In vivo analysis of the morphologic characteristics of synthetic mesh to resist MRSA adherence

Short-term outcomes of heavyweight versus mediumweight synthetic mesh in a retrospective cohort of clean-contaminated and contaminated retromuscular ventral hernia repairs

BACKGROUND

Mediumweight (40-60 g/m2) polypropylene (MWPP) mesh has been shown to be safe and effective in CDC class II-III retromuscular ventral hernia repairs (RMVHR). However, MWPP has the potential to fracture, and it is possible that heavyweight (> 75 g/m2) polypropylene mesh has similar outcomes in this context. However, there is limited data on HWPP mesh performance in clean-contaminated and contaminated scenarios. We aimed to compare HWPP to MWPP mesh in CDC class II-III wounds during open RMVHR.

METHODS

The Abdominal Core Health Quality Collaborative database was retrospectively queried for a cohort of patients who underwent open RMVHR with MWPP or HWPP mesh placed in CDC class II/III wounds from 2012 to 2023. Mesh types were compared using a 3:1 propensity score-matched analysis. Covariates for matching included CDC classification, BMI, diabetes, smoking within 1 year, hernia, and mesh width. Primary outcome of interest included wound complications. Secondary outcomes included reoperations and readmissions at 30 days.

RESULTS

A total of 1496 patients received MWPP or HWPP (1378 vs. 118, respectively) in contaminated RMVHR. After propensity score matching, 351 patients remained in the mediumweight and 117 in the heavyweight mesh group. There were no significant differences in surgical site infection (SSI) rates (13.4% vs. 14.5%, p = 0.877), including deep SSIs (0.3% vs. 0%, p = 1), surgical site occurrence rates (17.9% vs. 22.2%, p = 0.377), surgical site occurrence requiring procedural intervention (16% vs. 17.9%, p = 0.719), mesh removal (0.3% vs. 0%, p = 1), reoperations (4.6% vs. 2.6%, p = 0.428), or readmissions (12.3% vs. 9.4%, p = 0.504) at 30 days.

CONCLUSION

HWPP mesh was not associated with increased wound morbidity, mesh excisions, reoperations, or readmissions in the early postoperative period compared with MWPP mesh in open RMVHR for CDC II/III cases. Longer follow-up will be necessary to determine if HWPP mesh may be a suitable alternative to MWPP mesh in contaminated scenarios.

Long-term mesh-related complications from minimally invasive intraperitoneal onlay mesh for small to medium-sized ventral hernias

INTRODUCTION

Intraperitoneal onlay mesh (IPOM) placement for small to medium-sized hernias has garnered negative attention due to perceived long-term risk of mesh-related complications. However, sparse data exists supporting such claims after minimally invasive (MIS) IPOM repairs and most is hindered by the lack of long-term follow-up. We sought to report long-term outcomes and mesh-related complications of MIS IPOM ventral hernia repairs.

METHODS AND PROCEDURES

Adult patients who underwent MIS IPOM ventral hernia repair at our institution were identified in the Abdominal Core Health Quality Collaborative database from October 2013 to October 2020. Outcomes included hernia recurrence and mesh-related complications or reoperations up to 6 years postoperatively.

RESULTS

A total of 325 patients were identified. The majority (97.2%) of cases were elective, non-recurrent (74.5%), and CDC class I (99.4%). Mean hernia width was 4.16 ± 3.86 cm. Median follow-up was 3.6 (IQR 2.8-5) years. Surgeon-entered or patient-reported follow-up was available for 253 (77.8%) patients at 3 years or greater postoperatively. One patient experienced an early small bowel obstruction and was reoperated on within 30 days. Two-hundred forty-five radiographic examinations were available up to 6 years postoperatively. Twenty-seven patients had hernia recurrence on radiographic examination up to 6 years postoperatively. During long-term follow-up, two mesh-related complications required reoperations: mesh removed for chronic pain and mesh removal at the time of colon surgery for perforated cancer. Sixteen additional patients required reoperation within 6 years for the following reasons: hernia recurrence (n = 5), unrelated intraabdominal pathology (n = 9), obstructed port site hernia (n = 1), and adhesive bowel obstruction unrelated to the prosthesis (n = 1). The rate of reoperation due to intraperitoneal mesh complications was 0.62% (2/325) with up to 6 year follow-up.

CONCLUSION

Intraperitoneal mesh for repair of small to medium-sized hernias has an extremely low rate of long-term mesh-related complications. It remains a safe and durable option for hernia surgeons.

Synthetic Versus Biological Mesh in Ventral Hernia Repair and Abdominal Wall Reconstruction: A Systematic Review and Recommendations from Evidence-Based Medicine

AIM

To compare the efficacy and safety of synthetic and biological meshes in ventral hernia repair (VHR) and abdominal wall reconstruction (AWR).

METHODS

We screened all clinical trials that reported the application of synthetic and biological meshes in VHR and AWR using Medline, Web of Science, and Embase (Ovid). Only comparative studies with similar baselines such as age, sex, body mass index, degree of wound contamination, and hernia defects between the intervention and control groups were included. Effect sizes with 95% confidence were pooled using a random- or fixed-effects model based on the size of heterogeneity. A sensitivity analysis was performed to test the stability of the results.

RESULTS

Ten studies with 1305 participants were included. Biological meshes were associated with significantly higher recurrence rate (OR, 2.09; 95% CI 1.42-3.08; I2 = 50%), surgical site infection (OR, 1.47; 95% CI 1.10-1.97; I2 = 30%), higher re-admission rate (OR, 1.51; 95% CI 1.05-2.17; I2 = 50%), and longer length of hospital stay (SMD, 0.37; 95% CI 0.10-0.65; I2 = 72%). Similar surgical site occurrence, re-operation rate, and mesh explantation rate were observed among biological and synthetic meshes. Biological meshes have no difference in recurrence rate as compared to synthetic meshes, between the clean-contaminated, and contamination-infected fields (OR, 1.41; 95% CI 0.41-4.87 vs 3.00; 95% CI 1.07-8.46; P = 0.36).

CONCLUSION

Synthetic meshes are a safe alternative to biological meshes for VHR and AWR. Considering the high cost of biological meshes, synthetic meshes are more appropriate for the VHR and AWR.

Single-staged retromuscular abdominal wall reconstruction with mesh at the time of ostomy reversal: are we crossing the line? An ACHQC Analysis

INTRODUCTION

The most appropriate method of reconstructing the abdominal wall at the site of a simultaneous stoma takedown is controversial. The contaminated field, concomitant GI procedure being performed and presence of a hernia all complicate decision-making. We sought to describe the surgical approaches, mesh type and outcomes of concomitant abdominal wall reconstruction during stoma takedown in a large hernia registry.

METHODS AND PROCEDURES

All patients who underwent stoma takedown with simultaneous hernia repair with retromuscular mesh placement from January 2014 to May 2022 were identified within the Abdominal Core Health Quality Collaborative (ACHQC). Patients were stratified by mesh type including permanent synthetic (PS), resorbable synthetic (RS) and biologic mesh. Association of mesh type with 30-day wound events and other complications and 1-year outcomes were evaluated.

RESULTS

There were 368 patients who met inclusion criteria. Eighty-nine patients had ileostomies, 276 colostomies and 3 had both. Two hundred and seventy-nine (75.8%) patients received PS mesh, 46 (12.5%) biologic, and 43 (11.7%) RS. Seventy percent (259/368) had a parastomal hernia, 75% (285/368) had a midline incisional hernia, and 48% (178/368) had both. All groups had similar preoperative comorbidities and the majority had a transversus abdominus release. All mesh groups had similar thirty-day SSI (13.2-14.3%), SSO (10.5-17.8%) and SSOPI (7.9-14.1%), p = 0.6. Three patients with PS mesh developed infected synthetic mesh and one PS mesh required excision. Four patients with PS developed an enterocutaneous fistula. Of these, only one patient was recorded as having both an enterocutaneous fistula and mesh infection. Thirty-day reoperation and readmission were similar across all mesh groups. Recurrence at 1-year was similar between mesh groups. Quality of life measured using HerQLes scores were higher at one year compared to baseline in all groups indicating improvement in hernia-specific quality of life.

CONCLUSION

Early complication rates associated with simultaneous stoma takedown and abdominal wall reconstruction are significant, regardless of mesh type utilized. Concomitant surgery should be weighed heavily and tailored to individual patients.

Management of abdominal wall hernias in patients with severe obesity

Obesity is a risk factor for abdominal wall hernia development and hernia recurrence. The management of these two pathologies is complex and often entwined. Bariatric and ventral hernia surgery require careful consideration of physiologic and technical components for optimal outcomes. In this review, a multidisciplinary group of Society of American Gastrointestinal and Endoscopic Surgeons' bariatric and hernia surgeons present the various weight loss modalities available for the pre-operative optimization of patients with severe obesity and concurrent hernias. The group also details the technical aspects of managing abdominal wall defects during weight loss procedures and suggests the optimal timing of definitive hernia repair after bariatric surgery. Since level one evidence is not available on some of the topics covered by this review, expert opinion was implemented in some instances. Additional high-quality research in this area will allow for better recommendations and therefore treatment strategies for these complex patients.

Choice of Polymer, but Not Mesh Structure Variation, Reduces the Risk of Bacterial Infection with Staphylococcus aureus In Vivo

BACKGROUND

Synthetic mesh material is of great importance for surgical incisional hernia repair. The physical and biochemical characteristics of the mesh influence mechanical stability and the foreign body tissue reaction. The influence on bacterial infections, however, remains ill-defined. The aim of the present study was to evaluate the influence of a modified mesh structure with variation in filament linking on the occurrence of bacterial infection that is indicated by the occurrence of CD68⁺, CD4⁺, and CD8⁺ cells in two different materials.

METHODS

A total of 56 male Sprague Dawley rats received a surgical mesh implant in a subcutaneous abdominal position. The mesh of two different polymers (polypropylene (PP) and polyvinylidenfluoride (PVDF)) and two different structures (standard structure and bold structure with higher filament linking) were compared. During the implantation, the meshes were infected with Staphylococcus (S.) aureus. After 7 and 21 days, meshes were explanted, and the early and late tissue responses to infection were histologically evaluated.

RESULTS

Overall, the inflammatory tissue response was higher at 7 days when compared to 21 days. At 7 days, PP meshes of the standard structure (PP-S) showed the strongest inflammatory tissue response in comparison to all the other groups. At 21 days, no statistically significant difference between different meshes was detected. CD8⁺ cytotoxic T cells showed a significant difference at 21 days but not at 7 days. PP meshes of both structures showed a higher infiltration of CD8⁺ T cells than PVDF meshes. CD4⁺ T helper cells differed at 7 days but not at 21 days, and PVDF meshes in a bold structure showed the highest CD4⁺ T cell count. The number of CD68⁺ macrophages was also significantly higher in PP meshes in a standard structure when compared to PVDF meshes at 21 days.

CONCLUSION

The inflammatory tissue response to S. aureus infection appears to be highest during the early period after mesh implantation. PP meshes showed a higher inflammatory response than PVDF meshes. The mesh material appears to be more important for the risk of infection than the variation in filament linking.

Mediumweight polypropylene mesh fractures after open retromuscular ventral hernia repair: incidence and associated risk factors

PURPOSE

Mediumweight (MW) and heavyweight (HW) polypropylene have demonstrated similar clinical and patient-reported outcomes in the setting of open retromuscular ventral hernia repair (VHR). While MW mesh has an anecdotal risk of central mesh fracture, that phenomenon is not well-characterized. We sought to assess the incidence of and risk factors for MW polypropylene mesh fractures after VHR.

METHODS

The ACHQC registry was queried for patients with CT-documented hernia recurrence after open retromuscular VHR with MW polypropylene mesh at our institution with 1-year follow-up between January 2014 and April 2022. Images were reviewed by five blinded surgeons at Cleveland Clinic to reach consensus that hernia recurrence mechanism was central mesh fracture. Patients without clinical recurrence or patient-reported bulge were used as a comparator group.

RESULTS

Eighty patients were identified with radiographically documented recurrence; 28 had recurrence from mesh fractures and these were compared to 644 patients without recurrence. Incidence of MW fracture was 4.2%. Bridging of anterior fascia was more common in the group with the central mesh fracture (33.3% vs 3.3%, p < 0.001); the incidence of fracture was 30% (9/30) in patients requiring a bridged closure. Mesh fracture was associated with larger hernias (median width: 20 cm [16-26] vs 15 cm [12-18], p < 0.001,), length (25 cm [23-30] vs 23 cm [19-26], p = 0.004).

CONCLUSION

MW polypropylene mechanical failures are surprisingly common, particularly in settings of bridged fascial closure and larger hernias. Use of HW polypropylene should be considered in this setting, and industry should be encouraged to create larger pieces of HW polypropylene mesh.

Gastrointestinal procedures and anastomoses can be safely performed during complex abdominal wall reconstruction

INTRODUCTION

The literature regarding combined abdominal wall reconstruction and gastrointestinal surgery is limited and largely suggests staged procedures due to a reported increased incidence of surgical site infections (SSIs), hernia recurrence and anastomotic leak, but this exposes patients to the risks of two substantial procedures. This study evaluates the outcomes of single-stage GI surgery with complex abdominal wall reconstructions (CAWR) by a single surgeon.

METHODS

Analysis of 10 years of a prospectively maintained single surgeon CAWR database compared those who had CAWR-alone with those having concomitant gastrointestinal surgery (CAWR-GI) such as stoma reversal or bowel resection but excluding cholecystectomy, gynaecological surgery and adhesiolysis alone. Groups were compared using the paired t test (continuous data) and Fisher's exact test (nominal data).

RESULTS

Overall, 62 elective cases (42 CAWR-alone vs. 20 CAWR-GI) were analysed. Baseline demographics (age, BMI, co-morbidities, smoking status and hernia size) showed no differences; CAWR-GI mean operating time was significantly longer compared to the CAWR-alone group (5.4 h vs. 4.1 h) with an increased incidence of post-operative ileus in the intestinal group (40% vs. 11.9%, p < 0.05). Post-operative complications were common (chest infection (32.3%) and SSI (41.9%)), but similar between groups. There were no anastomotic leaks, and the hernia recurrence rate at almost 4 years median follow-up was 10% in both groups.

CONCLUSION

Performing simultaneous intestinal surgery during complex abdominal wall repair can be performed safely without increasing the risk of hernia recurrence, mesh infections or anastomotic leak. A careful choice of mesh implant is required.

Biologic vs Synthetic Mesh for Single-stage Repair of Contaminated Ventral Hernias: A Randomized Clinical Trial

IMPORTANCE

Biologic mesh is widely used for reinforcing contaminated ventral hernia repairs; however, it is expensive and has been associated with high rates of long-term hernia recurrence. Synthetic mesh is a lower-cost alternative but its efficacy has not been rigorously studied in individuals with contaminated hernias.

OBJECTIVE

To determine whether synthetic mesh results in superior reduction in risk of hernia recurrence compared with biologic mesh during the single-stage repair of clean-contaminated and contaminated ventral hernias.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, single-blinded randomized clinical trial was conducted from December 2012 to April 2019 with a follow-up duration of 2 years. The trial was completed at 5 academic medical centers in the US with specialized units for abdominal wall reconstruction. A total of 253 adult patients with clean-contaminated or contaminated ventral hernias were enrolled in this trial. Follow-up was completed in April 2021.

INTERVENTIONS

Retromuscular synthetic or biologic mesh at the time of fascial closure.

MAIN OUTCOMES AND MEASURES

The primary outcome was the superiority of synthetic mesh vs biologic mesh at reducing risk of hernia recurrence at 2 years based on intent-to-treat analysis. Secondary outcomes included mesh safety, defined as the rate of surgical site occurrence requiring a procedural intervention, and 30-day hospital direct costs and prosthetic costs.

RESULTS

A total of 253 patients (median [IQR] age, 64 [55-70] years; 117 [46%] male) were randomized (126 to synthetic mesh and 127 to biologic mesh) and the follow-up rate was 92% at 2 years. Compared with biologic mesh, synthetic mesh significantly reduced the risk of hernia recurrence (hazard ratio, 0.31; 95% CI, 0.23-0.42; P < .001). The overall intent-to-treat hernia recurrence risk at 2 years was 13% (33 of 253 patients). Recurrence risk with biologic mesh was 20.5% (26 of 127 patients) and with synthetic mesh was 5.6% (7 of 126 patients), with an absolute risk reduction of 14.9% with the use of synthetic mesh (95% CI, -23.8% to -6.1%; P = .001). There was no significant difference in overall 2-year risk of surgical site occurrence requiring a procedural intervention between the groups (odds ratio, 1.22; 95% CI, 0.60-2.44; P = .58). Median (IQR) 30-day hospital direct costs were significantly greater in the biologic group vs the synthetic group ($44 936 [$35 877-$52 656] vs $17 289 [$14 643-$22 901], respectively; P < .001). There was also a significant difference in the price of the prosthetic device between the 2 groups (median [IQR] cost biologic, $21 539 [$20 285-$23 332] vs synthetic, $105 [$105-$118]; P < .001).

CONCLUSIONS AND RELEVANCE

Synthetic mesh demonstrated superior 2-year hernia recurrence risk compared with biologic mesh in patients undergoing single-stage repair of contaminated ventral hernias, and both meshes demonstrated similar safety profiles. The price of biologic mesh was over 200 times that of synthetic mesh for these outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02451176.

A pragmatic, evidence-based approach to coding for abdominal wall reconstruction

PURPOSE

Ambiguity exists defining abdominal wall reconstruction (AWR) and associated Current Procedural Terminology code usage in the context of ventral hernia repair (VHR), especially with recent adoption of laparoscopic and robotic-assisted AWR techniques. Current guidelines have not accounted for the spectrum of repair complexity and have relied on expert opinion. This study aimed to develop an evidence-based definition and coding algorithm for AWR based on myofascial releases performed.

METHODS

Three vignettes and associated outcomes were evaluated in adult patients who underwent elecive VHR with mesh between 2013 and 2020 in the Abdominal Core Health Quality Collaborative including: (1) no myofascial release (NR), (2) posterior rectus sheath myofascial release (PRS), and (3) PRS with transversus abdominis release or external oblique release (PRS-TA/EO). The primary outcome measure was operative time based on the following categories (min): 0-59, 60-119, 120-179, 180-239, and 240 + ; secondary outcomes included disease severity measures and 30-day postoperative outcomes.

RESULTS

15,246 patients were included: 7287(NR), 2425(PRS), and 5534(PRS-TA/EO). Operative time increased based on myofascial releases performed: 180-239 min (p < 0.05): NR(5%), PRS(23%), PRS-TA/EO(28%) and greater than 240 min (p < 0.05): NR (4%), PRS (17%), PRS-TA/EO(44%). A dose-response effect was observed for all secondary outcome measures indicative of three distinct levels of patient complexity and outcomes for each of the three vignettes.

CONCLUSION

AWR is defined as VHR including myofascial release. Coding for AWR should reflect the actual effort used to manage these patients. We propose an evidence-based approach to AWR coding that focuses on myofascial release and is inclusive of minimally invasive techniques.

Risk Factors for Surgical Site Infection in the Undeserved Population After Ventral Hernia Repair: A 3936 Patient Single-Center Study Using National Surgical Quality Improvement Project

Background: Ventral hernia repair (VHR) is one of the most common surgical procedures performed in the United States. Surgical site infections (SSI) carry significant morbidity for the patient and pose a very challenging problem for the surgeon, associated with up to 6.6% of cases. Thus, surgeons should be well versed in the risk factors implicated in SSI after VHR. Given the high burden of diabetes, obesity, and smoking in our patient population, we sought to study the rate of SSI and the risk factors that led to SSI in our population. Study Design: This is a retrospective study using the American College of Surgeons-National Surgical Quality Improvement Project (ACS-NSQIP) database for the years 2014-2019. We identified patients who underwent VHR at a single institution in the Bronx, New York. The rate of SSI was calculated, and then, risk factors for SSI were identified using logistic regression analysis. Results: A total of 3936 patients underwent VHR. Incisional hernias made up 41% of the cohort, and there were 37.4% laparoscopic repairs. During the 30-day follow-up, SSI was identified in 101 patients (2.6%). Factors associated with SSI include emergent surgery (adjusted odds ratio [aOR] = 2.57), body mass index >35 kg/m² (aOR = 2.38), insulin-dependent diabetes mellitus (aOR = 2.36), and incisional hernia (aOR = 1.81). In addition, a laparoscopic approach was found to be a protective factor (aOR = 0.43, 95% confidence interval 0.25-0.75). Surprisingly, different from other studies, smoking cigarettes was not associated with SSI in our cohort. Conclusions: The rate of SSI after VHR in our institution is 2.6%, which is within that reported in the literature. Most of the variables associated with SSI are modifiable and are similar to those previously reported. Laparoscopic repairs appear to be protective for its occurrence.

Synthetic Mesh in Contaminated Abdominal Wall Surgery: Friend or Foe? A Literature Review

INTRODUCTION

The use of synthetic mesh in contaminated fields is controversial. In the last decade, published data have grown in this matter suggesting favorable outcomes. However, multiple variables and scenarios that influence the results still make difficult to obtain convincing recommendations.

METHODS

We performed a review of relevant available data in English regarding the use of synthetic meshes in contaminated abdominal wall surgery using the Medline database. Articles including patients undergoing ventral hernia in contaminated fields were included for analysis.

RESULTS

Most studies support the use of synthetic meshes for ventral hernia repair in contaminated fields, as they have shown lower recurrence rate and similar wound morbidity. Although no mesh seems ideal in this setting, most surgeons advocate for the use of reduced-in-weight polypropylene mesh. Sublay location of the prosthesis associated with complete fascial closure appears to offer better results in these patients. In addition, current evidence suggests that the use of prophylactic synthetic mesh when performing a stoma or for stoma reversal incisional hernias might be beneficial.

CONCLUSION

A better understanding of surgical site occurrences and its prevention, as well as the introduction of new reduced-in-weight meshes have allowed using synthetic meshes in a contaminated field. Although the use of mesh has indeed shown promising results in these patients, the surgical team should still balance pros and cons at the time of placing synthetics in contaminated fields.

Controversies in Abdominal Wall Reconstruction

This article discuses current controversies in abdominal wall reconstruction, including the standardization of outcome reporting, mesh selection, the utility of robotic surgery in ventral hernia repair, and role for prophylactic stoma mesh at the time of permanent end colostomy formation. The current state of the literature pertaining to these topics is reviewed in detail.

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.

Management of ventral hernia defect during enterocutaneous fistula takedown: practice patterns and short-term outcomes from the Abdominal Core Health Quality Collaborative

BACKGROUND

An enterocutaneous fistula (ECF) with an associated large hernia defect poses a significant challenge for the reconstructive surgeon. We aim to describe operative details and 30-day outcomes of elective hernia repair with an ECF when performed by surgeons participating in the Abdominal Core Health Quality Collaborative (ACHQC).

STUDY DESIGN

Patients undergoing concomitant hernia and ECF elective repair were identified within the ACHQC. Outcomes of interest were operative details and 30-day rates of surgical site infections (SSI), surgical site occurrences requiring procedural intervention (SSOPI), medical complications, and mortality.

RESULTS

170 patients were identified (mean age 60 years, 52.4% females, mean BMI 32.3 kg/m²). 106 patients (62%) had small-bowel ECFs, mostly managed with resection without diversion. 30 patients (18%) had colonic ECFs, which were managed with resection without diversion (14%) or resection with diversion (6%). 100 (59%) had a prior mesh in place, which was removed in 90% of patients. Hernias measured 14 cm ± 7 in width, and 68 (40%) had a myofascial release performed (41 TARs). Mesh was placed in 115 cases (68%), 72% as a sublay, and more frequently of biologic (44%) or permanent synthetic (34%) material. 30-day SSI was 18% (37% superficial, 40% deep), and 30-day SSOPI was 21%. 19 patients (11%) were re-operated: 8 (8%) due to a wound complication and 4 (2%) due to a missed enterotomy. Two infected meshes were removed, one biologic and one synthetic.

CONCLUSIONS

Surgeons participating in the ACHQC predominantly resect ECFs and repair the associated hernias with sublay mesh with or without a myofascial release. Morbidity remains high, most closely related to wound complications, as such, concomitant definitive repairs should be entertained with caution.

Intraperitonealversusretromuscular mesh placement for open incisional hernias: an analysis of the Americas Hernia Society Quality Collaborative

Background

Incisional hernia repair with mesh improves long-term outcomes, but the ideal mesh position remains unclear. This study compared intraperitoneal versus retromuscular or preperitoneal sublay (RPS) mesh positions for open incisional hernia repairs.

Methods

All patients who had elective open incisional hernia repairs were identified retrospectively in the Americas Hernia Society Quality Collaborative database. The primary outcome was the rate of 30-day surgical-site infection (SSI). Other outcomes of interest included 30-day surgical-site occurrences requiring procedural intervention (SSOPI), hernia-related quality-of-life survey (HerQLes) scores and long-term recurrence. A logistic model was used to generate propensity scores for mesh position using several clinically relevant co-variables. Regression models adjusting for propensity score and baseline characteristics were developed to assess the effect of mesh placement.

Results

A total of 4211 patients were included in the study population: 587 had intraperitoneal mesh and 3624 had RPS mesh. Analysis with propensity score adjustment provided no evidence for differences in SSOPI (odds ratio (OR) 0·79, 95 per cent c.i. 0·49 to 1·26) and SSI (OR 0·91, 0·50 to 1·67) rates or HerQLes scores at 30 days (OR 1·20, 0·79 to 1·82), or recurrence rates (hazard ratio 1·28, 0·90 to 1·82).

Conclusion

Mesh position had no effect on short- or long-term outcomes, including SSOPI and SSI rates, HerQLes scores and long-term recurrence rates.

Value Improvement and Resource Utilization in Complex Abdominal Wall Reconstruction

Although recommendations help guide surgeons’ mesh choice in abdominal wall reconstruction (AWR), financial and institutional pressures may play a bigger role. Standardization of an AWR algorithm may help reduce costs and change mesh preferences. We performed a retrospective review of high- and low-risk patients who underwent inpatient AWR between 2014 and 2016. High risk was defined as immunosuppression and/or history of infection/contamination. Patients were stratified by the type of mesh as biologic/biosynthetic or synthetic. These cohorts were analyzed for outcome, complications, and cost. One hundred twelve patients underwent complex AWR. The recurrence rate at two years was not statistically different between high- and low-risk cohorts. No significant difference was found in the recurrence rate between biologic and synthetic meshes when comparing both high- and low-risk cohorts. The average cost of biologic mesh was $9,414.80 versus $524.60 for synthetic. The estimated cost saved when using synthetic mesh for low-risk patients was $295,391.20. In conclusion, recurrence rates for complex AWR seem to be unrelated to mesh selection. There seems to be an excess use of biologic mesh in low-risk patients, adding significant cost. Implementing a critical process to evaluate indications for biologic mesh use could decrease costs without impacting the quality of care, thus improving the overall value of AWR.

A Current Review of Long-Acting Resorbable Meshes in Abdominal Wall Reconstruction

Concern for chronic infection of a permanent synthetic material in contaminated and "high risk" ventral hernia repairs has led to the development and dissemination of slowly resorbable biosynthetic materials at a lower cost compared with biologic mesh counterparts. Here, we review the preclinical and clinical data available for each long-acting resorbable mesh, with a candid comparison to biologic and synthetic equivalents.

Fight or Flight: The Role of Staged Approaches to Complex Abdominal Wall Reconstruction

Surgeons' comfort with abdominal wall reconstruction techniques and use of prosthetic reinforcement in contaminated fields has made repair of complex hernias during concomitant procedures an attractive endeavor. Understanding the precarious nature of this practice, tenets of thoughtful patient selection, and principles of repair that mitigate morbidity can allow for an educated thought process when deciding whether or not to pursue concomitant abdominal wall reconstruction.

Development of a Disease-based Hernia Program and the Impact on Cost for a Hospital System

OBJECTIVE

The aim of this study was to assess the impact of developing a hernia program on mesh utilization.

BACKGROUND

With the ongoing changes in healthcare, the value of all interventions will see increased scrutiny. Hernia mesh can be one of the most costly components of hernia repairs. A disease-based institutional hernia program that defines roles for mesh utilization and measures outcomes has the potential to add significant value to hospital systems.

METHODS

In August 2014, a disease-based hernia program was initiated across a hospital system. In collaboration with hospital administration, surgical operations, and all surgeons involved in the care of hernia patients, general guidelines for mesh utilization based on CDC wound class were created. All hernia repairs performed between January 2013 and November 2015 were reviewed.

RESULTS

Approximately, 13,937 hernias were repaired during the study period. Biologic mesh was used in 0.4% of clean, 7.1% of clean-contaminated, 38.5% of contaminated, and 58.8% of dirty cases. After initiation of the hernia program there was a reduction in biologic mesh utilization across the system (clean: 66% reduction; clean-contaminated: 63% reduction; contaminated: 55% reduction; dirty: 47% reduction). Surgeons who participated in the hernia program used significantly less biologic mesh in clean (P < 0.01), clean-contaminated (P = 0.01) and contaminated (P < 0.01) hernia repairs.

CONCLUSIONS

The development of a system-wide hernia program based on collaboration with the hospital administration, operating room purchasing and clinicians resulted in a significant reduction in costly mesh utilization. This collaborative effort from all stakeholders involved in the care of a specific disease process could provide a reproducible model to improve the value equation through cost reduction strategies in today's healthcare environment.

"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.

A critical review of the in vitro and in vivo models for the evaluation of anti-infective meshes

BACKGROUND

Infectious complications following mesh implantation for abdominal wall repair appear in 0.7 up to 26.6% of hernia repairs and can have a detrimental impact for the patient. To prevent or to treat mesh-related infection, the scientific community is currently developing a veritable arsenal of antibacterial meshes. The numerous and increasing reports published every year describing new technologies indicate a clear clinical need, and an academic interest in solving this problem. Nevertheless, to really appreciate, to challenge, to compare and to optimize the antibacterial properties of next generation meshes, it is important to know which models are available and to understand them.

PURPOSE

We proposed for the first time, a complete overview focusing only on the in vitro and in vivo models which have been employed specifically in the field of antibacterial meshes for hernia repair.

RESULTS AND CONCLUSION

From this investigation, it is clear that there has been vast progress and breadth in new technologies and models to test them. However, it also shows that standardization or adoption of a more restricted number of models would improve comparability and be a benefit to the field of study.

High Infection Rates in Patients with Long-Segment Dynesys System

BACKGROUND

Infection follow-up in patients stabilized with the Dynesys system. Infection rates were determined in patients who had ≥5 segments stabilized with the Dynesys system.

METHODS

Eighty-three patients with various etiologies were stabilized with the Dynesys system. Long-level stabilization patients were separated from the main group as a result of their high rates of infection.

RESULTS

Long-level stabilizations were performed in 8 of 83 patients. Five patients were determined to have infections including 4 deep infections and 1 superficial infection. In patients with deep infections, 3 of them exhibited chronic infections that lasted for approximately 2 years and the system was removed. A deep infection in 1 patient and a superficial infection in 1 patient were diagnosed after 1 month. The early-diagnosed deep infection patient was treated with wound irrigation and antibiotics. The system was not removed, and the wound was closed with daily dressing after 45 days. One superficial infection patient was only treated with daily dressing, and the infection healed within 2 weeks. The infectious agent was determined in 2 patients. Three patients in the chronic infection group underwent a surgical procedure to remove the system. Specific antibiotic treatments were administered to patients whose infectious agents were identified. The remaining patients were treated with wide-spectrum antibiotics.

CONCLUSIONS

We report that long-level stabilization with the Dynesys system results in a high infection rate.

Infections associated with mesh repairs of abdominal wall hernias: Are antimicrobial biomaterials the longed-for solution?

The incidence of mesh-related infection after abdominal wall hernia repair is low, generally between 1 and 4%; however, worldwide, this corresponds to tens of thousands of difficult cases to treat annually. Adopting best practices in prevention is one of the keys to reduce the incidence of mesh-related infection. Once the infection is established, however, only a limited number of options are available that provides an efficient and successful treatment outcome. Over the past few years, there has been a tremendous amount of research dedicated to the functionalization of prosthetic meshes with antimicrobial properties, with some receiving regulatory approval and are currently available for clinical use. In this context, it is important to review the clinical importance of mesh infection, its risk factors, prophylaxis and pathogenicity. In addition, we give an overview of the main functionalization approaches that have been applied on meshes to confer anti-bacterial protection, the respective benefits and limitations, and finally some relevant future directions.

The preventive effect of ambroxol hydrochloride chitosan on postoperative intraperitoneal adhesion formation in a rat model

BACKGROUND

This study aimed to investigate the effects of ambroxol hydrochloride chitosan reduced the degree of peritoneal adhesion.

METHODS

A total of 120 Sprague-Dawley (SD) rats were experimented, group A: the damaged peritoneal was covered with ambroxol hydrochloride chitosan, group B: chitosan membrane only, group C: nothing. Enzyme-linked immunosorbent assay (ELISA), western blotting, and immunohistochemistry (IHC) were used to observe the expression of TNF-α and NF-κB p65.

RESULTS

TNF-α and NF-κB p65 in group A significantly decreased in comparison with the controls. IHC showed TNF-α and NF-κB p65 were significantly down-regulated in group A. Adhesion grade in the treatment group was significantly lower than in controls.

CONCLUSION

Ambroxol hydrochloride chitosan reduced the degree of peritoneal adhesion.

Outcomes of Posterior Component Separation With Transversus Abdominis Muscle Release and Synthetic Mesh Sublay Reinforcement

OBJECTIVE

To evaluate the safety and efficacy of transversus abdominis muscle release (TAR) with retrorectus synthetic mesh reinforcement in a large series of complex hernia patients.

BACKGROUND

Posterior component separation via TAR during abdominal wall reconstruction (AWR) continues to gain popularity. Although our early experience with TAR has been promising, long-term outcomes have not been reported.

METHODS

From December 2006 to December 2014, consecutive patients undergoing open AWR utilizing TAR were identified in our prospectively maintained database and reviewed retrospectively. Main outcome measures included demographics, perioperative details, wound complications, and recurrences.

RESULTS

During the study period, 428 consecutive TAR procedures were analyzed. Mean age was 58, with mean body mass index 34.4 kg/m (range 20-65). Major comorbidities included diabetes (21%), chronic obstructive pulmonary disease (12%), and immunosuppression (3%). Mean hernia defect area was 606 cm (range 180-1280) and average mesh size was 1220 cm (range 600-4500). The majority of cases (66%) were clean, 26% were clean-contaminated, and 8% were contaminated. Eighty (18.7%) surgical-site events occurred, of which 39 (9.1%) were surgical-site infections. Three patients required mesh debridement; however, no instances of mesh explantation occurred. Of the 347 (81%) patients with at least 1-year follow-up (mean 31.5 mo), there were 13 (3.7%) recurrences.

CONCLUSIONS

Complex AWR represents a formidable surgical challenge. In this large series, we demonstrated that posterior component separation via TAR with wide synthetic mesh sublay provides a very durable repair with low morbidity, even in comorbid patients with large defects. We strongly advocate TAR as a robust addition to the armamentarium of reconstructive surgeons.

Infection prevention using affinity polymer-coated, synthetic meshes in a pig hernia model

BACKGROUND

Given concern for hernia mesh infection, surgeons often use biologic mesh which may provide reduced risk of infection but at the cost of decreased repair durability. We evaluated mesh coating to provide sustained release of antibiotics to prevent prosthetic mesh infection and also allow a durable repair.

MATERIALS AND METHODS

Cyclodextrin-based polymer was crosslinked onto multifilament polyester mesh and loaded with vancomycin (1.75 mg/cm²). Pigs received modified meshes (n = 6) or normal, untreated meshes (n = 4), which were implanted into acute 10 × 5 cm ventral hernia, then directly inoculated with 10⁶ colony-forming unit (CFU) of methicillin-resistant Staphylococcus aureus (MRSA). These were compared to animals receiving normal, uninfected mesh. All mesh was secured in an underlay bridge manner, and after 30 d, the abdominal wall was removed for quantitative bacterial culture and biomechanical analysis.

RESULTS

All animals survived 30 d. All six animals with coated mesh cleared MRSA infection. The four control animals did not clear MRSA (P = 0.005). Quantitative bacterial load was higher in standard mesh versus drug-delivery mesh group (2.34 × 10⁴versus 80.9 CFU/gm). These data were log₁₀-transformed and analyzed by Welch's t-test (P = 0.001). Minimum number of CFUs detectable by assay (300) was used instead of zero. Biomechanical analysis of controls (1.82 N/mm infected; 1.71 N/mm uninfected) showed no difference to the modified meshes (1.31 N/mm) in tissue integration (P = 0.15).

CONCLUSIONS

We successfully prevented synthetic mesh infection in a pig model using a cyclodextrin-based polymer to locally deliver vancomycin to the hernia repair site and clearing antibiotic-resistant bacteria. Polymer coating did not impact the strength of the hernia repair.

Synthetic versus Biologic Mesh in Single-Stage Repair of Complex Abdominal Wall Defects in a Contaminated Field

BACKGROUND

Synthetic meshes have been used with varying rates of success in a contaminated setting, although their use is not widely accepted because of concerns for infection. A biologic mesh (BM) is assumed to be more resistant to infection than a synthetic mesh; however, sparse clinical data support this theory. The hypothesis for this study: Uncoated polypropylene synthetic mesh (USM) can be used to obtain a durable repair in the setting of a contaminated abdominal wall reconstruction (AWR) in a single-stage procedure with comparable infectious outcomes to a biologic mesh repair.

PATIENTS AND METHODS

We performed a retrospective chart review on contaminated AWR, comparing 34 BM with 24 USM with infection as the primary outcome of interest. Secondary outcomes were re-admission and re-operation. We also investigated the microbial isolates that were cultured.

RESULTS

Mesh groups were similar in their demographics, duration of surgery, previous mesh, surgical site class, and source of contamination. Length of stay was 4 d longer in BM, p = 0.01. Overall infection rate was 50% for BM vs. 29.2% for USM, p = 0.18. Treatment in case of infection was similar across both groups. Gram positive bacteria comprised 39% of BM microbiology vs. 63% for USM. Re-admission rate was 52.9% for BM versus 45.8% for USM, p > 0.5. The BMs re-admitted for surgical site infection/abdominal abscess were 38.9% versus 55.6% for USM. No USM were re-admitted for seroma versus 33.3% of BM, p = 0.06. Re-operation rate was 26.5% for BM versus 33.3% for USM, p > 0.5. Procedures performed at re-operation were similar between groups. Regression analysis did not demonstrate an association between mesh type and our outcomes.

CONCLUSION

Our results show that synthetic meshes are not inferior to biologic meshes in contaminated AWR. This is important in view of the tremendous cost disparity between these two products and the questionable ability of biologic mesh to offer a durable hernia repair.

Oral, intestinal, and skin bacteria in ventral hernia mesh implants

Background

In ventral hernia surgery, mesh implants are used to reduce recurrence. Infection after mesh implantation can be a problem and rates around 6–10% have been reported. Bacterial colonization of mesh implants in patients without clinical signs of infection has not been thoroughly investigated. Molecular techniques have proven effective in demonstrating bacterial diversity in various environments and are able to identify bacteria on a gene-specific level.

Objective

The purpose of this study was to detect bacterial biofilm in mesh implants, analyze its bacterial diversity, and look for possible resemblance with bacterial biofilm from the periodontal pocket.

Methods

Thirty patients referred to our hospital for recurrence after former ventral hernia mesh repair, were examined for periodontitis in advance of new surgical hernia repair. Oral examination included periapical radiographs, periodontal probing, and subgingival plaque collection. A piece of mesh (1×1 cm) from the abdominal wall was harvested during the new surgical hernia repair and analyzed for bacteria by PCR and 16S rRNA gene sequencing. From patients with positive PCR mesh samples, subgingival plaque samples were analyzed with the same techniques.

Results

A great variety of taxa were detected in 20 (66.7%) mesh samples, including typical oral commensals and periodontopathogens, enterics, and skin bacteria. Mesh and periodontal bacteria were further analyzed for similarity in 16S rRNA gene sequences. In 17 sequences, the level of resemblance between mesh and subgingival bacterial colonization was 98–100% suggesting, but not proving, a transfer of oral bacteria to the mesh.

Conclusion

The results show great bacterial diversity on mesh implants from the anterior abdominal wall including oral commensals and periodontopathogens. Mesh can be reached by bacteria in several ways including hematogenous spread from an oral site. However, other sites such as gut and skin may also serve as sources for the mesh biofilm.

Evaluation of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh in a porcine model of ventral hernia repair

Background

The objective of this study was to evaluate the mechanical and histological properties of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh (Phasix™ ST) compared to partially absorbable (Ventralight™ ST), fully absorbable (Phasix™), and biologically derived (Strattice™) meshes in a porcine model of ventral hernia repair.

Methods

Bilateral abdominal surgical defects were created in twenty-four Yucatan pigs, repaired with intraperitoneal (Phasix™ ST, Ventralight™ ST) or retromuscular (Phasix™, Strattice™) mesh, and evaluated at 12 and 24 weeks (n = 6 mesh/group/time point).

Results

Prior to implantation, Strattice™ demonstrated significantly higher (p < 0.001) strength (636.6 ± 192.1 N) compared to Ventralight™ ST (324.3 ± 37.1 N), Phasix™ ST (206.9 ± 11.3 N), and Phasix™ (200.6 ± 25.2 N). At 12 and 24 weeks, mesh/repair strength was significantly greater than NAW (p < 0.01 in all cases), and no significant changes in strength were observed for any meshes between 12 and 24 weeks (p > 0.05). Phasix™ mesh/repair strength was significantly greater than Strattice™ (p < 0.001) at 12 and 24 weeks, and Ventralight™ ST mesh/repair strength was significantly greater than Phasix™ ST mesh (p < 0.05) at 24 weeks. At 12 and 24 weeks, Phasix™ ST and Ventralight™ ST were associated with mild inflammation and minimal–mild fibrosis/neovascularization, with no significant differences between groups. At both time points, Phasix™ was associated with minimal–mild inflammation/fibrosis and mild neovascularization. Strattice™ was associated with minimal inflammation/fibrosis, with minimal neovascularization at 12 weeks, which increased to mild by 24 weeks. Strattice™ exhibited significantly less neovascularization than Phasix™ at 12 weeks and significantly greater inflammation at 24 weeks due to remodeling.

Conclusions

Phasix™ ST demonstrated mechanical and histological properties comparable to partially absorbable (Ventralight™ ST) and fully resorbable (Phasix™) meshes at 12 and 24 weeks in this model. Data also suggest that fully absorbable meshes with longer-term resorption profiles may provide improved mechanical and histological properties compared to biologically derived scaffolds.

Evaluation of the Antimicrobial Efficacy of a Novel Rifampin/Minocycline-Coated, Noncrosslinked Porcine Acellular Dermal Matrix Compared With Uncoated Scaffolds for Soft Tissue Repair

Background Despite meticulous aseptic technique and systemic antibiotics, bacterial colonization of mesh remains a critical issue in hernia repair. A novel minocycline/rifampin tyrosine-coated, noncrosslinked porcine acellular dermal matrix (XenMatrix AB) was developed to protect the device from microbial colonization for up to 7 days. The objective of this study was to evaluate the in vitro and in vivo antimicrobial efficacy of this device against clinically isolated methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Methods XenMatrix AB was compared with 5 existing uncoated soft tissue repair devices using in vitro methods of zone of inhibition (ZOI) and scanning electron microscopy (SEM) at 24 hours following inoculation with MRSA or E coli These devices were also evaluated at 7 days following dorsal implantation and inoculation with MRSA or E coli (60 male New Zealand white rabbits, n = 10 per group) for viable colony-forming units (CFU), abscess formation and histopathologic response, respectively. Results In vitro studies demonstrated a median ZOI of 36 mm for MRSA and 16 mm for E coli for XenMatrix AB, while all uncoated devices showed no inhibition of bacterial growth (0 mm). SEM also demonstrated no visual evidence of MRSA or E coli colonization on the surface of XenMatrix AB compared with colonization of all other uncoated devices. In vivo XenMatrix AB demonstrated complete inhibition of bacterial colonization, no abscess formation, and a reduced inflammatory response compared with uncoated devices. Conclusion We demonstrated that XenMatrix AB possesses potent in vitro and in vivo antimicrobial efficacy against clinically isolated MRSA and E coli compared with uncoated devices.

Development of a novel murine model for treatment of infected mesh scenarios

BACKGROUND

Indications regarding hernia repair after removal of previously infected prostheses remain unclear. Patients may receive staged primary repair or single-stage reconstructions, neither of which may be ideal. Although animal models have simulated contamination by direct inoculation of implants with bacteria, there remains a paucity of literature, which simulates a field following mesh infection and removal. We aimed to develop a murine model to mimic this complex scenario to allow for further testing of various implants.

METHODS

Thirty-six female CL57BL/6J mice underwent implantation of a 0.7 × 0.7 cm polyester mesh in the dorsal subcutaneous position. Wounds were closed and inoculated with 100 µL containing 1 × 10⁴ CFU of GFP-labeled MSSA. After 2 weeks, the infected mesh was removed and the cavity was copiously irrigated with saline. Mice were split into four groups: with three groups receiving new polyester, polypropylene, and porcine mesh and remaining as non-mesh controls. Mice were survived for another 2 weeks and underwent necropsy. Gross infection was evaluated at 2 and 4 weeks. Tissue homogenization and direct plating to recover GFP MSSA was completed at 4 weeks.

RESULTS

At 2 weeks, all mice were noted to have gross mesh infection. One animal died due to overwhelming infection and wound breakdown. At 4 weeks, 5/6 (83 %) control mice who did not have a second mesh implantation had full clearance of their wounds. In contrast, 9/10 (90 %) mice with re-implantation of polypropylene were noted to have pus and recovery of GFP MSSA on plating. This was also observed in 100 % of mice with polyester and porcine mesh.

CONCLUSION

Our novel murine model demonstrates that mesh re-implantation after infected mesh removal results in infection of the newly placed prosthesis, regardless of the material characteristic or type. This model lays foundation for development and investigation of implants for treatment strategies following infected mesh removal.

Active Staphylococcus aureus infection: Is it a contra-indication to the repair of complex hernias with synthetic mesh? A prospective observational study on the outcomes of synthetic mesh replacement, in patients with chronic mesh infection caused by Staphylococcus aureus

INTRODUCTION

The management of chronic mesh infection is challenging and controversial. The use of synthetic material to repair the abdominal wall in the infected setting is not recommended, especially in the presence of active infection caused by Staphylococcus aureus.

METHODS

This is a prospective observational study designed to evaluate the outcomes in patients with active mesh infection caused by Staphylococcus aureus. Patients underwent simultaneous removal and replacement of polypropylene mesh. The treatment protocol included the complete removal of infected mesh, followed by the anatomical reconstruction, and reinforcement of the abdominal wall using a new onlay polypropylene mesh. Early and late wound complications, medical complications, and hernia recurrences were analyzed.

RESULTS

From 2006 until 2014, 22 patients with a mean age of 57.2 years and mean BMI of 29,3 kg/m2 were studied. Sinuses were present in 21 patients. A recurrent ventral hernia was observed in 14 patients; two patients required a complex abdominal wall reconstruction due to enteric fistulas. Bowel resections or other potentially contaminated procedures were associated in 10 patients. Fourteen patients (63.6%) had an uneventful postoperative course; 5 (22.7%) patients had wound infections requiring debridement and three required partial (2) or total (1) mesh removal. Two patients died due to medical complications. Adverse results on long-term follow-up included one hernia recurrence after complete mesh removal and one persistent sinus after partial mesh removal requiring a reoperation to remove mesh remnants. All of the patients were considered free of infection after a mean follow-up of 44 months.

CONCLUSIONS

Synthetic mesh replacement in patients with active Staphylococcus aureus infection has an acceptable incidence of postoperative wound infection and prevents hernia recurrence. Large-pore polypropylene mesh is a suitable material to be used in the infected surgical field as an onlay graft.

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.

An in vivo analysis of Miromesh--a novel porcine liver prosthetic created by perfusion decellularization

BACKGROUND

Bioprosthetics derived from human or porcine dermis and intestinal submucosa have dense, homogenous, aporous collagen structures that potentially limit cellular penetration, undermining the theoretical benefit of a "natural" collagen scaffold. We hypothesized that Miromesh-a novel prosthetic derived from porcine liver by perfusion decellularization-provides a more optimal matrix for tissue ingrowth.

METHODS

Thirty rats underwent survival surgery that constituted the creation of a 4 × 1 cm abdominal defect and simultaneous bridged repair. Twenty rats were bridged with Miromesh, and 10 rats were bridged with non-cross-linked porcine dermis (Strattice). Ten Miromesh and all 10 Strattice were rinsed in vancomycin solution and inoculated with 10(4) colony-forming units of green fluorescent protein-labeled Staphylococcus aureus (GFP-SA) after implantation. Ten Miromesh controls were neither soaked nor inoculated. No animals received systemic antibiotics. All animals were euthanized at 90 d and underwent an examination of their gross appearance before being sectioned for quantitative bacterial culture and histologic grading. A pathologist scored specimens (0-4) for cellular infiltration, acute inflammation, chronic inflammation, granulation tissue, foreign body reaction, and fibrous capsule formation.

RESULTS

All but one rat repaired with Strattice survived until the 90-d euthanization. All quantitative bacterial cultures for inoculated specimens were negative for GFP-SA. Of nine Strattice explants, none received a cellular infiltration score >0, consistent with a poor tissue-mesh interface observed grossly. Of 10 Miromesh explants also inoculated with GFP-SA, seven of 10 demonstrated cellular infiltration with an average score of +2.7 ± 0.8, whereas sterile Miromesh implants received an average score of 0.8 ± 1.0. Two inoculated Miromesh implants demonstrated acute inflammation and infection on histology.

CONCLUSIONS

A prosthetic generated from porcine liver by perfusion decellularization provides a matrix for superior cellular infiltration compared with non-cross-linked porcine dermis.

A case report on management of synergistic gangrene following an incisional abdominal hernia repair in an immunocompromised obese patient

•

Synergistic gangrene is generated from bacterial colonies present in necrotic tissues. Within our case, continual removal of the necrotic burden was essential in wound bed preparation, reducing contamination and tissue destruction.

•

In surgery, wide necrotic wound debridement, early and repetitive wound drainages with the use of a large pore polypropylene mesh with a detailed surgical follow up is recommended.

•

This case has demonstrated how a planned multidisciplinary action can produce prosperous results in a severely obese immunocompromised patient with an SSI, following an incisional hernia repair.

•

Our selective case is unique within current literature, being the first to illustrate mesh salvage in a morbid obese patient with chronic lymphoblastic leukaemia.

Introduction

We present a case on conservative management of salvaging the mesh in an immunocompromised morbidly obese patient, who developed a synergistic gangrene infection following a primary open mesh repair of an incisional hernia.

Presentation of case

Our patient presented with a surgical wound infection, comorbidities were Chronic Lymphoblastic Leukemia (CLL), Body Mass Index (BMI) of 50, hypertension and diet controlled type-2 diabetes. In surgery, wide necrotic wound debridement, early and repetitive wound drainages with the use of a large pore polypropylene mesh and a detailed surgical follow up was required. High dose intravenous broad-spectrum antibiotic treatment and Negative Pressure Wound Therapy (NPWT) was administrated in combination with adopting a multidisciplinary approach was key to our success.

Discussion

Stoppa Re et al. complied a series of 360 ventral hernia mesh repairs reporting an infection rate of 12% that were managed conservatively. However, our selective case is unique within current literature, being the first to illustrate mesh salvage in a morbid obese patient with CLL. Recent modifications in mesh morphology, such as lower density, wide pores, and lighter weight has led to considerable improvements regarding infection avoidance.

Conclusion

This case has demonstrated how a planned multidisciplinary action can produce prosperous results in a severely obese immunocompromised patient with an SSI, following an incisional hernia repair.

Emerging Trends in Abdominal Wall Reinforcement: Bringing Bio-Functionality to Meshes

Abdominal wall hernia is a recurrent issue world-wide and requires the implantation of over 1 million meshes per year. Because permanent meshes such as polypropylene and polyester are not free of complications after implantation, many mesh modifications and new functionalities have been investigated over the last decade. Indeed, mesh optimization is the focus of intense development and the biomaterials utilized are now envisioned as being bioactive substrates that trigger various physiological processes in order to prevent complications and to promote tissue integration. In this context, it is of paramount interest to review the most relevant bio-functionalities being brought to new meshes and to open new avenues for the innovative development of the next generation of meshes with enhanced properties for functional abdominal wall hernia repair.

Central failures of lightweight monofilament polyester mesh causing hernia recurrence: a cautionary note

INTRODUCTION

Uncoated, lightweight, macroporous,monofilament mesh has been shown to demonstrate improved bacterial clearance, better tissue integration,reduced foreign body response, and less chronic pain with equivalent durability for hernia repair. These findings led us to use a new lightweight monofilament polyester mesh (Parietex TCM, Covidien). Here, we report our experience with this mesh in open incisional hernia repair.

METHODS

Patients undergoing incisional hernia repair with Parietex TCM were retrospectively identified within our prospectively maintained database. Patient demographics,operative characteristics, and follow-up were reviewed. Outcome parameters included 90-day wound morbidity and hernia recurrence.

RESULTS

In 2011, 36 patients (mean age 56.8; mean BMI32.4 kg/m2) underwent open incisional hernia repair with retrorectus mesh placement by two surgeons (MJR, YWN) at Case Medical Center. Anterior and posterior fascial closure was achieved in all cases. Wound morbidity included seven surgical site occurrences: four superficial infections that resolved with antibiotics, one wound dehiscence requiring wet-to-dry packing, and two seromas that resolved without intervention. With a mean follow-up of 13 months, 8 (22%) recurrences have occurred. On reoperation, 7 (19%) of these patients had mechanical failure or fracturing of the mesh. No confounding variables were identified by univariate analysis of patient demographics,operative characteristics, or wound morbidity.

CONCLUSION

Lightweight monofilament polyester mesh (Parietex TCM) appears to have a high incidence of mechanical failure in the context of open incisional hernia repair. While this limitation may ultimately be revealed asa weakness of all lightweight mesh, surgeons should be aware that these failures have already been documented.

Gentamicin for prevention of intraoperative mesh contamination: demonstration of high bactericide effect (in vitro) and low systemic bioavailability (in vivo)

INTRODUCTION

Mesh infection is a severe complication after incisional hernia repair and occurs in 1-3 % of all open mesh implantations. For this reason, topical antimicrobial agent applied directly to the mesh is often used procedure. So far, however, this procedure lacks a scientific basis.

MATERIALS AND METHODS

Two different meshes (Parietex™, Covidien; Ultrapro™, Ethicon Johnson & Johnson) were incubated with increasing amounts of three different Staphylococcus aureus strains (ATCC 25923; Mu50; ST239) with or without gentamicin and growth ability were determined in vitro. To further address the question of the systemic impact of topic gentamicin, serum levels were analyzed 6 and 24 h after implantation of gentamicin-impregnated multifilament meshes in 19 patients.

RESULTS

None of the gentamicin-impregnated meshes showed any bacterial growth in vitro. This effect was independent of the mesh type for all the tested S. aureus strains. In the clinical setting, serum gentamicin levels 6 h after implantation of the gentamicin-impregnated meshes were below the through-level (range 0.4-2.9 mg/l, mean 1.2 ± 0.7 mg/l). After 24 h the gentamicin serum levels in all patients had declined 90-65 % of the 6 h values.

CONCLUSION

Local application of gentamicin to meshes can completely prevent the growth of even gentamicin-resistant S. aureus strains in vitro. The systemic relevance of gentamicin in the clinical controls showed to be very low, without reaching therapeutic concentrations.