Obturator tip
A surgical instrument for use with a surgical portal apparatus includes an elongate shaft having proximal and distal ends and defining a longitudinal axis and a dilating member disposed at the distal end of the elongate shaft. The dilating member has a first longitudinal arc segment and a second longitudinal arc segment in diametrical opposed relation to the first longitudinal arc segment. The first and second longitudinal arc segments define respective first and second radii of curvature transverse to the longitudinal axis. The first and second radii of curvature decrease from proximal to distal to define a generally tapered configuration of the dilating member. The first radius of curvature is greater than the second radius of curvature at predefined longitudinal positions of the dilating member such that the first longitudinal arc segment extends distally beyond the second longitudinal segment to define a penetrating tip. The penetrating tip has a reduced profile and dimensioned to facilitate initial insertion of the dilating member into tissue.
1. A surgical instrument for use with a surgical portal apparatus, which comprises:
an elongate shaft defining a longitudinal axis; and
a dilating member supported at a distal end of the elongate shaft and having a continuous closed outer end, the dilating member having a first longitudinal arc segment and a second longitudinal arc segment in diametrical relation and intersecting along a median plane of intersection, the first and second longitudinal arc segments each having a semi-circular cross-section orthogonal to the median plane of intersection and defining respective first and second radii of curvature, the first radius of curvature being different from the second radius of curvature at predetermined longitudinal positions along the dilating member, the first longitudinal arc segment defining a peripheral surface circumscribing an outer periphery of the second longitudinal arc segment, the peripheral surface coplanar with the median plane of intersection.
2. The surgical instrument according to claim 1 wherein the peripheral surface is planar.
3. The surgical instrument according to claim 2 wherein the first longitudinal arc segment is dimensioned to extend distally beyond the second longitudinal segment to define a penetrating tip, the penetrating tip having a reduced profile and dimensioned to facilitate initial insertion of the dilating member into tissue.
4. The surgical instrument according to claim 3 wherein the penetrating tip includes a section of the peripheral surface of the first longitudinal arc segment.
5. The surgical instrument according to claim 1 wherein the dilating member is a substantially solid member.
6. The surgical instrument according to claim 1 wherein the dilating member defines a hollow interior.
7. The surgical instrument according to claim 6 wherein the dilating member is at least partially transparent.
8. The surgical instrument according to claim 7 wherein the dilating member is monolithically formed.
9. A surgical instrument for use with a surgical portal apparatus, which comprises:
an elongate shaft defining a longitudinal axis; and
a dilating member supported at a distal end of the elongate shaft and having a continuous closed outer end, the dilating member having a first longitudinal arc segment and a second longitudinal arc segment in diametrical relation and intersecting along a median plane of intersection, the first longitudinal arc segment defining a peripheral surface circumscribing an outer periphery of the second longitudinal arc segment, the peripheral surface coplanar with the median plane of intersection, the juncture of the second longitudinal arc segment and the elongate shaft defining a vertical surface in general transverse relation to the longitudinal axis, the vertical surface extending about the second longitudinal arc segment.
10. The surgical instrument according to claim 9 wherein the vertical surface is substantially planar.
11. The surgical instrument according to claim 9 wherein the first and second longitudinal arc segments define respective first and second radii of curvature transverse to the longitudinal axis, the first radius of curvature being different from the second radius of curvature at predetermined longitudinal positions along the dilating member.
12. A surgical instrument for use with a surgical portal apparatus, which comprises:
an elongate shaft defining a longitudinal axis; and
a dilating member supported at a distal end of the elongate shaft and having a continuous closed outer end, the dilating member having a first longitudinal arc segment and a second longitudinal arc segment in diametrical relation and intersecting along a median plane of intersection, the first longitudinal arc segment defining a peripheral surface circumscribing an outer periphery of the second longitudinal arc segment, the peripheral surface coplanar with the median plane of intersection, the first and second longitudinal arc segments defining respective first and second radii of curvature transverse to the longitudinal axis, the first radius of curvature being greater than the second radius of curvature at predetermined positions along the longitudinal axis.
13. A surgical instrument for use with a surgical portal apparatus, which comprises:
an elongate shaft having proximal and distal ends, and defining a longitudinal axis; and
a dilating member supported at the distal end of the elongate shaft and having a continuous closed outer end, the dilating member having a first longitudinal arc segment and a second longitudinal arc segment in diametrical relation with respect to a median longitudinal plane extending between the first and second longitudinal arc segments, the first and second longitudinal arc segments defining first and second radii of curvature, the first and second radii of curvature decreasing from proximal to distal to define a generally tapered configuration and being different at predetermined longitudinal positions relative to the longitudinal axis, the first longitudinal arc segment in fixed relation with the second longitudinal arc segment.
14. The surgical instrument according to claim 13 wherein the dilating member is monolithically formed.
15. The surgical instrument according to claim 13 wherein the first and second longitudinal arc segments are dimensioned to define a peripheral surface circumscribing an outer periphery of the second longitudinal arc segment.
16. The surgical instrument according to claim 15 wherein the peripheral surface is coplanar with the median longitudinal plane.