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

Advances, challenges, and future directions in the clinical translation of ECM biomaterials for regenerative medicine applications

Extracellular Matrix (ECM) scaffolds and biomaterials have been widely used for decades across a variety of diverse clinical applications and have been implanted in millions of patients worldwide. ECM-based biomaterials have been especially successful in soft tissue repair applications but their utility in other clinical applications such as for regeneration of bone or neural tissue is less well understood. The beneficial healing outcome with the use of ECM biomaterials is the result of their biocompatibility, their biophysical properties and their ability to modify cell behavior after injury. As a consequence of successful clinical outcomes, there has been motivation for the development of next-generation formulations of ECM materials ranging from hydrogels, bioinks, powders, to whole organ or tissue scaffolds. The continued development of novel ECM formulations as well as active research interest in these materials ensures a wealth of possibilities for future clinical translation and innovation in regenerative medicine. The clinical translation of next generation formulations ECM scaffolds faces predictable challenges such as manufacturing, manageable regulatory pathways, surgical implantation, and the cost required to address these challenges. The current status of ECM-based biomaterials, including clinical translation, novel formulations and therapies currently under development, and the challenges that limit clinical translation of ECM biomaterials are reviewed herein.

Collagen biomaterials promote the regenerative repair of abdominal wall defects in Bama miniature pigs

Due to adhesion and rejection of recent traditional materials, it is still challenging to promote the regenerative repair of abdominal wall defects caused by different hernias or severe trauma. However, biomaterials with a high biocompatibility and low immunogenicity have exhibited great potential in the regeneration of abdominal muscle tissue. Previously, we have designed a biological collagen scaffold material combined with growth factor, which enables a fusion protein-collagen binding domain (CBD)-basic fibroblast growth factor (bFGF) to bind and release specifically. Though experiments in rodent animals have indicated the regeneration function of CBD-bFGF modified biological collagen scaffolds, its translational properties in large animals or humans are still in need of solid evidence. In this study, the abdominal wall defect model of Bama miniature pigs was established by artificial operations, and the defective abdominal wall was sealed with or without a polypropylene patch, and unmodified and CBD-bFGF modified biological collagen scaffolds. Results showed that a recurrent abdominal hernia was observed in the defect control group (without the use of mesh). Although the polypropylene patch can repair the abdominal wall defect, it also induced serious adhesion and inflammation. Meanwhile, both kinds of collagen biomaterials exhibited positive effects in repairing abdominal wall defects and reducing regional adhesion and inflammation. However, CBD-bFGF-modified collagen biomaterials failed to induce the regenerative repair reported in rat experiments. In addition, unmodified collagen biomaterials induced abdominal wall muscle regeneration rather than fibrotic repair. These results indicated that the unmodified collagen biomaterials are a better option among translational patches for the treatment of abdominal wall defects.

The composition and mechanical properties of porcine placental ECM from three different breeds

Biologic scaffolds are extensively used in various clinical applications such as musculotendinous reconstruction, hernia repair or wound healing. Biologic scaffolds used in these applications vary in species, breed and tissue of origin, and other variables that affect their properties. Decellularization and sterilization processes also determine the characteristics of these scaffolds. The goal of the present study is to compare the composition and mechanical properties of decellularized porcine placental scaffolds from three different porcine breeds: Landrace, York and Duroc. Placental extracellular matrix (ECM) scaffolds from the three porcine breeds preserved the amnion/chorion ECM structure and the basement membrane markers laminin and collagen type IV. ECM placental scaffolds showed similar contents of collagen, elastin and lipids, and minimal differences in glycosaminoglycans content. Mechanical properties from the three breeds ECM placental scaffolds were also similar and stable for 24 months. While this study serves as preliminary characterization of porcine ECM scaffolds, future studies will determine their compatibility and suitability for tissue engineering applications.

Outcomes of Abdominal Wall Reconstruction with a Bovine versus a Porcine Acellular Dermal Matrix: A Propensity Score-Matched Analysis

BACKGROUND

Abdominal wall reconstruction (AWR) is one of the most commonly performed procedures, yet large comparative studies comparing outcomes of AWR using bovine acellular dermal matrix (BADM) and porcine acellular dermal matrix (PADM) are lacking.

METHODS

In this retrospective cohort study of patients who underwent AWR from March of 2005 to June of 2019, the primary comparative outcome measure was hernia recurrence with BADM versus PADM. The secondary outcome was the incidence of surgical-site occurrence (SSO) and surgical-site infection. A propensity score matching approach was applied to compare the clinical outcomes between the two study groups.

RESULTS

The authors identified 725 patients who underwent AWR using BADM (50.5%) or PADM (49.5%). Their mean ± SD age was 59.8 ± 11.5 years, mean body mass index was 31.4 ± 6.7 kg/m 2 , and mean follow-up time was 42 ± 29 months. With propensity score matching, 219 matched pairs were identified. Hernia recurrence rates in BADM (11.4%) and PADM (13.7%) groups did not differ significantly ( P = 0.793). SSO (26.5% versus 29.2%; P = 0.518) and SSI (13.2% versus 11%; P = 0.456) rates did not differ significantly in the PADM and BADM groups, respectively. Conditional logistic regression model and marginal Cox proportional hazards regression model determined that type of acellular dermal matrix was not significantly associated with SSOs (adjusted OR, 1.11; 95% CI, 0.74 to 1.70; P = 0.589) or hernia recurrence (adjusted hazard ratio, 0.85; 95% CI, 0.50 to 1.42; P = 0.52).

CONCLUSIONS

Both BADMs and PADMs provide durable, long-term outcomes. The hernia recurrence and postoperative surgical complication rates were not significantly different between BADM and PADM.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Dermal Matrices: Do We Always Know What Is Going On?

The use of dermal matrices in abdominal wall reconstruction has gained increased attention over time, particularly in contaminated fields. One of their advantages is the greater capacity to resist infection. We report a case of a 36-year-old man, with congenital bladder exstrophy and neobladder reconstruction during childhood. He presented to us with an abdominal hernia associated with a vesicocutaneous fistula. We used a bovine-derived dermal matrix (SurgiMend®, TEI Biosciences, MA, USA) for reinforcement of the abdominal repair considering its laboratory-proven mechanical superiority regarding strength. The early postoperative period was complicated by an infection that led to mesh disintegration and the need for surgical revision. We believe that matrix digestion by bacterial enzymes culminated in rapid breakdown of the product. Further investigations are warranted to determine optimal selection criteria and indications of bioprosthesis in contaminated wounds. Surgeons should be cautious when selecting a biologic mesh in these cases, favoring meshes with a better integration profile.

Construction and properties of the silk fibroin and polypropylene composite biological mesh for abdominal incisional hernia repair

Background: In this study, a new composite biological mesh named SFP was prepared by combining silk fibroin with polypropylene mesh. The mechanism and clinical application value of the SFP composite mesh were explored.

Methods: The fibrous membrane was prepared by electrospinning of silk fibroin. The silk fibrous membrane was adhered to the polypropylene mesh by fibrin hydrogel to make a new composite mesh. The characterizations were verified by structural analysis and in vitro cell experiments. A total of 40 Sprague–Dawley rats were randomly divided into two groups, and 20 rats in each group were implanted with the SFP mesh and pure polypropylene mesh, respectively. The rats were sacrificed in batches on the 3rd, 7th, 14th, and 90th days after surgery. The adhesion degree and adhesion area on the mesh surface were compared, and a histopathological examination was carried out.

Results:In vitro cell function experiments confirmed that the SFP mesh had good cell viability. The control group had different degrees of adhesion on the 3rd, 7th, 14th, and 90th days after surgery. However, there was almost no intraperitoneal adhesions on the 3rd and 7th days after surgery, and some rats only had mild adhesions on the 14th and 90th days after surgery in the SFP group. There were statistically significant differences in the postoperative intraperitoneal adhesion area and adhesion degree between the two groups (p < 0.05). Histopathological examination confirmed that the mesenchymal cells were well arranged and continuous, and there were more new capillaries and adipocyte proliferation under the mesenchymal cells in the SFP group.

Conclusion: The SFP mesh shows good biocompatibility and biofunction in vitro and in vivo. It can promote the growth of peritoneal mesenchymal cells. The formation of a new mesenchymal cell layer can effectively reduce the extent and scope of adhesion between the mesh and abdominal organs. The SFP mesh will have a good application prospect in the field of abdominal wall hernia repair.

Xenogeneic Mesh Provides Safe and Durable Long-Term Outcomes in Abdominal Wall Reconstruction of High-Risk Centers for Disease Control and Prevention Class III and IV Defects

Objective

Evaluate long-term outcomes of abdominal wall reconstruction (AWR) using xenogeneic mesh in patients with Centers for Disease Control and Prevention (CDC) class III/IV defects. We hypothesized that AWR with xenogeneic mesh results in acceptable outcomes.

Background

Optimal mesh selection in AWR of CDC class III/IV defects is controversial. Outcomes using xenogeneic mesh are lacking.

Methods

We conducted a retrospective cohort study of patients who underwent AWR using xenogeneic mesh in CDC class III/IV defects from March 2005 to June 2019. Primary outcome was hernia recurrence (HR). Secondary outcomes were surgical site occurrence (SSO) and surgical site infection (SSI).

Results

Of consecutive 725 AWRs, we identified 101 patients who met study criteria. Sixty-eight patients had class III defects, while 33 had class IV defects. Patients had a mean age of 61.3 ± 11.1 years, mean body mass index of 31.8 ± 7.3 kg/m2, and mean follow-up time of 41.9 ± 26.3 months. Patients had HR rate of 21%, SSO rate of 49%, and SSI rate of 24. Class IV defects were predictive of SSOs (odds ratio [OR], 2.88; 95% confidence interval [CI], 1.11-7.42; P = 0.029) but not HR (hazard ratio, 1.60; 95% CI, 0.59-4.34; P = 0.355) or SSIs (OR, 2.62; 95% CI, 0.85-8.10; P = 0.094).

Conclusions

Patients with class IV defects have a higher risk of SSOs, but not HR or SSIs, compared with patients with class III defects. Despite the high level of defect contamination, AWR with xenogeneic mesh demonstrated acceptable HR, SSO, and SSI rates. Therefore, safe and durable long-term outcomes are achievable in single-stage AWR using xenogeneic mesh for CDC class III/IV defects.

Abdominal wall complications after kidney transplantation: A clinical review

Introduction

Abdominal wall complications are common after kidney transplantation, and although they have a minor impact on patient and graft survival, they increase the patient's morbidity and may have an impact on quality of life. Abdominal wall complications have an overall incidence of 7.7–21%.

Methods

This review will explore the natural history of abdominal wall complications in the kidney transplant setting, with a special focus on wound dehiscence and incisional herni, with a particular emphasis on risk factors, clinical characteristics, and treatment.

Results

Many patient‐related risk factors have been suggested, including older age, obesity, and smoking, but kidney transplant recipients have an additional risk related to the use of immunosuppression. Wound dehiscence usually does not require surgical intervention. However, for deep dehiscence involving the fascial layer with concomitant infection, surgical treatment and/or negative pressure wound therapy may be required.

Conclusions

Incisional hernia (IH) may affect 1.1–18% of kidney transplant recipients. Most patients require surgical treatment, either open or laparoscopic. Mesh repair is considered the gold standard for the treatment of IH, since it is associated with a low rate of postoperative complications and an acceptable rate of recurrence. Biologic mesh could be an attractive alternative in patients with graft exposition or infection.

Mesh fixation techniques in primary ventral or incisional hernia repair

BACKGROUND

The use of a mesh in primary ventral or incisional hernia repair lowers the recurrence rate  and is the accepted standard of care for larger defects. In laparoscopic primary ventral or incisional hernia repair the insertion of a mesh is indispensable. Different mesh fixation techniques have been used and refined over the years. The type of fixation technique is claimed to have a major impact on recurrence rates, chronic pain, health-related quality of life (HRQOL) and complication rates.

OBJECTIVES

To determine the impact of different mesh fixation techniques for primary and incisional ventral hernia repair on hernia recurrence, chronic pain, HRQOL and complications.

SEARCH METHODS

On 2 October 2020 we searched CENTRAL, MEDLINE (Ovid MEDLINE(R)) Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid MEDLINE(R)), Ovid Embase, and two trials registries. We also performed handsearches, and contacted experts from the European Hernia Society (EHS).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) including adults with primary ventral or incisional hernia that compared different types of mesh fixation techniques (absorbable/nonabsorbable sutures, absorbable/nonabsorbable tacks, fibrin glue, and combinations of these techniques).

DATA COLLECTION AND ANALYSIS

We extracted data in standardised piloted tables, or if necessary, directly into Review Manager 5. We assessed risks of bias with the Cochrane 'Risk of bias' tool. Two review authors independently selected the publications, and extracted data on results. We calculated risk ratios (RRs) for binary outcomes and mean differences (MDs) for continuous outcomes. For pooling we used an inverse-variance random-effects meta-analysis or the Peto method in the case of rare events. We prepared GRADE 'Summary of findings' tables. For laparoscopic repair we considered absorbable tacks compared to nonabsorbable tacks, and nonabsorbable tacks compared to nonabsorbable sutures as key comparisons.

MAIN RESULTS

We included 10 trials with a total of 787 participants. The number of randomised participants ranged from 40 to 199 per comparison. Eight studies included participants with both primary and incisional ventral hernia. One study included only participants with umbilical hernia, and another only participants with incisional hernia. Hernia size varied between studies. We judged the risk of bias as moderate to high. Absorbable tacks compared to nonabsorbable tacks Recurrence rates in the groups were similar (RR 0.74, 95% confidence interval (CI) 0.17 to 3.22; 2 studies, 101 participants). It is uncertain whether there is a difference between absorbable tacks and nonabsorbable tacks in recurrence because the certainty of evidence was very low. Evidence suggests that the difference between groups in early postoperative, late follow-up, chronic pain and HRQOL is negligible. Nonabsorbable tacks compared to nonabsorbable sutures At six months there was one recurrence in each group (RR 1.00, 95% CI 0.07 to 14.79; 1 study, 36 participants). It is uncertain whether there is a difference between nonabsorbable tacks and nonabsorbable sutures in recurrence because the certainty of evidence was very low. Evidence suggests that the difference between groups in early postoperative, late follow-up and chronic pain is negligible. We found no study that assessed HRQOL. Absorbable tacks compared to absorbable sutures No recurrence was observed at one year (very low certainty of evidence). Early postoperative pain was higher in the tacks group (VAS 0 - 10: MD -2.70, 95% CI -6.67 to 1.27; 1 study, 48 participants). It is uncertain whether there is a difference between absorbable tacks compared to absorbable sutures in early postoperative pain because the certainty of evidence was very low. The MD for late follow-up pain was -0.30 (95% CI -0.74 to 0.14; 1 study, 48 participants). We found no study that assessed HRQOL. Combination of different fixation types (tacks and sutures) or materials (absorbable and nonabsorbable) There were mostly negligible or only small differences between combinations (e.g. tacks plus sutures) compared to a single technique (e.g. sutures only), as well as combinations compared to other combinations (e.g. absorbable sutures combined with nonabsorbable sutures compared to absorbable tacks combined with nonabsorbable tacks) in all outcomes. It is uncertain whether there is an advantage for combining different fixation types or materials for recurrence, chronic pain, HRQOL and complications, because the evidence certainty was very low or low, or we found no study on important outcomes. Nonabsorbable tacks compared to fibrin sealant The two studies showed different directions of effects: one showed higher rates for nonabsorbable tacks, and the other showed higher rates for fibrin sealant. Low-certainty evidence suggests that the difference between groups in early postoperative, late follow-up, chronic pain and HRQOL is negligible. Absorbable tacks compared to fibrin sealant One recurrence in the tacks group and none in the fibrin sealant group were noted after one year (low certainty of evidence). Early postoperative pain might be slightly lower using tacks (VAS 0 - 100; MD -12.40, 95% CI -27.60 to, 2.80;1 study, 50 participants; low-certainty evidence). The pattern of pain and HRQOL course over time (up to 1 year) was similar in the groups (low certainty of evidence).

AUTHORS' CONCLUSIONS

Currently none of the techniques can be considered superior to any other, because the certainty of evidence was low or very low for all outcomes.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Biologic mesh implantation is associated with serious abdominal wall complications in patients undergoing emergency abdominal surgery: A randomized-controlled clinical trial

BACKGROUND

Open, emergency abdominal surgery is associated with a high incidence of fascial dehiscence and incisional hernia. Implantation of biologic meshes potentially reinforces the abdominal wall and therefore decreases such complications. The aim of this prospective randomized study was to compare the outcome after prophylactic intraperitoneal implantation of a biologic Strattice mesh (Allergan, Dublin, Ireland) with standard abdominal closure in patients undergoing emergency abdominal surgery.

METHODS

A two-arm randomized clinical trial was performed in patients undergoing emergency abdominal surgery at Bern University Hospital, University of Bern, Switzerland, from April 2016 to March 2019. Patients were randomly assigned to prophylactic implantation of a biological intraperitoneal mesh using Strattice, Allergan (mesh group), or standard abdominal closure using a single, continuous running suture (no-mesh group). Because of safety concerns, patient enrollment was closed prematurely.

RESULTS

Eligibility for inclusion was assessed in 61 patients. A total of 48 patients were randomized (21 in the mesh group, 28 in the no-mesh group). No differences in baseline characteristics were found. Abdominal wall complications requiring reoperations were more frequent in the mesh group compared to the no-mesh group (5 [83.3%] of 13 vs. 1 [14.3%] of 13 patients, p = 0.026). Mesh-associated abdominal wall complications included nonintegration of the mesh into the abdominal wall, dissolution of the mesh, and mesh-related infections.

CONCLUSION

In patients undergoing emergency abdominal surgery, intraperitoneal biologic Strattice mesh implantation is associated with significantly more frequent abdominal wall complications requiring reoperation. Therefore, the use of such meshes cannot be recommended in the contaminated environment of emergency abdominal surgery.

LEVEL OF EVIDENCE

Therapeutic, level I.

Surgical site infection in mesh repair for ventral hernia in contaminated field: A systematic review and meta-analysis

Background

Given the risk of surgical site infection (SSI), the use of mesh in contaminated ventral hernia repair (VHR) is not standardized and still a clinical dilemma. This meta-analysis aimed to assess whether mesh use increased the risk of SSI in patients following VHR in contaminated field.

Methods

We performed a systematic review of published literature. Studies comparing the mesh repair and anatomic repair, the use of mesh in different Center for Disease Control and Prevention (CDC) wound classes and mesh repair with synthetic mesh or other type of meshes to treat complicated and contaminated VHR were considered for analysis. The main outcome was SSI incidence.

Results

Six studies compared mesh and suture repairs. No significant difference in SSI incidence was observed between patients with complicated VHR in the mesh and suture repair groups.Five studies analyzed mesh repair in patients by field contamination level. There was no significant difference between the use of mesh in clean-contaminated, contaminated and dirty field versus clean wound class. Moreover, there was no significant difference between the use of mesh in clean-contaminated and contaminated cases.Four studies compared mesh repair technique with synthetic mesh or other type of meshes were included. The incidence of SSI was significantly lower in the synthetic mesh group.

Conclusions

The use of mesh repair in the management of complicated VHR compared to suture repair is not associated with an increased incidence of SSI even in potentially contaminated fields.

Biologic Mesh in Surgery: A Comprehensive Review and Meta-Analysis of Selected Outcomes in 51 Studies and 6079 Patients

BACKGROUND

In recent decades, biologic mesh (BM) has become an important adjunct to surgical practice. Recent evidence-based clinical applications of BM include but are not limited to: reconstruction of abdominal wall defects; breast reconstruction; face, head and neck surgery; periodontal surgery; other hernia repairs (diaphragmatic, hiatal/paraesophageal, inguinal and perineal); hand surgery; and shoulder arthroplasty. Prior systematic reviews of BM in complex abdominal wall hernia repair had several shortcomings that our comprehensive review seeks to address, including exclusion of laparoscopic repair, assessment of risk of bias, use of an acceptable meta-analytic method and review of risk factors identified in multivariable regression analyses.

MATERIALS AND METHODS

We sought articles of BM for open ventral hernia repair reporting on early complications, late complications or recurrences and included minimum of 50. We used the quality in prognostic studies risk of bias assessment tool. Random effects meta-analysis was applied.

RESULTS

This comprehensive review selected 62 articles from 51 studies that included 6,079 patients. Meta-analytic pooling found that early complications are present in about 50%, surgical site occurrences (SSOs) in 37%, surgical site infections (SSIs) in 18%, reoperation in 7%, readmission in 20% and mortality in 3%. Meta-analytic estimates of late outcomes included overall complications (42%), SSOs (40%) and SSIs (22%). Specific SSOs included seroma (14%), hematoma (4%), abscess (10%), necrosis (5%), dehiscence (8%) and fistula formation (5%). Reoperation occurred in about 17%, mesh explantation in 9% and recurrence in 36%.

CONCLUSION

Estimates of nearly all outcomes from individual studies were highly heterogeneous and sensitivity analyses and meta-regressions generally failed to explain this heterogeneity. Recurrence is the only outcome for which there are consistent findings for risk factors. Bridge placement of BM is associated with higher risk of recurrence. Prior hernia repair, history of reintervention and history of mesh removal were also risk factors for increased recurrence.

Chinese expert consensus on adult ventral abdominal wall defect repair and reconstruction

BACKGROUND

Surgical management of patients with ventral abdominal wall defects, especially complex abdominal wall defects, remains a challenging problem for abdominal wall reconstructive surgeons. Effective surgical treatment requires appropriate preoperative assessment, surgical planning, and correct operative procedure in order to improve postoperative clinical outcomes and minimize complications. Although substantial advances have been made in surgical techniques and prosthetic technologies, there is still insufficient high-level evidence favoring a specific technique. Broad variability in existing practice patterns, including clinical pre-operative evaluation, surgical techniques and surgical procedure selection, are still common.

DATA SOURCES

With the purpose of providing a best practice algorithm, a comprehensive search was conducted in Medline and PubMed. Sixty-four surgeons considered as experts on abdominal wall defect repair and reconstruction in China were solicited to develop a Chinese consensus and give recommendations to help surgeons standardize their techniques and improve clinical results.

CONCLUSIONS

This consensus serves as a starting point to provide recommendations for adult ventral abdominal wall repair and reconstruction in China and may help build opportunities for international cooperation to refine AWR practice.

Clinical outcomes and quality of life associated with the use of a biosynthetic mesh for complex ventral hernia repair: analysis of the "Italian Hernia Club" registry

With the development of newer meshes and approaches to hernia repair, it is currently difficult to evaluate their performances while considering the patients' perspective. The aim of the study was to assess the clinical outcomes and quality of life consequences of abdominal hernia repairs performed in Italy using Phasix and Phasix ST meshes through the analysis of real-world data to support the choice of new generation biosynthetic meshes. An observational, prospective, multicentre study was conducted in 10 Italian clinical centres from May 2015 to February 2018 and in 15 Italian clinical centres from March 2018 to May 2019. The evaluation focused on patients with VHWG grade II-III who underwent primary ventral hernia repair or incisional hernia intervention with a follow-up of at least 18 months. Primary endpoints included complications' rates, and secondary outcomes focused on patient quality of life as measured by the EuroQol questionnaire. Seventy-five patients were analysed. The main complications were: 1.3% infected mesh removal, 4.0% superficial infection requiring procedural intervention, 0% deep/organ infection, 8.0% recurrence, 5.3% reintervention, and 6.7% drained seroma. The mean quality of life utility values ranged from 0.768 (baseline) to 0.967 (36 months). To date, Phasix meshes have proven to be suitable prostheses in preventing recurrence, with promising outcomes in terms of early and late complications and in improving patient quality of life.

Incisional Hernia Repairs after Abdominal Organ Transplantation

Incisional hernias occur after abdominal organ transplantation with rates of 1.6 per cent to 18 per cent in kidney transplants (KTs) and 1.7 to 32.4 per cent in liver transplants (LTs). We hypothesized a difference in KTand LToutcomes in patients with and without repair of incisional hernias. We conducted a retrospective cohort study of abdominal transplants from 2012 through 2016. The difference across compared groups for continuous variables was assessed using the independent sample t test, and for binary variables, using the chi-squared test. A total of 1518 transplants were performed, including 1138 KTs and 380 LTs. There were 83 KT incisional hernias (67 repaired) and 59 LT incisional hernias (48 repaired). There was no difference between groups with regard to smoking, diabetes, age, BMI, days on dialysis (KTs), pretransplant Model for End-Stage Liver Disease (MELD) (LTs), cold ischemic time, graft survival, or recurrence rate by repair method. In the LT population, there was a statistically significant difference in days on the waitlist ( P = 0.02), drain placement ( P = 0.04), and cytomegalovirus (CMV) mismatch ( P = 0.02). Patient survival was also statistically significant for KTs ( P = 0.04) and LTs ( P = 0.01). KT and LT patients who have their incisional hernias repaired have better overall survival, regardless of the repair technique.

Long term comparative evaluation of two types of absorbable meshes in partial abdominal wall defects: an experimental study in rabbits

PURPOSE

Synthetic prosthetic materials that are fully absorbable seek to reduce the host foreign body reaction and promote host tissue regeneration. This preclinical trial was designed to analyse, in the long term, the behaviour of two prosthetic meshes, one synthetic and one composed of porcine collagen, in abdominal wall reconstruction.

METHODS

Partial defects were created in the abdominal walls of New Zealand rabbits and repaired using a synthetic absorbable mesh (Phasix™) or a non-crosslinked collagen bioprosthesis (Protexa™). After 3, 6, 12 and 18 months, specimens were recovered for light microscopy and collagen expression analysis to examine new host tissue incorporation, macrophage response and biomechanical strength.

RESULTS

Both materials showed good host tissue incorporation in line with their spatial structure. At 18 months postimplant, Protexa™ was highly reabsorbed while the biodegradation of Phasix™ was still incomplete. Collagenization of both materials was good. Macrophage counts steadily decreased over time in response to Phasix™, yet persisted in the collagen meshes. At 18 months, zones of loose tissue were observed at the implant site in the absence of herniation in both implant types. The stress-stretch behaviour of Phasix™ implants decreased over time, being more pronounced during the period of 12-18 months. Nevertheless, the abdominal wall repaired with Protexa™ became stiffer over time.

CONCLUSION

Eighteen months after the implant both materials showed good compatibility but the biodegradation of Phasix™ and Protexa™ was incomplete. No signs of hernia were observed at 18 months with the stress-stretch relations being similar for both implants, regardless of the more compliant abdominal wall repaired with Protexa™ at short term.

Porcine Small Intestinal Submucosa Mesh to Treat Inguinal Hernia in Young Adults Using Laparoscopic Inguinal Hernia Repair: A Retrospective Controlled Study

BACKGROUND

The authors evaluated the effects and clinical value of small intestinal submucosa (SIS) mesh to treat inguinal hernia in young adults by the laparoscopic method.

METHODS

The clinical data of 357 cases with inguinal hernia using SIS mesh in our hospital were analyzed retrospectively from June 2014 to June 2018. All cases were divided into 2 groups according to the surgical method. Operation time, hospital stay, cost, postoperative complications, and complications during follow-up were analyzed.

RESULTS

Of the 357 patients, 202 (56.6%) underwent Lichtenstein repair and 155 (43.4%) underwent transabdominal preperitoneal (TAPP) repair. Operation time and hospital costs of the Lichtenstein group were significantly lower compared with the TAPP group (P<0.05). The incidence of seroma in the Lichtenstein group was lower than that in the TAPP group at 1 week, 1 month, and 3 months postoperatively with significant differences (P<0.05). Perioperative pain scores in the Lichtenstein group were higher than the TAPP group (P<0.05). No statistical difference was observed for hospital stay between 2 groups (P>0.05). In the Lichtenstein group, 1 case recurred during the follow-up period (0.5%). No intestinal obstruction or intestinal fistula occurred in any patient during the follow-up period.

CONCLUSION

The effect of SIS mesh was positive whether the patient underwent a Lichtenstein or TAPP method. Seroma was more common in the TAPP method that may cause lower postoperative pain. Therefore, we recommend individualized treatment.

Differential recurrence after laparoscopic incisional hernia repair: importance of a nationwide registry-based mesh surveillance

BACKGROUND

Identification of suboptimal mesh products is essential to improve the outcome after hernia surgery. This study investigated whether a national clinical database combined with administrative registries may serve as a tool for postmarketing evaluation of mesh products for hernia surgery.

METHODS

This was a propensity score-matched case-control cohort study comparing outcomes in patients undergoing laparoscopic incisional hernia repair with either one particular mesh or any other synthetic mesh. Data on patients registered in the Danish Ventral Hernia Database between 2010 and 2016 were combined with administrative data from the Danish National Patient Registry. The primary outcome was operation for recurrence. Secondary outcomes were 30-day readmission, 30-day reoperation for complications (excluding hernia recurrence), and mortality after 30 and 90 days.

RESULTS

In total, 740 patients who underwent repair with one particular mesh were matched with 1479 patients who received any other synthetic mesh. The rate of repair for hernia recurrence was significantly higher in the particular mesh group than in the reference group: 12·8 versus 6·3 per cent respectively (hazard ratio 2·09, 95 per cent c.i. 1·57 to 2·79; P < 0·001). Use of the particular mesh increased the risk of readmission (odds ratio (OR) 1·53, 1·16 to 2·01; P = 0·002) and reoperation for a complication (OR 1·60, 1·03 to 2·47, P = 0·030). No difference in mortality was found.

CONCLUSION

Clinical registries with prospectively collected data can provide long-term surveillance of commercial mesh. Laparoscopic incisional hernia repair with one particular mesh was associated with an increased rate of short-term complications and double the risk of repair for recurrence.

A retrospective, Italian multicenter study of complex abdominal wall defect repair with a Permacol biological mesh

Complex abdominal wall defects (CAWDs) can be difficult to repair and using a conventional synthetic mesh is often unsuitable. A biological mesh might offer a solution for CAWD repair, but the clinical outcomes are unclear. Here, we evaluated the efficacy of a cross-linked, acellular porcine dermal collagen matrix implant (Permacol) for CAWD repair in a cohort of 60 patients. Here, 58.3% patients presented with a grade 3 hernia (according to the Ventral Hernia Working Group grading system) and a contaminated surgical field. Permacol was implanted as a bridge in 46.7%, as an underlay (intraperitoneal position) in 38.3% and as a sublay (retromuscolar position) in 15% of patients. Fascia closure was achieved in 53.3% of patients. The surgical site occurrence rate was 35% and the defect size significantly influenced the probability of post-operative complications. The long-term (2 year) hernia recurrence rate was 36.2%. This study represents the first large multi-centre Italian case series on Permacol implants in patients with a CAWD. Our data suggest that Permacol is a feasible strategy to repair a CAWD, with acceptable early complications and long-term (2 year) recurrence rates.

Comparison of biosynthetic versus synthetic mesh in clean and contaminated ventral hernia repairs

BACKGROUND

Abdominal hernias are an increasingly common presentation due to obesity, ageing and prevalence of prior abdominal surgery. Mesh repair is the mainstay of treatment; however, mesh selection remains largely subjective. There are little data available to assess the performance of biosynthetic meshes against synthetic meshes across all wound types. This study assessed the 6-month outcomes of a single surgeon's cohort of ventral hernia repairs performed with either GORE BIO-A (BioA) or Parietex ProGrip (ProGrip).

METHODS

Retrospective case cohort study across two centres with patients undergoing repair by a single surgeon (KS) between January 2014 and April 2018 was conducted. All hernia repairs were performed with either BioA (n = 55) or ProGrip mesh (n = 60). Outcomes were monitored for 6 months post repair. Wounds were classified according to the Centre for Disease Control Wound Status. Outcomes measured were length of stay, general complications, wound complications and hernia recurrence.

RESULTS

The overall complication rate and length of stay were similar for both groups. In clean wounds, the complication rate was equivalent for BioA and ProGrip (34% versus 22%, P = 0.22). There was a significant difference in complication rates in contaminated wounds - BioA 17% versus ProGrip 100% (P = 0.004). BioA performed equivocally in clean and contaminated wounds (34% versus 17%, P = 0.178), whereas ProGrip performed worse in contaminated wounds (22% versus 100%, P = 0.016).

CONCLUSION

Our results suggest that BioA is a suitable, if not preferable, choice for contaminated hernia repair. In this cohort, BioA was also demonstrated as safe and equivalent to ProGrip mesh in clean hernia wounds.

Resistance of Synthetic and Biologic Surgical Meshes to Methicillin-Resistant Staphylococcus aureus Biofilm: An In Vitro Investigation

Surgical meshes have become the standard procedure for a variety of surgical applications with 20 million meshes being implanted each year. The popularity of mesh usage among surgeons is backed by the multiple studies that support its functionality as a tool for improving surgical outcomes. However, their use has also been associated with infectious surgical complications and many surgeons have turned to biologic meshes. While there have been several studies investigating synthetic meshes, there is limited data comparing synthetic and biologic meshes in vitro in an infection model. This study evaluates the in vitro susceptibility of both synthetic and biologic meshes to single-species methicillin-resistant Staphylococcus aureus (MRSA) biofilms. This research compares biofilm biomass, average thickness, and coverage between the three meshes through florescent in situ hybridization (FISH), confocal scanning microscopy (CSLM), and image analysis. We also report the varying levels of planktonic and attached bacteria through sonication and cfu counts. While the data illustrates increased biofilm formation on biologic mesh in vitro, the study must further be investigated in vivo to confirm the study observations.

Biomaterial Implants in Abdominal Wall Hernia Repair: A Review on the Importance of the Peritoneal Interface

Biomaterials have long been used to repair defects in the clinical setting, which has led to the development of a wide variety of new materials tailored to specific therapeutic purposes. The efficiency in the repair of the defect and the safety of the different materials employed are determined not only by the nature and structure of their components, but also by the anatomical site where they will be located. Biomaterial implantation into the abdominal cavity in the form of a surgical mesh, such as in the case of abdominal hernia repair, involves the contact between the foreign material and the peritoneum. This review summarizes the different biomaterials currently available in hernia mesh repair and provides insights into a series of peculiarities that must be addressed when designing the optimal mesh to be used in this interface.

Performance of biological mesh materials in abdominal wall reconstruction: study protocol for a randomised controlled trial

INTRODUCTION

Abdominal wall hernias are a common source of morbidity and mortality. The use of biological mesh has become an important adjunct in successful abdominal wall reconstruction. There are a variety of biological mesh products available; however, there is limited evidence supporting the use of one type over another. This study aims to compare the performance (eg, the rate of hernia recurrence) of either a crosslinked biological mesh product or a non-crosslinked product in patients undergoing abdominal wall reconstruction.

METHODS AND ANALYSIS

This is a single-centre, dual arm randomised controlled trial. Patients requiring abdominal wall reconstruction will be assessed for eligibility. Eligible patients will then undergo an informed consent process following by randomisation to either (1) crosslinked porcine dermis mesh (Permacol); or (2) non-crosslinked porcine dermis mesh (Strattice). These groups will be compared for the rate of hernia recurrence at 1 and 2 years as well as the rate of postoperative complications (eg, surgical site infections).

ETHICS AND DISSEMINATION

This study has been approved by the institution's research ethics board and registered with clinicaltrials.gov. All eligible participants will provide informed consent prior to randomization. The results of this study may help guide the choice of biologic mesh for this population. The results of this study will be published in peer-reviewed journals as well as national and international conferences.

TRIAL REGISTRATION NUMBER

NCT02703662.

Lessons learned from 227 biological meshes used for the surgical treatment of ventral abdominal defects

PURPOSE

The advantages of biological meshes for ventral hernia repair are still under debate. Given the high financial cost, the proper indications for biological meshes should be clarified to restrict their use to properly selected patients.

METHODS

A retrospective database was instituted to register all cases of abdominal wall defect treated with biological meshes from 1/2010 to 3/2016.

RESULTS

A total of 227 patients (mean age: 64 years) whose ventral abdominal defects were reconstructed with a biological mesh were included in the study. Patients were divided according to the 2010 four-level surgical-site complication risk grading system proposed by the Ventral Hernia Working Group (VHWG): Grade 1 (G1, 12 cases), Grade 2 (G2, 68 cases), Grade 3 (G3, 112 cases), and Grade 4 (G4, 35 cases). The surgical site complication rate was higher in patients with one or more risk factors (33.6% vs 19% in patients with no risk factors) (P = 0.68). Statistically significant risk factors associated with the onset of one or more postoperative surgical site complications included: diabetes, coronary artery disease, immunosuppression, and obesity. Recurrence was more common in patients with surgical site complications and mainly associated with infection (38.9%) and wound necrosis (44.4%), and in cases of inlay positioning of the mesh (36%).

CONCLUSIONS

Due to their high costs, biological mesh should not be used in G1 patients. In infected fields (G4), they should only be used if no other surgical solution is feasible. There is a clear need to prospectively evaluate the performance of biological meshes.

"Complex abdominal wall" management: evidence-based guidelines of the Italian Consensus Conference

To date, there is no shared consensus on a definition of a complex abdominal wall in elective surgery and in the emergency, on indications, technical details, complications, and follow-up. The purpose of the conference was to lay the foundations for a homogeneous approach to the complex abdominal wall with the primary intent being to attain the following objectives: (1) to develop evidence-based recommendations to define “complex abdominal wall”; (2) indications in emergency and in elective cases; (3) management of “complex abdominal wall”; (4) techniques for temporary abdominal closure. The decompressive laparostomy should be considered in a case of abdominal compartment syndrome in patients with critical conditions or after the failure of a medical treatment or less invasive methods. In the second one, beyond different mechanism, patients with surgical emergency diseases might reach the same pathophysiological end point of trauma patients where a preventive “open abdomen” might be indicated (a temporary abdominal closure: in the case of a non-infected field, the Wittmann patch and the NPWT had the best outcome followed by meshes; in the case of an infected field, NPWT techniques seem to be the preferred). The second priority is to create optimal both general as local conditions for healing: the right antimicrobial management, feeding—preferably by the enteral route—and managing correctly the open abdomen wall. The use of a mesh appears to be—if and when possible—the gold standard. There is a lot of enthusiasm about biological meshes. But the actual evidence supports their use only in contaminated or potentially contaminated fields but above all, to reduce the higher rate of recurrences, the wall anatomy and function should be restored in the midline, with or without component separation technique. On the other site has not to be neglected that the use of monofilament and macroporous non-absorbable meshes, in extraperitoneal position, in the setting of the complex abdomen with contamination, seems to have a cost effective role too. The idea of this consensus conference was mainly to try to bring order in the so copious, but not always so “evident” literature utilizing and exchanging the expertise of different specialists.

Defining the characteristics of certified hernia centers in Italy: The Italian society of hernia and abdominal wall surgery workgroup consensus on systematic reviews of the best available evidences

BACKGROUND

The terms "Hernia Center" (HC) and Hernia Surgeon" (HS) have gained more and more popularity in recent years. Nevertheless, there is lack of protocols and methods for certification of their activities and results. The Italian Society of Hernia and Abdominal Wall Surgery proposes a method for different levels of certification.

METHODS

The national board created a commission, with the task to define principles and structure of an accreditation program. The discussion of each topic was preceded by a Systematic Review, according to PRISMA Guidelines and Methodology. In case of lack or inadequate data from literature, the parameter was fixed trough a Commission discussion.

RESULTS

The Commission defined a certification process including: "FLC - First level Certification": restricted to single surgeon, it is given under request and proof of a formal completion of the learning curve process for the basic procedures and an adequate year volume of operations. "Second level certification": Referral Center for Abdominal Wall Surgery. It is a public or private structure run by at least two already certified and confirmed FLC surgeons. "Third level certification": High Specialization Center for Abdominal Wall Surgery. It is a public or private structure, already confirmed as Referral Centers, run by at least three surgeons (two certified and confirmed with FLC and one research fellow in abdominal wall surgery). Both levels of certification have to meet the Surgical Requirements and facilities criteria fixed by the Commission.

CONCLUSION

The creation of different types of Hernia Centers is directed to create two different entities offering the same surgical quality with separate mission: the Referral Center being more dedicated to clinical and surgical activity and High Specialization Centers being more directed to scientific tasks.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Impaired intestinal immune barrier and physical barrier function by phosphorus deficiency: Regulation of TOR, NF-κB, MLCK, JNK and Nrf2 signalling in grass carp (Ctenopharyngodon idella) after infection with Aeromonas hydrophila

In aquaculture, the occurrence of enteritis has increased and dietary nutrition is considered as one of the major strategies to solve this problem. In the present study, we assume that dietary phosphorus might enhance intestinal immune barrier and physical barrier function to reduce the occurrence of enteritis in fish. To test this assumption, a total of 540 grass carp (Ctenopharyngodon idella) were investigated by feeding graded levels of available phosphorus (0.95-8.75 g/kg diet) and then infection with Aeromonas hydrophila. The results firstly showed that phosphorus deficiency decreased the ability to combat enteritis, which might be related to the impairment of intestinal immune barrier and physical barrier function. Compared with optimal phosphorus level, phosphorus deficiency decreased fish intestinal antimicrobial substances activities or contents and down-regulated antimicrobial peptides mRNA levels leading to the impairment of intestinal immune response. Phosphorus deficiency down-regulated fish intestinal anti-inflammatory cytokines mRNA levels and up-regulated the mRNA levels of pro-inflammatory cytokines [except IL-1β and IL-12p35 in distal intestine (DI) and IL-12p40] causing aggravated of intestinal inflammatory responses, which might be related to the signalling molecules target of rapamycin and nuclear factor kappa B. In addition, phosphorus deficiency disturbed fish intestinal tight junction function and induced cell apoptosis as well as oxidative damage leading to impaired of fish intestinal physical barrier function, which might be partially associated with the signalling molecules myosin light chain kinase, c-Jun N-terminal protein kinase and NF-E2-related factor 2, respectively. Finally, based on the ability to combat enteritis, dietary available phosphorus requirement for grass carp (254.56-898.23 g) was estimated to be 4.68 g/kg diet.

Major Complex Abdominal Wall Repair in Contaminated Fields with Use of a Non-cross-linked Biologic Mesh: A Dual-Institutional Experience

Background

Data on the use of biologic mesh in abdominal wall repair in complex cases remain sparse. Aim of this study was to evaluate a non-cross-linked porcine acellular dermal matrix for repair of complex contaminated abdominal wall defects.

Methods

Retrospective observational cohort study of consecutive patients undergoing abdominal wall repair with use of Strattice™ Reconstructive Tissue Matrix (LifeCell Corporation, Oxford, UK) between January 2011 and February 2015 at two National Intestinal Failure Units.

Results

Eighty patients were identified. Indications for abdominal wall repair included enterocutaneous fistula takedown (n = 50), infected synthetic mesh removal (n = 9), restoration of continuity or creation of a stoma with concomitant ventral hernia repair (n = 12), and others (n = 9). The median defect area was 143.0 cm² (interquartile range or IQR 70.0–256.0 cm²). All had a grade III or IV hernia. Component separation technique (CST) was performed in 54 patients (68%). Complete fascial closure was not possible despite CST and biologic mesh-assisted traction (bridged repair) in 20 patients (25%). In-hospital mortality was 1%. Thirty-six patients (45%) developed a wound infection. None required mesh removal. Of 76 patients with a median clinical follow-up of 7 months (IQR 4–15) available for analysis, 10 patients (13%) developed a hernia recurrence, of whom 3 had undergone bridged repairs. Seven patients developed a postoperative (recurrent) fistula (9%).

Conclusion

Repair of challenging and contaminated abdominal wall defects can be done effectively with non-cross-linked biologic mesh and component separation technique without the need for mesh removal despite wound infections.

Comparison of biological and alloplastic meshes in ventral incisional hernia repair

PURPOSE

The aim of our retrospective analysis was to compare the results of incisional hernia repair by porcine small intestinal submucosa-derived (SIS) meshes with those obtained by alloplastic polypropylene-based (PP) meshes in comparable surgical indications by matched-pair design. We hypothesized that in incisional hernia, SIS mesh repair is associated with fewer recurrences and SSO than PP mesh repair in incisional hernias.

METHODS

Twenty-four matched pairs (SIS vs. PP mesh repair between 1 January 2005 and 31 December 2013) were identified by matching criteria: gender, age, comorbidities, body mass index, EHS hernia classification, mesh implantation technique, CDC wound classification, and source of contamination/primary surgery leading to incisional hernia. Minimal follow-up time was 24 months. Means and standard deviations were compared by paired t test; categorial data were compared by McNemar's test. Poisson's distribution and negative binominal distribution were employed to detect significant correlation.

RESULTS

There were no statistically significant differences between both groups in the pre- and perioperative factors and the follow-up times. There were significantly more wound complications (19 vs. 12, p = 0.041), longer hospital stay (22.0 ± 6.3 vs. 12.0 ± 3.1 days, p = 0.010), and significantly more recurrent hernias (25 vs. 12.5%, p = 0.004) after SIS mesh repair. Both the Poisson's distribution and the negative binominal distribution unveiled significantly more complication points (3-6 vs. 1-2) per month after SIS mesh repair.

CONCLUSION

There is no advantage of SIS meshes compared to PP meshes in incisional hernia repair with different degrees of wound contamination in this matched-pair analysis. Further prospective and randomized trials or at least registry studies such as the EHS register with standardized and defined conditions are warranted.

Characterization of a new decellularized bovine pericardial biological mesh: Structural and mechanical properties

Implants made from naturally-derived biomaterials, also called biological meshes or biomeshes, typically derive from decellularized extracellular matrix of either animal or human tissue. Biomeshes have many biomedical applications such as ligament repair, bone and cartilage regeneration and soft tissue replacement. Bovine collagen is one of the most widely used and abundantly available xenogenic materials. In particular, bovine pericardium is widely used as extracellular matrix bioprosthetic tissue. The efficiency of a pericardial mesh to function as scaffold depends on the quality of the decellularization protocol used. Moreover, the biomesh mechanical features are critical for a successful surgical repair process, as they must reproduce the biological properties of the autologous tissue. Different methods of physical, chemical, or enzymatic decellularization exist, but no one has proved to be ideal. Therefore, in the present study, we developed a novel decellularization protocol for a bovine pericardium-derived biomesh. We characterized the biomesh obtained by comparing some ultrastructural, physical and mechanical features to a reference commercial biomesh. Quantification revealed that our novel decellularization process removed about 90% of the native pericardial DNA. Microscopic and ultrastructural analysis documented the maintenance of the physiological structure of the pericardial collagen. Moreover, mechanical tests showed that both the extension and resilience of the new biomesh were statistically higher than the commercial control ones. The results presented in this study demonstrate that our protocol is promising in preparing high quality bovine pericardial biomeshes, encouraging further studies to validate its use in tissue engineering and regenerative medicine protocols.

Complex abdominal wall reconstruction in the setting of active infection and contamination: a systematic review of hernia and fistula recurrence rates

AIM

Minimal evidence exists to guide surgeons on the risk of complications when performing abdominal wall reconstruction (AWR) in the presence of active infection, contamination or enterocutaneous fistula. This study aims to establish the outcomes of contaminated complex AWR.

METHOD

Analysis was conducted according to PRISMA guidelines. Systematic search of the MEDLINE, EMBASE and Pubmed databases was performed. Studies reporting exclusively on single-staged repair of contaminated complex AWR were included. Pooled data were analysed to establish rates of complications.

RESULTS

Sixteen studies were included, consisting of 601 contaminated complex AWRs, of which 233 included concurrent enterocutaneous fistula repair. The average follow-up period was 26.7 months. There were 146 (24.3%) reported hernia recurrences. When stratified by repair method, suture repair alone had the lowest rate of recurrence (14.2%), followed by nonabsorbable synthetic mesh reinforcement (21.2%), biological mesh (25.8%) and absorbable synthetic mesh (53.1%). Hernia recurrence was higher when fascial closure was not achieved. Of the 233 enterocutaneous fistula repairs, fistula recurrence was seen in 24 patients (10.3%). Suture repair alone had the lowest rate of recurrence (1.6%), followed by nonbiological mesh (10.3%) and biological mesh reinforcement (12%). Forty-six per cent of patients were reported as having a wound-related complication and the mortality rate was 2.5%.

CONCLUSION

It is feasible to perform simultaneous enterocutaneous fistula repair and AWR as rates of recurrent fistula are comparable with series describing enterocutaneous fistula repair alone. Hernias recurred in nearly a quarter of cases. This analysis is limited by a lack of comparative data and variability of outcome reporting.

Biomimetic collagen/elastin meshes for ventral hernia repair in a rat model

Ventral hernia repair remains a major clinical need. Herein, we formulated a type I collagen/elastin crosslinked blend (CollE) for the fabrication of biomimetic meshes for ventral hernia repair. To evaluate the effect of architecture on the performance of the implants, CollE was formulated both as flat sheets (CollE Sheets) and porous scaffolds (CollE Scaffolds). The morphology, hydrophylicity and in vitro degradation were assessed by SEM, water contact angle and differential scanning calorimetry, respectively. The stiffness of the meshes was determined using a constant stretch rate uniaxial tensile test, and compared to that of native tissue. CollE Sheets and Scaffolds were tested in vitro with human bone marrow-derived mesenchymal stem cells (h-BM-MSC), and finally implanted in a rat ventral hernia model. Neovascularization and tissue regeneration within the implants was evaluated at 6weeks, by histology, immunofluorescence, and q-PCR. It was found that CollE Sheets and Scaffolds were not only biomechanically sturdy enough to provide immediate repair of the hernia defect, but also promoted tissue restoration in only 6weeks. In fact, the presence of elastin enhanced the neovascularization in both sheets and scaffolds. Overall, CollE Scaffolds displayed mechanical properties more closely resembling those of native tissue, and induced higher gene expression of the entire marker genes tested, associated with de novo matrix deposition, angiogenesis, adipogenesis and skeletal muscles, compared to CollE Sheets. Altogether, this data suggests that the improved mechanical properties and bioactivity of CollE Sheets and Scaffolds make them valuable candidates for applications of ventral hernia repair.

STATEMENT OF SIGNIFICANCE

Due to the elevated annual number of ventral hernia repair in the US, the lack of successful grafts, the design of innovative biomimetic meshes has become a prime focus in tissue engineering, to promote the repair of the abdominal wall, avoid recurrence. Our meshes (CollE Sheets and Scaffolds) not only showed promising mechanical performance, but also allowed for an efficient neovascularization, resulting in new adipose and muscle tissue formation within the implant, in only 6weeks. In addition, our meshes allowed for the use of the same surgical procedure utilized in clinical practice, with the commercially available grafts. This study represents a significant step in the design of bioactive acellular off-the-shelf biomimetic meshes for ventral hernia repair.

Effectiveness and versatility of biological prosthesis in transplanted patients

AIM

To emphasize the effectiveness and versatility of prosthesis, and good tolerance by patients with incisional hernia (IH).

METHODS

From December 2001 to February 2016, 270 liver transplantations were performed at San Camillo Hospital. IH occurred in 78 patients (28.8%). IH usually appeared early within the first year post-orthotopic liver transplantation. In the first era, fascial defect was repaired by primary closure for defects smaller than 2.5 cm or with synthetic mesh for greater defects. Recently, we started using biological mesh (Permacol™, Covidien). We present a series of five transplanted patients submitted to surgery for abdominal wall defect correction repaired with biological mesh (Permacol™, Covidien).

RESULTS

In our cases, the use of biological prosthesis (Permacol™, Covidien) have proven to be effective and versatile in repairing hernia defects of different kinds; patients did not suffer infections of the prosthesis and no recurrence was observed. Furthermore, the prosthesis remains intact even in the years after surgery.

CONCLUSION

The cases that we presented show that the use of biological mesh (Permacol™, Covidien) in transplanted patients may be safe and effective, being careful in the management of perioperative immunosuppression and renal and graft function, although the cost of the product itself has been the main limiting factor and there is need for prospective studies for further evaluations.

Hospital wide porcine mesh conversion results in cost savings with equivalent clinical outcomes

BACKGROUND

A variety of biologic mesh is available for ventral hernia repair. Despite widely variable costs, there is no data comparing cost of material to clinical outcome.

METHODS

Biologic mesh product change was examined. A prospective survey was done to determine appropriate biologic mesh utilization, followed by a retrospective chart review of those treated from Sept. 2012 to Aug. 2013 with Strattice™ and from Sept. 2013 to Aug. 2014 with Permacol™. Outcome variables included complications associated with each material, repair success, and cost difference over the two periods.

RESULTS

28 patients received Strattice™ and 41 Permacol™. There was no statistical difference in patient factors, hernia characteristics, length of stay, readmission rates or surgical site infections at 30 days. The charges were significantly higher for Strattice™ with the median cost $8940 compared to $1600 for Permacol™ (p < 0.001). Permacol™ use resulted in a savings if $181,320.

CONCLUSIONS

Permacol™ use resulted in similar clinical outcomes with significant cost savings when compared to Strattice™. Biologic mesh choice should be driven by a combination of clinical outcomes and product cost.

Xenograft biologic mesh in parietal and general surgery: Technical assessment and review of clinical effectiveness and safety data

STUDY AIM

To describe the main technical characteristics of biologic prostheses used for parietal reinforcement and to present the state of the art on their risk/benefit ratio.

METHODS

We conducted a technical analysis of manufacturer specifications of the biologic prostheses that are currently available in France accompanied by a literature review by selecting meta-analyses and systematic reviews, randomized controlled trials and publications of health technology rating agencies.

RESULTS

Biological implants for parietal reinforcement are mainly intended for use in a contaminated environment where the use of synthetic prostheses is contra-indicated. We identified fourteen systematic reviews and meta-analyses and one randomized controlled trial. Six ongoing clinical trials were identified as well as two clinical trials that had been interrupted. In the current state of knowledge, there are no high-level evidence data on the therapeutic contribution of biologic prostheses that allow prioritization of the various biologic prostheses according to their characteristics or their different manufacturing processes.

CONCLUSION

Pending the results of current randomized controlled trials to validate the indications and an eventual specific reimbursement, indications for the use of biologic parietal reinforcement prostheses seems to be limited to rare clinical situations and only after collegial discussion.

The use of a negative pressure wound management system in perineal wound closure after extralevator abdominoperineal excision (ELAPE) for low rectal cancer

BACKGROUND

Perineal wound healing is a significant challenge after extralevator abdominoperineal excision (ELAPE) due to a high rate of wound breakdown. Negative pressure therapy has proven benefits in open wounds, and recently a negative pressure system has been developed for use on closed wounds at high risk of breakdown, such as apronectomy and hysterectomy. The aim of the present study was to determine whether negative pressure therapy applied to closed perineal wounds after ELAPE improved wound healing and compare outcomes to the published literature and outcomes from a historical cohort of patients who had undergone 'standard' abdominoperineal resection (APR) and primary closure of the perineal wounds.

METHODS

Prospective data on consecutive patients having ELAPE in the period from November 2012 to April 2015 were collected. The pelvic floor defect was reconstructed with biologic mesh. The adipose tissue layer was closed with vicryl sutures, a suction drain was left in the deep layer, the subcuticular layer and skin were closed, and the negative pressure system was applied. Any wound breakdown within the first 30 days postoperatively was recorded.

RESULTS

Of the 32 consecutive ELAPE patients whose perineal wounds were closed within 30 days with the use of the negative pressure system, there was 1 patient with major perineal wound breakdown and 2 patients with a 1 cm superficial wound defect, which needed no further treatment. In the remaining 29 (90 %) patients, the perineal wounds healed fully without complications. Twenty-five patients underwent standard APR in 2010-2011 with primary closure of their perineal wounds. Ten out of 25(40 %) of patients who had undergone standard APR and primary closure of perineal wounds had major wound complications (p = 0.01).

CONCLUSIONS

Our results suggest that after ELAPE the application of a negative pressure system to the perineal wound closed with biologic mesh may reduce perineal wound complications and may reduce the need for major perineal reconstruction.

Use of Biological Tissue Matrix in Postneurosurgical Posterior Trunk Reconstruction Is Associated with Higher Wound Complication Rates

BACKGROUND

Patients undergoing neurosurgical spine surgery for spinal tumors are increasingly undergoing soft-tissue reconstruction involving the use of biological tissue matrices. There are limited data available on the safety of these devices in posterior trunk reconstruction.

METHODS

A cohort study of patients undergoing oncologic spine surgery with subsequent plastic surgery soft-tissue reconstruction from 2002 to 2014 was conducted. Demographic, medical, and surgical variables were recorded. The primary outcome variable was development of a postoperative wound complication. Secondary outcome variables were specific complications, including infection, seroma, hematoma, dehiscence, and cerebrospinal fluid leak. The predictor variable was the presence or absence of biological matrix at the reconstruction site.

RESULTS

A total of 293 cases in 260 patients were included in this study. The cohorts were similar with regard to demographic, medical, and surgical variables. The incidence of all-cause wound complications in patients receiving biological matrix for reconstruction was 49.2 percent, whereas the all-cause complication rate for patients not receiving the matrix was 31.7 percent (p = 0.010). The rates of infection (34.9 percent versus 20.9 percent) and seroma (19.0 percent versus 10.0 percent) were also increased in patients receiving biological matrix. In multivariate analysis, biological matrix use remained a predictor of wound complications (p = 0.045), infection (p = 0.011), and seroma (p = 0.047).

CONCLUSIONS

The authors identified an increased risk of infection and seroma with the use of biological tissue matrix in posterior trunk reconstruction. Careful consideration of the risks and benefits of using these devices in this patient population is warranted.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

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.

Effectiveness and properties of the biological prosthesis Permacol™ in pediatric surgery: A large single center experience

INTRODUCTION

The use of prosthetic patches of non-absorbable materials represents a valid tool in the treatment of abdominal wall and diaphragmatic defects in pediatric age. In recent years research has developed biological dermal scaffolds made from a sheet of acellular matrix that can provide the desired support and reduce the occurrence of complications from non-absorbable implant. We present our experience and a systematic review to evaluate the use of biologic prosthesis for abdominal wall closure in pediatric patients.

METHODS

The study from January 2009 to January 2015 involved 20 patients treated with Permacol™ implant. We observed postoperative complications only in patients treated for abdominal wall closure, which is the major indication for the use of Permacol™. We conducted a systematic review and meta-analysis (according to PRISMA) on PubMed/Medline, Scopus and EMBASE regarding the use of biological prosthesis in pediatric population considering the incidence of complications as the primary outcome.

RESULTS

3/20 patients experienced complications: 2 patients with skin necrosis healed conservatively and 1 of them developed laparocele. Thus only 1 patient with incisional hernia had significant surgery complication. In patients who were permanently implanted with Permacol™ it has not determined adverse reactions with optimal functional outcome.

CONCLUSIONS

In accordance with the few data (case reports and case series) reported in literature about pediatric patients, our experience in different pathologies and applications has shown the effectiveness of Permacol™, in particular for the non-occurrence of infections, that often affect the use of prosthesis.

Surgical mesh for ventral incisional hernia repairs: Understanding mesh design

Surgical mesh has become an indispensable tool in hernia repair to improve outcomes and reduce costs; however, efforts are constantly being undertaken in mesh development to overcome postoperative complications. Common complications include infection, pain, adhesions, mesh extrusion and hernia recurrence. Reducing the complications of mesh implantation is of utmost importance given that hernias occur in hundreds of thousands of patients per year in the United States. In the present review, the authors present the different types of hernia meshes, discuss the key properties of mesh design, and demonstrate how each design element affects performance and complications. The present article will provide a basis for surgeons to understand which mesh to choose for patient care and why, and will explain the important technological aspects that will continue to evolve over the ensuing years.