Abstract:
A scalpel enabling both safe blade engagement or disengagement and safe passing among personnel during surgical procedures. The blade arm assembly of the scalpel is positionable in three positions, including a retracted position, an operational extended position and a fully extended position for engagement and disengagement of the blade.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to surgical scalpels and, in particular, to surgical scalpels that have disposable, retractable and ejectable blades. 
       BACKGROUND OF THE INVENTION 
       [0002]    Surgical scalpels have long been available. However, there is need for a scalpel with better ergonomic features while meeting rigorous occupational health and safety requirements for sharps used in medical practice. More specifically, there is need for scalpels that facilitate scalpel blade engagement and disengagement (ejection). It is desirable to minimize the need to exert pressure with fingers when mounting the blade to the blade tang and to eliminate entirely the need for direct contact with the blade to disengage it from the scalpel handle. In addition, for safe passing of scalpels among surgical personnel, it is desirable for the blade to be retracted into the handle and preferably to minimize the need for visual confirmation that the blade is retracted. 
       SUMMARY OF THE INVENTION 
       [0003]    The scalpel assembly of this invention incorporates two key features enabling safe blade engagement or disengagement and safe passing among personnel during surgical procedures. For scalpel blade loading, the blade is readily positioned on the blade with one hand, and a simple retraction motion by the other hand positions the blade in a horizontal manner for entry into a guiding channel slot within the scalpel handle. During use the blade is held in the handle in a stable manner to allow for highly controlled surgical incisions without any undesirable blade mobility. For disengaging the scalpel blade, a simple extension of the blade arm, beyond the locked operational position, to a fully extended position permits the blade to disengage from its firmly fixed engagement with the blade holder, thereby enabling hands-free blade disengagement. 
         [0004]    During use of the scalpel assembly, it may be safely passed from one person to another because the blade may be easily retracted within the handle with one hand. In addition to distinct tactile indications of positioning of the blade (in a retracted or extended position), there is a distinct auditory cue. 
         [0005]    The scalpel assembly includes a handle and a blade arm sub-assembly for easy disassembly for cleaning, reassembly and subsequent sterilization for re-use. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a top view of a blade arm assembly of a scalpel of this invention. 
           [0007]      FIG. 2  is a side view of the assembly shown in  FIG. 1 . 
           [0008]      FIG. 3  is a side view of a scalpel assembly of this invention with the blade assembly retracted. 
           [0009]      FIG. 4  is a top view of the scalpel assembly of  FIG. 3 , with the blade assembly retracted. 
           [0010]      FIG. 5  is a top view of the scalpel assembly of  FIG. 3 , with the blade assembly extended to the position in which it is used. 
           [0011]      FIG. 6  is a front view of the scalpel of  FIG. 3  without the blade. 
           [0012]      FIG. 7  is a bottom view of the bi-cantilever element of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    A scalpel assembly of this invention includes a handle and a blade arm assembly that cooperate to provide both safe blade engagement or disengagement and safe passing during surgical procedures. The blade arm assembly, an embodiment  35  of which is shown in  FIGS. 1 and 2 , slides within longitudinal slots in the handle, an embodiment  20  of which is shown in  FIG. 3 , and may be positioned in either a blade retracted position ( FIG. 4 ), a blade extended operational position ( FIG. 5 ), or a fully extended blade engagement and disengagement position. 
         [0014]    As may be seen in  FIGS. 3-6 , the handle  20  is an elongated body  22  preferably having a generally uniform, more or less oval cross section (best seen in  FIG. 6 ) with a longitudinal central channel slot  24  that penetrates the handle body and two opposed internal transverse slots  29  oriented perpendicular to the central channel slot  24 . All of the slots  24  and  29  extend fully from the proximal end  21  to the distal end  23  of the handle, making it relatively easy to manufacture handle  20  from a section of aluminum extrusion. 
         [0015]    Slots  24  and transverse slots  29  together provide a T-shaped or X-shaped slot within the handle  20  within which the blade arm assembly  35  and blade  32  slide. The leading edges of slot  29  may be beveled, rounded over or otherwise eased to facilitate entry of the back end  31  of the blade into the slots  29 . 
         [0016]    A scalpel blade  32  is held on a blade holder  44  extending from one end of a blade arm  36  that slides within the central slot  24 . Blade arm  36  carries a bi-cantilever element  52  (shown in  FIGS. 1 ,  2  and  7  and further described below) that functions as a spring, and a button  38  is attached to the bi-cantilever element  52  by a pin  42 . Button  38  travels within a recessed region  39 , visible in  FIGS. 4 and 5 . 
         [0017]    The bi-cantilever element  52  is generally flat and extends from the blade arm  36  on either side so that portions of it can be received in transverse slots  29  while the element  52  more or less surrounds a portion of blade arm  36 , as may be appreciated by reference to  FIGS. 1 and 2 . Pin  42  projects from hole  63  (shown in  FIG. 7 ) bi-cantilever element  52  and through central slot  24 , but pin  42  is urged toward one side  25  (shown in  FIGS. 5 and 6 ) of that slot  24  by the spring action of bi-cantilever element  52  thereby urging pin  42  to seat in one of detents  26  or  28  when it reaches those detents, thereby locking blade arm  36  in a blade extended position (with pin  42  in detent  26 ) or a blade retracted position (with pin  42  in detent  28 ). In an alternative embodiment, a face of the slot channel that opposes the detents may have a slight indentation so that the slot width is slightly wider in that region. This alternative allows additional lateral movement of the button and pin prior to movement of the blade arm, thereby providing a more distinct lateral shift of the button and pin and increasing the tactile feel of the device. 
         [0018]    By sliding blade arm  36  so that pin  42  travels beyond detent  26  (i.e., further from detent  28 ), the base  31  of blade  32  will move out of transverse slot  29 , thereby permitting it to lift off of tang or blade holder  44  and release from blade arm  36 . With blade arm  36  in the same position, a blade  32  can easily be positioned on the blade holder  44  and then secured by sliding the blade arm  36  into the handle until pin  42  reaches at least detent  26 , at which point the base  31  of blade  32  will be captured in transverse slots  29 , thereby preventing it from disengaging from tang or blade holder  44 . 
         [0019]    The position of blade arm  36  in handle  20 , and thus the position of blade  32  is easily manipulated with one hand by finger contact with button  38  to disengage pin  42  from the detent  26  or  28  within which it is seated and by then sliding the blade arm  36  relative to handle  20  by contact with either or both of button  38  and ridges  66 . The shapes and relative positions of the components of the scalpel of this invention permit all of these manipulations to be done with one hand. Simple reversal of the scalpel blade and blade tang accommodates both left and right handed scalpel users. 
         [0020]    As explained above, the blade arm assembly  35  consists of several components: the blade arm  36 , the button  38  and pin  42 , and the planar bi-cantilever element  52 . The function of the bi-cantilever element  52 , shown in  FIG. 7 , in cooperation with the button  38  and pin  42 , is to control movement of the blade arm  36  within the handle  20 , and to provide positively locking positions (together with audible confirmation of achievement of those positions) with the blade  32  in an extended for use or a retracted for safety position. Element  52  functions as a spring but in a planar structure that travels and functions partially within the transverse slots  29  that also serve to receive and retain blade  32  on tang or blade holder  44 . Moreover, the geometry and material of element  52  is durable, capable of sterilization and otherwise highly functional in this application. 
         [0021]    In the embodiment shown in  FIG. 7 , the crook  60  of one arm  54  of bi-cantilever element  52  is shaped to fit around the head  56  of the second cantilever arm  58 , thereby allowing for a spring-like action limited in its inward travel by the contact between the two cantilever arms  54  and  58  as they are squeezed toward each other. The head  56  and crook  60  of the bi-cantilever element  52  align edge-to-edge in the horizontal plane (coming out of the page in  FIG. 2 ), which restricts the lateral inward movement of the assembly  35  and provides for definitive control of the motion of button  38 . In other words, the crook  60  cradles the head  56  when the element  52  is compressed. In an alternative embodiment, inward or outward motion of the button is restricted by the physical contact of the button pin with the edge of the channel slot. In this embodiment, it is not necessary for the fixed portion of the cantilever element to interact with the non-fixed section of the cantilever element to control the extent of lateral motion. As a result, the fixed cantilever portion may be shorter in length. 
         [0022]    The assembly of button  38  and pin  42  may be permanently joined to the distal end of the bi-cantilever element  52 . In another embodiment, the button  38  and pin  42  may be fastened to blade arm  36  in a manner similar to that of a semi-tubular rivet. In this manner, the scalpel assembly may be formed so that either of the arms  54  or  58  may act as the flexible member of the spring element. In yet another embodiment, both arms  54  and  58  are flexible and free to move. 
         [0023]    The bi-cantilever element  52  may be inserted or removed from the main blade arm  36 , if required, but it is normally maintained assembled to the blade arm  36 . Notch  53  (shown in  FIGS. 1 and 7 ) of bi-cantilever element  52  is adapted to receive the blade arm  36 . 
         [0024]    As shown in  FIG. 2 , a step-like feature  64  is located at the junction of the blade holder  44  and the rest of the blade arm  36  to allow for a ramping up motion as the blade arm  36  moves toward the distal end  23  of holder body  22 , thereby positioning the scalpel blade  32  for alignment with the traverse slots  29 , facilitating retraction of scalpel blade  32  into the proximal end  21  of the handle body  22 . This motion of the blade arm  36  generally requires a relatively loose fit between the blade arm  36  and the bi-cantilever element  52 . The ramping up motion is partially guided by a channel  61  (shown in  FIG. 2 ) in the blade arm  36  while the bi-cantilever element  52  remains captured in the traverse slot  29 . If, as an alternative to the separate blade arm  36  and element  52  assembly shown in the Figures, a one-piece molded assembly is used for arm  36  and bi-cantilever element  52 , the inherent properties of the materials (such as plastics or plastic composites) could allow for a similar flexible motion to permit for horizontal blade alignment with the slots  29 . Alternatively, any other suitable structure may be used to create this ramping motion. For example, the inner topmost portion of the opening of the proximal end of the handle may be slightly beveled (e.g. 30 degrees), providing a ramping force to gently push the distal end of the scalpel blade downwards and onto the blade tang. 
         [0025]    Engagement of the button pin  42  with the detents  26  or  28  produces an audible sound, confirming the tactile sense of detent engagement with the button  38  and pin  42 . The need for visual confirmation of either blade retraction or extension may be minimized by the combined tactile and auditory cues. 
         [0026]    In the embodiment shown in the Figures, the transition area  33  (shown in  FIG. 4 ) between the proximal detent  26  and a side of the slot includes a steeper, almost perpendicular, rise requiring an increased lateral force on the button  38  followed by a forward motion along the handle channel to allow the blade arm  36  to travel from the operational, blade extended position (with button pin  42  in detent  26 ) to the further extended position (in which pin  42  is located proximally to detent  26 ) allowing for blade disengagement. The transition area  34  (shown in  FIG. 5 ) between the distal detent  28  and a side of the slot may be more gradual, requiring less force to travel from a retracted position to an operational position. 
         [0027]    Uni-directional blade arm loading occurs from the distal end  23  with the detents  26  and  28  engaging the button  38  and pin  42  on the blade arm  36 , automatically locking in place at either the fully retracted or extended blade positions. 
         [0028]    The handle  22  may be easily separated from the inner components (blade arm  36 , bi-cantilever element  52 , pin  42  and button  38 ) for cleaning. During such separation, the button  38  position is maintained essentially along the axis of the channel  24  for pulling the blade arm assembly back and out from the handle body  22 . 
         [0029]    The blade-securing structures of tang or blade holder  44  on the blade arm  36  are generally the same as those disclosed in U.S. patent application Ser. No. 09/937,542 filed Sep. 26, 2001 for Scalpel Assembly, Michael S. G. Bell, et al, inventors (PCT/1800/00426, WO 00/61014) which is incorporated herein by this reference. A scalpel handle body of this invention can accommodate in its standard configuration essentially all scalpel blades complying with ISO 7740-1985 (E) standards except for those that have a hooked or curved surface which would require a larger opening adaptation at the proximal end of the handle. As shown in  FIG. 6 , shallow notches  61  located on the upper inner surface of transverse slot  29  may be included in order to accommodate rib-backed scalpel blades, which are designed to prevent snapping of the blade during surgery. 
         [0030]    For improved control and to facilitate gripping of the handle body  22 , ridges  46  are positioned across the width of the handle body  22  top-most and bottom-most edges on the proximal portion  48 . These ridges may be about 0.6 mm deep, or any other suitable size. Ridges  46  may cover approximately ¼-⅓ of the handle length. 
         [0031]    Handle body  22  may include ruler markings (not shown in the Figures) imprinted or stamped on the non-slotted broad face  50  (shown in  FIG. 10 ) of the handle body  22 . In addition, the handle  22  can be made of different lengths to provide industry standard scalpel assemblies, such as #3, #3L, #4, #4L. Handle  22  may also be weighted if desired depending upon the materials used. 
         [0032]    The top-most surface of the blade arm  36  may include ridges  66  (shown in  FIG. 2 ) to provide adequate contact area for one-finger induced motion, either forward or backwards, of the blade arm  36 . 
         [0033]    The button  38  can be colored differently to indicate different scalpel types. 
         [0034]    The inner assembly of blade arm  36 , bi-cantilever element  52 , button  38  and pin  42  can be produced as individual components and then assembled or it can be produced as a single entity by, for instance, metal injection molding or machining, or molding or otherwise fabricating of plastics or a plastic composite. 
         [0035]    The handle body  22  and inner blade arm  36  assemblies can be produced from materials such as aluminum, stainless steel, titanium or plastic allowing for a full-range of sterilization techniques to be used (e.g. steam, gas, E-beam or gamma irradiation sterilization). 
         [0036]    The scalpel assembly of this invention can be produced for reusable (non-disposable) or disposable systems. 
         [0037]    As will be understood by those skilled in the art, variations in materials or manufacturing techniques and numerous other variations in the details of the protected blade scalpel handle of this invention can be made without departing from the scope and spirit of this invention as described above and in the accompanying Figures and the following claims.