In a sign that there are way too many surgical meshes out there, SAGES dedicated an entire morning panel to a discussion of the subject titled “The Explosion of Biomaterials for Hernia Repair; What Do I Do?”. The answer, apparently, is: we don’t know. 

We don’t pretend to be experts on mesh placement, and this was a dizzying tour de force. Dr. Bruce Ramshaw presented first, and he touched on the basic principles of surgical meshes. Some of his major points included:

• Polypropylene meshes are the most commonly used now.
• Without meshes, hernias have a 63% incidence of recurrence, whereas meshes lower the rate to 32%.
• Meshes contract a lot, sometimes losing over 80% of their original area, and so they must always be placed with wide margins.
• Meshes sometimes erode through the skin, or into bowel.
• Meshes often change their consistency after implantation and may become extremely rigid (requiring, for example, a 10,000-fold increase in force to bend).
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• Lowering the density, and increasing the porosity, seems to make things better.

Next up was Dr. Brent Matthews, who discussed barrier-coated meshes:

• Laparoscopic hernia repair has lower recurrence and wound morbidity than open procedures, but the intraperitoneal mesh can interact with the abdominal viscera
• Intraperitoneal placement of macroporous bare mesh leads to eventual small bowel resection in 21% of patients
• To avoid this, use absorbable barriers to protect the mesh from the intraperitoneal cavity during healing.
  • Proceed (Ethicon) - barrier is oxidized regenerated cellulose
  • Sepramesh (Genzyme) - barrier is Na hyaluronate and carboxymethylcellulose
  • Parietex (Covidien) - barrier is collagen, glycerol, polyethylene glycol, and water
  • C-Qur (Atrium) - barrier is omega-three fatty acids
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• These take variable times to be excreted completely. The C-Qur takes 90-120 days, while the others take 14-21 days. (Click on the slide below for a larger version — there’s a lot of text.)
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Dr. Scott Roth then took the podium and presented on “Quality of Life with Different Meshes.” Some of his key points were:

• One study found that lightweight and heavyweight polypropylene meshes do not show significant differences in pain or quality of life, although hernia recurrence is more likely with lightweight meshes.
• Another study showed that heavyweight meshes were associated with increased incidence of seromas, hematomas, greater foreign body perception, more weather sensitivity.
• Heavyweight polypropylene meshes contract the most.
• TiMesh, an ultra lightweight mesh, showed lower rates of quality of life deterioration after surgery than standard lightweight or heavyweight
• Coated meshes minimize incidence of adhesions, but the effects on quality of life are unknown.

Next was Dr. Yuri Novitsky, who presented “The Ideal Synthetic Mesh — has it arrived?” (Short answer: no.)

•  The ideal mesh:
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• One problem with heavyweight meshes is that they may reduce the compliance of the abdominal wall. In 43% of patients, they are palpable.
• Lightweight meshes are associated with less scarring, greater compliance of adjacent soft tissues than heavyweight meshes.
• Inflammation markers like Ki-67 and apoptotic cells were higher for heavyweight mesh than for lightweight.
• Heavyweight and lightweight meshes cause no difference in pain in the short term, but in a study of inguinal hernia repairs, heavyweight meshes caused more groin and testicular pain at one year than lightweight meshes. But recurrence was higher with lightweight meshes.

Finally, Dr. Scott Helton talked about biological meshes and their potential advantages.

• A few years ago there were only three biological meshes, but now there are thirteen.
• For six of those meshes there is no published data whatsoever… if you want to learn about them, you have to do so from industry reps, or from the patent office.
• Biological meshes are made of extracellular matrix that contains laminin, entactin, perlecan, and type IV collagen.
• There may be religious objections to these meshes — try telling a Muslim person that you are going to put a piece of pig in him.
• According to the data you’re more likely, however, to get an infection from human cadaveric tissue than from a xenogenic graft.
• There have been concerns about prion disease with bovine grafts, but there is no evidence that this is actually a problem.
• The various kinds of biological meshes have different texture, compliance, thickness, and the way the meshes are handled further modify these factors. Processing steps like UV/gamma irradiation, hydration, oxidation, and so on all influence the mesh.
• Biological meshes have short-term advantages over synthetic meshes: avoid bowel dessication, reduce incidence of fistula (maybe), interact with and help wound healing (faster angiogenesis, accelerated wound contraction).
• There are also theoretical long-term advantages: lower incidence of chronic inflammation, reduce incidence of bowel obstruction, less rigidity, increased compliance.
• Although these are very expensive, costs may be lower in the long run if complications can be avoided.

The bottom line from all of this is that there is no one perfect mesh, and that different situations require different materials. Moreover, even the panelists acknowledged that ultimately the surgeon’s technique makes a much greater impact than the mesh material. So how, exactly, was this a consensus panel?