A device may comprise a work element, an outer tube co-axially disposed around a portion of the work element and a collar assembly. The work element may be configured to rotate and define proximal and distal ends, and may comprise a body portion, one or more articulable beak(s) configured to cut tissue, and a beak actuation portion. The collar assembly may be coupled to the work element away from the articulable beak(s), and may comprise a distal collar element coupled to the body portion, a middle collar element coupled to the outer tube and a proximal collar element coupled to the beak actuation portion. The distal collar element may comprise a first peripheral surface that extends around the distal collar element and that faces the proximal end and the middle collar element may comprise a second peripheral surface that that extends around the middle collar element, faces the distal end and at least partially contacts the first peripheral surface. The first and second peripheral surfaces each may comprise a smooth undulating surface that comprises a plurality of peaks and valleys. The distal, middle and proximal collar elements may be configured to control opening, closing, extending and retracting the articulable beak(s) by rotating in synchronicity, rotating differentially and/or moving toward the distal or proximal ends.
