Hernias occur when an internal organ or tissue pushes through a weakened area of muscle or fascia. To repair this weakness and reduce recurrence, surgeons often use a hernia mesh. These meshes act as a scaffold, reinforcing the weakened area and encouraging new tissue growth. The choice of material is important, as it directly influences how the mesh interacts with the body and its long-term effectiveness.
Synthetic Materials
Synthetic meshes are widely used in hernia repair and are primarily made from man-made polymers. These materials are engineered for strength and durability. They are classified based on their permanence: non-absorbable, which remain indefinitely, or absorbable, which degrade over time.
Polypropylene (PP) is a common non-absorbable synthetic material, known for its excellent strength and resistance to biological degradation. PP meshes are often knitted monofilaments, allowing for tissue ingrowth through their pores. While generally well-tolerated, PP meshes may lead to reduced flexibility and shrinkage over time.
Expanded polytetrafluoroethylene (ePTFE) is another non-absorbable synthetic material, known for its chemical stability and inert nature. ePTFE meshes often have a microporous structure, which can prevent immune cells from penetrating, potentially hindering infection clearance. Some ePTFE meshes are designed with a barrier layer to minimize adhesion to internal organs.
Polyester (PET) meshes are permanent, valued for their strength, toughness, and chemical resistance. Unlike polypropylene, polyester meshes may trigger a more pronounced inflammatory response. This can lead to increased scar tissue and mesh contraction over time.
Absorbable synthetic meshes, such as polyglycolic acid (PGA) or polylactic acid (PLA), gradually break down and are absorbed by the body. These meshes provide temporary support while the body forms its own strong tissue.
Biological Materials
Biological meshes offer an alternative to synthetic options, derived from natural tissues. They originate from human (allograft) or animal (xenograft) sources, such as porcine or bovine tissues.
Biological mesh processing involves decellularization, which removes all cellular components from the tissue. This leaves behind the extracellular matrix, primarily collagen, which acts as a natural scaffold.
The preserved extracellular matrix retains its natural structure, which allows the patient’s own cells to grow into and eventually remodel the mesh into new, integrated tissue. Biological meshes are absorbable, meaning they are gradually broken down and replaced by the body’s own regenerating tissue. They are often chosen for complex cases or in situations where there is a higher risk of infection, as they tend to integrate well and may have a lower risk of infection compared to permanent synthetic options.
Factors Influencing Material Choice
The selection of an appropriate hernia mesh material involves considering several important properties that affect its performance within the body. Biocompatibility is a primary concern, referring to how well the body tolerates the implanted material without adverse reactions. A mesh with good biocompatibility minimizes inflammation and promotes healthy tissue integration.
Tensile strength, or the material’s ability to withstand stretching forces, is another property. The mesh needs sufficient strength to reinforce the weakened abdominal wall and prevent the hernia from recurring. Flexibility is also important, allowing the mesh to conform to the body’s movements and reduce discomfort.
Porosity, which describes the size and number of pores in the mesh, plays a significant role in tissue ingrowth and the body’s response. Meshes with larger pores (typically greater than 75 micrometers) generally allow for better tissue integration and reduced scar tissue formation. This improved tissue ingrowth can lead to a more flexible and durable repair.
Finally, whether a mesh is permanent or absorbable influences its long-term function. Permanent meshes provide continuous reinforcement, while absorbable meshes offer temporary support, eventually dissolving as the body’s natural tissue strengthens the repair. The choice among these materials and their specific properties depends on the individual patient’s needs and the characteristics of their hernia.