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Is Hernia Mesh Safe?

What is it anyway?

Absolutely yes! Mesh is very safe and we use it every day.

Use of hernia mesh is safe and very effective.

 

What is mesh? 

What is it made of?

Are you going to use that recalled mesh I see on the TV commercials from law firms?

What happens if my body "rejects" the mesh?

Will I set off metal detectors?

What's the rationale, can't you just close the hole?

What mesh will you use for a hernia repair?

Well, those are a lot of questions... Let's try to clear them up.

Perhaps we should start at the beginning.... What is mesh and why do we use it?

As noted in the "Tissue vs Mesh repair" and "Is it necessary to use mesh?" sections, mesh is man-made sheet of material used to reinforce or strengthen weak tissue for the purposes of providing a "durable" (long-lasting) repair of a hernia. Some hernias cannot even be effectively repaired without it. 

But what is it really?

 

Well, the mainstay of our repairs for the last few decades has been, for lack of a better description, "permanent plastic materials" of a sort.  There are three main materials that most of our present meshes are built from right now.

Without giving you a chemistry lesson, these are the big three:

  • Polypropylene

  • Polyester

  • Polytetrafluoroethylene (PTFE)

As mentioned in other sections, there has been an explosion in the engineering of mesh in the last 10-15 years and the selection of mesh has increased substantially. We'll discuss more about that later.

So "permanent" mesh is a form of high-tech plastic. Permanent means that it lasts forever. It will not degrade, break down, dissolve, or otherwise go away. It is meant to be very strong (to reinforce the repair), but it is also meant to be a scaffold or matrix for your body to lay down fibrin (scar tissue) on and around to make the repair even stronger than your body every could do on its own.

 

So does the mesh need to be permanent? We have recently been studying this question. At this point, we honestly don’t know how long a piece of mesh needs to be present in order to repair a hernia. But if you look at the studies mentioned in the section regarding "Tissue vs Mesh repair," your hernia recurrence rate (chance that it will come back) continues to increase over time, so it does suggest that a permanent material might be what is needed.

But as our thoughts and techniques continue to evolve, things are getting more complicated....

We not only have "permanent" plastic, but we now also have "reabsorbable" plastic.

 

  • These materials are now being combined in different ways with permanent mesh, and we are making absorbable mesh out of these different plastics with different capabilities and characteristics.

We also have "Biologic" materials:

  • These biologic materials are sourced from animals or humans:

    • Xenograft from an animal

    • Allograft from a human

And these "Biologics" come from very different parts of the body, with very different collagen structures and other materials inside.

So as far as the big three plastics:

Polypropylene has always been the standard for hernia mesh (it still is) and has been the model for other meshes. Polypropylene (PP) is a thermoplastic “addition polymer” made from the combination of propylene monomers. It is used in a variety of applications to include packaging for consumer products, plastic parts for various industries including the automotive industry, special devices like living hinges, textiles, and you guessed it... the surgical implant industry. 

Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Polyesters have evolved tremendously over the years, and now comes in multifilament and monofilament versions (Multiple strands (like cables) in different patterns that make of the sheet, or single strands).

 

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene and is most commonly known as "Gore-Tex". Being hydrophobic, non-wetting, high density and resistant to high temperatures, PTFE is an incredibly versatile material with a wide variety of applications, though it's perhaps best-known for its non-stick properties.

  • it can be "extruded" in multiple different ways

  • it can be a solid sheet with no pores, can be solid filaments, or can be this “expanded” version that we most commonly use, which is microporous (3 micron pores) on one side and macroporous (17 micron pores) on the other side.

We have so many different types of mesh now, and each one can have many different characteristics

Different characteristics of the mesh that we look at, and are studying:

  • Openings between the filaments (pores) and their sizes

  • Diameter of the individual filaments that make up the mesh and how they are put together (some are woven together, some are knitted, some are monofilament, some are dual, and some are multifilament.

  • Thickness of the mesh

  • Density - the amount of actual foreign body

Here you can see an example of different sheets of polypropylene mesh made by different companies. You can see many of the various characteristics I mentioned.

Picture of various meshes.jpg

Deeken CR, Abdo MS, Frisella MM, Matthews BD. Physicomechanical evaluation of polypropylene, polyester, and polytetrafluoroethylene meshes for inguinal hernia repair. J Am Coll Surg. 2011 Jan;212(1):68-79. doi: 10.1016/j.jamcollsurg.2010.09.012. Epub 2010 Nov 5. PMID: 21115372.

 

So now you have an idea of some of the different materials we have to work with, now we have to look at their different properties and characteristics. What the engineers work on and study are things like: 

  • Ball burst strength (how strong before they break)

  • Elasticity (How much give do they have)

  • Anisotropicity (how and how much they stretch in a given direction)

  • Tear resistance (How easy to tear)

  • Suture retention strength (How well do they hold stitches)

Examples:

Table of Hernia Mesh Properties.PNG

Will you reject the mesh?

Well, any foreign material that is placed in your body will illicit what's called a "Foreign Body Response." This reaction is a natural response of your immune system when it recognizes something that is, well frankly, not you. We place foreign bodies, in the form of implants, in people every singles day. Artificial implants range from fillings in your teeth, to pacemakers and defibrillators, artificial hips or knees, breast implants, vascular (blood vessel grafts), heart stents, sutures (stitches), and oh yes.... surgical mesh.

And we know that the amount of foreign body we implant has a direct effect on the amount of response. The more we put in, the greater the foreign body response. The more foreign material you’ve got, the more response, the more scar tissue. So, in terms of mesh, what we aim to do is to use the least amount possible to get the best results we can get. This is why we have been steadily engineering better materials, with lower density, lower weight, less thickness, very strong, and just the right amount of stretch (some, but not too much). Needless to say, this is a daunting task. The human body is an amazing thing.

 

So when a patient asks if they are going to reject the mesh, I tell them yes, to a degree, but that I am going to use the least amount of foreign body that I believe you need to have a good repair. 

 

And, as stated earlier, these products change... and frequently.

So currently in our arsenal we have all of these types (and in a large variety of sizes):

  • Synthetic Permanent Mesh

    • which have different options:
      • uncoated

      • coated

      • heavy weight

      • mid weight

      • light weight

      • macroporous

      • microporous ​

  • Synthetic Partially Absorbable Mesh (Hybrid, part permanent, part absorbable)

  • Biosynthetic Completely Absorbable Mesh

  • Biosynthetic Partially Absorbable Mesh (Hybrid)

  • Biologic

  • Biologic-derived Partially Absorbable Mesh (Hybrid)

  • Biologic Antibiotic Impregnated Mesh. 

So it is vitally important for the hernia surgeon to have an understanding of the characteristics of the mesh he uses. Choosing a specific one on purpose, is important.

To make the task of choosing mesh even more complicated, many manufacturers of surgical mesh manufacture each type of mesh, and often with their own twist of science for each one. And they each have a cadre of scientific studies to show that their mesh is better than those of each member of the competition.

 

If you would like to learn more, give us a call or come and see us at Advanced Hernia Specialists. Call at 904-808-5658 or email us, use our online Contact Form, or Book Online

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