Medical instrument with dual action drive

DETAILED DESCRIPTION The dual action end effector medical instrument including a dual action drive member disclosed herein uses a dual action drive member to move the end effectors of the instrument, relative to one another, as the dual action drive member is moved proximally or distally within a tubular extension.
In one embodiment, the medical instrument employs two movable end effectors each of which is rotatably attached, by means of a hollow pivot, located substantially adjacent to the proximal end of each end effector, to and within the tubular extension.
Each end effector is also attached, between the outer surface of the end effector and the pivot, to a respective arm of the dual action drive member.
As the dual action drive member is moved proximally or distally within the tubular extension, the distal ends of the end effectors are made to rotate about the pivot in a direction opposite to one another.
The counter rotation of the distal ends of the end effectors opens and closes the instrument.
The closing motion involves the application of face to face forces at the ends of the arms of the dual action drive member and thereby avoids the excessive shear forces which occur on the linking pins of the prior art drive members.
The dual action drive member may be used with a variety of different end effector devices including but not limited to medical grippers, scissors, punches, extractors, dissectors and clamps.