Author Topic: Challenging medical knot tying scenario  (Read 17087 times)

xarax

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Re: Challenging medical knot tying scenario
« Reply #15 on: October 22, 2011, 11:53:29 PM »
I'm working with rolling the double overhand knot. 

   Perhaps one could use a double overhand knot instead of a half hitch.
The adjustable noose / loop based on the double overhand knot, was shown elsewhere (1).  Notice the particular way the second eye leg passes through the knot s nub.
   ( I have not tested this eye knot in the case of very slippery and  elastic materials. )
 
1.   http://igkt.net/sm/index.php?topic=3315   
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Dan_Lehman

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Re: Challenging medical knot tying scenario
« Reply #16 on: October 23, 2011, 06:35:09 AM »
I've noticed several suggestions involving the tying of different (better?) knots than the Dines Slider.  It was my impression from the original post that that the solution was limited to those with a starting point of a "preconfigured" Dines Slider (you also mention later that the Dines Knot is provided beforehand to others with possibly little knot-tying expertise).  If this is the case, some clarification (pictures are always a plus) would be helpful on what the structure of a preconfigured Dines Slider might be.

Ah, touche' --pull the reins on our flights of fancy!

Well, then my analysis of the problem with that knot
suggest a limited chance of success, at best (i.e., not
a sure, immediate lock).

I like Roo's simplicity to the general idea I tried to
implement --of putting a u-turn into the part that
had formerly been sliding, to lock.  If forceps or some
device holds the knot up snug for the tightening,
it seems that Roo's re-reeved buntline hitch can be
locked; but another thing to consider, though, is at
what angle of incidence/departure the binding parts
have to the knot.  Possibly, something a little more
involved (another turn or two) than the clove structure
will be needed.

(nb:  the fine material isn't monofilament --more flexible.)

--dl*
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xarax

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Re: Challenging medical knot tying scenario
« Reply #17 on: October 23, 2011, 12:29:37 PM »
My first general plan was to suggest employing a 2nd line...

    That is a very good plan ! The simplest way I can think of, that implements this "second line"  idea, is shown in the attached picture. I guess that one might figure out many other knots, that can slide towards the object, and then locked there by pulling the second line.
« Last Edit: October 23, 2011, 12:45:52 PM by xarax »
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Dan_Lehman

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Re: Challenging medical knot tying scenario
« Reply #18 on: October 24, 2011, 05:31:56 AM »
My first general plan was to suggest employing a 2nd line...

    That is a very good plan ! The simplest way I can think of, that implements this "second line"  idea, is shown in the attached picture. I guess that one might figure out many other knots, that can slide towards the object, and then locked there by pulling the second line.

Xarax, you quite miss the points : (1) what you show
is the OP's technique, roughly, but with another knot;
(2) it is of one "line", which has, yes, two ends.

My "2nd line" means using an UNknotted line in the bight,
binding role, with a 2nd line sliding down some line-binder
as a choking mechanism --for temporary locking--, which
then must be tied off using 1st & 2nd line's ends.


--dl*
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xarax

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Re: Challenging medical knot tying scenario
« Reply #19 on: October 24, 2011, 12:33:10 PM »
(1) what you show is the OP's technique, roughly, but with another knot;

   I think that, at the end, it is with the same  knot, is nt it that so ? Is this the technique the same one used by the surgeons ? If yes, then I we can say we know now, how on earth Dines thought of this seemingly complicated knot : It is not complicated at all ! In fact, it is the simplest knot that uses the "second line" idea, to carry a "lock" on the already tightened hitch on the surface of the object.

(2) it is of one "line", which has, yes, two ends
   I interpreted the "second line" idea as a "second bight "idea  :), a bight with a tip going through  the whatever hitch that has been already pushed and tightened on the surface of the object. This loop serves as a vehicle to carry the "lock" to the hitch - you pull the one end, and the other, with the "lock" attached on it, slides towards the hitch. When it reaches the hitch, the two knots bind together, and you have a secure binder. We can think of a number of sliding "locks", but a simple half turn will suffice, I believe. Now, from this idea it is only a small step to figure out how to connect the two bights together, so, at the end, when the "loch" reaches the hitch, you are left with two only ends...
   Why you always believe that I have missed tha point, when I have not, and I always believe you have understood what I mean...when you had not ?  :)
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Nickels

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Re: Challenging medical knot tying scenario
« Reply #20 on: October 26, 2011, 04:35:00 PM »
Before I provide an update, please accept my most sincere "Thanks!" for all that have contributed to this thread.  It has really opened my eyes to some of the alternate ways of solving this problem.

I'm working through testing the options presented in this thread (including prototyping some tooling).  So far, the data I'm collected suggests that the buntline hitch on its own won't do the trick; however, I'm looking at using the ideology for other knots.  DDK mentioned that the post goes around the object and then pre-tied loops come over it at the end - that's exactly how this system works.

As I collect the data, I'll post back on the performance of each.

Again, many thanks to all for your input.


Dan_Lehman

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Re: Challenging medical knot tying scenario
« Reply #21 on: October 27, 2011, 05:00:28 AM »
... the alternate {alternatIVe} ways of solving this problem.

Note that we have two "problems" : the one you defined
really --as pointed out by DDK-- was to secure the extant,
"preconfigured" Dines knot;
but some us *backed-up* to the problem that the Dines knot
was trying to solve, and offered alternatives to that.  (Imagine
an instruction : "First, UNtie the preconfigured knot; THEN ..." ! )  ;D

Quote
So far, the data I'm collected suggests that the buntline hitch on its own won't do the trick;

But please note that what Roo presented was NOT exactly
the buntline hitch,  but was that structure modified by taking
the noose's standing part through the knot a 2nd time.
Are you saying that this revised structure doesn't work?

Quote
DDK mentioned that the post goes around the object and then pre-tied loops come over it at the end - that's exactly how this system works.

Okay, I wanted a more detailed explanation of the knotting
situation.  The provided diagram above shows a relatively
large (green-shaded) "object" for the line, suggesting that
the buntline hitch indeed will have some challenges, with
the ultimately loaded lines pulling it apart --and that perhaps
the two half-hitches orientation of the clove hitch would
better serve, here (with Roo's modification).

And to the question of exactly how this knotting/binding
is effected, let me point out that in some case what we
are facing is some fixed amount of slippage/yield from
the knot, which serves to lengthen-loosen the binding loop;
but were one to make a double loop, the fixed yield
would be divided in half in its loosening effect (half to each
of the two loops.  So, without adjusting any of the knots
--assuming that they do lock and hold, but just yield some
tightness in doing so--, one can halve the effect on the binding.
(in theory)

--dl*
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roo

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Re: Challenging medical knot tying scenario
« Reply #22 on: October 28, 2011, 02:07:34 AM »
  So far, the data I'm collected suggests that the buntline hitch on its own won't do the trick; however, I'm looking at using the ideology
I made a comment earlier about friction hitches being used in place of the buntline's clove structure, but really, you don't have to limit yourself.  Perhaps some common angling nooses like the Uni-Knot might serve as a basis to apply the aforementioned lock in place of the buntline hitch example.

The greater number of coils may make up for the slippery line you apparently have. 
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