Mechanical properties of synthetic implants used in the repair of prolapse and urinary incontinence in women: which is the ideal material?

Six-year follow-up outcomes of the P(LLA-CL)/Fg bio-patch for anterior vaginal wall prolapse treatment

INTRODUCTION AND HYPOTHESIS

There were few data about the long-term outcomes of bio-compatible patches for pelvic organ prolapse (POP). The efficacy of poly (L-lactide-co-caprolactone) blended with fibrinogen [P(LLA-CL)/Fg] bio-patches were investigated for anterior vaginal wall prolapse treatment in a 6-year follow-up.

METHODS

The P(LLA-CL)/Fg bio-patch was fabricated through electrospinning. Nineteen patients with symptomatic anterior prolapse (Pelvic Organ Prolapse Quantification [POP-Q] stage ≥ 2) were treated with anterior pelvic reconstruction surgery using a P(LLA-CL)/Fg bio-patch and were followed up at 1, 2, 3, 6 months, and 6 years. The primary outcome was objective anatomical cure (anterior POP-Q stage ≤ 1). Secondary outcomes included complications, MRI evaluation, and scores of the Pelvic Floor Impact Questionnaire-7 (PFIQ-7) and the Pelvic Floor Distress Inventory-20 (PFDI-20).

RESULTS

The micro-morphology of the bio-patch resembled the extracellular matrix, which was suitable for the growth of fibroblasts. Sixteen (84.2%) patients were finally assessed, with a mean follow-up of 6.08 ± 0.18 years. The cure rate without anterior prolapse recurrence was 93.8% at 6 years. Compared with baseline, the POP-Q measurements of Aa, Ba, and C points and scores of PFIQ-7 and PFDI-20 manifested significant differences at all times (all p < 0.05). One (5.26%) case of bio-patch-related infection, 1 (5.26%) case of urinary retention, and no exposures and erosion occurred. MRI evaluation showed that the bio-patch gradually degraded to fragments at 1 month and was completely absorbed at 3 months.

CONCLUSIONS

Among long-term follow-ups, anterior pelvic reconstruction surgery with a P(LLA-CL)/Fg bio-patch demonstrated significant improvements in anatomical correction of anterior pelvic prolapse and pelvic function without severe morbidity.

Progress in Niobium Oxide-Containing Coatings for Biomedical Applications: A Critical Review

Typically, pure niobium oxide coatings are deposited on metallic substrates, such as commercially pure Ti, Ti6Al4 V alloys, stainless steels, niobium, TiNb alloy, and Mg alloys using techniques such as sputter deposition, sol-gel deposition, anodizing, and wet plasma electrolytic oxidation. The relative advantages and limitations of these coating techniques are considered, with particular emphasis on biomedical applications. The properties of a wide range of pure and modified niobium oxide coatings are illustrated, including their thickness, morphology, microstructure, elemental composition, phase composition, surface roughness and hardness. The corrosion resistance, tribological characteristics and cell viability/proliferation of the coatings are illustrated using data from electrochemical, wear resistance and biological cell culture measurements. Critical R&D needs for the development of improved future niobium oxide coatings, in the laboratory and in practice, are highlighted.

Development of 3D Printed Biodegradable Mesh with Antimicrobial Properties for Pelvic Organ Prolapse

To address the increasing demand for safe and effective treatment options for pelvic organ prolapse (POP) due to the worldwide ban of the traditional polypropylene meshes, this study introduced degradable polycaprolactone (PCL)/polyethylene glycol (PEG) composite meshes fabricated with melt-electrowriting (MEW). Two PCL/PEG mesh groups: 90:10 and 75:25 (PCL:PEG, wt%) were fabricated and characterized for their degradation rate and mechanical properties, with PCL meshes used as a control. The PCL/PEG composites showed controllable degradation rates by adjusting the PEG content and produced mechanical properties, such as maximal forces, that were higher than PCL alone. The antibacterial properties of the meshes were elicited by coating them with a commonly used antibiotic: azithromycin. Two dosage levels were used for the coating: 0.5 mg and 1 mg per mesh, and both dosage levels were found to be effective in suppressing the growth of S. aureus bacteria. The biocompatibility of the meshes was assessed using human immortalized adipose derived mesenchymal stem cells (hMSC). In vitro assays were used to assess the cell viability (LIVE/DEAD assay), cell metabolic activity (alamarBlue assay) and cell morphology on the meshes (fluorescent and electron microscopy). The cell attachment was found to decrease with increased PEG content. The freshly drug-coated meshes showed signs of cytotoxicity during the cell study process. However, when pre-released for 14 days in phosphate buffered saline, the initial delay in cell attachment on the drug-coated mesh groups showed full recovery at the 14-day cell culture time point. These results indicated that the PCL/PEG meshes with antibiotics coating will be an effective anti-infectious device when first implanted into the patients, and, after about 2 weeks of drug release, the mesh will be supporting cell attachment and proliferation. These meshes demonstrated a potential effective treatment option for POP that may circumvent the issues related to the traditional polypropylene meshes.

An Attempt to Optimize Supercritical CO2 Polyaniline-Polycaprolactone Foaming Processes to Produce Tissue Engineering Scaffolds

Conjugated polymers are biomaterials with high conductivity characteristics because of their molecular composition. However, they are too rigid and brittle for medical applications and therefore need to be combined with non-conductive polymers to overcome or lessen these drawbacks. This work has, consequently, focused on the development of three-dimensional scaffolds where conductive and non-conductive polymers have been produced by combining polycaprolactone (PCL) and polyaniline (PANI) by means of supercritical CO2 foaming techniques. To evaluate their therapeutic potential as implants, a series of experiments have been designed to determine the most influential variables in the production of the three-dimensional scaffolds, including temperature, pressure, polymer ratio and depressurization rate. Internal morphology, porosity, expansion factor, PANI loads, biodegradability, mechanical and electrical properties have been taken as the response variables. The results revealed a strong influence from all the input variables studied, as well as from their interactions. The best operating conditions tested were 70 °C, 100 bar, a ratio of 5:1 (PCL:PANI), a depressurization rate of 20 bar/min and a contact time of 1 h.

Design, mechanical and degradation requirements of biodegradable metal mesh for pelvic floor reconstruction

Pelvic organ prolapse (POP) is the herniation of surrounding tissue and organs into the vagina and or rectum, and is a result of weakening of pelvic floor muscles, connective tissue,...

Biomaterials assisted reconstructive urology: The pursuit of an implantable bioengineered neo-urinary bladder

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

Pelvic organ prolapse meshes: Can they preserve the physiological behavior?

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

Meshy business: MRI and ultrasound evaluation of pelvic floor mesh and slings

Pelvic floor disorders are a complex set of conditions including but not limited to stress urinary incontinence and pelvic organ prolapse that generally affect older and multiparous women. Of the several surgical options available for treatment of these conditions, synthetic mid-urethral slings for stress urinary incontinence and vaginal mesh for pelvic organ prolapse are amenable to imaging evaluation by ultrasound and magnetic resonance imaging techniques. Ultrasound can evaluate the sub- and immediate peri-urethral portions of sling due to its ability to differentiate synthetic material from native tissues with real-time imaging, while MRI is able to better depict the global pelvic floor anatomy and assess the more distant components of mesh and slings material. Given the high prevalence of pelvic floor disorders and complications after surgical repair, it is important that radiologists familiarize themselves with normal and abnormal imaging findings after these procedures. This article provides a review of the spectrum of imaging findings in patients after pelvic floor repair with synthetic mid-urethral slings and vaginal mesh.

A novel antibacterial biomaterial mesh coated by chitosan and tigecycline for pelvic floor repair and its biological performance

The biomaterials composed of mammalian extracellular matrix (ECM) have a great potential in pelvic floor tissue repair and functional reconstruction. However, bacterial infection does cause great damage to the repair function of biomaterials which is the major problem in clinical utilization. Therefore, the development of biological materials with antimicrobial effect is of great clinical significance for pelvic floor repair. Chitosan/tigecycline (CS/TGC) antibacterial biofilm was prepared by coating CS/TGC nanoparticles on mammalian-derived ECM. Infrared spectroscopy, scanning electron microscopy, bacteriostasis circle assay and static dialysis methods were used to characterize the membrane. MTS assay kit and DAPI fluorescence staining were used to evaluate cytotoxicity and cell adhesion. The biocompatibility was assessed by subabdominal implantation model in goats. Subcutaneous antimicrobial test in rabbit back was used to evaluate the antimicrobial and repairing effects on the infected wounds in vivo. Infrared spectroscopy showed that the composite coating had been successfully modified. The antibacterial membrane retained the main structure of ECM multilayer fibers. In vitro release of biomaterials showed sustained release and stability. In vivo studies showed that the antibacterial biological membrane had low cytotoxicity, fast degradation, good compatibility, anti-infection and excellent repair ability.

[Cystocele repair by a light tension-free vaginal mesh: results after 6 years of follow-up]

INTRODUCTION

The objective of this study was to evaluate the long-term anatomical and functional efficacy, but also the safety of tension-free vaginal mesh in cystocele repair.

METHODS

This retrospective and monocentric study included 90 women who underwent a prolapse repair between June 2006 and November 2008. A light-weight polypropylene vaginal mesh (22g/m2, Novasilk COLOPLAST®) was used without any fixation. Females were followed at 1 month, 1 year, 3 years and 6 years. Only long-term results are presented in this study. The anatomical result was assessed by the POP-Q classification and the functional results by standardized symptoms (PFDI-20), sexuality (PISQ-12) and quality of life (PFIQ-7) questionnaires.

RESULTS

6 years after surgery, the follow-up rate was 74%. Anatomically, the prolapse recurrence rate (Ba≥0) was 17% (n=8). Functionally, the overall patient satisfaction rate was 89%. Quality of life and symptoms scores (4,11±8.45 vs. 17.5±14.4 and 35.8±15.9 vs 94±23.4 respectively) were significantly improved (p<0.001). Concerning the prevalence of the complication, the retraction and exposition rate was 1.7% (n=1) and a re-intervention rate was 6.7% (n=4). The rate of de novo dyspareunia was 1.7% (n=1).

CONCLUSION

In this short retrospective series of vaginal mesh interposition for cystocele repair, the prevalence of medium-term patient satisfaction was high.

Deformation of Transvaginal Mesh in Response to Multiaxial Loading

Synthetic mesh for pelvic organ prolapse (POP) repair is associated with high complication rates. While current devices incorporate large pores (>1 mm), recent studies have shown that uniaxial loading of mesh reduces pore size, raising the risk for complications. However, it is difficult to translate uniaxial results to transvaginal meshes, as in vivo loading is multidirectional. Thus, the aim of this study was to (1) experimentally characterize deformation of pore diameters in a transvaginal mesh in response to clinically relevant multidirectional loading and (2) develop a computational model to simulate mesh behavior in response to in vivo loading conditions. Tension (2.5 N) was applied to each of mesh arm to simulate surgical implantation. Two loading conditions were assessed where the angle of the applied tension was altered and image analysis was used to quantify changes in pore dimensions. A computational model was developed and used to simulate pore behavior in response to these same loading conditions and the results were compared to experimental findings. For both conditions, between 26.4% and 56.6% of all pores were found to have diameters <1 mm. Significant reductions in pore diameter were noted in the inferior arms and between the two superior arms. The computational model identified the same regions, though the model generally underestimated pore deformation. This study demonstrates that multiaxial loading applied clinically has the potential to locally reduce porosity in transvaginal mesh, increasing the risk for complications. Computational simulations show potential of predicting this behavior for more complex loading conditions.

Significant Improvement in Quality of Life, Positive Effect on Sexuality, Lasting Reconstructive Result and Low Rate of Complications Following Cystocele Correction Using a Lightweight, Large-Pore, Titanised Polypropylene Mesh: Final Results of a National, Multicentre Observational Study

Introduction Patients who suffer from pelvic organ prolapse can experience severe limitations in their quality of life. To improve the quality of life of women affected and achieve a stable reconstruction, surgical therapy is often indispensable. In conventional prolapse surgery, the rate of recurrence is high. For this reason, alloplastic mesh has been implanted increasingly in recent years to reconstruct the anatomy of the pelvic floor organs. Even if the anatomical result can be significantly improved as a result, the mesh-induced complications have been the subject of controversial discussion. In this national, multicentre study, the quality of life, anatomical result as well as the rate of complications following the implantation of an alloplastic mesh for the correction of a cystocele were investigated. Method Fifty-four patients with symptomatic ≥ grade II were included in this prospective, national, multicentre study. The study participants were implanted with a titanised polypropylene mesh (TiLOOP ^® PRO A, pfm medical ag). The follow-up observation period was 12 months. Primary as well as repeat procedures were taken into account. The anatomic result of the pelvic floor reconstruction was quantified using the POP-Q system. Data on quality of life and sexuality were collected using validated questionnaires. All complications which occurred were documented and evaluated by an independent committee. Results On average, the patients were in line with the census. An improvement in quality of life was able to be determined during the study in all domains investigated (p < 0.001, Wilcoxon test). Minus incorrect entries and incorrect reports, a total of 19 reports of adverse events in 15 patients were evaluated by the end of the study. The rate of recurrence in the anterior compartment was 4.3%. Conclusion In the reconstruction of the anatomical position of the pelvic floor organs given the presence of a symptomatic cystocele, the implantation of a third-generation alloplastic mesh achieves very good results. Affected patients benefit from the anatomical stability as well as a significant improvement in quality of life, whereby the risks are justifiable.

A Study on Laparoscopic Sacral Colpopexy for Uterine Prolapse

Objectives

We sought to describe the perioperative and postoperative adverse events associated with sacral colpopexy and evaluate the surgical outcome, complications, and benefits of laparoscopic sacral fixation for patients with pelvic prolapse.

Methods

Ninety-two women with uterine prolapse underwent sacral colpopexy between January 2011 and September 2016 at Chosun University Hospital. Patients' electronic medical records were investigated for demographic, intraoperative, and postoperative data. Strict definitions were used for all clinically relevant adverse events. Patients' outcomes were documented with 1 self-administered quality of life questionnaires: the Pelvic Floor Distress Inventory-20 focused on symptom distress. The primary analysis looking at perioperative and postoperative adverse events was descriptive and statistics were reported for all groups as n/N (%) with 95% confidence intervals for categorical variables and as mean ± standard deviation and mean (range) for all continuous variables.

Results

Their mean age was 69 ± 8.1 years, mean follow-up duration was 12 months, and mean operating time was 61 minutes. There were seven conversions due to anesthetic or surgical difficulties. Follow-up was performed using a telephone questionnaire and physical examination at 12 months. There were three cases of sacral pain with strong analgesics, one of vaginal erosion, two of transient urinary retentions, one of spondylitis, and two of mesh infection. Of the patients, 98.9% were satisfied with the surgical results, while none complained of sexual dysfunction or problems performing her usual activities.

Conclusions

Laparoscopic sacral colpopexy is a feasible and highly effective technique that offers good long-term results with complication rates similar to those of open surgery with the added benefit of being minimally invasive.

In vitro study of the mechanical performance of hernia mesh under cyclic loading

The use of prostheses for hernia surgery, made from synthetic polymers may lead to development of postoperative complications. The reason for this can be the mismatch of the mechanical properties of meshes and the loads acting on them. The aim of this work was to investigate the behavior of 3 different hernia meshes under in vitro simulated physiological conditions followed by cyclic loadings. Meshes, Ultrapro (poliglecaprone and polypropylene), Dynamesh (polyvinylidenefluoride) and Surgipro (polypropylene) were selected. For in vitro degradation test, samples were kept in alkaline and acid mediums at 37 °C during 42 and 90 days and analyzed in terms of their weight loss and thickness changes. This was followed by cyclic loading in three increasing load stages. The greatest weight loss and thickness reduction were suffered by Ultrapro mesh. The mesh showed pH independent characteristics. Surgipro mesh had pH independent behavior due to the degradation process, with slight weight loss and thickness reduction. The degradation mechanism of Dynamesh is highly dependent on the pH, with acid surrounding medium acting as a degradation catalyst. Mechanical hysteresis was observed in all three meshes. The larger deformations occurred in Surgipro (25%); necking phenomenon was also observed. The deformation of Dynamesh was 22%, the mesh unweaves under applied load and was unable to withstand the third period of cyclic loads. Ultrapro mesh exhibits the lowest level of deformation (10%). Despite the different compositions and architectures of the meshes, all three underwent permanent plastic deformation, which will induce decreased mesh flexibility over time.

Porcine Small Intestinal Submucosa Mesh for Treatment of Pelvic Organ Prolapsed

Background:

Pelvic organ prolapse (POP) is a major health concern that affects women. Surgeons have increasingly used prosthetic meshes to correct POP. However, the most common used is synthetic mesh, and absorbable mesh is less reported. This research aimed to evaluate the clinical effectiveness of porcine small intestinal submucosa (SIS).

Methods:

Consecutive forty POP patients who met the inclusion criteria underwent pelvic reconstruction surgery with SIS between March 2012 and December 2013. The patients’ clinical characteristics were recorded preoperatively. Surgical outcomes, measured by objective and subjective success rates, were investigated. We evaluated the quality of life (QOL) using the Pelvic Floor Distress Inventory-20 (PFDI-20) and the Pelvic Floor Impact Questionnaire-7 (PFIQ-7). Sexual QOL was assessed by the Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Questionnaire-12 (PISQ-12).

Results:

At postoperative 12 months, the subjective recurrence rate (7.5%) was much lower than the objective recurrence rate (40.0%). Postoperatively, no erosion was identified. One underwent a graft release procedure because of urinary retention, and one had anus sphincter reconstruction surgery due to defecation urgency. Another experienced posterior vaginal wall infection where the mesh was implanted, accompanied by severe vaginal pain. Estrogen cream relieved the pain. One patient with recurrence underwent a secondary surgery with Bard Mesh because of stage 3 anterior vaginal wall prolapse. Scoring system of PFDI-20 was from 59.150 ± 13.143 preoperatively to 8.400 ± 4.749 postoperatively and PFIQ-7 was from 73.350 ± 32.281 to 7.150 ± 3.110, while PISQ-12 was from 15.825 ± 4.050 to 12.725 ± 3.471.

Conclusions:

QOL and the degree of subjective satisfaction were significantly improved postoperatively. Anterior repair deserves more attention because of the higher recurrence rate. The long-term follow-up of the patient is warranted to draw firm conclusion.

Biomaterial-Based Approaches to Address Vein Graft and Hemodialysis Access Failures

Veins used as grafts in heart bypass or as access points in hemodialysis exhibit high failure rates, thereby causing significant morbidity and mortality for patients. Interventional or revisional surgeries required to correct these failures have been met with limited success and exorbitant costs, particularly for the US Centers for Medicare & Medicaid Services. Vein stenosis or occlusion leading to failure is primarily the result of neointimal hyperplasia. Systemic therapies have achieved little long-term success, indicating the need for more localized, sustained, biomaterial-based solutions. Numerous studies have demonstrated the ability of external stents to reduce neointimal hyperplasia. However, successful results from animal models have failed to translate to the clinic thus far, and no external stent is currently approved for use in the US to prevent vein graft or hemodialysis access failures. This review discusses current progress in the field, design considerations, and future perspectives for biomaterial-based external stents. More comparative studies iteratively modulating biomaterial and biomaterial-drug approaches are critical in addressing mechanistic knowledge gaps associated with external stent application to the arteriovenous environment. Addressing these gaps will ultimately lead to more viable solutions that prevent vein graft and hemodialysis access failures.

Micro-structural and Biaxial Creep Properties of the Swine Uterosacral-Cardinal Ligament Complex

The uterosacral ligament and cardinal ligament (USL/CL) complex is the major suspensory tissue of the uterus, cervix, and vagina. This tissue is subjected primarily to bi-axial forces in-vivo that significantly alter its structure and dimension over time, compromising its support function and leading to pelvic floor disorders. In this study, we present the first rigorous characterization of the collagen fiber microstructure and creep properties of the swine USL/CL complex by using scanning electron microscopy and planar biaxial testing in combination with three-dimensional digital image correlation. Collagen fiber bundles were found to be arranged into layers. Although the fiber bundles were oriented in multiple directions, 80.8% of them were aligned within ±45[Formula: see text] to the main in-vivo loading direction. The straightness parameter, defined as the ratio of the end-to-end distance of a fiber bundle to its length, varied from 0.28 to 1.00, with 95.2% fiber bundles having a straightness parameter between 0.60 and 1.00. Under constant equi-biaxial loads of 2 and 4 N, the USL/CL complex exhibited significant creep both along the main in-vivo loading direction (the parallel direction) and along the direction perpendicular to it (the perpendicular direction). Specifically, over a 120-min period, the mean strain increased by 20-34[Formula: see text] in the parallel direction and 33-41[Formula: see text] in the perpendicular direction. However, there was no statistically significant difference in creep strains observed after 120 min between the parallel and perpendicular directions for either the 2 or 4 N load case. Creep proceeded slightly faster in the perpendicular direction under the equi-biaxial load of 2 N than under the equi-biaxial load of 4 N ([Formula: see text]). It proceeded significantly faster in the parallel direction under the equi-biaxial loads of 2 N than under the equi-biaxial loads of 4 N ([Formula: see text]). Overall, our findings contribute to a greater understanding of the biomaterial properties of the USL/CL complex that is needed for the development of new surgical reconstruction methods and mesh materials for pelvic floor disorders.

Biomechanical, Topological and Chemical Features That Influence the Implant Success of an Urogynecological Mesh: A Review

Synthetic meshes are normally used to treat several diseases in the field of urogynecological surgery. Not-optimal selection of mesh and/or its not-correct implant may increase patient's pain and discomfort. The knowledge of mechanical behaviour and topological and chemical properties of a mesh plays a fundamental role to minimize patient's suffering and maximize the implant success. We analysed several papers reporting the meshes application for urogynecological pathologies, to extrapolate the principal parameters that normally are used to characterise the biomechanical, topological, and chemical properties, and to verify their influence on implant success. In this way we want demonstrate that, knowing these features, it is possible to foresee the success of a mesh implant. This review shows that the application of a mesh strictly depends on elastic modulus, failure load, porosity and pore size, filament diameter, polymer weight, and crystallinity. To increase the success of the implant and to help choice of optimal mesh for a clinical need, two indexes have been proposed for comparing, in an easier way, the mechanical performance of different commercially available meshes.

Synthetic surgical meshes used in abdominal wall surgery: Part I-materials and structural conformation

Surgical implants are commonly used in abdominal wall surgery for hernia repair. Many different prostheses are currently offered to surgeons, comprising permanent synthetic polymer meshes and biologic scaffolds. There is a wide range of synthetic meshes currently available on the market with differing chemical compositions, fiber conformations, and mesh textures. These chemical and structural characteristics determine a specific biochemical and mechanical behavior and play a crucial role in guaranteeing a successful post-operative outcome. Although an increasing number of studies report on the structural and mechanical properties of synthetic surgical meshes, nowadays there are no consistent guidelines for the evaluation of mechanical biocompatibility or common criteria for the selection of prostheses. The aim of this work is to review synthetic meshes by considering the extensive bibliography documentation of their use in abdominal wall surgery, taking into account their material and structural properties, in Part I, and their mechanical behavior, in Part II. The main materials available for the manufacture of polymeric meshes are described, including references to their chemical composition, fiber conformation, and textile structural properties. These characteristics are decisive for the evaluation of mesh-tissue interaction process, including foreign body response, mesh encapsulation, infection, and adhesion formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 689-699, 2017.

Biomechanical properties of synthetic surgical meshes for pelvic prolapse repair

Synthetic meshes are widely used for surgical repair of different kind of prolapses. In the light of the experience of abdominal wall repair, similar prostheses are currently used in the pelvic region, to restore physiological anatomy after organ prolapse into the vaginal wall, that represent a recurrent dysfunction. For this purpose, synthetic meshes are surgically positioned in contact with the anterior and/or posterior vaginal wall, to inferiorly support prolapsed organs. Nonetheless, while mesh implantation restores physiological anatomy, it is often associated with different complications in the vaginal region. These potentially dangerous effects induce the surgical community to reconsider the safety and efficacy of mesh transvaginal placement. For this purpose, the evaluation of state-of-the-art research may provide the basis for a comprehensive analysis of mesh compatibility and functionality. The aim of this work is to review synthetic surgical meshes for pelvic organs prolapse repair, taking into account the mechanics of mesh material and structure, and to relate them with pelvic and vaginal tissue biomechanics. Synthetic meshes are currently available in different chemical composition, fiber and textile conformations. Material and structural properties are key factors in determining mesh biochemical and mechanical compatibility in vivo. The most significant results on vaginal tissue and surgical meshes mechanical characterization are here reported and discussed. Moreover, computational models of the pelvic region, which could support the surgeon in the evaluation of mesh performances in physiological conditions, are recalled.

Prosthetic Meshes for Repair of Hernia and Pelvic Organ Prolapse: Comparison of Biomechanical Properties

This study aims to compare the mechanical behavior of synthetic meshes used for pelvic organ prolapse (POP) and hernia repair. The analysis is based on a comprehensive experimental protocol, which included uniaxial and biaxial tension, cyclic loading and testing of meshes in dry conditions and embedded into an elastomer matrix. Implants are grouped as POP or hernia meshes, as indicated by the manufacturer, and their stiffness in different loading configurations, area density and porosity are compared. Hernia meshes might be expected to be stiffer, since they are implanted into a stiffer tissue (abdominal wall) than POP meshes (vaginal wall). Contrary to this, hernia meshes have a generally lower secant stiffness than POP meshes. For example, DynaMesh PRS, a POP mesh, is up to two orders of magnitude stiffer in all tested configurations than DynaMesh ENDOLAP, a hernia mesh. Additionally, lighter, large pore implants might be expected to be more compliant, which was shown to be generally not true. In particular, Restorelle, the lightest mesh with the largest pores, is less compliant in the tested configurations than Surgipro, the heaviest, small-pore implant. Our study raises the question of defining a meaningful design target for meshes in terms of mechanical biocompatibility.

High structural stability of textile implants prevents pore collapse and preserves effective porosity at strain

Reinforcement of tissues by use of textiles is encouraged by the reduced rate of recurrent tissue dehiscence but for the price of an inflammatory and fibrotic tissue reaction to the implant. The latter mainly is affected by the size of the pores, whereas only sufficiently large pores are effective in preventing a complete scar entrapment. Comparing two different sling implants (TVT and SIS), which are used for the treatment of urinary incontinence, we can demonstrate that the measurement of the effective porosity reveals considerable differences in the textile construction. Furthermore the changes of porosity after application of a tensile load can indicate a structural instability, favouring pore collapse at stress and questioning the use for purposes that are not “tension-free.”

Transvaginal retropubic sling systems: efficacy and patient acceptability

Stress urinary incontinence is a common, disabling, and costly medical problem that affects approximately 50% of women with urinary incontinence. Suburethral retropubic slings have been developed as a minimally invasive and effective surgical option, and they have been used as a first-line treatment for stress urinary incontinence since 1995. However, complications including vaginal extrusion, erosion, pain, bleeding, infections, lower urinary tract symptoms, urinary retention, and incontinence have been reported with use of the slings. Several companies manufacture sling kits, and the sling kits vary with regard to the composition of the mesh and introducer needle. The aim of this review was to determine which sling kit was most effective for patients, had minimal reported side effects, and was best accepted by patients and surgeons. In a review of the literature, it was found that a total of 38 studies were published between 1995 and 2014 that reported on eight tension-free retropubic sling kits: SPARC, RetroArc, Align, Advantage, Lynx, Desara, Supris, and Gynecare TVT. The Gynecare TVT was the most cited sling kit; the second most cited was the SPARC. This review provides a summary of the studies that have examined positive and negative outcomes of the retropubic tension-free suburethral sling procedure using various sling kits. Overall, the results of the literature review indicated that data from comparisons of the available sling kits are insufficient to make an evidenced-based recommendation. Therefore, the decision regarding which sling kit is appropriate to use in surgery is determined by the medical provider’s preference, training, and past experience, and not by the patient.

The outcome of transobturator anterior vaginal wall prolapse repair using porcine dermis graft: intermediate term follow-up

INTRODUCTION AND HYPOTHESIS

We evaluated the anatomical success and complications of Perigee® with porcine dermis Graft in the repair of anterior vaginal wall prolapse (AVWP) MATERIALS AND METHODS: After Institutional Review Board (IRB) approval, the charts of all patients who underwent AVWP repair using the Perigee/InteXen® kit from July 2005 to July 2009 were reviewed. Patients who had less than 6-month follow-up were excluded. Preoperative data including patient age, previous AVWP repairs, hysterectomy status, preoperative dyspareunia and pertinent physical findings were collected and recorded. Postoperative success was defined as anatomical stage 0 or I using the Pelvic Organ Prolapse Quantification (POP-Q) scoring system. Graft related complications were also recorded.

RESULTS

Out of 89 patients, 69 completed at least 6-month follow-up. Median follow-up was 13 (6-48) months. Seventeen patients (25%) had previous AVWP repair and 32 (46%) had previous hysterectomy. Preoperatively, AVWP stage II was found in 9 (13%), stage III in 27 (39%) and stage IV in 33 (48%) patients. Anatomic success was found in 48 (69%) patients, with 23 (33%) having stage 0 and 25 (36%) stage I AVWP. Intraoperative complications included incidental cystotomy in one patient and bladder perforation in one. Postoperative complications included vaginal exposure and dyspareunia in one case, wound dehiscence in one and tenderness over the graft arm with dyspareunia in one.

CONCLUSIONS

The use of porcine dermis in AVWP repair is safe with minimal graft related complications; however, anatomical success is lower than that reported with the use of synthetic grafts.

Proangiogenic microtemplated fibrin scaffolds containing aprotinin promote improved wound healing responses

Survival of tissue engineered constructs after implantation depends heavily on induction of a vascular response in host tissue, promoting a quick anastomosis of the cellular graft. Additionally, implanted constructs typically induce fibrous capsule formation, effectively preventing graft integration with host tissue. Previously we described the development of a high density microtemplated fibrin scaffold for cardiac tissue engineering applications with tunable degradation and mechanical properties which promoted seeded cell survival and organization in vitro (Thomson et al., Tissue Eng Part A, 2013). Scaffold degradation in vitro was controllable by addition of the serine protease inhibitor aprotinin and/or the fibrin cross-linker Factor XIII (FXIII). The goal of this study was to assess host tissue responses to these fibrin scaffold formulations by determining effects on scaffold degradation, angiogenic responses, and fibrous capsule formation in a subcutaneous implant model. Aprotinin significantly decreased scaffold degradation over 2 weeks of implantation. A significant increase in capillary infiltration of aprotinin implants was found after 1 and 2 weeks, with a significantly greater amount of capillaries reaching the interior of aprotinin scaffolds. Interestingly, after 2 weeks the aprotinin scaffolds had a significantly thinner, yet apparently more cellular fibrous capsule than unmodified scaffolds. These results indicate aprotinin not only inhibits fibrin scaffold degradation, but also induces significant responses in the host tissue. These included an angiogenic response resulting in increased vascularization of the scaffold material over a relatively short period of time. In addition, aprotinin release from scaffolds may reduce fibrous capsule formation, which could help promote improved integration of cell-seeded scaffolds with host tissue.

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.

Seventeen years' follow-up of the tension-free vaginal tape procedure for female stress urinary incontinence

INTRODUCTION AND HYPOTHESIS

The minimally invasive tension-free vaginal tape (TVT) operation has become the "gold standard" of incontinence surgery. The aim of the present study was to evaluate the long-term effect of the tape material and to assess the continence status 17 years after surgery

METHODS

A cohort of 90 women operated upon with the TVT procedure at three Nordic centers has been prospectively followed for 17 years. All of the women alive according to national registries were contacted and invited to visit the clinics for evaluation. Pelvic examination was performed to reveal any adverse effects of the tape material. Objective and subjective continence status were assessed by a cough stress test and the patients' global impression of improvement as well as by condition-specific quality of life questionnaires.

RESULTS

Seventy-eight percent of the potentially assessable women were evaluated either by a clinic visit or by a telephone interview. One case of a minimal, symptom-free tape extrusion was seen. No other tape complications occurred. Over 90 % of the women were objectively continent. Eighty-seven per cent were subjectively cured or significantly improved.

CONCLUSION

The TVT operation is durable for 17 years, with a high satisfaction rate and no serious long-term tape-induced adverse effects.

Robotic sacrocolpopexy: how does it compare with other prolapse repair techniques?

Abdominal sacrocolpopexy has been shown to have the highest, most durable success rates among techniques for apical pelvic organ prolapse repair. Recently, there has been increased application of minimally invasive techniques, such as laparoscopic and robotic approaches, to performing a sacrocolpopexy. We report an overview of the literature in order to compare between robotic sacrocolpopexy and other surgical techniques for the repair of apical pelvic organ prolapse. Our review will include a discussion of operative techniques, anatomic and subjective success rates, costs, and complications.

Mechanical properties of mesh materials used for hernia repair and soft tissue augmentation

Background

Hernia repair is the most common surgical procedure in the world. Augmentation with synthetic meshes has gained importance in recent decades. Most of the published work about hernia meshes focuses on the surgical technique, outcome in terms of mortality and morbidity and the recurrence rate. Appropriate biomechanical and engineering terminology is frequently absent. Meshes are under continuous development but there is little knowledge in the public domain about their mechanical properties. In the presented experimental study we investigated the mechanical properties of several widely available meshes according to German Industrial Standards (DIN ISO).

Methodology/Principal Findings

Six different meshes were assessed considering longitudinal and transverse direction in a uni-axial tensile test. Based on the force/displacement curve, the maximum force, breaking strain, and stiffness were computed. According to the maximum force the values were assigned to the groups weak and strong to determine a base for comparison. We discovered differences in the maximum force (11.1±6.4 to 100.9±9.4 N/cm), stiffness (0.3±0.1 to 4.6±0.5 N/mm), and breaking strain (150±6% to 340±20%) considering the direction of tension.

Conclusions/Significance

The measured stiffness and breaking strength vary widely among available mesh materials for hernia repair, and most of the materials show significant anisotropy in their mechanical behavior. Considering the forces present in the abdominal wall, our results suggest that some meshes should be implanted in an appropriate orientation, and that information regarding the directionality of their mechanical properties should be provided by the manufacturers.

The use of synthetic mesh and the management of mesh extrusion in vaginal surgery

The authors present a review of the literature regarding the management of mesh extrusion in vaginal surgery. As used in traditional surgical techniques, the use of mesh theoretically allows for a broader base of support and eliminates the need to rely on pre-existing weakened fascia. In this article, the different physical properties and types of synthetic mesh used, and their respective advantages and disadvantages in terms of mesh extrusion, are reviewed.

Vaginal mesh repair: is it appropriate for pelvic organ prolapse in a nulliparous female following pelvic ring fracture?

Pelvic organ prolapse (POP) in a nulliparous woman is a rare sequela of high-energy pelvic trauma. We report a case of a 26-year-old nulliparous woman who developed stage III pelvic organ prolapse two decades after pelvic ring disruption. Abdominal wall cervicopexy was performed as a primary procedure by her attending local gynecologist. Recurrence occurred in early postoperative period following which she was referred to our institute. Examination revealed 5-cm pubic symphysis widening and stage III pelvic organ prolapse with deficient perineal body. Widened levator hiatus with atrophic pelvic floor muscles were confirmed on MRI. The patient was successfully managed by sacrospinous hysteropexy using predesigned vaginal mesh kit along with anterior colporrhaphy and colpoperineorrhaphy. Mesh exposure detected at the 6th year of follow-up required partial excision of the exposed mesh.

Vaginal prolapse repair: suture repair versus mesh augmentation: a urogynecology perspective

Based on the growing evidence within our literature, mesh is clearly needed for long-term success for the repair of anterior/apical defects. Clear credentialing and clinical privilege criteria policies are long overdue. Current data are rapidly growing, with level I studies completed that demonstrate that when transvaginal mesh-augmented repair is used in appropriately selected patients for the repair of pelvic organ prolapse, the procedure has a favorable risk/benefit ratio when compared with suture repair. This article highlights the evolving clinical-based experiences of the authors that are primarily grounded in reality-based medicine with the consideration and incorporation of evidence-based medicine.

Uniaxial biomechanical properties of seven different vaginally implanted meshes for pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Recently, numerous type I macroporous polypropylene vaginal meshes have been introduced into the market with little known of their differences.

METHODS

Seven vaginal meshes were obtained and loaded to failure (n = 5/type). Additional cyclic loading determined permanent deformation with submaximal loading.

RESULTS

The load elongation curves demonstrated a bilinear response with lower stiffness (N/mm), followed by higher stiffness. Ascend™ was the stiffest mesh in both regions of the load elongation curve (0.72 and 1.66 N/mm) with the lowest transition to higher stiffness (13.4%). Polyform™ had the highest failure load (53.8 N) while Ultrapro™ had the lowest (7.83 N). Novasilk™ (89.4%) and Ultrapro™ (87.9%) had the highest relative elongations at mesh failure while Ascend™ had the lowest (40.2%). Ascend™ had the least relative elongation after three protocols of cyclic loading (3.0%, 9.8%, and 9.7%).

CONCLUSIONS

Current vaginal meshes demonstrate marked variation in biomechanical characteristics which may impact the in vivo behavior.

Polypropylene mesh and the host response

The use of polypropylene (PP) mesh for pelvic floor repair has been increasing dramatically over the past decade; however, tissue response in humans has not been extensively studied. This review discusses PP mesh and postimplantation host tissue response. Emphasis is placed on studies investigating the relationship between individual mesh properties and specific responses. There is an immediate inflammatory response after PP mesh implantation that lays the framework for tissue ingrowth and subsequent mesh integration. This response varies based on physical properties of individual mesh, such as pore size, weight, coatings, bacterial colonization, and biofilm production.