Patent ID: 8187293

Claim:
A microsurgical instrument, comprising: a cutting member having: a tubular outer cutting member with a port for receiving tissue, said port having a distal cutting surface and a proximal cutting surface; and a tubular inner cutting member disposed within said outer cutting member and having a third cutting surface; and a base having an actuating mechanism for reciprocating actuation of said inner cutting member so that said inner cutting member opens and closes said port and cuts tissue disposed in said port, said actuating mechanism comprising: a diaphragm chamber having a distal wall portion and a proximal wall portion; a rigid center support disposed in said diaphragm chamber and having a rigid distal limiting surface and a rigid proximal limiting surface; a flexible diaphragm coupled to said center support and said base; a first pneumatic port for providing pressurized gas to a portion of said diaphragm chamber on a proximal side of said flexible diaphragm; and a second pneumatic port for providing pressurized gas to a portion of said diaphragm chamber on a distal side of said flexible diaphragm; whereby upon actuation of said inner cutting member via a pressure differential across said flexible diaphragm created using said first pneumatic port and said second pneumatic port, said rigid distal limiting surface contacts said distal wall portion when said third cutting surface is disposed proximate said distal cutting surface at an end of a cutting stroke in which said inner cutting member is moving in a distal direction, and said rigid proximal limiting surface contacts said proximal wall portion when said third cutting surface is disposed proximate said proximal cutting surface at an end of a return stroke in which said inner cutting member is moving in a proximal direction.