| 摘要 |
A surgical incising instrument having a helical blade allows a surgeon to helically incise a pathway through tissue into the interior of the body at a controlled rate without exerting longitudinal forces on the instrument. The instrument incorporates a variform or "split-lands" helix that includes a blade member with a sharp helical blade edge and a shield member with a dull helical edge that mate along helicoidal interfaces that "split" the lands, thus providing for a helix periphery that may either expose or not expose the sharp blade edge outside the dull lands. The instrument is particularly useful for accessing an anatomic cavity and incorporates a latch and spring mechanism that transforms the variform helix into a dull-edged helix from a sharp-edged helix in response to penetration of a body wall overlying an anatomic cavity, thus protecting organs within the cavity from contact with any sharp blade edge. |
