Directionally biased staple and anvil assembly for forming the staple

Abstract

In accordance with the present disclosure a directionally biased staple is provided for use in all types of surgical staplers having anvil structure against which the staple is formed. The directionally biased staple may be constructed in a wide variety of cross-sectional configurations including rectangular, elliptical, trapezoidal, etc. All of the configurations are distinguished by having a bending region requiring more force to twist or malform the staple than is required to properly form the staple. Preferably, these staples have Moment of Inertia Ratios on the order of between about 1.1 to about 3.0. The staple preferably corresponds in other respects to conventional formed staples, i.e. having at least a pair of leg members interconnected by a crown portion wherein the leg members are formed by direct contact with the anvil. An anvil assembly is also provided for minimizing the malformation of staples.

What is claimed is:  
     
         1 . An anvil assembly comprising: 
 an anvil plate having a tissue contact surface defining a plane and a plurality of anvil pockets formed therein, each of the anvil pockets having a central longitudinal axis and including first and second staple forming cups, each of the first and second staple forming cups having an outside portion and an inside portion, the inside portion of the first and second staple forming cups being positioned in close relation to each other on the central longitudinal axis of the anvil pocket, the outside portion of the first and second staple forming cups being positioned in spaced relation to each other on the central longitudinal axis of the anvil pocket, each of the first and second cups being defined by sidewalls and an elongated base surface extending along the central longitudinal axis of the anvil pocket, wherein the sidewalls of each of the first and second cups form an acute angle with respect to the plane defined by the tissue contact surface of the anvil plate at the outside portion of the cup and become progressively more perpendicular towards the inside portion of the cup such that the first and second cups are substantially vertical through at least a portion of the inside portion of the cup.    
     
     
         2 . An anvil assembly according to  claim 1 , wherein the elongated base surface is linear along an axis perpendicular to the longitudinal axis of the anvil pocket.  
     
     
         3 . An anvil assembly according to  claim 1 , wherein the sidewalls defining the inside portion of each cup are substantially perpendicular to the plane defined by the tissue contact surface of the anvil plate such that a substantially vertical trap is formed in a central portion of each of the anvil pockets.  
     
     
         4 . An anvil assembly according to  claim 3 , further including a channeling surface formed about at least a portion of each of the staple forming cups.  
     
     
         5 . An anvil assembly according to  claim 3 , wherein the elongated base surface is concavely curved along the longitudinal axis of the anvil pocket.  
     
     
         6 . An anvil assembly according to  claim 5 , wherein the concavely curved elongated base surface has a radius of curvature r, and the length of the substantially vertical trap is from about 0.5 r to about 2 r.  
     
     
         7 . An anvil assembly according to  claim 6 , wherein the length of the substantially vertical trap is about r.  
     
     
         8 . An anvil assembly according to  claim 7 , wherein the length of the substantially vertical trap is from about 0.030″ to about 0.100 inch.  
     
     
         9 . An anvil assembly according to  claim 8 , wherein the length of the substantially vertical trap is about 0.050 inch.  
     
     
         10 . An anvil assembly according to  claim 3 , wherein the substantially vertical trap extends along the entirety of the length of the inside portion of the staple forming cup.  
     
     
         11 . An anvil assembly according to  claim 10 , wherein the substantially vertical trap starts in the central portion of the staple forming cup.  
     
     
         12 . An anvil assembly according to  claim 11 , wherein the substantially vertical trap starts before the central portion of the staple forming cup.