Abstract:
A device for treating fractures of a bone comprises a plurality of arms, each extending from a proximal end to a distal end and movable in a three-dimensional space, the proximal end of each arm coupled to a frame and a plurality of couplings, each of the couplings coupled to a distal end of each of the plurality of arms, the coupling lockingly receiving a bone fixation element secured to a corresponding bone fragment such that each of the arms is coupled to a corresponding fragment of the bone in combination with a mechanical unit moving each of the arms relative to the frame and a controller receiving data corresponding to a desired final position of the fragments relative to one another and controlling the mechanical unit to move the arms relative to one another to achieve the desired final position of the bone fragments relative to one another.

Description:
PRIORITY CLAIM 
     The present application claims priority to U.S. Provisional Application Ser. No. 61/181,505 filed on May 27, 2009 entitled “Robotic Arms,” the entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to devices for treating fractures and, in particular, relates to a device for reducing and/or holding fractured portions of the bone. 
     BACKGROUND 
     Fractures of bones may be difficult to treat due to displacement of fractured portions of the bone. Bone have attachments to muscles, tendons and ligaments, which tend to displace and angulate the bone, causing the fractured portions to move out of place. Thus, fractured portions must be realigned to achieve reduction. Realignment may require traction and correction of displacements and angulations via an application of force. For example, a surgeon or other medical professional may physically pull a patients foot or leg to distract the bone. Once proper reduction is obtained, the fractured portions of the bone must be held in position until fixation is applied to prevent re-displacement. However, the necessary force and the direction of the application required to correct displacements of the bone may be difficult to attain and maintain. Current methods do not allow the force, direction and the speed of the process to be gauged or controlled. 
     SUMMARY OF THE INVENTION 
     The present invention, directed to a device for treating fractures of a bone, comprises a plurality of arms, each extending from a proximal end to a distal end and movable in a three-dimensional space, the proximal end of each arm being coupled to a frame and a plurality of couplings, each of the couplings being coupled to a distal end of each of the plurality of arms, the coupling lockingly receiving a bone fixation element secured to a corresponding bone fragment such that each of the arms is coupled to a corresponding fragment of the bone in combination with a mechanical unit supplying motion to each of the arms relative to the frame and a controller receiving data corresponding to a position of the bone fragments relative to one another and controlling the motion to move the arms relative to one another to achieve the desired final position of the bone fragments relative to one another. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic view of a system according to an exemplary embodiment of the present invention; 
         FIG. 2  shows a perspective view of a robotic device of the system of  FIG. 1 ; 
         FIG. 3  shows a perspective view of a wrist portion of the robotic device of  FIG. 1 , in a first configuration; 
         FIG. 4  shows a perspective view of the wrist portion of  FIG. 3 , in a second configuration; 
         FIG. 5  shows an enlarged perspective view of a distal end of the wrist portion of  FIG. 3 ; 
         FIG. 6  shows a cylinder assembly of the wrist portion of  FIG. 3 ; 
         FIG. 7  shows a schematic diagram of a hydraulic unit of the system of  FIG. 1 ; 
         FIG. 8  shows a schematic diagram of an alternate embodiment of the hydraulic unit of  FIG. 7 ; 
         FIG. 9  shows a perspective view of the robotic device of  FIG. 2  in which connectors are coupled to bone fragments; 
         FIG. 10  shows a perspective view of the robotic device of  FIG. 2 , connected to a connector inserted into a fractured portion of a bone; 
         FIG. 11  shows a perspective view of the robotic device of  FIG. 2 , moving fractured portions of the bone to reposition the bone; 
         FIG. 12  shows a perspective view of the robotic device of  FIG. 2 , having repositioned the fractured portions of the bone; and 
         FIG. 13  shows a perspective view of the robotic device of  FIG. 2 , maintaining the repositioned bone fragments for fixation. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention relates to devices for treating fractures and, in particular, relates to a device for reducing and/or holding fractured portions of the bone. Exemplary embodiments of the present invention provide a device including robotic arms that may be connected to the fractured bone to move the bone through all necessary axes to reposition fractured portions of the bone for fixation. 
     As shown in  FIGS. 1-13 , a system  100  according to an exemplary embodiment of the invention comprises a robotic device  102  for moving fractured portions of a bone  120  into a desired spatial relationship to one another. As shown in  FIG. 1 , the robotic device  102  is connectable to a power source  104  controlled via a user interface  106 . The robotic device  102  may further comprise a control module  110  processing input from the user interface  106  to control movement of a plurality of arms  108  via, for example, hydraulic forces provided by a fluid pressurizing/compressing unit such as the hydraulic unit  112 . Alternatively, the arms  108  may be moved by one or more servo motors (not shown) coupled thereto via any known gearing mechanism as would be understood by those skilled in the art. Each of the arms  108  may be connected to a target portion of the fractured bone  120  such that movement of the arms  108  repositions the fractured portions as desired. Each of the arms  108  may be equipped with an encoder  116  capable of precisely determining the position of the arm  108  such that the positions of the fractured portions of bone  120  may be accurately monitored and repositioned as desired. 
     The power source  104  may be any power source available in an operating room. For example, the power source  104  may be any source of electrical power, including a battery power. The power source  104  may be used to power the hydraulic unit  112  to move hydraulic fluid through the robotic device  102 . As would be understood by those skilled in the art, the hydraulic fluid may be any suitably incompressible fluid such as, for example, mineral oil or saline. In another embodiment, the system  100  may use a compressible fluid for a fluid or pneumatic system  100 . Instructions for the movement of the arms  108  may be inputted via the user interface  106  and processed by the control module  110  to control the hydraulic unit  112  in the manner necessary to achieve the desired motion indicated by the user as would be understood by those skilled in the art. The user interface  106  may be a simple switch and/or joystick arrangement for activating the robotic device  102  and directing movement of the arms  108 . In a preferred embodiment, however, the user interface  106  may be a personal computer or other processing arrangement that may be used to input a direction of motion for each of the arms  108  and may also allow a user to specify a speed of movement of one or more of the arms. For example, the user may be able to assign vertex points to portions of the bone  120  and additional target points to which it is desired that the portions of the bone  120  be moved. 
     According to a further embodiment, the system  100  may also include an imaging device  114  for visualizing various fragments of the bone  120  such that the fractured portions are indicated on a screen of the imaging device. The system  100  may be capable of determining a position of each of the bone fragments relative to one another such that a user may input a final desired spatial relationship via the user interface  106 . The position of each of the bone fragments  120  may be determined by the encoders  116  of the arms  108 , which are connected to the bone fragments via the connectors  122 . 
     As shown in  FIG. 2 , the robotic device  102  may be mountable to an operating table  118  such that the arms  108  may be coupled to connectors  122  inserted into fractured portions of a bone  120 . Alternatively, the robotic device  102  may be mounted on a separate table movable to a position alongside the operating table  118 . The arms  108  may be mounted to a side of the table  118  via a longitudinal element  109  such that each of the arms  108  is slidable along the longitudinal element  109  to move longitudinally along the table  118 . The longitudinal element  109  may also be movable relative to the table  118  via, for example, rotation. Although the figures show the robotic device  102  as including two arms  108 , it will be understood by those of skill in the art that the robotic device  102  may include any number of arms  108 . 
     The arms  108  are adapted to be movable through a three-dimensional space in six directions and six angulations to permit any desired positioning of the arms  108  relative to one another. To move in six directions, each of the arms  108  includes a first portion  140  and a second portion  142  rotatably coupled to one another. The first portion  140  extends from a first end  144  to a second end  146  and the second portion  142  extends from a first end  148  to a second end  150 . The second end  146  of the first portion  140  is rotatably coupled to the first end  148  of the second portion  146  via, for example, a pin (not shown), such that the first portion  140  and the second portion  142  are rotatable relative to one another about the pin. It will be understood by those of skill in the art that the rotatable coupling of the first portion  140  and the second portion  142  of the arm  108  may function similarly to a human elbow. Additionally, the second end  150  of the second portion  144  of each of the arms  108  may be slidably coupled to the longitudinal element  109  such that the second portion  144  is also rotatable relative to the longitudinal element  109 , permitting movement of the arms  108  relative to the table  118 . Thus, it will be understood by those of skill in the art that the arms  108 , along with the longitudinal element  109 , permit movement of the arms  108  in a three-dimensional space to correct six displacements (e.g., anterior-posterior, medial-lateral and shortening-lengthening). 
     The first portion  140  of the arm  108  may further include a wrist portion  152 , which will be understood by those of skill in the art as functioning similarly to a human wrist. As shown in  FIGS. 3-4 , the wrist portion  152  includes a plate  154  supporting and positioning a spindle  189 , which may be engaged to an end effector  136  (shown in  FIGS. 9-13 ) for coupling to the connector  122 . The end effector  136  may be, for example, a collet, chuck or jaws adapted to securely grasp the connectors  122 . The plate  154  is also attached to a plurality of cylinders  164  that control movement of the plate  154  and the end effector  136  to provide a desired angulation of the end effector  136 . The plate  154  may be attached to the cylinders  164  via, for example, a grouping of fibers, a cable or a shaft with a joint assembly. The plate  154  includes a distal surface  156  and a proximal surface  158 , the spindle  189  being coupled to the distal surface  156  while the cylinders  164  are attached to the proximal surface  158 . A shaft  160  providing axial support for the spindle  189  is coupled to the plate  154 . As shown in  FIG. 5 , the shaft  160  may be coupled to the plate  154  via a pivot  162  received through the proximal surface  158  in a corresponding space  164  of the plate  154 . The pivotable coupling allows the plate  154  to be angled and rotated about the pivot  162 , permitting angulatory movement of the spindle  189  and thereby the end effector  136 . In a preferred embodiment, the pivot  162  will be spherical such that the plate  154  may be angled in any desired direction. The cylinders  164  provide hydraulic forces for angling the plate  154  about the pivot  162 , permitting angulations of the end effectors  136  to correct angular deformity in three planes (e.g., medial-lateral angulation, anterior-posterior angulation, internal and external radial angulation). 
     The plate  154  may also include tendon attachment regions  166  for attaching to a fiber tendon  168  of each of the cylinders  164 . The tendon attachment regions  166  may be positioned on the proximal surface  156  about a perimeter of the plate  154 . Fluid movement through each of the cylinders  164  provided by the hydraulic unit  112  translates into a force on each of the tendons  168  attached to the plate  154  such that the force on the tendons  168  moves the plate  154  about the pivot  160 , and therefore the attached spindle  189 , in various angulations. In a preferred embodiment, the wrist portion  152  may include four cylinders  164  and four corresponding tendon attachment regions  166 . However, it will be understood by those of skill in the art that any number of cylinders  164  may be included so long as the number of cylinders  164  is sufficient to provide complete angulation of the plate  154  and the spindle  189  through the desired range of movement. As shown in  FIG. 6 , the tendon  168  may extend from within the cylinder  164  past a distal end  170  of the cylinder  164 . The cylinder may include a piston  172  fluid-sealed via a seal  174 . The piston  170  may be connected to a rod  176  through which the tendon  166  extends. Thus, hydraulic force supplied by the hydraulic unit  112  through the cylinder  164  is provided to the tendon  168  extending therefrom to translate into movement of the plate  154 . Although the cylinders  164  are described as being attached to the plate  154  via fiber tendons  168 , it will be understood by those of skill in the art that the cylinders  164  may be attached to the plate  154  via a variety of attaching elements such as, for example, a cable or a shaft with a joint assembly. 
     In an alternative embodiment, movement of the plate  154  may be provided by a linear movement mechanism comprising gears, belts or a lead screw arrangement. The linear movement mechanism may also be attached to the plate  154  via, for example, fibers, a cable or a shaft with a joint assembly. 
     As shown in  FIG. 7 , the hydraulic unit  112  may supply hydraulic force through the cylinders  164  to tendons  168  to angulate the plate  154  via a motor  178  and a pump  180  that draws fluid from a reservoir  182 . The hydraulic unit  112  further includes a pressure relief valve  184 , a selector valve  186  and a bypass valve  188 . The pump  180  draws fluid from the reservoir  182 , which flows to the pressure relief valve  184  as it leaves the pump  180 . The pressurized fluid is then directed either back to the reservoir  182  or on to the selector valve  186 . The pressurized fluid may be directed back to the reservoir  182 , for example, when a predetermined maximum system pressure has been reached. The selector valve  186  may have three settings. In a first setting no fluid is permitted to pass through the selector valve  186 . In a second setting, pressurized fluid passes through the selector valve  186  and into a first one of the cylinders  164   a , while non-pressurized fluid from a second one of the cylinders  164   b  is permitted to return to the reservoir  182 . In a third setting, pressurized fluid is permitted to flow through the selector valve  186  into the second cylinder  164   b  while non-pressurized fluid from the first cylinder  164   a  is permitted to return to the reservoir  182 . 
     The hydraulic unit  112  may also be set such that the robotic device  102  may be operated in a neutral or limp mode, in which the cylinders  164  are manually movable. In the limp mode, the selector valve  186  is moved to the first setting, in which no fluid passes therethrough and the bypass valve  188  is set such that fluid passes freely therethrough. The cylinders  164  and the arms may then be manually moved to desired positions and/or orientations and then locked in the desired position. It will be understood by those of skill in the art that although the hydraulic unit  112  is shown and described with two cylinders  164   a ,  164   b , the hydraulic unit  112  may be adapted such that any number of cylinders  164  may be used to move the plate  154 . 
     In an alternate embodiment, a hydraulic unit  112 ′ may supply hydraulic forces to first and second cylinders  164   a ′,  164   b  to provide angulation of the plate  154  and the arms  108 , as described above in regard to the system  100 . The hydraulic unit  112 ′ may comprise a motor  178 ′ driving a linear actuator  180 ′ to simultaneously move first and second master cylinders  182   a ′,  182   b ′, respectively. Depending on a desired motion, one of the first and second master cylinders  182   a ′,  182   b ′ transfer pressurized fluid to one of the first cylinder  164   a ′ and second cylinder  164   b ′, respectively. Similarly to the hydraulic unit  112 , the hydraulic unit  112 ′ may be configured in a limp mode so that the cylinders  164 , and thereby the arms  108 , may be manually moved, as desired. When operating in the limp mode, a bypass valve  188 ′ is set such that fluid is allowed to pass freely therethrough. 
     As shown in  FIG. 9 , an exemplary method of use of the system  100  includes inserting one or more connectors  122  into each of a plurality of portions of the bone  120  to be repositioned relative to one another. Each of the connectors  122  may be a bone holding device such as, for example, a schanz screw, pin or clamp type device. In an exemplary embodiment, a first end  132   a  of a first connector  122   a  is inserted into a first fractured portion  124  of the bone  120  while a first end  132   b  of a second connector  122   b  is inserted into a second fractured portion  126  of the bone  120 . As can be seen, in this example, the first connector  122   a  has been inserted into a proximal portion  128  of the bone  120  while the second connector  122   b  has been inserted into a distal portion  130  of the bone  120 . Although in this example, two connectors  122  are shown with a single connector  122  in each of the fractured portions of the bone  120 , it will be understood by those of skill in the art that any number of connectors  122  may be employed in the each of the fractured portions of the bone  120  to achieve the desired stabilization of each of the fractured portions. 
     As shown in  FIGS. 10-11 , each of the arms  108  is connectable to the bone  120  via the connectors  120 . For example, a first arm  108   a  is connected to the first connector  122   a  and a second arm  108   b  is connected to the second connector  122   b . It will be understood by those of skill in the art, however, any number of arms  108  may be included to independently maneuver any number of fractured portions of bone relative to one another. As indicated above, each of the arms  108  may include an end effector  136  connectable to a corresponding second end  134  of a connector  122 . The end effectors  136  of the arms  108  may include, for example, jaws or a grasper adapted to securely grasp the second ends  134  of the connectors  122 . Alternatively, the end effectors  136  may be a protrusions or other elements configured to securely mate with the second ends  134  of the connectors  122 . 
     To connect the end effectors  136  to the second ends  134  of the connectors  122 , the robotic device  102  may be placed in the limp mode allowing each of the arms  108  to be manually moved to a position in it is connectable to a corresponding one of the connectors  122 . It will be understood by those of skill in the art that the limp mode may be initiated via the user interface  106 . Once the end effectors  136  have been connected to each of the connectors  122 , the robotic device  102  may be switched to a locked mode in which the arms  108  are locked along all axes of movement. The encoders  116  on each of the arms  108  then supply information to the system to determine the exact position and location of each of the arms  108 . This information is then used to direct movement of the arms  108  and, consequently the connectors  122  and attached portions of bone, to achieve the desired final spatial relations between the various portions of bone. Once in the locked mode, the user directs motion of the arms  108  via the user interface  106 . 
     The user may direct motion of the arms  108  via the user interface  106  by, for example, selecting one or more of the arms and manipulating one or more joysticks or other controllers in desired directions to cause corresponding movement of the arms  108 . If need be, this process may be repeated for others of the arms  108  until the desired spatial relations among the portions of bone have been achieved. As described above, the arms  108  may be moved in six linear directions and angulations via movement of the rotatable first and second portions  140 ,  142  and the wrist portion  152  of the arm  108 . If the user interface  106  includes a personal computer, points on the fractured portions  124 ,  126  of the bone may be identified as vertices, which may be moved by assigning target positions to these points, as would be understood by those skilled in the art. In a preferred embodiment, the points identified as vertices may be those points on the fractured portions  124 ,  126  at the proximal and distal ends  128 ,  130 , respectively, to which the arms  108  are connected. It will be understood by those of skill in the art that each of the arms  108  may be moved independently of the others to achieve the desired spatial relationship between the fragments of the bone  120 . Alternatively, as will also be understood by those of skill in the art, any grouping of the arms  108  may be moved simultaneously to maintain a desired spatial relationship between any or all of the bone fragments during the movement to the desired spatial relationship. The user may continue to input instructions corresponding to a desired placement of the arms  108  and, consequently, of the bone fragments, via the user interface  106 , until all of the portions of the bone  120  have been repositioned, as desired. 
     Generally, the repositioning will end when the fractured portions  124 ,  126  of the bone  120  have been realigned resembling as closely as possible their alignment before the fracture, as shown in  FIG. 12 . However, the system  100  may be used to maintain any alignment of the bone  120  desired for proper fixation. For example, as shown in  FIG. 13 , the robotic device  102  may rotate the bone  120  relative to the operating table  118  to a position designed to facilitate insertion of a fixation device, such as an intramedullary nail. The arms  108  may rotate the bone  120  via rotation of the longitudinal element  109 , to which the arms  108  are coupled, relative to the table  118 . 
     In an alternative embodiment, at least one of the arms  108  may be connected to a connector/connectors that holds a carriage that cradles a proximal or terminal portion of a limb of the fractured bone  120 . The limb may be attached to the carriage through bone connectors or simply rested on the carriage with an appropriate bolster. The carriage facilitates a placement of the bone  120  in a desired spatial position such that the bone  120  may be reduced or positioned for the introduction of the fixation device. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided that they come within the scope of the appended claims and their equivalents.