Silk3/4frequently reacts with tissue and can be "spit" from the wound.

* Cotton 3/4 loses tensile strength with each autoclaving.
* Linen 3/4 is better than silk or cotton but is more expensive and not as readily available.
* Synthetic materials (e.g., nylon, dermalon)3/4 are excellent, particularly for surface use. They cause very little tissue reaction. Their only problem seems to be the tendency for the knots to come untied. (Because of this tendency, most surgeons tie 3 to 4 square knots in each such suture.) Nylon is preferred over silk for face and lip areas because silk too often causes tissue reactions.

* Rust-proof metal (usually stainless steel wire) 3/4has the least tissue reaction of all suture materials and is by far the strongest. The primary problems associated with it are that it is more difficult to use because it kinks and that it must be cut with wire cutters.

ABSORBABLE SUTURES.-These are sutures that are absorbed or digested during and after the healing processes by the body cells and tissue fluids in which they are embedded. It is this characteristic that enhances their use beneath the skin surfaces and on mucous membranes.

Surgical gut fulfills the requirements for the perfect suture ease of manufacture, tensile strength, and variety available more often than any other material.

Manufacture of catgut: Though it is referred to as "catgut," surgical gut is derived from the submucosal connective tissue of the first one-third (about 8 yards) of the small intestine of healthy government-inspected sheep. The intestine of the sheep has certain characteristics that make it especially adaptable for surgical use. Among these characteristics is its uniformly fine-grained tissue structure and its great tensile strength and elasticity.

Tensile strength of catgut: This suture material is available in sizes of 6-0 to 0 and 1 to 4, with 6-0 being the smallest diameter and 4 being the largest. The tensile strength increases with the diameter of the suture.

Varieties of catgut: Surgical gut varies from plain catgut (the raw gut that has been gauzed, polished, sterilized, and packaged) to chromic catgut (that has undergone various intensities of tanning with one of the salts of chromic acid to delay tissue absorption time). Some examples of these variations and their absorption times follow in table 4-3.

Suture Needles
Suture needles may be straight or curved, and they may have either a tapered round point or a cutting edge point. They vary in length, curvature, and diameter for various types of suturing. Specific characteristics of suture needles are listed below.

Size: Suture needles are sized by diameter and are available in many sizes.

Taper point: Most often used in deep tissues, this type needle causes minimal amounts of tissue damage.
Cutting edge point: This type needle is preferred for suturing the skin because of the needle's ability to penetrate the skin's toughness.
Atraumatic (atraloc, wedged): These needles may either have a cutting edge or a taper point.

Additionally, the suture may be fixed on the end of the needle by the manufacturer to cause the least tissue trauma.