Use of porcine dermal collagen as a prosthetic mesh in a contaminated field for ventral hernia repair: a case report

Outcomes and Quality of Life After Resorbable Synthetic Ventral Hernia Repair in Contaminated Fields

INTRODUCTION

The ideal mesh type for hernia repair in a contaminated field remains controversial. Data regarding outcomes beyond 1 year and the impact on quality of life (QoL) are unknown. This study aims to evaluate the long-term surgical outcomes and patient-reported outcomes (PROs) after contaminated repair with poly-4-hydroxybutyrate (P4HB) mesh.

MATERIALS METHODS

Patients undergoing a contaminated hernia repair with P4HB between 2015 and 2020 were identified. Surgical site occurrences and hernia recurrences were recorded. Long-term PROs as defined by the Abdominal Hernia-Q and Hernia-Related Quality-of-Life Survey were assessed.

RESULTS

Fifty-five patients were included with a mean age of 54.5 years, a body mass index of 34 kg/m2, and a defect size of 356.9 ± 227.7 cm2. Median follow-up time was 49 months with a reoperation rate of 14.5% and a hernia recurrence rate of 7.3%. Of the 55 patients, 37 completed preoperative and postoperative PRO questionnaires. When comparing preoperative with postoperative Abdominal Hernia-Q, there was significant improvement in overall PROs (2.1 vs 3.5, P < 0.001). This improvement was maintained with no significant changes between postoperative scores over the course of 5 years. Patients with complications saw the same improvement in postoperative PRO scores as those without complications.

CONCLUSIONS

Our study found a low hernia recurrence and acceptable long-term reoperation rates in patients undergoing hernia repair with P4HB mesh in a contaminated setting. We demonstrate a sustained significant improvement in QoL scores after hernia repair. These data yield insight into the long-term outcomes and QoL improvement, providing physicians further knowledge to better counsel their patients.

The increased angiogenic capacity and decreased inflammatory response when a mesh is used in combination with an omental flap. A prospective experimental study

BACKGROUND

The use of a surgical mesh for abdominal wall reconstruction is well established and has been used for long with minor complications, whereas the omental flap has been used for decades in reconstructive surgery.

AIM

To demonstrate the increased angiogenic capacity and the reduced inflammatory markers of a synthetic mesh when used in combination with an omental flap. Furthermore, we compare two independent meshes when used alone or in combination with the omental flap.

MATERIALS AND METHODS

Twenty-eight rats were included in the study. To determine the effect of using an omental flap under two different meshes, the animals were separated into four groups, i.e., group A (flap + mesh 1), group B (flap + mesh 1 + silicone), group C (flap + mesh 2), and group D (flap + mesh 2 + silicone). A silicone sheet was placed as a barrier between the mesh and the flap. All groups were sacrificed 8 weeks post-operatively.

RESULTS

The use of a silicone sheet barrier between any of the two synthetic meshes and the omental flap in an abdominal wall defect is accompanied by a markedly reduced angiogenesis in terms of a cluster of differentiation (CD)-34 (p < 0.001) and factor VIII (p = 0.0012) and by increased inflammatory response CD-68 (p = 0.0024) and visual scoring (p < 0.001).

CONCLUSIONS

Τhe increased angiogenic capacity and the reduced inflammatory markers of a synthetic surgical mesh when used in combination with an omental flap make it a useful option in the reconstruction of an abdominal wall defect on a large or contaminated wound.

Preventing Recurrence in Clean and Contaminated Hernias Using Biologic Versus Synthetic Mesh in Ventral Hernia Repair: The PRICE Randomized Clinical Trial

OBJECTIVE

The aim of this study was to evaluate which mesh type yields lower recurrence and complication rates after ventral hernia repair.

SUMMARY BACKGROUND DATA

More than 400,000 ventral hernia repairs are performed annually in the United States. Although the most effective method for repairing ventral hernias involves using mesh, whether to use biologic mesh versus synthetic mesh is controversial.

METHODS

Single-blind, randomized, controlled, pragmatic clinical trial conducted from March 2014 through October 2018; 165 patients enrolled with an average follow up of 26 months. Patients were randomized 1:1 to have their ventral hernias repaired using either a biologic (porcine) or synthetic (polypropylene) mesh. The primary study outcome measure was hernia recurrence at 2 years.

RESULTS

A total of 165 patients (68 men), mean age 55 years, were included in the study with a mean follow-up of 26 months. An intention-to-treat analysis noted that hernias recurred in 25 patients (39.7%) assigned to biologic mesh and in 14 patients (21.9%) assigned to synthetic mesh (P = 0.035) at 2 years. Subgroup analysis identified an increased rate of hernia recurrence in the biologic versus the synthetic mesh group under contaminated wound conditions (50.0% vs 5.9%; P for interaction = 0.041). Postoperative complication rates were similar for the 2 mesh types.

CONCLUSIONS

The risk of hernia recurrence was significantly higher for patients undergoing ventral hernia repair with biologic mesh compared to synthetic mesh, with similar rates of postoperative complications. These data indicate that the use of synthetic mesh over biologic mesh to repair ventral hernias is effective and can be endorsed, including under contaminated wound conditions.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02041494.

Emergency repair of complicated abdominal wall hernias: WSES guidelines

PURPOSE

In July 2013, the World Society of Emergency Surgery (WSES) held the first Consensus Conference on emergency repair of abdominal wall hernias in adult patients with the intention of producing evidence-based guidelines to assist surgeons in the management of complicated abdominal wall hernias. Guidelines were updated in 2017 in keeping with varying clinical practice: benefits resulting from the increased use of biological prosthesis in the emergency setting were highlighted, as previously published in the World Journal of Emergency Surgery. This executive summary is intended to consolidate knowledge on the emergency management of complicated hernias by providing the broad readership with a practical and concise version of the original guidelines.

METHODS

This executive manuscript summarizes the WSES guidelines reporting on the emergency management of complicated abdominal wall hernias; statements are highlighted focusing the readers' attention on the main concepts presented in the original guidelines.

CONCLUSIONS

Emergency repair of complicated abdominal hernias remains one of the most common and challenging surgical emergencies worldwide. WSES aims to provide an essential version of the evidence-based guidelines focusing on the timing of intervention, laparoscopic approach, surgical repair following the Centers for Disease Control and Prevention (CDC) wound classification, antimicrobial prophylaxis and anesthesia in the emergency setting.

2017 update of the WSES guidelines for emergency repair of complicated abdominal wall hernias

Emergency repair of complicated abdominal wall hernias may be associated with worsen outcome and a significant rate of postoperative complications. There is no consensus on management of complicated abdominal hernias. The main matter of debate is about the use of mesh in case of intestinal resection and the type of mesh to be used. Wound infection is the most common complication encountered and represents an immense burden especially in the presence of a mesh. The recurrence rate is an important topic that influences the final outcome. A World Society of Emergency Surgery (WSES) Consensus Conference was held in Bergamo in July 2013 with the aim to define recommendations for emergency repair of abdominal wall hernias in adults. This document represents the executive summary of the consensus conference approved by a WSES expert panel. In 2016, the guidelines have been revised and updated according to the most recent available literature.

Long-term outcomes of sandwich ventral hernia repair paired with hybrid vacuum-assisted closure

BACKGROUND

Sandwich ventral hernia repair (SVHR) may reduce ventral hernia recurrence rates, although with an increased risk of surgical site occurrences (SSOs) and surgical site infections (SSIs). Previously, we found that a modified negative pressure wound therapy (hybrid vacuum-assisted closure [HVAC]) system reduced SSOs and SSIs after ventral hernia repair. We aimed to describe our outcomes after SVHR paired with HVAC closure.

METHODS

We conducted a 4-y retrospective review of all complex SVHRs (biologic mesh underlay and synthetic mesh overlay) with HVAC closure performed at our institution by a single surgeon. All patients had fascial defects that could not be reapproximated primarily using anterior component separation. Descriptive statistics were used to report the incidence of postoperative complications and hernia recurrence.

RESULTS

A total of 60 patients (59.3 ± 11.4 y, 58.3% male, 75% American Society of Anesthesiologists class ≥3) with complex ventral hernias being underwent sandwich repair with HVAC closure. Major postoperative morbidity (Dindo-Clavien class ≥3) occurred in 14 (23.3%) patients, but incidence of SSO (n = 13, 21.7%) and SSI (n = 4, 6.7%) was low compared with historical reports. Median follow-up time for all patients was 12 mo (interquartile range 5.8-26.5 mo). Hernia recurrence occurred in eight patients (13.3%) after a median time of 20.6 months (interquartile range 16.4- 25.4 months).

CONCLUSIONS

Use of a dual layer sandwich repair for complex abdominal wall reconstruction is associated with low rates of hernia recurrence at 1 year postoperatively. The addition of the HVAC closure system may reduce the risk of SSOs and SSIs previously reported with this technique and deserves consideration in future prospective studies assessing optimization of ventral hernia repair approaches.

Porcine Dermis and Pericardium-Based, Non-Cross-Linked Materials Induce Multinucleated Giant Cells After Their In Vivo Implantation: A Physiological Reaction?

The present study analyzed the tissue reaction to 2 novel porcine-derived collagen materials: pericardium versus dermis. By means of the subcutaneous implantation model in mice, the tissue reactions were investigated at 5 time points: 3, 10, 15, 30, and 60 days after implantation. Histologic, histochemical, immunhistologic, and histomorphometric analysis methodologies were applied. The dermis-derived material underwent an early degradation while inducing mononuclear cells together with some multinucleated giant cells and mild vascularization. The pericardium-derived membrane induced 2 different cellular tissue reactions. The compact surface induced mononuclear cells and multinucleated giant cells, and underwent a complete degradation until day 30. The spongy surface of the membrane induced mainly mononuclear cells, and served as a stable barrier membrane for up to 60 days. No transmembranous vascularization was observed within the spongy material surface layer. The present data demonstrate the diversity of the cellular tissue reaction toward collagen-based materials from different tissues. Furthermore, it became obvious that the presence of multinucleated giant cells was associated with the material breakdown/degradation and vascularization. Further clinical data are necessary to assess extent to which the presence of multinucleated giant cells observed here will influence the materials stability, integration, and, correspondingly, tissue regeneration within human tissue.

Evaluation of a porcine dermal collagen (permacol) implant for abdominal wall reconstruction in a pediatric multitrauma patient

The presence of a contaminated surgical field in abdominal wall defects caused by trauma presents a challenge for surgeons. Both primary suture and synthetic meshes are strongly discouraged as surgical treatments in such cases. We describe the use of a porcine dermal collagen (Permacol) implant in an eight-year-old patient with multiple injuries. Three months after discharge, the child remains well with good cosmetic results. He is free of pain and has returned to full activity levels with complete wound closure and without any evidence of residual hernia. In conclusion, our experience indicates that the use of Permacol can be considered an efficient technique for reconstructing an infected abdominal wall defect of a pediatric multitrauma patient.

Impact of pericardium bovine patch (Tutomesh(®)) on incisional hernia treatment in contaminated or potentially contaminated fields: retrospective comparative study

PURPOSE

This retrospective comparative study analyzes the outcome of patients affected by incisional hernia in potentially contaminated or contaminated field, treated by three operative techniques.

METHODS

152 patients (62 M:90 F; mean age 65 ± 14 years) underwent incisional hernia repair (January 2002-January 2012) in complicated settings. Criteria of inclusion in the study were represented by the following causes of admission: mesh rejection/infection, obstruction without gangrene but with possible peritoneal bacterial translocation, obstruction with gangrene, enterocutaneous fistula or simultaneous presence of ileo- or colostomy. The patients were divided into three groups: A (n = 76), treated with primary closure technique; B and C (n = 38 each), with reinforcement by synthetic or pericardium bovine mesh (Tutomesh(®)), respectively. The prosthetic groups were divided into Onlay and Sublay subgroups.

RESULTS

Significant decreases in C vs A were observed for wound infection (3 vs 37%) and recurrence (0 vs 14%), and in C vs B for wound infection (3 vs 53%), seroma (0 vs 34%) and recurrence (0 vs 16%). Patients with concomitant bowel resection (BR) (43%) showed (all P < 0.05) an increase of overall morbidity (55 vs 33%) and wound infection rate (42 vs 24%) compared to cases without BR. Morbidity presented no significant differences in C-Onlay or Sublay subgroups. B-Sublay subgroup has (all P < 0.05) lower overall morbidity (20 vs 75%), wound infection (10 vs 68%) and seroma (0 vs 46%) than B-Onlay.

CONCLUSIONS

The pericardium bovine patch seems to be safe and effective to successfully repair ventral hernia in potentially contaminated operative fields, especially in association with bowel resection.

WSES guidelines for emergency repair of complicated abdominal wall hernias

Emergency repair of complicated abdominal hernias is associated with poor prognosis and a high rate of post-operative complications.A World Society of Emergency Surgery (WSES) Consensus Conference was held in Bergamo in July 2013, during the 2nd Congress of the World Society of Emergency Surgery with the goal of defining recommendations for emergency repair of abdominal wall hernias in adults. This document represents the executive summary of the consensus conference approved by a WSES expert panel.

Conservative management of mesh-site infection in hernia repair surgery: a case series

PURPOSE

The aim of this study is to assess the outcome of conservative management of infected mesh grafts following abdominal wall hernia repair.

METHODS

This study retrospectively examined the charts of patients who developed mesh-site infection following surgery for abdominal hernia repair to determine how effective conservative management in the form of antibiotics and wound management was on the resolution of infection and wound healing.

RESULTS

Over a period of 30 months, 13 patients developed infected mesh grafts post-hernia repair surgery. Twelve patients were successfully treated conservatively with local wound care and antibiotics if clinically indicated. One patient returned to theatre to have the infected mesh removed. Of the patients that healed eleven were treated with negative pressure wound therapy (VAC(®)).

CONCLUSION

This series of case studies indicate that conservative management of abdominal wall-infected hernia mesh cases is likely to be successful.

A decade of ventral incisional hernia repairs with biologic acellular dermal matrix: what have we learned?

BACKGROUND

Innovative types of biologic mesh have provided new alternatives to ventral incisional hernia repair, especially in the face of contamination. The authors studied the experience and outcomes of patients who underwent repair of a ventral incisional hernia with biologic mesh.

METHODS

Online database and detailed reference searches were conducted. Studies chosen for review had a sample size of at least 40 patients, level IV evidence at most, and a Methodological Index for Nonrandomized Studies index of at least 10. Indications for use of biologic mesh, type of mesh, patient comorbidities, and surgical techniques were also noted.

RESULTS

Eight studies fulfilled the search criteria and included 635 patients using AlloDerm, Surgisis, and Strattice biologic tissue matrices. In one study, indications and surgical techniques were standardized, and follow-up was prospective. In the other seven studies, indications, surgical techniques, and follow-up were assessed retrospectively. The mean patient age, when reported, was 55.7 years. Body mass index ranged from 30 to 35 kg/m2 in 44 percent of the reported patients. In seven of the eight studies [565 patients (89 percent)], the mean follow-up was 25.8 months and the mean hernia recurrence rate was 21 percent. Complication rate exceeded 20 percent in most studies.

CONCLUSIONS

Biologic tissue matrices are mostly used in contaminated fields, which has allowed for a one-stage repair with no or little subsequent mesh removal. Ventral incisional hernia repair with these matrices continues to be plagued by a high recurrence rate and complications. Prospective randomized trials are needed to properly direct practice in the use of these meshes and evaluate their ultimate value.

The use of porcine acellular dermal matrix in a bridge technique for complex abdominal wall reconstruction: an outcome analysis

BACKGROUND

Outcomes using the porcine acellular dermal matrix (PADM) in abdominal wall reconstruction (AWR) have been reported when used for midline reinforcement; however, there have been no reports focused on outcomes when used as a bridging mesh.

METHODS

A retrospective review was conducted of all patients who underwent AWR with a non-cross-linked PADM as a bridged repair without midline fascial approximation.

RESULTS

Nine patients were identified with an average follow-up of 546 days. The average preoperative hernia defect diameter was 22.4 cm. After PADM placement, the average defect diameter was 9.8 cm. Complications occurred in 55.6% of patients, with PADM exposure occurring in all of these patients. No PADM was explanted, and all patients eventually healed. Abdominal wall eventration and/or recurrence occurred in 8 of 9 (88.9%) patients.

CONCLUSIONS

When fascial approximation cannot be achieved, PADM bridging may be the best option to avoid complications associated with synthetic mesh. However, there is a high potential for abdominal wall eventration and/or recurrence.

Repair of incisional hernias with biological prosthesis: a systematic review of current evidence

BACKGROUND

No consensus has been reached on the use of bioprosthetics to repair abdominal wall defects. The purpose of this systematic review was to summarize the outcomes from studies describing this use of various bioprosthetics for incisional hernia repair.

METHODS

Studies published by October 2011 were identified through literature searches using EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials.

RESULTS

A total of 491 articles were scanned, 60 met eligibility criteria. Most studies were retrospective case studies. The studies ranged considerably in methodologic quality, with a modified Methodological Index of Nonrandomized Studies score from 5 to 12. Many repairs were performed in contaminated surgical sites (47.9%). At least one complication was seen in 87% of repairs. Major complications noted were wound infections (16.9%) and seroma (12.0%). With a mean follow-up period of 13.6 months the hernia recurrence rate was 15.2%.

CONCLUSIONS

There is an insufficient level of high-quality evidence in the literature on the value of bioprosthetics for incisional hernia repair. Randomized controlled trials that use standardized reporting comparing bioprosthetics with synthetic mesh for incisional hernia repair are needed.

Use of permacol in parietal and general surgery: a bibliographic review

BACKGROUND

The use of synthetic meshes on infected incisional hernias often fails and is therefore contraindicated. Biological meshes offer a novel solution. Among them, Permacol requires a bibliographic analysis of its efficacy and tolerance.

DESIGN

A bibliographic analysis was carried out on the efficacy and tolerance of Permacol in parietal and general surgery.

RESULTS

A total of 22 publications described the use of Permacol in digestive surgery. The advantages of Permacol would be usability in contaminated surgical fields, biocompatibility, no erosion of intestinal wall, and less risk of adhesions. The main drawback of Permacol is its high cost.

CONCLUSION

Even so, Permacol can play an important part in the short-term management of complex or contaminated abdominal wall defects. The lack of long-term studies and the high cost of the implant call for a medical cost-effectiveness assessment to determine the indications for Permacol in parietal and general surgery.

Instant Abdominal Wall Reconstruction with Biologic Mesh following Resection of Locally Advanced Colonic Cancer

We present a case of immediate abdominal wall reconstruction with biologic mesh following the resection of locally advanced colonic cancer. The tumor in the right colon did not respond to neoadjuvant chemotherapy. Surgical enbloc excision, including excision of the invasion in the abdominal wall, was achieved, and the defect was reconstructed with porcine dermal collagen mesh. The patient was discharged with no complication, and adaptation of the mesh was excellent at the six-month followup.

Comparative analysis of histopathologic effects of synthetic meshes based on material, weight, and pore size in mice

BACKGROUND

While synthetic prosthetics have essentially become mandatory for hernia repair, mesh-induced chronic inflammation and scarring can lead to chronic pain and limited mobility. Mesh propensity to induce such adverse effects is likely related to the prosthetic's material, weight, and/or pore size. We aimed to compare histopathologic responses to various synthetic meshes after short- and long-term implantations in mice.

MATERIAL AND METHODS

Samples of macroporous polyester (Parietex [PX]), heavyweight microporous polypropylene (Trelex[TX]), midweight microporous polypropylene (ProLite[PL]), lightweight macroporous polypropylene (Ultrapro[UP]), and expanded polytetrafluoroethylene (DualMesh[DM]) were implanted subcutaneously in mice. Four and 12 wk post-implantation, meshes were assessed for inflammation, foreign body reaction (FBR), and fibrosis.

RESULTS

All meshes induced varying levels of inflammatory responses. PX induced the greatest inflammatory response and marked FBR. DM induced moderate FBR and a strong fibrotic response with mesh encapsulation at 12 wk. UP and PL had the lowest FBR, however, UP induced a significant chronic inflammatory response. Although inflammation decreased slightly for TX, marked FBR was present throughout the study. Of the three polypropylene meshes, fibrosis was greatest for TX and slightly reduced for PL and UP. For UP and PL, there was limited fibrosis within each mesh pore.

CONCLUSION

Polyester mesh induced the greatest FBR and lasting chronic inflammatory response. Likewise, marked fibrosis and encapsulation was seen surrounding ePTFE. Heavier polypropylene meshes displayed greater early and persistent fibrosis; the reduced-weight polypropylene meshes were associated with the least amount of fibrosis. Mesh pore size was inversely proportional to bridging fibrosis. Moreover, reduced-weight polypropylene meshes demonstrated the smallest FBR throughout the study. Overall, we demonstrated that macroporous, reduced-weight polypropylene mesh exhibited the highest degree of biocompatibility at sites of mesh implantation.

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.

Methods

Animals were divided into 12 groups (4 matrix types and 3 termination time-points per matrix). A ventral defect was carefully created and overlapped with the biologic prosthesis.

Results

Major complications were seroma induction (3 mesh types), implant extrusion (1 mesh type), severe inflammatory and immune responses (non-crosslinked mesh), fibrosis and mineralisation (3 mesh types). After inflammation resolution, 3 of the matrices tested supported hernia healing but with marked tissue and temporal differences. AlloDerm^®* and Surgisis Gold™ showed tissue reactivity with the host and a rapid rate of matrix remodelling. Bard CollaMend™^* Implant proved to be inept for hernia repair under the conditions tested. Permacol™ biological implant integration with host tissue increased over time, supporting hernia healing with strength of tissue, and appears to be a safe prosthetic material for ventral hernia repair based on the results of this rodent study.

Biological mesh for abdominal wall hernia synthetic mesh multidrug-resistant Pseudomonas aeruginosa infection: report of a case

The use of biological mesh for the treatment of synthetic mesh-related infections in patients who undergo ventral hernia repair has been considered over the past few years. Removal of the infected synthetic mesh, which may be required in such cases, can result in recurring herniation. Biological implants have thus been recently used for the reconstruction of the existing defect. We herein present the case of a patient who developed multidrug-resistant Pseudomonas aeruginosa synthetic mesh infection following hernia repair, which was managed by the removal of the material and the application of a biological mesh in the contaminated area.

Effects of mast cell modulation on early host response to implanted synthetic meshes

INTRODUCTION

Mast cells (MCs) and their products (e.g., histamine, serotonin, heparin, prostaglandins, cytokines, etc.) play key roles in controlling local inflammation, wound healing, and foreign body reactions in vivo. Investigation of the role of MCs in mediating local tissue responses to synthetic hernia meshes has been very limited to date. We aimed to determine the effects of MCs/MC products in mice undergoing synthetic mesh implantation.

MATERIALS AND METHODS

Circular samples (5 mm) of heavyweight microporous polypropylene (Trelex), midweight microporous polypropylene (ProLite), lightweight macroporous polypropylene with poliglecaprone (Ultrapro), and 3-dimensional macroporous polyester (Parietex) meshes were implanted subcutaneously in C57BL/6 J mice with and without cromolyn (MC stabilizer/suppressant) treatment (50 mg/kg, daily IP). Two weeks post-implantation, all meshes were explanted and evaluated histologically using H&E and trichrome stains.

RESULTS

Chronic inflammation was focused around individual mesh fibers; inter-fiber inflammation and fibrosis diminished as mesh porosity increased. MC accumulation was seen at the periphery of inflammatory reactions, and in association with mesh-induced fibrosis and neovascularization. Cromolyn treatment resulted in significantly decreased fibrotic responses to all four meshes and reduced inflammation induced by Trelex, ProLite, and Parietex meshes but not Ultrapro.

CONCLUSION

We demonstrated that MCs play important roles in mesh-induced host tissue reactions. Blocking MC degranulation decreased early inflammation and fibrosis induced by most synthetic meshes in this study. Further evaluation and understanding of the role of MCs in mesh-induced tissue reactions will provide new therapeutic approaches to enhance the biocompatibility of surgical meshes and ultimately improve clinical outcomes in patients undergoing hernia repair with synthetic biomaterials.

Use of biological meshes for abdominal wall reconstruction in highly contaminated fields

Abdominal wall defects and incisional hernias represent a challenging problem. In particular, when a synthetic mesh is applied to contaminated wounds, its removal is required in 50%-90% of cases. Biosynthetic meshes are the newest tool available to surgeons and they could have a role in ventral hernia repair in a potentially contaminated field. We describe the use of a sheet of bovine pericardium graft in the reconstruction of abdominal wall defect in two patients. Bovine pericardium graft was placed in the retrorectus space and secured to the anterior abdominal wall using polypropylene sutures in a tension-free manner. We experienced no evidence of recurrence at 4 and 5 years follow-up.

Morphological and mechanical characteristics of the reconstructed rat abdominal wall following use of a wet electrospun biodegradable polyurethane elastomer scaffold

Although a variety of materials are currently used for abdominal wall repair, general complications encountered include herniation, infection, and mechanical mismatch with native tissue. An approach wherein a degradable synthetic material is ultimately replaced by tissue mechanically approximating the native state could obviate these complications. We report here on the generation of biodegradable scaffolds for abdominal wall replacement using a wet electrospinning technique in which fibers of a biodegradable elastomer, poly(ester urethane)urea (PEUU), were concurrently deposited with electrosprayed serum-based culture medium. Wet electrospun PEUU (wet ePEUU) was found to exhibit markedly different mechanical behavior and to possess an altered microstructure relative to dry processed ePEUU. In a rat model for abdominal wall replacement, wet ePEUU scaffolds (1x2.5 cm) provided a healing result that developed toward approximating physiologic mechanical behavior at 8 weeks. An extensive cellular infiltrate possessing contractile smooth muscle markers was observed together with extensive extracellular matrix (collagens, elastin) elaboration. Control implants of dry ePEUU and expanded polytetrafluoroethylene did not experience substantial cellular infiltration and did not take on the native mechanical anisotropy of the rat abdominal wall. These results illustrate the markedly different in vivo behavior observed with this newly reported wet electrospinning process, offering a potentially useful refinement of an increasingly common biomaterial processing technique.

Human monocyte activation by biologic and biodegradable meshes in vitro

BACKGROUND

Inflammation and wound healing play critical roles in the integration of biologic and biodegradable meshes (BMs) at hernia repair sites. Monocytes/macrophages (M/MØs) are key cells controlling inflammation and wound healing. These cells release inflammatory cytokines and growth factors such as interleukin (IL)-1beta, IL-6, IL-8, and vascular endothelial growth factor (VEGF) upon activation. Although BMs have been increasingly used in hernia repairs worldwide, to date, investigations of inflammatory responses to various BMs have been limited.

METHODS

Mesh samples of three acellular human dermis-derived biologic meshes (AlloDerm, AlloMax, FlexHD) and one biodegradable synthetic mesh (Bio-A) were placed in 96-well plates. Human peripheral blood mononuclear cells (PBMCs) were isolated from six healthy subjects, added to each well, and incubated for 7 days. Culture supernatants were assayed for IL-1beta, IL-6, IL-8, and VEGF levels using a multiplex bead-base immunoassay system (Bio-Plex).

RESULTS

All four meshes induced cytokine expression from activated M/MØs to varying degrees in vitro. FlexHD induced significantly more IL-1beta (2,591 pg/ml) than AlloMax (517 pg/ml), AlloDerm (48 pg/ml), or Bio-A (28 pg/ml) (p < 0.001). AlloMax stimulated a significantly greater quantity of IL-6 (38,343 pg/ml) than FlexHD (19,317 pg/ml), Bio-A (191 pg/ml), or AlloDerm (103 pg/ml) (p < 0.05). Interleukin-8 and VEGF displayed trends similar to that of IL-6. There were no significant differences in cytokine production between AlloDerm and Bio-A.

CONCLUSION

This study demonstrated that human macrophages are activated by human dermis-derived biologic and biodegradable meshes in vitro. A wide range of cytokine and growth factor induction was seen among the different mesh products. These differences in M/MØ activation may be related to the proprietary processing technologies of the studied meshes. The study results raise the possibility that these differences in M/MØ activation could indicate varying intensities of inflammation that control integration of different biologic meshes at the sites of hernia repair.

Are biologic grafts effective for hernia repair?: a systematic review of the literature

Biologic grafts for hernia repair are a relatively new development in the world of surgery. A thorough search of the Medline database for uses of various biologic grafts in hernia shows that the evidence behind their application is plentiful in some areas (ventral, inguinal) and nearly absent in others (parastomal). The assumption that these materials are only suited for contaminated or potentially contaminated surgical fields is not borne out in the literature, with more than 4 times the experience being reported in clean fields and the average success rates being higher (93% vs 87%). Outcomes prove to be highly dependent on material source, processing methods and implant scenarios with failure rates ranging from zero to more than 30%. Small intestinal submucosa (SIS) grafts have an aggregate failure rate of 6.7% at 19 months whereas acellular human dermis (AHD) grafts have a failure rate of 13.6% at 12 months. Chemically cross-linked grafts have much less published data than the non-cross-linked materials. In particular, the search found 33 articles for SIS, 32 for AHD, and 13 for cross-linked porcine dermis. Furthermore, the cumulative level of evidence for each graft material was fairly low (2.6 to 2.9), and only 1 material (SIS) had level 1 evidence reported in any hernia type (inguinal and hiatal). Together, biologic grafts have published evidence showing success rates better than 90% overall and more than 2000 years of cumulative implant time. Improvements in materials, techniques, and patient selection are likely to improve these numbers as this field of surgery matures.

Prosthetic abdominal wall hernia repair in emergency surgery: from polypropylene to biological meshes

The use of nonabsorbable prosthetic materials such as polypropylene, polyester, and ePTFE, have expanded and are now widely used in reparative surgery for abdominal wall hernias.There are still difficulties to find correct indication for prosthetic implant in emergency hernia surgery: as a matter of fact there is still a great debate if to use non-absorbable prostheses in potentially or truly infected operating fields [e.g. after intestinal resections].All these problems can be avoided with the use of absorbable prosthetic materials such as those composed of lactic acid polymers or lactic and glycolic acid copolymers: however, the use of these absorbable prosthesis exposes the patient to a rapid and inevitable hernia recurrence.It is important to remember that prosthetic repair has been proven to have a significant less risk of recurrence than repair with direct sutures.Recently, new "biologic" prosthetic materials have been developed and proposed for the clinical use in infected fields. These materials can be called "remodeling" for the way by which they are replaced after their placement within the patient. The "remodeling" process is made possible through a process of incorporation, where a reproduction of a site-specific tissue similar to the original host tissue is created.

New "biological" meshes: the need for a register. The EHS Registry for Biological Prostheses: call for participating European surgeons

Non-absorbable prosthetic materials in hernia surgery can cause relatively rare complications, which include chronic pain, a feeling of stiffness with reduced compliance of the abdominal wall, prosthetic erosion/fistulisation and an increased risk of persistent deep infection. Recently, to avoid these problems, new "biological" prosthetic materials have been developed and proposed for clinical use. These materials are all essentially composed of an extracellular matrix stripped of its cellular components, and differ substantially only in their source (porcine small intestine submucosa, porcine dermis or cadaveric human dermis). Because of the numerous variables involved, it is very difficult to conduct a randomised controlled trial. Therefore, the European Hernia Society (EHS) has decided to start the EHS Registry for Biological Prostheses (ERBP). This is a prospective registry in Europe on the use of collagen meshes in (potentially) contaminated circumstances or clean surgical fields. The registry intends to collect some preoperative data on the patient and indication, intraoperative data and outcome data.

Prosthetic material in ventral hernia repair: how do I choose?

Several factors must be considered in deciding which mesh to use for a ventral hernia repair. Open hernia repairs with no exposure of mesh to viscera can be performed with unprotected synthetic mesh, preferably a "lightweight" option. For open repair with high risk for fascial dehiscence and visceral exposure to mesh, and for open underlay repair and laparoscopic underlay repair, recommendations call for a tissue-separating mesh that prevents ingrowth of intra-abdominal contents into the mesh. Although no long-term data are available about biologic (acellular collagen scaffold) meshes, these may have good results when used in contaminated or well-drained infected fields, and do best when used according to the principles of a high-quality synthetic mesh repair (wide mesh overlap, frequent fixation points). Evidence is still insufficient to support the use of biologic materials for primary hernia repair.