A minimally invasive surgical instrument includes a first mechanism including a periphery and an opening in the periphery, a second mechanism including a surface and a helical slot in the surface, a pin extending through the opening of the first mechanism and into the helical slot of the second mechanism, and a surgical device coupled to an end of the first mechanism. A first axial axis of rotation is defined for the first mechanism. A second axial axis of rotation is defined for the second mechanism. The second axial axis of rotation is coincident with the first axial axis of rotation. Rotation of the first mechanism relative to the second mechanism results in motion of the second mechanism along the second axial access of rotation relative to the first mechanism.