Author Topic: Constrictor vs. Strangle binding security in surgical ligatures  (Read 3875 times)

mcjtom

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A nice paper on a set of tests on the holding ability of a bunch of binding knots on surgical sutures.  The interesting part to me is the comparison of the Constrictor [#1249] with the Strangle [#1239].  The Constrictor wins (it basically holds better), which is common lore, but I haven't seen any testing done on it - on the suture, or on other cords. 

It seems to make sense to me considering that the riding turn in the Constrictor presses down on two strands on top of each other (higher friction between two ropes than a rope on the object, plus more transverse elasticity/rebound to keep the construct tight) whereas in the Strangle the riding turn presses two strands flat against the object, more or less.
« Last Edit: August 29, 2022, 10:06:20 AM by mcjtom »

Sweeney

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Re: Constrictor and Strangle biding in surgical ligature knots
« Reply #1 on: June 22, 2022, 12:11:15 PM »
It seems to make sense to me considering that the riding turn in the Constrictor presses down on two strands on top of each other (higher friction between two ropes than a rope on the object, plus more transverse elasticity/rebound to keep the construct tight) whereas in the Strangle the riding turn presses two strands flat against the object, more or less.

I agree - I do use a strangle knot occasionally but only because it has a slightly neater finish and holding ability is not paramount.

Sweeney

Dan_Lehman

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Re: Constrictor and Strangle biding in surgical ligature knots
« Reply #2 on: June 26, 2022, 07:46:26 PM »
And then there come the **multiples** of these two
binders, where I think one will find the constrictor
to be of diminishing appeal :: going "multiple" means
that the width/length --span along bound axis-- will
increase, and increasingly the C.'s had-been-perpendicular
(to axis) ends will be separated; whereas the S.'s will
remain parallel.

With the strangle, one can use several wraps for making
a whipping, and put in an extra crossing of the buried
ends :: I find that in mason line 4-5 wraps work well with
the extra crossing; with 30#? nylon monofilament fish line,
7-8 (and I usually will finish the knot with a bight from the
whipped-rope's end (i.e., bight'd whipping tail points INwards
along line) and put in a few wraps of sailmaker's whipping (is it?)
in that, then cutting both of the whipping tails short at the
end of the rope).

The strangle also can work nicely with a Gleipnir'd sort of turn
in the middle (i.e., one of its "multiple" wraps will wrap ONLY
the two ends of the knot, not the bound object) ; this serves
well when binding something that isn't nicely round/convex,
so the nipping of pure cord-on-cord is needed.

--dl*
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mcjtom

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Re: Constrictor and Strangle biding in surgical ligature knots
« Reply #3 on: June 26, 2022, 08:02:19 PM »
The strangle also can work nicely with a Gleipnir'd sort of turn
in the middle (i.e., one of its "multiple" wraps will wrap ONLY
the two ends of the knot, not the bound object) ; this serves
well when binding something that isn't nicely round/convex,
so the nipping of pure cord-on-cord is needed.
Any chance for a sketch or a picture?

Dan_Lehman

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Re: Constrictor and Strangle biding in surgical ligature knots
« Reply #4 on: June 27, 2022, 06:09:56 PM »
Dang, I'm pretty sure that I posted a photo of the binders
in pink mason line on 'T'-cross-section'd laundry soap cup
holders --my tying them to part of the washer needing a
secure attachment to the cup : noose-hitch around cup
and then at-cup & at-end strangles to secure line running
out the T-shaped handle.

Tie a dbl.strangle (at least double) around something;
then gently pull out the "something"/object so to be
able to collapse the center wrap to be no longer around
this object but just the 2 strangle ends,
carefully reinserting your something (in small cord,
a pointed pencil comes to mind).

It's not an easy knot to tie,
as you have this present then disappearing object
to surround, or to wrap it but then wrap only the
cord ends --one of which isn't there yet, as you're
still wrapping/tying the knot!

The point/need to the above was to get good nipping
(cord around cord, not around the smooth FLAT plastic
cup handle) and also the secure gripping on the handle.
Absent this "around cord only" wrap,
the strangle would be trying to find pressure against
its ends to hold tight --the flat smooth plastic not at
all helping.

--dl*
====

alana

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Re: Constrictor and Strangle biding in surgical ligature knots
« Reply #5 on: August 29, 2022, 09:54:41 AM »
A nice paper on a set of tests on the holding ability of a bunch of binding knots on surgical sutures.  The interesting part to me is the comparison of the Constrictor [#1249] with the Strangle [#1239].  The Constrictor wins (it basically holds better), which is common lore, but I haven't seen any testing done on it - on the suture, or on other cords. 

great,
this helped to know when i was tying a POM-POM !

mcjtom

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Re: Constrictor vs. Strangle binding security in surgical ligatures
« Reply #6 on: August 29, 2022, 10:34:53 AM »
BTW, there is also #1253 that Xarax fell in love with at one point (where is he anyway?). Not in the article, but I don't blame him - it's a v. neat construct with the mechanics similar to the Constrictor/Strangle, but with a wider footprint and possibly even more secure.  Not difficult to tie either, once you do it a few times.
« Last Edit: August 29, 2022, 11:25:01 AM by mcjtom »

alana

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Re: Constrictor vs. Strangle binding security in surgical ligatures
« Reply #7 on: March 15, 2024, 08:28:35 AM »
teeny tiny rope burns

if any suture-tyers reading here,
when pulling the thread through skin, it equates to rope burn

could affect healing of the cells surrounding the suture,
maybe not by much but i thought a thing to consider,
just needs to be slowed down a little.
as medical care continuously fine-tunes its bedside manner into the twentieth century

KC

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Re: Constrictor vs. Strangle binding security in surgical ligatures
« Reply #8 on: March 17, 2024, 09:03:37 AM »
Really dead locking Constrictor or Double for more permanent;
Much more occasional use i find Bag, even slipped quite adequate.
ABoK Lesson# 1244/pg.224:Slipped Bag
.
As turn the corner and use as Hitch, especially on a small host; the more reaching towards top for nip into play i think favoring Bag
>>where Constrictor tends to float a more side nip, harder to draw up tight
>>for Bag, the slip(s) then become spacers to/towards the key top nip position(from an input directly opposing nip of downward input for top nip)
.
Hitch usage is a linear input pull converted to radial to give this effect; forces reduce as trace arc(s) from loss of conversion form linear input to radial control.
Binding usage of a same lacing here is a radial input of even swell all around, so no top/bottom/sides ;force undifferentiated, trace arc(s) show equal forces until the nips.  Because no conversion, is radial input against swell to radial control.
.
Groundline is same lacing only finishing as 'outie' vs. Bag's 'innie'.
i like the Bag innie as more, at least visually, balanced form, more self centering cleanly like Constrictor.
But, will favor Groundline for making tail/Bitter End hang more cleanly in 90degree situation.
.
Bag and Constrictor to me make Crossed Turn of Clove w/o final tuck, Bag tucks under the input leg, to take top nip on small host in Hitch, Constrictor does the double bury by contrast.  #12530goes beyond Crossed Turn fully to Clove, then does the Double lock of Constrictor, but could choose Bag's single final lock instead.
.

 
"Nature, to be commanded, must be obeyed" -Sir Francis Bacon[/color]
East meets West: again and again, cos:sine is the value pair of yin/yang dimensions
>>of benchmark aspect and it's non(e), defining total sum of the whole.
We now return you to the safety of normal thinking peoples

alana

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Re: Constrictor vs. Strangle binding security in surgical ligatures
« Reply #9 on: March 20, 2024, 02:28:39 AM »
later this week i get a couple of stitches removed after small excision on my face.

they get cut with a stitch remover, a curved 1cm blade;
this is stupid because it involves some tugging at the stitch for it to cut.
i will probably use scissors to cut them, myself.

also, my dr is usually pretty good, but this time one of the stitches had both ends pointing and digging into the excision line,
which i didn't check for 3 days, as i thought i was being well behaved not touching any of it.
well i had to pick the ends out carefully with a pin,
and trim,
so it is a little inflamed.
and another stitch, the overhand had loosened. i tightened that up  ::)
that was the only stitch that was pointing the right way, perpendicular to the cut line.

and there's the wondrous hardware that is dissolving stitches,
a couple of those,
maybe they're doing all the work,
on top though, it's a relative mess

still, one of the least of my concerns,
just would've been nice if it was straightforward and with knots ship shape

 

anything