Abstract:
A disposable safety scalpel comprises a handle and a blade carrier, which fit together such that the blade carrier can shift between a retracted position whereby a front portion of the handle covers or otherwise blocks contact with the sharp edge of the blade, and an extended position whereby the sharp edge of the blade protrudes beyond the handle. The handle has a substantially flat base portion that can be held by the forefinger of the surgeon for shifting of the carrier with the thumb between retracted and extended positions. When the carrier and blade are extended, the surgeon can hold only the base of the handle between the thumb and forefinger for cutting during surgery. The shifting between the retracted and deployed positions with only the fingers of one hand can be readily accomplished even in the presence of slippery fluids during surgery.

Description:
RELATED APPLICATION 
     This application claims priority under 35 U.S.C. 119(e) from U.S. Provisional Application No. 60/921,738 filed Apr. 4, 2007, for “Miniature Disposable Safety Scalpel”, the entire disclosure of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present invention relates to surgical scalpels and especially to miniature scalpels. 
     In order to minimize any danger of accidental injury all currently produced surgical scalpels feature means to cover or otherwise protect the sharp edge of the blade whenever the scalpel is not deployed for use, including prior to disposal after the use. Ideally this protective means should be permanently attached to the scalpel and preferably be engaged and disengaged by fingers of one hand only. 
     SUMMARY 
     The disposable safety scalpel according to the present disclosure comprises a handle and a blade carrier, which fit together such that the blade carrier can shift between a retracted position whereby a front portion of the handle covers or otherwise blocks contact with the sharp edge of the blade, and an extended position whereby the sharp edge of the blade protrudes beyond the handle. The handle has a substantially flat base portion that can be held by the forefinger of the surgeon for shifting of the carrier with the thumb between retracted and extended positions. When the carrier and blade are extended, the surgeon can hold only the base of the handle between the thumb and forefinger for cutting during surgery. 
     The shifting between the retracted and deployed positions with only the fingers of one hand can be readily accomplished even in the presence of slippery fluids during surgery. Also, the sandwiching of handle, blade, and blade carrier according to the invention, results in an exceptionally thin scalpel. As a consequence, when the scalpel is deployed, the base of the handle where grasped, the overlapping region of the locking interaction and blade attachment, and the extended blade, present an overall slim appearance as viewed by the surgeon from above. 
     In an exemplary aspect, the scalpel comprises an elongated handle having a front and a back, outer and inner sides, and vertically opposite upper and lower edges. An elongated blade carrier has front and back ends, inner and outer sides, and vertically opposite upper and lower edges. The back of the handle has a base portion, the back of the carrier has a base portion, and each of the handle and carrier has a frontal protrusion that preferably narrows vertically toward the respective front ends, thereby defining respective vertical profiles. A blade is secured to the inner side of the carrier and projects from the front of the carrier laterally adjacent to the protrusion on the handle. The blade cutting edge faces away from the bottom edge of the carrier. Longitudinal guide tracks on one of the handle or carrier engage the other of the handle or carrier, whereby the tracks maintain the carrier and handle in close parallel axial alignment while the carrier and secured blade are shiftable longitudinally relative to the handle. A locking device is located at the back end of the carrier and includes a locking member at the inside of the carrier. Two locking elements are longitudinally spaced apart on the inside of the handle and aligned with the locking member on the carrier. In this manner, the locking member is selectively engageable with each locking element as the carrier and blade shift longitudinally between a rearward locked safety position in which the cutting edge of the blade is entirely within the profile of the frontal protrusion of the handle and a forward locked deployment position in which the cutting edge of the blade projects from the front end of the handle. 
     Preferably, the engageable parts of carrier and handle are of generally similar shape but have a different size, whereby the smaller member can slide in track guides of the larger member. As a further preference, the locking device in the base portion of the carrier has a longitudinally oriented lever arm with a tooth portion that is biased toward the handle so it can snap into either of two longitudinally spaced locking windows on the base portion of the handle as the blade carrier slides forward or backward in tracks of the handle. An actuating button or the like is on the opposite end of the lever arm, facing away from the handle, such that depressing the button lifts the toothed end out of one locking window so the carrier can be shifted and secured by engagement of the tooth in the other locking window. 
     The blade carrier and handle are well suited for cooperation as a miniature scalpel, but can be configured with a handle that is much longer than the carrier. Especially with the longer handle, the guide tracks can be on either the handle or the carrier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Embodiments of the invention will be described in greater detail below with reference to the accompanying drawing, in which: 
         FIG. 1 , is a perspective view of the blade carrier and the handle, prior to joining together to form a miniature safety scalpel according to aspects of the invention; 
         FIGS. 2 and 3  are each elevation views of blade carriers showing different versions of anti-slippage surfaces on the handle portions; 
         FIGS. 4A and 4B  show the outside and the inside of the blade carrier, respectively; 
         FIGS. 5A and 5B  show the operation of a first version of the locking arm; 
         FIGS. 6A and 6B  show the operation of another version of the locking arm; 
         FIG. 7  shows the preferred profile of the region on which the tooth slides between the front and back locking windows; 
         FIG. 8  is a side view of the scalpel with the blade exposed for use; 
         FIG. 9  is a side view of the scalpel with the blade retracted for protection; 
         FIG. 10  is a view similar to  FIG. 1 , but for a second embodiment modified for use with a full length handle; 
         FIG. 11  is a variation of the scalpel of  FIG. 10 , wherein the sliding track is on the carrier rather than on the handle; 
         FIG. 12  is a perspective view of another embodiment of the miniature scalpel; and 
         FIG. 13  is a section view along line  13 - 13  of  FIG. 12 . 
     
    
    
     DESCRIPTION 
     With reference first to  FIG. 1 , the miniature scalpel  10  comprises two main components: a compact handle and protection shield combination  12  and a blade carrier and blade assembly  14 . For convenient and consistent reference, the sides of the handle and carrier that face each other will herein be deemed the “inside”, whereas the respective opposite sides will be deemed the “outside”. 
     The figure shows both main components prior to final assembly. Each part has a base portion  16 ,  18  in the back and a vertically narrowing protrusion  20 ,  22  at the front. In this embodiment the height of the base portion of the carrier  14  is less than the height of the base portion of the handle  12 , and likewise the height of the protruding portion  22  of the carrier is correspondingly less than the height of the narrowing portion  20  of the handle. Because the overall shapes are similar but the carrier is smaller than the handle, the parts are subsequently assembled by inserting of the blade carrier in between the upper and lower guide tracks  24 ,  26  at the upper and lower edges of the handle and moving the blade carrier from right to left until the toggle lever tooth  28  on the locking device  40  passes the forward (first) locking element on the handle such as rectangular opening or window  30  and then engages with the rear (second) rectangular opening  32  of the handle. This is preferably confirmed by an audible clicking sound. The blade assembly is then ready for sterilization and packaging. 
     With further reference to  FIGS. 2-9 , a shallow groove or recess  34  is provided in the inside surface of the handle protrusion  20  for accommodating the rivet heads  58 ,  60  which attach the blade to the carrier body, and thereby minimize the lateral distance between the cutting edge  36 ′ of blade  36  and the blade guide  38  of the handle when the blade is retracted. The left end  34 ′ of this groove  34  at the same time prevents any over travel toward the left, which could cause possible disengagement. Similar means, such as a small interfering notch (not shown) in the lower guide track  26 , prevents possible over travel beyond blade exposed position. 
     The handle  14  is substantially flat except that the upper guide track  24  projects transversely inward from the upper edge of the base portion  16  of the handle, and the lower track  26  projects transversely inward from the lower edge of the handle, keeping a uniform distance between them substantially equal to the uniform height of the base portion  18  of the carrier. The lower track  26  can extend from the forward portion of the base  16  substantially the full length of the front portion  20  of the handle, to cradle the lower edge of the front portion  22  of the carrier. The upper track preferably extends only along the forward portion of base  16 , approximately spanning the openings  30 ,  32 . The upper edge of the front portion  22  of the carrier is not contacted by the (foreshortened) upper track  24 . 
     In one embodiment as shown in detail in  FIG. 9 , the front portion of the handle has an inwardly projecting guide  38  for laterally contacting the cutting edge  36 ′ of the retracted blade, which faces away from the bottom edge of the carrier. The upper and lower edges of the front portion of the handle define a vertical profile P, and the blade  36  remains within the profile when in the retracted position. The top edge of the guide  38  will thus block vertical contact with the edge  36 ′ of the blade. The edge of the blade is angled obliquely as affixed to the carrier, and the guide upper edge has substantially the same profile angle. The front end  38 ′ of the guide  38  does not reach the front tip  20 ′ of the handle, but the top edge  20 ″ of the handle rises above the cutting edge and likewise blocks vertical contact with the blade edge. The main purpose of the inward projection  38  of the guide in this embodiment is to provide lateral support to the blade edge  36  and thus maintain the blade edge in proper axial alignment during shifting. 
     In another embodiment the inwardly projecting structure at the location of the guide  38  could instead be formed as a hood, cover, spaced apart studs or other transverse projection, extending along the rear portion of the handle protrusion  20 , to overly the cutting edge  36 ′ of the blade and directly shield at least the rearward portion of the cutting edge when in the retracted position. For example, track  24  could be extended along profile P. As used herein, the term “shield” should be understood as encompassing structure that contacts or covers the cutting edge of the blade in a manner that blocks vertical access to the cutting edge. 
     With particular reference to  FIGS. 1 ,  8  and  9 , the base portion  18  of the carrier has a longitudinally oriented locking device preferably in the form of a lever  40  that pivots about an axis passing through the carrier base. A locking arm cantilevered forward of the pivot axis includes a tooth portion  28  that is biased toward the handle  12  so it can snap into either of the two longitudinally spaced locking windows  30 ,  32  on the base portion of the handle as the blade carrier slides forward or backward in tracks  24 ,  26  of the handle. It is not necessary that the windows  30 ,  32  penetrate the full thickness of the handle. The biasing of the tooth  28  need not be via a separate member, but is preferably a result of the thickness of the lever  40  or tooth portion  28  relative to the separation distance between the base portions  16 ,  18  of the assembled device. An actuating arm is cantilevered toward the rear and has an actuating pad or button  42  such that depressing the button lifts the toothed end  28  out of one locking window so the carrier and blade can be shifted and secured by engagement of the tooth in the other locking window. The fulcrum of the lever is preferably formed by lateral integral web regions  44  that are thin or flexible enough to permit pivoting around the web centerlines (pivot axis)  67  that extend transverse to the lever  40 . The button extends in free space behind the web  44 , whereas the arm portion forward of the web is situated in a cut out  46  through the base  18 . 
     Preferably, as best shown in  FIGS. 1 ,  7 , and  9 , the back locking element  32  is located immediately forward of the textured surfaces  16 ′ of the base of the handle, and the front locking element  30  is longitudinally spaced forward of the back locking element. The recess  48  in the handle extends from one web  64  adjacent the locking element  32  to another web  66  adjacent the other locking element  30  whereby during shifting of the carrier relative to the handle the locking member  28  rides in the recess  48  and upon further shifting from the recess into a locking element is deflected by and rides over a web. Preferably, each of the webs has a transition slope  50 ,  52  that rises from the recess to a flat surface immediately adjacent to the respective locking element. To facilitate pivoting of the locking device, the actuator arm and locking arm have obliquely angled inner surfaces  54 ,  56  facing the handle. The pivot axis is shown at  67 . 
       FIGS. 5A and 5B  show two options  28 A and  28 B for the tooth. The tooth  28 A has a tapered or frustoconical shape  28 A′, whereas tooth  28 B′ is substantially rectangular or cylindrical with an annular shoulder  28 B′. 
     As shown in  FIGS. 2 and 3 , the textured anti-slippage surfaces on both side surfaces of the base portion of the handle can be dimples  16 ′, shallow depressions, vertical channels  16 ″ or perforations. Also, a deeply channeled or swirled surface on the actuating button  42  can be provided. This minimizes the accumulation of blood-induced finger slippage where the surgeon is expected to exert relatively opposite, axially directed forces with the forefinger and thumb to extend or retract the blade, or transverse force to lift the tooth  28  out of a locking window, or uniformly axially directed forces to produce a cutting action during surgery. 
     The above described design is very compact. In the extended position the device is the size of a conventional fixed blade thumb scalpel. Both the handle and carrier components can be manufactured in plastic with by very simple dies. Because the blade is visible even in the retracted position, neither of the parts needs to be transparent. The material of both components can be identical (type and color) making recycling much easier. 
     As shown in  FIGS. 2 ,  3 ,  8  and  9 , the base portion  18  of the carrier including the locking device  40  overlays the base portion  16  of the handle when the scalpel is in the locked safety position. Preferably one locking element  32  is located immediately forward of the textured surfaces of the base of the handle, and the other locking element  30  is longitudinally spaced forward of the one locking element  32 . Furthermore, in the locked safety position of the scalpel the carrier and blade lie within the front, back, and upper and lower edges of the handle, i.e. within the perimeter or profile P of the handle. This is a consequence of the overall similar but smaller shape of the carrier. In the deployed position of the scalpel the base  18  of the carrier is forward of the base  16  of the handle, whereby the outer and inner surfaces of the base  16  of the handle can be grasped between the thumb and forefinger for manipulating the blade, while the blade projects forwardly from the handle. 
     Also evident in  FIG. 8 , is that in the deployed position, the locking engagement of the tooth  28  in the window  30  is situated nearly vertically between portions of both upper and lower tracks  24 ,  26  that engage upper and lower edges of the carrier. This provides high stability to the lock. 
     In  FIG. 9 , the cutting edge of the blade partially overlaps laterally with the shield and the cutting edge is entirely below the upper edge of the handle protrusion, but the angle of the blade is such that when the carrier is deployed as per  FIG. 8 , a portion of the of the cutting edge overlaps but is above the protrusion of the handle while the remainder of the cutting edge is forward of the protrusion. 
     As shown in  FIG. 10 , a very similar blade carrier can be used for full length and, partially disposable scalpels. In the full length embodiment  100 , the handle  112  extends well back of the carrier  114 , i.e., at least three times the length. One of ordinary skill can optimize the profile P′ of the handle to accommodate and protect a variety of blades  136 . This affords the possibility of providing a uniform handle that can accommodate a variety of blade sizes or types. Such variety can in most instances rely on a uniform carrier; however, the protrusion at the front end of the handle must be sized to provide full protection for the variety of blades. 
     Especially in but not limited to the embodiment of a universal handle and blade carrier, relocation of the guide track  224 ,  226  from the handle  212  to the blade carrier  214  can simplify the shape of the handle to become a flat piece of material. One such embodiment is shown in  FIG. 11 . Because of the simplicity, this version would be ideally suitable for application with a semi disposable scalpel (scalpel with reusable stainless steel handle  212 ). Additional means (not shown) could be provided to protect and cover the blade  236  while still stored in its sterile pouch (prior to being attached to the handle  212 ). This protection could for example be provided by a breakaway extension of the blade carrier  214  temporarily covering the blade  236  or by a loose flat plastic flap inserted between both guide tracks  224 ,  226  covering the blade until it is pushed out by the handle during the process of attaching the blade carrier to the handle. 
     Another embodiment of the miniature scalpel  300  is shown in  FIGS. 12 and 13 , which embodiment can also be adapted with the variations shown in  FIGS. 10 and 11 . In this embodiment the orientation of the locking device on the carrier is longitudinal reversed and the locking elements on the handle are commensurately longitudinally set farther back into the base of the handle, while maintaining the slim lines and improving the ease of use. The last two digits in the numeric identifiers in  FIGS. 12 and 13  refer to functionally similar structure identified with the same two digits in  FIGS. 1-9 . 
     The scalpel  300 , shown in the deployed condition, has a handle  312  and a blade carrier  314  with respective base portions  316 ,  318  in the back and a vertically narrowing protrusion  320 ,  322  at the front. The parts are assembled by inserting of the blade carrier in between the upper and lower guide tracks  324 ,  326  at the upper and lower edges of the handle and moving the blade carrier from right to left until the toggle lever tooth  328  on the locking device  340  passes the forward (first) locking element on the handle such as rectangular opening or window  330  and then engages with the rear (second) rectangular opening  332  of the handle. 
     A shallow groove or recess  334  is provided in the inside surface of the handle protrusion  320  for accommodating the rivet heads which attach the blade  336  to the carrier body, and thereby minimize the lateral distance between the cutting edge of blade  336  and the blade guide  338  of the handle when the blade is retracted. 
     The base portion  318  of the carrier including the locking device  340  overlays the base portion  316  of the handle when the scalpel is in the locked safety position. One locking element  332  is located close at the back end of the handle and the other locking element  330  is spaced longitudinally forward. Preferably, as shown in  FIG. 13 , both locking elements  330 ,  332  on the inside of the back  316  of the handle are within the longitudinal span of the textures surface  316 ′ on the outside of the base of the handle. The recess  348  in the handle extends from one web adjacent the locking element  332  to another web adjacent the other locking element  330  whereby during shifting of the carrier relative to the handle the locking member  328  rides in the recess  348  and upon further shifting from the recess into a locking element is deflected by and rides over a web. 
     The locking device  340  has the tooth  328  toward the back and the actuating pad  342  toward the front of the base  318 . The locking device  340  can be a simple lever as in the previously described embodiments, or the actuating and locking arms can be laterally supported for a pivoting type movement, by a pair of legs or the like, such as described in U.S. Pat. No. 7,153,317. The outside back of the carrier has a no-slip, textured surface  318 ′ surrounding and forward of the locking device  340 . This provides a greater textured contact area for the thumb during shifting, than the embodiment of  FIGS. 1-9 . 
     As in the other embodiments described herein, the front portion of the handle has an inwardly projecting guide  338  for laterally contacting the cutting edge of the retracted blade  336 . The upper and lower edges of the front portion of the handle define a vertical profile and the blade  336  remains within the profile when in the retracted position. The top edge of the guide  338  will thus block vertical contact with the edge  336  of the blade. 
     For many users, the scalpel  300  according to  FIGS. 12 and 13  should feel better balanced and stable. With the actuating button  342  located more forwardly, closer to the center of the device, the tendency of any incidentally applied torque to rotate the carrier is reduced.