Activation of human mononuclear cells by porcine biologic meshes in vitro

Introduction

While porcine-based biologic meshes are increasingly used for hernia repair, little data exist on tissue responses to such products. Host foreign body reaction, local inflammation, and wound healing are principally controlled by monocytes/macrophages (M/MØs). Exaggerated activation of M/MØs may deleteriously influence mesh integration and remodeling. We hypothesized that common porcine meshes induce the differential activation of M/MØs in vitro.

Materials and methods

Samples of four acellular porcine-derived meshes, CollaMend? (CM; C.R. Bard/Davol), Permacol? (PC; TSL/Covidien), Strattice? (ST; LifeCell), and Surgisis^® (SS; Cook Biotech), were exposed to mononuclear cells derived from the peripheral blood of six healthy subjects. Following a 7-day incubation period, supernatants were assayed for interleukin-1beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF) using a multiplex bead-based immunoassay system. The four groups were compared using analysis of variance (ANOVA) and Student’s t-test.

Results

Each mesh type induced differential mononuclear cell activation in vitro. The mean IL-1β expressions for CM (7,195 pg/ml) and PC (4,215 pg/ml) were significantly higher compared to ST and SS (123 and 998 pg/ml, respectively; P < 0.05). Similar trends were also seen for IL-6 (range 445–70,729 pg/ml), IL-8 (range 11,640–1,045,938 pg/ml), and VEGF (range 686–7,133 pg/ml).

Conclusion

For the first time, we demonstrated that porcine meshes induce M/MØ activation in vitro. CM and PC (chemically crosslinked dermis) induced significantly higher cytokine expression compared to ST (non-crosslinked dermis) and SS (small intestine submucosa). These differences are likely related to proprietary processing methods and/or the extent of collagen crosslinking. Further understanding of immunologic effects of porcine-derived biologic meshes will not only allow for a comparison between existing products, but it may also lead to mesh modifications and improvement of their clinical performance.     

Gentamicin for prevention of intraoperative mesh contamination: demonstration of high bactericide effect (in vitro) and low systemic bioavailability (in vivo)

Introduction

Mesh infection is a severe complication after incisional hernia repair and occurs in 1–3 % of all open mesh implantations. For this reason, topical antimicrobial agent applied directly to the mesh is often used procedure. So far, however, this procedure lacks a scientific basis.

Materials and methods

Two different meshes (Parietex?, Covidien; Ultrapro?, Ethicon Johnson & Johnson) were incubated with increasing amounts of three different Staphylococcus aureus strains (ATCC 25923; Mu50; ST239) with or without gentamicin and growth ability were determined in vitro. To further address the question of the systemic impact of topic gentamicin, serum levels were analyzed 6 and 24 h after implantation of gentamicin-impregnated multifilament meshes in 19 patients.

Results

None of the gentamicin-impregnated meshes showed any bacterial growth in vitro. This effect was independent of the mesh type for all the tested S. aureus strains. In the clinical setting, serum gentamicin levels 6 h after implantation of the gentamicin-impregnated meshes were below the through-level (range 0.4–2.9 mg/l, mean 1.2 ± 0.7 mg/l). After 24 h the gentamicin serum levels in all patients had declined 90–65 % of the 6 h values.

Conclusion

Local application of gentamicin to meshes can completely prevent the growth of even gentamicin-resistant S. aureus strains in vitro. The systemic relevance of gentamicin in the clinical controls showed to be very low, without reaching therapeutic concentrations.     

Evaluation of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh in a porcine model of ventral hernia repair

Background

The objective of this study was to evaluate the mechanical and histological properties of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh (Phasix? ST) compared to partially absorbable (Ventralight? ST), fully absorbable (Phasix?), and biologically derived (Strattice?) meshes in a porcine model of ventral hernia repair.

Methods

Bilateral abdominal surgical defects were created in twenty-four Yucatan pigs, repaired with intraperitoneal (Phasix? ST, Ventralight? ST) or retromuscular (Phasix?, Strattice?) mesh, and evaluated at 12 and 24 weeks (n = 6 mesh/group/time point).

Results

Prior to implantation, Strattice? demonstrated significantly higher (p < 0.001) strength (636.6 ± 192.1 N) compared to Ventralight? ST (324.3 ± 37.1 N), Phasix? ST (206.9 ± 11.3 N), and Phasix? (200.6 ± 25.2 N). At 12 and 24 weeks, mesh/repair strength was significantly greater than NAW (p < 0.01 in all cases), and no significant changes in strength were observed for any meshes between 12 and 24 weeks (p > 0.05). Phasix? mesh/repair strength was significantly greater than Strattice? (p < 0.001) at 12 and 24 weeks, and Ventralight? ST mesh/repair strength was significantly greater than Phasix? ST mesh (p < 0.05) at 24 weeks. At 12 and 24 weeks, Phasix? ST and Ventralight? ST were associated with mild inflammation and minimal–mild fibrosis/neovascularization, with no significant differences between groups. At both time points, Phasix? was associated with minimal–mild inflammation/fibrosis and mild neovascularization. Strattice? was associated with minimal inflammation/fibrosis, with minimal neovascularization at 12 weeks, which increased to mild by 24 weeks. Strattice? exhibited significantly less neovascularization than Phasix? at 12 weeks and significantly greater inflammation at 24 weeks due to remodeling.

Conclusions

Phasix? ST demonstrated mechanical and histological properties comparable to partially absorbable (Ventralight? ST) and fully resorbable (Phasix?) meshes at 12 and 24 weeks in this model. Data also suggest that fully absorbable meshes with longer-term resorption profiles may provide improved mechanical and histological properties compared to biologically derived scaffolds.

     

Intraperitoneal behaviour of a new composite mesh (Parietex™ Composite Ventral Patch) designed for umbilical or epigastric hernia repair

Introduction

The most common treatment option for ventral and umbilical hernias is the implant of a prosthetic mesh. This study compares the behaviour of a new mesh, Parietex? Composite Ventral Patch (Ptx), with two commercially available meshes, Ventralex? ST Hernia Patch and Proceed? Ventral Patch.

Materials and methods

The following meshes were tested in a umbilical-hernia repair model using 54 rabbits: Ventralex? ST Hernia Patch (Vent) (Bard Davol Inc., USA); Proceed? Ventral Patch (PVP) (Ethicon, USA) and Ptx (Covidien, Sofradim, France) (n = 18 each). At 3, 7 and 14 days postimplantation, peritoneal behaviour and adhesion formation were assessed by sequential laparoscopy. Adhesions were scored for consistency and quantified by image analysis. The animals were euthanized at 2 (n = 27) and 6 weeks (n = 27) postsurgery. Mesothelial cover of meshes and tissue ingrowth were determined by scanning and light microscopy.

Results

Seroma was observed in 1/18 Vent, 7/18 PVP and 4/18 Ptx, mainly between the implant and subcutaneous tissue. Firm omental adhesions between the mesh and parietal peritoneum were noted in 2/9 Vent, 6/9 PVP and 3/9 Ptx at 2 weeks and in 3/9 Vent, 5/9 PVP and 1/9 Ptx at 6 weeks. Three (out of 9) encapsulated PVP implants showed “tissue-integrated” adhesions affecting the intestinal loops. No differences between implants were detected in the surface area occupied by adhesions at 2 weeks, though at 6 weeks, percentages were significantly higher (p < 0.01; Mann–Whitney U test) for PVP compared to Ptx or Vent. At this time point, Ptx and Vent showed good host tissue incorporation and optimal mesothelialization.

Conclusions

The PVP implants showed greater adhesion formation than the other materials. Postimplantation behaviour was comparable for Ptx and Vent including scarce adhesion formation and optimal mesothelialization. Regarding tissue integration, Ptx showed greater long-term collagenization of the neoformed tissue.     

Hernienchirurgie: Wachstumsverhalten humaner Fibroblasten auf alloplastischen Kunststoffnetzen

Background

The biocompatibility of meshes in hernia surgery seems to be influenced markedly by the amount of the selected material and its structure. Fibroblasts play a major key role during the process of mesh incorporation. This study was performed to investigate differences in cell morphology and proliferation of human fibroblasts cultured on different polypropylene meshes.

Methods

In the present in vitro study the cellular response of human fibroblasts was investigated by scanning electron microscopy (SEM), comparing three different polypropylene meshes: a newly constructed low-weight and microporous mesh (NK1), a low-weight and macroporous mesh with absorbable polyglactin filaments (Vypro), and a heavy-weight and microporous mesh (BiomeshP1). Human fibroblasts (1,5·10⁵ cells) were incubated with the meshes (each 12 mm²) for 6 hours, 5 days, 2, 4, 6, and 12 weeks. Computer-assisted morphometry of the fibroblast/mesh surface ratio served to reflect the biological cell response.

Results

The Vypro mesh showed the significantly highest fibroblast density during the first 6 weeks, but cell growth was nearly exclusively limited to the polyglactin filaments. At 3 months, after reabsorption of the polyglactin, the fibroblast-coated polypropylene mesh surface was only 50% compared to NK1 and BiomeshP1. The morphologic aspect of the fibroblasts on the BiomeshP1 mesh was much more degenerative and unphysiological, compared to NK1 and Vypro, with isolated, single cells instead of a broad, connective growth. The BiomeshP1 showed a significantly higher fibroblast proliferation around the nodes of the mesh compared to the straight filaments. On the NK1 mesh fibroblasts exclusively proliferated on the filaments but not on the pressed mesh surface.

Conclusions

The polymer surface and structure appears to be of major importance for the biocompatibility of meshes: human fibroblasts preferably grow on low-weight meshes, thin filaments, and mesh nodes. Heavy-weight meshes induce degenerative cell reactions. Polyglactin seems to further improve cell proliferation whereas a pressed mesh surface without pores hinders fibroblast growth.     

Human monocyte activation by biologic and biodegradable meshes in vitro

Background

Inflammation and wound healing play critical roles in the integration of biologic and biodegradable meshes (BMs) at hernia repair sites. Monocytes/macrophages (M/MØs) are key cells controlling inflammation and wound healing. These cells release inflammatory cytokines and growth factors such as interleukin (IL)-1β, IL-6, IL-8, and vascular endothelial growth factor (VEGF) upon activation. Although BMs have been increasingly used in hernia repairs worldwide, to date, investigations of inflammatory responses to various BMs have been limited.

Methods

Mesh samples of three acellular human dermis-derived biologic meshes (AlloDerm, AlloMax, FlexHD) and one biodegradable synthetic mesh (Bio-A) were placed in 96-well plates. Human peripheral blood mononuclear cells (PBMCs) were isolated from six healthy subjects, added to each well, and incubated for 7 days. Culture supernatants were assayed for IL-1β, IL-6, IL-8, and VEGF levels using a multiplex bead-base immunoassay system (Bio-Plex).

Results

All four meshes induced cytokine expression from activated M/MØs to varying degrees in vitro. FlexHD induced significantly more IL-1β (2,591 pg/ml) than AlloMax (517 pg/ml), AlloDerm (48 pg/ml), or Bio-A (28 pg/ml) (p < 0.001). AlloMax stimulated a significantly greater quantity of IL-6 (38,343 pg/ml) than FlexHD (19,317 pg/ml), Bio-A (191 pg/ml), or AlloDerm (103 pg/ml) (p < 0.05). Interleukin-8 and VEGF displayed trends similar to that of IL-6. There were no significant differences in cytokine production between AlloDerm and Bio-A.

Conclusion

This study demonstrated that human macrophages are activated by human dermis-derived biologic and biodegradable meshes in vitro. A wide range of cytokine and growth factor induction was seen among the different mesh products. These differences in M/MØ activation may be related to the proprietary processing technologies of the studied meshes. The study results raise the possibility that these differences in M/MØ activation could indicate varying intensities of inflammation that control integration of different biologic meshes at the sites of hernia repair.     

Effectiveness and safety of n-butyl-2-cyanoacrylate medical adhesive for noninvasive patch fixation in laparoscopic inguinal hernia repair

Background

Our purpose was to compare the recurrence rate and other clinical outcomes of laparoscopic (LS) transabdominal preperitoneal (TAPP) inguinal hernia repair using n-butyl-2-cyanoacrylate (NBCA) for mesh fixation with those of no mesh fixation and mesh fixation with titanium spiral tacks (ST).

Methods

The medical records of patients who received LS TAPP inguinal hernia repair between 2009 and 2012 at our institution were reviewed. Patients were included if the received LS TAPP with either no mesh fixation, mesh fixation with NBCA only, fixation with ST only, or fixation with NBCA + ST. Outcome measures were operation time, postoperative length of stay, visual analogue scale (VAS) pain score 24 h after surgery, postoperative complications, and hernia recurrence.

Results

A total of 1,027 TAPP cases were included. In 552 cases, meshes were fixed with NBCA only, in 89 cases only ST were used, in 47 cases ST and NBCA were used, and in 339 cases meshes were not fixed. The groups were comparable with respect to demographic and clinical characteristics. No surgical complications occurred in any group. VAS pain scores were significantly lower in the nonfixation and NBCA only groups (1.4 ± 0.6 and 1.3 ± 0.6, respectively) than in the ST and NBCA + ST groups (2.2 ± 0.9 and 2.2 ± 0.7, respectively; P = 0.001). The mean follow-up duration was ~19 months. At the final follow-up, no wound infections or hernia recurrences had occurred in any of the groups. No occurrence of chronic pain was noted in the nonfixation and NBCA only groups, whereas two cases (2.2%) were noted in the ST group and one case (2.1%) in the NBCA + ST group (P = 0.005).

Conclusions

The use of NBCA medical adhesive for noninvasive patch fixation in laparoscopic hernia repair (TAPP) is effective and safe.     

The effects of different prosthetic materials on the formation of collagen types in incisional hernia

Objective

The aim of this study was to determine the rate of collagen Type I/Type III for different meshes.

Method

Fifty rats were used. Five groups were formed: prolene (n = 10), mersilene (n = 10), parietex (n = 10), e PTFE (n = 10) and control group (n = 10). In all animals, laparotomy was performed using a midline incision. After that four different kinds of meshes are placed into the retro-rectus plane and fixed with a non-absorbable suture. Rectus superficial fascia and skin are closed. In the control group, repairment is done primarily. Thirty days later, meshes are found through the incisions that were done previously. Scar tissues above and near by meshes and also in the control group are taken, and in these tissue samples, the ratio of Type I/III is evaluated histochemically.

Results

The Prolene mesh was found to contain more collagen fibers than e PTFE. As a result of the histopathologic evaluation, it was seen that Group I contained statistically significantly more collagen density than the other four groups (p < 0.05). Moreover, the collagen Type I/III ratio in the specimen taken from the top part and the surrounding area of Group I was found significantly higher than the collagen Type I/III ratios of the rest of the groups (p < 0.05).

Conclusion

As a conclusion, the ratio of collagen Type I/III is the highest in the prolene group.     

Early and late postoperative inflammatory and collagen deposition responses in three different meshes: an experimental study in rats

Purpose

Although meshes reduce abdominal hernia recurrence, they increase the risk of inflammatory complications. This study aimed to compare the early and late postoperative inflammation and collagen deposition responses induced by three meshes.

Methods

Rats were allocated into three groups. In group I, a polypropylene (PP) mesh was implanted in the abdominal wall. In groups II and III, PP + polyglactin (PP + PG) and PP + titanium (PP + TI) meshes were employed, respectively. On the seventh (7th) postoperative day, collagen deposition and inflammation were evaluated, and immunohistochemistry was performed on abdominal wall biopsies. These data were compared with those obtained on the fortieth (40th) postoperative day in a previous study.

Results

The early inflammatory responses were the same in all groups. With time, it decreased in group I (p = 0.047) and increased in group II (p = 0.003). Group I exhibited early elevated VEGF (p < 0.001), COX2 (p < 0.001), and collagen (p = 0.023) levels, and group II exhibited the most severe inflammatory tissue response. On the 40th postoperative day, the VEGF (p < 0.001) and collagen (p < 0.005) were reduced as compared with the 7th postoperative day in all groups.

Conclusions

Belatedly, the inflammatory reaction decreased in PP mesh group and increased in PP + PG mesh group. The PP mesh induced early great elevations in VEGF, COX2 and collagen levels, whereas the PP + PG mesh caused severe tissue inflammation with small elevation in these levels. PP + TI mesh induced inflammatory response levels between the others. In conclusion, the inflammatory response depends on the mesh density and also the mesh material with clinical implications.     

Biologic meshes are not superior to synthetic meshes in ventral hernia repair: an experimental study with long-term follow-up evaluation

Background

In laparoscopic incisional hernia repair, direct contact between the prosthesis and the abdominal viscera is inevitable, which may lead to an inflammatory reaction resulting in abdominal adhesion formation. This study compared five different synthetic and biologic meshes in terms of adhesion formation, shrinkage, incorporation, and histologic characteristics after a period of 30 and 90 days.

Methods

In 85 rats, a mesh was positioned intraperitoneally in direct contact with the viscera. Five different meshes were implanted: Prolene (polypropylene), Parietex composite (collagen-coated polyester), Strattice (porcine dermis, non-cross-linked), Surgisis (porcine small intestine submucosa, non-cross-linked), and Permacol (porcine dermis, cross-linked). The meshes were tested in terms of adhesion formation, shrinkage, and incorporation after a period of 30 and 90 days. Additionally, collagen formation after 90 days was determined.

Results

Significantly less adhesion formation was observed with Parietex composite (5 %; interquartile range [IQR], 2–5 %) and Strattice (5 %; IQR, 4–10 %) in the long term. In contrast, organs were attached to Permacol with four of seven meshes (57 %), and adhesion coverage of Surgisis mesh was present in 66 % (IQR, 0–100 %) of the cases. After 90 days, the best incorporation was seen with the Parietex composite mesh (79 %; IQR, 61–83 %). After 90 days, major alterations in adhesion formation were seen compared with 30 days. Histologically, Strattice and Parietex composite showed a new mesothelial layer on the visceral side of the mesh. Microscopic degradation and new collagen formation were seen in the Surgisis group.

Conclusions

Parietex composite mesh demonstrated the best long-term results compared with all the other meshes. The biologic non-cross-linked mesh, Strattice, showed little adhesion formation and moderate shrinkage but poor incorporation. Biologic meshes are promising, but varying results require a more detailed investigation and demonstrate that biologic meshes are not necessarily superior to synthetic meshes. The significant changes that take place between 30 and 90 days should lead to careful interpretation of short-term experimental results.     

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.     

Coated meshes for hernia repair provide comparable intraperitoneal adhesion prevention

Background

Laparoscopic incisional hernia repair with intraperitoneal mesh is associated with a certain degree of adhesion formation to the mesh. This experimental study examined the efficacy of several coated meshes for adhesion reduction.

Methods

Five commercially available meshes with a layered coating were placed intraperitoneally in rats and followed up for 90 days: polypropylene and polyester meshes, both coated with absorbable collagen (Parietene Composite and Parietex Composite, respectively), and three polypropylene meshes respectively coated with absorbable omega-3 fatty acids (C-Qur Edge), absorbable cellulose (Sepramesh IP), and nonabsorbable expanded polytetrafluoroethylene (Intramesh T1). Uncoated polypropylene and collagen meshs (Parietene and Permacol, respectively) served as the control condition. Adhesions, incorporation, and tissue reaction were evaluated macro- and microscopically. Additionally, the development of the neoperitoneum was examined.

Results

All the coated meshes performed equally well in terms of adhesion reduction. The collagen mesh performed comparably, but the uncoated polypropylene mesh performed significantly worse. The different coatings led to very differing degrees of inflammation. Ingrowth was observed only at the place of suture but was comparable for all the meshes except C-Qur Edge, which showed the weakest incorporation. Development of a neoperitoneum on the mesh surface occurred independently of whether an absorbable or nonabsorbable coating or no coating at all was present.

Conclusions

Commercially available meshes with a layered coating deliver comparable adhesion reduction. The physical presence of a layered coating between the intraperitoneal content and the abdominal wall seems to be more important than the chemical properties of the coating in adhesion formation.     

Infected large pore meshes may be salvaged by topical negative pressure therapy

Purpose

To evaluate the efficacy of negative pressure therapy for superficial and deep mesh infections after ventral and incisional hernia repair by a prospective monocentric observational study.

Methods

During a 6-year period, 724 consecutive open ventral and incisional hernia repairs were performed. Pre- and intraoperative data as well as postoperative complications were prospectively recorded. In case of wound infection, negative pressure therapy (NPT) was our primary treatment.

Results

Sixty-three patients (8.7 %) were treated using negative pressure therapy after primary ventral and incisional hernia repair. Infectious complications needing NPT occurred in 54 patients in the retromuscular group (54/523; 10.3 %), none when laparoscopically treated and in 9 patients (9/143; 6.3 %) treated by an open intraperitoneal mesh technique. Considering outcome, all meshes were completely salvaged in the retromuscular mesh group after a median of 5 dressing changes (range, 2–9), while in the intraperitoneal mesh, group 3 meshes needed complete (n = 2) or partial (n = 1) excision. Mean duration to complete wound closure was 44 days (range, 26–63 days).

Conclusion

NPT is a useful adjunct for salvage of deep infected meshes, particularly when large pore monofilament mesh is used.     

Remodeling characteristics and collagen distribution in synthetic mesh materials explanted from human subjects after abdominal wall reconstruction: an analysis of remodeling characteristics by patient risk factors and surgical site classifications

Background

The purpose of this study was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of synthetic meshes biopsied from their abdominal wall repair sites in the first attempt to generate a multivariable risk prediction model of non-constructive remodeling.

Methods

Biopsies of the synthetic meshes were obtained from the abdominal wall repair sites of 51 patients during a subsequent abdominal re-exploration. Biopsies were stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell infiltration, cell types, extracellular matrix deposition, inflammation, fibrous encapsulation, and neovascularization) and a mean composite score (CR). Biopsies were also stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a threshold p value of ≤0.200.

Results

The model selection process for the extracellular matrix score yielded two variables: subject age at time of mesh implantation, and mesh classification (c-statistic = 0.842). For CR score, the model selection process yielded two variables: subject age at time of mesh implantation and mesh classification (r ² = 0.464). The model selection process for the collagen III area yielded a model with two variables: subject body mass index at time of mesh explantation and pack-year history (r ² = 0.244).

Conclusion

Host characteristics and surgical site assessments may predict degree of remodeling for synthetic meshes used to reinforce abdominal wall repair sites. These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances for which non-constructive remodeling of an abdominal wall repair site with synthetic mesh reinforcement is most likely to occur.     

Inguinal hernia repair using a synthetic long-term resorbable mesh: results from a 3-year prospective safety and performance study

Purpose

Conventional meshes for hernia repair and abdominal wall reinforcement are usually made from polypropylene, polyester or other synthetic plastic materials known to promote foreign body reactions and a state of chronic inflammation that may lead to long-term complications. A novel approach is to use long-term resorbable implants like TIGR^® Matrix Surgical Mesh. Preclinical studies have shown that this mesh maintains mechanical integrity beyond the point in time where newly formed tissue is capable of carrying the abdominal loads.

Methods

This was a first-in-man, prospective, pilot study performed during 2009, at two sites in Sweden. Forty patients with primary inguinal hernias were enrolled for Lichtenstein repair using TIGR^® Matrix Surgical Mesh. The primary endpoint was safety as assessed by monitoring the incidence of adverse events and serious adverse events (SAEs) both related and unrelated to the mesh. The secondary endpoint was pain or discomfort. Visual Analogue Scale (VAS) 0–10 and Inguinal Pain Questionnaire were used for scoring pain and discomfort. Included patients have been followed for 36 months using ultrasound in combination with clinical examination.

Results

All patients followed a normal early postoperative course. After 12 months no SAEs were reported. None of the patients with an isolated lateral inguinal hernia (LIH) had developed a recurrence but 4 (44 %) with medial and 4 (33 %) with combined hernias had recurred at 36-month follow-up. After 3-year follow-up none of the patients with LIH reported pain in the VAS-form and none of those patients could feel the sensation of a mesh in their groin. In the total study population 5 (16 %) patients experienced chronic pain in the form of mild sporadic pain and 3 (9.7 %) patients could feel the sensation of a mesh in their groin.

Conclusion

The use of a synthetic long-term resorbable mesh (TIGR^® Matrix Surgical Mesh) in Lichtenstein repair was found to be safe, without recurrences, and promising regarding pain/discomfort at 3-year follow-up in patients with LIH. However, patients with medial and combined inguinal hernias had high recurrence rates.     

Does Presoaking Synthetic Mesh in Antibiotic Solution Reduce Mesh Infections? An Experimental Study

Background

Prosthetic mesh infection is one of the most challenging complications after hernia repair. We evaluate the efficacy of soaking mesh in antibiotics to prevent prosthetic infection in an animal model of clean–contaminated ventral hernia repair (VHR).

Material and Methods

Rats underwent an acute VHR with one of four synthetic meshes (composite multifilament polyester (Parietex PCO), multifilament polyester (Parietex TET), composite monofilament polypropylene (Ventralight), or monofilament polypropylene (SoftMesh)). Prior to implantation, mesh was soaked in saline or 10 mg/ml of vancomycin for 15 min. Following implantation, meshes were contaminated with 10⁴ CFU of methicillin-resistant Staphylococcus aureus (MRSA) bacteria. Thirty days after implantation, mesh samples were cultured and evaluated under scanning electron microscope for biofilm formation.

Results

Presoaking meshes significantly improves bacterial clearance in composite meshes and multifilament polyester mesh. MRSA clearance was as follows for all meshes (saline-soaked vs. vanco-soaked): Parietex PCO (0 vs. 56 %, p?=?0.006), Parietex TET (0 vs. 50 %, p?=?0.01), Ventralight (20 vs. 78 %, p?=?0.012), and SoftMesh (70 vs. 80 %, p?=?0.6). MRSA biofilm formation was consistent with bacterial growth.

Conclusion

Presoaking multifilament and composite mesh in vancomycin solution reduces MRSA bacterial growth. Its implementation may reduce the risk of mesh infection in clean–contaminated cases, although further investigation with human trials should be performed.     

What do we know about titanized polypropylene meshes? An evidence-based review of the literature

Purpose

Despite the vast selection of brands available, nearly all synthetic meshes for hernia surgery continue to use one or other of three basic materials: polypropylene, polyester and ePTFE. These are used in combination with each other or with a range of additional materials such as titanium, omega 3, monocryl, PVDF and hyaluronate. This systematic review of all experimental and clinical studies is aimed at investigating whether titanized meshes confer advantages over other synthetic meshes in hernia surgery.

Materials and methods

A search of the medical literature from 2002 to 2012, as indexed by Medline, was performed, using the PubMed search engine (http://www.pubmed.gov). The search terms were: hernia mesh, titanium coating, lightweight mesh, TiMesh, mesh complications. All papers were graded according to the Oxford hierarchy of evidence.

Results

Patients operated on with the Lichtenstein technique performed using the lightweight titanium-coated mesh have a shorter convalescence than those with the heavy-weight mesh Prolene. For inguinal hernias operated on with the TAPP technique and using a lightweight titanium-coated mesh in comparison to a heavy-weight Prolene mesh, the early postoperative convalescence seems to improve. Titanized meshes do exhibit a negative effect on sperm motility 1 year after a TEP operation, but not after 3 years. The laparoscopic IPOM technique with a titanium-coated polypropylene mesh was associated with less postoperative pain in the short term, lower analgesic consumption and a quicker return to everyday activities compared with the Parietex composite mesh.

Conclusion

In clinical studies, the titanium-coated polypropylene mesh shows in inguinal hernia repair certain benefits compared with the use of older heavy-weight meshes.     

TiLoop® Bra mesh used for immediate breast reconstruction: comparison of retropectoral and subcutaneous implant placement in a prospective single-institution series

Background

Immediate implant reconstruction after a conservative mastectomy is an attractive option made easier by prosthetic devices. Titanized polypropylene meshes are used as a hammock to cover the lower lateral implant pole. We conducted a prospective nonrandomized single-institution study of reconstructions using titanium-coated meshes either in a standard muscular mesh pocket or in a complete subcutaneous approach. The complete subcutaneous approach means to wrap an implant with titanized mesh in order to position the implant subcutaneously and spare muscles.

Methods

Between November 2011 and January 2014, we performed immediate implant breast reconstructions after conservative mastectomies using TiLoop® Bra, either with the standard retropectoral or with a prepectoral approach. Selection criteria included only women with normal Body Mass Index (BMI), no large and very ptotic breasts, no history of smoking, no diabetes, and no previous radiotherapy. We analyzed short-term outcomes of such procedures and compared the outcomes to evaluate implant losses and surgical complications.

Results

A total of 73 mastectomies were performed. Group 1 comprised 29 women, 5 bilateral procedures, 34 reconstructions, using the standard muscular mesh pocket. Group 2 comprised 34 women, 5 bilateral procedures, 39 reconstructions with the prepectoral subcutaneous technique. Baseline and oncologic characteristics were homogeneous between the two groups. After a median follow-up period of 13 and 12 months, respectively, no implant losses were recorded in group 1, and one implant loss was recorded in group 2. We registered three surgical complications in group 1 and two surgical complications in group 2.

Conclusions

Titanium-coated polypropylene meshes, as a tool for immediate definitive implant breast reconstruction, resulted as safe and effective in a short-term analysis, both for a retropectoral and a totally subcutaneous implant placement. Long-term results are forthcoming. A strict selection is mandatory to achieve optimal results. Level of Evidence: Level II, therapeutic study.     

Mesh Repair Versus Non-Mesh Repair for Strangulated Inguinal Hernia: Systematic Review with Meta-Analysis

Background

The optimal technique to cure strangulated inguinal hernia remains controversial. The use of mesh in cases of strangulated hernia is still debated due to the potential risk of infection.

Objective

This systematic review aimed to determine whether or not the mesh repair technique is associated with a higher risk of surgical site infection than non-mesh techniques for strangulated inguinal hernias in adults.

Methods

An electronic search of the relevant literature was performed on 15 December 2012 using the following databases: MEDLINE, the Cochrane Library, Scopus, Embase, and the Web of Science. Articles reporting a comparison between the mesh repair technique and a non-mesh technique to treat strangulated inguinal hernias in adults, and published in the English or French language in a peer-reviewed journal, were considered for analysis. The quality of randomized controlled trials (RCTs) was assessed using the Jadad scoring system. To assess the quality of non-randomized trials, we used the Methodological Index for Non-Randomized Studies (MINORS).

Results

A total of 232 papers was found in the initial search; nine were included in the meta-analysis. The wound infection rate in the mesh repair technique group was lower than in the control group, with a trend towards significance (odds ratio [OR] 0.46, 95 % confidence interval [CI] 0.20–1.07; p = 0.07). The hernia recurrence rate was lower in the mesh repair group (OR 0.2, 95 % CI 0.05–0.78; p = 0.02).

Conclusion

The mesh repair technique is a good option for the treatment of strangulated inguinal hernias in adults, giving an acceptable wound infection rate and fewer recurrences than non-mesh repair. Our study does not allow us to recommend the use of mesh in cases of bowel resection. We emphasize that, except the two RCTs, the results are predicated on patient selection bias by careful surgeons. Further RCTs are required to obtain more powerful evidence-based data.