A surgical suture, or stitch, is used to hold body tissues together following an injury or surgical incision. The primary goal of this thread and needle combination is to facilitate healing by securing the edges of a wound in close alignment. This approximation reduces the risk of infection and helps minimize scarring. Material selection depends on the tissue type, the tension on the wound, and the required duration of support.
The Fundamental Difference: Absorbable Sutures
Absorbable sutures are designed to break down and be safely metabolized by the body over a predictable period. They are chosen for internal closures, such as deep tissue layers or organs, where temporary support is sufficient until the wound heals. Since they dissolve, no follow-up procedure is needed to remove them.
Most modern synthetic absorbable sutures break down via hydrolysis, where water molecules gradually attack the thread’s polymer chains. This leads to a predictable loss of tensile strength and complete absorption. This is more controlled than the enzymatic degradation of older materials like catgut, which is derived from purified animal intestines.
Synthetic materials offer greater control and less tissue reaction. Polyglycolic Acid (PGA) is a common braided synthetic absorbed within two to three months. Polyglactin 910 is also absorbed through hydrolysis and is valued for its handling. For longer support, Polydioxanone (PDS) maintains strength for several weeks and takes up to six months to disappear.
Permanent Closure: Non-Absorbable Sutures
Non-absorbable sutures resist breakdown and either remain permanently embedded or must be manually removed. They are selected for areas requiring long-term structural support or tissues subject to high mechanical stress. They are commonly used for external skin closure, removed by a clinician once the wound has healed.
Internally, these threads are used in procedures like cardiovascular surgery where permanent closure is necessary. Common synthetics include Nylon and Polypropylene. Both are monofilaments, causing minimal inflammatory response. Polypropylene is favored in delicate vascular work due to its chemical inertness.
Traditional materials like Silk are also used; they are flexible but can elicit a greater tissue response than synthetics. For extreme strength, such as in orthopedic procedures, stainless steel wire is the most durable non-absorbable option.
Beyond the Thread: Alternative Wound Closures
Surgeons frequently employ alternatives to traditional sutures based on the wound’s size, depth, and location. Surgical staples offer a speed advantage, making them suitable for closing long skin incisions following abdominal or orthopedic procedures. Staples are useful in high-volume areas or for scalp wounds, where rapid placement saves valuable operating time.
For small, low-tension wounds, surgical adhesives (glue) provide a needle-free closure option. These glues are typically made from cyanoacrylate compounds that quickly polymerize on the skin’s surface, creating a strong, protective seal. The glue naturally sloughs off as the skin heals, usually within five to ten days, and is often preferred for cosmetic results since it avoids needle puncture marks.
Adhesive tapes, commonly known as Steri-Strips, are a non-invasive alternative often used to reinforce a closure after staples or sutures have been removed. These sterile strips are applied across the wound to hold the edges together. Tapes are most effective for linear, low-tension lacerations that do not extend deep into the tissue.
The Sizing System: What Suture Gauge Means
Suture diameter, or gauge, is standardized using the United States Pharmacopeia (USP) system, which dictates the material’s thickness and tensile strength. This sizing system uses an “aught” designation. Larger numbers, such as 6-0 (“six-aught”), represent a finer, thinner thread, while smaller numbers, like 1-0 (“one-aught”) or size 1, indicate a significantly thicker material.
Gauge selection relates directly to the tissue being closed and the cosmetic outcome. Extremely fine sutures, such as 8-0 or 10-0, are used in delicate procedures like ophthalmic surgery. Conversely, thicker sizes, such as 0 or 1, are needed for high-strength closures, such as repairing the abdominal wall fascia, where maximum tensile strength is required.