Surgical needle abstract
A sterile surgical needle having a dark, non-reflective and non-flaking
surface. The needle is produced by selecting an appropriately shaped
needle having the desired degree of sharpness. The needle is treated
to activate the surface and then immersed in a solution of sulfuric
acid, potassium dichromate and water to form a dark, non-reflective,
non-flaking surface. The needle is sterilized to produce a sterile
surgical needle of improved visibility.
Surgical needle claims
What is claimed is:
1. A chromium containing stainless steel, sterile surgical needle,
said needle having a uniform black and non-reflective surface and
said needle having penetration characteristics substantially the
same as a sterile surgical needle having a shiny and polished surface.
Surgical needle description
The present invention relates to sterile surgical needles, and
more particularly to such needles which have a uniformly dark and
non-reflective surface.
BACKGROUND OF THE INVENTION
In the past, sterile surgical needles generally have had a bright
or shiny chromium or silver type of surface. It was thought this
shiny surface, which was a result of polishing for the most part,
was required in order to obtain desired sharpness and cutting characteristics
or penetration characteristics with the needle. A drawback to these
shiny surfaces is the difficulty they present in being observed
by the surgeon during a surgical procedure. Cardiovascular surgeons
and micro-surgeons have found it quite difficult to use needles
which reflect light in surgery because of the reduced visibility
of such needles. With the advent of micro-surgery there is a similar
problem in lack of visibility within the surgical site of these
highly reflective needles.
Methods of blackening the reflective surfaces of metal materials
have been known for sometime and have been attempted with surgical
needles. To the best of my knowledge, no one has been able to develop
a suitably dark, non-reflective needle as these blackening processes
suffer from one or more disadvantages. Often these blackening processes
form a coating on the needle which may flake off during use. In
some instances the processes form a non-uniform non-reflective surface
which causes visibility problems as well as interfering with the
sharpness characteristics of the needle. In most of these blackening
Processes the needle becomes dull as a result of the blackening
treatment.
What I have discovered is a new method for blackening surgical
needles and a new method for producing sterile surgical needles
having a dark and non-reflective surface. The surface of my new
needles doos not flake and my new needles have excellent sharpness
and penetration characteristics. Other objects and advantages of
the present invention will become readily apparent from a reading
of the following detailed description and drawings.
SUMMARY OF THE PRESENT INVENTION
In accordance with the present invention, my new sterile surgical
needle has a uniformly dark and non-reflective surface. The surface
is non-flaking and the needle has Penetration characteristics substantially
the same as needles having shiny and polished surfaces. The preferred
needles of the present invention have a matte black surface. The
method of the Present invention for producing my new needles is
to first select a needle containing chromium. The needle should
have the desired shape or configuration and degree of sharpness.
The surface of the selected needle is treated by electrical processes
to activate the surface by eliminating chromium rich oxides. The
treated needle is submersed in a solution of sulfuric acid, potassium
dichromate, and water at a temperature in excess of 100.degree.
C. The needle is maintained in the bath for a sufficient period
of time to uniformly darken the bath for a sufficient period of
time to uniformly darken the surface of the needle and render that
surface non-reflective. The needle is removed from the bath and
may be rinsed with running hot water, ultrasonically rinsed at room
temperature, air dried, lubricated and oven dried. It is preferred
that the needles be lubricated with silicone and dried. The needle
is sterilized by various well known sterilization techniques such
as gas sterilization, irradiation, or the like. In most instances,
a suture will be attached to the blunt end of the needle and the
needle placed in a suitable Package prior to sterilization.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of one shape of needle of the present
invention;
FIG. 2 is a cross-sectional view taken along line 2--2 of FIG.
1; and
FIG. 3 is a box flow sheet showing the various steps in the method
of the present invention
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, in FIG. 1 there is shown one shape of
needle of the present invention. In this figure there is shown a
curved needle. As shown in FIG. 2 the cross-sectional shape of the
needle, at least of the pointed end, is circular. The blunt end
of the needle may have a suture attached thereto and in many instances
the sides of the needle will be flattened to assist in grasping
of the needle b a suitable needle holding instrument. The entire
surface of the needle is dark and non-reflective and the surface
is uniformly dark and non-reflective. The surface is also non-flaking
and the needle has excellent penetration characteristics. In the
preferred embodiments of the needles of the present invention, the
needle has a matte black finish. The needles of the present invention
may be made from any of the various steels containing chromium.
The preferred materials are 300 or 400 series stainless steels.
To determine the characteristics of the needle surface, the needles
are tested for flaking characteristics. The tenacity and the non-flaking
characteristics of the surface are evaluated by grasping the needle
with a serrated jawed needle holder such as a Codman Classic Plus
needle holder. The needle holder is closed to the first locking
position and released. The needle is examined under a scanning electron
microscope at a magnification of approximately 500 times to determine
whether any of the material has flaked. Also, the needles are examined
at a magnification of 20 times to determine the intensity of the
color, the edge quality and the uniformity of the colored needle.
The blackened needles are passed through a chamois under a microscope
to see if any of the surface of the coating comes off on the chamois.
The penetration performance of the needle is determined utilizing
a curved needle penetration tester. Two sensations are determined
when testing the needle for penetration. The first is, the force
to initially penetrate the point through a standard material and
the second is to determine the drag on a needle as it passes through
the appropriate material. The combination of these forces is reflected
in the total force to penetrate and is measured on an Instron tester.
FIG. 3 is a block flow diagram depicting the various steps which
may be used to produce the needles of the present invention. First
and as shown in Box A, the needle having the desired shape and a
desired degree of sharpness and made from a steel containing chromium
is selected. Steel containing chromiums are required in order to
produce hard needles which will retain sharp cutting edges. The
selected needle is treated (Box B) to render the surface of the
needle activated; that is, to allow the chromium on the surface
of the needle to form oxides. Two techniques for activating the
surface of the needle are to either electroclean or electropolish
the needle immediately before the blackening treatment. If the surface
of the needle is not suitably activated, a thin layer of the metal
is removed in the process and the cutting edges dulled and the surface
roughened or channeled. The dulling and roughening greatly increases
the penetration forces required with the needle and make the needle
unsuitable for use in many surgical procedures where tissue trauma
must be kept to a minimum. The treated needle is submersed in a
solution of sulfuric acid, potassium dichromate, and water (Box
C). Solutions, having a specific gravity of about 1.5 to 1.6 have
been found satisfactory. The solutions are prepared by mixing about
60 to about 65 percent by weight of sulfuric acid with the remainder
water. About 7 to about 10 percent of weight of Potassium dichromate
is combined with the sulfuric acid water mixture to form the blackening
solution. The solution is heated to a temperature of at least 100.degree.
C. and maintained at about 100.degree. and below the boiling point
of the solution or about 135.degree. C. (Box D). To obtain the advantages
of the present invention, it is important that the blackening treatment
be carried out at temperatures in excess of 100.degree. C. The needle
is maintained in the solution for a sufficient length of time to
darken the needle surface (Box E). Periods of time of from about
4 minutes up to 30 minutes or even longer have been found satisfactory.
Other dichromate salts, such as sodium dichromate, may also be used.
The needle is removed from the solution (Box F) and the needle
rinsed to remove solution residue by running hot water over the
needle (Box G). The needle is preferably ultrasonically rinsed needle
is lubricated (Box I) and an appropriate suture is attached to the
blunt end of the needle (Box J). The blunt end of the needle would
usually have a drilled hole or a channel with a suture swaged into
the hole or channel as is well known in the art. The needle and
suture is packaged in a suitable Package (Box K) and the package
sterilized (Box L) by cobalt radiation or ethylene oxide or other
sterilization techniques as are well known in the art.
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