U.S. patent application number 10/539641 was filed with the patent office on 2006-03-09 for internal tissue retractor.
Invention is credited to CharlesC Hart.
Application Number | 20060052669 10/539641 |
Document ID | / |
Family ID | 32825212 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060052669 |
Kind Code |
A1 |
Hart; CharlesC |
March 9, 2006 |
Internal tissue retractor
Abstract
A positionable internal retraction device is provided comprising
a malleable ring member and a web-like structure. The retraction
device operates to temporarily reposition tissues and organs from
an operative site to provide a clear access and visual path for the
surgeon. The ring member may be elongated, twisted, folded, bent or
deformed to provide an appropriate insertion profile and subsequent
functional shape. The retraction device may be shaped for both open
and minimally invasive surgeries. The retraction device is
atraumatic and may be used for retraction of delicate tissues and
organs. The ring member may have different bending biases. The
web-like structure may be constructed of any elastic material that
can stretch and recover from the shaping and reshaping of the ring
member. In another aspect of the invention, the ring member further
comprises an internal lumen defining a wall, which may be of any
geometric shape providing a desired bending bias. The ring member
may further include a reinforcement member placed within the lumen
and made of a "shape memory" material that allows the reinforcement
member to return to its desired shape or condition after being
bent. The reinforcement member may be placed in some sections of
the ring member to keep these sections substantially straight. Each
of the ring member, the reinforcement member and the internal wall
may have a cross-section or profile of any geometric shape to
provide a desired bending bias in a preferred plane. In yet another
aspect of the invention, the ring member further comprises a second
lumen and a second reinforcement member placed within the second
lumen to provide a desired bending bias.
Inventors: |
Hart; CharlesC;
(Summerville, SC) |
Correspondence
Address: |
APPLIED MEDICAL RESOUCES CORPORATION
22872 Avenida Empresa
Rancho Santa Margarita
CA
92688
US
|
Family ID: |
32825212 |
Appl. No.: |
10/539641 |
Filed: |
January 20, 2004 |
PCT Filed: |
January 20, 2004 |
PCT NO: |
PCT/US04/01584 |
371 Date: |
June 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60442390 |
Jan 24, 2003 |
|
|
|
Current U.S.
Class: |
600/206 |
Current CPC
Class: |
A61B 17/0218 20130101;
A61B 2017/0212 20130101; A61B 2017/2931 20130101; A61B 1/32
20130101; A61B 17/0293 20130101 |
Class at
Publication: |
600/206 |
International
Class: |
A61B 1/32 20060101
A61B001/32 |
Claims
1. A retraction device 10 adapted to temporarily reposition body
tissues and organs during a surgical procedure, comprising: a
malleable ring member 15 comprising a plurality of bending portions
24, 25, 26, 27 adapted to be twisted, folded, bent or deformed to
be inserted into a surgical incision; and a membrane 60 fixedly
attached around the perimeter of the ring member 15.
2. The retraction device of claim 1, wherein the membrane 60 is a
flexible fabric operable to retain the body tissues and organs of
different shapes and sizes.
3. The retraction device of claim 1, wherein the membrane 60 is
capable to retaining both hard and soft body tissues and organs
during surgery.
4. The retraction device of claim 1, wherein the bending portions
24, 25, 26, 27 and the membrane 60 are taut enough to securely hold
and separate hard tissues and organs yet are flexible enough to
gently retain soft tissues and organs so as to damage the tissues
and organs or affect their circulation.
5. The retraction device of claim 1, wherein the membrane 60 is
transparent.
6. The retraction device of claim 1, wherein the membrane 60 is
sized and configured to stretch and recover to the shaping and
reshaping of the ring member 15.
7. The retraction device of claim 1, wherein the membrane 60 is a
bias woven or knitted fabric.
8. The retraction device of claim 1, wherein the membrane 60 is
formed of any elastic material that responds to the shaping and
reshaping of the ring member 15.
9. The retraction device of claim 1, wherein the ring member 15 has
an oval cross-section providing a preference for bending along the
long axis.
10. The retraction device of claim 1, wherein the ring member 15
has a substantially square cross-section providing equal preference
to bending in both axes or planes and resistance to bending
diagonally.
11. The retraction device of claim 1, wherein the ring member 15
has a circular cross-section.
12. The retraction device of claim 1, wherein the ring member 15
further comprises an internal lumen 56 defining a wall 57.
13. The retraction device of claim 12, wherein the wall 57 has a
circular cross-section or a cross-section of any geometric shape
providing a desired bending bias.
14. The retraction device of claim 12, wherein the ring member 15
further comprises a reinforcement member 315 placed within the
lumen 56 to provide additional bending bias.
15. The retraction device of claim 14, wherein the reinforcement
member 315 comprises at least a plastic component and a metallic
component.
16. The retraction device of claim 15, wherein the metallic
component includes at least one of aluminum, titanium and stainless
steel.
17. The retraction device of claim 14, wherein the reinforcement
member 315 is placed in some sections 28, 29 of the ring member 15
to keep said sections 28, 29 substantially straight.
18. The retraction device of claim 14, wherein the reinforcement
member 315 comprises a shape memory material including Nitenol.
19. The retraction device of claim 1, wherein the ring member 15
comprises a plurality of cords 202, 204, said cords 202, 204 are
vertically joined at a point 206 along vertical axes of the cords
202, 204.
20. The retraction device of claim 19, wherein the cords 202, 204
have oval cross-sections.
21. The retraction device of claim 14, wherein the reinforcement
member 315 has a first cross-section and the ring member 15 has a
second cross-section different in shape from the first
cross-section.
22. The retraction device of claim 21, wherein the first
cross-section of the reinforcement member 315 is rectangular and
the second cross-section of the ring member 15 is circular.
23. The retraction device of claim 14, wherein each of the ring
member 15, the reinforcement member 315 and the wall 57 has a
cross-section or a profile of any geometric shape to provide a
desired bending bias in a preferred plane.
24. The retraction device of claim 21, wherein the reinforcement
member 315 imparts a different bending bias on the ring member
15.
25. The retraction device of claim 14, wherein the ring member 325
further comprises a second lumen 335 and a second reinforcement
member 355 placed within the second lumen 335.
26. A method for operating a retraction device 10 adapted to
reposition body tissues and organs during a surgical procedure,
comprising the steps of: providing a malleable ring member 15
having a plurality of bending portions 24, 25, 26, 27 and a
membrane 60 fixedly attached around the perimeter of the ring
member 15, said portions 24, 25, 26, 27 adapted to be twisted,
folded, bent or deformed to be inserted into a surgical incision;
inserting the ring member 15 into the surgical incision to provide
an operable area; and twisting, folding, bending or deforming the
portions 24, 25, 26, 27 of the ring member 15 during the surgical
procedure to reposition the body tissues and organs.
27. The method of claim 26, further comprising the step of removing
the ring member 15 from the operable area by twisting, folding,
bending or deforming the portions 24, 25, 26, 27 and puling them
through the surgical incision after surgery.
28. The method of claim 26, wherein the membrane 60 is a flexible
fabric operable to retain the body tissues and organs of different
shapes and sizes.
29. The method of claim 26, wherein the membrane 60 is capable to
retaining both hard and soft body tissues and organs during
surgery.
30. The method of claim 26, wherein the ring member 15 further
comprises an internal lumen 56 defining a wall 57.
31. The method of claim 30, wherein the wall 57 has a circular
cross-section or a cross-section of any geometric shape providing a
desired bending bias.
32. The method of claim 30, wherein the ring member 15 further
comprises a reinforcement member 315 placed within the lumen 56 to
provide additional bending bias.
33. The method of claim 32, wherein the reinforcement member 315
comprises at least a plastic component and a metallic
component.
34. The method of claim 32, wherein the reinforcement member 315 is
placed in some sections 28, 29 of the ring member 15 to keep said
sections 28, 29 substantially straight.
Description
[0001] This is a non-provisional application claiming the priority
of provisional application Ser. No. 60/442,390, filed on Jan. 24,
2003, entitled "Internal Tissue Retractor," which is fully
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to surgical
retractors and, in particular, to a retractor for retracting
tissues and organs to facilitate access and viewing during a
surgical procedure.
[0004] 2. Discussion of the Prior Art
[0005] Surgical procedures often require temporary retraction of
surrounding tissues and organs from the immediate surgical site to
provide an access and viewing path for the surgeon. In the prior
art, clamps, towels and other makeshift methods have been used to
separate and hold structures in a preferred position away from the
point of surgery. Retractors have been developed to push and hold
tissues and organs away from the surgical site. These devices
typically include paddles and/or collapsible fingers that expand
after the retractors have been inserted into the body. The
retractors may include expandable frames for supporting expandable
sheaths or covers. While some of these devices have been
successfully used for smaller tissues and organs, the current
retractors have had difficulty in clearing the surgical field of
larger and more slippery tissues and organs. In particular, the
shape, size and fragility of the tissues and organs may present
problems during surgery. For example, large, soft organs such as
the intestines and/or stomach are often more difficult to retract
and hold in place than from harder, less slippery tissues such as
the muscles.
[0006] Another drawback of the current retraction devices is they
typically need to be attached to an external device to provide
support and/or manipulation. These devices often need to be
over-tightened or compressed to maintain a proper grip and position
on the tissues and organs, which may cause damage to delicate
tissues and organs. Moreover, a large surgical incision must be
made to accommodate all the components of the retraction device. As
a result, the surgical site may become cluttered and encumbered by
the many additional components of the retraction device. Therefore,
there is a need in the art for a retraction device that can be
flexibly utilized to clear a surgical site of tissues and organs
having different shapes, sizes and fragility. The retraction device
should be atraumatic and be able to twist, fold or bend to
facilitate insertion and removal.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to a positionable internal
retraction device providing an operable area while holding adjacent
structures in a desired position. The retraction device comprises a
malleable ring member that supports a web-like structure. The ring
member may be elongated, twisted, folded, bent or deformed to
provide an appropriate insertion profile and subsequent functional
shape. The retraction device may be shaped for both open and
minimally invasive surgeries. The retraction device is atraumatic
and may be used for retraction of delicate tissues and organs. The
ring member may have different cross-sectional construction
providing different bending biases. The ring member may include a
lumen sized and configured to receive a reinforcement member
providing a desired bending bias in a preferred plane. The
reinforcement member may comprise a "shape memory" material that
enables the reinforcement member to return to its desired shape or
condition after being bent.
[0008] The web-like structure is constructed of an elastic material
such as a bias-woven or knitted fabric that can stretch and recover
from the shaping and reshaping of the ring member. The web-like
structure operates to retain the body tissues and organs of
different shapes and sizes. More particularly, the web-like
structure is able to retain both hard and soft body tissues and
organs during surgery. It is preferable that the web-like structure
is a transparent membrane.
[0009] In another aspect of the invention, the ring member further
comprises an internal lumen defining a wall, which may be of any
geometric shape providing a desired bending bias. The ring member
may further comprise a reinforcement member placed within the lumen
to provide additional bending bias. The reinforcement member may be
formed of a plastic component, a metallic component or any
combination thereof. The metallic component includes at least one
of aluminum, titanium, stainless steel and Nitenol. In the above
aspect of the invention, the reinforcement member may be placed in
some sections of the ring member to keep these sections
substantially straight. It is appreciated that each of the ring
member, the reinforcement member and the internal wall may have a
cross-section or profile of any geometric shape to provide a
desired bending bias in a preferred plane. In yet another aspect of
the invention, the ring member further comprises a second lumen and
a second reinforcement member placed within the second lumen to
provide a desired bending bias.
DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1(a) and 1(b) illustrate the arterial and venous
systems, respectively, of a human being;
[0011] FIG. 2 illustrates an abdominal region of a human being that
may have to be retracted during a surgical procedure;
[0012] FIG. 3 illustrates a retraction device of the present
invention positioned to relocate a portion of the intestines;
[0013] FIG. 4 illustrates a ring member of a retraction device of
the present invention formed in a first condition;
[0014] FIG. 5 illustrates a ring member of a retraction device of
the present invention formed in a second condition.
[0015] FIG. 6 illustrates a perspective view of a ring member of a
retraction device of the present invention formed in accordance
with another embodiment of the invention;
[0016] FIG. 7 illustrates a perspective view of a ring member of a
retraction device having a web structure formed on a back side of
the ring member;
[0017] FIG. 8 illustrates a perspective view of a ring member of a
retraction device having a web structure formed on a front side of
the ring member;
[0018] FIGS. 9-11 illustrate the steps of inserting a retraction
device of the present invention into an abdominal region of a human
body;
[0019] FIG. 12 illustrates a retraction device of the present
invention having a knitted web member as it is being held prior to
insertion into a surgical incision of a body;
[0020] FIG. 13 illustrates a retraction device of the present
invention having a woven web member as it is being held prior to
insertion into a surgical incision of a body;
[0021] FIG. 14 illustrates a cross-section view of a ring member
having an oval shape;
[0022] FIG. 15 illustrates a cross-section view of a ring member
having a square shape;
[0023] FIG. 16 illustrates a cross-section view of a ring member
having a circular shape;
[0024] FIG. 17 illustrates a cross-section view of a ring member
having an oval shape and an internal lumen;
[0025] FIG. 18 illustrates a cross-section view of a ring member
having a square shape and an internal lumen;
[0026] FIG. 19 illustrates a cross-section view of a ring member
having a circular shape and an internal lumen;
[0027] FIG. 20 illustrates a cross-section view of a ring member
having a pair of vertical ovals connected along the long axes;
[0028] FIG. 21 illustrates a cross-section view of a ring member
having a pair of vertical ovals connected along the short axes;
[0029] FIG. 22 illustrates a cross-section view of a ring member
having a connected pair of circles;
[0030] FIG. 23 illustrates a cross-section view of a circular ring
member having a lumen and a reinforcement member placed
therein;
[0031] FIG. 24 illustrates a cross-section view of a circular ring
member having a plurality of lumens and reinforcement members
placed within the lumens; and
[0032] FIG. 25 illustrates a cross-section view of an oval ring
member having a lumen and a biasing reinforcement member placed
within the lumen.
DESCRIPTION OF PREFERRED EMBODIMENTS AND BEST MODE OF THE
INVENTION
[0033] Surgical procedures often require that tissues and organs be
temporarily repositioned to provide a clear visual path for the
surgeon. For example, FIGS. 1(a) and 1(b) illustrate the arterial
and venous systems, respectively, of a human being that is often
covered or obscured by body tissues and/or organs that may need to
be repositioned during a surgical procedure. The obscuring tissues
and/or organs may be the abdominal content such as the intestines,
bowel, fat, etc., as illustrated in FIG. 2, which may need to be
relocated and held in a preferred position away from the point of
surgery. FIG. 3 illustrates a retraction device 10 of the present
invention that may be placed in a surgical area such as the
abdominal area to provide an unobstructed workplace 7., The
retraction device 10 operates to retract or reposition abdominal
content 5 away from the immediate workplace 7. Once the retraction
device 10 is properly placed in the abdominal area, the surgeon
will have a clear and reasonably unobstructed view of the operative
site.
[0034] Referring to FIGS. 4 and 5, the retraction device 10 of the
present invention comprises a ring member or wire element 15 that
is made of a malleable material. That is, the ring member 15 is
bendable and will stay bent in the shape or form in which it is
bent. The ring member 15 may include first bending portions 22, 23
and second bending portions 24, 25, 26 and 27. The first bending
portions 22, 23 may be used to fold the ring member 15 in half
bringing opposing portions 28, 29 toward each other as illustrated
in FIG. 5. Once the ring member 15 is folded in half along the
first bending portions 22, 23, the second bending portions 24, 25,
26 and 27 may then be bent to form substantially straight portions
200, 210 as illustrated in FIG. 4. It is appreciated that the ring
member 15 may have a plurality of bending portions and may be bent
in any shape depending on the needs of each particular surgical
procedure.
[0035] Referring to FIGS. 6-8, the ring member 15 of the retraction
device 10 is illustrated in a flat, low profile condition that is
suitable for insertion into a surgical incision. The ring member 15
has a front ring surface 30, a back ring surface 31, an inner ring
surface 32, and an outer ring surface 33. The ring member 15
further includes substantially parallel portions 34, 35 that may be
squeezed together forming the low profile condition. The ring
member 15 may support a membrane or web structure 60 such as a
fabric cover that is fixedly attached to the front ring surface 30
as illustrated in FIG. 8, the back ring surface 31 as illustrated
in FIG. 7, or to both the front and back ring surfaces 30 and 31.
It is foreseeable that the membrane 60 may be fixedly attached to
at least one of the inner ring surface 32 and the outer ring
surface 33.
[0036] The membrane or web structure 60 is preferably flexible such
that it can retain tissues and organs of different shapes and
sizes. Furthermore, the membrane or web structure 60 should be able
to retain both hard and soft tissues such as the muscles and bowel
during abdominal surgery. Specifically, the retraction device 10
and membrane 60 should be taut enough to securely hold and separate
hard tissues and organs and, at the same time, be flexible enough
to gently retain soft tissues and organs so as not to damage the
tissues and organs or affect their circulation. The membrane 60 is
preferably transparent so that tissues and organs are viewable
through the membrane. An advantage of this feature is it allows a
surgeon to view and ascertain the condition of a tissue or organ
during a surgical procedure.
[0037] Once the retraction device 10 is flattened, it may be
inserted into a surgical incision 102 as generally illustrated in
FIGS. 9-11. The retraction device 10 may be inserted through the
small incision 102 because it is flattened and the retraction
device 10 does not fully expand to its final shape until it is
partially or fully inserted to a point well within the abdominal
cavity. As illustrated in FIGS. 12 and 13, the retraction device 10
may be flattened by squeezing along sides 40, 45 of the ring member
15 in a first condition to facilitate insertion. It is appreciated
that the membrane 60 is also sized and configured to stretch and
recover in response to the shaping and reshaping of the ring member
15. The membrane 60 may be a bias-woven or knitted fabric that
exhibits elastic properties. Alternatively, the membrane 60 may be
constructed of any elastic material that responds to the shaping
and reshaping of the ring member 15.
[0038] The ring member may have different cross-sectional shapes
and configurations as illustrated in FIGS. 14-22. Each of the
cross-sectional shapes of the ring member provides a bending bias
in a preferred plane. For instance, the ring member of FIG. 14 has
an oval shape 50 providing a preference for bending along the long
axis over bending along the short axis., That is, a retraction
device having an oval ring member will be easier to bend and shape
along the long axis than along the short axis. In addition, the
region bent along the long axis is more resilient than the region
bent along the short axis. As a result, the strongest retraction
for this configuration is developed in that portion which comprises
a bend along the long axis. In another embodiment of the invention,
FIG. 15 illustrates a cross-section view of acting member having a
substantially square shape 52 that bends equally in two planes but
resists bending diagonally. An additional embodiment may also
include a ring member having a rectangular cross-section that
provides preferential bending in one plane and increased resistance
to bending in the opposite plane. The rectangular cross-section
would also substantially resist bending diagonally.
[0039] FIG. 16 illustrates a ring member having a circular
cross-section 54 where the entire ring member may bend equally in
all directions and that yields only to the forces applied by the
membrane 60. The circular cross-section 54 is therefore shapeable
to a greater degree in all directions than other geometries and may
allow the retraction device to be placed in awkward positions or to
be shaped in a manner that avoids delicate or sensitive structures.
It is appreciated that the ring member may have a cross-section of
any shape or geometry to provide a desired bending bias in a
preferred plane.
[0040] Referring to FIGS. 17-19, each of the ring members of FIGS.
14-16, respectively, may include an internal lumen 56 defining a
wall 57. The wall 57 may be circular or form a shape that provides
a desired bending bias. That is, the lumen 56 may impart a bending
bias in a similar manner as the various cross-sections of the ring
members discussed above. The relationship between the wall 57 of
the lumen 56 and a surface 58 of the ring member may also impact
the bending bias. For example, the thickness of the wall 57, i.e.,
the distance between the wall 57 and the surface 58 of the ring
member, may determine a bending bias. In another embodiment of the
invention, a reinforcement member 315 is placed within a lumen 305
to provide additional bending bias as illustrated in FIG. 23. The
reinforcement member 315 may comprise a plastic component, a metal
component or any combination thereof. The metal component may
include aluminum, titanium, stainless steel or any combination of
these compounds.
[0041] The reinforcement member 315 may be inserted and placed in a
preferred location along the lumen 305 so that a preferred bending
bias is developed in specific regions along the lumen 305 of the
ring member. For instance, referring back to FIGS. 4 and 5, a
preferred embodiment may require that a section or, sections 28, 29
of the retraction device 10 be substantially straight whereas
sections 24, 25, 26 and 27 are bendable. In this case, a rigid
reinforcement member may be placed along the sections 28, 29 to
keep these sections substantially straight. A second, more
resilient reinforcement member, may then be placed adjacent to the
first, more rigid reinforcement member within the lumen to prevent
the first reinforcement member from shifting position along the
lumen.
[0042] In yet another embodiment of the invention, the
reinforcement member 315 comprises a material having a "shape
memory" that enables the reinforcement member to return to its
desired shape. With this design, the reinforcement member may be
used with a retraction device that can be severely deformed during
insertion while maintaining the ability to return to its original
shape or condition. The shape memory materials, for example,
include a blend of nickel and titanium metals, which are also
commonly referred to as Nitenol.RTM.. In particular, a retraction
device would be constructed with a reinforcement member comprising
Nitenol.RTM., or the like, in a preferred shape and condition, the
retraction device would then be subjected to cold temperature so
that it becomes malleable or flexible. During use, the retraction
device would be bent to facilitate insertion into a preferred
location. Once inserted, the reinforcement member would warm to
body temperature and return to the preferred shape and condition,
thereby returning the retraction device to its original shape and
condition. An advantage of the reinforcement member of the
invention is it allows the ring member to be severely deformed,
even beyond the normal elastic limits of the material from which
the ring member is constructed.
[0043] Moreover, the reinforcement member has very good resistance
to kinking and permanent deformation because it is constructed of,
e.g., nickel-titanium alloys. That is, with this construction, the
reinforcement member of the invention placed within the lumen of
the ring member can prevent the ring member from being overstressed
or kinked. In addition, the reinforcement member may allow the
retraction device to be compressed or folded or otherwise reshaped
into a condition that allows it to be inserted into a body cavity
through the smallest possible surgical incision.
[0044] FIGS. 20-22 illustrate ring members 200, 210 and 220,
respectively, comprising a plurality of cords in accordance with
additional embodiments of the invention. The cords of ring members
200, 210 and 220 may be constructed according to previously
discussed geometric cross-sectional shapes or profiles. FIG. 20
illustrates the ring member 200 comprising a pair of oval cords
202, 204 that are vertically joined at point 206 along the long
axes of the cords 202, 204. FIG. 21 illustrates the ring member 210
comprising a pair of oval cords 212, 214 that are vertically joined
at point 216 along the short axes of the cords 212, 214. In yet
another embodiment of the invention, FIG. 22 illustrates the ring
member 220 comprising a pair of circular cords 222, 224 joined at
point 226 along the length of each of the cords 222, 224. Each of
the ring members 200, 210 and 220 exhibits bending preferences in
accordance with the individual cord geometries combined with the
overall geometry of the connected cords.
[0045] In each of the above embodiments, the ring members were
formed by combining two cords; however, it is appreciated that a
plurality of cord elements comprising three or more individual
cords may be combined to exhibit a desired bending preference. It
is further noted that each of the above constructions may be
achieved by extrusion of material having a cross-section that
resembles a combination of cords or by the actual connection of
individual cord elements. In addition, the combined cords may be
contained within the lumen of a covering tube or wrap.
[0046] As discussed above, FIG. 23 illustrates a cross-section view
of a ring member 300 having an internal lumen 305 and a
reinforcement member 315 placed within the lumen 305. The lumen 305
defines a wall 310. In this embodiment, the reinforcement member
315 has a cross-sectional shape or profile that is different from
the cross-sectional shape or profile of the ring member 300. For
example, the ring member 300 may have a circular cross-section
while the reinforcement member 315 may have a rectangular
cross-section. With a different cross-sectional shape or profile,
the reinforcement member 315 may impart a different bending bias on
the ring member 300. It is appreciated that the ring member 300,
reinforcement member 315 and wall 310 may have different
cross-sectional shapes or profiles from one another to provide a
desired bending bias in a preferred plane.
[0047] FIG. 24 illustrates a ring member 325 having a plurality of
internal lumens 330, 335 that may or may not communicate with one
another in accordance with another embodiment of the invention. The
ring member 325 further includes reinforcement members 350, 355
that may be inserted into the lumens 330, 335, respectively, to
provide a desired bending bias of a retraction device. In another
embodiment of the invention, FIG. 25 illustrates a ring member 370
having an oval cross section, a round or oval lumen 375, and a
rectangular reinforcement member 380 placed within the lumen 375.
The configuration of ring member 370 provides a bending bias that
allows the retraction device to be shaped or bent in a preferred
plane while providing great strength in an opposite plane.
[0048] Many alterations and modifications may be made by those
having ordinary skill in the art without departing from the spirit
and scope of the invention. Therefore, it must be understood that
the illustrated embodiments have been set forth only for the
purposes of examples and that they should not be taken as limiting
the invention.
* * * * *