An apparatus for use during endoscopic discectomy procedures includes an elongated portion defining a generally longitudinal axis and having proximal and distal ends, a retractor mechanism disposed at the distal end of the elongated portion and having at least two retractor members for engaging...http://www.google.es/patents/US5785647?utm_source=gb-gplus-sharePatente US5785647 - Surgical instruments useful for spinal surgery
