Abstract:
Described is a linkage for coupling an external fixtaor to a brace supporting an appendage. The linkage comprises, a pair of mounting members, a pair of first elongate members, a pair of position fixing members, a second pair of elongate members and a pair of quick release mechanisms. The mounting members are selectively coupleable to the external fixator. Each of the first elongate members is rotatably coupled to a corresponding one of the mounting members. Each of the position fixing members includes first and second locking channels for slidably receiving a corresponding one of the first elongate members in the first locking channel. Each of the second elongate members is slidably received in a corresponding one of the second locking channels. The quick release mechanisms couple the pair of the first elongate members to the pair of mounting members.

Description:
BACKGROUND 
       [0001]    Circular fixation allows precise and dependable correction of limb fracture and deformity (e.g., limb length discrepancy). However, circular fixation also carries a number of risks, most notably joint stiffness and muscular contracture, which may continue even with physical therapy. Correction of muscular contracture may be difficult, if not impossible, without further surgery (e.g., joint mobilization, tendon lengthening). Braces have been developed which allow for controlled motion of a joint adjacent to a limb that is circularly fixated to prevent joint stiffness and muscular contracture. These braces used screwed-on linkages to circular fixators to enhance stability around the joint and restrict motion that may inhibit the healing process. 
       SUMMARY OF THE INVENTION 
       [0002]    The present invention relates to a linkage for coupling an external fixtaor to a brace supporting an appendage. The linkage comprises, a pair of mounting members, a pair of first elongate members, a pair of position fixing members, a second pair of elongate members and a pair of quick release mechanisms. The mounting members are selectively coupleable to the external fixator. Each of the first elongate members is rotatably coupled to a corresponding one of the mounting members. Each of the position fixing members includes first and second locking channels for slidably receiving a corresponding one of the first elongate members in the first locking channel. Each of the second elongate members is slidably received in a corresponding one of the second locking channels. The quick release mechanisms couple the pair of the first elongate members to the pair of mounting members. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  shows an exemplary embodiment of a limb brace system according to the present invention. 
           [0004]      FIG. 2  shows an exemplary embodiment of a frame-brace coupling device according to the present invention. 
           [0005]      FIG. 3  shows an exemplary embodiment of a linkage for a frame-brace coupling device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0006]    The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are provided with the same reference numerals. The present invention relates to an external fixator linkage. The exemplary embodiments of the present invention describe a frame-to-brace linkage/coupling device which may detachably couple a circulator fixator of a spatial frame to a limb brace. As will be described further below, uses of the coupling device may allow the brace to be removed for physical therapy, washing the patient, repairing/replacing/cleaning the brace, etc. The coupling device also allows the limb brace to be properly aligned and fitted to the patient and may provide a therapeutic effect to alleviate/prevent muscular contracture, joint stiffness and any other negative effects associated with circular fixation. 
         [0007]      FIG. 1  shows an exemplary embodiment of a limb brace system  5  according to the present invention. The limb brace system  5  may generally comprise an external fixator (e.g., a spatial frame  10 ) mounted on a limb and a coupling device  12  connecting the spatial frame  10  to a brace  15  via a joint  20 . The spatial frame  10  may be a Taylor Spatial Frame or Ilizarov-Taylor Spatial Frame which comprises a proximal circular fixator  25  and a distal circular fixator  30  coupled together via a plurality of struts  35 . As is known in the art, the spatial frame  10  may be secured to the limb using, for example, pins, screws, rods, wires, etc. to prevent rotational and/or translational movement of the spatial frame  10  relative to the limb. 
         [0008]    The spatial frame  10  may be used to support a fractured limb and/or correct a deformity (e.g., limb length discrepancy) through the concept of callotasis. In the latter instance, a surgical fracture may be created in a long bone in the limb. The bone is allowed to commence healing but is distracted using the spatial frame  10  to regenerate new bone for correcting the deformity, e.g., lengthening the bone. The spatial frame  10  may also be used for a bone transport. In this case, a defect in a long bone may be treated by removing a segment of bone while simultaneously lengthening the bone to replace the removed segment and produce a single bony unit. Regardless of the reason for use, the spatial frame  10  may be mounted over any long bone, e.g., femur, tibia, humerus, ulna. 
         [0009]    As shown in  FIG. 1 , the brace  15  may be a boot worn on the foot when the spatial frame  10  is mounted on the lower leg. However, a structure of the brace  15  may be determined based on the body part on which it will be worn. For example, when the brace  15  to be attached to the lower leg (e.g., the spatial frame  10  is mounted on the upper leg), the brace  15  may be a wrap, a circular band, a cuff, a shell, etc. When the attached to the hand (e.g., the spatial frame  10  is mounted on the lower arm), the brace  15  may also be a glove. 
         [0010]    The joint  20  allows the brace  15  to move relative to the spatial frame  10 . For example, the joint may comprise  20  a pair of hinges  40  which have distal arms  45  coupled to the brace and proximal arms  50  coupled to the coupling device  12  (coupled to the spatial frame  10 ). Thus, in the exemplary embodiment shown in  FIG. 1 , the joint  20  may function substantially similar to an ankle joint allowing extension/flexion of the foot about the joint  20 . This embodiment may be similarly implemented over a knee joint. For example, the spatial frame  10  may be mounted on the upper leg (over the femur) and the brace  15  may be worn on the lower leg. The joint  20  may then function substantially similar to a knee joint, allowing extension/flexion of the lower leg about the joint  20 . The system  5  may also be implemented on limbs of the upper body. While the joint  20  is shown as a hinge joint only allowing movement in one plane, those of skill in the art that a rotational or sliding joint may be utilized to simulate other body joints and/or other degrees of movement. 
         [0011]    In the exemplary embodiment, the hinges  40  of the joint  20  may be configured for operation in a static mode or a dynamic mode. In the static mode, an angle between the proximal arms  45  and the distal arms  50  may be fixed to create a preselected angle between the brace  15  and the spatial frame  10 . That is, after a surgical procedure, the brace  15  may be set in a predetermined position creating an initial angle between the spatial frame  10  and the brace  15 . Increasing the initial angle to the preselected angle may stretch muscles in the lower leg and foot, alleviating/preventing joint stiffness and muscular contracture. 
         [0012]    In the dynamic mode, a continuous pressure may be applied in a predetermined direction to which the patient may apply resistance. For example, if the hinges  40  are configured to apply pressure to cause extension of the foot, the patient may resist the pressure by attempting to flex the foot. The pressure applied by the hinges  40  may be variable, allowing the patient to gradually rebuild and then maintain muscle tone while wearing the spatial frame  10 . 
         [0013]    Those of skill in the art will understand that various mechanisms may be utilized to implement a dual mode joint as described above. For example, a gearing mechanism having a ratchet may be used to implement the static mode. As the angle between the spatial frame  10  and the brace  15  increases, the ratchet may interlock with a gear to maintain the angle (i.e., resist muscle contracture pulling the brace  15  back to the initial angle). The dynamic mode may be implemented by spring-loading the gearing mechanism and/or adding resistance bands thereto. 
         [0014]      FIG. 2  shows an exemplary embodiment of the coupling device  12  according to the present invention. As noted above, the coupling device  12  may be coupled to the spatial frame  10  and the joint  20 . The coupling device  12  allows the joint  20  and the brace  15  to be removed from the patient, enabling the brace  15  to be cleaned, the area previously covered by the joint  20  and the brace  15  to be washed, a physical therapist to easily remove the joint  20  and brace  15 , etc. The coupling device  12  also allows a distance between the spatial frame  10  and the joint  20  to be varied for properly aligning the joint  20  with the bodily joint (e.g., ankle, knee, etc.). 
         [0015]    The coupling device  12  may include a circular fixator  200  which may be substantially similar to the distal circular fixator  30  on the spatial frame  10 . In the exemplary embodiment, the circular fixator  200  is coupled to the distal circular fixator  30  by, for example, mechanical means (e.g., bolts, screws, pins, latches, etc.). 
         [0016]    Extending from the circular fixator  200  is a pair of linkages  205 . The linkages  205  may be disposed on a circumference of the circular fixator  200  so that they are separated by a distance which corresponds to a distance separating the proximal arms  50  of the joint  20 . The linkages  205  may be used to detachably couple the spatial frame  10  to the joint  20 . While the exemplary embodiment describes the linkages  205  as attached to the circular fixator  200 , those of skill in the art will understand that the linkages  205  may be attached directly to the distal circular fixator  50  of the spatial frame. 
         [0017]    In the exemplary embodiment, the linkages  205  include mounting members (e.g., L-brackets  210 ) that are coupled to the circular fixator  200 . Although the L-brackets  210  are shown in  FIG. 2  as mechanically coupled to the circular fixator  200  via a mechanical means (e.g., a bolt, a pin, etc.), those of skill in the art will understand that the L-brackets may be electrically or chemically affixed to the circular fixator  200 , and that this coupling may be temporary or permanent. 
         [0018]    Holes are provided in the L-brackets  210  for receiving quick release mechanisms (e.g., pins  215 ). In the exemplary embodiment, the pins  215  are removably coupled to the L-brackets  210 . For example, each of the pins  215  may comprise a cylindrical portion having a catch which, when the catch is in a retracted position, the cylindrical portion may be passed through the hole. After the cylindrical portion has been passed through the hole, the catch may be released into an expanded position, preventing the cylindrical portion from retreating back through the hole. Control of the catch may be affected using, for example, a button on a face of the pin  215 , e.g., depressing the button for the retracted position and releasing the button for the expanded position. 
         [0019]    The pins  215  may be used to couple first elongate members  220  to the L-brackets  210 . When coupled to the L-brackets  210 , the first elongate members  220  may be statically disposed and/or rotatable relative to the L-brackets  210 . For example, the first elongate members  220  may be statically disposed after a surgical procedure to ensure that the surgical site heals properly, but a rotational aspect may be gradually introduced to prevent muscular contracture and joint stiffness. The rotational aspect may also be useful for properly aligning the joint  20  with the bodily joint, as explained further below. 
         [0020]    The first elongate members  220  may be coupled to second elongate members  225  via position fixing members (e.g., locking mechanisms  230 ). As shown more clearly in  FIG. 3 , the locking mechanism  230  may be implemented as, for example, a sliding block which includes a first channel receiving the first elongate member  220  and a second channel receiving the second elongate member  225 . In the exemplary embodiment, the first and second channels may be disposed at a predetermined angle (e.g., substantially perpendicular) relative to each other. A first lock may be disposed on the first channel to lock the first elongate member  220  in a position relative to the block, and a second lock may be disposed on the second channel to lock the second elongate member  225  in a position relative to the block. After the circular fixator  200  of the coupling device  12  is affixed to the distal circular fixator  30  of the spatial frame  10 , the first and second elongate members  220 ,  225  may be moved relative to each other to align the joint  20  with the corresponding bodily joint. The first and second elongate members  220 ,  225  may include stops to prevent disassociation with the sliding block. When the joint  20  has been properly aligned, the first and second locks (e.g., locking screws) may statically position the first and second elongate members  220 ,  225  relative to each other, maintaining the joint  20  in its proper alignment (e.g., over the ankle, knee, elbow, etc.). Those of skill in the art will understand that various embodiments of the locking mechanism  230  may be utilized to allow the joint  20  to be properly aligned with the bodily joint. 
         [0021]    The second elongate member  225  may be coupled to the proximal arm  50  of the joint  20 . The coupling may be affected via mechanical means (e.g., a bolt, screw, etc.) so that the coupling device  12  can be secured to the joint  20 . 
         [0022]    In an exemplary use of the system  5 , the spatial frame  10  may be mounted on the patient following a surgical procedure. For example, after lengthening a bone(s) in the lower leg, the spatial frame  10  may be mounted over the lower leg as is conventionally known in the art. The circular fixator  200  of the coupling device  12  may then be affixed to the distal circular fixator  30  of the spatial frame  10 . The brace  15  and the joint  20  may then be mounted on the patient. The second elongate members  225  may then be coupled to the proximal arms  50  of the joint  20 , and the joint  20  may be aligned with the ankle joint by positioning the first and second elongate members  220 ,  225  relative to each other. When the joint  20  has been properly aligned, the first and second elongate members  220 ,  225  may be locked in their respective positions using the locking mechanism  230 . 
         [0023]    After the system  5  has been fully mounted on the lower leg and foot, the patient or medical personnel may configure the system  5  for therapeutic operation. As described above, the joints  20  may be configured for the static mode or the dynamic mode to reduce the effects of joint stiffness and muscular contracture. In the static mode, the angle between the spatial frame  10  and the brace  15  may be set to a predetermined value, allowing the muscles, tendons and ligaments of the lower leg to be stretched. In the dynamic mode, the joint  20  may be configured to apply pressure in a predetermined direction (plane, angle, etc.), forcing the brace  15  to extend or flex. In this mode, the patient may resist the pressure strengthen/tone the muscles of the lower leg and foot. 
         [0024]    The exemplary embodiments of the present invention allow the patient or medical personnel to remove the brace  15  and the joint  20 . For example, when the patient is going to wash, during physical therapy, or when the brace  15  and/or joint  20  needs to be cleaned, repaired, etc., the pins  215  may be removed from the L-brackets  210  on the circular fixator  200 . When the pins  215  are removed, the first elongate members  220  are released and the joint  20  and the brace  15  may be removed. Alternatively, the first and/or second locks may be released, allowing the sliding blocks to be removed from the first and/or second elongates members  220 ,  225 , respectively. If the sliding blocks are removed from the first and/or second members, preferably a marking device (e.g., pen, marker, scratch, etc.) is used to mark a position of the first and/or second elongate members  220 ,  225  relative to sliding blocks. 
         [0025]    The present invention has been described with the reference to the above exemplary embodiments. Accordingly, various modifications and changes may be made to the embodiments without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings, accordingly, should be regarded in an illustrative rather than restrictive sense.