Mesh

Mesh classification

Materials
- Polyester
  - Composed of polyethylene terephthalate
  - Hydrophilic, heavyweight, macroporous mesh
  - Comparable complication rates to other products when placed in pre-peritoneal space
  - Appropriate for extraperitoneal use
  - Infected polyester mesh generally requires at least partial removal - areas that are well-incorporated at time of removal can be left behind
- Polypropylene
  - Hydrophobic macro-porous mesh
  - Allows the ingrowth of native fibroblasts and incorporation into surrounding fascia
  - Semi-rigid, somewhat flexible, and porous
  - Lightweight polypropylene meshes often have an absorbable component of Vicryl or Monocryl which provides initial handling stability
  - Appropriate for extraperitoneal use
  - Tend to be the best for mesh salvage
- Expanded polytetrafluoroethylene (ePTFE)
  - More expensive
  - Non-adherent to bowel in micro-porous form
  - Can be made in composite-type form - micro-porous on the visceral side and macro-porous on the abdominal wall side to promote tissue ingrowth
  - Impermeable to fluid
  - Not incorporated into native tissue like polypropylene
  - Does not allow skin grafting on top
  - When it is infected, it almost always needs to be removed
- Composite
  - ePTFE on the visceral surface, polypropylene on the abdominal wall surface
    - Variable rates of contraction, so can cause buckling of the mesh
  - There are also combinations of synthetic meshes with biologic coatings

Function
- Largely composed of acellular matrix
- Provide a matrix for neovascularisation and native collagen deposition
- Function best as a fascial reinforcement rather than as a bridge or interposition repair
- Enthusiasm waning for these somewhat - prone to late formation of weaknesses and bulges, and eventual hernia recurrence
Classification
- Source material
- Post-harvesting processing techniques
- Sterilisation techniques
- Materials
  - Human dermis
  - Porcine dermis
  - Bovine fetal dermis
  - Porcine intestine
Brands
- Bio-A
  - 67% PGA and 33% TMC
  - Polyfilament, microporous
  - Expected to absorb in 6-7 months
- Phasix
  - Knitted monofilament mesh scaffold of P4HB (poly-4-hydroxybutyrate)
  - Biologically-derived, fully resorbable in 12-18 months
  - Essentially a polymerised version of butyrate, which means it takes 12-18 months to hydrolyse
- Biodesign grafts including rectopexy
  - Porcine intestinal submucosa scaffold
Indications
- Advantage in infected or contaminated fields - but long-term outcomes questionable here
- Can be used for coverage of viscera as part of a planned hernia with eventual skin graft on top

Monofilament polypropylene flat sheet - 15x10cm
Parietene DS - composite polypropylene and absorbable collagen film. Comes in 12cm or 15cm round, or 15x10/20x15/25x20/30x20cm sizes.
ProGrip - composite polyester and absorbable polylactic acid microgrip
Parietex - composite patch of polyester and absorbable hydrophilic collagen film - comes in 4.6, 6.6 and 8.6 sizes
Symbotex
Ventralex ST - polypropylene with hydrogel posterior layer, for intra-peritoneal placement. Comes in 4.3, 6.4 and 8cm sizes.
Ventralex - polypropylene/ePTFE, for pre-peritoneal placement.
ProLite - polypropylene. ProLite Ultra is low-weight polypropylene.
Bard 3D Max - knitted polypropylene pre-formed mesh
UltraPro - macroporous partially-absorbable - polypropylene/monocryl - monocryl added to make it 'stiffer' and less flimsy - commonly 6x11cm

European Hernia Society Guidelines on use of mesh
Grade 1 - no risk factors for infection or contamination - use whatever you choose
Grade 2 - risk factors for infection but no contamination - whatever you choose, but could consider biologic
Grade 3 - potentially contaminated e.g. stoma, violation of GIT - biologic mesh generally recommended
Grade 4 - infected - biologic