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are buried within the tissues. When used for skin closure, they must be removed postoperatively.

A further subdivision of suture materials is useful: monofilament and multifilament. A monofilament suture is made of a single strand. It resists harboring microorganisms, and it ties down smoothly. A multifilament suture consists of several filaments twisted or braided together. This gives good handling and tying qualities. However, variability in knot strength among multifilament sutures might arise from the technical aspects of the braiding or twisting process.

The sizes and tensile strengths for all suture materials are standardized by U.S.P. regulations. Size denotes the diameter of the material. Stated numerically, the more zeroes (0's) in the number, the smaller the size of the strand. As the number of 0's decreases, the size of the strand increases. The 0's are designated as 5-0, for example, meaning 00000 which is smaller than a size 4- 0. The smaller the size, the less tensile strength the strand will have. Tensile strength of a suture is the measured pounds of tension that the strand will withstand before it breaks when knotted. (Refer to Absorbable Sutures & Nonabsorbable

Sutures section)

Principles of Suture Selection

The surgeon has a choice of suture materials from which to select for use in body tissues. Adequate strength of the suture material will prevent suture breakage. Secure knots will prevent knot slippage. But the surgeon must understand the nature of the suture material, the biologic forces in the healing wound, and the interaction of the suture and the tissues. The following principles should guide the surgeon in suture selection.

1.When a wound has reached maximal strength, sutures are no longer needed. Therefore:

a.Tissues that ordinarily heal slowly such as skin, fascia, and tendons should usually be closed with nonabsorbable sutures. An absorbable suture with extended (up to 6 months) wound support may also be used.

b.Tissues that heal rapidly such as stomach,colon, and bladder may be closed with absorbable sutures.

2.Foreign bodies in potentially contaminated tissues may convert contamination to infection. Therefore:

a.Avoid multifilament sutures which may convert a contaminated wound into an infected one.

b.Use monofilament or absorbable sutures in potentially contaminated tissues.

3.Where cosmetic results are important, close and prolonged apposition of wounds and avoidance of irritants will produce the best result. Therefore:

a.Use the smallest inert monofilament suture materials such as nylon or polypropylene.

b.Avoid skin sutures and close subcuticularly, whenever possible.

c.Under certain circumstances, to secure close apposition of skin edges, a topical skin adhesive or skin closure tape may be used.

4.Foreign bodies in the presence of fluids containing high concentrations of crystalloids may act as a nidus for precipitation and stone formation. Therefore:

a.In the urinary and biliary tract, use rapidly absorbed

sutures.

5.Regarding suture size:

a.Use the finest size, commensurate with the natural strength of the tissue.

b.If the postoperative course of the patient may produce sudden strains on the suture line, reinforce it with retention sutures. Remove them as soon as the patient?s condition is stabilized.

Metric Measures and U.S.P Suture Diameter Equivalents

Absorbable Sutures

Absorbable Sutures

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The United States Pharmacopeia (U.S.P.) defines an absorbable surgical suture as a "sterile strand prepared from collagen derived from healthy mammals or a synthetic polymer. It is capable of being absorbed by living mammalian tissue, but may be treated to modify its resistance to absorption. It may be impregnated or coated with a suitable antimicrobial agent. It may be colored by a color additive approved by the Federal Food and Drug Administration (F.D.A.)."

The United States Pharmacopeia, Twentieth Revision, Official from July 1, 1980.

Absorbable Suture Materials Most Commonly Used

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