Endoscopic Instrument with Control Member Having Decreasing Torsional and Flexural Stiffness Along Its Length
An endoscopic instrument includes a tubular member having a proximal end and a distal end, a clevis rotatably mounted at the distal end of the tubular member, and an end effector assembly having first and second end effectors mounted on the clevis. A control member extends through the tubular and is coupled to the end effector assembly for moving at least one end effector relative to the other. The control member has decreasing torsional and flexural stiffness at different portions along its length from its proximal end to its distal end. The control member is a composite structure.
1 . An endoscopic instrument, comprising:
a) a flexible tubular member having proximal and distal ends and defining a longitudinal axis;
b) a control member having proximal and distal ends and a length therebetween, said control member having decreasing torsional and flexural stiffness at different portions along its length from its proximal end to its distal end, said control member extending through said tubular member;
c) a clevis mounted at said distal end of said tubular member;
d) at least one end effector mounted on said clevis, said distal end of said control member being coupled to said end effector; and
e) a proximal handle assembly for longitudinally and rotationally displacing said control member relative to said tubular member to cause (i) movement of said at least one end effector relative to said clevis and (ii) rotation of said at least one end effector about the longitudinal axis.
2 . An endoscopic instrument according to claim 1 , wherein:
said control member includes a proximal portion consisting essentially of a single rod, and a distal portion consisting essentially of multistrand cable.
3 . An endoscopic instrument according to claim 2 , wherein:
said single rod and said multistrand cable are joined by a section of a hypotube.
4 . An endoscopic instrument according to claim 2 , wherein:
said single rod is a spring steel wire.
5 . An endoscopic instrument according to claim 1 , wherein:
said control member includes a proximal portion consisting essentially of a single spring steel wire, and a distal portion consisting essentially of a single superelastic metal alloy wire.
6 . An endoscopic instrument according to claim 5 , wherein:
said steel wire and said superelastic metal alloy wire are joined by a section of a hypotube.
7 . An endoscopic instrument according to claim 1 , wherein:
said control member includes a proximal portion consisting essentially of a composite carbon rod, and a distal portion consisting essentially of multistrand cable.
8 . An endoscopic instrument according to claim 1 , wherein:
said control member includes a proximal portion consisting essentially of a composite carbon rod, and a distal portion consisting essentially of a single superelastic metal alloy wire cable.
9 . An endoscopic instrument according to claim 1 , wherein:
said proximal and distal portions of said control member are joined by a hypotube.
10 . An endoscopic instrument according to claim 1 , wherein:
said tubular member is sufficiently elastically-flexible to be passed through a tortuous passage of a retroflexed endoscope.
11 . An endoscopic instrument according to claim 1 , wherein:
said clevis is rotatably mounted relative to said distal end of said tubular member.
12 . An endoscopic instrument according to claim 1 , further comprising:
an inner bearing fixed within and relative to said distal end of said tubular member, said clevis disposed distally adjacent said inner bearing; and
an outer bearing fixed to said clevis and rotatable about said inner bearing such that said clevis is rotatable relative to said distal end of said tubular member.