Abstract:
A sensing device for determining the location of an intramedullary pin emplaced within the bone of a patient. The sensing device is useable with a frame that initially holds the intramedullary pin external of the patient and the sensing device used to contact a planar portion of the intramedullary pin to verify the orientation of predrilled holes in the intramedullary pin. The same set up is thereafter used with the intramedullary pin emplaced within the bone of a patient. The sensing device verifies the same location of the predrilled holes by contacting the same planar portion. The sensing device is an electrical continuity device that completes an electrical circuit when the distal end of the sensing device contacts the planar portion of the intramedullary pin, thereby activating an alerting device to notify the physician that the contact has been established and the predrilled holes are accurately located.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a sensing device for use with a medical procedure and, more particularly, to a device to aid in the accurate location and orientation of an intramedullary pin. 
       BACKGROUND 
       [0002]    In the healing of certain fractures in bones of a patient, particularly the femur and tibia bones, one common procedure is the surgical emplacement of intramedullary pins within the bones. In such procedure, the intramedullary pin is normally retained in the desired position within the bone by means of securing screws that pass through the bone and pre-drilled holes in the intramedullary pin at both the distal and proximal ends of the intramedullary pin. 
         [0003]    One of the difficulties, therefore, is to make sure that pin is in the exact desired location for receiving the screws since it is a blind procedure and the physician cannot actually see the intramedullary pin or the location of the pre-drilled holes in that pin. 
         [0004]    One of the present methods of locating the pin position and the location of the holes therein involves the use of an image intensifier, however, that is a relatively costly device in that setting and hampers the surgeries. 
         [0005]    Another currently used system involves an external frame that is set up prior to inserting the intramedullary pin onto the bone and the location of the holes in the distal end of the intramedullary pin is accomplished with a metal stick which fastens to and controls the correct position of the external frame system whenever that metal stick contacts the midline of the longitudinal axis of the intramedullary pin. 
         [0006]    Again, however, since this is a blind procedure, it is difficult to evaluate and verify with total accuracy, the metal sound as the metal stick contacts the intramedullary pin that is indicative of the correct placement of the intramedullary pin contacting the midline of the longitudinal axis of the intramedullary pin. 
         [0007]    The difficulty is, however, that with the metal stick is inserted, there must be a certainty that it is touching the intramedullary pin and further, where that contact takes place. In more the 50% of the cases, the extremity of the metal stick is wedged medially or laterally in relation to the intramedullary pin and thus allows a misalignment of the holes in the intramedullary pin when the screws are attempted to pass through those holes. 
         [0008]    Since the bone&#39;s cortical area is solid, the contact between the metal stick and the solid cortical area could often be confused with contact with the intramedullary pin. Alternatively, the metal stick could be contacting the intramedullary pin in a lateral or offset location in relation to the midline of the intramedullary and therefore not at the midline itself. The problem is exacerbated by the fact that the intramedullary pin changes position when it is inserted into the medullary canal. 
         [0009]    To a large degree, therefore, the effectiveness of locating the position and orientation of the distal end of the intramedullary pin is determined by the skill for the surgeon. 
         [0010]    It would, therefore, be advantageous to have a relatively simple system that can be used to accurately locate the position and orientation of the intramedullary pin to verify that the holes in the distal end are properly positioned and aligned to receive the securing screws. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, the present invention relates to a sensing device and system for accurately determining the location and orientation of an intramedullary pin surgically emplaced within a bone of a patient. 
         [0012]    The sensing device has a distal end and a proximal end and has a handle located at the proximal end. In the exemplary embodiment, the handle has an internal compartment within which there is an electronic circuit and an electrical source to power that electronic circuit. The electronic circuit has first and second electrical contacts such that when an electrical circuit is completed between both contacts, a signal is provided to activate an alerting device to alert a physician that the electrical circuit has been completed. 
         [0013]    While the exemplary embodiment includes the presence of a handle, it can be seen that the sensing device of this invention could be manipulated by means of some automatic device, such as a robotic system, and thus not require presence of a handle. 
         [0014]    As such, one contact is electrically connected to the intramedullary pin and the other is electrically connected to the distal end of the sensing device. 
         [0015]    Thus, when the distal end of the sensing device contacts the intramedullary pin, the circuit is completed and the alerting device is activated. 
         [0016]    As an alternative, the contact between the distal end of the sensing device and the intramedullary pin can be carried out by other sensing system, such as by inducing an electromagnetic field surrounding the intramedullary pin and/or the distal end of the sensing device and an electrical circuit provided to sense the change in that electromagnetic field when contact is made between the distal end of the sensing device and the intramedullary pin. 
         [0017]    The device is used in a system that determines the orientation of the intramedullary pin, first external of the bone of the patient and then with the intramedullary pin emplaced within the bone of the patient. The location of the holes in the intramedullary pin is therefore established by the system external of the patient and then repeated with the intramedullary pin emplaced within the bone and, in each instance, the orientation of the holes in the intramedullary pin are established by a contact of the distal end of the sensing device with a planar section on the intramedullary pin. 
         [0018]    The system therefore eliminates the subjective determination by a physician of the contact between a sensing device and the intramedullary pin by providing a positive alert to the physician when that contact has been established, thereby providing an accurate means of determining the location and orientation of the pre-drilled holes in the intramedullary pin. 
         [0019]    These and other features and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a perspective view of an exemplary intramedullary pin for emplacement into the bone of a patient; 
           [0021]      FIG. 2  is a perspective view of an exemplary frame retaining an intramedullary pin utilizing the present invention; 
           [0022]      FIG. 3  is a perspective view illustrating the use of the present invention with an exemplary intramedullary pin emplaced within the bone of a patient; 
           [0023]      FIG. 4  is a perspective view of a sensing device in accordance with one embodiment of the present invention; 
           [0024]      FIG. 5  is an exploded view of the handle portion of the  FIG. 4  embodiment; and 
           [0025]      FIG. 6  is a schematic view of an exemplary electronic circuit useable with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Referring now to  FIG. 1 , there is shown a perspective view of an exemplary intramedullary pin  10  that is to be emplaced within the bone of a patient. The intramedullary pin  10  is generally surgically emplaced within the tibia or femur bones to repair those bones and, in general, is comprised of, for example, a conductive metal, such as stainless steel, titanium and cobalt chrome. 
         [0027]    In order to secure the intramedullary pin  10  within the bone of the patient, there are two holes  12  located at the proximal end  14  and two holes  16  located at the distal end  18 . After the intramedullary pin  10  is surgically inserting into the bone, screws are passed through the holes  12 ,  16  to secure the intramedullary pin  10  within the bone. As such, since the intramedullary pin  10  is, at that time, located within the bone itself during the insertion of the screws, it is important that the physician be able to accurately locate the holes  12 ,  16  in order to properly align and insert the screws. 
         [0028]    There is also a planar section  20  formed on the intramedullary pin  10  and that planar section  20  may preferably be in a plane that is parallel to a plane passing through the longitudinal axes of the holes  16 . 
         [0029]    Turning next to  FIG. 2 , taken along with  FIG. 1 , there is shown a perspective view of a representative frame  22  that is used to determine the initial alignment of the intramedullary pin  10  so as to later accurately determine the location of the holes  16  when emplaced within the bone of the patient. The frame  22  includes generally horizontal strut  24  comprised of a proximal section  26  and a distal section  28  with the proximal and distal sections  26 ,  28  joined together by means of a movable joint  30  that allows side to side or pivoting movement therebetween. 
         [0030]    The proximal section  26  is firmly affixed to the proximal end  14  of the intramedullary pin  10  whereas the intramedullary pin  10  itself is firmly affixed to a base  32 . The distal section  28  is affixed to the proximal section  26  by means of the movable joint  30  and a bolt  31 . 
         [0031]    An L-shaped bracket  34  is disposed generally horizontally and slidably affixed to the distal section  28 . The bracket  34  includes a boss  36  having two holes  38  that are spaced apart the same distance as the spacing of the holes  16  in the intramedullary pin  10 . In the positioning of the frame  22 , the distal section  28  is moved side to side to be in relative alignment with the intramedullary pin  10  and is then locked in that position at the movable joint  30 . 
         [0032]    The L-shaped bracket  34  can then be moved horizontally along the distal section  28  such that the holes  38  align precisely with the holes  16  in the intramedullary pin  10 . To accomplish that goal, there are two alignment pins  40  that are passed through the holes  38  to enter into the holes  16  in the intramedullary pin  10 . When that procedure has been completed, the location of the L-shaped bracket  34  is locked into position along the distal section  28 . 
         [0033]    At this point, the sensing device  42  of the present invention is inserted through a vertically movable guide  44  slidingly affixed to the L-shaped bracket  34  and the vertical movable guide  44  moved vertically until the distal end  46  of the sensing device  42  contacts the planar section  20  of the intramedullary pin  10 . When that contact has been established, an alert is signaled to the user in a manner to be later explained. 
         [0034]    In any event, when the alert is activated, the vertically movable guide  44  is locked in that position with respect to the L-shaped bracket  34  and a collar  48  tightened about the sensing device  42  marking its position with respect to the L-shaped bracket  34 . 
         [0035]    With that action, the exact location of the holes  16  is established with respect to the L-shaped bracket  34  and verified by the sensing device  42  and the frame is disassembled by separating the distal section  28  including the L-shaped bracket  34  affixed thereto by removal of the bolt  31  while leaving the proximal section  26  affixed to the intramedullary pin  10 . 
         [0036]    At this stage of the procedure, the intramedullary pin  10  can be surgically emplaced within the particular bone of the patient. 
         [0037]    Turning then to  FIG. 3 , there is shown a perspective view illustrating the intramedullary pin  10  having been surgically emplaced within a bone  50  of a patient. The proximal section  26  of the horizontal strut  24  is still firmly affixed to the intramedullary pin  10  with the intramedullary pin  10  positioned within the bone  50 . 
         [0038]    At this point, the distal section  28  is reattached to the proximal section  26  be re securing the bolt  31  whereas the orientation of the distal section  28  is retained the same as was locked in by means of the movable joint  30  so that the location of the distal section  28 , with the L-shaped bracket  34  still attached and in the same position with respect to the intramedullary pin  10  as described in  FIG. 2 . 
         [0039]    A hole is then drilled in the bone  50  by inserting a drill through the vertically movable guide  44  in the same location as was used to insert the sensing device  42  so that the intramedullary pin  10  is accessible through hole drilled in the bone  50 . 
         [0040]    With the hole drilled in the bone, the sensing device  42  is again re-inserted through the movable guide  44  and maneuvered so as to make contact with the planar section  20  of the intramedullary pin  10 . When that contact is established, there is a positive verification in the form of an alert to the physician that the sensing device  42  has made that contact and that, therefore, there is a positive indication that the holes  38  in the boss  36  are correctly and accurately positioned with respect to the holes  16  in the intramedullary pin  10 . 
         [0041]    A drill can now be used to pass through the holes  38  in the boss  36  and the drill will accurately align with the holes  16  in the intramedullary pin  10  so that holes can be drilled through bone  50  and passed through the holes  16 . Once holes are drill, screws are inserted through the bone  50  and the holes  16  to secure the intramedullary pin  10  within the bone  50 . 
         [0042]    Accordingly, as can now be appreciated, an important component of the aforedescribed procedure is the sensing device  42  that is moved to a position contacting the planar section  20  of the intramedullary pin  10  to establish the correct and accurate position and alignment for drilling holes through the bone  50  that align with the holes  16  so that the screws can pass therethrough. 
         [0043]    In  FIG. 4 , there is shown a perspective view of the sensing device  42  of the present invention. As can be seen, there is a distal end  46  and a proximal end  52 . At the proximal end  52 , there is a handle  54  for convenience in grasping and manipulating the sensing device  42  as previously described. In this exemplary embodiment, the handle  54  has an internal compartment  56  and has a cover  58  for access to the internal compartment  56 . In the exemplary embodiment, the various components used to carry out the purpose of the present invention are located within the internal compartment  56 . As can be seen, while the exemplary embodiment utilizes a handle, the present sensing device could be manipulated by means of some automatic device, such as a robotic system and thus eliminate the need for a handle. 
         [0044]    Accordingly, there is an extension  60  extending distally from the handle  54  and can be affixed to the handle  54  by a threaded engagement. The extension  60  can electrically conductive and, in one exemplary embodiment, the extension  60  can serve as an electrical contact with the intramedullary pin  10  through the frame  22  as will be later described. An insulator  62  extends distally from the extension  60  and is comprised of an electrically insulating material. Finally, there is a conductive pin  64  that extends from the insulator  62  to the distal end  46  of the sensing device  42 . The conductive pin  64  can extend proximally through the insulator  62  and the extension  60  to the internal compartment  56  of the handle  54 . There is also a threaded cap  66  located at the proximal end of the handle  54  for access to the internal compartment  56 . 
         [0045]    Turning now to  FIG. 5 , there is an exploded view of the handle  54  having the threaded cap  66  and cover  58  removed, both providing the access to the internal compartment  56 . As such, in the exemplary embodiment, an electronic circuit  68  is located within the internal compartment  56  along with an electrical source  70 , such as batteries. Thus, in such embodiment, all of the components are located within the handle  54  that are needed to carry out the use of the sensing device  42 . 
         [0046]    In  FIG. 6 , there is shown, a schematic view of an exemplary electronic circuit  68  useable with the present invention connected to an electrical source  70  and an alerting device  72 . As can be seen, there are first and second contacts  74 ,  76  that, when electrically connected together, create an electrical circuit or signal to the alerting device  72 . The alerting device  72  can be any device that has the ability of alerting the physician that an electrical circuit has been completed between the first and second contacts  74 ,  76  and may include a light signal, an audible signal or a vibrational signal. 
         [0047]    As such, the electrical circuit  68  comprises a continuity checker such that when the first and second contacts  74 ,  76  complete a circuit, the alerting device  72  notifies the physician of that completed circuit. Thus, with the first contact  74 , for example, electrically connected to the conductive intramedullary pin  10  and the second contact  76  electrically connected to the conductive pin  64  at the distal end  46  of the sensing device  42 , any contact between the distal end  46  of the sensing device  42  and the intramedullary pin  10  will activate the alerting device  72  to notify the physician of that contact. 
         [0048]    Returning to  FIGS. 2 and 3 , therefore, it can be seen that as the sensing device  42  is inserted through the vertically mounted guide  44 , the alerting device  72  will be activated upon the distal end  46  of the sensing device  42  contacting the planar section  20  of the intramedullary pin  10  thereby assuring the physician that the holes  38  in the boss  36  are accurately aligned with the holes  16  in the distal end of the intramedullary pin  10 . 
         [0049]    As also can be seen in the exemplary embodiment, the electrical connection between the first contact  74  and the intramedullary pin  10  can easily be carried out by an electrical connection between that first contact  74  and the conductive extension  60  such that when that sensing device  42  is affixed to the vertically movable guides  44 , the extension electrically contacts the frame  22 , thereby establishing a electrically conductive path to the intramedullary pin  10 . Alternatively, there may be a wire, not shown, that connects the first contact  74  to the frame  22  or any conductive portion of the frame or the intramedullary pin  10  to establish the electrical path. 
         [0050]    As an alternative, while the exemplary embodiment senses the contact between the distal end  46  of the sensing device  42  by utilizing electrical continuity, it can be seen that other electrical systems could be used, for example there may be an electromagnetic field established surrounding the intramedullary pin  10  and/or the distal end  46  of sensing device  42  such the electrical circuit determines the contact between the distal end  46  of the sensing device  42  and the intramedullary pin  10  by sensing a change in that electromagnetic field. 
         [0051]    Those skilled in the art will readily recognize numerous adaptations and modifications which can be made to the sensing device and its use of the present invention which will result in an improved device and system, including, for example, omission of the handle or locating the electronic circuit, alert indicator elsewhere in accordance with the present invention. In addition, it is possible to implement the invention by including a single contact for the sensory device for sensing an electrical signal induced in the intramedulary pin by means other than such electrical circuit yet all of which will fall within the scope and spirit of the present invention as defined in the following claims. Accordingly, the invention is to be limited only by the following claims and their equivalents.