| 摘要 |
An active cannula which does more than merely maintain a passage is usable to create and/or enlarge a passage, to position a scope or instrument, to move or locate tissue, etc. The cannula can vary in size or shape as needed, intraoperatively. Because a cannula of the present invention is expandable, the surgeon can make a relatively small incision, stretch the tissue with the expandable cannula, contract the cannula and remove it, allowing the skin to come back to its unstretched condition. Thus, a smaller incision can be made to fit the same size instrument. The cannulas can assume such a non-circular shape, to fit into a natural skin opening and cause less trauma. The devices can be used to seal off a space, expand an existing space or a potential space for working or visualization, move tissue (for example, to stretch an incision), or protect tissue.
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