Mesh overview

• Mesh can primarily be divided into: Absorbable or non-absorbable, biological or synthetic
  • Absorbable
    • Biologic mesh
      • Animal
      • Human
    • Synthetic
      • Vicryl
  • Non-Absorbable
    • Synthetic
      • Polypropylene (monofilament
      • Polyester (mono or multi filament)
      • Polytetrafluoroethylene (PTFE) mesh

Absorbable mesh

• Can be either biological or synthetic.

Biological mesh

• Biological grafts are derived from human, bovine, or porcine tissue that has been decellularized to leave a collagen matrix. This structure acts as a regenerative framework that supports remodeling and new collagen deposition.
  • Permacol - porcine derived dermal collagen matrix.
  • Alloderm - is an acellular tissue matrix from donated human dermis.
  • Surgisis - porcine small intestinal submucosa - has since been replaced by Biodesign

Advantages

• Lower risk of infection and can be used in contaminated fields Disadvantages
• Expensive, weaker long-term strength, potential for degradation.

Absorbable synthetic mesh

• Vicryl mesh
  • Completely absorbed between 90-180 days.
  • Does not have to be removed in the setting of infection.
• Phasix (P4HB) ST (with hydrogel barrier)

Non-absorbable mesh

Polypropylene

• Surgipro Mesh and Parietene
• Associated with a vigorous inflammatory reaction which may contribute to chronic pain as well as loss of activity.
• Lightweight, flexible and durable.
• Available in multiple thicknesses and pore size.
• Less prone to degradation

Polyester

• Parietex
  • Medtronic meshs
  • lightweight, macroporous mesh
• Polyester mesh coated with a collagen hydrogel matrix.
• Slightly stiffer and heavier than polypropylene.

PTFE

• Microporous woven mesh that was originally used in vascular grafts.
• The material used in abdominal cases generally has two sides—one side is smooth with small pores, the other has larger pores with ridges and groves.
• The material is designed to place the smooth side toward the bowel to minimize adhesions, and the rough side toward the fascia to allow for tissue ingrowth.
• However, experimental studies have shown limited ingrowth of fibers and minimal inflammatory changes surrounding ePTFE grafts.
• High rates of seroma formation

Composite meshes

• Have two layers
• The protective layer has omega 3, regenerated cellulose, collagen hydrogels, or monocryl.
• They require hydration prior to use and should not be cut.
• Benefits include that they can be used intra-peritoneally.
• Symbotex mesh
  • Polyester
  • Absorbable film of collagen from porcine origin and glycerol. The collagen film is essentially degraded in less than 1 month
• Ventral Patch
  • Parietex - Polyester
  • Hydrophilic absorbable collagen film

Ideal mesh

1. Good tensile strength.
2. Easy to manipulate
3. Durable.
4. Good degree of tissue ingrowth
5. Chemically and biologically inert
6. Non-carcinogenic.
7. Resistant to bacteria.
8. Sterilizable.
9. Low cost.
10. Limited contraction.

Properties of mesh

• Absorbability
  • Absorbable
    • can be used in clean-contaminated or contaminated fields, often a material safe to use against viscera
    • Non-absorbable
      • permanent tissue support
• Porosity
  • Macro porous - increases ingrowth, better integration, with lower risk of infection.
  • Microporous - Doesn’t allow tissue ingrowth which can be advantage in decreasing adhesions e.g. against bowel. But has a higher rate of infection.
• Weight
  • Light increases flexibility, decreases shrinkage and decreases risk of infection
  • Heavy - increases tensile strength.
• Filament
  • Monofiliment
    • reduced infection risk, typically easier to cut and shape, less prone to shrinkage and better tissue intergration
    • typically softer and more pliable, increased surface area can encourage rapid tissue ingrowth
• Self-fixation mesh
  • Has barbs or hooks that adhere to tissues without sutures or tacks.

Preferred mesh should be lightweight <80g/m2, large pore > 1 mm and microporous > 10 μm (if too small, bacteria will hide from larger inflammatory cells). Porosity should be at least 60%.