What is a Suture ?
Sutures
Sutures are probably the largest group of devices implanted in humans, few
devices have been made of so many different materials. By definition, a
suture is a thread that either approximates and maintains tissues until the
natural healing process has provided a sufficient level of wound strength or
compresses blood vessels in order to stop bleeding.
The United States Pharmacopeia (USP) is the official compendium for
the suture industry. It sets standards and guidelines for suture
manufacture.
These monographs have the force of law, established the standards by which
legal acceptability of Sutures is judged, and are the final reference in
cases of compliment and dispute concerning properties covered by them.
The United States Pharmacopeia determines the procedure and
parameters for standard suture test. Sutures are tested immediately after
removal from their sterile packages without drying or conditioning. Diameters
of sutures are measured using a gauge of the dead-weight type with a
presser-foot 12.7 +/- 0.02mm in diameter. The diameter of each strand is
measured at three points corresponding roughly to one-fourth, one-half, and
three-fourths of the strand length.

Universal Ultra Test Machine
for Knot Pull Strength and
Needle Detachment Load |
For knot pull breaking strength, the suture is tied with a
surgeon's knot with one turn around a flexible rubber tubing of 6.5 mm
inside diameter and 1.6 mm wall thickness. The suture is then attached to a
suitable testing machine and tested at a rate such that the specimen breaks
in less than twenty seconds. In all strength tests, it is important to keep
in mind that the breaking strength retention of absorbable and nonabsorbable
sutures should be considered separately because the strength retention of
the absorbable sutures will be quite different than that of the
nonabsorbable suture.
Also, needle attachments tests are done in a similar manner to the knot
pull breaking strength tests. SMB measures knot pull strength and needle
etachment load on Universal Ultra Test Machine with microprocessor Digital
Advanced Force Gauge.
Nonabsorbable Surgical Suture
Nonabsorbable Surgical Sutures is a flexible strand of material that is
suitably resistant to the action of living mammalian tissue. It may be in
either monofilament or multifilament form. If it is a multifilament strand,
the individual filaments may be combined by spinning, twisting, braiding or
any combination thereof. It may be either sterile or nonsterile. Its
diameter and tensile strength correspond to the size designation indicated
on the label, within the limits prescribed herein. It maybe modified with
respect to body or texture, or to reduce capillarity and may be suitably
bleached. It may be impregnated or treated with a suitable coating,
softening, or antimicrobial agent.
Nonabsorbable Surgical Suture is classed and typed as follows.
Class[I] Suture is composed of silk or synthetic fibers of
monofilaments, twisted, or braided construction where the coating, if any,
does not significantly affect thickness (e.g., braided silk, polyester, or
nylon; monofilament nylon or polypropylene).
Class[II] Suture is composed of cotton or linen fibers or coated
-natural or synthetic fibers where the coating significantly affects
thickness but does not contribute significantly to strength (e.g., virgin
silk sutures).
Class[III] Suture is composed of monofilament or multifilament metal
wire.