A surgical instrument for use in a therapeutic treatment of a patient has a stem connected to a handle, and a slide connected to a trigger. An end effector forms a distal portion for manipulating body tissue, for example a curette, and a proximal portion that is pivotally connected to either the stem or slide. A lever extends from near the pivot and is engaged by the other of the stem or slide. When the slide and stem are slid relative to each other, the lever is engaged to pivot the end effector within the body, for example to cut tissue. A post on the lever engages a channel in the stem or slide, to guide movement of the end effector. A link may be pivotally connected between the lever and a stem or slide, to increase a range of motion of the end effector.