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

Outcomes of Retromuscular Porcine Biologic Mesh Repairs Using Transversus Abdominis Release Reconstruction

BACKGROUND

Optimal mesh reinforcement and operative technique for major abdominal wall reconstructions (AWR) remain debatable. Posterior component separation via transversus abdominis release (TAR) allows for wide sublay mesh reinforcement with durable reconstruction, and has been gaining popularity in recent years. Although biologic mesh has been associated with mixed results, outcomes of AWR with bioprosthetics have not been well elucidated to date. We evaluated our outcomes of TAR reconstructions with retromuscular porcine biologic mesh reinforcement.

STUDY DESIGN

Consecutive patients undergoing AWR using TAR with biologic mesh sublay reinforcement were identified in our prospective databases and analyzed. We characterized patient demographics and perioperative details. Main outcomes measures included wound complications and hernia recurrence.

RESULTS

Between 2007 and 2014, seventy-seven patients (mean age 56 years, mean BMI 35 kg/m(2)) underwent AWR using TAR with biologic mesh. Mean hernia size was 306 ± 128 cm(2) with mean width of 14.3 ± 3.3 cm. The vast majority of patients had grade 3 hernias (92%) and more than half had a history of wound infection (55%). There were 22 (28.6%) surgical site infections consisting of 14 deep, 7 superficial, and 1 organ-space surgical site infections. There were no incidences of chronic mesh infection or explantation. In patients with at least 12 months follow-up (mean duration 28.2 months), there were 8 (12.5%) recurrences.

CONCLUSIONS

Complex hernias repaired with TAR and retromuscular porcine biologic mesh reinforcement are associated with a low rate of serious perioperative wound/mesh complications. Additionally, our approach resulted in a fairly low rate of hernia recurrences in this complex cohort of patients. We believe that the TAR approach and retromuscular mesh placement can be beneficial when biologic mesh reinforcement is chosen during complex and/or contaminated abdominal wall reconstructions.

In Vitro Enzymatic Degradation of Tissue Grafts and Collagen Biomaterials by Matrix Metalloproteinases: Improving the Collagenase Assay

Matrix metalloproteinase-1 and -8 are active during the wound healing and remodelling processes, degrading native extracellular matrix and implantable devices. However, traditional in vitro assays utilize primarily matrix metalloproteinase-1 to mimic the in vivo degradation microenvironment. Herein, we assessed the influence of various concentrations of matrix metalloproteinase- 1 and 8 (50, 100, and 200 U/mL) as a function of pH (5.5 and 7.4) and time (3, 6, 9, 12, and 24 h) on the degradation profile of three tissue grafts (chemically cross-linked Permacol, nonchemically cross-linked Permacol and nonchemically cross-linked Strattice) and a collagen biomaterial (nonchemically cross-linked collagen sponge). Chemically cross-linked and nonchemically cross-linked Permacol samples exhibited the highest resistance to enzymatic degradation, while nonchemically cross-linked collagen sponges exhibited the least resistance to enzymatic degradation. Qualitative and quantitative degradation analysis of all samples revealed a similar degradation profile over time, independently of the matrix metalloproteinase used and its respective concentration and pH. These data indicate that matrix metalloproteinase-1 and matrix metalloproteinase-8 exhibit similar degradation profile in vitro, suggesting that matrix metalloproteinase-8 should be used for collagenase assay.

Cost of ventral hernia repair using biologic or synthetic mesh

BACKGROUND

Patients undergoing ventral hernia repair (VHR) with biologic mesh (BioM) have higher hospital costs compared with synthetic mesh (SynM). This study compares 90-d pre- and post-VHR hospital costs (180-d) among BioM and SynM based on infection risk.

METHODS

This retrospective National Surgical Quality Improvement Program study matched patient perioperative risk with resource utilization cost for a consecutive series of VHR repairs. Patient infection risks, clinical and financial outcomes were compared in unmatched SynM (n = 303) and BioM (n = 72) groups. Propensity scores were used to match 35 SynM and BioM pairs of cases with similar infection risk for outcomes analysis.

RESULTS

BioM patients in the unmatched group were older with higher American Society of Anesthesiologists (ASA) and wound classification, and they more frequently underwent open repairs for recurrent hernias. Wound surgical site infections were more frequent in unmatched BioM patients (P = 0.001) as were 180-d costs ($43.8k versus $14.0k, P < 0.001). Propensity matching resulted in 31 clean cases. In these low-risk patients, wound occurrences and readmissions were identical, but 180-d costs remained higher ($31.8k versus $15.5k, P < 0.001). There were no differences in hospital 180-d diagnostic, emergency room, intensive care unit, floor, pharmacy, or therapeutic costs. However, 180-d operating room services and supply costs were higher in the BioM group ($21.1k versus $7.1k, P < 0.001).

CONCLUSIONS

BioM is used more commonly in hernia repairs involving higher wound class and ASA scores and recurrent hernias. Clinical outcomes after low-risk VHRs are similar; SynM utilization in low-risk hernia repairs was more cost-effective.

Emerging Implications for Extracellular Matrix-Based Technologies in Vascularized Composite Allotransplantation

Despite recent progress in vascularized composite allotransplantation (VCA), limitations including complex, high dose immunosuppression regimens, lifelong risk of toxicity from immunosuppressants, acute and most critically chronic graft rejection, and suboptimal nerve regeneration remain particularly challenging obstacles restricting clinical progress. When properly configured, customized, and implemented, biomaterials derived from the extracellular matrix (ECM) retain bioactive molecules and immunomodulatory properties that can promote stem cell migration, proliferation and differentiation, and constructive functional tissue remodeling. The present paper reviews the emerging implications of ECM-based technologies in VCA, including local immunomodulation, tissue repair, nerve regeneration, minimally invasive graft targeted drug delivery, stem cell transplantation, and other donor graft manipulation.

Inhibition of COX1/2 alters the host response and reduces ECM scaffold mediated constructive tissue remodeling in a rodent model of skeletal muscle injury

Extracellular matrix (ECM) has been used as a biologic scaffold material to both reinforce the surgical repair of soft tissue and serve as an inductive template to promote a constructive tissue remodeling response. Success of such an approach is dependent on macrophage-mediated degradation and remodeling of the biologic scaffold. Macrophage phenotype during these processes is a predictive factor of the eventual remodeling outcome. ECM scaffolds have been shown to promote an anti-inflammatory or M2-like macrophage phenotype in vitro that includes secretion of downstream products of cycolooxygenases 1 and 2 (COX1/2). The present study investigated the effect of a common COX1/2 inhibitor (Aspirin) on macrophage phenotype and tissue remodeling in a rodent model of ECM scaffold treated skeletal muscle injury. Inhibition of COX1/2 reduced the constructive remodeling response by hindering myogenesis and collagen deposition in the defect area. The inhibited response was correlated with a reduction in M2-like macrophages in the defect area. The effects of Aspirin on macrophage phenotype were corroborated using an established in vitro macrophage model which showed a reduction in both ECM induced prostaglandin secretion and expression of a marker of M2-like macrophages (CD206). These results raise questions regarding the common peri-surgical administration of COX1/2 inhibitors when biologic scaffold materials are used to facilitate muscle repair/regeneration.

STATEMENT OF SIGNIFICANCE

COX1/2 inhibitors such as nonsteroidal anti-inflammatory drugs (NSAIDs) are routinely administered post-surgically for analgesic purposes. While COX1/2 inhibitors are important in pain management, they have also been shown to delay or diminish the healing process, which calls to question their clinical use for treating musculotendinous injuries. The present study aimed to investigate the influence of a common NSAID, Aspirin, on the constructive remodeling response mediated by an ECM scaffold (UBM) in a rat skeletal muscle injury model. The COX1/2 inhibitor, Aspirin, was found to mitigate the ECM scaffold-mediated constructive remodeling response both in an in vitro co-culture system and an in vivo rat model of skeletal muscle injury. The results presented herein provide data showing that NSAIDs may significantly alter tissue remodeling outcomes when a biomaterial is used in a regenerative medicine/tissue engineering application. Thus, the decision to prescribe NSAIDs to manage the symptoms of inflammation post-ECM scaffold implantation should be carefully considered.

Mesh Infection and Hernia Repair: A Review

BACKGROUND

The use of a prosthetic mesh to repair a tissue defect may produce a series of post-operative complications, among which infection is the most feared and one of the most devastating. When occurring, bacterial adherence and biofilm formation on the mesh surface affect the implant's tissue integration and host tissue regeneration, making preventive measures to control prosthetic infection a major goal of prosthetic mesh improvement.

METHODS

This article reviews the literature on the infection of prosthetic meshes used in hernia repair to describe the in vitro and in vivo models used to examine bacterial adherence and biofilm formation on the surface of different biomaterials. Also discussed are the prophylactic measures used to control implant infection ranging from meshes soaked in antibiotics to mesh coatings that release antimicrobial agents in a controlled manner.

RESULTS

Prosthetic architecture has a direct effect on bacterial adherence and biofilm formation. Absorbable synthetic materials are more prone to bacterial colonization than non-absorbable materials. The reported behavior of collagen biomeshes, also called xenografts, in a contaminated environment has been contradictory, and their use in this setting needs further clinical investigation. New prophylactic mesh designs include surface modifications with an anti-adhesive substance or pre-treatment with antibacterial agents or metal coatings.

CONCLUSIONS

The use of polymer coatings that slowly release non-antibiotic drugs seems to be a good strategy to prevent implant contamination and reduce the onset of resistant bacterial strains. Even though the prophylactic designs described in this review are mainly focused on hernia repair meshes, these strategies can be extrapolated to other implantable devices, regardless of their design, shape or dimension.

Strategies for skeletal muscle tissue engineering: seed vs. soil

The most commonly used tissue engineering approach includes the ex vivo combination of site-appropriate cell(s) and scaffold material(s) to create three-dimensional constructs for tissue replacement or reconstruction. These three-dimensional combinations are typically subjected to a period of culture and conditioning (i.e., self-assembly and maturation) to promote the development of ex vivo constructs which closely mimic native target tissue. This cell-based approach is challenged by the host response to the engineered tissue construct following surgical implantation. As an alternative to the cell-based approach, acellular biologic scaffolds attract endogenous cells and remodel into partially functional mimics of native tissue upon implantation. The present review examines cell-types (i.e., seed), scaffold materials (i.e., soil), and challenges associated with functional tissue engineering. Skeletal muscle is used as the target tissue prototype but the discussed principles will largely apply to most body systems.

Component Separation vs. Bridged Repair for Large Ventral Hernias: A Multi-Institutional Risk-Adjusted Comparison, Systematic Review, and Meta-Analysis

BACKGROUND

Repair of large ventral hernia defects is associated with high rates of surgical site occurrences (SSO), including surgical site infection (SSI), site dehiscence, seroma, hematoma, and site necrosis. Two common operative strategies exist: Component separation (CS) with primary fascial closure and mesh reinforcement (PFC-CS) and bridged repair (mesh spanning the hernia defect). We hypothesized that: (1) ventral hernia repair (VHR) of large defects with bridged repair is associated with more SSOs than is PFC, and (2) anterior CS is associated with more SSOs than is endoscopic, perforator-sparing, or posterior CS.

METHODS

Part I of this study was a review of a multi-center database of patients who underwent VHR of a defect ≥8 cm from 2010-2011 with at least one month of follow-up. The primary outcome was SSO. The secondary outcome was recurrence. Part II of this study was a systematic review and meta-analysis of studies comparing bridged repair with PFC and studies comparing different kinds of CS.

RESULTS

A total of 108 patients were followed for a median of 16 months (range 1-50 months), of whom 84 underwent PFC-CS and 24 had bridged repairs. Unadjusted results demonstrated no differences between the groups in SSO or recurrence; however, the study was underpowered for this purpose. On meta-analysis, PFC was associated with a lower risk of SSO (odds ratio [OR] = 0.569; 95% confidence interval [CI] = 0.34-0.94) and recurrence (OR = 0.138; 95% CI = 0.08-0.23) compared with bridged repair. On multiple-treatments meta-analysis, both endoscopic and perforator-sparing CS were most likely to be the treatments with the lowest risk of SSO and recurrence.

CONCLUSIONS

Bridged repair was associated with more SSOs than was PFC, and PFC should be used whenever feasible. Endoscopic and perforator-sparing CS were associated with the fewest complications; however, these conclusions are limited by heterogeneity between studies and poor methodological quality. These results should be used to guide future trials, which should compare the risks and benefits of each CS method to determine in which setting each technique will give the best results.

Complex ventral hernia repair with a human acellular dermal matrix and component separation: A case series

We present a case series of 19 patients requiring complex abdominal hernia repairs. Patients presented with challenging clinical histories with 95% having multiple significant comorbidities including overweight or obesity (84%), hypertension (53%), diabetes (42%), cancer (26%), and pulmonary disease (16%). The majority of patients (68%) had prior abdominal infections and 53% had at least one failed prior hernia repair. Upon examination, fascial defects averaged 282 cm². Anterior and posterior component separation was performed with placement of a human acellular dermal mesh. Midline abdominal closure under minimal tension was achieved primarily in all cases. Post-operative complications included 2 adverse events (11%) – one pulmonary embolism and one post-operative hemorrhage requiring transfusion; 6 wound-related complications (32%), 1 seroma (5%) and 1 patient with post-operative ileus (5%). Operative intervention was not required in any of the cases and most patients made an uneventful recovery. Increased patient age and longer OR time were independently predictive of early post-operative complications. At a median 2-year follow-up, three patients had a documented hernia recurrence (16%) and one patient was deceased due to unrelated causes.

Conclusion

Patients at high risk for post-operative events due to comorbidities, prior abdominal infection and failed mesh repairs do well following component separation reinforced with a human bioprosthetic mesh. Anticipated post-operative complications were managed conservatively and at a median 2-year follow-up, a low rate of hernia recurrence was observed with this approach.

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Intraperitoneal placement of acellular dermal matrix using component separation.

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Acceptable recurrence rates of 16% at 2 years of follow up.

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Correlation in age and complication chances.

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Retrorectus technique possibly the best surgical technique for hernia repair.

One year experience of swine dermal non-crosslinked collagen prostheses for abdominal wall repairs in elective and emergency surgery

Introduction

The approach to the abdominal wall surgical repair is dramatically changed in the last years. This study evaluates our institutional outcomes about the usage of biological meshes for abdominal wall repair in different setting: in elective surgery, in emergency surgery and in abdominal wall repair following open abdomen (OA) procedure.

Methods

A database was prospectively conducted (January–December 2014) and data were reviewed for patients who underwent to an abdominal wall reconstruction with swine dermal non-cross linked collagens prostheses either in elective or emergency setting, and following OA/laparostomy procedure. Demographic data, co-morbidities, indications for surgery, intra-operative details, post-operative complications and outcome (peri-operative, 3, 6, 9-months) were analyzed.

Results

A total of 30 cases were reported: 9 in elective surgery (Group 1), 4 in emergency surgery (Group 2) and 17 with abdominal wall closure following OA management (Group 3). Two meshes were removed: 1 in the Group 1 and 1 in the Group 3. During follow-up only one patient in the Group 3 had a recurrence of the incisional hernia. Mortality rate was 11.1 % at 3 months in Group 1, 0 % in the Group 2, and 29.4 % in peri-operative period in the Group 3.

Conclusions

The use of non-cross linked biological meshes can be safe and versatile in different situations from elective to emergency surgery, and also for the reconstruction of the abdominal wall after OA procedure, with an acceptable recurrence and mortality rate.

The role of the open abdomen procedure in managing severe abdominal sepsis: WSES position paper

The open abdomen (OA) procedure is a significant surgical advance, as part of damage control techniques in severe abdominal trauma. Its application can be adapted to the advantage of patients with severe abdominal sepsis, however its precise role in these patients is still not clear. In severe abdominal sepsis the OA may allow early identification and draining of any residual infection, control any persistent source of infection, and remove more effectively infected or cytokine-loaded peritoneal fluid, preventing abdominal compartment syndrome and deferring definitive intervention and anastomosis until the patient is appropriately resuscitated and hemodynamically stable and thus better able to heal. However, the OA may require multiple returns to the operating room and may be associated with significant complications, including enteroatmospheric fistulas, loss of abdominal wall domain and large hernias. Surgeons should be aware of the pathophysiology of severe intra-abdominal sepsis and always keep in mind the option of using open abdomen to be able to use it in the right patient at the right time.

Treatment of foregut fistula with biologic plugs

INTRODUCTION

Enteric fistulas are a recognised complication of various diseases and surgical interventions. Non-operative medical management will result in closure of 60-70% of all fistulas over a six- to eight-week period, those that fail non-operative management will require operative intervention if they are to close. We present a series of upper gastrointestinal fistula managed with endoscopic intervention and insertion of biological fistula plug over a 3-year period across three Hospitals, both public and private, in Western Australia.

METHODS

Over a three-year period, 14 patients were referred for treatment of acute or persistent foregut fistulas. All fistulas were managed with endoscopic intervention and insertion of a porcine small intestine sub-mucosa plug (Biodesign (®) Cook medical Inc., Bloomington, IN, USA). No patients with fistula were excluded. Data were collected on patient demographics and underlying diagnosis. The biological plugs were deployed using three different endoscopic techniques (direct deployment via the endoscope, catheter-assisted endoscopic deployment, or a pull through via a guide wire using a rendezvous technique).

RESULTS

Fourteen patients with foregut fistula were treated using biological plugs. The age of the fistulas treated ranged from 14 days to 3 years. The fistulas were predominantly gastric in origin (eight cases). Three oesophageal, one gastro-pleural-bronchial, and two jejunal fistulas were also managed using this technique. Of the 14 fistulas treated using this method, 13 resolved following the treatment. Median time to closure of the fistula was 2 days (range 1-120 days). Three patients required more than one intervention to complete closure.

CONCLUSION

Biological plugs offer a further option for management of the traditionally difficult foregut fistula, without major morbidity associated with other treatment modalities. It is limited to the ability to deploy the plug endoscopically.

Type I collagen as an extracellular matrix for the in vitro growth of human small intestinal epithelium

Background

We previously reported in vitro maintenance and proliferation of human small intestinal epithelium using Matrigel, a proprietary basement membrane product. There are concerns over the applicability of Matrigel-based methods for future human therapies. We investigated type I collagen as an alternative for the culture of human intestinal epithelial cells.

Methods

Human small intestine was procured from fresh surgical pathology specimens. Small intestinal crypts were isolated using EDTA chelation. Intestinal subepithelial myofibroblasts were isolated from a pediatric sample and expanded in vitro. After suspension in Matrigel or type I collagen gel, crypts were co-cultured above a confluent layer of myofibroblasts. Crypts were also grown in monoculture with exposure to myofibroblast conditioned media; these were subsequently sub-cultured in vitro and expanded with a 1∶2 split ratio. Cultures were assessed with light microscopy, RT-PCR, histology, and immunohistochemistry.

Results

Collagen supported viable human epithelium in vitro for at least one month in primary culture. Sub-cultured epithelium expanded through 12 passages over 60 days. Histologic sections revealed polarized columnar cells, with apical brush borders and basolaterally located nuclei. Collagen-based cultures gave rise to monolayer epithelial sheets at the gel-liquid interface, which were not observed with Matrigel. Immunohistochemical staining identified markers of differentiated intestinal epithelium and myofibroblasts. RT-PCR demonstrated expression of α-smooth muscle actin and vimentin in myofibroblasts and E-Cadherin, CDX2, villin 1, intestinal alkaline phosphatase, chromogranin A, lysozyme, and Lgr5 in epithelial cells. These markers were maintained through several passages.

Conclusion

Type I collagen gel supports long-term in vitro maintenance and expansion of fully elaborated human intestinal epithelium. Collagen-based methods yield familiar enteroid structures as well as a new pattern of sheet-like growth, and they eliminate the need for Matrigel for in vitro human intestinal epithelial growth. Future research is required to further develop this cell culture system for tissue engineering applications.

A review of biocompatibility in hernia repair; considerations in vitro and in vivo for selecting the most appropriate repair material

PURPOSE

Repair of hernia typically makes use of a prosthetic material; synthetic or biologic in nature. Any material which enters the body is subject to interrogation by the inflammation and immune system in addition to numerous other cell families, the outcome of which ultimately determines the success of the repair. In this review, we discuss the fundamental biology which occurs in situ when a biomaterial associates with a tissue, compare and contrast the techniques available to predict this in vitro, and review how features of hernia repair materials specifically may manipulate tissue interrogation and integration. Finally, we conclude our article by examining how biocompatibility impacts surgical practise and how a better understanding of the manner by which materials and tissues interact could benefit hernia repair.

MATERIALS AND METHODS

A review of the literature was conducted using appropriate scientific search engines in addition to inclusion of findings from the groups' primary research.

RESULTS

Using pre-clinical assays to anticipate the biocompatibility of a medical device is critical; however, to maximise the scientific power of in vitro findings, we must carefully consider the in vivo niche of the cells with which we are working. Excessive in vitro culture or contact to non-self materials can add compounding complexity to studies involving leucocytes for instance; therefore, we must ensure careful and stringent assay design when developing techniques for assaying pre-clinical biocompatibility. Furthermore, many of the features associated with hernia repair material design specifically, included to enhance their mechanical or biodegradation characteristics, are inadvertently instructive to cells, and therefore, throughout the prototype stages of a materials development, regular biocompatibility assessment must be performed.

CONCLUSION

The biocompatibility of a material is rate limiting in its ability to function as a medical device. The future of hernia repair materials will rely on close cohesion between the surgical and scientific communities to ensure the most robust biocompatibility assessment techniques, and models are utilised to predict the efficacy of a given material in a particular surgical application.

Biologic scaffolds for regenerative medicine: mechanisms of in vivo remodeling

Successful regenerative medicine strategies for functional tissue reconstruction include the in situ placement of acellular materials composed of the extracellular matrix (ECM) or individual components of the ECM. The composition and ultrastructure of these materials vary depending on multiple factors including the tissue source and species from which the materials are harvested, the methods of manufacture, the efficiency of decellularization, post-processing modifications such as chemical cross-linking or solubilization, and the methods of terminal sterilization. Appropriately configured materials have the ability to modulate different stages of the healing response by inducing a shift from a process of inflammation and scar tissue formation to one of constructive remodeling and functional tissue restoration. The events that facilitate such a dramatic change during the biomaterial-host interaction are complex and necessarily involve both the immune system and mechanisms of stem cell recruitment, growth, and differentiation. The present manuscript reviews the composition of biologic scaffolds, the methods and recommendations for manufacture, the mechanisms of the biomaterial-host interaction, and the clinical application of this regenerative medicine approach.

Long-term outcome of biologic graft: a case report

INTRODUCTION

Biologic grafts have been shown to support tissue regeneration in various animal models. Very few reports in the literature exist to show tissue remodeling in patients after placement of a biologic graft.

CASE PRESENTATION

We report the case of a 69-year-old Caucasian man with a history of small bowel carcinoid resection and concurrent recurrent ventral hernia repair with component separation and underlay biologic graft placement who underwent re-operation for metastatic carcinoid tumor to his liver. Complete incorporation of the biologic graft was observed. Tissue analysis of the incised midline fascia revealed tissue remodeling at the site of the previous abdominal wall defect.

CONCLUSION

Placement of a biologic graft in ventral hernia repair supports tissue regeneration similar to that previously reported in animal models.

Delayed primary closure of contaminated abdominal wall defects with non-crosslinked porcine acellular dermal matrix compared with conventional staged repair: a retrospective study

INTRODUCTION

Synthetic mesh has been used traditionally to repair abdominal wall defects, but its use is limited in the case of bacterial contamination. New biological materials are now being used successfully for delayed primary closure of contaminated abdominal wall defects. The costs of biological materials may prevent surgeons from using them. We compared the conventional staged repair of contaminated abdominal wall defects with a single-stage procedure using a non-crosslinked porcine acellular dermal matrix.

METHODS

A total of 14 cases with Grade 3 contaminated abdominal wall defects underwent delayed primary closure of the abdomen using a non-crosslinked porcine acellular dermal matrix (Strattice™ Reconstructive Tissue Matrix, LifeCell Corp., Branchburg, NJ, USA). The results were compared with a group of 14 patients who had received conventional treatment for the repair of contaminated abdominal wall defects comprising a staged repair during two separate hospital admissions employing synthetic mesh. Treatment modalities, outcomes, and costs were compared.

RESULTS

In all cases treated with delayed primary closure employing non-crosslinked porcine acellular dermal matrix, there were no complications related to its use. Two patients died due to unrelated events. Although treatment costs were estimated to be similar in the two groups, the patients treated with porcine acellular dermal matrix spent less time as an inpatient than those receiving conventional two-stage repair.

CONCLUSIONS

Delayed primary closure of contaminated abdominal wall defects using a non-crosslinked porcine acellular dermal matrix may be a suitable alternative to conventional staged repair. In our patients, it resulted in early restoration of abdominal wall function and shorter hospitalization. The costs for treating contaminated abdominal wall defects using porcine acellular dermal matrix during a single hospital admission were not higher than costs for conventional two-stage repair. Further randomized studies are needed to expand upon these findings.

Current concept of abdominal sepsis: WSES position paper

Although sepsis is a systemic process, the pathophysiological cascade of events may vary from region to region.

Abdominal sepsis represents the host’s systemic inflammatory response to bacterial peritonitis.

It is associated with significant morbidity and mortality rates, and is the second most common cause of sepsis-related mortality in the intensive care unit.

The review focuses on sepsis in the specific setting of severe peritonitis.

Use of a Bioprosthetic Mesh in Complex Hernia Repair

Background. Implantation of synthetic meshes for reinforcement of abdominal wall hernias can be complicated by mesh infection, which often requires mesh explantation. The risk of mesh infection is increased in a contaminated environment or in patients who have comorbidities such as diabetes or smoking. The use of biological prostheses has been advocated because of their ability to resist infection. Initial results, however, have shown high hernia recurrence rates and wound occurrences. The objective of the present study is to evaluate early and mid-term outcomes in the largest French series that included 43 consecutive complex abdominal hernias repaired with biological prostheses. Materials and methods. Retrospective observational study of a prospective collected data bank. Patient demographics, history of previous repairs, intraoperative findings and degree of contamination, associated procedures, postoperative prosthetic-related complications, and long-term results were retrospectively reviewed. Results. There were 25 (58%) incisional, 14 parastomal, and 4 midline hernia repairs. Hernias were considered “clean” (n = 5), “clean-contaminated” (n = 19), “contaminated” (n = 12), or “dirty” (n = 7). Wound-related morbidity occurred in 17 patients; 4 patients needed reoperation for cutaneous necrosis or abscess. Smoking was the only risk factor associated with wound complication ( P = .022). No postoperative wound events required removal of the prosthesis. There were 4 hernia recurrences (9%). A previous attempt at repair ( P = .018) and no complete fascia closure ( P = .033) were associated with hernia recurrence. Conclusions. This study demonstrated that the use of bioprothesis in complex hernia repair allowed successful single-stage reconstruction. Wound-related complications were frequent. Cost-benefit analyses are important to establish the validity of these findings.

Fractionation of an ECM hydrogel into structural and soluble components reveals distinctive roles in regulating macrophage behavior

Extracellular matrix (ECM) derived from mammalian tissues has been utilized to repair damaged or missing tissue and improve healing outcomes.

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.

Mesh choice in ventral hernia repair: so many choices, so little time

BACKGROUND

Currently, >200 meshes are commercially available in the United States. To help guide appropriate mesh selection, the investigators examined the postsurgical experiences of all patients undergoing ventral hernia repair at their facility from 2008 to 2011 with ≥12 months of follow-up.

METHODS

A retrospective review of prospectively collected data was conducted. All returns (surgical readmission, office or emergency visit) for complications or recurrences were examined. The impact of demographics (age, gender, and body mass index [BMI]), risk factors (hernia grade, hernia size, concurrent and past bariatric surgery, concurrent and past organ transplantation, any concurrent surgery, and American Society of Anesthesiologists score), and prosthetic type (polypropylene, other synthetic, human acellular dermal matrix, non-cross-linked porcine-derived acellular dermal matrix, other biologic, or none) on the frequency of return was evaluated.

RESULTS

A total of 564 patients had 12 months of follow-up, and 417 patients had 18 months of follow-up. In a univariate regression analysis, study arm (biologic, synthetic, or primary repair), hernia grade, hernia size, past bariatric surgery, and American Society of Anesthesiologists score were significant predictors of recurrence (P < .05). Multivariate analysis, stepwise regression, and interaction tests identified three variables with significant predictive power: hernia grade, hernia size, and BMI. The adjusted odds ratios vs hernia grade 2 for surgical readmission were 2.6 (95% confidence interval [CI], 1.3 to 5.1) for grade 3 and 2.6 (95% CI, 1.1 to 6.4) for grade 4 at 12 months and 2.3 (95% CI, 1.1 to 4.6) for grade 3 and 4.2 (95% CI, 1.7 to 10.0) for grade 4 at 18 months. Large hernia size (adjusted odds ratio vs small size, 3.2; 95% CI, 1.6 to 6.2) and higher BMI (adjusted odds ratio for BMI ≥50 vs 30 to 34.99 kg/m(2), 5.7; 95% CI, 1.2 to 26.2) increased the likelihood of surgical readmission within 12 months.

CONCLUSIONS

The present data support the hypothesis that careful matching of patient characteristics to choice of prosthetic will minimize complications, readmissions, and the number of postoperative office visits.

Biological implants in abdominal wall repair

Research needed to find out how they work and why they fail

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.

2013 WSES guidelines for management of intra-abdominal infections

Despite advances in diagnosis, surgery, and antimicrobial therapy, mortality rates associated with complicated intra-abdominal infections remain exceedingly high.The 2013 update of the World Society of Emergency Surgery (WSES) guidelines for the management of intra-abdominal infections contains evidence-based recommendations for management of patients with intra-abdominal infections.