Absorbable sutures are specialized surgical threads designed to close wounds and provide temporary tissue support. Unlike traditional stitches, these materials are engineered to be broken down and eliminated by the body over time, meaning they do not require a follow-up procedure for manual removal. This allows for internal closure and surface stitching that disappears as the wound heals fully.
The Core Chemical Compositions
Absorbable sutures are primarily classified into two distinct groups based on their origin and chemical makeup: natural and synthetic materials. Natural absorbable sutures are derived from purified collagen, historically sourced from the submucosa of sheep intestine or the serosal connective tissue of beef intestine, commonly known as surgical gut or Catgut.
Synthetic absorbable sutures, which are now the most widely used, are complex polymers created in a laboratory setting. These materials are built from repeating smaller chemical units called monomers. Common examples include Polyglycolic Acid (PGA), Polyglactin 910 (PGLA), and Polydioxanone (PDO).
The advantage of these synthetic polymers is that they break down into simple, non-toxic chemical components that are already naturally present in the body. For example, PGA and PGLA degrade into glycolic acid and lactic acid, which are then easily metabolized and excreted.
How Absorbable Sutures Dissolve
The primary mechanism for breaking down synthetic polymers is hydrolysis, a predictable, non-enzymatic process. Hydrolysis occurs when water molecules from the surrounding bodily fluids penetrate the suture material and break the long polymer chains into smaller fragments.
This gradual chemical reaction weakens the material’s structure until it completely disintegrates. Since this process is driven by the presence of water rather than biological agents, the rate of absorption is highly controlled and reliable.
In contrast, natural sutures like Catgut are dissolved primarily through enzymatic degradation. This process involves the body’s proteolytic enzymes, which are specialized proteins that attack and metabolize the collagen material. Because this breakdown is dependent on the concentration and activity of enzymes at the wound site, it is generally less predictable and can sometimes cause a higher local inflammatory response compared to synthetic materials.
Major Material Types and Their Absorption Timelines
The surgical application of absorbable sutures depends heavily on their absorption profile, which is typically divided into three categories based on the material’s strength retention and complete mass absorption timeline. Short-term absorption materials are used in tissues that heal rapidly, such as mucosal or skin layers that require support for only a week or two. Plain Catgut, for example, loses its tensile strength quickly and is fully absorbed within approximately 70 days. Another short-term example is Poliglecaprone 25 (PGCL), which retains strength for about a week and is completely resorbed within 91 to 119 days.
Medium-term sutures provide support for a longer period and are commonly used for general soft tissue closure. Polyglycolic Acid (PGA) and Polyglactin 910 (PGLA) are prominent materials in this class. PGA sutures typically maintain their strength for about two to three weeks and are fully absorbed within 60 to 90 days. PGLA has a similar profile, retaining effective strength for approximately three to four weeks with complete absorption occurring between 56 and 70 days.
For wounds requiring extended support, long-term absorption sutures are selected to ensure stability over many months. Polydioxanone (PDO) is the standard material in this group, designed for areas that are under constant stress or that heal slowly. PDO sutures can retain a significant portion of their initial tensile strength for as long as four to eight weeks, with the material requiring an extended period of 180 to 210 days for complete mass absorption.