The invention relates to an instrument for endoscopic therapy. A cutting tool including a rigid tubular shank is so guided within a tubular longitudinally slotted instrument shank having an essentially oval inner cross section, that the cutting tool may be tilted out of the axis of the instrument...http://www.google.com.au/patents/US5735865?utm_source=gb-gplus-sharePatent US5735865 - Instrument for endoscopic therapy
