower portion; 
           [0013]      FIG. 7  depicts a cross sectional view of the coupler of  FIG. 1  showing the flat side of the slot tapering to the circular lower portion; 
           [0014]      FIG. 8  depicts a cross sectional view of the coupler of  FIG. 1  showing a curved end of the bore and a protuberance for rotationally aligning the coupler with an intramedullary nail; 
           [0015]      FIG. 9  depicts a bottom perspective view of the coupler of  FIG. 1  showing a tapered outer wall with a key in the form of a flat surface for rotationally aligning the coupler with the holder of  FIGS. 3 and 4  and two protuberances for rotationally aligning the coupler with an intramedullary nail; 
           [0016]      FIG. 10  depicts a cross sectional view of one of the intramedullary nails of  FIG. 1  showing a nail angle between the axis of the threaded upper portion of a bore and the axis of a fastener bore; 
           [0017]      FIG. 11  depicts a top plan view of the intramedullary nail of  FIG. 10  showing a head with two slots for rotationally aligning the intramedullary nail with the coupler of  FIG. 1 ; 
           [0018]      FIG. 12  depicts a cross sectional view of one of the intramedullary nails of  FIG. 1  showing a nail angle between the axis of the threaded upper portion of a bore and the axis of a fastener bore that is different from the nail angle of the intramedullary nail of  FIG. 10 ; 
           [0019]      FIGS. 13-15  depict the coupling member of  FIG. 1  used to clamp one of the intramedullary nails of  FIG. 1  to the coupler and targeting device of  FIG. 1 ; 
           [0020]      FIG. 16  depicts the clamped intramedullary nail of  FIG. 15  with the fastener bore axis out of alignment with the drill guide axis of the targeting device; 
           [0021]      FIGS. 17-19  depict pivoting of the axially aligned coupling member and intramedullary nail relative to the targeting device wherein the coupling member pivots within the slotted bore portion of the holding member and about the circular bore portion of the holding member to change the alignment of the fastener bore axis with respect to the drill guide axis of the targeting device while maintaining the rotational alignment of the coupling member and intramedullary nail relative to the targeting device; 
           [0022]      FIG. 20  depicts the clamped intramedullary nail of  FIG. 15  after aligning the fastener bore axis with the drill guide axis of the targeting device; 
           [0023]      FIG. 21  depicts the coupling member of  FIG. 1  used to clamp one of the intramedullary nails of  FIG. 1  to the coupler and targeting device of  FIG. 1 ; 
           [0024]      FIG. 22  depicts the clamped intramedullary nail of  FIG. 21  after aligning the fastener bore axis with the drill guide axis of the targeting device by locating the coupling member in the middle of the slotted bore of the holding member; and 
           [0025]      FIGS. 23 and 24  depict partial views of an alternative embodiment of a targeting device wherein the holding member includes a coupler component integrally formed with a holder component and markings on the spherical upper surface of the holding member to assist in aligning the drill guide axis with intramedullary nails having various nail angles. 
       
    
    
     DETAILED DESCRIPTION  
       [0026]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein by described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
         [0027]    A targeting system  100  is shown in  FIG. 1 . The targeting system  100  includes a targeting device  102 , a holding bolt  104 , a coupler  106 , and two intramedullary nails  108  and  110 . The targeting device  102  includes a frame  112  with a guide portion  114 . An arm  116  extends from the frame  112  and supports a holder  118 . 
         [0028]    With reference to  FIG. 2 , the guide  114  includes a drill guide  120  and a targeting guide  122 . The drill guide  120  and the targeting guide  122  have parallel longitudinal axes  124  and  126 , respectively. 
         [0029]    The holder  118  is shown in  FIGS. 2-4 . The holder  118  includes a spherically shaped upper surface  130  and a circular lower surface  132 . A bore  134  extends between the upper surface  130  and the lower surface  132 . A ledge  136  in the bore  134  separates an upper bore  138  from a lower bore  140 . The upper bore  138  opens to the upper surface  130  as an elongated slot as most clearly shown in  FIG. 3 . The lower bore  140  opens to the lower surface  132  in the form of a circular opening with the exception of a flat portion  142  that extends upwardly from the lower surface  132 . 
         [0030]    The holding bolt  104 , shown in  FIG. 5 , includes a shaft  150  and a head  152 . The shaft  150  includes a threaded portion  154 . A bore  156  extends completely through the shaft  150  and opens to the upper surface  158  of the head  152 . The lower surface  160  of the head  152  is spherically shaped on a radius complimentary to the radius of the spherical upper surface  130  of the holder  118 . 
         [0031]    The coupler  106  is shown in  FIGS. 6-9 . The coupler  106  includes a tapered outer wall  162  which terminates at a ledge  164 . The outer wall  162  is substantially circular in cross section with the exception of a flat portion  166 . Two protuberances  168  and  170  extend from a skirt  172  located below the ledge  164 . A bore  174  extends from the lower surface  176  of the skirt  172  to the upper surface  178  of the coupler  106 . The opening of the bore  174  to the lower surface  176  is circular while the opening of the bore  174  to the upper surface  178  forms an elongated slot  180 . The elongated slot  180  includes two end curves  182  and  184  that are formed with the same radius as the opening of the bore  174  to the lower surface  176 . Two sides  186  and  188  extend between the end curves  182  and  184 . The sides  186  and  188  taper inwardly and downwardly within the bore  174  as best seen in  FIG. 7 . 
         [0032]    The intramedullary nail  108  shown in  FIGS. 10 and 11  includes a shaft  190  with transaxial bores  192 ,  194 ,  196 , and  198 . A bore  200  extends along the length of the intramedullary nail  108 . The bore  200  includes a threaded portion  202  and opens to the head  204  of the intramedullary nail  108 . Two slots  206  and  208  are located in the head  204 . The bore  194  is configured to receive a lag screw (not shown) and is formed with a centerline  210  that intersects the centerline  212  of the threaded portion  202  at an angle α, also referred to herein as a nail angle, of about 125 degrees. The intramedullary nail  110  shown in  FIG. 12  is substantially identical to the intramedullary nail  108  with the exception that a bore  214  which is configured to receive a lag screw (not shown) is formed with a centerline  216  that intersects the centerline  218  of the threaded portion  220  at an angle β of about 130 degrees. 
         [0033]    With reference to the foregoing figures, the targeting system  100  may be used by initially preparing a femur to receive an intramedullary nail in accordance with a desired procedure. Once the surgical site is properly prepared, an intramedullary nail is selected based upon, in part, the angle between the axis of the femoral neck and the axis of the femoral diaphysis. For this example, the intramedullary nail  108  will be used. As with many of the actions described herein, the order of the actions may be varied. Thus, the selected intramedullary nail may first be implanted or the intramedullary nail may first be attached to the targeting device  102 . 
         [0034]    In either case, the protuberances  168  and  170  of the coupler  106  are aligned with the slots  206  and  208  on the head  204  of the intramedullary nail  108 . The protuberances  168  and  170  are sized to fit within the slots  206  and  208 . Accordingly, once the protuberances  168  and  170  are aligned with the slots  206  and  208 , the protuberances  168  and  170  are inserted into the slots  206  and  208 , respectively. 
         [0035]    Next, the holder  118  is aligned with the coupler  106 . More specifically, the flat portion  166  of the coupler  106  is aligned with the flat portion  142  of the holder  118 . The upper surface  178  of the coupler  106  is then inserted into the bore  134 . The height of the tapered outer wall  162  corresponds to the distance from the lower surface  132  of the holder  118  to the ledge  136  within the bore  134 . Additionally, the diameter of the ledge  164  is greater than the diameter of the lower bore  140  of the holder  118  and the diameter of the upper surface  178  is greater than the diameter of the bore  134  at the ledge  136 . Accordingly, as the upper surface  178  abuts the ledge  136 , the ledge  164  abuts the lower surface  132  of the holder  118  resulting in the configuration shown in  FIG. 13 . 
         [0036]    The bolt  104  is then inserted through the bore  134  of the holder  118  and through the bore  174  of the coupler  106  as shown in  FIG. 14 . Engaging the threaded portion  154  of the bolt  104  with the threaded portion  202  of the intramedullary nail  108  provides the configuration of  FIG. 15 . In  FIG. 15 , the intramedullary nail  108  is pulled tightly against the coupler  106  which is, in turn, held firmly against the holder  118 . The assembly is thus clamped between the head  152  of the bolt  104  and the head  204  of the intramedullary nail  108 . 
         [0037]    When the intramedullary nail  108  is clamped in this manner, the axis or centerline  210  of the bore  194  is not aligned with the axis  124  of the drill guide  120  as shown in  FIG. 16 . Alignment is enabled by backing the bolt  104  out of the threaded portion  202  to the position shown in  FIG. 17 . In  FIG. 17 , the system  100  is not tightly clamped. Accordingly, because the upper surface  130  of the holder  118  and the lower surface  160  of the head  152  are both spherically shaped with the same radius of curvature, the targeting device  102  and the coupler  106  may be pivoted in the direction of the arrow  222  with respect to the bolt  104  and the intramedullary nail  108 . The radius of curvature for the upper surface  130  of the holder  118  and the radius of curvature for the lower surface  160  of the head  152  need not be identical. Increased clamping surface, however, is realized as the radii of curvature are matched more closely. 
         [0038]    The bolt  104  thus moves along the slot  180  of the coupler  106  within the upper bore  138  of the holder  118 . The bolt  104  is thus pivoted with respect to the slot  180  as it pivots about the circular portion of the bore  174 . 
         [0039]    Pivoting the targeting device  102  and the coupler  106  in the direction of the arrow  222  pivots the protuberance  170  partially out of the slot  208  resulting in a gap  224  between the coupler  106  and the intramedullary nail  108  shown in  FIG. 18 . Once the targeting device  102  and the coupler  106  have been pivoted to the desired location along the slot  180 , the bolt  104  is threaded into the threaded portion  202  of the intramedullary nail  108  which provides the configuration of  FIG. 19 . In  FIG. 19 , the intramedullary nail  108  is again pulled tightly against the coupler  106  which is, in turn, held firmly against the holder  118 . The assembly is thus clamped between the head  152  of the bolt  104  and the head  204  of the intramedullary nail  108  with a different alignment between the targeting device  102  and the intramedullary nail  108 . 
         [0040]    Pivoting the targeting device  102  and the coupler  106  thus adjusts the alignment between the centerline  210  of the bore  194  and the axis  124  of the drill guide  120 . Consequently the length of the slot  180  limits the amount by which the alignment may be modified. In other words, the intersection of the axes defined by each of the end curves  182  and  184  with the axis  124  of the drill guide  120  define the limiting nail angles that can be aligned with the drill guide  120 . In this embodiment, the length of the slot  180  is selected such that when the shaft  150  of the bolt  104  is positioned against the end curve  182  as shown in  FIG. 19 , the centerline  210  of the bore  194  and the axis  124  of the drill guide  120  are aligned as shown in  FIG. 20 . 
         [0041]    If desired, flats may also be formed on the protuberances  168  and  170  to provide increased clamping surface. Additionally, the coupler  106  and the holder  118  may be formed as an integral holding member. When the coupler  106  and the holder  118  are formed as separate components of a holding member, the holder  118  may be manufactured from a metal material and the targeting device  102  formed from a carbon fiber or other radiolucent material. 
         [0042]    Coupling of the intramedullary nail  110  is accomplished in significantly the same manner as discussed above with respect to the intramedullary nail  108 . The axis or centerline  216  of the bore  214 , however, is oriented at a larger angle with respect to the axis of the threaded portion  220  than the centerline  210  of the bore  194  is oriented with respect to the axis of the threaded portion  202 . Thus, once the intramedullary nail  110  is positioned with the holding bolt  104  located in the center of the slot  178  as shown in  FIG. 21 , the centerline  216  of the bore  214  is aligned with the axis  124  of the drill guide  120  as shown in  FIG. 22 . 
         [0043]    As is evident from  FIG. 21 , the slot  180  is configured in this embodiment to provide further pivoting of the targeting device  102  and coupler  106  in the direction of the arrow  228 . Accordingly, the system  100  may further include an intramedullary nail (not shown) with an angle of about 135 degrees between a bore axis and the axis of a threaded portion which could be aligned with the axis  124  of the drill guide  120 . In alternative embodiments, the targeting system may be configured to align intramedullary nails configured within a larger or smaller range of angles. 
         [0044]    In alternative embodiments, the centerline  210  of the bore  194  and the axis  124  of the drill guide  120  are automatically aligned as the intramedullary nail  108  is clamped to the targeting device  102  by the holding screw  104 . In such embodiments, a base clamping angle between a plane defined by the clamping component of the coupler  106  and the axis  124  of the drill guide  120  is established. A nail clamping angle between a plane defined by the clamping component of the intramedullary nail  108  and the axis  212  of the threaded portion  202  is then selected such that the sum of the base clamping angle and the nail clamping angle is equal to the angle between the axis  212  of the threaded portion  202  and the centerline  210  of the bore  194 . 
         [0045]    By way of example, a base clamping angle may be 40 degrees. Thus, a component against which the intramedullary nail  108  is to be clamped, such as the lower surface  176  of the skirt  172  or the bottom of the protuberances  168  and  170 , is configured to define a plane which intersects the axis  124  of the drill guide  120  at an angle of 40 degrees. Since the intramedullary nail  108  has a nail angle of 125 degrees, the nail clamping angle must be 85 degrees. Accordingly, the component which clamps against the coupler, such as the upper surface of the head  204  if the lower surface  176  is a clamping component, or the bottom of one or both of the slots  206  and  208  if the bottom of one or both of the protuberances  168  and  170  is a clamping component, is configured to define a plane which intersects the axis  212  of the threaded portion  202  at an angle of 85 degrees. 
         [0046]    Thus, when the clamping component of the intramedullary nail  108  is clamped against the clamping component of the coupler  106 , the intramedullary nail  108  will be forced into a position whereat the centerline  210  of the bore  194  and the axis  124  of the drill guide  120  are aligned. For intramedullary nails having different nail angles, each intramedullary nail may be provided with a different nail clamping angle for use with a single coupler, or a variety of couplers with different base clamping angles may be used with intramedullary nails with different nail angles but the same nail clamping angle to provide automatic alignment. In these alternative embodiments, the intersection of the axes defined by each of the end curves  182  and  184  with the axis  124  of the drill guide  120  may be selected to be larger than the nail angles to be used with the device. 
         [0047]    An alternative embodiment of a targeting device  230  is shown in  FIG. 23 . The targeting device  230  includes an integrally formed holding member  232  with a spherically curved upper surface  234  and a slot  236 . Markings  238 ,  240 , and  242  are located on the spherical surface  234 . The targeting device  230  is in all other ways substantially identical to the targeting device  102 . The markings  238 ,  240 , and  242  provide references for aligning the bore axes of three different intramedullary nails (not shown) with the drill guide (not shown) of the targeting device  230 . By way of example, aligning the head  152  of the bolt  104  with the mark  238  may align the bore axis of a 125 degree intramedullary nail as shown in  FIG. 24 . Similarly, the marks  240  and  242  may be used to align a 130 degree intramedullary nail and a 135 degree intramedullary nail, respectively. Although the present invention has been described with respect to certain preferred embodiments, it will be appreciated by those of skill in the art that other implementations and adaptations are possible. Moreover, there are advantages to individual advancements described herein that may be obtained without incorporating other aspects described above. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.