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Making Sense of the New Hernia Meshes
What are the qualities you should seek out ??? and be wary of ??? when looking into the new options for hernia repair?
Nathan Hall
Publish Date: October 10, 2007   |  Tags:   General Surgery

Reading the choices for hernia meshes aloud is enough to make your lips pucker: Plug or patch? Polyester, polypropylene or PTFE? Proceed, Prolene, ProLite or UltraPro? You'll probably need to take a drink before going on to talk about coatings and other features. By some estimates, more than 120 hernia meshes are on the market. Picking the few types that you'll stock may come down to knowing what to say to surgeons who insist on a particular brand. Here's advice from the experts we consulted.

Better than the others
There may be clinical consensus for what sorts of meshes are better for certain types of hernias, but when it comes to the "best" features, a dozen surgeons will probably give a dozen different answers. "When you ask if there's a best mesh, I don't think anybody could say that," says Guy Voeller, MD, FACS, professor of surgery at the University of Tennessee Health Science Center in Memphis and president of the American Hernia Society. "They all have their uses, their own proponents, and surgeons have their own individual preferences."

Some of the features you'll have to sort through:

  • Materials. What the mesh is made from and whether it's a single material or a combination (see "Why So Many Meshes?" on page 54). are key factors in determining how heavy or light the mesh will be as well as how supple and strong it is.
  • Coating. Many of the newer patches have an extra layer of material, which may be bioabsorbable to facilitate healing. There are some data indicating that this is effective.1
  • Shape. Some physicians may prefer the newer 3-D plugs to the traditional flat-sheet meshes, but there is little data proving that one is more effective than the other, and one comparison found that plugs seem to cause more complications.2
  • Weight. The AHS is advocating that surgeons move away from heavier meshes and to the lighter ones, says Dr. Voeller. "The data show that the heavier weight polypropylene meshes cause more chronic pain, and this is due to the amount of scarring and contracture and stiffening of the mesh," he says. "This is true no matter where the mesh is used."

Before the arrival of composite meshes with a laminar membrane on one side, there really wasn't much worth mentioning since the development of polypropylene monofilament, says Parviz Amid, MD, FACS, FRCS, clinical professor of surgery and director of the Lichtenstein Hernia Institute at UCLA and a founding member and past president of the AHS. The laminar membrane is useful when the mesh has to be placed near the bowel, as it can prevent the growth of mesh into the intestine, which can result in intestinal fistula, says Dr. Amid.

The Reading Hospital Surgicenter at Spring Ridge in Wyomissing, Pa., typically has seven different types of mesh ready for its surgeons and several different sizes for most of these, says assistant director Theresa Snyder, RN, CNOR. To figure out which ones were the best choices for her facility, she picked her surgeons' brains about mesh. Even though some had specific preferences or were excited about something they'd just seen at a conference, Ms. Snyder asked the surgeons to focus on the attributes they really found important. These were:

Why So Many Meshes?

Hernia repair may be one of the oldest operations in the history of surgery, but there was little development in this procedure after suturing the hernia shut became standard. When surgeons realized how common this procedure was and that the failure rate was as high as 35 percent, though, they began looking for new options. In the late 1950s to early 1960s, polypropylene monofilament'mesh became available for hernia repair. Polytetrafluoro-ethylene, also known as PTFE or Gore-Tex, became a source for hernia material in the early '80s, but it wasn't until laparoscopic surgery made hernia repair quick and easy that the industry began to see a flood of devices come onto the market. Manufacturers put out their own variations of polypropylene, composites that combine materials and coatings.

"The industry is taking advantage of the need for mesh to repair hernias because mesh, by itself, has no patent," says Parviz Amid, MD, FACS, FRCS, a clinical professor of surgery and the director of the Lichtenstein Hernia Institute at UCLA. "Any company can make a mesh, and as a result there is competition."

- Nathan Hall

  • Transparency. Some surgeons find it helpful to see through the mesh while they place it.
  • Permanency. Some meshes are backed by studies that show lower recurrence rates.
  • Type. Laparoscopic procedures use different meshes than open procedures. For example, the Gore Bioabsorbable Hernia Plug can be inserted by a laparoscope to treat groin, umbilical or abdominal hernias, while Ethicon's UltraPro Mesh is made for open surgery treatments of inguinal hernias.
  • Composition. Many of the surgeons at Ms. Snyder's facility say they prefer polypropylene due to their personal experiences and training.

In addition to the assortment needed to treat its patient population, Ms. Snyder says her facility also has a newer mesh with tabs designed for treating umbilical hernias. "It's a very nice product, but also very pricey," she says. "We keep it on hand, but we try to have our surgeons be very selective about when they use it."

Beware of "meshoma"
Once you take into account surgeons' preferences, you have to consider their dislikes. The relative newness of many meshes means there is little research confirming the benefits to some of the new designs, but there is some emerging data that some types may present greater risks than others.

One example of a mesh that causes problems, says Dr. Amid, are the variety of hernia devices or systems that contain a 3-D component which is commonly referred to as a "plug." After these are implanted, Dr. Amid says they tend to solidify and become a hard and abrasive ball of mesh, which can cause chronic pain. According to the literature, one in 20 patients who've had their hernias repaired with plugs have required removal of the devices.2 What happens with these 3-D meshes is similar to what happens to 2-D meshes that aren't fixed properly: They begin to develop wrinkles. Over time, the mesh begins to fold in on itself until it becomes a solid ball that Dr. Amid refers to as a "meshoma."3

"The mesh is no longer a very soft foreign body - it is now as hard as bone or wood," says Dr. Amid. "The sheer mechanical pressure can cause chronic pain, and if the meshoma is close to an organ, such as the bladder, bowel or colon, it can erode into that structure. This can create a hole that can cause serious complications."

To keep a flat mesh from becoming a meshoma, says Dr. Amid, it's important to make sure it's properly secured so it won't wrinkle. And how to keep the 3-D meshes from folding? "That is a good question," he says, because they are meshomas to begin with. It's worth keeping an eye on studies comparing the benefits of 3-D devices to flat sheets of mesh.2

Some of the newer plug meshes are designed to avoid this complication by not being permanent. An example is the Gore Bioabsorbable Hernia Plug, a device that resembles a half-circular cluster of straws. It's made from a biocompatible and nonantigenic synthetic co-polymer that acts as a scaffold for tissue regeneration. This device is designed to retain mechanical strength for four to five weeks before it is completely degraded and reabsorbed into the patient's body over a six-month period.

You're probably already aware of the recent recall of the Davol-Bard Composix Kugel Mesh Patch for incisional hernias. This device had a memory recoil ring around its edges to keep it straight so it wouldn't wrinkle and fold in on itself. According to the FDA, the rings in these patches could break under the stress of being placed in the abdomen, resulting in broken wires poking patients and possibly causing bowel ruptures or intestinal fistulas.

There were only about 10 cases of this happening among the thousands of patients who had this device implanted in them, says Dr. Voeller, but he says he frequently sees patients who are concerned about it. "At this point, that's the only mesh we really had a problem with. Some of the other meshes had been reevaluated in the past because they were not working as well as thought, but it was nothing as serious as the Composix Kugel," he says.

Biologic meshes on the horizon
Not only are you likely to see more combinations of mesh materials and coatings, you may see completely new types of meshes in the future.

Researchers are working on biologic meshes, which could be the next big breakthrough in hernia treatment. Here, the mesh is made from tissue taken either from a cadaver or animal, reprocessed until no cells are left and then implanted. It becomes a collagen scaffold that lets the patient's blood vessels grow into it, which in effect would create scar tissue to repair the hernia. It remains to be seen if this will be effective in the long term. "We don't have the data to say right now, and we won't have it for some time," says Dr. Voeller.

The thought of meshes that are treated with a medicated coating strikes Dr. Amid as something that could have some benefit in the distant future. "Growth factors or other substances can be placed on the mesh, and if something can be found that can at least locally alter the metabolic defect and result in formation of tissue or scar tissue that does not have bad collagen and only has good collagen, that would be a major breakthrough," he says. Although there have been some early studies in this area, Dr. Amid says the actual application is still far from the market.

References:
1. Gonzalez R, et al. Resistance to adhesion formation: A comparative study of treated and untreated mesh products placed in the abdominal cavity. Hernia 2004;8:213-9.
2. Kingsnorth AN, et al. Prospective double-blind randomized study comparing Perfix plug-and-patch with Lichenstein patch in inguinal hernia repair: one year quality of life results. Hernia 2000;4:255-8.
3. Amid PK. Radiologic images of Meshoma. Arch Surg. 2004;139:1297-8.

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