Abstract:
A surgical knife may include a handle and a blade embedded in the handle. The handle may have a tissue-displacing member surrounding the blade.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61417577 filed Nov. 29, 2010. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to instruments for performing medical procedures and more particularly to surgical knives for making incisions. 
         [0003]    When making an incision in a tissue layer such as a peritoneum or dural layer, there is a risk that a knife or scalpel blade may cause damage to underlying organs or tissue. In order to mitigate such risk, a practitioner must exercise great care to control a depth of cut during the process of making an incision. The practitioner must apply only enough pressure on a knife to cause the knife to penetrate and cut the layer of interest. Thus the practitioner may be required to not only guide the knife laterally in a desired direction, but he or she must also provide an appropriate vertical force that counterbalances weight of the knife and cutting force needed to penetrate the layer of interest while simultaneously avoiding injury to underlying organs or other tissue. 
         [0004]    As can be seen, there is a need for a method and an instrument for making incisions that may reduce the risk of causing injury to underlying organs or tissue when making an incision. 
       SUMMARY OF THE INVENTION 
       [0005]    In one aspect of the present invention, a surgical knife may comprise a handle; and a blade embedded in the handle, the handle having a tissue-displacing member surrounding the blade. 
         [0006]    In another aspect of the present invention, a method of making an incision in a tissue layer may comprise the steps of: positioning a blade of a knife in an incision plane with a rounded tip of a tissue-displacing member of the knife projecting below the incision plane; pressing on the knife to cause the tissue-displacing member to displace underlying tissue away from the incision plane and the tissue layer that is to be cut; and passing the blade through the tissue layer that is to be cut while maintaining downward pressure on the knife to maintain the tissue-displacing member against the underlying tissue to displace the underlying tissue from the incision plane. 
         [0007]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a surgical knife in use in accordance with an embodiment of the invention; 
           [0009]      FIGS. 2 ,  3  and  4  are perspective views of the knife of  FIG. 1 ; 
           [0010]      FIG. 5  is an elevation view of the knife of  FIG. 1 ; 
           [0011]      FIG. 6  is a cross-sectional view of the knife of  FIG. 1  taken along the lines  6 - 6  of  FIG. 5 ; and 
           [0012]      FIG. 7  is a partial cross-sectional view of the knife of  FIG. 1  showing an operational feature of the knife. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0014]    Various inventive features are described below that can each be used independently of one another or in combination with other features. 
         [0015]    Broadly, embodiments of the present invention generally provide a method and instrument for making surgical incisions through a tissue layer while holding underlying tissue away from an incision plane. 
         [0016]    Referring to the Figures various views are shown of an exemplary embodiment of a surgical knife  10 . The knife  10  may comprise a blade  18  with a blade cutting edge  20  and a handle  22  with handle grip ribs  24 , a logo area  26 , a blade recess  28 , a tissue-displacing member  30  and a concave arc-shaped notch  32 . The blade  18  may be a conventional scalpel blade that may have a curved or a straight cutting edge  20 . The blade  18  may be positioned in the arc-shaped notch  32  of the handle  22 . A portion of the cutting edge  20  may project below a lower surface  42  of the handle  22 . The tissue-displacing member  30  may have a convex arc shape. An outer tip  30 - 1  of the member  30  may have a smooth rounded shape with a radius of between about 1.5 mm to 3 mm. The outer tip  30 - 1  may project below a forward end  20 - 1  of the blade cutting edge  20  by a distance L. Advantageously the distance L may be between about 1 mm to about 6 mm. The outer tip  30 - 1  may project a distance D below the bottom surface  42  of the handle  22 . Advantageously, the distance D may be between about 7 mm to about 10 mm. 
         [0017]    The knife  10  may be constructed with the blade  18  imbedded in the handle  22  as an injection molded assembly. In that regard, the knife  10  may be produced as a relatively inexpensive and disposable surgical instrument. 
         [0018]    In operation, the knife  10  may be employed to safely make an incision in a tissue layer such as a peritoneum or dural layer without risk that the blade  18  may cause damage to underlying organs or tissue. Referring particularly to  FIG. 7 , it may be seen that tip  30 - 1  of the knife  10  may be inserted through an initial-entry opening in the tissue layer or membrane  14 . The blade  20  may be then drawn across the membrane  14  to be cut. The tip  30 - 1  of the tissue-displacement member  30  may press against underlying tissue  15  to displace the tissue  15  from the incision plane. It may be seen that the knife  10  may safely make incisions while being either pulled or pushed along the incision plane. 
         [0019]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.