(Brian Grimley) wrote in
om:

Thanks for your comments Brian.

... I would tie a particular knot
several times for each material. I would also try to tie each knot
with the same tension.

We repeated the experiment 7 times for each of 11 different suture
materials. The final 2 throws were tied with a standardised tension of
500gms.

I would try to obtain the "stretch" ....

This might be a factor. Some of the materials (particularly the
monofilaments) stretch but don't seem to recover. Ductile might be the
term I think. We did not "prestretch" to remove this ductility. Maybe
that would make a difference.


coefficent of friction of the materals and see if there is any
correlation between them and the results of the "knot-in-a-sponge -
warm rinse cycle".

I'm sure this is a factor. Some threads (particularly the braided ones)
are deliberately coated so they slip through the tissue easily but the
down side is the knot insecutity. The coatings vary between
manufacturers but commonly soap teflon, or other polymers are used.


.... range of tensions with a specific knot and specific material, one
could repeat the "knot-in-a-sponge - warm rinse cycle" and see if
there is a threshold. Similarily, different materials may have a
requirement for a much higher tension when setting a knot to obtain
resistance to unravelling than other materials.

I think this might be a fruitfull avenue to explore. Intuitively I
think that with failure under load the tension when tying the knot might
not matter all that much, where as for unravelling when not loaded (I
still think there needs to be a generally accepted term for this) it
might be a more important factor.

Doug Turner