A hernia occurs when an internal organ or tissue pushes through a weak spot in the muscle or tissue wall. This can manifest as a bulge, often in the abdomen or groin area. Hernia repair surgery frequently uses a mesh to reinforce this weakened tissue. The mesh acts as a scaffold, providing structural support to the damaged area and helping prevent recurrence. This reinforcement allows the body’s own tissues to heal and integrate, stabilizing the repair and reducing the chances of the hernia returning.
Synthetic Mesh Materials
Synthetic hernia meshes are man-made devices providing permanent reinforcement. These meshes are primarily composed of durable polymers that remain in the body indefinitely. The most common materials include polypropylene (PP), polyethylene terephthalate (PET), and expanded polytetrafluoroethylene (ePTFE).
Polypropylene (PP) is a widely used synthetic material known for its strength and mechanical stability. It is a non-absorbable polymer exhibiting resistance to biological degradation. While durable, polypropylene meshes can experience reduced flexibility, shrinkage, and local cracks over time.
Polyethylene terephthalate (PET), also known as polyester, offers a soft texture with significant strength. PET meshes resist many chemicals and are susceptible to hydrolysis and long-term degradation.
Expanded polytetrafluoroethylene (ePTFE) is a synthetic polymer known for its chemical stability and inert nature, making it resistant to degradation. ePTFE typically has a smooth texture and can inhibit tissue ingrowth, requiring proper fixation to prevent easy breakage.
Synthetic meshes are constructed from either monofilament or multifilament fibers. Monofilament meshes, made from single strands, present a lower risk of infection because bacteria find it difficult to colonize. Multifilament meshes, braided from multiple strands, can trap bacteria, making infections harder to clear.
Biological Mesh Materials
Biological meshes are derived from natural sources, such as animal tissues (porcine or bovine dermis/pericardium) or human cadaveric dermis. A key characteristic of these meshes is their absorbable nature, meaning the body gradually incorporates or replaces them over time. They provide a temporary scaffold that is eventually remodeled by the body’s own tissues. Biological meshes are often used in specific situations, such as contaminated surgical fields.
Preparation involves decellularization, which removes cellular components from the donor tissue, leaving a collagen scaffold. This minimizes the immune response in the recipient, allowing for better integration and reducing rejection risk.
How Material Properties Influence Mesh Function
The properties and design of hernia mesh materials impact their performance and suitability. Biocompatibility, how a material interacts with the body, is a key factor, as different materials cause varying foreign body reactions and inflammation.
Mesh pore size plays a role in tissue integration and the body’s response. Macroporous meshes, typically with pore sizes greater than 75 micrometers, facilitate better tissue ingrowth. This larger porosity helps reduce inflammation and minimizes scar bridging, allowing immune cells to penetrate and clear infections. Microporous meshes, with pores smaller than 10 micrometers, hinder tissue ingrowth and increase infection risk because immune cells struggle to enter.
Flexibility and weight also affect patient comfort and surgical handling. Lightweight meshes are generally more elastic and induce a less pronounced foreign body reaction. These characteristics contribute to improved patient comfort and allow for better abdominal wall distension. Heavyweight meshes, while strong, can restrict abdominal movement and lead to dense adhesions. The choice balances tensile strength and elasticity.
Non-absorbable meshes provide permanent reinforcement and lasting structural support. Absorbable meshes offer temporary support, dissolving as the body heals and generates new tissue.
Some meshes feature specialized coatings to prevent adhesion to internal organs, especially when placed within the abdominal cavity. These coatings, made from materials like collagen or ePTFE, create a barrier between the mesh and viscera, reducing complications.
The material’s inherent strength dictates its capacity to provide lasting support against abdominal pressure. Synthetic polymers offer robust mechanical stability, while biological scaffolds vary in tensile strength. The design balances strength with flexibility to adapt to body movements.