Abstract:
An apparatus includes: a member configured to be received within an intramedullary canal, the member having an opening therethrough; a flexible elongate element sized to extend through the opening; a section having a first bone-engaging surface and a coupling structure for fixedly securing the section to the elongate element; and a further section having a bone-engaging surface and a coupling structure for fixedly securing the further section to the elongate element. In another form, an apparatus includes a first section having spaced first and second surface portions to engage a bone and a second section configured to extend into a bone. The first surface portion exerts a first force in a direction that is at an angle with respect to a force exerted by the second surface portion. Yet another form involves methods of using each apparatus.

Description:
BACKGROUND  
       [0001]     Embodiments of the present disclosure relate generally to devices and methods for accomplishing bone fixation, and more particularly in some embodiments, to devices and methods for reduction and fixation of a type IV supination external rotation injury.  
         [0002]     The treatment of fractures in the femur, tibia, fibula, and other bones often requires reduction and fixation of the bone. Further, for some injuries it is also helpful, or necessary, to limit the motion between the fractured bone and another bone. For example, in the treatment of a type IV supination external rotation injury, limiting but not completely preventing syndesmotic motion between the fibula and tibia can be advantageous. Although existing methods, devices, and surgical techniques have been generally adequate for their intended purposes, they have not been entirely satisfactory in all respects. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0003]      FIG. 1  is a diagrammatic fragmentary front view of an arrangement that embodies aspects of the present invention.  
         [0004]      FIG. 2  is a sectional view of the arrangement of  FIG. 1  taken along section line  2 - 2 .  
         [0005]      FIG. 3  is a diagrammatic, fragmentary side view of the arrangement of  FIG. 1 .  
         [0006]      FIG. 4  is a diagrammatic fragmentary front view of selected components of the apparatus  16  of  FIG. 1  in one operational position, and also shows part of a delivery device.  
         [0007]      FIG. 5  is a diagrammatic fragmentary front view, similar to  FIG. 4 , but showing a different operational position.  
         [0008]      FIG. 6  is a diagrammatic, fragmentary front view of several of the components of the arrangement of  FIG. 1  in a partially assembled state.  
         [0009]      FIG. 7  is a diagrammatic, fragmentary front view of the arrangement of  FIG. 1  in a partially assembled state.  
         [0010]      FIG. 8  is a diagrammatic, fragmentary side view similar to  FIG. 3 , but showing an alternative embodiment.  
         [0011]      FIG. 9  is a diagrammatic, fragmentary side view similar to  FIG. 3 , but showing an alternative embodiment.  
         [0012]      FIG. 10  is a diagrammatic, fragmentary front view similar to  FIG. 1 , but showing an alternative embodiment.  
         [0013]      FIG. 11  is a sectional view of the alternative embodiment shown in  FIG. 10  taken along section line  11 - 11 .  
         [0014]      FIG. 12  is a diagrammatic, fragmentary side view of the alternative embodiment of  FIG. 10 . 
     
    
     DETAILED DESCRIPTION  
       [0015]      FIG. 1  is a diagrammatic fragmentary front view of an arrangement  10  that embodies aspects of the present invention. The arrangement  10  includes a bone  12 , a bone  14 , and an apparatus  16 .  FIG. 2  is a sectional view of the arrangement  10  of  FIG. 1  taken along section line  2 - 2 .  
         [0016]     In the embodiment shown in  FIG. 1 , the bones  12  and  14  are parts of a human leg, where the bone  12  is a tibia and the bone  14  is a fibula. The bone  12  has intramedullary canal  18  and an exterior surface  20 . Similarly, the bone  14  has an intramedullary canal  22  and an exterior surface  23 . The bone  14  also has a fracture  24 . As best shown in  FIG. 2 , the fracture  24  has caused the bone  14  to have several bone fragments, some of which are visible at  26 ,  27 , and  28 .  
         [0017]     As shown in  FIGS. 1 and 2 , the apparatus  16  includes a member or intramedullary rod  30 . The intramedullary rod  30  is approximately cylindrical and configured to be received within the intramedullary canal  22  of the bone  14 . In the embodiment shown in  FIG. 1 , the intramedullary rod  30  includes a tapered portion  31  at its upper end that facilitates insertion of the intramedullary rod into the intramedullary canal  22 . As best shown in  FIG. 2 , the intramedullary rod  30  includes a central, longitudinal opening  32 . The opening  32  opens through the lower end of the intramedullary rod  30  and extends substantially the entire length of the intramedullary rod to a location near the upper end. The intramedullary rod  30  is made of a sturdy, surgical-grade material, and in particular is made of stainless steel. Two fixation members or bone screws  33  pass through respective, axially spaced, transverse, parallel openings in the intramedullary rod  30  to secure the rod to the bone  14 , as shown in  FIG. 1 . The transverse openings extend completely through the intramedullary rod  30  in a generally anterior to posterior direction. In the embodiment of  FIG. 1 , the bone screws  33  are made of stainless steel. As best illustrated in  FIG. 2 , the intramedullary rod  30  also includes a further transverse opening  34  located between the openings for bone screws  33  and extending in a generally lateral to medial direction. The opening  34  extends completely through the rod  30  and is angularly offset by approximately 90° with respect to the openings the bone screws  33  pass through.  
         [0018]     The apparatus  16  also includes an anchor  35 . The anchor  35  includes a curved, plate-like portion with a bone-engaging surface  36 . As best shown in  FIG. 2 , the bone-engaging surface  36  is curved to approximately match the curvature of the exterior surface  23  of the bone  14 . Thus, the bone-engaging surface  36  has a concave surface that engages the bone  14 . In the illustrated embodiment, the concave surface is approximately cylindrical and oriented so that it extends parallel to the longitudinal axis of bone  14 . The bone engaging surface  36  of the anchor  35  engages the exterior surface  23  of the bone  14  adjacent the bone fragments  26 - 28 . The bone-engaging surface includes a plurality of spaced surface portions that apply forces to the bone  14  in respective, different directions. By way of example, two of these surface portions are shown at  37  and  38  in  FIG. 2 . The spaced surface portions  37  and  38  apply respective forces in directions parallel to an axis  39  and an axis  40 . The axes  39  and  40  are at an angle with respect to one another. As shown best in  FIG. 2 , the anchor  35  also includes a projection  41  that projects outwardly from a central region of the surface  36 . The projection  41  is approximately cylindrical and extends into the bone  14 . A central longitudinal opening  42  in the projection  41  extends completely through the anchor  35 . The anchor  35  is made of a flexible, surgical-grade material, and in particular is made of cobalt-chrome.  FIG. 3  is a diagrammatic, fragmentary side view of the arrangement  10  of  FIG. 1 . As shown, the plate-like portion of the anchor  35  is approximately rectangular in shape with rounded comers.  
         [0019]     Referring again to  FIGS. 1 and 2 , the apparatus  16  also includes a flexible elongate element or cable  43 . The cable  43  is formed from flexible surgical-grade material, and in particular is made of cobalt-chrome. The cable  43  includes a portion  44 , a portion  45 , and a portion  46 . In the embodiment shown in  FIGS. 1 and 2 , the portions  44 - 46  of the cable  43  are of a substantially uniform diameter, and the cable  43  extends through the opening in the anchor  35 , the opening  34  in the intramedullary rod  30 , and portions of both of the bones  12 ,  14 . The cable  43  is substantially taut, but can flex. A ferrule  48  is fixedly secured to the portion  44  by crimping the ferrule to the cable  43 . The ferrule  48  is formed from a deformable surgical-grade material, and in particular is made of cobalt-chrome.  
         [0020]     A mechanism  50  is coupled to the portion  45 .  FIG. 4  is a diagrammatic fragmentary front view of selected components of the apparatus  16  of  FIG. 1  in one operational position, and also shows a portion  62  of a delivery device.  FIG. 5  is a diagrammatic fragmentary front view, similar to  FIG. 4 , but showing a different operational position.  
         [0021]     The mechanism  50  includes a section  52 . The section  52  includes a bone-engaging surface  53 . The section  52  is approximately cylindrical, has a rounded end surface  54 , and has an central longitudinal opening  56 . The opening  56  opens through the end of section  52  remote from surface  54  and extends to a location near surface  54 . The opening  54  has a diameter that is approximately the same as the outer diameter of the cable  43 . The end of section  52  near surface  54  is crimped to the end of cable portion  45  to couple the mechanism  50  to the cable  43 . The flexible nature of the cable  43  serves to permit limited pivotal movement of the mechanism  50  relative to the cable. The end of the portion  45  of the cable is bent to the position shown in  FIG. 5 . The portion  45  is deformable to other positions, as shown in  FIG. 4 , but is resilient such that it returns to the bent position shown in  FIG. 5 . The section  52  also includes a slot  58  through a sidewall having the bone-engaging surface  53  thereon. The slot  58  communicates with the opening  54  and extends axially from the left end of section  52 , as seen in  FIG. 4 , approximately half the length of section  52 . The section  52  also includes an end portion  60 . The end portion  60  is approximately cylindrical with a diameter less than the outer diameter of section  52 . The end portion  60  also includes an inclined surface  61  that extends at an angle with respect to a longitudinal axis of section  52 . In the current embodiment, the section  52  is made of cobalt chrome.  
         [0022]     In  FIGS. 4 and 5 , the cable  43  and coupling mechanism  50  are shown in combination with a cannula  62  that is part of a delivery device. The cannula  62  is made of a surgical-grade material, and in particular stainless steel. The cannula  62  is cylindrical with an opening  64  extending along its entire length. In the current embodiment, the diameter of the opening  64  is slightly larger than the outer diameter of the cable  43 , such that the cable  43  is slidable within the opening. Further, the diameter of the opening  64  is such that the end portion  60  of section  52  fits within the cannula, as shown in  FIG. 4 .  
         [0023]     The section  52  is moveable between two positions: an insertion position wherein the section  52  is approximately parallel with a longitudinal axis  66  of the cable  43  (as shown in  FIG. 4 ), and a bone-engaging position wherein the section  52  is at an angle with respect to the longitudinal axis  66  of the cable (as shown in  FIGS. 1 and 2 ). The bend in the cable  43  resiliently biases the section  52  toward the bone-engaging position. The slot  58  receives a piece of the cable  43  when the section  52  is in the bone-engaging position so that the section  52  can pivot with respect to the longitudinal axis of the cable.  
         [0024]     The apparatus  16  is utilized for reduction and fixation of the fracture  24  and for limiting syndesmotic motion between the bones  12 ,  14 . The apparatus  16  is assembled and implanted in the following manner. The intramedullary rod  30  is installed within the intramedullary canal  22  of the bone  14  extending across fracture  24  using known techniques. The intramedullary rod  30  is secured in place by bone screws  33 . Once secured in place, the intramedullary rod  30  helps to align and stabilize the fracture  24 .  
         [0025]      FIG. 6  is a diagrammatic, fragmentary front view of several of the components of the arrangement  10  of  FIG. 1  in a partially assembled state. Referring to  FIG. 6 , the cable  43  is shown in the process of being inserted from a lateral approach to fibula  14 . The cable  43  passes through cannula  62  and is securely coupled to the mechanism  50  at one end. The end portion  60  is received within the cannula  62  to hold the section  52  in the installation position during insertion. The cannula  62  cooperates with the mechanism  50  such that as the cannula is advanced forward, the mechanism  50  and, therefore, the cable  43  are also advanced forward. The rounded tip  54  of the mechanism  50  serves to guide the cable  43  and cannula  62  through opening  34  of rod  30  and through portions of bones  12  and  14 . In the current embodiment, a drill is used to form a passage through bones  12  and  14  in alignment with opening  34  prior to insertion of the cannula  62 .  
         [0026]      FIG. 7  is a diagrammatic, fragmentary front view of the arrangement  10  of  FIG. 1  in a partially assembled state. Once the mechanism  50  has passed all the way through bone  14 , across the gap between the bone  12  and bone  14 , and all the way through bone  12 , the section  52  is moved from the insertion position—in substantial alignment with the longitudinal axis  66  of the cable  43 , as shown in  FIG. 6 —into the bone-engaging position—at an angle with respect to the longitudinal axis  66  of the cable, as shown in  FIG. 7 . As previously mentioned, the cable  43  is bent such that it resiliently biases the section  52  toward the bone-engaging position. Thus, moving the section  52  between the insertion position and the bone-engaging position is accomplished by either retracting the cannula  62  with respect to the cable  43  or extending the cable with respect to the cannula. The inclined surface  61  facilitates movement of the section  52  between the insertion position and the bone-engaging position by allowing the end portion  60  to be more easily removed from the cannula  62  and rotated into the bone-engaging position. The cannula  62  is removed once the section  52  is in the bone-engaging position.  
         [0027]     Referring to  FIG. 7 , once the section  52  is inserted and rotated into the bone-engaging position, the bone-engaging surface  53  abuts the exterior surface  20  of bone  12 . Engagement of the exterior surface  20  and the bone-engaging surface  53  prevents leftward lateral movement of the cable  43 , as viewed in  FIG. 7 . This also allows the cable  43  to be tensioned.  FIG. 7  shows the anchor  35  and the uncrimped ferrule  48  slidably supported on the cable  43 . The anchor  35  is moved rightwardly along the cable  43  until the projection  41  is positioned within at least a portion of the bone  14 . The bone-engaging surface  36  initially engages the exterior surface  23  of the bone  14  adjacent the bone fragments  26 - 28  ( FIG. 2 ). As the anchor  35  is moved into position, the bone-engaging surface  36  is urged against the bone fragments and helps to reduce the fracture  24 . Once in position, the bone-engaging surface  36  functions to properly align and hold the bone fragments in place. The ferrule  48  is then advanced rightwardly along the cable  43  to a position adjacent the anchor  35 . The left end of the cable  43  is pulled leftwardly in  FIG. 7  to tension the cable, and the ferrule  48  is pressed rightwardly and then crimped to the cable  43 . Once the ferrule  48  is crimped to the cable  43 , the end of portion  44  of the cable is cut so that it does not extend beyond the ferrule  48 , as shown in  FIGS. 1 and 2 . Since the cable  43  is tensioned before crimping the ferrule  48 , the anchor  35  will be held securely in place with respect to the exterior bone surface  23  and the bone fragments. Further, the tension along cable  43  also serves to limit or stabilize the motion between the bones  12  and  14 . The flexibility of the cable  43  allows some limited syndesmotic motion. Thus, the apparatus  16  is able to simultaneously reduce and fix the fracture  24  and limit syndesmotic motion between the bones  12  and  14 .  
         [0028]     The components of the apparatus  16 , including the intramedullary rod  30 , the bone screws  33 , the anchor  35 , the cable  43 , the ferrule  48 , and the coupling mechanism  50 , have been described as being made from certain specific surgical-grade materials including stainless steel and cobalt-chrome. However, these components can alternatively be made of other appropriate surgical-grade materials, including: metals, such as titanium and titanium alloys; polymers, such as polyetheretherketone (PEEK); or any other suitable materials. Further, the materials chosen may be based on a desired flexibility, or lack thereof, for the specific component. Further, the actual shapes, sizes, and material choices for the various components may be varied, and for example modified for the particular application or patient.  
         [0029]     For example,  FIG. 8  is a diagrammatic, fragmentary side view similar to  FIG. 3 , but showing an anchor  68  that is an alternative embodiment of the anchor  35  of  FIG. 3 . The anchor  68  is similar to the previously described anchor  35 , except that the anchor  68  has curved upper and lower edges, as shown.  FIG. 9  is a diagrammatic, fragmentary side view similar to  FIG. 3 , but showing an anchor  70  that is an alternative embodiment of the anchor  35  of  FIG. 3 . The anchor  70  is similar to anchor  35 , except that the anchor  70  has a curved, “hour-glass” shape with smooth contours, as shown.  
         [0030]      FIG. 10  is a diagrammatic, fragmentary front view similar to  FIG. 1 , but showing an apparatus  71  that is an alternative embodiment of the apparatus  16 .  FIG. 11  is a sectional view of the apparatus  71  of  FIG. 10  taken along section line  11 - 11 . The apparatus  71  shown in  FIGS. 10 and 11  is similar to the apparatus  16  described above, except for the differences noted below.  
         [0031]     As shown in  FIGS. 10 and 11 , the apparatus  71  includes an anchor  72 . The anchor  72  includes a curved portion with a bone-engaging surface  74 . As best shown in  FIG. 11 , the bone-engaging surface  74  is curved to approximately match the curvature of the exterior surface  23  of the bone  14 . Thus, the bone-engaging surface  74  has a concave surface that engages the bone  14 . In the illustrated embodiment, the concave surface is approximately cylindrical and oriented so that its axis extends parallel to the longitudinal axis of bone  14 . The bone engaging surface  74  of the anchor  72  engages the exterior surface  23  of the bone  14  adjacent the bone fragments  26 - 28 . The anchor  72  includes barbs  76  and  78  at each end. The barbs  76  and  78  extend from the bone engaging surface  74  at an acute angle generally toward the center of the anchor, as shown. Also, the barbs  76  and  78  are pointed to facilitate engagement with the bone  14 . The barbs  76  and  78  serve to secure the anchor  72  against the exterior surface  23  of the bone  14  and hold the bone fragments  26 - 28  in place for proper reduction of the fracture  24 . The angle of the barbs  76  and  78 , however, allows the anchor  72  to be urged into position around the bone  14  without interference from the barbs. Once in position the barbs  76  and  78  engage the bone  14  to hold the anchor in place and prevent the anchor  72  from migrating out of position away from the bone fragments  26 - 28  or the bone  14 .  
         [0032]     As shown best in  FIG. 11 , the anchor  72  also includes a projection  80  that projects outwardly from a location eccentric to the center of the surface  74 . The projection  80  is approximately cylindrical and extends into the bone  14 . The off-center projection  80  is adapted to engage the opening  34  of the intramedullary rod  30 . The off-center projection  80  is utilized where the intramedullary rod has been inserted in the intramedullary canal  22  of the bone  14  in an off-center position.  FIG. 11  shows the projection  80  engaging the opening  34  where the intramedullary rod  30  has been inserted in a position posterior to a central position. A central longitudinal opening  82  in the projection  80  extends completely through the anchor  72 .  
         [0033]     Referring again to  FIGS. 10 and 11 , the apparatus  71  also includes a flexible elongate element or cable  43 . In the current embodiment, the portions  44 - 46  of the cable  43  are of a substantially uniform diameter. The cable  43  is inserted using a needle  83  having a diameter substantially similar to the diameter of the cable portions  44 - 46 . The cable  43  extends through the opening  82  in the anchor  72 , the opening  34  in the intramedullary rod  30 , portions of both of the bones  12 ,  14 , and the gap between the bones. Adjacent the anchor  72 , a ferrule  48  is fixedly secured to the portion  44  by crimping the ferrule to the cable  43 . The ferrule  48  is formed from a deformable surgical-grade material, and in particular is made of cobalt-chrome. At the other end of the cable, a ferrule  84 , similar to ferrule  48 , is fixedly secured to the portion  45  by crimping the ferrule  84  to the cable. A washer  86  is positioned around the cable between the ferrule  84  and the bone  12  to prevent the ferrule and portion  45  of the cable  43  from moving medially beyond the exterior surface  20  of the bone  12 . To that end, the washer  86  includes a flat bone-engaging surface  88 . The washer  86  is formed from cobalt chrome, such that it is slightly deformable to adapt to the contour of the exterior surface  20  of the bone  12 .  
         [0034]      FIG. 12  is a diagrammatic, fragmentary side view of the apparatus  71  of  FIG. 10 . As shown, the anchor  71  is elongate and has tapered ends. The central longitudinal opening  82  has a diameter slightly larger than the diameter of the cable  43  to allow the cable to pass through it.  
         [0035]     In some embodiments the anchor  35  is slightly flexible or deformable. In that respect, in some embodiments the anchor  35  is flexible near each end and rigid, or less flexible, near its middle. In a further embodiment, the bone engagement surface  36  of the anchor  35  is substantially circular. Further, in other embodiments the bone-engaging surface  36  may have a variable radius of curvature. Also, in other embodiments the anchor  35  may not include a barrel portion or projection  41 . Further, in other embodiments the number of bone screws may be increased or decreased, the orientation of the bone screws may be altered, and the position of the bone screws may be changed. The tension and flexibility of the cable  43  may be adjusted for the particular application or patient, as well. Also, the section  52  may be moved into the bone-engaging position while located in the intramedullary canal  18  of the bone  12 . Using such an approach, the bone-engaging surface  53  engages a surface on the cortical bone material surrounding the intramedullary canal  18 .  
         [0036]     Accordingly, all such modifications and alternatives are intended to be included within the scope of the invention as defined in the following claims. Those skilled in the art should also realize that such modifications and equivalent constructions or methods do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. It is understood that all spatial references, such as “horizontal,” “vertical,” “top,” “upper,” “lower,” “bottom,” “left,” and “right,” are for illustrative purposes only and can be varied within the scope of the disclosure. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.