U.S. patent application number 10/393799 was filed with the patent office on 2003-09-11 for pretreatment for lubricated surgical needles.
This patent application is currently assigned to Tyco Healthcare Group LP. Invention is credited to Cabezas, Alan, Kennedy, John, Maiorino, Nicholas, Roby, Mark S..
Application Number | 20030171777 10/393799 |
Document ID | / |
Family ID | 25509139 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030171777 |
Kind Code |
A1 |
Roby, Mark S. ; et
al. |
September 11, 2003 |
Pretreatment for lubricated surgical needles
Abstract
A method for siliconizing surgical needles is provided whereby
the needles are treated with acid before they are siliconized.
Inventors: |
Roby, Mark S.;
(Killingworth, CT) ; Kennedy, John; (Guilford,
CT) ; Cabezas, Alan; (Ansonia, CT) ; Maiorino,
Nicholas; (Branford, CT) |
Correspondence
Address: |
Mark Farber
C/O United States Surgical, a division of
Tyco Healthcare Group LP
150 Glover Avenue
Norwalk
CT
06856
US
|
Assignee: |
Tyco Healthcare Group LP
|
Family ID: |
25509139 |
Appl. No.: |
10/393799 |
Filed: |
March 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10393799 |
Mar 21, 2003 |
|
|
|
09964902 |
Sep 27, 2001 |
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Current U.S.
Class: |
606/222 |
Current CPC
Class: |
A61B 17/06066 20130101;
A61B 2017/06028 20130101 |
Class at
Publication: |
606/222 |
International
Class: |
A61B 017/06 |
Claims
What is claimed is:
1. A method comprising the steps of: providing a surgical needle
having a surface; contacting the surface of the needle with a
pretreating solution comprising an acid to form a pretreated
needle.
2. The method of claim 1 wherein a lubricant composition is applied
on at least a portion of the surface of the pretreated needle.
3. The method of claim 1 wherein the acid is a mineral acid
selected from the group consisting of hydrochloric acid, sulfuric
acid, phosphoric acid, hydrobromic acid, nitric acid, and water
soluble salts thereof.
4. The method of claim 1 wherein the acid is an organic acid
selected from the group consisting of citric acid, acetic acid,
tartaric acid, trifluoroacetic acid, and water soluble salts
thereof.
5. The method of claim 1 wherein the pretreating solution comprises
citric acid in a concentration of about 1.0 wt. % to about 10 wt.
%.
6. The method of claim 2 further comprising the step of rinsing the
surface of the needle after applying the pretreating solution but
before applying the lubricant composition.
7. The method of claim 2 wherein the lubricant composition
comprises a silicone.
8. The method of claim 2 wherein the lubricant composition
comprises an aminoalkyl siloxane.
9. The method of claim 8 wherein the lubricant composition further
comprises a second siloxane that is copolymerizable with the
aminoalkyl siloxane.
10. The method of claim 8 wherein the lubricant composition further
comprises a second siloxane that does not copolymerize with the
aminoalkyl siloxane.
11. The method of claim 8 further comprising the step of curing the
aminoalkyl siloxane.
12. The method of claim 2 wherein the lubricant composition
comprises a polydimethylsiloxane having amino and alkoxy functional
groups.
13. The method of claim 2 wherein the lubricant composition
comprises a polydimethylsiloxane and hexane.
14. The method of claim 11 wherein the step of curing the lubricant
composition comprises: subjecting the lubricant composition to an
atmosphere of from about 20% to about 80% relative humidity, at a
temperature from about 10.degree. C. to about 50.degree. C. for a
time period ranging from about 1 hour to about 6 hours; and,
heating to a temperature of from about 100.degree. C. to about
200.degree. C. for a time period ranging from about 2 hours to
about 48 hours to effectively polymerize the lubricant
composition.
15. A method for manufacturing a siliconized surgical needle
comprising the steps of: providing a surgical needle having a
surface; contacting the surface of the needle with a pretreating
solution comprising an acid to form a pretreated needle; applying a
lubricant composition to at least a portion of the surface of the
pretreated needle, the lubricant composition comprising at least
one polydialkylsiloxane and at least one other siliconization
material which does not covalently bond with the
polydialkylsiloxane, the siliconization material being capable of
crosslinking; and, curing the lubricant composition on the surface
of the needle whereby the siliconization material cross-links to
physically interlock the polydialkylsiloxane in the coating and
provide an interpenetrating network coating.
16. The method of claim 15 wherein the acid is a mineral acid
selected from the group consisting of hydrochloric acid, sulfuric
acid, phosphoric acid, hydrobromic acid, nitric acid, and water
soluble salts thereof.
17. The method of claim 15 wherein the acid is an organic acid
selected from the group consisting of citric acid, acetic acid,
tartaric acid, trifluoroacetic acid, and water soluble salts
thereof.
18. The method of claim 15 further comprising the step of rinsing
the surface of the needle after applying the pretreating solution
but before applying the lubricant composition.
19. The method of claim 15 wherein the step of curing comprises:
subjecting the lubricant composition to an atmosphere of from about
20% to about 80% relative humidity, at a temperature from about
10.degree. C. to about 50.degree. C. for a time period ranging from
about 1 hour to about 6 hours; and, heating to a temperature of
from about 100.degree. C. to about 200.degree. C. for a time period
ranging from about 2 hours to about 48 hours.
20. An article of manufacture comprising: a surgical needle having
a tip portion, a body portion and suture attachment portion, at
least a portion of a surface of the surgical needle being
acid-treated; and a silicone-containing coating applied over the
acid-treated portion of the surgical needle.
21. An article of manufacture as in claim 20 wherein the
silicone-containing coating comprises an aminoalkyl siloxane.
22. An article of manufacture as in claim 20 wherein the
silicone-containing coating comprises an interpenetrating
network.
23. An article of manufacture as in claim 20 wherein the
silicone-containing coating comprises a copolymer of an aminoalkyl
siloxane and a second siliconization material.
24. A surgical needle having reduced penetration force comprising:
a surgical needle having an acid-treated surface; and a
silicone-containing coating on at least a portion of the acid
treated surface, whereby the surgical needle has a penetration
force on a fifth pass through tissue that is at least 10% less than
the penetration force on a fifth pass through tissue of a needle
having the same silicone-containing coating on the same surgical
needle having no surface that is acid treated.
25. A surgical needle as in claim 24 wherein the
silicone-containing coating comprises an aminoalkyl siloxane.
26. An article of manufacture as in claim 24 wherein the
silicone-containing coating comprises an interpenetrating
network.
27. An article of manufacture as in claim 24 wherein the
silicone-containing coating comprises a copolymer of an aminoalkyl
siloxane and a second siliconization material.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure generally relates to a method for
improving the adhesion of lubricants to surgical needles. More
particularly, the present disclosure is directed to a method for
siliconizing surgical needles in which the needles are treated with
an acid solution before a siliconizing material is applied to the
needles. The present disclosure also relates to needles made by
this process having reduced tissue penetration force.
[0003] 2. Background of Related Art
[0004] The siliconization of metallic cutting edges of articles
such as, for example, razor blades, hypodermic needles, surgical
needles, scissors, scalpels, and curettes, is known. For example, a
process is known for preparing a siliconized surgical needle in
which an amino alkyl siloxane is applied to the surface of the
needle by immersion in a solution or by spraying and then cured at
elevated temperature in order to produce a silicone coating. A
product sold by Dow Corning under the name "MDX4-4159" can be used
as the amino alkyl siloxane, with the heat treatment being carried
out for half an hour or longer at about 120.degree. C.
[0005] U.S. Pat. No. 3,574,673, the contents of which are
incorporated by reference herein, discloses the silicone coating of
a cutting edge employing a siliconization fluid containing a
mixture of copolymerizable silicones made up of an aminoalkyl
siloxane, specifically a (polyaminoalkyl) alkoxysilane, and a
dimethylpolysiloxane.
[0006] In order to reduce the force of penetration, it is also
known to immerse surgical needles in a solution of a condensable
polymethyl siloxane in a mixture of n-heptane and xylene and then
to remove the solvent by thermal after-treatment for one hour at
100.degree. C. The product sold by Dow Corning under the name
"Syl-Off DC 23", which exhibits an average degree of polymerization
of about 8000, is suitable as the condensable polymethyl
siloxane.
[0007] Other examples include U.S. Patent Nos. 5,258,013 and
5,458,616 which disclose coating surgical needles with a
siliconization material containing an aminoalkyl siloxane and a
cyclosiloxane employing ultrasonic radiation. The siliconization
material can be applied in a solvent carrier, e.g., hexane or
heptane.
[0008] The previously known processes produce surgical needles in
which the force of penetration is clearly reduced compared with
untreated needles. It would be advantageous to provide siliconized
surgical needles which exhibit an even greater reduction in
penetration force upon repeated passages through tissue during a
suturing operation.
SUMMARY
[0009] It has been discovered that pretreating a surgical needle
with acid prior to the application of a silicone coating provides a
siliconized surgical needle in which the needle exhibits an average
tissue penetration force below that of a standard siliconized
surgical needle. A siliconized needle in accordance with this
disclosure can be obtained by applying a pretreating solution
containing an acid to the surface of a needle to be coated, and
then applying a lubricant composition.
[0010] The expression "standard siliconized surgical needle" or
"standard needle" as used herein refers to a commercially available
siliconized surgical needle, e.g., the siliconized surgical needles
attached to sutures marketed by Ethicon, Inc. (Somerville,
N.J.).
[0011] The acid of the acid solution can be an inorganic acid (such
as, for example hydrochloric acid, sulfuric acid, phosphoric acid,
hydrobromic acid and/or nitric acid), or an organic acid (such as,
for example, citric acid, acetic acid, tartaric acid and/or
trifluoroacetic acid).
[0012] After treatment with an acid, the needles are coated with a
lubricant composition. In one embodiment, the lubricant composition
includes an aminoalkyl siloxane and at least one other siloxane
such as a cyclosiloxane which is copolymerizable therewith. In
another embodiment, the lubricant composition is a mixture that
includes at least one polydialkylsiloxane having a molecular weight
sufficient to provide a viscosity of the mixture of at least about
10,000 cp and at least one other siliconization material. In yet
another embodiment, the lubricant composition includes a
polydialkylsiloxane and at least one siliconization material which
does not covalently bond with the polydialkylsiloxane.
[0013] While the amount of force required to achieve penetration of
tissue during suturing may initially be about the same for the
siliconized surgical needle of this disclosure and a presently
available siliconized surgical needle, and while both needles will
tend to experience an increase in penetration force with each
successive passage through tissue, at the conclusion of any given
number of such passages, the siliconized needle of this disclosure
will exhibit significantly less penetration force than the
presently available needle. Thus, the siliconized needle of this
disclosure will advantageously retain its initial tissue
penetration characteristics to a greater extent than a presently
available siliconized needle in a manner which is~particularly
advantageous, as it reduces the effort required in the suturing
operation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Preferred embodiments of the present disclosure involve
pretreating surgical needles with an acid solution prior to coating
them with a siliconization material to produce siliconized surgical
needles. It has been discovered that by pretreating a surgical
needle with a pretreating solution containing an acid and then
coating the needle with a silicone-containing lubricant
composition, a siliconized surgical needle is provided which
exhibits a significantly reduced tissue penetrating force after a
number of passages through tissue. Thus, the average tissue
penetration force of the siliconized needle herein will
advantageously be less than about 10%, preferably less than about
20% and more preferably less than about 30%, of the average tissue
penetration force of a commercially available siliconirzed needle
presently on the market from after about 5 to about 20 passes
through tissue.
[0015] As seen in FIG. 1, a surgical needle 10 generally includes a
tip portion 12, a body portion 14 and a needle attachment portion
16. The coatings described herein can be applied to needles of any
configuration. Thus the needle may be curved, straight or have a
compound configuration. The cross section of the needle can be
round, oval, triangular, rectangular, or any other geometry. The
needle may include cutting edges. The tip portion may be pointed or
blunt. The suture attachment portion can be, e.g., an eye, a slot
or, as shown in FIG. 1, a bore 18.
[0016] Surgical needles which can be treated and coated in
accordance with this disclosure can be manufactured from a variety
of metals. Such metals include, but are not limited to, Series 400
and Series 300 stainless steels, and the quaternary alloys
disclosed in U.S. Pat. Nos. 3,767,385 and 3,816,920, the contents
of which are incorporated by reference herein. A preferred
quaternary alloy possesses the ranges of components set forth below
in Table I:
1TABLE I COMPOSITION OF SURGICAL NEEDLE QUATERNARY ALLOY (WT. %)
Most Preferred Component(s) Broad Range Preferred Range Range
Nickel 10-50 24-45 30-40 Cobalt 10-50 25-45 30-40 Nickel + Cobalt
50-85 60-80 65-75 Chromium 10-30 12-24 15-22 Molybdenum, 5-20 8-16
10-13 tungsten and/or niobium (columbium)
[0017] Another preferred quaternary alloy within Table I which can
be utilized for the siliconized needle of this disclosure,
designated MP35N, is available in wire form from Maryland Specialty
Wire, Inc. (Cockeysville, Md.) and contains (nominal analysis by
weight): nickel, 35%; cobalt, 35%; chromium, 20% and molybdenum,
10%.
[0018] In general, applying a pretreating solution containing an
acid to the surface of a surgical needle followed by applying a
silicone coating mixture will provide a siliconized surgical needle
meeting the requirements of this disclosure.
[0019] To enhance formation of the silicone coating and its
adherence to a surgical needle, the metal surface of the needle is
pretreated with a solution containing an acid. Metal surfaces
normally tend to be covered with a heterogeneous layer of oxides
and other impurities. This covering can hinder the effectiveness of
the silicone coating formation. Thus, it becomes useful to convert
the needle surface to a homogenous state thereby permitting more
complete and uniform silicone coating formation. Surface
preparation can be accomplished using a pretreatment solution,
either an acid bath or spray, to dissolve the oxide layers as well
as wash away impurities. The use of organic solvents and detergents
or surfactants can also aid in this surface preparation
process.
[0020] The pretreating solutions of the present disclosure contain
acids that are selected for their ability to enhance the adhesion
of siliconization material(s) to the surface of a surgical needle
in order to form a silicone coating. Suitable acid solutions
include solutions of mineral acids such as, for example,
hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid
and nitric acid. Organic acids such as, for example, carboxylic
acids, are also useful. Preferable carboxylic acids include citric
acid, acetic acid, tartaric acid and trifluoroacetic acid. In a
particularly useful embodiment, citric acid is used as the acid in
the pretreating solution.
[0021] Where organic acid solutions are selected, strong acid
solutions are preferred, with solutions having a pH of less than 7
and more preferably less than 4.5. The pretreating solution is
preferably an aqueous solution from about 10 to about 100 g/L of
one or more water soluble carboxylic acids or water soluble salts
of these acids.
[0022] Where the acid in the pretreating solution is citric acid,
the citric acid, or salt thereof, is dissolved in deionized water
so that the acid concentration is about 1.0 to about 10 wt. %
carboxylic acid. As can be appreciated by one of skill in the art,
lower or higher acid concentrations may be used with
correspondingly more or less time on the needle to improve the
adherence of the silicone coating on the needles' surface.
[0023] The acid solution may be applied to the substrate by any
conventional technique such as dipping, flowing, spraying and,
preferably, wiping.
[0024] Where the acid solution is volatile and will evaporate from
the needle without leaving a residue, the acid is applied to the
needle and allowed to evaporate, whereupon siliconization material
is applied to the needle. Volatile acid solutions are defined
herein as those which are capable of volatilizing at ambient
conditions within a short time period (i.e., within about 10
minutes or less) after application to the needle. Examples of
volatile acid solutions include hydrochloric, hydrobromic, acetic,
nitric, and trifluoroacetic acid solutions.
[0025] Where the acid solution is non-volatile, or is volatile but
leaves behind a residue upon evaporation, the needle should be
rinsed after the acid pretreatment to remove the acid solution or
its residue. Non-volatile acid solutions are defined herein as
those which are not capable of volatilizing at ambient conditions
within a short time period (i.e. within about 10 minutes or less)
after application to the needle. Examples of non-volatile acids
include sulfuric, tartaric, citric, and phosphoric acids. The
rinsing solutions may include water or alcohol, with water being
preferred. After rinsing, the needle is dried and the
siliconization material applied to the needle.
[0026] It is believed that the acid solution enhances the adherence
of the siliconization material to form the silicone coating by
removing contaminating residues from the surface of the needle and
increasing the number of bonding sites on the surface of the needle
available for reaction with the siliconization material.
[0027] The temperature of the pretreating solution is desirably in
the range of from about 20 to about 95.degree. C. The pretreating
time can be in the range of about 2 to about 90 minutes. In one
embodiment of the present disclosure, the needles are dipped into a
bath containing the pretreating solution. It is preferred to place
the needles onto a wire screen mesh, immerse the needles into the
pretreating solution, and then remove them from the pretreating
solution. The needles are rinsed with hot water and then allowed to
dry and placed onto another wire screen mesh for exposure to a
lubricant composition.
[0028] Once the surface is pretreated, the surface can then be
subjected to further activation, if necessary, to enhance the
formation and adherence of the lubricant composition, including but
not limited to oxidation by any suitable method. Examples of
suitable methods for application of oxidizers include immersion in
hydrogen peroxide, sodium peroxide, potassium permanganate and
mixtures thereof.
[0029] A lubricant composition is applied to at least the tip
portion of the needle. In particularly usefull embodiments, the
entire needle receives the lubricant composition. Where the
lubricant composition is curable, it may be necessary to avoid
filling or blocking any eye, slit or bore present at the suture
attachment portion of the needle.
[0030] The lubricant composition includes at least one silicone
material. As used herein, the term silicone means silicones and
derivatives of silicone chemistry, including but not limited to
silicone fluids, silicone oils, silicone-organic copolymers,
silicone resins, volatile silicones (cyclomethicones), linear
silicones, cyclosiloxanes, polydialkylsiloxanes,
polydimethylsiloxanes, dimethicone copolyols, silicone glycols,
aminofunctional silicones, polymeric silicones, silicone waxes,
such as high molecular weight dimethicones, and silicone derivative
waxes.
[0031] In one embodiment, the lubricant composition is Dow
Coming.RTM. MDX 4-4159 Fluid ("MDX Fluid"), a 50 percent active
solution of dimethyl cyclosiloxanes and
dimethoxysilyldimethylaminoethylaminopropyl silicone polymer in a
mixture of Stoddard solvent (mineral spirits) and isopropyl
alcohol. It is preferred to apply the MDX Fluid to a surface of the
pretreated surgical needle by dipping, wiping, spraying, etc. in
the form of a first dilute organic solution, e.g., prepared with a
solvent such as, for example, a hydrocarbon solvent possessing from
about 5 to about 10 carbon atoms, e.g., pentane, hexane, heptane,
octane, etc.,trichlorotrifluoroethane, 1,1,1-trichloroethane,
mineral spirits, alcohols, e.g., isopropyl alcohol, and the like
and mixtures thereof. It is preferred to dilute MDX Fluid (or other
siliconization material) with hexane and isopropyl alcohol with MDX
Fluid being present in the concentration range of from about 10 g/l
to about 80 g/l and preferably from about 20 g/l to about 40
g/l.
[0032] In a particularly useful embodiment, the lubricant
composition is a mixture containing at least a polydialkylsiloxane
having a molecular weight sufficient to provide a viscosity of the
coating mixture of at least about 10,000 cp and at least one
siliconization material followed by curing.
[0033] Suitable polydialkylsiloxanes for use in forming the coating
mixture herein include polydimethylsiloxanes, polydiethylsiloxanes,
polydipropylsiloxanes, polydibutylsiloxanes and the like with
polydimethylsiloxanes being preferred. Particularly preferred
polydimethylsiloxanes are polydimethylsiloxanes having a molecular
weight sufficient to provide a viscosity of the coating mixture of
at least about 10,000 cp and preferably of at least about 30,000
cp. Such polydimethylsiloxanes for use herein are the products sold
by Dow Corning under the name "Syl-Off DC 23", which is suitable as
a high density condensable polydimethylsiloxane, and NuSil
Technology under the name "MED1-4162" (30,000 cp).
[0034] Suitable siliconization materials for addition with the
foregoing polydialkylsiloxanes to form the coating mixtures of this
disclosure include siliconization materials containing an
aminoalkyl siloxane and at least one other copolymerizable
siloxane, e.g., an alkylpolysiloxane or a cyclosiloxane; a silicone
oil, e.g., one sold by Dow Corning Corporation under the name Dow
36 Medical Fluid (350 to 12,500 centistokes), and the like with the
siliconization material containing an aminoalkyl siloxane and at
least one other copolymerizable siloxane being preferred.
Generally, the preferred siliconization material includes (a) from
about 5 to about 70 weight percent of an aminoalkyl siloxane of the
general formula 1
[0035] wherein R is a lower alkyl radical containing no more than
about 6 carbon atoms; Y is selected from the group consisting of
--OH and --OR' radicals in which R is an alkyl radical of no more
than about 3 carbon atoms; Q is selected from the group consisting
of hydrogen, --CH.sub.3 and --CH.sub.2CH.sub.2NH.sub.2; a has a
value of 0 or 1, b has a value of 0 or 1 and the sum of a+b has a
value of 0, 1 or 2; and (b) from about 30 to about 95 weight
percent of a methyl substituted siloxane of the general formula
2
[0036] wherein R" is selected from the group consisting of --OH and
--CH.sub.3 radicals and c has a value of 1 or 2. The two components
of this siliconization material copolymerize, forming a lubricating
coating on the surface of the needle.
[0037] In addition to, or in lieu of, the foregoing second
copolymerizable siloxane, one can use one or more cyclosiloxanes
such as, e.g., those described in the "Encyclopedia of Polymer
Science and Engineering", Mark et al., eds., 2.sup.nd ed., Vol. 15,
John Wiley & Son (1989), p. 207 et seq., the contents of which
are incorporated by reference herein, provided, of course, the
total amount of the second copolymerizable siloxane(s) is within
the aforestated range.
[0038] A particularly preferred siliconization material for use
herein in combination with the aforementioned
polydimethylsiloxane(s) to form the coating mixture is MDX Fluid,
which, as noted above, is an active solution of dimethyl
cyclosiloxanes and dimethoxysilyldimethylaminoethyla- minopropyl
silicone polymer in a mixture of Stoddard solvent (mineral spirits)
and isopropyl alcohol. Another preferred siliconization material is
NuSil Technology's MED-4159.
[0039] In one embodiment of the present disclosure, the coating
mixture can be formed by adding a first solution of at least one of
the foregoing polydialkylsiloxanes in a solvent with a second
solution of at least one of the foregoing siliconization materials
in a solvent. Under preferred conditions, the first solution can be
prepared by adding Syl-Off DC 23, MED1-4162 or both in a solvent
such as, for example, a hydrocarbon solvent having from about 5 to
about 10 carbon atoms, e.g., pentane, hexane, heptane, octane,
etc., xylene, chlorinated solvents, THF, dioxanone and the like and
mixtures thereof with hexane being preferred. The first solution is
typically formed from Syl-Off DC 23 or MED1-4162 with hexane with
Syl-Off DC 23 or MED1-4162 being present in the concentration range
of from about 10 g/l to about 70 g/l and preferably from about 35
g/l to about 45 g/l.
[0040] The second solution, also under preferred conditions, can be
prepared in the form of a dilute organic solution, e.g., one
prepared with a solvent such as, for example, a hydrocarbon solvent
possessing from about 5 to about 10 carbon atoms, e.g., pentane,
hexane, heptane, octane, etc., trichlorotrifluoroethane,
1,1,1-trichloroethane, mineral spirits, alcohols, e.g., isopropyl
alcohol, and the like and mixtures thereof. It is preferred to
dilute MDX Fluid (or other siliconization material) with hexane and
isopropyl alcohol with MDX Fluid being present in the concentration
range of from about 10 g/l to about 80 g/l and preferably from
about 20 g/l to about 40 g/l. In a preferred embodiment, the
siliconization material is a mixture of MED1-4162 and MDX
Fluid.
[0041] The mixture will ordinarily be formed by adding the first
solution of the polydialkylsiloxane in solvent with the second
solution of the siliconization material in solvent in a ratio
ranging from about 12:1 to about 1:12, preferably from about 6:1 to
about 1:6 and more preferably from about 2:1 to about 1:2. As one
skilled in the art will readily appreciate, the amount of the first
and second solutions necessary in forming the mixtures herein will
vary depending on the volume of mixture desired.
[0042] Once the coating mixture is formed, it can then be applied
to the foregoing needles employing techniques known to one skilled
in the art, e.g., by dipping, wiping, spraying, total immersion,
etc, with dipping and spraying being the preferred techniques.
Preferably, the needles are dipped into the coating mixture for
about 5 to about 60 seconds, preferably about 10 to about 45
seconds and more preferably from about 15 to 30 seconds to form a
coating on the needles. After evaporation of any dilutant or
solvent carrier, the siliconized coating is cured to the desired
degree.
[0043] The coating can be cured by, for example, first placing the
coated needle in a humid environment, e.g., a humidification
chamber, and exposing the coated needle to a temperature of from
about 10.degree. C to about 50.degree. C. and preferably from about
20.degree. C. to about 35.degree. C. in a relative humidity of from
about 20% to about 80% and preferably from about 50% to about 65%.
The coated needles are subjected to the foregoing temperatures and
humidities to initiate curing to the desired degree and provide an
improved lubrication coating. Typically, a time period ranging from
about 1 hour to about 6 hours and preferably from about 2 hours to
about 4 hours is employed. The coated needles are then placed in,
e.g., furnace or oven, and cured by heating the needles to a
temperature of from about 100.degree. C. to about 200.degree. C.,
preferably from about 110.degree. C. to about 150.degree. C. and
more preferably from about 115.degree. C. to about 150.degree. C.
for a time period ranging from about 2 hours to about 48 hours and
preferably from about 15 hours to about 25 hours such that
cross-linking of the polydialkylsiloxane and siliconization
material occurs. In a particularly useful embodiment, the coated
needles are heated to a temperature of 140.degree. C. for 4 hours
and a temperature of 120.degree. C. for 20 hours.
[0044] In another embodiment of the present disclosure, the coating
mixture herein is formed from at least a polydialkylsiloxane and a
siliconization material which does not covalently bond with the
polydialkylsiloxane. A suitable polydimethylsiloxane for use herein
which does not covalently bond with the siliconization material is
a product sold by NuSil Technology under the name "MED-4162".
Generally, the mixture is formed by adding a first solution
containing at least the polydimethylsiloxane in a solvent with the
second solution discussed hereinabove. The first solution is
preferably formed employing the polydimethylsiloxane MED-4162 in a
solvent such as, for example, a hydrocarbon solvent having from
about 5 to about 10 carbon atoms, e.g., pentane, hexane, heptane,
octane, etc., xylene, and the like and mixtures thereof with hexane
being preferred. It is particularly preferred to form the first
solution from MED-4162 in hexane in generally the same ranges as
the first solution discussed above and then adding the first
solution and second solution in generally the same ratios as
discussed above to form the coating mixture. Once the mixture is
formed, it can then be applied to the surface of a surgical needle
employing generally the same techniques and parameters as discussed
above. The coating mixture is then subjected to curing conditions,
e.g., the curing steps discussed above, such that the
siliconization material polymerizes and cross-links thereby
interlocking the polydimethylsiloxane in the coating resulting in
an interpenetrating networked coating.
[0045] The following non-limiting examples are illustrative of the
siliconized surgical needles and the method for their manufacture
of the present disclosure.
EXAMPLES
[0046] This Example compared the lubricity of needles pretreated
with acid in accordance with the present disclosure with those that
were not subjected to the pretreatment step.
[0047] A first batch of needles were prepared that were not
subjected to the pretreatment step. These needles were coated with
Dow Corning.RTM. MDX4-4159 Fluid. The MDX Fluid was applied as a
spray, and the needles were held at 25.degree. C., in 57% relative
humidity, for 4 hours, and then held at 120.degree. C. for 44
hours. Five needles were tested by passing a needle through Porvair
(Inmont Corporation), a microporous polyurethane membrane of about
0.042 inches thickness which served to simulate flesh and is known
to those skilled in the art to be representative of tissue. The
amount of force in grams to achieve penetration of the Porvair by
the needle was then measured for each of eight successive
penetrations of the 5 needles for each trial.
[0048] Measurement of the needle penetration force was accomplished
using the test procedure and apparatus described in U.S. Pat. No.
5,181,416, the contents of which are incorporated by reference
herein. The test was performed by a testing fixture and an Instron
Universal Testing Machine. The surgical needles were mounted in a
gripping clamp which fixed the needle in a position perpendicular
to the Porvair surface and oriented on its radial profile with the
axis of rotation on the same plane as the plane of the Porvair. The
needle was rotated into the Porvair which was mounted on top of an
Instron load cell. The maximum amount of vertical force is recorded
as the needle is pushed through the Porvair. The results of these
tests are set forth below in Table 1, with the averages of the data
summarized in Table 2.
2TABLE 1 TRIAL Needle 1 Needle 2 Needle 3 Needle 4 Needle 5 1 50.1
62.4 56.0 48.8 56.0 2 51.0 58.1 52.7 49.7 54.6 3 52.9 66.0 51.9
52.2 53.0 4 55.8 74.9 50.2 61.2 51.4 5 61.1 85.8 55.3 55.6 53.3 6
64.2 96.4 49.7 60.1 53.4 7 69.7 97.0 55.4 58.1 58.8 8 67.5 111.3
56.8 62.7 59.1
[0049]
3 TABLE 2 Average of force for 5 Needles sigma min max 54.66 5.45
48.8 62.4 53.22 3.29 49.7 58.1 55.20 6.06 51.9 66.0 58.70 10.03
50.2 74.9 62.22 13.50 53.3 85.8 64.76 18.57 49.7 96.4 67.80 17.21
55.4 97.0 71.48 22.62 56.8 111.3 overall average: 61.0 13.97 48.8
111.3
[0050] A separate batch of needles were treated as above, except
they were first subjected to a pretreatment process. According to
the pretreatment process, needles were first placed into a citric
acid bath, one part CitriSuri.TM. 2250 (Stellar Solutions,
Algonquin, Ill.) with ten parts of water, to achieve a pH of
between 3.5 and 4.5. The tank was filled with sufficient volume of
the pretreatment solution to adequately cover all needles to be
treated and the temperature of the solution was maintained at
150.degree. C. The needles were immersed in the solution for 20
minutes.
[0051] The needles were then dipped into water at ambient
temperature for 1 minute, then rinsed with water heated to
60.degree. C. for 10 minutes, and then sprayed with hot tap water
for 1 minute. After rinsing, the needles were then subjected to air
heated to 90.degree. C. for 60 minutes to allow the needles to
dry.
[0052] After pretreatment, needles were coated with MDX Fluid in
the same fashion described above for those needles not subjected to
the pretreatment step, subjected to heating at 25.degree. C. for 4
hours at 57% relative humidity, and then held at 120.degree. C. for
44 hours. Penetration forces were measured for five needles as
described above, with the results of eight successive penetrations
of the five needles set forth below in Table 3, and the average
data reported in Table 4.
4TABLE 3 TRIAL Needle 1 Needle 2 Needle 3 Needle 4 Needle 5 1 57.4
62.4 58.1 61.3 45.1 2 57.7 56.5 56.9 56.1 53.0 3 57.7 55.4 55.3
56.0 51.3 4 56.9 54.5 52.7 53.5 58.1 5 61.3 54.2 53.3 52.7 63.1 6
67.2 54.4 52.5 57.7 71.1 7 67.9 52.9 52.9 61.9 64.7 8 60.7 54.1
53.9 59.1 68.0
[0053]
5 TABLE 4 Average of force for 5 Needles sigma min max 56.86 6.90
45.1 62.4 56.04 1.80 53.0 57.7 55.14 2.35 51.3 57.7 55.14 2.29 52.7
58.1 56.92 4.89 52.7 63.1 60.58 8.16 52.5 71.1 60.06 6.87 52.9 67.9
59.16 5.78 53.9 68.0 overall average: 57.5 5.30 45.1 71.1
[0054] As can be seen by a comparison of Tables 3 and 4 with Tables
1 and 2, needles subjected to the pretreatment solution had
improved lubricity and reduced penetration forces.
[0055] It will be understood that various modifications may be made
to the embodiments disclosed herein. Therefore the above
description should not be construed as limiting, but merely as
exemplifications of preferred embodiments. For example, metal
surfaces other than needles can be coated with the coating mixture
in accordance with the methods described herein. Those skilled in
the art will envision other modifications within the scope and
spirit of the claims appended hereto.
* * * * *