Surgical needle abstract
A combined surgical needle-suture device is provided by attaching
the reduced shank of a needle and the tip region of a suture to
each other through a heat shrinkable tubing fitted around both,
the axial length of the tubing bearing a defined relationship to
the effective axial length of the needle shank. In the preferred
detachable needle-suture device, a removal interface having a predetermined
axial length and/or contact area is defined between a shrinkable
tubing having a predetermined axial length and a suture tip region.
Surgical needle claims
What is claimed is:
1. A combined surgical needle-suture device which comprises:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and,
(c) a shrinkable tubing around said needle shank and a portion
of said suture, the ratio of the axial length of the tubing to the
effective axial length of the needle shank being at least about
4:1 when the needle is intended to be non-detachable from the suture
and no more than about 3.5:1 when the needle is intended to be detachable
from the suture.
2. The combined surgical needle-suture device of claim 1 wherein
the device is of the non-detachable type and said ratio is at least
about 4.5:1.
3. The combined surgical needle-suture device of claim 1 wherein
the device is of the non-detachable type and said ratio does not
exceed about 12:1.
4. The combined surgical needle-suture device of claim 1 wherein
the device is of the non-detachable type and said ratio does not
exceed about 9.5:1.
5. The combined surgical needle-suture device of claim 1 wherein
the device is of the detachable type and said ratio does not exceed
about 3.2:1.
6. The combined surgical needle-suture device of claim 1 wherein
the device is of the detachable type and said ratio is not less
than about 1.2:1.
7. The combined surgical needle-suture device of claim 1 wherein
the device is of the detachable type and said ratio is not less
than about 1.4:1.
8. The combined surgical needle-suture device of claim 1 wherein
the device is of the detachable type and said ratio is in the range
of about 1.6 to 2.3.
9. The combined surgical needle-suture device of claim 1 wherein
the device is of the detachable type and said shrinkable tubing
has an axial length of about 0.125 inch.
10. The combined surgical needle-suture device of claim 1 wherein
the device is of the detachable type and said shrinkable tubing
has an axial length of about 0.115 inch.
11. The combined surgical needle-suture device of claim 1 wherein
the ratio of the axial length of the tubing to the effective axial
length of the suture tip is in the range of from about 1.8 to about
2.6.
12. The combined surgical needle-suture device of claim 1 wherein
the axial length of the tubing is in the range of from about 0.115
to about 0.160 inches.
13. A plurality of combined surgical needle-suture devices, each
such device comprising:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and,
(c) a shrinkable tubing around said needle shank and a portion
of said suture, a surface contact area defined between said shrinkable
tubing and at least one of said needle shank and/or suture to provide
a detachable needle-suture device, said surface contact area having
an effective axial length in the range of from about 0.045 to about
0.105 inch; and,
each said needle-suture combination meeting the pull-out force
limits for removable needle attachment set forth in the United States
Pharmacopeia and said plurality of needle-suture combinations exhibiting
a standard deviation in average pull-out force of less than or equal
to about 0.15.
14. A combined surgical needle-suture device which comprises:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and
(c) a shrinkable tubing around said needle shank and a portion
of said suture, a surface contact area defined between said shrinkable
tubing and at least one of said needle shank and/or suture to provide
a detachable needle-suture device, said surface contact area having
an effective axial length in the range of from about 0.045 to about
0.105 inch,
wherein the ratio of the axial length of the tubing to the effective
axial length of the needle shank does not exceed about 3.5:1.
15. The combined surgical needle-suture device of claim 14 wherein
said ratio is in the range of from about 1.6 to about 2.3.
16. A combined surgical needle-suture device which comprises:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and,
(c) a shrinkable tubing having an axial length in the range of
from about 0.115 to about 0.160 inches, the shrinkable tubing disposed
around the needle shank and a portion of said suture to join the
suture and needle defining a pull-out force for a detachable needle-suture
combination.
17. A method for attaching a surgical needle to a suture comprising:
(a) providing a needle having a shank of reduced cross-section;
(b) placing a shrinkable tubing around the reduced diameter shank
and the suture, the axial length of the tubing to the effective
axial length of the needle shank being at least about 4:1 when the
needle is intended to be non-detachable from the suture and no more
than about 3.5:1 when the needle is intended to be detachable from
the suture; and,
(c) applying energy to the shrinkable tubing to bring the tubing
into engagement with the needle shank and suture.
18. The method of claim 17 wherein the device is of the non-detachable
type and said ratio is at least 4.5:1.
19. The method of claim 17 wherein the device is of the non-detachable
type and said ratio does not exceed about 12:1.
20. The method of claim 17 wherein the device is of the non-detachable
type and said ratio does not exceed about 9.5:1.
21. The method of claim 17 wherein the device is of the detachable
type and said ratio does not exceed about 3.2:1.
22. The method of claim 17 wherein the device is of the detachable
type and said ratio is not less than about 1.2:1.
23. The method of claim 17 wherein the device is of the detachable
type and said ratio is not less than about 1.4:1.
24. The method of claim 17 wherein the device is of the detachable
type and said ratio is in the range of from about 1.6 to about 2.3.
25. The method of claim 17 wherein the device is of the detachable
type and said tubing has an axial length in the range of from about
0.115 to about 0.160 inches.
26. A method for attaching a plurality of surgical needles to sutures
to provide a plurality of detachable needle-suture devices comprising:
(a) providing a plurality of needles having a shank of reduced
cross-section;
(b) placing a shrinkable tubing around each reduced needle shank
and a suture;
(c) applying energy to the shrinkable tubing to bring the tubing
into engagement with the needle shank and suture so as to define
a surface contact area between each shrinkable tubing and the needle
shank, the suture or the needle shank and the suture, the surface
contact area having an effective axial length in the range of from
about 0.045 to about 0.105 inches, and,
(d) controlling said energy application to provide a plurality
of devices meeting the pull-out force limits for removable needle
attachment set forth in the United states Pharmacopeia and exhibiting
a standard deviation in average pull-out force of less than or equal
to about 0.15.
27. The method of claim 26 wherein said applied energy is heat
and said tubing remains shrunken after cooling, whereby said needle
shank and suture remain coupled after cooling.
28. A method for attaching a plurality of surgical needles to sutures
to provide a plurality of detachable needle-suture devices comprising:
(a) providing a plurality of needles having a shank of reduced
cross-section;
(b) placing a shrinkable tubing having an axial length in the range
of from about 0.115 to about 0.160 inches around each reduced needle
shank and a suture;
(c) applying energy to the shrinkable tubing to bring the tubing
into engagement with each needle shank and suture to join the needle
and suture; and,
(d) controlling said energy application to provide a plurality
of needle-suture devices meeting the pull-out force limits for removable
needle attachment set forth in the United States Pharmacopeia and
exhibiting a standard deviation in average pull-out force of less
than or equal to about 0.15.
29. The method of claim 28 wherein said applied energy is heat
and said tubing remains shrunken after cooling, whereby said needle
shank and suture remain coupled after cooling.
30. A combined surgical needle-suture device which comprises:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and
(c) a shrinkable tubing around said needle shank and a portion
of said suture, a surface contact area defined between said shrinkable
tubing and at least one of said needle shank and/or suture to provide
a detachable needle-suture device, said surface contact area having
a contact area in the range of about 0.001 to about 0.008 square
inches.
31. The combined surgical needle-suture device of claim 30 wherein
said contact area is in the range of from about 0.001 to about 0.006
square inches.
32. The combined surgical needle-suture device of claim 30 wherein
the ratio of the axial length of the tubing to the effective axial
length of the needle shank does not exceed about 3.5:1.
33. The combined surgical needle-suture device of claim 32 wherein
said ratio is in the range of from about 1.6 to about 2.3.
34. The combined surgical needle-suture device of claim 30 wherein
the ratio of the axial length of the tubing to the effective axial
length of the suture tip is in the range of from about 1.8 to about
2.6.
35. The combined surgical needle-suture device of claim 30 wherein
the axial length of the tubing is in the range of from about 0.115
to 0.160 inches.
36. The combined surgical needle-suture device of claim 30 wherein
the axial length of the surface contact area is in the range of
from about 0.04 to about 0.105 inches.
37. A combined surgical needle-suture device which comprises:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and,
(c) a shrinkable tubing around said needle shank and a portion
of said suture, a surface contact area defined between said shrinkable
tubing and said suture to provide a detachable needle-suture device,
said surface contact area related to suture size substantially as
follows:
38. The combined surgical needle-suture device of claim 37 wherein
the axial contact length of said tube and suture is in the range
of from about 0.045 inches to about 0.105 inches.
39. The combined surgical needle-suture device of claim 37 wherein
the tip of said suture has a diameter related to suture size substantially
as follows:
40. The combined surgical needle-suture device of claim 37 wherein
the surface contact area is related to suture size substantially
as follows:
41. The combined surgical needle-suture device of claim 40 wherein
the axial contact length of said tube and suture is in the range
of from about 0.060 to about 0.090 inches.
42. The combined surgical needle-suture device of claim 40 wherein
the tip of said suture has a diameter related to suture size substantially
as follows:
43. The combined surgical needle-suture device of claim 40 where
the ratio of the axial length of the tubing to the effective axial
length of the needle shank is not less than about 1.2:1.
44. The combined surgical needle-suture device of claim 40 wherein
said suture is a braided suture.
45. The combined surgical needle-suture device of claim 44 wherein
said suture is tipped with cyanoacrylate.
46. The combined surgical needle-suture device of claim 37 wherein
said suture is a monofilament suture.
47. The combined surgical needle-suture device of claim 37 wherein
said suture is a braided suture.
48. A shrinkable tubing configured and dimensioned to engage a
portion of a surgical suture and a needle to attach same in a substantially
axial end-to-end relationship, the shrinkable tubing having a minimum
expanded inner diameter and a maximum recovered inner diameter related
to suture size substantially as follows:
49. A combined surgical needle-suture device which comprises:
(a) a needle having a shank of reduced cross-section;
(b) a suture; and,
(c) a shrinkable tubing configured and dimensioned to surround
at least a portion of said needle shank and suture to attach same
and provide a detachable needle-suture device, said needle shank,
suture and tubing dimensions related to each other substantially
as follows:
50. The needle-suture combination of claim 49 wherein said tubing
has a maximum recovered wall thickness substantially as follows:
51. A plurality of detachable needle-suture combinations each comprising
a size 0 braided synthetic absorbable suture joined to a needle,
the plurality of needle-suture combinations meeting the pull-out
force limits for removable needle attachment set forth in the United
States Pharmacopeia and exhibiting a standard deviation in average
pull-out force of less than or equal to about 0.15
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
52. A plurality of detachable needle-suture combinations, each
comprising a size 4/0 braided synthetic absorbable suture joined
to a needle, the plurality of needle-suture combinations meeting
the pull-out force limits for removable needle attachment set forth
in the United States Pharmacopeia and exhibiting a standard deviation
in average pull-out force of less than or equal to about 0.05
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
53. A plurality of detachable needle-suture combinations, each
comprising a size 0 monofilament polypropylene suture joined to
a needle, the plurality of needle-suture combinations meeting the
pull-out force limits for removable needle attachment set forth
in the United States Pharmacopeia and exhibiting a standard deviation
in average pull-out force of less than or equal to about 0.05
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
54. A plurality of detachable needle-suture combinations, each
comprising a size 2/0 monofilament polypropylene suture joined to
a needle, the plurality of needle-suture combinations meeting the
pull-out force limits for removable needle attachment set forth
in the United States Pharmacopeia and exhibiting a standard deviation
in average pull-out force of less than or equal to about 0.03
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
55. A plurality of detachable needle-suture combinations, each
comprising a size 2/0 braided nylon suture joined to a needle, the
plurality of needle-suture combinations meeting the pull-out force
limits for removable needle attachment set forth in the United States
Pharmacopeia and exhibiting a standard deviation in average pull-out
force of less than or equal to about 0.04
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
56. A plurality of detachable needle-suture combinations, each
comprising a size 3/0 braided nylon suture joined to a needle, the
plurality of needle-suture combinations meeting the pull-out force
limits for removable needle attachment set forth in the United States
Pharmacopeia and exhibiting a standard deviation in average pull-out
force of less than or equal to about 0.30
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
57. A plurality of detachable needle-suture combinations, each
comprising a size 0 braided nylon suture joined to a needle, the
plurality of needle-suture combinations meeting the pull-out force
limits for removable needle attachment set forth in the United States
Pharmacopeia and exhibiting a standard deviation in average pull-out
force of less than or equal to about 0.11
wherein the suture is joined to a needle having a reduced diameter
shank by a heat shrinkable tubing surrounding at least a portion
of the needle shank and a portion of the suture.
Surgical needle description
BACKGROUND OF THE INVENTION
The present invention relates to a combined surgical needle-suture
device and, more particularly, to such a device in which a shrinkable
tubing attaches a suture to a surgical needle.
For many years, surgeons have employed needle-suture combinations
in which the tip of the suture or ligature is attached to the blunt,
or shank, end of the needle. Such needle-suture combinations are
provided for a wide variety of monofilament and braided suture materials,
e.g., nonabsorbable materials such as surgical gut, silk, nylon,
polyester, polypropylene, linen and cotton, and absorbable materials
such as the synthetic polymers and copolymers of glycolic and lactic
acids.
Needle-suture combinations fall into two general classes: standard
needle-suture devices and standard detachable needle-suture devices.
In the case of standard needle-suture devices, the suture is securely
attached to the needle and is not intended to be separable therefrom
except by a deliberate cutting or severing of the suture. By contrast,
in standard detachable needle-suture devices, separation of the
needle from the suture is achieved by application of a separation,
or pull-out, force applied by the surgeon. Minimum acceptable pull-out
forces required to separate a needle from a suture (for various
suture sizes) are set forth in the United States Pharmacopeia (USP).
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
USP are hereby incorporated by reference and are as follows.
______________________________________ Standard Needle Attachment
for Absorbable And Nonabsorbable Sutures Metric Size Limits on Needle
(Gauge No.) Attachment Nonabsorbable Indi- Absorbable and Synthetic
Average vidual (Collagen) Absorbable UPS (kgf) (kgf) Suture Suture
Size (Min.) (Min.) ______________________________________ 0.1 11-0
0.007 0.005 0.2 10-0 0.014 0.010 0.4 0.3 9-0 0.021 0.015 0.5 0.4
8-0 0.050 0.025 0.7 0.5 7-0 0.080 0.040 1 0.7 6-0 0.17 0.08 1.5
1 5-0 0.23 0.11 2 1.5 4-0 0.45 0.23 3 2 3-0 0.68 0.34 3.5 3 2-0
1.10 0.45 4 3.5 0 1.50 0.45 5 4 1 1.80 0.60 6 & larger 5 &
larger 2 & larger 1.80 0.70 ______________________________________
The requirements are met if neither the average of 5 values nor
any individual value is less than the limit given in the foregoing
table.
______________________________________ Removable Needle Attachment
for Absorbable and Nonabsorbable Sutures Metric Size (Gauge No.)
Nonabsorbable Attachment Limits Absorbable and Synthetic USP Minimum
Maximum (Collagen) Absorbable Size (kgf) (kgf) ______________________________________
1.5 1 5-0 2 1.5 4-0 3 2 3-0 3.5 3 2-0 0.028 1.59 4 3.5 0 5 4 1 6
5 2 ______________________________________
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 valve 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 pre-tensioning
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 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.
U.S. Pat. No. 3918455 describes a needle-suture attachment wherein
a hollow suture portion is secured to the shank end of a needle
which is of reduced cross-section as compared to the remainder of
the needle.
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),
3835912 (laser welding of metal tube to needle), 2814296 2802468
(chamfered tubing ends), 2302986 2240330 1981651 (needle
and tubing screw threaded), 1960117 and 1591021.
Numerous disadvantages exist with methods used heretofore to effect
needle-suture attachment. For example, those methods which involve
the formation and use of an axial bore in the shank end of the needle
require the use of expensive hole forming equipment. Moreover, it
is difficult to maintain the bore concentric with the center-line
of the needle and to control the depth (and diameter) of the bore
when drilling the needle shank, whether using conventional drilling
equipment or laser drilling. Another disadvantage is the possibility
that foreign substances may inadvertently or uncontrollably be introduced
into the needle bore, e.g., oil used during drilling or silicone
from the needle silconization process. Safeguards employed in an
attempt to prevent the introduction of such foreign materials, e.g.,
water blocking during needle silconization, are inconvenient, adding
time, effort and cost to the needle production process.
Attachment processes which employ bored needle shanks also limit
the range of materials from which needles may be fabricated in a
cost effective fashion. For example, it is exceedingly difficult
to drill Series 300 stainless steel (laser drilling is required)
and, once drilled, it is difficult to swage Series 300 stainless
steel in a consistent and reliable manner. For this reason, Series
300 stainless steel is not employed for the vast majority of needled
suture products despite its advantageous combination of strength
and ductility characteristics as compared to conventionally employed
Series 400 stainless steel.
Additional disadvantages associated with needle-suture attachment
methods which employ bored needle shanks include the weakness imparted
to the bored section of the needle, particularly after swaging,
and the attendant increased possibility that the needle will fracture
in this region. It is also difficult to provide a specialized surface
finish to the needle shank to assist in needle attachment, e.g.,
a texturized surface and/or a tapered bore. Swaging equipment used
in such needle-suture attachment methods is also maintenance intensive.
Needle-suture attachment methods which have employed tubings heretofore
also exhibit numerous disadvantages. Methods which employ metal
tubings greatly diminish the flexibility of the needle-suture combination
in the attachment region. Such diminished flexibility has a deleterious
effect in many surgical procedures. Swaging of the tubing to the
needle and the suture is also undesirable in that swaging is time-consuming,
maintenance intensive, and subject to variability in attachment
force.
Moreover, needle-suture attachment methods which have employed
tubings heretofore have necessarily required the use of tubing having
an inner diameter essentially equal to the outer diameters of the
needle shank and suture tip to be attached. Too large a difference
between the aforesaid inner and outer diameters inhibits the attachment
process, and prevents a tight, secure interface between needle (and/or
suture) and tubing. The limited tolerance between the tubing inner
diameter and the needle shank/suture outer diameters in such methods
make these dimensions critical, thereby making the attachment process
more difficult and time-consuming, and increasing the likelihood
of attachment failure and/or rejected materials.
With regard to conventional detachable needles, a further disadvantage
is that such needles heretofore have been attached by swaging or
crimping. It is difficult to sufficiently control the swaging process
in day to day manufacture so as to consistently obtain suture-needle
devices which consistently detach under the same force with minimal
variation in detachment force. Indeed, conventional swaged detachable
needles have been observed to fail prematurely under minimal force,
e.g. in removing the suture from the package, or to fail to yield
under considerable force. Such events can result in unnecessary
waste, lost time and, at worst, unavailability of a suture-needle
to the surgeon when needed.
Commonly assigned, copending U.S. patent application Ser. No. 413240
filed Sep. 27 1989 describes a combined surgical needle-suture
device and surgical needle-suture attachment method which overcomes
the aforementioned drawbacks of the previously known needle-suture
combinations and needle-suture attachment methods. In accordance
with said application, a combined needle-suture device is provided
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.
SUMMARY OF THE INVENTION
It has now been found that relationships exist among the area,
length and diameter of the tubing and the area, length and diameter
of the shank of the needle and suture required to predictably and
reliably achieve standard (i.e., ordinarily non-detachable) or selectively
reversible (i.e., detachable) attachment of the needle and suture
in the combined surgical needle-suture devices of aforementioned
U.S. patent application Ser. No. 413240.
In accordance With the present invention, there is provided a combined
surgical needle-suture device which comprises:
a) a needle having a shank of reduced cross-section;
b) a suture; and,
c) a shrinkable tubing around said needle shank and a portion of
said suture, the ratio of the axial length of the tubing to the
effective axial length of the needle shank being at least about
4:1 when the needle is intended to be non-detachable from the suture
and no more than about 3.5:1 when the needle is intended to be detachable
from the suture.
Further in accordance with this invention, there is provided a
method for attaching a surgical needle to a suture to provide a
combined surgical needle-suture device which comprises:
a) providing a needle having a shank end of reduced cross-section;
b) placing a shrinkable tubing around the reduced diameter shank
and the suture, the ratio of the axial length of the tubing to the
effective axial length of the needle shank being at least about
4:1 when the needle is intended to be non-detachable from the suture
and no more than about 3.5:1 when the needle is intended to be detachable
from the suture; and,
c) applying energy to the shrinkable tubing to bring the tubing
into engagement with the needle shank and suture.
It will be noted that for an entire line of surgical needles differing
in length, diameter and configuration, attachment of the needles
to their sutures in accordance with this invention can be accomplished
with as few as two different axial lengths of tubing, the tubing
of greater axial length being used for suture-needle devices of
the non-detachable variety and the tubing of shorter axial length
being used for suture-needle devices of the detachable variety.
The use of such tubings makes it possible to minimize the number
of different tubings which must be manufactured and inventoried
to accommodate the needle-to-suture attachment needs of a comprehensive
line of combined surgical needle-suture devices.
In a particularly preferred embodiment of the invention, it has
been found that a detachable suture-needle combination can be provided
which exhibits more consistent detachment (pull-out) force than
known types of detachable needle-suture combinations of comparable
size. More specifically, it has been found that a removal interface
characterized by optimized suture tip surface characteristics in
combination with optimized shrinkable tubing suture contact area
results in a detachable suture-needle combination with a more consistent
detachment force than the known types of standard detachable suture-needle
combinations.
As used herein, the expression "standard needle-suture"
refers to permanently attached needle-suture combinations in which
the force required to separate the needle from the suture is within
the range of pull-out force set forth in the United States Pharmacopeia
for permanently attached needle-suture combinations.
As used herein, the expression "standard detachable needle-suture"
refers to a detachable needle-suture combination in which the force
to separate the needle from the suture is within the range of pull-out
forces set forth in the United States Pharmacopeia for removable
needle-suture combinations, and includes detachable or removable
needle-suture combinations commercially available from Ethicon,
Inc. (Johnson & Johnson) and Davis & Geck (American Cyanamid
Co.)
|