Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1257 CIP ~;
POLYPROPYLENE MuLTIFILAMENT YARN
AND SUTURE MANUFACTURED THEREFROM
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BACXGROUND OF THE INVENTION
This invention relates to a polypropylene
multifilament yarn manufactured under particular melt
spinning conditions and to a surgical suture manufactured
from the yarn which exhibits greater flexibility than a
polypropylene suture of comparable construction manufactured - ~
from a polypropylene multifilament yarn produced under . ~ .
different melt spinning conditions. :~
Monofilament sutures fabricated from polypropylene ~ -~
: homopolymers and copolymers and from polymer blends ;~
containing polypropylene are disclosed in, among others,
U.S. Patent Nos. 3,359,983, 3,630,205, 4,520,822, 4,557,264,
4,620,542, 4,621,638 and 4,911,165 and in U.K. Patent
Specification No. 1,588,031 and European Patent Application
No. 415,783.
: Thus, e.g., in accordance with U.S. Patent No. .`
3,630,205, following extrusion an isotactic polypropylene
monofilament is quenched to effect its solidification and :~
drawn, or stretched, from six to seven times its original
length at elevated temperature resulting in its orientation
: and an increase in its tensile strength. The stretched
monofilament is then collected on a spool for subsequent
processing, specifically, an annealing operation which
results in the shrinkage of the suture. The various
conditions of the extrusion, stretching and annealing steps
are indicated to be important for obtaining the desired
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polypropylene monofilament suture, one which is
characterized by an ultimate elongation of from 35 to 63
percent.
The polypropylene monofilament suture
manufacturing process of U.S. Patent No. 4,911,165 is said
to provide a suture exhibiting improved compliance while
retaining the excellent properties of prior polypropylene
monofilament sutures. An increase in the draw ratio during
orientation and the allowed shrinkage during annealing is
credited with resulting in a monofilament suture of lower
modulus at a given level of tensile strength.
As disclosed in U.S. Patent No. 5,217,485, if in
the polypropylene monofilament suture manufacturing process
described in U.s. Patent No. 3,630,205 the stretched
monofilament is permitted to equilibrate, or "rest", prior
to undergoing the annealing operation, the resulting suture
will exhibit significantly improved properties such as
reduced strain energy, increased knot security and reduced
out-of-package set even after relatively lengthy periods of
shelf storage. The strain energy of a polypropylene i~
monofilament suture is related to the amount of effort
required to straighten the suture upon removal of the suture
from its package such that the lower the strain energy, the
lesser the effort required to straighten the suture prior to
use.
Braided sutures fabricated from polypropylene
multifilament yarns are known, e.g., from U.S. Patent Nos.
1 5,019,093 and 5,059,213. As disclosed in U.S. Patent No.
¦ 5,019,093, a braided suture manufactured from a variety of
materials, polypropylene among them, is co~structed with a
significantly greater number of sheath yarns for a given
overall denier, the sheath yarns being fabricated from
individual filaments of finer denier than those typical of
known types of braided suture. The unique construction of -
the braided suture of U.S. Patent No. 5,019,093 results in a
perceptible improvement in its flexibllity and hand and
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reduced chatter and drag compared with the same characteristics
in a braided suture of theretofore known construction. U.S.
Patent No. 5,059,213 descrihes a suture of spiroid braid
construction which can also be manufactured from various
materials including polypropylene. The suture of U.S. Patent No.
5,059,213, like that of U.S. Patent No. 5,019,093, exhibits
greater flexibility, better hand and less chatter and drag than
other types of braided suture construction. The improved
properties of the sutures of U.S. Patent Nos. 5,019,093 and
5,059,213 have largely resulted from their pattern of
construction rather than from the physical properties of the
yarns utilized in their manufacture.
In accordance with an embodiment of the present
invention there is provided a polypropylene multifilam~nt yarn ~;`
produced by the process which comprises melt spinning an
isotactic polypropylene employing an extruder equipped with a
spinneret and downstream of the extruder a draw frame possessing
three pairs of godets, the extruder being operated in one or more
zones thereof at a temperature of from about 230 to about 270C,
the pressure of the extruder being from about 1000 to about 2000
psi, the temperature of the spinneret being from about 220 to
about 250C, the first pair of godets being operated at a
temperature of from about 40 to about 90C and an mpm of from
about 100 to about 300, the second pair of godets being operated
at a temperature of from about 70 to about 130C and an mpm of
from about 300 to about 1000 and the third pair of godets being
operated at ambient temperature and an mpm of from about 250 to
about 1000, the draw ratio of the yarn being from about 2 to
about 4 and the shrinkage of the yarn being from about 5 to about
15 percent.
In accordance with another embodiment of the present
invention there is provided a suture constructed with a
polypropylene multifilament yarn produced by the process which
comprises melt spinning an isotactic polypropylene employing an
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extruder equipped with a spinneret and downstream of the extruder
a draw frame possessing three pairs o~ godets, the extruder being
operated in one or more zones thereof at a temperature of from
about 230 to about 270C, the pressure of the extruder being from
about lO00 to about 2000 psi, the temperature of the spinneret
being from about 220 to about 250C, the first pair of godets
being operated at a temperature of from about 40 to about 90C
and an mpm of from about lO0 to about 300, the second pair of
godets being operated at a temperature of from about 70 to about
130C and an mpm of from about 300 to about 1000 and the third
pair of godets being operated at ambient temperature and an mpm
of from about 250 mpm to about lO00, the draw ratio of the yarn
being from about 2 to about 4 and the shrinkage of the yarn being
from about 5 to about 15 percent.
Braided sutures fabricated from the foregoing
polypropylene multifilament yarn exhibit significantly greater
out-of-package flexibility than monofilament polypropylene
sutures of the same size or braided sutures made with
polypropylene multifilament yarns produced under melt spinning
conditions which depart significantly in one or more respects
from those recited. Thus, braided sutures incorporating the yarn
of this invention can be more easily manipulated and placed at
the desired wound closure site, a particularly welcome advantage
where the newer laparoscopic surgical procedures are concerned.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
The multifilament yarn of this invention is .
fabricated from a polypropylene resin (isotactic index of at
least about 90), preferably one which is already accepted . ~. :
for use as a suture material, e~g., a polypropylene resin
having a melt flow index in g/10 min (ASTM D 1238-89) of
from about 2 to about 6, preferably from about 2.1 to about
5.0 and most preferably from about 2.5 to about 4.6.
. Xnown and conventional melt spinning apparatus can
be used for the production of the polypropylene
multifilament yarn herein. However, the melt spinning
conditions are fairly critical and for the equipment
configuration described in Table I below, are as follows~
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TABLE I
MELT SPINNING APPARATUS AND OPERATING CONDITIONS -
Apparatus Component,Range of
O~erating ParameterOperatingLCondition
Extruder barrel temp, zone 1 C 230-250
Extruder barrel temp, zone 2 C 230-270
Extruder barrel temp, zone 3 C 230-270
Extruder barrel pressure, psi 1000-2000
Extruder barrel melt temp., C 230-275
Pump size, cc per rev. .16-.584
Pump rpm 25-35 for size .16 pump ; -~ -~
6-10 for size .584 pump
pump temp., C 220-250
Pump pressure, psi 400-1000
Pump melt temp., C 215-255
Block temp, C 220-250 ~ -
Clamp temp., C 220-250
Adapter temp., C 220-250 ~ ~ ;
Candle filter, screen, microns 10-100
No. of spinneret orifices 10-200
Diameter of spinneret orifices, 5-30
.001 in. . .
Spinneret temp., C 220-250
Spinneret pressure, psi 400-1500
Spinneret melt temp., C 215-255
cc/hr output, per spinneret orifice 5-20
First pair of godets, C 40-go
First pair of godets, mpm100-300
Second pair of godets, C 70-130
Second pair of godets, mpm300-1000
Draw (stretch) ratio 2-4
Third pair of godets, C ambient -
Third pair of godets, mpm250-1000
Shrinkage (relaxation), percent 5-15
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Properties of the individual polypropylene
filaments and the yarns incorporating the filaments are ;~
advantaqeouslY as set forth in Table II below~
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TABLE II ~ ,
PROPERTIESQ F INDIVIDUAL FILAMENTS AND YARNS
More
Broad Preferred Preferred ` ;~
Ranqe Range Ranqe
Denier per Filament 0.2-6 0.6-3 0.8-2.5
Filaments per Yarn3-200 5-100 5-70
Denier per Yarn 0.6-1200 3-300 4-175
During the spinning process, after the individual
polypropylene filaments have been brought together to
provide the yarn, it is conventional practice to apply a
spin finish to the yarn. The spin finish typically contains
lubricant, antistatic and adhesive components to hold the
yarn together and improve its processability, e.g.,
drawability. One spin finish composition which is known to
provide generally good results is Lurol 1187 (Goulston Inc.,
700 N. Johnson Street, Monroe, NC 28110) which can be
applied to the yarn from a solution prepared with a suitable
solvent, e.g., as a 5-35 weight percent solution in
isopropyl alcohol.
Following spinning, the multifilament yarn is
ordinarily subjected to further mechanical processing, e.g.,
twisting, air entanglement, etc., in order to further
enhance its processability. Thus, e.g., the yarn can be
ring twisted at a rate of from about 1 to about 5 turns per
inch or air entangled at a level of at least about 50 nodes
per meter prior to being formed into a surgical suture.
The polypropylene multifilament yarn of this
invention is particularly well suited for the construction
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of braided sutures. Preferred suture constructions are
disclosed in U.S. Patent Nos. 5,019,093 and 5,059,213,
discussed supra, the contents of which are incorporated by
reference herein.
The defining structural characteristics of a
braided suture manufactured in accordance with the
parameters set out in U.S. Patent No. 5,019,093 and ~ `
incorporating the polypropylene multifilament yarn of this -~
invention are:
(1) overall suture denier;
(2) the pattern of the interlocking yarns ~ `
expressed as the pick count, which is to say,
the number of crossovers of individual sheath
yarns per linear inch of suture;
(3) the number of sheath yarns comprising the
brald;
(4) the denier of the individual filaments
comprising each sheath yarn; and,
(5) the denier of the core, where present.
The term "braid" or "braided" as applied to the
suture of U.S. Patent No. 5,019,093 refers to an arrangement
of discrete units, or bundles, denominated "sheath yarns",
made up of individual filaments with individual sheath yarns
interlocking or interlacing each other in a regular criss-
cross pattern.
The term "pick count" refers to the number of
crossovers of sheath yarns per linear inch of suture and,
together with the overall denier of the suture, the denier
of the individual filaments constituting a sheath yarn and
the number of sheath yarns employed, defines the principal
construction characteristics of the braided suture.
The braided suture can optionally possess a core
component around which the braid is constructed.
(1) Overall Denier of the Suture
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The overall denier of the braided suture can vary
from about 15 to about 3000. Within this range, the ranges
of overall denier for particular sutures are: from about 15
to about 20 denier; from above about 20 to about 40 denier; ~ ;
from above about 40 to about 70 denier; from above about 70
to about 180 denier; from above about 180 to about 300
denier; from above about 300 to about 450 denier; from above
about 450 to about 800 denier; from above about 800 to about
1200 denier; from above about 1200 to about 1600 denier; -~
a~d, from above about 1600 to about 2500 denier.
(2) Pattern of the Interlocking Sheath Yarns (Pick Count)
For a suture of any range of overall denier, pick
count can vary from about 50 to about 100 crossovers/inch
with about 55-80 crossovers/inch being preferred. For
sutures constructed within any range of overall denier, as
larger numbers of sheath yarns are employed, the pick-count
for acceptable sutures will also increase within the above
ranges.
For a suture of a particular range of denier and
number of sheath yarns, pick count is advantageously
established to achieve a balance in the properties deslred.
In general, with increasing pick count, surface roughness of
the suture tends to increase and with decreasing pick count,
the ability of the external braided sheath to contain the
core (if present) tends to decrease even reaching the point
where the braid may become so loose as to result in the core
protruding therethrough, the occurrence of which is often
referred to as "core popping".
For sutures of any specific denier range and
number of sheath yarns, it is preferable to have as low a
pick count as possible in order to achieve optimum surface
smoothness, consistent, of course, with the need to provide
a compact braid which prevents core popping (where a core is
present).
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(3) The Number of Sheath Yarns
The number of sheath yarns bears some relation to
overall suture denier, the number generally increasing with ;~
the weight of the suture. Thus, across the range of suture
weight (denier) indicated above, the braided suture can be
constructed with from about 4 up to as many as about 36
individual sheath yarns constructed from individual
filaments having the deniers discussed below.
Table III below sets forth broad and preferred
ranges for the numbers of sheath yarns which are suitable ;; ;-~
for the construction of braided sutures of various ranges of
overall denier. The pick counts of the sutures vary from
about 50 to about 100 and deniers of individual filaments ~ -
vary from about 0.2 to about 6.0 for the broad range of
number of sheath yarns and the pick counts vary from about
55 to about 80 and the deniers of individual filaments vary
from about 0.6 to about 3.0, and advantageously from about
0.8 to about 2.5, for the preferred range of number of
sheath yarns.
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TABLE III
SHEATH YARNS RELATED TO SUTURE DENIER
Number of -
Number of Sh~ath
Sheath Yarns Yarns
Overall Suture Suture Size (Broad (Preferred
Denier Range) Range)
from about 15 to 7/0, 8/0 3-12 3-8
about 40
greater than about 6/0 4-16 6-12
40 to about 70
greater than about 5/0 4-16 6-12
70 to about 180
greater than about 4/0 8-20 10-14
180 to about 300 ~;~
greater than about 3/0 12-20 12-18
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300 to about 450
greater than about 2/0 16-32 20-30
450 to about 800
greater than about 0 20-40 24-36
800 to about 1200
greater than about 1,2 20-40 24-36
1200 to about 2500
While the sheath yarns need not be twisted, it is
generally preferred that they be provided with a twist so as
to minimize snagging during braid construction.
(4) Individual Filament Denier
The individual filaments comprising each sheath
yarn can vary in weight from about 0.2 to about 6.0 denier,
preferably from about 0.6 to about 3.0 denier and more
preferably from about 0.8 to about 2.5 denier. The number
of such filaments present in a particular sheath yarn will
depend on the overall denier of the suture as well as the
number of sheath yarns utilized in the construction of the
suture. Table IV sets forth some typical numbers of
filaments per sheath yarn for both the broad and preferred
ranges of filament weight:
TABLE IV
NUMBER OF FILAMENTS PER SHEATH YARN
":
approximate approximate
minimum maximum fiber denier
23 90 0.2
9 36 0.5
o.g
- 3 10 1.8
l 3 6.0
.,
(5) Core
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For all but the lowest range of overall denier,
the braided suture can be constructed around a filamentous ~
core which can itself be braided or provided in some other ~ ~`
configuration such as a twist, ply, cable, etc. The
filament(s) comprising the core need not be as fine as those
comprising the sheath yarns. The core is preferably a
cabled core as disclosed in commonly assigned copending
PCT/US 91/09137, the contents of which are incorporated by
reference herein.
The cabled core of PCT/US 91/09137 is manufactured
in a separate operation and is assembled from a plurality of
individual yarns, e.g., from about 2 to about 200, and
preferably from about 3 to about 80 yarns. Each yarn to be
incorporated into the core is given a twist in one
direction, the "front" direction, the twisted yarns then
being combined into a core which is then twisted in the
opposite direction, the "back" direction, to provide the
cabled core unit around which the remainder of the suture is
constructed. This arrangement has the desirable effect of
preventing or minimizing the possibility of core popping. ~-
Depending upon the material used in the construction of the
core, it may be desirable to heat set and/or stretch the
core in a known manner prior to final assembly of a braided
suture incorporating the cabled core.
The denier of the individual yarns comprising the
core is not particularly critical and can range in most
cases from about 10 to about 100 and preferably from about
15 to about 70. The degree of twist which is
applied to the individual yarns can vary widely with from
about 200 to about 1500 turns per meter, and preferably,
from about 240 to about 1200 turns per meter, generally
providing good results.
The overall denier of the cabled core is, of
course, determined by the number and individual deniers of
the core yarns from which the core is constructed. For many
suture constructions, core denier can range from about 20 to
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about 80 and preferably from about 25 to about 50 in the
smallest size suture and from about 800 to about 2400 and
preferably from about 1000 to about 2200 in the largest size
suture. In order to increase the total core denier, it is
contemplated that for larger suture cores it may be
desirable to ply two or more yarns together, preferably
before front twisting of the yarns.
The degree of reverse-direction, or "back" twist,
should be determined for a particular suture construction so
as to provide a balanced structure. Yarn-to-yarn twist
levels can he compared through the "coefficient of twist
function" alpha which is related to the helical angle. The
coefficient of twist function can be calculated from the
relationship
alpha = K AO.lllD
100
in which alpha is the coefficient of twist, K is the twist
level in turns per meter and D is the denier of the
resulting twisted product, e.g., twisted yarn or core. In
other words, the coefficient of twist, alpha, is given by
the product of yarn twist, K, and the square root of yarn
count, i.e. mass per unit length or linear density. This
coefficient of twist is also directly proportional to the
helical or twist angle in yarns having the same solid
density (or melt density), so alpha determined for one
material can be applied to materials of the same density.
Therefore, yarns having different deniers and the same
coefficient of twist are geometrically similar, with the
coefficient of twist thus being independent of the yarn
denier.
The coefficient of twist in the cabled core
construction is preferably at least about 24, more
preferably at least about 28 and most preferably at least
about 32. -
To apply equal deformation to yarns of different
denier, the coefficient of twist of the yarns should be the
same. Yarns with higher deformation will have a higher
coefficient of twist. For many braided suture
constructions, the twist level in turns per meter of the -
cabled core component can range from about 200 to about 1500
turns per meter and preferably from about 240 to about 1200
turns per meter.
More speclfically, the cabled core is constructed
from a plurality oE individual yarns possessing a first
twist of from about 100 to about 1500 turns per meter, the
twisted yarns being assembled into a core possessiny a
second, opposite twist of from about 100 to about 1200 turns
per meter. Preferably, the individual yarns possess a first
twist of from about 200 to about 1200 turns per meter with
the second opposite twist of the core being about 200 to
about 1100 turns per meter.
In practice, once the desired overall core denier
and denier of the yarns used to make the core are known, the
coefficient of twist can be calculated for the overall core
and individual yarns in order to approximate a balanced core
structure. The above equation is first used to determine
the degree of back twist, K, required to obtain a core of
the desired overall core denier having a desired coefficient
of twist, alpha, greater than 24. Using the same value for
the coefficient of twist, the equation is then solved using
the denier of the individual yarns to determine the
approximate degree of front twist which must be applied to
the individual yarns in order to obtain a balanced
structure. - -
If multiple plied yarns are to be back-twisted to ~-
form the cabled core, the plied yarns are front twisted -
using the equation to determine the degree of twist required
to obtain a balanced structure. After the cabled core is
constructed, a simple loop test can be performed to
determine whether a balanced structure has been achieved. In
one suitable test, a one meter length of core is sampled and
the ends of the core sample are brought together with the
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remainder of the core allowed to hang and form a loop. If
the loop remains substantially open, i.e., without twisting
or with a twist less than 360, the core structure is
considered balanced. Howeve~r, if the loop twists more than
360(2 turns) in either direction, the structure is
unbalanced and should be modified accordingly. It should be
noted that if a cabled core has too much twist in one
direction, then the loop will take a twist in the opposite
direction. Thus, if the loop twists in a back direction
(z), the amount of twist applied to the core or yarn in that
back direction (z) should be increased, or the degree of
twist in the opposite front direction(s) should be
decreased. As will be appreciated, minor variations may be
required in order to obtain the desired balanced core
structure.
For the preferred suture constructions of U.S.
Patent No. 5,019,093, suture sizes 7/0 and smaller can be
made without a core component while a core can be optionally
included in sutures of size 6/0. Cores for suture sizes
4/0, 5/0 and 6/0 can be constructed by twisting individual
yarns in the front direction and then reverse-twisting
individual yarns together. For sutures of size 3/0 and
larger, it is preferred to obtain the desired overall core ~ ;~
denier by plying multiple yarns together, then front ;~
twisting and then back twisting the multiple plied yarns
together to form the cabled core. In describing the cabled ; `~
core, it is useful to identify the number of filaments in
the structure in terms of the number of filaments in each
yarn times the number of yarns plied together times the
number of plied yarns which are back twisted together to
form the cabled core.
Table V below provides some typical core deniers
for polypropylene braided sutures of various deniers
manufactured in accordance with U.S. Patent No. 5,019,093.
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TABLE V
CORE DENIER RELATED TO SUTURE DENIER
::
Denler of Denier of :.Cabled Core Cabled Core . -~
Overall Suture Suture (Broad (Preferred :-~
Denier Size Range) Range)
~rom about 15 to 7/0, 8/0 none none
about 40
greater than about 6/0 none none :.
40 to about 70
greater than about 5/0 20-70 35-55
70 to about 180
greater than about 4/0 30-100 50-80
180 to about 300
greater than about 3/0 70-220 120-170 ~ :
300 to about 450
greater than about 2/0 160-480 260-390
450 to about 800
. ~
greater than about 0 250-800 400-610
800 to about 1200
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greater than about 1,2 450-2000 720-1600 ;~
1200 to about 2500 `~;
. ,,
For a braided suture of given overall denier, the
ranges of pick count, number of sheath yarns and denier of
individual filaments comprising a sheath yarn and cabled
core are related to each other as set forth in Table VI :: .~ ~-
below~
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TABLE VI
STRUCTURAL PROPERTIES OF BRAIDED SUTURES OF VARIOUS SIZES
Deni.er of
Overall Number of Individual Denier of
Suture Pick Count Sheath Filaments Cabled
Denier Yarns Core
greater from about from about from about from about
than about 50 to 4 to about 0.2 to 20 to
120 to about 100 16 about 3.0 about 70
about 180
greater from about from about from about from about
than about 50 to 8 to about 0.2 to 30 to
180 to about 100 20 about 3.0 about 100
about 300
greater from about from about from about from about
than about 50 to 12 to 0.2 to 70 to ~`
300 to about 100 about 20 about 6.0 about 220 ; ~ .
about 450 ;~
greater from about from about from about from about -- :
than about 50 to 16 to 0.2 to 150 to ; : `.
450 to about 100 about 20 about 6.0 about 500 :~ `:
about 800 :~
greater from about from about from about from about . :~
than about 50 to 20 to 0.2 to ~ 250 to `~
800 to about 100 about 40 about 6.0 about 800
about 1200 . -.
greater from about from about from about from about
than about 50 to 20 to 0.2 to 400 to
1200 to about 100 about 40 about 6.0 about 1400
about 1600 `~
greater from about from about from about from about :
than about 50 to 20 to 0.2 to 600 to ~:
1600 to about 100 about 40 about 6.0 about 2000
about 2500
Table VII, below, sets forth the preferred ranges
of pick count, number of sheath yarns, denier of individual
filaments in a sheath yarn and cabled core:
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TABLE VII
STRUCTURAL PROPERTIES OF PREFERRED
BRAIDED SUTURES OF VARIOUS SIZES
Denier of Denier of
Overall Number of Individual Cabled
Suture Pick Count Sheath Filaments Core
Denier Yarns (Optional)
greater from about from about from about from about
than about 55 to 6 to about 0.8 to 35 to
120 to about 80 12 about 2.5 about 55
about 180
greater from about from about from about from about ;:-
than about 55 to 10 to 0.8 to 50 to
180 to about 80 about 14 about 2.5 about 80
about 300
greater from about from about from about from about
than about 55 to 12 to 0.8 to 120 to
300 to about 80 about 18 about 2.5 about 170 .
about 450
greater from about from about from about from about
than about 55 to 10 to 0.8 to 260 to
450 to about 80 about 30 about 2.5 about 390
about 800
greater from about from about from about from about
than about 55 to 24 to 0.8 to 400 to - -
800 to about 80 about 36 about 2.5 about 610
about 1200 , i
greater from about from about from about from about
than about 55 to 24 to 0.8 to 720 to -
1200 to about 80 about 36 about 2.5 about 1000
about 1600
greater from about from about from about from about
than about 55 to 24 to 0.8 to ~ 1000 to -~-~
1600 to about 80 about 36 about 2.5 about 1600
about 2500
U.S. Patent No. 5,059,213 describes another type
of suture, namely, a spiroid braided suture, which can be ~
constructed from the polypropylene multifilament yarn of -
this invention. The defining structural characteristics of -~
such a suture are: - i;
(1) suture size (i.e., suture diameter);
¦ (2) overall suture denier;
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(3) the pattern of the interlocking yarns;
(4) pick count;
(5) the number of yarns comprising the braid;
(6) the denier of the filaments comprising each
yarn; and,
(7) the denier of the core, where present.
The spiroid braided suture can be of "solid"
construction, i.e., a structure in which the filamentous
material of its construction occupies substantially the
entire cross-sectional area of the suture with a relatively -
minor percentage of such area constituting void spaces or `
interstices between adjacent yarns and fibers, or it can
possess a lumen, optionally occupied by a core component as
in the braided cored suture of U.S. Patent No. 5,019,093, ~ `~
supra.
'..'`~" ~'"
(1) Suture Size (i.e., Suture Diameter)
The suture size can be expressed in terms of ;-
standard sizes, corresponding to certain ranges of diameter
(in millimeters), as set forth in the United States
Pharmaco~oeia (USP). Standard sizes of spiroid braided
suture are set forth in Table VIII as follows~
TABLE VIII
SUTURE SIZE
USP Suture Size Diamater (mm)
2 0.50-0.599
1 0.40-0.499
0 (1/0) 0-35-0-399
2/0 0.30_0.399
3/o 0.20-0.249
4/o 0.15-0.199
5/0 0.10-0.149
6/0 0.070-o.ogg
7/0 0.050-0.069
8/0 0.~40-0.049
; ~ 2 ~ ~ :J ~ ~ g
-20-
(2) Overall Denler of the Suture
The overall denier of the braided suture can vary
from about 15 to about 4000. Within this range, the ranges
of overall denier for particular sutures are: from about 15
to about 20 denier; from above about 20 to about 40 denier;
from above about 40 to about 70 denier; from above about 70
to about 180 denier; from above about 180 to about 300
denier; from above about 300 to about 450 denier; from above -
about 450 to about 800 denier; from above about 800 to about ;~
1200 denier; from above about 1200 to about 1600 denier;
and, from above 1600 to 2500 denier.
(3) Pattern of the Interlocking Yarns
Unlike the braided structure of U.S. Patent No.
5,019,093 where the yarns form a criss-cross pattern which
may be thought of as confined to the surface of a hollow
cylinder, a spiroid braided suture consists of a pattern of
interlocking yarns which may be considered as extending from
the surface of a cylinder to its center thus providing a
solid structure as defined above. The characteristic -
pattern of a spiroid braided suture is clearly different
from that of the braided suture of U.S. Patent No.
5,019,093. In the former, the yarns are essentially
parallel to the longitudinal axis of the suture whereas in
the latter, the yarns cross over each other at some angle to
the longitudinal axis of the suture.
(4) Pick Count
Pick count is the number of stitches per inch
lying in a single line parallel to the longitudinal axis of
the suture as viewed from the surface of the suture.
Suitable pick counts can vary from 40-80 stitches/inch and
preferably from 50-70 stitches/inch.
(5) The Number of Yarns
' ~, ' , . ' ' :' ., ' '
l 3 ~
-21-
The number of yarns employed in the construction
of the spiroid braided suture bears some relation to overall
suture denier, the number of yarns generally increasing with ~ .
the weight of the suture. Thus, across the range of suture
weight (denier) indicated above, a spiroid braided suture
can be fabricated with from about 6 up to as many as about
30 individùal yarns constructed from individual filaments
having the deniers discussed belo~
Table IX below sets forth broad and preferred
ranges for the numbers of yarns which are suitable for the
construction of spiroid braided sutures of various ranges of :~
overall denier. The deniers of individual filaments in a
yarn can vary from about 0.2 to about 6.0 for the broad
range of number of yarns and the deniers of individual :.
filaments can vary from about 0.6 to about 3.0, and
advantageously from about 0.8 to about 2.5, for the
preferred range of number of yarns.
TABLE IX :
NUMBER OF YARNS RELATED TO SUTURE DENIER
Number of Number of
Yarns Yarns :~
Overall SutureSuture(Broad (Preferred
Denier Size Range) Range)
.
from about 15 to7/0, 8/03-12 3-6
about 40
greater than about 6/0 6-15 6-12 ~.
40 to about 70
greater than about 5/0 6-15 6-12
70 to about 180
greater than about 4/0 6-26 9-22
180 to about 300
greater than about 3/0 20-36 24-32
300 to about 450
greater than about 2/0 40-58 46-54
450 to about 800
2 ~ .L ~ 8
-22-
greater than about 0 60-80 66-74
800 to about 1200
greater than about 1,2 84-170 88-164
1200 to about 2500
While the yarns need not be twisted, it is
generally preferred that they be provided with a slight
twist so as to minimize snagging during construction.
(6) Individual Filament Denier
The individual filaments comprising each yarn can
vary in weight from about 0.2 to about 6.0 denier,
preferably from about 0.6 to about 3.0 denier and more
preferably from about 0.8 to about 2.5 denier. The number
of such filaments present in a particular yarn will depend `
on the overall denier of the suture as well as the number of
yarns utilized in the construction of the suture. Table X
sets forth some typical numbers of filaments per yarn for
both the broad and pre~erred ranges of filament weight~
TABLE X
NUMBER OF FILAMENTS PER YARN
Approximate ApproximateFilamer.t
Miniumum Maximum Denier
23 135 0.2
9 54 0.5
o.g
3 15 1.8 -~
l 5 6.0
~'~
(7) Core (Optional)
For all but the smallest sizes of spiroid braided
suture, the suture, although substantially solid in the
sense defined above, can optionally contain some small
amount of void space, generally not exceeding 25% or so in
the larger sutures sizes, which, if desired, can be
2~ 3.
-23-
." ~, " ,.
partially or substantially completely filled with a core
component. A core may be advantageous where it is desired
to increase the density of the suture and/or preserve its
roundness. The core, where present, can be monofilamentous
or multifilamentous. In the case of the latter, the core
itself can be braided or can be provided with some other
configuration such as a twist, ply, cable, etc. Preferably,
the core is a cabled core of the type disclosed in PCT/US
91/09137, discussed supra.
Table XI below provides some typical core deniers
for spiroid braided sutures of various deniers:
TABLE XI
CORE DENIER RELATED TO SUTURE DENIER
- Maximum
Denier ofMaximum Denier
Overall Suture Suture Optional of Optional Core
Denier Size Core (Broad(Preferred
Range) Range)
:.
from about 15 to 8/0, 7/0 none none
about 40
greater than about 6/0 none none
40 to about 70
greater than about 5/0 25-65 35-55
70 to about 180
greater than about 4/0 40-80 50-70
180 to about 300
greater than about 3/0 120-170 130-160
300 to about 450
greater than about 2/0 290-340 310-330
450 to about 800
greater than about 0 450-550 470-530
800 to about 1200
greater than about 1,2 800-1600 850-1500
1200 to about 2500
-
21~ 31 ~
- -24-
' :
It can be advantageous to apply one or more
coating compositions to a braided suture manufactured with
the polypropylene multifilament yarn of this invention in
order to improve one or more of its properties such as
surface lubricity and knot tiedown behavior. A variety of
suture coating compositions proposed for either or both
purposes is known in the art, e.g., those disclosed in U.S.
Patent No. 4,047,533, the contents of which are incorporated i
by reference herein. -~
It is also within the scope of this invention to
impregnate the suture with, or otherwise apply thereto, one
or more medico-surgically useful substances, e.g.; those
which accelerate or beneficially modify the healing process
when the suture is applied to a wound or surgical site. So,
for example, the braided suture can be provided with a
therapeutic agent which will be deposited at the sutured
site. The therapeutic agent can be chosen for its i
antimicrobial properties, capability for promoting wound
repair and or tissue growth or for specific indications such
as thrombosis. Antimicrobial agents such as broad spectrum
antibiotics (Gentamycin sulphate, erythromycin or
derivatized glycopeptides) which are slowly released into ;
the tissue can be applied in this manner to aid in combating
clinical and sub-clinical infections in a surgical or trauma
wound site.
To promote wound repair and/or tissue growth, one
or more biologically active materials known to achieve
either or both of these objectives can be applied to the ;
spiroid braided suture of the present invention. Such
materials include any of several Human Growth Factors
(HGDFs), magainin, tissue or kidney plasminogen activator to
cause thrombosis, superoxide dismutase to scavenge tissue
damaging free radicals, tumor necrosis factor for cancer
therapy, colony stimulating factor, interferon, interleukin- -~ 2 or other lymphokine to enhance the immune system, and so
forth.
~ ~ 2~
The term "Human Growth Factor" or "HGF" embraces
those materials, known in the literature, which are referred ~ ~`
to as such and includes their biologically active closely
related derivatives. The HGFs can be derived from naturally
occurring sources including human and non-human sources,
e.g., bovine sources, and are preferably produced by
recombinant DNA techniques. Specifically, any of the HGFs
which are mitogenically active and as such are effective in
stimulating, accelerating, potentiating or otherwise
enhancing the wound healing process can be usefully applied
to the suture herein, e.g., hEGF (urogastrone), TGF-beta,
IGF, PDGD, FGF, etc. These and other useful HGFs and `
closely related HGF derivatives, methods by which they can
be obtained and methods and compositions featurlng the use
of HGFs to enhance wound healing are variously disclosed,
inter alia, in U.S. Patent Nos. 3,833,497, 3,917,824,
3,948,875, 4,338,397, ~,418,591, 4,528,186, 4,621,052,
4,743,679 and 4,717,717, European Patent Applications 0 046
039, 0 128 733, 0 131 868, 0 136 490, 0 147 178, 0 150 572, `
0 177 915 and 0 257 015, PCT International Applications WO
83/04030, W0 86/02271 and UK Patent Applications GB 2 092
155 A, 2 162 851 A and GB 2 172 890 A, all of which are
incorporated by reference herein. of the known HGFs, hEGF,
TGF-beta, IGF, PDGF, FGF are preferred.
EXAMPLE 1
This example illustrates the manufacture of a ;~
polypropylene multifilament yarn in accordance with the
invention. The yarn was manufactured from a 96 percent
isotactic polypropylene having a melt flow index of about
3.3 g/10 min, a weight average molecular weight of 283,000
and a number average weight of 61,000 as reported by the
supplier (Resin F040A Natural of Aristech Chemical
Corporation, Pittsburgh, PA).
';`'~.
2 ~
-26-
The condltions of melt spinning the polypropylene :~
multifilament yarn and the properties of the resulting yarn
are set forth in Table XII below~
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~: , ::,
. . : ~
. ;
~ ' .
, . ~
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' ~
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-27-
TABLE XII
YARN MANUFACTURING CONDITIONS
A. Melt Spinninq Apparatus and Operating Conditions
Operating
Apparatus Component, Operating Condition
Parameter
`
Extruder barrel temp., zone 1 C 240
Extruder barrel temp., zone 2 C 260
Extruder barrel temp., zone 3 C 260
Extruder barrel pressure, psi1500
Extruder barrel melt temp., C 260 ~ ~-
Pump size, cc per rev. 0.16
Pump temp., C 240
Pump pressure, psi 500-750
Pump melt temp., C 240
Block temp., C 240
Clamp temp., C 240
Adapter temp., ~C 240 ~`
Candle filter, screen, microns40 ;
No. of spinneret orifices 30
Diameter of spinneret orifices, .001 in 10
Spinneret temp., C 240
Spinneret pressure, psi 400-800
Spinneret melt temp., C 240 ~ ;
First palr of godets, C 65
First pair of godets, mpm 160
Second pair of godets, C 90
Second pair of godets, mpm 510
Draw (stretch) ratio 2.9
Third pair of godets, C ambient
Third pair of godets, mpm 465
Shrinkage (relaxation), percent 9
35 wt% isopropyl
Spin finish alcohol solution
of Lurol 1187, as
needed
' ` ' ;~
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~ ~ ~ 5 ~
-28~
B. Properties of Polypropvlene Multifilament Yarn
Denler per Filament 0.93
Filaments per Yarn 5,6,9,15,17,18,23,27,48 . ::
Denier per Yarn 5,6,8,14,16,17,21,25,45
EXAMPLES 2-9
These examples illustrate the manufacture of .
various sizes of braided suture in accordance with the
structural parameters of U.S. Patent No. 5,019,093 employing
the polypropylene multifilament yarn of Example 1. The
structural parameters of the sutures are set forth in Table
XII as follows:
TABLE XIII ~ ~:
CONSTRUCTION OF BRAIDED SUTURES
Overall Number of Denier of Denier
Suture Suture Pick Sheath Individual of
Example Denier Size Count Yarns Filaments Core
2 37 7/0 82 8 0.93 - :
3 67 6/0 75 12 0.93 -
4 174 5/0 65 8 0.93 16 : :
254 4/0 75 12 0.93 62 :.
6 404 3/0 65 16 0.93 146
7 667 2/0 72 24 0.93 321 : :~
8 918 0 65 28 0.93 510
9 1384 1 65 32 0.93 907
EXAMPLES 10-13
These examples illustrate the manufacture of
various sizes of braided suture possessing cabled cores as
disclosed in PCT US 91/09137 and incorporating the ~ .
polypropylene multifilament yarn of Example 1. The cabled . .:~
core components of the sutures are constructed in accordance
with parameters set forth in Table XIV as follows:
' ' ~ ' ~
., :
: ~ :
~ 2 ~
- 29
TABLE XIV
CABLED CORE CONSTRUCTION CHARACTERISTICS
First
Twist Second
In Twist
No. Turns In
No. of Denier of Per Turns : :~
Filame of Yarns Meter Per Cable
nts In Individ In (appli Meter Coeffici d
Examp The ual Each ed to (appli ent of Core .
le Core Yarns Plied the ed to Twist Denie
In The Yarn plied form r
Core yarn) the
core) : X~
1048 x 7 43 7 305 250 32 907 `~ ~
x 3 ::
1127 x 7 24 7 534 409 40 510
x 3 ~ :
1217 x 7 15 7 583 447 35 321 :
x 3
1318 x 3 16 3 823 630 37 146 : ~.
x 3
Braided sutures are constructed around the cabled
cores of Examples 10-13 in accordance with the parameters ;~
set forth in Table XV as follows~
TABLE XV
BRAIDED SUTURE CONSTRUCTION~CHARACTERISTICS
Denier of Individual `: :~
: Yarns
Overa No.
I Core Sutur ll Pick of % of Braid
L of e Sutur Count Sheat Sheat Core Core Angle
I Examp Size e h h -~:- .;;
I le Denie Yarns
r
1 1384 74 32 14 43 66 15.3
11 1/0 918 80 28 14 24 56 17.4
::: : : :~
12 2/0 667 72 24 14 15 48 15.4
13 3/0 404 58 16 15 16 36 13.7
`
- -30~
EXAMPLES 14-20
These examples illustrate additional sutures
containing a cabled core component as described in PCT/US
91/09137 and incorporating the polypropylene multifilament ~ ~
yarn of Example 1. :
The cabled cores of Examples 14-20 are constructed
in accordance with the parameters set forth in Table XVI as
follows: -
,.
TABLE XVI :
CABLED CORE CONSTRUCTION CHARACTERISTICS
Back
Front Twist
Twist In
Denier Denie In Turns
No. of of r of Tota Turns Per Coeffic
Filament Indivi Each l Per Meter ient Of
Examp s In The dual Plied Core Meter To Back
le Core Yarns Yarn Deni Applied Form Twist
Iner To Each Cable
CorePlied Core
Yarn*
: ~ ~
1423 x 7 x 21 1501348 250 278 44.5
1548 x 7 x 45 312937 320 324 43.5 ;~
1627 x 7 x 25 176527 590 505 50.5
1717 x 7 x 16 111332 640 576 45.8 : ;:
1818 x 3 x 17 50 151 830 854 45.7
1923 x 1 x 21 21 64 1000 1035 36.3 :~
2017 x 1 x 16 16 47 1200 1200 36.0
:~
. * In Examples 19 and 20, only unplied yarn is used ;~
. .
.
-31-
Braided sutures are constructed around the cabled
cores of Examples 14-20 in accordance with the parameters
set forth in Table XVII as follows~
TABLE XVII
BRAIDED SUTURE CONSTRUCTION CHARACTERISTICS
Pick
Overa Count No.
Core Sutur ll Picks of Denier of % of Braid
of e Sutur Per Sheat Sheath / Core Angle
Examp Size e Inch h Core
le Denie Yarns
r : -`
14 2 1853 7932 5051348 73 18
1 1384 7932 447 937 68 18
.. .:
16 0 918 8328 391 527 57 17
17 2/0 667 8824 335 332 50 17
18 3/0 404 6316 253 151 37 16 `~
19 4/0 254 7912 190 64 25 16
20 5/0 174 55 8 125 49 28 15
~. , " '' "
EXAMPLES 21-29
These examples illustrate the manufacture of
various sizes of spiroid braided suture in accordance with ;~
~ the structural parameters of U.S. Patent No. 5,059,213 i~
¦ employing the polypropylene multifilament yarn of Example 1.
¦ The structural parameters of the sutures are set forth in ~ .
Table XVIII as follows~
TABLE XVIII
CONSTRUCTION OF SPIROID BRAIDED SUTURES ~ ~
OverallDenier of : .:::
SutureNumber of Individual
ExampleSuture DenierYarns Filaments `~
Size
,
: ;~
~` 2 1 ~ 3 ~
-32-
21 7/0 30 7 0-93
22 6/0 60 8 0.93
23 5/0 140 9 0.93
24 4/0 250 16 0.93
3/0 400 26 0.93
26 2/0 730 54 0.93
27 0(1/0) 1000 74 0.93
28 1 1580 117 0.93
29 2 2280 149 0.93
'.
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