Author Topic: Challenging medical knot tying scenario  (Read 17081 times)

Nickels

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Challenging medical knot tying scenario
« on: October 18, 2011, 11:33:12 PM »
Hello,

I'm new to the community and to knot tying, so please bear with my explanation of the situation!  Thanks to the administrators for hosting this very informative forum.

The situation I'm facing is one where a suture has been tied around a wound and secured with a Dines knot.  The wound is deep in the body, and requires tools to access the site (typically you work through a tube).  The dines knot come pre-configured and is used to slide down and approximate the wound.  Unfortunately, even when locked, the Dines knot tends to slide back when the loop is under tension; however, it is useful to close the wound temporarily, prior to backing it up with (perhaps) some additional knots.

I am looking to secure the dines knot with some other knots.  I've tried multiple overhand knots (reverse half-hitches with alternating posts), but that is "finnicky" and not easy to ensure it has been done properly when working in the tube and pushing it down with a tool.  I was hoping that perhaps I could put a stopper knot on the end of each of the post and locker, and somehow slide these stopper knots down to the treatment site.  Is there such a knot?  Are there any other options that I should consider?

Thanks to everyone in advance for your time and consideration with this problem.
« Last Edit: October 21, 2011, 01:06:50 AM by SS369 »

SS369

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Re: Challending medical knot tying scenario
« Reply #1 on: October 19, 2011, 01:06:07 AM »

roo

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Re: Challending medical knot tying scenario
« Reply #2 on: October 19, 2011, 03:46:57 AM »
Hello,

I'm new to the community and to knot tying, so please bear with my explanation of the situation!  Thanks to the administrators for hosting this very informative forum.

The situation I'm facing is one where a suture has been tied around a wound and secured with a Dines knot.  The wound is deep in the body, and requires tools to access the site (typically you work through a tube).  The dines knot come pre-configured and is used to slide down and approximate the wound.  Unfortunately, even when locked, the Dines knot tends to slide back when the loop is under tension; however, it is useful to close the wound temporarily, prior to backing it up with (perhaps) some additional knots.

I am looking to secure the dines knot with some other knots.  I've tried multiple overhand knots (reverse half-hitches with alternating posts), but that is "finnicky" and not easy to ensure it has been done properly when working in the tube and pushing it down with a tool.  I was hoping that perhaps I could put a stopper knot on the end of each of the post and locker, and somehow slide these stopper knots down to the treatment site.  Is there such a knot?  Are there any other options that I should consider?

Thanks to everyone in advance for your time and consideration with this problem.

Looking up this Dines Slider Knot, I noticed it is a loop based on this knot form (sometimes called a Japanese Knot):



I'm a little surprised that such a high-complexity knot is used.  It seem to do OK in monofilament once locked, only slipping at higher loads.  Perhaps your material is more difficult to deal with, and it makes me wonder if add-ons like half hitches and stopper knots wouldn't just spring out.  A simple overhand stopper can be "slid" to the knot as an add-on by inserting a needle in the center of the knot to force it to roll where the needle pulls it.

The Dines Slider Knot has a slide-locking-when-the-free-end-is-pulled mechanism that is similar to a Sailor's Hitch that is tied around its own standing part to form a loop.  I don't think it will surpass the performance of the knot you are using, but it would be less complex:

http://notableknotindex.webs.com/sailorhitches.html
(see first footnote)

Does the knot need to slide and then lock?
« Last Edit: October 20, 2011, 12:22:09 AM by roo »
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Nickels

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Re: Challending medical knot tying scenario
« Reply #3 on: October 19, 2011, 05:12:31 PM »
Thansk roo and SS369 for your quick feedback!

SS369: The issue with standard arthroscopic techniques is generally that they require quite a bit of training - the doctors performing the procedure I'm working on won't have that type of training (they know overhand knots/square knots but that's about it).  I'm stuck in that sense - can't use very complicated knots yet somehow need good security.  That being said, the Google book link you provided is interesting and I'll dig into that a litter bit more.  The Dines knot is something that we can provide beforehand, and it seems to be the best in terms of temporarily securing the loop.

roo: I'm really interested in the idea of a double overhand knot; however, whenever I tighten the knot it tightens "towards" me, and away from the dines knot.  This gap between the two knots ends up as a loss in tension in the loop.  Is there a way to tighten an overhand stopper fully whilst only pushing from one side?  To answer your other question, the backup knot doesn't necessarily need to "slide" and "lock" as used in knot terminology, but does need to be made outside the tube and then pushed down using an instrument.

Thank you both for your help!

roo

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Re: Challending medical knot tying scenario
« Reply #4 on: October 20, 2011, 04:35:27 PM »
Thank you both for your help!

I've been playing with various knots that are supposed to shrink and lock, but the devil is in the details.  Once you get the loop shrunk down and binding something, the tension caused by this binding often interferes with the intended change of geometry that is supposed to cause locking in order to prevent backsliding.

I am assuming that your task is a compact binding task (applying or holding tension around an object or group of objects).  Correct me if I am mistaken.
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Nickels

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Re: Challending medical knot tying scenario
« Reply #5 on: October 20, 2011, 08:47:57 PM »
roo:  That's exactly right - we're trying to hold tension around an object with a very small suture (about 0.3 mm).  The locking of a knot, plus ensuring that the back up knot is close behind is very tricky!  Thanks again for looking into this.

Sweeney

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Re: Challending medical knot tying scenario
« Reply #6 on: October 20, 2011, 09:16:48 PM »
The overhand locking knot should work (I've tried it in fine monofilament) but you cannot tighten it by pulling on the standing part. Using a needle or fine forceps the knot has to "roll" down to the Dines knot and be held there while the standing end is finally tightened. This is probably best practised with some cord first to understand the mechanics but it should be possible in a .3mm suture.

Barry

Dan_Lehman

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Re: Challending medical knot tying scenario
« Reply #7 on: October 20, 2011, 09:36:52 PM »
... where a suture has been tied around a wound and secured with a Dines knot.
...

It would be best to include an image of the knot of interest,
either directly --by your own camera, say-- or with a URLink
to some clear image (and not to some paper which might have
an image somewhere buried ... --I'm now still digging, trying
to find this; which is a waste of each responder's time (reinventing
the wheel), compared to the OP providing the information needed!).
So, far, I've reached the frustrating dead ends of finding image-LESS
astracts, full articles (w/image(s)?) for a fee --no thanks.

Having been consulted by a doctor some ages ago (who provided
materials to me, for *play*), I'm guessing that your material
is rather flexible?


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DDK

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Nickels

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Re: Challenging medical knot tying scenario
« Reply #9 on: October 21, 2011, 02:02:20 PM »
Thanks again everyone for your replies!  This has helped quite a bit already.

Sweeney: Thanks for the tips.  I'm working with rolling the double overhand knot.  As far as I can tell, when you "hold" the loops down just before tightening, there will always be some length of the suture between the dines knot and the first turn in the overhand knot which ends up as slack when finally tightening the overhand knot.  I'll try some more to see if I can get that last little bit out.

Dan_Lehman: Sorry Dan!  Here's a link to the dines knot:
The material is flexible - a multi-filament suture.  It's quite strong, but also very slippery which is making holding a knot very difficult.
Here's a picture of the application:
Because the dines knot (or any sliding/locking knot) can slip back, I'm trying to secure that with some additional knots.

DDK: Thanks for providing the link!

Again, many apologies if I'm not providing the right information or if I should be more clear.  Appreciate the help of everyone on this board.

Dan_Lehman

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Re: Challenging medical knot tying scenario
« Reply #10 on: October 22, 2011, 06:10:14 AM »
DDK, that URLink --lengthy though it be-- didn't work for me
(or not yet) : claimed it was either NA or I'd seen too much.
Maybe ..., BUT I'm thankful for the book reference, as it seems
one that could be added to a great many knotters' libraries,
for something quite different from the usual (and maybe better
done)!

Nickles, you still didn't clearly indicate the disposition of the
knot, but I think I've got it (two chances :o) --those squiggly,
cut-off indicators are towards the bound object, upper, as in
the schematic you followed the knot with.  --and that works,
anyway.

Which brings back old memories, for I discovered this as my
"#56''' " qua eyeknot (not to be drawn up so tightly as your
binder (for ring-loading).  --and then followed my notes
with recognition to Eastern sources, though via Brion Toss's
Rigger's Apprentice (pp. xviii/0 [i.e, between "xvii" & "1"], 331, & 381),
it comes out Chinese, not Japanese.  (Sounds like a myth ... .)

Now, to the problem at hand.  Nickles complains ... :

Quote
Unfortunately, even when locked, the Dines knot tends to slide back when the loop is under tension; however, it is useful to close the wound temporarily, prior to backing it up with (perhaps) some additional knots

I don't think that this is an accurate analysis of the failure.
(Btw, in some abstract of a related medical-knotting article,
it was stated that a failure was slippage of 2mm (!).)
What I see happening is that the bight/turn around the
in-tension-until-locking part simply doesn't get tensioned
and drawn snug by tightening via the 2nd end, and so
constitutes slack awaiting expansion of the bound object,
which then pulls it tight with the egress of material.
.:.  I'm skeptical at trying to redress this w/back-up knotting.
Or at least I want to try to find a direct solution, if possible.

My first general plan was to suggest employing a 2nd line,
to tie some gripping hitch to the two ends of the binding line,
which binder-hitch would be slid down into place and then
tightened around the binding line ends; then, tie off those
ends in a usual manner of successive/alternating half-hitches.
So, the binder-hitch would need to serve as a good *choke*
against the ring-loading of the binder, and as a good gripper
of the binder ends temporarily as they were further secured.

But I might have a more "direct" solution, using a ProhGrip
(aka "Blake's hitch") with a modification to enable it to be
locked once set.  As gripping hitches go, the ProhGrip works well
in like diameters (line to itself, in contrast to other such hitches
that are typically used in a smaller line gripping a larger one),
which is what is wanted here.  The modification I see at the
moment is to reeve the knot's tail through final turn and the
gripped line, to enable it to capsize its final turn and bend and
bind the line back against the knot --the bend, u-turn, being
what will prevent slippage.  Further, the angle of incidence
of the gripping knot to the gripped line is good for any wide
angle (relatively large object) --not so much an issue re the
"choke", as it would be for the knot I mused about above.

I don't have any 0.3mm (!!) stuff lying about to play with
--or maybe I do, but don't have my microscopic spectacles
on to see it.  One quick fiddling in 2mm (giant, hawserish!)
very soft-laid PP looks promising, at least.

I ID it : #20111021a00:44  (yes, this is my time, not GMT;
"a" = "sAturday").


QED?!

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roo

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Re: Challenging medical knot tying scenario
« Reply #11 on: October 22, 2011, 07:32:09 AM »
Nickels,

I think I may have something, but I'll let you decide.  I've attached a diagram. 

In all of these sliding binders, you have a hitch being tied around the standing part.  Then then standing part is pulled to cause the hitch to travel and bind.

I propose that we may tie this hitch component around the twinned portion of a coil made in the standing part.  I'm only showing the buntline hitch (which employs a clove hitch) as an example for simplicity and clarity.  Any better friction hitch of your choice would likely be employed.  So in the example, we cause the clove hitch to travel by first pulling on the blue line labeled "1".  Once this mechanism is squeezing the gray object, we pull on the green portion of line labeled "2" to set the line.  I suppose you may use a tube or other tool to hold the knot in place while you set the line.

This approach solves the problem I was having earlier with the tension in the binder preventing the knot form shift to cause locking.

I hope this works for you.  My eyes can't take working with the tiny, nearly invisible monofilament anymore.   ;)
« Last Edit: October 22, 2011, 06:37:33 PM by roo »
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DDK

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Re: Challenging medical knot tying scenario
« Reply #12 on: October 22, 2011, 02:37:00 PM »
@ Nickels

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. 

I had thought that "preconfigured" possibly meant that the post limb of the suture (that which goes through the knot pusher, what we might call the standing part of the knot) was first threaded around/through the object(s) to be tensioned, then reeved through a partially tied Dines Knot structure (which has been "tied" on the loop limb of the suture, what we might call the working end).  I'm wondering if the post limb can be further reeved through this partially tied Dines (prior to the sliding down of the knot) to produce a more secure knot.  This would require one to "roll down" the additional loop produced as one slides the knot.

DDK

roo

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Re: Challenging medical knot tying scenario
« Reply #13 on: October 22, 2011, 04:35:38 PM »
... Knot is provided beforehand to others with possibly little knot-tying expertise
In the solution I offered in my previous post this can be done.  In the simplified example, a clove hitch can be tied in the air first, and then that clove-ring is clamped to maintain form with forceps or clips, etc.  It'd probably be good to point the clamping forceps toward the intended "standing part entry side" of the hitch.  This could be done with whatever friction hitch is chosen (sailor's hitch, etc.).  Just about any friction hitch will be better than clove hitch.

Then you put the future standing part through once, coil around, and put it through twice.  Then proceed with the binding and setting operation once you release the hitch clips.

I believe that would make it easy for surgeons without an extensive knot tying background.  It would also save time during the operation.
« Last Edit: October 22, 2011, 06:33:05 PM by roo »
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roo

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Re: Challenging medical knot tying scenario
« Reply #14 on: October 22, 2011, 09:26:57 PM »
I'd like to offer an extension, pictured below, of my previous solution.  It may improve holding performance enough to use it with a simple buntline hitch.

Obviously, extra tucks may be made if desired.

As before, the blue portion is pulled first to shrink the loop, and as the knot is held in place, the green portion is pulled second to secure the knot from backsliding.
« Last Edit: October 22, 2011, 11:18:05 PM by roo »
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