Importance

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Abstract

A cannula for extension through a tissue into a cavity and having: a cylindrical sleeve defining a hollow passageway through which a surgical instrument can be directed, with the sleeve having a) a proximal end to be manipulated by a user in directing the sleeve into an operative position through the body tissue into the body cavity, b) a distal end which projects into the body cavity with the sleeve in its operative position, and c) a cylindrical outer surface; expandable structure at the distal end of the sleeve for preventing withdrawal of the sleeve from the tissue with the expandable structure in an expanded state, the expandable structure being collapsible from its expanded state, wherein it projects radially beyond the outer surface of the sleeve sufficiently to prevent passage of the distal end of the sleeve and expandable structure thereon through an incision having a diameter approximately equal to the diameter of the outer cylindrical surface of the sleeve, to a collapsed state in which the expandable structure does not project sufficiently beyond the outer surface of the sleeve to significantly obstruct passage of the distal end of the sleeve and expandable structure through a tissue incision approximately equal in diameter to the outer surface of the sleeve; structure for selectively placing the expandable structure in its expanded and collapsed states; a retaining collar having a tapered surface; and cooperating structure on the sleeve and collar for permitting movement of the collar relative to the sleeve towards the sleeve distal end so that the body tissue through which the sleeve is directed can be captured between the tapered collar surface and the expandable structure to thereby maintain the sleeve positively in its operative position.

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First Claim