Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
;i 5ingle use, eyeless, or drilled end needles, are
meeting with increasing acceptance for surgical suture usages.
These are needle~ in which a concentric axial hole is formed
in the base or back end of the needle into which the end of
a suture is placed and crimped.
One of the problems in using a drilled end needle
on a suture is that during use of the suture may be bent and
twisted sharply at the point of attachment to the needle
where the suture comes out of the hole in the end of the need-
le, which may cause the suture to break. Bending particular-
ly ha~ been recognized, and various expedients for solving
the problem have been devised but new and improved systems
are in demand.
DESCRIPTION OF THE PRIOR ART
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U. S. Patent 1,558,037, Morton, SURGICAL NEEDLE AND
SUTURE ASSEMBLY AND METHOD OF MAKING THE SAME, October 20,
1925, shows a drilled end needle crimped on a suture.
U. S. Patent 1,981,651, Logan, SURGICAL NEEDLE AND
SUTURE, November 20, 1934, shows an internally threaded tube
which is contracted at the back end and screwed onto the end
of a surgical needle, so that the tube can be threaded over
the end of a suture, which is then knotted, drawn into the
tube, and the tube screwed onto the surgical needle. Both
swollen ends and sleeves are disclosed to retain the suture
in the contracted end of the threaded tube.
U. S. Patent 3,038,475, Orcutt, SURGICAL NEEDLES
AND MU~NUFACTURE OF SAME, June 12, 1962, shows curved and
straight drilled end needles with hollow ground points.
U.S. Patent 3,125,095, Kaufman et al., FLEXIBLE
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STAINLESS STEEL SUTURES, March 17, 1964, shows a polyfilamentary stainless
steel suture, crimped in a drilled end needle.
U. S. Patent 3,311,110, Singerman et al, FLEXIBLE COMPOSITE SUTURE
HAVING A TANDEM LINKAGE, March 28, 1967, shows a flexible monofilament leader ~ -
between an eyeless surgical needle and a monofilament stainless steel suture.
Column 3 of this patent describes tests of flexibility at the needle-suture
junction.
U.S. Patent 3,910,282, Messer and Singerman, NEEDLING MONOFILAMENT
SUTURES, October 7, 1975, shows a counterbore system to reduce flex and
fatigue failure at the point of attachment of a suture to its needle.
British Patent 1,424,953, A. S. Taylor and M. H. Weinert, LASER
MANUFACTURE OF SUTURE NEEDLES, granted June 16, 1976, shows using a laser -
beam to drill a hole in the end of a need'e blank, which hole is tapered
by the nature of the laser drilling. The hole is then swaged to size and
cylindrical shape.
It has now been found that breakage of surgical sutures at their
juncture with a drilled end surgical needle is caused not only by the sharp
flexing where the suture emerges from the drilled end of the needle but by
torsional forces introduced by twisting of the needle with respect to the
suture at the junction. During emplacement of a suture by a surgeon,
frequently there is a certain degree of twisting of the needle with respect
to the suture which tends to cause a torsional loading of the suture at its
point of attachment to the needle. This is in addition to any stresses and
strains that may be introduced by bending the suture with respect to the
needle. Without getting into a complete mathematical analysis of the
combination of such strains and stresses, it is obvious to students of stress
analysis that markedly higher strain and stresses will be introduced into
the suture at its attachment to the needle.
It has now been found that by forming a swivel at the junction, so
that the suture may rotate with respect to the needle, stresses at the point
of attachment are markedly reduced and failures are minimized. The improved
results are particularly noticeable with monofilament sutures, and particular-
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ly, those having a high Young's Modulus. A rigorous mathematical analysis
would be illusory because it could not be founded upon perhaps rash assump-
tions as to rotational and bending motions of the needle in a surgical
procedure.
By attaching the needle to the suture so that the suture can swivel
in the needle, improved results are obtained by the surgeon in that accident-
al detachment of the needle from the suture is markedly reduced and addition-
ally in flex tests in which torsion is a factor, improved test results can be
obtained in the laboratory. The surgical needles used may be straight or
curved, including 3/8 or 1/2 circle needles, and the needles may be tapered
pointed, or three cornered cutting edge needles, or reverse cutting edge
needles, or duck billed or side cutting needles, any of which may have flats
on them for the needle holders, or other conventional shapes of surgical
needles. Torsion is more apt to be a problem with curbed needles as the
plane of curvature must be oriented with respect to the subject during use.
A swivel attachment is particularly useful with monofilament steel
sutures as such sutures are quite torsionally stiff. The swivel end may be
used with multi-filament sutures either braided or twisted. The advantages
of this swivel attachment are greater with metallic sutures which have a
higher torsional stiffness.
Thus, according to a first broad aspect of the present invention,
there is provided an eyeless surgical needle in combination with a surgical
suture comprising: a surgical suture having a suture retaining enlargement
;~ adjacent the end thereof, and a one-piece pointed, eyeless surgical needle
having a cylindrical bore at the back end of the needle, with the suture
retaining enlargement in said cylindrical bore, and the back end of the
needle crimped smaller into retaining relationship with said enlargement,
whereby the suture can swivel with relationship to the needle, but is re-
-~ tained in said cylindrical bore.
According to another broad aspect of the present im~ention, there
is provided a method of forming an eyeless surgical suture needle - surgical
suture combination comprising: flattening the end of a monofilament stainless
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steel suture to enlarge one diameter thereof, forming a bore hole in the
back end of a one piece eyeless surgical needle which hole is slightly larger
in diameter than the said enlarged diameter, inserting the end of the suture
having the said enlarged diameter into said bore hole, and crimping the back
end of the needle behind said enlarged diameter so that the crimped bore
hole is smaller than said enlarged diameter, but larger than the suture dia-
meter, whereby the suture and needle may swivel with respect to each other,
but the suture is reatined in the said needle.
Other advantages and objects of the present invention are apparent
from the following detailed description and drawings.
DRAWINGS
FIGURE 1 shows a curved surgical needle to which is attached a
steel suture.
FIGURE 2 is an enlarged view in partial cross-section showing a
flattened end of a wire suture ready to be assembled to a drilled-end
surgical needle.
FIGURE 3 shows an axial or end view of a wire suture with a
flattened end.
FIGURE 4 shows the flattened wire end inserted in the drilled-end
needle, and crimped around the suture.
FIGURE 5 shows a spherical ball on the end of the suture.
; FIGURE 6 shows an axial v ew looking at the ball on the end of
the suture.
As shown in FIGURE 1 a stainless steel monofilament surgical suture
11 is attached to an eyeless suture needle 12. The sizes of sutures in most
countries conform to a Governmental or Industrial standard. In the United
States, sizes conform to the United States Pharmacopeia standards. Because
each of the several sizes has a maximum diameter and because the greater
diameter of the suture the stronger, it is customary to merchandise sutures
which are just under the maximum diameter and hence have the greatest
strength for each
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standard size, The drawings and further description are de-
signed to illustrate the relationship between the suture and
the needles in the standard sizes. In the table gi~en below
the configurations of sizes, flattened ends and needle bore
diameters are shown. In areas where different suture stand-
ards pertain, a minor modification in wire diameter may be
used with analogous modifications in the other dimensions
to fit the standards of a particular country.
The sutures may be either single or double armed --
that is have a needle on one or both ends. As shown, a need-
le is attached to only one end, as a needle attached to the
other would be strictly comparable, and is well known to those
skilled in the art.
As shown in FIGURE 2 the suture 11 has at its end a
suture retaining enlargement 13. This is conveniently formed
by cold forming the end of a metal suture. Conveniently, a
long piece of wire can be both cut and have the end flattened
at a single operation. The cold forming of the end is con-
veniently to a thickness of from one-third to two-thirds of
its original diameter so that in cold forming the wire expands
; its lateral diameter, so that it nearly fills the needle bore
diameter at the back end of the drilled end needle.
Conveniently, the cold forming end appears as a flat
disc, but its exact shape is not critical.
The eyeless suture needle 12 has formed in its rear
end a cylindrical bore 14. Conveniently this hole is formed
by using a small drill. It may be formed by a laser beam,
chemical or electrical etching, or by a separate sleeve which
is formed at the end of the solid portion of the needle.
Whatever the method of forming, the needle is one piece with
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an ~xial hole at the rear end, foxming the cylindrical bore 14.
The length of the cylindrical bore should be at
least three to five times its diameter, which permits inser-
tion of the suture retaining enlargement on the end of the
suture wire in the cylindrical bore, and then compressing to
form the crimp 15 on the back end of the needle, The inside
diameter of the crimp is smaller than the suture retaining
enlar~ement, and is larger than the suture diameter so that
the suture may swivel with the respect to the needle with low
friction. Preferably the crimp has a slight flare 16 at the
-~ point where the suture emerges from the bore as this permits
additional bending and avoids having a sharp edge against which
the suture may be drawn.
FIGURE 5 shows a slightly different modification in
that the suture 17 has formed on the end thereof a retaining
ball 18. This retaining ball may be formed by swedging the
suture wire, as for example the end of the suture may be com-
pressed back on itself in a suitable die so as to be enlarged
to form a ball. The ball may be formed by a small drop of
silver solder on the end of the suture. The appearance is
essentially the same, as is shown in Figures 5 and 6.
A ball slides some what more freely in the crimped
end of the cylindrical bore but is more costly to form and
normally a flattened end is satisfactory and less expensive.
The easiest way of forming the suture retaining
; enlargement 13 is to use a cutting die with a shoulder so that
after the cutting of the suture, the shoulder compresses the
end of the suture against the top of a cutting die, and by
having a stop to control the degree of the compression, the
end of the suture can be cold formed to a desired thickness.
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PXopoxtions which have been found to give good re-
sults are shown in the following table, which shows suture
size, wire diameter for that suture size, the cold formed
flattened thickness of the suture retaining enlargement, and
5 the needle bore diameter.
Flat
Suture Suture Dimension Needle bore
- Size Wire Dia. Thickness Diameter
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5/0 .0047-.0055" .0015" .0102-.0110"
4/0 .0073-.0085" .0030" .0152-.0162"
3/0 .0090-.0105' .0040" .0182-.0192"
2/0 .0115-.0134" .0055" .0212-.0222"
0 .0154-.0165" .0070" .0235-.0245"
.0180-.0194" .0090" .0284-.0299"
2 .0200-.0225" .0120" .0302-.0317"
- 3 .0230-.0254" .0140" .0360-.0375"
4 .0260-.0285" .0165" .0425-.0440"
The same bore diameter may be used for different
size needles so that different sizes of needles may be used
with any particular suture. The degree of crimp is control-
led so that with uniform suture retaining enlargements, the
20 crimp is tight enough to hold the suture retaining enlarge-
ment on the end of the suture and yet permit rotation of the
suture and needle with respect to each other. If desired, the
crimp may be accurately controlled, so as to give a controlled
degree of pull-off, that is a needle may be crimped so that
25 it pulls free from the suture with less than the breaking
stress on the suture.
In surgical use after emplacing the suture it is
necessary usually to tie a knot in the suture. In the tieing
of the suture, the surgeon frequently desires to have the need-
30 le removed from the end of the suture. This may be done by
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cutting the suture or if the pull-off strength is controlled,
the suture is held into the needle tightly enough so that it
permits emplacement of the suture and yet by increasing the
pull on the needle, the needle pulls free from the suture.
Such controlléd pull-off requires close control of the suture
retaining enlargement with respect to the crimp on the end of
the needle so that the pull-off is within a desired range.
Preferably the crimp is essentially uniform all
around the needle so that there is no off-center relationship
which would tend to lock the suture enlargement in place.
With a uniform crimp, the needle twist with respect to the
sutures permits minimizing torsional loads on the suture and
thus gives a marked reduction in the likelihood of the suture
breaking at its point of attachment to the needle during a
surgical procedure.
The advantages of a swivelled end needle are not
particularly apparent on an ordinary flex test in which the
needle is flexed 90, that is a total of 45 on each side of
the center, as a weight pulls the suture downward from the
suspended needle. In surgical usages where both flexure and
torsion occur, the number of failures during usage is remark-
ably reduced. If a test be used in which the needle is both
twisted and flexed at the same time, the advantages of the
swivel connection appear outstanding. Its particular advan-
tage is that as the surgeon twists the needle with respect tothe suture before pulling it through the tissue and frequent-
ly before any axial load is applied to the suture, a suture
can twist so tha* the applied load is purely axial, and there
is no additional torsion introduced into the suture during
its use.
