Abstract:
The present invention relates to a hand-held device for cutting or heating medical implants, in particular for cutting and bending resorbable implants. The device comprises a heating element electrically connectable to a power source (e.g., a battery), a switch for selectively completing the circuit between the heating element and the power source, and a housing for enclosing the battery and associated electrical connections. The invention is directed to a kit comprising a handle assembly and multiple interchangeable cutting or heating tips for use therewith. One tip member is configured for heating an implant to a sufficient temperature to cut the implant while a second tip member is configured for heating the implant to a sufficient temperature to bend the implant. A tip member housing an additional power source may be provided to bend larger size implants.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/487,885, filed Jul. 16, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to hand-held device for cutting or heating medical implants, in particular the invention relates to an in-situ bender cutter device for resorbable implants.  
       BACKGROUND OF THE INVENTION  
       [0003]     In the field of medical instruments, various hand-held instruments for heating exist. For instance, hand-held instruments exist for cauterizing tissue of a patient in order to prevent or stop bleeding from blood vessels.  
         [0004]     A typical instrument used for heating in the field of medical instruments comprises a heating element electrically connectable to a power source (e.g., a battery), a switch for selectively completing the circuit between the heating element and the power source, and a housing for enclosing the battery and associated electrical connections. The electrical connections typically comprise a strip of conductive material connecting one end of the heating element to a positive terminal of the power source and another strip of conductive material connecting the other end of the heating element to a negative terminal of the power source with the switch providing a break therebetween. The electrical circuit of the heating instrument is normally open and it does not become a completed circuit unless pressure is applied to a movable member (i.e. a button) on the exterior of the housing to engage the switch. Typically, the heating element is fixedly attached to the housing and changing the types of heating elements attached to the housing is difficult without destroying the utility of the instrument.  
         [0005]     A need exists for an improved heating instrument with interchangeable heating elements or tips.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention generally relates to a device for use with a resorbable fixation system including a resorbable implant. In one embodiment, the invention is directed to a kit comprising a handle assembly and three interchangeable tips for use therewith. The handle assembly comprises a longitudinal member extending from a proximal end to a distal end and houses a power source. The kit also includes a first tip member removably attachable to the handle assembly and comprises a first heating element electrically coupleable to the power source. The first heating element is configured and dimensioned for heating an implant to a sufficient temperature to cut the implant when the first heating element is electrically coupled to the power source while being applied to the implant. A second tip member is included in the kit and is removably attachable to the handle assembly and comprises a second heating element electrically coupleable to the power source, and the second heating element is configured and dimensioned for heating the implant to a sufficient temperature to bend the implant when the second heating element is electrically coupled to the power source while being applied to the implant. Also included in the kit is a third tip member that is removably attachable to the handle assembly. The third tip member houses an additional power source and comprises a third heating element electrically coupleable in series to both the internal power source and the power source located in the handle assembly, and the third heating element is configured and dimensioned for heating the implant to a sufficient temperature to bend the implant when the third heating element is electrically coupled to the power sources while being applied to the implant. The first heating element comprises a first surface area, the second heating element comprises a second surface area, and the third heating element comprises a third surface area, and the first, second, and third surface areas are different and are configured and dimensioned to heat to different temperatures when electrically coupled to the power source. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     Preferred features of the present invention are disclosed in the accompanying drawings, wherein similar reference characters denote similar elements throughout the several views, and wherein:  
         [0008]      FIG. 1  is a perspective view of a preferred embodiment of a hand-held device according the invention;  
         [0009]      FIG. 2  is a top view of the hand assembly of  FIG. 1 ;  
         [0010]      FIG. 3  is a cross-sectional view along line III-III of  FIG. 2 ;  
         [0011]      FIG. 4  is a top view of a preferred embodiment of a tip member for use with the handle assembly of  FIG. 1 ;  
         [0012]      FIG. 5  is a side view of the tip member of  FIG. 4 ;  
         [0013]      FIG. 6  is a top view of a preferred embodiment of another tip member for use with the handle assembly of  FIG. 1 ;  
         [0014]      FIG. 7  is a side view of the tip member of  FIG. 6 ;  
         [0015]      FIG. 8  is a top view of a preferred embodiment of yet another tip member for use with the handle assembly of  FIG. 1 ;  
         [0016]      FIG. 9  is a side view of the tip member of  FIG. 8 ; and  
         [0017]      FIG. 10  is a cross-sectional view along line IV-IV of  FIG. 8 .  
         [0018]      FIG. 11  is a cross-sectional view along line A-A of the heating element of  FIG. 10 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     Referring to  FIG. 1 , a preferred embodiment of a hand-held device  10  according to the present invention is shown. Hand-held device  10 , comprises a handle assembly  12  that mates with at least one removable tip member  14 . Handle assembly  12  comprises a generally cylindrical outer housing  16  extending from a proximal end  18  to a distal end  20 , and tip member  14  is removably attachable to distal end  20 .  
         [0020]     Referring to  FIGS. 2-3 , housing  16  includes a power source. For example, in a preferred embodiment at least one battery  22  is disposed in housing  16  toward distal end  20 , and preferably two batteries  22  are provided. Throughout the following discussion, batteries  22  may be referred to in the singular or plural, however, it will be recognized that all of the embodiments disclosed herein may be implemented using either one or two batteries. As shown in  FIG. 3 , batteries  22  may be secured with tape  23  to diminish rattling. A conductor  24  contacts battery  22  adjacent proximal end  18  and extends within housing  16  from proximal end  18  toward distal end  20  to selectively couple battery  22  to tip member  14 . A selectively depressible power button  26  is coupled to the distal end of conductor  24  adjacent distal end  20 , and extends through a slot  28  in outer housing  16 . In one preferred embodiment, conductor  24  comprises a thin metal strip and power button  26  can be ultrasonically welded to an outside face of conductor  24 . Power button  26  is selectively depressible between a rest position and a second position to flex the distal end of conductor  24  to engage tip member  14  and electrically connect tip member  14  to battery  22 . A second conductor  30  contacts the distal end of battery  22  and includes a free end  32  that extends radially inward to couple the distal end of battery  22  to tip member  14 . As best seen in  FIG. 1 , distal end  20  of handle assembly  12  includes a pair of circular socket holes  34  and a generally rectangular slot  36  for receiving tip member  14 . In a preferred embodiment, power button  26  and housing  16  are made of plastic and housing  16  preferably comprises shell members  38  ultrasonically welded together.  
         [0021]     Referring to  FIGS. 4-5 , one preferred tip member  14  comprises a cutting tip member and includes first and second conductive prongs  40 ,  42  extending from a proximal end of a tip body  44 . Prongs  40 ,  42  are electrically coupled to opposing ends of a heating element  46  that extends from the distal end of tip body  44 . A rectangular tab  48  extends proximally from tip body  44  and is configured and dimensioned to be received in slot  36  (shown in  FIG. 1 ) of handle assembly  12  for aligning tip body  44  with the handle assembly when tip member  14  is attached to the handle assembly. In a preferred embodiment, tab  48  includes a protrusion  49  along its proximal end and when tab  48  is inserted into rectangular slot  36 , the proximal end of tab  48  extends through handle housing  16  and protrusion  49  engages the interior of housing  16  to retain tip member  14  on the handle assembly  12 .  
         [0022]     As best seen in  FIG. 5 , tip body  44  is tapered from a proximal end to a narrower distal end and comprises concave lateral cutout portions on the sides to accommodate, for example, a user&#39;s fingers to facilitate attachment of the tip to handle assembly  12 . Prongs  40 ,  42  are configured and dimensioned to be received in socket holes  34  when tip member  14  is attached to handle assembly  12 . Prongs  40 ,  42  extend through socket holes  34  and into handle assembly  12  and second prong  42  contacts free end  32  of second conductor  30 . Power from battery  22  may be transferred to heating element  46  by depressing power button  26  to flex conductor  24  to engage first prong  40  and complete an electric circuit. Heating element  46  generally comprises a thin wire loop that heats up when an electric current passes through it. The thin wire loop has a relatively small surface area which facilitates efficient heating of material. When heated, the wire loop is configured and dimensioned to operate at a temperature sufficient to cut through a medical implant, and in particular a resorbable implant. In use, the implant may be cut by contacting the heating element  46  to the area of the implant to be cut with power button  26  depressed.  
         [0023]     Referring to  FIGS. 6-7 , another preferred tip member  60  comprises a narrow plate bending tip member. The proximal end of tip member  60  is substantially similar to the proximal end of tip member  14  and comprises first and second conductive prongs  60 ,  62  and a rectangular tab  68  extending from a proximal end of a tip body  64  to attach to the distal end of handle assembly  12  as described above with respect to tip member  14 . A generally cylindrical elongate flexible member  70  extends from the distal end of tip body  64  and includes a heating element  72  at the distal end. Flexible member  70  comprises an insulating material covering a conductive element that electrically couples heating element  72  to prongs  60 ,  62 . In a preferred embodiment, a protective covering  74  extends over a portion of tip body  64  and over a portion of elongate member  70  to cover and insulate the electrical connection between prongs  60 ,  62  and the conductive element extending through elongate member  70 . Heating element  72  generally comprises a flat narrow metal plate or bending element. Power from battery  22  may be transferred to heating element  72  when tip member  60  is attached to handle assembly  12 , as described above. The flat narrow plate generally has larger surface area than heating element  46 , described above, and heating element  72  is generally heated to a lower temperature relative to heating element  46 . In operation, heating element  72  is configured and dimensioned to operate at a temperature sufficient to bend or form the implant. For example, the implant may be formed by contacting the heating element  72  to the area of the implant to be bent with power button  26  depressed. Once sufficiently heated, the heated area of the implant remains malleable for a period of time and the implant may be contoured to a desired geometry.  
         [0024]     Referring to  FIGS. 8-11 , another preferred tip member  80  comprises a wide plate bending tip member. The proximal end of tip member  80  is substantially similar to the proximal end of tip members  14 ,  60  described above and comprises first and second prongs  80 ,  82  and a rectangular tab  88  extending from a proximal end of a tip body  84  to attach to the distal end of handle assembly  12 , as described above. An elongate member  90  extends from the distal end of tip body  84  and includes a heating element  92  at the distal end. Elongate member  90  extends at an angle with respect to handle assembly  12  to facilitate application of heating element  92  to an implant. Heating element  92  generally comprises a large flexible loop with a generally flat wide section in the central portion.  
         [0025]     As illustrated in  FIG. 11 , the flexible loop may have a composite structure comprising a bottom layer of foam  92   a , a flexible heater layer comprising a plastic flexible circuit  92   b  (i.e. a plurality of copper tracing sandwiched between layers of plastic), and a top layer of metal foil  92   c . The bottom foam layer  92   a  may provide structural support for the plastic flexible circuit  92   b , while the top metal foil layer  92   c  may spread the heat generated by the flexible circuit evenly over the surface of the heating element  92 . A battery  96  is disposed in housing  90  towards the distal end to provide additional current to heating element  92 . A conductor  94  contacts a coil spring  95  which in turn contacts the distal end of battery  96  adjacent distal end and extends within housing  90 , towards heating element  92 , selectively coupling battery  96  to heating element  92 . A second conductor  100  contacts the distal end of prong  82  and extends within housing  90 , towards heating element  92  selectively coupling prong  82  to heating element  92 . The proximal end of battery  96  extends to distal end of prong  80 , selectively coupling battery  96  with prong  80 . Power from battery  22  and battery  96  may be transferred to heating element  92  when tip member  80  is attached to handle assembly  12 , and power button  26  is depressed, as described above. The large metal loop of heating element  92  generally has a larger surface area than heating elements  46  and  72 , described above. This larger surface area allows the user to bend or form larger implants than with heating element  72 . In operation, heating element  92  is configured and dimensioned to operate at a temperature sufficient to bend or form an implant as described above with respect to heating element  72 , and is particularly well suited for bending or forming a resorbable mesh.  
         [0026]     In operation, hand-held device  10  may be used in heating, forming or cutting medical implants, such as plates, meshes, sheets, screws, and tacks. For instance, device  10  may be used before, during, and after surgery, in-situ or otherwise. In particular, device  10  may be used with resorbable fixation systems such as those used in maxillofacial applications. To cut an implant, the cutting tip member  14  may be attached to distal end  20  of handle assembly  12 . In this regard, rectangular tab  48  should be aligned with slot  36  for aligning tip body  44  with handle assembly  12  when tip member  14  is attached to handle assembly  12 . In use, power button  26  may be depressed for approximately 3-5 seconds to heat up heating element  46 . While keeping power button  26  depressed, heating element  46  may be applied to the area of the implant to be cut. After the implant has been cut, tip member  14  can be removed from the handle and other tip members can be attached to handle assembly  12 .  
         [0027]     The heat an implant, such as a resorbable plate, for forming or bending the implant, the narrow plate bending tip member  60  or the wide plate bending tip member  80  may be attached to distal end  20  of handle assembly  12 . In use, power button  26  may be depressed for approximately 5-10 seconds to heat up heating element  72 , or approximately 10-15 seconds to heat up heating element  92 . While keeping power button  26  depressed, heating element  72 ,  92  may be applied to the area of the implant to be heated for forming or bending. In a preferred embodiment, the heating element  72 ,  92  is applied to the implant for approximately 10-15 seconds. After the implant has been sufficiently heated, the heated area will generally remain malleable for a period of time, during which the implant can be contoured to a desired geometry. In a preferred embodiment, the implant remains malleable for approximately 7-10 seconds. After the implant is contoured to the desired geometry it may be allowed to cool to original rigidity. To contour additional areas of the implant the process can be repeated.  
         [0028]     Referring again to  FIG. 1 , device  10  may be a single use device that is disposable after use. In a preferred embodiment, a stress channel  37  extends around the circumference of outer housing  16  proximal to power button  26 . If desired, prior to disposal of handle assembly  12 , the batteries  22  within handle assembly  12  can be removed for reuse or separate disposal by cracking housing  16  open at stress channel  37 .  
         [0029]     As will be appreciated, the tip members described above can be interchangeably attached to handle assembly  12 . Such interchangeability advantageously provides the user an option to use different tip members as appropriate, depending on the type of implant to be cut, formed, contoured, or otherwise heated, particularly in the case of resorbable implants. For example, cutting tip member  14  is generally well suited for cutting implants such as resorbable plates, and screws. Narrow plate bending tip  60  is generally well suited for forming or bending resorbable plates and wide plate bending tip member  80  may be more appropriate for use to form or bend a resorbable mesh material. In this regard, a kit for use with a resorbable fixation system may be provided that comprises a handle assembly  12 , cutting tip member  14 , narrow plate bending tip member  60 , and wide plate bending tip member  80 . In a preferred kit, a handle assembly  12  will be provided, as will one cutting tip member  14 , and either a narrow or wide plate bending tip member  60 ,  80 .  
         [0030]     While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein. Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.