Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/573,310 filed Oct. 5, 2009 disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     During reconstruction of a fractured or broken bone it is necessary to keep the repaired bone in an immobilized and stable state during the healing process. Further, the pieces of broken bones need to be encouraged to grow together. That is, the bone may be broken into multiple pieces and those pieces need to be moved together to promote proper healing. Presently, this is accomplished using a rigid body such as an external fixation ring or frame and various fixation components (e.g., wires, pins, etc.). These fixation components extend from the ring and immobilize the bone and move the bone into proper realignment. 
     More specifically, the rigid body used in foot and/or ankle reconstruction is a foot frame. Typically, foot frames have an open ring member. This open ring member typically is a single U-shaped frame designed to connect with half pins or wires (e.g., Kirschner or k-wires) passed through the broken or fractured bones. To encourage the bones together, these wires are implanted through particular pieces of the bone (e.g., the foot and/or ankle) and are attached at their ends to the open ring member. These wires are, typically, attached to the open ring member by wire/rod nuts. Further, these wires immobilize and/or apply force to the particular bones in order to move the bones together into proper alignment. 
     Presently, in order to provide a force to move the bones these wires are bent prior to being attached to the open ring member. Thus, by applying tension to the wire, the wire straightens creating a force on the bone and encouraging the bones together. However, this technique provides little control over the movement of the wire and amount of force on the bone. 
     Accordingly, a need exists to develop a device and method for accurately moving the wires so as to move the bones together in a controlled manner. 
     BRIEF SUMMARY OF THE INVENTION 
     Disclosed herein is an external fixation system. The external fixation system includes a ring element having a planar portion and an adjustable device having a body releasably mounted on the planar portion of the ring element. The adjustable device further includes a first member mounted on the body for movement in a direction generally perpendicular to the planar ring portion; a second member pivotally mounts on the first member for angular movement with respect to the body; a third member mounts on the second member for movement with respect to a circumference of the ring element; and a bone engaging element mounts on the third member. 
     Further, disclosed herein is an external fixation system including a ring element having a planar portion; and an adjustable device including a body, a first member and a second member. The body being releasably mounted on the ring element. Further, the first member is capable of moving in a direction perpendicular to a planar surface on the ring element and the second member is capable of linear motion about the circumference of the ring element. The body, first member, and second member each include a planar surface; and the planar surface of the body contacts a first planar surface of the first member and second planar surface on the first member is in contact with a first planar surface of the second member. 
     Also disclosed herein is a method for realigning a broken bone. The method includes providing an external fixation device having a ring member, a first adjustable device, and a second adjustable device. The first adjustable device having a body attached to the ring member, a first member mounted on the body, a second member mounted on the first member, and a third member mounted on the second member. The second adjustable device having a body attached to the ring member, a first member mounted on the body, a second member mounted on the first member, and a third member attached to the second member. Further, a first k-wire or half pin is inserted through a first piece of a broken bone and the first k-wire or half pin is affixed to the ring member. A second k-wire or half pin is inserting through a second piece of (broken) bone and the second k-wire is affixed to the first and second adjustable devices. Adjusting at least one of the first and second adjustable devices realigns the broken bone. 
     The dynamic fixator described herein can be used to gradually correct a traumatized bone (i.e., a bone that is broken or fractured). The fixator provides accurate multi axis movement (i.e., movement in two to three different axes-linear, vertical, and angular). This multi axis movement is used in repairing traumatized bone by, for example, realigning two pieces of a traumatized bone. Note: sometimes the wires are not in the broken bones. They may be in healthy bones on either sides of the fractured bones 
     For example, two pieces of a (traumatized) bone can be realigned by bringing the pieces of bone together. The bones are brought together by having a first and second k-wire pass through a first and second piece of the (traumatized) bone and having the first and second k-wires attached to one of a rigid body (e.g., ring element) or an adjustable device wherein the traumatized bone is realigned by moving the adjustable device in at least one axis. More specifically, after passing the first k-wire through the traumatized bone, both the first and second ends of the first k-wire are attached to a ring element. With the first piece of traumatized bone secured, a second k-wire is passed through a second piece of traumatized bone. After passing the second k-wire through the second piece of traumatized bone, the first end of the second k-wire is attached to a first adjustable device and the second end of the second k-wire is attached to a second adjustable device. Keeping the first k-wire attached to the rigid body the second k-wire can be moved in accurate multi axis movement by adjusting the first and second adjustable devices. Moving at least one of the first and second adjustable devices causes the second k-wire to move thereby moving the traumatized bone into a desired position (e.g., proper alignment). 
     In some embodiments, the adjustable device is capable of motion in three different directions. For example, the adjustable device is capable of linear, vertical, and angular motion. In other embodiments, the adjustable device is capable of motion in two different directions. For example, the adjustable device is capable of linear and vertical motion, however, it can not move angularly. It will be apparent that the adjustable device can produce any combination of linear, vertical, and angular motion. Further, although described as having the second k-wire attached to a first and second adjustable device the first end or second end of the second k-wire can be attached to the rigid body. Further still, as an alternative, both the first and the second k-wires can be attached to adjustable devices, the rigid body, or a combination of an adjustable device and the rigid body. Lastly, although depicted as only one or two adjustable devices, any number of adjustable devices can be attached to the rigid body. 
     As used herein when referring to bones or other parts of the body, the term “proximal” means close to the heart and the term “distal” means more distant from the heart. The term “inferior” means toward the feet and the term “superior” means toward the head. The term “anterior” means toward the front part or the face and the term “posterior” means toward the back of the body. The term “medial” means toward the midline of the body and the term “lateral” means away from the midline of the body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects of this invention are explained and elaborated through reference to the embodiments described as examples below. Examples of embodiments are described in the following with reference to the following drawings. 
         FIGS. 1A-1B  show an isometric view of an external fixation device having a ring element and two adjustable devices having k-wires mounted thereon attached to the parts according to the present invention; 
         FIG. 2A  shows an enlarged isometric view of the adjustable device shown in  FIG. 1 ; 
         FIG. 2B  shows an enlarged view of area A of  FIG. 2A  showing a ring coupling element; 
         FIG. 2C  is an enlarged view of an alternate ring coupling element of the present invention used in  FIG. 3A ; 
         FIG. 3A  is an isometric view of an adjustable device showing the interaction between a first member and a body that enables the first member to move up and down (i.e., perpendicular to a planar surface on the ring element); 
         FIG. 3B  is an isometric view from lines  3 - 3  of  FIG. 2A  and shows the internal gearing that enables a second member to pivot with respect to the ring element; 
         FIG. 3C  is an exploded view of the moveable third member and second member shown in  FIG. 2A  as well as a threaded rod that enables the third member to move linearly with respect to the circumference of the ring element; 
         FIG. 3D  is a cross-sectional view showing the member of  FIG. 3C  assembled; 
         FIG. 4  is a rear view of the adjustable device of  FIG. 4  in a first position; 
         FIG. 5  is an isometric end view of the adjustable device of  FIG. 4  in a second position; 
         FIGS. 6A and 6B  are exploded views of an adjustable device of  FIG. 2A  showing the body, the first member, the second member, and the third member; 
         FIGS. 7A-7B  are isometric views similar to  FIGS. 1A and 1B  showing the adjustable device from two different positions; 
         FIG. 8A  is an isometric view of an alternate adjustable device allowing two degrees of movement; 
         FIG. 8B  is a side isometric view of the alternate adjustable device of  FIG. 8A ; 
         FIG. 9  is an exploded view of the alternate adjustable devices of  8 A and  8 B; 
         FIG. 10  is a top view of an alternate dynamic external fixator with adjustable members mounted on the inside of the rings; 
         FIG. 11  is an enlarged isometric view of the ring and adjustable members of  FIG. 10 ; 
         FIG. 12  is a top isometric view of an alternate adjustable device exhibiting two degrees of freedom; and 
         FIG. 13  is a bottom isometric view of the adjustable member of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1A-1B , in accordance with a preferred embodiment of the present invention, an isometric view of a dynamic external fixator generally denoted as  100  is shown mounted on a foot  101  by pins. Dynamic external fixator  100  includes a U-shaped ring element  102  having a plurality of mounting holes  103  with at least one adjustable device  104 , and preferably two, releasably attached to a pair of mounting holes  103 . Adjustable device  104  includes a body  106  releasably attached to arms  108 ,  108 ′ of ring element  102 . The adjustable device further includes a first member  110  slidably mounted on body  106  capable of providing movement in a direction perpendicular to a proximal surface  109  of arm  108 ,  108 ′ of ring element  102 . Further, a second member  112  pivotally mounts on first member  110  for providing angular movement (i.e., rotation) with respect to first member  110 . Further still, a third member  114  mounts on second member  112  providing linear movement along arms  108 ,  108 ′. Preferably one or more wire engagement elements  116  attach first or second k-wires  118  that pass through a fractured bone respectively. The wire engagement elements are mounted to third member  114  and/or to ring  102  directly. For example, as shown, first k-wire  118  attaches to a standard bone engagement element  116 . Further, a second k-wire  120  can attach directly to ring element  102 . For example, as shown, second k-wire  120  attaches to ring element  102  by being clamped in a standard ring engagement element  122  mounted in a hole  103 . 
     Preferably first and second k-wires  118 , 120  are substantially smooth pins with a drill tip. In some instances, however, first and second k-wires  118 , 120  may not include a drill tip. Further, first and second k-wires  118 , 120  can be made of any suitable material, such as, but not limited to, stainless steel, titanium, and titanium alloy. Further, first and second k-wires  118 ,  120  can connect to bone engagement element  116  and ring engagement element  122  by being inserted through a hole (not shown) in bone engagement element  116  or ring engagement element  122  and applying a force on first or second k-wires  118 ,  120  by, for example, a set screw (not shown). Alternatively, bone engagement element  116  or ring engagement element  122  can be a wire/rod nut. Any reasonable method for attaching first and second k-wires  118 ,  120  to bone engagement element  116  or ring engagement element  122  can be used. 
     Ring element  102  can be a substantially monolithic material designed to releasably attach to at least one adjustable device  104 . Ring element  102  can be made of metal (e.g., stainless steel, titanium, etc.), composites (e.g., Carbon PEEK, etc.), or any other material deemed suitable. Further, although described as a u-shaped ring, ring element  102  can include any shape that allows at least one adjustable device to be releasably connected to it. For example, ring element  102  can be a circle shape, horseshoe shape, square shape, rectangle shape, or any other shape deemed suitable. Ring element  102  preferably is planer creating a relatively flat surface on ring element  102 . This flat surface is used to provide a flat surface to releasably attach ring element  102  with adjustable device  104 . Such a ring can have four levels as shown in U.S. patent application Ser. No. 12/157,612 filed Jun. 11, 2008, the disclosure of which is incorporated herein by reference. 
     Referring to  FIG. 2A , adjustable device  104  is shown in greater detail. Adjustable device  104  has a body  106  with a pair of expandable connectors  202 A that releasably connect adjustable device  104  to holes  103  of ring element  102 . Attached to body  106  is first member  110  which slidably mounts on body  106 . While mounted on body  106 , when fixed on ring  102 , first member  110  can move up and down with respect to top planar surface  206  of body  106 . That is, first member  110  can move in a direction perpendicular to upper surface  206  of body  106  and the plane of the ring  102 . This is accomplished by the rotating threaded pin  308  as will be described below. Further, because, in the preferred embodiment, surface  206  of body  106  is parallel to the plane of ring element  102  (see,  FIGS. 1A-1B ) first member  110  moves in a direction perpendicular to the plane of ring element  102 . 
     Referring to  FIG. 2B  an exemplary ring element connector is displayed. As shown, preferred connector  202 A includes a lower outer portion  215  located under body  106  split into two sections  214 ,  216  and an inner portion  217  with a pair of drive heads  208 ,  209  located above body  106  for engaging a drive tool. Further, inner portion  217  has a threaded shaft  212  coupled to drive heads  208 ,  209  and extends between the two halves  214 ,  216 . Threaded shaft  212  includes tapered nut  218  which when moved toward body  106  caused sections  214  and  216  to expand. After connector  202 A is placed through body  106  and into hole  103  in the ring element  102 , nut  218  is threaded on the bottom of threaded shaft  212 . As drives  208 ,  209  are rotated nut  218  causes the two halves  214 , 216  to expand thereby securing the adjustable device to the ring element. Although described as two halves the split portion can include any number of sections (e.g., three or four sections). 
     Referring to  FIG. 2C  there is shown an alternative ring element connector  202 B. As shown, ring connector  202 B can include a shaft  219  with a screw thread portion  222  and a drive head  221 . The threaded shaft portion  222  is inserted through the bore in body  106  until drive head  221  comes into contact with upper surface body  106 . Threaded shaft portion  222  is further inserted through an opening  103  in ring element  102  and threaded into a nut  224 . As threaded shaft portion  222  is threaded into nut  224  adjustable device  104  is secured onto ring element  102 . Further, any method of releasably securing adjustable device  104  to the ring element can be used. For example, the adjustable device can be releasably attached to the ring element by a screw and nut, a bolt assembly, or any other securing method deemed suitable. 
     Referring to  FIG. 3A , a rear view of two parts of the preferred adjusting device  104  is shown. The two parts are members  110  and  106 . First member  110  has a first portion  113  and a central portion  306  which can move in a direction perpendicular to the plane of ring element  102  by rotating a screw shaft  302  via drive head  308 . Screw shaft  302  is placed through a hole  115  in body  106  and is threaded into a second threaded hole  117  located in central flange  306  extending rearwardly from first portion  113  of first member  110 . Shaft  302  has an end  338  with a pin  340  to ensure the assembly does not come apart during use. In use, a user rotates a drive head  308  causing screw  302  to thread into the second hole thereby moving first member  110  up and down with respect to body  106  (i.e., perpendicular to planar surface  206  of body  106  and perpendicular to the plane of ring element  102 ). Alternatively, although screw shaft  302  is described as threaded into a second hole in member  110 , screw  302  may thread into a threaded hole in body  106  and fixed in part  306 . It will be understood that any method of making first member  110  move up and down with respect to body  106  can be used. Further, increasing the number of threads on screw shaft  302  increases the number of rotations needed to move first member  110  up and down. Thus, increasing the number of threads increases the precision of up and down movement. 
     In some embodiments, flange  306  extending from first member  110  is designed to ride along a protruding track  310  extending from body  106 . Riding on track  310  reduces the amount of movement in an undesired direction. Further, any method of mating first member  110  with body  106  designed to decrease movement in an undesired direction can be used. For example, first member  110  and body  106  can include any male-female mating features (e.g., tongue and groove or dovetail) for providing guided movement up and down. 
     Referring to  FIGS. 2A, 4 and 6A , second member  112  is rotably mounted on first member  110 . While mounted on first member  110 , second member  112  can rotate through a range of angles with respect to first member  110 . That is, second member  112  is pivotally mounted by guide tracks  612  on first member  110  and can rotate with respect to first member  110 . For example, in the preferred embodiment, second member  112  can pivot up to  120  degrees around its center on guide  614  mounted on first member  110  as shown in  FIG. 6A . That is, second member  112  can, for example, rotate 60 degrees from parallel in an upward direction and 60 degrees in a downward direction with respect to surface  306 . 
     Referring to  FIG. 3B  in the preferred embodiment, second member  112  rotates through a range of angles by the interaction of a worm  312  (i.e., a gear in the form of a screw) with an arcuate worm gear  314  mounted on second member  112  on the outer surface of the portion thereof forming track  612  (i.e., a worm wheel). For example, worm  312  can thread into worm gear  314  causing second member  112  to rotate relative to first member  110 . In use, a user rotates drive head  316  of worm  312  causing worm  312  to rotate while engaged with worm gear  314 . Because first member  110  is attached to body  106  that is fixed to ring element  102 , rotating worm  312  while engaged with worm gear  314  causes second member  112  to rotate upwardly or downwardly with respect to the plane of ring  102 . Although described as a worm gear and worm any reasonable method can be used to change the angle of second member  112  with respect to first member  110 . For example, the angle can be changed by spur gears, helical gears, double helical gears, bevel gears, crown gears, or any other gearing deemed suitable. Further increasing the number of threads (i.e., increasing the number of threads on the worm gear and worm) increases the number of rotations of user interface  316  required to move through a given angle. Thus, increasing the number of threads provides a greater level of precision during rotation. 
     Referring to  FIGS. 2A and 6A , as shown, third member  114  is mounted on second member  112 . While mounted on second member  112 , third member  114  can move linearly with respect to second member  112 . That is, third member  114  can linearly move along arms  108 ,  108 ′ of the ring element in a direction parallel to the plane of ring  102  in an anterior-posterior direction. 
     Referring to  FIG. 3C  in the preferred embodiments, third member  114  includes a dovetail protrusion  322  (i.e., guide element) that mates with a groove  324  extending along second member  112 . Protrusions  322  mates with groove  322  thereby providing a guide for the linear motion. For example, in the preferred embodiment, a male dovetail protrusion  322  extending from third member  114  can mate with a female dovetail  324  located on second member  112  thereby providing a linear guide between second member  112  and third member  114 . Any form of male and female guide elements can be used to provide a linear guide between third member  114  and second member  112 . 
     Referring to  FIGS. 3C and 3D , in the preferred embodiment, second member  112  includes a bore  326  for receiving an end  327  of a threaded rod  328 . Further, third member  114  can translate on threaded rod  328  as it is rotated via drive head  331  or  332 . Translation is possible because third member  114  includes a threaded bore  330  for receiving threaded rod  328 . Thus, rotating threaded rod  328  translates third member  114  along the axis of threaded rod  328 . In use, a user rotates drive head  331  or  332  causing threaded rod  328  to rotate in bore  330  of third member  114  thereby causing third member  114  to move linearly along arm  108 ,  108 ′ of ring element  102 . Alternately, any reasonable method for moving third member  114  linearly can be used. Further, increasing the number of threads/grooves on third member  114  and the number of threads/grooves on rod  328  increases the amount of precision in linearly moving third member  114 . In the preferred embodiment, one rotation moves member  114  about one millimeter. 
     Referring to  FIG. 4 , the adjustable device having the first, second, and third member in a first position is illustratively depicted. As shown, first member  110  has not moved perpendicular to planar surface  206  of body  106 . Further, second member  112  has not been rotated with respect to first member  110 . Lastly, third member  114  is depicted in a first position. 
     Referring to  FIG. 5 , the relative displacement of each of the first, second, and third members is illustratively depicted as compared to  FIG. 4 . As shown, first member  110  has been displaced perpendicularly to planar surface  206  of body  106 . Further, second member  112 , has rotated with respect to first member  110 . Lastly, third member  114  is depicted in a second position where it has moved linearly with respect to second member  112 . 
     Referring to  FIGS. 6A and 6B , there is shown an exploded view of adjustable device  104  of the preferred embodiment illustratively depicts the internal contact surfaces for each of body  106 , first member  110 , and second member  112 . As shown, body  108  includes internal planar surface  602  which contacts internal planar surface  604  of first member  110 . These planar surfaces provide a guide surface as first member  110  is displaced in a direction perpendicular to the plane of ring  102 . Preferably, internal planar surfaces  602 ,  604  are substantially smooth surfaces permitting low friction sliding movement. Alternatively, in other instances, internal planar surfaces  602 ,  604  can include male and female protrusions (not shown) for allowing movement only perpendicular to planar surface  206  of body  106 . 
     Further, as shown, internal planar surface  606  of first member  110  contacts an internal planar surface  608  of second member  112 . Thus, during rotation these guide surfaces minimize motion in an undesired direction. Further, the angular motion of second member  112  is guided by track  612  which is in the form of an arcuate guide surface that rides on an arcuate guide element  614  which is attached to a planar surface  616  located on first member  110 . Further, track  612  provides a center of rotation centrally located on first member  110 . Disc  614  attaches to planar surface  616  by, for example, screws  618  threaded into holes  620  located in first member  110 . Because track  612  rides on disc  614  motion in any direction other than the desired angular rotation direction is minimized. Gear teeth  315  are provided on the outer surfaces of track  612  which are driven by worm  312 . A lock element  350  may be provided to lock second member  112  in the desired angular position. 
     Further, third member  114  includes a male dovetail protrusion  610  that mates with a female guide surface  609  acting as a guiding surface when third member  114  moves linearly. Each of the above described surfaces increase the control of the adjustable device by minimizing motion other than in the desired directions. 
     Referring to  FIGS. 7A-7B , in some embodiments, adjustable device  104  can move only in the anterior-posterior and inferior-posterior directions. As shown, an alternate adjustable device  700  can include a body  702  attached to a ring element  704 . Further mounted on body  702  is a first member  706  providing movement perpendicular to body  702  by rotation of screw  714  and a second member  708  mounted on first member  706  providing linear movement along arms  710  of ring element  704  by rotation of screw  712 . In this embodiment there is no rotational movement between member  706  and  702 . 
     As shown, unlike the preferred adjustable device capable of motion in three directions, the adjustable device of  FIGS. 7A and 7B  is only capable of movement in two directions. As depicted, first member  706  mounted on body  702  provides movement perpendicular to body  702 . Further, second member  708  mounted on first member  706  provides motion parallel to the plane of the ring. 
     Further, in some embodiments, a scale can be located on at least one of first member  110  and second member  112 . This scale can be used to determine the length of angular or linear displacement by the member. Further, a scale can be located on any of the body, first member, second member, or third member for respectively determining the amount of linear, angular, or circumferential movement of each of the members. 
     Referring to  FIGS. 8A-9 , there is shown an alternate adjustable device as shown in  FIGS. 8A and 8B . The device generally denoted as  700  includes a body  702 , first member  706  and second member  708  but does not provide rotational movement between member  706  and  702  as in adjustable device  104  ( FIG. 5 ). Movement parallel to the ring is accomplished by turning screw shaft  712  to move element  708  and movement perpendicular to the ring is accomplished by turning screw shaft  714  and moving element  706  in relation to body  702 . Pin holder can be located in one or both of holes  718 . 
       FIG. 9  shows an exploded view of the alternate adjustable device  700  including body  702  and element  708  slidably mounted in a groove  716  in member  706  via a dovetail extension  728  and sliding element  708 . Again, screw  712  is rotated in a threaded bore  720  of element  708  to cause the movement of element  708  parallel to the ring arm  710 . Element  706  and body  702  includes contacting surfaces  722  and  724  respectively. These surfaces contact when the element  706  is moved in a direction perpendicular to the plane of the ring by turning screw  714  in threaded bore  725 . This movement may be guide by tongue and groove interconnection as in device  104 . 
     Referring to  FIGS. 10 and 11 , there is shown a top view of an alternate system in which the adjustable device  700  is mounted on the inner surface  730  of ring  704 . Again, Kirschner wires  118  and  120  may be engaged with a foot  101 . 
     Referring to  FIGS. 10  though  13 , there is shown as an alternate adjustable device  700 ′ which is similar to adjustable device  700  with the exception that a second pin holder  740  is attached to a block  742  which is slidably mounted within the groove  716  of element  706 . Block  742  has a threaded bore which is mounted on screw shaft  712  and is moveable with respect to element  706 . First block  708 A is also provided with a pin holder and is operated as block  708 . This allows the mounting of two Kirschner wires on element  706  with both Kirschner wires being adjustable along the length of the arm  710 . Again, screw shaft  714  allows the block  706  to move in the direction perpendicular to the plane of arm  710 . As shown in  FIG. 12 , indicators scales  746  and  748  may be provided to indicate the amount of movement of the Kirschner wires in millimeters. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

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