Patent Publication Number: US-2013245625-A1

Title: Adjustable orthopedic fixation system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of U.S. application Ser. No. 12/618,514, which was filed on Nov. 13, 2009 and is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to orthopedic fixation systems, more particularly to improved orthopedic fixation systems that use a plurality of rigid struts of equal or non-equal length to support a pair of base members, such as rings affixed to respective bone parts with pins. 
     BACKGROUND 
     Without limiting the scope of the present disclosure, this background is described in connection with external fixation devices. Generally, external fixation devices are commonly used on both the upper and lower limbs for both adults and children in a variety of surgical procedures including limb lengthening, deformity correction and treatment of fractures, mal-unions, non-unions and bone defects. Such orthopedic fixation systems may be utilized to treat fractures of the skeleton, soft tissue injuries, delayed union of the skeleton when bones are slow to heal, nonunion of the skeleton when bones have not healed, mal-union where broken or fractured bones have healed in a mal-position, congenital deformities where bones develop a mal-position, and bone lengthening, widening, or twisting. These systems are sometimes called “halo” systems or “hexapod” type circular ring fixation systems. 
     Such ring-based fixator systems are typically placed on the affected patient by medical personnel in such a way as to align the affected body part during the healing process, holding the affected body part in the proper position for treatment. For example, such fixators may be used to stabilize bone fragments by holding the fragments in a relatively fixed spatial relation, and are adjustable orthopedic systems that allow the physician or other medical professional to reorient one fragment with respect to another along all six axes in an acute motion, usually by loosening one or more clamps and effecting the corrective motion manually and then retightening clamps to stably hold the fragments in the desired position. Since applications of such devices can include a wide variety of deformities, body sites, and surgical implementations, there is a need for fixation devices that can initially be acutely adjusted in order to accommodate such variabilities, and subsequently maintain the affected body part in one desirable position. Moreover, a typical treatment regimen requires frequent adjustments to be performed by the patient and/or during repeated visits to medical professionals so that the fixation device can be periodically and gradually adjusted, providing the desired orientation to the affected body part and setting the proper amount of support and stretching or compression for healing. 
     One common external fixation device of type discussed above is known as the Ilizarov apparatus. The Ilizarov external fixation procedure involves a rigid framework consisting of several rings or arches that are placed externally around the limb, and attached to injured (e.g., due to fracture) or surgically separated (e.g., for limb lengthening and deformity correction) bone segments using special bone fasteners (wires and pins) inserted into the bone segment and connected to the related section of the external rigid framework. 
     Another common external fixation device of the type discussed above is a Taylor Spatial Frame, as described in U.S. Pat. Nos. 6,030,386, 5,891,143, and 5,776,132. The Taylor Spatial Frame is a hexapod-type of device and shares many components and features of the Ilizarov apparatus. The Taylor Spatial Frame consists of two external fixator rings attached to bone segments by wires or half-pins, and connected together by six struts that may be lengthened or shortened as necessary. Adjustment of strut lengths allows manipulation of the bone segments in 6 axes (e.g., lengthening/shortening, external/internal rotation, anterior/posterior horizontal translation, medial/lateral horizontal translation, anterior/posterior angular translation, and medial/lateral angular translation) to correct linear, angular and rotational deformities simultaneously. 
     Looking specifically into their functionality, with most fixators based on rings or arches like those discussed above, the opposite rings/frames of the rigid framework are connected by either threaded or telescopic connection rods or by assembled uni-planar or multi-planar angular hinges, which allow the medical professional to adjust the relative position of the rings to each other longitudinally or angularly over a period of time. This allows new bone to gradually form in the gap between bone segments created by this distraction technique. Once the desired position of bone segments is achieved over the course of time (e.g., 2-6 weeks), the external apparatus is stabilized into a fixed position and left on the bone segments until the fracture is healed or newly formed bone is completely or substantially mineralized, which could take up to an additional 3-6 months, depending on the nature of pathology and degree of deformity. 
     Based on the above, current orthopedic fixation systems may have a number of mechanical benefits, including flexibility in positioning one ring with respect to another, and strength during compressive loading. However, configurations that can provide a full six degrees of freedom between two circular fixator rings typically require adding struts to increase range of movement, which is problematic from a clinical use perspective, or require having fewer struts, which requires multiple degrees of controllable motion within each strut and thereby unfortunately reducing the overall system strength in supporting loads. Accordingly, an orthopedic ring fixation system is needed that provides six degrees of freedom, but that is easy to configure and does not reduce the overall system strength. Still other objects and advantages of the invention will become clear upon review of the following detailed description in conjunction with the appended drawings. 
     SUMMARY 
     Disclosed herein are improved orthopedic fixation systems that use a plurality of rigid struts, typically of equal or un-equal length, to support a pair of base members, such as rings affixed to respective bone parts with pins. The orthopedic fixation systems can comprise two rings separated by the plurality of struts. The one or more of the struts are attached to the rings by a combination of a moveable attachment mechanism and a slidable connecting mechanism. The slidable connecting mechanisms are connected to and slide along one or more tracks located on the two base elements, which allows for six degrees of freedom of movement between the base elements. 
     In one embodiment, an orthopedic fixation system may comprise a first base element comprising at least one track located on at least a portion of the perimeter of the first base element, and a second base element comprising at least one track located on at least a portion of the perimeter of the second base element. This embodiment of the system may also comprise at least six rigid struts spanning between the first base element and the second base element, each of the struts comprising an upper attachment mechanism and a lower attachment mechanism on opposite ends, where the attachment mechanisms are each capable of at least two degrees of movement. In addition, the system may comprise one or more upper connecting mechanisms for moveably connecting one or more corresponding ones of the upper attachment mechanisms to the track of the first base element, as well as one or more lower connecting mechanisms for moveably connecting one or more corresponding ones of the lower attachment mechanisms to the track of the second base element. 
     In another embodiment, an orthopedic fixation system may comprise an upper ring comprising at least one circumferential track and six upper connecting members which are moveable around the at least one track, and a lower ring comprising at least one circumferential track and six lower connecting members which are moveable around the at least one track. In such an embodiment, the system may also comprise at least six struts, each strut comprising a rigid rod, an upper attachment member having at least two degrees of movement at one end, and a lower attachment member having at least two degrees of movement at an opposing end. In these embodiments, each upper attachment member is connected to a corresponding one of the upper connecting members, and each lower attachment member is connected to a corresponding one of the lower connecting members. 
     In yet another embodiment, an orthopedic fixation system may comprise an upper ring comprising a first circumferential track having at least three first upper connecting members, one or more of which are moveable around the first track, and a second circumferential track having at least three second upper connecting members, one or more of which are moveable around the second track. The fixation system may also comprise a lower ring comprising a third circumferential track having at least three first lower connecting members, one or more of which are moveable around the third track, and a fourth circumferential track having at least three second lower connecting members, one or more of which are moveable around the fourth track. The system may further comprise at least six struts, each strut comprising a rigid rod, an upper attachment member having at least two degrees of movement at one end, and a lower attachment member having at least two degrees of movement at an opposing end. In such embodiments, the at least three upper attachment members on the first track are connected to corresponding ones of the at least three first upper connecting members, and the at least three upper attachment members on the second track are connected to corresponding ones of the at least three second upper connecting members. Furthermore, the at least three lower attachment members on the third track are connected to corresponding ones of the at least three first lower connecting members, and wherein the at least three lower attachment members on the fourth track are connected to corresponding ones of the at least three second lower connecting members. 
     In yet a further embodiment, an orthopedic fixation system constructed according to the disclosed principles may comprise a first base element and a second base element, at least one of the first or second base elements comprising at least one track located on at least a portion of the perimeter of the first base element. Such a system may also comprise a plurality of rigid struts spanning between the first and second base elements, each of the struts comprising an upper attachment mechanism and a lower attachment mechanism on opposite ends, where the attachment mechanisms are each capable of at least two degrees of movement. Such embodiments may further comprise one or more upper connecting mechanisms for connecting one or more corresponding ones of the upper attachment mechanisms to the track of the first base element, and one or more lower connecting mechanisms for connecting one or more corresponding ones of the lower attachment mechanisms to the track of the second base element. In these embodiments, at least one of the upper and lower connecting mechanisms is moveable along a corresponding one of the at least one track. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description along with the accompanying figures and in which: 
         FIG. 1  is a perspective view of an embodiment of an orthopedic fixation system of the present invention; 
         FIG. 1A  is a side view of the embodiment of the orthopedic fixation system of  FIG. 1 ; 
         FIG. 2  is a perspective view of an alternate embodiment of an orthopedic fixation system of the present invention; 
         FIGS. 3   a - 3   d  are cross-sectional views of exemplary embodiments of carriage shapes for use as connecting mechanism disclosed herein; 
         FIG. 4  is a perspective view of yet another embodiment of an orthopedic fixation system of the present invention; and 
         FIG. 4A  is a side view of the embodiment of the orthopedic fixation system of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is of the best mode or modes of the invention or inventions presently contemplated. Such description is not intended to be understood in a limiting sense, but to be an example of the invention presented solely for illustration thereof, and by reference to which in connection with the following description and the accompanying drawings one skilled in the art may be advised of the advantages and construction of the invention. The invention is intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     An embodiment of an orthopedic fixation system is shown in  FIG. 1  and identified by the numeral  100 . The orthopedic fixation system  100  includes a first base element  102  and a second base element  104 . The first base element  102  and the second base element  104  are preferably spaced apart by a plurality of struts  106   a - 106   f . Although six struts  106  of substantially equal length are illustrated, none of the embodiments of a fixator device constructed as disclosed herein is limited to specifically six struts  106 , nor is there any limitation to the use of all equal length struts  106 . In fact, in some applications, the fixator device  100  may specifically require struts  106  of unequal length for proper implementation. In addition, although only two base elements  102 ,  104  are illustrated and described below, it should be understood that 3 or more base elements may also be employed with the principles of the present disclosure disclosed herein. Moreover, although such base elements are often discussed herein as “rings,” it should be understood that an entirely circular shape for the elements is not necessarily intended. Also, the elements may comprise only partially enclosed fixator elements, such as only a partial circular structure. 
     Furthermore, elements in the accompanying drawings that are the same except for their location have been given the same number but a different alphabetic character. For example, a first strut is  106   a , a second strut  106   b , etc. If there are a plurality of the same element, then only one such element is described and all such elements are deemed identical. Moreover, the materials of all parts/components described herein may be those materials typically used in orthopedic instruments and known to those skilled in the art, for example, but not limited to, stainless steel, fiberglass, titanium, etc. In advantageous embodiments, some or all of the materials may be constructed from radiotranslucent materials, to aid in the x-raying of the afflicted area being treated by the fixator  100 . Of course, no limitation to any particular material is intended or should be implied. 
     Struts  106  include an upper attachment mechanism  108   a - 108   f  and a lower attachment mechanism  110   a - 110   f . Each upper attachment mechanism  108  is mounted to an upper connecting mechanism  112   a - 112   f  in a manner that can provide at least two degrees of movement. Each lower attachment mechanism  110  is also mounted to a lower connecting mechanism  114   a - 114   f  in a manner that can provide at least two degrees of movement. The upper connecting mechanisms  112  are slidably (or otherwise moveably) mounted on the first base element  102 , and the lower connecting mechanism  114  are slidably (or otherwise moveably) mounted on the second base element  104 , using carriages or a similar structure that permits sliding of the mechanisms  112 ,  114  around the rings, but not for the mechanisms  112 ,  114  to be removed from the rings when pressure is applied using the struts  106 . It should be noted that in many embodiments, all of the upper and lower connecting mechanisms  112 ,  114  are moveably connected to the tracks/base elements  102 ,  104 ; however, in other embodiments less than all of the connecting members  112 ,  114  are moveably connected to the base elements  102 ,  104 , and are instead fixedly connected thereto. Accordingly, the movements of the struts  106  described herein may be made to all of the strut  106  ends, or only to some of them. 
     In a preferred embodiment, the first base element  102  is a substantially circular ring for placing around a patient&#39;s leg. The first base element  102  may be provided in various shapes and sizes, dependent upon the patient&#39;s frame and/or the afflicted area to be treated. For example, base elements employed herein may not necessarily be completely enclosed, such as comprising a semi- or partial-circular shape, or even just a partial linearly-shaped frame, or even an angled frame. The first base element  102  further includes a plurality of apertures  116  therethrough. The apertures  116  are sized, shaped and spaced apart for securing transfixation screws, wires or pins, etc., to be secured thereto with typical fixator clamps or the like, as will be apparent to those skilled in the art for securing the first base element  102  to a patient&#39;s bone. In addition, the apertures  116  provide places for the affixing of additional struts or other support components designed to help hold the relative positions of the first and second base elements  102 ,  104 . In such embodiments, the apertures  116  may also provide locations for attaching a third base element (not illustrated) to either the first or second base elements  102 ,  104 . 
     The first base element  102  may also include one or more tracks  118  for use with the sliding mechanisms  112  disclosed above. In the illustrated embodiment of  FIG. 1 , two tracks  118   a ,  118   b  are present on the upper base element  102 . The track(s)  118  may be integral to the first base element  102  or may be a separate component attachable to the first base element  102 . In embodiments employing attachable tracks  118 , the tracks  118  (and any necessary strut  106  connecting components) may beneficially be retrofitted to ring/base elements not having tracks. Accordingly, the advantages provided by the principles of the present disclosure may be extended to existing fixator designs. 
     The tracks  118  allow for circumferential movement of the upper connecting mechanism  112  around the first base element  102 . However, in embodiments where either or both of the base elements  102 ,  104  are not circular or otherwise fully enclosed, the track(s) may  118  simply follow the shape and extent of the base element(s) employed. Thus, although circular base elements  102 ,  104  with circumscribing tracks  118  are discussed herein, it should be understood that no limitation to such a specific design and structure is intended. Further, while the tracks  118  are illustrated with a specific groove structure, the tracks  118  may be comprised of any mechanism which allows for the connection and the movement of the upper connecting mechanism  112  around the first base element  102 . In addition, the tracks  118  may include teeth configured to engage one or more gears associated with the struts, as described in further detail below. While in a preferred embodiment, the first base element  102  includes first and second tracks  118   a ,  118   b , more or less tracks are also within the broad coverage of the present disclosure. 
     Also in a preferred embodiment, the second base element  104  is also a substantially circular ring for placing around a patient&#39;s leg. Like the first base element  102  in such an embodiment, the second base element  104  may be various shapes and sizes, dependent upon the patient&#39;s frame. The second base element  104  further includes a plurality of apertures  120  therethrough. The apertures  120  are sized, shaped and spaced apart for securing transfixation screws, wires or pins, additional base elements, etc., to be secured thereto with typical fixator clamps or the like as will be apparent to those skilled in the art for securing the second base element  104  to a patient&#39;s bone. The second base element  104  also includes one or more tracks  118 . The track  118  may again be integral to the second base element  104  or may be a separate component attachable to the second base element  104 . The track  118  allows for circumferential movement of the lower connecting mechanism  114  around the second base element  104 . While a track  118  is shown, the track  118  may be any mechanism which allows for the movement of the lower connecting mechanism  114  around the second base element  104 . In a preferred embodiment, the second base element  104  further includes a first track  118   a  and a second track  118   b.    
     In a preferred embodiment, there are six struts  106 , being substantially identical. Of course, in other configurations, there may be a fewer or greater number of struts  106 . For example, in embodiments where the first and second base elements  102 ,  104  comprise square shapes or octagon shapes, the number of struts  106  (or pairs of struts  106 ) may correspond to the sides of such shapes. The struts  106  may be a solid rod having a fixed length, although adjustable length struts may be employed for one or more of the struts  106 . The length will be dependent, at least partially, upon the length of the patient&#39;s bone, as well as the course of therapy for the affliction of that bone. In the present disclosure, when describing only one strut  106  and its corresponding upper attachment mechanism  108  and lower attachment mechanism  110 , the description would be true for all struts  106 . On a first end of the strut  106  is the upper attachment mechanism  108 , on the opposite end of the strut  106  is the lower attachment mechanism  110 . In some embodiments, the upper attachment mechanism  108  and the lower attachment mechanism  110  are substantially identical. 
     The upper attachment mechanism  108  may be any mechanism capable of allowing a variable range of motion between the strut  106  and the first base element  102 , via the upper connecting mechanism  112 . In the illustrated embodiment, the upper attachment mechanism  108  is a passive ball-and-socket joint. However, in other embodiments, the upper attachment mechanism  108  may be a universal joint, a heim joint, a johnny joint, or any joint known by one skilled in the art or even later developed that would allow the range of motion described herein. In some embodiments, the upper attachment mechanism  108  is connected to the end of the strut  106  by means known to one skilled in the art, for example, it may be welded. In other embodiments, the upper attachment mechanism  108  may include a threaded extension threaded into the end of the strut  106 . Alternatively, the upper attachment mechanism  108  may include a different type of extension element that is otherwise connected to the end of the strut  106 . Moreover, that means of connection between such an extension and the strut  106  may be adjustable, thus adjusting the relative position of the upper attachment mechanism  108  with respect to the strut  106 , and thereby adjusting the distance between the first and second base elements  102 ,  104  along the length of that strut  106 . In still other embodiments, the upper attachment mechanism  108  may be an integral part of the strut  106 . 
     The upper attachment mechanism  108  is also connected to the upper connecting mechanism  112 . As described above with regard to the upper attachment&#39;s  108  connection to the strut  106 , the upper attachment  108  may also be connected to the upper connecting mechanism  112  in a variety of ways. For example, the upper attachment mechanism  108  may be welded to the upper connecting mechanism  112 , or it may be threadedly attached to the upper connecting mechanism  112 . 
     As mentioned above, and as illustrated in  FIG. 1 , the upper connecting mechanism  112  is connected to the first base element  102  via one or more tracks  118 . While describing only one upper connecting mechanism  112  and its connection to the track(s)  118 , the description would be true for all upper connecting mechanisms  112 . The upper connecting mechanism  112  is preferably a carriage that is slidably connected to the track  118 . As used herein, the term “carriage” is broadly defined to include any component designed to carry something on or along something else. For example, the connecting mechanisms  112 ,  114  comprise carriages configured to carry the ends of the struts  106  along the tracks  118 . 
     Dependent upon the placement of the other struts  106 , the upper connecting mechanism  112  is connected to either the first track  118   a  or the second track  118   b , for a two-track system. Furthermore, as illustrated in  FIG. 1 , the first rack  118   a  is provided as a raised structure configured to be received in a similarly sized slot or groove in one or more of the upper connecting mechanisms  112 . Conversely, the second track  118   b  is illustrated as a slot or groove configured to received the upper connecting mechanism(s)  112  therein. In an advantageous embodiment, the grooves in either the upper connecting mechanism(s)  112  or the track(s) is provided as a dove tail, which beneficially allows the upper connecting mechanism(s)  112  to slide (or otherwise move, in other embodiments) along the track  118  (and around the first base element  102 ), while securely maintaining the upper connecting mechanism(s)  112  within the groove. Of course, however, the grooves, whether in the track  118  or the upper connecting mechanism(s)  112  can have any shape providing the relative movement described herein.  FIGS. 3   a - 3   d  illustrate cross-sectional views of some exemplary embodiments of carriage shapes for use as the connecting mechanisms  112   a - 112   d  (and/or  114   a - 114   d ). Of course, depending on the configuration and shape of the carriage(s) used, the track(s) for such carriage(s) would have a corresponding mating cross-sectional shape. 
     By connecting the upper attachment mechanism  108  to the upper connecting mechanism  112  and not directly to the first base element  102 , the strut  106  is capable of an unlimited set of orientations with six degrees of motion of the first base element  102 . Additionally, although a carriage-type upper connecting mechanism  112  is illustrated in  FIG. 1 , the upper connecting mechanism  112  may be any mechanism which allows the upper attachment mechanism  108  to be moved in a circumferential path via the track  118  around the first base element  102 . 
     The upper connecting mechanism  112  translates along the first base element  102  via the one or more tracks  118 . In some embodiments, the upper connecting mechanism  112  and/or the track  118  may include a drive system to gradually and controllably re-orient the first base element  102 . For example, the carriages comprising the upper connecting mechanisms  112  (and/or the lower connecting mechanisms  114  discussed below) could include one or more gears therein configured to engage teeth located on or within the tracks  118 . The drive system could then comprise one or more points through which the gear(s) in the carriages are turned in order to move the carriages along the tracks  118 .  FIGS. 4 and 4A , described below, illustrate such an embodiment. In other embodiments, a worm gear-based drive system may be employed, where the carriage(s) include the screw of the system, and the track(s)  118  again include teeth to corresponding to drive screw. 
     The drive system could also include a locking mechanism that would hold the upper connecting mechanism  112  in a static position until intentionally moved to reposition the struts  106  and thus re-orient the first base element  102 . The drive system may be, for example, a rack and pinion system, and may include one or more non-moving gears on the carriage(s) configured to engage the teeth on the track(s)  118  for locking, and disengage the teeth for unlocking, the movement of the carriage(s). In other embodiments, a simple screw (e.g., a thumb screw, set screw, or the like) passing through the carriage(s) and contacting the track(s)  118  may provide the locking mechanism. In embodiments employing a worm gear drive system, stopping the turning of the screw in the carriage(s) when adjustments are finished may be enough to prevent further movement of the carriage(s), and thus provide the locking mechanism. 
     In some embodiments, the drive system may be separate from the fixator device  100 , and removably attached to the fixator device  100  to drive the locations of the carriages comprising the upper connecting mechanisms  112 . However, the drive system may still be manipulated by medical personnel to position or reposition the upper connecting mechanisms  112  with respect to the first base element  102 . In most embodiments, regardless of drive system, the upper connecting mechanisms  112  are capable of moving independently from one another, accordingly providing great degree of movement of the first base element  102  with respect to the second base element  104 . However, in still other embodiments, two or more struts  106  may have their ends that are proximate either of the base elements  102 ,  104  connected to a single connecting mechanism  112 . In such embodiments, the other ends of those end-connected struts  106  may still be independent from one another. 
     Similar to the upper attachment mechanisms  108  described above, the lower attachment mechanisms  110  may be any mechanism capable of allowing a variable range of motion between the strut  106  and the second base element  104 , via the lower connecting mechanisms  114 . In the illustrated embodiment, the lower attachment mechanism  110  is also a passive ball-and-socket joint. However, in other embodiments, the lower attachment mechanism  110  may be a universal joint, a heim joint, a johnny joint, or any joint known by one skilled in the art or even later developed that would allow the range of motion described herein. In some embodiments, the lower attachment mechanism  110  is connected to the end of the strut  106  by means known to one skilled in the art, such as the welding described above. In other embodiments, the lower attachment mechanism  110  may include a threaded extension threaded into the end of the strut  106  opposite to the upper attachment mechanism  108 . Alternatively, the lower attachment mechanism  110  may include a different type of extension element that is otherwise connected to the end of the strut  106 . Moreover, as with the upper attachment mechanism  108 , that means of connection between such an extension and the strut  106  may be adjustable, thus adjusting the relative position of the lower attachment mechanism  110  with respect to the strut  106 , and thereby adjusting the distance between the first and second base elements  102 ,  104  along the length of that strut  106 . In still other embodiments, lower attachment mechanism  110  may simply be an integral part of the strut  106 . 
     The lower connecting mechanism  114  is connected to the second base element  104  via one or more tracks  118 . While describing only one lower connecting mechanism  114  and its connection to the track(s)  118 , the description would be true for all lower connecting mechanisms  114 . Moreover, it is again emphasized that not all of the lower connecting mechanisms  114  are necessarily moveably connected to the second base element  104 , and thus one or more may be fixed to the base element  104 . The lower connecting mechanism  114  is also preferably a carriage that is slidably (or otherwise moveably) connected to the track  118  on the lower base element  104 . Dependent upon the placement of the other struts  106 , the lower connecting mechanism  114  is connected to either the first track  118   a  or the second track  118   b , for a two-track system, such as that illustrated in  FIG. 1 . As also illustrated in  FIG. 1 , the second rack  118   b  on the second base element  104  is the one provided as a raised structure configured to be received in a similarly sized slot or groove in one or more of the lower connecting mechanism  114 . Conversely, the first track  118   a  is illustrated as a slot or groove configured to received the lower connecting mechanism(s)  114  therein. In an advantageous embodiment, the grooves in either the lower connecting mechanism(s)  114  or the track(s) on the lower base element  104  are again provided as a dove tail, which beneficially allows the lower connecting mechanism(s)  114  to slide along the track  118  (and around the second base element  104 ), while securely maintaining the lower connecting mechanism(s)  114  within the groove. Of course, however, the grooves, whether in the track  118  or the lower connecting mechanism(s)  114  can have any shape providing the relative secure connection and movement described herein. 
     By connecting the lower attachment mechanism  110  to the lower connecting mechanism  114  and not directly to the second base element  104 , the strut  106  is capable of an unlimited set of orientations with six degrees of motion of the second base element  104 . Additionally, although a specific structure is illustrated for the lower connecting mechanism  114  is illustrated in  FIG. 1 , the lower connecting mechanism  114  may be any mechanism which allows the lower attachment mechanism  110  to be moved along the track  118  of the second base element  102 , or may be fixed with respect to the lower base element  104  for those strut ends not intended to move along the track. 
     The lower connecting mechanism  114  translates along the second base element  104  via the one or more tracks  118 . In some embodiments, the lower connecting mechanism  114  and/or the track  118  may include a drive system to gradually and controllably re-orient the second base element  104 . This drive system may be the same or different from a drive system incorporated or employed with the upper connecting mechanisms  112  and the upper track  118 . As before, the drive system could also include a locking mechanism that would hold the lower connecting mechanism  114  in a static position until intentionally moved to reposition the struts  106  and thus re-orient the second base element  104 . The system may be, for example, a rack and pinion system or a worm gear system, or any other beneficial drive system capable for use herein. In other embodiments, as discussed above, the drive system may be separate from the fixator device  100 , and removably attached to the fixator device  100  to drive the locations of the lower connecting mechanisms  114  as well. Still further, the drive system may simply be manipulation by medical personnel to position or reposition the lower connecting mechanisms  114  with respect to the second base element  104 , and thus not include any mechanical driving parts. In all embodiments, regardless of drive system, some or all of the lower connecting mechanisms  114  may also capable of moving independently from one another, accordingly providing great degree of movement of the second base element  104  with respect to the first base element  102 . As with the upper connecting mechanisms  112 , however, one or more may be fixedly connected to the lower base element  104 . 
     The orthopedic fixation system  100  constructed in accordance with the disclosed principles is used to position a displaced bone or other bone-related use as described above. When used to position a displaced bone or similar task, the first base element  102  and the second base element  104  are separated some distance by the struts  106 . Depending on the therapy proposed, the struts  106  are adjusted using a combination of moving the struts  106  and either the upper attachment mechanism(s)  18 /upper connecting mechanism(s)  112 , or the lower attachment mechanism(s)  110 /lower connecting mechanism(s)  114  or any combination of these components. Notably, not all of the struts  106  necessarily need adjustment, either along the track(s)  118  or along their lengths, if adjustable length struts  106  are employed. The upper attachment mechanism(s)  18  and lower attachment mechanism(s)  110  mounted with at least two degrees of movement allow for six degrees of freedom when combined with the sliding/movement of the upper connecting mechanism(s)  112  and lower connecting mechanism(s)  114  with respect to the first and second base elements  102 ,  104 . 
     If a pair of struts  106  are configured in a cross arrangement (as shown in both  FIG. 1  and  FIG. 2 ), the vertical height can be increased by drawing one or more of the upper connecting mechanisms  112  of the struts  106  together (or the lower connecting mechanisms  114 , or both). To bring such components together, one or more of the upper and/or lower connecting mechanism(s)  112 / 114  are loosened/unlocked from their respective base element  102 ,  104 , and then slid/moved along their respective track  118  to the desired position(s). The mechanism(s) can then be locked in their new position(s). As mentioned above, the sliding/moving of one or more of these mechanisms  112 / 114  may be accomplished by a drive system, however, such a system is not required. Similarly, when a pair of struts  106  are configured in the illustrated crossing arrangement, the vertical height can be decreased by pushing apart the upper connecting mechanisms  112  of the struts  106  (or the lower connecting mechanisms  114 , or both). Again, this can be accomplished by unlocking or otherwise loosening the mechanisms  112 / 114  from their respective base elements  102 / 104 , and sliding/moving the mechanism(s)  112 / 114  along their respective track(s), and then locking the one or more repositioned mechanism(s)  112 / 114  in their new position(s). Changing the positions of the upper connecting mechanisms  112  and/or the lower connecting mechanisms  114  along with the ability of the upper attachment mechanisms  108  and the lower attachment mechanisms to provide at least two degrees of movement  110  provides flexibility to the positioning of the first base element  102  and the second base element  104  with respect to one another. 
     Turning now to  FIG. 2 , illustrated is an alternate embodiment of an orthopedic fixation system  200  constructed in accordance with the disclosed principles. This embodiment of the disclosed fixation system  200  has variations from the orthopedic fixation system  100  illustrated in  FIG. 1 . That being said, designator numbers and their accompanying descriptions for parts that are the same or similar between the two embodiments will be the same as detailed in the description of  FIG. 1 , and thus those descriptions will not be detailed again with reference to  FIG. 2 . 
     One of the distinctions between the two embodiments is the that the alternate embodiment of  FIG. 2  includes a first base element  202  and a second base element  204  that has a hexagonal ring with a circular aperture therethrough. The first base element  202  includes a single track  118 , and the second base element  204  includes just a single track  118  as well. By providing the first and second base elements  202 ,  204  with a hexagonal shape, use of this embodiment of the fixator device  200  can be simplified since the sliding movement of each of the upper and lower connecting mechanisms  212 ,  214  is limited to one of the “sides” of the hexagonal shape of the base elements  202 ,  204 . Moreover, because the sliding movement of the upper and lower connecting mechanisms  212 ,  214  along their respective base elements is linear rather than the circular movement seen in the embodiment of FIGURE  1 , the manufacture of the raised portions or grooves of the connecting mechanisms  212 ,  214  and their corresponding track  218  grooves or raised portions may be simplified since all of the manufactured surfaces may be rectilinear. When compared with machining or grinding precision surfaces have mating curved portions, the use of rectilinear mating surfaces can substantially decrease manufacturing costs for the ring elements  202 ,  204  and thus the overall fixator device  200 . Of course, in embodiments where the connecting mechanisms  212 ,  214  do not actually slide on the tracks  218 , and instead roll for example on gears, the same precision may be present for such curved mating components. 
     Another difference between the embodiments of  FIG. 1  and  FIG. 2  is that the base elements  202 ,  204  of the fixator device  200  in  FIG. 2  includes large number of apertures  216  formed through the base elements  202 ,  204 . The apertures  216  in this embodiment may again be sized, shaped and spaced apart for securing transfixation screws, wires or pins, etc., to be secured thereto with typical fixator clamps or the like, as will be apparent to those skilled in the art for securing the first and second base elements  202 ,  204  to a patient&#39;s bone. In addition, the large number of apertures  216  in this embodiment provides numerous places for the affixing of additional struts or other support components designed to help hold the relative positions of the first and second base elements  202 ,  204 . 
     Yet another difference between the embodiments of  FIG. 1  and  FIG. 2  is that the struts  206  used in the fixator  200  of  FIG. 2  each have a bowed configuration along their lengths. More specifically, each strut  206  in a pair of struts  206  is bowed opposite to the other strut  206  in that pair. Therefore, as illustrated, when a single track  118  is used on each base element  202 ,  204 , the pairs of struts  206  are bowed with respect to each other to prevent the struts  206  in a given pair from contacting each other. In embodiments such as that illustrated in  FIG. 1 , two tracks along one or both ring elements  202 ,  204  may be used to help prevent pairs of struts  106  from contacting each other when being positioned. That same goal may be accomplished when only a single track  218  is used for one or both ring elements  202 ,  204 , such as the embodiment in  FIG. 2 . This approach simplifies the design and construction of the base elements  202 ,  204  since only one track  218  needs to be formed in the base element(s)  202 ,  204 . 
     Moreover, this embodiment may be advantageous since the upper connecting mechanisms  212  for all of the struts  206 , or all of the lower connecting elements  214  for the struts  206 , may be manufactured the same since they share the same track. This allows the upper components of the struts  206  to be interchangeable with other upper strut components. Even further, if the track  218  in both the first and second base elements  202 ,  204  are manufactured the same, then all of the upper and lower connecting mechanisms  212 ,  214  may be manufactured the same. This would allow entire struts  206  to be interchangeable, including interchanging upper and lower connecting mechanisms  212 ,  214 , thus further accentuating interchangeability of components for the fixator device  200 , as well as simplifying the manufacturing process to a single strut  206  with a single upper or lower connecting mechanism  212 ,  214 . 
     Yet another embodiment of an orthopedic fixation system constructed according to the disclosed principles is shown in  FIGS. 4 and 4A .  FIG. 4  provides a perspective view of this alternative embodiment, while  FIG. 4A  provides a side view of the fixation system of  FIG. 4 . Looking at these figures together, the orthopedic fixator device or system in this embodiment is identified by the numeral  400 . 
     The fixation system  400  again includes a first base element  402  and a second base element  404 . As with other embodiments, the first and second base elements  402 ,  404  also include a plurality of apertures  416  therethrough, which can be sized, shaped and spaced apart for securing transfixation screws, other fixator frames/rings, wires or pins, etc., to be secured thereto with typical fixator clamps or the like. The first base element  402  and the second base element  404  are also again spaced apart by a plurality of struts  406   a - 406   f . Although six struts  406  of substantially equal length are illustrated, the device is not limited to specifically six struts  406 , nor is there any limitation to the use of all equal length struts  406 . The base elements  402 ,  404  in this embodiment are provided as enclosed rings with a substantially circular shape. Of course as with other embodiments, either or both of the base elements  402 ,  404  may comprise only partially enclosed fixator elements, such as only a partial circular structure or an angular frame, or even simply a linear structure or a frame with both linear and curved portions. Also in this embodiment, six struts  406  are again illustrated. These struts  406  are shown substantially identical to one another in both length and shape. As before, however, in other configurations there may be a fewer or a greater number of struts  406 . In addition, some or all of the struts  406  may comprise a solid rod having a fixed length or may be adjustable along their lengths. 
     Struts  406  again include an upper attachment mechanism  408   a - 408   f  and a lower attachment mechanism  410   a - 410   f . Also as before, the upper and lower attachment mechanisms  408 ,  410  provide for at least two degrees of movement. The upper and lower attachment mechanisms  408 ,  410  may be any mechanism capable of allowing a variable range of motion between a strut  406  and a base element  402 ,  404 . In the illustrated embodiment, the upper and lower attachment mechanisms  408 ,  410  are provided as passive ball-and-socket joints. However, some of the attachment mechanisms  408 ,  410  may be different from others. 
     Each upper attachment mechanism  408  is mounted to an upper connecting mechanism  412   a - 412   f , and each lower attachment mechanism  410  is mounted to a lower connecting mechanism  414   a - 414   f . The upper connecting mechanisms  412  are slidably mounted on the first base element  402 , and the lower connecting mechanism  414  are slidably mounted on the second base element  404 , using carriages that permits sliding of the mechanisms  412 ,  414  around the rings  402 ,  404 , but not for the mechanisms  412 ,  414  to be removed from the rings  402 ,  404  when pressure is applied using the struts  406 . In some embodiments, less than all of the connecting members  412 ,  414  are moveably connected to the base elements  402 ,  404 , and are instead fixedly connected thereto. Accordingly, the movements of the struts  406  described herein may be made to all of the strut  406  ends, or only to some of them. 
     The first and second base elements  402 ,  404  also include a single track  418  each for use with the sliding mechanisms  412 . The tracks  418  allow for circumferential movement of the connecting mechanisms  412 ,  414  around the base elements  402 . While the tracks  418  are illustrated with a specific groove structure, the tracks  418  may be comprised of any mechanism which allows for the connection and the movement of the connecting mechanisms  412 ,  414  around the base elements  402 ,  404 . 
     In addition, in this embodiment, the fixator system  400  includes a drive system, which includes a drive motor  422 . Such a drive system may be employed with a fixator device  400  according to the disclosed principles to gradually and controllably re-orient the base elements  402 ,  404 . More specifically, one or more of the connecting mechanisms  412 ,  414  can be translated along the tracks  418  to a desired position. To accomplish this in the illustrated embodiment, the tracks  418  include teeth  420  configured to engage one or more gears  424   a - 424   f  associated with the connecting mechanisms  412   a - 412   f ,  414   a - 414   f  a the ends of the struts  406   a - 406 - f . The carriages comprising the connecting mechanisms  412 ,  414  include one or more gears  424  therein configured to engage the teeth  420  located on or within the tracks  418 . The carriages  412 ,  414  could comprise one or more points through which the drive motor  422  and its drive gear  422   a  engage and turn the gears in the carriages  412 ,  414  in order to move the carriages  412 ,  414  along the tracks  418 . This allows the moveable ones of the connecting mechanisms  412 ,  414  to move independently from one another. Of course, as discussed above,  FIG. 4  provides only an exemplary embodiment of a drive system in accordance with the disclosed principles, and other types of drive system and related techniques for drive the positions of the struts  406  are also within the broad scope of the present disclosure. Also, although the drive system for the two base elements  402 ,  404  in  FIG. 4  are the same, the base elements  402 ,  404  may include different drive systems. 
     The drive system could also include a locking mechanism that would hold the connecting mechanisms  412 ,  414  in a static position until intentionally moved to reposition the struts  406  and thus re-orient the base elements  402 ,  404  with respect to one another. For example, the gear in the carriages  412 ,  414  could be planetary or otherwise configured such that the gears  424  configured to engage the teeth  420  would not move along the teeth  420  unless driven by a carriage drive gear  426   a - 426   f . Alternatively, the drive system may include one or more non-moving gears on the carriage  412 ,  414  configured to engage the teeth  420  on the tracks  418  for locking, and disengage the teeth  420  for unlocking, the movement of the carriages  412 ,  414 . As mentioned above, a simple screw (e.g., a thumb screw, set screw, or the like) passing through the carriages  412 ,  14  and contacting the tracks  418  may provide the locking mechanism. 
     All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims. 
     Moreover, while various embodiments of the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the invention(s) should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with any claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages. 
     Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, although the headings refer to a “Technical Field,” such claims should not be limited by the language chosen under this heading to describe the so-called technical field. Further, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.