Abstract:
A scalpel assembly utilizing an ejectable blade allowing easy installation and removal of the blade. Use of an ejectable blade permits a used or contaminated blade to fall freely from the scalpel assembly without direct contact with the blade.

Description:
RELATED APPLICATION DATA 
   This application claims priority under U.S. law to U.S. Patent Application No. 60/128,529 filed Apr. 9, 1999, entitled “Scalpel Assembly” which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a scalpel having a releasable, detachable or disposable blade and a reusable scalpel assembly. 
   2. Description of Related Art 
   Surgical scalpels have long been available, including such devices utilizing detachable or disposable blades that have a keyed or keyhole shaped slot. There is a need for a scalpel with better ergonometric properties. In addition, there is a need for a scalpel assembly that allows easy installation of a blade and that allows easy, safe release of a detachable or disposable blade and that can be manipulated with one hand. There is also a need for such a scalpel assembly to be durable and able to withstand repeated autoclaving and other sterilization techniques. 
   SUMMARY OF THE INVENTION 
   This invention is a scalpel assembly for disposable or detachable blades ejectable with the push of a button. This allows a used or contaminated blade to fall freely from the scalpel assembly into a disposal receptacle, such as a sharps container, without direct contact of medical personnel with the used or contaminated blade. A conventional disposable or detachable blade having a keyed slot is utilized and engaged by a blade bar that extends from a handle assembly. This blade bar may be extended with one hand by manipulating a push button or other actuator, releasing the blade from the handle. The push button is located on the handle remote from the blade, so that contact between the user&#39;s fingers and the blade is unnecessary and unlikely. 
   Accordingly, it is a feature of this invention to provide a scalpel assembly that allows release of a blade without requiring medical personnel to touch the blade. 
   It is a further feature of this invention to provide a scalpel assembly that allows release of a blade by manipulation with one hand. 
   Another feature of this invention is to provide a scalpel assembly that allows easy blade installation. 
   It is another feature of this invention to provide a scalpel assembly that is durable, and capable of withstanding repeated sterilization. 
   Another feature of this invention is to provide a scalpel assembly with desirable ergonometric properties. 
   This invention can be better understood by reference to the Brief Description of the Drawings, which should not be interpreted to limit the scope thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of one embodiment of the scalpel handle assembly of this invention. 
       FIG. 2  is an exploded perspective view of the handle body assembly of the scalpel assembly shown in  FIG. 1 . 
       FIG. 3  is a side elevation view of the assembled handle body assembly of  FIG. 2 . 
       FIG. 4  is an exploded perspective view of a button assembly forming a part of the scalpel assembly of one embodiment of this invention. 
       FIG. 5  is a side elevation assembly view of the button assembly of  FIG. 4 . 
       FIG. 6  is a top plan view of the proximal portion of the blade bar of this invention. 
       FIG. 7  is a side elevation of the proximal portion of the blade bar of this invention. 
       FIG. 8  is a top plan view of the scalpel assembly of  FIG. 1 . 
       FIG. 9  is a side elevation view of the scalpel assembly of  FIG. 1 . 
       FIG. 10  is a longitudinal section view of the push rod shown in  FIG. 1 . 
       FIG. 11  is a side elevation section view of the button retainer shown in  FIG. 1 . 
       FIG. 12  is a side elevation view in section of the button shown  FIG. 1 . 
       FIG. 13  is a perspective view of a collet core forming part of the handle body assembly shown in  FIG. 8 . 
       FIG. 14  is an end elevation view of the collet core of  FIG. 13 . 
       FIG. 15  is a side elevation section view of the collet core of  FIG. 13 . 
       FIG. 16  is a perspective view of the collet of the handle body assembly of  FIG. 2 . 
       FIG. 17  is an enlarged end elevation view of the collet of  FIG. 16 . 
       FIG. 18  is a side elevation section view of the collet of  FIG. 16 . 
       FIG. 19  is a side elevation view of a push rod forming part of the button assembly of an alternative embodiment of this invention. 
       FIG. 20  is a side elevation section view, in section, of the button forming part of a button assembly of an alternative embodiment of this invention. 
       FIG. 21  is a side elevation view, in section, of the button retainer forming part of the handle assembly of an alternative embodiment of this invention. 
   

   DETAILED DESCRIPTION 
   This invention relates to a scalpel having an easily detachable, optionally disposable blade that can be removed by actuation of a button with the same hand holding the scalpel assembly. This eliminates the need for medical personnel to handle or touch the blade after the blade has come into contact with surgical patients or their body fluids. 
   The scalpel is an ergonomic surgical instrument, and the disposable or detachable scalpel blade need be handled only when it is sterile and is being attached to the scalpel assembly, if at all. In a more particular embodiment of this invention, the scalpel assembly comprises an attachment mechanism for receiving and engaging a disposable or detachable scalpel blade, and may desirably be adapted to receive and engage conventional scalpel blades. As used in the description of the scalpel assembly of this invention, a proximal end is one nearer to the blade tip and a distal end is one remote from the blade tip. 
   The scalpel assembly includes a handle body, which provides a surface for the surgeon or medical personnel to grip the scalpel during transport or use. A button assembly inside the handle body serves to allow attachment and detachment of the blade from the scalpel assembly. The handle assembly is made up of a collet core, a collet, a handle body, and a button retainer. The collet houses the collet core. The proximal end of the handle body is attached to the collet. The interior surface of the distal end of the handle body is adapted to receive and engage the proximal end of the button retainer after the button assembly is inserted into the handle assembly. The button assembly is made up of a blade bar, a spring, which may be tapered, a push rod, and a button. The blade bar contains a groove and heel forming a tang, which allows it to engage a blade. The proximal end of the spring engages the interior of the handle assembly, desirably toward the proximal end. For example, the spring may engage the distal end of the collet. The distal end of the spring is engaged by the push rod. The distal end of the blade bar is engaged with the proximal end of the push rod. The proximal end of the button is attached to the distal end of the push rod. Alternatively, two or more of the button, the push rod and the blade bar may be an integral component. Depression of the button compresses the spring and extends the blade bar, disengaging the blade. In alternative embodiments, the push rod may be actuate by a button, lever, slide or other mechanism located intermediate the ends of the handle rather than at the handle&#39;s distal end. 
   This invention is described below by reference to the drawings; however, it should be understood that the drawings are directed to a specific embodiment of the invention and do not limit the scope thereof. 
   As shown in  FIG. 1 , the scalpel assembly  86  of one embodiment of this invention includes a handle body assembly  40  and a button assembly  78 . The handle body assembly of this embodiment contains collet core  20  housed within collet  22 . Collet core  20  is penetrated by bore  24 , which provides for movement of blade bar  44  in and out of, and laterally within, collet core  20  during engaging and releasing of the blade  50  in response to depressing button  76 . Collet core  20  also contains a pair of sloping front surfaces  21  and  23 . Collet core  20  is inserted into collet hole  26  of collet  22  with a press fit, as shown in  FIGS. 2 and 3 . Distal end  28  of collet  22  is inserted into body bore  29  at proximal end  30  of handle body  32  with a press fit, as shown in  FIGS. 2 and 3 . In an alternative embodiment, either the button assembly, the handle body assembly, or both, may be manufactured as a single unit. Proximal end  34  of button retainer  36  is connected to distal end  38  of handle body  32 . 
   The button assembly  78  contains blade bar  44 , tapered coiled spring  56 , push rod  62 , and button  76 . As best shown in  FIGS. 6 and 7 , proximal end  42  of blade bar  44  contains a groove  46 . Grove  46  in the proximal end  42  of blade bar  44  and extending along portions of two of the blade bar&#39;s opposed sides, and a heel  45 , define a tang  47  that is received in keyed slot  48  in blade  50 . When tang  47  is inserted in keyed slot  48  of blade  50 , the narrower portion of keyed slot  48  engages the unshaped groove  46  in proximal end  42  of blade bar  44 . 
   Reduced diameter distal end  52  of blade bar  44  enters proximal end  54  of tapered coiled spring  56 , telescopes through tapered coiled spring  56 , and is received in push rod bore  58  in proximal end  60  of push rod  62 . Tapered coiled spring  56  is telescopingly connected to proximal end  60  of push rod  62 , so that smaller diameter distal end  64  of tapered coiled spring  56  is captured by notch  66  on push rod  62 . As shown in  FIGS. 1 and 4 , distal end  68  of push rod  62  contains a recess or flat surface  70 . This recess  70  allows air to escape when reduced diameter distal end  68  of push rod  62  is telescopingly inserted into button bore  72  in proximal end  74  of button  76 . 
     FIGS. 4 and 5  illustrate how blade bar  44 , tapered coiled spring  56 , push rod  62  and button  76  combine to form button assembly  78 . Blade bar  44  is formed at an angle  79  to allow blade  50  to be freely inserted or removed in the extended position of the scalpel assembly, and held in place on blade bar  44  upon retraction, further described below. Button assembly  78 , shown in  FIG. 5 , is inserted into handle assembly  40 , shown in  FIG. 3 , before button retainer  36  is connected to distal end  38  of handle body  32 . Button retainer  36  is then connected to distal end  38  of handle body  32  so that button  76  passes through button retainer bore  80 . Proximal end  34  of button retainer  36  is threadedly connected to distal end  38  of handle body  32 . Proximal end  74  of button  76  is held in place in handle body  32  by button retainer  36 . Scalpel assembly  86  is shown in  FIGS. 8 and 9 . 
     FIG. 10  shows push rod  62 . Push rod bore  58  is located at proximal end  60  of push rod  62 . Recess  70  is located at distal end  68  of push rod  62 . Push rod  62  has annular depression or notch  66 . As shown in  FIG. 11 , distal end  88  of button retainer  36  can be knurled to make disassembly easier. Threads  92  on button retainer  36  allow button retainer  36  to be joined to distal end  38  of handle body  32 .  FIG. 12  shows button  76 , which has button bore  72  at proximal end  74 . 
     FIGS. 13 ,  14  and  15  depict collet core  20 . Proximal end  94  of collet core  20  contains longitudinally oriented, centered slit  96  positioned transverse to the wider dimension of bore  24 . Collet core  20  has collet core bore  24  that has a greater height (in  FIG. 14 ) than width and may be oval as shown, rectangular or another appropriate shape that confines side-to-side bar movement along slit  96  and permits such movement transverse to slit  96 . Collet  22  is depicted in  FIGS. 16 ,  17  and  18 .  FIGS. 16 and 18  show threads  98  on collet  22 . 
   Retraction of blade bar  44  secures blade  50  by positioning distal end  100  of blade  50  within slit  96  of collet core  20 , so that blade  50  is held in place on blade bar  44 . Blade bar angle  79  allows blade  50  to be inserted and removed from blade bar  44  when the handle is in an extended position, and holds blade  50  in place, coaxial with or parallel to the longitudinal axis of the handle, upon retraction. As can best be seen in  FIGS. 6 and 7 , blade bar  44  is bent so that proximal end  42  is at an acute angle  79  relative to distal end  52  (and the longitudinal axis  51  of the button assembly  78  and scalpel assembly  86 ). Groove  46  is positioned at an acute angle  81  (at least approximately equal to angle  79 ) relative to the tang face  83  of blade bar  44 . This causes blade  50  to be at least approximately coaxial with the longitudinal axis of scalpel assembly  86  when blade  50  is secured in scalpel handle assembly  86 . 
   Collet core  20  has slit  96 , which traps blade  50  upon retraction. Front surfaces  21  and  23  each slope toward slit  96 , thereby serving to guide distal end  52  of blade bar  44  into slit  96  when blade bar  44  retracts into collet core bore  24 , drawing blade  50  back with it. The oval shape of bore  24  allows blade bar  44  to move perpendicular to slit  96  as blade bar  44  is guided into slit  96  by one or both of the pair of front surfaces  21  and  23 . The slit urges the distal end of blade  50  toward blade bar  44 , thereby retaining the keyed slot  48  in blade  50  on heel  45  of tang  47 . Tapered coiled spring  56  retracts the blade bar  44 , securing blade  50  in the scalpel assembly  86  while the flared larger diameter end of spring  58  permits the above-described lateral movement of blade bar  44 . 
   Blade  50  may be released with one hand by pressing of button  76 . Depression of button  76  forces blade bar  44  out of proximal end  94  of collet core  20  so that blade  50  is discharged from slit  96  in collet core  20  and blade  50  disengages from blade bar  44 . This allows easy installation and push button ejection of blade  50 . 
   This invention may be formed from any durable metals, including aluminum, stainless steel, and autoclavable plastics. The scalpel may be made in any desired size, although typical handle lengths range between 3.5 and 6 inches and typical handle diameters range between 0.330 and 0.750 inch. The shape of the handle may vary from full round to oval or multi-faceted shapes in order to suit a range of ergonomic considerations. 
     FIG. 19  depicts an alternative push rod  102 , for use in the scalpel assembly of this invention.  FIG. 20  depicts an alternative button  104 , for use in the scalpel assembly of this invention.  FIG. 21  depicts an alternative button retainer  106  for use in the scalpel assembly of this invention. 
   The invention has been described by reference to specific embodiments, but is not limited to these embodiments. The invention extends to all variations and equivalents thereof within the scope of the following claims, as would be apparent to those of skill in the art.