Polypropylene mesh and the host response

The Infected Polypropylene Mesh: When Does Biofilm Form and Which Antiseptic Solution Most Effectively Removes It?

BACKGROUND

Polypropylene (PPE) mesh is commonly utilized to reconstruct catastrophic extensor mechanism disruptions in revision total knee arthroplasty. Unfortunately, these procedures are associated with a high rate of periprosthetic joint infection. The purpose of the current study was to: 1) visualize and quantify the progression of bacterial biofilm growth on PPE-mesh; and 2) determine which antiseptic solutions effectively remove viable bacteria.

METHODS

Knitted PPE mesh samples were cultured with either methicillin-sensitive Staphylococcus aureus (MSSA) or Escherichia coli (E. coli) for 7 days, with regular quantification of colony forming units (CFUs) and visualization using scanning electron microscopy to identify maturity. Immature (24 hour) and mature (72 hour) biofilm was treated with one of 5 commercial antiseptics for 3 minutes. A 0.05% chlorhexidine gluconate, a surfactant-based formulation of ethanol, acetic acid, sodium acetate, benzalkonium chloride, diluted povidone-iodine (0.35%), undiluted (10%) povidone-iodine, and 1:1 combination of 10% povidone-iodine and 3% hydrogen peroxide. A 3-log reduction in CFUs compared to saline was considered clinically meaningful.

RESULTS

The CFU counts plateaued, indicating maturity, at 72 hours for both MSSA and E. coli. The scanning electron microscopy confirmed confluent biofilm formation after 72 hours. The 10% povidone-iodine was clinically effective against all MSSA biofilms and immature E. coli biofilms. The 10% povidone-iodine with hydrogen peroxide was effective in all conditions. Only 10% povidone iodine formulations produced significantly (P < .0083) reduced CFU counts against mature biofilms.

CONCLUSIONS

Bacteria rapidly form biofilm on PPE mesh. Mesh contamination can be catastrophic, and clinicians should consider utilizing an antiseptic solution at the conclusion of mesh implantation. Undiluted povidone-iodine with hydrogen peroxide should be considered when attempting to salvage infected PPE mesh.

The Use of Platelet-Rich Fibrin and Polypropylene Mesh in Repair of Nasal Septal Perforation

OBJECTIVE

In this study, we aimed to investigate the effectiveness of the use of polypropylene mesh and platelet-rich fibrin (PRF) in nasal septal perforation (NSP) repair.

STUDY DESIGN

Prospective experimental study.

SETTING

Laboratory.

METHODS

Twenty-four adult male New Zealand rabbits were used in our study. In all subjects, a 10 × 10 mm perforation was created in the septum. The subjects were divided into 3 equal groups according to the different methods used in perforation closure. The bilateral mucosal flap was used in the control group, polypropylene mesh + bilateral mucosal flap in the mesh group, and polypropylene mesh + bilateral mucosal flap + PRF in the mesh + PRF group.

RESULTS

NSP treatment success rate was found to be significantly higher in the mesh (4/6, 66.7%) and mesh + PRF (6/6, 100%) groups compared to the control group (0/6, 0%). Re-epithelialization score was higher in the mesh + PRF group and the control group compared to the mesh group. While the necrosis, neutrophil, and abscess scores were highest in the mesh group, they were similar to the control group in the mesh + PRF group.

CONCLUSIONS

While polypropylene mesh significantly increases the success rate in NSP repair, it causes severe inflammatory responses. However, when polypropylene mesh is combined with PRF, it both increases the rate of perforation closure and significantly reduces the complications associated with the use of mesh.

Bilateral inguinal hernia repair and male fertility: a randomized clinical trial comparing Lichtenstein versus laparoscopic transabdominal preperitoneal (TAPP) technique

BACKGROUND

The effects of hernia repair on testicular function remain uncertain, regardless of the technique used. Studies that analyze testicular volume and flow after hernia repair or hormonal measurements are scarce and show contradictory results. This study aimed to evaluate the impact of bilateral inguinal hernia repair on male fertility in surgical patients in whom the Lichtenstein and laparoscopic transabdominal preperitoneal (TAPP) techniques were used.

METHODS

A randomized clinical trial comparing open (Lichtenstein) versus laparoscopic (TAPP) hernia repair using polypropylene mesh was performed in 48 adult patients (20 to 60 years old) with primary bilateral inguinal hernia. Patients were evaluated preoperatively and 90 and 180 postoperative (PO) days. Sex hormones (Testosterone, FSH, LH and SHGB) analysis, testicular ultrasonography, semen quality sexual activity changes and quality of life (QoL) were performed. Postoperative pain was evaluated using the visual analog scale (VAS).

RESULTS

Thirty-seven patients with aged of 44 ± 11 years were included, 19 operated on Lichtenstein and 18 operated on TAPP. The surgical time was similar between techniques. The pain was greater in the Lichtenstein group on the 7th PO day. The biochemical and hormonal analyses, testicular ultrasonography (Doppler, testicular volume, and morphological findings) and sperm quality were similar between groups. However, the sperm morphology was better in the Lichtenstein group after 180 days (p < 0.05 vs. preoperative) and two patients who underwent Lichtenstein hernia repair had oligospermia after 180 days. The QoL evaluation showed a significant improvement after surgery in the following domains: physical function, role emotional, bodily pain and general health (p < 0.05). On comparison of Lichtenstein vs. TAPP none of the domains showed statistically significant differences. No patient reported sexual changes.

CONCLUSION

Bilateral inguinal hernia repair with polypropylene mesh, whether using Lichtenstein or TAPP, does not impair male fertility in terms of long-term outcomes.

TRIAL REGISTRATION

Approved by the Ethics Committee for the Analysis of Research Projects (CAPPesq) of the HC/FMUSP, Number 2.974.457, in June 2015, Registered on Plataforma Brasil in October 2015 under Protocol 45535015.4.0000.0068. Registered on Clinicaltrials.gov, NCT05799742. Enrollment of the first subject in January 2016.

Fabrication and in vitro investigation of hyperbranched poly-lysine-grafted warp knitted polypropylene sling for potential treatment of stress urinary incontinence

Polypropylene (PP) sling implantation is the most commonly performed procedure for women with stress urinary incontinence (SUI). However, concerns have arisen regarding complications caused by slings, including the common issue of erosion, which can be attributed to various factors such as the body's response and bacterial contamination. To address these concerns, we have developed a rectangular mesh self-locking edge sling with a large pore size and lightweight design. Promising results have been obtained from preliminary in vivo mechanical reliability tests, including uniaxial tensile tests. In comparative in vitro fixed load tensile tests and simulated Tension-free Vaginal Tape (TVT) and Transobturator Vaginal Tape inside-out (TVT-O) technique tests using commercial slings, our sling demonstrated less transverse wrinkling. Both slings achieved an effective porosity of over 45% under the TVT technique. However, the commercial sling experienced a significant reduction in effective porosity during the TVT-O technique, whereas our sling maintained a stable effective porosity with minimal wrinkling. Furthermore, we successfully developed cationic hydration rejection-driven antibacterial-anti-fouling coatings on the surface of our sling by grafting hyperbranched poly-lysine (HBPL) mediated by polynorepinephrine. The HBPL coating imparts a positive charge and hydrophilicity to the sling, resulting in elevated bactericidal activity and reducing protein adhesion. An optimal grafting concentration of 20 mg mL-1 was selected, confirming the stability and biocompatibility of the sling coating. This coating is expected to reduce the likelihood of postoperative erosion. Overall, our research represents significant advancements in improving the safety and performance of PP slings for stress urinary incontinence, potentially leading to a reduction in complications following surgery.

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.

Mechanical Properties of Smart Polypropylene Meshes: Effects of Mesh Architecture, Plasma Treatment, Thermosensitive Coating, and Sterilization Process

Smart polypropylene (PP) hernia meshes were proposed to detect surgical infections and to regulate cell attachment-modulated properties. For this purpose, lightweight and midweight meshes were modified by applying a plasma treatment for subsequent grafting of a thermosensitive hydrogel, poly(N-isopropylacrylamide) (PNIPAAm). However, both the physical treatment with plasma and the chemical processes required for the covalent incorporation of PNIPAAm can modify the mechanical properties of the mesh and thus have an influence in hernia repair procedures. In this work, the mechanical performance of plasma-treated and hydrogel-grafted meshes preheated at 37 °C has been compared with standard meshes using bursting and the suture pull out tests. Furthermore, the influence of the mesh architecture, the amount of grafted hydrogel, and the sterilization process on such properties have been examined. Results reveal that although the plasma treatment reduces the bursting and suture pull out forces, the thermosensitive hydrogel improves the mechanical resistance of the meshes. Moreover, the mechanical performance of the meshes coated with the PNIPAAm hydrogel is not influenced by ethylene oxide gas sterilization. Micrographs of the broken meshes evidence the role of the hydrogel as reinforcing coating for the PP filaments. Overall, results confirm that the modification of PP medical textiles with a biocompatible thermosensitive hydrogel do not affect, and even improve, the mechanical requirements necessary for the implantation of these prostheses in vivo.

Dermatoscopic and Dermatopathologic Features of a 3-Year-Old Buried Polypropylene Suture

ABSTRACT

Cutaneous foreign bodies are a well-known cause of delayed wound healing and complications such as abscesses, fistula formation, and secondary infections. Polypropylene sutures are widely utilized in cutaneous surgery because they easily travel through tissues while eliciting minimal tissue reactions. Despite these advantages, retained polypropylene sutures can cause complications. The authors report a case of a retained polypropylene suture that remained buried after a total excision 3 years prior. It started to cause cutaneous symptoms when the patient began exercising 1 week prior to presentation. The authors also examine the dermatoscopic and dermatopathologic features and other complications related to retained polypropylene sutures that have been reported in the literature.

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Tailor-Made 3D Printed Meshes of Alginate-Waterborne Polyurethane as Suitable Implants for Hernia Repair

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.

Feasibility of a Wireless Implantable Multi-electrode System for High-bandwidth Prosthetic Interfacing: Animal and Cadaver Study

BACKGROUND

Currently used prosthetic solutions in upper extremity amputation have limited functionality, owing to low information transfer rates of neuromuscular interfacing. Although surgical innovations have expanded the functional potential of the residual limb, available interfaces are inefficacious in translating this potential into improved prosthetic control. There is currently no implantable solution for functional interfacing in extremity amputation which offers long-term stability, high information transfer rates, and is applicable for all levels of limb loss. In this study, we presented a novel neuromuscular implant, the the Myoelectric Implantable Recording Array (MIRA). To our knowledge, it is the first fully implantable system for prosthetic interfacing with a large channel count, comprising 32 intramuscular electrodes.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate the MIRA in terms of biocompatibility, functionality, and feasibility of implantation to lay the foundations for clinical application. This was achieved through small- and large-animal studies as well as test surgeries in a human cadaver.

METHODS

We evaluated the biocompatibility of the system's intramuscular electromyography (EMG) leads in a rabbit model. Ten leads as well as 10 pieces of a biologically inert control material were implanted into the paravertebral muscles of four animals. After a 3-month implantation, tissue samples were taken and histopathological assessment performed. The probes were scored according to a protocol for the assessment of the foreign body response, with primary endpoints being inflammation score, tissue response score, and capsule thickness in µm. In a second study, chronic functionality of the full system was evaluated in large animals. The MIRA was implanted into the shoulder region of six dogs and three sheep, with intramuscular leads distributed across agonist and antagonist muscles of shoulder flexion. During the observation period, regular EMG measurements were performed. The implants were removed after 5 to 6 months except for one animal, which retained the implant for prolonged observation. Primary endpoints of the large-animal study were mechanical stability, telemetric capability, and EMG signal quality. A final study involved the development of test surgeries in a fresh human cadaver, with the goal to determine feasibility to implant relevant target muscles for prosthetic control at all levels of major upper limb amputation.

RESULTS

Evaluation of the foreign body reaction revealed favorable biocompatibility and a low-grade tissue response in the rabbit study. No differences regarding inflammation score (EMG 4.60 ± 0.97 [95% CI 4.00 to 5.20] versus control 4.20 ± 1.48 [95% CI 3.29 to 5.11]; p = 0.51), tissue response score (EMG 4.00 ± 0.82 [95% CI 3.49 to 4.51] versus control 4.00 ± 0.94 [95% CI 3.42 to 4.58]; p > 0.99), or thickness of capsule (EMG 19.00 ± 8.76 µm [95% CI 13.57 to 24.43] versus control 29.00 ± 23.31 µm [95% CI 14.55 to 43.45]; p = 0.29) were found compared with the inert control article (high-density polyethylene) after 3 months of intramuscular implantation. Throughout long-term implantation of the MIRA in large animals, telemetric communication remained unrestricted in all specimens. Further, the implants retained the ability to record and transmit intramuscular EMG data in all animals except for two sheep where the implants became dislocated shortly after implantation. Electrode impedances remained stable and below 5 kΩ. Regarding EMG signal quality, there was little crosstalk between muscles and overall average signal-to-noise ratio was 22.2 ± 6.2 dB. During the test surgeries, we found that it was possible to implant the MIRA at all major amputation levels of the upper limb in a human cadaver (the transradial, transhumeral, and glenohumeral levels). For each level, it was possible to place the central unit in a biomechanically stable environment to provide unhindered telemetry, while reaching the relevant target muscles for prosthetic control. At only the glenohumeral level, it was not possible to reach the teres major and latissimus dorsi muscles, which would require longer lead lengths.

CONCLUSION

As assessed in a combination of animal model and cadaver research, the MIRA shows promise for clinical research in patients with limb amputation, where it may be employed for all levels of major upper limb amputation to provide long-term stable intramuscular EMG transmission.

CLINICAL RELEVANCE

In our study, the MIRA provided high-bandwidth prosthetic interfacing through intramuscular electrode sites. Its high number of individual EMG channels may be combined with signal decoding algorithms for accessing spinal motor neuron activity after targeted muscle reinnervation, thus providing numerous degrees of freedom. Together with recent innovations in amputation surgery, the MIRA might enable improved control approaches for upper limb amputees, particularly for patients with above-elbow amputation where the mismatch between available control signals and necessary degrees of freedom for prosthetic control is highest.

The impact of bacterial contamination on the host response towards fully absorbable poly-4-hydroxybutyrate and nonabsorbable polypropylene pelvic floor implants

Polypropylene (PP) implants for the vaginal surgical correction of pelvic organ prolapse (POP) are known for adverse events, like vaginal or visceral exposures. It is hypothesized that this is a result of a prolonged inflammatory response. One of the triggering factors of prolonged inflammation might be bacterial contamination. A possible solution might lie in an absorbable biomaterial, which provides initial mechanical support while being gradually replaced by the host tissue.

With this study we aimed to compare the host response, in a subcutaneous mouse implant infection model, to delayed absorbable poly-4-hydroxybutyrate (P4HB) and a latest generation PP implant. By comparing non-infected to Staphylococcus aureus infected mice, we assessed how bacterial contamination affects the host response and its role in the development of complications. Further, we included sham surgery as a control, mimicking the wound response in native tissue repair.

Despite the higher surface area of the P4HB implants, the clearance of infection was similarly delayed in the presence of a P4HB or PP implant, as compared to sham. Further, the host response towards P4HB and PP was quite comparable, yet collagen deposition was significantly increased around infected P4HB implants at early time points. Adverse event rates were similar, though implant exposures were only seen in infected mice and more often with PP (11.1%) than P4HB implants (5.6%). Infected mice overall had significantly higher levels of infiltration of inflammatory cells and lower levels of vascularization and collagen deposition compared to non-infected mice. Thus, for both P4HB and PP, bacterial contamination negatively affected mesh integration by increased inflammation and an increased adverse event rate. Altogether, our results from this subcutaneous mouse implant infection study suggest that P4HB could be a promising degradable alternative to PP, warranting further research to study its potential as a new surgical solution for women with POP.

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Absorbable poly-4-hydroxybutyrate (P4HB) is studied as a novel pelvic floor implant.

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Comparable host response to P4HB and polypropylene in a subcutaneous mouse implant infection model.

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Implant exposures exclusively occurred upon Staphylococcus aureus infection.

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Exposures occurred less with P4HB (5.6%) compared to polypropylene (11.1%).

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S. aureus infection increased inflammation and deranged the host response.

Are polypropylene mesh implants associated with systemic autoimmune inflammatory syndromes? A systematic review

Purpose

The surgical implantation of polypropylene (PP) meshes has been linked to the occurrence of systemic autoimmune disorders. We performed a systematic review to determine whether PP implants for inguinal, ventral hernia or pelvic floor surgery are associated with the development of systemic autoimmune syndromes.

Methods

We searched Embase, Medline, Web of Science, Scopus, Cochrane library, clinicaltrialsregister.eu, clinicaltrails.gov and WHO-ICTR platform. Last search was performed on November 24th 2021. All types of studies reporting systemic inflammatory/autoimmune response in patients having a PP implant for either pelvic floor surgery, ventral or inguinal hernia repair were included. Animal studies, case reports and articles without full text were excluded. We intended to perform a meta-analysis. The quality of evidence was assessed with the Newcastle–Ottawa Scale. This study was registered at Prospero (CRD42020220705).

Results

Of 2137 records identified, 4 were eligible. Two retrospective matched cohort studies focused on mesh surgery for vaginal prolapse or inguinal hernia compared to hysterectomy and colonoscopy, respectively. One cohort study compared the incidence of systemic conditions in women having urinary incontinence surgery with and without mesh. These reports had a low risk of bias. A meta-analysis showed no association when comparing systemic disease between mesh and control groups. Calculated risk ratio was 0.9 (95% CI 0.82–0.98). The fourth study was a case series with a high risk of bias, with a sample of 714 patients with systemic disease, 40 of whom had PP mesh implanted.

Conclusion

There is no evidence to suggest a causal relationship between being implanted with a PP mesh and the occurrence of autoimmune disorders.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10029-021-02553-y.

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.

Is it the Surgeon? A Re-examination of Mid-urethral Sling Complications

OBJECTIVE

To identify potential technical factors during initial mid-urethral sling (MUS) placement that contribute to subsequent sling revision procedures.

METHODS

A retrospective chart review was performed examining synthetic MUS reoperations at a single institution from 2008-2020. The implanting surgeon's operative note, when available, was critically reviewed with respect to trocar placement, sling location, and tensioning technique. The reoperative report was reviewed for aberrant intraoperative findings relating to the index surgery.

RESULTS

A total of 306 women underwent revision of their MUS. Operative reports from the implanting surgeon were available for 276 (90.2%) women. Review of index operative reports revealed 47 unambiguous descriptions of improper technique, including 19 cases of described excessive tensioning and 2 cases of MUS placement despite noted urethral injury during the index case. Indications for reoperation were clinical obstruction (63%), pain (40%), and mesh erosion/exposure (33%). In 186 (67.4%) women, there was an intraoperative finding during the revision that likely contributed to the need for reoperation. Among these 186 women, 110 (59.1%) slings were noted to have been placed too proximally, 78 (41.9%) were over-suspended, and 57 (30.6%) were placed too deep in the periurethral fascia.

CONCLUSION

Review of the index operative note and findings at operative re-exploration of MUS surgeries, often reveals evidence that the initial MUS implantation was technically suboptimal. Such findings suggest that intraoperative surgical technique is a critically important factor contributing to postoperative complications in MUS surgery. This underscores the importance of surgical training and adherence to surgical principles during the placement of a synthetic MUS.

Development of a cellulose-based prosthetic mesh for pelvic organ prolapse treatment: In vivo long-term evaluation in an ewe vagina model

The use of vaginal surgical mesh to treat pelvic organ prolapse (POP) has been associated with high rates of mesh-related complications. In the present study, we prepared new kinds of meshes based on bacterial cellulose (BC) and collagen-coated BC (BCCOL) using a laser cutting method and perforation technique. The mechanical properties of pre-implanted BC meshes, including breaking strength, suture strength and rigidity, were equal to or exceeded those of available clinically used polypropylene meshes. An in vitro cellular assay revealed that BCCOL meshes exhibited enhanced biocompatibility by increasing collagen secretion and cell adhesion. Both BC and BCCOL meshes only caused weak inflammation and were surrounded by newly formed connective tissue composed of type I collagen after implantation in a rabbit subcutaneous model for one week, demonstrating that the novel mesh is fully biocompatible and can integrate into surrounding tissues. Furthermore, a long-term (ninety days) ewe vaginal implantation model was used to evaluate foreign body reactions and suitability of BC and BCCOL meshes as vaginal meshes. The results showed that the tissue surrounding the BC meshes returned to its original physiology as muscle tissue, indicating the excellent integration of BC meshes into the surrounding tissues without triggering severe local inflammatory response post-implantation. The collagen coating appeared to induce a chronic inflammatory response due to glutaraldehyde remnants. The present exploratory research demonstrated that the developed BC mesh might be a suitable candidate for treating POP.

Visualization of implanted mesh in the pelvic reconstructive surgery using an X-ray-detectable thread

PURPOSE

Visualization of the implanted mesh after a pelvic floor repair surgery is important for evaluating mesh-related complications. We made an X-ray-detectable mesh and studied the histocompatibility and toxicity of it.

METHODS

A thin barium sulfate thread was weaved on a traditional polypropylene mesh to make it X-ray detectable. The cytotoxicity of the mesh was tested by the MTT assay on L929 cell line. The histocompatibility and toxicity of mesh were evaluated in rabbits. Meshes were first implanted intraperitoneally. On postoperative day 7, bloods were tested to estimate the acute toxicity of meshes. After 6 months, rabbits were sacrificed and local inflammatory reaction and tissue regeneration at implantation sites were estimated by the HE stain and Masson stain. In addition, CT scans were performed after surgeries to display the location and shape of implanted meshes.

RESULTS

Compared to the polypropylene mesh group, no significant difference was observed in the X-ray-detectable mesh group on both in vitro cytotoxicity and in vivo acute and chronic toxicity. The amounts of extra cellular matrix between two groups did not differ. Through CT scan and 3D remodeling, the barium sulfate thread clearly revealed the position and shape of the X-ray-detectable mesh, whereas the traditional mesh was invisible under CT scan.

CONCLUSION

Adding a thin barium sulfate thread on the polypropylene mesh does not change its histocompatibility or toxicity in rabbit model. The barium sulfate thread can effectively show the location and shape of implanted mesh under CT scan.

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

INTRODUCTION AND HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Animal experimental research assessing urogynecologic surgical mesh implants: Outcome measures describing the host response, a systematic review and meta-analysis

Aim

Before the introduction of new biomaterials for prolapse surgery, animal studies on the host response are required. Unfortunately, large variation in study design hampers obtaining an overview of the safety and efficacy, and translation to clinical practice. Our aim is to systematically review the literature on all outcome measures describing the host response in animal studies assessing the biocompatibility of urogynecologic surgical mesh implants for prolapse surgery. Furthermore, by meta‐analysis, we aim to assess the effect of implantation and compare this to control animals receiving sham surgery or native tissue repair.

Methods

We performed a systematic search from inception to August 2020. Since this is an explorative study we included original, controlled, and noncontrolled animal studies describing any host response to the implant. Quantitative outcome measures reported ≥10 times in ≥2 articles were eligible for meta‐analysis.

Results

Fifty articles were included in the qualitative synthesis and 36 articles were eligible for meta‐analysis. In total, 154 outcome measures were defined and classified into (1) histomorphology, (2) biomechanics and, (3) macroscopic morphology. Animals with vaginal implants demonstrated significantly increased M1 and M2 macrophages, MMP‐2, neovascularization, TNF‐α, and stiffness, and lower vaginal contractility compared to control animals.

Conclusion

The host response significantly differs in animals after vaginal mesh implantation compared to control animals, both pro‐ and anti‐inflammatory. However, we observed a paucity in the uniformity of reported outcomes. For future animal studies, we propose the development of a core outcome set, which ideally predicts the host response in women.

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

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

Fully absorbable poly-4-hydroxybutyrate implants exhibit more favorable cell-matrix interactions than polypropylene

Pelvic organ prolapse (POP) is a multifactorial condition characterized by the descent of the pelvic organs due to the loss of supportive tissue strength. This is presumably caused by the decreased fibroblast function and the subsequent change in the quality of the extracellular matrix. The correction of POP using an implant intends to provide mechanical support to the pelvic organs and to stimulate a moderate host response. Synthetic polypropylene (PP) implants were commonly used for the correction of prolapse. Although they were successful in providing support, these implants have been associated with clinical complications in the long term due to substantial foreign body response and inappropriate tissue integration. The complications can be avoided or minimized by engineering a biocompatible and fully absorbable implant with optimized mechanical and structural characteristics that favor more appropriate cellular interactions with the implant. Therefore, in this study, we evaluated implants comprised of poly-4-hydroxybutyrate (P4HB), a fully absorbable material with high mechanical strength, as an alternative to PP. The P4HB implants were knitted in four unique designs with different pore shapes ranging from a more rectangular geometry- as it is in PP implant- to a rounded geometry, to determine the effect of the implant structure on the textural and mechanical properties and subsequent cell-matrix interaction. The cellular response was investigated by seeding primary vaginal fibroblasts isolated from patients with POP. P4HB favored cellular functions more than PP, as indicated by greater cell attachment and proliferation (P < 0.01), and significantly more collagen deposition (P4HB vs PP, 11.19 μg vs 6.67 μg) at 28 days culture (P < 0.05). All P4HB implants had higher strength and lower stiffness than the PP scaffold. The material and the design of the implant also influenced the behavior of vaginal fibroblasts. The aspect ratio of the vaginal POP fibroblasts cultured on the PP implant (1.61 ± 0.75) was significantly (P < 0.005) smaller than those cultured on P4HB implants (average 2.31 ± 0.09). The P4HB structure with rounded pores showed the lowest stiffness and highest fibroblast attachment and proliferation (P < 0.01). Overall, P4HB induces more matrix deposition compared to PP and knit design can further optimize cell behavior.

Mechanical properties of warp-knitted hernia repair mesh with various boundary conditions

In this paper, two most representative hernia repair meshes were prepared with 0.15 mm polypropylene monofilaments via warp knitting technology, and their mechanical properties were tested in various aspects. Meanwhile, a focused investigation of the boundary conditions between the sutures and the mesh was simulated in several directions innovatively. The results revealed that the hernia repair mesh with different structures has different mechanical properties, and the mechanical properties of standard hernia repair mesh were superior to that of lightweight hernia repair mesh. In order to reduce foreign body sensation and postoperative adverse reactions significantly, the lightweight hernia repair mesh may be preferred. At the same time, the mesh should be placed in the proper direction to comply with the anisotropy of abdominal wall during operation. The area where the hernia mesh is in contact with the sutures was vulnerable to damage. The curved or wrinkled area of the hernia repair mesh increases with the increase of load, which may lead to poor tissue growth, a strong inflammatory response, and even the recurrence of the hernia. Therefore, the hernia repair meshes with different structures may require unique suture techniques. And they also should be further treated prior to implantation. This study provides a theoretical basis for development, utilization and improvement of meshes. Further research will focus on the biomechanical properties of the mesh after implantation in vivo studies.

Prospective ultrasonographic follow-up of transvaginal lightweight meshes: a 1-year multicenter study

INTRODUCTION AND HYPOTHESIS

The use of new lightweight meshes in pelvic organ prolapse (POP) surgery may reduce complications related to mesh retraction (chronic pain, dyspareunia, and mesh exposure). The aim of this study was to investigate changes in the area and position of Uphold Lite™ mesh 6 weeks and 12 months after anterior and/or apical prolapse repair.

METHODS

This observational prospective multicenter study included patients who had undergone transvaginal surgery for symptomatic POP-Q stage ≥ II anterior and/or apical compartment prolapse with placement of Uphold Lite mesh. The dimensions and position of the mesh were evaluated at 6 weeks and 12 months by ultrasonography. Correlations between ultrasonographic mesh characteristics and POP recurrence were analyzed.

RESULTS

Fifty evaluable women with an average age of 66.8 years were included. No statistically significant difference in mesh area was found between week 6 and month 12 postoperatively, either at rest (1746.92 vs. 1574.48 mm²; p = 0.15) or on Valsalva (1568.81 vs. 1542.98 mm²; p = 0.65). The ROC-AUC of the distance between the mesh and the bladder neck (M-BN) at 6 weeks for predicting cystocele recurrence at 12 months was 0.764 (95% CI 0.573-0.955) at rest and 0.724 (95% CI 0.533-0.916) on Valsalva. An M-BN distance > 12.5 mm could predict cystocele recurrence at month 12 with a sensitivity of 80% and a specificity of 69%.

CONCLUSIONS

Ultrasonographic measurements of the Uphold Lite™ mesh appear to remain stable between 6 weeks and 12 months postoperatively. M-BN distance correlates with cystocele recurrence. These results appear to confirm the value of ultrasound in mesh evaluation.

Immunochemical analysis on polypropylene mesh: does mesh size make a difference?

INTRODUCTION AND HYPOTHESIS

The aim of the study is to demonstrate the impact of the size of implanted mesh in relation to its immunohistochemical reaction implanted into animal models.

METHODS

An experimental study utilizing 54 female Sprague Dawley (SD) rats was divided into five groups: control, sham, and study groups (mesh-small [M-S], mesh-medium [M-M], mesh-large [M-L]). The M-S group used a mesh size of 0.2 × 0.2 cm, the M-M group a mesh size of 0.5 × 0.5 cm, and the M-L a mesh size of 0.7 × 1.0 cm. The sham group underwent vaginal dissection with no mesh implantation. The rats were sacrificed using isoflurane overdose on days 7 and 30. The mesh with the surrounding vaginal and bladder wall tissues were removed and processed for histochemical and western blot analysis.

RESULTS

There is a significant increase in IL-1 and TNF-α immunoreactivity in the M-M and M-L groups on day 7 when compared with the sham group with p values of 0.001 and < 0.001 respectively. M-L showed significantly higher immunoreactivity to TNF-α persisting until day 30. All study groups presented a significantly higher immunoreactivity to MMP-2 and NGF on day 7. However, reactivity to NGF does not persist to day 30 in all groups. Immunoreactivity to CD 31 on days 7 and 30 appears significantly greater in the M-M and M-L groups, with the reaction in the M-L group continuing until day 30.

CONCLUSION

Mesh size is directly proportional to the inflammatory reaction in the host tissue. The prolonged inflammatory process leads to delayed tissue remodeling and angiogenesis, which could delay mesh-tissue integration.

Is antibiotic prophylaxis necessary in mid-urethral sling surgery?

Introduction and hypothesis

Antibiotic prophylaxis is commonly used when implanting a mid-urethral sling (MUS) for female stress urinary incontinence. Use of antibiotics may lead to adverse events and the development of antibiotic resistance. This study compared a variety of outcomes after MUS surgery with and without antibiotic prophylaxis using data from the national Norwegian Female Incontinence Registry.

Methods

Preoperative and 6–12 months postoperative subjective and objective data from 28,687 patients who received MUS surgery from 1998 through 2017 were extracted from the registry. Categorical outcomes were compared between women with or without antibiotic prophylaxis using chi-square test for independence. Primary outcome was incidence of postoperative surgical site infection (SSI). Secondary outcomes were incidence of tape exposure, de novo or persistent urgency urinary incontinence, postoperative pain > 3 months, subjective and objective cure rates, and patient satisfaction.

Results

Antibiotic prophylaxis was used in 9131 and not used in 19,556 patients. SSIs and prolonged postoperative pain occurred significantly more often without antibiotic prophylaxis. Subjective and objective cure rates were significantly higher and tape exposures significantly lower in women not receiving prophylactic antibiotics. There were no significant differences in other outcomes.

Conclusions

Antibiotic prophylaxis resulted in fewer women developing postoperative infections or prolonged postoperative pain after MUS surgery, but did not offer protection against tape exposure. The differences in cure rates were small and probably without clinical relevance. If a small increase in surgical site infections is accepted, the routine use of antibiotic prophylaxis can probably be omitted.

Could polypropylene mesh impair male reproductive organs? Experimental study with different methods of implantation

PURPOSE

To evaluate the vas deferens and testicles of rats submitted to bilateral inguinotomy and polypropylene (PP) mesh placement.

METHOD

Sixty Wistar rats were randomized into three groups: Control (inguinotomy only), mesh placement over the vas deferens (Mesh-DD) or under the spermatic funiculus (Mesh-SF). The following analyses were performed: vas deferens morphometry (lumen area and wall thickness), quantification of collagen fibers, spermatogenesis, apoptosis (cleaved caspase-3 and TUNEL) and cellular proliferation (Ki67). Quantitative gene expression (qPCR) for apoptosis and inflammatory cytokines were evaluated by RT-PCR.

RESULTS

In the apoptosis pathway, Mesh-DD showed one upregulated gene (Il10) and three downregulated genes (Fadd, Tnfrsf1b and Xiap). In Mesh-SF, 17 genes were downregulated. In the inflammation pathway (Mesh-DD), one gene was upregulated (Il1r1), and one gene was downregulated (Ccl12). In Mesh-SF, three genes were upregulated (Il1r1, Tnfsf13b and Csf1), and two were downregulated (Ccl12 and Csf2). PP mesh placement preserved spermatogenesis and did not alter the vas deferens or the testicle. In the ductus deferens, there was reduced luminal area (30 days), increased wall thickness (90 days), and increased type III collagen and cell proliferation (30 and 90 days) (p < 0.05). In the testicle, cell proliferation was greater in the Mesh-DD (p < 0.05).

CONCLUSIONS

PP mesh, whether or not in direct contact with spermatic funicular structures, induces changes that were not sufficient to cause damage to the evaluated organs.

Historic transvaginal meshes and procedures: what did my patient have done?

PURPOSE OF REVIEW

Transvaginal mesh kits were widely used to treat pelvic organ prolapse for over a 10-year period in the early 2000s. Due to safety concerns and FDA regulations, these mesh kits are no longer available for use. Thus, current Obstetricians and Gynecologists are likely to encounter these meshes, but may have no previous experience or exposure to the devices making it difficult to adequately monitor, counsel, and care for patients that underwent these types of procedures. This review highlights the most commonly used transvaginal mesh kit types, provides insight into signs and symptoms related to transvaginal mesh complications, and provides guidance for management of mesh complications.

RECENT FINDINGS

Not all transvaginal mesh will give rise to a complication. If complications do occur, treatment options range from conservative observation to total mesh excision. Management must be customized to an individual patient's needs and goals.

SUMMARY

Transvaginal mesh kits promised increased durability of surgical repair for pelvic organ prolapse. Safety concerns over time caused these kits to no longer be available for use. Practicing Obstetricians and Gynecologists should be aware of the history of transvaginal mesh and the signs and symptoms of mesh complications.

The in vivo biocompatibility of titanized polypropylene lightweight mesh is superior to that of conventional polypropylene mesh

OBJECTIVE

To evaluate the histological response to and changes in the biomechanical properties of titanized polypropylene lightweight mesh and conventional polypropylene mesh at 1 and 12 weeks following implantation in the sheep vagina.

METHODS

We compared a titanized polypropylene lightweight mesh (TiLOOP Mesh) to a conventional polypropylene mesh (Gynemesh PS) in a sheep vagina model. Explants were harvested after 1 and 12 weeks (n = 6/mesh type/time point) for histological observation. After 12 weeks, mesh-tissue complex specimens were biomechanically assessed by a uniaxial tension system.

RESULTS

One week after implantation, there was no significant difference in the inflammatory response between the two groups. Twelve weeks after implantation, the TiLOOP light mesh elicited a lower inflammatory response than was observed for the Gynemesh PS (1.44 ± 0.61 vs 2.05 ± 0.80, P = .015). Twelve weeks after implantation, the collagen I/III ratio was lower in the TiLOOP light mesh group than in the Gynemesh PS group (9.41 ± 5.06 vs 15.21 ± 8.21, P = .019). The messenger RNA expression levels of the inflammatory factors interleukin 10 and tumor necrosis factor α were lower in the TiLOOP Mesh group than in the Gynemesh PS group at both 1 and 12 weeks (P < .05). There were no significant differences in any of the evaluated biomechanical characteristics between the two meshes (P > .05).

CONCLUSION

Although the titanized polypropylene lightweight mesh induces slightly less tissue reactivity and has better in vivo biocompatibility, further studies should be conducted including the complications and the success rate of pelvic organ prolapse in patients before recommending it in pelvic floor reconstruction.

Experimental study of a new original mesh developed for pelvic floor reconstructive surgery

INTRODUCTION AND HYPOTHESIS

Most synthetic meshes used in transvaginal surgery are made of polypropylene, which has a stable performance, but does not easily degrade in vivo. However, mesh-related complications are difficult to address and have raised serious concerns. A new biomaterial mesh with good tissue integration and few mesh-related complications is needed. To evaluate the effect of a new bacterial cellulose (BC) mesh on pelvic floor reconstruction following implantation in the vagina of sheep after 1 and 12 weeks.

METHODS

The meshes were implanted in the submucosa of the posterior vagina wall of sheep. At 1 and 12 weeks after surgery, mesh-tissue complex (MTC) specimens were harvested for histological studies and biomechanical evaluation. At 12 weeks after surgery, MTC specimens were biomechanically assessed by a uniaxial tension "pulley system".

RESULTS

The BC mesh elicited a higher inflammatory response than Gynemesh™PS at both 1 and 12 weeks after implantation. Twelve weeks after implantation, the BC mesh resulted in less fibrosis than Gynemesh™PS. Compared with the Gynemesh™PS group, the BC mesh group had increased mRNA expression of MMP-1, MMP-2, and MMP-9 (P < 0.05), but decreased expression of the anti-inflammatory factor IL-4 (P < 0.05). Twelve weeks after implantation, the ultimate load and maximum elongation percentage of the BC mesh were significantly lower than those of Gynemesh™PS.

CONCLUSIONS

The BC mesh could not be a promising biomaterial for pelvic floor reconstructive surgery unless the production process and parameters were improved.

Polydopamine-Inspired Surface Modification of Polypropylene Hernia Mesh Devices via Cold Oxygen Plasma: Antibacterial and Drug Release Properties

Mesh infection is a major complication of hernia surgery after polypropylene (PP) mesh implantation. Modifying the PP mesh with antibacterial drugs is an effective way to reduce the chance of infection, but the hydrophobic characteristic of PP fibers has obstructed the drug adhesion. Therefore, to prepare antimicrobial PP mesh with a stable drug coating layer and to slow the drug release property during the hernia repair process has a great practical meaning. In this work, PP meshes were coated by bio-inspired polydopamine (PDA), which can load and release levofloxacin. PP meshes were activated with cold oxygen plasma and then plasma activated PP fibers were coated with PDA. The PDA coated meshes were further soaked in levofloxacin. The levofloxacin loaded PP meshes demonstrate excellent antimicrobial properties for 6 days and the drug release has lasted for at least 24 h. Moreover, a control PP mesh sample without plasma treatment was also prepared, after coating with PDA and loading levofloxacin. The antimicrobial property was sustained only for two days. The maximum inhibition zone of PDA coated meshes with and without plasma treatment was 12.5 and 9 mm, respectively. On all accounts, the modification strategy can facilely lead to long-term property of infection prevention.

One-Step Surface Functionalized Hydrophilic Polypropylene Meshes for Hernia Repair Using Bio-Inspired Polydopamine

An ideal hernia mesh is one that absorbs drugs and withstands muscle forces after mesh implantation. Polypropylene (PP) mesh devices have been accepted as a standard material to repair abdominal hernia, but the hydrophobicity of PP fibers makes them unsuitable to carry drugs during the pre-implantation of PP meshes. In this study, for the first time, one-step functionalization of PP mesh surfaces was performed to incorporate bio-inspired polydopamine (PDA) onto PP surfaces. All PP mesh samples were dipped in the same concentration of dopamine solution. The surface functionalization of PP meshes was performed for 24 h at 37 °C and 80 rpm. It was proved by scanning electron microscopic (SEM) images and Fourier Transform Infrared Spectroscopy (FTIR) results that a thin layer of PDA was connected with PP surfaces. Moreover, water contact angle results proved that surface functionalized PP meshes were highly hydrophilic (73.1°) in comparison to untreated PP mesh surfaces (138.5°). Thus, hydrophilic PP meshes with bio-inspired poly-dopamine functionalization could be a good choice for hernia mesh implantation.

Surgery for Apical Vaginal Prolapse after Hysterectomy: Transvaginal Mesh-Based Repair

Several transvaginal mesh products have been marketed to address vaginal vault prolapse. Although data are limited, prolapse recurrence rates and subjective outcome measures seem to be equivalent for vaginal mesh compared with native tissue apical prolapse repair, and the different vaginal meshes have not proven superior to one another. Given the known unique complications specific to vaginal mesh with equivalent outcomes for the apical vaginal prolapse, it is reasonable to reserve mesh use for specific high-risk cases, such as patients with large apical prolapse recurrence after native tissue repair who are not candidates for sacrocolpopexy.

Pro - inflammatory cytokines and metalloproteinase activation in polypropylene mesh implant in rat subcutaneous tissue

AIMS AND OBJECTIVES

Polypropylene meshes have been increasingly adopted for correction of pelvic organ prolapse due to its lower recurrence rate when compared to surgeries without meshes. The study of the interaction of these materials with the host tissue may contribute to the development of materials with best biocompatibility and, consequently, less complication rates.

MATERIALS AND METHODS

The present study compares the inflammatory reaction of standard-weight (SW) and lightweight (LW) meshes (72 g/m216g/m2 respectively), implanted in the abdomen of 20 adult rats, which were euthanized in four or 30 days. Quantification of pro-inflammatory markers, IL-1 and TNF-α, and of metalloproteinases, MMP2 and MMP3, were carried out through immunohistochemistry with AxioVision ® software.

RESULTS

There were no significant differences in the quantification of IL-1 and TNF-α in LW versus SW meshes. However, IL-1 quantification increased along time (30 days >4 days, p=0.0269). Also, MMP-2 quantification was similar to SW and LW and both presented a significant increase along time (30 days >4 days, p < 0.0001). MMP-3 quantification also showed no difference between the SW and LW groups, but increased along time (30 days >4 days, p=0.02).

CONCLUSIONS

Mesh's density did not influence the quantification of pro-inflammatory cytokines IL-1 and TNF-α and metalloproteinases 2 and 3. The increased expression of IL-1, MMP-2 and MMP-3 over time could represent a longstanding inflammatory response after PP mesh implantation. Possibly, the occurrence of adverse events following PP prosthetic implants can be influenced by other factors, not solely related to the amount of implanted material.

Effects of mesh-related complications in vaginal surgery on quality of life

Introduction and hypothesis

Vaginal mesh surgery is subject of debate due to the impact of mesh-related complications on patient’s lives. Not all of these complications are symptomatic. Restoration of the anatomy and improvement of pelvic floor function as a result may counter the experienced discomfort related to adverse events. We hypothesized that health-related quality of life (HR-QoL) is comparable in women after vaginal mesh surgery regardless of the presence or absence of a mesh-specific complication.

Methods

This was a cross-sectional study of 128 women who had vaginal mesh surgery in a Dutch university hospital between 2007 and 2012. HR-QoL was measured in women with and without mesh complications using standardized QoL questionnaires Urogenital Distress Inventory-6 (UDI-6), Incontinence Impact Questionnaire (IIQ), Defecation Distress Inventory (DDI), and Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Questionnaire (PISQ-12). Complications were scored according to the International Urogynecological Association (IUGA) complication classification. Comparisons between groups were performed with Student’s t test and analysis of variance (ANOVA) test.

Results

In 29 (23%) women, a mesh-related complication occurred. The domain scores of the UDI-6, DDI, IIQ, and PISQ showed no statistically significant differences between women with and without a mesh-related complication. A post hoc analysis showed similar HR-QoL for those in whom the complication had been resolved and those with persistent symptoms of the complication.

Conclusion

Mesh surgery imposes specific complications. When counseling patients about the potential adverse events related to vaginal mesh surgery, it is important to inform them that mesh-related complications do not negatively affect QoL related to micturition, defecation, and sexual functioning.

Exploring the basic science of prolapse meshes

PURPOSE OF REVIEW

Polypropylene mesh has been widely used in the surgical repair of pelvic organ prolapse. However, low but persistent rates of complications related to mesh, most commonly mesh exposure and pain, have hampered its use. Complications are higher following transvaginal implantation prompting the Food and Drug Administration to release two public health notifications warning of complications associated with transvaginal mesh use (PHN 2008 and 2011) and to upclassify transvaginal prolapse meshes from Class II to Class III devices. Although there have been numerous studies to determine the incidence and management of mesh complications as well as impact on quality of life, few studies have focused on mechanisms.

RECENT FINDINGS

In this review, we summarize the current understanding of how mesh textile properties and mechanical behavior impact vaginal structure and function, as well as the local immune response. We also discuss how mesh properties change in response to loading.

SUMMARY

We highlight a few areas of current and future research to emphasize collaborative strategies that incorporate basic science research to improve patient outcomes.

Generation and Evaluation of Novel Stromal Cell-Containing Tissue Engineered Artificial Stromas for the Surgical Repair of Abdominal Defects

Repair of abdominal wall defects is one of the major clinical challenges in abdominal surgery. Most biomaterials are associated to infection and severe complications, making necessary safer and more biocompatible approaches. In the present work, the adequate mechanical properties of synthetic polymer meshes with tissue-engineered matrices containing stromal mesenchymal cells is combined to generate a novel cell-containing tissue-like artificial stroma (SCTLAS) for use in abdominal wall repair. SCTLAS consisting on fibrin-agarose hydrogels seeded with stromal cells and reinforced with commercial surgical meshes (SM) are evaluated in vitro and in vivo in animal models of abdominal wall defect. Inflammatory cells, collagen, and extracellular matrix (ECM) components are analyzed and compared with grafted SM. Use of SCTLAS results in less inflammation and less fibrosis than SM, with most ECM components being very similar to control abdominal wall tissues. Cell migration and ECM remodeling within SCTLAS is comparable to control tissues. The use of SCTLAS could contribute to reduce the side-effects associated to currently available SM and regenerated tissues are more similar to control abdominal wall tissues. Bioengineered SCTLAS could contribute to a safer treatment of abdominal wall defects with higher biocompatibility than currently available SM.

Bioerosion of Synthetic Sling Explants

This study was performed to investigate the changes over time in polypropylene (PP) mesh explants from women with stress urinary incontinence originally treated with a midurethral PP sling. Following Institutional Review Board (IRB) approval, 10 PP explants removed for pain or obstructive symptoms between January and June 2016 were analyzed through various techniques to determine the degradation of the material in vivo. Exclusion criteria were exposed or infected mesh sling or sling in place for less than six months. One pristine control was studied for comparison. The explant samples were analyzed with scanning electron microscopy to visualize the surface defects as well as infrared spectroscopy and energy dispersive X-ray spectroscopy to determine if the degradation was oxidative in nature. The results show qualitative and quantitative bioerosion over the surface of the explant samples and an increase in the content of oxygen pointing toward oxidative degradation occurring in vivo.

Hips, Knees, and Hernia Mesh: When Does Gender Matter in Surgery?

This paper draws attention to gendered dimensions of surgical device failure, focusing on two case studies—hernia repair mesh for pelvic organ prolapse, and metal-on-metal hip implants. We explore possible reasons for higher rates of harms to women, including systematic biases in health research and device regulation. Given that these factors are readily identifiable, we look to feminist scholarship to understand what might maintain them, including the role of cultural factors within surgery, such as gendered communication patterns and sexism. We then canvas potential measures to mitigate the increased risk of harms faced by women who use implanted devices.

Textile properties of synthetic prolapse mesh in response to uniaxial loading

BACKGROUND

Although synthetic mesh is associated with superior anatomic outcomes for the repair of pelvic organ prolapse, the benefits of mesh have been questioned because of the relatively high complication rates. To date, the mechanisms that result in such complications are poorly understood, yet the textile characteristics of mesh products are believed to play an important role. Interestingly, the pore diameter of synthetic mesh has been shown to impact the host response after hernia repair greatly, and such findings have served as design criteria for prolapse meshes, with larger pores viewed as more favorable. Although pore size and porosity are well-characterized before implantation, the changes in these textile properties after implantation are unclear; the application of mechanical forces has the potential to greatly alter pore geometries in vivo. Understanding the impact of mechanical loading on the textile properties of mesh is essential for the development of more effective devices for prolapse repair.

OBJECTIVE

The objective of this study was to determine the effect of tensile loading and pore orientation on mesh porosity and pore dimensions.

STUDY DESIGN

In this study, the porosity and pore diameter of 4 currently available prolapse meshes were examined in response to uniaxial tensile loads of 0.1, 5, and 10 N while mimicking clinical loading conditions. The textile properties were compared with those observed for the unloaded mesh. Meshes included Gynemesh PS (Ethicon, Somerville, NJ), UltraPro (Artisyn; Ethicon), Restorelle (Coloplast, Minneapolis, MN), and Alyte Y-mesh (Bard, Covington, GA). In addition to the various pore geometries, 3 orientations of Restorelle (0-, 5-, 45-degree offset) and 2 orientations of UltraPro (0-, 90-degree offset) were examined.

RESULTS

In response to uniaxial loading, both porosity and pore diameter dramatically decreased for most mesh products. The application of 5 N led to reductions in porosity for nearly all groups, with values decreasing by as much as 87% (P < .05). On loading to 10 N of force, nearly all mesh products that were tested were found to have porosities that approached 0% and 0 pores with diameters >1 mm.

CONCLUSION

In this study, it was shown that the pore size of current prolapse meshes dramatically decreases in response to mechanical loading. These findings suggest that prolapse meshes, which are more likely to experience tensile forces in vivo relative to hernia repair meshes, have pores that are unfavorable for tissue integration after surgical tensioning and/or loading in urogynecologic surgeries. Such decreases in pore geometry support the hypothesis that regional increases in the concentration of mesh leads to an enhanced local foreign body response. Although pore deformation in transvaginal meshes requires further characterization, the findings presented here provide a mechanical understanding that can be used to recognize potential areas of concern for complex mesh geometries. Understanding mesh mechanics in response to surgical and in vivo loading conditions may provide improved design criteria for mesh and a refinement of surgical techniques, ultimately leading to better patient outcomes.

BIOMECHANICAL PROPERTIES OF MESHES FOLLOWING IMPLANTATION IN THE RAT ABDOMINAL WALL MODEL

The objective of our study was to (1) evaluate mesh strength and collagen incorporation after 4 and 12 weeks of implantation in a rat abdominal wall model and (2) determine the relationship between collagen deposition and mechanical strength of a chitosan-coated polypropylene mesh. We implanted 0.5% chitosan-coated polypropylene mesh (PPM), collagen-coated PPM (PelvitexTM; C.R. Bard), and PPM (Avaulta Solo[Formula: see text]; C.R. Bard) using a rat abdominal defect model. Mechanical properties were determined from uniaxial tensile testing and collagen deposition of each mesh was evaluated 4 and 12 weeks post-implantation. We found that after implantation, the neo tissue of Ch-PPM is stiffer than the commercially available meshes. We also observed no significant difference in the ratio of collagen types I/III between mesh samples at 4 weeks or 12 weeks. We found no relationship between the ratio of collagen types I/III and the mechanical strength of mesh samples after implantation. The increased stiffness with chitosan coating could be due to increased muscle tissue ingrowth.

Physical Characteristics of Medical Textile Prostheses Designed for Hernia Repair: A Comprehensive Analysis of Select Commercial Devices

Inguinal hernia repairs are among the most frequent operations performed worldwide. This study aims to provide further understanding of structural characteristics of hernia prostheses, and better comprehensive evaluation. Weight, porosity, pore size and other physical characteristics were evaluated; warp knitting structures were thoroughly discussed. Two methods referring to ISO 7198:1998, i.e., weight method and area method, were employed to calculate porosity. Porosity ranged from 37.3% to 69.7% measured by the area method, and 81.1% to 89.6% by the weight method. Devices with two-guide bar structures displayed both higher porosity (57.7%–69.7%) and effective porosity (30.8%–60.1%) than single-guide bar structure (37.3%–62.4% and 0%–5.9%, respectively). Filament diameter, stitch density and loop structure combined determined the thickness, weight and characteristics of pores. They must be well designed to avoid zero effective porosity regarding a single-bar structure. The area method was more effective in characterizing flat sheet meshes while the weight method was perhaps more accurate in describing stereoscopic void space for 3D structure devices. This article will give instructive clues for engineers to improve mesh structures, and better understanding of warp knitting meshes for surgeons.

New strategies to improve results of mesh surgeries for vaginal prolapses repair--an update

The use of meshes has become the first option for the treatment of soft tissue disorders as hernias and stress urinary incontinence and widely used in vaginal prolapse's treatment. However, complications related to mesh issues cannot be neglected. Various strategies have been used to improve tissue integration of prosthetic meshes and reduce related complications. The aim of this review is to present the state of art of mesh innovations, presenting the whole arsenal which has been studied worldwide since composite meshes, coated meshes, collagen's derived meshes and tissue engineered prostheses, with focus on its biocompatibility and technical innovations, especially for vaginal prolapse surgery.