By Christina Frangou
Washington—Newer-generation permanent synthetic meshes were associated with significantly reduced short-term frequencies of surgical site occurrences and hernia recurrences compared with biologic meshes for open ventral hernia repairs in clean-contaminated and contaminated surgical sites, according to research presented at the 2013 Clinical Congress of the American College of Surgeons.
The report comes from the first prospective, observational cohort study comparing the effectiveness of permanent synthetic mesh and biologic mesh reinforcement in these difficult cases.
The authors, who are experts in hernia repair, stress that the study is observational: Cases were not matched and follow-up was considerably shorter in the synthetic mesh group. But the results support those from other studies that demonstrate the safety and effectiveness of synthetic mesh in clean-contaminated and contaminated surgical sites (J Am Coll Surg 2013;217:991-998; Trials 2012;13:226; World J Surg 2010;34:1637-1640).
“These observational data indicate that in the hands of surgeons with expertise and experience in abdominal wall reconstruction, one can achieve equivalent if not better short-term outcomes with lightweight, macroporous, permanent synthetic mesh compared with biologic mesh in clean-contaminated or contaminated open ventral hernia repairs,” said lead author Jaime A. Cavallo, MD, MPHS, a surgical research scholar at Washington University in St. Louis.
Investigators compared outcomes for 89 patients who underwent repair with biologic mesh and 111 who underwent repairs with permanent synthetic mesh, between 2007 and 2013 at two medical centers.
Surgical site occurrences were reported more often after repair with biologic mesh than synthetic mesh (46.07% vs. 29.73%; P=0.0173). Surgical site occurrences requiring procedural intervention were also higher in the biologic mesh group (17.95% vs. 9.01%; P=0.0615), although the difference was not statistically significant.
The durability of biologic mesh remains a topic for discussion. Long-term studies have reported recurrence rates in the range of 50% with biologic mesh. In this study, 29.21% of patients who received a biologic mesh implant developed a recurrence, with a mean follow-up of 19.98 months. In comparison, 7.21% of patients who received a permanent synthetic mesh had a recurrence, but the follow-up period of this group was considerably shorter at only 7.96 months.
The differences in follow-up make it impossible to compare long-term recurrence between the two styles of mesh. Centers for Disease Control and Prevention (CDC) measures require follow-up of at least one year to identify synthetic mesh infection, noted B. Todd Heniford, MD, professor of surgery and chief of gastrointestinal and minimally invasive surgery, Carolinas Medical Center, Charlotte, N.C.
“This is an excellent start, but I do have concerns that this study is short term and there could be the potential for selection bias in the choice of a lightweight synthetic mesh versus a biologic mesh. In the context of complicated patients, you would expect surgeons to frequently choose a biologic mesh,” Dr. Heniford said.
He added that the study does demonstrate that the current philosophy that synthetic mesh should only be used in truly clean cases “needs to be challenged.”
“Perhaps this study is telling us something about biologic mesh, inferring a higher rate of wound complications because of its processing, sterilization or other properties. We also know that one biologic implant does not behave identically to another. The answers to these questions are important and need to be answered in a randomized, prospective study.”
Synthetic meshes currently being used differ greatly from those used 15 years ago. Current synthetic meshes are lightweight, wide-pore monofilament meshes, which are less prone to infection than the heavyweight, close-knit meshes of the 1990s. Animal data show these meshes are more resistant to bacterial colonization and bacterial clearance. Unlike earlier-generation synthetic meshes, some studies have demonstrated that the newer meshes can be salvaged following contamination. Synthetic meshes also cost considerably less than biologics.
These developments have led to the reevaluation of the role of permanent synthetic mesh for open ventral hernia repair in clean-contaminated and contaminated surgical sites.
In this study, four surgeons from University Hospitals Case Medical Center, Cleveland, and Greenville Health System University Medical Center, Greenville, S.C., completed the repairs. Patients were well matched in terms of age, body mass index and CDC wound class. Synthetic meshes were placed more often in a retrorectus position (91.89% vs. 67.42%) and less often in the intraperitoneal space (1.08% vs. 31.48%).
To further investigate these findings, the authors are currently conducting a multicenter, prospective randomized trial of biologic versus permanent synthetic mesh in clean-contaminated and contaminated ventral hernia repairs under appropriate FDA Investigational Device Exemptions (ClinicalTrials.gov NCT01746316).