Shape-Configurable Mesh for Hernia Repair by Synchronizing Anisotropic Body Motion

Continuous progress has been made in elucidating the relationship between material property, device design, and body function to develop surgical meshes. However, an unmet need still exists wherein the surgical mesh can handle the body motion and thereby promote the repair process. Here, the hernia mesh design and the advanced polymer properties are tailored to synchronize with the anisotropic abdominal motion through shape configuration. The thermomechanical property of shape configurable polymer enables molding of mesh shape to fit onto the abdominal structure upon temperature shift, followed by shape fixing with the release of the heat energy. The microstructural design of mesh is produced through finite element modeling to handle the abdominal motion efficiently through the anisotropic longitudinal and transverse directions. The design effects are validated through in vitro, ex vivo, and in vivo mechanical analyses using a self-configurable, body motion responsive (BMR) mesh. The regenerative function of BMR mesh leads to effective repair in a rat hernioplasty model by effectively handling the anisotropic abdomen motion. Subsequently, the device-tissue integration is promoted by promoting healthy collagen synthesis with fibroblast-to-myofibroblast differentiation. This study suggests a potential solution to promote hernia repair by fine-tuning the relationship between material property and mesh design.

Characterization and in vivo evaluation of a fabricated absorbable poly(vinyl alcohol)-based hernia mesh

The most widely taken medical approach toward hernia repair involves the implementation of a prosthetic mesh to cover the herniated site and reinforce the weakened area of the abdominal wall. Biodegradable meshes can serve as biocompatible grafts with a low risk of infection. However, their major complication is associated with a high rate of degradation and hernia recurrence. We proposed a facile and cost-effective method to fabricate a poly(vinyl alcohol)-based mesh, using the solution casting technique. The inclusion of zinc oxide nanoparticles, citric acid, and three cycles of freeze-thaw were intended to ameliorate the mechanical properties of poly(vinyl alcohol). Several characterization, cell culture, and animal studies were conducted. Swelling and water contact angle measurements confirmed good water uptake capacity and wetting behavior of the final mesh sample. The synthesized mesh acquired a high mechanical strength of 52.8 MPa, and its weight loss was decreased to 39 %. No cytotoxicity was found in all samples. In vivo experiments revealed that less adhesion and granuloma formation, greater tissue integration, and notably higher neovascularization rate were resulted from implanting this fabricated hernia mesh, compared to commercial Prolene® mesh. Furthermore, the amount of collagen deposition and influential growth factors were enhanced when rats were treated with the proposed mesh instead of Prolene®.

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.

A Novel Bio-Adhesive Mesh System for Medical Implant Applications: In Vivo Assessment in a Rabbit Model

Injectable surgical sealants and adhesives, such as biologically derived fibrin gels and synthetic hydrogels, are widely used in medical products. While such products adequately adhere to blood proteins and tissue amines, they have poor adhesion with polymer biomaterials used in medical implants. To address these shortcomings, we developed a novel bio-adhesive mesh system utilizing the combined application of two patented technologies: a bifunctional poloxamine hydrogel adhesive and a surface modification technique that provides a poly-glycidyl methacrylate (PGMA) layer grafted with human serum albumin (HSA) to form a highly adhesive protein surface on polymer biomaterials. Our initial in vitro tests confirmed significantly improved adhesive strength for PGMA/HSA grafted polypropylene mesh fixed with the hydrogel adhesive compared to unmodified mesh. Toward the development of our bio-adhesive mesh system for abdominal hernia repair, we evaluated its surgical utility and in vivo performance in a rabbit model with retromuscular repair mimicking the totally extra-peritoneal surgical technique used in humans. We assessed mesh slippage/contraction using gross assessment and imaging, mesh fixation using tensile mechanical testing, and biocompatibility using histology. Compared to polypropylene mesh fixed with fibrin sealant, our bio-adhesive mesh system exhibited superior fixation without the gross bunching or distortion that was observed in the majority (80%) of the fibrin-fixed polypropylene mesh. This was evidenced by tissue integration within the bio-adhesive mesh pores after 42 days of implantation and adhesive strength sufficient to withstand the physiological forces expected in hernia repair applications. These results support the combined use of PGMA/HSA grafted polypropylene and bifunctional poloxamine hydrogel adhesive for medical implant applications.

Evaluating the Role of Glove Changing Before Mesh Application During Herniorrhaphy Surgery to Reduce Surgical Site Infections

Background: Prevention of surgical site infection (SSI) in hernia repair with mesh remains the main concern. Many risk factors have been proposed; however, the role of changing the glove remains to be elucidated. Methods: This longitudinal study was conducted on adult inguinal hernia cases referred to elective repair using mesh reconstruction. Two hundred cases were enrolled and classified into two groups, including the group that surgeon and his assistants changed the glove and the group in which the gloves remained unchanged. Age, gender, surgery duration, and the side of hernia were compared between those who developed SSI and those without this complication. Moreover, the infection rate was compared between the two study groups. Results: One hundred and two males (51.0%) and 98 females (49.0%) with a mean age of 42.60 ± 15.79 years old were enrolled in the study. None of the variables showed a significant difference between SSI cases and non-SSI cases. Moreover, the rate of infection was not significantly different between the two study groups. Conclusions: Glove changing before mesh application indicates no considerable role in reducing SSI rate; however, further studies are needed to confirm these findings.

New Insights into the Application of 3D-Printing Technology in Hernia Repair

Abdominal hernia repair using prosthetic materials is among the surgical interventions most widely performed worldwide. These materials, or meshes, are implanted to close the hernial defect, reinforcing the abdominal muscles and reestablishing mechanical functionality of the wall. Meshes for hernia repair are made of synthetic or biological materials exhibiting multiple shapes and configurations. Despite the myriad of devices currently marketed, the search for the ideal mesh continues as, thus far, no device offers optimal tissue repair and restored mechanical performance while minimizing postoperative complications. Additive manufacturing, or 3D-printing, has great potential for biomedical applications. Over the years, different biomaterials with advanced features have been successfully manufactured via 3D-printing for the repair of hard and soft tissues. This technological improvement is of high clinical relevance and paves the way to produce next-generation devices tailored to suit each individual patient. This review focuses on the state of the art and applications of 3D-printing technology for the manufacture of synthetic meshes. We highlight the latest approaches aimed at developing improved bioactive materials (e.g., optimizing antibacterial performance, drug release, or device opacity for contrast imaging). Challenges, limitations, and future perspectives are discussed, offering a comprehensive scenario for the applicability of 3D-printing in hernia repair.

Imaging and Treatment of Complications of Abdominal and Pelvic Mesh Repair

Surgical mesh is used most frequently for tension-free repair of abdominal wall hernias in adults, because the rate of hernia recurrence is lower with mesh than with primary soft-tissue repair. Since the introduction of polypropylene mesh in the middle of the 20th century, many mesh materials and configurations for specific surgical procedures have been developed. In addition to abdominal wall hernia repair, mesh may be used for repair of diaphragmatic hernias, urinary incontinence in women (female slings), genitourinary prolapse (vaginal mesh and sacrocolpopexy), rectal prolapse (rectopexy), and postprostatectomy male urinary incontinence (male slings). General mesh repair complications include chronic pain; fluid collections such as seromas, hematomas, and abscesses; adhesions that may lead to intestinal blockage; erosion into solid or hollow viscera including enterocutaneous fistulizing disease; and mesh failure characterized by mesh shrinkage, detachment, and migration with repair malfunction. Several mesh complications are often diagnosed with imaging, primarily with CT and less frequently with MRI and US, despite variable mesh visibility at imaging. This article reviews the common surgical mesh applications in the abdomen and pelvis, discusses imaging of mesh repair complications, and provides complication treatment highlights.^©RSNA, 2020.

Developing a Hernia Mesh Tissue Integration Index Using a Porcine Model-A Pilot Study

Introduction: With so many prosthetics available, it can be difficult for surgeons to choose the most appropriate hernia mesh. Successful hernia repair mandates an understanding of how the patient's inflammatory response influences surgical outcomes. Failure to appreciate the importance of the biological aspect of hernia repair can be very costly as emerging evidence supports that biofilm formation and reduction in effective mesh porosity gives rise to long-term mesh complications including fibrosis, chronic mesh infection, and pain. In this pilot study, we utilized a large animal (porcine) model to develop a numerical Mesh Tissue Integration (MTI) Index focused on visible tissue ingrowth, fibrosis, adhesion formation and resorption of mesh. The aim is to help surgeons adopt an evidence-based approach in selecting the most appropriate mesh according to its tissue ingrowth characteristics, matched to the patient to achieve improved surgical outcomes and optimal patient-centered care.

Methods: Two forty kg female Landrace pigs were recruited for this pilot study. A total of eight commonly used hernia mesh products and two controls measuring 5 × 5cm were surgically implanted in subrectus and intraperitoneal planes. The pigs were euthanised at 2 and 4 weeks, respectively. The abdominal wall was explanted, and the mesh specimens underwent macroscopic, histologic and biomechanical analysis, with engineering and pathology teams blinded to the mesh.

Results: Significant differences between the degrees of MTI were observed at 2 weeks and the distinctions were even more apparent at 4 weeks. One of the interesting incidental findings we observed is that mesh products placed in the subrectus plane displayed greater degrees of adhesion strength and integration than those placed intraperitoneally.

Conclusion: This pilot study is one of the first to propose a functional, biological standardized model for comparing hernia mesh products. The results are encouraging and demonstrate that this is a robust and transferrable model for assessing MTI in hernia mesh. The intention for this model is that it will be utilized synergistically with long term mesh/patient outcome registries and databases to inform improved matching of mesh to patient, particularly in the setting of the complex hernia repair and abdominal wall reconstruction.

Two Polyurethane Adhesives for PVDF Fixation Show Superior Biocompatibility in a Rat Model

BACKGROUND

The current standard for open and laparoscopic repair of incisional hernia consist of an abdominal wall augmentation by mesh implantation. However, the ideal fixation method of the prothesis material remains under discussion, due to potential complications of conventional fixation methods such as chronic abdominal pain or intestinal obstruction. As the use of adhesive based mesh fixation is an option of growing interest, the aim of this experimental study was to investigate the strength and biocompatibility of two newly developed polyurethane-based adhesives in comparison to a cyanoacrylatic adhesive, which is currently in clinical use.

METHODS

Two experimental polyurethane/urea-based adhesives (Adhesive-A and Adhesive-B) were compared to a conventional cyanoacrylatic adhesive and an untreated control group. Biomechanical testing was carried out using a pull-out test in uniaxial tensile mode, while biocompatibility assessment was performed in a rat model with 40 Sprague-Dawley rats receiving a subcutaneous implanted PVDF mesh fixed by the corresponding adhesive. Histological and immunohistochemical analysis by a Tissue FAXS system examined the tissue integration of the mesh/adhesive combination and characterized the foreign body reaction.

RESULTS

Biomechanical testing of the mesh/adhesive combinations showed a minimal strength of 15.08 N without a significant difference between the groups. Cellular penetration into the mesh/adhesive interface was significantly improved after application of polyurethane adhesives and Adhesive-A showed a significantly lower migration of CD68 positive cells to the adhesive sites compared to cyanoacrylate after 7 days.

CONCLUSION

The developed polyurethane-based adhesives are a promising alternative with sufficient adhesive strength and superior short-term biocompatibility to cyanoacrylate.

Patient perceptions on mesh use in hernia repair: A prospective, questionnaire-based study

BACKGROUND

There has been increasing media coverage regarding the controversy of using mesh in various operations. At this time, there are no published studies evaluating the potential influence of this controversy on patients' perceptions. Therefore, our study aimed to assess patient perceptions of hernia repair surgery with mesh as well as factors that may influence patient opinions.

METHODS

A 16-item questionnaire evaluated each patient's perceptions of the use of mesh in their upcoming hernia repair. The primary outcomes of interest were their level of comfort regarding the possibility of hernia repair surgery with mesh, aversion to hernia surgery with mesh, and positive belief that mesh is a safe product in hernia repair surgery.

RESULTS

We included 100 patients presenting for a hernia repair and 100 patients presenting for other operations. Both groups identified the media as their most common influence (37% and 40%, respectively). Factors leading to a high level of comfort regarding the possibility of mesh repair included believing mesh was a safe product (P < .001) and hearing about the advantages of mesh (P = .012) from medical professionals (P = .001). Factors leading to a positive belief that mesh was a safe product included the male sex (P = .015), a high socioeconomic standing (P = .006), and their own personal experience (P = .013). Factors leading to aversion to mesh use included the female sex (P = .006) and hearing about meshes causing mesh-related (P = .028) and wound-related complications (P = .025) as well as chronic pain (.008).

CONCLUSION

Despite the high penetration of non-medical information in the population before presentation for medical care, most patients overall do not seem to be opposed to the concept of the use of mesh in a hernia repair, but there are certain factors associated with aversion to the use of mesh that physicians should acknowledge and should address this potential issue.

Physicochemical characterization of barrier membranes for bone regeneration

Barrier membranes are essential biomaterials for guided bone regeneration. Due to different origin and structure of barrier membranes, singular mechanical properties and clinical behaviors can be expected. It is important to understand the physic and chemical properties of barrier membranes to select the needed biomaterial for each clinical situation. To date, no study has evaluated and compared the physicochemical properties of various families of barrier membranes. The aim of this study is to evaluate the physicochemical properties of various barrier membranes. Fifteen membranes of different origin were tested in this study. Membranes were divided into biological or synthetic origin and grouped in natural allogenic collagen, natural xenogenic collagen, cross-linked collagen and synthetic membranes. Physicochemical properties were evaluated in terms of tension, stiffness, absorption ability, pH and wettability. For the tension tests, all membranes showed similar low tension and low stiffness, especially after a 4-min hydration, except for bone laminas that showed a greater stiffness particularly in a dry status. Regarding wettability and hydration of the barrier membranes, porcine origin membranes had greater hydration; wettability was also superior in porcine derived barrier membranes and showed a faster absorption of the drop on the rough surfaces. All membranes had a stable pH, having the synthetic membranes the most stable pH when compared to physiologic. The wide variety of barrier membranes opens a debate in which the practitioner should select the adequate barrier membrane for each clinical situation. Different materials show singular potentials depending on their tissue origin making them suitable for specific clinical indications. More studies regarding adsorption, integration and degradation of barrier membranes are needed to understand their behavior.

The use of prosthetic mesh for abdominal wall repairs: A semi-systematic-literature review

Following abdominal wall surgery, incisions are commonly sutured, stapled, or glued together by primary intention. Developments within the field of tissue engineering have led to the use of prosthetic meshes, with over 20 million meshes implanted each year worldwide. The function of the mesh is to hold together abdominal wall incisions and repair abdominal hernias. This has been demonstrated to be highly effective in some individuals; however, some patients have experienced postoperative complications, including dehiscence with further abdominal herniation (viscera protruding through the abdominal wall). Little is currently known about why these complications occur in a subset of patients who have had prosthetic mesh implants in abdominal wall repairs; therefore, this literature review examined existing studies identified via six electronic databases. A total of 463 studies were identified, of which 13 were included in this review. The results identified that the prosthetic mesh is highly successful in a large proportion of patients who have had a had a hernia repair in a range of locations; however, the prosthetic mesh has long-term complications, with rejection being observed in a subset of patients. The reason why the prosthetic is being rejected is still largely unknown, and therefore, further investigation needs to be carried out.

Adhesions on polypropylene versus Sepramesh® meshes: an experimental study in rats

OBJECTIVE

to compare the formation of induced intraperitoneal adhesions in rats when using polypropylene and Sepramesh® meshes.

METHODS

we used 20 male Wistar rats, randomly grouped in two groups of ten animals each. We arranged two 10x20mm meshes intraperitoneally into each animal, one being the polypropylene (PP), and the other, Sepramesh®. In Group 1, the polypropylene mesh was positioned to the right, and the Sepramesh®, to the left. In Group 2, the meshes' layout was reversed. After 14 days of the procedure, we euthanized the animals and analyzed the incorporation and percentages of adhesions macroscopically in each mesh. We submitted the collected data to statistical analysis with a significance level of 5% (p<0.05).

RESULTS

all meshes showed adhesions. In the Sepramesh® ones, the percentage of surface covered by adhesions ranged from 2% to 86%, with a mean of 18.6±18.6%, while in the polypropylene meshes, it varied between 6% and 86%, with an average of 57.4%±34.9% (p<0.05). The preferred adhesion sites on both meshes were the edges.

CONCLUSION

although no mesh was able to completely inhibit the development of adhesions, the Sepramesh® mesh presented less adhesions to the polypropylene mesh. The most common sites of adhesion formation were the edges of the prosthesis, which evidences the importance of the adequate fixation of the meshes.

Improved biocompatibility of profiled sutures through lower macrophages adhesion

The biocompatibility of a textile implant is determined by various parameters, such as material composition and surface chemistry. However, little is known about the influence of geometry of sutures on biocompatibility. To elucidate this factor we focused on geometry-modification resulting in ultrafine polyethylene terephthalate (UFPET) suture and a snowflake like shaped polyvenylidenfluorid (PVDF) suture. Forty-eight rats were divided into two observation periods. In each rat 3 out of 4 sutures (profiled UFPET, snowflake-like profiled PVDF, reference Prolene and Mersilene suture) were randomly placed into the subcutaneous tissue. Rats were euthanized after 7 and 21 days and samples were explanted. Foreign body granuloma was measured and expression of CD68, TUNEL, Ki-67 and Collagen I/III ratio were determined. The profiled (snowflake) suture showed a significantly smaller FBG in comparison to standard sutures (p < 0.001). Both modified sutures showed a significant lower tissue remodeling by Ki-67 and TUNEL expression (p < 0.03). Furthermore, profiled sutures caused a lower inflammatory reaction expressed in a significant lower amount of CD68 positive macrophages after 21 days (p < 0.001). Modifications of suture geometry alter the foreign body granuloma and the inflammatory reaction. Therefore, profiled sutures might be a promising approach to improve biocompatibility of textile mesh prosthesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1772-1778, 2019.

Adhesion Prevention to Polypropylene Meshes Using Combined Icodextrin Four Percent and Dimetindene Maleate

BACKGROUND

The use of surgical meshes in ventral hernia repair has significantly reduced hernia recurrence rates. However, when placed intraperitoneally prosthetic materials can trigger the development of peritoneal adhesions. The present experimental study evaluated the combined icodextrin 4% and dimetindene maleate treatment in preventing peritoneal adhesion formation to polypropylene and titanium-coated polypropylene meshes.

MATERIALS AND METHODS

Sixty female white rabbits were divided into four groups. A 2 × 2 cm piece of mesh was fixed to intact peritoneum in all animals through a midline laparotomy. A lightweight polypropylene mesh was implanted in groups 1 and 2 and a titanium-coated polypropylene mesh in groups 3 and 4. Groups 2 and 4 were treated, intraoperatively, with intravenous dimetindene maleate (0.1 mg/kg) and intraperitoneal solution of icodextrin 4% (20 mL/kg) and for the next 6 d with dimetindene maleate intramuscularly. The observation period lasted 15 d. Adhesion scores, percentage of mesh affected surface, tissue hydroxyproline levels, and tissue histopathology were examined.

RESULTS

All animals in group 1 and 57% of animals in group 3 presented postoperative adhesions. The combination of antiadhesives significantly reduced the extent and severity of adhesions as well as the hydroxyproline levels in groups 2 and 4 compared with groups 1 and 3. On microscopic evaluation, animals in group 1 exhibited higher inflammation scores compared with group 2, whereas animals in groups 2 and 4 had better mesotheliazation compared with groups 1 and 3.

CONCLUSIONS

The combined administration of icodextrin 4% and dimetindene maleate reduces the extent and severity of adhesions and may be successfully used to prevent adhesion formation after mesh intraperitoneal placement.

Mesh implants for hernia repair: an update

INTRODUCTION

Today the use of textile meshes has become a standard for the treatment of abdominal wall hernias and for the reinforcement of any tissue repair as the strength of the implant decreases the recurrence rates. With increasing use, side effects of the textile implants became apparent, as well.

AREAS COVERED

Based on publications in Medline over the past decade, general and specific benefits, as well as risks, are discussed with the challenge to define individual risk-benefit ratios. For meshes, certain high-risk or low-risk conditions can be defined. In an attempt to eliminate mesh-related risks, quality control for medical devices has meanwhile been revised. In both the USA and the EU post-market surveillance studies are required to keep medical devices approved.

EXPERT COMMENTARY

The impact of material on the complication rate will vary depending on the patient's co-morbidity or the risks of the procedure. Even the best material can end up with disappointing results in case of poor healing or poor surgery. On the other hand, when using high-risk devices, most of the complications after excellent surgery with excellent indication can be supposed to be mesh-related. Thus, the use of low-risk devices is recommended even though its advantage may not be demonstrable in clinical studies.

A Current Review of Hybrid Meshes in Abdominal Wall Reconstruction

Complex abdominal wall defects remain a common problem, though there has been significant advancement in technique and biomaterials over the last decade. The newly developed hybrid meshes are targeted to address several shortcomings of other meshes. Specifically, the marriage of biosynthetic or biologic materials with permanent prosthetic material is designed so that each will counteract the other's negative attributes. There are reports of permanent meshes having been associated with chronic pain, stiffness, and inflammation. However, their utility in maintaining biomechanical strength, thus limiting recurrence, makes them of value. In hybrid meshes, biosynthetic or biologic materials are coupled with permanent prosthetics, potentially protecting them from exhibiting deleterious effects by promoting and hastening tissue ingrowth. The various hybrid meshes currently available and investigational data are reviewed.

The influence of different sterilization types on mosquito net mesh characteristics in groin hernia repair

Background

In low-resource countries, a suture repair is still in common use due to the limited access to commercial mesh implants. The search for less expensive alternatives to the synthetic meshes has led to using mosquito nets. Sterilized mosquito net appears to be a low-cost and commonly available product that closely resembles commercially available meshes. However, the extent to which sterilization alters the structure of mosquito nets is still unknown. The aim of this research was to assess the effects of different sterilization types on physico-mechanical properties of mosquito nets.

Materials and methods

Nine different polymers were analyzed (six mosquito nets from low-resource countries, one European net, and two commercial meshes). The analyzed parameters included: polymer type, net surface area, fiber diameter, net thickness, mesh weight, pore size, tensile strength, and tear force. The measurements were taken before sterilization, after sterilization at 121 and at 134 °C.

Results

Sterilization altered net surface and pore size, but did not significantly alter the single fiber diameter, weave of filaments, or net thickness. Steam sterilization did not affect the tensile strength or tear force.

Conclusions

The reduction of the mosquito net surface area by more than 40% due to sterilization at 121 °C, results in a loss of macroporous structure, turning the mesh into hard, shrunken, non-pliable masses. Sterilization at 134 °C causes some mosquito nets to melt and completely destroys their porous structure. Maximum pressure in the abdominal cavity is higher than the tensile strength and tear force of some locally available mosquito nets; therefore, these nets should not be used.

International guidelines for groin hernia management

INTRODUCTION

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.

METHODS

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.

CONCLUSIONS

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.

The State of Prophylactic Mesh Augmentation

Prophylactic mesh augmentation (PMA) is the implantation of mesh during closure of an index laparotomy to decrease a patient's risk for developing incisional hernia (IH). The current body of evidence lacks refined guidelines for patient selection, mesh placement, and material choice. The purpose of this study is to summarize the literature and identify areas of research needed to foster responsible and appropriate use of PMA as an emerging technique. We conducted a comprehensive review of Scopus, Cochrane, PubMed, and clinicaltrials.gov for articles and trials related to using PMA for IH risk reduction. We further supplemented our review by including select papers on patient-reported outcomes, cost utility, risk modeling, surgical techniques, and available materials highly relevant to PMA. Five-hundred-fifty-one unique articles and 357 trials were reviewed. Multiple studies note a significant decrease in IH incidence with PMA compared with primary suture-only–based closure. No multicenter randomized control trial has been conducted in the United States, and only two such trials are currently active worldwide. Evidence exists supporting the use of PMA, with practical cost utility and models for selecting high-risk patients, but standard PMA guidelines are lacking. Although Europe has progressed with this technique, widespread adoption of PMA requires large-scale pragmatic randomized control trial research, strong evidence-based guidelines, current procedural terminology coding, and resolution of several barriers.

Evolution of ventral hernia repair

PURPOSE

The aim of this review was to look at relevant data and research on the evolution of ventral hernia repair.

METHODS

Resources including books, research, guidelines, and online articles were reviewed to provide a concise history of and data on the evolution of ventral hernia repair.

RESULTS

The evolution of ventral hernia repair has a very long history, from the recognition of ventral hernias to its current management, with significant contributions from different authors. Advances in surgery have led to more cases of ventral hernia formation, and this has required the development of new techniques and new materials for ventral hernia management. The biocompatibility of prosthetic materials has been important in mesh development. The functional anatomy and physiology of the abdominal wall has become important in ventral hernia management. New techniques in abdominal wall closure may prevent or reduce the incidence of ventral hernia in the future.

CONCLUSION

The management of ventral hernia is continuously evolving as it responds to new demands and new technology in surgery.

Critical overview of all available animal models for abdominal wall hernia research

PURPOSE

Since the introduction of the first prosthetic mesh for abdominal hernia repair, there has been a search for the "ideal mesh." The use of preclinical or animal models for assessment of necessary characteristics of new and existing meshes is an indispensable part of hernia research. Unfortunately, in our experience there is a lack of consensus among different research groups on which model to use. Therefore, we hypothesized that there is a lack of comparability within published animal research on hernia surgery due to wide range in experimental setup among different research groups.

METHODS

A systematic search of the literature was performed to provide a complete overview of all animal models published between 2000 and 2014. Relevant parameters on model characteristics and outcome measurement were scored on a standardized scoring sheet.

RESULTS

Due to the wide range in different animals used, ranging from large animal models like pigs to rodents, we decided to limit the study to 168 articles concerning rat models. Within these rat models, we found wide range of baseline animal characteristics, operation techniques, and outcome measurements. Making reliable comparison of results among these studies is impossible.

CONCLUSION

There is a lack of comparability among experimental hernia research, limiting the impact of this experimental research. We therefore propose the establishment of guidelines for experimental hernia research by the EHS.

From intraperitoneal onlay mesh repair to preperitoneal onlay mesh repair

Laparoscopic repair for ventral and incisional hernias was first reported in the early 1990s. It uses intraperitoneal only mesh placement to achieve a tension-free repair of the hernia. However, in recent years, there has been greater concern about long-term complication involving intraperitoneal mesh placement. Many case reports and case series have found evidence of mesh adhesion, mesh fistulation, and mesh migration into hollow organs including the esophagus, small bowel, and large bowel, resulting in various major acute abdominal events. Subsequent management of these complications may require major surgery that is technically demanding and difficult; in such cases, laparotomy and bowel resection have often been performed. Because of these significant, but not common, adverse events, many surgeons favor open sublay repair for ventral and incisional hernias. Investigators are therefore searching for a laparoscopic approach for ventral and incisional hernias that might overcome the mesh-induced visceral complications seen after intraperitoneal only mesh placement repair. Laparoscopic preperitoneal onlay mesh is one such approach. This article will explore the fundamental of intraperitoneal only mesh placement and its problems, the currently available peritoneal visceral-compatible meshes, and upcoming developments in laparoscopic ventral and incisional hernia repair. The technical details of preperitoneal onlay mesh, as well as its potential advantages and disadvantages, will also be discussed.

Lightweight Titanium-coated Mesh Versus Standard-Weight Polypropylene Mesh in Totally Extraperitoneal Inguinal Hernia Repair (TEP): A Cohort Analysis

PURPOSE

The study objective is to compare the outcomes of laparoscopic to tally extraperitoneal repair using the standard-weight polypropylene mesh or a lightweight titanium-coated mesh.

METHODS

A retrospective review was conducted on 138 adult patients with unilateral inguinal hernias, who underwent totally extraperitoneal inguinal hernia repair between 2010 and 2013 using either a standard-weight polypropylene mesh (Prolene mesh, 80 g/m) or a lightweight titanium-coated mesh (Ti Mesh light, 35 g/m).

RESULTS

There was no difference in reported pain at 24 hours postoperatively. The difference in reported pain at follow-up (mean: 21 mo) was insignificant [PP vs. Ti: 7.8% (n=5) vs. 8.3% (n=3), P=0.92], the differences regarding chronic inguinal pain was also insignificant [PP vs. Ti: 14% (n=9) vs. 5.5% (n=2), P=0.191], and there was no difference in the development of hernia recurrence [PP vs. Ti: 1.5% (n=1) vs. 0, P=0.42].

CONCLUSIONS

No statistically significant differences of the overall postoperative outcome were observed between the 2 mesh types.

Degradation of polypropylene in vivo: A microscopic analysis of meshes explanted from patients

Polypropylene meshes, originally introduced for hernia repair, are presently utilized in several anatomical sites. Several million are implanted annually worldwide. Depending on the device, up to 10% will be excised to treat complications. The excised meshes can provide material to study the complications, however, they have remained underutilized over the last decades and the mechanisms of complications continue to be incompletely understood. The fundamental question as to whether polypropylene degrades in vivo is still debated. We have examined 164 excised meshes using conventional microscopy to search for features of polypropylene degradation. Four specimens were also examined by transmission electron microscopy. The degraded material, detected by its ability to absorb dyes in the degradation nanopores, formed a continuous layer at the surface of the mesh fibers. It retained birefringence, inclusions of non-degraded polypropylene, and showed ability to meld with the non-degraded fiber core when heated by the surgical cautery. Several features indicated that the degradation layer formed in vivo: inflammatory cells trapped within fissures, melting caused by cautery of excision surgery, and gradual but progressive growth of the degradation layer while in the body. Cracking of the degraded material indicated a contribution to clinically important mesh stiffening and deformation. Chemical products of degradation need to be analyzed and studied for their role in the mesh-body interactions. The described methods can also be used to study degradation of other materials. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 237-248, 2017.

A case of a colocutaneous fistula: A rare complication of mesh migration into the sigmoid colon after open tension-free hernia repair

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This is the first report of mesh migration to sigmoid colon post tension free hernia repair.

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Colonoscopy is highly recommended if mesh migration to the colon is suspected.

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Identification of a concurrent sliding hernia in Lichtenstein repair is adviced to avoid physical contact of a mesh to the sliding organ.

Introduction

The Lichtenstein technique is commonly used in inguinal hernia repair and a polypropylene mesh is the most frequently used mesh. Mesh migration into the colon has been rarely reported in the literature. Here we report a case of a colocutaneous fistula that developed following delayed mesh migration into the sigmoid colon.

Presentation of case

A 52-year-old man undergone Lichtenstein repair for left direct inguinal herniain 2008. Three years later, he presented complaining of rectal bleeding and concurrent bloody discharge from the hernia repair scar. Colonoscopy identified an internal fistulous orifice with intraluminal extrusion of the polypropylene mesh. Furthermore, abdominal ultrasound revealed a fistulous tract extending from the sigmoid colon to the anterior abdominal wall, and a fistulogram confirmed the findings. Open sigmoidectomy and resection of the abdominal wall with the fistula tract was performed, and BIO-A^® tissue reinforcement meshwas placed. His postoperative course was unremarkable and was discharged on postoperative day 3.

Discussion

Mesh migration after mesh inguinal hernia repair is unpredictable. A previous report has presented complications related to prosthetics in hernia repair, such as infection, contraction, rejection, and, rarely, mesh migration.Mesh migration may occur as an early or late complication after hernioplasty.

Conclusion

During hernia repair, the surgeon should carefully check for a sliding hernia, which may contain the sigmoid colon within the sac, because failure to identify this hernia may lead to direct contact between the mesh and the colon, which may cause pressure necrosis and fistula formation followed by mesh migration.

Surgical approach to abdominal wall defects: history and new trends

We briefly outline the history of hernia surgery development from the Ebers Papyrus to modern prosthetic repairs. The rapid evolution of anatomical, physiological and pathogenetic concepts has involved the rapid evolution of surgical treatments. From hernia sack cauterization to sack ligation, posterior wall repair (Bassini), and prosthetic reinforcement there has been an evident improvement in surgical treatment results that has stimulated surgeons to find new technical solutions over time. The introduction of prosthetic repair, the laparoscopic revolution, the impact of local anesthesia and the diffusion of day surgery have been the main advances of the last 50 years. Searching for new gold standards, the introduction of new devices has also led to new complications and problems. Research of the last 10 years has been directed to overcome prosthetic repair complications, introducing every year new meshes and materials. Lightweight meshes, composite meshes and biologic meshes are novelties of the last few years. We also take a look at future trends.

Changes in the frequencies of abdominal wall hernias and the preferences for their repair: a multicenter national study from Turkey

Abdominal wall hernias are a common problem in the general population. A Western estimate reveals that the lifetime risk of developing a hernia is about 2%. As a result, hernia repairs likely comprise the most frequent general surgery operations. More than 20 million hernias are estimated to be repaired every year around the world. Numerous repair techniques have been described to date however tension-free mesh repairs are widely used today because of their low hernia recurrence rates. Nevertheless, there are some ongoing debates regarding the ideal approach (open or laparoscopic), the ideal anesthesia (general, local, or regional), and the ideal mesh (standard polypropylene or newer meshes).

Application of Biodegradable Polyhydroxyalkanoates as Surgical Films for Ventral Hernia Repair in Mice

The cytotoxicity and biosafety of poly-(3-hydroxybutyrate) (P3HB) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HBV) films were investigated in vitro using 3T3 fibroblast cells and in vivo through subcutaneous implantation of the film in mice. The in vitro test revealed that endotoxin-free P3HB and P3HBV films allowed cell attachment and growth. Film-soaked conditional media showed no significant inhibitory or cytotoxic effects on cell proliferation. The in vivo absorption test showed that both the P3HB and P3HBV films slowly degraded and that P3HB had a slower degradation rate than that of P3HBV. Applying a P3HB film in hernia repair demonstrated a favorable outcome: the film was able to correct the abdominal ventral hernia by inducing connective tissue and fat ingrowth and exhibited an extremely slow rate of degradation. Furthermore, the P3HB film demonstrated the advantage of lower intestinal adhesion to the ventral hernia site compared with the P3HBV and PP commercial films.

Effects of chitosan coatings on polypropylene mesh for implantation in a rat abdominal wall model

Hernia repair and pelvic floor reconstruction are usually accompanied with the implantation of a surgical mesh, which frequently results in a foreign body response with associated complications. An ideal surgical mesh that allows force generation of muscle tissues without significant granulation tissue and/or fibrosis is of significant clinical interest. The objective of the present study was to evaluate the in vitro and in vivo responses of a chitosan coating on polypropylene mesh (Ch-PPM) in comparison with commercially available meshes. We found that application of a 0.5% (w/v) Ch-PPM elicited preferential attachment of myoblasts over fibroblast attachment in vitro. Therefore, we test the hypothesis that 0.5% Ch-PPM will encourage skeletal muscle tissue ingrowth and decrease fibrosis formation in vivo. We implanted 0.5% Ch-PPM, collagen-coated polypropylene mesh (Pelvitex™; C.R. Bard), and polypropylene (Avaulta Solo(®); C.R. Bard) alone using a rat abdominal defect model. Force generation capacity and inflammatory response of each mesh were evaluated 2, 4, and 12 weeks postimplantation. We found that chitosan coating is associated with the restoration of functional skeletal muscle with histomorphologic characteristics that resemble native muscle and an early macrophage phenotypic response that has previously been shown to lead to more functional outcomes.

An in vitro study assessing the effect of mesh morphology and suture fixation on bacterial adherence

PURPOSE

Prosthetic infections, although relatively uncommon in hernia surgery, are a source of considerable morbidity and cost. The aims of this experimental study were to assess the influence of the morphological properties of the mesh on bacterial adherence in vitro. The morphological properties assessed were the polymer type, filament type, filament diameter, mesh weight, mean pore size, and the addition of silver chlorhexidine and titanium coatings. In addition, the study assessed the effect on bacterial adherence of adding a commonly used suture to the mesh and compared adherence rates to self-gripping mesh that does not require suture fixation.

METHODS

Eight commercially sourced flat hernia meshes with different material characteristics were included in the study. These were Prolene(®) (Ethicon(®)), DualMesh(®) (Gore(®)), DualMesh(®) Plus (Gore(®)), Parietex™ ProGrip (Covidien™), TiMesh(®) Light (GfE Medical), Bard(®) Soft Mesh (Bard(®)), Vypro(®) (Ethicon(®)), and Omyra(®) (Braun(®)). Individual meshes were inoculated with Staphylococcus epidermidis and Staphylococcus aureus with a bacterial inoculum of 10(2) bacteria. To assess the effect of suture material on bacterial adhesion, a sterile piece of commonly used monofilament suture material (2.0 Prolene(®), ZB370 Ethicon(®)) was sutured to selected meshes (chosen to represent different commonly used polymers and/or the presence of an antibacterial coating). Inoculated meshes were incubated for 18 h in tryptone soy broth and then analysed using scanning electron microscopy. A previously validated method for enumeration of bacteria using automated stage movement electron microscopy was used for direct bacterial counting. The final fraction of the bacteria adherent to the mesh was compared between the meshes and for each morphological variable. One-way analysis of variance (ANOVA) was performed on the bacterial counts. Tukey's test was used to determine the difference between the different biomaterials in the event the ANOVA was significant.

RESULTS

Properties that significantly increased the mean bacterial adherence were the expanded polytetrafluoroethylene polymer (P < 0.001); multifilament meshes (P < 0.001); increased filament diameter (P < 0.001); increased mesh weight (P < 0.001); and smaller mean pore size (P < 0.001). In contrast, mesh coating with antibacterial silver chlorhexidine significantly reduced bacterial adhesion (S. epidermidis mean bacterial count 140.7 ± 19.1 SE with DualMesh(®) vs. 2.3 ± 1.2 SE with DualMesh(®) Plus, P < 0.001; S. aureus mean bacterial count 371.7 ± 22.7 SE with DualMesh(®) vs. 19.3 ± 4.7 SE with DualMesh(®) Plus, P = 0.002). The addition of 2.0 Prolene suture material significantly increased the mean number of adherent bacteria independent of the mesh polymer or mesh coating (P = 0.04 to <0.001).

CONCLUSION

The present study demonstrates the significant influence of the prosthetic load on bacterial adherence. In patients at increased risk of infection, low prosthetic load materials, i.e., lightweight meshes with large pores, may be beneficial. Furthermore self-fixing meshes, which avoid increasing the prosthetic load and antibacterial impregnated meshes, may have an advantage in this setting.

'The ideal mesh?'

Currently, more than 200 different textile constructions, so-called 'meshes', are available for use world-wide in the more than 20 million operations performed annually for the reinforcement of tissues. As any reintervention at the mesh-tissue compound is a surgical challenge, sometimes resulting in almost untreatable defects, huge efforts are being made to improve the biological and functional performance of the meshes. Based on numerous experimental and clinical studies in the past 20 years, our understanding of them has improved markedly. This includes the biomechanical aspects and the histopathological evaluation of the recipient tissue. Sufficiently large pores as well as structural stability in case of mechanical strain have been identified to be crucial to reduce excessive inflammation and fibrosis. Furthermore, large pores prevent bridging of the foreign body reaction through the pore and thereby help to reduce clinical adverse events as erosion, shrinkage or pain. However, with regard to the many different indications for meshes, there will never be one single ideal mesh for all purposes. To achieve an optimal performance, every construction should be designed according to the specific functional requirements, charging the surgeon to identify the best mesh for his purpose.