Product Manual

When enough force is applied to the tied suture to result in breakage, the site of

disruption of the suture is almost always the knot. The force necessary to break

a knotted suture is lower than that required to break an untied suture made

of the same material.

The forces exerted on a tied suture are converted into

shear forces, by the knot configuration that break the knot. The percentage loss

of tensile strength, as a result of tying a secure knot, is least with mono-filament

and multifilament steel.

This relationship between the tensile strength of

unknotted and knotted suture which is designated knot efficiency, is described

in the following equation:

Knot efficiency (%) = tensile strength of a knotted suture

tensile strength of unknotted suture

Regardless of the type of suture material, the efficiency of the knot is enhanced

with an increasing number of throws, although only up to a certain limit.

The type of knot configuration that results in a secure knot that fails by

breaking varies considerably with different suture material. The magnitude of

force necessary to produce knot breakage is influenced by the configuration

of the knotted suture loop, type of suture material, and the diameter of the

suture.

The tissue in which the suture is implanted also has considerable

influence on the knot strength of suture. In the case of absorbable sutures, a

progressive decline in knot breaking strength is noted after tissue implantation.

In addition, the magnitude of knot breakage force is significantly influenced by

the rate of application of forces to the “ears” of the knot.

When a constant

force is applied slowly to the knot “ears,” the knot breakage force is significantly

greater than that for knots in which the same constant force is applied rapidly

to the “ears.” The latter knot loading rate is often referred to as “the jerk at the

end of the knot,” especially when the knotted suture breaks.

knot breakage