A cutter (10) for use in surgery, comprising a needle (20) having a cutting end (21) and a cursor (30) slidably mountable on or mounted on the needle (20). The cursor has a cursor housing (32) slidably mountable on the needle (20) with the cursor housing (32) having an open end facing the needle cutting end, and a pair of flat cutter blades (15) mounted in the cursor housing (32) on either side of the needle (20). The cutter blades are mounted for movement together relative to the cursor housing (32) between a first stored position wherein the cutter blades (15) are enclosed in the cursor housing (32) and a second projecting position wherein cutting edges (16) of the cutter blades (15) project from the open end of the cursor housing (32). The cutter blades (15) are movable from the first to the second position against the action of biasing means (38) that act to return the cutter blades to the first position.
