U.S. patent application number 13/604190 was filed with the patent office on 2012-12-27 for tissue fasteners and related insertion devices, mechanisms, and methods.
This patent application is currently assigned to OPUS KSD INC.. Invention is credited to Kenneth S. Danielson, Edward R. Hall, Charles H. Rogers, Peter L. Stokes.
Application Number | 20120325889 13/604190 |
Document ID | / |
Family ID | 38895203 |
Filed Date | 2012-12-27 |
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United States Patent
Application |
20120325889 |
Kind Code |
A1 |
Danielson; Kenneth S. ; et
al. |
December 27, 2012 |
TISSUE FASTENERS AND RELATED INSERTION DEVICES, MECHANISMS, AND
METHODS
Abstract
A mechanism for deploying a fastener into skin tissue comprises
a first foot, a second foot, and an insertion device. The first
foot is configured to contact an external surface of the skin
tissue on one side of an incision or wound. The second foot is
configured to contact the external skin surface on the other side
of the incision/wound. The first and second feet are spaced apart
by a gap, and each is configured to allow the skin tissue from one
side of the incision or wound to be retracted thereover at an acute
angle to expose an inner surface of each of the sides of the
incision or wound. The insertion device releasably holds the
fastener and is movable to deploy the fastener into the exposed
inner surfaces from above and generally perpendicular to the
external skin surface.
Inventors: |
Danielson; Kenneth S.;
(Peacham, VT) ; Rogers; Charles H.; (Halifax,
MA) ; Stokes; Peter L.; (Boston, MA) ; Hall;
Edward R.; (Somerville, MA) |
Assignee: |
OPUS KSD INC.
Peacham
VT
|
Family ID: |
38895203 |
Appl. No.: |
13/604190 |
Filed: |
September 5, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12305071 |
Dec 16, 2008 |
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PCT/US2007/015418 |
Jun 29, 2007 |
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13604190 |
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60817858 |
Jul 1, 2006 |
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Current U.S.
Class: |
227/175.1 |
Current CPC
Class: |
A61B 17/08 20130101;
A61B 17/0682 20130101; A61B 2017/0641 20130101; A61B 17/064
20130101; A61B 2017/00004 20130101; A61B 2017/081 20130101 |
Class at
Publication: |
227/175.1 |
International
Class: |
A61B 17/068 20060101
A61B017/068 |
Claims
1. A mechanism for deploying a fastener into skin tissue having an
incision or wound, comprising: a first foot including a lower
surface that is configured to contact an external surface of the
skin tissue on one side of the incision or wound; a second foot
including a lower surface that is configured to contact the
external surface of the skin tissue on the other side of the
incision or wound, the first and second feet being spaced apart by
a gap, and each of the first and second feet configured to allow
the skin tissue from one side of the incision or wound to be
retracted thereover at an acute angle relative to the external
surface of the skin tissue to expose an inner surface of each of
the sides of the incision or wound in the gap; and an insertion
device that releasably holds the fastener and is adapted to be
moved to deploy the fastener into the exposed inner surfaces of the
incision or wound from above and generally perpendicular to the
external surface of the skin tissue.
2. The mechanism of claim 1 wherein the insertion device is
operatively coupled with the first and second feet and adapted to
be moved between a first position and a second position along a
path generally perpendicular to the lower surfaces of first and
second feet such that moving from the first position to the second
position translates the insertion device through the gap and
returning to the first position releases the fastener to leave the
fastener embedded in the exposed inner surfaces.
3. The mechanism of claim 1 wherein the fastener is
bioabsorbable.
4. A method of deploying a bioabsorbable fastener into two sides of
an incision or wound in skin tissue, comprising: everting each of
the two sides of the incision or wound to expose an inner surface
of each of the sides such that the inner surfaces face in a
direction generally perpendicular to an external surface of the
skin tissue; inserting the bioabsorbable fastener into the exposed
inner surfaces of the incision or wound from above and generally
perpendicular to the external surface of the skin tissue; and
releasing the everted sides of the incision or wound to leave the
bioabsorbable fastener below the external surface of the skin
tissue.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of, and claims priority to and the
benefit of, Nonprovisional U.S. patent application Ser. No.
12/305,071, which is a US national stage application of
International Patent Application Number PCT/US2007/015418 filed on
Jun. 29, 2007. International Patent Application Number
PCT/US2007/015418 claims priority to and the benefit of Provisional
U.S. Patent Application Ser. No. 60/817,858 filed on Jul. 1, 2006.
The entirety of the contents of each of these three applications is
incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates to mechanisms for and methods of
deploying fasteners into skin tissue having an incision or wound.
The mechanisms are, more particularly, for deploying bioabsorbable
fasteners that appose the two sides of the incision or cut in the
human skin (or other tissue) to allow healing.
BACKGROUND INFORMATION
[0003] Sutures for closing incisions in human skin are well known.
The sutures are applied by physicians using a needle to pull the
suture material through the two sides of the incision. The suture
material is tied which fastens or apposes the two sides to allow
healing. The suture material may be non-absorbable such as silk,
polyester, etc. or it may be formed from bioabsorbable materials
such as polyglycolic acid polymers. Applying sutures in this way
requires skill and dexterity. Also it exposes the operator to
possible needle stick injury. For these reasons and because of the
time that it takes to apply sutures, other fasteners have been
developed, the most popular of these being referred to as
staples.
[0004] Surgical staples are made of non-reactive metals and are
strong enough to hold the tissues together once the ends of the
staple have been bent inward. Although staples are faster and safer
to apply than sutures, they have disadvantages. Because they
penetrate the epidermis and remain exposed on the surface of the
skin, they (i) present an opportunity for infection, (ii) the wound
must be kept dry until the staples are removed (5-7 days), and
(iii) the patient must return for removal which requires another
device, is time consuming, inconvenient and can cause
discomfort.
[0005] Recently staples have been made of bioabsorbable plastics so
that they can be applied below the skin and will not require
removal. To have sufficient strength to penetrate the skin and
secure the tissue, the plastic typically must be much larger in
cross section than an equivalent metal staple. For example, a
staple wire with diameter of 0.65 mm in metal would need to have a
diameter of 2.5 mm to have the same bending or buckling strength if
made of plastic. Hence, the bioabsorbable staples tend to be bulky
and to occupy significant volume within the wound. In addition, the
means of applying the plastic staple may be complex.
[0006] U.S. Pat. No. 6,726,705 relates to a mechanical method and
apparatus for fastening tissue.
SUMMARY OF THE INVENTION
[0007] There exists a need for a biodegradable or bioabsorbable
fastener that can be easily deployed from above the incision or
other wound and that can be used to close minimally invasive
surgery incisions as short as 5 mm and that will hold the tissue
apposed, lie below the surface of the skin, and occupy a small
volume within the wound.
[0008] In one aspect, the invention generally relates to a tissue
fastener comprising a bridge section and first and second leg
sections. The bridge section includes a first portion and a second
portion. The first leg section is integral with the bridge section
and extends from the first portion of the bridge section. At least
a portion of the first leg section defines a first lumen extending
therethrough such that the first leg section is cannulated. The
second leg section also is integral with the bridge section, and it
extends from the second portion of the bridge section. At least a
portion of the second leg section defines a second lumen extending
therethrough such that the second leg section also is cannulated.
The bridge section and the first and second leg sections comprise a
single piece of material.
[0009] In accordance with this aspect of the invention, various
embodiments are possible. For example, the single piece of material
can be bioabsorbable, and the bioabsorbable material can be a
polyglycolic acid polymer, a copolymer, or a blend of polymers.
Also, each of the first and second leg sections can include at
least one barb, and the at least one barb can be oriented in a
direction away from the surface of tissue after the tissue fastener
is inserted into the tissue. In general, the barbs are oriented to
resist dislodgement from tissue after the tissue fastener is
inserted into the tissue. In addition, the bridge section can be
sufficiently flexible to allow the first and second leg sections to
spread angularly after the tissue fastener is inserted into tissue.
And, a portion of each of the first and second leg sections can be
tapered. Also, the bridge section can include a frangible connector
for releasably connecting the bridge section to another tissue
fastener.
[0010] In another aspect, the invention generally involves a tissue
fastening system comprising the tissue fastener described above and
also an insertion device for deploying the tissue fastener into
tissue.
[0011] In accordance with this other aspect of the invention,
various embodiments also are possible. For example, the insertion
device can be part of a larger insertion mechanism that an operator
(such as a surgeon) manually operates to move indirectly the
insertion device to deploy the tissue fastener from above the
tissue in a generally perpendicular orientation in relation to the
surface of the tissue. Also, the insertion device can include a
first needle for insertion into the first lumen of the cannulated
first leg section and a second needle for insertion into the second
lumen of the cannulated second leg section, and these needles can
be substantially parallel to each other.
[0012] In yet another aspect, the invention generally features a
tissue fastening system comprising the above-described tissue
fastener and an insertion mechanism for deploying the tissue
fastener into tissue. The insertion mechanism includes an insertion
device, and the insertion device is utilized to deploy the tissue
fastener from above and generally perpendicular to the tissue.
[0013] In still another aspect, the invention generally involves a
tissue fastening system comprising the above-described tissue
fastener, an insertion device for deploying the tissue fastener
into tissue, and compressing forceps that include first and second
arms where each of the arms includes a surface for contacting the
tissue. The first and second arms can include a pair of movable
tissue compressing arms.
[0014] The present invention also generally relates to a cannulated
fastener device made from bioabsorbable plastic materials.
Accordingly, the bioabsorbable fastener comprises two legs
cannulated to receive an insertion device (which can be at least
partially metallic), each leg having at least one barb oriented to
resist retraction of the fastener after deployment into tissue. The
two legs are connected by a flexible bridge and initially oriented
parallel to each other. The bridge may be formed from a
bioabsorbable polymer that becomes flexible at body temperature
and/or can be shaped in a manner, such as having a rectangular
cross-section, which bends easily and allows the legs to spread
angularly after insertion.
[0015] A fastener according to the invention is designed to hold
the tissue in apposition while remaining totally below the surface
of the skin. Accordingly, one preferred target area for each leg is
the deep surface of the dermis between 1 and 4 mm, and preferably
between 2 and 3 mm displaced from the cut surface in one
embodiment. After the opposing walls of the wound (or other tissue
slit or opening) are pulled apart and everted to expose the inner
surface of each of the walls upward, needles or other sharp
injection members of the insertion device penetrate the deep
surface of the everted dermis and drive the fastener and its barbs
into the body of the dermal tissue from above the surface of the
skin. After insertion of the bioabsorbable fastener, the delivering
needles are withdrawn, leaving the fastener within the tissue and
the tissue is released to allow the skin to relax as the legs of
the embedded fastener open outwardly. The resulting final
orientation of the embedded fastener brings the barbs into tension
when the two sides of the tissue are apposed and slightly everted
with the fastener resting completely below the surface of the
skin.
[0016] A fastener according to the invention is designed to occupy
a small volume within the wound to promote wound healing.
Accordingly, the legs of the bioabsorbable fastener are cannulated
with very thin side walls having a radial thickness between 0.1 and
0.5 mm, for example, and preferably between 0.2 and 0.3 mm in one
embodiment. The thin walls of the legs are tapered inwardly at
their distal ends so that they reduce the penetrating force needed
to insert them into the tissue. Strength to penetrate human tissue
is provided by an insertion device, which has dual metallic needles
in one embodiment, dimensioned so that they slide into the two legs
of the fastener and exit the tapered ends of each leg. The dual
needles are sharpened at their distal ends thus providing a sharp
point for entry into the tissue to be apposed.
[0017] A fastener made according to the present invention holds the
two apposing tissues together by tension forces between the barbs
at the ends of each leg. A bioabsorbable material, such as a
polyglycolic acid polymer, a copolymer, or a blend of polymers, is
chosen to have mechanical properties such that each cannulated leg
has a tensile breaking strength of 2.5 pounds or greater in one
embodiment. One bioabsorbable material is polyglycolide, which is
also known as polyglycolic acid or (PGA), and it has a glass
transition temperature of 35-40.degree. C., which is sufficiently
low to allow the fastener, especially the bridge structure
connecting the two legs, to become flexible at body temperature.
Since the present fasteners operate in tension, while other staples
operate by their structural strength, compressive strength, or
resistance to deforming, fasteners according to the present
invention do not need to be as massive, thus reducing the volume of
foreign material in the wound.
[0018] Fasteners according to the invention are designed to be
deployed from above the skin. Accordingly, one embodiment of the
present invention provides specially adapted compressing forceps or
presser feet that are used in conjunction with tissue manipulators
to evert the tissues to be apposed and thereby turn them upwards
and also to compress them to a predetermined dimension suitable for
accepting the fastener. The fastener, mounted on the insertion
device, then may be manually driven into the tissue in the
predetermined space between the compressing forceps. In an
alternate embodiment, the compressing forceps can be used in
conjunction with a stapler-like device to deploy the fasteners. The
stapler-like device may be manually positioned with respect to the
compressing forceps using indexing pins or other features suitable
for mechanically referencing one part to another.
[0019] Fasteners according to the invention are designed to be
deployed easily and reproducibly without requiring special
dexterity. An insertion mechanism may be used (in conjunction, for
example, with tissue manipulators) to provide a way to reproducibly
position the surfaces of the dermal layer and to deploy the
fastener. The insertion mechanism desireably is able to carry
multiple fasteners of the present invention, and comprises a means
for loading the fasteners one at a time onto the insertion device
by passing the sharpened needles of the insertion device through
the legs of the fastener. Alternatively, the insertion mechanism
can carry a cartridge of insertion devices each pre-loaded with a
bioabsorbable fastener of the present invention, and means for
moving the insertion devices one at a time into the translating
mechanism to drive into the tissue and then retract the insertion
device thereby leaving the fastener in place. The insertion
mechanism has two features (indentations or slots) into which two
manipulators are positioned, each having pinched one side of the
tissue to be apposed. Tissue compressing arms, located on either
side of the insertion mechanism, move in unison when the user
presses an actuating lever. The tissue compressing arms descend,
opposing the tissue below the points held in place by the tissue
manipulators, and positions the two sides of the tissue against one
another. The insertion mechanism further comprises an actuation arm
attached to the insertion device which allows only vertical
translation synchronized to deploy the insertion device carrying
one of the fasteners after the tissue is positioned. This vertical
translation may be driven by electromotive, spring, or manual force
through coupling arms, or other means known in the art for driving
staples. The final downward position may be constrained by a
mechanical stop adjusted to deploy the fastener to a desired depth
in the tissue. In an alternate embodiment, the final downward
position is determined by a limiting spring, which is chosen to
compress significantly only when a force comparable to the maximum
force to be applied to the insertion device to seat the fastener
fully within the everted tissue is applied.
[0020] Needles of the insertion device do not need to be exposed
until the deployment mechanism is activated, thus the risk of
needle sticks to the operator is minimized. At the completion of
the inserting actions accomplished by any of the above or other
means, the insertion device is retracted leaving the fastener in
place in the tissue. Further retraction of the actuation mechanism
allows the insertion mechanism to be withdrawn and the tissue
compressing arms to reopen. As a final step of a method to deploy
the fastener, the user urges the two sides of the tissue that have
been held with the tissue manipulators toward the line of
apposition until the cut surfaces come into contact with one
another, and then releases the epidermis.
[0021] Indications for the bioabsorbable fastener of the present
invention include minimally invasive surgical skin wound closure as
well as longer skin wound closure (both surgical and accidental).
Also, approximating other tissues, such as intestines, arteries and
veins, or any soft tissue apposition in an everted or inverted
orientation such as anastamoses, are procedures that would benefit
from the present invention. While the present invention is
described utilizing bioabsorbable materials, it will be appreciated
that in some circumstances many of the benefits of the fastener can
be achieved using non-bioabsorbable materials.
[0022] Accordingly, an aspect of the invention involves a fastener
for use in apposing body tissues, said fastener being fabricated
from bioabsorbable material such as a polyglycolic acid, a
copolymer, or a blend of polymers. The fastener is formed to have
two legs, each leg having an inwardly tapered distal end and barbs
oriented to resist dislodgement of the fastener after insertion
into tissue. The two legs are connected by a flexible bridge at
their proximal end and cannulated to receive an insertion device,
which extends through the legs and exits the distal end exposing a
sharp point to facilitate insertion of the fastener into
tissue.
[0023] Another aspect of the invention relates to a method for
apposing the tissues in closing a surgical incision or wound
utilizing a bioabsorbable fastener of the present invention, tissue
manipulators, and an insertion device. The method comprises use of
tissue manipulators to pull upwards and index the two sides to be
apposed with respect to compressing forceps, such procedure being
adapted to roll the surfaces of the dermis from a horizontal to a
vertical orientation while compressing the tissue together. The two
sides of the incision or wound are held in this upward facing
orientation while the bioabsorbable fastener is inserted from
above.
[0024] Still another aspect of invention comprises an insertion
mechanism able to carry multiple fasteners of the present
invention, at least one insertion device having two sharpened
needles inserted into the cannulated legs of the fastener to
facilitate penetration of the tissue, mechanical means to reference
the two sides of the tissue to be apposed, to compress and hold the
tissue in a favorable orientation for receiving the fastener, and a
translating mechanism to drive and then retract the at least one
insertion device into the tissue thereby leaving the fastener in
place.
[0025] Disclosed and contemplated embodiments of tissue fasteners,
insertion mechanisms, insertion devices, and methods for closing a
wound (whether created surgically or otherwise) with the fastener,
in accordance with the invention, are different in a variety of
ways than known surgical staples and related stapler devices. For
example, embodiments of tissue fasteners according to the invention
are structurally distinct from known staples. Also, as another
example, the inventive fasteners are deployed in a distinct way. As
yet another example, fasteners according to the invention, once
deployed into the body hold wounds together by tension.
[0026] Other aspects, objects, and advantages of the invention are
included herein even if not expressly called out. The disclosed
embodiments are exemplary and not limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In the drawings, like reference characters generally refer
to the same parts throughout the different views. Also, the
drawings are not necessarily to scale, emphasis instead generally
being placed upon illustrating the principles of the invention. In
the following description, various embodiments of the present
invention are described with reference to the following drawings,
in which:
[0028] FIG. 1 shows a typical incision in the skin of the type that
may be closed using the present invention;
[0029] FIG. 2 is a cross section of incision shown in FIG. 1 taken
along the section 2-2';
[0030] FIG. 3a shows the insertion device positioned to be inserted
into the legs of the bioabsorbable fastener of the present
invention;
[0031] FIG. 3b shows the bioabsorbable fastener of the present
invention positioned on the insertion device ready to be
deployed;
[0032] FIG. 4a is a cross section of the skin tissue of FIG. 2
raised by pulling upwards using tissue manipulators;
[0033] FIG. 4b is a cross section similar to FIG. 4a showing the
tissue further oriented for receiving the fastener of the present
invention and the insertion device with a bioabsorbable fastener
ready to be deployed;
[0034] FIG. 5a shows a cross section of skin tissue similar to FIG.
4b with the bioabsorbable fastener and insertion device
deployed;
[0035] FIG. 5b shows the cross section of skin tissue of FIG. 5a
after the insertion device has been removed;
[0036] FIGS. 6a and 6b show the cross section of skin tissue of
FIG. 5b after the tissue manipulator has been removed and the
bridge connecting the legs of the bioabsorbable fastener has
relaxed, for two possible embodiments of the bioabsorbable
fastener;
[0037] FIGS. 7a through 7e show alternate embodiments of the
bioabsorbable fastener;
[0038] FIG. 7f shows a plurality of fasteners molded into an
assembly in which linked components interconnect the bridges of the
fasteners;
[0039] FIGS. 7g, 7h, and 7i show assemblies of fasteners and
insertion devices created by an insert molding process;
[0040] FIG. 8 shows a cross section of skin tissue similar to FIG.
5 with a specially adapted compressing forceps compressing the
dermal tissues to be apposed;
[0041] FIGS. 9a through 9d show the process illustrated in FIGS. 4
and 5 implemented with the aid of a mechanism that coordinates the
several steps;
[0042] FIG. 10 shows a modification of the arrangement depicted in
FIG. 8, now equipped with presser feet for approximating the cut
surfaces of the tissue to be repaired;
[0043] FIG. 11 is a perspective view of an alternate embodiment of
a hand-held insertion mechanism used to insert the bioabsorbable
fastener;
[0044] FIG. 12a shows a cross section of skin tissue as in FIG. 2
in which the cut surfaces of the tissue are raised and reflected
over the presser feet by tissue manipulators, orienting the cut
surfaces for receiving the bioabsorbable fastener, shown mounted on
an insertion device;
[0045] FIG. 12b shows the cross section of skin tissue as in FIG.
12a, with the bioabsorbable fastener and insertion device deployed
and penetrating through the dermal layer;
[0046] FIG. 12c shows the cross section of skin tissue as in FIG.
12b after the insertion device has been removed;
[0047] FIGS. 12d and 12e show the cross section of skin tissue as
in FIG. 12c after the tissue manipulators have been removed and the
bridge connecting the legs of the bioabsorbable fastener has
relaxed, FIG. 12e showing a fastener with additional axially
directed barbs as in FIG. 7b;
[0048] FIG. 13a shows a perspective view of an individual
fastener;
[0049] FIG. 13b shows a top view of the fastener of FIG. 13a;
[0050] FIG. 13c shows a front view of the fastener of FIG. 13a
through section A-A of FIG. 13b, and also shows a partial cutaway
view of one of the legs of the fastener; and
[0051] FIG. 13d shows a side view of the fastener of FIG. 13a
through section B-B of FIG. 13c.
DESCRIPTION
[0052] With reference to FIG. 1, an opening 50 in the skin 53 is
shown such as may be caused by an incision or wound. For purposes
of this description, the "upward" or vertical direction is that
direction generally perpendicular to the surface of the skin 53,
even if that surface is curved or facing in another direction.
Human skin is comprised of layers that are indicated in FIG. 1 and
seen in FIG. 2 which is a cross-section taken along line 2-2'. The
outermost layer, the epidermis 56 consists of mostly dead cells.
Below this is found the dermal layer 59 that is a thin layer of
strong living tissue and then the subcutaneous layer 62. While the
present invention will be described with reference to openings in
human skin 53, it will be understood that approximating other
tissues such as intestines, arteries and veins, or any soft tissue
apposition in an everted or inverted orientation such as
anastamoses, can benefit from the present invention.
[0053] In FIG. 2, the line of apposition 65 represents a vertical
plane that runs longitudinally bisecting the opening 50 in the skin
53. To facilitate the healing process, the surfaces 68a and 68b of
the living dermal layer must be brought together and held in close
contact for several days.
[0054] In FIG. 3a and FIG. 3b, the fastener 71 of the present
invention is positioned in relation to the driving end of an
insertion device 74. The fastener 71 is mounted onto the insertion
device 74 for purposes of deploying the fastener into tissue. The
fastener 71 is made from bioabsorbable plastic materials such as
polyglycolides and comprises two legs 77a, 77b cannulated to
receive the insertion needles 79a, 79b of the insertion device 74.
In FIG. 3a, the insertion device 74 is shown aligned for insertion
into the fastener 71, while FIG. 3b shows the two components fully
assembled, as would be the case prior to deployment into tissue.
The needles 79a, 79b of the insertion device 74, when fully
inserted in the legs 77a, 77b as shown in FIG. 3b, extend a small
distance beyond the distal end of legs 77a, 77b to expose sharp
ends 80. The sharp ends 80 facilitate penetration into tissue. The
sharp ends 80 can be, for example, tapered similar to a typical
pencil point, as shown in FIG. 3b and other figures. If the sharp
ends 80 are tapered, each of them has a centered point, as would a
sharpened pencil. The sharp ends 80 instead can be, for example,
beveled as shown in FIGS. 7g-7i. Each leg 77a or 77b of the
fastener 71 has at least one barb 83 oriented to resist retraction
of the fastener 71 after deployment into tissue. The two legs 77a,
77b are connected at the proximal end by a flexible bridge 86.
[0055] FIG. 4a shows the skin 53 being pulled upward by tissue
manipulators 91a, 91b while being urged toward the line of
apposition 65 by arms 94a, 94b. Continued pulling by tissue
manipulators 91a, 91b as shown in FIG. 4b and urging by arms 94a,
94b causes the surfaces 68a, 68b of the dermal layer to move from a
generally vertical orientation facing each other, to a generally
horizontal one facing upward pulling it away from the subdermal
tissue and exposing the underside of the dermal layer. In FIG. 4b,
the insertion device 74 carrying the fastener 71 is shown in the
correct orientation prior to inserting the fastener 71 into the
tissue.
[0056] FIG. 5a shows the insertion device 74 with fastener 71 after
insertion showing the entry point for the legs 77a, 77b into the
under side of the dermal layer 59. The displacement 97 indicated
for leg 77b (and similar for leg 77a) is the distance along the
underside of the dermal layer 59 from the cut surface 68b to the
insertion point for leg 77b. This displacement 97 of the insertion
point is approximately half the length of the bridge 86 where it
connects the two legs 77a and 77b. We have found that this
insertion technique allows the barbs 83 to engage the tissue at a
depth sufficiently far from the surfaces 68a, 68b so that the
bridge 86 can provide a tension holding the tissues together after
the insertion device 74 is removed from the fastener 71 as shown in
FIG. 5b.
[0057] FIG. 6 shows the tissues of FIG. 5b after the tissue
manipulators 91a, 91b and arms 94a, 94b have been removed. The
flexible bridge 86 bends easily and allows the legs 77a, 77b to
spread angularly after the insertion device 74 is removed. A small
amount of curvature may remain in the bridge 86, as it is desirable
that the tissue be slightly everted where it meets along the line
of apposition 65.
[0058] FIGS. 7a through 7e show alternate embodiments of the
fastener 71 of the present invention differing principally in the
position and number of barbs 83. The barbs may further lie in any
plane that passes through the axis of the leg, either to facilitate
manufacturing (e.g. using injection molding tooling) or to enhance
the fastener's retention strength in tissue. However, it is
desirable that no barb should be placed such that its pointed
element, once the fastener is in place, is directed upwards towards
the skin surface 53. The fastener in FIG. 7b adds axially directed
barbs 98 at the top of each leg that can supplement the retention
strength of the other barbs 83 when they are engaged as shown in
FIG. 6b.
[0059] While the present description shows the fasteners
individually, it will be understood that they may be placed in an
assembly containing a plurality of fasteners held in relation to
one another by a cartridge means or molded in such an assembly with
inter connecting frangible plastic components 99, as shown in FIG.
7f. While the inter-connecting components 99 are shown for only one
of the alternate embodiments it will be understood that components
99 can be added to other embodiments of FIGS. 7a to 7e.
[0060] To facilitate molding of the fasteners of the present
invention either singly or in multiples, the legs 77a, 77b may be
oriented in the open position similar to that shown in FIG. 7e with
the bridge 86 straightened and subsequently bent to the
configuration as shown in FIG. 7a prior to deployment.
[0061] In one embodiment, fasteners 71 can be made using a
manufacturing process known as insert molding, as shown in FIGS. 7g
through 7i. Referring to those figures, the insertion device 74' is
fabricated prior to molding fastener 71. Needles 79'a and 79'b are
installed in cylindrical shoulders 90a and 90b respectively which
are part of yoke 92. Insertion device 74' is inserted into a
molding cavity in an injection molding process, and the
bioabsorbable polymer is injected around it to form fastener 71.
FIG. 7h shows the combination of insertion device 79' and fastener
71 as molded by this process. FIG. 7i shows how the insert molding
process described above can be used in a multi-cavity tool to yield
multiple fasteners each connected to another by frangible
components 99'.
[0062] FIG. 8 shows compressing forceps 101 that facilitate
insertion of the bioabsorbable fastener of the present invention.
The compressing forceps 101 have at the distal ends of each arm
103a, 103b, half-cylinder components 106a, 106b with features 109a,
109b (indentations or slots) at the top of the half-cylinder
components 106a, 106b into which tissue manipulators 91a, 91b can
be positioned. The user places the compressing forceps 101 so that
each cylindrical component 106a, 106b presses against the skin 53
on either side of the line of apposition 65 with the axes of the
cylinders parallel to incision or wound. Tissue manipulators 91a,
91b are used to pinch each side of the tissue to be apposed and
pull it upwards indexing the tips of the manipulators in the
features 109a, 109b at the top of the cylindrical component. The
compressing forceps 101 are then squeezed until stopping elements
112a, 112b in the forceps meet to restrict further compression. The
stopping elements 112a, 112b are designed to allow the tissues to
be compressed leaving a predetermined distance of 4-8 mm separating
the inner surfaces of the cylindrical components (dimension A in
FIG. 8). This configuration assures that the cut surfaces 68a, 68b
of the dermal layer are displaced away from the insertion device
exposing the underside of the dermal layer and orienting it upwards
to accept the fastener from above. The user deploys the fastener
using the insertion device by penetrating the compressed dermal
tissue between the two cylindrical components 106a, 106b. The
compressing forceps 101 may also have indexing means to align an
insertion device (not shown) so that it penetrates the underside of
the dermal tissue equally spaced between the cylindrical components
106a, 106b.
[0063] FIGS. 9a-9d show an insertion mechanism 200 which provides a
means for deploying the fastener 71 from above the skin 53. An
alternate embodiment of the fastener 71, described above in FIG.
7b, is depicted being used with the insertion mechanism 200.
Accordingly, one method uses an insertion mechanism 200 in
conjunction with tissue manipulators 91a, 91b, to provide a means
to coordinate the relative positions of the driving head of the
insertion device 74, the tissue compressing arms 203a, 203b and the
dermal layer. The tissue manipulators 91a, 91b are manually used to
pinch the epidermis 56 and pull upwards on the two sides of the
incision. The distal ends of the tissue manipulators 91a, 91b are
then positioned in index cavities 206a, 206b which positions the
cut surfaces 68a, 68b of the dermal layer away for the point of
penetration on either side of the line of apposition 65. The tissue
compressing arms 203a, 203b are movably attached to the insertion
mechanism 200 as for example, with pivoting elements 209a, 209b.
The tissue compressing arms 203a, 203b, located on either side of
the insertion mechanism 200, move in unison when the user presses
an actuating lever (not shown). At the distal ends of the tissue
compressing arms 203a, 203b there are cylindrical elements 213a,
213b which contact the tissue below the points held in place by the
tissue manipulators 91a, 91b, and compress the two sides of the
tissue against one another. The insertion mechanism 200 further
comprises an actuation arm 216 attached to the insertion device 74
which allows only vertical translation synchronized to deploy the
insertion device 74 carrying one of the fasteners 71 after the
tissue is compressed. This vertical translation may be driven by
electromotive, spring, or manual force through coupling arms, or
other means known in the art for driving staples. The final
downward position may be constrained by a mechanical stop (not
shown) adjusted to deploy the fastener to a desired depth in the
tissue. In an alternate embodiment, the final downward position is
determined by a limiting spring 219, which is chosen to compress
significantly only when a force comparable to the maximum force to
be applied to the insertion device to seat the fastener fully
within the everted tissue is applied. If the motive force for the
actuation arm 216 is manual force the limiting spring 219 can
provide force feedback to the user without appreciably advancing
the fastener further into the tissue. This adds a degree of
compliance to the mechanism making the exact vertical position of
the surfaces 68a, 68b of the dermis less critical than with a rigid
mechanism. In addition, the likelihood of tissue tearing as a
result of excessive force applied to the actuation arm 216 is
reduced so long as the user remains sensitive to the maximum
appropriate force to be applied.
[0064] The different steps of a method of the present invention are
shown in FIG. 9a-9d. In FIG. 9a, tissue manipulators 91a, 91b have
pinched the epidermis 56 on either side of the wound to be apposed
and the insertion mechanism 200 has been brought into place. The
tissue manipulators 91a, 91b have been located to index cavities
206a, 206b provided on the insertion mechanism for this purpose. A
fastener 71 has been mounted on the insertion device 74, which is
in turn mounted to the actuation arm 216 by means of a shaft 222
that allows only vertical translation.
[0065] In FIG. 9b, the actuating arm 216 of the mechanism has
started to descend, forcing tissue compressing arms 203a, 203b
against the edges of epidermis 56 held by the tissue manipulators
91a, 91b. Movement of the tissue compressing arms 203a, 203b is
limited by the engagement of the actuating arm 216 such that the
cylindrical elements 213a, 213b remain separated a predetermined
distance between 4 mm and 8 mm as indicated by dimension "B". The
fastener 71 is shown ready to descend with the insertion device 74
driven by the actuation arm 216 towards the underside of the dermal
layer of the wound.
[0066] In FIG. 9c, the actuating arm 216 of the insertion mechanism
200 has descended further than in FIG. 9b, maintaining the position
of the tissue compressing arms 203a, 203b while inserting the
fastener 71 into the tissue with the aid of the sharp ends 80 of
the insertion device 74. (As indicated previously, the sharp ends
80 can be tapered as shown in FIG. 3b or beveled as shown in FIGS.
7g-7i, to give just two examples of the possible shapes of the
sharp ends 80.) The limiting spring 219 is compressing, which
builds up the force feedback on the user who is providing the
motivating force on the actuation arm without appreciably advancing
the fastener further into the tissue. The fastener 71 is desireably
inserted at a point that is displaced from the edge of the cut
surfaces 68a, 68b by a distance C that is approximately half the
length of the bridge 86 of the fastener 71.
[0067] In FIG. 9d, the actuation arm 216 is shown in a partially
retracted position leaving the fastener 71 in place in the dermal
layer 59. Remaining steps, not illustrated, include the further
retraction of the actuation arm 216, allowing the tissue
compressing arms 203a, 203b to reopen, and the insertion mechanism
200 to be withdrawn while the tissue manipulators 91a, 91b
momentarily retain the edges of the epidermis 56. As a final step
the user brings the tissue manipulators 91a and 91b together along
the line of apposition thereby pulling the two sides of the dermal
layer 59 until the surfaces 68a, 68b of the dermal layer touch one
another. Since the points of insertion are a distance C from each
of the surfaces 68a, 68b, and the distance of twice C is
approximately equal to the length of the bridge 86, the bridge
straightens and comes into tension at the point where the surfaces
68a, 68b touch.
[0068] In an alternative embodiment, FIG. 10 shows compressing
forceps 301 having tissue contacting members 306a and 306b that are
referred to herein as presser feet and which are shown in FIG. 10
in cross section. The presser feet 306a and 306b have a lower
vertical profile than the half-cylinder components 106a and 106b of
compressing forceps 101 of FIG. 8, with that height or profile of
the presser feet 306a, 306b shown in FIG. 10 as "d" where "d" can
be, for example, about 1.0 mm. This lower profile allows the cut
surfaces 68a and 68b of the skin tissue to be everted and reflected
over the presser feet 306a and 306b at a more acute angle than
achievable with the arrangements of FIGS. 4, 5, 8, and 9.
Reflecting the cut surfaces 68a and 68b at a more acute angle
exposes the subcutaneous layer 62 of the dermis 59, permitting the
insertion device 74 to insert the fastener 71 perpendicularly with
respect to the plane of the skin surface 53 through the dermis 59
and into the subcutaneous layer 62.
[0069] The presser feet 306a and 306b can include surface features
309a and 309b for engaging the ends of tissue manipulators 391a and
391b. The surface features 309a and 309b can be notches or ridges,
for example. By engaging the ends of tissue manipulators 391a and
391b, the surface features 309a and 309b help to stabilize the
manipulators 391a and 391b in a fixed position once the cut
surfaces 68a and 68b of the skin tissue have been elevated and
reflected over the presser feet 306a and 306b to the extent
desired. The presser feet 306a and 306b can be made of any
sterilizable metal (such as stainless steel), sterilizable or
single use plastic, or other material suitable for use in surgical
instruments. They can be formed integrally with the arms 303a and
303b of the compressing forceps 301, or they can be attached by
means of weld joints, screws, adhesive, and/or snap-fitting
connecting members.
[0070] The presser feet 306a and 306b can be brought into
apposition by squeezing the compressing forceps 301 until the
stopping elements 312a and 312b make contact. As shown in FIG. 10,
a pre-determined gap A' remains between the opposing presser feet
306a and 306b when stopping element 312a makes contact with
stopping element 312b. This gap A' is designed to bring the cut
surfaces 68a and 68b together to the extent necessary to align
fastener leg 77a with cut surface 68a, and fastener leg 77b with
cut surface 68b, as shown in FIG. 12a. Gap A' is larger than
fastener width B' by about 1.0 mm to ensure that fastener legs 77a
and 77b reliably penetrate through the dermis 59 and partially into
the subcutaneous tissue 62, as shown in FIG. 12b. For an embodiment
with fastener width B' of 4.0 mm, the gap A' can be in the range of
about 4.05 mm to about 4.15 mm.
[0071] With cut surfaces 68a and 68b elevated and reflected over
the apposed presser feet 306a and 306b, respectively, as shown in
FIG. 10, the tissue is then ready to receive an insertion device 74
having a mounted fastener 71. The insertion device can be inserted
into the tissue in a number of ways. For example, an operator can
grasp insertion device 74 manually with thumb and index finger and
advance it generally perpendicular to the plane or surface of the
tissue as shown in FIG. 12a. After depositing the fastener 71 into
cut surfaces 68a and 68b, the operator can then withdraw the
insertion device 74, as shown in FIG. 12c.
[0072] FIG. 11 is a perspective view of a hand-held insertion
mechanism 400 which can hold and deploy the fastener 71 from above
the plane of the tissue 453 (e.g., the skin of a human or other
mammal) having the cut or incision. The insertion mechanism 400 is
held in a position to place its insertion device 74 generally
perpendicular to the plane or surface of the tissue having the cut
or incision, as shown in FIG. 12a. The insertion mechanism 400 can
have loaded into it and held internally one or more of the
fasteners 71.
[0073] As shown in FIG. 11, the insertion mechanism 400 comprises a
pair of opposing presser feet 406a and 406b attached to the
insertion mechanism 400 via arms 403a and 403b, respectively. Arms
403a and 403b are spaced apart by gap 412 which is chosen to
provide the correct gap A' between the opposing presser feet 406a
and 406b. Gap 412 may be fixed by the mechanical assembly of the
insertion mechanism 400 or in another embodiment gap 412 can be
adjustable by a screw or other means know in the art. At least one
of the presser feet 406a and 406b can have an angular or curved
shape in the horizontal plane, such that the distal ends of presser
feet 406a and 406b define a wider lead-in area that becomes
progressively narrower from front to back, as shown in FIG. 11. The
lead-in area reaches a minimum width which defines gap A' directly
beneath the insertion device 74. In order to bring cut surfaces 68a
and 68b into proper alignment for fastener insertion, an operator
can use tissue manipulators 491a and 491b to raise cut surfaces 68a
and 68b. The operator can then slide insertion mechanism 400
longitudinally along the cut, trapping and compressing the cut
surfaces 68a and 68b between the fixed presser feet 406a and 406b,
as shown in FIG. 11.
[0074] Alternatively, arms 403a and 403b of the insertion mechanism
400 can move in response to handles 410a and 410b to move presser
feet 406a and 406b laterally into and out of the operative field.
After the cut surfaces 68a and 68b are raised by the tissue
manipulators 491a and 491b, the insertion mechanism 400 can be
placed directly over the planned insertion site with reference to
alignment mark 420, and the operator can move handles 410a and 410b
through a first distance to compress presser feet 406a and 406b and
align the tissue segments.
[0075] After the cut surfaces 68a and 68b of the skin tissue or
other type of tissue are elevated and reflected over the fixed
presser feet 406a and 406b by tissue manipulators 491a and 491b, an
operator can manually compress handles 410a and 410b through a
second distance, causing downward movement of the insertion device
74. As the insertion device 74 is made to move downward toward the
tissue, it exits fastener cartridge 416 and penetrates the cut
surfaces 68a and 68b, depositing fastener 71 (not shown). The
handles 410a and 410b can be spring-loaded, so that upon release of
the handles, the insertion device 74 can retract into fastener
cartridge 416, leaving the embedded fastener 71 behind as shown in
FIG. 12c.
[0076] The insertion mechanism 400 also can be configured to accept
a plurality of the fasteners 71 held in fastener cartridge 416. In
one embodiment each fastener 71 is factory installed onto a
disposable insertion device 74 and the plurality of these
assemblies is held in fastener cartridge 416. The assemblies of
fastener 71 and insertion device 74 can be fabricated from separate
components, or by an insert molding process as described previously
with reference to FIGS. 7g, 7h, and 7i. The insertion mechanism 400
operates on the insertion devices one at a time to deploy the
tissue fasteners 71 into the tissue and to store each insertion
device 74 after deploying its preloaded tissue fastener 71. In
another embodiment insertion mechanism 400 has one insertion device
74 and a plurality of fasteners 71 are positioned within fastener
cartridge 416. The plurality of fasteners 71 may be individually
placed into fastener cartridge or inserted as a molded assembly
with inter-connecting frangible components 99, as shown in FIG. 7f.
The frangible components 99 can be formed with and made out of the
same bioabsorbable material used to form the fasteners 71. This
assembly of breakaway fasteners provides ease of loading the
fasteners 71 into the cartridge 416 and also provides controlled
positioning of the fasteners 71 to facilitate the mechanical
loading of the fastener onto the insertion device 74 for
deployment. Although FIG. 7f depicts the frangible components 99
interconnecting the bridge sections 86 of the fasteners 71, the
breakaway connecting components 99 can instead, or additionally,
releasably connect together one or more other sections of adjacent
fasteners 71.
[0077] The method of deploying fastener 71 into tissue is further
explained in FIG. 12a-12d. The sequence of steps is similar for an
operator manually inserting individual insertion devices 74 with
the aid of compressing forceps 301 or using the hand-held insertion
mechanism 400. As shown in FIG. 12a, the low profile of presser
feet 306a and 306b (or 406a and 406b), allows the cut surfaces 68a
and 68b to be raised and retracted at an acute angle with respect
to the plane of tissue 53. As shown in FIG. 12b, the acute angle of
reflection of the cut surfaces 68a and 68b allows the needles 79a
and 79b of insertion device 74 to enter and exit the dermis 59. As
shown in FIG. 12c, as insertion device 74 is withdrawn from the
tissue, the fastener 71 is left behind in the tissue by virtue of
the engagement of barbs 83 of legs 77a and 77b into the dermis 59.
As shown in FIG. 12d, upon release of the cut surfaces 68a and 68b
and removal of the tissue manipulators 391a and 391b (or 491a and
491b), as well as presser feet 306a and 306b (or 406a and 406b),
the cut surfaces 68a and 68b relax into anatomical apposition with
one another. The elasticity of the tissue causes the two cut
surfaces 68a and 68b to exert a distracting force against the
embedded fastener 71, causing its legs 77a and 77b to spread apart,
a process facilitated by the flexible bridge 86. As the legs 77a
and 77b spread apart, the curvature of the flexible bridge 86 is
reduced, and the distracting force places the bridge 86 in tension
thereby aligning and holding legs 77a and 77b from further
separation. The tensile strength of legs 77a, 77b, and bridge 86
acting on the engagement of barbs 83 with the dermis 59 holds the
tissue in apposition. As shown in FIG. 12e, incorporating
additional barbs 98, for example, can provide support for apposing
the tissue to reduce the likelihood of the tissue receding to
expose the mid-section of bridge 86 under conditions of increased
distraction force. These conditions can occur, for example in skin
that overlies a joint, or that is otherwise subject to frequent
stretching (such as facial skin).
[0078] An advantage of the fastener 71 is that it functions by
placing the legs 77a and 77b in tension with bridge 86. Various
known staples, whether metal or plastic, hold the tissue in
apposition by structural strength, compressive strength, or
resistance to deformation. A property of plastics, such as
bioabsorbable materials used in the present invention, is to be
significantly stronger in tensile strength than in deformation
resistance strength. Thus, for any given distracting force, the
fastener 71 can be made smaller and less irritating to tissue than
known fasteners.
[0079] A perspective view of an embodiment of fastener 71 is shown
in FIG. 13a. A top view of fastener 71 is shown in FIG. 13b. In
this embodiment, the distance 85 between lumen 84a of leg 77a and
lumen 84b of leg 77b is approximately 2.75 mm. Shown in FIG. 13c is
a front view of fastener 71 through section A-A of FIG. 13b. A
partial cutaway view of leg 77b is shown, demonstrating the
dimensional relationships between leg 77b, lumen 84b and barb 83.
Barb 83, for example, can form an angle 72 of approximately 30
degrees with respect to the long axis of leg 77b. In an embodiment,
the effective sharpness of barb 83 can be given by angle 73, which
in this case is approximately 25 degrees. The perpendicular
distance 70 of the tip of barb 83 from the surface of leg 77b in
this embodiment is approximately 0.6 mm. The amount by which the
distal portion 78b of leg 77b tapers inwardly can be determined by
angle 75, which in this embodiment is approximately 15 degrees. In
the fastener 71 of FIG. 13c, the overall width 76 of leg 77b is
approximately 0.8 mm, the diameter 81 of lumen 84b is approximately
0.3 mm, and the radial thickness of the wall of leg 77b tapers from
approximately 0.25 mm to approximately 0.075 mm at its tip 78. FIG.
13d is a side view of fastener 71, through section B-B of FIG. 13c.
In this embodiment, the overall length 87 of legs 77a and 77b is
approximately 5.25 mm. The cross-sectional rectangular shape of
bridge 86 of this embodiment is also apparent in this view, a shape
that contributes to the lateral flexibility of the bridge. The
bridge 86 of FIG. 13d has a vertical thickness 88 of approximately
0.25 mm and a transverse thickness 89 of approximately 0.7 mm.
[0080] Embodiments of fasteners according to the invention, such as
the disclosed fastener 71, can be manufactured from one or more
bioabsorbable materials, such as copolymers of L-Lactide or
D,L-Lactide, and Glycolide. Any suitable bioabsorbable material(s)
can be used to form the fastener 71, as long as the material(s) can
be formed into the fastener 71 and perform as disclosed herein.
[0081] The terms bioabsorbable and bioabsorbable material as used
herein are intended to include any suitable material(s) for
fasteners according to the invention that hold their shape and are
stable outside of the body but that degrade, resorb, absorb, erode,
and/or otherwise breakdown within the body of a patient over time
and are eliminated by the body's normal functions.
[0082] A fastener made of a poly(lactic-glycolic) acid ("PLGA")
copolymer, for example, can have a ratio of L-lactide to Glycolide
of from about 10:90 to about 95:5 by weight, such as for example
80:20, 82:18, or 85:15.
[0083] In some embodiments, the bioabsorbable material used for the
fastener 71 is a lactide/glycolide copolymer (such as, for example,
poly-DL-Lactide-co-Glycolide or "PDLGA") where the ratio is never
less than at least 10% of one element and, in a more specific
embodiment, is in a range of 60%-70% lactide.
[0084] Some of the bioabsorbable materials that could be used to
form a fastener according to the invention include
poly(d1-lactide), poly(1-lactide), polyglycolide, poly(dioxanone),
poly(glycolide-co-trimethylene carbonate),
poly(1-lactide-co-glycolide), poly(d1-lactide-co-glycolide),
poly(1-lactide-co-d1-lactide), poly(glycolide-co-tri methylene
carbonate-co-dioxanone), caprolactone, ploydioxane, and/or
copolymers of L-Lactide or D,L-Lactide, and Glycolide.
[0085] The material used for the fastener 71 could include
compositions with naturally occurring biopolymers such as collagen
and elastin, or stainless steel, metal, nylon or any other
biocompatible materials in the case of a non-absorbable fastener,
or even various combinations of such materials depending upon the
desired application and performance of the fastener 71.
[0086] Different formulations of bioabsorbable polymers can provide
different strength versus dissolution profiles. In one embodiment,
a bioabsorbable fastener according to the present invention is
formed of a polymer, or a formulation of polymers, which provides a
tensile breaking strength from leg 77a to leg 77b across bridge 86
of about 3.5 lbs. upon initial deployment into a patient and
maintains that breaking strength at or above about 2 lbs. for a
minimum of about 5 days. A fastener made of PLGA having a ratio of
L-lactide to Glycolide of about 82:18 and having a bridge of a
rectangular cross-section of about 0.25 mm high and about 0.8 mm
wide can have such force-withstanding properties.
[0087] Depending on the type of opening or wound being held
together within the body of the patient with one or more of the
fasteners 71 according to the invention, each of the fasteners 71
will be formed in such a way and of one or more bioabsorbable
materials suitable to allow the fastener 71 to maintain its
structural integrity within the body of the patient for about 14
days or for a minimum of about 5 days. The specific time it takes
for any particular fastener to be bioabsorbed in any particular
application within the body of a patient typically will vary and is
a function of the bioabsorbable material(s) used to form the
fastener, the fastener's precise shape, the area within the body of
the patient where the fastener is deployed, and the patient himself
or herself.
[0088] The disclosed embodiments according to the invention are
exemplary and illustrative. The invention is not limited by or only
to the disclosed embodiments. Various alternatives, modifications,
and combinations not necessarily expressly described herein in
connection with any particular disclosed embodiments are considered
part of this disclosure and within the scope of this
disclosure.
* * * * *