Apparatus is described including an elongate element (922) for inserting into a subject's body, there being a joint (911) at a distal end of the elongate element. An arm (912) has a proximal end and a distal end (913). The distal end of the arm is articulatable at the joint with the elongate element. In a closed position of the arm with respect to the elongate element, a portion of the arm faces a portion of the elongate element. A cutting element (921) is coupled to at least one of the portions. Other embodiments are also described.
