Experimental data show that large-pored meshes reduce foreign body reaction, inflammation and scar bridging and thus improve mesh integration. However, clinical data on the effect of mesh porosity on the outcome of hernioplasty are limited. This study investigated the relation of pore size in polypropylene meshes to the outcome of Lichtenstein inguinal hernioplasty using data from the Herniamed registry.

This analysis of data from the Herniamed registry evaluated perioperative and 1-year follow-up outcomes in patients undergoing elective, primary, unilateral Lichtenstein inguinal hernia repair using polypropylene meshes. Patients operated with a non-polypropylene mesh or a polypropylene mesh with absorbable components were excluded. Polypropylene meshes with a pore size of 1.0 × 1.0 mm or less were defined as small-pored meshes, while a pore size of more than 1.0 × 1.0 mm was considered large-pored. Unadjusted analyses and multivariable analyses were performed to investigate the relation of pore size of polypropylene meshes, patient and surgical characteristics to the outcome parameters.

Data from 22,141 patients were analyzed, of which 6853 (31%) were operated on with a small-pore polypropylene mesh and 15,288 (69%) with a large-pore polypropylene mesh. No association of mesh pore size with intraoperative, general or postoperative complications, recurrence rate or pain requiring treatment was found at 1-year follow-up. A lower risk of complication-related reoperation tended to be associated with small-pore size (p = 0.086). Furthermore, small-pore mesh repair was associated with a lower risk of pain at rest and pain on exertion at 1-year follow-up.

The present study could not demonstrate an advantage of large-pore polypropylene meshes for the outcome of Lichtenstein inguinal hernioplasty.

Repair and reconstruction of the myopectineal orifice area using meshes is the mainstay of surgical treatment of inguinal hernias. However, the limitations of existing meshes are becoming increasingly evident in clinical applications; thus, the idea of using three-dimensionally (3D)-printed biological meshes was put forward. According to the current level of the 3D printing technology and the inherent characteristics of biological materials, the direct use of the 3D printing technology for making biological materials into finished products suitable for clinical applications is not yet supported, but synthetic materials can be first printed into 3D form carriers, compounded with biological materials, and finally made into finished products. The purpose of this study was to develop a technical protocol for making 3D-printed biomesh carriers using polyurethane as a raw material. In our study: raw material, polyurethane; weight, 20-30 g/m2; weaving method, hexagonal mesh; elastic tension aspect ratio, 2:1; diameters of pores, 0.1-1 mm; surface area, 8 × 12 cm2; the optimal printing layer height, temperature and velocity were 0.1 mm, 210-220 °C and 60 mm/s. Its clinical significance lies in: (1) applied to preoperative planning and design a detailed surgical plan; (2) applied to special types of surgery including patients in puberty, recurrent and compound inguinal hernias; (3) significantly improve the efficiency of doctor-patient communication; (4) it can shorten the operation and recovery period by about 1/3 and can save about 1/4 of the cost for patients; (5) the learning curve is significantly shortened, which is conducive to the cultivation of reserve talents.

Particulate matters (PM) and volatile organic compounds (VOCs) are the sources of toxic substances that hurt human health and can cause human carcinogens. An active living wall was applied to reduce PM and VOC contamination, while Sansevieria trifasciata cv. Hahnii, a high-performance plant for VOC removal, was selected to grow on the developing wall and used to treat PM and VOCs. The active living wall operating in a 24 m3 testing chamber showed the ability to remediate more than 90% PM within 12 h. The VOC removal can be approximately 25-80% depending on each compound. In addition, the suitable flow velocity of the living wall was also investigated. The flow rate of 1.7 m3 h-1 in front of the living wall was found as the best inlet flow velocity for the developed active living wall. The suitable condition for PM and VOC removal in the active living wall application on the real side was presented in this study. The result confirmed that the application of an active living wall for PM phytoremediation can be an alternative effective technology.

This study uses free-floating contractile fibroblast-populated collagen matrices (FPCMs) to test the shrinkage of different hernia mesh products. We hope to present this model as a proof of concept for the development of in vitro hernia mesh testing-a novel technology with interesting potential.

FPCMs were formed by seeding Human Dermal Fibroblasts into collagen gels. FPCMs were seeded with three different cell densities and cast at a volume of 500 μl into 24-well plates. Five different mesh products were embedded within the collagen constructs. Gels were left to float freely within culture media and contract over 5 days. Photographs were taken daily and the area of the collagen gel and mesh were measured. Media samples were taken at days 2 and 4 for the purposes of measuring MMP-9 release. After 5 days, dehydrated FPCMs were also examined under light and fluorescence microscopy to assess cell morphology.

Two mesh products-the mosquito net and large pore lightweight mesh were found to shrink notably more than others. This pattern persisted across all three cell densities. There were no appreciable differences observed in MMP-9 release between products.

This study has successfully demonstrated that commercial mesh products can be successfully integrated into free-floating contractile FPCMs. Not only this, but FPCMs are capable of applying a contractile force upon those mesh products-eliciting different levels of contraction between mesh products. Such findings demonstrate this technique as a useful proof of concept for future development of in vitro hernia mesh testing.

There is considerable variability among surgeons regarding the type of mesh used in ventral hernia repair. There has been an increasing incidence of mesh fractures with lightweight (LW) and mediumweight (MW) meshes. However, HW mesh has been associated with a greater foreign body sensation and chronic pain. This meta-analysis aims to compare the outcomes of HW and non-heavyweight (NHW) meshes in ventral hernia repair.

We systematically reviewed the PubMed, Embase, Cochrane, and Scopus databases to identify studies comparing HW with NHW meshes in hernia repair. Outcomes analyzed included hernia recurrence, seroma, hematoma, foreign body sensation, postoperative pain, and wound infection. We performed two subgroup analyses focusing on randomized controlled trials and open retromuscular repairs. Statistical analysis was performed using RevMan 5.4.

We screened 1704 studies. Nine studies were finally included in this meta-analysis and comprised 3001 patients from 4 RCTs and 5 non-randomized. The majority of patients (57.1%) underwent open retromuscular repair. HW mesh was significantly associated with increased in foreign body sensation (OR 3.71; 95% CI 1.40-9.84; p = 0.008), but there was no difference in other outcomes. In RCTs analysis, there was no difference between meshes. In open retromuscular repairs, HW mesh was associated with more seromas (OR 1.48; 95% CI 1.01-2.17; p = 0.05).

Our study found that HW mesh was associated with more foreign body sensation. Also, open retromuscular repairs analysis showed that HW was associated with more seromas. Further randomized studies are needed to understand better the role of HW mesh in ventral hernia repair.

This study compared the in vitro/benchtop and in vivo mechanical properties and host biologic response to ovine rumen-derived/polymer mesh hybrid OviTex™ with porcine-derived acellular dermal matrix Strattice™ Firm.

OviTex 2S Resorbable (OviTex 2S-R) and Strattice morphology were examined in vitro using histology and scanning electron microscopy; mechanical properties were assessed via tensile test; in vivo host biologic response and explant mechanics were evaluated in a rodent subcutaneous model. Separately, OviTex 1S Permanent (OviTex 1S-P) and Strattice were evaluated in a primate abdominal wall repair model.

OviTex 2S-R demonstrated layer separation, whereas Strattice retained its structural integrity and demonstrated higher maximum load than OviTex 2S-R out-of-package (124.8 ± 11.1 N/cm vs 37.9 ± 5.5 N/cm, p < 0.001), 24 h (55.7 ± 7.4 N/cm vs 5.6 ± 3.8 N/cm, p < 0.001), 48 h (45.3 ± 14.8 N/cm vs 2.8 ± 2.6 N/cm, p = 0.003), and 72 h (29.2 ± 10.5 N/cm vs 3.2 ± 3.1 N/cm, p = 0.006) following collagenase digestion. In rodents, inflammatory cell infiltration was observed between OviTex 2S-R layers, while Strattice induced a minimal inflammatory response. Strattice retained higher maximum load at 3 (46.3 ± 27.4 N/cm vs 9.5 ± 3.2 N/cm, p = 0.041) and 6 weeks (28.6 ± 14.1 N/cm vs 7.0 ± 3.0 N/cm, p = 0.029). In primates, OviTex 1S-P exhibited loss of composite mesh integrity whereas Strattice integrated into host tissue with minimal inflammation and retained higher maximum load at 1 month than OviTex 1S-P (66.8 ± 43.4 N/cm vs 9.6 ± 4.4 N/cm; p = 0.151).

Strattice retained greater mechanical strength as shown by lower susceptibility to collagenase degradation than OviTex 2S-R in vitro, as well as higher maximum load and improved host biologic response than OviTex 2S-R in rodents and OviTex 1S-P in primates.

To compare the reoperation rate for recurrence between different mesh types in laparoscopic ventral hernia repair.

Ventral hernia repair has improved over the last decades. Nevertheless, recurrence rates are still high, and one type of mesh was recently found to increase it even more.

A nationwide cohort study based on prospectively collected data from the Danish Ventral Hernia Database. We included adult patients that had undergone a laparoscopic ventral hernia repair for either an incisional or a primary hernia. The primary and incisional hernias were analyzed in separate cohorts. The mesh-group with the lowest reoperation for recurrence curve was used as the reference. The outcome was reoperation for recurrence.

Study population comprised 2874 patients with primary hernias and 2726 with incisional hernias. For primary hernias, Physiomesh [HR = 3.45 (2.16-5.51)] and Proceed Surgical Mesh [HR = 2.53 (1.35-4.75)] had a significantly higher risk of reoperation for recurrence than DynaMesh-IPOM. For incisional hernias, Physiomesh [HR = 3.90 (1.80-8.46), Ventralex Hernia Patch (HR = 2.99 (1.13-7.93), Parietex Composite (incl. Optimized) (HR = 2.55 (1.17-5.55), and Proceed Surgical Mesh (HR = 2.63 (1.11-6.20)] all had a significantly higher risk of reoperation for recurrence than Ventralight ST Mesh.

For primary hernias, Physiomesh and Proceed Surgical Mesh had a significantly higher risk of reoperation for recurrence compared with DynaMesh-IPOM. For incisional hernias, the risk was significantly higher for Physiomesh, Parietex Composite, Ventralex Hernia Patch, and Proceed Surgical Mesh compared with Ventralight ST Mesh. This indicates that type of mesh may be associated with outcomes, and mesh choice could therefore depend on hernia type.

A randomized, controlled, prospective multicenter clinical trial with a parallel group design was initiated in eight surgical centers to compare a large-pore polypropylene mesh (Ultrapro®) to a small-pore polypropylene mesh (Premilene®) within a standardized retromuscular meshplasty for incisional hernia repair.

Between 2004 and 2006, patients with a fascial defect with a minimum diameter of 4 cm after vertical midline laparotomy were recruited for the trial. Patients underwent retromuscular meshplasty with either a large-pore or a small-pore mesh to identify the superiority of the large-pore mesh. Follow-up visits were scheduled at 5 and 21 days and 4, 12, and 24 months after surgery. A clinical examination, a modified short form 36 (SF-36®), a daily activity questionnaire, and an ultrasound investigation of the abdominal wall were completed at every follow-up visit. The primary outcome criterion was foreign body sensation at the 12-month visit, and the secondary endpoint criteria were the occurrence of hematoma, seroma, and chronic pain within 24 months postoperatively.

In 8 centers, 181 patients were included in the study. Neither foreign body sensation within the first year after surgery (27.5% Ultrapro®, 32.2% Premilene®) nor the time until the first occurrence of foreign body sensation within the first year was significantly different between the groups. Regarding the secondary endpoints, no significant differences could be observed. At the 2-year follow-up, recurrences occurred in 5 Ultrapro® patients (5.5%) and 4 Premilene® patients (4.4%).

Despite considerable differences in theoretical and experimental works, we have not been able to identify differences in surgical or patient-reported outcomes between the use of large- and small-pore meshes for retromuscular incisional hernia repair.

Clinical Trials NCT04961346 (16.06.2021) retrospectively registered.

Porous Nb-25Ta-25Ti alloys (60% porosity and 100-600 μm pore size) for bone implant applications were manufactured combining impregnation and sintering methods. Surfaces with porous micro-nanostructured networks on Nb-Ta-Ti alloys were successfully modified by various surface pre-treatments (acid etching, alkali-heat treatment and annealing treatment). Surface characteristics and Ca-P layer deposition behaviors of the multilevel structured porous Nb-Ta-Ti alloys were investigated by conducting various tests, including x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray, atomic force microscopy and optical contact angle measurement. In particular, bulk Nb-Ta-Ti alloys were also used as mutual control. The results demonstrated that the porous alloy exhibited a unique multilevel porous structure with macro-networks and micro-pits after pre-treatments. The surface passive TiO₂/Nb₂O₅/Ta₂O₅layers on Nb-Ta-Ti alloys were partially dissolved by the corrosive attack of hydroxyl ions during alkali heat treatment. In addition, subsequent annealing treatment increased the density of the gel layers formed during alkali heat treatment. After immersion in SBF for 14 d, a continuous relatively uniform apatite layer was formed on the multilevel structured surfaces. Moreover, the mechanism of surface mineralization can be construed as electrostatic interactions between substrates and ions. Furthermore,in vitrocell culture showed that Nb-Ta-Ti alloys had a good biocompatibility and the multilevel porous structure could enhance the cellular behaviors including: cell adhesion and spreading.

Additive Manufactured (AM) Polyether-ether-ketone (PEEK) orthopaedic implants offer new opportunities for bone substitutes. However, owing to its chemical inertness, the integration between PEEK implants and soft tissue represents a major challenge threatening the early success of the PEEK implants. Here we investigated the influence of hydroxyapatite (HA) fillers and porous structure of AM HA/PEEK scaffolds on the integration with soft tissue through in-vitro cellular experiments and in-vivo rabbit experiments. Among the animal experiments, HA/PEEK composite scaffolds with HA contents of 0, 20 wt%, 40 wt% and pore sizes of 0.8 mm, 1.6 mm were manufactured by fused filament fabrication. The results indicated that HA promoted the proliferation and adhesion of myofibroblasts on PEEK-based composites by releasing Ca²⁺ to active FAK and its downstream proteins, while the surface morphology of the scaffolds was also roughened by the HA particles, both of which led to the tighter adhesion between HA/PEEK scaffolds and soft tissue in-vivo. The macroscopic bonding force between soft tissue and scaffolds was dominated by the pore size of the scaffolds but was hardly affected by neither the HA content and nor the surface morphology. Scaffolds with larger pore size bonded more strongly to the soft tissue, and the maximum bonding force reached to 5.61 ± 2.55 N for 40 wt% HA/PEEK scaffolds with pore size of 1.6 mm, which was higher than that between natural bone and soft tissue of rabbits. Although the larger pore size and higher HA content of the PEEK-based scaffolds facilitated the bonding with the soft tissue, the consequent outcome of reduced mechanical properties has to be compromised in the design of the porous PEEK-based composite implants. The present study provides engineering-accessible synergistic strategies on material components and porous architecture of AM PEEK orthopaedic implants for improving the integration with soft tissue.

Healthcare-associated infections (HAIs) are a persistent clinical challenge caused primarily by bacteria on the skin. Proper utilization of optimized antiseptic skin preparation solutions helps reduce the prevalence and impact of HAIs by decreasing patient skin microorganisms preoperatively. The purpose of this study was to evaluate the efficacy of 2 antimicrobial solutions containing iodine and isopropyl alcohol (IPA): Povidone iodine (PVP-I) with IPA (ie, PVP-I+IPA, PurPrep) and Iodine Povacrylex+IPA (DuraPrep).

The antimicrobial activity of the test solutions was evaluated in vitro by determinations of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against 1105 diverse microbial isolates and a time-kill assay to evaluate efficacy against 120 strains of Gram-positive and Gram-negative bacteria and yeasts. Peel tests were performed between skin samples treated with test solutions and representative drape/dressing materials to determine effects of test solutions on the biomechanical adhesion properties. Finally, an Institutional Review Board (IRB)-approved, randomized, controlled, single-center, partially blinded in vivo study was performed to assess the immediate and persistent antimicrobial activity of the test solutions on the abdomen and groin.

Both PVP-I+IPA and Iodine Povacrylex+IPA solutions demonstrated broad-spectrum antimicrobial activity with MIC and MBC at less than 1% of the full-strength concentration of each product against a wide variety of microorganisms. In the time-kill tests, both solutions were able to successfully reduce all microbial populations by 99.99% (ie, 4 log₁₀) at the contact times of 30 seconds, 2 minutes and 10 minutes. The 2 solutions showed relatively similar adhesion results when tested with 3 representative operating room materials. Both PVP-I+IPA and Iodine Povacrylex+IPA met the expected Food and Drug Administration (FDA) efficacy requirements at 10 minutes and 6 hours post-treatment for both anatomic sites (ie, groin, and abdomen) in the clinical study, with no safety issues or adverse events.

Analysis of the in vitro antimicrobial activity, biomechanical adhesive strength, and in vivo efficacy of PVP-I+IPA demonstrated similar results compared to Iodine Povacrylex+IPA. Both products were efficacious at reducing or eliminating a wide range of clinically-relevant microorganisms in lab-based and clinical settings, supporting their use as antiseptic skin preparation solutions to reduce bacteria on the skin that can cause infection.

Proposed mechanisms that potentially contribute to polypropylene mesh degradation after in vivo exposure include oxidizing species and mechanical strains induced by normal healing, tissue integration, muscle contraction, and the immediate and chronic inflammatory responses.

This study explores these potential degradation mechanisms using 63 mesh implants retrieved from patients after a median implantation time of 24 months following hernia repair surgery (mesh explants) and analysis of multivariate associations between the material changes and clinical characteristics. Specifically, polypropylene mesh degradation was characterized in terms of material changes in surface oxidation, crystallinity and mechanical properties, and clinical characteristics included mesh placement location, medical history and mesh selection.

Compared to pristine control samples, subsets of mesh explants had evidence of surface oxidation, altered crystallinity, or changed mechanical properties. Using multivariate statistical approach to control for clinical characteristics, infection was a significant factor affecting changes in mesh stiffness and mesh class was a significant factor affecting polypropylene crystallinity changes.

Highly variable in vivo conditions expose mesh to mechanisms that alter clinical outcomes and potentially contribute to mesh degradation. These PP mesh explants after 0.5 to 13 years in vivo had measurable changes in surface chemistry, crystallinity and mechanical properties, with significant trends associated with factors of mesh placement, mesh class, and infection.

Hernia injuries are the main condition where mesh implants are needed to provide a suitable reinforcement of the damaged tissue. Mesh implants made of polypropylene (PP) are widely used for this application, however complications related to lack of flexibility, elasticity, and mesh infection have been reported. The development of mesh implants from safer materials adaptable to patient necessities can suppose an alternative for conventional PP meshes. In this work, personalized mesh implants made of alginate and waterborne-polyurethane (A-WBPU) are developed using 3D printing technology. For that purpose, five waterborne polyurethane ink formulations with different amounts of alginate are developed and rheologically characterized. All ink formulations are 3D printed showing good printability, manufacturing surgical mesh implants with suitable morphological characteristics customizable to patient injury through computer-aided design (CAD) mesh model adaptation. A calcium chloride (CaCl₂ ) coating is applied after 3D printing as mesh reinforcement. Mechanical analysis revealed that CaCl₂ coated meshes containing 6 wt % of alginate in their formulation are the most suitable to be used as implants for small and groin hernias under physiological tensile strength value of 16 N cm^-1 , and presenting proper elasticity to cover physiological corporal movements (42.57 %). Moreover, an antibiotic-loaded A-WBPU formulation suitable for 3D printing of meshes are developed as strategy to avoid possible mesh infection.

Throughout the past few years, hernia incidence has remained at a high level worldwide, with more than 20 million people requiring hernia surgery each year. Synthetic hernia meshes play an important role, providing a microenvironment that attracts and harbors host cells and acting as a permanent roadmap for intact abdominal wall reconstruction. Nevertheless, it is still inevitable to cause not-so-trivial complications, especially chronic pain and adhesion. In long-term studies, it was found that the complications are mainly caused by excessive fibrosis from the foreign body reaction (FBR) and infection resulting from bacterial colonization. For a thorough understanding of their complex mechanism and providing a richer background for mesh development, herein, we discuss different clinical mesh products and explore the interactions between their structure and complications. We further explored progress in reducing mesh complications to provide varied strategies that are informative and instructive for mesh modification in different research directions. We hope that this work will spur hernia mesh designers to step up their efforts to develop more practical and accessible meshes by improving the physical structure and chemical properties of meshes to combat the increasing risk of adhesions, infections, and inflammatory reactions. We conclude that further work is needed to solve this pressing problem, especially in the analysis and functionalization of mesh materials, provided of course that the initial performance of the mesh is guaranteed.

Urinary bladder is a dynamic organ performing complex physiological activities. Together with ureters and urethra, it forms the lower urinary tract that facilitates urine collection, low-pressure storage, and volitional voiding. However, pathological disorders are often liable to cause irreversible damage and compromise the normal functionality of the bladder, necessitating surgical intervention for a reconstructive procedure. Non-urinary autologous grafts, primarily derived from gastrointestinal tract, have long been the gold standard in clinics to augment or to replace the diseased bladder tissue. Unfortunately, such treatment strategy is commonly associated with several clinical complications. In absence of an optimal autologous therapy, a biomaterial based bioengineered platform is an attractive prospect revolutionizing the modern urology. Predictably, extensive investigative research has been carried out in pursuit of better urological biomaterials, that overcome the limitations of conventional gastrointestinal graft. Against the above backdrop, this review aims to provide a comprehensive and one-stop update on different biomaterial-based strategies that have been proposed and explored over the past 60 years to restore the dynamic function of the otherwise dysfunctional bladder tissue. Broadly, two unique perspectives of bladder tissue engineering and total alloplastic bladder replacement are critically discussed in terms of their status and progress. While the former is pivoted on scaffold mediated regenerative medicine; in contrast, the latter is directed towards the development of a biostable bladder prosthesis. Together, these routes share a common aspiration of designing and creating a functional equivalent of the bladder wall, albeit, using fundamentally different aspects of biocompatibility and clinical needs. Therefore, an attempt has been made to systematically analyze and summarize the evolution of various classes as well as generations of polymeric biomaterials in urology. Considerable emphasis has been laid on explaining the bioengineering methodologies, pre-clinical and clinical outcomes. Some of the unaddressed challenges, including vascularization, innervation, hollow 3D prototype fabrication and urinary encrustation, have been highlighted that currently delay the successful commercial translation. More importantly, the rapidly evolving and expanding concepts of bioelectronic medicine are discussed to inspire future research efforts towards the further advancement of the field. At the closure, crucial insights are provided to forge the biomaterial assisted reconstruction as a long-term therapeutic strategy in urological practice for patients' care.

Component separation (CS) procedures have become an important part of surgeons' armamentarium. However, the exact criteria for training, procedure/mesh choice, as well as patient selection for CS remains undefined. Herein we aimed to identify trends in CS utilization between various cohorts of practicing surgeons.

Members of the Americas Hernia Society were queried using an online survey. Responders were stratified according to their experience, practice profile (private vs academic, general vs hernia surgery), and volume (low (< 10/year) vs high) of CS procedures. We used Chi-squared tests to evaluate significant associations between surgeon characteristics and outcomes.

275 responses with overwhelming male preponderance (88%) were collected. The two most common self-identifiers were "general" (66%) and "hernia" (28%) surgeon. PCS was the most commonly (67%) used type of CS; endoscopic ACS was least common (3%). Low-volume surgeons were more likely to utilize the ACS (p < 0.05). Only 7% of respondents learned PCS during their residency, as compared to 36% that use ACS. 65% felt 0-10 cases was sufficient to become proficient in their preferred technique. 10 cm-wide defect was the most common indication for CS; 23% used it for 5-8 cm defects. Self-identified "hernia" and high-volume surgeons were more likely to use synthetic mesh in the setting of previous wound infections and/or contaminated field (p < 0.05). More general/low-volume surgeons use biologic mesh. Contraindications to elective CS varied widely in the cohort, and 9.5% would repair poorly optimized patients electively. Severe morbid obesity was the most feared comorbidity to preclude CS.

The use of CS varies widely between surgeons. In this cohort, we discovered that PCS was the most commonly used technique, especially by hernia/high-volume surgeons. There are differences in mesh utilization between high-volume and low-volume surgeons, specifically in contaminated fields. Despite its prevalence, CS training, indications/contraindications, and patient selection must be better defined.

Implants for the cure of female genital prolapse still show numerous complications cases that sometimes have dramatic consequences. These implants must be improved to provide physiological support and restore the normal functionalities of the pelvic area. Besides the trend towards lighter meshes, a better understanding of the in vivo role and impact of the mesh implantation is required. This work investigates the mechanical impact of meshes after implantation with regards to the behavior of the native tissues. Three meshes were studied to assess their mechanical and biological impact on the native tissues. An animal study was conducted on rats. Four groups (n = 17/group) underwent surgery. Rats were implanted on the abdominal wall with one of the three polypropylene knitted mesh (one mesh/group). The last group served as control and underwent the same surgery without any mesh implantation. Post-operative complications, contraction, mechanical rigidities, and residual deformation after cyclic loading were collected. Non-parametric statistical comparisons were performed (Kruskal-Wallis) to observe potential differences between implanted and control groups. Mechanical characterization showed that one of the three meshes did not alter the mechanical behavior of the native tissues. On the contrary, the two others drastically increased the rigidities and were also associated with clinical complications. All of the meshes seem to reduce the geometrical lengthening of the biological tissues that comes with repetitive loads. Mechanical aspects might play a key role in the compatibility of the mesh in vivo. One of the three materials that were implanted during an animal study seems to provide better support and adapt more properly to the physiological behavior of the native tissues.

Neointimal hyperplasia (NH) is a main source of failures in arteriovenous fistulas and vascular grafts. Several studies have demonstrated the promise of perivascular wraps to reduce NH via promotion of adventitial neovascularization and providing mechanical support. Limited clinical success thus far may be due to inappropriate material selection (e.g., nondegradable, too stiff) and geometric design (e.g., pore size and spacing, diameter). The influence of pore size and spacing on implant neovascularization is investigated here for a new biodegradable, thermoresponsive shape memory polymer (SMP) perivascular wrap. Following an initial pilot, 21 mice were each implanted with six scaffolds: four candidate SMP macroporous designs (a-d), a nonporous SMP control (e), and microporous GORETEX (f). Mice were sacrificed after 4 (N = 5), 14 (N = 8), and 28 (N = 8) days. There was a statistically significant increase in neovascularization score between all macroporous groups compared to nonporous SMP (p < .023) and microporous GORETEX (p < .007) controls at Day 28. Wider-spaced, smaller-sized pore designs (223 μm-spaced, 640 μm-diameter Design c) induced the most robust angiogenic response, with greater microvessel number (p < .0114) and area (p < .0055) than nonporous SMPs and GORETEX at Day 28. This design also produced significantly greater microvessel density than nonporous SMPs (p = 0.0028) and a smaller-spaced, larger-sized pore (155 μm-spaced, 1,180 μm-sized Design b) design (p = .0013). Strong neovascularization is expected to reduce NH, motivating further investigation of this SMP wrap with controlled pore spacing and size in more advanced arteriovenous models.

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.

Polymeric mesh implantation has become the golden standard in hernia repair, which nowadays is one of the most frequently performed surgeries in the world. However, many biocompatibility issues remain to be a concern for hernioplasty, with chronic pain being the most notable post-operative complication. Oxidative stress appears to be a major factor in the development of those complications. Lack of material inertness in vivo and oxidative environment formed by inflammatory cells result in both mesh deterioration and slowed healing process. In a pilot in vivo study, we prepared and characterized polypropylene hernia meshes with vitamin E (α-tocopherol)-a potent antioxidant. The results of that study supported the use of vitamin E as potential coating to alleviate post-surgical inflammation, but the pilot nature of the study yielded limited statistical data. The purpose of this study was to verify the observed trend of the pilot study statistically.

In this work, we conducted a 5-animal experiment where we have implanted vitamin E-coated and uncoated control meshes into the abdominal walls of rabbits. Histology of the mesh-adjacent tissues and electron microscopy of the explanted mesh surface were conducted to characterize host tissue response to the implanted meshes.

As expected, modified meshes exhibited reduced foreign body reaction, as evidenced by histological scores for fatty infiltrates, macrophages, neovascularization, and collagen organization, as well as by the surface deterioration of the meshes.

In conclusion, results indicate that vitamin E coating reduces inflammatory response following hernioplasty and protects mesh material from oxidative deterioration.

Wound healing is a complex cellular and biochemical process and can be affected by several systemic and local factors. In this study, we aimed to discuss the aetiologic factors of non-healing wounds and the management of this complicated process with current information. The medical data of the patients who were admitted to our clinic due to non-healing or chronic wounds were analysed retrospectively. A total of 27 patients were evaluated retrospectively during the 14 months of the study. The data of 6 patients who were followed up for chronic wound that developed after abdominal incisional hernia repair and pilonidal sinus surgery were not included in the study as their data could not be reached. A total of 21 patients were included in the study. Malignancy was diagnosed in two patients and granulomatous disease was found in four patients. The aetiology of the other cases included foreign body reaction, infection, and mechanical causes. Non-healing wounds are a serious social and economic problem for patients. Further studies on the pathophysiology of various aetiologies in non-healing wounds in both clinical settings and experimental animal models would be a useful step in treatment.

Low in macro-porosity electro-spun scaffolds are often associated with foreign body response, whilst macro-porous electro-spun scaffolds have low mechanical integrity. Herein, compressed, macro-porous and collagen (bovine Achilles tendon and human recombinant) coated electro-spun poly-ε-caprolactone scaffolds were developed and their biomechanical, in vitro and in vivo properties were assessed. Collagen coating, independently of the source, did not significantly affect the biomechanical properties of the scaffolds. Although no significant difference in cell viability was observed between the groups, collagen coated scaffolds induced significantly higher DNA concentration. In vivo, no signs of adverse tissue effect were observed in any of the groups and all groups appeared to equally integrate into the subcutaneous tissue. It is evidenced that macro-porous poly-ε-caprolactone electro-spun meshes with adequate mechanical properties and acceptable host response can be developed for biomedical applications.

Transversus abdominis muscle release (TAR) combines retromuscular mesh placement with posterior component separation and muscle release. TAR is usually an open technique for abdominal wall reconstruction; however, several centers have performed this operation robotically and claim better clinical outcomes when compared to open surgery. We sought to compare robotic versus open TAR utilizing a porcine model.

Animals were randomized to open versus robotic TAR with mesh placement, survived for 4 weeks, then underwent diagnostic laparoscopy to assess adhesive burden and adhesion tenacity. T-peel testing was utilized to assess mesh ingrowth. The primary outcome was adhesive burden; secondary outcomes included mesh incorporation, contraction, and operative time.

Nine robotic and eight open TARs were performed. Mean operative time was significantly shorter for the open cases compared to robotic cases (88.6 ± 12.9 min versus 228.3 ± 46.2, p < 0.01). Operative time in the robotic arm of the study decreased over time, from 300 to 165 min. No difference was seen in the mean adhesion area between the two groups. Adhesion tenacity and mesh flatness were similar. The work required to peel the mesh off surrounding tissue was significantly higher in the open TAR than in the robotic TAR group: 52.6 ± 15.5 and 32.9 ± 10.6 mJ/cm2, respectively (p < 0.01).

There were no differences in adhesions between the robotic and open approaches, but greater mesh contraction and ingrowth was observed in the open TAR group. Though operative time was longer in the robotic group, time dropped by about 40% from the first case to the last.

Polypropylene meshes that are commonly used for inguinal hernia repair may trigger granulomatous foreign body reactions. Here, we show that asymptomatic patients display mesh-associated inflammatory granulomas long after surgery, which are dominated by monocyte-derived macrophages expressing high levels of inflammatory activation markers. In mice, mesh implantation by the onlay technique induced rapid and strong myeloid cell accumulation, without substantial attenuation for up to 90 days. Myeloid cells segregated into distinct macrophage subsets with separate spatial distribution, activation profiles, and functional properties, showing a stable inflammatory phenotype in the tissue surrounding the biomaterial and a mixed, wound-healing phenotype in the surrounding stromal tissue. Protein mass spectrometry confirmed the inflammatory nature of the foreign body reaction, as characterized by cytokines, complement activation, and matrix-modulating factors. Moreover, immunoglobulin deposition increased over time around the implant, arguing for humoral immune responses in association with the cell-driven inflammation. Intravital multiphoton microscopy revealed a high motility and continuous recruitment of myeloid cells, which is partly dependent on the chemokine receptor CCR2. CCR2-dependent macrophages are particular drivers of fibroblast proliferation. Thus, our work functionally characterizes myeloid cell-dependent inflammation following mesh implantation, thereby providing insights into the dynamics and mechanisms of foreign body reactions to implanted biomaterials.

The nano-fibrous architecture of electro-spun meshes favours their use in biomedicine, but their low mechanical properties prohibit their wide use in clinical practice. Introduction of porosity, essential of tissue integration, decreases further mechanical integrity. Herein, we hypothesised that macro-porous electro-spun meshes with adequate mechanical properties can be fabricated through layering and subsequent compression. Two and three layers electro-spun poly-ε-caprolactone scaffolds were fabricated, compressed and subsequently 30% circular porosity was introduced through laser cutting. Three-layered porous electro-spun meshes exhibited mechanical properties similar to commercially available scaffolds without any structural or cytotoxic effect. This study brings electro-spun materials closer to clinical translation and commercialisation.

Introduction: This study looks at the outcome of 352 patients that underwent the "Manchester groin repair" in the period from 2007 to 2016. The effect of laterality on chronic groin pain and the reduction of pain scores post-surgery are evaluated as well as the rate of hernia recurrence for the inguinal hernia repairs. Methods: The "Manchester groin repair" is a modification of a laparoscopic totally extra-peritoneal approach with fibrin sealant mesh fixation. Data were collected prospectively. In addition to demographic data and the European Hernia Society classification grading of each hernia, pain scores were assessed prior to surgery and at 4-6 weeks post-operatively using a ten-point visual analog pain scale. Data were collected on a bespoke database and differences between time-points analyzed by non-parametric Wilcoxon signed rank tests with Kruskal-Wallis rank sum test for three-group comparisons. Significance was at the P < 0.05 level. The study was undertaken as an institutional audit. Results: Three hundred and fifty two patients underwent TEP repair as per the "Manchester Groin Repair" modification during the period of interest with a median follow-up period of 109.5 (IQR 57.0-318.5) weeks. Of these 274 (77.8%) were for the repair of true hernias and 78 (22.2%) were for inguinal disruptions. All inguinal hernia repairs patients were evaluated (254 m, 20 f); median [interquartile range] age 50 (39-65) years. There were 75 right inguinal hernias (27.4%), 39 Left inguinal hernias (14.2%), and 160 bilateral inguinal hernias (58.4%), giving a total of 434 hernia repairs. During follow-up there were 6 recurrences (1.4%).Of the 274 patients evaluated, 145 (52.9%) had both pre and post-operative pain scores available. Median pre-operative pain score was 5 [IQR 4-7]. Median post-operative pain score was 1 [IQR 1-2]. This difference was significant (P < 0.001). Pre-operative pain scores were higher for those with a bilateral hernia (median 6 vs. 5 and 4, respectively; P = 0.005), but there was no difference in post-operative scores (P = 0.347). One patient (0.3%) presented with chronic groin pain (pain after 3 months). Conclusion: This study demonstrates that the "Manchester groin repair" provides an excellent repair with a low rate of recurrence and low incidence of chronic pain. Longer-term evaluation and larger patient series will add to the understanding of the role of this procedure in groin hernia repair.

Worldwide, more than 20 million patients undergo groin hernia repair annually. The many different approaches, treatment indications and a significant array of techniques for groin hernia repair warrant guidelines to standardize care, minimize complications, and improve results. The main goal of these guidelines is to improve patient outcomes, specifically to decrease recurrence rates and reduce chronic pain, the most frequent problems following groin hernia repair. They have been endorsed by all five continental hernia societies, the International Endo Hernia Society and the European Association for Endoscopic Surgery.

An expert group of international surgeons (the HerniaSurge Group) and one anesthesiologist pain expert was formed. The group consisted of members from all continents with specific experience in hernia-related research. Care was taken to include surgeons who perform different types of repair and had preferably performed research on groin hernia surgery. During the Group's first meeting, evidence-based medicine (EBM) training occurred and 166 key questions (KQ) were formulated. EBM rules were followed in complete literature searches (including a complete search by The Dutch Cochrane database) to January 1, 2015 and to July 1, 2015 for level 1 publications. The articles were scored by teams of two or three according to Oxford, SIGN and Grade methodologies. During five 2-day meetings, results were discussed with the working group members leading to 136 statements and 88 recommendations. Recommendations were graded as "strong" (recommendations) or "weak" (suggestions) and by consensus in some cases upgraded. In the Results and summary section below, the term "should" refers to a recommendation. The AGREE II instrument was used to validate the guidelines. An external review was performed by three international experts. They recommended the guidelines with high scores. The risk factors for inguinal hernia (IH) include: family history, previous contra-lateral hernia, male gender, age, abnormal collagen metabolism, prostatectomy, and low body mass index. Peri-operative risk factors for recurrence include poor surgical techniques, low surgical volumes, surgical inexperience and local anesthesia. These should be considered when treating IH patients. IH diagnosis can be confirmed by physical examination alone in the vast majority of patients with appropriate signs and symptoms. Rarely, ultrasound is necessary. Less commonly still, a dynamic MRI or CT scan or herniography may be needed. The EHS classification system is suggested to stratify IH patients for tailored treatment, research and audit. Symptomatic groin hernias should be treated surgically. Asymptomatic or minimally symptomatic male IH patients may be managed with "watchful waiting" since their risk of hernia-related emergencies is low. The majority of these individuals will eventually require surgery; therefore, surgical risks and the watchful waiting strategy should be discussed with patients. Surgical treatment should be tailored to the surgeon's expertise, patient- and hernia-related characteristics and local/national resources. Furthermore, patient health-related, life style and social factors should all influence the shared decision-making process leading up to hernia management. Mesh repair is recommended as first choice, either by an open procedure or a laparo-endoscopic repair technique. One standard repair technique for all groin hernias does not exist. It is recommended that surgeons/surgical services provide both anterior and posterior approach options. Lichtenstein and laparo-endoscopic repair are best evaluated. Many other techniques need further evaluation. Provided that resources and expertise are available, laparo-endoscopic techniques have faster recovery times, lower chronic pain risk and are cost effective. There is discussion concerning laparo-endoscopic management of potential bilateral hernias (occult hernia issue). After patient consent, during TAPP, the contra-lateral side should be inspected. This is not suggested during unilateral TEP repair. After appropriate discussions with patients concerning results tissue repair (first choice is the Shouldice technique) can be offered. Day surgery is recommended for the majority of groin hernia repair provided aftercare is organized. Surgeons should be aware of the intrinsic characteristics of the meshes they use. Use of so-called low-weight mesh may have slight short-term benefits like reduced postoperative pain and shorter convalescence, but are not associated with better longer-term outcomes like recurrence and chronic pain. Mesh selection on weight alone is not recommended. The incidence of erosion seems higher with plug versus flat mesh. It is suggested not to use plug repair techniques. The use of other implants to replace the standard flat mesh in the Lichtenstein technique is currently not recommended. In almost all cases, mesh fixation in TEP is unnecessary. In both TEP and TAPP it is recommended to fix mesh in M3 hernias (large medial) to reduce recurrence risk. Antibiotic prophylaxis in average-risk patients in low-risk environments is not recommended in open surgery. In laparo-endoscopic repair it is never recommended. Local anesthesia in open repair has many advantages, and its use is recommended provided the surgeon is experienced in this technique. General anesthesia is suggested over regional in patients aged 65 and older as it might be associated with fewer complications like myocardial infarction, pneumonia and thromboembolism. Perioperative field blocks and/or subfascial/subcutaneous infiltrations are recommended in all cases of open repair. Patients are recommended to resume normal activities without restrictions as soon as they feel comfortable. Provided expertise is available, it is suggested that women with groin hernias undergo laparo-endoscopic repair in order to decrease the risk of chronic pain and avoid missing a femoral hernia. Watchful waiting is suggested in pregnant women as groin swelling most often consists of self-limited round ligament varicosities. Timely mesh repair by a laparo-endoscopic approach is suggested for femoral hernias provided expertise is available. All complications of groin hernia management are discussed in an extensive chapter on the topic. Overall, the incidence of clinically significant chronic pain is in the 10-12% range, decreasing over time. Debilitating chronic pain affecting normal daily activities or work ranges from 0.5 to 6%. Chronic postoperative inguinal pain (CPIP) is defined as bothersome moderate pain impacting daily activities lasting at least 3 months postoperatively and decreasing over time. CPIP risk factors include: young age, female gender, high preoperative pain, early high postoperative pain, recurrent hernia and open repair. For CPIP the focus should be on nerve recognition in open surgery and, in selected cases, prophylactic pragmatic nerve resection (planned resection is not suggested). It is suggested that CPIP management be performed by multi-disciplinary teams. It is also suggested that CPIP be managed by a combination of pharmacological and interventional measures and, if this is unsuccessful, followed by, in selected cases (triple) neurectomy and (in selected cases) mesh removal. For recurrent hernia after anterior repair, posterior repair is recommended. If recurrence occurs after a posterior repair, an anterior repair is recommended. After a failed anterior and posterior approach, management by a specialist hernia surgeon is recommended. Risk factors for hernia incarceration/strangulation include: female gender, femoral hernia and a history of hospitalization related to groin hernia. It is suggested that treatment of emergencies be tailored according to patient- and hernia-related factors, local expertise and resources. Learning curves vary between different techniques. Probably about 100 supervised laparo-endoscopic repairs are needed to achieve the same results as open mesh surgery like Lichtenstein. It is suggested that case load per surgeon is more important than center volume. It is recommended that minimum requirements be developed to certify individuals as expert hernia surgeon. The same is true for the designation "Hernia Center". From a cost-effectiveness perspective, day-case laparoscopic IH repair with minimal use of disposables is recommended. The development and implementation of national groin hernia registries in every country (or region, in the case of small country populations) is suggested. They should include patient follow-up data and account for local healthcare structures. A dissemination and implementation plan of the guidelines will be developed by global (HerniaSurge), regional (international societies) and local (national chapters) initiatives through internet websites, social media and smartphone apps. An overarching plan to improve access to safe IH surgery in low-resource settings (LRSs) is needed. It is suggested that this plan contains simple guidelines and a sustainability strategy, independent of international aid. It is suggested that in LRSs the focus be on performing high-volume Lichtenstein repair under local anesthesia using low-cost mesh. Three chapters discuss future research, guidelines for general practitioners and guidelines for patients.

The HerniaSurge Group has developed these extensive and inclusive guidelines for the management of adult groin hernia patients. It is hoped that they will lead to better outcomes for groin hernia patients wherever they live. More knowledge, better training, national audit and specialization in groin hernia management will standardize care for these patients, lead to more effective and efficient healthcare and provide direction for future research.

Ventral hernia repairs are common and have high recurrence rates. They are usually repaired laparoscopically with an intraperitoneal mesh, which can be fixed in various ways. The aim was to evaluate the recurrence rates for the different fixation techniques.

This systematic review included studies with human adults with a ventral hernia repaired with an intraperitoneal onlay mesh. The outcome was recurrence at least 6 months after operation. Cohort studies with 50 or more participants and all RCTs were included. PubMed, Embase and the Cochrane Library were searched on 22 September 2016. RCTs were assessed with the Cochrane risk-of-bias assessment tool and cohort studies with the Newcastle-Ottawa scale. Studies comparing fixation techniques were included in a network meta-analysis, which allowed comparison of more than two fixation techniques.

Fifty-one studies with a total of 6553 participants were included. The overall crude recurrence rates with the various fixation techniques were: absorbable tacks, 17·5 per cent (2 treatment groups); absorbable tacks with sutures, 0·7 per cent (3); permanent tacks, 7·7 per cent (20); permanent tacks with sutures, 6·0 per cent (25); and sutures, 1·5 per cent (6). Six studies were included in a network meta-analysis, which favoured fixation with sutures. Although statistical significance was not achieved, there was a 93 per cent chance of sutures being better than one of the other methods.

Both crude recurrence rates and the network meta-analysis favoured fixation with sutures during laparoscopic ventral hernia repair.

With an array of hernia meshes with varying properties, intraoperative decision making for the optimal mesh is critical. Although meshes are subjected to regulatory review through the Food and Drug Administration, it is unknown whether mesh properties are visually accessible. To facilitate greater knowledge for the surgeon on mesh choice, we aimed to comprehensively analyze hernia mesh packaging and regulations.

Labeling guidelines and 510(k) requirements across Food and Drug Administration-regulated products were analyzed and compared with mesh packaging. Packages and Instructions for Use were analyzed for commonly available hernia meshes. Literature review was conducted to understand recommended guidelines for mesh products. A novel hernia mesh packaging label was designed to rectify under-reporting.

We found that food labels undergo critical scrutiny and detailed specifications, yet medical devices are not subjected to similar guidelines. The highest reported property on packages was the presence of a barrier (80%), and the lowest reported property was barrier composition (33%). For Instructions for Use, the lowest reported properties were mechanics (31%) and thickness (11%), both of which were not reported on packaging. Descriptive terms for pore size and mechanics were reported inconsistently. To overcome this under-reporting of properties, we propose a novel packaging label with properties chosen from regulatory guidelines, packaging analysis, and literature review.

Although standardized terminology has been proposed in literature, property knowledge has not adequately permeated surgery, industry, or regulatory guidelines. There is extreme under-reporting and lack of consistency of clinically important mesh properties. Standardized packaging labels will provide accessibility of these properties and aim to bring standardized terminology into practice. With an increase in access to important properties, this can facilitate intraoperative decision making on a case-by-case basis.

In this report, we review the use of the New Zealand White rabbit as the experimental animal for several models of abdominal wall repair. For the repair of an abdominal wall defect, such as a hernia in clinical practice, multiple types of prosthetic material exist. Before their marketing, each of these biomaterials needs to be tested in a preclinical setting to confirm its biocompatibility and appropriate behavior at the different tissue interfaces. For preclinical trials, we have always used the New Zealand White rabbit as the model owing to its ease of handling and suitable size. This size allows for laparoscopic studies designed to follow the behavior in real time of a biomaterial implanted at the peritoneal interface, a delicate interface that often gives rise to complications in human practice. The size of the rabbit also offers a sufficiently large number of implant samples to be harvested for a complete battery of tests at several time points postimplant. In this review, we first describe the models established and then provide the results obtained so far using these models to test the different types of biomaterial. We end our review with a discussion of the clinical implications of these results.

The frequency of laparoscopic approaches increased in hernia surgery over the past years. After mesh placement in IPOM position, the real extent of the meshes configurational changes after termination of pneumoperitoneum is still largely unknown. To prevent a later mesh folding it might be useful to place the mesh while it is kept under tension. Conventionally used meshes may lose their Effective Porosity under these conditions due to poor elastic properties. The aim of this study was to evaluate a newly developed elastic thermoplastic polyurethane (TPU) containing mesh that retains its Effective Porosity under mechanical strain in IPOM position in a porcine model. It was visualized under pneumoperitoneum using MRI in comparison to polyvinylidenefluoride (PVDF) meshes with similar structure.

In each of ten minipigs, a mesh (TPU containing or native PVDF, 10 × 20 cm) was randomly placed in IPOM position at the center of the abdominal wall. After 8 weeks, six pigs underwent MRI evaluation with and without pneumoperitoneum to assess the visibility and elasticity of the mesh. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. The degree of adhesion formation was documented.

Laparoscopic implantation of elastic TPU meshes in IPOM position was feasible and safe in a minipig model. Mesh position could be precisely visualized and assessed with and without pneumoperitoneum using MRI after 8 weeks. Elastic TPU meshes showed a significantly higher surface increase under pneumoperitoneum in comparison to PVDF. Immunohistochemically, the amount of CD45-positive cells was significantly lower and the Collagen I/III ratio was significantly higher in TPU meshes after 8 weeks. There were no differences regarding adhesion formation between study groups.

The TPU mesh preserves its elastic properties in IPOM position in a porcine model after 8 weeks. Immunohistochemistry indicates superior biocompatibility regarding CD45-positive cells and Collagen I/III ratio in comparison to PVDF meshes with a similar structure.

The study investigated the effect of collagen mesh-assisted closure at the donor site in preventing the formation of incisional hernia following construction of a vertical rectus abdominis myocutaneus (VRAM) flap as part of pelvic surgery for recurrent colorectal cancer.

The study was a double-blinded randomized controlled superiority trial that was designed and performed according to the Consolidated Standards of Reporting Trials (CONSORT) Statement. Eligible patients undergoing surgery that included a VRAM flap for advanced colorectal pelvic malignancy were prospectively randomized to conventional abdominal wound closure or collagen mesh-assisted closure. The primary end-point was incisional herniation at 1 year confirmed by CT. Secondary end-points were CT-verified incisional herniation at 3 and 36 months, clinically recognizable incisional herniation, donor-site and reconstructive-site complications, surgical mortality, postoperative morbidity, postoperative recovery and survival.

In total, 58 (29 conventional closure; 29 mesh-assisted closure) patients were included. At 1 year, incisional herniation on the CT scan was found in 12 (50%) of 24 patients in the conventional closure group, and in 8 (33%) of 24 in the mesh-assisted closure group (P = 0.38). No significant difference between the groups was found in surgical mortality, early or late complications or survival. Donor-site morbidity was comparable between the two groups.

No preventative effect of collagen mesh-assisted closure was observed following VRAM flap reconstruction.