Abstract:
An outrigger for connecting to an external bone fixation clamp comprises an elongated member having a length, a proximal end and a distal end, the distal end having a threaded portion. The outrigger also comprises a connecting member operably associated with the elongated member, the connecting member having a tightening portion at a proximal end and a gripping portion at a distal end, the gripping portion having a greater diameter than the tightening portion. The outrigger also comprises a slide lock disposed about the threaded portion, the slide lock being longitudinally movable along the length of the threaded portion and having a non-smooth engagement surface configured to engage a non-smooth surface of the external bone fixation clamp in order to prevent rotation of the elongated member relative to the external bone fixation clamp.

Description:
PRIORITY CLAIM 
     The present application is a Continuation Application of U.S. patent application Ser. No. 11/114,554 filed on Apr. 25, 2005 entitled “Outrigger With Locking Mechanism.” The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an outrigger for use in an external fixation system and, in particular, a locking mechanism which prevents loosening of the outrigger after surgery. 
     BACKGROUND OF THE INVENTION 
     Outriggers typically form part of an external fixation system and are usually attached to a clamp which holds one or more wires, pins, screws, rods, bars and/or rings. Threads on one end of the outrigger have been used to attached the outrigger to a clamp. Such a construction, however, may allow the outrigger to loosen and/or separate from the clamp after a surgical procedure. Therefore, it is desirable to have an outrigger incorporating a locking mechanism which prevents the outrigger from loosening and/or separating from a clamp after surgery. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an outrigger which may include an elongated member having a distal end, a proximal end and a connecting portion proximate the distal end; a moveable member operably associated with the distal end; and a slide lock. In one embodiment, the connecting portion may be a threaded portion. 
     The threaded portion may have a keyed portion (e.g., at least one flat side) and may be screwed into a threaded opening in a clamp. The slide lock may have an opening therethrough which may be keyed or configured such that it can translate along the threaded portion but not rotate about the threaded portion. In one embodiment, the slide lock may have an opening therethrough with at least one flat portion which may cooperate with at least one flat side of the threaded portion. 
     The moveable member may be positioned proximal the slide lock such that the slide lock may be positioned between the moveable member and a clamp. The moveable member may engage the threaded portion of the elongated member such that the moveable member may move distally and proximally along the threaded portion. In one embodiment, the movement member may be a nut having an opening with internal threads, which may engage the threaded portion. Rotation of the nut may move the nut towards and/or away from the slide lock. Movement of the moveable portion towards the slide lock may push the slide lock distally such that the slide lock may translate along the threaded portion towards a clamp. 
     The slide lock may have an engagement portion such as, for example, a serrated, knurled or rough surface. As the moveable member moves the slide lock distally along the threaded portion, the engagement portion of the slide lock may engage a surface of a clamp, which may be a serrated, knurled or rough surface. Contact between the engagement portion of the slide lock and the surface of the clamp may prevent rotational movement of the slide lock relative to the clamp. Because of the configuration, such as, for example, the keyed configuration of the opening in the slide lock, rotational movement of the outrigger with respect to the slide lock and, consequently, the clamp may also be prevented. In one exemplary embodiment, at least one flat portion of the slide lock may engage the flat, unthreaded side of the threaded portion to prevent rotation of the outrigger with respect to the slide lock and, consequently, rotation of the outrigger with respect to the clamp. 
     In one embodiment, the threaded portion of the elongated member of the outrigger may have a groove for receiving a washer, which may limit the extent the threaded portion may be screwed into a clamp. The washer may also keep the moveable portion and slide lock from sliding off the elongated member so that the elongated member, moveable portion and slide lock may be attached to a clamp as an assembly that cannot be readily disassembled, or may only be disassembled by breaking one or more pieces of the assembly. 
     In use, the elongated member, moveable member and slide lock may be connected together. The moveable member may be positioned proximate the slide lock such that the slide lock may be located between the moveable member and a clamp. The threaded portion may be screwed into a threaded opening in a clamp. In an embodiment incorporating a washer around the threaded portion, the threaded portion may be screwed into the clamp until the washer contacts the clamp. Thereafter, the moveable member may be moved in a distal direction towards the slide lock and the clamp. The moveable member, in turn, may move the slide lock towards the clamp until the engagement portion of the slide lock engages a portion of the clamp. The moveable member may be tightened to fix the position of the slide lock and, consequently, the elongated member relative to the clamp. 
     In one embodiment, a method for inserting an outrigger to a clamp of an external fixation system may comprise providing an outrigger which may have an elongated member having a length, a distal end, a proximal end and a connecting portion on the distal end, wherein the connecting portion may have a keyed portion; a moveable member operably associated with the elongated member which may be moveable along the elongated member; and a slide lock which may be disposed about the elongated member, the slide lock may have a keyed portion and an engagement surface, wherein the keyed portion of the connecting portion and the keyed portion of the slide lock may be operably associated with each other to permit longitudinal movement of the slide lock along the length of the elongated member while preventing rotation, and wherein the engagement surface of the slide lock may be configured to engage a portion of a clamp. The method may further comprise providing a clamp which may have an opening and an engagement portion positioned proximate the opening, moving the connecting portion of the elongated member into the opening of the clamp, engaging the connecting portion to the clamp, moving the moveable member on the connecting portion to move the slide lock towards the clamp, and engaging the engagement surface of the slide lock with the engagement portion of the clamp. Moreover, in an embodiment where the connecting portion may further comprise a groove for receiving a washer, the method may also comprise moving the connecting portion into the opening until the washer contacts the engagement portion of the clamp. 
     In an embodiment where the connecting portion may be a threaded portion, the method may further comprise providing a clamp which may have a threaded opening and an engagement portion positioned proximate the opening, screwing the threaded portion of the elongated member into the threaded opening of the clamp, moving the moveable member on the threaded portion to move the slide lock towards the clamp, and engaging the engagement surface of the slide lock with the engagement portion of the clamp. Furthermore, in an embodiment where the threaded portion may further comprise a groove for receiving a washer, the method may also comprise screwing the threaded portion into the threaded opening until the washer contacts the engagement portion of the clamp. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be better understood by reference to the following drawings, wherein like references numerals represent like elements. The drawings are merely exemplary to illustrate certain features that may be used singularly or in combination with other features and the present invention should not be limited to the embodiments shown. 
         FIG. 1  is a side view of an exemplary embodiment of the outrigger of the present invention; 
         FIG. 2  is a side view of an alternative exemplary embodiment of the outrigger of  FIG. 1 ; 
         FIGS. 3A-C  are side views of an exemplary embodiments of a component of the present invention; 
         FIGS. 4A and 4B  are perspective views of an exemplary embodiment of additional components of the present invention; 
         FIG. 5  is a perspective, exploded view of an exemplary embodiment of a clamp used in an external fixation system; 
         FIG. 6  is a top view of the clamp of  FIG. 5 ; and 
         FIG. 7  is a perspective view of an exemplary embodiment of an external fixation system incorporating the devices of  FIGS. 1 ,  2  and  5 . 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIG. 1 , the outrigger  1  may include an elongated member  2  having a distal end  3 , a proximal end  4  and a connecting portion  6  proximate the distal end  3 ; a moveable member  8  operably associated with the distal end  3 ; and a slide lock  10 . It should, however, be understood that those of ordinary skill in the art will recognize many modifications and substitutions which may be made to various elements of the present invention. 
     The elongated member  2 , moveable member  8  and slide lock  10  may be made of any material, preferably, a biocompatible material such as, for example, metal (e.g., stainless steel, titanium, aluminum), plastic, rubber, ceramic, an alloy of two or more materials, or a composite material (i.e., made up of two or more materials). The elongated member  2 , moveable member  8  and slide lock  10  may be made of the same or different materials. 
     The elongated member  2  may be straight or bent at an angle. As illustrated in  FIGS. 1 and 2 , the elongated member  2  may be bent at an angle θ of, for example, between about 90 degrees and about 180 degrees, preferably, between about 115 degrees and about 170 degrees and, most preferably, between about 140 degrees and about 160 degrees. The elongated member  2  may be solid or hollow. 
     In one embodiment, the connecting portion  6  may be a threaded portion. The threaded portion  6  may have a keyed portion  12  or may otherwise have a non-circular cross-section for reasons that will be explained below. As shown in  FIGS. 1 and 3A , the keyed portion  12  of the threaded portion  6  of the elongated member  2  may take the form of at least one flat side  12 . In a preferred embodiment, the threaded portion  6  may have two diametrically opposed flat sides  12 . Moreover, the threaded portion  6  may also have a circumferential, unthreaded groove  14  for receiving a washer  16 . The washer  16  may limit the extent to which a surgeon may screw the outrigger  1  into a clamp (e.g., clamp  100  of  FIGS. 5 and 6 ). In addition, the washer  16  may keep the moveable member  8  and the slide lock  10  from sliding off the elongated member  2  so that the elongated member  2 , moveable member  8  and the slide lock  10  may be attached to a clamp as an assembled, single unit. The washer  16  may be made of any of metal (e.g., stainless steel, titanium, aluminum), plastic, rubber, ceramic, an alloy of two or more materials, or a composite material (i.e., made up of two or more materials). In a preferred embodiment, the washer  16  may be made of metal. 
     It will be appreciated by those skilled in the art that the connecting portion  6  may be configured in any manner so long as the connecting portion  6  may prevent the elongated member  2  from being removed from a clamp (e.g., clamp  100 ,  FIGS. 5 and 6 ) and may allow for attachment of the moveable member  8  to the elongated member  2 . In one embodiment, the lower portion  6   b  of the connecting portion  6  may be unthreaded and may have a portion (e.g., a flat surface, an indentation, an opening), which may be engaged by a set screw  19  ( FIG. 3B ) positioned through a clamp. The set screw  19  may hold the elongated member  2  to the clamp. In another embodiment, the connecting portion  6  may comprise a retractable member (e.g., ball detent)  21  ( FIG. 3C ) which may be in a retracted position as the connecting portion  6  is inserted into an opening of a clamp and which may expand to fix the elongated member  2  to the clamp once the connecting portion  6  has been inserted a distance into the opening of the clamp. 
     A moveable member  8  may be attached to the threaded portion  6 . As shown in  FIG. 4A  the moveable member  8  may have an opening  17  with internal threads  18 . The internal threads  18  may engage external threads  6   a  on the threaded portion  6  such that rotation of the moveable member  8  in a first direction may result in the moveable member  8  moving towards the distal end  3  and rotation of moveable member  8  in a second direction may result in the moveable member  8  moving towards the proximal end  4 . The moveable member  8  may also have a gripping portion  20  and a tightening portion  22 . The gripping portion  20  may be used by a surgeon to tighten the moveable member  8  to a clamp using the surgeon&#39;s fingers. The gripping portion  20  may have numerous grooves or other surface roughening or enhancements to improve a surgeon&#39;s grip on the moveable member  8 . To further tighten the moveable member  8  to a clamp, the surgeon may use a tool to engage tightening portion  22 . The tightening portion  22  may be any shape (e.g., square, hexagon, octagon). It will be appreciated by those skilled in the art that the moveable member  8  may be any component which may be moved up and down the threaded portion  6  and fixed in position on the threaded portion  6 , and may comprise a nut. 
     The slide lock  10  ( FIG. 4B ) may be positioned proximate the moveable member  8  and, in particular, may be positioned between the moveable member  8  and a clamp. The slide lock  10  may have an opening  24  which may receive the threaded portion  6 . The opening  24  may be keyed or otherwise configured to cooperate with the keyed portion of the threaded portion  6  so that the slide lock  10  may translate along the threaded portion  6 , but not rotate thereabout. In one embodiment, the opening  24  may have at least one flat portion  26  which may cooperate with the at least one flat side  12  of the threaded portion  6  such that the slide lock  10  may translate along the threaded portion  6 , but not rotate thereabout. In a preferred embodiment, the slide lock  10  may have two diametrically opposed flat portions  26  to engage two diametrically opposed flat sides  12  of the threaded portion  6 . It should be noted, however, that any configuration of the slide lock  10  and threaded portion  6  may be used so long as the slide lock  10  may be prevented from rotating with respect to the threaded portion  6 . 
     The slide lock  10  may have an engagement portion  28  such as, for example, a serrated, knurled or rough surface. The engagement portion  28  of the slide lock  10  may be integral with the slide lock  10  or may be a separate piece. The engagement portion  28  may contact a portion of a clamp. In one embodiment, the engagement portion  28  may be serrated and may engage the serrations  30  on either side of a clamp  100  ( FIGS. 5 and 6 ). It will be appreciated that the engagement portion  28  of the slide lock  10  may be configured to include a surface which may provide sufficient friction when engaged with a surface of a clamp so as to prevent the slide lock  10  from moving (e.g., rotating) with respect to the clamp. Although shown as a relatively flat disc, the slide lock  10  may take the form of other shapes. 
     In use, the elongated member  2 , moveable member  8  and slide lock  10  may be operably connected to each other. The threaded portion  6  of the elongated member  2  may be twisted or screwed into a threaded opening in a clamp. In an embodiment that includes the optional washer  16 , the elongated member  2  may be screwed into the clamp until the washer  16  engages the clamp. The moveable member  8  may be rotated such that the moveable member  8  moves towards the clamp and, thus, may move the slide lock  10  towards the clamp. The keyed configuration of the threaded portion  6  and the slide lock  10  may allow the slide lock  10  to translate without rotating. For example, the engagement of the at least one flat side  12  of the threaded portion  6  with the at least one flat portion  26  of the slide lock  10  may result in the slide lock  10  translating along the threaded portion  6 , while preventing the slide lock  10  from rotating about the threaded portion  6 . As the slide lock  10  moves closer to the clamp, the engagement portion  28  of the slide lock  10  may engage a surface of the clamp. In an embodiment where the engagement portion  28  may be serrated, these serrations may engage corresponding serrations on the clamp. When the slide lock  10  engages the clamp, the slide lock  10  may be fixed or locked relative to the clamp and rotation between the slide lock  10  and the clamp may be prevented. Moreover, the engagement between the at least one flat side  12  and the at least one flat portion  26  may prevent the elongated member  2  from rotating with respect to slide lock  10  and, consequently, also with respect to the clamp. Such a construction may help prevent the outrigger  1  from loosening or separating from a clamp after surgery. 
     As shown in  FIG. 7 , the outrigger  1  may be used to connect various components including, for example, a clamp  200  and rod  300 , to a pin clamp  100 , which may engage pins or wires  400  inserted in a bone  500 . The outrigger  1  may be used as a component of an external fixation device. 
     While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope of the present invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other specific forms, structures, arrangements, proportions, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and not limited to the foregoing description.