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Corporate Documents, Expert Witnesses Take Center Stage in First Federal Vaginal Mesh Trial

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Dr. Anthony Brennan - Professor of Materials Science and Engineering & Biomedical Engineering at UF

By Doug Allen

CHARLESTON, W.Va. – Attorneys for the plaintiff continued to lay the scientific foundation for their case Friday in the first federal trial regarding transvaginal mesh devices, while a videotaped deposition of a C.R. Bard Inc. employee suggested the company knew of a flaw in the Avaulta Plus long before it pulled the product from the market.

Judge Joseph R. Goodwin and a jury of eight began hearing testimony a week ago in Cisson v. C.R. Bard Inc. Plaintiff Donna Cisson claims an Avaulta Plus product caused her permanent injury after it was implanted to treat pelvic organ prolapse. It’s the first of more than 23,000 transvaginal mesh cases that have been combined in the U.S. District Court for the Southern District of West Virginia, in Charleston.

The Avaulta Plus is a synthetic mesh product, made from a material called polypropylene. The Material Safety Data Sheet for polypropylene presented in court last week indicates it is not safe for permanent implantation in the human body.

Bard voluntarily stopped selling the Avaulta line of products in July 2012 rather than meet U.S. Food and Drug Administration (FDA) requirements for further clinical testing. Goodwin has excluded this information from the trial.

Bard Patent Application Acknowledged Complications from Mesh

During the fifth day of testimony, a videotaped deposition of Bard engineer and team leader Douglas Evans, taken on Aug. 17, 2012, was shown to the court. In it, plaintiff attorney Henry Garrard questioned Evans about a patent application bearing his name and signature on behalf of Bard, dated June 14, 2002.

The application sought a patent to create a sling-type product from a natural biological material. In the background section of the application, Bard outlined the rationale for the new patent by describing the limitations of synthetic mesh devices made from materials like polypropylene.

In the video, Garrard read the section in question aloud: “‘Although some doctors are satisfied with the results they’ve achieved with synthetic sling kits, some doctors prefer not to use them due to potential infection, urethral or vaginal wall erosion because the mesh … (can) unravel, creating a fishing line effect, slicing through the patient’s tissue.’”

“Did you ever say to your boss,” Garrard continued, “‘Boss, if it’s known that synthetic mesh sling kits might unravel (and) create a fishing line effect, I don’t think we ought to be selling this product’? Did you ever do that?”

“I don’t recall a specific conversation on that,” Evans replied after a nearly one-minute pause.

‘This Was a Bad Design’

Anthony Brennan, Ph.D., took the stand for three and a half hours Friday. Brennan is a professor of Materials Science and Engineering and Biomedical Engineering at the University of Florida in Gainesville.

Recognized by the court as an expert witness, Brennan studies how cells interact with materials. He said his research is funded primarily by the U.S. Department of Defense, and has been featured on the Discovery Channel and “Nova.”

Brennan and his team studied the Avaulta Plus product for more than two years at the request of attorneys for the plaintiff, who paid him around $200,000 for his work. After reading and evaluating the literature related to the product, he said he had doubts about it.

“I first thought that, biomechanically, this was a bad design,” Brennan said.

He explained that polypropylene is a polymer made with free radicals, which he told jurors to think of like a rubber tire that gets old and cracks. Once implanted, free radicals produced by the body break down the material.

“When you put an implant in, it’s seen as a foreign body,” Brennan said. “The body will try to encapsulate it. … The problem is it continues forming an inflammatory response. If you use free radicals to make it, you use free radicals to break it down.”

Defense attorney Michael Nicodema continuously objected during this section of Brennan’s testimony. Goodwin had previously ruled that, as Brennan was not a medical doctor, he could not testify about certain medical issues.

But due to Brennan’s expertise in materials science and biomedical engineering, Goodwin overruled Nicodema’s objections and allowed the testimony. Goodwin explained to the jurors that they should listen to Brennan’s testimony in that context.

Plaintiff attorney Jim Matthews asked Brennan if polypropylene degrades when implanted in the human body.

“Yes,” Brennan said. “Polypropylene degrades in the body.”

“Does that include Avaulta Plus polypropylene mesh?” Matthews asked.

“Yes,” Brennan said.

Pore Size Affects Performance

The Avaulta Plus device has a design feature called “arms,” or long, narrow strands of mesh that protrude from the “body” of the device. The arms are intended to help anchor the device in place once implanted.

The mesh contains many pores by design. Brennan said the pores need to be large enough for the body to create a scab through them, holding the arms and the entire device in place. He said the pore size should be between 2mm and 3.5mm.

When Brennan measured the pore size in Avaulta Plus, he found the pores were too small. He also said the practice of rolling the arms during the implantation surgery created an overlap in the material, ultimately deforming the pores.

“If you are deforming the pores, you’re reducing their size and making it more difficult for tissue to grow in, fill it in,” Brennan said.

Cutting Arms Increases Material Degradation

Previous testimony disclosed it was common practice for surgeons to cut the arms on the Avaulta device during implantation to customize it to a patient’s body. Brennan testified that cutting the arms affects the device’s biomedical properties.

“When you cut something, you weaken it,” Brennan said. “If you cut a notch in a cloth, it weakens. Anytime you take a polymer fiber and cut it, it’s going to further exasperate the problem of polymer degradation. … Those loose ends are places where degradation will start.”

Brennan said that the overall design of the Avaulta Plus was flawed from the beginning.

“The geometry of that mesh and material it’s made of is a poor design,” he said. “Your pore sizes are so small … you’re going to get degradation of polypropylene. We’ve known that from the literature for years. … Once degradation of a medical device begins, it’s like a cascade effect. It just continues and keeps going.”

Doug Allen is a freelance reporter based in Aspen, Colo. His work has appeared in local and national print and radio outlets, including The Washington Post and Aspen Public Radio.

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