Long-lasting bioresorbable poly(lactic acid) (PLA<Subscript>94</Subscript>) mesh: a new approach for soft tissue reinforcement based on an experimental pilot study

The purpose of this study was to evaluate host response and soft-tissue regeneration after poly(lactic acid) (PLA) mesh implantation in a rat model, in comparison with light-weight polypropylene (PPL) and poly(glycolic acid) (PGA) meshes. Full-thickeness abdominal wall defects were created in 45 Wistar rats and reconstructed with 15 PLA₉₄, 15 PPL and 15 PGA meshes. Animals were killed on days 7, 30 and 90 to evaluate the presence of adhesions and changes in tensile strength of the implants. Histolopathology and immunohistochemistry were performed to evaluate the collagen deposition and the inflammatory response. Statistics were done using unpaired Student’s t-test, Mann–Whitney rank sum test, Student–Newman–Keuls test and Bonferroni (Dunn) t-test. The inflammatory response induced by the PLA mesh implantation was significantly milder than after PPL mesh. In PLA, vascularity and collagen organization was significantly higher than in PPL and PGA at 30 and 90 days, and collagen composition score was significantly higher than in PPL at 7 and 30 days. In PLA, shrinkage was significantly lower than in PPL and PGA at 7 and 30 days. Elongation at break and tensile strength were comparable between PLA and PPL over the 90-day period. The PLA mesh induces a milder inflammatory response, more orderly collagen deposition than PPL, and preserved comparable tensile strength after 90 days.     

Adhesion formation and reherniation differ between meshes used for abdominal wall reconstruction

Incisional hernia is a common surgical problem, frequently requiring prosthetic mesh repair. The demands of the ideal mesh seem conflicting; ingrowth at the mesh–fascia interface, without development of adhesions at the visceral mesh surface. Various antiadhesives combined with macroporous mesh and composite meshes were studied for prevention of adhesions to mesh and ingrowth into the fascia. In 60 rats an abdominal wall defect was created and repaired with underlay mesh. Rats were divided into six groups and treated with polypropylene mesh (PPM, control), PPM with auto-cross-linked polymers (ACP) gel, PPM with fibrinogen glue (FG), polypropylene/expanded polytetrafluoroethylene (ePTFE) mesh, polypropylene/sodium hyaluronate/carboxymethylcellulose (HA/CMC) mesh, and polypropylene-collagen/polyethylene-glycol/glycerol (CPGG) mesh. Mesh infection was assessed in the postoperative period, adhesions and reherniations were scored at sacrifice 2 months after operation, and tensile strength of the mesh–tissue interface was measured. Six rats developed mesh infection, half of them were treated with PPM/ePTFE. The PPM/HA/CMC group showed a significant reduction in the amount and severity of adhesions. In animals treated with PPM/ACP and PPM/FG, severity of adhesions was reduced as well. Reherniation rate in the PPM/ACP group was 50% and significantly higher than that in other groups. Rats in the PPM/HA/CMC had the highest tensile strength. PPM/HA/CMC approaches the demands of the ideal mesh best, having superior antiadhesive properties, no reherniation and no infection in this rat model of incisional hernia.     

Does the additional application of a polylactide film (SurgiWrap) to a lightweight mesh (TiMesh) reduce adhesions after laparoscopic intraperitoneal implantation procedures? Experimental results obtained with the laparoscopic porcine model

Background  Intraperitoneal repair of incisional hernias using a mesh makes particular demands on the material used. In addition to good integration of the mesh on the parietal side, adhesions to the visceral peritoneum must be avoided. Large-pore, light-weight meshes induce fewer adhesions than heavy-weight polypropylene meshes. Although numerous adhesion-barrier substances for use in combination with a polypropylene mesh have been tested already, mostly in open small animal models, unequivocal benefits have been identified to date in only a few of the experiments. Methods  Using the laparoscopic intraperitoneal onlay mesh technique, six pigs were implanted with either a lightweight polypropylene mesh (TiMesh light) or TiMesh plus an adhesion-barrier film made of polylactide (SurgiWrap). After 3 months, the animals underwent a postmortem laparoscopy, and specimens were obtained for planimetric and histologic investigations. Results  No adhesions to intestinal structures were found in any of the animals. Adhesions between the greater omentum and the mesh did not differ significantly between the TiMesh (32%) and SurgiWrap (33.5%) groups. The shrinkage of the mesh’s surface area was comparable between the two groups (18% vs. 21%). Histology showed pronounced inflammatory reaction and bridging of scar tissue between the filaments with the use of SurgiWrap versus TiMesh light without film. However, immunohistochemical investigations examining the partial volume of the inflammatory cells, the proliferation marker Ki67, and the apoptotic index at the interface of the filaments all failed to show any significant differences. Conclusion  To avoid adhesions, it is essential that the acute and chronic inflammatory reaction to the implanted material be as small as possible. This requirement is met specifically by the lightweight polypropylene mesh TiMesh light. The additional application of a slowly absorbable adhesion-barrier film made of polylactide (SurgiWrap) does not appear to confer any further benefit.     

Evaluation of new prosthetic meshes for ventral hernia repair

Background In hernia repair, particularly laparoscopic hernia repair, direct contact between mesh and abdominal organs cannot always be avoided. Several mesh materials and composite meshes have been developed to decrease subsequent adhesion formation. Recently, new meshes have been introduced. In an experimental rat study, their value was established and compared with that of meshes already available on the market. Methods In 200 rats, eight different meshes were placed intraperitoneally and in direct contact with abdominal viscera. The following meshes were tested: polypropylene (Prolene), e-PTFE (Dualmesh), polypropylene– polyglecaprone composite (Ultrapro), titanium–polypropylene composite (Timesh), polypropylene with carboxymethylcellulose–sodium hyaluronate coating (Sepramesh), polyester with collagen-polyethylene glycol–glycerol coating (Parietex Composite), polypropylene–polydioxanone composite with oxidized cellulose coating (Proceed), and bovine pericardium (Tutomesh). At 7 and then at 30 days postoperatively, adhesion formation, mesh incorporation, tensile strength, shrinkage, and infection were scored by two independent observers. Results Parietex Composite, Sepramesh, and Tutomesh resulted in decreased surface coverage with adhesions, whereas Prolene, Dualmesh, Ultrapro, Timesh, and Proceed resulted in increased adhesion coverage. Parietex Composite, Prolene, Ultrapro, and Sepramesh resulted in the most mesh incorporation. Dualmesh and Tutomesh resulted in significantly increased shrinkage. There were no differences in mesh infection. Parietex Composite and Dualmesh resulted in a moderate inflammatory reaction, as compared with the mild reaction the other meshes exhibited. Conclusion Parietex Composite and Sepramesh combine minimal adhesion formation with maximum mesh incorporation and tensile strength. The authors recommend the use of these meshes for hernia repair in which direct contact with the abdominal viscera cannot be avoided.     

Comparative evaluation of adhesion formation, strength of ingrowth, and textile properties of prosthetic meshes after long-term intra-abdominal implantation in a rabbit

BACKGROUND: Effective laparoscopic ventral herniorrhaphy usually mandates the use of an intraperitoneal prosthetic. Visceral adhesions and changes in textile characteristics of prosthetics may complicate repairs, especially long-term. The aim of this study was to compare the adhesion formation, tissue ingrowth, and textile characteristics one year after intra-abdominal placement of the commonly used prosthetic meshes. MATERIALS AND METHODS: Forty (4 x 4 cm) meshes were sutured using absorbable suture to an intact peritoneum in 20 New Zealand white rabbits. The study groups included: polypropylene (PP) [Marlex; C.R. Bard Inc, Cranston, NJ], expanded polytetrafluoroethylene (ePTFE) [DualMesh; WL Gore, Flagstaff, AZ], ePTFE and PP (ePTFE/PP) [Composix, C.R. Bard Inc], reduced weight PP and oxidized regenerated cellulose (rPP/C) [Proceed; Ethicon, Inc, Somerville, NJ]. The meshes were explanted after one year. Adhesions were scored as a percentage of explanted biomaterials' affected surface area. Prosthetic shrinkage was calculated. The strength of incorporation and mesh compliance were evaluated using differential variable reluctance transducers. Mesh ingrowth was measured as the load necessary to distract the mesh/tissue complex. Mesh compliance was calculated as the change in linear displacement of the sensors due to applied load. The groups were compared using Student's t-test and Fisher's exact test. RESULTS: ePTFE had significantly less adhesions (0%) than both ePTFE/PP (40%) and PP (80%) groups (P < 0.001). The mean area of adhesions for the rPP/C (10%) and the ePTFE/PP (14%) groups was less than that for the PP group (40%) (P = 0.02). Prosthetic shrinkage was greatest in the ePTFE (32%) group than in any other group (P = 0.001). There were no differences in mesh incorporation between the groups. At explantation, mesh compliance in the ePTFE group was superior to other meshes (P < 0.0001). The rPP/C mesh induced the smallest change in the compliance of the tissue adjacent to the mesh (P = 0.0001). CONCLUSIONS: Prosthetic materials demonstrate a wide variety of characteristics. Although exposed PP formed the most adhesions, up to 40% of the other PP-based meshes formed adhesions despite protective barriers. The ePTFE mesh did not induce adhesions and was the most compliant, however, this prosthetic's contraction was greatest. Reduced weight polypropylene (rPP/C) mesh induced the smallest change in the adjacent tissue pliability/compliance. Understanding of the long-term effects of various prosthetic materials is important to ensure an adequate hernia repair while minimizing postoperative morbidity and patient discomfort.     

N-Butyl Cyanoacrylate Versus Conventional Suturing for Fixation of Meshes in an Incisional Hernia Model

ABSTRACT

Background: Chronic pain and related complications reported after the use of perforating fixation devices in hernia surgery have led to the use of tissue sealants. Fibrin sealant is a feasible option for mesh fixation; however data on cyanoacrylate glues are limited. Methods: 32 Sprague-Dawley rats were divided into two groups and a 1.5 cm abdominal wall defect was created on each animal. The lesions were then repaired with 2 × 2 cm polypropylene meshes, fixed with n-butyl-cyanoacrylate in the first group and with polypropylene sutures in the second group. The rats were sacrificed on the 21st and 42nd days. The presence of infection, recurrence, and abdominal adhesions were evaluated, followed by biomechanical testing and histological examination. Results: No mesh infection or hernia recurrences were recorded. There was no statistically significant difference between neither the adhesion scores nor the mean broken pressure of the two groups. Cyanoacrylate sealing was found equivalent to suturing in terms of tissue ingrowth, fibrosis, inflammatory infiltration, abscess formation, and necrosis. Furthermore, cyanoacrylate resulted in less foreign body reaction. Conclusions: Mesh fixation by cyanoacrylate may be considered as an alternative to suture fixation.     

Effective prevention of adhesions with hyaluronate

HYPOTHESIS: Hyaluronate sodium in the form of a bioresorbant membrane reduces the development of intra-abdominal adhesions frequently found after implantation of synthetic mesh in the context of surgical hernia repair. DESIGN: The effect of hyaluronate on the formation of adhesions was evaluated when applied laparoscopically as a bioresorbant membrane to protect the peritoneal surface of a synthetic mesh. SETTING: Experimental animal model. INTERVENTIONS: A peritoneal defect 5 cm in diameter was bilaterally created in the abdominal wall of each of 9 pigs by laparoscopy. A polypropylene mesh was fixed with clips onto these defects on both sides. In each of the animals, only on one side, the synthetic mesh was also covered by a hyaluronate membrane. MAIN OUTCOME MEASURES: The incidence and severity of adhesions (grade 0-4, where 0 indicates no adhesion; 1, filmy avascular adhesions; 2, vascular adhesions; 3, cordlike fibrous adhesions; and 4, plain fibrous adhesions) were determined after 45 days, comparing treated and untreated sides by autopsy results and histological features. RESULTS: Adhesions, mainly grades 3 and 4, occurred in 7 of the 9 animals in those meshes not covered by hyaluronate; 2 untreated animals did not develop adhesions. On the other hand, only 1 of the 9 animals developed adhesions (grade 2) at the mesh concealed by the hyaluronate membrane. CONCLUSIONS: The bioresorbant hyaluronate membrane significantly reduced the formation of peritoneal adhesions (1-sided sign test, P<.05) induced by the insertion of a polypropylene mesh, when compared with the contralateral implants not protected by hyaluronate. Thus, hyaluronate membranes are efficient for reducing the incidence of peritoneal adhesions.     

Polypropylene meshes coated with a polysaccharide based bioadhesive for intra-abdominal mesh fixation in a rabbit model

Background

In this study, we evaluate a new bioadhesive for intra-abdominal onlay mesh fixation of a polypropylene–polyvinylchloride graft.

Methods

Three pieces of a commercially available polypropylene/polyvinylfluoride mesh, each 3 × 3 cm in size, and three pieces of the same mesh coated with a polysaccharide bioadhesive were fixated to the surface of the anterior abdominal wall of 30 New Zealand white rabbits. The fixation was performed either by using four transabdominal Prolene^® 4/0 sutures, four spiral tacks (Protack 5 mm Tyco), or cyanoacrylate glue (Glubran^® GEM, Viareggio, Italy). Each mesh position and the according kind of fixation were randomized before implantation. The animals were sacrificed 12 weeks postoperatively. After determining the extent of intra-abdominal adhesions, the meshes were excised en bloc with the anterior abdominal wall for tensile strength measurements and histological analysis.

Results

All meshes coated with the bioadhesive adhered to the intact peritoneum without extra fixation. Irrespective of the fixation technique coated meshes led to more and stronger adhesions. Mesh shrinkage by scarring was increased in coated meshes fixed with glue and low in uncoated meshes fixed with tacks. Testing the tensile strength, coated meshes fixed with transfascial sutures achieved the best results (16.14 ± 6.1 N), whereas coated meshes fixed with glue showed the lowest strength (10.39 ± 4.81 N). The foreign body reaction was considerably more distinctive using coated mesh. The mesh ingrowth was not influenced by this reaction.

Conclusions

All meshes coated with the new bioadhesive were self-adhesive in that way; they stayed in position when attached to the peritoneum. Although this may facilitate intra-operative mesh fixation, the bioadhesive displayed several disadvantages, such as stronger adhesions and an increased shrinkage of the implant. The tensile strength was not influenced by the use of the bioadhesive. At present, we see no major advantage for polysaccharide bioadhesive applied in this study.     

Prevention of adhesion formation to polypropylene mesh by collagen coating: A randomized controlled study in a rat model of ventral hernia repair

Introduction In laparoscopic incisional hernia repair with intraperitoneal mesh, concern exists about the development of adhesions between bowel and mesh, predisposing to intestinal obstruction and enterocutaneous fistulas. The aim of this study was to assess whether the addition of a collagen coating on the visceral side of a polypropylene mesh can prevent adhesion formation to the mesh.Method In 58 rats, a defect in the muscular abdominal wall was created, and a mesh was fixed intraperitoneally to cover the defect. Rats were divided in two groups; polypropylene mesh (control group) and polypropylene mesh with collagen coating (Parieten mesh). Seven and 30 days postoperatively, adhesions and amount and strength of mesh incorporation were assessed. Wound healing was studied by microscopy.Results With Parieten mesh, the mesh surface covered by adhesions was reduced after 30 days (42% vs 69%, p = 0.01), but infection rate was increased after both 7 (p = 0.001) and 30 days (p = 0.03), compared to the polypropylene group with no mesh infections. If animals with mesh infection were excluded in the analysis, the mesh surface covered by adhesions was reduced after 7 days (21% vs 76%, p = 0.02), as well as after 30 days (21 vs 69%, p < 0.001). Percentage of mesh incorporation was comparable in both groups. Mean tensile strength of mesh incorporation after 30 days was higher with Parieten mesh.Conclusion Although the coated Parieten mesh was more susceptible to mesh infection in the current model, a significant reduction of adhesion formation was still seen with the Parieten mesh after 30 days, with comparable mesh incorporation in the abdominal wall.     

Prolene–Monocryl-composite meshes do not increase microvascular <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> adherence and do not sensitize for leukocytic inflammation

Background and aims Mesh implantation for hernia repair bears the risk of bacterial mesh infection. In this study, we analyzed whether this complication is supported by an increased interaction of bacteria and leukocytes with the microvascular endothelium at the implantation site. Materials and methods Ultrapro meshes were implanted into the dorsal skinfold chamber of Syrian golden hamsters. After 12 days, fluorescein isothiocyanate (FITC)-labeled staphylococci were injected in the animals. Subsequently, we analyzed bacterial adherence, leukocyte–endothelial cell interaction, and microhemodynamics in venules of the mesh border zone and of distant control tissue under baseline conditions and during TNF-α-induced inflammation using intravital fluorescence microscopy. The results were compared to animals which did not receive any bacteria. Results Under baseline conditions, leukocyte–endothelial cell interaction and bacterial adherence were not affected by the implanted biomaterial. TNF-α-induced inflammation significantly increased numbers of adherent leukocytes and bacteria in venules located in direct vicinity to the mesh however without any differences to control tissue. Comparable results were found for the leukocyte–endothelial cell interaction when animals were not exposed to bacteria. Conclusion Implanted Ultrapro meshes do neither increase microvascular Staphylococcus aureus adherence nor sensitize for leukocytic inflammation. Thus, we suggest that a mesh-induced increase of bacterial adherence in vessels of the implantation site cannot be considered as a primary cause for the development of mesh infection. German Society of Surgery, Surgical Forum 2008, Best of Abstracts.     

Strategies to minimize adhesions to intraperitoneally placed mesh in laparoscopic ventral hernia repair

Introduction:

Adhesions to mesh/tacks in laparoscopic ventral hernia repair are often cited as reasons not to adopt its evidence-based superiority over conventional open methods. This pilot study assessed the occurrence of adhesions to full-sized Polypropylene and Gore-tex DualMesh Plus meshes and the possibility for adhesion prevention using fibrin sealant.

Methods:

Two 10-cm to 15-cm pieces of mesh were placed and fixed laparoscopically in pigs (25kg to 55kg). Group I: 2 animals with Polypropylene mesh on one side and DualMesh on other side. Group II: 2 animals with DualMesh on each side with fibrin sealant applied to the periphery of mesh and staples to one side. Group III: 1 animal with 2 pieces of Polypropylene mesh with fibrin sealant applied to the entire mesh. All animals underwent laparoscopy 3 months later to assess the extent of adhesions, and full-thickness specimens were removed for histological evaluation.

Results:

More Polypropylene mesh was involved in adhesions than DualMesh. However, with the DualMesh involved in adhesions, more of the surface area was involved in forming adhesions than with Polypropylene mesh. None of the implanted DualMesh had visceral adhesions, while 2 out of 3 Polypropylene meshes had adhesions to both the liver and spleen but none to the bowel. Implanted Polypropylene mesh with fibrin sealant had no adhesions. DualMesh had shrunk more significantly than Polypropylene mesh. Histological evaluation showed absence of acute inflammatory response, significantly more chronic inflammatory response to DualMesh compared to Polypropylene and complete mesothelialization with both meshes. There was extensive collagen deposition between Polypropylene mesh fibers, while fibrosis occurred on both sides of DualMesh with synovial metaplasia over its peritoneal surface akin to encapsulation.

Conclusions:

DualMesh caused fewer omental and visceral adhesions than Polypropylene mesh did. Fibrin sealant eliminated adhesions to DualMesh and prevented adhesions to Polypropylene mesh when applied over the entire surface. These results support our current use of DualMesh and fibrin sealant in LVHR.     

Fibrin glue for mesh fixation in laparoscopic transabdominal preperitoneal (TAPP) hernia repair: indications, technique, and outcomes

Background The efficacy and safety of prosthesis fixation were studied by means of fibrin glue (Tissucol, Baxter Healthcare) during laparoscopic transabdominal preperitoneal (TAPP) treatment of inguinal and femoral hernias. Methods Between September 2001 and December 2004, fibrin glue was used for mesh fixation during TAPP. Results In this study, 320 hernias were treated for 230 patients (225 men and 5 women) with an average age of 45 years (range, 20–75 years). No perioperative complications were observed. After an average follow-up period of 26 months (range, 1–40 months), the only postoperative complications observed were six seromas (1.8%) and one trocar-site hematoma (0.3%). The mean operating time was 30 min for unilateral hernias and 50 min for bilateral hernias, whether primary or recurrent. Patients usually were discharged the day after surgery and returned to work after 5 days. Conclusions The authors’ experience demonstrates that fibrin glue (Tissucol) is an effective method for mesh fixation during TAPP.     

Relationship Between Tissue Ingrowth and Mesh Contraction

Contraction is a well-documented phenomenon occurring within two months of mesh implantation. Its etiology is unknown, but it is suggested to occur as a result of inadequate tissue ingrowth into the mesh and has been associated with hernia recurrence. In continuation of our previous studies, we compared tissue ingrowth characteristics of large patches of polyester (PE) and heavyweight polypropylene (PP) and their effect on mesh contraction. The materials used were eight PE and eight PP meshes measuring 10 × 10 cm². After random assignment to the implantation sites, the meshes were fixed to the abdominal wall fascia of swine using interrupted polypropylene sutures. A necropsy was performed three months after surgery for evaluation of mesh contraction/shrinkage. Using a tensiometer, tissue ingrowth was assessed by measuring the force necessary to detach the mesh from the fascia. Histologic analysis included inflammatory and fibroblastic reactions, scored on a 0–4 point scale. One swine developed a severe wound infection that involved two PP meshes and was therefore excluded from the study. The mean area covered by the PE meshes (87 ± 7 cm²) was significantly larger than the area covered by the PP meshes (67 ± 14 cm²) (p = 0.006). Tissue ingrowth force of the PE meshes (194 ± 37 N) had a trend toward being higher than that of the PP meshes (159 ± 43 N), although it did not reach statistical significance. There was no difference in histologic inflammatory and fibroblastic reactions between mesh types. There was a significant correlation between tissue ingrowth force and mesh size (p = 0.03, 95% CI: 0.05–0.84). Our results confirm those from previous studies in that mesh materials undergo significant contraction after suture fixation to the fascia. PE resulted in less contraction than polypropylene. A strong integration of the mesh into the tissue helps prevent this phenomenon, which is evidenced by a significant correlation between tissue ingrowth force and mesh size. Presented at the Southeastern Surgical Congress 2004 Meeting, Atlanta, GA, January 31–February 3, 2004 This study was sponsored by Promethian Surgical Devices, Boston, MA, USA.     

Prevention of adhesion to prosthetic mesh: comparison of different barriers using an incisional hernia model

OBJECTIVE: To assess whether use of antiadhesive liquids or coatings could prevent adhesion formation to prosthetic mesh. SUMMARY BACKGROUND DATA: Incisional hernia repair frequently involves the use of prosthetic mesh. However, concern exists about development of adhesions between viscera and the mesh, predisposing to intestinal obstruction or enterocutaneous fistulas. METHODS: In 91 rats, a defect in the muscular abdominal wall was created, and mesh was fixed intraperitoneally to cover the defect. Rats were divided in five groups: polypropylene mesh only (control group), addition of Sepracoat or Icodextrin solution to polypropylene mesh, Sepramesh (polypropylene mesh with Seprafilm coating), and Parietex composite mesh (polyester mesh with collagen coating). Seven and 30 days postoperatively, adhesions were assessed and wound healing was studied by microscopy. RESULTS: Intraperitoneal placement of polypropylene mesh was followed by bowel adhesions to the mesh in 50% of the cases. A mean of 74% of the mesh surface was covered by adhesions after 7 days, and 48% after 30 days. Administration of Sepracoat or Icodextrin solution had no influence on adhesion formation. Coated meshes (Sepramesh and Parietex composite mesh) had no bowel adhesions. Sepramesh was associated with a significant reduction of the mesh surface covered by adhesions after 7 and 30 days. Infection was more prevalent with Parietex composite mesh, with concurrent increased mesh surface covered by adhesions after 30 days (78%). CONCLUSIONS: Sepramesh significantly reduced mesh surface covered by adhesions and prevented bowel adhesion to the mesh. Parietex composite mesh prevented bowel adhesions as well but increased infection rates in the current model.     

Experimental evaluation of intra-abdominal adhesions comparing two different intraperitoneal meshes and the effect of a natural anti-inflammatory product on their formation

Purpose:In laparoscopic incisional hernia repair, meshes with a tissue-separating barrier are positioned intraperitoneally. Despite this property, the close contact between mesh and viscera involves a risk of adhesion formation. Some natural products, such as red propolis (RP), could reduce these adhesions owing to their anti-inflammatory properties. This study aimed to compare two different intraperitoneal meshes with respect to their characteristics of adhesion formation, histological findings and evaluate the role of RP in the development of these adhesions.Methods:40 Wistar rats received placement of two different meshes (Symbotex and Dynamesh IPOM) on peritoneum. The animals were divided into two groups: control group (mesh) and treatment group (mesh and RP). After 7 and 14 days, 20 animals of each group underwent midline laparotomy to determine the adhesions and histological characteristics.Results:Out of the 40 animals, there were two deaths in the test group and two in the control group. All animals in both groups developed adherence to the mesh. At postoperative day (POD) 7, two Symbotex meshes presented firm adhesions and at POD 14, two Dynamesh meshes had firm adhesions as well. The comparison between the meshes under the effect of RP in relation to the control group showed no statistical difference.Conclusions:Both meshes showed intraperitoneal adhesions in all evaluated samples with similar results on the characteristics of adhesions. RP showed no effect on the incidence or gradation of intraperitoneal adhesions with the mesh.Key words: Surgical Mesh, Hernia, Rats     

Re-operation due to severe late-onset persisting groin pain following anterior inguinal hernia repair with mesh

Objectives  Mild pain lasting for a few days is common following mesh inguinal hernia repair. In some patients however, severe groin pain may appear months or even years postoperatively. The aim of this study was to report our experience of late-onset persisting severe postoperative groin pain occurring years after mesh hernioplasty. Methods  In a 9-year period, 1,633 patients (1,073 men), median age 63 years (range 19–88), underwent mesh groin hernia repair. Between 1.5 and 4 years postoperatively, six patients (0.35%) presented with severe chronic groin pain unrelieved by conservative measures and surgical exploration was essential. The patients’ records were retrospectively reviewed for the purpose of this study. Results  Ilioinguinal nerve entrapment was detected in four patients. The meshes appeared to be indistinguishable from the nerve and were removed along with the stuck nerve. New meshes were properly inserted. Mesh fixation on the periostium of the pubic tubercle by a staple was found in the other two patients. The staples were removed from the periostium in both patients. Neither hernia recurrence nor chronic groin pain was persisting in all six patients during a follow-up of 6–44 months postoperatively. Conclusion  From the results of this study, it appears that ilioinguinal nerve entrapment and/or mesh fixation on the periostium of the pubic tubercle are the causes of late-onset severe chronic pain after inguinal mesh hernioplasty. Mesh removal, along with the stuck ilioinguinal nerve and staple detachment from the periostium, are the gold-standard techniques if conservative measures fail to reduce pain.     

Bursting strength evaluation after different types of mesh fixation in laparoscopic herniorrhaphy

Background: In laparoscopic inguinal herniorrhaphy, meshes commonly have been fixed with a stapler. Recently, a new mode of fixation using a helical fastener has been introduced. The purpose of this experimental study was to compare the stability achieved by various types of mesh fixation. Methods: In 20 human cadavers, polypropylene meshes 10 × 15 cm in size were fixed in both groins by using either a helical fastener or a hernia stapler (4.8 mm). The mesh was fixed with 2, 4, and 8 elements and stressed with a dynamometer until the prosthesis ruptured. A paired and two-sided Student's t-test was used for statistical evaluation. Results: With the helical fastener, the mesh could be fixed always at the desired site. However, with the stapler, it was not possible to fix the mesh in the pubic bone or, at times, in the Cooper's ligament. When two fixation elements were used, the mesh fixed by the helical fastener was able to withstand a median load of 34 N (range 23–53 N), and that fixed by the stapler 7.5 N (range 3–12 N; p < 0.001). When four fixation elements were used, the mesh fixed by the helical fastener was able to withstand 70.5 N (range 53–80 N) and that fixed by the stapler 17.5 N (range 4–25 N; p < 0.001). With the use of eight elements, the mesh fixed by the helical fastener withstood 127 N (range 84–156 N) and that fixed by the stapler 32.5 N (range 15–59 N; p < 0.001). Thus, in all cases the helical fastener was significantly more stress resistant. The main reason for detachment of the mesh was tissue disruption or deformation of the fixation elements. Only when a stress of more than 130 N was applied did the mesh tear in two cases. Conclusions: The stress-bearing capacity (shear force resistance) of a mesh fixed by a helical fastener is up to four times that of a mesh fixed by a stapler. Therefore, the helical fastener provides significantly more stable fixation and will be able to protect the patient better from recurrent hernias caused by mesh migration. Received: 10 August 1998/Accepted: 26 March 1999     

Laparoscopic evaluation of abdominal adhesions with different prosthetic meshes in rabbits.

BACKGROUND: The use of prosthetic materials to reinforce the abdominal wall is associated with a low index of recurrence; however, intraperitoneal placement of a foreign body may lead to adhesions. The present investigation was designed to determine adhesion formation with commercially available meshes implanted laparoscopically in rabbits. METHODS: Three different meshes were implanted laparoscopically in 24 rabbits: polypropylene (mesh A), polypropylene and sodium hyaluronate-carboxymethylcellulose (mesh B), and polypropylene and expanded polytetrafluoroethylene (mesh C). Sites of implantation for each mesh (the left lower quadrant, right lower quadrant, and lower midline) were randomly determined so that every rabbit had all 3 meshes implanted. All animals underwent diagnostic laparoscopy after 28 days to grade adhesions and histological analysis of inflammation. RESULTS: Adhesions were noticed in 46 of the 72 meshes implanted (64%). The number of adhesions was higher for mesh C (87.5%) compared with meshes A (62.5%) and B (41.6%). The severity of adhesions was also higher for mesh C (grade I in 14, II in 6, and III in 1) compared with mesh A (grade I in 10, II in 4, and III in 1 case) and B (all of them grade II). Histological inflammatory reaction was classified as mild in 23 cases of mesh A, 15 of mesh B, and 23 of mesh C. A moderate reaction was found in 1 case of mesh A, 4 cases of mesh B, and 1 case of mesh C. Severe reaction was induced in 5 cases of mesh B. Mesh B induced a higher inflammatory reaction compared with the other meshes. CONCLUSIONS: All meshes induced adhesions of different grades. Mesh B had fewer adhesions and more intense inflammation them did the others.     

The use of composite meshes in laparoscopic repair of abdominal wall hernias: are there differences in biocompatibily?

Introduction  In recent years, laparoscopic repair of abdominal wall hernias has become increasingly established in routine clinical practice thanks to the myriad advantages it confers. Apart from the risk of intestinal damage following adhesiolysis, to date no information is available on the best way of preventing the formation of new adhesions in the vicinity of the implanted meshes. Numerous experimental investigations, mainly conducted on an open small-animal model, have demonstrated the advantages of coating meshes, inter alia with absorbable materials, compared with uncoated polypropylene meshes. In our established laparoscopic porcine model we set about investigating three of these meshes, which are already available on the market. Materials and methods  In total, 18 domestic pigs underwent laparoscopic surgery and three different composite meshes were tested in each case on six animals (Dynamesh IPOM, Proceed, Parietene Composite). At 4 months, postmortem diagnostic laparoscopy was carried out, followed by full-wall excision of the specimens. Planimetric analysis was conducted to investigate the size of the entire surface area and the extent of adhesions. Histological investigations were performed on five sections for each specimen. These focused on the partial volumes of inflammatory cells, the proliferation marker Ki67, apoptotic index, inflammatory cell marker CD68 and transforming growth factor beta (TGF-β) as a marker of the extracellular matrix. Results  A similar value of 14% was obtained for shrinkage of Dynamesh IPOM and Parietene Composite, while Proceed showed a 25% reduction in its surface area. Markedly lower values of 12.8% were obtained for Parietene Composite in respect of adhesions to the greater omentum, compared with 31.7% for Proceed and 33.2% for Dynamesh IPOM (p = 0.01). Overall, Parietene Composite performed best in the histological and immunhistochemistry tests. Conclusions  On the whole, all composite meshes showed evidence of good biocompatibility. However, none of the coatings was completely able to prevent adhesions. Coating of polypropylene meshes with collagen appears to confer significant advantages compared with other coatings.     

Mechanical properties of polypropylene mesh used in pelvic floor repair

The aim of this study was the comparison of the stiffness of different meshes under two types of mechanical tests. Five different mesh types were mechanically tested. The methods used consisted on uniaxial tension test (tensile stiffness) and tape ring tests, experimental continuous compression of the mesh loops (flexural stiffness). The most significant difference of tensile stiffness behaviour appears between Aris™ and TVTO™. From the analysis of the experimental data, we divided the flexural stiffness, in two main groups. The first group includes Auto Suture™ and Aris™ meshes. The two meshes seem to have a similar flexural behaviour. The second group includes TVTO™, Uretex™ and Avaulta™. The difference between these two groups is clearly evident comparing TVTO™ and Aris™. This study shows that there are significant differences on the mechanical properties between urogynecology meshes. An erratum to this article can be found at