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

Remodeling and Regenerative Properties of Fully Absorbable Meshes for Abdominal Wall Defect Repair: A Systematic Review and Meta-Analysis of Animal Studies

Fully absorbable meshes can repair abdominal wall defects and effectively reduce the incidence of complications, but different types of fully absorbable meshes have different remodeling and regeneration effects. In order to investigate and compare the effects of different fully absorbable meshes on remodeling and regeneration in animals and reduce the biological risk of clinical translation, SYRCLE was adopted to evaluate the methodological quality of the included studies, and GRADE and ConQual were used to evaluate the quality of evidence. According to the inclusion and exclusion criteria, a total of 22 studies related to fully absorbable meshes were included in this systematic review. These results showed that fiber-based synthetic materials and fiber-based natural materials exhibited better restorative and regenerative effects indicated by infiltration and neovascularization, when compared with a porcine acellular dermal matrix. In addition, the human acellular dermal matrix was found to have a similar regenerative effect on the host extracellular matrix and scaffold degradation compared to the porcine acellular dermal matrix, porcine intestinal submucosa, and fiber-based natural materials, but it offered higher tensile strength than the other three. The quality of the evidence in this field was found to be poor. The reasons for downgrading were analyzed, and recommendations for future research included more rigor in study design, more transparency in result reporting, more standardization of animal models and follow-up time for better evaluation of the remodeling and regenerative performance of abdominal wall hernia repair meshes, and less biological risk in clinical translation.

An established abdominal wall multidisciplinary team improves patient care and aids surgical decision making with complex ventral hernia patients

INTRODUCTION

Abdominal wall reconstruction (AWR) is an emerging subspecialty within general surgery. The practice of multidisciplinary team (MDT) meetings to aid decision making and improve patient care has been demonstrated, with widespread acceptance. This study presents our initial experience of over 150 cases of complex hernia patients discussed in a newly established MDT setting.

METHODS

From February 2020 to July 2022 (30-month period), abdominal wall MDTs were held bimonthly. Key stakeholders included upper and lower gastrointestinal surgeons, a gastrointestinal specialist radiologist, a plastic surgeon, a high-risk anaesthetist and two junior doctors integrated into the AWR clinical team. Meetings were held online, where patient history, past medical and surgical history, hernia characteristics and up-to-date computed tomography scans were discussed.

RESULTS

Some 156 patients were discussed over 18 meetings within the above period. Ninety-five (61%) patients were recommended for surgery, and 61 (39%) patients were recommended for conservative management or referred elsewhere. Seventy-eight (82%) patients were directly waitlisted, whereas seventeen (18%) required preoperative optimisation: three (18%) for smoking cessation, eleven (65%) for weight-loss management and three (18%) for specialist diabetic assessment and management. In total, 92 (59%) patients (including operative and nonoperative management) have been discharged to primary care.

DISCUSSION

A multidisciplinary forum for complex abdominal wall patients is a safe process that facilitates decision making, promotes education and improves patient care. As the AWR subspecialty evolves, our view is that the "complex hernia MDT" will become commonplace. We present our experience and share advice for others planning to establish an AWR centre.

A novel self-gripping long-term resorbable mesh providing temporary support for open primary ventral and incisional hernia

A novel synthetic fully long-term resorbable self-gripping mesh has been recently developed to reinforce soft tissue where weakness exists during ventral hernia repair open procedures. This resorbable mesh is a macroporous, knitted, poly-L-lactide, poly-trimethylene carbonate copolymer monofilament mesh with the ProGrip™ technology, providing grips on one side of the mesh. A new poly-L-lactide, poly-trimethylene copolymer was developed to provide the required features for mechanical support during at least 20 weeks covering the critical healing period, including resistance to fatigue under cyclic loading conditions, as it occurs in patients. The yarns and mesh initial physical and biomechanical properties were characterized. Then, the mesh mechanical strength was evaluated over time. The mechanical properties of the proposed mesh were found to be above the generally recognized threshold value to mechanically support the repair site of a hernia over a 20-week period during in-vitro cyclic loading test. The mesh performance was evaluated in vivo using a published preclinical porcine model of hernia repair at 4-, 12- and 20-weeks post implantation. The burst strength of the hernia repair sites reinforced with the new mesh were higher at 4 & 12 weeks and comparable at 20 weeks to the one of the native abdominal walls. At all time points, the mesh was well tolerated with moderate inflammation and was fast integrated in the abdominal wall at 4 weeks. Particularly, the grips were nicely engulfed in the newly formed connective tissue. They must facilitate the anchoring of the mesh by their extension from the mesh and their mushroom shape. The preclinical data of the self-gripping resorbable mesh suggests that it has all the favorable characteristics for future clinical use during ventral hernia repair open procedures.

Poly-4-hydroxybutyrate Mesh for Ventral Hernia Repairs: A Single-Surgeon Experience

Background

Poly-4-hydroxybutyrate (P4HB) (Phasix) biosynthetic mesh was recently introduced as an alternative to synthetic and biologic meshes for ventral hernia repair (VHR). However, outcomes data are limited. This study aims to analyze outcomes of VHR with P4HB mesh and identify predictors of postoperative outcomes.

Methods

We performed a retrospective study of adults who underwent open VHR with P4HB by the senior author from 2014 to 2020 with >12 months' follow-up. Subgroup comparisons and multivariate logistic regression were performed.

Results

Inclusion criteria were met by 169 patients with a median of 15 months of follow-up. Overall, 21.9% had surgical site occurrences, 17.8% required reoperation, and 4.7% had recurrences. Patients with prior VHR (47.9%) experienced similar outcomes to those without. Patients with prior mesh infection (18.3%) had higher rates of postoperative mesh infection (6.5% vs 0.7%; P = .029) but did not have higher rates of reoperation. Retrorectus repairs (45.5%) had similar outcomes to onlay repairs (54.5%). Recurrence risk was increased by hypertension (odds ratio [OR] = 13.64; P = .046), immunosuppression (OR = 42.57; P = .004), and history of prior VHR (OR = 20.20; P = .014).

Conclusions

This study aimed to analyze outcomes of VHR augmented with P4HB mesh through retrospective review. VHR with P4HB mesh produces acceptable recurrence rates with favorable complication risks compared with biologic and synthetic meshes. Predictors of recurrence include a history of prior hernia repair, hypertension, and immunosuppression. A history of prior mesh infection seems to place patients at risk for developing subsequent infection but did not increase need for reoperation.

Abdominal wall hernia repair: from prosthetic meshes to smart materials

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

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.

Biosynthetic meshes in contaminated fields: where are we now? A systematic review and meta-analysis in humans

PURPOSE

Selection of an appropriate mesh reinforcement for hernia repair in contaminated fields is a significant problem for surgeons. To date the proper mesh for contaminated fields has not been found. Biosynthetic meshes have emerged as new treatment option in contaminated fields. This study aims to evaluate the postoperative outcomes of biosynthetic meshes in contaminated fields.

METHODS

Systematic electronic search (PubMed, Medline, Embase, Scopus), according to PRISMA criteria, was performed. A literature search of scientific papers was performed by two reviewers until April 2021. Articles were chosen based on reference to biosynthetic meshes, their use in infected fields, and in human subjects. GRADE methodology and the modified Newcastle-Ottawa scale were used to assess the quality of studies. According to CDC-Centers for Disease Control classes patients were divided into two subgroups, group 1 (CDC class 2) and group 2 (CDC classes 3-4).

RESULTS

The research included 21 articles and 1619 patients were analyzed. Long-term follow-up showed a significant higher recurrence rate than short-term follow-up. P < 0.001. Meta-analysis of these studies showed that the SSI were significantly higher in CDC classes 3-4 than CDC class 2 (P < 0.01). No differences were found in SSO (P = 0.06) and recurrence (P = 0.37) rate among the two groups. Phasix™ was the most common mesh in 15 studies. The mean follow-up was 23.0 months. The surgical site infection (SSI) rate was 17.3%. The surgical site occurrence (SSO) rate was 32.4%. Recurrence rate was 11.5%.

CONCLUSION

This is the first systematic review and meta-analysis on the clinical outcomes of abdominal wall repair using biosynthetic mesh in contaminated-infected settings. The results show good results in patients at high risk of postoperative wound complications. The aim of this study is to add to the growing literature on biosynthetic mesh a picture of current literature evidence to help future researchers performing further studies on this topic.

Incisional hernia repair with a slowly absorbable P4HB mesh: what happens after the mesh disappears? A retrospective longitudinal clinical study

PURPOSE

To analyze the incisional hernia recurrence rate at a long-term follow-up using a biosynthetic long-term absorbable mesh in patients with a higher risk of surgical infection in a contaminated surgical field.

METHODS

This was a retrospective multicentric study. All patients undergoing incisional hernia repair between 2016 and 2018 at 6 participating university centers were included. Patients were classified according to the Ventral Hernia Working Group (VHWG). All consecutive patients who underwent abdominal wall repair using biosynthetic long-term absorbable mesh (Phasix^®) in contaminated fields (grade 3 and 4 of the VHWG classification) were included. Patients were followed-up until September 2021. Preoperative, operative, and postoperative data were collected. All patients' surgical site infections (SSIs) and surgical site occurrences (SSOs) were recorded. The primary outcome of interest was the clinical incisional hernia recurrence rate.

RESULTS

One hundred and eight patients were included: 77 with VHWG grade 3 (71.3%) and 31 with VHWG grade 4 (28.7%). Median time follow-up was 41 months [24; 63]. Twenty-four patients had clinical recurrence during the follow-up (22.2%). The SSI and SSO rates were 24.1% and 36.1%, respectively. On multivariate analysis, risk factors for incisional hernia recurrence were previous recurrence, mesh location, and postoperative enterocutaneous fistula.

CONCLUSIONS

At the 3 year follow-up, the recurrence rate with a biosynthetic absorbable mesh (Phasix^®) for incisional hernia repair in high-risk patients (VHWG grade 3 and 4) seemed to be suitable (22.2%). Most complications occurred in the first year, and SSI and SSO rates were low despite high-risk VHWG grading.

Polyhydroxyalkanoates (PHAs) as Biomaterials in Tissue Engineering: Production, Isolation, Characterization

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible biopolymers. These biomaterials have grown in importance in the fields of tissue engineering and tissue reconstruction for structural applications where tissue morphology is critical, such as bone, cartilage, blood vessels, and skin, among others. Furthermore, they can be used to accelerate the regeneration in combination with drugs, as drug delivery systems, thus reducing microbial infections. When cells are cultured under stress conditions, a wide variety of microorganisms produce them as a store of intracellular energy in the form of homo- and copolymers of [R]—hydroxyalkanoic acids, depending on the carbon source used for microorganism growth. This paper gives an overview of PHAs, their biosynthetic pathways, producing microorganisms, cultivation bioprocess, isolation, purification and characterization to obtain biomaterials with medical applications such as tissue engineering.

Self-adhesive hydrogel meshes reduce tissue incorporation and mechanical behavior versus microgrips self-fixation: a preclinical study

Purpose

Atraumatic mesh fixation for abdominal hernia repair has been developed to avoid the disadvantages of classical fixation with sutures, which is considered a cause of chronic pain and discomfort. This study was designed to analyze, in the short and medium term, the biological and mechanical behavior of two self-fixing meshes compared to that of a polypropylene (PP) mesh fixed with a cyanoacrylate (CA) tissue adhesive.

Methods

Partial abdominal wall defects (6 × 4 cm) were created in New Zealand rabbits (n = 36) and repaired using a self-adhesive hydrogel mesh (Adhesix™), a self-gripping mesh (ProGrip™) or a PP mesh fixed with CA (Surgipro™ CA). After 14 and 90 days, the host tissue incorporation, macrophage response and biomechanical strength were examined.

Results

At 14 and 90 days, the ProGrip and Surgipro CA meshes showed good host tissue incorporation; however, the Adhesix implants presented poor integration, seroma formation and a higher degree of shrinkage. The Adhesix hydrogel was completely reabsorbed at 14 days, whereas ProGrip microhooks were observed at all study times. The macrophage response was higher in the ProGrip and Surgipro CA groups at 14 and 90 days, respectively, and decreased over time. At 90 days, the ProGrip implants showed the highest tensile strength values and the Adhesix implants showed the highest failure stretch.

Conclusion

Meshes with mechanical microgrip self-fixation (ProGrip) show better biological and mechanical behavior than those with adhesive hydrogel (Adhesix) in a preclinical model of abdominal hernia repair in rabbits.

The Synthetic Scaffolds for Ventral Hernia Repair: Perspectives for Regenerative Surgery—Systematic Review

Ventral hernia (VH) frequently affects patients after abdominal surgery. The use of a mesh is often recommended. Different materials are described, from synthetic non-resorbable meshes to biological meshes. New generation meshes, also named scaffolds, aim to combine the advantages of both materials. The aim of this review is to provide an overview of the cytological, histological, biomechanical, and clinical outcomes of the use of the newest resorbable synthetic scaffolds in VH repair, based on experimental studies in a pre-clinical setting. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and to the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) guidelines. Only experimental studies were included. Outcome parameters were building technique, in vitro cytocompatibility, in vivo histocompatibility, biomechanical analysis, and clinical outcomes. The articles included were nine. The total number of cases treated was 257. Materials analyzed included electrospun silk fibroin (SF)/poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) hybrid scaffolds, biodegradable polyester poly-ε-caprolactone (PCL) in the form of nanofibers, biodegradable mesh in poly-4-hydroxybutyrate (P4HB), nanofibrous polylactic acid (PLA) scaffold with a polypropylene (PP) material to generate a sandwich-like mesh, the collagen sponge (CS) group, the hybrid scaffold (HS) containing CS and poly-L-lactide (PLLA), and the hybrid scaffold (HS) + bone marrow (HSBM). Resorbable synthetic scaffolds are new, safe, surgical materials for the treatment or prevention of ventral hernia in animal models. Scaffolds should be tested in a contaminated surgical field for emergency use. Rigorous schematic indications for data collection are needed to improve the quality of the data in order to definitively clarify the pathway involved in inflammatory induced response.

Current Advances towards 4-Hydroxybutyrate Containing Polyhydroxyalkanoates Production for Biomedical Applications

Polyhydroxyalkanoates (PHA) are polyesters having high promise in biomedical applications. Among different types of PHA, poly-4-hydroxybutyrate (P4HB) is the only polymer that has received FDA approval for medical applications. However, most PHA producing microorganisms lack the ability to synthesize P4HB or PHA comprising 4-hydroxybutyrate (4HB) monomer due to their absence of a 4HB monomer supplying pathway. Thus, most microorganisms require supplementation of 4HB precursors to synthesize 4HB polymers. However, usage of 4HB precursors incurs additional production cost. Therefore, researchers have adopted strategies to reduce the cost, such as utilizing low-cost substrate as well as constructing 4HB monomer supplying pathways in microorganisms. We herein summarize the biomedical applications of P4HB, the natural producers of 4HB polymer, and the various strategies that have been applied in producing 4HB polymers in non-4HB producing microorganisms. It is expected that the readers would gain a vivid idea on the different strategic developments in the field of 4HB polymer production.

Resorbable Synthetic Ventral Hernia Repair in Contaminated Fields: Outcomes with Poly-4-Hydroxybutyrate Mesh

BACKGROUND

Hernia repair in the setting of contamination poses unique challenges, including complications such as recurrence and mesh infection. The ideal contaminated hernia repair including type of mesh use remains controversial. Poly-4-hydroxybutyrate is a biosynthetic scaffold for soft-tissue reinforcement and hernia repair and is potentially useful in contaminated hernia repair. The authors aim to describe postoperative outcomes, recurrence, and patient-reported outcomes after contaminated hernia repair with poly-4-hydroxybutyrate.

METHODS

Adult patients (≥18 years) undergoing a contaminated hernia repair with poly-4-hydroxybutyrate (Phasix) performed by a single plastic surgeon between January of 2015 and May of 2020 were identified. Patients with a ventral hernia defect and a Centers for Disease Control and Prevention wound class of II, III, or IV were included. Primary outcomes included recurrence, surgical-site infection, surgical-site occurrences, and surgical-site infection/occurrences requiring procedural interventions. As a secondary outcome, the authors assessed patient-reported outcomes as defined by the Abdominal Hernia-Q and Hernia-Related Quality of Life Survey.

RESULTS

Sixty patients were included with a median age of 52.5 and body mass index of 31 kg/m2. Median defect size was 300 cm2. Twenty-eight patients (46.7 percent) experienced a complication. The most common complications were surgical-site occurrence [n = 20 (33.3 percent)] and surgical-site infection [n = 10 (16.7 percent)]. Median follow-up was 24.2 months, with a recurrence rate of 8.3 percent (n = 4). Overall patient-reported outcomes improved postoperatively, and improvement was not affected by the presence of a complication.

CONCLUSIONS

Poly-4-hydroxybutyrateuse in contaminated hernia repair shows promising results with an acceptable safety profile. Although complications are frequent in this complex cohort, patient-reported outcomes improvement was significant even in patients with complications.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

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.

Long-term follow-up of prophylactic mesh reinforcement after emergency laparotomy. A retrospective controlled study

BACKGROUND

Prevention of incisional hernias with a prophylactic mesh in emergency surgery is controversial. The present study aimed to analyze the long-term results of prophylactic mesh used for preventing incisional hernia after emergency midline laparotomies.

METHODS

This study was a registered (NCT04578561) retrospective analysis of patients who underwent an emergency midline laparotomy between January 2009 and July 2010 with a follow-up period of longer than 2 years. Long-term outcomes and risk factors for the development of incisional hernias between patients who received a prophylactic reinforcement mesh (Group M) and suture (Group S) were compared.

RESULTS

From an initial 266 emergency midline laparotomies, 187 patients were included. The median follow-up time was 64.4 months (SD 35). Both groups had similar characteristics, except for a higher rate of previous operations (62 vs. 43.2%; P = 0.01) and operation due to a revision laparotomy (32.5 vs.13%; P = 0.02) in the M group. During follow-up, 29.9% of patients developed an incisional hernia (Group S 36.6% vs. Group M 14.3%; P = 0.002). Chronic mesh infections were diagnosed in 2 patients, but no mesh explants were needed, and no patient in the M group developed chronic pain. Long-term risk factors for incisional hernia were as follows: smoking (HR = 2.47; 95% CI 1.318-4.624; P = 0.05), contaminated surgery (HR = 2.98; 95% CI 1.142-7.8; P = 0.02), surgical site infection (SSI; HR = 3.83; 95% CI 1.86-7.86; P = 0.001), and no use of prophylactic mesh (HR = 5.09; 95% CI 2.1-12.2; P = 0.001).

CONCLUSION

Incidence of incisional hernias after emergency midline laparotomies is high and increases with time. High-risk patients, contaminated surgery, and surgical site infection (SSI) benefit from mesh reinforcement. Prophylactic mesh use is safe and feasible in emergencies with a low long-term complication rate.

TRIAL REGISTRATION

NCT04578561. www.clinicaltrials.gov.

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.

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.

Regulatory science for hernia mesh: Current status and future perspectives

Regulatory science for medical devices aims to develop new tools, standards and approaches to assess the safety, effectiveness, quality and performance of medical devices. In the field of biomaterials, hernia mesh is a class of implants that have been successfully translated to clinical applications. With a focus on hernia mesh and its regulatory science system, this paper collected and reviewed information on hernia mesh products and biomaterials in both Chinese and American markets. The current development of regulatory science for hernia mesh, including its regulations, standards, guidance documents and classification, and the scientific evaluation of its safety and effectiveness was first reported. Then the research prospect of regulatory science for hernia mesh was discussed. New methods for the preclinical animal study and new tools for the evaluation of the safety and effectiveness of hernia mesh, such as computational modeling, big data platform and evidence-based research, were assessed. By taking the regulatory science of hernia mesh as a case study, this review provided a research basis for developing a regulatory science system of implantable medical devices, furthering the systematic evaluation of the safety and effectiveness of medical devices for better regulatory decision-making. This was the first article reviewing the regulatory science of hernia mesh and biomaterial-based implants. It also proposed and explained the concepts of evidence-based regulatory science and technical review for the first time.

Behaviour at the peritoneal interface of next-generation prosthetic materials for hernia repair

BACKGROUND

When using a prosthetic material in hernia repair, the behaviour of the mesh at the peritoneal interface is especially important for implant success. Biomaterials developed for their intraperitoneal placement are known as composites and are made up of two different-structure materials, one is responsible for good integration within host tissue and the other is responsible to make contact with the viscera. This study examines the behaviour at the peritoneal level of two composites, the fully degradable Phasix-ST® and the partially degradable Symbotex®. A polypropylene mesh (Optilene®) served as control.

METHODS

Sequential laparoscopy from 3 to 90 days, in a preclinical model in the New Zealand white rabbit, allowed monitoring adhesion formation. Morphological studies were performed to analyse the neoperitoneum formed in the repair process. Total macrophages were identified by immunohistochemical labelling. To identify the different macrophage phenotypes, complementary DNAs were amplified by qRT-PCR using specific primers for M1 (TNF-α/CXCL9) and M2 (MRC1/IL-10) macrophages.

RESULTS

The percentage of firm and integrated adhesions remained very high in the control group over time. Both composites showed a significant decrease in adhesions at all study times and in qualitative terms were mainly loose. Significant differences were also observed from 7 days onwards between the two composites, increasing the values in Phasix over time. Neoperitoneum thickness for Phasix was significantly greater than those of the other meshes, showing mature and organized neoformed connective tissue. Immunohistochemically, a significantly higher percentage of macrophages was observed in Symbotex. mRNA expression levels for the M2 repair-type macrophages were highest for Phasix but significant differences only emerged for IL-10.

CONCLUSIONS

Fewer adhesions formed to the Symbotex than Phasix implants. Ninety days after implant, total macrophage counts were significantly higher for Symbotex, yet Phasix showed the greater expression of M2 markers related to the tissue repair process.

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.

Mechanical and Histological Characteristics of Phasix™ ST Mesh in a Porcine Model of Hernia Repair

PURPOSE

The objective of this study was to determine mechanical and histological properties of Phasix™ ST Mesh in various defect sizes and characterize the tissue replacing Phasix™ ST Mesh in a porcine model of ventral hernia repair.

METHODS

Simulated hernia defects were surgically created in the midline of twenty-four (n = 24) Yucatan pigs. Treatment groups included 8 cm defect sutured closed (buttress) and unclosed 4 cm and 8 cm defect groups. Phasix™ ST Mesh (15 cm diameter circle) was implanted laparoscopically and fixated circumferentially with SorbaFix™ Absorbable Fixation System fasteners. The repair sites underwent mechanical, molecular weight, and histological evaluation at 48 and 72 weeks postimplantation.

RESULTS

Mechanical testing of Phasix™ ST Mesh-repaired sites revealed similar strengths at both time points for all three repair types, p > 0.05 in all cases (48 weeks: 142.4 ± 6.0 N, 142.3 ± 16.5 N, and 168.8 ± 38.5 N; 72 weeks: 110.0 ± 18.3 N, 138.6 ± 42.2 N, and 160.6 ± 42.0 N for 4 cm defect, 8 cm defect, and 8 cm buttress, respectively. mean ± SEM) No significant differences were observed over time except at 72 weeks postimplantation when the 4 cm defect group exhibited significantly lower strength than the T₀ strength of Phasix™ ST Mesh (204.6 ± 5.0 N, p < 0.05). The molecular weight of Phasix™ ST Mesh decreased over time, regardless of repair type. Histological analysis showed comparable mature collagen/fibrovascular tissue around and within the Phasix™ ST Mesh interstices, including the segment of mesh overlying the defect.

CONCLUSION

Phasix™ ST Mesh-repaired sites exhibited similar mechanical strengths and histological properties across all defect sizes in this porcine model.

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.

Abdominal wall reconstruction with biosynthetic absorbable mesh after infected prosthesis explantation: single stage is better than two-stage approach of chronic mesh infection

PURPOSE

To assess the efficacy of surgical management of chronic mesh infection (CMI) after abdominal wall hernia repair (AWHR) in single-stage approach (complete removal of infected prosthesis and simultaneous replacement with poly-4-hydroxybutyrate mesh or BAM group), comparing results with two-stage treatment (complete mesh excision and abdominal wall repair with synthetic mesh after several months or SPM group).

METHODS

Retrospective comparative study of all patients who underwent surgery for CMI between January 2006 and January 2019 at a tertiary center. We compared results in terms of epidemiological data, hernia and prosthesis characteristics, surgical and postoperative variables of both two groups.

RESULTS

Over the 13-year study period, 2791 AWHR was performed at our hospital; the overall CMI rate was 2.5%. Of 71 patients, 30 (42.2%) were in BAM group and 41 (57.8%) in SPM group. The median cumulative operative time (252 min versus 132 min) and length of stay (16.6 days versus 6.2 days) were significatively longer in SPM group compared with BAM group, due to the need of two surgical procedures. There were a higher number of postoperative complications in SPM group (p = 0.002), some of them grade III. With mean follow-up of 36.5 months (range 21-59), there were no significant differences in terms of overall hernia recurrence and mesh reinfection in both groups.

CONCLUSION

The use of a poly-4-hydroxybutyrate resorbable mesh in single-stage management of CMI may be a safe and better option than two-stage approach, although more studies are needed to confirm our results.

Analysis of resorbable mesh implants in short-term human muscular fascia cultures: a pilot study

PURPOSE

Alteration in fascial tissue collagen composition represents a key factor in hernia etiology and recurrence. Both resorbable and non-resorbable meshes for hernia repair are currently used in the surgical setting. However, no study has investigated so far the role of different implant materials on collagen deposition and tissue remodeling in human fascia. The aim of the present study was to develop a novel ex vivo model of human soft tissue repair mesh implant, and to test its suitability to investigate the effects of different materials on tissue remodeling and collagen composition.

METHODS

Resorbable poly-4-hydroxybutyrate and non-resorbable polypropylene mesh implants were embedded in human abdominal fascia samples, mimicking common surgical procedures. Calcein-AM/Propidium Iodide vital staining was used to assess tissue vitality. Tissue morphology was evaluated using Mallory trichrome and hematoxylin and eosin staining. Collagen type I and III expression was determined through immunostaining semi-quantification by color deconvolution. All analyses were performed after 54 days of culture.

RESULTS

The established ex vivo model showed good viability at 54 days of culture, confirming both culture method feasibility and implants biocompatibility. Both mesh implants induced a disorganization of collagen fibers pattern. A statistically significantly higher collagen I/III ratio was detected in fascial tissue samples cultured with resorbable implants compared to either non-resorbable implants or meshes-free controls.

CONCLUSION

We developed a novel ex vivo model and provided evidence that resorbable polyhydroxybutyrate meshes display better biomechanical properties suitable for proper restoration in surgical hernia repair.

Platelet-rich plasma PRP vs. absorbable mesh as cruroplasty reinforcement: a study on an animal model

BACKGROUND

Reinforcement of posterior cruroplasty has been proposed to minimize the failure of hiatal hernia repair (HHR). The applications of autologous platelet-rich plasma (PRP) and absorbable mesh are barely reported in this area.

AIMS

To analyze local macroscopic and microscopic changes induced by mesh vs. PRP as reinforcement of HHR, using a reliable laparoscopic experimental porcine model.

MATERIAL AND METHODS

This prospective, comparative pilot study was conducted on 14 female pigs, aged four to six months. An iatrogenic hiatal defect was laparoscopically simulated and repaired, reinforced with Bio-A® mesh (group A) or PRP (group B). Specimen retrieval was performed after seven months for histopathological (HP) examination.

RESULTS

No local or general complications were registered, with complete resorption of reinforcements, that determined inflammatory infiltrates with local collagen production and tissue neo-vascularization. Group A had an increased mean chronic inflammation score (p = .3061), showing significant sclerotic collagenizing process. PRP enhanced angiogenesis, collagenizing, myofibroblast recruitment and tissue ingrowth.

CONCLUSIONS

No residual materials or evidence of anatomical distortion were found. Animal model was safe and reliable. This is the first report of complete absorption of Bio-A^® positioned on crural area. HP results suggest the clinical application of PRP in HHR as a promising co-adjuvant to local remodeling and healing.Abbreviations: ASA: American Society of Anesthesiologists; AB: Alcian Blue; PAS: Periodic Acid-Schiff; CP: platelet concentrate; fPC: filtered plasma concentrate; GERD: gastro-esophageal reflux disease; HSA: hiatal surface area; HHR: hiatal hernia repair; HP: histopathological; HH: hiatal hernia; HE: hematoxylin and eosin; HR: hiatus repair alone; HRM: hiatus repair and acellular dermal matrix; NM: Nicolae Manolesccu; LNF: laparoscopic Nissen fundoplication; PC: posterior cruroplasty; PPP: platelet-poor plasma; RP: platelet-rich plasma.

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.

Comparison of Phasix, polypropylene, and primary closure of the abdominal donor site after bilateral free flap breast reconstruction: Long-term evaluation of abdominal hernia and bulge formation

BACKGROUND

Abdominal free flap harvest for breast reconstruction may result in significant morbidity in terms of hernias and bulges. Reinforcement of the donor site with mesh has been recommended to minimize the risk of hernias and bulges, but no studies exist evaluating the optimal type of mesh. Polypropylene has traditionally been used but the development of Phasix restorable mesh may be a reasonable alternative. Here, we compared the use of Phasix to polypropylene and primary closure and hypothesize that the former has lower rates of abdominal morbidity in the long term.

PATIENTS AND METHODS

A retrospective review of all patients undergoing bilateral free flap breast reconstruction from the abdomen was performed while patients with pedicle flaps or alternative donor sites were excluded. Patient demographics, medical/surgical history, cancer treatments, and flap type were analyzed. All patients were monitored for a minimum of 2 years for early donor site complications as well as hernia/bulges.

RESULTS

Sixty-six consecutive patients were included (40 patients with Phasix, 20 patients with polypropylene, and 6 patients with primary closure). Use of Phasix mesh resulted in higher initial operative costs ($2,750 vs. $72 vs. $0). Two patients with polypropylene mesh and one patient undergoing primary closure developed an abdominal bulge in an average follow-up of 25.2 months (11.5% vs. 0%, p = .04).

CONCLUSIONS

Mesh placement for abdominal wall reinforcement after bilateral free flap breast reconstruction minimizes the risk of hernias and bulges. Although Phasix results in increased initial costs, abdominal morbidity is significantly decreased after follow-up beyond 2 years.

When the Mesh Goes Away: An Analysis of Poly-4-Hydroxybutyrate Mesh for Complex Hernia Repair

Mesh reinforcement is a cornerstone of modern ventral hernia repair (VHR); yet, complications with synthetic mesh and cost of biologic have created a need for alternative options. Biosynthetic mesh is a resorbable scaffold that theoretically leverages the benefits and minimizes deficiencies of existing mesh types. This study evaluates 2-year outcomes following poly-4-hydroxybutyrate (P4HB) mesh reinforcement for complex VHR.

Methods

A retrospective review of all consecutive VHR with P4HB (n = 70) was conducted from 2015 to 2018 by a single surgeon. Clinical outcomes, quality of life (QoL; and cost were assessed.

Results

Seventy patients were included with an average age and body mass index of 58.6 years and 33 kg/m², respectively. High-risk comorbidities included hypertension (59%), and smoking history (50%). Cases were primarily modified Ventral Hernia Working Group class 2 (50%), or 3 (36%), with average defect size of 323 cm² (25-972 cm²). P4HB was placed in the retromuscular (80%) or onlay (20%) plane. Mean follow-up was 24 months (12.2-41 months). Hernia recurrence rate was 5.7% (n = 4) and occurred an average of 285 days (209-368 days) post-repair. Of the 21 surgical site occurrences (SSO), 5 (7%) required surgical intervention. A significant improvement in overall QoL (P = 0.001) was noted following repair. Defect size and SSOPI were independently associated with increased direct cost.

Conclusions

P4HB mesh for complex VHR is associated with favorable 2-year clinical outcomes, acceptable hernia recurrence rate, and a significant improvement in QoL. This study supports the use of biosynthetic mesh as an effective biomaterial for complex VHR.

Incidence of Incisional Hernia After Emergency Subcostal Unilateral Laparotomy: Does Augmentation Prophylaxis Play a Role?

BACKGROUND

Few data are available about the frequency of incisional hernia in an emergency subcostal laparotomy. Our objective is to analyze the incidence of incisional hernia after emergency subcostal laparotomy and evaluate if prophylactic mesh could help prevent it.

METHODS

This study is a monocentric retrospective analysis following STROBE guideline statements of all patients who underwent an emergency subcostal laparotomy between January 2011 and July 2017 in our University Hospital. We compared complications and incidence of incisional hernia between patients who received sutures (Group S; N = 203) and patients with prophylactic onlay mesh (Group M; N = 80). A multivariate risk factor analysis of incisional hernia was performed. An incisional hernia-estimated risk calculator equation was created.

RESULTS

A total of 283 patients were analyzed. There were 80 patients in Group M and 203 in Group S. In short-term outcomes, length of surgery (213 ± 115 min vs 165 ± 73.3 min, P = 0.001) and hospital stay (16.4 ± 18.7 vs 11.6 days ± 13.4, P = 0.038) were longer in Group M. Long-term follow-up was conducted in 207 patients with a mean follow-up time of 39.3 ± 23 months. Incisional hernia was detected in 29 (19.1%) patients in Group S but in only two (3.8%) patients in Group M (P = 0.008). In the multivariate analysis, a risk factor analysis included wound infection (4.91 HR (2.12-11.4); P < 0.001), previous hernia repair (2.86 HR (1.24-6.61); P = 0.014), and shock (2.64 HR (1.01-6.93); P = 0.048).

CONCLUSIONS

The incidence of incisional hernia after emergency subcostal laparotomy is high. Risk factors are wound infection, shock, and previous hernia surgery. The use of prophylactic mesh augmentation was safe and reduced the incidence of incisional hernia.

Biomechanical Behaviour and Biocompatibility of Ureidopyrimidinone-Polycarbonate Electrospun and Polypropylene Meshes in a Hernia Repair in Rabbits

Although mesh use has significantly improved the outcomes of hernia and pelvic organ prolapse repair, long-term recurrence rates remain unacceptably high. We aim to determine the in vivo degradation and functional outcome of reconstructed abdominal wall defects, using slowly degradable electrospun ureidopyrimidinone moieties incorporated into a polycarbonate backbone (UPy-PC) implant compared to an ultra-lightweight polypropylene (PP) textile mesh with high pore stability. Twenty four New-Zealand rabbits were implanted with UPy-PC or PP to either reinforce a primary fascial defect repair or to cover (referred to as gap bridging) a full-thickness abdominal wall defect. Explants were harvested at 30, 90 and 180 days. The primary outcome measure was uniaxial tensiometry. Secondary outcomes were the recurrence of herniation, morphometry for musculofascial tissue characteristics, inflammatory response and neovascularization. PP explants compromised physiological abdominal wall compliance from 90 days onwards and UPy-PC from 180 days. UPy-PC meshes induced a more vigorous inflammatory response than PP at all time points. We observed progressively more signs of muscle atrophy and intramuscular fatty infiltration in the entire explant area for both mesh types. UPy-PC implants are replaced by a connective tissue stiff enough to prevent abdominal wall herniation in two-thirds of the gap-bridged full-thickness abdominal wall defects. However, in one-third there was sub-clinical herniation. The novel electrospun material did slightly better than the textile PP yet outcomes were still suboptimal. Further research should investigate what drives muscular atrophy, and whether novel polymers would eventually generate a physiological neotissue and can prevent failure and/or avoid collateral damage.

Evaluation of resorbable polydioxanone and polyglycolic acid meshes in a rat model of ventral hernia repair

The objective of this study was to evaluate physical, mechanical, and biological properties of the polydioxanone (PDO) monofilament meshes and polyglycolide (PGA) polyfilament meshes in comparison with Permacol^® implants. In rat experimental model, a 1.5 × 2.0 cm defect in abdominal wall was reconstructed by using the Permacol surgical implant or knitted meshes produced from either PDO monofilament, or PGA multifilament. The implant sites were assessed for the tensile strength and the extents of material resorption, host inflammatory response and host tissue replacement on days 3, 10, 30, or 60 after the surgery. The PDO and PGA meshes were rapidly pervaded by the host connective tissue with elements of skeletal muscle histogenesis. The degree of adhesions was significantly higher in the Permacol group. All of the prostheses underwent resorption, which correlated with gradual decreases in the overall tensile strength of the site and the Col1a1 gene expression level. Elevated expression of Fgf2 gene maintained longer in the PDO group, and the Mmp9 gene expression level in this group was higher than in the other groups. Gene expression levels of inflammatory cytokines were higher in the Permacol group. The foreign body giant cell numbers were lower in the PDO and Permacol groups than in the PGA group. Minimal macrophage infiltration with predominance of M2 cells was observed in the PDO group. Overall, the PDO prosthesis turned out to be significantly better than the PGA or Permacol prostheses by a number of indicators of biocompatibility and efficacy. © 2018 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 652-663, 2019.

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

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

Retrorectus repair of incisional ventral hernia with urinary bladder matrix reinforcement in a long-term porcine model

Aim: Not all biologically derived materials elicit the same host response when used for reinforcement of ventral hernia repairs. This study aimed to evaluate the remodeling characteristics of the abdominal wall following reinforcement with urinary bladder matrix (UBM) in a large animal preclinical model of ventral hernia repair. Materials & methods: Midline defects in 36 Yucatan minipigs were reinforced with UBM-derived surgical devices using a classic Rives–Stoppa–Wantz approach, and compared with primary repair controls. After 3 or 8 months, the abdominal wall was explanted for histological and mechanical analysis. Results & conclusion: All UBM-derived surgical devices were completely resorbed within 8 months and facilitated deposition of vascularized, biomechanically functional connective tissue in the retrorectus plane, with no evidence of hernia formation.

Updates in Mesh and Biomaterials

Prior publications of the Surgical Clinics of North America have highlighted the technical challenges of abdominal wall reconstruction. This article provides an update on synthetic, biologic, and biosynthetic mesh research since the 2013 Surgical Clinics of North America hernia publication and highlights the future of mesh research. This update features research that has been conducted since the prior publication to guide surgeons to choose the best and most appropriate mesh for their patients.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Clinical Use of GalaFLEX in Facial and Breast Cosmetic Plastic Surgery

Resolution of ptosis is a key step to the success of many plastic surgery procedures. Ptosis is a manifestation of tissue stretch. Tissue stretch can occur as a result of the natural aging process or health of the patient, or tissue may stretch under added weight or volume, such as when implants are placed. Surgical rejuvenation of ptotic tissues is very effective and results in marked changes in the patient profile yet the tissue that resulted in the need for the procedure first place has not improved and ptosis can recur. Recent developments in long-term resorbable porous materials have provided surgeons with the opportunity to experiment with tissue reinforcement in plastic surgery procedures. These new materials have a low profile, rapid tissue integration, and a long-term strength retention profile. Long-term resorbable scaffolds such as poly-4-hydroxybutyrate (P4HB) natural scaffold (GalaFLEX scaffold, Galatea Surgical, Inc., Lexington, MA) have shown promise for a host of plastic surgery indications. This article presents clinical experience with GalaFLEX for soft tissue reinforcement in three different clinical applications; including the reinforcement of the superficial muscular aponeurotic system (SMAS) in minimally invasive facelift, reinforcement of the skin envelope in mastopexy, and reinforcement of the breast capsule (pocket) in revisional breast surgery. Soft tissue reinforcement has been shown to provide increased mechanical strength as well as improved maintenance of postoperative results.

LEVEL OF EVIDENCE

5 Therapeutic.