Abstract:
A safety surgical knife has a blade guard and a knife blade holder. The knife blade is covered when the guard is extended to protect it. When the blade is extended to its full operating position the guard is simultaneously retracted. When the blade is retracted the guard is simultaneously extended to return to its protective position. A shaped knife handle acts as an orientation guide and an anti-roll prop keeps the knife from rolling over when placed on a flat surface.

Description:
[0001]    The present invention is a continuation-in-part of, and claims priority from, U.S. Provisional Patent Application Ser. No. 61/326,225, filed 21 Apr. 2010 and entitled “Safety Knife With Retractable Blade and Guard”, the entirety of which is hereby incorporated herein by reference. 
     
    
       [0002]    The present invention relates to knives used for surgery and, in particular, a safety surgical knife having a blade guard and a knife blade holder. The knife blade is covered when the guard is extended to protect it. When the blade is extended to its full operating position the guard is simultaneously retracted. When the blade is retracted the guard is simultaneously extended to return to its protective position. 
       BACKGROUND OF THE INVENTION 
       [0003]    Knives and scalpels used in ophthalmic surgery have small, extremely sharp blades. During eye surgery it is desirable to make the incisions as small as possible to allow for faster healing and to obviate the need for stitching the incision closed after surgery has been completed. 
         [0004]    Surgical instruments are typically arranged by a surgical assistant and passed to the surgeon as needed. When the surgeon is finished using a particular instrument, it is customary for the surgeon to pass the instrument back to the assistant who then retains it for further use or, if use is completed, disposes of the instrument. 
         [0005]    Operating in as confined a surgical field as the eye requires dexterity, concentration and, often, the use of microscopes or other magnifying devices to allow the surgeon to more clearly visualize the eye tissue. A constant concern during surgical procedures is the accidental cutting of either the surgeon or the assistant by an exposed cutting blade. Accidental cutting may cause serious injury and will also require that the person cut be regloved before surgery can continue. 
         [0006]    It is known to provide scalpels and knives with blade covers or blade guards to protect the blade itself prior to surgery and to protect the blade users during surgery. Examples of such blade guards are found in the prior art. 
         [0007]    U.S. Pat. No. 7,022,128 (Morawsky) teaches and describes a surgical knife safety handle having a blade guard that can be extended from and retracted into the handle. 
         [0008]    U.S. Pat. No. D496,730 (Morawsky et al) teaches and describes an ornamental design for surgical knife safety handle corresponding to the knife described and claimed in the &#39;128 patent. 
         [0009]    U.S. Pat. No. 6,626,925 (Newman et al) teaches and describes a shielded surgical scalpel having an extendable and retractable blade guard. 
         [0010]    A common drawback to the designs shown in the aforementioned references is the necessity for the surgeon to maintain either an uncomfortable hand position during retraction and extension of the guard, or the need for the surgeon to grip the knife in a first position to operate the blade guard, then change grips, or “walk the handle” to use the knife to make incisions. Repositioning the surgeon&#39;s hand after retracting the guard often means that the surgeon&#39;s attention and concentration is diverted from the operating field to the knife itself. 
         [0011]    It is good surgical procedure to have the guard in place when the knife is passed back and forth between the assistant and the surgeon. Prior knife designs tend to require the surgeon&#39;s hand to be repositioned to extend the guard after the surgeon&#39;s use of the knife is completed before passing the knife back to the surgical assistant. 
         [0012]    Commonly, the assistant already has the next instrument to be used in one hand ready to pass to the surgeon, while receiving the used instrument in the other hand. It would be awkward and dangerous for the surgical assistant to take a knife with the guard retracted and use a single hand to extend the guard before disposing of the knife. 
         [0013]    Prior art safety handle designs thus make the extension and retraction of the guard awkward and uncomfortable by requiring repositioning of the user&#39;s hand to extend and retract the guard. 
         [0014]    The present invention provides a safety knife with a knife blade guard that can be extended to protect the blade and retracted to expose the blade with limited repositioning of the user&#39;s hand When the guard is extended, the blade is simultaneously retracted so that no portion of the blade extends past the guard. When the guard is retracted, the blade is extended to its full operative position. 
         [0015]    The present invention also provides a safety knife designed to allow the movement of both the guard and blade with a single actuator. 
         [0016]    The present design also provides a guard which allows the blade to be fully observed when the guard is in the extended position and the blade is in the retracted position. 
         [0017]    The present invention also provides a safety knife which is economical to manufacture and simple to use. 
         [0018]    While the following describes a preferred embodiment or embodiments of the present invention, it is to be understood that this description is made by way of example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates and, while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims such language is intended to cover the structures described herein as performing the recited functions and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    These and further aspects of the present invention will best be appreciated upon considering the accompanying drawing wherein: 
           [0020]      FIG. 1  is a perspective view of a surgical safety knife embodying certain principles of the present invention, shown with the blade guard extended and the blade partially retracted; 
           [0021]      FIG. 2  is an enlarged view of the tip of the knife shown in  FIG. 1  with the guard extended; 
           [0022]      FIG. 3  is a view of  FIG. 2  with the guard retracted and the blade fully extended; 
           [0023]      FIG. 4  is a partial lateral sectional view of the knife of  FIG. 1  with the guard extended and the blade retracted; 
           [0024]      FIG. 5  is a partial lateral sectional view of the knife of  FIG. 1  showing the guard retracted and the blade extended; 
           [0025]      FIG. 6  is a perspective view of the guard carriage, lower housing and pivot pin disassembled from the knife of  FIG. 1 ; 
           [0026]      FIG. 7  is a perspective view of the guard carriage; 
           [0027]      FIG. 8  is a perspective view of the knife carriage; 
           [0028]      FIG. 9  is a perspective view of the pivot pin; 
           [0029]      FIG. 10  is a partial sectional perspective view showing the pivot pin mounted to the upper handle; 
           [0030]      FIG. 11  is a partial lateral view showing the assembly of the upper and lower handles together with the blade carriage pivot pin and guard carriage; 
           [0031]      FIG. 12  is a perspective view of the blade carriage; 
           [0032]      FIG. 13  is a perspective view of another embodiment of the invention with the blade guard retracted and the blade extended; 
           [0033]      FIG. 14  is a perspective view of the guard of the device shown in  FIG. 13 ; 
           [0034]      FIG. 15  is a perspective view of the blade carriage of the device shown in  FIG. 13 ; 
           [0035]      FIG. 16  is a partial sectional view of the device shown in  FIG. 13 ; 
           [0036]      FIG. 17  is a partial perspective view of the device of  FIG. 13  with the blade extended and the guard retracted; 
           [0037]      FIG. 18  is a partial lateral section along line  18 - 18  of  FIG. 17 ; 
           [0038]      FIG. 19  is a sectional view taken along  19 - 19  of  FIG. 13 ; and 
           [0039]      FIG. 20  is a lateral elevational view showing a handle prop. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    Referring now to  FIG. 1 , the numeral  10  identifies a surgical safety knife having a handle  12  with a proximal end  14  and a distal end  16 . A blade guard  18  extends from distal end  16  of handle  12  and is preferably sized and shaped to surround and protect a surgical blade  20  which also extends from distal end  16 . 
         [0041]    Referring now to  FIG. 2 , an enlarged detail is shown of distal end  16 . Preferably guard  18  is formed from a transparent plastic to allow blade  20  to be viewed when guard  18  is extended. This allows the surgeon to identify the type and orientation of blade  20 . An actuator  22  is shown slidably mounted to handle  12  in a manner to be described hereinbelow. In  FIG. 2 , actuator  22  is shown in its rearmost or retracted position and it is in this position that guard  18  is extended and blade  20  is retracted. 
         [0042]    Referring now to  FIG. 3 , actuator  22  is shown in its forwardmost or extended position. In this position, guard  18  is retracted into handle  12  and blade  20  is fully extended from handle  12  at distal end  16  to its operating position. 
         [0043]    Referring now to  FIG. 4 , a partial lateral sectional view of knife  10  is shown with guard  18  in its extended position. As seen in  FIG. 4 , handle  12  is hollow and slidably accommodates a guard carriage and needle carriage to be described hereinbelow. 
         [0044]    Referring to  FIGS. 4 and 8 , actuator  22  is formed as part of a knife carriage  24 . Blade  20  is formed as part of blade shaft  26  and is secured to blade carriage  24  at blade mount  28 . Front and rear carriage guides  30 ,  32 , formed as opposed pairs on knife carriage  24  and are received in slots  34 ,  36  formed on the interior of handle  12  as seen in  FIG. 12 . The combination of guides  30 ,  32  and slots  34 ,  36  constrain knife carriage  24  to slide in a straight line longitudinally within handle  12 . 
         [0045]    As seen in  FIG. 8 , actuator  22  is formed as an integral part of knife carriage  24  and includes a finger grip  38  extending from an upstanding actuator body portion  40 . Body portion  40  is, in turn, integrally attached to a tongue  42  which extends from knife carriage  24  at living hinge  44 . As can be appreciated from viewing  FIG. 8 , when finger grip  38  is pushed downward, tongue  42  flexes to bend about hinge  44 . Front and rear stops  46 ,  48  extend upwardly from tongue  42 . 
         [0046]    As seen in  FIG. 2 , a retainer slot  50  is formed in handle  12 , rearward of actuator  22 . As seen in  FIG. 4 , when knife carriage  24  is positioned to fold blade  20  in its retracted position, front stop  46  engages retainer slot  50 , keeping knife carriage  24  from being moved. 
         [0047]    Referring now to  FIG. 5 , blade  20  is shown in its extended position and it can be seen that carriage  24  has been moved in a forward direction to engage rear stop  48  with retainer slot  50 , also keeping knife carriage  24  from being moved. 
         [0048]    Referring now to  FIGS. 2 and 3 , an actuator guide slot  52  is shown formed in the uppermost surface of handle  12 . As seen in  FIGS. 2 and 3 , finger grip  38  of actuator  22  protrudes from and is carried within slot  52 . In  FIG. 2 , finger grip  38  is shown at the rearmost end of slot  52  with knife carriage  24  moved rearward and knife blade  20  shown in its retracted position. In  FIG. 3 , knife blade  20  is shown in its fully extended position with finger grip of actuator  22  positioned at the forwardmost end of slot  52 . 
         [0049]    In order to move knife carriage  24  longitudinally within handle  12 , finger grip  38  must be depressed, bending tongue  42  at hinge  44  to disengage stops  46 ,  48  from slot  50 . As an example, in  FIG. 4 , in order to move knife carriage  24  in a forward direction to extend blade  20 , finger grip  38  is depressed or pushed downward to disengage stop  46  from slot  50 . Thereafter, finger grip  38  is urged forward along slot  52  until rear stop  48  engages slot  50 . In this manner, knife carriage  24  is held in positive engagement with handle  12  when knife  20  is in its fully extended or fully retracted position. Referring now to  FIGS. 6 and 7 , a guard carriage  54 , blade guard  18  is formed as part of guard carriage  54  at the forward end thereof. As seen in  FIG. 6 , guard carriage  54  is slidably received in the lower half  56  of handle  12 . In one embodiment, guard carriage  54  is formed with a pair of opposed flat sides  58 ,  60  received between and guided by forward guide tabs  62  and rear guide tabs  64 . In this manner, guard carriage  54  is slidable longitudinally within handle  12  and is prevented from rotating. 
         [0050]    As seen in  FIGS. 6 and 9 , a pivot post  66  is positioned within handle  12  and engages guard carriage  54 . 
         [0051]    As best seen in  FIG. 9 , pivot post  66  has a central shaft  68  from which upper arm  70  and lower arm  72  extend. At one end of pivot shaft  68 , a cylindrical bearing  74  is formed while a similar bearing  76  is formed at the opposite end of pivot shaft  68 . Upper arm  70  terminates at a pivot tag  78  while lower arm  72  terminates at a similarly-shaped lower pivot peg  80 . In the embodiment shown, upper and lower pivot peg  78 ,  80  are generally cylindrical in shape and are formed as part of upper and lower arms  70 ,  72 , respectively. 
         [0052]    Referring now to  FIG. 10 , pivot post  68  is seen mounted to handle  12  with pivot bearings  74 ,  76  rotatably received and, respectively, right socket  82  and left socket  84 . In the embodiment shown, bearings  74 ,  76  are formed as cylindrical projections from pivot shaft  68  and sockets  82 ,  84  are formed with a corresponding cylindrical shape, whereby pivot shaft  68  is free to rotate within handle  12 . 
         [0053]    Referring now to  FIGS. 4 and 8 , pivot post  66  is seen installed within handle  12  with upper peg  78  engaging actuator slots  86  formed on knife carriage  24 . A set of guide posts  88  extend upward from slot  86  and are received by handle housing  90  formed as a part of handle  12 . 
         [0054]    Referring now to  FIGS. 4 and 7 , a guard carriage actuator slot  92  is formed rearward of guard  18  and is surrounded by a set of posts  94 . As seen in  FIG. 4 , posts  94  are received in lower handle housing  96 . 
         [0055]    As seen in  FIGS. 4 and 5 , upper peg  78  of pivot post  66  is sized and shaped to engage knife carriage actuator slot  86  while, at the same time, lower peg  80  of pivot post  66  is sized and shaped and positioned to engage guard carriage actuator slot  92 . 
         [0056]    The positioning of pivot post  86  with upper and lower arms  70 ,  72  and upper and lower peg  78 ,  80  within upper handle housing  90  and lower handle housing  96  is shown with both knife carriage  24  and guard carriage  54  removed. It can be seen that as pivot post  66  is rotated about pivot bearings  74 ,  76 , upper peg  78  and lower peg  80  move within upper and lower housings  90 ,  96 , respectively. It can also be seen from  FIG. 4  and  FIG. 5  that the movement of pivot post  66  within upper and lower housings  90 ,  96  is also limited by the engagement and disengagement of front and rear stops  46 ,  48  with retainer slot  50 . 
         [0057]    Operation of the features of knife  10  can now be described. As seen in  FIG. 4 , when blade  20  is in its retracted position, guard  18  is in its extended position. Blade  20  moves, responsive to the movement of blade carriage  24  while guard  18  moves responsive to the movement of guard carriage  54 . When, as seen in  FIG. 4 , finger grip  38  is depressed to disengage forward stop  46  from retainer slot  50  and is then moved forward along slot  52 , knife carriage  24  engages upper peg  78  in actuator slot  86  and causes pivot post  66  to rotate about pivot shaft  68 . 
         [0058]    Lower peg  80  is engaged within guard carriage actuator slot  92  and, as upper peg  78  rotates in the direction of extending blade  20 , peg  80  is rotated in the direction of retracting guard carriage  54 , thereby moving guard  18  rearwardly into distal end  16  of handle  12 . 
         [0059]    As seen in  FIG. 5 , when rear stop  48  is engaged with retainer slot  50 , peg  80  has moved guard carriage  54  to its rearmost position. At the same time, knife carriage  24  is at its forwardmost position allowing blade  20  to extend fully outwardly from distal end  16  of handle  12 . 
         [0060]    In use, when knife  10  is presented with guard  18  fully extended, blade  20  is covered but can be viewed through the transparent material used to form guard  18  so the surgeon can identify the type and orientation of the knife blade. When finger grip  38  is depressed front stop  48  is disengaged from slot  50  and knife carriage  24  is moved forward until rear stop  48  engages retainer slot  50 . In this position, guard  18  is retracted and knife  20  has been moved forward responsive to the motion of knife carriage  24  to place blade  20  in an operative position for surgery. When the knife is no longer needed, the surgeon pushes down on finger grip  38  to disengage rear stop  48  from slot  50  and moves finger grip  38  along slot  52  until front stop  46  engages slot  50 . 
         [0061]    Referring now to  FIG. 13  the numeral  98  identifies a knife comprising an additional embodiment of the present invention. 
         [0062]    Knife  98  has a handle  100 , which has a proximal end  102  and a distal end  104 . A blade guard  106  extends from distal end  104  of handle  100  and is preferably sized and shaped to surround and protect a surgical blade  108  which also extends from distal end  102 . 
         [0063]    Referring now to  FIG. 14 , it can be seen that guard  106  is formed as an integral portion of guard carriage  110 . In the embodiment shown, guard  106  is formed as an arch  112  having a pair of depending legs  114 ,  116  joined to carriage  110 . As described hereivabove, guard  106  can be formed from a transparent material to allow blade  108  to be seen when guard  106  is extended to cover blade  108 . 
         [0064]    Referring now to  FIG. 15  the numeral  118  identifies a combined blade carriage and actuator having a blade mount  120  fashioned at one end thereof adapted to receive and hold blade  108 . Carriage  118  has a body  122  on which is formed an actuator tongue  124  which is partially severed from body  122  along a tongue slot  126 . The material from which carriage  118  is fashioned allows tongue  124  to flex with respect to body  122  at a living hinge  128 . An actuator button  130  is formed on tongue  124  to effect such flexing action when desired. A locking tab  132  is formed at end  134  of tongue  124 , it being understood that end  134  is free to move responsive to the motion of actuator button  130 . 
         [0065]    Referring now to  FIG. 16 , a portion of handle  100  is shown within which carriage  118  is slidably received. It should be understood that the mechanism by which carriage  118  and guard  106  are retracted and extended is substantially as described earlier with respect to  FIGS. 4-12 . 
         [0066]    As seen in  FIG. 16 , a longitudinally-extending actuator slot  136  is formed through wall  138  of handle  100 , through which actuator button  130  extends when carriage  118  is inserted into handle  100 . A locking slot  140  is formed through wall  138  intermediate slot  136  and handle end  104 . When in the guarded position, with guard  106  covering blade  108 , locking tab  132  is engaged in locking slot  140 , preventing movement of carriage  118 . Engagement of locking tab  132  in slot  140  is also shown in  FIG. 13 . 
         [0067]    In order to move guard  106  and blade  108  to the open, or unguarded position, locking tab  132  must be disengaged from slot  140  to allow actuator button  130  to be moved along slot  136 . This is accomplished by pushing down on actuator button  130  until tongue  124  is bent downward sufficiently to move tab  132  clear of slot  140 . Actuator button  130  can then be moved longitudinally along slot  136  toward handle end  104 , responsive to which guard  106  is retracted as blade  108  is extended. 
         [0068]    Referring now to  FIG. 17  an enlarged, partial perspective view of knife  98  is shown with guard  106  fully retracted and blade  108  fully extended. As seen, actuator button  130  is positioned within that portion of slot  136  closest to handle end  104 . 
         [0069]    As further seen in  FIG. 17 , a mouth  142  is defined by handle end  104 , and mouth  142  includes a bight  144  extending generally in an arc about the upper surface of handle  100 . It is a feature of this embodiment that when actuator button  130  is moved forward in slot  136 , carriage  118  is responsively moved forward a sufficient distance to allow locking tab  132  to extend upward to engage bight  144 . This action locks carriage  118  and, thereby, blade  108  in an exposed position for use in surgery. 
         [0070]    Referring to  FIG. 18 , blade  108  is shown in its locked and extended position, with actuator button  130  moved forward in slot  136  sufficiently to move carriage  118  to allow locking tab  132  to engage bight  144 . To retract blade  108  and extend guard  106 , actuator button  130  is depressed a sufficient distance to disengage locking tab  132  from bight  144 , allowing carriage  118  to slide rearward responsive to the rearward motion of actuator button  142 . It is anticipated that the positioning of actuator button  130  on handle  100  will allow most users to extend and retract blade  108  without having to reposition the user&#39;s hand on knife  98 . 
         [0071]    Referring again to  FIG. 13 , handle  100  is shown having a flattened later surface portion  146  positioned where a user would grip handle  100 . As seen in  FIG. 19 , a cross-section of handle  100  shows a corresponding flattened surface portion  148  positioned opposite portion  146 . Flattened portions  146 ,  148  form a grip and a guide to the orientation of blade  108 . When a user&#39;s hand engages flats  146 ,  148  with actuator button  130  facing upward, knife  98  is then held in a position to place blade  108  in its operative position. Each time a user grips flats  146 ,  148  as described, the user knows that blade  108  is facing in its operative position. 
         [0072]      FIG. 19  also depicts the placement of a handle prop  150  at the proximal end of handle  100  to act as a support and to keep handle  100  from rolling over from its upright position. 
         [0073]      FIG. 20  shows a preferred placement of prop  150  in relation to the proximal end  106  of handle  100 . Prop  150  may be permanently deployed or may be adapted to be removed from or inserted into handle  100  when not in use. 
         [0074]    Thus, when blades  20 ,  108  are in their fully extended position, they are locked in place and cannot be inadvertently moved rearward. In similar fashion, when blade  20  is moved rearward to re-engage front stop  46  with retainer slot  50 , guard  18  is locked in place in its fully extended position and blade  20  has been retracted sufficiently to position it wholly within guard  18 , and when blade  108  is moved rearward, locking tab  132  re-engages locking slot  140  to do the same. 
         [0075]    Because they are locked in place, guards  18 ,  106  cannot be easily accidently moved rearward to expose blades  20 ,  108 . 
         [0076]    In this manner, knives  10 ,  98  may be used several times during a single surgery with their respective guards being extended and blades being retracted between uses to protect against damage to the blade and accidental cuts.