Note: Descriptions are shown in the official language in which they were submitted.
~lZl~Z3~
- \ This invention relates to a method for preparing
synthetic polyester surgical articles, as well as the art-
icles produced thereby and methods for using them.
The use of lactide polyesters in the fabrication
of synthetic surgical articles is known in the art~ In con-
junction therewith, comonomers have often been employe~ to
modify the characteristics of -the various polyesters. rrhe
conventional polymerization method for forming the polyest-
ers i5 through ring opening polymerizations of the appropri-
ate cyclic lactides. Usually where copolymers are prepaxed,one lactide is copolymerized with another. Other cyclic
materials have also optionally been employed as comonomers.
These include other lactones, compounds such as trimethylene
carbonate and the like.
Useful polymerization and post-treatment methods
as well as fabrication procedures for the surgical articles
are also known in the art. The surgical articles produced
include both absorbable and non-absorbable articlesO
The following patents are of interest in this re-
spect: United States Patents 3,268,486 and 3,268,487 issuedAugust 23, 1966 to inventor A. Klootwijk and assigned to
Shell Oil Company,New York, N.Y., U.S.A.
It has now been found that syn-thetic polyester
surgical articles can advantageously be manufactured by em-
ploying in conjunction therewith a polymerization procedurewhereby copolymeric lactide polyesters are formed through a
-` ring opening polymerization wherein the polymerization is
sequentially or incrementally carried out. This is achieved
by consecutively adding the comonomers used to form the co-
polymer chain. By conducting the polymerization procedure
in a stepwise or staged manner, the ln vivo characteristics
of the surgical articles produced can more broadly be modi-
-- 2
L28~31.
fied p~or to encounteri~n~ the usual degree of interference of the ability
of the paly~er to fo~m dimensionally stable, highly crystalline, or highly
oriented molecular structures.
Accordingly, the present invention provides in one aspec-t, a
method for -the manufacture of a sterile absorbable surgical article, ccmpris-
ing the steps of:
(1) preparing a snythetic absorbable copolymeric lactide ester
from copolymerizable manQmerS comprising at least one lactide mDnomer, the
polymerization being donducted in two or m~re stages employing sequential
addition of the comonomers whereby there is formed in each stage a
polymeric chain of different composition from the polymeric chain formed in
the or each other stage; and
(2) forming a sterile surgical article from the cop~lymeric
lactide polyester obtained in step (1).
In another aspect, the present invention provides a copolymer
comprising a proportion of sequential units having the formula:
- O O
u "
-C ~ -C (I)
and a proportion of sequential units having the formula:
, ~ O '
-O-(CH2)3-o~c (II)
m e process of the present invention can be employed in two or
; more stages using two or more cOmOnQmerS in the polymerizationprocedure.
In one or more of the stages, tw~ monomers can be employed simultaneously.
A different catalyst may be employed at each stage if desired.
It is generally preferred to conduct the consecutive polymerizations
in the same reaction vessel by sequentially adding the comonomers thereto;
~- hcwever, if desired one or more of the polymer segments can be prepared and
uscd as such for fuxther chemical reaction to form the polyesters in a
different reaction vessel of choice while still retaining the advantages of
and falling with m the present invention.
m e two lactides conventionally preferred for use in preparin~
3 --
~L~Z8Z3~
surgical articles a~e L(-) lactide and glycolide. They are also preferred
for use in the present in~ention. Furthermore, i-t is generally preferred,
herein to employ them together in a sequential polymerization procedure.
Other cyclic comDncmers conventionally employed therewith ~uch as tri-
methylene carbonate, 2-keto-1,4-dioxane and one or more of th~ Eollowing
compounds may also be u æ d as one of the comDnomers to copolymerize with
a lactide in the practice of the present invention: ~-prOpiolactone, tetra-
methylglycolide, ~-butyrolactone, ganmabutyrolactone, delta-valerolactone,
e~silon-caprolactone, pivalolactone and intermolecular cyclic esters of
~-hydroxybutyric acid, ~-hydroxyisobutyric acid, ~-hydroxyvaleric acid,
~-hydroxyiso-
- 3a -
~Z8~
1 valeric acid, a-hydroxycaproic acid, a-hydroxy-a-ethylbu-
tyric acid, a-hydroxyisocaproic acid, a-hydroxy-~-me-thyl-
valeric acid, a-hydroxyheptanoic acid, ~hydroxyoct~noic
acid, a-hyclroxydecanoic acid, ~~hydroxymyristic acid, ~~h~~
droxystearic acid, ~-hydroxylignoceric acid, ~ dieth~1-
propiolactone, ethylene carbonate, 2,5-diketomorpholine,
ethylene oxalate, 6,8-dioxabicyclo[3,2,1]-octane-7-one, di-
salicylide, trioxane, 3-methyl-1,~-dioxane-2,5-dione, 3,5--
-dimethyl-1,4-dioxane-2-one.
One of the preferred areas ~or use of the present
invention relates to the preparation of sterile, synthetic,
absorbable, surgical articles (especially sutures) wherein
glycolide is employed as the predominant lactide comonomer
in preparing the polyesters. The present state of the art
is such that detailed absorption mechanisms and details of
the polymer structures on the molecular levels are not known
with certainty.
One of the preferred embodiments of the present
nvention relates to sequentially copolymerizing lactide
[preferably L(-3 lactide] with glycolide. Triblock struc-
tures formed by sequentially and consecutively copolymeriz-
ing (L(-) lactide, glycolide and L(-) lactide respectively
are also of interest. In the latter case, the polyester
produced has lactic acid units predominating on both ends
of the glycolide polymer chain.
It is believed that the three usual morphological
units, namely spheres, rods (or cylinders) and lamellae
which are well known in AB and ABA type poly(styrene-b-buta-
diene~ (PSB) would be exhibited in the polyesters of the
present units to butadiene units in 80/20~ spherical domains
~2
8~3
1 have been observed by electron micrograph. Ag the mole
ratio decreases with relatively g.reater quantities of buta-
diene units the morphology o:E the microphase separation is
altered from spheres of butadiene units in a mat,ri~ of st~-
rene units to rods of butadiene units in a ma~rix o~ styreneunits and then to alternate lamellae of the units~ When the
mole ratio is further decreased until the butadiene predom-
inates, the styrene units are first presented as cylindrical
or rod-like microphase separations in a matrix of butadiene
units whereafter, as the mole ratio is further decreased,
the styrene units are presented as spheres in a matrix of
butadiene units. For a disclosure of this, see M. Matsuo,
S. Sagae and H. Asai, Polymer, 10, p. 79, 1969.
In the preparation of the absorbable sutures, in
accordance with the practice of the present invention, one
may employ polyesters wherein minor amounts of a monomer
segment of an inert homopolymer such as an L(~) lactide se~-
., .
ment is incorporated at one or both ends of a chain o~ gly-
colide units. The stable segment or segments may be employ-
ed in relatively minor amounts whereby it is believed that
the morphology of microphase separation would, for example,
exist as rods of L(-) lactide units in a matrix of glycolide
units or more preferably spherical domains of Lt-) lactide
units in a matrix of glycolide units.
The surgical articles are fabricated from the poly-
`~: esters using the procedures conventionally employed with the
polyesters disclosed in the reference above. Likewise, the
resulting surgical articles are employed in a conventional
manner.
The following examples illustrate procedures which
-- 5 --
~L~Z8;~3~L
1 are useful in conjunction with the practice of the present
invention but are not to be taken as being limiting thereof.
Unless o-therwise specified, all parts and percen-tages men-
tioned are by weight.
Examples 1 - 2
An ether solution of SnC12.2H2O was prepared -to-
gether with an ether solution of lauryl alcohol containing
10 mg/ml of lauryl alcohol. A sufficient volume of the
above solutions was added to two polymerizatian tubes so
that when the solvent was removed the final weights of cata-
lyst and lauryl alcohol per 20.0 g of L(-) lactide monomer
were:
Table I
Tube No. mg Sn C12.2H2O mg Lauryl Alcohol
1 2.0 125
2 4.0 250
After the solvent was removed, 20.0 g of L~-) lactide was
added to each tube. The tubes were evacuated and sealed
under vacuum. They were then placed in an oil bath at 180C.
for 24 hours. They were removed from the oil bath and let
cool to room temperature. The tubes were opened, the poly-
mer ground in a Wiley mill through a 20 mesh screen, and
- dried for 24 hours at 50C. at 0.1 mm Hg. The resultant
polymers from tubes 1 and 2 were formed in 86% and 89~ con-
version and had I.V.'s of 0.33 and 0.27, resp~ctively. The
percent conversion to polymer was obtained by dividing the
weight of polymer after drying by the weight of polymer be-
fore drying. I.V. means the inhe~ent viscosity of a solu-
tion of 0.5 g of dried polymer/100 ml of hexafluoroacetone
8Z3~l
1 sesquihydrate, measured at 30C.
Into a three neck 100 ml round bottom blask equip-
ped with a glass shaf~ and Teflon~ (DuPont Company, Wilminy-
ton, Delaware, U.S.A.) paddle stirrer, attach~d ~o a stirr-
ing motor and a gas inlet tube connected to an argon cylin~er,was added 7.0 g of the 0.33 I.V. poly L(-~ lactide described
above. The flask was flushed with argon gas for 15 minutes.
The flush was maintained throughout the polymerization. The
flask was placed in a 190C. oil bath. l'he pot contents
reached 180 + 2C. within 15 minutes. Then 3.5 g of glyco-
lide was added with stirring and the oil bath temperature
was adjusted to keep the temperature of the pot contents at
180 - 2C. for 30 minutes with continuous stirring. The
temperature of the oil bath was then raised so that during
30 minutes the temperature of the pot contents reached 220
- 2C. Then, the remainder of the glycolide, 31.5 g, was
added and the temperature of the pot contents was maintained
; at 220 - 2C. for 1 1/2 hours with continuous stirring. At
this time the oil bath was removed t the stirring was stopped,
and the pot contents were allowed to cool to approximately
room temperature under the argon flush. This flush was then
stopped. The glass flask was then broken and the polymer
was removed and ground in a Wiley mill through a 20 mesh
screen. 3.0 g. of the ground polymer were fabricated into
a fibrous sheet for implantation by first dissolving the
polymer in 60 ml of 60C. hexafluoroacetone sesquihydrate
(HFAS). The polymer was precipitated by dripping this solu-
tion into ~00 ml of methanol with stirring. The polymer was
collected by filtration and extracted with acetone in a Soxh-
let extractor for 2 days to remove the residue of fluorinated
~2~3~L
1 solvent. The polymer was then dried in a vacuum oven over-
rlight at 50C. at 0.1 mm Hg. The yield of polymer was 95~6.
The I.V. in HFAS was 0.77. The mole percent of the lactic
acid units in the polymer chain as determined by ~IMR wa~ ~.g.
The melting point as determined from the peak endotherm ob-
served in a differential thermal analysis (D.T.A.j appara-tus
was 218C.
A second two-stage copolymer was prepared as fol-
lows. Into a three neck 100 ml. round bottom flask equipped
with a glass shaft and a Teflon~ paddle stirrer attached to
a stirring motor, and a gas inlet tube connected to an argon
cylinder, was added 4.0 g of the poly Lt-) lactide whose I.V.
was 0.27, with stirring. This was flushed with argon gas
for 15 minutes. This argon gas flush was maintained through-
out the following polymerization. The flask was placed in a190C. oil bath. The pot contents reached 180 - 2C. with-
in 15 minutes. Then, 3.6 g. of glycolide were added with
stirring and the oil bath temperature was adjusted to keep
the temperature of the pot contents at 180 + 2C. for 30
minutes with continuous stirring. The temperature of the
oil bath was then raised so that at the end of 30 minutes
the temperature of the pot contents reached 220 + 2C.
Then, 31.4 g of glycolide was added and the temperature of
the pot contents was maintained at 220 + 2C. for 1 1/2
hours with continuous stirring. At this time the oil bath
was removed, the stirring was stopped and the pot contents
were allowed to cool to approximately room temperature under
the argon flush. The flush was then stopped. The glass
flask was broken and the polymer was removed and ground in
a Wiley mill through a 20 mesh screen. 3.0 g. of this poly-
-- 8 --
~2
1 mer were dissolved in 60 ml. of 60C. hexafluoroacetone ses~quihydrate (HFAS) and the polymer was precipitated by dri,pp-
ing this solution into 600 ml of methanol with stirring. The
polymer was collected by filtration and extrac-~ed with ace~
tone in a Soxlet extractor for 2 days. The polymer was then
dried in a vacuum oven overnight at 50C. at 0.1 mm Hg. The
yield of polymer was 95~. The I.V. in HFAS was 0.82. The
mole percent of lactic acid units in the polymer as deter-
mined by NMR was 5.9. The melting point as determined by
the peak endotherm observed in a D.T.A. apparatus was 219C.
Example 3
A sample of poly L(-) lactide was prepared by the
procedure of Examples 1-2 except that it was formed in 98%
conversion with a 0.5 I.V. using 1.2 mg of Sn C12-2H2O and
7.5 mg of lauryl lacohol. Into a three neck 100 ml round
bottom flask equipped with a glass shaft and a Teflon~ paddle
stirrer attached to a stirring motor and a gas inlet tube
attached to an argon cylinder, was added 10.0 g of the poly
Lt-) lactide. This was flushed with argon for 15 minutes.
This argon flush was maintained through the following poly-
merization. The flask was placed in a 190C. oil bath. The
pot contents reached 180 - 2C. within 15 minutes. Then 2
g of glycolide was added with stirring and the oil bath temp-
erature was adjusted to keep the temperature of the pot con-
tents at 180 + 2C. for 30 minutes with continuous stirring.The temperature of the~oil bath was then raised so that at
the end of 30 minutes the temperature of the po-t contents
reached 220 - 2C. Then, 18.0 g. of glycolide were added
and the temperature of the pot contents was maintained at
220 + 2C. for 1 1/2 hours with continuous stirring. At
. g _
~2~Z3~
1 this time the oil bath was removed, the stirring was stopped
and the pot contents were allowed to cool to approximately
room temperature under argon flush. This flush was then
stopped. The glass flask was broken and ~he polymer w~
ground up in a Wiley mill through a 20 mesh screen.
20.0 g. of this polymer was dissolved in ~00 ml
of 60C. hexafluoroacetone sesquihydrate (HFAS) and the poly-
mer was precipitated by dripping this solution into 4,000 ml
of methanol with stirring. The polymer was collected by
filtration and extracted with acetone in a Soxhlet extractor
for 2 days. The polymer was then dried in a vacuum oven
overnight at 50 at 0.1 mm Hg. The yield of polymer was
72~. The I.V. in HFAS was 0.60. The mole percent of lactic
acid units in the polymer as determined by NMR was 33. The
melting point as determined from the peak endotherm observed
in a differential thermal analysis (D.T.A.) apparatus was
219C.
~xample 4
Into a three neck 100 ml round bottom flask e~uip-
ped with a glass shaft and a Teflon~ paddle stirrer attachedto a stirring motor and a gas inlet tube attached to an argon
cylinder, was added 6.0 g of a 0.29 I.V. poly ~(-) lactide
prepared as in Example 3 except that a heating period of 1.5
hours at 200C. was used. The flask was flushed with argon
for 15 minutes. This argon flush was maintained throughout
the following polymerization. The flask was placed in a
200C. oil bath and the bath temperature was raised until the
temperature of the pot contents reached 200 - 2C. This
occurred within 15 minutes. Then, 48.0 g. of glycolide were
added with stirring and the temperature of the oil ~ath was
- 10 -
~13z33L
1 raised until the temperature of the pot contents was 225~
+ 2C. This occurred within 30 minutes. Stirr:ing was con-
tinued for 1 1/2 hours at this temperaturc. Then, 6.0 g of
L(-) lac-tide were added (with stirring of -the pot contents)
and stirring was continued for 1 1/2 hours at th:is temper-
ature. At this time, the oil bath was removed, the stirring
was stopped and the pot contents were allowed to cool to ap-
proximately room temperature under the argon flush. This
flush was then stopped. The glass flask was broken and the
polymer was removed and ground in a Wiley mill through a 20
mesh screen. 5.0 g. of this polymer were dissolved in 100
ml of hexafluoroacetone sesquihydrate (HFAS) and the poly-
mer was precipitated by dripping this solution in 1,000 ml
of methanol with stirring. The polymer was collected by
filtration and extracted with acetone in a Soxhlet extrac-
tor for 2 days. The polymer was dried in a vacuum oven
overnight at 50C. at 0.1 mm Hy. The yield of polymer was
82%. The I.V. in HEAS was 0.81. The mole percent of lactic
acid units in the polymer chain as determined by NMR was
11.2. The melting point as determined from the peak endo-
therm in a differential thermal a~alysis (.D.T.A.~ apparatus
was 216C.
Example 5
.
Into a three neck 100 ml round bottom flask equip-
ped with a glass shaft and a Teflon~ paddle attached to a
stirring motor and a gas inlet tube attached to an argon cyl-
inder, was added ~.5 g. of poly(epsilon-caprolactone) whose
I.V. was 0.42. The poly(epsilon-caprolactone) polymer was
prepared as in Example 1 except that 8.0 mg. of Sn C12 2~2O
and 500 mg. of lauryl alcohol were employed and epsilon-cap-
~12i!3,'~3~
1 rolactone was used in place of the L(-) lactide. The flask
was flushed with argon for 15 minutes. The argon flush was
maintained throughout the followiny polymeriza~ion. rl'he
flask was placed in a 190C. oil bath. The pot con-ten-ts
reached 180 ~ 2C. within 15 minutes. Then, 1.35 g of gly-
colide were added with stirring and the oil bath temperature
was adjusted to keep the temperature of the pot contents at
180 + 2C. for 30 minutes with continuous stirring. The
temperature of the oil bath was then raised so that at the
of 30 minutes the temperature of the pot contents was 220
- 2C. Then, 12.15 g of glycolide were added with stirring
and the temperature of the pot contents was maintained at
220 + 2C. for 1 1/2 hours with continuous stirring. At
this time the oil bath was removed, the stirring was stopped
and the pot contents were allowed to cool to approximately
room temperature under the argon flush. This flush was then
stopped. The glass flask was broken and the polymer was re-
moved and ground in a Wiley mill through a 20 mesh screen.
4.0 g. of this polymer was dissolved in 80 ml. of 60C. HFAS
and the polymer was precipitated by dripping this solution
into 1000 ml of methanol with stirring. The polymer was col-
lected by filtration and extracted with acetone in a Soxhlet
extractor for 2 days. The polymer was then dried overnight
in a vacuum oven at 50C. at 0.1 mm Hg. The yield of poly-
mer was 73%. The I.V. in HFAS was 0.77. The mole percentof epsilon-hydroxy caproic acid units in the polymer chain
as determined by NMR was 12.3. This corresponds to 12.1
weight percent caprolactone units. The melting point as
determined from the peak endotherm in a differential thermal
analysis (D.T.A.) apparatus was 218C.
- 12 -
~21~3~
l Example 6
Into a three neck 100 ml round bottom flas~ e~uip-
ped with a glass shaft and a Teflon~ paddle attached to a
stirring motor and a gas inlet tube attached to an argon c~l-
inder was added 7.0 g. of poly(trimethylene carbonate) whose
I.V. was 0.34. The poly(trimethylene carbonate) was prepared
by the procedure of Example l except that trimethylene car-
~onate was used in place of the L(-) lactide and 4.0 mg. of
SnC12 H2O were used with 250 mg. of lauryl alcohol. The con-
version was 48%. The flask was flushed with argon for 15minutes. The argon flush was maintained throughout the fol-
lowing polymerization. The flask was placed in a 190C. oil
- bath. The pot contents reached 180 2C. within 15 min-
utes. Then, 3.5 g. of glycolide were added with stirring
and the oil bath temperature was adjusted to keep the temp-
erature o~ the pot contents at 180 + 2C. for 30 minutes
with continuous stirring. The temperature of the oil bath
was then raised so~ that at the end of 30 minutes the temper-
ature of the pot contents was 220 ~ 2C. Then, 31.5 g of
glycolide were added with stirring and the temperature of
the pot contents was maintained at 220 - 2C. for 1 1/2
hours with continuous stirring. At this time the oil bath
was removed, the stirring was stopped and the pot contents
were allowed to cool to approximately room temperature under
argon flush. This flush was then stopped. The glass flask
was broken and the polymer was removed and ground in a Wiley
mill through a 20 mesh screen. 5.0 g. of this polymer were
dissolved in lO0 ml~ of 60C. HFAS and the polymer was pre-
cipitated by dripping this solution into 1,000 ml. of meth-
anol with stirring. The polymer was collected by filtration
- 13 -
~Z823J~
1 and extracted with acetone in a ~o~hlet extractor for 2 da~s.
The polymer was dried overnight in a vacuum oven at 50C. at
0.1 mm. Hg. The yield o~ polymer was 86%. The I.V. in HFAS
was 0.64. The mole percent of units deriv~d ~rom trimethyl-
; 5 ene carbonate in the polymer chain as de-termined b~ NMR was
16,4. This figure corresponds to 14.7 weiyht percent -tri-
methylene carbonate units. The melting point as determined
from the peak endotherm in a differential thermal analysis
(D.T.A.) apparatus was 218C.
Example_7
L~-) lactide (1612 g.), SnC12 2H2O (0.204 g.) and
lauryl alcohol (4.77 g.) were added to a stirred reactor
which had been preheated to 140C. The reactants were heat-
ed with stirring under a nitrogen atmosphere over a 30 min-
ute period to 200C. and then held at that temperature for 2hours.
The reactor was evacuated to a pressure of 50 mm
Hg and the mixture was stirred for 30 minutes during which
time the temperature of the mixture was allowed to fall to
180C.
Atmospheric pressure was restored by introducing
nitrogen into the reaction vessel and the temperature was
raised to 200C. over a 5 minute period. The molten glyco-
lide (5198 g.) preheated to 100C. was added and the temper-
ature was raised over a 15 minute period to 225C. and heldat this temperature for an additional 20 minutes.
The contents of the reactor were discharged and
the pol~meric mass was broken up after it had cooled to room
temperature. The polym~r was then ground and vacuum dried
at 8-10 mm Hg for 11 hours at 140C. to remove all volatiles
- 14 -
Z3~
l preparatory to spinning and determin:ing the polymer'.s vis-
cosity.
The inherent viscosity of the polymer was det~r-
mined to be 1.14, measured at 30C. in a 0.5~ solu~ion in
; 5 hexafluoroacetone sesquihydrate. The mole % of lactic acid
units in the finished polymer was determined to be 20.3% by
~MR. The n~elting range of the product was determined to be
215-223.5C. using a hot stage polarizing microscope.
A portion of the dried polymer was added to the
feed hopper of a small continuous extruder operating at about
230C. The extruder was equipped with a die having a 60 mil
cylindrical orifice and a length to diameter ratio of 4 to 1.
The extrudate was water quenched and collected at 44 feet
per minute. It was then drawn to about 4.5 times its orig-
inal length at 55C~ in a hot air draw unit. A sample of
glycolide homopolymer having a 1.05 I.V. was extruded and
drawn in the same way and then post treated along with the
above copolymer fiber, for 3 hours at 135C. at a pressure
of l mm ~g.
The copolymer fiber which was 2.45 mils in diam-
eter was found to have exceptional tensile-strength retention
properties (34,600 p.s.i.) in an accelerated strength reten-
tion test and very good initial tensile strength (96,500
p.s.i.) notwithstanding its high comonomer content (20.3
mole~). In the contrast, the initial strength of the homo-
polymer fiber which was 2.10 mils in diameter was 140,000
p.s.i. and the counterpart strength retained in an acceler-
ated test was 25,300 p.s.io
As mentioned above, it is believed that such co-
polymeric polyesters are characterized by microphase separa-
- 15 -
~28;~3il
l tions having spherical domains in -the molten state, prior
to orientation wherein the chain segments composed o~ lac-
tic acid units are overlapped with themselves irl a matri~
of glycolic acid units. It is believed -that polyesters
having such microphase separation would exist where the
mole percentage of L(-) lactide incorporated into the poly-
mer chains ranged up to about 25 percent. From about 25
percent to about 40 percent lactic acid units it is believed
that cylindrical domains of lactic acid units would predom-
inate. This would likewise be the case where the lacticacid units prevailed on both ends of the polyester chains
as a result of sequentially and consecutively polymerizing
L(-) lactide, glycolide and then L(-~ lactide.
Although the geometry of the domains in the molten
state is speculative, evidence for the existence of phase
separation or precipitation of the polymers may be seen by
comparing their melting points with that of the homopolymer
of the major component.
Accordingly, preferred surgical articles prepared
in accordance with the present invention are sterile syn-
thetic absorbable surgical sutures prepared from a lactide
polyester said polyester being composed of a copolymer hav-
ing cylindrical or more preferably spherical dominions of
L(-) lactide units in a matrix of glycolide units. The poly-
esters employed can have the relative quantities of glycolideunits and L(-~ lactide units indicated above. The sutures
may be in the form of a sterile surgical needle and suture
combination. Conventional suture constructions and sterili-
zation methods may be used. Preferahly a monofilament or
polyfilamentary braided polyester yarn is crimped into the
- 16 -
1 butt of a surgical needle and the needled suture is then
sterilized using a toxidant such as ethylene oxide. Poly-
esters ~ormed by sequentially and consecutively polymeriGing
L(-) lactide and glycolide are most preferred ~or use -there-
in.
While the surgical articles of the present inven-
tion are generally useful in conventional manners for retain-
ing living tissue in a desired location and relationship dur-
ing a healing process by positioning and emplacing living
tissue therewith, as in ligation of blood vessels, the need
led sutures are especially adapted for the closing of wounds
of living tissue by sewing together the edges thereof using
conventional suturing techniques.
- 17
