Surgical Stapler

Abstract

A surgical stapler includes a handle assembly, an elongated body portion extending distally from the handle assembly, and a head portion disposed adjacent a distal portion of the elongated body portion and including an anvil assembly and a shell assembly. The anvil assembly is movable in relation to the shell assembly between spaced and approximated positions. The shell assembly includes a pusher movable distally to advance staples from the shell assembly into contact with the anvil assembly. First and second alignment pins operatively associated with the pusher have distal ends positioned distally of the pusher, the alignment pins movable between a first non-engaged position spaced from the anvil assembly and a second position in engagement with the anvil assembly.

What is claimed is: 
     
         1 . A surgical stapler comprising:
 a handle portion;   an elongated shaft extending from the handle portion; and   an end effector disposed at a distal end of the elongated shaft, the end effector including,
 a shell assembly; 
 an anvil selectively repositionable with respect to the shell assembly between spaced and approximated positions; and 
 an alignment mechanism including corresponding structures on each of the shell assembly and the anvil that engage each other to align the shell assembly relative to the anvil. 
   
     
     
         2 . The surgical stapler of  claim 1 , wherein the alignment mechanism inhibits rotation of the anvil relative to the shell assembly. 
     
     
         3 . The surgical stapler of  claim 1 , wherein the alignment mechanism inhibits lateral movement of the anvil relative to the shell assembly. 
     
     
         4 . The surgical stapler of  claim 1 , wherein the alignment mechanism comprises a projection on one of the shell assembly and the anvil and an opening for receiving the projection in the other of the shell assembly and the anvil. 
     
     
         5 . The surgical stapler of  claim 4 , wherein the projection frictionally engages the opening to inhibit axial movement of the anvil relative to the shell assembly. 
     
     
         6 . The surgical stapler of  claim 1 , wherein the anvil includes an anvil head and an anvil shaft extending proximally from the anvil head, the anvil shaft being removably mounted to an anvil retainer of the stapler. 
     
     
         7 . The surgical stapler of  claim 1 , wherein the shell assembly includes a pusher block operatively associated with the corresponding structure of the shell assembly and selectively moveable to advance the corresponding structure of the shell assembly into engagement with the corresponding structure of the anvil assembly. 
     
     
         8 . The surgical stapler of  claim 1 , further including:
 an annular array of staples disposed in the shell assembly, the staples in operative association with the pusher block; and   an annular array of pockets located on the anvil for deforming the staples.   
     
     
         9 . The surgical stapler of  claim 8 , wherein the corresponding structure of the shell assembly is positioned radially inwardly of the annular array of staples. 
     
     
         10 . The surgical stapler of  claim 8 , wherein the corresponding structure of the anvil is positioned radially inwardly of the annular array of pockets. 
     
     
         11 . The surgical stapler of  claim 1 , wherein the shell assembly includes an annular knife and the corresponding structure of the shell assembly is positioned radially outwardly of the annular knife. 
     
     
         12 . The surgical stapler of  claim 1 , wherein the alignment mechanism includes two corresponding structures on each of the anvil and the shell assembly. 
     
     
         13 . The surgical stapler of  claim 1 , wherein the alignment mechanism includes at least one more corresponding structure on one of the anvil and the shell assembly than on the other of the anvil and the shell assembly.