Repair of abdominal wall defects with bovine pericardium

A Review of Advanced Abdominal Wall Hernia Patch Materials

Tension-free abdominal wall hernia patch materials (AWHPMs) play an important role in the repair of abdominal wall defects (AWDs), which have a recurrence rate of <1%. Nevertheless, there are still significant challenges in the development of tailored, biomimetic, and extracellular matrix (ECM)-like AWHPMs that satisfy the clinical demands of abdominal wall repair (AWR) while effectively handling post-operative complications associated with abdominal hernias, such as intra-abdominal visceral adhesion and abnormal healing. This extensive review presents a comprehensive guide to the high-end fabrication and the precise selection of these advanced AWHPMs. The review begins by briefly introducing the structures, sources, and properties of AWHPMs, and critically evaluates the advantages and disadvantages of different types of AWHPMs for AWR applications. The review subsequently summarizes and elaborates upon state-of-the-art AWHPM fabrication methods and their key characteristics (e.g., mechanical, physicochemical, and biological properties in vitro/vivo). This review uses compelling examples to demonstrate that advanced AWHPMs with multiple functionalities (e.g., anti-deformation, anti-inflammation, anti-adhesion, pro-healing properties, etc.) can meet the fundamental clinical demands required to successfully repair AWDs. In particular, there have been several developments in the enhancement of biomimetic AWHPMs with multiple properties, and additional breakthroughs are expected in the near future.

Abdominal wall hernia repair: from prosthetic meshes to smart materials

Hernia reconstruction is one of the most frequently practiced surgical procedures worldwide. Plastic surgery plays a pivotal role in reestablishing desired abdominal wall structure and function without the drawbacks traditionally associated with general surgery as excessive tension, postoperative pain, poor repair outcomes, and frequent recurrence. Surgical meshes have been the preferential choice for abdominal wall hernia repair to achieve the physical integrity and equivalent components of musculofascial layers. Despite the relevant progress in recent years, there are still unsolved challenges in surgical mesh design and complication settlement. This review provides a systemic summary of the hernia surgical mesh development deeply related to abdominal wall hernia pathology and classification. Commercial meshes, the first-generation prosthetic materials, and the most commonly used repair materials in the clinic are described in detail, addressing constrain side effects and rational strategies to establish characteristics of ideal hernia repair meshes. The engineered prosthetics are defined as a transit to the biomimetic smart hernia repair scaffolds with specific advantages and disadvantages, including hydrogel scaffolds, electrospinning membranes, and three-dimensional patches. Lastly, this review critically outlines the future research direction for successful hernia repair solutions by combing state-of-the-art techniques and materials.

Case report: Abdominal hernia repair using a surgical wire and an autologous omental graft in a Japanese Black calf

Background

Hernia formation is a well-known abdominal wall disorder in calves and most often occurs in the umbilical region. In addition, it occurs in the abdominal wall outside the umbilical region. It has been reported to involve acquired factors, such as external force to the lower or lateral abdominal wall, trauma, muscle weakness, and, although rare, congenital or hereditary factors. Although there have been reports on the repair of abdominal wall hernias caused by abnormal muscle formation, there have been no reports on the treatment of abdominal wall hernias caused by abnormal vertebral and rib formation in cattle or other ruminants. In this study, for the first time, we describe a case of successful closure of a hernia in the left flank caused by malformation of the vertebrae and ribs. The repair was performed by narrowing the ribs using a surgical wire and covering the defect with a free omental graft.

Case presentation

A male Japanese Black calf showed a mild bulge of the left abdominal wall and abnormal morphology of the left ribs immediately after birth. At 3 months of age, computed tomography revealed fusion of the 9th, 10th, and 11th thoracic vertebrae and missing formation of the 10th and 11th left ribs at the thoracic vertebral fusion site. Additionally, a 15.2 × 24.4 cm abdominal hernia had formed in the abdominal wall. During surgery, the ribs forming the hernia were narrowed with a surgical wire, and the hernia was covered with a large autologous free omental graft to prevent intra-abdominal organ prolapse. At the monthly follow-up (11 months after surgery), the calf had developed similarly to other calves of the same age on the farm, and no complications were noted.

Conclusions

The current case shows that a combination of rib correction using a surgical wire combined with transplantation of a free autologous greater omentum graft was shown to be a possible treatment option for surgical repair of large abdominal wall hernias caused by rib malformation.

Mapping of bovine pericardium to enable a standardized acquirement of material for medical implants

OBJECTIVES

Bovine pericardium - native, fixed as well as decellularized - is one of the most common implant materials in modern cardiovascular surgery. Although used in everyday procedures, there are no recommendations in regard to which part of the pericardium to prefer. It was the aim of this study, to identify areas of the pericardium with consistent properties and high durability.

METHODS

Fresh bovine pericardia were collected from a local slaughterhouse. The native pericardia were analyzed at 140 spots in regard to thickness and fiber orientation. Based on these results, five promising areas were selected for further evaluation. The pericardia were decellularized with detergents (0.5% sodiumdesoxycholate/0.5% sodiumdodecylsulfate) and subsequently incubated in DNAse. The two investigation groups native und DC consisted of 20 samples each. The efficiency of the decellularization was evaluated by DNA quantification, as well as DAPI and H&E staining. Biomechanical properties were determined using uniaxial tensile tests. To evaluate the microstructure, scanning electron microscopy, Picrosirius Red- and Movat's Pentachrome staining were utilized. To assess the long-term durability, patches were tested in a high-cycle system for a duration equaling the stress of three months in-vivo. Commercially available, fixed pericardium patches served as control group.

RESULTS

Only a limited part of the pericardium showed a homogenous and usable thickness. The decellularization removed all cell nuclei, proven by negative DAPI and H&E staining, and also significantly reduced the DNA amount by 84%. The mechanical testing revealed that two investigated areas had an inconsistent tensile strength. Microscopical observations showed that the integrity of the extracellular matrix did not suffer by the decellularization procedure. During the long-term testing, most of the pericardia slowly lost tautness, though none of them got measurably damaged. Especially one area showed no decline of tensile strength after durability testing at all. Decellularized patches and fixed patches achieved comparable results in mechanical testing and microscopical evaluation after the durability testing.

CONCLUSION

We could clearly document significant, location-based differences within single pericardia. Only one area showed consistent properties and a high durability. We highly recommend taking this into account for future implant material selections.

Biological Mesh in Contaminated Fields—Overuse without Data: A Systematic Review of Their Use in Abdominal Wall Reconstruction

Ventral hernia repair in contaminated fields is a significant problem for surgeons. We performed a systematic review regarding the use of biological mesh in contaminated fields for abdominal wall reconstruction. The primary end points were recurrence and infection of the hernia repair. An independent search of scientific papers in the English language was performed by three reviewers. Articles were chosen based on reference to ventral hernias, their use in infected fields, and in human subjects. Papers were scored using the Methodological Index for Non-Randomized Studies and those with a score of 8 or more were combined to evaluate the end points. A total of 16 studies from six different mesh products met our criteria. These papers comprised 554 patients with an overall infection rate of 24 per cent and a recurrence rate of 20 per cent. The largest study used 116 patients. All papers were case series. Overall the data for use of biological mesh products in contaminated fields are limited. Further controlled studies are needed to address this important and clinically relevant question. Caution should be used when using biological mesh products in infected fields because there is a paucity of controlled data and none have U.S. Food and Drug Administration approval for use in infected fields.

Mammalian Pericardium-Based Bioprosthetic Materials in Xenotransplantation and Tissue Engineering

Bioprosthetic materials based on mammalian pericardium tissue are the gold standard in reconstructive surgery. Their application range covers repair of rectovaginal septum defects, abdominoplastics, urethroplasty, duraplastics, maxillofacial, ophthalmic, thoracic and cardiovascular reconstruction, etc. However, a number of factors contribute to the success of their integration into the host tissue including structural organization, mechanical strength, biocompatibility, immunogenicity, surface chemistry, and biodegradability. In order to improve the material's properties, various strategies are developed, such as decellularization, crosslinking, and detoxification. In this review, the existing issues and long-term achievements in the development of bioprosthetic materials based on the mammalian pericardium tissue, aimed at a wide-spectrum application in reconstructive surgery are analyzed. The basic technical approaches to preparation of biocompatible forms providing continuous functioning, optimization of biomechanical and functional properties, and clinical applicability are described.

Multiparametric Optical Bioimaging Reveals the Fate of Epoxy Crosslinked Biomeshes in the Mouse Subcutaneous Implantation Model

Biomeshes based on decellularized bovine pericardium (DBP) are widely used in reconstructive surgery due to their wide availability and the attractive biomechanical properties. However, their efficacy in clinical applications is often affected by the uncontrolled immunogenicity and proteolytic degradation. To address this issue, we present here in vivo multiparametric imaging analysis of epoxy crosslinked DBPs to reveal their fate after implantation. We first analyzed the structure of the crosslinked DBP using scanning electron microscopy and evaluated proteolytic stability and cytotoxicity. Next, using combination of fluorescence and hypoxia imaging, X-ray computed microtomography and histology techniques we studied the fate of DBPs after subcutaneous implantation in animals. Our approach revealed high resistance to biodegradation, gradual remodeling of a surrounding tissue forming the connective tissue capsule and calcification of crosslinked DBPs. These changes were concomitant to the development of hypoxia in the samples within 3 weeks after implantation and subsequent induction of angiogenesis and vascularization. Collectively, presented approach provides new insights on the transplantation of the epoxy crosslinked biomeshes, the risks associated with its applications in soft-tissue reconstruction and can be transferred to studies of other types of implants.

A novel tool to evaluate bias in literature on use of biologic mesh in abdominal wall hernia repair

PURPOSE

Biologic meshes are being increasingly used for abdominal hernia repair in high-risk patients or patients with a previous history of wound infection, due to their infection-resistant properties. Several studies have been carried out to assess whether biologic mesh is superior to synthetic mesh, as well as to establish guidelines for their use. Unfortunately, most of these studies were not rigorously designed and were vulnerable to different types of bias. The systematic reviews that have been published so far on this topic contain the same biases and limitations of the primary articles that are analyzed. The lack of a literature review on the bias on the use of biological mesh prompted us to conduct the literature search, assessment and plan this article.

METHODS

We performed a literature search in PubMed, Embase and Cochrane databases of systematic reviews on biologic mesh for ventral hernia repair. The literature review was conducted using the Population, Intervention, Comparisons, Outcomes and Design approach. We identified 40 studies that matched the stringent criteria we had set. We then created a 13-point instrument to assess for bias and applied it on the primary studies that we intended to analyze.

RESULTS

Most primary studies are case series or case reports of patients undergoing abdominal hernia repair with biologic mesh, without any comparison group, and the inclusion of cases was only specified to be consecutive in 6 out of 40 cases. In terms of assessing outcomes, in none of the 40 articles were the outcome assessors blinded to the intervention or exposure status of participants.

CONCLUSION

The instrument that we created could allow to assess the risk of bias in different kind of studies. Our assessment of the studies based on the criteria that we had set up in the instrument clearly identified that further research needs to be done due to the lack of unbiased studies regarding the use of biologic meshes for abdominal hernia repair.

Stabilization and Sterilization of Pericardial Scaffolds by Ultraviolet and Low-Energy Electron Irradiation

IMPACT STATEMENT

Pericardium-based tissue transplantation is a lifesaving treatment. Commercial glutaraldehyde-treated pericardial tissue exhibits cytotoxicity, which is associated with the accelerated graft failure. Replacement of glutaraldehyde has been suggested to overcome those drawbacks. In this study, we report a toxin-free method that combines tissue stabilization with a terminal sterilization. Our data indicate that the SULEEI procedure, which is part of an issued patent, may be a promising first step toward glutaraldehyde-free pericardium-based tissue transplants. Thus, our results may contribute to improving cardiovascular treatment strategies.

Comparison of in vivo remodeling of urinary bladder matrix and acellular dermal matrix in an ovine model

Aim: Biologically derived surgical graft materials come from a variety of sources with varying mechanical properties. This study aimed to evaluate the host response and mechanical performance of two extracellular matrix devices in a large animal preclinical model. Materials & methods: Bilateral defects were created in the fascia lata of sheep and repaired with either an acellular dermal matrix (ADM) or urinary bladder matrix (UBM). After 1 or 3 months, the repair site was explanted for histological and mechanical analysis. Results & conclusion: Despite pre-implantation mechanical differences, both UBM and ADM demonstrated similar mechanical performance at 3 months. However, UBM was completely remodeled into site-appropriate tissue by 3 months, while ADM showed limited tissue incorporation.

Systematic review of the stage of innovation of biological mesh for complex or contaminated abdominal wall closure

Background

Achieving stable closure of complex or contaminated abdominal wall incisions remains challenging. This study aimed to characterize the stage of innovation for biological mesh devices used during complex abdominal wall reconstruction and to evaluate the quality of current evidence.

Methods

A systematic review was performed of published and ongoing studies between January 2000 and September 2017. Eligible studies were those where a biological mesh was used to support fascial closure, either prophylactically after midline laparotomy, or for reinforcement after repair of incisional hernia with midline incision. The primary outcome measure was the IDEAL framework stage of innovation. The key secondary outcome measure was the GRADE criteria for study quality.

Results

Thirty‐five studies including 2681 patients were included. Four studies considered mesh prophylaxis, 23 considered hernia repair, and eight reported on both. There was one published randomized trial (IDEAL stage 3), none of which was of high quality; the others were non‐randomized studies (IDEAL stage 2a). A detailed description of surgical technique was provided in most studies (27 of 35); however, no study reported outcomes according to the European Hernia Society consensus statement and only two described quality control of surgical technique during the study. From 21 ongoing randomized trials and observational studies, 11 considered repair of incisional hernia and 10 considered prophylaxis (seven in elective settings).

Conclusion

The evidence base for biological mesh is limited, and better reporting and quality control of surgical techniques are needed. Although results of ongoing trials over the next decade will improve the evidence base, further study is required in the emergency and contaminated settings.

Nitro-Oleic Acid (NO2-OA) Release Enhances Regional Angiogenesis in a Rat Abdominal Wall Defect Model

Ventral hernia is often addressed surgically by the placement of prosthetic materials, either synthetic or from allogeneic and xenogeneic biologic sources. Despite advances in surgical approaches and device design, a number of postsurgical limitations remain, including hernia recurrence, mesh encapsulation, and reduced vascularity of the implanted volume. The in situ controlled release of angiogenic factors from a scaffold facilitating abdominal wall repair might address some of these issues associated with suboptimal tissue reconstruction. Furthermore, a biocomposite material that combines the favorable mechanical properties achievable with synthetic materials and the bioactivity associated with xenogeneic tissue sources would be desirable. In this report, an abdominal wall repair scaffold has been designed based on a microfibrous, elastomeric poly(ester carbonate)urethane urea matrix integrated with a hydrogel derived from decellularized porcine dermis (extracellular matrix [ECM] gel) and poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with nitro-oleic acid (NO₂-OA). NO₂-OA is an electrophilic fatty acid nitro-alkene derivative that, under hypoxic conditions, induces angiogenesis. This scaffold was utilized to repair a rat abdominal wall partial thickness defect, hypothesizing that the nitro-fatty acid release would facilitate increased angiogenesis at the 8-week endpoint. The quantification of neovascularization was conducted by novel methodologies to assess vessel morphology and spatial distribution. The repaired abdominal wall defects were evaluated by histopathologic methods, including quantification of the foreign body response and cellular ingrowth. The results showed that NO₂-OA release was associated with significantly improved regional angiogenesis. The combined biohybrid scaffold and NO₂-OA-controlled release strategy also reduced scaffold encapsulation, increased wall thickness, and enhanced cellular infiltration. More broadly, the three components of the composite scaffold design (ECM gel, polymeric fibers, and PLGA microparticles) enable the tuning of performance characteristics, including scaffold bioactivity, degradation, mechanics, and drug release profile, all decisive factors to better address current limitations in abdominal wall repair or other soft tissue augmentation procedures.

Evaluation of a bioengineered construct for tissue engineering applications

Effective biomaterial options for tissue repair and regeneration are limited. Current biologic meshes are derived from different tissue sources and are generally sold as decellularized tissues. This work evaluated two collagen based bioengineered constructs and a commercial product in a model of abdominal full thickness defect repair. To prepare the bioengineered construct, collagen type 1 from porcine skin was isolated using an acid solubilization method. After purification, the collagen was formed into collagen sheets that were physically bonded to form a mechanically robust construct that was subsequently laser micropatterned with pores as a means to promote tissue integration (collagen only construct). A second engineered construct consisted of the aforementioned collagen construct embedded in an RGD-functionalized alginate gel that serves as a bioactive interface (collagen-alginate construct). The commercial product is a biologic mesh derived from bovine pericardium (Veritas^® ). We observed enhanced vascularization in the midportion of the engineered collagen-alginate construct 2 weeks after implantation. Overall, the performance of the bioengineered constructs was similar to that of the commercial product with comparable integration strength at 8 weeks. Bioengineered constructs derived from monomeric collagen demonstrate promise for a variety of load bearing applications in tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2345-2354, 2018.

Comparative Cellular Local Response in Abdominal Defect Plastic Surgery with Bovine Pericardium and Bovine Fascia Preserved in Formaldehyde in Experimental Rabbits

In the present paper, we refer to a method of primary closure of congenital defects of the anterior abdominal wall with tensionless viscero-abdominal disproportion. The study group included 10 animals subjected to surgery of the abdominal wall defect closure with bovine pericardium graft preserved in 0.5% formaldehyde, and 5 rabbits of the same breed and weight, in which bovine fascia graft was used as implant, being preserved in 0.5% formaldehyde. The abdominal anterior wall defect was made surgically by excision of the musculo-fascial structures and peritoneum. Bovine pericardium graft and bovine fascia graft were placed and fixed posteriorly to rectus abdominals muscles, having direct contact with the intra-abdominal contents and protected by suturing skin and subcutaneous layer.

The purpose of the study was to perform a comparative postoperative evaluation of local macroscopic and microscopic changes that develop after reconstruction of the major abdominal wall defects experimentally induced in rabbits, using bovine pericardium and bovine fascia grafts preserved in 0.5% formaldehyde.

In cases of major fascial defects of the anterior abdominal wall, bovine pericardium graft has acceptable strength and biocompatibility, having stabilizing properties of the abdominal wall due to the development of the connective tissue layer located between the implant and the subcutaneous layer. Bovine fascia grafts preserved in formaldehyde have an insignificant irritating and inflammatory action on the intestinal loops compared with bovine pericardium, and do not induce the development of a significant abdominal adhesion process, this allowing their use in the abdominal fascial defects closure with placement in direct contact with the abdominal contents.

Bone Marrow-Derived Mesenchymal Stem Cells Enhance Bacterial Clearance and Preserve Bioprosthetic Integrity in a Model of Mesh Infection

Background:

The reported incidence of mesh infection in contaminated operative fields is as high as 30% regardless of the material used. Recently, mesenchymal stem cells (MSCs) have been shown to possess favorable immunomodulatory properties and improve tissue incorporation when seeded onto bioprosthetics. The aim of this study was to evaluate whether seeding noncrosslinked bovine pericardium (Veritas Collagen Matrix) with allogeneic bone marrow–derived MSCs improves infection resistance in vivo after inoculation with Escherichia coli (E. coli).

Methods:

Rat bone marrow–derived MSCs at passage 3 were seeded onto bovine pericardium and cultured for 7 days before implantation. Additional rats (n = 24) were implanted subcutaneously with MSC-seeded or unseeded mesh and inoculated with 7 × 10⁵ colony-forming units of E. coli or saline before wound closure (group 1, unseeded mesh/saline; group 2, unseeded mesh/E. coli; group 3, MSC-seeded mesh/E. coli; 8 rats per group). Meshes were explanted at 4 weeks and underwent microbiologic and histologic analyses.

Results:

MSC-seeded meshes inoculated with E. coli demonstrated superior bacterial clearance and preservation of mesh integrity compared with E. coli–inoculated unseeded meshes (87.5% versus 0% clearance; p = 0.001). Complete mesh degradation concurrent with abscess formation was observed in 100% of rats in the unseeded/E. coli group, which is in contrast to 12.5% of rats in the MSC-seeded/E. coli group. Histologic evaluation determined that remodeling characteristics of E. coli–inoculated MSC-seeded meshes were similar to those of uninfected meshes 4 weeks after implantation.

Conclusions:

Augmenting a bioprosthetic material with stem cells seems to markedly enhance resistance to bacterial infection in vivo and preserve mesh integrity.

Prosthetics and Techniques in Repair of Animal's Abdominal Wall

The management of abdominal wall repair continues to present a challenging problem, especially in the repair of major defects. Many abdominal wall defects can be repaired by primary closure; however, if the defect is large and there is a tension on the closure of the wound, the use of prosthetic materials becomes indispensable. Many studies have been performed with various materials and implant techniques, without the comparison of their degrees of success, based on sound meta-analysis and/or inclusive epidemiologic studies. This review covered the effectiveness of recent advances in prosthetic materials and implant procedures used in repair of abdominal wall, based on biomechanical properties and economic aspects of reconstructed large abdominal wall defects and hernias in animals. The presented results in this review helped to reach treatment algorithms that could maximize outcomes and minimize morbidity.

Systemic inflammatory cytokine analysis to monitor biomaterial augmented tissue healing

PURPOSE

Hernias can be repaired by reinforcement of damaged fascia using biomaterials to provide stabilisation. Repair materials are usually porous, through which cells infiltrate, proliferate and secrete ECM. Their efficacy relies on good tissue integration and resolution of host defence mechanisms. Therefore, understanding the dynamics by which biomaterials interact with tissue will provide knowledge to advance prosthesis design. Furthermore, determining host response in real time would provide significant advantage both clinically and scientifically over the current terminal process of histology.

METHODS

3 materials comprising synthetic and composite (synthetic materials hybridised with a resorbable biologic component) meshes were implanted into a rat full-thickness abdominal wall excision model. Their efficacy was evaluated using histopathology whilst also monitoring systemic concentrations of cytokines associated with inflammation and wound healing to predict material outcome over 12 weeks.

RESULTS

The noncomposite material (polyester) and Material B (polypropylene mesh with oligocaprone film and polydioxanone glue) stimulated the largest degree of adhesion from the 3 materials tested, although after 28 days adhesions were stronger to Material B. Histologically, all 3 materials integrated well with abdominal musculature and infiltrated completely with cells.

CONCLUSIONS

Analysis of systemic inflammation biomarkers confirmed inflammation elicited by surgeries and meshes irrespective of their composition. However, at an early postoperative endpoint (i.e., 1 week), some biomarkers, namely, IL-18 and RANTES, appeared to discriminate the noncomposite mesh from the composite materials, although in this study all materials successfully repaired the defects without recurrence or external indicators of postoperative chronic pain.

A systematic review of outcomes following repair of complex ventral incisional hernias with biologic mesh

Repair of contaminated/infected ventral incisional hernias is marked by high rates of recurrence, complications, and/or explantation of synthetic mesh. Biologic mesh products are recommended for repair to permit reconstruction and reduce complications. A systematic review of PubMed, EMBASE, and Cochrane databases identified English-language articles reporting postoperative outcomes (e.g., hernia recurrence, infection, mesh explantation) in patients undergoing contaminated/infected ventral incisional herniorrhaphy. Eleven studies met inclusion criteria and contained quantitative outcome data. All were retrospective chart reviews of biologic mesh use (mostly human acellular dermal matrix). Hernia recurrence and wound infection rates were highly variable and inconsistently reported across studies. Mesh explantation was rarely reported. Outcome variability is likely owing to heterogenous patient populations, surgical technique variations, and follow-up duration. Biologic mesh use in contaminated/infected herniorrhaphy was marked by low reported rates of secondary surgeries for infected mesh removal. Data from large, well-controlled, prospective trials with biologic mesh products are needed.

Assessing complications and cost-utilization in ventral hernia repair utilizing biologic mesh in a bridged underlay technique

BACKGROUND

The inability to reapproximate fascia in complex ventral hernia (CVH) repair remains challenging. Single-stage bridging reconstructions have been reported, however, with high rates of recurrence and wound complications. We describe a single-surgeon experience with bridging biologic CVH repair.

METHODS

We reviewed 37 patients undergoing CVH repair with bridging biologic mesh by the senior author from January 1, 2007 to January 1, 2013. Surgical history and operative characteristics were analyzed for predictors of hernia recurrence and wound complications.

RESULTS

Average age was 53 ± 15 years, body mass index was 31.1 ± 8.1 kg/m(2), and history of prior repair in 18 patients. Common indications were trauma, intra-abdominal infection, and prior intra-abdominal surgery. Incidence of wound complications was 51.4%, most commonly wound breakdown and infection. With average follow-up of 13 months, recurrence rate was 18.9% at an average of 8.2 months postoperatively. Analysis demonstrated postoperative wound infection as the only predictor of recurrence (odds ratio = 22.1, P = .017).

CONCLUSIONS

Hernia recurrence rate was 18.9% with bridged biologic CVH repairs, strongly associated with postoperative wound infection. This suggests that patients with postoperative infections may benefit from closer surveillance and more aggressive wound management.

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.

Bioprosthetic tissue matrices in complex abdominal wall reconstruction

Background:

Complex abdominal defects are difficult problems encountered by surgeons in multiple specialties. Although current evidence supports the primary repair of these defects with mesh reinforcement, it is unclear which mesh is superior for any given clinical scenario. The purpose of this review was to explore the characteristics of and clinical relevance behind bioprosthetic tissue matrices in an effort to better clarify their role in abdominal wall reconstruction.

Methods:

We reviewed the peer-reviewed literature on the use of bioprosthetic mesh in human subjects. Basic science articles and large retrospective and prospective reviews were included in author’s analysis. The clinical performance and characteristics of 13 bioprosthetic tissue matrices were evaluated.

Results:

The majority of the products evaluated perform well in contaminated fields, where the risk of wound-healing difficulties is high. Clinical outcomes, which included infection, reherniation, and bulge formation, were variable, and the majority of the studies had a mean follow-up of less than 24 months.

Conclusions:

Although bioprosthetic matrix has a multitude of indications within the growing field of abdominal wall reconstruction, the functionality, regenerative capacity, and long-term fate of these products have yet to be fully established. Furthermore, the clinical performance, indications, and contraindications for each type of matrix need to be fully evaluated in long-term outcome studies.

Long-term outcomes (>5-year follow-up) with porcine acellular dermal matrix (Permacol) in incisional hernias at risk for infection

PURPOSE

We reviewed retrospectively all patients undergoing abdominal wall reconstruction using porcine acellular dermal matrix (PADM) from 2004 to 2008 with follow-up assessment in 2012. Technique, short-term (infection, seroma, wound dehiscence), and long-term (mesh infection, recurrence) complications, and hernia recurrences were evaluated by physician examination ≥5 years postoperatively.

RESULTS

56 patients at high risk for infection had elective operation; nine had non-elective operation for complications of prior incisional hernia/hernia repair. Operations were clean, clean-contaminated, contaminated, or grossly infected in 49, 32, 12, and 6%, respectively. Techniques of repair included 10 onlay (six reinforced primary closures, four bridging patches), 47 sublay (20 reinforced primary closures, 27 bridging patches), six inlay, and two sandwich (sublay and onlay). Early complications (≤30 days postoperatively) occurred in 19 of the 65 patients (29%), including two prosthetic dehiscences from fascial attachment, 13 wound infections, and 4 seromas. After a mean follow-up of ≥5 years in 59 of 65 patients, physician-reported incidences of infection requiring removal of mesh or hernia recurrence were 25 and 66%, respectively. Hernia recurrence occurred in 12 of 26 (46%) patients with a reinforced repair and 27 of 33 (82%) with patched repairs. Mesh infection occurred in 7 of 24 patients with sublay patch and in 4 of 19 sublay reinforcement. The greatest recurrence rate was in contaminated (71%) and grossly infected wounds (100%), while recurrence rate was 63% in clean and 63% in clean-contaminated wounds.

CONCLUSIONS

At ≥5 years of follow-up, use of PADM as a bioprosthesis in ventral hernia in high-risk patients is unreliable as a definitive repair in the majority of patients, but may provide satisfactory outcomes in some patients.

A 5-year clinical experience with single-staged repairs of infected and contaminated abdominal wall defects utilizing biologic mesh

OBJECTIVE

Our objective was to evaluate the safety and durability of biologic mesh for single-staged reconstruction of contaminated fields.

INTRODUCTION

The presence of contamination during ventral hernia repair (VHR) poses a significant challenge. Some advocate for a multistaged reconstructive approach with delayed definitive repair, whereas others perform definitive repair at the initial operation.

METHODS

Patients undergoing single-staged VHR in a contaminated field with biologic mesh over a 5-year period were retrospectively reviewed from a prospectively maintained database. Outcome measures included wound complication and hernia recurrence.

RESULTS

A total of 128 patients (76 F, 52 M) were identified, with a mean age of 58.2 years, mean American Society of Anesthesiologist (ASA) score 3.1, and mean body mass index (BMI) 34.1 ± 9.7 kg/m2. Comorbidities included COPD (n = 29), diabetes (n = 65), smoking (n = 29), and immunosuppression (n = 8). Mean hernia defect size was 431 cm2 (range 40-2450 cm2). Reasons for contamination included the presence of infected mesh (n = 45), stoma (n = 24), concomitant gastrointestinal (GI) surgery (n = 17), enterocutaneous fistula (n = 25), open nonhealing wound(s) (n = 6), enterotomy/colotomy (n = 5), and chronic draining sinus (n = 6). Postoperative wound complications were identified in 61 (47.7%) patients. Predictors of wound complications included ASA score, diabetes, smoking, number of previous abdominal surgeries or hernia repairs, hernia defect size, and operative time. With a mean follow-up time of 21.7 months, hernia recurrence was identified in 40 (31.3%) patients. The majority of recurrent hernias were asymptomatic and 7 patients underwent repair.

CONCLUSIONS

Despite the high rate of wound morbidity associated with single-staged reconstruction of contaminated fields, it can safely be performed with biologic mesh reinforcement. Although biologic mesh in these situations is safe, the long-term durability seems to be less favorable.

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.

Repair of abdominal wall defects with biodegradable laminar prostheses: polymeric or biological?

Introduction

Biological and synthetic laminar absorbable prostheses are available for the repair of hernia defects in the abdominal wall. They share the important feature of being gradually degraded in the host, resulting in place the formation of a neotissue. This study was designed to assess the host tissue’s incorporation of collagen bioprostheses and a synthetic absorbable prosthesis.

Methods

Partial defects were created in the abdominal walls of 72 New Zealand rabbits and repaired using collagen bioprostheses Tutomesh® and Strattice® or a synthetic prosthesis Bio-A®. Specimens were collected for light microscopy, collagens gene and protein expression, macrophage response and biomechanical resistance at 14, 30, 90 and 180 days post-implantation.

Results

Tutomesh® and Bio-A® were gradually infiltrated by the host tissue and almost completely degraded by 180 days post-implantation. In contrast, Strattice® exhibited material encapsulation, no prosthetic degradation and low cell infiltration at earlier timepoints, whereas at later study time, collagen deposition could be observed within the mesh. In the short term, Bio-A® exhibited higher level of collagen 1 and 3 mRNA expression compared with the two other biological prostheses, which exhibited two peaks of higher expression at 14 and 90 days. The expression of collagen III was homogeneous throughout the study and collagen I deposition was more evident in Strattice®. Macrophage response decreased over time in biomeshes. However, in the synthetic mesh remained high and homogeneous until 90 days. The biomechanical analysis demonstrated the progressively increasing tensile strength of all biomaterials.

Conclusions

The tissue infiltration of laminar absorbable prostheses is affected by the structure and composition of the mesh. The synthetic prosthesis exhibited a distinct pattern of tissue incorporation and a greater macrophage response than did the biological prostheses. Of all of the laminar, absorbable biomaterials that were tested in this study, Strattice® demonstrated the optimal levels of integration and degradation.

The role of biologic mesh in abdominal wall reconstruction: a systematic review of the current literature

BACKGROUND

Biologic mesh in the form of allograft or xenograft products have been used in complicated abdominal hernia repair, but few comparative studies exist.

METHODS

A systematic review of original incisional hernia studies was conducted to include 2 primary end points: hernia recurrence and surgical site occurrence. Analysis of variance and a Satterthwaite t test compared the devices.

RESULTS

Twenty-nine studies were included in this analysis, which included 1,257 patients. The total number of studies and the total subjects for each device include the following: Permacol (Tissue Science Laboratories, Hampshire, UK) (4/64), Surgisis (Cook Medical, Bloomington, IN) (3/87), and Alloderm (LifeCell, Corp, Branchburg, NJ) (23/1,106). Device-specific recurrence rates and surgical site occurrence rates, respectively, were as follows: Alloderm (20.8%, 31.4%), Permacol (10.9%, 25%), and Surgisis (8.0%, 40.2%). A Satterthwaite t test comparison revealed significantly higher numbers of hernia recurrence (P = .006) and surgical site occurrence (P = .04) when comparing Alloderm with Permacol.

CONCLUSIONS

Biologic mesh does play a beneficial role in abdominal wall reconstruction although allograft acellular dermal matrix does have a higher recurrence rate as compared with xenograft products, which limits its current role in hernia repair.

A preliminary comparison study of two noncrosslinked biologic meshes used in complex ventral hernia repairs

BACKGROUND

The biologic materials currently available for hernia repairs are costly and there are limited statistics on recurrences and rates of infection in connection with their use in complex cases.

METHODS

We performed a retrospective review and comparison of two types of biologic mesh used at our institution for abdominal hernia repairs spanning a 1-year period. Demographic data and outcomes relating to surgical site infections, hernia recurrences, and mortality were analyzed. Of the 35 patients in the study, 23 patients (Group I) were managed with SurgiMend, a neonatal bovine mesh, and 12 patients (Group II) were managed with Flex HD, a human-derived mesh.

RESULTS

The study cohorts met criteria for high-risk stratification based on body mass index, comorbid conditions, and a high prevalence of contaminated wounds. The overall surgical site infection rate was 17 % for Group I and 50 % for Group II. These differences reached statistical significance when comparing superficial infections but not for deep infections with mesh involvement. Hernia recurrences in Group I were 5 % compared to 33 % in Group II. No deaths were observed.

CONCLUSIONS

These preliminary data demonstrate promising short-term outcomes for high-risk complex hernias repaired with biologic mesh, particularly SurgiMend, but the long-term durability of these biological materials is yet to be determined.

A review of available prosthetic material for abdominal wall repair

Abdominal wall incisional and inguinal hernia repair can call for utilization of implants or prostheses as an alternative to simple suture techniques. The various implants can be synthetic, biologic or mixed: their physicochemical properties condition the mechanical results and the long-term outcome of the repair. The increasing number of available materials allows the surgeon to choose between a wide variety depending on the indication, the site of implantation, the surgical approach and whether the operative field is contaminated or not. With regard to evidence-based medicine, while several synthetic implants have been shown to be superior in efficacy to simple suture, other studies are underway to develop the indications for bioprostheses, in particular in contaminated fields. This review of the literature summarizes the current knowledge on synthetic and biologic implants (physicochemical characteristics, forms, indications).

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 bovine pericardium graft for abdominal wall reconstruction in contaminated fields

AIM: To employ, in such conditions, a biological graft such as bovine pericardium that offers resistance to infection.

METHODS: In our surgical department, from January 2006 to June 2010, 48 patients underwent abdominal wall reconstruction using acellular bovine pericardium; of these 34 patients had a contaminated wound due to diffuse peritonitis (complicated diverticulitis, bowel perforation, intestinal infarction, strangled hernia, etc.) and 14 patients had hernia relapse on infected synthetic mesh.

RESULTS: In our series, one patient died of multi-organ failure 3 d after surgery. After placement of the pericardium mesh four cases of hernia relapse occurred.

CONCLUSION: Recurrence rate is similar to that of prosthetic mesh repair and the application of acellular bovine pericardium (Tutomesh^®, Tutogen Medical Gmbh Germany) is moreover a safe and feasible option that can be employed to manage complicated abdominal wall defects where prosthetic mesh is unsuitable.

Experience with titanium devices for rib fixation and coverage of chest wall defects

OBJECTIVES

To describe our experience with two new titanium-based devices for chest wall reconstruction and stabilization.

METHODS

A retrospective analysis of 18 consecutive patients (multiple rib fractures n = 9, iatrogenic rib fracture n = 2, lung herniation n = 2, chest wall tumour n = 5) who underwent surgery for rib fractures or chest wall tumours requiring chest wall resection and reconstruction between October 2010 and March 2012 was conducted. Chest wall defects and rib fractures were fixed with titanium clips and bars or titanium plates and screws through a posterolateral thoracotomy.

RESULTS

There were 12 males, and the median age was 61 years. There were no postoperative deaths. The only postoperative complication observed was a pleural effusion requiring drainage in one patient who had titanium clips for the fixation of multiple traumatic rib fractures. Median length of stay of the drain and median length of hospital stay were 3 days (range 1-6) and 4 days (range 2-42 days), respectively. The average follow-up period of operatively managed patients was 6 months, (range 2-14 months). Two cases of hardware failure occurred in two patients treated for a lung hernia with large chest wall defects involving the anterior costal margin with either devices.

CONCLUSIONS

Titanium devices (clips and bars; screws and plates) are effective and safe for repair of rib fractures and large chest wall defect reconstruction with minimal complications and good long-term results.

Biomechanical and structural changes following the decellularization of bovine pericardial tissues for use as a tissue engineering scaffold

To achieve natural scaffolds for tissue engineering applications we decellularized bovine pericardial (BP) tissues according to two different protocols: a novel treatment based on Triton(®) X-100 (12 h, 4 °C) (BP1) and a trypsin/EDTA treatment (37 °C, 48 h) (BP2). Results were compared with commercially available acellular xenogeneic biomaterials, Veritas(®) and Collamed(®). Biomechanical characteristics, high (E(h)) and low (E(l)) modulus of elasticity, of the fresh untreated tissue varied with the anatomical direction (apex to base (T) to transverse (L)) (mean ± SDEV): (41.63 ± 14.65-48.12 ± 10.19 MPa and 0.27 ± 0.05-0.30 ± 0.12 MPa respectively). BP1 had no mechanical effect (44.65 ± 19.73-52.67 ± 7.59 MPa and 0.37 ± 0.14-0.37 ± 0.11 MPa, respectively) but BP2 resulted in significant decrease in E(h) and E(l) (20.96 ± 8.17-36.82 ± 3.23 MPa and 0.20 ± 0.06-0.23 ± 0.06 MPa). Hysteresis ratio (h) varied (19-26 % of the loading energy) independently of anatomical direction. Glycosaminoglycans content was unaffected by BP1, while 22 % of chondroitin/dermatan sulphate and 60 % of hyaluronan were removed after BP2 treatment. Endothelial cell adhesion was achieved after 24 h and 3 days cell culture.

[Biological implants in abdominal wall hernia surgery]

Permanent synthetic materials are currently of choice for abdominal wall hernia repair. However, they are not ideal as short- and long-term complications with these have been reported. Extracellular matrix-derived biological implants (EMDBI) have emerged as a result of research and development into new materials. Several types of EMDBI have appeared in the last few years, each with its own manufacture characteristics and different from the rest. The current panorama of the xenogeneic EMDBI available in Spain is analysed, their complications, the unknown factors arising in the long-term, and the clinical experience available on incisional and inguinal hernias.

Biological meshes: a review of their use in abdominal wall hernia repairs

PURPOSE

Biological meshes are mostly used in infected fields within complex abdominal wall hernia repairs. There is no consensus, however, on the most appropriate material to be used in a given situation.

METHODS

A literature review of published articles reporting the utilization of biological meshes in ventral/incisional hernia repair was conducted. Data were analyzed to compare the recurrence rates obtained with biological meshes.

MAIN FINDINGS

Only a few prospective comparative studies were identified. Most publications relate to AlloDerm®, Permacol™ and Surgisis™ with data from other meshes insufficient to draw conclusions. AlloDerm has a 0-100% recurrence rate among studies. It compares poorly with Surgisis and results in an unfavorable outcome when used as a 'bridge prosthesis'. Permacol has consistent recurrence rates of 0-15%, whatever the patients' profiles or the context of infected fields, when considering the most relevant studies. The Surgisis results are more conflicting: the mesh exhibits low recurrence rates in clean fields, but in infected fields the recurrence rate is up to 39%.

CONCLUSION

Taken together, these studies suggest that the cross-linked mesh, Permacol has the lowest failure rate and the longest time to failure, particularly in contaminated or infected fields. However, this data should be confirmed by large prospective randomized studies.

Bovine pericardium retail preserved in glutaraldehyde and used as a vascular patch

Background

In this study we evaluated the performance of bovine pericardium preserved in glutaraldehyde used as a vascular patch.

Methods

Fourteen young pigs, six females and eight males, weighting 10.3 - 18.4 kg were used in our study. We implanted three remnants in each pig, two in the abdominal aorta and one was juxtaposed to the peritoneum. The smooth face (SF) and rough face (RF) of each remnant were implanted turned to the vessel inner portion and one remnant was juxtaposed to the peritoneum. The animals were sacrificed in 4.5 - 8 months after surgery (75 - 109 kg). The remnants were assessed for aorta wall, fibroses formation in inner apposition and calcification related to the face turned to the vessel inner portion.

Results

The rough face showed a lower dilatation level compared to the face implanted in adjacent aorta. There was no difference between intensity and/or incidence of graft calcification when the superficies were compared. The bovine pericardium preserved in glutaraldehyde did not show alterations in its structure when implanted with different faces turned to the inner portion of vessel.

Conclusion

When turned to the inner portion of the vessel, the rough face of the remnant presented a lower dilatation in relation to the adjacent aorta and a better quality of endothelium layer and did not show a difference between intensity and/or incidence of graft calcification.

Does Veritas® play a role in breast reconstruction? a case report

To reduce operative times and surgical complications in implant-based breast reconstruction, many authors advocate the use of exogenous material (modified xenograft) to support tissue regeneration. In this article, a case is presented in which a bovine collagen patch (Veritas® Collagen Matrix; Synovis Surgical Innovations, St Paul, MN) was used in the immediate breast reconstruction with an implant. The good results obtained in this case confirm Veritas® as a viable alternative to AlloDerm® Regenerative Tissue Matrix (LifeCell Corporation, Branchburg, NJ) and further support its ability to sustain and stimulate recovery of the surrounding tissues.