Abstract: A surgical knife device includes a tubular shaft, a blade guide at the distal end of the shaft, an actuation wire extending through the shaft, a blade coupled to the distal end of the wire, and a handle which moves the wire relative to the shaft to effect extension and retraction of the blade from the guide. The blade height is substantially the same as the outer diameter of the distal end of the shaft and the blade guide to provide a large cutting surface. Movement of the blade is effected with a knob rotatably coupled to the handle and which provides fine longitudinal movement of the blade. The device is also preferably steerable such that it may be controllably articulated about a flexible distal portion of the shaft.