A hernia occurs when an internal organ or tissue pushes through a weak spot in muscle or connective tissue, often appearing as a bulge. Surgical mesh is a medical device used to support the weakened tissue in hernia repair.
Why Mesh is Used in Hernia Repair
Before mesh, traditional hernia repairs relied solely on sutures to close the defect. These suture-only repairs often resulted in high rates of hernia recurrence, as the weakened native tissues struggled to withstand the body’s internal pressures.
Mesh provides a scaffold that reduces tension on the repair site and strengthens the abdominal wall. This reinforcement significantly lowers the chance of the hernia returning, with studies showing a decrease in recurrence rates by up to 50% compared to repairs without mesh. Mesh integration creates a more durable repair, contributing to benefits like reduced operative time and quicker recovery.
Synthetic Mesh Types and Properties
Synthetic meshes are widely used in hernia repair, primarily made from polypropylene (PP), polyester, and expanded polytetrafluoroethylene (ePTFE). Polypropylene is the most common choice due to its high tensile strength and ability to provide long-term structural support. It often induces an inflammatory response, which helps promote tissue ingrowth and a strong bond with the surrounding muscle.
Polyester mesh can oxidize within the body and may be less resistant to infection. It triggers a more significant inflammatory reaction compared to other synthetic options. Expanded polytetrafluoroethylene (ePTFE) is known for its neutral interaction with the body and minimal inflammatory response, but it tends to be the least resistant to bacterial infection.
Synthetic meshes are categorized as either non-absorbable or absorbable. Non-absorbable meshes remain permanently in the body, offering continuous, long-term reinforcement. Absorbable synthetic meshes dissolve over time, providing temporary support while encouraging the growth of new tissue. They are generally not recommended when prolonged strength is required.
Mesh properties also include weight and pore size, which influence integration and performance. Heavyweight meshes, with smaller pores, are composed of thicker filaments and create a more pronounced tissue reaction. Conversely, lightweight meshes, with larger pores, use thinner filaments, leading to a less intense foreign body response and greater elasticity. Larger pores generally facilitate better tissue ingrowth and flexibility, potentially reducing the risk of infection and shrinkage.
Biological Mesh and Its Applications
Biological meshes represent a distinct category of materials used in hernia repair, derived from natural tissues. These meshes typically originate from human, porcine (pig), or bovine (cow) sources. Through a specialized process, these animal or human tissues are rendered acellular, leaving behind a collagen matrix that serves as a scaffold.
Unlike synthetic meshes that provide permanent reinforcement, biological meshes are designed to be remodeled and gradually replaced by the patient’s own tissue over time. This process allows the body to integrate the mesh and rebuild its natural structures. Biological meshes are often reserved for specific clinical situations, particularly in contaminated surgical fields or when there is an elevated risk of infection with synthetic materials.
While historically favored in challenging environments, some data suggest synthetic meshes can perform comparably in certain contaminated settings. Biological meshes cost more than synthetic counterparts. For routine hernia repairs, biological meshes may also be associated with a higher recurrence rate.
Factors Influencing Mesh Selection
Mesh selection is guided by various factors and the surgeon’s judgment. The specific characteristics of the hernia, including its type, size, and location, play a significant role in determining the most suitable mesh. Patient-specific considerations are also important, including overall health and lifestyle. The presence or risk of infection at the surgical site is another factor. Ultimately, the goal is to choose a mesh that balances durability, flexibility, and the body’s biological response to optimize patient outcomes and minimize complications.