Patent ID: 8241280

Claim:
A surgical instrument for insertion through a medical device having a handle and a working channel, said surgical instrument comprising: a elongate flexible tubular sheath having proximal and distal ends; a flexible shaft extending through and axially movable relative to the sheath, said shaft having proximal and distal ends; an end effector coupled to or formed at said distal end of said shaft; a first handle assembly positioned distally of the proximal end of the shaft; a second handle assembly coupled to the proximal ends of the tubular sheath and flexible shaft; wherein the first handle assembly includes a rotatable knob having a bore formed therein; wherein a key member is attached to the shaft; wherein the key member has a non-circular cross-sectional shape; wherein the key member is disposed within the bore and is axially movable within the bore; and wherein said flexible shaft includes a plurality of individual wire filaments, each having an input end and an output, the input end of each individual wire filament being coupled to the input end of each other individual wire filament, the output end of each individual wire filament being coupled to the output end of each other individual wire filament, and between their input ends and their output ends, said individual wire filaments are loosely associated.