Polyvinylidene Fluoride Mesh Research Articles

Fixation of polyvinylidene fluoride (PVDF) mesh with cyanoacrylate-derived glues in a rat experimental model: histopathologic immunohistochemical and morphometric study.

The use of cyanoacrylate (CA)-based tissue adhesives for mesh fixation in abdominal hernia repair is increasing due to the fast action and bond strength of these glues. The aim of the present study was to assess tissue changes induced by different CA glues used for mesh fixation in an animal model. Parietal defects were induced in the abdominal wall of 60 rats and repaired by polyvinylidene fluoride (PVDF) mesh fixation using different CA glues. At 1, 7, 15, and 30days post-surgery, macroscopic and histopathological studies were performed to evaluate mesh adhesion, the presence of complications and the tissue response. All meshes were successfully fixed without signs of inflammatory reaction, displacement or detachment. In areas where CA adhesives were applied, the acute tissue response was limited and transient. At 7days post-surgery, collagen fibril production around prosthetic materials was observed, and collagen maturation was achieved at 30days post-surgery. Good mesh incorporation was detected with all three glues, but the application of Glubran-2 was associated with an early macrophagic response and the early production and maturation of collagen fibrils. Our study confirmed that CA tissue adhesives induced the good incorporation of prosthetic mesh within host tissue with a low incidence of complications and reduced acute tissue reaction. At 30days post-surgery no signs of mesh disinsertion or migration were observed, the prosthetic mesh adhesion was due to the presence of a dense mature connective tissue rich in type I collagen fibres.

Standardizing abdominal sacrocolpopexy for the treatment of apical prolapse: One year on.

To determine the safety and efficacy of a standardized bilateral abdominal sacrocolpopexy using polyvinylidene fluoride mesh 1-year post-operatively. In a retrospective observational study of women undergoing bilateral abdominal sacrocolpo/cervicopexy between July 2013 and October 2016 at the Norfolk and Norwich University Hospital, Norwich, UK, patients were assessed 1 year post-operatively using the International Consultation on Incontinence Questionnaire-Vaginal Symptoms (ICIQ-VS). The study involved 100 women, 93 of whom were followed up 1year post-operatively. The primary outcome was apical prolapse rate, of which there were none. Eight women had anterior and four had posterior wall prolapses; four women required vaginal repairs. Eleven women complained of urinary stress incontinence (six worsening and five de novo) and five had subsequent tension-free vaginal tape procedures. One woman had urethral pain and one had mesh exposure into the vagina. Pre-operatively, mean ICIQ-VS score was 27.87 (standard deviation [SD] 6.8), and at 1year post-operatively it was 5.82 (SD 3.8). Impact on quality of life score dropped by 83.4%, from 8.35 (SD 2.1) to 1.39 (SD 1.1). The modified technique used in the present study retained the advantages of traditional sacrocolpopexy, but required smaller volumes of mesh. We found it to be safe and effective with excellent patient satisfaction at 1year, and providing a promising treatment option for patients suffering from apical prolapse.

A prospective pilot study on MRI visibility of iron oxide-impregnated polyvinylidene fluoride mesh after ventral rectopexy

BackgroundMagnetic resonance imaging (MRI) provides excellent information about pelvic anatomy after ventral rectopexy, but the position of the conventional mesh is not seen constantly. Iron oxide-impregnated polyvinylidene fluoride (PVDF) meshes are proven to have MRI visibility in hernia or vaginal reconstructive surgery. This prospective pilot study was designed to assess the visualization, position, and shape of the magnetic resonance (MR)–visible synthetic pelvic mesh used in minimally invasive ventral rectopexy.MethodsEight patients with pelvic organ prolapse were recruited for laparoscopic (LVMR) or robotic-assisted ventral mesh rectopexy (RVMR) with a synthetic MR–visible PVDF mesh. A follow-up visit was scheduled at 3 months after surgery. MR imaging was performed to evaluate the position and dimensions of the mesh and anatomical result. The visibility of the mesh in each sequence was assessed subjectively.ResultsThe visibility of the mesh was best on T1-weighted flash images. The mesh was also well visualized on T2-weighted sagittal images. T2-weighted images, in general, provided best visualization of the surrounding anatomical structures and enabled assessment of the mesh fixation.ConclusionsT2 sagittal and T1-weighted flash images provide the best information about the position and integrity of the iron oxide-impregnated PVDF mesh after LVMR or RVMR with a short examination time.

Vaginal hysterectomy with bilateral sacrospinous fixation plus an anterior mesh versus abdominal sacrocervicopexy for the treatment of primary apical prolapse in postmenopausal women: a randomized controlled study.

We compared vaginal hysterectomy with bilateral sacrospinous fixation plus an anterior polyvinylidene fluoride mesh versus abdominal sacrocolpopexy for the treatment of primary apical prolapse in postmenopausal women. A prospective, randomized, single-blind, parallel study [Registro Brasileiro de Ensaios Clinicos (REBEC) trial register code RBR-7t6rg2] was performed from October 2015 to May 2016. A total of 71 postmenopausal women with advanced pelvic organ prolapse (POP) and undergoing surgery were randomized to the abdominal sacrocolpopexy (ASC) (n= 36) or the vaginal sacrospinous fixation with anterior mesh (VSF-AM) (n= 35) groups. Pelvic Organ Prolapse Quantification (POP-Q) system classification was performed for objective assessment, and the International Consultation on Incontinence Questionnaire-Vaginal Symptoms (ICIQ-VS), International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF), and International Consultation on Incontinence Questionnaire Overactive Bladder (ICIQ-OAB) questionnaires were filled out for subjective evaluation by women before and 1year after surgery. All procedures were performed by a single surgeon. Both groups had improvement in almost POP-Q points (except for vaginal length in the VSF-AM group) and all ICIQ scores. The ASC group had a longer operative time (129 versus 117min, p= 0.0038) and duration for return to activities (103 versus 57days, p< .05). Four women (11%) in the VSF-AM group were reoperated versus none from the ASC group (p =.05). Although the study did not achieve the planned recruitment, after 12months of follow-up, ASC did not differ from VSF-AM in objective and subjective scores (ICIQ questionnaires; POP-Q measurements). Recovery time was longer after open abdominal surgery.

Blurring the boundary between open abdomen treatment and ventral hernia repair.

Therapeutic approaches for septic open abdomen treatment remain a major challenge with many uncertainties. The most convincing method is vacuum-assisted wound closure with mesh-mediated fascia traction with a protective plastic sheet placed on the viscera. As this plastic sheet and the mesh must be removed before final fascial closure, such a technique only allows temporary abdominal closure. This retrospective study analyzes the results of a modification of this technique allowing final abdominal closure using an anti-adhesive permeable polyvinylidene fluoride (PVDF) mesh. The outcome of all consecutive patients with septic open abdomen treatment at one academic surgical department from January 2013 to June 2015 was retrospectively analyzed. Retrospectively, 57 severely ill consecutive patients with septic open abdomen treatment with a 30-day mortality of 26% and a 2-year mortality of 51% were included in the study. In 26 patients, no mesh was implanted; in 31 patients, mesh implantation was done at median third-look laparotomy, median 5days postoperative. Re-laparotomies after mesh implantation (median n = 2) revealed anastomotic leakage in 16% but no new bowel fistula. In 40% of those patients who had mesh implantation, fascia closure was not achieved and the mesh was left in place in a bridging position avoiding planned ventral hernia. The application of an anti-adhesive PVDF mesh for fascia traction in vacuum-assisted wound closure of septic open abdomen is novel, versatile, and seems to be safe. It offers the highly relevant possibility for provisional and final abdominal closure.

Elastic TPU Mesh as Abdominal Wall Inlay Significantly Reduces Defect Size in a Minipig Model

ABSTRACTBackground: The open abdomen with mesh implantation, followed by early reoperation with fascial closure, is a modern surgical approach in difficult clinical situations such as severe abdominal sepsis. As early fascial closure is not possible in many cases, mesh-mediated fascial traction is helpful for conditioning of a minimized ventral hernia after open abdomen. The aim of this study was to evaluate the clinical utilization of an innovative elastic thermoplastic polyurethane mesh (TPU) as an abdominal wall inlay in a minipig model. Methods: Ten minipigs were divided in two groups, either receiving an elastic TPU mesh or a nonelastic polyvinylidene fluoride (PVDF) mesh in inlay position of the abdominal wall. After 8 weeks, mesh expansion and abdominal wall defect size were measured. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. Results: Eight weeks after abdominal wall replacement, transversal diameter of the fascial defect in the TPU group was significantly smaller than in the PVDF group (4.5 cm vs. 7.4 cm; p = 0.047). Immunhistochemical analysis showed increased Ki67 positive cells (p = 0.003) and a higher number of apoptotic cells (p = 0.047) after abdominal wall replacement with a TPU mesh. Collagen type I/III ratio was increased in the PVDF group (p = 0.011). Conclusion: Implantation of an elastic TPU mesh as abdominal wall inlay is a promising approach to reduce the size of the ventral hernia after open abdomen by mesh-mediated traction. However, this effect was associated with a slightly increased foreign body reaction in comparison to the nonelastic PVDF.

Simplified Laparoscopic Sacrohysteropexy

Study ObjectiveTo demonstrate a simplified technique of performing laparoscopic sacrohysteropexy for uterine prolapse. DesignA technical video demonstrating a simplified method of laparoscopic sacrohysteropexy (Canadian Task force classification level III). SettingThe benign gynecology department at a university hospital. InterventionsA 38-year old woman with grade 3 uterine descent presented requesting surgical management for symptomatic prolapse. ConclusionLaparoscopic sacrohysteropexy is becoming an increasingly popular alternative to hysterectomy to treat uterine prolapse in women. We present a novel approach of performing laparoscopic sacrohysteropexy that differs from previously described methods [1,2]; it is shorter, simpler, and reduces possible complications. Key differences include the mesh type, site of attachment, and dissection of the peritoneum while creating the possibility of future vaginal delivery after pregnancy. Our simplified technique uses a polyvinylidene fluoride mesh woven with a square weave secured to the posterior aspect of the cervix under a layer of visceral peritoneum. Because there is no longitudinal give of the mesh, unlike polypropylene meshes with a diamond weave, a wrap method [2] is not required. No dissection of the broad ligament and bladder is needed, eliminating the risk of bladder perforation and anterior mesh erosion with fewer adhesions and simplifying hysterectomy if required in the future. We also uniquely “tunnel” the peritoneum, reducing the size of defect for suture closure, and reperitonize the mesh. Previous methods restrict cervical dilatation and require women to have cesarean sections. The method described in the video allows women to deliver vaginally and, in the event of late miscarriage, avoid the need for hysterotomy. We have performed 25 cases with 1 mild cystocoele recurrence requiring no surgery, 1 reoperation for posterior compartment repair, and 1 case of cervical elongation requiring Manchester repair. No cases of recurrent uterine prolapse have occurred.

Sacrocolpopexy with polyvinylidene fluoride mesh for pelvic organ prolapse: Mid term comparative outcomes with polypropylene mesh

ObjectiveThe aim of this study was to compare the surgical, anatomical, and functional outcomes of sacrocolpopexy (SCP) using polyvinylidene fluoride (PVDF) mesh versus SCP using the standard polypropylene (PP) mesh. Study designThis was a retrospective single centre case-control study including female patients who underwent laparoscopic or abdominal SCP for POP with either PP (Cousin Biotech®) or PVDF (DynaMesh®-PRS) mesh between March 2005 and May 2015. Anatomical outcomes were assessed by the Pelvic Organ Prolapse Quantification (POP-Q) system. Functional outcomes included voiding and storage urinary symptoms (VS and SS, respectively), urgency and stress urinary incontinence (UUI and SUI) and sexual dysfunction (SD). Symptoms and their impact on patients’ quality of life (QoL) were assessed using validated questionnaires as Incontinence Impact Questionnaire (IIQ-7), Urinary Distress Inventory (UDI-6) and Female Sexual Function Index (FSFI). Global patient perception of improvement (PGI-I questionnaire) and mesh erosion rates were also recorded. ResultsOf the 166 patients enrolled, 136 could be included in the analysis: 73 in the PP group and 63 in the PVDF group. The mean follow-up was 94± 17.31 months for the PP and 25.6± 13.8 months for the PVDF group. There were no statistically significant differences in patient demographics and preoperative clinical characteristics. Postoperative anatomical correction were not significantly different between the two groups. The PVDF group showed superior results in term of storage symptoms (PVDF=0% versus PP=8.2%; p=0.02) and lower rate of sexual dysfunction (PVDF=0% versus PP=16,4%; p=0.001). Only 1 patient in PP group and 2 in PVDF group (p=0.47) presented a mesh exposure. There was no statistical difference in PGI-I scores (PP=1.5±1.0 vs PVDF=1.8±0.5; p=0.40). ConclusionsOur findings suggest that both meshes can be safely and effectively used with good anatomical outcomes. Interestingly, PVDF use was associated with significantly less storage symptoms and sexual dysfunction.

MRI Evaluation of an Elastic TPU Mesh under Pneumoperitoneum in IPOM Position in a Porcine Model

ABSTRACTBackground: The frequency of laparoscopic approaches increased in hernia surgery over the past years. After mesh placement in IPOM position, the real extent of the meshes configurational changes after termination of pneumoperitoneum is still largely unknown. To prevent a later mesh folding it might be useful to place the mesh while it is kept under tension. Conventionally used meshes may lose their Effective Porosity under these conditions due to poor elastic properties. The aim of this study was to evaluate a newly developed elastic thermoplastic polyurethane (TPU) containing mesh that retains its Effective Porosity under mechanical strain in IPOM position in a porcine model. It was visualized under pneumoperitoneum using MRI in comparison to polyvinylidenefluoride (PVDF) meshes with similar structure. Methods: In each of ten minipigs, a mesh (TPU containing or native PVDF, 10 × 20 cm) was randomly placed in IPOM position at the center of the abdominal wall. After 8 weeks, six pigs underwent MRI evaluation with and without pneumoperitoneum to assess the visibility and elasticity of the mesh. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. The degree of adhesion formation was documented. Results: Laparoscopic implantation of elastic TPU meshes in IPOM position was feasible and safe in a minipig model. Mesh position could be precisely visualized and assessed with and without pneumoperitoneum using MRI after 8 weeks. Elastic TPU meshes showed a significantly higher surface increase under pneumoperitoneum in comparison to PVDF. Immunohistochemically, the amount of CD45-positive cells was significantly lower and the Collagen I/III ratio was significantly higher in TPU meshes after 8 weeks. There were no differences regarding adhesion formation between study groups. Conclusions: The TPU mesh preserves its elastic properties in IPOM position in a porcine model after 8 weeks. Immunohistochemistry indicates superior biocompatibility regarding CD45-positive cells and Collagen I/III ratio in comparison to PVDF meshes with a similar structure.

Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo.

In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2 ) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2 ) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2 ) and 221.5 cm2 (± 11.8 cm2 ), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4% for TPU and of 1.2% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827-833, 2018.

Early safety and efficacy outcomes of a novel technique of sacrocolpopexy for the treatment of apical prolapse

ObjectiveTo assess the safety and efficacy of a modified technique of bilateral abdominal sacrocolpopexy in which both uterosacral ligaments are replaced with polyvinylidene fluoride mesh to provide support to the cervix (cervico-sacropexy [CESA]) or vaginal vault (vagino-sacropexy [VASA]). MethodsA retrospective observational study was undertaken of women with posthysterectomy vault prolapse or recurrent apical prolapse following previous prolapse repair who underwent bilateral sacrocolpopexy between July 1, 2013, and December 31, 2014, in a tertiary referral unit in the UK. Before surgery and 3 months afterwards, prolapse was assessed using the Pelvic Organ Prolapse Quantification scale and functional outcomes were recorded using the International Consultation on Incontinence Questionnaire for vaginal symptoms and urinary incontinence. ResultsFifty women were included. At 3 months, 47 (94%) patients reported no bulge symptoms and the mean point C was –7.6. Complications comprised bladder injury in 1 (2%) and minor wound problems in 3 (6%) patients. No mesh erosion was reported. ConclusionBilateral abdominal sacrocolpopexy seems to be a safe and effective option for apical prolapse. Longer-term follow-up is needed to detect prolapse recurrence and mesh-related complications.

Evaluating Alternative Materials for the Treatment of Stress Urinary Incontinence and Pelvic Organ Prolapse: A Comparison of the In Vivo Response to Meshes Implanted in Rabbits

Serious complications can develop with the mesh implants used for stress urinary incontinence and pelvic organ prolapse surgery. We evaluated 2 materials currently in clinical use and 2 alternative materials using a rabbit abdominal model to assess host response and biomechanical properties of the materials before and after implantation. Poly-L-lactic acid and polyurethane meshes were electrospun to be compared to commercially available polypropylene and polyvinylidene fluoride meshes. A total of 40 immunocompetent full-thickness abdominal wall defect rabbit models were used, including 8 in each of the poly-L-lactic acid, polyurethane, polyvinylidene fluoride and polypropylene experimental groups, and sham controls. Two 20 mm defects were created per animal and primarily repaired. The experimental groups then underwent onlay of each repair material while sham controls did not. Four rabbits per group were sacrificed at days 30 and 90. Abdominal wall specimens containing the defect with or without repair material were explanted to be assessed by histology (hematoxylin and eosin staining, and immunohistochemistry) and biomechanical testing at 30 and 90 days. At 90 days of implantation tissues repaired with all 4 materials showed biomechanical properties without significant differences. However, polypropylene and polyvinylidene fluoride meshes demonstrated a sustained chronic inflammatory response profile by 90 days. In contrast, poly-L-lactic acid and polyurethane meshes integrated well into host tissues with a decreased inflammatory response, indicative of constructive remodeling. Poly-L-lactic acid and polyurethane alternative materials achieved better host integration in rabbit models than current synthetic repair materials.

Laparoscopic Technique of Vagino-Sacropexy for Treatment of Vaginal Vault Prolapse and Urinary Urge Incontinence

Introduction: Pelvic organ prolapse is a common problem in women, especially in elderly. Many women with pelvic organ prolapse also suffer from urinary incontinence. Based on the studies of de Lancey, three levels of vaginal support are important for maintaining pelvic organ support and continence.1,2 Uterosacral and cardinal ligaments are the main structures in level 1 support that suspends the cervix and upper vagina. Uterosacral ligaments extend between upper vagina and sacrum at the level of S2 through S4 and maintain length and horizontal axis of the vagina. Horizontal axis of the vagina is essential for continence by supporting bladder base. Laxity or defects in the uterosacral ligaments are frequently associated with apical utero-vaginal descensus, urgency, and urge incontinence.3,4 It was proved that urgency or urge incontinence may be caused by anatomical defects of the posterior compartment and could be treated with surgery.5,6 Vagino-sacropexy (VASA) is a new surgical technique that was described for correcting vaginal stump descensus, prolapse, and/or urge incontinence in a hysterectomized patient.7 Cure rates in urge incontinence were reported as 70% to 77%.7 In this operation, vaginal vault is fixed to sacrum at the level of S2 bilaterally by using a one-piece polyvinylidene fluoride (PVDF) mesh. Although promontory is accepted to be the simplest localization for attachment of mesh in unilateral sacrocolpopexy, it is not the safest area for fixation.8,9 However, bilateral fixation of mesh on S2 results in a more anatomic suspension of vaginal vault when compared with unilateral mesh attachment on sacral promontory. In VASA, restoring vaginal horizontal axis improves urge incontinence. In this video, our aim was to demonstrate the laparoscopic surgical technique of VASA in a hysterectomized patient with vaginal vault prolapse and urge incontinence. According to our knowledge, this is the first report in the literature. Video run time is 05 mins 7 secs. Materials and Methods: Laparaoscopic VASA was performed in a 65-year-old woman with POP-Q stage 4 vaginal prolapse and urge incontinence (Video 1). The purpose of VASA is to re-create synthetic uterosacral ligaments to support vaginal vault by placing a one-piece mesh implant between vaginal cuff and second sacral vertebrae (S2) on the left side and right side of the pelvis. Vaginal part of the mesh implant should be fixed to the vaginal cuff with three or four nonabsorbable or late-absorbable multifilament sutures. Results and Conclusions: Vaginal vault prolapse was corrected anatomically by replacement of uterosacral ligaments with a synthetic PVDF surgical mesh by laparoscopic VASA operation. Postoperative term was uneventful and the patient was discharged at the first day following operation. In the first follow-up visit at 15th day postsurgery, the patient had no symptom of urge incontinence. Long-term anatomic and functional outcomes were also satisfactory. Laparoscopic vagino sacropexy is a little bit more difficult procedure than conventional laparoscopic unilateral sacrofixation because the normal anatomic position of the sigmoid colon challenges the placement of mesh implant on the left side. So, sigmoid colon should be deviated to the right side, and then the left arm of the mesh implant is placed under peritoneum in a similar manner to the right side. In addition, pelvic curve challenges formation of peritoneal tunnels from the sacrum to the level of insertion of uterosacral ligaments on the vaginal cuff, bilaterally. To facilitate this step, we prefer to use a flexible dissector for passing the pelvic curve. If a rigid dissector is used in this step, the peritoneum over the rigid instrument can easily be torn and then shortened. The average time taken to perform laparoscopic VASA is ~90 to 100 minutes and is mainly related to level of expertise. Intermediate or advanced surgical skills in laparoscopic pelvic surgery are required before one may attempt laparoscopic VASA. In conclusion, in surgical treatment of pelvic organ prolapse, pelvic organs should be restored to their original anatomic positions to restore their normal functions. In surgical treatment of apical prolapses, defective uterosacral ligaments should be replaced in original anatomic planes to restore normal bladder functions and improve urge incontinence. Laparoscopic approach for VASA also provides better access and identification of pelvic structures and rapid postoperative recovery. No competing financial interests exist. Runtime of video: 5 mins 7 secs

INDICATIONS AND CHOICE OF TECHNOLOGY FOR POLYMERIC MATERIALS IMPLANTATION IN THE ABDOMINAL WALL FOR PREVENTION AND TREATMENT OF POSTOPERATIVE VENTRAL HERNIAS

The absolute indication for primary covering a laparotomic wound with a synthetic prosthesis is complicated anatomic and functional insufficiency. There are relative indications for this surgery, such as old age, III–IV degree of obesity, repeated laparotomy in location of the same scar, covering a laparostoma in patients treated with programmed sanation of the abdominal cavity and laparotomy in patients treated with radiology or chemotherapy methods. Lowering of functional activity of ribosomal genes is a reason of the anterior abdominal cavity weakness, its progress causes lowering in skin and aponeuroses composition I–III types of collagen. We examined the speed of growing and differentiation of connective tissue after implantation endoprosthesis made of lavsan, polypropylene, polyvinylidene fluoride, polytetrafluoride ethylene. It was proved that the polyvinylidene fluoride mesh had the best biocompatibility. The progress of wound implantation process could be predicted by dynamics of cytokine profile, temperature, leukocyte and exudative reactions of a patient. The best insensitiveness to infection belonged to a standard polypropylene endoprosthesis, it could be used for covering a hernia defect in patients with strangulated hernias. The fact that urine poured into the operation wound during urinary system surgery combined with lateral hernias of abdomen was not a contraindication for endoprosthesis.

Elastic mesh with thermoplastic polyurethane filaments preserves effective porosity of textile implants.

In hernia surgery, meshes with small pores tend to be filled by fibrous tissue, which reduces their stretchability and causes patient complaints. Because of the inelasticity of current meshes, mechanical strain might cause pores to collapse even in large-pore mesh constructions. In this study, a mesh with elastic thermoplastic polyurethane (TPU) filaments was constructed to prevent pore size changes even under mechanical strain, and its biocompatibility in comparison with polyvinylidene fluoride (PVDF) was evaluated. A mesh was constructed using PVDF with elastic TPU filaments and mechanically tested. After midline laparotomy in 20 rabbits, we placed a 15 cm × 3 cm mesh as inlay in the defect. Animals were randomized to either the TPU or PVDF group. After 7 or 21 days, mesh expansion was measured under pneumoperitoneum, and abdominal walls were explanted for immunohistochemical investigations. In vitro, TPU meshes showed a slight reduction in effective porosity from 46% at tension-free conditions to 26% under longitudinal and to 34% under transverse strain. The nonelastic PVDF meshes showed a marked reduction in effective porosity from 70% to 7% and 52%, respectively. The TPU mesh had a breaking elongation of 101% and a tensile strength of 35 N/cm. In vivo, both meshes achieved healing of the incision without hernial defect. The TPU mesh maintained its elasticity under pneumoperitoneum. The amount of CD68-positive, Ki67-positive, and apoptotic cells was significantly lower in the TPU group after 7 and 21 days. The newly developed TPU mesh shows elasticity, structural stability, and preserved effective porosity under mechanical strain. Immunohistochemistry indicates superior biocompatibility of TPU mesh compared with PVDF after 7 and 21 days.

A comparative study of polyvinylidene fluoride and polypropylene hernia meshes in creep behavior and elasticity

Polypropylene (PP) is widely used in hernia repair for its compatibility with most mesh constructions. Polyvinylidene fluoride (PVDF) is a non-absorbable fluoropolymer with improved biostability, lower bending stiffness and less tissue reaction. Creep behavior and elasticity are significant properties of hernia mesh that influence the surgical handling of mesh and the postoperative recurrence. This work compares PVDF monofilament and hernia mesh with PP in creep deformation and elastic recovery percentage. The experimental results indicate that PVDF monofilament and mesh exhibit larger elastic recovery percentage, higher initial elongation and less creep deformation than PP mesh. The creep deformation of PVDF mesh in wale and course directions are 3.19 mm and 5.38 mm, which for PP mesh in wale and course directions are 7.73 mm and 8.30 mm. PVDF mesh has better performance in shape stability and elasticity. Additionally, creep models are used to analyze the experimental data and predict the long-term creep deformation. This method greatly reduces the time of creep experiment. In contrast to the four-element model and the Eyring's model, the modified generalized Maxwell model is more suitable to describe the creep curves of hernia meshes. Better agreements between theoretical and measured creep curves are observed. The predicted results demonstrate that PVDF mesh has better long-term shape stability than PP mesh.

First in vivo visualization of MRI‐visible IPOM in a rabbit model

Application of a mesh in presence of pneumoperitoneum may cause deformation or wave formation when gas is released. Moreover, mesh shrinkage during subsequent wound healing cannot be detected in vivo without invasive diagnostics. Using MRI-visible polyvinylidene fluoride (PVDF) mesh, the extend of mesh deformation and shrinkage could be objectified by MRI for the first time. Laparoscopic intraperitoneal onlay mesh (IPOM) implantation was performed in 10 female rabbits using ferro-oxide loaded PVDF meshes. MRI measurements were performed postoperatively at days 1 and 90. After three-dimensional reconstruction of all MRI images the total surface and the effective surface of the implanted mesh were explored and calculated computer-assisted. In all cases, the mesh could be identified in MRI. The subsequent three-dimensional reconstruction always allowed a calculation of the mesh area. In relation to the original size of the used textile implant, we found neither a significant reduction of the effective mesh surface after release of the pneumoperitoneum at day 1 after laparoscopic surgery nor a significant change of the total surface of this large pore mesh by the end of the observation period. In vivo investigation of mesh surface via MRI could exclude a significant initial reduction of the effective mesh surface after release of pneumoperitoneum, in this IPOM rabbit model. A further subsequent shrinkage of these large pore PVDF meshes could be excluded, as well. Imaging of MRI-visible IPOM mesh turned out to be a sufficient tool to objectify mesh configuration and position in vivo.

Mesh contraction: in vivo documentation of changes in apparent surface area utilizing meshes visible on magnetic resonance imaging in the rabbit abdominal wall model

Our aim was to analyze the apparent contraction of meshes in vivo after abdominal wall reconstruction and evaluate histological and biomechanical properties after explantation. Nine New Zealand female rabbits underwent repair of two full-thickness 25 × 30-mm midline defects in the upper and lower parts of the abdomen. These were primarily overlaid by 35 × 40-mm implants of a polyvinylidene fluoride (PVDF) DynaMesh (n = 6) or polypropylene meshes Ultrapro (n = 6) and Marlex (n = 6). Edges of the meshes were secured with iron(II,III) oxide (Fe(3)O(4))-loaded PVDF sutures. Magnetic resonance images (MRIs) were taken at days 2, 30 and 90 after implantation. The perimeter of the mesh was traced using a 3D spline curve. The apparent surface area or the area within the PVDF sutures was compared with the initial size using the one-sample t test. A two-way repeat analysis of variance (ANOVA) was used to compare the apparent surface area over time and between groups. PVDF meshes and sutures with Fe(3)O(4) could be well visualized on MRI. DynaMesh and Marlex each had a 17 % decrease in apparent surface area by day 2 (p < 0.001 and p = 0.001), respectively, which persisted after day 90. Whereas there was a decrease in apparent surface area in Ultrapro, it did not reach significance until day 90 (p = 0.01). Overall, the apparent surface area decreased 21 % in all meshes by day 90. No differences in histological or biomechanical properties were observed at day 90. There was a reduction in the apparent surface area between implantation and day 2, indicating that most mesh deformation occurs prior to tissue in-growth.

Development of a Composite Degradable/Nondegradable Tissue‐engineered Vascular Graft

The present study aimed to determine the feasibility of constructing a reinforced autologous vascular graft by combining the advantages of fibrin gel as an autologous cell carrier material with the inherent mechanical strength of an integrated mesh structure. It was hypothesized that the mesh and dynamic culture conditions could be combined to generate mechanically stable and implantable vascular grafts within a shorter cultivation period than traditional methods. A two-step moulding technique was developed to integrate a polyvinylidene fluoride (PVDF) mesh (pore size: 1-2 mm) in the wall of a fibrin-based vascular graft (I.D. 5 mm) seeded with carotid myofibroblasts. The graft was cultured under increasing physiological flow conditions for 2 weeks. Histology, burst strength, and suture retention strength were evaluated. Cell growth and tissue development was excellent within the fibrin gel matrix surrounding the PVDF fibers, and tissue structure demonstrated remarkable similarity to native tissue. The grafts were successfully subjected to physiological flow rates and pressure gradients from the outset, and mechanical properties were enhanced by the mesh structure. Mean suture retention strength of the graft tissue was 6.3 N and the burst strength was 236 mm Hg. Using the vascular composite graft technique, the production of tissue engineered, small-caliber vascular grafts with good mechanical properties within a conditioning period of 14 days is feasible.

Ventricular constraint in dilated cardiomyopathy: A new, compliant textile mesh exerts prophylactic and therapeutic properties

Dilated cardiomyopathy is associated with a progressive decrease in cardiac function, leading to end-stage heart failure. We aimed to stop this process by mechanically constraining the heart with a new, compliant textile mesh. In 16 male Munich minipigs (50 +/- 7 kg), dilated cardiomyopathy with congestive heart failure was induced through 4 weeks of rapid ventricular pacing (220 beats/min). In the early-mesh group (n = 8), a polyvinylidene fluoride mesh was positioned around both ventricles before pacing was started. In the other group (n = 8), experimental dilated cardiomyopathy through rapid pacing was induced (no mesh). After mesh grafting, rapid pacing was continued (late mesh). Rapid pacing in the no-mesh group (control group) significantly decreased both systolic (cardiac output, peak systolic pressure, and the derivative of pressure increase [dP/dt(max)]) and diastolic (minimum rate of pressure rise [dP/dt(min)] and left ventricular end-diastolic pressure) variables, whereas these variables remained almost unchanged in the early-mesh group. In the late-mesh group the passive-elastic constraint not only prevented further deterioration but even exerted reverse remodeling to some extent (dP/dt(max) and left ventricular end-diastolic pressure, P < .05). Ventricular constraint with the new mesh seems to be a prophylactic and therapeutic option in cardiac insufficiency caused by ventricular dilation. This passive-elastic cardioplasty induced reverse remodeling of dilated hearts and significantly improved diastolic and systolic ventricular function.