Abstract:
A safety scalpel that incorporates a reusable metal scalpel handle similar in shape and feel to the conventional metal handle preferred by most surgeons, and a disposable blade cartridge that covers the blade before, during and after use, and is easily mounted and released from the scalpel handle. The blade cartridge includes a blade with similar cutting profiles as standard surgical blades, a blade holder that is permanently fixed to the blade, and a blade guard that covers the blade and within which the blade holder is able to slide. The scalpel handle is reusable, while the blade cartridge is disposable. The blade cartridge is attachable and detachable from the scalpel handle.

Description:
CROSS REFERENCE TO RELATED APPLICATION AND CLAIM OF BENEFIT 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 11/259,939, filed on Oct. 26, 2005, now U.S. Pat. No. 7,669,337, which claims priority to U.S. Provisional Patent Application No. 60/623,741, filed on 29 Oct. 2004. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to scalpel devices and, in particular, to safety scalpels for medical use. 
     BACKGROUND OF THE INVENTION 
     Health care is the second fastest growing sector of the U.S. economy, employing over 12 million workers. Health care workers face a wide range of hazards on the job, including needlestick and sharps injuries, back injuries, latex allergies, violence, and stress. Although it is possible to prevent or reduce health care worker exposure to these hazards, health care workers are actually experiencing increasing numbers of occupational injuries and illnesses. Rates of occupational injury to health care workers have risen over the past decade. By contrast, two of the most hazardous industries, agriculture and construction, are safer today than they were a decade ago. 
     Precise national data is not available on the annual number of needlestick and other percutaneous injuries among health care workers; however, estimates indicate that 600,000 to 800,000 such injuries occur annually. About half of these injuries go unreported. Data from EPINet (the Exposure Prevention Information Network) suggests that at an average hospital, workers incur approximately thirty needlestick injuries per 100 beds per year. 
     Most reported needlestick and sharps injuries involve nursing staff; but laboratory staff, physicians, housekeepers, and other health care workers are also injured. Some of these injuries expose workers to bloodborne pathogens that can cause infection. The more serious of these pathogens are the hepatitis B virus (HBV), the hepatitis C virus (HCV), and the human immunodeficiency virus (HIV). Infections by each of these pathogens are potentially life threatening, yet preventable. 
     The emotional impact of needlestick and sharps injuries can be severe and long lasting, even when a serious infection is not transmitted. This impact is particularly severe when the injury involves exposure to HIV. In one study of twenty health care workers with an HIV exposure, eleven reported acute severe distress, seven had persistent moderate distress, and six quit their jobs as a result of the exposure. Other stress reactions requiring counseling have also been reported. Not knowing the infection status of the source patient can accentuate the health care worker&#39;s stress. In addition to the exposed health care worker, colleagues and family members may suffer emotionally. 
     Safety and health issues can best be addressed in the setting of a comprehensive prevention program that considers all aspects of the work environment and that has employee involvement as well as management commitment. Implementing the use of improved engineering controls is one component of such a comprehensive program. Other prevention strategy factors that must be addressed, however, include modification of hazardous work practices, administrative changes to address needle hazards in the environment (e.g., prompt removal of filled sharps disposal boxes), safety education and awareness, feedback on safety improvements, and action taken on continuing problems. 
     Improved engineering controls are often among the most effective approaches to reducing occupational hazards and, therefore, are an important element of a needlestick prevention program. Such controls include eliminating the unnecessary use of needles and implementing devices having safety features. A number of sources have identified several desirable characteristics for safety devices, which include preferences for safety devices that: do not use needles; incorporate the safety feature as an integral part of the device; work passively (i.e., requires no activation by the user); have a safety feature that can be engaged with a single-hand technique and allows the worker&#39;s hands to remain behind the exposed sharp, if user activation is necessary; allow the user to easily determine whether the safety feature is activated; have a safety feature that cannot be deactivated and remains protective through disposal; perform reliably; are easy to use and practical; and are safe and effective for patient care. 
     Although each of these characteristics is desirable, some are not feasible, applicable, or available for certain health care situations. For example, needles will always be necessary where alternatives for skin penetration are not available. Also, a safety feature that requires activation by the user might be preferable to one that is passive in some cases. Each device must be considered on its own merit and ultimately on its ability to reduce workplace injuries. 
     Regarding specifically scalpels, the conventional scalpel currently used in the healthcare industry includes a metal handle and a disposable blade that is mounted on the handle prior to use, and removed after use. The process of mounting and dismounting of the blade is a difficult and dangerous procedure, which exposes the medical practitioner to potential injury from the exposed blade and contamination due to blood that may be present on the blade. Further, sharps injuries may also occur during an operation as the surgeon passes the exposed scalpel to a colleague. 
     Surgeons who have developed a feel for the shape and weight of the metal handle dislike the current disposable safety scalpels as, among other things, the plastic handle is too light and feels “different.” During use, the plastic handle of the scalpel incurs undesirable flexibility than that of a metal handle scalpel. In addition, the disposable safety scalpel is significantly more expensive than the regular disposable blade. These two factors currently limit the adoption of safety scalpels in the healthcare industry. 
     What is needed is a safe and reliable scalpel that overcomes the present objections from the healthcare practitioner of current designs, while providing adequate protection for the medical workers handling the scalpel. It is to such a device that the present invention is primarily directed. 
     SUMMARY OF THE INVENTION 
     Briefly described, in a preferred form, the present invention is an improvement over the conventional scalpel by providing a safety scalpel that incorporates a reusable metal scalpel handle similar in shape and feel to the conventional metal handle preferred by most surgeons, and a disposable blade cartridge that covers the blade before, during, and after use, and is easily mounted and released from the metal scalpel handle. 
     The present safety scalpel comprises a blade with similar cutting profiles as standard surgical blades, a blade holder that is fixed to the blade, a blade guard that covers the blade and within which the blade holder is able to slide, a scalpel handle that receives a blade cartridge (being the blade, blade holder and blade guard assembled together), and a locking assembly. The scalpel handle is reusable, while the blade cartridge is disposable. 
     While prior art designs have incorporated disposable blade cartridges where the blade guard slides off the releaseably fixed blade, the present invention is based on the blade sliding out of the releaseably fixed guard. 
     The present invention comprises a safety disposable blade cartridge that can be used with either a preferably reusable metal, or disposable plastic, scalpel handle, having the weight and feel of conventional designs. The blade cartridge easily fixes onto the scalpel handle, and yet is securely and releasably locked on the scalpel handle. The blade is preferably movable through at least three distinct positions—open, closed, and locked. 
     Attaching and detaching the blade cartridge to the scalpel handle utilizes an easy, longitudinal sliding motion. When fixed to the scalpel handle, only the blade and blade holder of the blade cartridge can move in a longitudinal direction, as the blade guard experiences limited or no longitudinal movement. 
     In other preferred embodiments, the blade cartridge is itself a standalone mini-scalpel, which is securely fixed to a passive metal handle or the blade can move within a hollow metal holder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a perspective view of a safety scalpel in accordance with a preferred embodiment of the present invention. 
         FIG. 1B  illustrates a perspective view of a safety scalpel in accordance with another preferred embodiment of the present invention. 
         FIG. 2A  illustrates a perspective view of an unassembled blade and a blade holder in accordance with a preferred embodiment of the present invention. 
         FIG. 2B  illustrates a perspective view of the assembled blade and blade holder of  FIG. 2A . 
         FIG. 2C  illustrates a perspective view of a front face of a blade holder in accordance with preferred embodiment of the present invention. 
         FIG. 2D  illustrates a perspective view of a back face of the blade holder of  FIG. 2C . 
         FIG. 3A  illustrates a perspective view of a front face of a blade guard in accordance with a preferred embodiment of the present invention. 
         FIG. 3B  illustrates a perspective view of a back face of the blade guard of  FIG. 3A . 
         FIG. 3C  illustrates a perspective view of a front face of a blade guard in accordance with another preferred embodiment of the present invention. 
         FIG. 3D  illustrates a perspective view of a back face of the blade guard of  FIG. 3C . 
         FIG. 3E  illustrates a perspective view from a proximal end of the blade guard of  FIG. 3C . 
         FIG. 4  illustrates a perspective view of assembly of a blade cartridge in accordance with a preferred embodiment of the present invention. 
         FIG. 5  illustrates a front face, perspective view of the blade cartridge attached to a scalpel handle. 
         FIG. 6A  illustrates a perspective view of a front face of a safety scalpel with the blade housed in the blade cartridge, in accordance with a preferred embodiment of the present invention. 
         FIG. 6B  illustrates a perspective view of the front face of the safety scalpel of  FIG. 6A  with the blade extending from the blade cartridge, in accordance with a preferred embodiment of the present invention. 
         FIG. 6C  illustrates a perspective view of a back face of the safety scalpel of  FIG. 6A  with the blade housed in the blade cartridge, in accordance with a preferred embodiment of the present invention. 
         FIG. 7  illustrates a close-up, front face view of a distal end of a blade cartridge with a blade extending from a blade guard, in accordance with a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now in detail to the figures, wherein like reference numerals represent like parts throughout the several views, the present safety scalpel  10  of  FIGS. 1A ,  1 B, and  6 A- 6 C, comprises a blade  100  is fixable to a blade holder  200 , which subassembly is slideable within a blade guard  300 . The combination of the blade  100 , the blade holder  200 , and the blade guard  300  forms a blade cartridge  400 , attachable to a scalpel handle  500 . 
     The present safety scalpel  10  comprises the blade cartridge  400  and the scalpel handle  500 , such that the blade cartridge  400  is configured for secure attachment to and safe detachment from the scalpel handle  500 . In a preferred embodiment of the present invention, the blade cartridge  400  is disposable, while the scalpel handle  500  is non-disposable. Accordingly, a new blade cartridge  400  can be attached to the scalpel handle  500  for use by, for example, a medical practitioner. After the medical practitioner has finished using the safety scalpel  10 , the blade cartridge  400  can be safely removed from the scalpel handle  500 , so that the blade cartridge  400  can be disposed of properly. 
     The blade cartridge  400  can comprise the blade  100 , the blade holder  200  adapted to securely engage the blade  100 , and the blade guard  300  configured to slideably receive the blade  100  and blade holder  200 . Further, the blade holder  200  is adapted to move the blade  100 , or a portion thereof, between a closed and open position. In the closed position, the blade  100  is safely and fully contained within the blade guard  300 . In the open position, the blade  100 , or a portion thereof, extends beyond the blade guard  300 . As designed, the blade  100  is in the closed position during non-use of the safety scalpel  10  and in the open position during active use of the safety scalpel  10 . The safety scalpel  10  of the present invention, therefore, provides a safe and effective surgical tool. 
     As illustrated in  FIGS. 2A and 2B , the blade  100  includes a cutting edge  110  located at a distal end  102  of the blade  100 . Further, at a proximal end  107 , the blade  100  defines an aperture  120 ; preferably an elongated aperture  120  such as a slot. Other than perhaps the profile of the cutting edge  110 , the blade  100  preferably has a similar front and back face. 
     One skilled in the art will recognize that the blade  100  can be made of a variety of suitable materials including, but not limited to, both carbon and stainless steel. Generally, the carbon and stainless steel used to create the blade  100  are manufactured in compliance with several industry standards including British Standard (“BS”) 2982:1992, International Organization for Standardization (“ISO”) 7740:1985 and European Standard (“EN”) 27740:1992. The blade  100  further can be sterilized by, for example, gamma radiation. 
     The blade holder  200  is designed to mate with blade  100 . Unlike the blade  100 , the front face  210  and back/rear face  225  of the blade holder  200  are dissimilar, and the thickness of the blade holder  200  is non-uniform. A distal end  202  of blade holder  200  comprises a holder protrusion  205  extending from the front face  210  of the blade holder  200 , in a profile that generally corresponds to the aperture  120  of the blade  100 . The holder protrusion  205  is adapted to be securely engaged in the aperture  120  of the blade  100 . 
     The blade holder  200  can further comprise a protrusion notch  215  located on a proximal end of the holder protrusion  205 , such that the protrusion notch  215  locks the blade  100  to the blade holder  200 . As the holder protrusion  205  engages the blade aperture  120 , the blade  100  preferably snaps into the protrusion notch  215 , thereby preventing the blade  100  from accidentally disengaging with the blade holder  200 . 
     The blade holder  200  further comprises, at a proximal end  207 , a holder knob  220  extending from the front face  210  of the blade holder  200 . The surface of holder knob  220  can include a number of ridges  222  for increased traction when in contact with a finger during use of the safety scalpel  10 . As described more fully below, the holder knob  220  is adapted to move the blade  100  between the closed and open positions when in communication with the blade guard  300 . 
     The rear face  225  (see  FIG. 2D ) of the blade holder  200  can include a track  240  for receiving the scalpel handle  500 , preferably the blade receiving portion  550  of the scalpel handle  500 . The track  240  defines lateral movement of the blade cartridge  400  when secured to the scalpel handle  500 . 
     As illustrated in  FIGS. 3A-3E  and  4 , the blade guard  300  is designed to slideably receive the blade  100  and blade holder  200 . When the blade  100  is in the closed position, the blade guard, or blade sheath,  300  adequately surrounds the blade  100 , so that the blade  100  cannot inadvertently cut, puncture, or otherwise damage materials or individuals. 
     There are at least two preferred embodiments of the blade guard  300 . A first embodiment is illustrated in  FIGS. 3A-3B , while a second embodiment is illustrated in  FIGS. 3C-3E . The embodiment selected can depend on the type of scalpel handle  500  used. 
     The blade guard  300  comprises an aperture  320  (also referred to herein as slot  320 ) for providing a track for the holder knob  220  of the blade holder  200  to slide between the closed and open positions. Consequently, as the holder knob  220  moves between retracted and forward positions, the blade  100  moves between the closed and open positions, respectively. More particularly, a directional force applied to the holder knob  220  of the blade holder  200  permits the holder knob  220  to slide along the slot  320  when moving the blade  100  and blade holder  200  between the closed and open positions. 
     The blade guard  300  defines therein a cavity  305 . The blade  100  and blade holder  200  are positioned within the cavity  305  for sliding, when the holder knob  220  slides within the slot  320 . The holder knob  220  is positioned near a proximal end  327  of the slot  320  when the blade  100  is in the closed position and the holder knob  220  is positioned near a distal end  322  of the slot  320  when the blade  100  is in the open position. 
     The blade guard  300  comprises a forward catch  325  and rear catch  330 , such that the forward catch  325  is positioned near the distal end  322  of the slot  320  and the rear catch  330  is positioned near the proximal end  327  of the slot  320 . The forward catch  325  is adapted to engage the holder knob  220  when the blade  100  is in the open position. The forward catch  325  prevents the blade holder  200  from moving the blade  100  forwardly beyond the open position. The forward catch  325  can include a flexible locking member  326  that locks the blade holder  200 , so as to prevent unmistaken unlocking of the blade  100  in the open position. Similarly, the rear catch  330  is adapted to engage the holder knob  220  when the blade  100  is in the closed position. The rear catch  330  can prevent the blade holder  200  from moving the blade  100  rearwardly beyond the closed position. Alternatively, the rear catch  330  prevents the blade holder  200  from moving the blade  100  rearwardly beyond the fully locked position. Further, the rear catch  330  can prevent accidental unlocking of the blade holder  200 , in an attempt to prevent accidents. 
     The blade guard  300  can include a plurality of grooves  340  positioned on the rear face  315  of the blade guard  300 , as illustrated in  FIGS. 3B and 3D . The plurality of grooves  340  can prevent slippage of the safety scalpel  10  during use. 
     The blade guard has a front face  310 , as shown in  FIGS. 3A and 3C , and a back/rear face  315  as shown in  FIGS. 3B ,  3 D, and  3 E. The front faces  310  of the two embodiments are preferably the same. The rear face  315 , however, can have different attributes. 
     A beneficial feature of the differing rear faces  315  includes a method of releasing the blade guard  300 , and consequently the blade cartridge  400  from the scalpel handle  500 . 
     The blade guard  300  of  FIGS. 3C and 3D  further includes a latching assembly  345  for releasing the blade guard  300  from the scalpel handle  500 . The latching assembly  345  includes a knob  350  extending from the rear face  315  of the blade guard  300 , and a locking mechanism  355 . The surface of knob  350  can include ridges  352  for increased traction when in contact with a finger during removal of the blade guard from the scalpel handle  500 . As described more fully below, the knob  350  is adapted to remove the blade cartridge  400  from the scalpel handle  500 . 
     One skilled in the art will recognize that the blade holder  200  and blade guard  300  can be made of a variety of materials including, but not limited to, plastic, such as acrylonitrile-butadiene-styrene (ABS) copolymer plastic. 
     As described above, the blade  100  and blade holder  200  fit into the blade guard  300 . Collectively, these three elements form the blade cartridge  400 . The blade cartridge  400  is attachable to and detachable from a distal end of the scalpel handle  500 . 
     The scalpel handle  500 , as shown in  FIGS. 1A and 1B , comprises a handle portion  540  and a blade receiving portion  550 . The handle portion  540  extends from an approximate midpoint  555  of the scalpel handle  500  to the proximal end  507  of the scalpel handle  500 , while the blade receiving portion  550  extends from the approximate midpoint  555  to the distal end  502  of the scalpel handle  500 . 
     The distal end  502  of the scalpel handle  500  can be cut on the front face  510  to accommodate the blade cartridge  400 . Preferably, the distal end  502  of the scalpel handle  500  can have a tapered portion  504  for improved assembly of the safety scalpel  10 . 
     The scalpel handle  500  comprises at least one extending member  530  on the front face  510  of the proximal end  557  of the blade receiving portion  550 , such as near the approximate midpoint  555 . The extending member  530  extends outwardly from the scalpel handle  500  and is adapted to enable the securing of the blade cartridge  400  to the scalpel handle  500 . 
     That is, the at least one extending member, or medial notch,  530  is adapted to engage at least one catch  335  of the blade cartridge  400  (e.g., catch  335  of the blade guard  300 ). When the blade cartridge  400  is attached to the scalpel handle  500 , the catch  335  of the blade cartridge  400  can engage, or snap about, the extending member  530  to prevent longitudinal movement of the blade cartridge  400 . In addition, lateral movement of the blade cartridge  400  is limited due to the form fitting blade receiving portion  550 . 
     For increased traction of the scalpel handle  500  when in contact with a finger during use of the safety scalpel  10 , the handle portion  550  can include a plurality of grooves  525  positioned on a back face  515  of the scalpel handle  500 , as illustrated in  FIG. 6C . The plurality of grooves  525  can prevent slippage of the safety scalpel  10  during use. 
     As illustrated in  FIGS. 1A ,  1 B,  6 A, and  6 B, the handle portion  550  of the scalpel handle  500  can include indicia  520 . The indicia  520  is generally located on the front face  510  and near the proximal end  507  of the scalpel handle  500 . While one skilled in the art will recognize that the indicia  520  of the present invention can include multiple markings or printings, the indicia  520  are preferably units of measurement such as, but not limited to, the metric system, the Imperial system, or many other appropriate measuring systems. 
     The scalpel handle  500  is designed to accept the blade cartridge  400 , and provide the user with the feel of a conventional scalpel when used. It is thus provided of materials, weight, and design for comfortable use by the user. 
     Assembly of Blade Cartridge  400   
     The blade cartridge  400  includes the fitted cooperation of the blade  100 , the blade holder  200  and the blade guard  300 , as shown in  FIG. 4 . Preferably, the blade cartridge  400  is assembled offsite from where the present safety scalpel  10  is ultimately used, for example, in a factory, such that only the assembled blade cartridge  400  is delivered to the user. Also, the blade  100  can be attached to the blade holder  200  through insert molding, wherein the blade holder  200  is actually formed and molded around the blade  100 . With the use of insert molding, the blade  100  need not be subsequently attached to the blade holder  200 . 
     The blade cartridge  400  can be delivered in its own sterilized wrapping such as, for example, a foil wrap. Thus, the blade cartridge  400  is not intended for the user to assemble, but is intended only for the mating of the blade cartridge  400  with the scalpel handle  500 . 
     As described above, the blade  100  is fixed to the blade holder  200  by aligning the blade aperture  120  with the corresponding holder protrusion  205  of the blade holder  200 . The protrusion notch  215  permits the blade  100  to be secured onto the blade holder  200 , as shown in  FIGS. 2A and 2B . 
     The blade holder  200  with the blade  100  is then attached to the blade guard  300  by sliding and slotting the blade holder  200  into the aperture  305  of the blade guard  300 . This is shown by the arrow in  FIG. 4 . 
     To attach the blade  100  and blade holder  200  into the blade guard  300 , the blade  100  and blade holder  200  are inserted into the blade guard  300 , such that the blade  100  is aligned within the cavity  305  defined by the lateral sides of the blade guard  300  and the holder knob  220  fits into slot  320 . As illustrated in  FIG. 4  (see arrow), the blade holder  200  is slotted into the blade guard  300  such that the stopper rib  230  on the blade holder  200  engages the rear retaining slot  370  of the blade guard  300 . 
     The blade holder  200  and the blade  100  are kept temporarily locked in the blade guard  300  by the holder stopper rib  230  engaging and locking to the matching rear retaining slot  370  on the blade guard  300 . Accordingly, the blade  100  can be kept in the closed position. 
     In the assembled blade cartridge  400 , the blade  100  is wholly enclosed in the blade guard  300  until mounted on the scalpel handle  500  for use. 
     Mounting of Blade Cartridge  400  to Scalpel Handle  500   
     As shown in  FIGS. 1A and 1B , the process of mounting the assembled blade cartridge  400  to the scalpel handle  500  is fairly simple. The distal end  502  of the scalpel handle  500 , i.e., the blade receiving portion  550 , can be inserted into the cavity  305  of the blade cartridge  400 , preferably at the proximal end  307 . Indeed, the blade receiving portion  550  of the scalpel handle  500  can be housed in the track  240  of the rear face  225  of the blade holder  200  to secure the blade cartridge  400  to the scalpel handle  500 . The blade cartridge  400  slides to the point where the catch  335  engages an extending member  530 . 
     The catch  335  of the blade cartridge  400  is arranged to latch around the extending member  530 . Further, the proximal end  307  of the blade cartridge  400  (e.g., proximal end  307  of the blade guard  300 ) is adapted to abut against the approximate midpoint  555  of the scalpel handle  500 , such that the blade cartridge  400  has limited, or no, longitudinal and/or lateral movement.  FIG. 5  illustrates a close up of the blade cartridge  400  secured to the scalpel handle  500 , such that the catch  335  is latched to the extending member  530 . 
     In addition, when the scalpel handle  500  includes an aperture  505 , the blade cartridge  400  can be further secured to the scalpel handle  500 . The blade cartridge  400  (e.g., the blade guard  300 ) can include the latching assembly  345 . The latching assembly  345  includes a locking mechanism  355  that engages the aperture  505  of the rear face the scalpel handle  500 . This engagement further secures the blade cartridge  400  to the scalpel handle  500 . 
     Use of Safety Scalpel  10   
     When first mounted, the blade  100  in the blade cartridge  400  is in the closed position, as illustrated in  FIGS. 6A and 6C . The blade  100  can be extended out of the blade guard  300  by depressing the holder knob  220  of the blade holder  200  (e.g., pushing the holder knob  220  downward) or alternatively simply pushing outward towards the distal end  202  of the blade holder  200 ; releasing the stopper rib  230  on the blade holder  200  from the rear retaining slot  370  on the blade guard  300 ; sliding the holder knob  220  along the slot  320  of the blade guard  300  until the blade  100  reaches the open position, upon which the holder knob  220  is released such that the stopper rib  230  on the blade holder  200  engages the front retaining slot  375  on the blade guard  300 . Thus, the blade  100  is temporarily locked in the open position. When the blade guard  300  engages the front retaining slot  375 , the flexible locking member  326  can be moved outwardly toward an edge of the blade guard  300 , such that it locked. 
     In this open position, as shown in  FIG. 6B , the safety scalpel  10  is ready for use, i.e., cutting and/or slicing. Further, in this position, the blade  100  is prevented from moving laterally and transversally during use of the safety scalpel  10 . 
     The blade cartridge  400  (e.g., the blade guard  300 ) can further comprise a plurality of indentations  380 , as illustrated in  FIGS. 1A ,  3 A, and  3 B. The plurality of indentations  380  are positioned on at least one lateral side/edge of the blade guard  300 , such that the plurality of indentations  380  provide increased grip of the safety scalpel  10  during use. 
     If the user needs to hand the safety scalpel  10  to a colleague, she first moves the blade  100  into the closed position by depressing the holder knob  220  on the blade holder  200  to release the stopper rib  230  from the front retaining slot  375 . Alternatively, she can move the holder knob  220  towards the proximal end  307  of the blade guard  300 . In either case, this causes a sliding of the holder knob  220  back along the slot  320  of the blade guard  300 , until the blade  100  reaches the closed position, upon which the holder knob  220  is released such that the stopper rib  230  on the blade holder  200  re-engages the rear retaining slot  370  on the blade guard  300 . The blade  100  is now temporarily locked in the closed position. The blade  100  can be moved any number of times between the open and closed positions until the operation is completed. 
     Dismounting of Blade Cartridge  400  from Scalpel Handle  500   
     Because there are at least two embodiments of the scalpel handle  500  that can use two different blade guards  300 , there are two different processes of dismounting the blade cartridge  400  (e.g., blade guard  300 ) from the safety handle  500 . 
     In a first embodiment, the blade guard  300  of  FIGS. 3A and 3B  is secured to the scalpel handle  500  of  FIG. 1A . That is, there is no aperture  505  (see  FIG. 1B ). 
     The blade guard  300  in this first embodiment is removed by having the holder knob  220  placed in the rear retaining slot  370 , such that the blade  100  is in the closed position and does not extend from the blade guard  300 . The holder knob  220  can be slid slightly further towards the proximal end  307  of the blade cartridge  400  (e.g., proximal end  307  of the blade guard  300 ), or towards the approximate midpoint  555 . When the holder knob  220  slides in this direction, the catch  335  moves away from the extending member  530  of the scalpel handle  500 . This can release the blade cartridge  400  from the scalpel handle  500 . Then, the user need only slide the entire blade cartridge  400  towards the distal end  502  of the scalpel handle  500 , or off the scalpel handle  500 . 
     In a second embodiment, the scalpel handle  500  includes an aperture  505  in proximity to the extending member  530 , preferably slightly offset towards the distal end  502 . In this embodiment, the blade cartridge  400  (e.g., the blade guard  300 ) further includes the locking mechanism  355  about its rear face  315 . 
     Once the locking mechanism  355  is removed from the aperture  505 , the catch  335  can be released from the extending member  530 , as described above. Then, the blade cartridge  400  is loose enough to be released from the scalpel handle  500 . In essence, the latching assembly  345  is an additional safety feature to help ensure the blade cartridge  400  does not mistakenly release from the scalpel handle. 
     The rear face  315  of the blade cartridge  400  (e.g., the rear face  315  of the blade guard  300 ) matches up with the rear face  515  of the scalpel handle  500 . When the blade cartridge  400  is secured to the scalpel handle  500 , the latching assembly  345  is adapted to engage the aperture  505  of the scalpel handle  500 . The latching assembly  345  includes the knob  350  and the locking mechanism  355 . Because the locking mechanism is an inwardly extending mechanism, it engages the aperture  505  in its normal state. If the knob  350  is depressed, however, the locking mechanism  355  disengages from the aperture  505 . The knob  350  can include a plurality of ridges for increased traction in disengaging the locking mechanism  355  from the aperture  505 . 
     Disposable Safety Scalpel  10   
     In another alternative embodiment of the present invention, the safety scalpel  10  comprises a disposable scalpel handle  500 , such that the disposable scalpel handle  500  is separate and passive from the blade cartridge  400 . The disposable scalpel handle  500  is adapted to attach to the blade cartridge  400 . Preferably, the blade cartridge  400  and the disposable scalpel handle  500  are permanently fixed to each other at the factory during the manufacturing process of the safety scalpel  10 . After use, the blade cartridge  400  and disposable scalpel handle  500  can be properly discarded. 
     One skilled in the art will recognize that the disposable scalpel handle  500  can be made of a variety of materials including, but not limited to, plastic, such as acrylonitrile-butadiene-styrene (ABS) copolymer plastic. 
     In yet another alternative embodiment of the present invention, the safety scalpel  10  comprises a disposable scalpel handle  500  having a slideable blade  100  and blade holder  200  received therein. Accordingly, the blade guard  300  is an integral part of the disposable scalpel handle  500  and, therefore, does not detach from the scalpel handle  500 . Further, the entire safety scalpel  10  is disposable after use. 
     The blade cartridge  400  and scalpel handle  500  can be attached and detached as described above. 
     One skilled in the art will recognize that the scalpel handle  500  (e.g., the entire safety scalpel  10 , minus the blade  100 ) can be made of a variety of materials including, but not limited to, plastic, such as acrylonitrile-butadiene-styrene (ABS) copolymer plastic. 
     While the invention has been disclosed in its preferred forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.