Obturator with rotating, resettable safety shield

DETAILED DESCRIPTION The present invention is directed to an obturator usable with a hollow trocar body.
The obturator has a pivotal safety shield at the obturator's tip.
The safety shield is pivotally mounted to the tip of the obturator for movement between a cutting position, at which the cutting element is exposed, and a safe position, at which the cutting element is covered by the safety shield.
This movement occurs automatically with passage of the cutting element at least partly through the tissue layer being cut.
The safety shield can be returned to the cutting position, so to re-expose the cutting element, by manipulation of a rearming device at the proximal end of the obturator.
In the preferred embodiments the safety shield, which is normally biased from the cutting position to the safe position by a drive spring, is maintained in the cutting position until a release button at the tip of the obturator is depressed.
The release button is positioned so that the cut tissue depresses the release button to permit the safety shield to pivot, under the influence of the spring, from the cutting position to the safe position.
The safety shield, in one preferred embodiment, includes a pulley integrally formed with the safety shield.
The pulley is connected to the distal ends of a pair of drive cable segments.
The proximal end of one cable segment is placed in tension by the drive spring while the proximal end of the other cable segment is connected to a safety shield control element.
The drive spring pulls on the one cable segment to bias the safety shield from the cutting position to the safe position.
The safety shield control element is a user operable element and is used to pull on the other cable segment to return the safety shield to the cutting position.
The safety shield, in a second preferred embodiment, includes an integral pulley configured so that the drive cable segments each wrap around the pulley so that neither of the cable segments ever unwinds completely from the pulley