Surgical needle abstract
A method for producing a detachable surgical needle-suture combination
of the type incorporating a fluid swellable suture material is capable
of producing needle-suture attachments which conform to the prescribed
minimum pull-out forces for detachable needle-suture combinations
as set forth in the U.S. Pharmacopeia. Generally, the method includes
the steps of providing a surgical needle and a fluid swellable suture,
immersing an end portion of the suture into a liquid solution whereby
the suture end portion swells and assumes an expanded condition,
positioning the suture end portion in its expanded condition into
an aperture formed in the blunt end of the needle and swaging the
blunt end of the needle to cause deformation of at least a portion
of the blunt end and engagement with the suture end portion to effect
needle-suture attachment.
Surgical needle claims
What is claimed is:
1. A method for producing a surgical needle-suture combination,
comprising the steps of:
(a) providing a surgical needle and a suture, the needle having
a blunt end with an aperture formed therein, the suture including
a fluid swellable material and having an end portion suitably configured
for insertion into the aperture of the needle;
(b) immersing the end portion of the suture into a liquid solution
whereby the suture end portion swells and assumes an expanded condition;
(c) positioning the suture end portion into the aperture formed
in the blunt end of the needle; and
(d) swaging the blunt end of the needle to cause deformation of
at least a portion of the blunt end such that the blunt end portion
compresses the suture end portion to attach the suture to the needle.
2. The method according to claim 1 wherein step (d) involves swaging
the blunt end of the needle to form a removable needle-suture attachment.
3. The method according to claim 2 wherein step (a) includes providing
a suture fabricated from a collagenous material.
4. The method according to claim 3 wherein step (b) includes immersing
the end portion of the suture in a solution consisting of isopropanol,
triethanolamine solution and water.
5. The method according to claim 3 wherein step (b) includes immersing
the end portion of the suture for a period of at least 12 hours.
6. The needle-suture combination formed in accordance with the
method of claim 3.
7. The method according to claim 2 wherein step (a) includes providing
a curved surgical needle.
8. The method according to claim 2 wherein step (a) includes providing
a straight surgical needle.
9. The method according to claim 2 wherein step (a) includes providing
a surgical needle fabricated from stainless steel.
10. The needle-suture combination formed in accordance with the
method of claim 2.
11. A method for producing a surgical needle-suture combination,
comprising the steps of:
(a) providing a surgical needle and a suture, the needle having
a blunt end with an aperture formed therein, the suture including
a fluid swellable material and having an end suitably configured
for insertion into the aperture of the needle;
(b) immersing the suture end into a liquid solution whereby the
suture end swells and assumes an expanded condition;
(c) positioning the swelled suture end into the aperture formed
in the blunt end of the needle; and
(d) swaging the blunt end of the needle to bring at least a portion
of the inner surface defining the aperture into compressing engagement
with at least a portion of the suture end to attach the suture to
the needle.
12. The method of claim 11 wherein step (b) includes immersing
the suture end in a solution consisting of isopropanol, triethanolamine
solution and water.
13. The method of claim 11 wherein step (b) includes immersing
the suture end for a period of at least 12 hours.
Surgical needle description
BACKGROUND
1. Technical Field
The present disclosure relates to the attachment of surgical sutures
to surgical needles. In particular, the disclosure relates to a
method for the attachment of surgical needles to collagenous "catgut"
surgical sutures to provide a combined surgical needle-suture device
possessing controlled suture release characteristics.
2. Background of Related Art
For many years, surgeons have employed needle-suture combinations
in which a suture or ligature is attached to the shank end of a
needle. Such needle-suture combinations are provided for a wide
variety of monofilament and braided suture materials, both absorbable
and non-absorbable, e.g., catgut, silk, nylon, polyester, polypropylene,
linen, cotton, and absorbable synthetic materials such as polymers
and copolymers of glycolic and lactic acids.
Needle-suture combinations fall into two general classes: standard
needle attachment and removable or detachable needle attachment.
In the case of standard needle attachment, the suture is securely
attached to the needle and is not intended to be separable therefrom,
except by cutting or severing the suture. Removable needle attachment,
by contrast, is such that the needle is separable from the suture
in response to a force exerted by the surgeon. Minimum acceptable
forces required to separate a needle from a suture for various suture
sizes are set forth in the United States Pharmacopeia (USP XXII
1990). The United States Pharmacopeia prescribes minimum individual
pull-out forces and minimum average pull-out forces as measured
for five needle-suture combinations. The minimum pull-out forces
for both standard and removable needle-suture attachment set forth
in the United States Pharmacopeia are hereby incorporated by reference.
One typical method for securely attaching a suture to a needle
involves providing a cylindrical recess in the shank end of a needle
and securing a suture therein. For example, U.S. Pat. No. 1558037
teaches the addition of a cement material to such a substantially
cylindrical recess to secure the suture therein. Additional methods
for bonding a suture within a needle bore are described in U.S.
Pat. Nos. 2982395 (adhesives) and 3394704 (bonding agents).
Alternatively, a suture may be secured within an axial bore in a
needle by swaging the needle in the region of the recess, see, e.g.
U.S. Pat. No. 1250114. Additional prior art methods for securing
a suture within a needle bore include expansion of a catgut suture
through the application of heat (U.S. Pat. No. 1665216), inclusion
of protruding teeth within the axial bore to grasp an inserted suture
(U.S. Pat. No. 1678361) and knotting the end of the suture to
be inserted within the bore to secure the suture therein (U.S. Pat.
No. 1757129).
Methods of detachably securing a suture to a needle are also well
known. For example, a prevailing controlled release needle-suture
attachment is swaged or crimped described in U.S. Pat. Nos. 3890975
3980177 4060885 and 4072041. In accordance with the methods
taught by these patents, a suture tip is inserted into a drilled
end of the needle and the needle end is swaged to engage the suture
to effect needle-suture attachment.
The methods described in the above patents for forming detachable
needle suture combinations are intended to provide minimum pull-out
forces within a desired range. With suture materials that are stable
when packaged or stored, the pull-out value remains within the targeted
pull-out range. However, certain materials, such as catgut, have
a tendency to expand or swell when exposed to moisture, such as
conditioning fluid typically provided in the catgut suture package.
As a consequence, this expansion adversely increases the pull-out
force required to detach the suture from the needle.
In an effort to account for the increase in dimension of fluid
swellable suture materials upon exposure to moisture and, thus,
an increase in the force required to detach the suture from the
needle, attempts have been made to initially decrease the swaging
force during needle-suture attachment so that the pull out force
subsequent to packaging (and, hence after any swelling) would be
within an acceptable range. However, this approach is not feasible
since the attachment force prior to packaging must be lowered to
unacceptable levels. Consequently, the decreased attachment force
results in the sutures having a tendency to prematurely detach during
subsequent processing steps, such as packaging, thereby requiring
excessive special handling.
Other attempts to accommodate for suture swelling during storage
include providing a needle end having an increased dimensioned recess
or axial opening to accommodate subsequent expansion of the gut
suture material during storage. see, e.g., U.S. Pat. Nos. 3924630
and 4124027. However, with the methods suggested in these two
patents, the suture in its dry non-swollen condition, i.e., prior
to packaging in a conditioning fluid, is subject to displacement
within the enlarged recess of the needle and, consequently, is prone
to prematurely detach from the needle.
Accordingly, the present disclosure is directed to a method for
attaching a fluid swellable suture material to a surgical needle
whereby the attachment formed meets the minimum pull-out forces
for detachable needle suture devices as set forth in the United
States Pharmacopeia.
SUMMARY
The present disclosure is directed to a method for producing a
detachable surgical needle-suture combination of the type incorporating
a suture material which expands upon exposure to moisture or conditioning
fluid during, for example, storage in a suture package. The method
disclosed is capable of producing needle-suture attachments which
conform to the prescribed minimum pull-out forces for detachable
needle-suture combinations as set forth in the U.S. Pharmacopeia.
Generally, the method includes the steps of providing a surgical
needle and a fluid swellable suture, immersing an end portion of
the suture into a liquid solution whereby the suture end portion
swells and assumes an expanded condition, positioning the suture
end portion in its expanded condition into an aperture formed in
the blunt end of the needle and swaging the blunt end of the needle
to cause deformation of at least a portion of the blunt end and
engagement with the suture end portion to effect needle-suture attachment.
One of the distinct advantages of the present invention is that
the suture end portion is in an expanded condition prior to the
swaging attachment. Accordingly, the dimensional characteristics
of the suture remain stable (since it has achieved its fully expanded
condition) subsequent to the swaging operation and during storage
in the suture package. Thus, the needle pullout values as controlled
by the swaging operation remain substantially constant, thereby
resulting in fewer rejected units.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the disclosure is described hereinbelow
with reference to the drawings wherein:
FIG. 1 is a partial cross-sectional view of a needle-suture combination
in accordance with the principles of the present disclosure; and
FIG. 2 is a flow chart depicting the novel process for forming
the needle-suture combination of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
Referring now to FIG. 1 there is illustrated a surgical needle-suture
combination produced in accordance with the principles of the present
disclosure. Needle 10 includes drilled needle end 12 having an axial
opening or bore 14 for reception of one end of suture 16. A swaged
portion 18 is produced by swaging dies which causes deformation
of that portion 18 whereby the inner surfaces of the needle end
12 securely engage the suture end inserted within the bore 14. Examples
of suitable swaging dies for needle-suture attachment are disclosed
in commonly assigned U.S. patent application Ser. No. 08/071653
filed Jun. 2 1993 and U.S. Pat. Nos. 5046350 and 5099676 the
contents of each being incorporated herein by reference.
Needle 10 may be any type of surgical needle including curved,
straight or the like, provided it has an elongated aperture or bore
in needle end 12 for receiving suture 16. Preferably, the bore defines
a cross sectional dimension which corresponds to the cross sectional
dimension of the suture end portion in its expanded state. The needle
may be fabricated from stainless steel. Suture 16 contemplated for
use with the present invention is fabricated from a fluid swellable
material, i.e., a material which has a tendency to expand upon exposure
to moisture such as collagenous or "gut" suture material,
cotton and the like.
Referring now to FIG. 2 there is illustrated a flow chart depicting
the novel process for forming the needle-suture combination of FIG.
1. Generally stated, the process involves three steps. The first
step involves immersing an end portion of a fluid swellable suture,
e.g., gut suture material, into a liquid conditioning solution.
The suture upon immersion absorbs the liquid, and consequently,
expands in dimension to define a greater cross-sectioned area than
in its original dry state. Thereafter, the process is continued
by inserting the suture end portion in its expanded condition into
the aperture or opening 14 of the drilled end 12 of the needle 10.
Needle end 12 is thereafter swaged by a crimping operation to cause
deformation of the needle end and contacting engagement of the inner
surfaces of the needle end with the inserted suture thereby forming
the needle-suture attachment.
Unlike prior art methods for attaching a fluid swellable suture
to a needle, in accordance with the principles of the present disclosure,
the suture is initially immersed in the conditioning fluid prior
to needle-suture attachment. Thus, expansion of the suture material
is complete prior to the swaging step.
Accordingly, the swaging step can be performed to produce a detachable
needle-suture attachment within the desired ranges as set forth
in U.S. Pharmacopeia without concern of subsequent swelling and,
consequently, changes in the detachment force during, for example,
storage in a suture package.
The preferred conditioning fluid utilized in the first or immersing
step consists of about 89% isopropanol, 1% triethanolamine solution
and 10% water. This particular mixture is commonly available and
is also commonly used as a conditioning fluid in suture packages.
The duration of time for immersing the gut suture may vary depending
on the suture size, but, preferably extends for a minimum of twelve
(12) hours before removal. This twelve hour period is sufficient
to ensure complete saturation of the gut suture end such that expansion
of the suture material is complete prior to insertion into the drilled
end 12 of the needle 10.
The second or swaging step can be performed using any conventional
swaging apparatus and die arrangement such as that disclosed in
the aforementioned commonly assigned U.S. patent application Ser.
No. 08/071653 and U.S. Pat. Nos. 5046350 and 5099676. The swaging
force of the dies can be readily adjusted to the parameters and
dimensions of the needle and suture so as to produce a detachable
needle-suture attachment. It is to be appreciated that the swaging
step may alternatively be adjusted to form a non-detachable suture
attachment if desired.
The suture with expanded tip portion is inserted into the needle
bore and the attachment completed before the suture begins to dry
out. Preferably, the suture is withdrawn from the immersion solution
and promptly attached to a needle within a few hours. Most preferably,
the suture is inserted into and attached to a needle within a few
minutes of being withdrawn from the immersion fluid.
The present disclosure provides a needle-suture device which possesses
a pull-out value within the desired range and which remains substantially
stable during storage in a suture package.
While the above description contains many specifics, these specifics
should not be construed as limitations on the scope of the invention,
but merely as an exemplification of a preferred embodiment thereof.
Those skilled in the art will envision other possible variations
that are within the scope and spirit of the invention as defined
by the claims appended hereto.
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