Prospective evaluation of poly-4-hydroxybutyrate mesh in CDC class I/high-risk ventral and incisional hernia repair: 18-month follow-up

Emerging materials and technologies for advancing bioresorbable surgical meshes

Surgical meshes play a significant role in the treatment of various medical conditions, such as hernias, pelvic floor issues, guided bone regeneration, and wound healing. To date, commercial surgical meshes are typically made of non-absorbable synthetic polymers, notably polypropylene and polytetrafluoroethylene, which are associated with postoperative complications, such as infections. Biological meshes, based on native tissues, have been employed to overcome such complications, though mechanical strength has been a main disadvantage. The right balance in mechanical and biological performances has been achieved by the advent of bioresorbable meshes. Despite improvements, recurrence of clinical complications associated with surgical meshes raises significant concerns regarding the technical adequacy of current materials and designs, pointing to a crucial need for further development. To this end, current research focuses on the design of meshes capable of biomimicking native tissue and facilitating the healing process without post-operative complications. Researchers are actively investigating advanced bioresorbable materials, both synthetic polymers and natural biopolymers, while also exploring the performance of therapeutic agents, surface modification methods and advanced manufacturing technologies such as 4D printing. This review seeks to evaluate emerging biomaterials and technologies for enhancing the performance and clinical applicability of the next-generation surgical meshes. STATEMENT OF SIGNIFICANCE: In the ever-transforming landscape of regenerative medicine, the embracing of engineered bioabsorbable surgical meshes stands as a key milestone in addressing persistent challenges and complications associated with existing treatments. The urgency to move beyond conventional non-absorbable meshes, fraught with post-surgery complications, emphasises the necessity of using advanced biomaterials for engineered tissue regeneration. This review critically examines the growing field of absorbable surgical meshes, considering their potential to transform clinical practice. By strategically combining mechanical strength with bioresorbable characteristics, these innovative meshes hold the promise of mitigating complications and improving patient outcomes across diverse medical applications. As we navigate the complexities of modern medicine, this exploration of engineered absorbable meshes emerges as a promising approach, offering an overall perspective on biomaterials, technologies, and strategies adopted to redefine the future of surgical meshes.

Long-term results with biosynthetic absorbable P4HB mesh in ventral abdominal wall repair: a multicentre analysis

BACKGROUND

The aim of this multicentre study was to analyse the outcomes of biosynthetic absorbable poly-4-hydroxybutyrate (P4HB) prosthesis implantation in patients undergoing ventral hernia repair (VHR) in the context of different degrees of contamination.

METHODS

From May 2016 to December 2021, a multicentre retrospective analysis of patients who underwent elective or urgent hernia repair with P4HB prosthesis was performed in seven hospitals in Spain and Portugal. Patients with a postoperative follow-up of less than 20 months and those within the theoretical period of prosthesis resorption were excluded from the study. Regarding the degree of contamination, patients were assessed according to the modified Ventral Hernia Working Group (VHWG) classification. Epidemiological data, hernia characteristics, surgical and postoperative variables (Clavien-Dindo classification) of these patients were analyzed. Risk factors related to long-term recurrence were studied by a multivariate analysis.

RESULTS

In 236 cases of P4HB prosthesis implantation, repair in cases of Grade 3 was the most frequent (49.1%), followed by Grade 2 in 42.3% of cases and Grade 1 in 8.4%. The most frequent complications were Grade 1, with the majority occurring during the first year. The overall rate of surgical site occurrences (SSO) was 30%. The hernia recurrence rate was 14.4% (n = 34), with a mean postoperative follow-up time of 41 months (22-61). The multivariate analysis showed that the onlay location of the mesh (OR 1.07; CI 1.42-2.70, p = 0.004) was a significant independent risk factor for recurrence.

CONCLUSIONS

The use of a P4HB bioresorbable mesh for the VHR with different degrees of contamination leads to favourable results overall, with an acceptable rate of hernia recurrence. The onlay location of the P4HB prosthesis is the main factor in recurrence in both elective and emergency settings.

Three-year follow-up of the grip concept: an open, prospective, observational registry study on biomechanically calculated abdominal wall repair for complex incisional hernias

PURPOSE

We studied the effectiveness of biomechanically calculated abdominal wall reconstructions for incisional hernias of varying complexity in an open, prospective observational registry trial.

METHODS

From July 1st, 2017 to December 31st, 2020, four hospitals affiliated with the University of Heidelberg recruited 198 patients with complex incisional hernias. Hernias were repaired using biomechanically calculated reconstructions and materials classified on their gripping force towards cyclic load. This approach determines the required strength preoperatively based on the hernia size, using the Critical Resistance to Impacts related to Pressure. The surgeon is supported in reliably determining the Gained Resistance, which is based on the mesh-defect-area-ratio, as well as other mesh and suture factors, and the tissue stability. Tissue stability is defined as a maximum distension of 1.5 cm upon a Valsalva maneuver. In complex cases, a CT scan of the abdomen can be used to assess unstable tissue areas both at rest and during Valsalva's maneuver.

RESULTS

Larger and stronger gripping meshes were required for more complex cases to achieve a durable repair, especially for larger hernia sizes. To achieve durable repairs, the number of fixation points increased while the mesh-defect area ratio decreased. Performing these repairs required more operating room time. The complication rate remained low. Less than 1% of recurrences and low pain levels were observed after 3 years.

CONCLUSIONS

Biomechanical stability, defined as the resistance to cyclic load, is crucial in preventing postoperative complications, including recurrences and chronic pain.

Robotic transversus abdominis release (TAR) for ventral hernia repairs is associated with low surgical site occurrence rates and length of stay despite increasing modifiable comorbidities

PURPOSE

Modifiable comorbidities (MCMs) have previously been shown to complicate postoperative wound healing occasionally leading to surgeon hesitancy to repair ventral hernias prior to preoperative optimization of comorbidities. This study describes the effects of MCMs on surgical site occurrences (SSOs) and hospital length of stay (LOS) following robotic transversus abdominis release (TAR) with poly-4-hydroxybutyrate (P4HB) resorbable biosynthetic mesh retromuscular sublay for ventral hernia repair in patients who had not undergone preoperative optimization.

METHODS

A single-surgeon retrospective review was performed for patients who underwent the robotic TAR procedure with P4HB mesh between January 2015 and May 2022. Patients were stratified by the amount of MCMs present: 0, 1, or 2 + . MCMs included obesity, diabetes, and current tobacco use. Patient data was analyzed for the first 60 days following their operation. Primary outcomes included 60-day SSO rates and hospital LOS.

RESULTS

Three hundred and thirty-four subjects met the inclusion criteria for SSO and prolonged LOS analysis. 16.8% had no MCM, 56.1% had 1 MCM, and 27% had 2 + MCMs. No significant difference in SSO was seen between the 3 groups; however, having 2 + MCMs was significantly associated with increased odds of SSO (odds ratio 3.25, P = .019). When the groups were broken down, only having a history of diabetes plus obesity was associated with significantly increased odds of SSO (odds ratio 3.54, P = .02). No group showed significantly increased odds of prolonged LOS.

CONCLUSION

2 + MCMs significantly increase the odds of SSO, specifically in patients who have a history of diabetes and obesity. However, the presence of any number of MCMs was not associated with increased odds of prolonged LOS.

Ventral hernia repair using bioresorbable poly-4-hydroxybutyrate mesh in clean and contaminated surgical fields: a systematic review and meta-analysis

PURPOSE

Use of biologic or synthetic mesh in hernia repair shifts is based on evolving evidence. Poly-4-hydroxybutyrate (P4HB) biosynthetic mesh is a potential alternative to biologic and synthetic mesh in ventral hernia repair (VHR). This meta-analysis assesses the efficacy of P4HB mesh in clean and contaminated surgical settings.

METHODS

Two authors searched literature on PubMed, reviewing titles and abstracts of all articles to determine inclusion eligibility. Post-operative data were compared via transformation method to convert the proportion of patients with the outcome of interest into a suitable quantity for random-effects synthesis using STATA software.

RESULTS

Initial search yielded 287 citations. Six studies were included and categorized on whether hernia repairs were conducted in clean (CDC class I) or contaminated cases (CDC class II-IV). The pooled proportion of surgical site infection (SSI), surgical site occurrence (SSO), hernia recurrence, total surgical complications, and reoperation were calculated in 391 clean and 81 contaminated cases. For clean vs. contaminated cases, the following pooled proportions were noted: SSI (2% (CI 0-7%) vs 9% (CI 0-025) (p = 0.03), SSO: 14% (CI 5-25%) vs 35% (CI 22-50%) (p = 0.006), hernia recurrence (8% (CI 1-19%) vs 4% (CI 0-12%) (p = 0.769); surgical complications (17% (CI 6-32%) vs 50% (CI 27-72%) (p = 0.009). Reoperation data were available in 298 clean cases across four studies: 5% (CI 0-15%).

CONCLUSIONS

P4HB biosynthetic mesh may be more effective than previously thought, particularly in clean wounds. P4HB may also be superior to biologic mesh when compared to clinical trial data. Further research is necessary for more direct comparison.

Fully resorbable poly-4-hydroxybutyrate (P4HB) mesh for soft tissue repair and reconstruction: A scoping review

Background

Poly-4-hydroxybutyrate (P4HB) is a fully resorbable, biologically-produced polymer with a strength and flexibility comparable to permanent synthetic polymers. The objective was to identify/summarize all peer-reviewed publications involving P4HB mesh.

Methods

A scoping review was conducted within PubMed and included articles published through October 2022.

Results

A total of n = 79 studies were identified (n = 12 in vitro/bench; n = 14 preclinical; n = 6 commentaries; n = 50 clinical). Of the clinical studies, n = 40 reported results applicable to hernia and n = 10 to plastic/reconstructive surgery and involved patients of all Centers for Disease Control (CDC) wound classes and Ventral Hernia Working Group (VHWG) grades.

Conclusion

P4HB mesh provides long-term hernia repair strength and exhibits promising clinical outcomes beyond its resorption period. Future studies should include randomized controlled trials comparing P4HB to other biomaterials, as well as optimal patient selection, operative technique, long-term outcomes, minimization of potential mesh-related complications, and potential contraindications/complications for P4HB in hernia/abdominal wall reconstruction.

Surgical treatment of large and complicated hiatal hernias with the new resorbable mesh with hydrogel barrier (Phasix™ ST): a preliminary study

Evaluation of the efficacy and safety of the new monofilament fully resorbable mesh with hydrogel barrier (Phasix™ ST), for large and complex hiatal hernia repair. Between December 2017 and December 2020, 60 patients with large or complicated hiatal hernia were treated (40 robotic and 20 laparoscopic procedures). The mesh was placed after primary closure of the hiatal defect, in an onlay fashion around the esophagus, followed by 360^o fundoplication. Follow-up at 3, 6, 12, 18, 24 months from intervention included clinical evaluation and upper GI endoscopy. In cases of recurrence, radiologic survey and manometry were utilized. There were no conversions to open repair or significant postoperative incidents. Over a median follow-up of 21 months (range 3-36), no recurrences or mesh related complications were observed. From our early experience, Phasix™ ST mesh seems to be safe and effective for the reinforcement of crural defects in large and complex hiatal hernia.

Long-Term, Prospective, Multicenter Study of Poly-4-Hydroxybutyrate Mesh (Phasix Mesh) for Hernia Repair in Cohort at Risk for Complication: 60-Month Follow-Up

BACKGROUND

Long-term resorbable mesh represents a promising technology for ventral and incisional hernia repair (VIHR). This study evaluates poly-4-hydroxybutyrate mesh (P4HB; Phasix Mesh) among comorbid patients with CDC class I wounds.

STUDY DESIGN

This prospective, multi-institutional study evaluated P4HB VIHR in comorbid patients with CDC class I wounds. Primary outcomes included hernia recurrence and surgical site infection. Secondary outcomes included pain, device-related adverse events, quality of life, reoperation, procedure time, and length of stay. Evaluations were scheduled at 1, 3, 6, 12, 18, 24, 30, 36, and 60 months. A time-to-event analysis (Kaplan-Meier) was performed for primary outcomes; secondary outcomes were reported as descriptive statistics.

RESULTS

A total of 121 patients (46 male, 75 female) 54.7 ± 12.0 years old with a BMI of 32.2 ± 4.5 kg/m 2 underwent VIHR with P4HB Mesh (mean ± SD). Fifty-four patients (44.6%) completed the 60-month follow-up. Primary outcomes (Kaplan-Meier estimates at 60 months) included recurrence (22.0 ± 4.5%; 95% CI 11.7% to 29.4%) and surgical site infection (10.1 ± 2.8%; 95% CI 3.3 to 14.0). Secondary outcomes included seroma requiring intervention (n = 9), procedure time (167.9 ± 82.5 minutes), length of stay (5.3 ± 5.3 days), reoperation (18 of 121, 14.9%), visual analogue scale-pain (change from baseline -3.16 ± 3.35 cm at 60 months; n = 52), and Carolinas Comfort Total Score (change from baseline -24.3 ± 21.4 at 60 months; n = 52).

CONCLUSIONS

Five-year outcomes after VIHR with P4HB mesh were associated with infrequent complications and durable hernia repair outcomes. This study provides a framework for anticipated long-term hernia repair outcomes when using P4HB mesh.

Establishing Peer Consensus About the Use of Long-Term Biosynthetic Absorbable Mesh for Hernia (Grades 2-3) as the Standard of Care

BACKGROUND

Standard synthetic and biologic meshes, often used in hernia repair, have commonly been used and each have their strengths but associated drawbacks. Long-term biosynthetic absorbable (LTBA) mesh has been developed to combine the strengths of synthetic and biologic meshes without the associated weaknesses. As a newer type of mesh, the supporting evidence base is still growing, and their optimum use has yet to be defined. This consensus was initiated to provide insight into those situations where a LTBA might be considered the Standard of Care in ventral hernia repair grades 2-3 (original classification, 2010) of the Ventral Hernia Working Group.

METHODS

A steering group of expert surgeons identified 35 statements, based around the evidence supporting LTBA, surgical technique, patients type most suitable for LTBA, risk-benefit of LTBA, patient and surgeon considerations, LTBA value. Surgeons involved in hernia repair received an online survey to assess consensus with these statements. Consensus was defined as high if ≥ 70% and very high if ≥ 90% of respondents agreed. Statements that had not achieved consensus agreement were revised and these were then issued for a subsequent round. Finally, 34 statements were included.

RESULTS

Two hundred fifty-five surgeons were involved. Fourteen statements (41%) achieved very high consensus, 24 achieved consensuses (≥ 70-< 90%), whilst one (3%) just failed to achieve consensus with an agreement score of 69%.

CONCLUSIONS

Expert consensus opinion about the use of LTBA for hernia (Grades 2-3) as the Standard of Care was achieved. Based on the consensus scores, the steering group derived eleven keys.

Ventral hernia repair in high-risk patients and contaminated fields using a single mesh: proportional meta-analysis

PURPOSE

The use of mesh is a common practice in ventral hernia repair (VHR). Lack of consensus on which prosthetic material works better in different settings remains. This meta-analysis aims to summarize the available evidence on hernia recurrence and complications after repair with synthetic, biologic, or biosynthetic/bioabsorbable meshes in hernias grade 2-3 of the Ventral Hernia Working Group modified classification.

METHODS

A literature search was conducted in January 2021 using Web of Science (WoS), Scopus, and MEDLINE (via PubMed) databases. Randomized Controlled Trials (RCTs) and observational studies with adult patients undergoing VHR with either synthetic, biologic, or biosynthetic/bioabsorbable mesh were included. Outcomes were hernia recurrence, Surgical Site Occurrence (SSO), Surgical Site Infection (SSI), 30 days re-intervention, and infected mesh removal. Random-effects meta-analyses of pooled proportions were performed. Quality of the studies was assessed, and heterogeneity was explored through sensitivity analyses.

RESULTS

25 articles were eligible for inclusion. Mean age ranged from 47 to 64 years and participants' follow-up ranged from 1 to 36 months. Biosynthetic/bioabsorbable mesh reported a 9% (95% CI 2-19%) rate of hernia recurrence, lower than synthetic and biologic meshes. Biosynthetic/bioabsorbable mesh repair also showed a lower incidence of SSI, with a 14% (95% CI 6-24%) rate, and there was no evidence of infected mesh removal. Rates of seroma were similar for the different materials.

CONCLUSIONS

This meta-analysis did not show meaningful differences among materials. However, the best proportions towards lower recurrence and complication rates after grade 2-3 VHR were after using biosynthetic/slowly absorbable mesh reinforcement. These results should be taken with caution, as head-to-head comparative studies between biosynthetic and synthetic/biologic meshes are lacking. Although, biosynthetic/bioabsorbable materials could be considered an alternative to synthetic and biologic mesh reinforcement in these settings.

Slowly absorbable mesh versus standard care in the management of contaminated midline incisional hernia (COMpACT-BIO): a multicentre randomised controlled phase III trial including a health economic evaluation

INTRODUCTION

Incisional hernia (IH) is the most frequent mid-term and long-term complication after midline laparotomy. The current standard treatment includes repair using a mesh. In a contaminated field, the use of a non-absorbable mesh increases the risk of surgical site infection and the costs. Slowly absorbable meshes are safe in contaminated fields, but no data have been reported regarding their long-term recurrence rate. COMpACT-BIO is a multicentre prospective randomised controlled phase III trial designed to compare the 3-year recurrence rate in patients undergoing contaminated IH repair with either a slowly absorbable mesh or standard care.

METHODS

In patients undergoing midline IH repair in a contaminated surgical field (grade III of the modified Ventral Hernia Working Group classification), the COMpACT-BIO study compares the use of a slowly absorbable mesh with that of conventional care according to standardised surgical procedures (primary closure, non-absorbable synthetic mesh or biologic mesh, at the discretion of the surgeon). Randomisation is done during surgery before closure the fascia with an allocation ratio of 1:1. The choice of the slowly absorbable mesh is left to the criteria of each centre. The primary endpoint is the proportion of patients with scan-confirmed IH recurrence within 3 years after repair.

ETHICS/DISSEMINATION

This trial is conducted in compliance with international standards for research practice and reporting. Written informed consent will be obtained from patients prior to inclusion. All data were identified and anonymised prior to analysis. The protocol has been approved by an Institutional Review Board (2020-A0823-36/SI:20.07.03.66831), and will be conducted in compliance with the CONSORT (Consolidated Standards of Reporting Trials) statement. Results will be submitted for publication in peer-reviewed medical journals and presented to patients and healthcare professionals.

PROTOCOL VERSION

Version 2-13 October 2020.

TRIAL REGISTRATION NUMBER

NCT04597840.

Comparative Effectiveness Analysis of Resorbable Synthetic Onlay and Biologic Intraperitoneal Mesh for Abdominal Wall Reconstruction: A 2-Year Match-Paired Analysis

BACKGROUND

Abdominal wall reconstruction persists as a challenging surgical issue with a multitude of management strategies available. The aim of this study was to examine the efficacy of resorbable synthetic mesh onlay plane against biologic mesh in the intraperitoneal plane.

METHODS

A single-center, two-surgeon, 5-year retrospective review (2014 to 2019) was performed examining subjects who underwent abdominal wall reconstruction in the onlay plane with resorbable synthetic mesh or in the intraperitoneal plane with biologic mesh. A matched paired analysis was conducted. Data examining demographic characteristics, intraoperative variables, postoperative outcomes, and costs were analyzed.

RESULTS

Eighty-eight subjects (44 per group) were identified (median follow-up, 24.5 months). The mean age was 57.7 years, with a mean body mass index of 30.4 kg/m2. The average defect size was 292 ± 237 cm2, with most wounds being clean-contaminated (48.9 percent) and 55 percent having failed prior repair. Resorbable synthetic mesh onlay subjects were significantly less likely (4.5 percent) to experience recurrence compared to biologic intraperitoneal mesh subjects (22.7 percent; p < 0.026). In addition, mesh onlay suffered fewer postoperative surgical-site occurrences (18.2 percent versus 40.9 percent; p < 0.019) and required fewer procedural interventions (11.4 percent versus 36.4 percent; p < 0.011), and was also associated with significantly lower total costs ($16,658 ± $14,930) compared to biologic intraperitoneal mesh ($27,645 ± $16,864; p < 0.001).

CONCLUSIONS

Abdominal wall reconstruction remains an evolving field, with various techniques available for treatment. When faced with hernia repair, resorbable synthetic mesh in the onlay plane may be preferable to biologic mesh placed in the intraperitoneal plane because of lower long-term recurrence rates, surgical-site complications, and costs.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

VERSATILITY OF POLY-4-HYDROXYBUTYRATE (PHASIX™) MESH IN ABDOMINAL WALL SURGERY

BACKGROUND

Poly-4-hydroxybutyrate (P4HB) is a naturally occurring polymer derived from transgenic E. coli bacteria with the longest degradation rate when compared to other available products. This polymer has been manufactured as a biosynthetic mesh to be used as reinforcement when repairing a variety of abdominal wall defects.

OBJECTIVE

We aim to describe our center initial experience with this mesh and discuss the possible indications that may benefit from the use of P4HB mesh.

METHODS

This is a descriptive retrospective study of patients who underwent abdominal wall repair with a P4HB mesh from October 2018 to December 2020 in a single, large volume, academic center.

RESULTS

A total of 51 patients (mean age 54.4 years, range 12-89) underwent abdominal wall reconstruction with a P4HB mesh between October 2018 and December 2020. The mean BMI was 30.5 (range 17.2-50.6). Twenty-three (45%) patients had a prior hernia repair at the site. We grouped patients into six different indications for the use of P4HB mesh in our cohort: clean-contaminated, contaminated or infected field (57%), patient refusal for permanent meshes (14%), those with high risk for post-operative infection (12%), visceral protection of second mesh (10%), recurrence with related chronic pain from mesh (6%), and children (2%). Median follow-up was 105 days (range 8-648). Two patients had hernia recurrence (4%) and 8 (16%) patients developed seroma.

CONCLUSION

P4HB mesh is a safe and a viable alternative for complex hernias and high-risk patients with a low complication rate in the short-term.

Favourable outcomes after Retro-Rectus (Rives-Stoppa) Mesh Repair as Treatment for Non-Complex Ventral Abdominal Wall Hernia, a Systematic Review and Meta-Analysis

OBJECTIVE

To assess prevalence of hernia recurrence, surgical site infection (SSI), seroma, serious complications, and mortality after retro-rectus repair.

SUMMARY BACKGROUND DATA

Ventral abdominal wall hernia is a common problem, tied to increasing frailty and obesity of patients undergoing surgery. For non-complex ventral hernia, retro-rectus (Rives-Stoppa) repair is considered the gold standard treatment. Level-1 evidence confirming this presumed superiority is lacking.

METHODS

Five databases were searched for studies reporting on retro-rectus repair. Single-armed and comparative randomized and non-randomized studies were included. Outcomes were pooled with mixed-effects, inverse variance or random-effects models.

RESULTS

Ninety-three studies representing 12440 patients undergoing retro-rectus repair were included. Pooled hernia recurrence was estimated at 3.2% (95%CI: 2.2-4.2%, n = 11049) after minimally 12 months and 4.1%, (95%CI: 2.9-5.5%, n = 3830) after minimally 24 months. Incidences of SSI and seroma were estimated at respectively 5.2% (95%CI: 4.2-6.4%, n = 4891) and 5.5% (95%CI: 4.4-6.8%, n = 3650). Retro-rectus repair was associated with lower recurrence rates compared to onlay repair (OR: 0.27, 95%CI: 0.15-0.51, p < 0.001) and equal recurrence rates compared to intraperitoneal onlay (IPOM) repair (OR: 0.92, 95%CI: 0.75-1.12, p = 0.400). Retro-rectus repair was associated with more SSI than IPOM repair (OR: 1.8, 95%CI: 1.03-3.14, p = 0.038). Minimally invasive retro-rectus repair displayed low rates of recurrence (1.3%, 95%CI: 0.7-2.3%, n = 849) and SSI (1.5%, 95%CI: 0.8-2.8%, n = 982), albeit based on non-randomized studies.

CONCLUSIONS

Retro-rectus (Rives-Stoppa) repair results in excellent outcomes, superior or similar to other techniques for all outcomes except surgical site infection. The latter rarely occurred, yet less frequently after IPOM repair, which is usually performed by laparoscopy.

Long-term outcome of absorbable synthetic mesh in clean ventral hernia repairs

BACKGROUND

There are many materials available for the reinforcement of complex abdominal wall reconstruction, including permanent synthetic, biologic, and absorbable synthetic meshes. The recurrence rate of complex hernia repairs beyond 5 years has not been reported. We hypothesized that the use of absorbable synthetic mesh in clean wounds would yield favorable long-term outcomes.

STUDY DESIGN

Patients who underwent open complex ventral hernia repair with clean wounds (CDC class 1) using absorbable synthetic mesh (Bio-A, Gore, Flagstaff, AZ) in the retrorectus position were retrospectively reviewed. Chart review and a validated telephone questionnaire to screen for recurrence were utilized to evaluate and document hernia recurrence.

RESULTS

A total of 49 patients were included in this study. Patients were followed for recurrences for up to 105 months, with a mean follow-up time of 62.4 months (5.2 years). The total number of midline hernia recurrence was 7 out of the original 49 patients (14%). The mean and median recurrence time are 37.4 and 38.8 months, respectively. Kaplan-Meier survival analysis estimated hernia recurrence rate as 2%, 4.6%, 7.1%, 12%, 15%, and 18% at 12, 24, 36, 48, 60, and 72 months, respectively.

CONCLUSION

The use of absorbable synthetic mesh in clean wound ventral hernia repair resulted in favorable long-term recurrence rates. The recurrence rate of absorbable synthetic mesh is similar to that of permanent synthetic mesh, which gives a viable option for patients in whom permanent synthetic mesh is not an option.

A Prospective, Single Arm, Multi-Center Study Evaluating the Clinical Outcomes of Ventral Hernias Treated with OviTex® 1S Permanent Reinforced Tissue Matrix: The BRAVO Study 12-Month Analysis

BACKGROUND

Conflicting results from previous studies have led to dissent over whether surgical mesh is safe and effective in ventral hernia repair. A newer class of mesh known as a reinforced tissue matrix, combining a biologic scaffold and minimal polymer reinforcement, offers promise in reducing inflammatory response and increasing abdominal wall support. This study sought to assess the clinical utility of a reinforced tissue matrix (OviTex) in ventral hernia repair 12 months after implantation.

METHODS

This is a prospective, single-arm, multi-center study to evaluate the clinical performance of OviTex^® 1S Permanent (OviTex) in the repair of primary or recurrent ventral hernias (VH) in consecutive patients (ClinicalTrials.gov/NCT03074474). The rate of surgical site occurrences (SSOs) was evaluated 90 days post-surgery as the primary endpoint. Hernia recurrence and the incidence of postoperative events were evaluated between three and 12 months as secondary endpoints. The incidence of other complications and patient-reported outcomes were also recorded.

RESULTS

Ninety-two (92) patients were enrolled in the study, of whom seventy-six (76) reached the 12-month follow-up. All patients were at least 18 years of age with a BMI of <40 kg/m². Hernia defects were <20 × 20 cm, classified as class I-III according to the CDC wound classification system. Of the 76 patients who reached 12-month follow-up, twenty-six (34%) had previous VH repairs and thirteen (17%) had previous surgical infection. Sixty (79%) had factors known to increase the risk of recurrence. Twenty patients (26%) experienced SSOs, with ten (13%) requiring procedural intervention. Two of the 75 patients (2.7%) experienced a recurrence.

CONCLUSIONS

The low rate of hernia recurrence and SSOs requiring intervention illustrates the potential that reinforced tissue matrices, and OviTex 1S, in particular, have to improve outcomes in VH repairs. Follow-up to 24 months is ongoing.

Slowly resorbable biosynthetic mesh: 2-year results in VHWG grade 3 hernia repair

Introduction

Information on the long-term performance of biosynthetic meshes is scarce. This study analyses the performance of biosynthetic mesh (Phasix™) over 24 months.

Methods

A prospective, international European multi-center trial is described. Adult patients with a Ventral Hernia Working Group (VHWG) grade 3 incisional hernia larger than 10 cm², scheduled for elective repair, were included. Biosynthetic mesh was placed in sublay position. Short-term outcomes included 3-month surgical site occurrences (SSO), and long-term outcomes comprised hernia recurrence, reoperation, and quality of life assessments until 24 months.

Results

Eighty-four patients were treated with biosynthetic mesh. Twenty-two patients (26.2%) developed 34 SSOs, of which 32 occurred within 3 months (primary endpoint). Eight patients (11.0%) developed a hernia recurrence. In 13 patients (15.5%), 14 reoperations took place, of which 6 were performed for hernia recurrence (42.9%), 3 for mesh infection (21.4%), and in 7 of which the mesh was explanted (50%). Compared to baseline, quality of life outcomes showed no significant difference after 24 months. Despite theoretical resorption, 10.7% of patients reported presence of mesh sensation in daily life 24 months after surgery.

Conclusion

After 2 years of follow-up, hernia repair with biosynthetic mesh shows manageable SSO rates and favorable recurrence rates in VHWG grade 3 patients. No statistically significant improvement in quality of life or reduction of pain was observed. Few patients report lasting presence of mesh sensation. Results of biosynthetic mesh after longer periods of follow-up on recurrences and remodeling will provide further valuable information to make clear recommendations.

Trial registration

Registered on clinicaltrials.gov (NCT02720042), March 25, 2016.

Laparoscopic Ventral Hernia Repair with Poly-4-Hydroxybutyrate Absorbable Barrier Composite Mesh

Background

Repair of ventral and incisional hernias (VIHR) is a common procedure, newly introduced resorbable mesh biomaterials provide an attractive option to reduce the use of permanent synthetic mesh in hernia surgery and reduce its complications. However, data on the use of slowly resorbable mesh materials remains scarce, this study aims to evaluate the use of poly-4-hydroxybutyrate/absorbable barrier composite mesh (P4HB/ABCM) in laparoscopic repair of VIHR.

Methods

This is a retrospective study of a sequential cohort of patients undergoing laparoscopic VIHR utilizing a P4HB/ABCM mesh. Perioperative characteristics and clinical outcomes were collected.

Results

In total, 26 patients including 10 females and 7 males underwent laparoscopic VIHR using P4HB/ABCM. All surgeries were performed in a single institution by the same surgeon. The average patient age was 52.6, and the mean BMI was 35.5. All patients had a clean wound classification. The average defect size was 136.4 cm². All patients were seen in clinic with a median follow-up of 28 months. We observed 4 wound seromas, and no wound infections or recurrences during the follow-up period.

Conclusion

Results of laparoscopic VIHR with P4HB/ABCM are favorable and encourages further studies on the role of absorbable biosynthetic mesh materials in hernia surgery.

Incisional Hernia Incidence, Repair Techniques, and Outcomes Based on 1600 Consecutive Patients Receiving Abdominally Based Autologous Breast Reconstruction

BACKGROUND

As the number of postmastectomy patients who receive abdominally based autologous breast reconstruction (ABABR) increases, the frequency of unique paramedian incisional hernias (IHs) at the donor site is increasing as well. We assessed incidence, repair techniques, and outcomes to determine the optimal treatment for this morbid condition.

METHODS

A total of 1600 consecutive patients who underwent ABABR at the University of Pennsylvania between January 1, 2009, and August 31, 2016, were retrospectively identified. Preoperative and operative information was collected for these patients. Incisional hernia incidence was determined by flap type and donor site closure technique. Repair techniques and postoperative outcomes for all patients receiving IH repair (IHR) after ABABR at our institution were also determined. Univariate and multivariate analyses were conducted.

RESULTS

The incidence of IH after ABABR in our health system was 3.6% (n = 61). Fifteen additional patients were referred from outside hospitals for a total of 76 patients who received IHR. At the time of IHR, mesh was used in 79% (n = 60) of cases (13 biologic and 47 synthetic), with synthetics having significantly lower recurrent IH incidence (10.6% vs 38.5%, P = 0.017) when compared with biologics. Mesh position did not have any statistically significant effect on outcomes; however, sublay mesh position had zero adverse outcomes.

CONCLUSIONS

Mesh should be used in all cases when possible. Although retrorectus repair with mesh is optimal, this plane is often nonexistent or too scarred in after ABABR. Thus, intraperitoneal underlay mesh with primary fascial closure or primary closure with onlay mesh placement should then be considered.

Evaluation of the histological and biomechanical properties of poly-4-hydroxybutyrate scaffold for pelvic organ prolapse, compared with polypropylene mesh in a rabbit model

INTRODUCTION AND HYPOTHESIS

Poly-4-hydroxybutyrate (P4HB) is a biopolymer produced by Escherichia coli K12 bacteria. P4HB is fully resorbed in vivo by 18-24 months post-implantation. The aim of this study is to evaluate P4HB in the rabbit abdomen and vagina to determine that the biomechanical and histological properties are similar to the standard polypropylene mesh. Our hypothesis is that the histological and biomechanical properties of a fully absorbable graft will be similar to a lightweight polypropylene (PP) mesh when implanted in rabbit vagina and abdomen.

METHODS

Sixteen (n = 16) female New Zealand White (retired breeder) rabbits were equally divided between two time points (3 and 9 months). A total of 17 rabbits were used owing to one death secondary to suspected cardiomyopathy. P4HB scaffold and PP mesh were subcutaneously and peri-vaginally implanted into the rabbit abdomen and vagina respectively. All rabbits had both posterior and anterior vaginal implants, and half of the rabbits had four abdominal implants in addition to the vaginal implants. The abdominal implants were 4.5 cm long × 1.5 cm wide whereas the vaginal implants were 1.5 cm long × 0.5 cm wide. At 3 and 9 months, gross necropsy was performed and samples were obtained, sectioned, stained and evaluated via histological analysis. Specimens were assessed for host inflammatory response, neovascularization, elastin content, and collagen deposition/maturation. Specimens were also biomechanically evaluated via uniaxial tensile test to determine the stiffness, ultimate tensile strength and load at ultimate tensile strength of the device/tissue composite.

RESULTS

No abdominal mesh exposures were noted. A comparable number of asymptomatic partial vaginal exposures were observed at 3 months (P4HB: n = 3; PP: n = 2) and 9 months (P4HB: n = 3; PP: n = 2) respectively. Histological analysis of specimens showed comparable results in the P4HB and PP groups at 3 and 9 months post-implantation. Although no acute inflammation was seen, chronic inflammation was demonstrated in all specimens. Elastic fibers were present in the 3-month vaginal PP and P4HB specimens, but were not seen again. There was an increase in type I/III collagen noted over time. Biomechanical evaluation of the vaginal mesh tissue complex showed ultimate tensile strength was not significantly different between P4HB and PP groups at 3 (P = 0.625) and 9 months (P = 0.250) respectively.

CONCLUSIONS

P4HB scaffold may represent a fully absorbable alternative to permanent mesh for pelvic organ prolapse (POP) repair.

Outcomes of biosynthetic absorbable mesh use in high risk CDC Class I ventral hernia repair: a single surgeon series

PURPOSE

Biosynthetic absorbable meshes have emerged as suitable alternatives to permanent synthetic and biologic meshes in complex ventral hernia repair in contaminated wounds. Evidence regarding the use of these products in clean wounds is currently scant. This paper presents a large single surgeon series using GORE^®BIO-A^® (W.L. Gore & Associates, Newark, DE) (Bio-A) tissue reinforcement in high risk patients with predominantly CDC Class I wounds.

METHODS

Retrospective review of a prospectively maintained database of consecutive patients who underwent open ventral hernia repair with biosynthetic absorbable mesh was conducted. Ventral Hernia Working Group (VHWG) classification based on patient demographics and Centers for Disease Control (CDC) wound type were collected prospectively. All patients were followed up for a minimum of 12 months post-operatively.

RESULTS

155 patients were included with a mean post-operative follow up of 29 months (range 12-62 months). Mean age was 61.8 years with an average BMI of 33.5 kg/m². 147 patients (94.9%) were classified as VHWG 2 or 3 based on comorbidities or surgical field contamination. 69% (n = 107) of wounds were designated CDC Class I. Mean hernia size was 119.7cm² with recurrent defects comprising 32.3% (n = 50). Retrorectus mesh repair was achieved in 84.5% of patients (n  = 131). Post-operative wound events occurred in 19.3%. No mesh was explanted. Hernia recurrence rate was 9.0% with a mean time to recurrence of 14 months. There was no significant difference in recurrence rates between clean and contaminated wounds.

CONCLUSION

This study supports the use of Bio-A in high risk ventral hernias, demonstrating a safe and durable repair across all wound classes. Ongoing follow-up continues to monitor for late complications and recurrence.

Outcomes of mid-term and long-term degradable biosynthetic meshes in single-stage open complex abdominal wall reconstruction

OBJECTIVE

To assess clinical outcomes in patients that underwent open single-stage complex abdominal wall reconstruction (CAWR) with biosynthetic mesh.

METHODS

Retrospective observational study of two prospectively registered series of consecutive patients undergoing CAWR with either long-term degradable (LTD) Phasix^™ or mid-term degradable (MTD) BIO-A^® biosynthetic mesh in a single institution between June 2016 and December 2019.

RESULTS

From 169 patients with CAWR, 70 consecutive patients were identified who underwent CAWR with either LTD or MTD biosynthetic mesh. More than 85% of patients had an incisional hernia that could be classified as moderately complex to major complex due to a previous wound infection (67%), one or more complicating comorbidities (87.1%), one or more complicating hernia characteristics (75.7%) or contaminated or dirty defects (37.1%). Concomitant component separation was performed in 43 of 70 patients (61.4%). Overall surgical site infection (SSI) rate in these CAWR patients was 45.7%. Seventeen of 70 patients (24.3%) had computed tomography (CT) - and culture-confirmed SSI in direct contact of mesh, suspicious of mesh infection. Mesh removal for persistent local infection occurred in 10% (7 of 70) after a median of 229 days since surgery. Salvage rate of mesh after direct contact with infection was 58.8%. All removed meshes were in the LTD group. Seven patients (10%) had a recurrence; four patients in the LTD group (10%) had a recurrence at a median follow-up of 35 months and three patients in the MTD group (10%) at a median follow-up of 11 months. Three of the seven recurrences occurred in patients with SSI in persistent and direct contact with mesh.

CONCLUSIONS

Comorbid patients undergoing open complex abdominal wall reconstruction are at high risk of postoperative wound complications regardless of which type of biosynthetic mesh is used. When in persistent and direct contact with infection, long-term biodegradable biosynthetic meshes may need to be removed, whereas mid-term biodegradable biosynthetic meshes can be salvaged.

Polymer Hernia Repair Materials: Adapting to Patient Needs and Surgical Techniques

Biomaterials and their applications are perhaps among the most dynamic areas of research within the field of biomedicine. Any advance in this topic translates to an improved quality of life for recipient patients. One application of a biomaterial is the repair of an abdominal wall defect whether congenital or acquired. In the great majority of cases requiring surgery, the defect takes the form of a hernia. Over the past few years, biomaterials designed with this purpose in mind have been gradually evolving in parallel with new developments in the different surgical techniques. In consequence, the classic polymer prosthetic materials have been the starting point for structural modifications or new prototypes that have always strived to accommodate patients’ needs. This evolving process has pursued both improvements in the wound repair process depending on the implant interface in the host and in the material’s mechanical properties at the repair site. This last factor is important considering that this site—the abdominal wall—is a dynamic structure subjected to considerable mechanical demands. This review aims to provide a narrative overview of the different biomaterials that have been gradually introduced over the years, along with their modifications as new surgical techniques have unfolded.

Observational Cohort Study on the Use of a Slowly Fully Resorbable Synthetic Mesh (Phasix™) in the Treatment of Complex Abdominal Wall Pathology with Different Grades of Contamination

PURPOSE

Abdominal wall hernia repair in contaminated cases remains a therapeutic challenge due to the high risk of post-operative surgical site occurrences (SSO). Slowly resorbable synthetic (biosynthetic) meshes have recently been introduced and may offer unique advantages when challenged with bacterial colonization during abdominal wall reconstruction.

METHODS

A multicenter single-arm retrospective observational cohort study examined all consecutive patients in whom a poly-4-hydroxybutyrate mesh (Phasix™ or Phasix™ ST; Becton Dickinson, Franklin Lakes, NJ, USA) was used for the repair of an inguinal or ventral/incisional hernia, or to replace an infected synthetic mesh. Patient records were analyzed according to the level of contamination, using the classification score of the Centers for Disease Control and Prevention (CDC). The primary objective was to evaluate short-term postoperative morbidity by assessing SSOs and the need for reoperation or even mesh excision.

RESULTS

A total of 47 patients were included. The median age was 68 years (30-87), the male/female ratio was 26/21, and the median BMI was 26.5 kg/m2 (16.4-46.8). There were 17 clean cases, 17 clean-contaminated, 6 contaminated and 7 dirty. Median follow-up time was 48 days. An SSO was seen in 4 clean (23.5%), 7 clean-contaminated (41.2%), 2 contaminated (33.3%) and 5 dirty cases (71.4%). A surgical site occurrence requiring procedural intervention (SSOPI) was seen in 2 clean (11.8%), 3 clean-contaminated (17.6%), 1 contaminated (16.7%) and 2 dirty cases (28.6%). Hernia recurrence was seen in 1 clean (5.9%), 2 clean-contaminated (11.8%) and 3 dirty cases (42.9%). Mesh excision had to be performed in only one case in the contaminated group.

CONCLUSION

The Phasix™ mesh shows promising short-term results when used in contaminated hernia-related surgery. Even in contaminated or dirty conditions, with or without infection of the mesh, resection of the mesh only had to be performed once and patients could be managed either conservatively or by relatively minor reoperations. However, further research is needed to fully evaluate the safety and efficacy of these meshes.

Robust Electrospun Nanofibers from Chemosynthetic Poly(4-hydroxybutyrate) as Artificial Dural Substitute

Bioresorbable poly(4-hydroxybutyrate) (P4HB) may fulfill the specific requirements that are necessary for a dural substitute, including its high elasticity, long-term strength retention properties, and the biocompatibility without significant accumulation of acidic degradation products. However, commercial P4HB can only be produced by the bacterial fermentation, which limits its applications in the cerebrospinal system due to higher endotoxin restriction. Meanwhile, P4HB can be prepared via the ring-opening polymerization of γ-butyrolactone. In this contribution, high molecular weight P4HB from chemosynthesis is electrospun into fibrous membrane, showing good mechanical properties that match the natural dura mater. Such P4HB membrane induces fast cellular migration, adhesion, and proliferation of fibroblasts in vitro. Subcutaneous implantation in rats demonstrates excellent biocompatibility of the P4HB membrane with proper biodegradation behaviors. After implantation in the rabbit dural defect model as an onlay graft, the P4HB membranes prevent cerebrospinal fluid leakage and regenerate dura tissue without detecting any local or systematic infections or foreign body responses. Thus, the electrospun P4HB membranes may be particularly useful as artificial dural substitutes to induce wound closure and tissue regeneration, which will be of great benefit to neurosurgery in the future.

An evaluation of clinical and quality of life outcomes after ventral hernia repair with poly-4-hydroxybutyrate mesh

PURPOSE

Despite continued efforts, recurrence after ventral hernia repair (VHR) remains a common problem. Biosynthetic Phasix^™ (Poly-4-Hydroxybutyrate, P4HB) mesh combines the durability of synthetic mesh with the bio-resistance of biologics. P4HB has shown promising early outcomes, but long-term data are lacking. We examine patients following VHR with P4HB with at least 3 years of follow-up to assess clinical and patient reported outcomes (PROs).

METHODS

Adult patients (≥ 18 years old) undergoing VHR with P4HB mesh between 10/2015 and 01/2018 by a single surgeon were retrospectively identified. Patients with < 36 months of follow-up were excluded unless they had a documented recurrence. Clinical outcomes and quality of life using the Hernia-Related Quality of Life Survey (HerQLes) were assessed.

RESULTS

Seventy-one patients were included with a median age and body mass index of 61.2 and 31 kg/m², respectively. Mesh was placed in the retromuscular (79%) and onlay (21%) planes with 1/3 of patients having hernias repaired in contaminated fields. There were no mesh infections, enterocutaneous fistulas, or mesh explantations. Nine patients (12.7%) developed recurrence at a median follow-up of 43.1 months [38.2-49.1]. Mesh plane, fixation technique, and Ventral Hernia Working Group were not associated with recurrence. Significant improvement in disease-specific PROs was observed and maintained at 3-year follow-up.

CONCLUSION

Longitudinal clinical and quality of life outcomes after clean and contaminated VHR with P4HB are limited. Here, we conclude that P4HB is an effective and versatile mesh option for use in abdominal wall reinforcement.

Onlay Poly-4-Hydroxybutyrate (P4HB) Mesh for Complex Hernia: Early Clinical and Patient Reported Outcomes

BACKGROUND

While mesh re-enforcement and advanced surgical techniques are cornerstones of complex ventral hernia repair (CVHR), the risk of complications and recurrence is common. We aim to evaluate the efficacy, safety, and patient reported outcomes (PROs) of patients undergoing CVHR with onlay Poly-4-hydroxybutyrate (P4HB).

METHODS

Adult (>18 y old) patients undergoing VHR with P4HB (Phasix) in the onlay plane by a single surgeon from 01/2015 to 05/2020 were reviewed. VHR was considered complex if patients had significant co-morbidities, large abdominal wall defects, a history of extensive abdominal surgery, and/or concurrent intra-abdominal pathology. A composite of postoperative outcomes including surgical site occurrences (SSO), surgical site infection (SSI), and surgical site occurrences requiring procedural intervention (SSOpi), as well as PROs as defined by the Abdominal Hernia-Q (AHQ), were analyzed.

RESULTS

A total of 51 patients were included with average age and body mass index of 56.4 and 29.9 kg/m². Median follow up was 20 mo with a hernia recurrence rate of 5.9% (n = 3). 21 patients had an SSO (41.2%), 8 had an SSI (15.7%), and 6 had an SSOpi (11.8%). There was an association with Ventral Hernia Working Group ≥ 2 and development of SSO. There was a significant improvement in overall PROs (P < 0.0001) with no difference in those patients with and without complications (P > 0.05).

CONCLUSION

For hernia patients with large defects and complex intra-abdominal pathology, a safe and effective repair is difficult. The use of onlay P4HB was associated with acceptable postoperative outcomes and recurrence rate.

Long-Term Outcomes in Complex Abdominal Wall Reconstruction Repaired With Absorbable Biologic Polymer Scaffold (Poly-4-Hydroxybutyrate)

Introduction

After promising early outcomes in the use of absorbable biologic mesh for complex abdominal wall reconstruction, significant criticism has been raised over the longevity of these repairs after its 2-year resorption profile.

Methods

This is the long-term (5-year) follow-up analysis of our initial experience with the absorbable polymer scaffold poly-4-hydroxybutyrate (P4HB) mesh compared with a consecutive contiguous group treated with porcine cadaveric mesh for complex abdominal wall reconstructions. Our clinical analysis was performed using Stata 14.2 and Excel 16.16.23.

Results

After a 5-year follow-up period, the P4HB group (n = 31) experienced lower rates of reherniation (12.9% vs 38.1%; P = 0.017) compared with the porcine cadaveric mesh group (n = 42). The median interval in months to recurrent herniation was similar between groups (24.3 vs 20.8; P = 0.700). Multivariate logistic regression analysis on long-term outcomes identified smoking (P = 0.004), African American race (P = 0.004), and the use of cadaveric grafts (P = 0.003) as risks for complication while smoking (P = 0.034) and the use of cadaveric grafts (P = 0.014) were identified as risks for recurrence. The long-term cost analysis showed that P4HB had a $10,595 per case costs savings over porcine cadaveric mesh.

Conclusions

Our study identified the superior outcomes in clinical performance and a value-based benefit of absorbable biologic P4HB scaffold persisted after the 2-year resorption timeframe. Data analysis also confirmed the use of porcine cadaveric grafts independently contributed to the incidence of complications and recurrences.

Transcriptome-targeted analysis of human peripheral blood-derived macrophages when cultured on biomaterial meshes

Surgical meshes are commonly used to repair defects and support soft tissues. Macrophages (Mφs) are critical cells in the wound healing process and are involved in the host response upon foreign biomaterials. There are various commercially available permanent and absorbable meshes used by surgeons for surgical interventions. Polypropylene (PP) meshes represent a permanent biomaterial that can elicit both inflammatory and anti-inflammatory responses. In contrast, poly-4-hydroxybutyrate (P4HB) based meshes are absorbable and linked to positive clinical outcomes but have a poorly characterized immune response. This study evaluated the in vitro targeted transcriptomic response of human Mφs seeded for 48 h on PP and P4HB surgical meshes. The in vitro measured response from human Mφs cultured on P4HB exhibited inflammatory and anti-inflammatory gene expression profiles typically associated with wound healing, which aligns with in vivo animal studies from literature. The work herein provides in vitro evidence for the early transcriptomic targeted signature of human Mφs upon two commonly used surgical meshes. The findings suggest a transition from an inflammatory to a non-inflammatory phenotype by P4HB as well as an upregulation of genes annotated under the pathogen response pathway.

Successful conservative treatment of a poly-4-hydroxybutyrate mesh infection: A case report

Introduction and importance

An infection of an abdominal wall prosthesis can be a real disaster for the patient. A conservative treatment might be an option if biological or slowly resorbable synthetic meshes were used. However, adequate research of their use in contaminated and dirty wounds lacks.

Case presentation

Herein we report the case of a 69-year-old patient with a heavily infected poly-4-hydroxybutyrate mesh that was successfully treated conservatively.

Clinical discussion

Despite promising results of poly-4-hydroxybutyrate meshes, their use remains controversial and studies in contaminated wounds are scarce.

Conclusion

Our case report shows the potential benefits of a poly-4-hydroxybutyrate mesh in a very high-risk patient with active infection.

Bioabsorbable mesh use in midline abdominal wall prophylaxis and repair achieving fascial closure: a cross-sectional review of stage of innovation

BACKGROUND

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

METHODS

A systematic review of published and ongoing studies was performed until 31st December 2019. Inclusion criteria were studies where bioabsorbable mesh was used to support fascial closure either prophylactically after midline laparotomy or for repair of incisional hernia with midline incision. Exclusion criteria were: (1) study design was a systematic review, meta-analysis, letter, review, comment, or conference abstract; (2) included less than p patients; (3) only evaluated biological, synthetic or composite meshes. The primary outcome measure was the IDEAL framework stage of innovation. The key secondary outcome measure was the risk of bias in non-randomised studies of interventions (ROBINS-I) criteria for study quality.

RESULTS

Twelve studies including 1287 patients were included. Three studies considered mesh prophylaxis and nine studies considered hernia repair. There were only two published studies of IDEAL 2B. The remainder was IDEAL 2A studies. The quality of the evidence was categorised as having a risk of bias of a moderate, serious or critical level in nine of the twelve included studies using the ROBINS-I tool.

CONCLUSION

The evidence base for bioabsorbable mesh is limited. Better reporting and quality control of surgical techniques are needed. Although new trial results over the next decade will improve the evidence base, more trials in emergency and contaminated settings are required to establish the limits of indication.

What results can be expected one year after complex incisional hernia repair with biosynthetic mesh?

BACKGROUND

Incisional hernia is a frequent complication after midline laparotomy. The current standard repair includes the use of a synthetic mesh to prevent recurrence. However, the use of a synthetic mesh in a contaminated field carries a higher risk of mesh infection. In this setting biologic and biosynthetic meshes can be used as they resist to infection, but these are absorbable meshes. This raises the question of the risk of recurrence as the mesh disappears. Phasix® is a biosynthetic mesh getting absorbed in 12-18 months. The aim of this study was to assess the 1-year recurrence rate after abdominal-wall repair with a Phasix® mesh.

METHODS

All patients undergoing ventral hernia repair between 2016 and 2018 at the University Hospital of Dijon using a Phasix® mesh were prospectively included in a database. They were all followed-up with a physical exam and a routine CT scan at one year. All postoperative complications were recorded.

RESULTS

Twenty-nine patients were included in the study (55.2% women), with a mean BMI of 30,25 kg/m². Nineteen meshes were sublay and 10 intraperitoneal. Complications at 1 month were mainly mild: Clavien-Dindo I and II (61.1%). No mesh was explanted. There was no chronic infection. The mean length of stay was 11.5 days. The 1-year recurrence rate was 10.3%.

CONCLUSION

Patients having undergone complex ventral hernia repair with a Phasix® mesh have a 1-year recurrence rate of 10.3%. No severe surgical site occurrence was detected. A longer follow-up in a larger number of patients could confirm the place of this mesh in abdominal-wall repair.

Prospective, multicenter study of P4HB (Phasix™) mesh for hernia repair in cohort at risk for complications: 3-Year follow-up

BACKGROUND

This study represents a prospective, multicenter, open-label study to assess the safety, performance, and outcomes of poly-4-hydroxybutyrate (P4HB, Phasix™) mesh for primary ventral, primary incisional, or multiply-recurrent hernia in subjects at risk for complications. This study reports 3-year clinical outcomes.

MATERIALS AND METHODS

P4HB mesh was implanted in 121 patients via retrorectus or onlay technique. Physical exam and/or quality of life surveys were completed at 1, 3, 6,12, 18, 24, and 36 months, with 5-year (60-month) follow-up ongoing.

RESULTS

A total of n = 121 patients were implanted with P4HB mesh (n = 75 (62%) female) with a mean age of 54.7 ± 12.0 years and mean BMI of 32.2 ± 4.5 kg/m2 (±standard deviation). Comorbidities included: obesity (78.5%), active smokers (23.1%), COPD (28.1%), diabetes mellitus (33.1%), immunosuppression (8.3%), coronary artery disease (21.5%), chronic corticosteroid use (5.0%), hypo-albuminemia (2.5%), advanced age (5.0%), and renal insufficiency (0.8%). Hernias were repaired via retrorectus (n = 45, 37.2% with myofascial release (MR) or n = 43, 35.5% without MR), onlay (n = 8, 6.6% with MR or n = 24, 19.8% without MR), or not reported (n = 1, 0.8%). 82 patients (67.8%) completed 36-month follow-up. 17 patients (17.9% ± 0.4%) experienced hernia recurrence at 3 years, with n = 9 in the retrorectus group and n = 8 in the onlay group. SSI (n = 11) occurred in 9.3% ± 0.03% of patients.

CONCLUSIONS

Long-term outcomes following ventral hernia repair with P4HB mesh demonstrate low recurrence rates at 3-year (36-month) postoperative time frame with no patients developing late mesh complications or requiring mesh removal. 5-year (60-month) follow-up is ongoing.

Outcomes of Poly-4-hydroxybutyrate Mesh in Ventral Hernia Repair: A Systematic Review and Pooled Analysis

Within the past decade, poly-4-hydroxybutyrate (P4HB) biosynthetic mesh has been introduced as a potential alternative to traditional biologic and synthetic mesh in ventral hernia repair (VHR). The aim of this study was to systematically assess clinical outcomes with the P4HB in VHR.

Methods

A literature search identified all articles published in 2000 involving the use of P4HB in VHR. Descriptive statistics were used to synthesize collective data points, including postoperative outcomes. A pooled analysis of postoperative outcomes was performed using chi-square test and Fisher exact test.

Results

Across 7 studies, the P4HB was used in 453 patients. The mean rate of surgical site infection (SSI) was 6.8% (31/453), reoperation 10.7% (30/281), and recurrence 9.1% (41/453). At an average follow-up of 26.8 months, the incidence of recurrence was 10.4% (28/270). Onlay was significantly associated with increased recurrence (14.2% versus 4.4%, P = 0.001). Among sublay placements, there was no difference in recurrence in clean (Center for Disease Control [CDC] 1) or contaminated (CDC >1) wounds (2.7% versus 6.1%, P = 0.585), but contaminated wounds were associated with increased SSI (2.7% versus 15.2%, P = 0.028). Ventral Hernia Working Group grade 2 and 3 did not have different incidences of recurrence (8.0% versus 5.1%, P = 0.526) nor SSI (5.1% versus 14.6%, P = 0.265).

Conclusions

Overall, clinical outcomes of the P4HB mesh in VHR are acceptable. The P4HB mesh serves as a reliable alternative to traditional synthetic and biologic mesh across a range of defect characteristics and patient health conditions. Further research is needed to better understand the conditions in which it may provide a clinical benefit over traditional mesh types.

In Vitro Bacterial Adhesion and Biofilm Formation on Fully Absorbable Poly-4-hydroxybutyrate and Nonabsorbable Polypropylene Pelvic Floor Implants

Knitted polypropylene (PP) implants for the correction of pelvic organ prolapse have been associated with complications such as vaginal exposure, infection, and pain. Since certain complications may be linked to bacterial contamination and persistent inflammation, there is a rationale to develop a biocompatible implant that is less prone to bacterial adhesion and biofilm formation. Delayed absorbable materials could meet these requirements and poly-4-hydroxybutyrate (P4HB) might be such a new material for future pelvic floor implants. We studied in vitro bacterial adhesion and biofilm formation on P4HB in comparison to PP. We investigated the influence of both polymers using flat films and compared P4HB and PP implants with different knitting designs. P4HB flat films were demonstrated to be hydrophilic with significantly less Staphylococcus aureus and Escherichia coli cultured from P4HB films than from hydrophobic PP films after 24 h of incubation. On the implants, a higher number of E. coli were cultured after 1 h of incubation from the knitted P4HB implant with the highest density and smallest pore size, compared to other P4HB and PP implants. No differences were observed between the implants for E. coli at later time points or for S. aureus incubation. These results show that in flat films, the polymer influences biofilm formation, demonstrated by a reduced biofilm formation on P4HB compared with PP flat films. In addition, the knitting design may affect bacterial adhesion. Despite certain design and material characteristics that give the knitted P4HB implants a higher surface area, this did not result in more bacterial adhesion and biofilm formation overall. Collectively, these results warrant further (pre)clinical investigations of P4HB pelvic floor implants.

In-vivo evaluation of a reinforced ovine biologic: a comparative study to available hernia mesh repair materials

PURPOSE

Two innovative reinforced biologic materials were studied in a non-human primate hernia repair model. The test articles, which combine layers of ovine decellularized extracellular matrix with minimal amounts of synthetic polymer, were evaluated for their biologic performance as measured by inflammatory response, healing kinetics, integration, and remodeling into functional host tissue. For comparison, seven clinically used biologic and synthetic meshes were also studied.

METHODS

Animals were implanted with test articles in surgically created full-thickness midline abdominal wall defects, and evaluated macroscopically and histologically at 4, 12, and 24 weeks.

RESULTS

Macroscopically, biologics resorbed and remodeled into naturally appearing tissue; the reinforced biologics appeared similar, but remodeled earlier and were less prone to stretch. Synthetics developed a layer of reactive tissue above and separate from the contracted mesh structure. At early time points, the collagen networks of biologics and reinforced biologics were infiltrated by host cells primarily as a peripheral layer on the biologics. As early as 12 weeks, the collagen networks associated with the reinforced biologics remodeled into organized host collagen. By 24 weeks, both reinforced biologics and biologics had low levels of inflammation. In contrast, a foreign body response persisted at 24 weeks with the synthetics, which had developed less organized collagen, separate in space from the actual mesh.

CONCLUSIONS

The current study shows a favorable response to reinforced biologics, which were associated with an initial inflammatory response, resolving by later time points, followed by active remodeling, and the formation of new morphologically functional collagen.

CircRNA0001859, a new diagnostic and prognostic biomarkers for COPD and AECOPD

Background

Dysregulation of circRNAs has been reported to be functionally associated with chronic obstructive pulmonary disease (COPD). The present investigation elucidated the potential role of CircRNA0001859 in regulating chronic obstructive pulmonary disease acute (COPD) and Acute Exacerbation of COPD (AECOPD).

Methods

Mice model of COPD was established to screen and verify the dysregulated expression of CircRNA0001859. Fluorescence in situ hybridization (FISH) and quantitative real-time PCR (qRT-PCR) were carried out to detect the expression of CircRNA0001859. 38 stable COPD patients, 24 AECOPD patients, 57 COPD with lung cancer patients and 28 healthy person with age and sex matched to total patients were used for the present investigation.

Results

circRNA0001859 was downregulated in the lung tissue of mice after the three kinds of treatments (Cigarette smoke (CS)/NK alone or CS + NNK) for inducing COPD. FISH assay verified the downregulation of circRNA0001859 both in the mice lung and human bronchial epithelial cell of COPD model. Furthermore,, the level of circRNA0001859 was also downregulated in the peripheral blood of COPD and lung cancer patients. CircRNA0001859 might act as a diagnostic and prognostic biomarker for the treatment of in COPD and AECOPD with Are under the receiver operating characteristic curve (ROC curve) (AUC) of 0.7433 and 0.8717, respectively.

Conclusion

We explored a novel circRNA0001859, which might act as a potential therapeutic biomarker for the treatment of COPD and AECOPD.

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.

Role of 4-hydroxybutyrate in increased resistance to surgical site infections associated with surgical meshes

An increased resistance to surgical site infections has been associated with surgical meshes composed of naturally occurring materials, including poly-4-hydroxybutrate (4HB). 4HB is a naturally occurring short-chain fatty acid that has been shown to promote endogenous expression of the Cramp gene coding for the antimicrobial peptide (AMP) cathelicidin LL-37 in murine bone marrow-derived macrophages. The molecular pathways involved in the 4HB-induced cathelicidin LL-37 expression have not yet been identified. The present study showed that transcriptional activation of the Cramp gene by 4HB is independent of inhibition of histone deacetylase (HDAC) activity, and that upregulation of Cramp is modulated by the G-protein coupled receptor GPR109A. Furthermore, an intracellular signaling cascade that promotes the activation of the MAP kinases, p38 and JNK, and a subsequent NF-κB phosphorylation downstream from p38 is essential for the AMP transcriptional response in 4HB-stimulated macrophages. The findings provide a solid scientific basis and rationale for the decreased incidence of surgical site infections with the use of this type of surgical meshes. Further clinical significance is found in the fact that the 4HB activated molecular pathway includes common targets of frequently used nonsteroidal anti-inflammatory drugs (NSAIDs) and other FDA approved drugs recognizing G-protein coupled receptors.

Biosynthetic Resorbable Prosthesis is Useful in Single-Stage Management of Chronic Mesh Infection After Abdominal Wall Hernia Repair

BACKGROUND

The goal of this article was to report the results about the efficacy of treatment of chronic mesh infection (CMI) after abdominal wall hernia repair (AWHR) in one-stage management, with complete mesh explantation of infected prosthesis and simultaneous reinforcement with a biosynthetic poly-4-hydroxybutyrate absorbable (P4HB) mesh.

METHODS

This is a retrospective analysis of all patients that needed mesh removal for CMI between September 2016 and January 2019 at a tertiary center. Epidemiological data, hernia characteristics, surgical, and postoperative variables (Clavien-Dindo classification) of these patients were analyzed.

RESULTS

Of the 32 patients who required mesh explantation, 30 received one-stage management of CMI. In 60% of the patients, abdominal wall reconstruction was necessary after the infected mesh removal: 8 cases (26.6%) were treated with Rives-Stoppa repair, 4 (13.3%) with a fascial plication, 1 (3.3%) with anterior component separation, and 1 (3.3%) with transversus abdominis release to repair hernia defects. Three Lichtenstein (10%) and 1 Nyhus repairs (3.3%) were performed in patients with groin hernias. The most frequent postoperative complications were surgical site occurrences: seroma in 5 (20%) patients, hematoma in 2 (6.6%) patients, and wound infection in 1 (3.3%) patient. During the mean follow-up of 34.5 months (range 23-46 months), the overall recurrence rate was 3.3%. Persistent, recurrent, or new CMIs were not observed.

CONCLUSIONS

In our experience, single-stage management of CMI with complete removal of infected prosthesis and replacement with a P4HB mesh is feasible with acceptable results in terms of mesh reinfection and hernia recurrence.

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.

The use of a novel synthetic resorbable scaffold (TIGR Matrix®) in a clinical quality improvement (CQI) effort for abdominal wall reconstruction (AWR)

PURPOSE

The use of hernia mesh is a common practice in abdominal wall reconstruction (AWR) operations. The high cost of biologic mesh has raised questions about the value of its use in AWR. Resorbable synthetic mesh may have the potential benefits of biologic mesh, minimizing the need for removal when infected, at a lower cost.

METHODS

A hernia program has implemented the principles of clinical quality improvement (CQI) to improve patient outcomes. One process improvement attempt was implemented using a newly available resorbable synthetic scaffold. Long-term follow-up was obtained as a part of the CQI process.

RESULTS

A total of 91 patients undergoing AWR were included between 8/11 and 9/15 (49 months). There were 58 female (64%) and 33 male (36%) patients. The average age was 57.2 years (28-80). The average BMI was 34.0 (17.6-53.4). There were 52 patients (57%) with recurrent hernias. Mean hernia defect size was 306.6 cm² (24-720) and mean mesh size was 471.7 cm² (112-600). Outcomes included a mean length of stay of 7.5 days (0-49), a recurrence rate of 12% (11/91) and a wound complication rate of 27% (25/91). The recurrence rate decreased to 4.5% (3/66) after several improvements, including adopting a transversus abdominus release (TAR) approach, were implemented. There were no mesh-related complications and no mesh removal (partial or total) was required. The mean follow-up length was 42.4 months (0-102).

CONCLUSION

In this group of patients, an attempt at process improvement was implemented using a resorbable synthetic scaffold for AWR. With no mesh-related complications and no mesh removals required, there was an improvement in value due to the decrease in mesh cost and improved outcomes over time. Long-term follow-up demonstrated the durability of the repair.

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.

Poly-4-hydroxybutyrate (Phasix™) mesh onlay in complex abdominal wall repair

BACKGROUND

Poly-4-hydroxybutyric acid (P4HB, Phasix™) is a biosynthetic polymer that degrades by hydrolysis that can be woven into a mesh for use in soft tissue reinforcement. Herein, we describe our initial experience performing complex abdominal wall repair (CAWR) utilizing component separation and P4HB mesh as onlay reinforcement.

METHODS

All patients undergoing CAWR between June 2014 and May 2017 were followed prospectively for postoperative outcomes. Only those patients who underwent components separation with primary repair of the fascial edges followed by onlay of P4HB mesh were included in this study.

RESULTS

105 patients (52 male, 53 female; mean age 59.2 years, range 22-84) met inclusion criteria. Mean BMI was 29.1 (range 16-48); 52% patients had prior attempted hernia repair, most with multiple medical comorbidities (71% of patients with ASA 3 or greater). 30% of cases were not clean at the time of repair (CDC class 2 or greater). Median follow-up was 36 months (range 9-63). Eighteen patients (17%) developed a hernia recurrence ranging from 2 to 36 months postoperatively. Five (5%) patients developed a localized superficial infection treated with antibiotics, three (2.8%) required re-operation for non-healing wounds, and six (6%) patients developed seroma.

CONCLUSIONS

These data demonstrate a relatively low rate of hernia recurrence, seroma, and other common complications of CAWR in a highly morbid patient population. Importantly, the rate of mesh infection was low and no patients required complete mesh removal, even when placed into a contaminated or infected surgical field.

Comments to "PRevention of INCisional hernia after liver transplantation (PRINC trial): study protocol for a randomized controlled trial."

Prophylactic augmentation of the wound with mesh proposed by Kniepeiss et al is the world's first attempt to significantly reduce the risk of postoperative hernia in liver transplantation. Similar technique have been described 17 years ago in bariatric patients and confirmed by many studies in various clinical settings. The results of mesh hernia repair in patients on immunosuppressive therapy are not inferior from the data obtained from non- transplant surgery registers.To reduce the risk of using the mesh in patients scheduled for liver transplantation authors chose absorbable mesh, that maintains the mechanical strength of the wound for up to 18 months. Half of the incisional hernias have been diagnoses more than 3 years from the original procedure.For prevention of incisional hernias, there is no evidence to support the use of biologic/biosynthetic meshes.