Surgical needle abstract
An apparatus is disclosed for attaching a surgical needle having
a generally cylindrical end portion defining an elongated aperture
having a generally circular cross-section and a suture having a
generally elongated end portion of generally circular cross-section
corresponding in dimension to the elongated aperture of the needle.
The apparatus includes a pair of dies, each having a die face with
an inner die surface portion. The inner die surface portion includes
at least one generally planar crimping surface having an arcuate
recess formed therein which extends along at least a portion of
the planar crimping surface. The arcuate recess defines a material
relief zone such that when the end portion of the suture is positioned
within the aperture of the needle and the dies are positioned about
the generally cylindrical end portion of the needle with the crimping
surfaces generally facing the outer surface thereof, the application
of an inward crimping force to the dies causes the dies to impact
the needle and produce inward crimping forces on opposed sides of
the needle end portion to attach the needle to the suture. The relief
zones defined by the arcuate recesses receive and collect deformed
material from the needle. According to the invention, the symmetry
of the needle is maintained and the attachment is predictable and
superior to those of the prior art.
Surgical needle claims
What is claimed is:
1. Apparatus for attaching two members, at least a first member
having a generally cylindrical outer end portion and defining an
elongated aperture having a generally circular cross-section and
a second member including a generally elongated end portion of generally
circular cross-section corresponding in dimension to the elongated
aperture of the first member, which comprises a pair of dies, each
die including a die face having an inner die surface portion dimensioned
to accommodate at least the end portion of the first member, each
said inner die surface portion including a substantially planar
inner swaging surface defining a plane which is angularly offset
relative to a plane defined by said die face, said swaging surface
having a generally arcuate concavity formed therein and extending
along at least a portion of said swaging surface, said dies being
positioned about the end portion of the first member such that said
planar swaging surfaces are angularly offset relative to a longitudinal
axis defined by the elongated aperture of the first member, wherein
the application of inward force to said dies toward each other causes
at least portions of said swaging surfaces of said dies to engage
the end portion of the first member and transmit inward swaging
forces thereto at an angle offset to the longitudinal axis of the
elongated aperture so as to attach the members, whereby said concavities
define relief zones which permit deformed material of the first
member to collect therein.
2. Apparatus for attaching a surgical needle having a generally
cylindrical end portion defining an elongated aperture having a
generally circular cross-section and a suture having a generally
elongated end portion of generally circular cross-section corresponding
in dimension to the elongated aperture of the needle, which comprises
a pair of dies, each die including a die face having an inner die
surface portion, each said inner die surface portion including at
least one generally planar crimping surface having an arcuate recess
formed therein which extends along at least a portion of said planar
crimping surface, said arcuate recess defining a relief zone such
that when the cylindrical end portion of the suture is positioned
within the aperture of the needle and said dies are positioned about
the generally cylindrical end portion of the needle with said crimping
surfaces generally facing the outer surface thereof, the dies being
positioned such that the planar crimping surfaces are angularly
offset relative to the longitudinal axis of the elongated aperture
of the needle end portion, applying inward crimping force to said
dies causes said dies to impact the needle and produce inward crimping
forces on opposed sides of the needle end portion to attach the
needle to the suture wherein said arcuate recesses receive and collect
deformed material from the needle so as to facilitate attachment
of the needle and the suture.
3. Apparatus according to claim 2 wherein each said planar crimping
surface defines a plane which is angularly offset relative to a
plane defined by said die face.
4. Apparatus according to claim 3 wherein said plane of said crimping
surface defines an angle ranging from about 6.degree. to about 15.degree.
relative to said plane of said die face.
5. Apparatus according to claim 4 wherein each said arcuate recess
of each said die is disposed along the approximate midline of said
planar crimping surface.
6. Apparatus according to claim 4 wherein said arcuate recess extends
for at least one-quarter the length of said crimping surface.
7. Apparatus according to claim 6 wherein said arcuate recess defines
a radius:of curvature which remains constant throughout its length.
8. Apparatus according to claim 7 wherein an axis defined by said
arcuate recess is substantially parallel to said plane defined by,
said die face.
9. Apparatus according to claim 8 wherein the depth of said arcuate
recess gradually decreases from a first end portion of Said die
to a second end portion thereof.
10. The apparatus according to claim 3 wherein said pair of dies
are dimensioned and adapted for attaching a surgical needle to a
surgical suture made of at least one of suture material such as
silk, nylon, linen, cotton, polyester, stainless steel, polypropylene,
nature materials such as catgut, and Synthetic polymers having glycolic
acid ester linkages subject to hydrolytic degradation to nontoxic,
tissue compatible absorbable components, including polyglycolic
acid.
11. The apparatus according to claim 10 wherein said pair of dies
are dimensioned and adapted for attaching a surgical suture in,
the form of a braided, or twisted multifilament or a monofilament
to a cylindrical member in the form of a surgical needle.
12. The apparatus according to claim 11 wherein said dies are preferably
of a hardened material such as tungsten carbide or high speed steel.
13. Apparatus for attaching a surgical needle having a needle end
portion defining an elongated aperture and a suture having a generally
elongated suture end portion, which comprises a pair Of dies, each
die including a die face having an inner die surface portion for
at least partial reception of the needle end portion, each die surface
portion including at least one generally planar crimping surface
having a generally arcuately-shaped concavity extending along a
portion of the crimping surface, (the dies being positioned such
that the planar crimping surfaces are angularly offset relative
to the longitudinal axis of the elongated aperture of the needle
end portion,) wherein the application of inward crimping force to
the dies causes the dies to impact the needle end portion to thereby
cause crimping of the needle end portion whereby the arcuately-shaped
concavity of each die is configured and dimensioned to receive and
collect deformed material of the needle so as to facilitate attachment
of the needle and suture.
14. The apparatus according to claim 13 wherein the arcuately-shaped
concavity of each die is disposed along the approximate midline
of the planar crimping surface.
15. The apparatus according to claim 14 wherein the arcuately-shaped
concavity defines a radius of curvature which remains constant throughout
its length.
16. The apparatus according to claim 15 wherein the arcuately-shaped
concavity of each die is positioned and dimensioned such that an
axis defined thereby is substantially parallel to the longitudinal
axis of the elongated aperture of the needle end portion.
Surgical needle description
1. Field of the Invention
The present invention relates to the attachment of surgical sutures
to surgical needles. In particular, the invention relates to a method
and apparatus for the attachment of surgical needles to surgical
sutures to provide a combined surgical needle-suture device possessing
controlled suture release characteristics.
2. Description 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 no-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 describes 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 securing 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. 2928395
(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 for detachably securing a suture to a needle are also well
known. For example, U.S. Pat. Nos. 3890975 and 3980177 teach
swaging a suture within a needle bore such that the suture has a
pull-out value of 3 to 26 ounces. Alternative detachable attachment
methods include providing a weakened suture segment (U.S. Pat. No.
3949756), lubricant tipping the end of a suture to be inserted
in the axial bore of a needle (U.S. Pat. No. 3963031) and pretensioning
a suture that is swaged within an axial needle bore (U.S. Pat. No.
3875946). See also, U.S. Pat. Nos. 3799169; 3880167; 3924630;
3926194; 3943933; 3981307; 4124027; and 4127133.
Another method for attaching a suture to a needle involves the
use of tubing which is secured to the shank end of the needle and
to the suture. For example, U.S. Pat. No. 1613206 describes the
use of a tubing (preferably silver) which is secured to the shank
end of a needle and to a ligature. It is suggested that the tube
may be attached to the needle by pressure or soldering and to the
ligature by pressure or cementing. It is also suggested that the
shank of the needle be of reduced cross section and that the furthest
extremity of the reduced diameter shank section be provided with
a spike or point upon which the suture may be secured prior to the
tube application.
U.S. Pat. No. 2240330 describes a tubing attachment method whereby
the tubing and suture are releasably secured to the needle. In particular,
the needle and tubing are provided with cooperating catch and abutment
means which are released one from the other by rotating the needle
90.degree. relative to the tubing (or vice versa). The tubing is
manufactured from spring-tempered carbon steel or chrome nickel
steel and is secured to the suture by heating the tubing and then
swaging to the suture.
U.S. Pat. No. 3311100 relates to a flexible composite suture
having a tandem linkage. The needle is secured to a flexible suture
leader manufactured from a readily sterilizable plastic such as
nylon, linear polyethylene, isotactic polypropylene, polyester,
silk or other proteinaceous material, e.g., by inserting and crimping
the leader within an axial bore in the needle shank. The opposite
end of the suture leader is crimped within a connector sleeve of
a thin walled metal tubing, e.g., stainless steel. The opposite
end of the tubing is crimped around a stiff suture, e.g., monofilament
stainless steel.
Additional patents which describe the use of tubing to effect suture-needle
attachment include U.S. Pat. Nos. 4672734 (forming needle from
U-shaped metal plate around suture ), 4359053 (silicone tubing),
3814296 2802478 (chamfered tubing ends), 2302986 2240330
1981651 (needle and tubing screw threaded), 1960117 and 1591021.
Commonly assigned, U.S. Pat. No. 5139514 describes a combined
surgical needle-suture device in which a surgical needle having
a shank of reduced cross-section is attached to a suture through
a shrinkable tubing, or micro-ferrule, which is fitted about the
needle shank and a portion of the suture. Application of energy
to the shrinkable tubing brings the tubing into engagement with
both the needle shank and the suture. The physical and chemical
characteristics of the shrinkable tubing material, the relative
diameters of the tubing, the needle shank and the suture, and the
amount of energy applied to the tubing may be controlled to,provide
a needle-suture combination having a desired pull-out force. It
is thus possible to produce standard needle-suture combinations
and removable needle-suture combinations using a single attachment
process and a common inventory of materials.
These pull-out forces are obtained by prestressing the suture,
i.e., by applying tension to the suture after the tip of the suture
has been inserted into an axial bore, or recess, formed in the blunt
end of the needle and the needled suture has been swaged so that
the force required to pull the suture out of the recess exceeds
the minimum limits on needle attachment set forth in the United
States Pharmacopeia but is less than the actual tensile strength
of the suture used. As the suture is pulled from the needle during
application of the tensioning force, the force required to move
the end of the suture relative to the needle recess drops to the
desired pull-out value, where the tension is released.
A prevailing controlled release needle-suture attachment is a swage
or crimp attachment, such as described in the foregoing U.S. Pat
Nos. 3890975 and 3980177. Swaging dies for achieving removable
needle attachment are disclosed in U.S. Pat. Nos. 4060885 and
4072041. Conventional crimp operations of the type disclosed in
these patents are difficult to control. Usually a crimp is created
between several dies which close to a fixed gap. Any variation in
the crimping dies, the apparatus for closing the dies, the needle
size, the hole size, or the suture size will increase variability
of the needle suture attachment. Particularly with the manufacture
of controlled release sutures, it heretofore has been critical to
form the surgical needle to precise dimensions, i.e., the diameter
of the needle and the size of the drilled hole may often have to
be manufactured within a tolerance of .+-.0.0005 inches to achieve
acceptable attachment. Similarly, the suture end to be attached
to the needle has to be constructed within similar tight tolerances
to assure that the combined tolerances of the suture and needle,
when crimped with the crimping die apparatus result in a "pull-out"
force within a narrowly defined range. These manufacturing demands
result in increased manufacturing time and waste and, hence, increased
cost to the manufacturer.
In addition, conventional crimping operations often distort the
end of the needle thereby causing it to lose its symmetry. This
is undesirable because it may result in an unacceptable pull-out
force or increased trauma to tissue when the non-symmetrical needle
is drawn through the tissue.
For example, one conventional crimping method requires that the
back end of the needle be struck with two opposed dies. The needle
is then rotated 90.degree. and the dies are arranged to strike the
needle a second time. In effect, the first strike changes a round
hole into one of elliptical shape, i.e., major and minor axes. The
act of rotating the needle 90.degree. and repeating the operation
to some extent completes the attachment. However, these procedures
increase handling during manufacture and the likelihood that unacceptable
attachment will be achieved. Indeed, rotating the suture and needle
before the attachment is complete is likely to dislodge the suture
tip in whole or part prior to completion of the attachment, resulting
in unacceptable attachment. Moreover, multiple opposing die hits
may produce a distorted needle end which results in corresponding
asymmetry of tissue apertures and trauma during use.
In addition to size effects, the surface smoothness of the suture
and the needle aperture, and the presence of any lubricants applied
to either the suture or the needle may affect the resulting pull-out
values. The conventional method of crimping, as described, underscores
many of these parametric inconsistencies and necessarily utilizes
multiple hits to overcome these process variabilities.
Commonly assigned U.S. Pat. Nos. 5046350 to Proto et al. and
5099676 to Proto et al. disclose crimping or swaging die configurations
for attaching surgical needles and sutures. The split ring die disclosed
in the U.S. Pat. No. 5046350 includes a relief zone defined between
a pair of extensions. A needle positioned between a pair of the
split ring dies is stricken by the extensions whereby the superfluous
material caused by the swaging action collects within the relief
zone. The novel configuration of the split ring die provides a more
uniform swage while the needle retains its circular symmetry in
the area of suture attachment.
U.S. Pat. No. 5099676 discloses a die featuring a novel clover
leaf shape which is defined by a generally circular surface having
a series of interconnected alternating individual convex and concave
curved surfaces. The convex and concave surfaces permit needle material
swaged during the crimping process to flow from the convex portions
which perform the actual crimping action to the concave areas so
as to collect within the concave portions. The clover leaf dies
provide unique attachment of the suture components and also maintains
the symmetry of the product.
The present invention is directed to a unique die arrangement and
the swage formed thereby which overcome the inherent disadvantages
associated with conventional crimping dies and processes, particularly
applied to a suture needle to achieve removable needle-suture attachment.
In accordance with the method and apparatus of the present invention,
attachment is achieved while retaining the symmetry of the needle.
A significant advantage of the method and apparatus of the present
invention resides in the fact that the needle-suture components
need not be manufactured to as strict tolerances in order to achieve
consistent attachment and pull-out force. In addition, the method
and apparatus for attaching needles to sutures requires less handling
of the suture and needle and reduces process control requirements.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus for attaching
a surgical needle having a generally cylindrical end portion defining
an elongated aperture of generally circular cross-section and a
suture having a generally elongated end portion of generally circular
cross-section corresponding in dimension to the elongated aperture
of the needle. The apparatus comprises a pair of dies with each
die including a die face having an inner die surface portion. Each
inner die surface portion includes at least one generally planar
crimping surface having an arcuate recess formed therein which extends
along at least a portion of the planar crimping surface. The arcuate
recess defines a relief zone such that when the cylindrical end
portion of the suture is positioned within the aperture of the needle
and the dies are positioned about the generally cylindrical end
portion of the needle with the crimping surfaces generally facing
the outer surface thereof, applying inward crimping force to the
dies causes the dies to impact the needle and produce inward crimping
forces on opposed sides of the needle end portion to attach the
needle to the suture whereby the arcuate recesses receive and collect
deformed material from the needle while maintaining the same cross-sectional
dimension of the needle in the portion crimped by the dies.
In the preferred embodiment, each planar crimping surface defines
a plane which is angularly offset relative to a plane defined by
the die face. The arcuate recess of each die is disposed along the
approximate midline of the planar crimping surface and may extend
for at least one-quarter the length of the crimping surface. Preferably,
the arcuate recess defines a radius of curvature which remains constant
throughout its length.
A pair of dies according to the present invention may be used to
form detachable needle-suture combinations whereby the suture may
be readily separated from the needle by a predetermined force by
the user. In the alternative, the dies may form a non-detachable
needle-suture combination whereby separation of the suture is accomplished
by cutting.
The present invention is also directed to a method for attaching
a surgical needle having a generally cylindrical outer portion and
a blunt end with a substantially circular elongated aperture formed
therein to a suture having an end portion suitably configured for
insertion into the aperture. The method comprises the steps of providing
a pair of dies with each die including a die face having an inner
die surface portion for at least partial reception of the cylindrical
outer portion of the needle, each die surface portion including
at least one generally planar crimping surface having a generally
arcuate-shaped concavity extending along a portion of the crimping
surface, positioning the pair of dies adjacent the corresponding
cylindrical portion of the needle with the inner die surface portions
of the dies facing the generally cylindrical outer surface of the
needle and the arcuate-shaped concavity extending along the direction
of the needle portion which defines the elongated aperture and applying
inward impact force to the dies to displace the dies toward each
other causing the generally planar crimping surfaces of each die
to engage the surface of the needle to thereby cause crimping of
the needle and reduction of an average dimension of the aperture
defined therein. The arcuate-shaped concavity of each said die is
configured and dimensioned to permit deformed material of the needle
to be received and collected therewithin so as to facilitate attachment
of the needle and the suture.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiment of the invention are described hereinbelow
with reference to the drawings wherein:
FIG. 1 is a plan view of a pair of conventional dual lap-overlap
semicircular shaped dies;
FIG. 2 is a perspective view of a swaging die constructed according
to the present invention;
FIG. 3 is a rear axial view of a pair of dies constructed in accordance
with the invention and shown with a needle positioned for attachment
to a suture;
FIG. 4 is a cross-sectional view taken along lines 4--4 of FIG.
3;
FIG. 5 is a rear axial view similar to the view of FIG. 3 illustrating
the dies in a closed position engaging the needle end;
FIG. 6 is a cross-sectional view taken along lines 6--6 of FIG.
5;
FIG. 7 is a plan view of the "crimped" needle illustrating
the effects of the dies of the present invention on the needle surface;
FIG. 8 is an end view of a needle crimped by the dies of the present
invention;
FIG. 9 is a front view of an apparatus with which the dies constructed
according to the present invention may be utilized to attach a suture
to a needle by crimping;
FIG. 10 is a side view of the apparatus shown in FIG. 9;
FIG. 11 is an exploded view illustrating the dies of the present
invention mounted in the apparatus of FIG. 9 for attaching a suture
to a needle; and
FIG. 12 is an exploded side view of a pair of dies constructed
according to the present invention positioned to attach a suture
to a curved surgical needle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring initially to FIG. 1 there is illustrated a pair of prior
art dies 10 12 of a type utilized to attach a suture to a surgical
needle. Each die 10 has a working surface at 14 of generally semi-circular
shape and adjacent arcuate corner portions 16 to receive limited
amounts of excess needle material overflowing during the crimping
process. The arcuate corner portions 16 are of lesser radii than
the working surface and are not concentric therewith as shown.
To attach a needle to a suture, the dies are positioned within
an apparatus as will be described hereinbelow. The apparatus is
arranged to cause both dies to simultaneously move toward each other
and strike a needle positioned between them. This causes the needle
to become elliptical in cross-section and causes portions of the
needle to deform into corner portions 16. Once the dies are impacted
toward each other, they are separated and the needle is rotated
90.degree.. The dies are then struck once again and the attachment
is completed. In essence, the first strike causes the circular aperture
in the needle to become elliptical. The second strike completes
the attachment and reverses the distortion imparted to the needle.
In certain instances additional hits are required to secure the
suture to the needle. This procedure necessitates at least a dual
step attachment which in turn requires additional time and labor.
Referring now to FIGS. 2-4 there is illustrated a pair of dies
20 constructed according to the present invention. Each die 20 is
configured to have an inner cavity 22 (FIGS. 2 and 3) which, when
combined with the other die of the pair, forms a generally rectangular
opening for reception of an end of a needle to be swaged. The particular
arrangement of the pair of dies 20 is best depicted in the axial
view of FIG. 3 in which the dies are shown with a needle 100 therebetween
in a position to be attached to a suture 200 (shown in phantom)
and the cross-sectional view of FIG. 4 which is taken along lines
4--4 of FIG. 3. In FIGS. 2-4 the dies 20 are shown separated from
each other in position prior to impact on a surgical needle 100
having an aperture 110 in which the end portion of suture 200 is
positioned (See FIG. 4).
Each die includes a die face 24 a pair of inner walls 26 perpendicular
to the die face 24 and an inner die surface portion 28. She dies
20 also have a front surface 20A and an angled rear surface 20B
(see FIGS. 2 and 4). The inner die surfaces 28 each include a substantially
planar crimping or swaging surface 30. Swaging surfaces 30 are each
angled relative to a plane defined by the die face 24. In particular,
as shown in FIG. 4 swaging surfaces 30 gradually taper radially
inwardly, relative to needle 100 disposed within the dies, going
from the front surface 20A of die 20 to the rear surface 20B of
the die 20.
The cross-sectional view of FIG. 4 illustrates the tapering feature
of swaging surfaces 30 in greater detail. As shown in the FIG.,
each swaging surface 30 of a single die 20 defines a plane which
is oriented at an angle relative to a plane defined by die face
24. As will become appreciated from the description provided hereinbelow,
such orientation of swaging surfaces 30 produces:opposed tapered
surfaces on the needle end. The angle defined by swaging surfaces
30 relative to their respective die faces 24 may range from about
6.degree. to about 15.degree.. In a preferred embodiment, this angle
is about 11.degree..
Referring again to FIGS. 2-4 inner die surface portion 28 also
includes an arcuate-shaped concavity or recess 32. Recesses 32 are
formed in swaging surfaces 30 and may extend from approximately
1/4 of the length of swaging surface 30 to approximately 3/4 the
length of the surface. Recesses 32 define material relief zones
to receive needle material displaced by the die 20 when a pair of
dies are caused to strike a needle positioned within the generally
5 rectangular-shaped cavity as described above. Recesses 32 are
preferably generally arcuate in shape and define a radius of curvature
which is generally constant throughout its length. The axis defined
by each arcuate recess 32 of die 20 is substantially parallel to
the plane defined by its respective die face 24. However, due to
the tapering configuration of swaging surface 30 relative to die
face 24 the depth of recess 32 gradually decreases towards the
front end portion 20A of the die as best shown in FIGS. 2 and 4.
Recesses 32 are each preferably disposed along the midline of swaging
surface 30.
FIGS. 5-6 illustrate the swaging effect dies 20 produce on the
drilled needle end. During the crimping process, the dies 20 are
moved towards each other until die faces 24 meet, whereby the swaging
surfaces 30 strike the drilled or blunt end portion of needle 100.
The needle material which is engaged by swaging surfaces 30 accumulates
by the swaging action into the relief zone provided by recess 32.
Simultaneously therewith, the apertured portion of the needle will
be ineffectively crimped and attached to the suture by the physical
reduction of the dimension of the aperture surrounding the suture.
Advantageously, the dies of the present invention require only
one strike or "hit" to effect attachment of the suture
components, thus, eliminating the double-hit method along with its
inherent disadvantages. Further, the dies are capable of consistently
producing detachable needle-suture combinations having pull-out
values within the ranges set forth in U.S. Pharmacopeia. A further
significant advantage of the present die resides in the fact that
its particular configuration reduces the criticality of manufacturing
the suture components to relatively strict tolerances even when
detachable needle-suture attachment is the objective. For example,
with conventional crimping procedures for producing detachable needle-suture
combinations the suture and needle components often need to be manufactured
to a .+-.0.0005 inch tolerance in order to achieve proper detachable
needle attachment. However, with the dies 20 of the present invention,
manufacturing tolerances need to be held only to .+-.0.0025 inch
to provide consistent acceptable detachable needle-suture combinations.
This is due to the nature of the crimp formed in the blunt end of
the needle. In particular, the depth of the crimp is sufficient
to cause the swaged portion of the needle to securely contact and
engage the suture even if precise manufacturing tolerances are not
met.
Similarly, with conventional crimping dies and processes, the "ovality"
of a suture may present additional difficulties regarding suture
attachment. Ovality is a term of art that refers to the degree in
which the cross-sectional dimension of the suture varies from an
exact circular configuration. In known crimping processes, the suture
must approach a near circular cross-section to achieve proper removable
needle suture attachment. This is disadvantageous in that the extra
manufacturing processes required to obtain a substantially circular
suture are costly and time consuming. With the dies of the present
invention, the ovality of the suture is not as critical as a parameter
in achieving acceptable suture attachment since the depth of the
crimp formed by the dies is sufficient to securely engage the suture
and compensates for any variation in the suture dimensions.
In the preferred crimping or swaging method, the needle 100 and
suture 200 is positioned within the dies in the manner shown in
FIG. 4 i.e., the blunt end surface 120 of needle 100 is aligned
with the front end 20A of the dies as shown with the suture 200
inserted within aperture 102 of the needle. Consequently, with this
particular positioning of the needle 100 within dies 20 the greatest
depth of the crimp caused by the swaging surfaces 30 is provided
away from the blunt needle end 120 towards the needle point 130.
Accordingly, the tapered surfaces formed on the needle taper inwardly
towards the needle point 130.
The particular dimensions of die 20 may be modified to accommodate
different sized surgical needles. Referring to FIG. 3 dimension
"W" of die 20 may be increased or decreased depending
on the diameter of the needle end to be received within the die.
Similarly, dimension "X" which indicates the depth of
the die may also be modified for a particular needle size. Further,
radius "Z" which indicates the dimension of the radius
of curvature of recess 32 may also be varied to accommodate alternative
dimensioned needle and suture components. Dimension Y which indicates
the maximum depth of recess 32 and which is a function of radius
"Z" may also be varied. The following chart indicates
proposed die parameters for various sized surgical needles.
The foregoing table illustrates the dimensional characteristics
required for detachably connecting a needle of a particular dimension
to a suture with the die of the present invention. I he table is
intended to be used only as a guide since the particular dimensions
of the die may vary depending on the type and size of the suture
being attached as well as the presence of lubricants, etc. One skilled
in the art may readily determine appropriate dimensions for the
die so as to achieve the objectives of the present invention. Further,
it is to be noted that the angular orientation of swaging surfaces
may be altered to achieve other desired results as well.
Preferably, the die of the present invention is configured in a
manner such that the needle is detachably attached to the suture
so as to be readily separated by a quick tug provided by,the surgeon.
However, it is entirely within the scope of the present invention
to modify the die such that the needle is attached with greater
pull-out so as to provide a "non-detachable" suture, in
which case the suture may be separated from the needle in a more
conventional manner, as by cutting with scissors or a scalpel.
Referring now to FIGS. 7 and 8 the drawings illustrate the configuration
of the needle after the crimping process. The dies form a generally
arrow-shaped impression on the needle surface. The swaging surfaces
of the die produce tapered surfaces 36 on the needle. The arcuate
raised portion 38 present on the needle end reflects the relief
zone 32 of the die where the material overflow is received during
swaging. As shown in the axial view of FIG. 8 needle-suture attachment
is achieved while maintaining the general symmetry of the needle
A with relatively insignificant surface distortion except for the
minor impression formed on the surface. Thus, the needle retains
its general circular symmetry in the area of suture attachment which
thereby minimizes tissue trauma during the suturing process.
Referring now to FIGS. 9 and 10 there is shown an exemplary apparatus
40 on which sutures may be attached to needles utilizing a pair
of dies of the present invention. The apparatus 40 shown in manufactured
and marketed as model A Suture Attaching Machine by B. G. Sulzle,
Inc., Syracuse, N.Y. Other comparable machines suitable for attaching
sutures may be utilized with the dies of the present invention.
The suture attaching machine 40 as illustrated in FIG. 9 includes
a table 42 having treadle 44 which is foot operated and connected
via treadle rod 46 to suture press 48. The treadle 44 iS mounted
for pivotal movement on pivot rod 50.
Referring now to FIG. 11 there is shown a side view of the apparatus
shown in FIG. 10. The suture press 48 is encircled and is shown
in enlarged form in FIG. 11. As can be seen in FIG. 1 the pair
of dies 20 which are constructed according to the invention are
positioned within the jaws of the suture press 48 and arranged to
be stricken against a needle 100 with the suture 200 in position
as shown in FIG. 12.
The needle 100 shown in FIG. 12 is of a curved type having a straight
rear end portion which defines an elongated aperture 110 dimensioned
for reception and attachment to an appropriately sized suture 200.
The needle 100 is supported on a guide support having a "V
shaped" guide channel which positively determines and positions
the needle location and orientation as shown. Thereafter, appropriate
adjustments are made to predetermine the strike force to be transmitted
to the needle and suture as may be appropriately calculated to obtain
a predetermined pull-out force. The treadle is depressed to cause
the dies to strike the needle.
An alternative apparatus for attaching surgical sutures to needles
is disclosed in commonly assigned U.S. Patent application Ser. No.
07/959114 filed Oct. 9 1992 the contents of which are incorporated
herein by reference. This apparatus includes a frame for positioning
and maintaining the needle while the suture is being attached and
a die system which selectively impacts the needle to secure the
needle thereto. The die system may be modified to incorporate the
novel dies of the present invention.
It will be readily appreciated that the dies of the present invention
are particularly advantageous in that many types of sutures may
be readily attached to needles having an aperture in their blunt
end, i.e., drilled end needles. Further, single strike force is
utilized thereby avoiding the need to provide "double-hit"
attachment as necessary with prior art dies. This procedure provides
a suture having a needle which is symmetrical and unaffected by
the distorting forces provided by dies and procedures of the prior
art. Moreover, the single-hit attachment procedure provides consistent
and controlled attachment of the suture and the needle which additionally
reduces the time and effort to complete the attachment. Die life
is increased, rejected needle/suture attachments are reduced, and
attachment time is reduced. As a result the cost of producing a
surgical suture is sizably reduced.
The swaging dies of the present invention may be utilized with
all types of needles such as curved needles, straight needles, or
the like, provided they have an elongated aperture on their ends
portion for receiving the suture. Sutures usable with the present
invention include silk, nylon, linen, cotton, polyester, polypropylene,
stainless steel, natural materials such as catgut, synthetic polymers
having glycolic acid ester linkages subject to hydrolytic degradation
to non-toxic tissue compatible absorbable components, including
polyglycolic acid. The sutures may be monofilamentary or braided,
absorbable or non-absorbable. The dies of the present invention
are preferably constructed of a hardened material such as tungsten
carbide. However, it should be understood that all materials suitable
for such die construction may be used, provided the geometric and
configurational parameters taught by the present invention are met.
While the above description contains many specifics, these specifics
should not be construed as limitations on the scope of the invention,
but merely as exemplifications of preferred embodiments thereof.
Those skilled in the art will envision many other possible variations
that are within the scope and spirit of the invention as defined
by the claims appended hereto. |