Apparatus and method for cutting tissue

Abstract

A cutting instrument comprising: an outer tube; an inner tube rotatably disposed within the outer tube; the inner tube comprising an opening having a leading edge and a trailing edge; and the outer tube comprising a window having a leading edge and a trailing edge; at least one of the leading edge of the opening, the trailing edge of the opening, the leading edge of the window and the trailing edge of the window comprising a canted edge; and the window of the outer tube being adapted to be completely blocked by the inner tube during a phase of the rotation of the inner tube within the outer tube.

1 .- 20 . (canceled) 
     
     
         21 . A cutting instrument comprising:
 an outer tube;   an inner tube rotatably disposed within said outer tube;   said outer tube comprising a window having a leading edge and a trailing edge; and   wherein said window of said outer tube is progressively increasingly blocked, from said leading edge of said window to said trailing edge of said window, during successive phases of rotation of said inner tube within said outer tube, and completely blocked by said inner tube during a phase of the rotation of said inner tube within said outer tube.   
     
     
         22 . A cutting instrument according to  claim 21  wherein said inner tube comprises an opening having a leading edge and a trailing edge. 
     
     
         23 . A cutting instrument according to  claim 22  wherein at least one of said leading edge of said opening, said trailing edge of said opening, said leading edge of said window and said trailing edge of said window comprises a canted edge. 
     
     
         24 . A cutting instrument according to  claim 23  wherein said canted edge comprises a helix of constant pitch. 
     
     
         25 . A cutting instrument according to  claim 23  wherein said canted edge comprises a segment of an ellipse. 
     
     
         26 . A cutting instrument according to  claim 21  wherein, during rotation of said inner tube relative to said outer tube, a scissoring effect is created at one of said leading edge of said window and said trailing edge of said window. 
     
     
         27 . A cutting instrument according to  claim 22  wherein at least one of said leading edge of said opening and said trailing edge of said opening comprises a helix. 
     
     
         28 . A cutting instrument according to  claim 21  wherein at least one of said leading edge of said window and said trailing edge of said window comprises a helix. 
     
     
         29 . A cutting instrument according to  claim 27  wherein at least one of said leading edge of said opening and said trailing edge of said opening comprises a different pitch than at least one of said leading edge of said window and said trailing edge of said window. 
     
     
         30 . A cutting instrument according to  claim 23  wherein at least one edge of said opening is canted, at least one edge of said window is canted, and said at least one canted edge of said opening and said at least one canted edge of said window are canted in the same direction of turn. 
     
     
         31 . A cutting instrument according to  claim 22  wherein at least one of said leading edge of said opening and said trailing edge of said opening comprises a canted edge, and at least one of said leading edge of said window and said trailing edge of said window comprises a canted edge; and
 wherein said at least one canted edge of said opening and said at least one canted edge of said window are canted in the same direction of turn. 
 
     
     
         32 . A cutting instrument according to  claim 29  wherein said at least one canted edge of said opening comprises a helix of constant pitch, and further wherein said at least one canted edge of said window comprises a helix of constant pitch. 
     
     
         33 . A cutting instrument according to  claim 29  wherein said at least one canted edge of said opening comprises a segment of an ellipse, and further wherein said at least one canted edge of said window comprises a segment of an ellipse. 
     
     
         34 . A cutting instrument according to  claim 29  wherein, during rotation of said inner tube relative to said outer tube, a scissoring effect is created at one of said leading edge of said opening and said trailing edge of said opening. 
     
     
         35 . A cutting instrument according to  claim 29  wherein, during rotation of said inner tube relative to said outer tube, a scissoring effect is created at one of said leading edge of said window and said trailing edge of said window. 
     
     
         36 . A cutting instrument according to  claim 29  wherein at least one of said leading edge of said opening and said trailing edge of said opening comprises a helix. 
     
     
         37 . A cutting instrument according to  claim 29  wherein at least one of said leading edge of said window and said trailing edge of said window comprises a helix. 
     
     
         38 . A cutting instrument according to  claim 33  wherein at least one of said leading edge of said opening and said trailing edge of said opening comprises a different pitch than at least one of said leading edge of said window and said trailing edge of said window. 
     
     
         39 . A method for cutting an object, the method comprising:
 providing a cutting instrument comprising:
 an outer tube; 
 an inner tube rotatably disposed within said outer tube; 
 said outer tube comprising a window having a leading edge and a trailing edge; 
 wherein said window of said outer tube is progressively increasingly blocked, from said leading edge of said window to said trailing edge of said window, during successive phases of rotation of said inner tube within said outer tube, and completely blocked by said inner tube during a phase of the rotation of said inner tube within said outer tube; 
   positioning the object in said window; and   rotating said inner tube within said outer tube.   
     
     
         40 . A cutting instrument comprising:
 an outer tube;   an inner tube rotatably disposed within said outer tube;   said inner tube comprising an opening having a leading edge and a trailing edge; and   said outer tube comprising a window having a leading edge and a trailing edge;   at least one of said leading edge of said opening, said trailing edge of said opening, said leading edge of said window and said trailing edge of said window comprising a canted edge; and   wherein said window of said outer tube is progressively increasingly blocked, from said leading edge of said window to said trailing edge of said window, during successive phases of rotation of said inner tube within said outer tube, and completely blocked by said inner tube during a phase of the rotation of said inner tube within said outer tube.