In Vivo Analysis of the Morphologic Characteristics of Synthetic Mesh to Resist MRSA Adherence

Background

Synthetic mesh has significantly reduced recurrence rates for ventral hernia repair; however, prosthetic mesh infections remain a significant complication. We hypothesized that unique mesh constructs might alter the ability of various synthetic meshes to clear bacterial contamination. To evaluate this, we studied commercially available synthetic meshes ability to clear a bacterial contamination with methicillin resistant Staphylococcus aureus infection.

Methods

Two hundred and eighty-three rats underwent hernia repair with one of nine synthetic materials. Control animals were closed, and the remainder was inoculated with either 10⁴ or 10⁶ methicillin-resistant S. aureus (MRSA). Animals were survived for 30?days without systemic antibiotics. At necropsy, the mesh was harvested and quantitative cultures and bacterial clearance assessed.

Results

All clean repairs remained sterile. Rates of bacterial clearance for 10⁴ repairs revealed that unprotected monofilament materials cleared significantly more bacteria than composite meshes and multifilament meshes (p?=?<0.01 and p?=?0.01, respectively). At higher levels of bacterial contamination (10⁶), all materials had a reduction in bacterial clearance, although monofilament materials had higher bacterial clearance compared to composite meshes (p?=?0.03).

Conclusions

Monofilament unprotected polypropylene and polyester mesh can clear a large percentage of MRSA contaminants. Multifilament, composite anti-adhesive barrier meshes, and laminar antimicrobial impregnated mesh are not able to clear bacterial contamination with MRSA. Unique properties of synthetic material should be considered when evaluating a prosthetic for high-risk incisional hernia repair.     

In-vivo and in-vitro histological evaluation of two commercially available acellular dermal matrices

Purpose  

Post-herniation abdominal wall repair can be performed with synthetic or biologic meshes. Synthetics have been associated with complications, so biologics are promising alternatives. The methods used to decellularize biological matrices may affect the extracellular components. This study evaluated the post-implantation biological response of two allogenic acellular dermal matrices (ADMs) in a hernia model.     

Comparison of a lightweight polypropylene mesh (Optilene® LP) and a large-pore knitted PTFE mesh (GORE® INFINIT® mesh)—Biocompatibility in a standardized endoscopic extraperitoneal hernia model

Purpose  

The use of a mesh with good biocompatibility properties is of decisive importance for the avoidance of recurrences and chronic pain in endoscopic hernia repair surgery. As we know from numerous experiments and clinical experience, large-pore, lightweight polypropylene meshes possess the best biocompatibility. However, large-pore meshes of different polymers may be used as well and might be an alternative solution.     

The comparison of heavyweight mesh and lightweight mesh in an incisional animal model

Purpose  

An incisional hernia may occur through the incision area following a surgical operation, through the trocar opening and even through drainage exit points. Various synthetic surgical meshes have recently been used for the surgical repair of incisional hernias. In this study, we analysed the burst strength forces of heavyweight mesh and lightweight mesh in an incisional animal model.     

What is the evidence for the use of biologic or biosynthetic meshes in abdominal wall reconstruction?

Introduction

Although many surgeons have adopted the use of biologic and biosynthetic meshes in complex abdominal wall hernia repair, others have questioned the use of these products. Criticism is addressed in several review articles on the poor standard of studies reporting on the use of biologic meshes for different abdominal wall repairs. The aim of this consensus review is to conduct an evidence-based analysis of the efficacy of biologic and biosynthetic meshes in predefined clinical situations.

Methods

A European working group, “BioMesh Study Group”, composed of invited surgeons with a special interest in surgical meshes, formulated key questions, and forwarded them for processing in subgroups. In January 2016, a workshop was held in Berlin where the findings were presented, discussed, and voted on for consensus. Findings were set out in writing by the subgroups followed by consensus being reached. For the review, 114 studies and background analyses were used.

Results

The cumulative data regarding biologic mesh under contaminated conditions do not support the claim that it is better than synthetic mesh. Biologic mesh use should be avoided when bridging is needed. In inguinal hernia repair biologic and biosynthetic meshes do not have a clear advantage over the synthetic meshes. For prevention of incisional or parastomal hernias, there is no evidence to support the use of biologic/biosynthetic meshes. In complex abdominal wall hernia repairs (incarcerated hernia, parastomal hernia, infected mesh, open abdomen, enterocutaneous fistula, and component separation technique), biologic and biosynthetic meshes do not provide a superior alternative to synthetic meshes.

Conclusion

The routine use of biologic and biosynthetic meshes cannot be recommended.

     

Parastomal hernia repair outcomes in relation to stoma site with diisocyanate cross-linked acellular porcine dermal collagen mesh

Purpose  

Biologic meshes are increasingly used in parastomal hernia repair. This study evaluates the efficacy and safety of diisocyanate cross-linked acellular porcine dermal collagen mesh for parastomal hernia repair, with particular reference to the relationship of the stoma site to the rectus sheath.     

Systematic review and meta-analysis of the repair of potentially contaminated and contaminated abdominal wall defects

Background

Repair of contaminated abdominal wall defects entails the dilemma of choosing between synthetic material, with its presumed risk of surgical site complications, and biologic material, a costly alternative with questionable durability.

Data sources

Thirty-two studies published between January 1990 and June 2015 on repair of (potentially) contaminated hernias with ≥25 patients were reviewed. Fifteen studies solely described hernia repair with biologic mesh, 6 nonabsorbable synthetic meshes, and 11 described various techniques. Surgical site complications and hernia recurrence rates were evaluated per degree of contamination and mesh type by calculating pooled proportions.

Conclusions

Analysis showed no benefit of biologic over synthetic mesh for repair of potentially contaminated hernias with comparable surgical site complication rates and a hernia recurrence rate of 9% for biologic and 9% for synthetic repair. Biologic mesh repair of contaminated defects showed considerable higher rates of surgical site complications and a hernia recurrence rate of 30%. As only 1 study on synthetic repair of contaminated hernias was available, surgical decision making in the approach of contaminated abdominal wall defects is hampered.     

Evaluation of crosslinked and non-crosslinked biologic prostheses for abdominal hernia repair

Introduction  

Abdominal wall defects and incisional hernias represent a challenging problem. Currently, several commercially available biologic prostheses are used clinically for hernia repair. We compared the performance and efficacy of two non-crosslinked meshes in ventral hernia repair to two crosslinked prostheses in a rodent model.     

Mosquito Net Mesh for Abdominal Wall Hernioplasty: A Comparison of Material Characteristics with Commercial Prosthetics

Background

The use of sterilized mosquito net as a cheaper alternative to commercial mesh used in hernia repair has previously been published. However, as no standards with regard to the material have been documented, we aimed to define the characteristics of a commonly available and low-cost mosquito net, which has already been shown to be clinically efficacious in groin hernia repair. We compared its characteristics to other commercially available meshes, in keeping with the well-established FDA and MHRA regulatory processes.

Methods

The macromolecular structure of the mosquito net was determined by vibrational spectroscopy. The ultrastructure of the meshes was examined with scanning electron microscopy, and uniaxial and burst tensile strength testing was performed. The following parameters were assessed: polymer type, filament characteristics, pore size, weight, linear density, elasticity, and tensile strength.

Results

The mosquito net was a polyethylene homopolymer, knitted from monofilament fibers with a mean filament diameter of 109.7 μm and a mean mesh thickness of 480 μm. The mean pore maximum diameter was 1.9 mm, with 91.2 % porosity, 53.7 g/m² mean mesh weight, and a linear mass density of 152 denier. This was comparable to the “large pore” (class I) commercial meshes. The bursting force for polyethylene mosquito net was greater than for UltraPro and Vypro (43.0 vs. 35.5 and 27.2 N/cm, respectively), and the mosquito net exhibited less anisotropy compared to the commercial meshes.

Conclusions

The material and mechanical properties of the polyethylene mosquito net are substantially equivalent to those of commonly used lightweight commercial meshes.     

Chronic Pain after Laparoscopic Transabdominal Preperitoneal Hernia Repair: A Randomized Comparison of Light and Extralight Titanized Polypropylene Mesh

Background  

The aim of this prospective, randomized, single-blinded clinical trial was to compare the incidence of chronic pain after laparoscopic transabdominal preperitoneal hernia repair (TAPP) using a 35-g/m² titanized polypropylene mesh and a 16-g/m² titanized polypropylene mesh. The reported incidence of chronic pain in patients who underwent laparoscopic hernia repair is a serious problem. The techniques of dissection, mesh fixation, and the mesh material used have all been identified as being part of the problem. Excellent biocompatibility through a unique combination of a lightweight open porous polypropylene mesh covered with a covalent-bonded titanium layer has been claimed. The aim of this study was to find out whether the titanium surface alone or the difference in material load between the two available meshes influences clinical outcomes.     

Comparison of Permacol™ and Strattice™ for the repair of abdominal wall defects

Background  

Incisional hernias repaired with mesh can be expected have a lower recurrence rate than with primary repair. Biologic implants have replaced synthetic meshes in certain complex settings. We compared two porcine-dermis derived implants—cross-linked Permacol™ biologic implant and non-cross linked Strattice-firm™ tissue matrix—in a ventral hernia animal model. Our hypothesis is that cross-linked biologic implants are remodeled differently and thus behave differently than non-cross-linked biologic implants.     

Prospective evaluation of adhesion characteristics to intraperitoneal mesh and adhesiolysis-related complications during laparoscopic re-exploration after prior ventral hernia repair

Background  

The purpose of this study was to characterize the adhesion characteristics of absorbable- and nonabsorbable-barrier-coated meshes and to report adhesiolysis-related complications during laparoscopic re-exploration after prior ventral hernia repair.     

Remodeling characteristics and collagen distribution in synthetic mesh materials explanted from human subjects after abdominal wall reconstruction: an analysis of remodeling characteristics by patient risk factors and surgical site classifications

Background

The purpose of this study was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of synthetic meshes biopsied from their abdominal wall repair sites in the first attempt to generate a multivariable risk prediction model of non-constructive remodeling.

Methods

Biopsies of the synthetic meshes were obtained from the abdominal wall repair sites of 51 patients during a subsequent abdominal re-exploration. Biopsies were stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell infiltration, cell types, extracellular matrix deposition, inflammation, fibrous encapsulation, and neovascularization) and a mean composite score (CR). Biopsies were also stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a threshold p value of ≤0.200.

Results

The model selection process for the extracellular matrix score yielded two variables: subject age at time of mesh implantation, and mesh classification (c-statistic = 0.842). For CR score, the model selection process yielded two variables: subject age at time of mesh implantation and mesh classification (r ² = 0.464). The model selection process for the collagen III area yielded a model with two variables: subject body mass index at time of mesh explantation and pack-year history (r ² = 0.244).

Conclusion

Host characteristics and surgical site assessments may predict degree of remodeling for synthetic meshes used to reinforce abdominal wall repair sites. These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances for which non-constructive remodeling of an abdominal wall repair site with synthetic mesh reinforcement is most likely to occur.     

Repair of Parastomal Hernias with Biologic Grafts: A Systematic Review

Background  

Biologic grafts are increasingly used instead of synthetic mesh for parastomal hernia repair due to concerns of synthetic mesh-related complications. This systematic review was designed to evaluate the use of these collagen-based scaffolds for the repair of parastomal hernias.     

Evaluation of acute fixation strength of absorbable and nonabsorbable barrier coated mesh secured with fibrin sealant

Introduction  

The purpose of this study was to evaluate the acute fixation strength of fibrin sealant as an alternative fixation method for laparoscopic ventral hernia repair (LVHR) when utilized with absorbable and nonabsorbable barrier meshes.     

Mesh-related chronic infections in silicone-coated polyester suburethral slings

Introduction and hypothesis  

Despite claims of equivalence to the tension-free vaginal tape, a variety of suburethral slings have been introduced, with various modifications. Complications in certain synthetic slings and meshes have led to a recent FDA public health notification.     

Intraperitoneal onlay mesh: an experimental study of adhesion formation in a sheep model

Purpose  

Current hernia literature shows that the use of mesh in ventral hernia repair reduces the risk of recurrence significantly. In laparoscopic repair, the mesh is placed intraperitoneally. Accordingly, the close contact between mesh and viscera involves a risk of adhesion formation. In this experimental study, we examined the degree of de novo adhesion formation over time to currently available meshes.     

Methods for Assessing Bone Quality: A Review

Background  

Bone mass, geometry, and tissue material properties contribute to bone structural integrity. Thus, bone strength arises from both bone quantity and quality. Bone quality encompasses the geometric and material factors that contribute to fracture resistance.     

Biomechanical compatibility of surgical mesh and fascia being reinforced: dependence of experimental hernia defect repair results on anisotropic surgical mesh positioning

Purpose  

We aimed to compare the effectiveness of experimental middle hernia defect repair in regard to the transverse and longitudinal positioning of anisotropic lightweight surgical mesh.