Title: Soft tissue defect repair device
Abstract: An inguinal hernia repair device in the form of an implantable plug that is affixed at one end to the center region of a sheet of implantable material. The plug takes the form of a plurality of hollow members, arranged so as to be in substantially parallel relationship when implanted into a defect. The hollow members are preferably tubular members and are preferably bundled together by various means, such as bonding or wrapping a band or strand about the plurality of hollow members to maintain them in adjacent and contacting relationship during insertion into a defect.
Patent Number: 6,991,637 Issued on 01/31/2006 to Crawley, et al.
| Inventors:
|
Crawley; Jerald M. (Flagstaff, AZ);
Herman; John M. (Flagstaff, AZ);
Montgomery; William D. (Flagstaff, AZ);
White; Charles F. (Camp Verde, AZ)
|
| Assignee:
|
Gore Enterprise Holdings, Inc. (Newark, DE)
|
| Appl. No.:
|
465110 |
| Filed:
|
June 18, 2003 |
| Current U.S. Class: |
606/151; 623/11.11 |
| Current Intern'l Class: |
A61B 17/08 (20060101) |
| Field of Search: |
606/151-155
623/111.1,236.4,237.5
|
References Cited [Referenced By]
U.S. Patent Documents
| 4769038 | Sep., 1988 | Bendavid et al.
| |
| 4854316 | Aug., 1989 | Davis.
| |
| 4891263 | Jan., 1990 | Kotliar et al.
| |
| 4990158 | Feb., 1991 | Kaplan et al.
| |
| 5092884 | Mar., 1992 | Devereux et al.
| |
| 5098779 | Mar., 1992 | Kranzler et al.
| |
| 5116357 | May., 1992 | Eberbach.
| |
| 5147374 | Sep., 1992 | Fernandez.
| |
| 5254133 | Oct., 1993 | Seid.
| |
| 5258000 | Nov., 1993 | Gianturco.
| |
| 5356432 | Oct., 1994 | Rutkow et al.
| |
| 5425766 | Jun., 1995 | Bowald.
| |
| 5508036 | Apr., 1996 | Bakker et al.
| |
| 5593441 | Jan., 1997 | Lichtenstein et al.
| |
| 5716408 | Feb., 1998 | Eldridge et al.
| |
| 6113641 | Sep., 2000 | Leroy et al.
| |
| 6165217 | Dec., 2000 | Hayes.
| |
| 6166286 | Dec., 2000 | Trabucco.
| |
| 6180848 | Jan., 2001 | Flament et al.
| |
| 6241768 | Jun., 2001 | Agarwal et al.
| |
| 6270530 | Aug., 2001 | Eldridge et al.
| |
| 6309423 | Oct., 2001 | Hayes.
| |
| 6425924 | Jul., 2002 | Rousseau.
| |
| 2001/0027347 | Oct., 2001 | Rousseau.
| |
| 2003/0181988 | Sep., 2003 | Rousseau.
| |
| Foreign Patent Documents |
| 2222954 | Mar., 1990 | GB.
| |
Other References
U.S. Appl. No. 60/405,517, filed Jan. 23, 2002, Gingras.
|
Primary Examiner: Isabella; David J.
Attorney, Agent or Firm: Sheets; Eric J
Claims
We claim:
1. An implantable hernia repair device comprising:
a plurality of substantially hollow members;
wherein each substantially hollow member has a length and a midpoint along said length;
wherein each substantially hollow member has two ends and at least one of said
ends is open;
wherein each substantially hollow member is made of a bioabsorbable polymeric
material; and
wherein each substantially hollow member is attached to a substantially planar
base member at about said midpoint of said substantially hollow member.
2. The implantable hernia repair device of claim 1 wherein said substantially
planar base member is made of a bioabsorbable polymeric material in the form of
a self-cohering web.
3. The implantable hernia repair device of claim 2 wherein said self-cohering
web is made of a co-polymer of polyglycolic acid and trimethylene carbonate (PGA:TMC).
4. The implantable hernia repair device of claim 1 wherein said substantially
planar base member is in the form of a composite made of a non-bioabsorbable polymeric
material and at least one bioabsorbable polymeric material in the form of a self-cohering web.
5. The implantable hernia repair device of claim 4 wherein said self-cohering
web is made of a co-polymer of polyglycolic acid and trimethylene carbonate (PGA:TMC).
6. The implantable hernia repair device of claim 4 wherein said non-bioabsorbable
polymeric material is expanded polytetrafluoroethylene (ePTFE).
7. The implantable hernia repair device of claim 1 wherein said bioabsorbable
polymeric material of said substantially hollow member is in the form of a self-cohering web.
8. The implantable hernia repair device of claim 7 wherein said self-cohering
web is made of a co-polymer of polyglycolic acid and trimethylene carbonate (PGA:TMC).
Description
FIELD OF THE INVENTION
The present invention relates to the field of soft tissue defect repair devices,
and more particularly to the field of inguinal hernia repair devices.
BACKGROUND OF THE INVENTION
The repair of inguinal hernias is one of the most commonly performed surgical
procedures. Various prosthetic materials, typically porous to allow for tissue
ingrowth, have been provided in a variety of combinations, forms and shapes. Surgical
mesh, typically of polypropylene, has been commonly used, in some instances having
been rolled up into a cylindrical shape and inserted into the defect as a plug.
To reduce the tendency to migrate, these plugs are sometimes affixed at one end
to the center of a sheet of material. The sheet is used to overlap the defect and
for attachment to the adjacent tissue to reduce the likelihood of migration of
the device; see, for example, U.S. Pat. No. 5,116,357 to Eberbach and U.S. Pat.
No. 5,147,374 to Fernandez. These sheet-and-plug devices lend themselves to laparoscopic
repair as they may be inserted via a trocar wherein, after insertion, the edges
of the sheet may be fastened to the tissue adjacent the defect.
Hernia repair plug devices have been refined into a variety of shapes. One
such commercially available device is the PerFix® Plug from C. R. Bard, Inc.
(Murray Hill N.J.), described in U.S. Pat. No. 5,356,432 to Rutkow et al. and in
revised form by U.S. Pat. No. 5,716,408 to Eldridge et al. This device is in the
form of a pleated conical fabric mesh provided with additional mesh filler material
within the hollow of the cone; a sheet of material is not attached to the plug.
There are reported cases of devices of this type having migrated from the site
of the defect. Further, the mesh filler material is often not adequate to provide
the necessary axial stiffness and radial compliance to the conical form. These
attributes are desirable in order to aid in the insertion of the device into a
hernia defect (In the axial direction with regard to the device) and to better
enable the device to fill the defect in the radial direction.
U.S. Pat. No. 6,425,924 to Rousseau teaches two opposing conical mesh shapes
fitted together on a common axis and separated by one or more tubular components
also on the common axis, with the apices of the two cones pointed away from each
other. The apex of one cone is affixed to the center of a sheet of mesh material.
Various materials have been discussed for use as prosthetic plugs for the
repair of inguinal hernias. Polypropylene and polytetrafluoroethylene are commonly
discussed. Polypropylene is most often used in the form of a woven or knitted mesh
fabric to create the desired shapes. Polytetrafluoroethylene is typically used
in its porous, expanded form, usually noted as ePTFE. Other described non-absorbable
materials include cotton, linen, silk, polyamide (e.g., nylon 66) and polyethylene
terephthalate. Various absorbable materials have also been proposed, including
homopolymers and copolymers of glycolide and lactide, caprolactones and trimethylene
carbonates. See, for example, U.S. Pat. No. 6,113,641 to Leroy et al., U.S. Pat.
No. 6,180,848 to Flament et al. and U.S. Pat. No. 6,241,768 to Agarwhal et al.
While the literature contains suggestions to manufacture hernia repair plugs from
absorbable materials, the present inventors are unaware of any such absorbable
plugs having ever been made commercially available.
Further, there remains a need for a repair plug that possesses adequate
axial stiffness and radial compliance, and encourages rapid healing of the defect.
SUMMARY OF THE INVENTION
The present invention is an inguinal hernia repair device in the form of an implantable
plug that is affixed at one end to the center region of a sheet of implantable
material, with the length of the plug component oriented to be substantially perpendicular
to the sheet. The plug takes the form of a plurality of hollow members, arranged
so as to be in substantially parallel relationship when implanted into a defect.
The hollow members are preferably bundled together by various means, such as bonding
or wrapping a band or strand about the plurality of hollow members to maintain
them in adjacent and contacting relationship during insertion into a defect.
The hollow members are preferably tubular. The use of a plurality of tubular
members provides for good axial stiffness, beneficial during insertion into the
defect, in combination with good radial compliance due to the transverse compressibility
of the relatively thin-walled tubes. Preferably, a plurality of discrete, individual
tubes are used, with at least one end of each tube remaining open to allow rapid
access for body fluids and living cells. The open end of the tube is located at
the end of the plug opposite the end that is affixed to the sheet of implantable
material. As noted above, the plurality of tubes may be affixed at one end to the
center region of a sheet of implantable material. The purpose of the sheet is to
provide stabilization of the device by anchoring in the preperitoneal space, thus
ensuring proper placement of the plug.
In a preferred embodiment, the tubular members are about twice the desired length
of the plug component. Each tube is folded in half at the midpoint of its length,
with all tubes attached at the fold to the sheet component. The plurality of folded
tubes is then bundled together as described above.
The hollow members and the sheet component may be made from any suitable implantable
materials including both absorbable and non-absorbable materials. The entire device
may be made to be non-absorbable, or alternatively the entire device may be made
to be absorbable. The plug may be made to be absorbable and affixed to a non-absorbable
sheet, or vice versa. Absorbable materials are preferred, particularly for the
plug component, in that they are anticipated to elicit an inflammatory tissue response
that may result in more rapid healing. It is apparent that absorbable materials
with differing absorption rates may be used for various different components of
the hernia defect repair device.
If desired, the length of the hollow members may be reduced by trimming with a
cutting tool.
A preferred material for either or both of the sheet and plug components is a
copolymer
of poly(glycolide:trimethylene carbonate). The copolymer's polyglycolide component
is commonly abbreviated as PGA for poly(glycolic acid), the chemical byproduct
to which it degrades after hydrolysis. The poly(trimethylene carbonate) component
is commonly abbreviated as TMC, with the copolymer itself typically referred to
as PGA:TMC accompanied with relative percentage composition by weight. The preferred
PGA:TMC copolymer embodiment is in the form of a non-woven web as taught by Hayes
in U.S. Pat. Nos. 6,165,217 and 6,309,423. Another preferred embodiment involves
the use of a PGA:TMC plug with a sheet of ePTFE. Alternatively, the sheet may be
a composite sheet of ePTFE and PGA:TMC.
Either or both of the sheet component and the plug component may optionally
be treated (e.g., impregnated or coated) with any of various bioactive agents such
as antimicrobials or antibiotics. This is possible regardless of whether the material
used for the treated component is absorbable or non-absorbable.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a hernia repair device of the present invention.
FIG. 1A is a side view of a method of making the device of FIG. 1.
FIGS. 1B and 1C are top views further illustrating the method of FIG. 1A.
FIG. 2 is a perspective view of an alternative hernia repair device of the present
invention wherein a corrugated sheet is rolled to create the plug component.
FIGS. 2A and 2B are upper and lower perspective views of the corrugated sheet
prior to rolling up to create the plug.
FIG. 3 is an end view of an embodiment wherein the hollow members have hexagonal
transverse cross sections.
FIG. 4 is a perspective view of a hernia plug incorporating a barb component
around the circumference of the plug.
FIG. 5 is a perspective view of an embodiment of the hernia repair device incorporating
a layered sheet component
FIG. 5A shows a cross section of a composite sheet material for use with the
hernia repair device.
FIG. 6 is a longitudinal cross section that describes an alternative way to
accomplish the attachment of the plurality of hollow members to the sheet component.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of a hernia repair device
10 of the present
invention, wherein a plurality of hollow members
12 are provided in substantially
parallel relationship, creating plug
14. Preferably, hollow members
12
are tubular as shown in this embodiment. Optionally and preferably, one end of
plug
14 is affixed to the approximate center of a sheet
16 of implantable
material. Sheet
16 may optionally be provided with one or more slits
17
as desired to increase flexibility of sheet
16 and to better enable it to
be folded as necessary for insertion.
Hollow members
12 are not required to be tubular. Consequently, each
hollow member
12 is not required to have either a round or continuous (uninterrupted)
circumference. The hollow members may, for example, be tubes provided with a slit
along all or a portion of their length in order to further increase their radial
or transverse compressibility. While round transverse cross sections are preferred,
other shapes such as square, rectangular, hexagonal, elliptical, etc. may be used.
The transverse cross sectional shapes of the hollow members making up an individual
plug may all be the same, or two or more different transverse cross sectional shapes
may be used in combination to make up a single plug.
Hollow members
12 are preferably provided in a bundle that results
in their being substantially parallel to each other when inserted. By "substantially
parallel" in this context is meant that the hollow members vary only about +/-20
degrees, and more preferably only about +/-10 degrees, from perfectly parallel.
The hollow members may be maintained in a bundled relationship by various bundling
means, such as bonding together outer surfaces of adjacent hollow members or wrapping
a band
18 or strand about the plurality of hollow members
12 to maintain
them in adjacent and contacting relationship during insertion into a defect. The
bundled relationship may also result from the means used to affix the individual
hollow members
12 to a sheet
16.
For embodiments wherein plug
14 is fabricated from an absorbable material,
band
18 or any other suitable bundling means may be made from a material
that absorbs or dissolves faster than the material of plug
14. As such,
band
18 (or other bundling means) can be expected to absorb or dissolve
before the plug and will release the substantially hollow members to allow them
to better conform to the shape of the defect into which they were inserted when
contained by the bundling means.
Hollow members
12 have opposing ends wherein one end of each of the
plurality of hollow members remains open, thereby allowing access of body fluids
and cells into the luminal space of each hollow member. This is anticipated to
increase the rate of tissue attachment and healing, particularly if the hollow
members
12 comprise an absorbable material. The end of each hollow member
12 opposing the open end may be affixed to the central region of sheet
16.
Alternatively, as shown by FIG. 1A, each hollow member
12 may
be of a length that is about twice the length of plug
14, wherein individual
hollow members
12 are folded in half transversely (indicated by arrows
22)
at about the midpoint of their length, and attached at the fold to sheet
16.
Attachment of hollow members
12 to sheet
16 may be accomplished
in a variety of manners, depending on the configuration of hollow members
12
and the materials selected for the hollow members
12 and sheet
16.
The various affixing means include the use of adhesives suitable for the chosen
materials, various mechanical attachment means such as sewing with suitable materials
(e.g., suture materials), or welding means such as the appropriate application
of heat, solvent welding or by ultrasonic welding.
A preferred method of making the embodiment with folded hollow members is shown
in the top views of FIGS. 1B and 1C. FIG. 1B shows how a hollow member
12
may be provided with opposing notches
24 along its sides to better enable
additional hollow members to be stacked at the same attachment point as further
shown in FIG. 1C. Notches
24 reduce the interference resulting from multiple
hollow members
12 being attached at different angles at the common location.
It is apparent that a plurality of hollow members
12 may be attached at
the common location in this manner. The hollow members may be further provided
with a hole
26 at the center of the transverse fold line to accommodate
a temporary locating pin (not shown for clarity; for use only during fabrication
until the assembly is complete). Conversely, such a locating pin might be made
from a suitable absorbable material and remain in place as a part of the device construction.
FIG. 2 is a perspective view of an alternative hernia repair plug of the present
invention describing an embodiment wherein the hollow members
12 are in
the form of a corrugated material
32 that is rolled up or otherwise bundled
to form plug
14. The corrugated material
32 may be rolled up to create
the plug
14 or simply folded and bundled by wrapping with a band
18
or my other means described previously. Plug
14 is affixed to sheet
16
as described previously. For any of the embodiments described herein, the resulting
juncture of plug
14 and sheet
16 may be optionally reinforced by
a fillet component
39. Fillet
39 is simply a disc of suitable material
fitted around the base of plug
14 with enough interference to cause it to
fit tightly around the base of plug
14. Fillet
39 may be joined to
sheet
16 and plug
14 by various affixing methods described previously.
Alternatively, sheet
16, fillet
39 and band
18 may be formed
of a single piece.
FIGS. 2A and 2B show respectively upper and lower perspective views of a corrugated
sheet material suitable for rolling or otherwise bundling to create plug
14.
The corrugated sheet
32 comprises an upper layer
34 that is corrugated
and affixed to a planar lower layer
36 by any suitable means. The corrugations
result in a plurality of hollow members
12. Rolling of the corrugated sheet
32 to create plug component
14 is accomplished by rolling in a direction
transverse to the length of the corrugations. As shown by FIG. 2, this results
in the corrugations that provide the plurality of hollow members
12 extending
along the length of the cylindrical plug
14, parallel to the longitudinal
center line of the plug
14. The ends of the corrugations, opposite the end
of the plug that is subsequently affixed to sheet
16, remain open. The corrugated
sheet material
32 may be made from any desired absorbable or non-absorbable
material. These corrugated sheets are anticipated to have other implantable applications
in addition to use as the plug component of the hernia repair device described
herein. For example, the corrugated sheet material
32 may be useful in planar
form for the repair of various tissue defects where a somewhat flexible, but "reinforced"
sheet is desired. They may also have utility when rolled up to create a cylindrical
shape appropriate for other applications. The hollow members resulting from the
corrugated construction may be beneficial for various implantable applications.
Optionally, as shown by FIGS. 2A and 2B, corrugated sheet material
32
may be provided with one or more transverse corrugations
38 on the lower
surface of planar lower layer
36. When the corrugated sheet material is
rolled up to create plug
14 of FIG. 2, these corrugations
38 become
barbs or anchoring features extending circumferentially around the outer surface
of plug
14, as will be further described. Corrugations
38 must be
adequately flexible or distortable to allow the corrugated sheet
32 to be
rolled up in the direction of their length. If desired, corrugations
38
may be cut transversely at intervals along their length to better enable the corrugated
sheet
32 to be rolled up
FIG. 3 shows a top view of plug
14 wherein the hollow members
12
have hexagonal transverse cross sections. Plug
14 may result from bundling
a plurality of individual hollow members
12 or alternatively the members
may be provided by extrusion of a honeycomb form wherein adjacent hollow members
12 share common walls. It is apparent that hollow members
12 may
be provided in a variety of cross sectional shapes.
FIG. 4 shows a perspective view of a plug
14 provided with a band
18
that includes one or more barbs
42, intended to aid in the securement or
anchoring of plug
14 within a tissue defect. Additionally, barbs
42
may serve as the band component
18 that holds hollow members
12 together
in a bundle. These barb components
42 may be made in a variety of ways.
FIG. 4 shows two barbs made from discs of absorbable material and provided with
flanges
44 that enable the attachment of barbs
42 to the outer surface
of plug
14. These anchoring barbs
42 may also be made by providing
transverse corrugations
38 to corrugated sheet
32 prior to rolling
corrugated sheet
32 to form plug
14, as described previously and
shown in FIGS. 2A and 2B.
FIG. 5 shows a perspective view of an alternative embodiment wherein sheet
16
is provided in two or more layers which may optionally be attached (e.g., laminated)
together to create a composite sheet material
51 wherein the two layers
have different properties. In a preferred embodiment, composite sheet material
51 includes a non-absorbable layer
53 and an absorbable layer
55.
In use, absorbable layer
55 is placed in contact with the tissue adjacent
the defect. The non-absorbable layer
53 is preferably ePTFE and the absorbable
layer
55 is preferably PGA:TMC as taught by the Hayes patents referred to above.
FIG. 5A shows a cross section of an alternative composite sheet material
51
wherein the non-absorbable layer
53 has opposing surfaces
57 and
59 with different characteristics, for example, surface
57 being
rougher and/or more open than surface
59. Rougher surface
57 is intended
to encourage long term tissue attachment and ingrowth while smoother surface
59
is intended as a barrier to tissue attachment and ingrowth in order to prevent
or reduce the likelihood of tissue adhesions. If layer
53 is a porous material,
then smoother surface
59 may be provided with a suitably small pore size
while rougher surface
57 may be provided with a suitably larger pore size.
If desired, sheet
16 may be the result of attaching two different layers
together (as by bonding with an adhesive or melt bonding, or by mechanical fastening
means such as sewing) to achieve the desired different surface characteristics.
Rougher surface
57 is preferably provided with a covering or coating of
absorbable layer
55; when this layer
55 is bioabsorbed after a suitable
time, rougher surface
57 remains to provide the desired long term tissue
attachment. The presence of the bioabsorbable layer
55 is anticipated to
enhance healing as a result of the increased inflammatory tissue response to the
absorbable material. This may be desirable due to the chemically inert character
of the PTFE material (which consequently does little to elicit a biological reaction
from adjacent tissue when implanted by itself).
It is also apparent that the bioabsorbable layer
55 may be provided on
one surface of an ePTFE material having similar opposing surfaces, as well as providing
such an absorbable layer on one surface of a differentially-sided ePTFE material.
A preferred material for the non-absorbable layer
53 is Gore-Tex Dual-Mesh™
with Corduroy™ surface (Flagstaff Ariz.); this material has opposing surfaces
with different tissue attachment and ingrowth characteristics as described above.
FIG. 6 is a longitudinal cross section of a band
18 that has been flared
using suitable tooling to create the bioabsorbable layer
55 that may be
adhered to a non-absorbable layer
53 such as ePTFE. This describes an alternative
way to accomplish the attachment of the plurality of hollow members to the sheet component.
The following examples are provided for illustrative purposes only as examples
of particular embodiments of the described invention. As such, they are not intended
to be limiting.
EXAMPLE 1
This example describes the construction of a multiple tube hernia repair device
of the present invention as shown in FIG. 1. A triblock copolymer of 67%/33% PGA:TMC
(w/w) was acquired from US Surgical (Norwalk Conn.) and formed into a self-cohering
web as generally taught by Hayes in U.S. Pat. No. 6,165,217. Sheets of this copolymer
web material were formed into the 3 component types used in the construction of
this device.
A first component used for making this device was a tube formed from the self-cohering
web sheets that had an area density of approximately 8-10 mg/cm
2 and
a thickness of approximately 0.3 mm. The first step in making a tube was to cut
an approximately 25 mm wide strip of the self-cohering web material from a piece
of "unset" web sheet perpendicular to the belt direction used in forming the web.
This strip of "unset" web material was then wrapped lengthwise around an approximately
5 mm diameter stainless steel rod into a "cigarette roll" having an exposed edge
at the surface of the resulting tube extending along the length of the tube. This
material then self-cohered (as generally taught by Hayes in U.S. Pat. No. 6,165,217)
at the overlapping portion of the "cigarette roll" to form a 5 mm diameter tube
that was approximately 150 mm long. The strip of "unset" web material wrapped around
the stainless steel rod was then placed into a Baxter Scientific Products (McGaw
Park Ill.) constant temperature oven, model DK-43, for approximately 30 minutes
at 75° C. to "set" the web. The stainless steel rod and "set" web material
were then removed from the oven and allowed to cool. After cooling, the tube formed
from the now "set" web material was slipped off of the stainless steel rod. Both
ends of the "set" web tube were then trimmed leaving a tube that was approximately
90 mm long. Each tube was then placed onto a cutting die to create the notches
24 shown in FIG. 1B. A piece of 0.05 mm thick Mylar® sheet (DuPont
Company, Wilmington Del.) was placed over the tube to protect it from contamination.
A lightweight plastic-faced mallet was then used to lightly tap onto the tube through
the Mylar® sheet to cut out two notches 24 and centering hole 26
with the cutting die. Multiple tubes were made using these methods.
Another component used in making this device was a disc-shaped planar sheet
of approximately 38 mm in diameter. This disc-shaped planar sheet was made by first
taking two 50 mm square sheets of the "unset" self-cohering web material, each
with an area density of approximately 19 mg/cm
2 and approximately 1
mm thick. The two sheets were then stacked and placed in a restraining frame fitted
about the perimeter of the stacked sheets. The restrained web material was then
put into the Baxter Scientific Products constant temperature oven for approximately
30 minutes at 75° C. to bond the two pieces together to create a thicker sheet
and to "set" the web. After letting the web material cool to room temperature,
a disc was cut using an approximately 38 mm diameter circular cutting die punch.
A third component used in making this device was a band formed from an approximately
19 mm wide strip of copolymer web material. This copolymer web strip had an area
density of approximately 6-8 mg/cm
2 and a thickness of approximately
0.3 mm. This was made by rolling the strip of "unset" self-cohering web material
into a tube and then holding the overlapped ends together to allow for self-cohering.
The unset web material was then put into a Baxter Scientific Products constant
temperature oven for approximately 30 minutes at 75° C. The resulting band
was approximately 19 mm in diameter.
The device was then assembled by taking the disc first and centering it on a
centering pin extending from the center of the surface of an assembly fixture.
Then six of the tubes with notches and centering holes were placed on top of the
disc, also centering them on the centering pin. The tubes were arranged so that
they were equally spaced radially. The assembly was then placed onto a Branson
model 8400 ultrasonic welder (Branson Sonic Power Co., Danbury Conn.). The ultrasonic
welder had a Branson catenoidal horn, model 609-010-020 and an approximately 7.6
mm diameter tip that had an approximately 3.2 mm hole in the center to accommodate
the centering pin of the assembly fixture. The ultrasonic welder also had a 1:
0.6 booster. The downstop was set at approximately 0.4 mm with the downspeed set
at number 4. Pressure was set at approximately 0.08 MPa with the trigger set at
number 2; time was set to 0.2 seconds and the hold duration set at 1.0 seconds.
The ultrasonic welder was shut and activated 3 times for each device. After ultrasonic
welding, the six tubes were securely attached to the disc-shaped sheet. The tubes
were then folded up so that they were oriented to be substantially perpendicular
to the sheet component. The band component was then placed around the tubes to
hold them in a bundled configuration wherein the tubes were substantially parallel
to each other along their lengths. Four slits, spaced equally apart, were then
cut into the disc approximately three quarters of the way from the perimeter of
the disc to the center to facilitate insertion on the device into a hernia defect site.
EXAMPLE 2
This example describes the construction of a corrugated tube hernia repair device
of the present invention as shown in FIG. 4. A triblock copolymer of 50% PGA:TMC
(w/w) was made and formed into a self-cohering web as generally taught by Hayes
in U.S. Pat. No. 6,165,217. Sheets of this copolymer web material were formed into
some of the components used in the construction of this device. Other components
were made from expanded polytetrafluoroethylene (ePTFE) and from an absorbable
polymer adhesive, as described below.
A corrugated sheet was made by first placing a piece of the "unset" PGA:TMC web
sheet (approximately 100 mm square, about 0.2 mm thick having and having an area
density of approximately 4-6 gm/cm
2) onto a piece of PeCap® polyester
screen, product number 7-1000/45 (Sefar America, Monterey Park Calif.) material.
This screen material, by virtue of its surface texture, was used to restrain the
web material from dimensional change during the "setting" process. A fixture approximately
125 mm square was then placed onto the surface of the web sheet. The fixture was
provided with a set of multiple parallel rods with all of their centerlines in
the same plane, the rods being of approximately 2.4 mm diameter and spaced 5.3
mm center-to-center. These rods acted as mandrels for forming the hollow members
of the corrugation.
A second piece of "unset" web material of the same type as the first and of approximately
the same dimensions was then placed on top of the multiple parallel rod fixture.
Unsecured rods of approximately the same diameter as the rods in the fixture were
then placed on top of the second piece of "unset" web material, between the parallel
rods of the underlying fixture. These unsecured rods were individually pushed down
until they were in the same plane as the parallel rods of the underlying fixture.
The result was that the second piece of "unset" web material now formed the hollow
members of the corrugated sheet as it assumed a convoluted shape with self-cohering
contact points on the bottom piece of "unset" web material. Another piece of PeCap®
polyester screen was placed on top of the upper piece of "unset" web material to
restrain it from dimensional changes during the "setting" process. An aluminum
plate was placed on top of the polyester and then a weight was placed on top of
the entire assembly. The assembly was then placed into an oven at 80° C. for
30 minutes to "set" the web material. After "setting" in the oven, the web material
was allowed to cool and then removed from the fixture of multiple parallel rods.
Another component used in making this device was a sheet component with a
fillet and band for accepting a rolled up piece of corrugated web material. The
first step in making this sheet component was to provide a piece of "unset" web
sheet material approximately 50 mm square. A circular cutting die was used to cut
an approximately 13 mm diameter hole in the center of it. A 19 mm diameter aluminum
rod, approximately 150 mm long, was then fixtured to stand perpendicularly on a
flat aluminum plate. The piece of "unset" web material with a hole in its center
was then pushed over the aluminum rod. Since the hole in the "unset" web was smaller
than the diameter of the aluminum rod, and because the "unset" web material was
deformable, the difference in diameters between the hole in the web material and
the aluminum rod produced a flared hole in the "unset" web. The aluminum rod and
web material were then placed into an oven at 80° C. for 30 minutes to "set"
the web material. After allowing the web material to cool, it was removed from
the aluminum rod. The flared hole in the "set" web material formed a combined fillet
and band (as in FIG. 6) for accepting the corrugated web material. The piece of
"set" web material with the flange was then adhered to a piece of ePTFE material
by using an absorbable adhesive. The adhesive was made from a mixture of poly(85%
d,l-lactide-co-15% glycolide) (by mole; abbreviated as 85% d,l-PLA:15% PGA) mixed
1:4 by weight in acetone. It is apparent that this device could be made without
the ePTFE layer.
Barb components (FIG. 4, reference no. 42) were individually formed by
taking a piece of "unset" PGA:TMC web material approximately 65 mm long×13
mm wide and wrapping this lengthwise around a suitably tapered mandrel chosen to
shape the downwardly-angled barb. The strip of "unset" web material was temporarily
restrained to the mandrel by using a piece of PTFE pipe tape. The tapered mandrel
and restrained "unset" web material were then put into an oven at approximately
80° C. for approximately 30 minutes to "set" the web material. After the web
material was "set" in the oven, it was removed from the mandrel. Cutouts were then
made to the center region of the now tapered band to create flanges 44.
The device was then assembled by taking the corrugated sheet and rolling it into
a tube. Some of the absorbable adhesive was applied to the circumference of one
end of this tube and also to the walls of the filleted band portion to be attached
to the sheet component. The end of the tube with adhesive on it was then inserted
in a perpendicular orientation into the filleted band portion of the sheet component.
Absorbable adhesive was then applied to the interiors of a pair of anchoring barbs,
after which they were immediately fitted over the circumference of the plug component.
EXAMPLE 3
This example describes a method used to alter the stiffness and rate of bioabsorption
of a bioabsorbable device. A solution was made by mixing 65% d,l-PLA:35% PGA available
from Birmingham Polymers (Birmingham Ala.) in a 1:10 ratio by weight with acetone.
A device as described in Example 1 was dipped into this solution which imbibed
into the structure of the device, and then allowed to air dry. The resulting coated
device was stiffer than prior to imbibing. Alternatively, this solution could be
sprayed onto devices to achieve similar effects. Other copolymer ratios can also
be used to vary the stiffness and rate of bioabsorption. Also, other ratios of
polymer:acetone can be used to vary the final amount of polymer imbibed into or
sprayed onto the structure of the device.
While the principles of the invention have been made clear in the illustrative
embodiments set forth herein, it will be obvious to those skilled in the art to
make various modifications to the structure, arrangement, proportion, elements,
materials and components used in the practice of the invention. To the extent that
these various modifications do not depart from the spirit and scope of the appended
claims, they are intended to be encompassed therein.
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