Surgical needle abstract
A siliconized surgical needle is provided which requires significantly
less force to effect tissue penetration than a standard siliconized
needle.
Surgical needle claims
What is claimed is:
1. A method for manufacturing a siliconized surgical needle comprising
(a) providing a surgical needle possessing a suture top-receiving
axial recess in its blunt end;
(b) placing the needle in an ultrasonic cleaning unit having a
vapor section;
(c) moving the needle to the vapor section of the unit;
(d) removing the needle from the ultrasonic cleaning unit;
(e) spraying a curable siliconization material upon the needle
while its recess is unoccluded, there being no significant amount
of the siliconization material entering the bore;
(f) allowing the siliconization material to spread evenly over
the needle's surface thereafter;
(g) curing the siliconization material on the needle to provide
a silicone coating thereon.
2. The method of claim 1 wherein the needle is fabricated from
an alloy comprising nickel, cobalt, chromium and at least one metal
selected from the group consisting of molybdenum, tungsten and niobium.
3. The siliconized surgical needle of claim 2 wherein the needle
is fabricated from an alloy comprising from about 10 to about 50
weight percent nickel, from about 10 to about 50 weight percent
cobalt with the combined weight of nickel and cobalt being from
about 50 to about 85 weight percent, from about 10 to about 30 weight
percent chromium and from about 5 to about 20 weight percent of
at least one metal selected from the group consisting of molybdenum,
tungsten and niobium.
4. The method of claim 1 wherein the shank end of the needle is
embedded in a support material during spraying.
5. The method of claim 1 wherein the siliconization material comprises
an aminoalkyl siloxane and at least one other siloxane.
6. The method of claim 5 wherein the silicone coating on the needle
is obtained from a siliconization material comprising an aminoalkyl
siloxane and a cyclosiloxane.
7. The method of claim 5 wherein the silicone coating on the needle
is obtained from a siliconization material comprising an aminoalkyl
siloxane, at least one other siloxane copolymerizable therewith
and at least one hydrocarbon solvent of from 5 to 10 carbon atoms.
8. The method of claim 7 wherein the silicone coating on the needle
is obtained from a siliconization material comprising an aminoalkyl
siloxane, a cyclosiloxane and at least one hydrocarbon solvent selected
from the group consisting of hexane and heptane.
9. A method according to claim 5 wherein the needle after siliconization
exhibits less than about a 100% increase in penetration force after
about 5 successive passes through a microporous polyurethane membrane
about 0.042 inches thick.
10. The siliconized surgical needle of claim 9 exhibiting an average
tissue penetration force after 10 successive passages of less than
about 500 grams.
11. The siliconized surgical needle of claim 10 wherein the uncoated
needle possesses a diameter of about 0.039 inches.
12. The siliconized surgical needle of claim 9 wherein the silicone
coating on the needle is obtained from an aminoalkyl siloxane and
an alkyl polysiloxane.
13. The siliconized surgical needle of claim 9 wherein the silicone
coating on the needle is obtained from an aminoalkyl siloxane and
a cyclosiloxane.
14. The siliconized surgical needle of claim 9 wherein the silicone
coating on the needle is obtained from a siliconization material
comprising an aminoalkyl siloxane, at least one other siloxane copolymerizable
therewith and at least one hydrocarbon solvent of from 5 to 10 carbon
atoms.
15. The siliconized surgical needle of claim 14 wherein the silicone
coating on the needle is obtained from a siliconization material
comprising an aminoalkyl siloxane, a cyclosiloxane and at least
one hydrocarbon solvent selected from the group consisting of hexane
and heptane.
16. The siliconized surgical needle of claim 9 wherein the needle
is fabricated from an alloy comprising nickel, cobalt, chromium
and at least one metal selected from the group consisting of molybdenum,
tungsten and niobium.
17. The siliconized surgical needle of claim 16 wherein the needle
is fabricated form an alloy comprising from about 10 to about 50
weight percent nickel, from about 10 to about 50 weight percent
cobalt with the combined weight of nickel and cobalt being from
about 50 to about 85 weight percent, from about 10 to about 30 weight
percent chromium and from about 5 to about 20 weight percent of
at least one metal selected from the group consisting of molybdenum,
tungsten and niobium.
18. The method of claim 9 exhibiting less than about a 77% increase
in penetration force after about 5 successive passes through a microporous
polyurethane membrane about 0.042 inches thick.
19. The method of claim 9 wherein the silicone coating on the needle
is obtained from an aminoalkyl siloxane and an alkyl polysiloxane.
20. The method of claim 9 wherein the silicone coating on the needle
is obtained from an aminoalkyl siloxane and a cyclosiloxane.
21. The method of claim 5 wherein the needle exhibits less than
about a 200% increase in penetration force after about 10 successive
passes through a microporous polyurethane membrane about 0.042 inches
thick.
22. The method of claim 21 wherein the needle after siliconization
exhibits less than about a 150% increase in penetration force after
about 10 successive passes through a microporous polyurethane membrane
about 0.042 inches thick.
23. The method of claim 21 wherein the silocone coating on the
needle is obtained from an aminoalkyl siloxane and an alkyl siloxane.
24. Method of claim 21 wherein the silicone coating on the needle
is obtained from an aminoalkyl siloxane and a cyclosiloxane.
Surgical needle description
BACKGROUND OF THE INVENTION
This invention relates to a surgical needle possessing a silicone
resin coating providing reduced tissue penetration force and to
a method for manufacturing the needle.
The siliconization of metallic cutting edges of such articles as
razor blades, hypodermic needles, scissors, scalpels and currettes
has been known for some time.
U.S Pat. No. 3574673 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.
Dow Corning Corporation's Bulletin 51-599A (Jul. 1986) describes
Dow Corning.RTM. MDX4-4159 Fluid for siliconizing cutting edges
such as those previously mentioned with an ambient temperature and
humidity-curable mixture of aminoalkyl siloxane and a cyclosiloxane
dissolved in a mixture of Stoddard solvent and isopropyl alcohol.
It is recommended that the fluid be applied by dipping, wiping,
spraying, etc., in the form of a dilute organic solution, 2 e.g.,
prepared with a solvent such as hexane, trichlorotrifluoroethane,
111-trichloroethane or mineral spirits.
U.S. Pat. No. 4720521 describes a film-forming siloxane composition
for application to the aforementioned cutting edge articles which
contains a mixture of three reactive siloxanes together with a non-reactive
lubricating siloxane polymer.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a siliconized surgical
needle and method for siliconizing a surgical needle in which the
needle exhibits an average tissue penetration force below that of
a standard siliconized surgical needle.
It is a particular object of the invention to provide a surgical
needle with an adherent silicone coating derived from a siliconization
material comprising an aminoalkyl siloxane and at least one other
siloxane such as a cyclosiloxane which is copolymerizable therewith.
It is another particular object of the invention to provide a siliconization
method to be carried out upon a surgical needle possessing an axial
bore, or recess, for receiving the tip of a suture, the siliconization
method omitting the step of occluding the bore with water as a preliminary
to the application of the siliconization material to the needle.
In keeping with these and other objects of the invention, there
is provided a siliconized surgical needle exhibiting an average
tissue penetration force which is less than the average tissue penetration
force of a standard siliconized needle.
A siliconized needle in accordance with this invention can be obtained
by applying to a surface of the needle a siliconization material
comprising an aminoalkyl siloxane and at least one other silicone
copolymerizable therewith and thereafter curing the siliconization
material to provide an adherent silicone coating on the needle.
The expression "standard siliconized surgical needle"
as used herein refers to a commercially available siliconized surgical
needle, e.g., the siliconized surgical needles marketed by Ethicon,
Inc., Somerville, N.J.
While the amount of force required to achieve penetration of tissue
during suturing may initially be about the same for both the siliconized
surgical needle of this invention and a standard 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 needle
of this invention will exhibit significantly less penetration force
than the standard needle. Stated another way, the siliconized needle
of this invention will retain its initial tissue penetration characteristics
to a greater extent than a standard siliconized needle. This reduced
tissue penetration force is advantageous inasmuch as it reduces
the effort required in the suturing operation, a particular benefit
in those cases involving extensive wound closure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The surgical needles which can be siliconized in accordance with
this invention can be manufactured from a variety of metals such
as Series 400 and Series 300 stainless steels. Other suitable metals
for the fabrication of surgical needles include the quaternary alloys
disclosed in U.S. Pat. Nos. 3767385 and 3816920 the contents
of which are incorporated by reference herein. A particularly preferred
quaternary alloy possesses the ranges of components set forth in
Table I as follows:
TABLE I ______________________________________ COMPOSITION OF SURGICAL
NEEDLE QUATERNARY ALLOY (WT. %) Broad Preferred Most Preferred Component
Range 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) ______________________________________
A particular quaternary alloy within Table I which can be utilized
for the siliconized needle of this invention, designated MP35N,
is available in wire form from Maryland Specialty Wire, Inc., Cockeysville,
Maryland and contains (nominal analysis by weight): nickel, 35%;
cobalt, 35%; chromium, 20% and molybdenum, 10%.
The siliconization material employed herein and the procedure used
in its application will be such as to provide a siliconized surgical
needle exhibiting a significantly reduced tissue penetration force
compared with that of a standard surgical needle after an equivalent
number of passages through the same, or substantially the same,
tissue. Advantageously, the average tissue penetration force of
the siliconized needle herein will be less than about 10 percent,
preferably less than about 20 percent and still more preferably
less than about 30 percent, of the average tissue penetration force
of a standard siliconized needle after from 5 to 20 passes through
the same or similar tissue.
In general, application of a curable siliconization material containing
an aminoalkyl siloxane and at least one other copolymerizable siloxane,
e.g., an alkyl polysiloxane or a cyclosiloxane, to a surgical needle
followed by curing will provide a siliconized surgical needle meeting
the requirements of this invention.
One suitable method for achieving siliconization herein utilizes
the siliconization material and procedures described in U.S. Pat.
No. 3574673 the contents of which are incorporated by reference
herein. The siliconization material includes (a) from about 5-20
weight percent of an aminoalkyl siloxane of the formula ##STR1##
in which 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
3 carbon atoms; Q is selected from the group consisting of hydrogen,
--CH.sub.3 and --CH.sub.2 CH.sub.2 NH.sub.2 ; a has a value of 0
or 1 and 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 80 to 95 weight percent of a methyl
substituted siloxane of the formula ##STR2## in which R" is
selected from the group consisting of --OH and --CH.sub.3 radicals
and c has a value of 1 or 2.
In addition to, or in lieu of, the foregoing second copolymerizable
siloxane, one can use one or more cyclosiloxanes, e.g., as described
in the "Encyclopedia of Polymer Science and Engineering",
Mark et al., eds., 2nd ed., John Wiley & Son (1989), Vol. 15
p. 207 et seq., the contents of which are incorporated by reference
herein, provided, of course, the total amount of second copolymerizable
siloxane(s) is within the aforestated range.
A particularly preferred siliconization material for use herein
is Dow Corning Corporation's Dow Corning.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. MDX Fluid can be applied to a surface of the cleaned surgical
needle by dipping, wiping, spraying, etc., in the form of a dilute
organic solution, e.g., prepared with a solvent such as hexane,
trichlorotrifluoroethane, 111-trichloroethane or mineral spirits.
In general, it is preferred to dilute MDX Fluid (or other siliconization
material) in a hydrocarbon solvent possessing from 5 to 10 carbon
atoms, e.g., pentane, hexane (which is preferred), heptane, octane,
etc. MDX Fluid cures at room temperature to provide an adherent
silicone coating.
After evaporation of any diluent or solvent carrier, the siliconization
material is cured to the desired degree. The material can be cured
by heating for a short time, e.g., 30 minutes at 120.degree. C.,
or by exposure to ambient temperature and humidity conditions for
longer periods of time.
As previously mentioned, where an axially bored surgical needle
is concerned, it is preferred to siliconize the needle employing
a procedure which does not require the preliminary step of temporarily
occluding the bore. Typically, when siliconizing such a needle by
dipping or total immersion in the siliconization material, it has
been found necessary to occlude the bore with a liquid, e.g., water,
which is immiscible with the siliconization material and thus prevents
any of such material from entering the bore where it might interfere
with proper attachment of the suture. It has been found that the
bore-occluding step can be totally omitted by applying the siliconization
material to the needle by spraying. Accordingly, spraying is a preferred
method of application of the siliconization material at least in
the case of a needle possessing an axial bore, or recess.
Spraying is also the preferred method for applying siliconization
fluid to a needle possessing a reduced shank end which is intended
to be attached to the tip of a suture employing a shrinkable tubular
connector as disclosed in commonly assigned copending U.S. Pat.
application Ser. No. 07/413240 filed Sep. 27 1989 the contents
of which are incorporated by reference herein. If is preferred in
the case of such a needle to insert the needle shank end--first
into a support block, e.g., of rigid foam, and thereafter to spray
the siliconization fluid onto the exposed surface of the needle.
Since the shank end of the needle is embedded in the support block,
it will remain free of silicone during the spraying procedure. The
use of a support block can, of course, also be employed in the case
of the axial recess type needle described above to prevent siliconization
material from entering the recess. It is preferable that the coated
needle while still in its support block be subjected to curing conditions;
if this involves heat, it will, of course, be necessary to select
a support block material which can withstand the elevated temperature
selected for curing. |