Surgical scalpel
This application is a Continuation Application of application Ser. No. 08/163,938, filed on Dec. 8, 1993, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The field of the invention is surgical cutting instruments. Conventional surgical instruments provide a significant potential for harm to surgeons, nurses and other support personnel. In the operating room, various surgical instruments are quickly passed by hand. The rapid handling of such instruments with exposed sharp edges can lead to accidental cuts or puncture wounds. Surgical gloves may also be inadvertently punctured leading to loss of glove integrity further increasing the risk of infection to a surgeon, nurse or other medical personnel. 
     Previous attempts to guard against inadvertent cuts or punctures led to the development of retractable blade guards. Some of the earliest versions were simply retractable bladed knives used in various industries outside the medical field. These blade guards generally required two hands to operate, i.e., one hand to manipulate the blade and a second hand to secure the blade guard by turning a threaded screw. Other conventional devices having spring loaded moving parts or tabs that clipped into notches on a hollow tubed sheathing device, were not practical for surgical use because they did not provide a good grip or &#34;feel&#34; for the blade. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an improved scalpel. Preferably, a handle has a male or female end on one end to which a blade holder is attached. A sleeve or cover most desirably slides onto both the handle and the blade holder, preferably by guide flanges that engage channels on both pieces. The surgical blade may be exposed for use by retracting the sleeve. The blade may be covered by manually manipulating the sleeve into an extended position. In a preferred embodiment, the handle is metal and the blade holder is plastic, allowing the natural friction forces to hold them together. 
     The blade holder and the sleeve may advantageously be removed as a unit and the used blade easily disposed of while covered. The scalpel provides a good feel for or grip on the blade because the blade is secured to the handle. Accordingly, it is an object of the invention to provide an improved scalpel having a blade cover or sheath. Other and further objects and advantages will appear hereinafter to those skilled in the art from the following description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, wherein similar reference numbers denote similar elements throughout the several views: 
     FIG. 1 is an exploded side elevation view of a preferred embodiment of the present scalpel; 
     FIG. 2a is a top view of the blade holder; 
     FIG. 2b is a side elevation view of the blade holder illustrating the position of the hook in the preferred embodiment and illustrating a partial section view of the attachment slot; 
     FIG. 2c is a back end view of the blade holder showing the hook and the attachment slot; 
     FIG. 2d is a front end view thereof; 
     FIG. 3a is a top view of the handle shown in FIG. 1; 
     FIG. 3b is a side elevation view of the handle illustrating the groove and a male end attachment flange; 
     FIG. 3c is a section view taken along line 3c--3c of FIG. 3b; 
     FIG. 3d is a front end view of the handle; 
     FIG. 4a is a top view of the sleeve; 
     FIG. 4b is a side elevation view thereof; 
     FIG. 4c is a section view of the sleeve taken along line 4c--4c of FIG. 4b; 
     FIG. 4d is a front end view of the sleeve showing the arch; 
     FIG. 5a is a side elevation view of the assembled scalpel with the sleeve positioned in an extended position; 
     FIG. 5b is an elevation view thereof with the sleeve in a retracted position; 
     FIG. 5c is a side elevation view with the sleeve removed; 
     FIG. 6 shows a perspective view of an alternative embodiment of the blade holder with the blade attached; 
     FIG. 7 is a perspective view of an alternative embodiment of the handle; 
     FIG. 8 is a perspective view of a second alternative embodiment of the handle; 
     FIG. 9 is a perspective view of an alternative embodiment of the blade holder having a female end connection; and 
     FIG. 10 is a perspective view of an alternate embodiment of the sleeve. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning in detail to the figures, the surgical scalpel 10 is first shown in FIG. 1 with the blade 12 secured to the blade holder 20. The scalpel 10 is gripped by the handle 50 which has a preferably contoured elongated grip portion 52. As shown in FIGS. 2a and 2b, adjacent the front end of the blade holder 20 are two tabs 22 and 24 for securing the blade 12 to the blade holder 20 by interlocking with respective openings on the blade 12. Adjacent the back end of the blade holder 20 is the attachment slot 26 shown as a female end connection. Channels 28 are positioned longitudinally on opposite sides of the blade holder 20 along a channel section 30 of the blade holder 20. 
     A hook 32 is cantilevered from the back end of the blade holder 20. The hook 32 can resiliently flex upwardly and downwardly to engage the handle 50. The cantilevered end of the hook 32 has an inclined aft surface 34 and a protrusion 36 which is adapted to engage a complementary shaped groove 60 on the handle 50 when the blade holder 20 mates with the handle 50. 
     Referring now to FIGS. 3a and 3b, a pair of guide channels 54 are provided on opposite sides of the guide channel section 48 of the handle 50 in front of the grip portion 52. The guide channels 54 terminate at detents 56 where the guide channel section 48 adjoins the grip portion 52. 
     An attachment flange 58 (shown as a male ended attachment) is joined to the front end of the guide channel section 48. As shown in FIGS. 3b and 3d, the attachment flange 58 is generally rectangular in cross section, although other configurations are possible, and is adapted to mate with the attachment slot 26 of the blade holder 20. A groove 60 at the forward end of the guide channel section 48 is shaped to mate with the hook 32. 
     Next referring to FIGS. 4a through 4d, the sleeve 70 is generally U-shaped in cross section having a closed bottom portion and an open upper portion. A pair of guide flanges 72 are positioned within the sleeve 70 and are adapted to engage the guide channels 54 and 28. An arch 74 at the back end of the sleeve 70 spans between the two sides of the sleeve 70. The arch 74 preferably has a radiused front surface 76. 
     The sleeve 70 preferably has a digit engaging portion 78 adjacent to the arch 74 having a series of ribs forming a thumb rest. The digit engaging portion 78 improves the surgeon&#39;s &#34;feel&#34;  for the sleeve 70 when the sleeve 70 slides along the guide channels 28 and 54 by hand or thumb pressure. FIG. 5a shows an assembled scalpel 10 with the sleeve 70 in a forward position to cover or sheath the blade 12. The forward movement of the sleeve 70 is guided by the guide flanges 72 that travel along the guide channels 28 and 54. With the sleeve 70 moved fully forward, the radiused surface 76 contacts the hook 32 to stop additional forward movement. Additional forward movement by the sleeve 70 toward the extended position as guided by the user&#39;s hand will cause the arch 74 to lift the hook 32 out of the groove 60 for removal of the blade holder 20 from the handle 50. This allows the sleeve 70 and blade holder 20 to be disassembled as a unit from the handle 50 while the blade 12 is sheathed by the sleeve 70, thus minimizing the risks of inadvertent cuts. The blade 12, blade holder 20 and sleeve 70 may then be disposed of. The handle may advantageously be reused. 
     FIG. 5b shows the sleeve 70 moved to the fully retracted position with the back end of the sleeve 70 abutting the detents 56 to fully expose the blade 12. The user may utilize the digit engaging portion 78 on the sleeve 20 to improve fingertip control of the longitudinal front to back movement of the sleeve 70. FIG. 5c shows the sleeve 70 removed from the handle 50 (for purposes of illustration). 
     FIG. 6 illustrates an embodiment of the blade holder 20 with both a male ended attachment and a female ended slot. FIG. 7 shows an embodiment of the handle 50 which mates with the blade holder 20 shown in FIG. 6. An alternative embodiment of the handle 50 is also shown in FIG. 8 with male ended connections. An embodiment of the blade holder 20 which mates with the handle 50 of FIG. 8 is further shown in FIG. 9 with an outline of the attached blade 12. An alternative embodiment of the sleeve 70 is shown in FIG. 10 which illustrates a stop tab 80 which may be utilized to stop forward longitudinal sliding of the sleeve 70. An inclined digit engaging portion 78 feature is illustrated and may be used to facilitate use as a thumb rest for the operating surgeon. 
     While a preferred embodiment of the present invention has been shown and disclosed in the drawings and specification, alternate embodiments of the present invention would be apparent to the person of ordinary skill in the art and this application is intended to include those embodiments within the full breadth and scope of the claims. Moreover, the present invention need not include all of the features disclosed in the single embodiment but rather one or more features may be included.