An endoscopic surgical instrument includes an elongated shaft, which may be articulated to facilitate positioning of an end effector. The instrument accommodates reactionary forces associated with closing the end effector without substantial disruption to the position of the end effector. The instrument includes an elongated shaft housing generally defining distal and proximal shaft axes, and a torsion member extending through the shaft housing. The torsion member transmits rotational displacement from a handle portion of the instrument to the end effector to selectively move the end effector between open and closed configurations. The torsion member comprises a flexible shaft exhibiting a plurality of generally radial slots spaced longitudinally along a length of the flexible shaft.
