The choice of suture materials is important in wound closure. Sutures are made of a wide variety of materials, both natural and synthetic. Natural substances include gut (sheep and beef), cotton, and silk. Natural substance sutures cause more tissue reactions and scarring, which limits their use. Cotton sutures are not discussed, as they are no longer used in clinical practice. Synthetic sutures can be made of nylon, polyethylene (Dacron), polyglactin (Vicryl), polypropylene (Surgilene, Prolene), polyglycolic acid (Dexon), poliglecaprone (Monocryl), polydiaxanone (PDS), polyglyconate (Maxon), and metal.6 Metal sutures are used in the Operating Room and not in the Emergency Department as they are difficult to handle, prone to breakage, and indicated in only a few situations. Synthetic sutures tend to have a problem with “memory.” That is, they tend to retain the shape of their packaging. This can make it difficult to manipulate the suture during wound closure.
Sutures are constructed as monofilaments or polyfilaments. Polyfilament fibers consist of multiple filaments braided together to form one suture. They are easier to handle than monofilament sutures, as they tend to be more pliable. Polyfilament sutures have better knot security and therefore reduce the incidence of knot slippage. However, they can be associated with a higher incidence of infection than monofilament sutures. They allow bacteria to migrate (or wick) between the strands of the suture located at the skin surface and into the wound.
Select the smallest diameter suture that can adequately hold the tissue edges together in order to reduce tissue damage and scarring. The largest suture material available is size #5. The suture sizes decrease to zero (#4, #3, #2, #1, #0) and then are followed by #00 (2-0), #000 (3-0), and #0000 (4-0), in decreasing size. The smallest suture commonly used in the Emergency Department is 6-0 for facial lacerations, nail bed lacerations, as well as lacerations in cosmetically sensitive areas. The tensile strength of sutures is related to their size. The tensile strength of suture increases as the size increases. For example, 4-0 is stronger than 5-0.
The other main category of suture classification is absorbable versus nonabsorbable. In the past, absorbable sutures were primarily used to close the subcutaneous layers of a wound. More recently, absorbable sutures have also been used for skin closure. Nonabsorbable sutures are primarily used for skin closure.
Absorbable Suture Materials
Absorbable sutures are degraded by the body and do not require removal. They usually do not maintain their tensile strength for longer than 60 days. Body enzymes dissolve the absorbable sutures with the aid of an inflammatory reaction. The rate of absorption of the sutures varies based upon the tissue where it is placed, the composition of the suture, and the size of the suture. Absorbable sutures placed in mucous membranes absorb faster than those placed in muscle tissue or fascia. Smaller sizes of suture dissolve faster than larger sizes.
There are several types of absorbable sutures, both natural and synthetic (Table 93-1). The most commonly used absorbable sutures in the Emergency Department are plain gut, chromic gut, polyglycolic acid (Dexon), polyglactin (Vicryl), and Vicryl Rapide. Plain gut and chromic gut are both natural forms of absorbable sutures. They are made from the intestines of sheep and cattle. Gut is a tissue irritant and can cause a substantial tissue reaction while it is being absorbed and degraded by the body. Chromic gut is plain gut that has been soaked in chromic acid salts. This process helps to extend the half-life of the suture and allows it to maintain its tensile strength longer than plain gut. Chromic gut may retain its tensile strength for 2 to 3 weeks, while plain gut retains its tensile strength for 1 to 2 weeks. Both types of gut are packaged wet in order to keep them from drying out and becoming too stiff.
Table 93-1 Absorbable Suture Materials ||Download (.pdf)
Table 93-1 Absorbable Suture Materials
|Suture type||Source||Tensile strength||Tissue reaction||Knot security||Absorption|
|Plain surgical gut||Beef or sheep collagen||Poor||Moderate||Poor||1–2 weeks|
|Chromic surgical gut||Beef or sheep collagen||Poor||Moderate||Fair||2–3 weeks|
|Monocryl||Poliglecaprone 25||20% remains by 3 weeks||Minimal||Good||3 months|
|Coated Vicryl||Polyglycolic 910, polyglactin 370, and calcium stearate||65% remains at 2 weeks; 40% at 3 weeks||Minimal||Fair||3–6 months|
|Dexon||Polyglycolic acid||50% remains at 4 weeks||Minimal||Good||3–4 months|
|Vicryl Rapide||Polyglactin 910||50% remains in 5–6 days||Minimal||Good||42 days|
|PDS polydioxanone||Polyester polymer||70% remains at 2 weeks; 50% at 4 weeks||Slight||Poor||6 months|
|Maxon||Polyglyconate||50% remains at 7 weeks||Slight||Fair||6 months|
Synthetic absorbable sutures, such as Dexon and Vicryl, are typically used more often than natural absorbable sutures in the Emergency Department. They are degraded by the body more slowly than natural fibers and can therefore help maintain the strength of the wound longer. Vicryl and Dexon maintain their tensile strength at 80 days and 120 days, respectively. They cause less reaction in the tissues as they break down when compared to natural absorbable sutures.
Recently, absorbable sutures have gained some popularity for use in skin closure.7–10 Absorbable sutures have been shown to yield equal results in their rate of dehiscence, rate of infection, and cosmesis when compared to nonabsorbable sutures.7 Absorbable sutures have the added benefit for the patient of not having to return to have their sutures removed. Vicryl Rapide is a newer form of Vicryl that is especially suited for this purpose. This type of suture is rapidly absorbed. They begin to fall off in 7 to 10 days as the wound heals. This can be especially useful for children in whom suture removal can be difficult, under casts, or if a patient will not be able to follow up due to travel.
Nonabsorbable Suture Materials
Nonabsorbable sutures are not degraded by the body and must be removed. They maintain their tensile strength for longer than 60 days. They are composed of monofilament or polyfilament strands of organic, synthetic, or metal fibers (Table 93-2). Nonabsorbable sutures generally have greater tensile strength and lower tissue reactivity than absorbable sutures. They are used in a variety of applications including skin closure. Nonabsorbable sutures can be used within a body cavity and subcutaneously, where they will eventually become encapsulated in connective tissue.
Table 93-2 Nonabsorbable Suture Materials ||Download (.pdf)
Table 93-2 Nonabsorbable Suture Materials
|Suture type||Source||Tensile strength||Tissue reaction||Knot security||Absorption|
|Silk (braided)||Organic protein||Gradual loss by progressive degradation||High||Good||Gradual encapsulation by connective tissue|
|Ethilon||Polyamide (nylon)||Progressive hydrolysis may result in gradual loss of tensile strength||Minimal||Fair||Gradual encapsulation by connective tissue|
|Nurolon||Polyamide (nylon)||Progressive hydrolysis may result in gradual loss of tensile strength||Minimal||Fair||Gradual encapsulation by connective tissue|
|Prolene||Polyamide (nylon)||Not subject to degradation||Minimal||Poor||Nonabsorbable|
|Mersilene||Polyester||No significant change occurs||Minimal||Good||Gradual encapsulation by connective tissue|
|Ethibond||Coated polyester||No significant change occurs||Minimal||Good||Gradual encapsulation by connective tissue|
|Stainless steel||Stainless steel||Indefinite||Minimal||Good||Nonabsorbable|
Nonabsorbable sutures can be classified as organic, synthetic, and wire. Organic sutures include those made of cotton or silk. Cotton is the oldest of the nonabsorbable sutures. It is not discussed here as cotton sutures are no longer used in general medical practice. Silk is a polyfilament suture that has limited use in the practice of Emergency Medicine. There are several advantages to silk suture material. Its pliability makes it very easy to handle. It holds knots better than other types of suture. However, as with all natural and/or polyfilament sutures, it has a greater tendency to cause wound infections. The polyfilament braids can provide a place for bacteria to lodge. Silk suture may actually protect the bacteria from attack by the body's defenses if the wound becomes infected. The primary use of silk sutures is for the repair of lip, oral cavity, and tongue lacerations.
Synthetic nonabsorbable sutures are available in monofilament and polyfilament forms. Commonly used synthetic sutures include nylon, polypropylene, polybutester, and Dacron. Nylon, polypropylene, and polybutester are monofilament synthetic sutures. Dacron is a polyfilament synthetic suture. The synthetic nonabsorbable sutures have several advantages over the natural nonabsorbable sutures. They are less reactive in tissues, generally stronger than the natural sutures, and retain their tensile strength over many years.
Nylon (Ethilon, Dermalon) is the most common nonabsorbable suture used in the Emergency Department. It is a monofilament suture, it is inert, and it does not tend to harbor bacteria. It is primarily used for skin closure. Nylon has good tensile strength and minimal tissue reactivity. However, nylon is difficult to handle and difficult to tie. It requires more knots to achieve good knot security than other types of suture. This is primarily due to the tendency of the suture to return to its packaged shape. This tendency is also known as “memory.” Because the knot can unravel or slip, it is important to place at least four or five knots when using nylon suture.
Polypropylene and polybutester are less commonly used synthetic nonabsorbable sutures. Polypropylene (Prolene) is stronger but more difficult to work with than nylon because it has greater memory. Polybutester (Novafil) is a newer suture in this category. It is stronger than the other monofilaments and does not have significant memory. Therefore, it is easier to work with than the other monofilament synthetic sutures.