A laparoscopic surgical retractor for use during a laparoscopic spinal procedure, includes an elongated sleeve member having proximal and distal end portions and defining a longitudinal opening therethrough and a valve assembly mounted to the proximal end portion of the elongated sleeve member for sealing...http://www.google.es/patents/US6004326?utm_source=gb-gplus-sharePatente US6004326 - Method and instrumentation for implant insertion
