Abstract:
A fracture reduction device comprises linear adjustment means for linearly reducing a fractured bone in three directions, and angular adjustment mechanism for angularly reducing a fractured bone about three independent axes. The adjustment mechanism is such that adjustment in each direction and about each axis is independent of the others. The device also allows stable incremental adjustments to be made to the bone position and/or orientation.

Description:
FIELD OF THE INVENTION 
     The present invention relates to fracture reduction devices. 
     BACKGROUND OF THE INVENTION 
     A variety of techniques are known for holding together the parts of a fractured bone while healing takes place. One such technique is external fixation, in which pins are inserted into the bone on each side of the fracture point, and which are then connected to a frame by adjustable clamps. The clamps can then be tightened to hold the parts of the bone fixed with respect to each other. 
     However, before such fixation can take place, the fracture must be reduced so that the bone fragments are in the correct positions for fixation and healing. 
     Previously considered reduction devices allow such reduction to be controlled, but are inconvenient since it is not simple to control a single degree of freedom of movement independently of the other degrees of freedom. 
     It is desirable to provide a fracture reduction apparatus in which controlled vector separation can be easily and simply achieved. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a fracture reduction device comprising linear adjustment means and angular adjustment means for reducing a fractured bone, the adjustment means allowing stable incremental adjustments to be made to the bone position and/or orientation, the adjustment means comprising: 
     a substantially rigid support structure; 
     first and second loading supports attached to the support structure for attachment to first and second portions of a fractured limb about a fracture site, the loading supports being arranged such that the limb can be subjected to a longitudinal distractive force by means of the loading supports; and 
     first and second bone supports for supporting first and second portions of a fractured bone about the fracture site; 
     one of the first and second loading supports being rotatable with respect to the other loading support about two mutually perpendicular axes; 
     at least one of the first and second bone supports being movable in two linear directions perpendicular to one another and to the longitudinal direction of the bone; and 
     wherein adjustment of the positions of the loading and bone supports allows stable incremental adjustments to be made to the bone position and/or orientation. 
     The provision of adjustment means which allow incremental adjustment to be made enables a fractured bone to undergo gradual vector separation in order to improve the healing process. Such incremental adjusters are preferably screw-threaded, but could be provided by some suitable alternative. 
     Once reduction is complete, a bone fixator may be fitted and the reduction device removed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: 
     FIG. 1 shows a schematic view of an embodiment of the present invention, applied to a fractured leg; 
     FIG. 2 shows an enlarged view of part of the embodiment of FIG. 1; 
     FIG. 3 shows an enlarged view of another part of the FIG. 1 embodiment; 
     FIG. 4 shows an enlarged view of yet another part of the FIG. 1 embodiment; and 
     FIG. 5 shows an enlarged view of a further part of a FIG. 1 embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a schematic diagram of an embodiment of the present invention applied to a fractured leg bone  1  having a fracture site  11  and proximal and distal bone fragments  10  and  12 . The device  200  is attached to a patient using two rods  227  and  243 . The first (proximal) rod  227  passes through the leg at or about the knee and the second (distal)  243  passes through the leg at or around the ankle. These rods allow a tensile force to be applied to the broken bone  10 . 
     Two bone pins  14  and  15  are attached close to the fracture site  11 , the bone pins are generally uni-cortical, and the reduction device  200  is attached to the bone pins. The use of uni-cortical bone pins, which may be inserted using normal clinical methods, allows later use of conventional intra-medullary nailing. 
     An initial distractive (longitudinal) force can be applied directly using the device  200  of FIG.  1 . The reduction process can then take place before the bone is fixed using a fixation device. 
     The device  200  comprises two support tubes  225  which extend parallel to the leg bone  1  and which extend from a proximal end fixing arrangement  220  to a distal end fixing arrangement  230 . The proximal end fixing arrangement  220  comprises a substantially C-shaped bracket  221  having clamp regions  223  to which the support tubes  225  are rigidly attached. The proximal end rod  227  is held in slots  228  in the bracket  221 . The side support tubes extend to a distal end bracket  223  and are rigidly clamped thereto by clamps  234 . 
     A mounting plate  231  is slidably mounted on the tubes  225  and carries a distal end attachment  240 , which will be described in more detail below. The attachment  240  holds the distal end support rod  243  which passes through the distal end of the bone. 
     Bone pin brackets  201  are slidably engaged on one of the support tubes  225  as shown in FIG. 1, and will now be described with reference to FIG.  2 . 
     Each bone pin bracket  201  is adjusted for longitudinal position and then clamped to the side tube  225 . Bone pins  14  and  15  are inserted into respective bone fragments  10  and  12  and have their position, and hence the fracture position, controlled by the device  200  via the brackets  201 . Each bracket includes a main bracket body  202  which clamps to the side tube when in use, and which defines a slot  203 . An adjustment block  205  is arranged to engage with the slot  203  and thereby be slidable along the main body  202 . A flange  204  extends from the body  202  and supports an adjustment screw  206 . The adjustment screw  206  engages with the block  205  so that the position of the block can be controlled and adjusted as required by turning of the screw  206 . 
     A plate  208 , which defines a slot  209 , is carried on the block  205  by means of a fixing screw  213 . A flange  210  extends from the plate  208  and is secured thereto by a screw  214 . The flange  210  supports a second adjustment screw  212 , which engages with the block  205 . The plate  208  carries the bone pin  14 ,  15 . 
     Adjustment of the bone pin position is achieved by rotating the adjustment screws  206  and  212 . Rotating screw  206  moves the pin in a vertical direction shown by arrow A (up/down) which is the sagittal direction, and rotating the adjustment screw,  212  moves the pin in a lateral direction shown by arrow B (the coronal translation). 
     The bone pin brackets allow the two directions of adjustment to be adjusted independently of one another and without causing unwanted uncontrolled movement at the fracture site  11 . 
     FIG. 3 shows an enlarged view of the second end fixing system  240 . A mounting plate  231  is slidably engaged with the side support tube  225  and carries a support block  244 . In turn, the support block  244  carries three rollers  246  and  247 . A substantially C-shaped bracket  241  is slidably engaged with these rollers. The bracket  241  carries the distal fixing rod  243  in slots  242 . The rod  243  passes through a distal part of the leg. 
     Sliding the C-shaped bracket  241  through the rollers  246  and  247 , enables the angular displacement of the leg to be adjusted in the coronal plane (i.e. about an axis perpendicular to the longitudinal and lateral/coronal directions). The movement of the bracket  241  can be controlled by frictional engagement with the rollers  246  and  247 , or by a fixing screw (not shown). 
     FIG. 4 shows a cross-sectional view of further details of the distal fixing arrangement  240 . The support block  244  is held on the mounting plate  231  by means of a nut  248  and bolt  249  arrangement. When the nut  248  is slackened, the support block  244  is able to rotate about the longitudinal axis of the device, thereby enabling the angular position of the leg, and the distal bone fragment  12  to be adjusted with respect to the proximal bone fragment  10 . When the required angular displacement is achieved, the nut  248  can be locked thereby fixing the relative positions. 
     FIG. 5 shows a view of the further details of the fixing arrangement  240 . A support plate  233  is rigidly attached to the support bars  225  by means of clamps  234 . This provides a rigid reference point for longitudinal movement of the device. A threaded adjustment screw  235  extends from the sliding support plate and is in threaded engagement with the fixed support plate  234 . A handle  236  is rigidly attached to the free end of the adjustment screw  235 , so that rotation of the handle causes the screw  235  to rotate, thereby adjusting the position of the sliding support plate  231  by virtue of the threaded engagement between the screw and the rigid support plate. 
     The arrangement shown in FIG. 5 allows longitudinal extension (traction) to be applied to the leg by simply turning the screw  235 . Such adjustment is independent of the other position adjustments. 
     It will be appreciated that a device embodying the present invention allows adjustment to be made to the bone fragment positions in each of six degrees of freedom. 
     Furthermore, the embodiment described allows stable incremental adjustments (vector separation) to be made during the reduction process. In contrast, previously-considered reduction devices have required almost complete slackening of adjustment bolts etc. to enable adjustments to be made. 
     The described embodiment of the invention includes adjustment mechanisms which hold their position, even when undergoing adjustment. 
     One advantage of this design is that repeated separation/reduction of the fractured bone can be easily achieved. Simply turning the screw threaded adjusters enables such incremental adjustment. 
     Other major advantages of the above described device embodying the present invention are: 
     Repeatably better anatomical reduction, through the provision of independent adjusters; 
     Repeatably better operating times, up to 50% less than with conventional devices, achieved by virtue of the simple design; 
     Minimal interference at the fracture site. This enables easy access for X-ray or image intensifier equipment, for judging the reduction process, and for easier access for attaching a fixator; and 
     Since there are no bi-cortical pins used in the preferred embodiments, the device is suitable for use with intra-medullary nailing.