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KNOT
TYING
There are many knot tying variations and techniques, all
with the intention of completing a secure, square knot. A complete
square knot consists of two sequential throws that lie in opposite
directions. This is necessary to create a knot that will not
slip (Figure 4.17).
A surgeon’s knot is a variation in which a double
throw is followed by a single throw to increase the friction
on the suture material and to decrease the initial slip
until a full square knot has been completed (Figure
4.18).
Use a minimum of two complete square knots on any substantive
vessel and more when using monofilament suture. If the suture
material is slippery, more knot throws will be required to
ensure that the suture does not come undone or slip. When
using a relatively “non-slippery” material
such as silk, as few as three throws may be sufficient to
ensure a secure knot.
Cut sutures of slippery materials longer than those of “non-slippery” materials.
There is a balance between the need for security of the knot
and the desire to leave as little foreign material in the
wound as possible.
Techniques
There are three basic techniques of knot tying.
1 Instrument tie
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This
is the most straightforward and the most commonly used
technique; take care to ensure that the knots are tied
correctly |
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You
must cross your hands to produce a square knot; to prevent
slipping, use a surgeon’s knot on the first throw
only |
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Do
not use instrument ties if the patient’s life depends
on the security of the knot (Figure
4.19). |
2 One handed knot
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Use
the one handed technique to place deep seated knots and
when one limb of the suture is immobilized by a needle
or instrument |
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Hand
tying has the advantage of tactile sensations lost when
using instruments; if you place the first throw of the
knot twice, it will slide into place, but will have enough
friction to hold while the next throw is placed |
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This
is an alternative to the surgeon’s knot, but must
be followed with a square knot |
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To
attain a square knot, the limbs of the suture must be
crossed even when the knot is placed deeply (Figure
4.20).
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3 Two handed knot
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The
two handed knot is the most secure. Both limbs of the
suture are moved during its placement. A surgeon’s
knot is easily formed using a two handed technique (Figure
4.21).
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With practice, the feel of knot tying will begin to
seem automatic. As with learning any motor skill, we
develop “muscle memory”.
Our brain teaches our hands how to tie the knots, and
eventually our hands tie knots so well, we are no longer
consciously completing each step.
To teach knot tying (or any other skill) to someone else, remember
the discrete steps involved. Demonstrate the whole skill of tying
a knot; then demonstrate each step. Let the learner practice
each step. Watch carefully and reinforce the correct actions,
while making suggestions to correct problems. Once each step
is mastered, the learner should put them together to tie a complete
knot on his/her own. The learner must then practice tying knots
over and over again, until the steps become a more fluid action
requiring less conscious thought.
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