Abstract:
Disclosed herein are systems and methods for manipulating the orientation of a plurality of bone fragments with respect to one another. A bone transport frame including first and second rings, a plurality of elongate struts, and a plurality of ring transport assemblies for orienting a first bone segment with respect to a second bone segment is disclosed. A third ring may be included in the bone transport frame for orienting a third bone segment with respect to the first and second bone segments. Manipulation of an adjustable member of the bone transport frame can transport a ring in either a proximal or distal direction with respect to other rings of the frame. Manipulation of another adjustable member of the bone transport frame can translate a central axis of one of the rings either toward or away from the central axes of the plurality of elongate struts.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to systems and methods for manipulating the orientation of a plurality of bone fragments with respect to one another, and in particular it relates to external fixation devices in which rings thereof may be manipulated with respect to one another via bone transport assemblies. 
       BACKGROUND OF THE INVENTION 
       [0002]    External fixation frames may be used to correct skeletal deformities using the distraction osteogenesis process. The Ilizarov external fixation devices, for example, are widely used for this purpose. The Ilizarov-type devices may be used to translate bone segments by manipulating rings connected to each bone segment. 
         [0003]    External fixation devices generally utilize a plurality of threaded rods fixated to through-holes in the rings to build the frame. In order to build a desired frame, these rods generally have to have different lengths. A problem that may arise out of this is that such external fixation frames generally do not allow significant manipulation of what may be referred to as a transport ring without disassembling and then reassembling the frame or adding new devices. These systems generally require removal of the entire frame in order to perform reconstruction. 
         [0004]    Once the frame is installed, the patient or surgeon generally moves the rings or percutaneous fixation components manually or mechanically by adjusting a series of adjustment mechanism, such as nuts, for example. A traditional method of adjusting the frame height generally requires the surgeon to loosen an individual nut gradually while tightening another other nut in order to secure the frame. These position adjustments must be done where the nuts are secured, making it very difficult for the patient to make the required daily adjustments with consideration of stable fixation in mind. Other devices use different techniques to adjust the effective length of the rods, but all must be adjusted somewhere between the ends, offering limited access for the patient. 
         [0005]    As adjustments made to external fixation devices are often a daily task for the patient, easy access to frame adjustment mechanisms would be beneficial for the patient. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    A first aspect of the present invention is a bone transport frame including first and second rings, a plurality of elongate struts, and a plurality of ring transport assemblies. The first and second rings each have upper and lower ring surfaces and a central axis that is perpendicular to the upper and lower ring surfaces. The plurality of elongate struts each having a central axis and are coupled to the first and second rings, the plurality of elongate struts each include a first adjustable member. The plurality of ring transport assemblies are adapted to rotatably couple the second ring to the plurality of elongate struts, the plurality of ring transport assemblies each include a second adjustable member. Preferably, rotation of the first adjustable member transports the second ring in either a proximal or distal direction with respect to the first ring, and rotation of the second adjustable member translates the central axis of the second ring either toward or away from each central axis of the plurality of elongate struts. 
         [0007]    In accordance with one embodiment of this first aspect of the present invention, the bone transport frame includes a third ring having upper and lower ring surfaces and having a central axis that is perpendicular to the upper and lower ring surfaces. The third ring is also coupled to the plurality of elongate struts and is located distally to the second ring, the second ring being located distally to the first ring. 
         [0008]    In accordance with another embodiment of this first aspect, the first, second and third rings each include a plurality of through-holes that extend through the upper and lower ring surfaces. 
         [0009]    In accordance with yet another embodiment of this first aspect, the bone transport frame further includes a plurality of pin retention members and bone pins adapted to couple the first, second, and third rings to a first, second and third bone fragments, respectively. The plurality of pin retention members are operatively coupled to the plurality of through-holes of the first, second and third rings. 
         [0010]    In accordance with still yet another embodiment of this first aspect, the bone transport frame further includes a plurality of wire retention members and bone wires adapted to couple the first, second and third rings to the first, second and third bone fragments, respectively. The plurality of wire retention members are operatively coupled to the plurality of through-holes of the first, second, and third rings. 
         [0011]    In accordance with still yet another embodiment of this first aspect, the bone transport frame further includes a plurality of flange extension members adapted to couple the first ring to the plurality of elongate struts, wherein each of the plurality of flange extension members include a first through-hole adapted to receive a first coupling member for coupling a first end of the plurality of flange extension members to the first ring and a second through hole adapted to receive a proximal end portion of the plurality of elongate struts. Each of the plurality of flange extension members further comprises a third through-hole adapted to receive a second coupling member for rigidly coupling the first end of the plurality of flange extension members to the first ring. 
         [0012]    In accordance with still yet another embodiment of this first aspect, the first adjustable member of each of the plurality of elongate struts is located at the proximal end portion of the plurality of elongate struts. The first adjustable member of each of the plurality of elongate struts is adapted to make incremental adjustments, each incremental adjustment corresponding to a clinically optimal adjustment length. The first adjustable member of each of the plurality of elongate struts is adapted to record each incremental adjustment. 
         [0013]    In accordance with still yet another embodiment of this first aspect, the plurality of elongate struts further includes a threaded shaft and a position adjustment member coupled to each of the plurality of ring transport assemblies, each position adjustment member adapted to transport along a length of the threaded shaft in the proximal and distal directions. Each position adjustment member has a semi-locked position such that the location of each position adjustment member on the threaded shaft is constant when the threaded shaft is not being rotated in either clockwise or counterclockwise directions about the central axis of the plurality of elongate struts and has an unlocked position such that the location of each position adjustment member can transport in either the proximal or distal directions without the threaded shaft being rotated in either the clockwise or counterclockwise directions about the central axis of the plurality of elongate struts. 
         [0014]    In accordance with still yet another embodiment of this first aspect, each of the plurality of ring transport assemblies further comprises a third adjustment member and wherein releasing the third adjustment member allows the second ring to move such that the central axis of the second ring is oblique to the central axis of each of the plurality of elongate struts. 
         [0015]    In accordance with still yet another embodiment of this first aspect, the second adjustment member is coupled to the third adjustment member, the second adjustment member being adapted to incrementally translate the central axis of the second ring either toward or away from each central axis of the plurality of elongate struts. 
         [0016]    A second aspect of the present invention is a method for transporting a second bone segment with respect to a first bone segment utilizing a bone transport frame including a first ring, a second ring, a plurality of ring transport assemblies, a plurality of first and second adjustment mechanisms, and a plurality of elongate struts. The method includes coupling the first bone segment to the first ring; coupling the second bone segment to the second ring; actuating the first adjustment mechanism to transport the second ring in either a proximal or distal direction along a central axis of at least one of the plurality of elongate struts; and actuating the second adjustable member to translate the second ring either toward or away from each of the plurality of elongate struts. 
         [0017]    In accordance with one embodiment of this second aspect, the step of actuating the first adjustment mechanism comprises incrementally rotating the first adjustment mechanism such that the second ring transports a fixed length along the central axis of at least one of the plurality of elongate struts, each incremental rotation of the first adjustment mechanism corresponding to a first fixed length. The step of actuating the second adjustable member comprises incrementally rotating the second adjustment mechanism such that the second ring translates either toward or away from each of the plurality of elongate struts, each incremental rotation of the second adjustment mechanism corresponding to a second fixed length. 
         [0018]    In accordance with another embodiment of this second aspect, the step of coupling the first bone segment to the first ring comprises coupling a first end of a bone pin to the first bone segment and coupling a second end of the bone pin to a pin retention member, the pin retention member being coupled to the first ring. The step of coupling the first bone segment to the first ring comprises coupling a first end of a bone wire to the first bone segment and coupling a second end of the bone wire to a wire retention member, the wire retention member being coupled to the first ring. 
         [0019]    In accordance with yet another embodiment of this second aspect, the method further includes transporting a position adjustment member along a length of one of the plurality of elongate strut members in the proximal or distal direction, the position adjustment member being in an unlocked state and being coupled to one of the plurality of bone transport assemblies; and locking the position adjustment member into a semi-locked state such that the position adjustment member engages a thread of the elongate strut member and such that the position adjustment member is unable to transport along a length of the elongate strut member in the proximal or distal direction independently of rotation of the thread. 
         [0020]    A third aspect of the present invention is a bone transport frame including first and second rings, a plurality of elongate struts, and a plurality of ring transport assemblies. The first and second rings each have upper and lower ring surfaces and a central axis that is perpendicular to the upper and lower ring surfaces. The plurality of elongate struts each having a central axis and are coupled to the first and second rings, the plurality of elongate struts each include a first adjustable member. Rotation of the first adjustable member transports the second ring in either a proximal or distal direction along the central axis of at least one of the plurality of elongate struts. The plurality of ring transport assemblies are adapted to rotatably couple the second ring to the plurality of elongate struts, wherein at least one of the plurality of ring transport assemblies comprises a flange and a ball joint, a first end of the flange being coupled to the second ring and a second end of the flange being coupled to one of the plurality of elongate struts, the ball joint enabling the second ring to rotate with respect to the plurality of elongate struts such that the central axis of the second ring is oblique to the central axis of each of the plurality of elongate struts. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Other aspects, aims and advantages of the present invention will become more apparent on reading the following detailed description of preferred embodiments thereof, given by way of example, and with reference being made to the attached drawings, in which: 
           [0022]      FIG. 1  is a perspective view of one embodiment of a bone transport frame in accordance with the present invention. 
           [0023]      FIG. 2  is an isometric view of the bone transport frame of  FIG. 1 . 
           [0024]      FIG. 3  is an exemplary view showing ring manipulation of the bone transport frame of  FIG. 1  in accordance with the present invention. 
           [0025]      FIG. 4  is a perspective view of a strut assembly of the bone transport frame of  FIG. 1 . 
           [0026]      FIG. 5  is a perspective view of a top click mechanism and flange of the bone transport frame of  FIG. 1 . 
           [0027]      FIG. 6  is a perspective view of the top click mechanism of  FIG. 5  and a top click mechanism screw driver. 
           [0028]      FIG. 7  is a vertical cross sectional view of the top click mechanism of  FIG. 5  at A-A. 
           [0029]      FIG. 8  is a horizontal cross sectional view of the top click mechanism of  FIG. 5  at B-B. 
           [0030]      FIG. 9  is a perspective view illustrating a bolted connection between a ring of the bone transport frame of  FIG. 1  and the top click mechanism and flange of  FIG. 5 . 
           [0031]      FIG. 10  is a perspective view illustrating the capability of the flange of  FIG. 5  to be mechanically connected to either the top or bottom of a ring of the bone transport frame of  FIG. 1 . 
           [0032]      FIG. 11  is a perspective view illustrating the capability of the strut assembly of  FIG. 4  to be connected to either the inside or outside of a ring of the bone transport frame of  FIG. 1 . 
           [0033]      FIG. 12  is a perspective view of one embodiment of a bone transport assembly of the bone transport frame of  FIG. 1  in accordance with the present invention. 
           [0034]      FIG. 13  is a perspective view illustrating the connection between a bone transport assembly and a ring of the bone transport frame of  FIG. 1 . 
           [0035]      FIG. 14  is a vertical cross sectional view of the ring transport assembly of  FIG. 12  at C-C. 
           [0036]      FIG. 15  is a vertical cross sectional view of the ring transport assembly of  FIG. 12  at D-D. 
           [0037]      FIG. 16  is a vertical cross sectional view of the ring transport assembly of  FIG. 12  at E-E. 
           [0038]      FIG. 17  is a perspective view of a quick release and frame height adjustment mechanism and flange in accordance with an embodiment of the present invention. 
           [0039]      FIG. 18  is a vertical cross sectional view of the quick release and frame height adjustment mechanism and flange of  FIG. 17  at F-F. 
           [0040]      FIG. 19  is vertical cross sectional view of the quick release and frame height adjustment mechanism of  FIG. 17  at G-G, which is orthogonal to section F-F. 
           [0041]      FIG. 20  is a perspective view of an alternate configuration of a quick release and frame height adjustment mechanism and flange of an embodiment of the present invention. 
           [0042]      FIG. 21  is a vertical cross sectional view of the quick release and frame height adjustment mechanism and flange of  FIG. 20  at H-H. 
           [0043]      FIG. 22  is a perspective view of another embodiment of a bone transport frame in accordance with the present invention. 
           [0044]      FIG. 23  is a perspective view of the bone transport assembly of  FIG. 22 . 
           [0045]      FIG. 24  is a perspective view of another embodiment of a bone transport frame in accordance with the present invention. 
           [0046]      FIG. 25  is a perspective view of a strut assembly of the bone transport frame of  FIG. 24 . 
           [0047]      FIG. 26  is a perspective view illustrating possible movements of the bone strut assembly of  FIG. 25 . 
           [0048]      FIG. 27  is a perspective view illustrating possible movements of the bone transport frame of  FIG. 24 . 
           [0049]      FIG. 28  is a perspective view of the bone transport frame of  FIG. 24  illustrating the position of a medial ring after transport has occurred. 
       
    
    
     DETAILED DESCRIPTION 
       [0050]    Where possible, identical or similar elements or parts are designated by the same reference labels. 
         [0051]    The term “proximal” and “distal” used throughout the present description correspond, respectively, to that end of the bone transport frame nearest the patient&#39;s heart and the end of the bone transport frame farthest from the patient&#39;s heart. 
         [0052]    Referring to  FIGS. 1-3 , a first embodiment of a bone transport frame  100  is shown. The bone transport frame  100  generally comprises a plurality of bone transport assemblies  150 , a plurality of bone transport rings  200 , a plurality of strut assemblies  300 , a plurality of top click mechanisms  400 , and a plurality of devices that interact with different segments or portions of a bone. 
         [0053]    Each of the bone transport rings  200  has a lower ring surface  280  and an upper ring surface  285  as well as an outer ring surface  290  and an inner ring surface  295 . Upper  285 , lower  280 , inner  295 , and outer  290  ring surfaces are substantially flat such that each ring has a vertical cross section that is substantially rectangular. In other embodiments, ring surfaces  280 ,  285 ,  290  and  295  need not be flat, but rather can take on various shapes to accommodate other devices such as clamps, for example. 
         [0054]    Along the circumference of each of the bone transport rings  200  resides a plurality of through-holes  210  that extend through both the upper  285  and lower  280  ring surfaces. The through-holes  210  facilitate mechanical connections between the strut assemblies  300  and numerous other devices the surgeon may deem necessary during use of bone transport frame  100 . 
         [0055]    Such devices, for example, include bone-pin retaining devices  920  and bone-wire retaining devices  960 . Due to the substantially flat contours of the ring surfaces and the plurality of through-holes  210 , a user is provided significant flexibility in appropriately placing the bone-pin retaining devices  920  and bone-wire retaining devices  960  at desired locations. Thus, a user can couple any of these devices at numerous locations around the circumference of each of the bone transport rings  200  as well as coupling the devices at the upper  285  or lower  280  ring surfaces of the bone transport rings  200 . Devices that can be used to facilitate interaction between the bone transport frame  100  and portions of a bone include, for example, a series of bone-wires  980  and bone-pins  940 . 
         [0056]    As shown in  FIGS. 1 and 2 , bone transport frame  100  includes a proximal ring  220 , a medial ring  240 , and a distal ring  260  wherein the proximal ring  220  is affixed to a first bone segment  820 , the medial ring  240  is affixed to a second bone segment  840 , and the distal ring  260  is affixed to a third bone segment  860 . The first bone segment  820  and second bone segment  840  are typically separated by an osteotomy created in the bone to allow for osteogenesis as the second bone segment is incrementally transported toward the third bone segment  840 . The second bone segment  820  and third bone segment  860  are typically separated by a deformity, such as a fracture or the like. 
         [0057]    Strut assemblies  300  act to stabilize the bone segments and to provide for transportation thereof.  FIGS. 1-3  show bone transport frame  100  including three strut assemblies  300 , but in other embodiments more than three strut assemblies  300  may be utilized, such as four, five, six or more strut assemblies  300 , for example. 
         [0058]    Referring to  FIGS. 4-8 , the proximal end of each strut assembly  300  includes a top click mechanism  400 . The top-click mechanism  400  includes a square head  410 , a clamping nut  420 , a clicking body  430 , a driver body  440 , a spring and ball system  460 , and a series of retaining balls  450 . The square head  410  provides an interface to mate with a screw driver  480  as shown in  FIG. 6 . The clamping nut  420  clamps a flange  700  to the top-click mechanism  400 . 
         [0059]    The driver body  440  is rigidly coupled to the strut  310  via a coupling member  415  and pin  417  so that rotation of the driver body  440  causes the strut  310  to rotate in unison with the driver body  440 . Further, the driver body  440  has an elongated portion  445  which terminates at the proximal end thereof as at square head  410 . 
         [0060]    A clicking body  430  fits over the elongated portion  445  of the driver body  440  like a sleeve, for example. The clicking body  430  is axially retained by a series of retaining balls  450  that allow the clicking body  430  to rotate with respect to the driver body  440  without translating with respect to the driver body. 
         [0061]    A cylindrical notch  470  is formed within the elongated portion of the driver body  440 . Within this cylindrical notch  470  resides a detent means in the form of a spring and ball system  460 , for example, which communicates with a series of recesses  490  on the internal portion of the clicking body  430  as shown in  FIG. 8 . The recesses or profile cuts  490  are created so that a portion of the ball of the spring and ball system  460  sits in and partially conforms to each of the profile cuts  490 . Further, the profile cuts  490  are such that as the driver body  440  is rotated, the ball of the ball and spring system  460  is capable of translating to an adjacent profile cut  490  creating a clicking sound and feel. 
         [0062]    Each profile cut  490  should be spaced and each strut  310  should be threaded so that each click corresponds with the strut  310  rotating a sufficient amount to cause the medial ring  240  to axially translate along the strut  310  a clinically optimal length. In one embodiment, the clinically optimal length is approximately 0.25 mm. At a rate of four “clicks” per day, the rate of osteogenesis between the first bone segment  820  and second bone segment  840  will be approximately 1 mm per day. However, a single “click” can correspond to different distances lengths, depending on the specific needs for a particular situation. 
         [0063]    The ball and spring system  460  additionally functions to constrain the driver body  440  and strut  310  from the rotation provided by the retaining balls  450 . Thus, the driver body  440  and strut  310  cannot rotate until a screw driver  480  applies the proper torque to the square nut  410  to overcome the force of the spring and ball system  460  and translate the ball to the adjacent profile cut  490 . 
         [0064]    An arrow  495  as shown in  FIG. 8  that points distally is etched on the outer surface of the clicking body  430  and is lined up with a corresponding number  485  etched on the outer surface of the driver body  440 . The numbers  485  are spaced such that each click corresponds to a rotation of the arrow  495  from a first number  485  to an adjacent number  485 . Preferably, the numbers  485  are placed on the flat surfaces of an octagon and numbered 1-4 and 4-1. This numbering is done so that the patient can keep track of the preferred four adjustments per day, for example. The clicking mechanism as disclosed in U.S. Patent Application Publication No. 2012/0041439 is hereby incorporated by reference herein in its entirety. 
         [0065]    As best seen in  FIG. 5 , a flange  700  extends from the outer surface of a portion of the clicking body  430  and is clamped against the clicking body  430  by a clamping nut  420 . When the flange  700  is coupled to a transport ring  200 , clamping the flange  700  will not only secure the flange to the clicking body  430  but also prohibits the clicking body  430  from rotating with the driver body  440  and strut  310 . 
         [0066]    The flange  700  includes anterior through-holes  740  and a medial through-hole  760  in a triangular pattern. The anterior through-holes  740  are the primary junctions for coupling the flange  700  to the bone transport rings  200 . A single retaining pin  720  can be used to couple the flange  700  to the through-holes  210  of the transport rings  200 . Alternately, both anterior through-holes  740  can be used, each in conjunction with a retaining pin  720 , to provide an anti-torque function that prevents rotation of the flange  700  with respect to the transport ring  200 . Other connection mechanisms besides retaining pints  720  can be used. For example, a user may choose to use a bolt and nut system in lieu of the retaining pin to secure the flange to the transport ring as seen in  FIGS. 9-10 . 
         [0067]    The flat surfaces of the flange  700  and the transport rings  200  allow the flange  700  to be coupled to the upper  285  or lower  280  ring surfaces of the transport rings  200  as seen in  FIG. 10 . This provides the user with the option of coupling a bone transport ring  200  to the top of flange  700  or to the bottom of flange  700 . Also, the dimensions of the flange  700  allow the strut assembly  300  to be coupled to the bone transport ring  200  such that the strut  310  can lie either inside the bone transport ring  200  or outside of the bone transport ring  200  as seen in  FIG. 11 . 
         [0068]    Referring to  FIGS. 12-16 , there are shown different illustrations of a bone transport assembly  150  of the first embodiment of the invention. The bone transport assembly generally includes a ball and socket joint  500 , a quick release mechanism  600 , and a translational rod  1000 . 
         [0069]    The ball and socket joint  500  has a hyperbolic collar  595  that fits loosely over the distal end of the quick release mechanism  600  and is coupled to the quick release mechanism  600  by a locking nut  620  that substantially conforms to the shape of the hyperbolic collar  595 . When the locking nut  620  is loosened, the ball and socket joint  500  is free to swivel about a three dimensional axis until the locking nut  620  is tightened, thereby locking the ball and socket joint  500  at its latest position. This feature enables the medial ring  240  to rotate so that it is no longer parallel with the proximal  220  and distal  260  rings, thus allowing the second bone segment  840  to be more precisely aligned with the third bone segment  860  as the distraction osteogenesis process progresses. An example of a medial ring  240  being non-parallel to a proximal  220  and distal  260  ring is shown in  FIG. 3 , for example. The ball and socket joint  500  also helps in aligning second bone segment  840  with third bone segment  860  during the docking process. A user can accomplish this by unlocking locking nut  620 , marginally loosening the ball and socket joint  500 , and rotating at least one of the top click mechanism  400  and translational short rod  1000  or translation bolt  730 . 
         [0070]    The hyperbolic collar  595  terminates on two sides with a first retaining ring  575  on one side and a second retaining ring  585  on the opposing side. The first retaining ring  575  connects and retains the translational rod  1000  to the ball and socket joint  500  by way of a series of retaining pins  565 . The second retaining ring  585  provides the user the option to add an extra rod of any type, for example, to provide extra stiffness to the frame  100 , if desired. 
         [0071]    The translational rod  1000  has a structure similar to the click mechanism  400 . One end of the translational rod  1000  terminates in a square head  1010  that can mate with a driving tool such as a screw driver. The translational rod  1000  includes a driving body  1040  with a cylindrical notch  1070  that houses a spring and ball system  1060 . A first retaining ring  575  includes recesses or profile cuts  1090 . As the driving body  1040  is rotated, the ball of the spring and ball system  1060  may move from one profile cut  1090  and into an adjacent profile cut  1090 . 
         [0072]    The driving body  1040  is threadedly mated to a connector piece  1085 . The connector piece  1085  includes an aperture  1095 . The connector piece  1085  can be fixed to a bone transport ring  200  by means of a fastener, such as a locking nut  1097  that extends through a through-hole  210  of a bone transport ring  200  and further through the aperture  1095  of the connector piece  1085 . 
         [0073]    When the square head  1010  of the translational short rod  1000  is rotated, for example by a screw driver, the driving body  1040  rotates. As the driver body  1040  rotates, the spring and ball system  1060  provides feedback to the user each time the ball moves into one of the profile cuts  1090  of the first retaining ring  575 . The rotation of the driver body  1040  forces the outer body  1080  to move axially. The axial movement of the outer body  1080  is caused by the inability of the outer body  1080  to rotate, due to the rigid connection to the connecting piece  1085  and the bone ring  200 . The axial movement of the outer body  1080  causes the connector piece  1085  to move in conjunction with the outer body  1080 . Finally, the movement of the connector piece  1085  moves the bone transport ring  200  to which the connector piece  1085  is attached, allowing translation of the bone transport ring  200  towards or away from strut assembly  300 . This translation of the medial ring  240  may be useful when “docking” the bone. The docking phase is reached at the end of the transport phase, when the second bone segment  840  reaches the third bone segment  860 . Sometimes the two bone segments do not align well and then it becomes advantageous to translate the medial ring  240  to correct the alignment between the second bone segment  840  and the third bone segment  860 . 
         [0074]    Quick release mechanism  600  of bone transport assembly  150  allows for quick adjustment of the medial ring  240  compared to the finer adjustment by the top click mechanism  400 . It should be noted that the quick release mechanism  600  is only intended to be used prior to fixation of the bone transport frame  100  to the patient. Because the distal ring  260  includes an anti-torque quick release mechanism  605 , which is substantially similar to the quick release mechanism  600 , the workings of the quick release mechanism  600  are omitted here and are described with reference to the anti-torque quick release mechanism  605 . 
         [0075]    Referring to  FIGS. 17-21 , the distal portion of the strut assembly  300  generally includes a flange  700 , an anti-torque quick release mechanism  605 , and a tapered nut  630 . 
         [0076]    The anti-torque quick release mechanism  605  has an unlocked state, a semi-locked state, and a locked state. In the unlocked state, the anti-torque quick release mechanism  605 , flange  700  and attached distal ring  260  are free to move vertically up or down the strut  310  regardless of rotation of the strut  310 . This allows for quick adjustment of the distal ring  260  prior to fixing the bone transport frame  100  to the patient&#39;s bone. The quick release mechanism  600  provided with the medial ring  240  has the same feature. 
         [0077]    In the semi-locked state, the anti-torque quick release mechanism  605  travels vertically up or down the strut  310  with rotation of the strut  310  by the top click mechanism  400 . To switch from the unlocked state to the semi-locked state, the user rotates the anti-torque quick release mechanism  605 . To accomplish this, the body of the anti-torque quick release mechanism  605  is pushed proximally, compressing spring  670 . This moves locking pin  680  into a position in groove  690  which allows for rotation of the body of the anti-torque quick release mechanism  605 . Rotation is continued until the locking pin  680  traverses to the opposite side of the groove, allowing the spring to decompress. Once rotated, the bearings  660  engage the thread of the strut  310 , disabling the anti-torque quick release mechanism  605  from freely travelling vertically up or down the strut  310 . Rather, it will move vertically up or down the strut  310  only with rotation of the strut  310  by virtue of rotation of the top click mechanism  400 . It should be noted, however, that this function is only desirable for the quick release mechanism  600  coupled to the bone transport assembly  150 , and not for the anti-torque quick release mechanism  605 . 
         [0078]    The anti-torque quick release mechanism  605  should only be configured in the unlocked state or the locked state, and not the semi-locked state. To switch from the semi-locked state to the locked state, the tapered nut  630  is threaded onto sleeve  640 . Because of the taper inside tapered nut  630 , the collet  635  at the tip of sleeve  640  bends inward and creates friction with the strut  310  when the tapered nut  630  is tightened. This friction causes the tapered nut  630 , sleeve  640  and strut  310  to move as a single unit, rotating together with the strut  310 . This rotation is possible because of the retaining balls  650 , which allow these pieces to rotate inside the flange  700 . The flange  700  is connected to the distal ring  260 . Because there is no thread at the interface between the flange  700  and the combination tapered nut  630 , sleeve  640  and strut  310 , the distal ring  260  is not driven vertically up or down the strut  310  when it is rotated by actuation of the top click mechanism  400 . The quick release mechanism  600 , on the other hand, has no anti-torque feature and thus can only be in the unlocked or semi-locked state. When the quick release mechanism  600  is in the semi-locked state, the medial ring  240  thus can be driven vertically up or down the strut  310  allowing for transport. 
         [0079]    The bearings  660 , in addition to enabling the switch from the unlocked to the semi-locked positions, take much of the axial load when that load moves from the strut  310  to the sleeve  640  (e.g. when the patient is standing). The bent collet  635  alone may not be able to take all that axial loading. A screw  695  is provided at the far distal end of the strut  310  to prevent the anti-torque quick release mechanism  605  from sliding off the strut  310  when it is in the unlocked state and the distal ring  260  is being adjusted. 
         [0080]    Referring to  FIGS. 22-23 , a second embodiment of a bone transport frame  100 ′ is shown. The bone transport frame  100 ′ generally includes a plurality of bone transport assemblies  150 ′, a plurality of bone transport rings  200  and a plurality of strut assemblies  300 . 
         [0081]    One difference between the second embodiment shown in  FIGS. 22-23  and the first embodiment shown in  FIGS. 1-3  is that the bone transport assembly  150 ′ coupled to the medial ring  240  includes a different structure such that the gradual translation of the medial ring  240  does not occur by way of a clicking mechanism. 
         [0082]    The second embodiment of the bone transport assembly  150 ′ comprises a quick release mechanism  600 , a ball jointed flange  705 , a series of hinge pin and bracket assemblies, a series of nuts, and a translational bolt. 
         [0083]    The ball jointed flange  705  has a hyperbolic collar  595  much like the hyperbolic collar  595  seen on the ball joint  500  of the first embodiment. This ball jointed flange  705  is also coupled to the quick release mechanism  600  by means of the same locking nut  620 . However, rather than terminating with a first retaining ring  575  and a second ring  585 , the hyperbolic collar  595  terminates with a flange like that disclosed elsewhere herein. A hinge pin  715  is coupled to the ball jointed flange  705  through the medial through-hole  760  and is axially retained by a series of nuts  725 , but is capable of rotation within the medial through-hole  760 . The hinge pin  715  terminates at the proximal end with a bracket  710 . Another hinge pin  715  and bracket  710  is coupled to a through-hole  210  of the medial ring  240 . A translating bolt  730  connects both of the hinge pin  715  and bracket  710  assemblies and is retained by a series of nuts  725 . The hinged connection in combination with the translating bolt  730  allows the surgeon to translate the medial ring  240  toward or away from the struts  310 . This is accomplished by rotating the translating bolt  730 . Furthermore, the ball jointed flange  705  allows for swivel about a three dimensional axis. These features combine to provide the medial ring  240  with six degrees of freedom. 
         [0084]    Referring to  FIGS. 24-28 , there is shown a third embodiment of a bone transport frame  100 ″. A difference between the bone transport frame  100 ″ shown in  FIGS. 24-28  and previous embodiments is that medial ring  240  does not have the capability of horizontal translation. 
         [0085]    Structurally speaking, the embodiment shown in  FIGS. 24-28  is obtained by taking the embodiment of the bone transport frame  100 ′ shown in  FIGS. 22-23 , removing the translating bolt  730  and accessories, and directly attaching the ball jointed flange  705  to the medial ring  240 . As disclosed elsewhere herein, the ball jointed flange  705  can connect to the medial ring  240  by virtue of a retaining pin  720  that extends through both a through-hole  210  of the medial ring  240  and through an anterior through-hole  740  of the ball jointed flange  705 . This permits the medial ring  240  to move such that it is no longer parallel with proximal ring  220  and distal ring  260 , but there are no mechanisms for translating medial ring  240  toward or away from the struts  310  as shown in  FIG. 28 . 
         [0086]    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.