A cannula includes a tubular body having a proximal end and distal blunt end, at least one lumen extending the length of the body, an endoscope having a lighted, viewing end disposed in the lumen near the distal end of the body, and a transparent, tissue-separating tip substantially covering the distal...http://www.google.fr/patents/US5976168?utm_source=gb-gplus-shareBrevet US5976168 - Tissue separation cannula
