Terminology

(Karl Pollak) wrote in
:

..Doug, I take it that you are talking about silk sutures, rather than
sythetic ones. ..... We're used to play with fishing
lines and cables and ropes and all sorts of other fun things, but I
doubt there is one amongst us who had ever tested his knotting skills
inside somebody else's body.

I don't think ther is anything different or special about suture
material. When I was a young doctor in the 1970 some hospitals still
used nylon fishing line as suture material. It was threaded through a
reusable needle. Now days it is the same nylon but custom packaged with
a needle already swagged onto to the line. Some newer soluble suture
materials look and feel very similar to nylon or polypropylene but are a
bit more "springy" and their knots have disconceting habit of un-
ravelling. This is a property of the material, not its location. The
mechanism is shaking or vibration when the suture (rope, line etc) in
not under load. I see a lot of references to this in the climbing and
nautical people but strangely it is not some thing surgeons know about.

Essentially surgeon's knot is a variation of the reef or square knot
in which the second time you wind the two different ends around each
other, you do 3 or 4 passes instead of a simple one. The additional
friction is believed to hold the knot more secure.

This is the knot surgeons traditionally use. It is used because it is
easy to tie under difficult conditions. It's not much good asking
surgeons about knots as they only ever use the one knot but can
generally tie it blindfolded, one handed,under blood, wearing double
gloves etc etc. But I would not let most of my collegues tie any knot I
intended to fish with!

Doug Turner

x-no-archive: yes
Doug Turner wrote:

reusable needle. Now days it is the same nylon but custom packaged with
a needle already swagged onto to the line. Some newer soluble suture
materials look and feel very similar to nylon or polypropylene but are a
bit more "springy" and their knots have disconceting habit of un-
ravelling. This is a property of the material, not its location.

Have you considered contacting the manufacturer of the material?

--
Karl Pollak, Richmond, British Columbia
Sea Scouting in Canada at http://www.seascouts.ca/

.. Have you considered contacting the manufacturer of the material?

No, but they have a disclaimer in the product information section warning
about its knot holding properties.

Doug

Doug Turner wrote in message 1.5...
(Brian Grimley) wrote in
om:

.....
Another variable to interpret the "knot-in-a-sponge - warm rinse
cycle" would be the "spring" in the thread. By "spring" I mean the
force of the thread to straighten itself when bent.......

Hi Brian, I think this might be another term for "memory". A rubber
band (besides being very stretchy) has a lot of memory. You can bend or
kink it as much as you like and it will resime its initial shape.
Stainless steel wire on the other hand has little memory. Once bent or
deformed it retains that shape. This tends to make knots more secure.


... A suggestion for a generally accepted term for unravelling when not
loaded is UNL (Unravelling when Not Loaded). I think UNL trips lightly
from the tongue and acronyms are always fun and popular. :-)

Sounds good too. But what really surprises me is there is not an
already accepted term.

...As a "brain storming" suggestion, perhaps the suture should be
manufactured so that the needle and the first 1/2 of the suture are
friendly to piercing tissue. The second half changes (perhaps with
colour for identification) to have properties to reduce UNL.

Mostly a long thread is used to tie multiple sutures like you see in a
repaired skin wound. Each suture is tied near the end of the long
thread, cuting the tail off near the skin and re-using the now shortened
thread until none is left.


...If you are Doug Turner, the "orthopod", I expect, when you read
this, to hear your
groan where I live - 1/2 way around the world.


'Tis me. ...I give up...how did you find me?

Doug Turner


The memory quality mentioned earlier is, I believe, very significant
to this entire discussion, since even the best tied knot will tend to
unravel if the coefficient of friction is too little to adequately
secure a knot, especially if it is not under any real load or a
changeable load. Dealing with a wet environment and 'slimy' tissues
and juices, one can hardly expect an essentially smooth fiber to
resist movement as its memory tries to open the knot. When synthetic
fibers are made, the maker is primarily concerned with ease of
manufacture which mostly involves straight linked polymers, of course,
since that creates maximum profit, and there is no reason to assume so
much nobility on the part of makers of medical sutures that they are
not also bound by this normal dictum of the business world. They do
not exist to help surgeons; they exist to make a profit -- a BIG
profit! This means that they are going to publish disclaimers and
tacitly blame the users (surgeons) for poor knot tying technique since
that takes all responsibility from their product.

What to do? Is it possible to find someone medical who is so prominent
that he can influence the OWNERS of these companies making the suture
material to change to EMBOSSED fibers such as are often made by the
makers of fabric synthetics to address the specific tension
requirements of a designed fabric? The process of EMBOSSING (sometimes
called CRIMPING) the surface of a synthetic as it exits the
spinarettes of the extruding machine, has long been used by textile
fiber makers to achieve the degree of 'tack' necessary for a weave or
knit to hold against other fibers. This Embossing or Crimping process
does add another cost step to the making, and also will somewhat
reduce the strength of the fiber, so there is, of course, a
cost/benefit analysis to be done. The maker will always resist any
change unless they can see a profit motive involved, since that is
their business, not surgery. Perhaps an article on this problem in
JAMA or LANCET or other prestegious journal will bring others to your
cause and put subtle pressure on the makers to improve their product.
Yes, a surgeon usually does not have time to do the tests that the
journals will expect to underpin your conclusions, but if you have a
friendly relationship with a manager at one of the suture makers, it
is possible that you can get him to sponsor a test of materials (NOT
knots) as to coefficients of friction under 'wet and lubricated'
conditions. If he will agree in advance to allow you to publish his
results (with credit to his firm, of course!) it is possible that you
will have the nucleus of an article with documentation of tests, and
then even if his firm declines to revamp their fibers (which they
might for business reasons), other firms may take heed and see an
opportunity to outsell their competitors by claiming dominance of the
market for suture materials. You might in fact contact Textile
Engineers through such directories as Davison's Textile Blue Book (at
larger libraries or on-line) to get their expert opinions to insert in
your article in the medical press. There are departments of textile
science at some universities, and perhaps a dean or professor at some
such would be willing to undertake a study with their students to
determine definitavely what the benefits/merits/faults of
uusing/designing special Embossed fibers would be to the medical arts.
Such contacts might also lead you to makers who would be more
sympathetic to your needs, or merely wanting to penetrate the medical
materials field. These people think in commercial terms, not medical
ones, so you must appeal to their motives if you expect results.

Clearly, it is not the fault of the surgeon who learns all reasonable
knots, but is defeated by the new synthetic materials, and even the
traditional silk under some circumstances. Since failure of knots in
sutures or the like might end up as the cause in a malpractice suit,
it is quite possible that some providers of malpractice insurance
would be willing to fund a study at some school, with perhaps you
doing the write-up for a medical journal. If you can site specific
cases of suture/knot failures leading to costly or horrible results,
you would be that much more ahead of the naysayers. Best Wishes!