The original Parietex was introduced to the market in 1999 and was a non-coated mesh. The original Parietex had many weaknesses and design defects, which Covidien has attempted to fix in later versions of the Parietex. No human trials were conducted with the Parietex hernia mesh before it was sold.
History of the Case
Parietex Design Defects
The original Parietex hernia mesh was made of heavy-weight Polyester, which causes many complications similar to polypropylene, but also has some additional weaknesses. Unlike polypropylene which is stiffer and can keep its shape, polyester is soft and flimsy. Many surgeons reported problems with being able to properly manipulate the Parietex during implantation. In an attempt to rectify this problem, Covidien added a collagen layer to subsequent versions of the Parietex, such as the Parietex Composite and the Parietex ProGrip. In 2009, Covidien came out with the Parietex monofilament polyester mesh, which is made from a light-weight polyester. However, the light-weigh version of the Parietex continues to cause high rates of complications.
Most hernia meshes on the market have some sort of a sealed or smooth edge. However the Parietex has an unsealed edge, exposing the end of hundreds of polyester fibers. After implantation, these polyester fibers become much harder and can perforate the bowel or other underlying organs. Not having a sealed edge also increases the ability of the individual polyester fibers to fray and unravel. Once the Parietex begins to unravel, it becomes even more susceptible to tearing away from the tacks or sutures securing it. As the Parietex frays and unravels, small polyester fibers break away from the mesh. These small polyester fibers then travel throughout the body and become embed in other tissue. Each individual polyester fiber then chronically incites its own inflammatory response. Covidien decided to keep the unsealed edges on both the Parietex Composite and the Parietex ProGrip.
Prone to Tearing
Covidien’s Parietex hernia mesh shrinks and contracts to a significant degree after it is implanted. The polyester fibers that create the Parietex are weaker than the titanium tacks or polypropylene sutures used to secure the mesh. Because of this, the polyester fibers will tear on the securing tacks or sutures after tension increases due to the Parietex contracting. Once the mesh tears, the patient re-herniates and the Parietex can migrate or ball up. Covidien’s solution to the tearing was the Parietex ProGrip, to which they added thousands of “micro-hooks” so that sutures or tacks wouldn’t be needed to secure the mesh.
Parietex Composite Hernia Mesh
In the late 90’s Covidien set itself apart from other hernia mesh manufacturers and gained a foothold in the market by focusing primarily on creating hernia meshes out of polyester instead of polypropylene. However, by the early 2000’s Covidien faced two challenges in maintaining its market share. First, Covidien’s polyester mesh was more difficult for surgeons to handle than the feasible available alternative hernia meshes. Second, the manufacturers of polypropylene based hernia meshes had started applying coatings to their meshes so that they could be inserted easily via laparoscopic surgeries and placed close to the bowel. Covidien then added a thin collagen film to the Parietex and called the new mesh the Parietex Composite. The collagen film improved handling of the Parietex Composite, but failed miserably at protecting a patient’s bowel from the polyester. After implantation, the collagen film quickly disintegrates and exposes bare polyester to any underlying organs. Infections and dense adhesions to the bowel resulting in bowel obstructions are common with the Parietex Composite. No human trials were conducted with the Parietex Composite before it was sold. Learn more at our Parietex Composite Lawsuit page.
Covidien continued to be plagued by its polyester based hernia meshes tearing on tacks and sutures, because polyester meshes contract. The underlying problem with the Parietex mesh line is that it contracts, not that it tears on sutures and tacks. The Parietex tearing is a result of the mesh contracting. Covidien should have recalled the entire Parietex mesh line, because there is nothing that can be done to fix the underlying defect of the Parietex shrinking over time. However, Covidien decided they could continue making money on the Parietex mesh line if they fixed the “problem” of the mesh tearing on tacks or sutures. Covidien’s patchwork solution was to attach thousands of “micro-grips” to the polyester to create the Parietex ProGrip. While Covidien’s solution does alleviate the need to use sutures or tacks, it doesn’t solve the underlying problem of mesh contraction. The Parietex ProGrip’s 5,000 Velcro-like micro-grips all hook securely into a patient’s underlying tissue. If 5,000 micro-grips in the groin isn’t painful enough, the Parietex will then start to contract, pulling and stretching the underlying tissue from 5,000 points of attachment. The pain is absolutely debilitating. Oh, and here’s there kicker, it’s attached in 5,000 spots so it’s nearly impossible to remove. To explant the ProGrip, it has to be cut out in little pieces along with all the underlying tissue. It typically takes several operations just to get a majority of the ProGrip removed. No human trials were conducted with the Parietex ProGrip before it was sold. Learn more at our Parietex ProGrip Lawsuit page.
Injuries Related To Product
- Severe or chronic pain
- Serious infection
- Mesh shrinkage
- Mesh migration
- Organ perforation
- Bowel obstruction
- Bowel adhesion
- Hernia recurrence
Apr 2018: Erosion of Polytetrafluoroethylene (Gore-Tex) Sling Over 20 Years After Placement for Stress Urinary Incontinence.
A Gore-tex ePTFE mesh eroded through tissue 21 years after placement.
Dec 2013: An In Vitro Study Assessing the Effect of Mesh Morphology and Suture Fixation on Bacterial Adherence.
Unocated ePTFE mesh was found to have the greatest bacterial adherence compared to any of the other meshes studied. “It was unclear whether the increased filament diameter or the small pore size of DualMesh was accountable for the increased bacterial adherence rather than the ePTFE polymer itself. Taking into account the combined results of this study, it is likely that the increased prostheticload from a reduced pore size and increased mesh thickness had a relatively greater contribution than the ePTFE polymer. In the clinical setting, several studies have shown that ePTFE is more susceptible to infection than other biomaterials, and that when infection occurs, most ePTFE implants will need to be removed. However, once again, it is probably the small pores and increased mesh thickness observed with ePTFE prosthetics that account for these results.”
Sept 2012: Biomechanical and Histological Evaluation of Abdominal Wall Compliance with Intraperitoneal Onlay Mesh Implants in Rabbits: A comparison of Six Different State-of-the-Art Meshes.
The authors found that “significant shrinkage was seen in Gore DualMesh.”
June 2012: Does Expanded Polytetrafluoroethylene Mesh Really Shrink After Laparoscopic Ventral Hernia Repair?
The authors of the study found that the DualMesh Plus (ePTFE) shrunk between 2.6% and 25% in 16 patients implanted with the DualMesh. Seromas were also observed in approximately 8% of patients implanted with the DualMesh.
June 2009: The Problem of Mesh Shrinkage in Laparoscopic Incisional Hernia Repair
A literature search was conducted and found eleven experimental and 3 clinical studies published data referring to shrinkage of intraperitoneally placed meshes. ePTFE meshes, such as the DualMesh were found to shrink up to 51%. The author noted that the surgeon would have to anticipate significant mesh shrinkage in laparoscopic hernia repair. Gore does not warn surgeons that they will experience significant mesh shrinkage with the DualMesh.
Apr 2009: Erosion of a composite PTFE/ePTFE mesh after hiatal hernia repair.
Case report of an 80-year-old women who experienced erosion with an ePTFE hernia mesh. The author concluded that “mesh erosion is a rarely reported complication after hiatal hernia repair, and because many cases will go unreported, their true incidence is unknown. Besides the durability of mesh repair, the ongoing clinical trials investigating laparoscopic correction of hiatal hernias should also focus on the risk of complications associated with the use of prosthetic materials and the mode of fixation.”
Apr 2008: Rejection of Goretex Mesh Used in Prosthetic Cruroplasty: A Case Series.
Three patients underwent hiatal hernia repair utilizing a Gore-Tex (ePTFE) mesh. After 7, 12, and 34 months each of the cases presented with dysphagia. In all three cases initial endoscopy revealed narrowing at the lower end of the esophagus, with inflammatory changes and erosion. In two cases, the mesh was noted to have eroded into the distal esophagus, and in the third case relaparoscopy showed a peri-esophageal collection including the mesh surrounded with fibrosis. The authors concluded that Gore-Tex should be used with great caution in the peri-esophageal region, despite the fact that Gore-Tex (ePTFE) is currently being recommended as one of the choice materials for the prosthetic reconstruction of the hiatus.
June 2007: Management of Infections of Polytetrafluoroethylene-Based Mesh.
The authors conducted a study to determine a protocol for salvaging infected ePTFE mesh after many had advocated a mandatory removal of infected ePTFE mesh. Removal of the infected ePTFE meshes were noted as the cause of high hernia recurrence rates. 22 patients were treated for ePTFE mesh related infections, with an onset between 10 and 480 days. The authors concluded that “infections of ePTFE-based mesh can present in early or delayed fashion. Although mesh with extensive infection could not be salvaged, limited mesh infections could be managed successfully with percutaneous or open drainage and prolonged antibiotic courses.”
June 2007: Comparative Evaluation of Adhesion Formation, Strength of Ingrowth, and Textile Properties of Prosthetic Meshes After Long-Term Intra-Abdominal Implantation in a Rabbit.
The authors of the study found that “prosthetic shrinkage was greatest in the ePTFE (32%) group than in any other group.”
Sept 2006: Prospective Evaluation of Adhesion Formation and Shrinkage of Intra-abdominal Prosthetics in a Rabbit Model.
The authors of the study noted that “laparoscopic ventral hernia repair requires an intraperitoneal prosthetic; however, these materials are not without consequences.” It was found that “Overall prosthetic shrinkage was statistically greater for DualMesh (34.7%) than for the remaining mesh types.”
Apr 2004: Tissue Integration and Biomechanical Behaviour of Contaminated Experimental Polypropylene and expanded Polytetrafluoroethylene Implants.
ePTFE implants infected with S. aureus showed “zones of erosion, disorganized tissue, haemorrhage and necrosis.” Integration with host tissue was also impacted when ePTFE was infected with s. aureus.
May 2000: Ultrastructural Alterations of Polytetrafluoroethylene Prostheses Implanted in Abdominal Wall Provoked by Infection: Clinical and Experimental Study.
Explanted infected ePTFE meshes were compared to explanted non-infected ePTFE meshes. Examination of the explanted infected ePTFE meshes revealed alterations to teh ePTFE structure, such as areas of fragmentation, fracture lines, and detachment of fine layers of ePTFE that harbored numerous Staphylococcus colonies. The contaminated implants were also observed to be arranged more loosely, and on occasion large spaces between fibers gave rise to an unknitted appearance. It was concluded that “irreversible changes to the structure of the prosthesis are produced owing to colonization of the biomaterial by microorganisms, which in most cases necessitates total replacement of the prosthesis.
Jan 1993: Expanded Polytetrafluoroethylene Patch Versus Polypropylene Mesh for the Repair of Contaminated Defects of the Abdominal Wall.
An ePTFE patch was utilized to repair contaminated defects in 21 rats. Wound infection occurred in 16 rats, two of which died due to infection related complications. It was concluded that “expanded PTFE is unsuitable for the reconstruction of contaminated abdominal wall defects.”