Less is best
Ideally, prosthetic mesh for hernia repair should be strong, lightweight and porous enough for blood vessels to grow through it, which helps stabilize it in the patient's body. Over the years, mesh has improved greatly along these lines. In the past, meshes were over-engineered to be stronger than necessary. The problem is that mesh becomes stiff when you implant it, and patients can feel it if the mesh is made of a material that's too dense. When a mesh becomes too stiff, it can hinder a patient's ability to move.

Another challenge is that polypropylene, the material used in many meshes, causes an intense inflammatory response, resulting in a scar plate. The more implanted mesh, the greater the inflammatory response, which can lead to more connective tissue formed and a greater chance of adhesion to the abdominal wall. The inflammatory response also causes shrinkage of the mesh, which in turn will cause more loss of tissue flexibility.

So less is best when it comes to hernia mesh. Less implanted material will cause less scar tissue, fewer undesired side effects and less post-op discomfort for the patient. To reduce the amount of polypropylene used, companies have decreased the weight of the mesh by reducing the density of the filament used and by increasing the pore size.

Sold by weight and by size
Hernia mesh is available in lightweight, midweight and heavyweight formats, based on the weight in grams per square meter. The weight is determined by the density of the filament and size of the pores. Denser filament and smaller pores create a heavier mesh.

• lightweight is 16 to 20 grams per square meter;
• midweight is 35 to 45 grams per square meter; and
• heavyweight is about 100 grams per square meter.

Lightweight mesh with larger pore sizes has been shown to reduce inflammation and improve tissue ingrowth and incorporation into surrounding tissue. In animal studies, lightweight meshes have shown less inflammatory response and less shrinkage.

Besides weight, mesh is also sold by size. Sheets of 4-by-6 inches, the most popular size for inguinal hernias, usually cost between $100 and $200 each and are sold in boxes of 6 sheets. Six-by-8-inch sheets for bilateral hernias are also popular because you can cut the sheet in half and use a single sheet for each side.

Once in place, mesh can be attached to the surrounding tissue with permanent sutures, stainless steel staples or permanent or absorbable tacks. Tacks and staples are applied with a pre-loaded gun. Usually you can negotiate the price of these guns, based on your hernia mesh volume, as part of your contract with the vendor.

Coatings to prevent adhesion
A certain percentage of all mesh implants will have some adhesion to abdominal walls and organs. One way to reduce the chance of adhesion is to coat the filament with a material that will keep the tissue from sticking to it. A coating should be a material that causes the least amount of foreign body reaction and inflammatory response. The implant should be well incorporated by the surrounding tissue. This will reduce adhesions to the bowel, chronic pain, intestinal obstructions and enterocutaneous fistulas.

The material used for coatings depends on the manufacturer. Some manufacturers use cellulose, which creates a resorbable barrier that keeps the tissue from attaching to the abdominal wall. Another coating is omega-3 fatty acid gel. Omega-3 fatty acid helps prevent the inflammatory response because it's a naturally occurring substance in the body. Still other manufacturers coat mesh with titanium because of the metal's inert properties, which is why it's also used for orthopedic implants and surgical instruments. Coated mesh products cost about twice as much as non-coated mesh.

Infection risk
Mesh infections are a problem that frequently requires the removal of the mesh. Infection has also been associated with erosion into adjacent structures, fistulas, chronic pain and the dangers of a second procedure and a hernia recurrence.

Infection is a risk with many implants because when you implant a device, you're adding a surface that can be vulnerable to biofilm development. Bacterial colonization on the surface of the mesh and the pores can cause acute and sometimes delayed or chronic infections. The type of filament used — monofilament vs. multifilament — in the mesh as well as weave, pore size and surface coating may play into the spread of infection. For example, sometimes with multifilament weave, bacteria attaches inside the weave but the macrophages that kill the bacteria often can't reach the bacteria inside the weave.

Your mesh alternatives
Absorbable mesh. Surgeons use absorbable mesh as temporary scaffolding when they need tissue to stay together for a short time. Absorbable mesh, made of polyglycolic acid also used in absorbable sutures, loses its strength after about 90 days. That's why it's often used as a quick fix for trauma cases where the patient will undergo follow-up surgery once his condition has improved.

Biologics. Made from human or porcine dermis, biologic mesh works as a graft that will bind with surrounding tissue. It's well-suited for an infected or contaminated surgical field, such as after a bowel resection. A graft will heal well, even in an infected area, whereas a synthetic mesh implantation may not heal in an infected area because the bacteria often binds to the prosthetic material. Biologic mesh is much more expensive, as much as $3,000 per procedure. It also needs to be refrigerated and has a shelf life.

PTFE. Patches made of polytetrafluoroethylene (PTFE) can also be used for hernia repair. This material has no pores and creates an impervious barrier that is fairly resistant to inflammation, so it causes fewer adhesions. Because a PTFE patch is a solid barrier, it doesn't become incorporated into the surrounding tissue but is encapsulated by the body. Like hernia mesh, PTFE patches are fixed into place with staples, tacks or permanent sutures. Once this material is infected, it must be removed or it will become a permanent source of infection and wound problems.

Many surgeons are loyal to a particular type of hernia mesh because they want to use what has worked for them. It would be difficult to stock a single type of hernia mesh. But you can standardize to a specific class of mesh. For example, work with your surgeons to agree on a single lightweight, large-pore, non-coated mesh and a single lightweight, large-pore, coated mesh. When you're making your choice, also consider the shelf life of the different products.

When you're meeting with mesh vendors, remember that the rep's job is to service and educate the facility and the surgeons who'll be using the products. Look for a rep who can give you quick turnaround if you need a certain type of mesh the next day. Ask about in-service training. Is the rep willing to come to the facility and educate the physicians, nurses and materials managers on the mesh that you'll be using? Finally, ask about the return policy. If the only surgeon who was using a certain mesh stops doing cases at your facility, can you return the unused mesh for a refund or credit?