Surgical adhesives are biocompatible materials developed for use in medicine to close wounds and repair internal tissues without the need for traditional sutures or staples. They offer a less invasive and faster alternative for tissue approximation. These materials function by creating a stable bond between separated tissue surfaces, providing immediate support for the healing process. Their use is particularly beneficial in complex surgical fields where traditional mechanical closure is difficult or time-consuming.
Composition and Types
Surgical adhesives are broadly categorized into natural (biological) and synthetic materials, each with a distinct chemical structure and mechanism of action. Biological adhesives often mimic the body’s natural processes, with Fibrin sealants being the most common example. These sealants are derived from human plasma components, specifically purified fibrinogen and thrombin. When combined, these components replicate the final stage of the blood clotting cascade to form a stable, biological matrix.
Synthetic adhesives are polymer-based compounds chemically engineered for medical use. Cyanoacrylates are a prominent synthetic class, similar to common super glues but formulated with longer molecular chains to improve biocompatibility. Other synthetic options include polyethylene glycol (PEG) hydrogels and glues based on proteins like albumin, which utilize cross-linking agents for stability. Fibrin sealants are resorbable, meaning the body naturally breaks them down, while some synthetic types are non-resorbable or degrade very slowly.
How Adhesives Seal Tissue
The liquid adhesive creates a strong bond by initiating a rapid chemical or biological reaction upon application to the tissue surface. Synthetic cyanoacrylates achieve tissue approximation through a process called anionic polymerization. The liquid monomer rapidly links together into a solid polymer chain when it contacts the moisture and tissue proteins present on the wound surface. This fast reaction forms a strong, immediate physical barrier that holds the tissue edges together.
Biological sealants, such as Fibrin, function by leveraging the body’s natural healing mechanisms. Fibrinogen and thrombin are applied simultaneously to the site of injury, where the thrombin enzyme acts to convert the soluble fibrinogen protein into insoluble fibrin strands. These strands then interweave to form a stable, mesh-like clot that adheres strongly to the tissue. This biological matrix immediately seals the wound and provides a scaffold for the body’s own cells to begin the repair process.
Adhesives provide a chemical or biological cohesion that seals microscopic gaps, in contrast to the mechanical strength provided by sutures. The adhesive material must possess high interfacial bond strength, which comes from interactions like chemical bonds between the adhesive and the tissue. This ability to solidify quickly and adhere strongly under wet, physiological conditions is what makes these materials effective alternatives for tissue closure and sealing.
Common Medical Applications
Surgical adhesives are frequently utilized in surgical specialties where a leak-proof seal or minimal tissue trauma is desired. In skin closure, especially after pediatric or cosmetic procedures, cyanoacrylate adhesives are applied to the external skin layer to approximate the wound edges, often resulting in less scarring than traditional stitches. The adhesive provides a strong, flexible seal that remains in place until the underlying tissue is strong enough to hold itself together.
Internally, these sealants are particularly valuable for managing fluid and air leaks in delicate organs. For instance, in thoracic surgery, Fibrin sealants are routinely used to seal air leaks in the lung tissue after the removal of a section of the lung. Adhesives are also instrumental in stopping bleeding (hemostasis) from large, raw surfaces of solid organs like the liver or spleen, where the tissue is too fragile to be sewn effectively.
The ease of application in confined spaces has made adhesives an attractive tool in laparoscopic and other minimally invasive surgeries. Surgeons can deliver the fluid-like adhesive through a small port, which simplifies the process of joining cut tissues deep inside the body compared to manipulating sutures or staples. Adhesives are also used in neurosurgery to help prevent cerebrospinal fluid leaks after procedures involving the brain or spine.
Absorption and Healing
The final role of a surgical adhesive is to support the tissue until it is fully healed, after which the material must be safely processed by the body. Biological adhesives, such as Fibrin sealants, are designed to be bioresorbed; the body’s natural enzymes break down the fibrin clot over a period that can range from several days to months. This degradation process occurs gradually, ensuring the adhesive’s structural support diminishes only as the underlying tissue gains mechanical strength.
Synthetic adhesives have a more varied absorption profile, which is a consideration in their selection. Some cyanoacrylates are non-resorbable, while others break down slowly over time. Polyethylene glycol-based glues, for instance, can degrade over a period that may extend up to 20 months. Materials used inside the body must be highly biocompatible, meaning they do not provoke a harmful immune response as they degrade.
The temporary presence of the adhesive provides a protective barrier and a scaffold for the migration and proliferation of new cells. The adhesive’s support allows the tissue to undergo its natural repair cycle, including the formation of new collagen, without being subjected to mechanical stress.