Abstract:
The present invention relates to a disposable surgical safety scalpel with a retractable blade inside a hollow handle with a novel locking and unlocking arrangement that enables easy use and ensures safety in pre-use, use, and post-use conditions.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a disposable surgical safety scalpel. More particularly, the present invention relates to a disposable surgical safety scalpel with a retractable blade inside a hollow handle with a novel locking and unlocking arrangement that enables easy use and ensures safety in pre-use, use, and post-use conditions.  
         BACKGROUND OF THE INVENTION  
         [0002]    Scalpels are widely used in surgery the world over. Surgical scalpels have sharp cutting edges on the blades, which makes them dangerous to use for the surgical team. The potential for accidents when for example the scalpel is being passed back and forth during an operation, is very high. Similarly during post-use, the disposal of the scalpel also poses a problem, in that the slightest negligence during handling in the postoperative time frame can also result in accidents unless extreme care is exercised.  
           [0003]    In recent years, the spread of communicable diseases such as Hepatitis, AIDS and such other diseases makes it important to ensure that safety features are built into the surgical scalpel such that the potential for accidental harm be falling the handler or any person in the vicinity, inadvertently is minimized. A study by Dr. Jannie Jagger in April 1995 on the “Advances in exposure prevention” published by International Health Care Workers and Safety, Research and Resource Center, shows that 34% of scalpel wounds occur during the use of the scalpel in an operative procedure, while 39% occurs when the scalpel is passed from hand to hand during an operation, and the balance 27% when disposal of the scalpel is being effected.  
           [0004]    Hepatitis—B, AIDS and other blood carried diseases all can be communicated during the operative stage. Since detection and treatment of the above diseases is not possible at the time that a scalpel used accidentally cuts or nicks a person, the normal presumption is that all the persons who are involved in an operative procedure are exposed to risk of infection. Additionally, to ensure that injury is not caused during the disposal stage of the scalpel, it must be ensured that the blade is suitably inaccessible and protected such that the disposal of the scalpel is made free of the potential for injury.  
           [0005]    Several methods are provided in the art to ensure that the scalpel during all of pre-use, use and post-use conditions is safe and does not cause accidental harm to the handler.  
           [0006]    In the art, surgical scalpels have been provided with a blade shield or guard in order to ensure that the safe packaging of the product and thus its sterility is maintained. But the solution does not take care of the problem in the use and post operative stage.  
           [0007]    U.S. Pat. No. 2,735,176 discloses a surgical knife that is provided with a hollow handle which functions as a sheath for the blade that is extendable slidingly and retractable between a first cutting position and a second shielded position. Movement of the blade requires the surgeon to positively act to at least rearrange the handle in his/her hand. In some embodiments, it requires a two-handed actuation of the shield to ensure that the blade is properly sheathed before transfer to another person. Another disadvantage of the sheath system for surgical knives is that they require complex locking and retraction mechanisms. Such mechanisms often prove to be extremely fragile and expensive to incorporate resulting in an increase in cost of manufacture. The increased cost of manufacture of such scalpels renders the disposal factor not very attractive for the user. Similar to the scalpel disclosed in the above patent, U.S. Pat. Nos. 3,905,101 and 3,906,626 disclose sheaths wherein the handle carrying the blade is slideble from a first protective position to a second cutting position and vice versa. However, to initiate the sliding action, two-handed actuation is required rendering the instrument user unfriendly.  
         OBJECTS OF THE INVENTION  
         [0008]    The main object of the present invention is to provide a disposable safety scalpel wherein the blade is protected from exposure during pre- and post-use conditions.  
           [0009]    It is another object of the present invention to provide a disposable safety scalpel where bringing the cutting edge of the blade into the operational mode requires a specific actuation by the user.  
           [0010]    It is another object of the present invention to provide a disposable safety scalpel with a retractable blade that is user friendly and with a firm locking arrangement to ensure safety in handling during operative stage.  
           [0011]    It is another object of the present invention to provide a disposable safety scalpel where the potential for pre- and post-operative accidental injury to the user or to other persons in the vicinity are completely eliminated or substantially minimized.  
           [0012]    It is a further object of the invention to provide a disposable safety scalpel with a permanent locking mechanism in the post use stage to ensure total or at least substantial safety in disposal of the scalpel post—use.  
         SUMMARY OF THE INVENTION  
         [0013]    Accordingly, the present invention provides a disposable safety scalpel comprising a housing with a proximal open end to enable sliding in and out of the blade carrier to expose the cutting edge of the scalpel blade and a distal closed end, a blade carrier slideably provided in such housing, said blade carrier being provided with a scalpel blade fixedly located on one end thereof, the other end of the blade carrier being provided with a plurality of locking means to enable locking of the blade in three positions of pre-use, actual use and post use disposal stage, said blade carrier also being provided with a sliding means to enable movement of the blade carrier within the housing, the housing being provided with lock cooperating mechanisms at three positions thereon corresponding to pre-use, use and post-use disposal stages, said lock cooperating mechanisms cooperating with the respective locking means provided on said blade carrier during use.  
           [0014]    In one embodiment of the invention, the blade carrier is provided with actuating means to enable positive movement of the blade carrier from a first pre-use stage to an actual use stage and finally to a post-use disposal stage.  
           [0015]    In another embodiment of the invention, the first locking mechanism for the pre-use stage comprises of at least one lug provided on the blade carrier and cooperating with a depression provided on said housing to ensure pass locking.  
           [0016]    In another embodiment of the invention, the second in-use locking mechanism comprises of at least a pair of matched arms extending in the longitudinal direction from the end of the blade carrier opposite the blade end and provided with lugs cooperating with a corresponding second pair of slots provided in the flange on said housing, said pair of slots being adapted to receive the lugs on said arms and retain them therein permanently till actual release by the user.  
           [0017]    In a further embodiment of the invention, the second in-use locking mechanism is provided with an actuating means to enable release of the blade carrier from the use position to the pass position by natural action of retraction.  
           [0018]    In a further embodiment of the invention, the third arm provided on the said blade carrier to ensure permanent locking of the blade by wedge locking it to the end piece in the post use disposal stage.  
           [0019]    In another embodiment of the invention, the housing is provided with a groove running on one side thereon to enable sliding movement of the blade carrier thereon from a pass position to a in use position as required during operation, and to a third permanent locking position for the post-use disposal stage.  
           [0020]    In another embodiment of the invention, the blade carrier is provided with a actuating means to enable movement of the blade carrier from the pass to in use stage and finally to a post-use disposal stage.  
           [0021]    In a further embodiment of the invention, the actuating means provided on said blade carrier comprises a knob.  
           [0022]    In another embodiment of the invention, the slots on the housing are adapted to receive the said second locking mechanism and the third locking mechanism are provided respectively on opposite sides of the housing.  
           [0023]    In another embodiment of the invention, the notches on the housing are adapted to receive the said first locking mechanism and the second locking mechanism are provided respectively on the same side of the housing.  
           [0024]    In a further embodiment of the invention, the knob and the mechanisms are integral enabling movement of the blade carrier and locking simultaneously. 
       
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0025]    [0025]FIG. 1 is an isometric view of the disposable safety scalpel of the invention with the blade shown in a cutting position.  
         [0026]    [0026]FIG. 2 is a schematic representation of the housing with the groove shown to enable the carrier to slide. The housing has a bottom, two side walls and two flanges at the top showing the in use locking position and a groove between the flanges for actuating the knob for the lateral movement of the carrier.  
         [0027]    [0027]FIG. 3 is a schematic representation of the blade carrier without the blade showing the different locking means provided thereon.  
         [0028]    [0028]FIG. 4 is a schematic representation of the knob provided on the blade carrier with the respective locking means for pass and in use stages shown thereon.  
         [0029]    [0029]FIG. 5 is a schematic representation of the rear end stopper provided on the housing showing tapper wedge for disposable locking.  
         [0030]    [0030]FIG. 6 is a schematic representation of the blade carrier with the knob and the locking means being integral inter se. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    In the operating room, surgical scalpels are often transferred back and forth between the operating surgeon and the other personnel assisting in the operation. The transfer of instruments during surgery is often dictated by considerations of speed. As such, the use of scalpels during surgery often result in cuts and nicks due to the rapid transfer from one person to another. The spread of communicable diseases such as Hepatitis and AIDS and other blood carried diseases has rendered the operation theater fraught with risk for the operating personnel. It is therefore important to devise instruments, which avoid or at least minimize substantially the risk of operating room personnel being infected with communicable diseases due to accidental injuries suffered during the course of operation.  
         [0032]    Simlarly, after the completion of the surgical procedures, it has now become mandatory whether by way of statutory regulations or in house policies of most hospitals to dispose of instruments such as scalpels which are invasive and have come into direct contact with the patient. Disposal of such instruments such as scalpels poses a problem due to the sharp cutting edge of the blade. Disposal therefore inevitably requires tremendous safety precautions and it is not unknown for accidental cuts and nicks to occur during disposal of such instruments to the persons handling such equipment.  
         [0033]    The present invention is a disposable safety scalpel with a retractable blade and a novel locking mechanism. The invention will be described in detail below with reference to the accompanying drawings.  
         [0034]    Referring now to FIG. 1, an isometric view of the disposable safety scalpel according to the invention is shown with the blade being displayed in a cutting or operating position.  
         [0035]    The housing ( 1 ) is provided with a groove ( 3 ) which holds the blade carrier ( 2 ). The blade carrier ( 2 ) is provided with a knob ( 4 ) which is slideable in the groove ( 3 ) from a first in use position ( 5 ) to a second pass position ( 6 ) and after use to a final disposal position ( 7 ) where the blade is permanently locked. The blade carrier ( 2 ) is also provided with a first locking means ( 8 ) to ensure locking of the blade carrier in the housing in the in use position ( 5 ), a second locking means ( 9 ) to ensure locking in the pass position ( 6 ). A third locking means ( 10 ) is provided on said blade carrier ( 2 ) to ensure permanent locking of the blade carrier( 2 ) with the blade( 11 ) in a retracted position (not shown) when the scalpel is ready for disposal. As a result of the permanent disposal locking position, the safety of handlers during disposal is ensured. Similarly, the easy locking transfer between the pass position and the in use position ensures that transfer of the scalpel during operation does not result in any accidental nick or cut to the user or handler.  
         [0036]    [0036]FIG. 2 is a schematic representation of the housing with the different locking positions indicated thereon. The housing ( 21 ) is provided with a first pair of slots( 22 ) to enable locking of the blade carrier (not shown) in a first in use position. Since the slots ( 22 ) are engaged in a relatively rigid manner by the corresponding lugs provided on the blade carrier, the actual positive force required to be applied by the user will not cause unlocking of the blade carrier from the first in use position to the second pass position. This ensures that the blade carrier remains in a rigid position in actual use and the potential of the accidental retraction during surgery is avoided. The release of the in use locks by the natural forces of retraction necessary to bring the carrier to the past position. At each stage of the surgical procedure requiring the use of the scalpel, the blade carrier can be retracted to a pass position ( 23 ) where a releasable locking means is provided. This ensures the safety of those assisting personnel who handle the scalpel after the completion of the specific surgical maneuver. After the completion of the entire surgical procedure, the blade carrier can be retracted to a third and final locking position comprising a slot ( 24 ) provided in the end stopper( 21 ). This permanent locking ensures that the potential for accidental nicks and cuts during post operative disposal of used surgical instruments is avoided  
         [0037]    [0037]FIG. 3 is a schematic representation of the blade carrier without the blade showing the different locking means provided thereon. The first locking means ( 32 ) cooperates with a corresponding pair of slots provided on the housing (see FIG. 2) to ensure a rigid locking during in use position for the blade carrier. This ensures that accidental retraction of the blade during actual surgical maneuver does not occur. However, the blade can be retracted from the first in use position by direct application of force on an actuator comprising a knob ( 34 ) to release the first locking means from the corresponding slots provided on the housing. The blade then retracts into the pass position and stay locked therein due to the second locking means( 33 ) provided on the blade carrier. Since the second locking means is releasable, the scalpel can be reused during the same surgical procedure by simply pushing the knob to move in the groove provided on the housing (not shown) to push the blade into a first in use position. After final completion of the surgical procedure, the blade carrier is pushed back to a final permanent locking position where a third locking means ( 35 ) provided on the blade carrier engage a notch on the housing to ensure permanent locking. In this final stop position, the blade carrier cannot be released accidentally, thereby ensuring complete safety of the operator.  
         [0038]    [0038]FIG. 4 is a schematic representation of the knob provided on the blade carrier with the respective locking means for safe, in use and post use stages shown thereon. The knob is used for exposing and retracting the blade as required. The in use lock are pressed into the slots provided in the two flanges of the housing. During in use position, the lock components engage two slots provided on the housing and the elasticity of the plastic carrier spring ensures firm locking during this position. The firm locking and the closed tolerance between the hollow handle and the slideable carrier provide stability to the blade during the surgical procedure. After use, the blade can be retracted. The movement of the knob in the groove provided on the housing first releases the in use lock by downward pressure. The knob is provided with two pads for the specific application of pressure in a downward direction on the first locking means to ensure their release. Further retraction of the blade after release from the in use position brings the blade carrier to a second pass position where the locking means is a releasable locking means. If the scalpel is required again during the surgical procedure, the blade carrier can simply be extended to the in use position where the first locking means operates as described above. If the scalpel is not required any longer, the blade carrier can simply be retracted by actuation using the knob to a final stop position where the third locking means acts to ensure permanent locking of the blade carrier. At this stage, the scalpel is ready for disposal with no risk of any accidental injury. In one embodiment the knob and the locking means are integral inter se (see FIG. 6).  
         [0039]    [0039]FIG. 5 is a schematic representation of the rear end stopper provided on the housing to ensure disposable locking. The operation of the rear end stopper is to ensure a permanent locking of the blade carrier after completion of the surgical procedure where the blade is ready for disposal.  
         [0040]    [0040]FIG. 6 is a schematic representation of the blade carrier with the knob and the locking means being integral inter se. The blade carrier ( 61 ) is provided with the knob ( 62 ) located centrally on the flat portion thereon. The knob functions to push the blade carrier between the various operative and non-operative (pass and dispose-off positions) on the application of an actuating force by the user. The locking at the various positions (operative, pass, and dispose-off) is provided with respective locking means ( 63 ,  64  and  65  respectively).  
         [0041]    The embodiments described above are illustrative and various modifications are possible within the scope and spirit of the invention. The figures describe specific preferred embodiments and should not be construed as limiting the scope of the invention in any manner.