Surgical sutures, commonly known as stitches, are medical devices designed to hold body tissues together after an injury or surgical incision. Their main purpose is to maintain the approximation of wound edges until natural healing provides sufficient strength for the tissue to remain closed. The ideal suture should securely hold the wound for the necessary duration while causing minimal reaction within the body. Choosing the correct thread involves balancing factors like the required tensile strength, the location of the wound, and the expected healing time of the tissue being repaired.
The Primary Distinction: Absorbable Versus Non-Absorbable
The most fundamental way surgical threads are categorized is by their fate within the body. Absorbable sutures are designed to break down naturally over time, eliminating the need for a follow-up procedure to remove them.
These dissolvable threads break down through enzymatic degradation (for natural materials like catgut) or hydrolysis (for synthetic materials). Synthetic absorbable sutures, the more common modern choice, degrade via hydrolysis, where water slowly breaks the polymer chains. This process offers a more predictable rate of strength loss, making synthetic threads widely used for closing deep internal tissues, such as muscle layers or organ linings.
Conversely, non-absorbable sutures are made from materials the body cannot metabolize or break down, remaining intact indefinitely unless manually removed. They are employed when long-term wound support is required, such as in tendon repair, cardiovascular procedures, or for external skin closure. Although the body may encapsulate these permanent sutures, the material retains its original tensile strength for extended periods.
Material Composition: Natural and Synthetic Threads
The origin of the thread material forms another major classification, affecting the suture’s handling, strength, and the body’s reaction. Historically, natural sutures were standard, including catgut, derived from animal collagen, and silk, a braided non-absorbable thread. While silk is valued for its handling and knot security, natural fibers generally provoke a greater tissue reaction and are more prone to harboring bacteria than synthetic alternatives.
The majority of modern threads are synthetic, offering more consistent and predictable performance. Non-absorbable synthetic examples include Nylon and Polypropylene, the latter known for minimal tissue reactivity. For absorbable needs, synthetic polymers such as Polydioxanone (PDS) and Polyglycolic Acid (PGA) are widely used. These materials allow manufacturers to precisely control the thread’s strength and absorption profile, leading to reliable outcomes.
Physical Structure: Monofilament and Braided Sutures
Surgical threads are also defined by their physical structure: monofilament or multifilament. Monofilament sutures consist of a single, uniform strand, providing a smooth surface that minimizes friction as they pass through tissue. This slick surface reduces tissue drag and significantly lowers the risk of infection because there are no spaces to harbor bacteria.
The single-strand construction of monofilament threads, such as Nylon or PDS, often makes them stiffer and challenging to handle, sometimes giving them a “memory.” Their smooth texture also reduces knot security, often requiring surgeons to tie extra throws. Despite these handling issues, the reduced tissue trauma and lower infection risk make monofilaments the preferred choice for vascular surgery or closure in contaminated wounds.
In contrast, multifilament sutures are made from several small filaments twisted or braided together, as seen in materials like silk or PGA. This braided structure provides superior flexibility and handling characteristics. While the textured surface enhances knot security for high-tension closures, the greater surface area can theoretically increase the risk of infection, which is why they are often coated to improve tissue passage.
How Doctors Select the Right Thread
The choice of surgical thread integrates all three classification systems based on the unique demands of the procedure and the patient. A primary consideration is the required duration of support, which must match the tissue’s healing time. For instance, a fast-healing organ might require a rapidly absorbing suture, while fascia or tendons, which heal slowly, require a non-absorbable or very slow-absorbing thread.
The anatomical location also plays a significant role, particularly concerning the potential for infection and cosmetic outcomes. For wounds in high-tension areas or those with a high risk of bacterial contamination, a monofilament thread is often chosen due to its lower propensity to harbor microorganisms. Conversely, in cosmetic procedures, surgeons may prefer a fine, absorbable thread for subcuticular closures to avoid the need for removal and minimize visible scarring.
The selection process balances the thread’s tensile strength, handling properties, and anticipated tissue reaction. Surgeons weigh the superior knot security of braided sutures against the lower infection profile of monofilament sutures. By considering the wound type, the patient’s overall health, and the specific properties of the thread material, doctors ensure the chosen stitch provides optimal support for a successful recovery.