Evaluation of composite mesh for ventral hernia repair

A keyhole approach gives a sound repair for ileal conduit parastomal hernia

PURPOSE

The purpose of this study was to report and evaluate a laparoscopic surgical technique for the treatment of parastomal hernia (PSH) after ileal conduit urinary diversion aiming to minimize PSH recurrence and perioperative complications.

METHODS

We retrospectively evaluated all patients who underwent a PSH (after ileal conduit urinary diversion) repair at Addenbrookes Hospital, Cambridge. As a surgical approach, a laparoscopic repair with mesh was utilized in all cases. Subsequently, we performed a voluntary follow-up of the patients to evaluate long-term recurrence and complication rates. In addition, we conducted a reassessment of the cross-sectional imaging available.

RESULTS

Between November 2008 and December 2019, 27 patients underwent hernia repair due to a clinically significant hernia. Out of those patients, one suffered from a post-operative wound infection. In total 23 patients participated in the follow-up with a median follow-up period of 91 months. Follow-up examination revealed two cases of recurrent PSH (8.7% of patients followed up), four patients suffered from minor complications (14.8%).

CONCLUSION

Repair of PSH associated with ileal conduit is particularly scarce. Our surgical approach presents the only laparoscopic case series of an effective method for treating a PSH from an ileal conduit with a low complication and recurrence rate.

Evaluation of In Vivo Adhesion Properties of New Generation Polyglactin, Oxidized Regenerated Cellulose and Chitosan-Based Meshes for Hernia Surgery

Introduction

Composite meshes coated with anti-adhesive barriers have been developed by taking advantage of the robustness of polypropylene meshes for use in hernia repair. We aimed to evaluate the effects of composite meshes containing polyglactin, polycaprolactone, oxidized regenerated cellulose and chitosan on the adhesion formation.

Methods

Forty-two Sprague Dawley male rats were divided into six groups of seven rats according to the content of the meshes used. A defect was created on the right abdominal wall of the rats and an oval composite mesh of 2 cm in diameter was placed over the defect and fixed. The rats were sacrificed under anesthesia on the 7th postoperative day. Macroscopic and histopathological examination was performed and the incorporation of the mesh with the abdominal wall and the presence of intraabdominal adhesions were evaluated.

Results

When the macroscopic findings of the rats were evaluated, there was a statistically significant difference between the rat groups in terms of the distribution of peritoneal adhesion scores (p<0.05). There was no statistically significant difference between the rat groups in terms of the distribution of inflammation, fibrosis and macrophage levels (p>0.05).

Conclusion

It was evaluated that the development of intraabdominal adhesion and the strength of adhesion decreased when biocompatible adhesion barriers with anti-adhesive properties such as oxidized regenerated cellulose and chitosan were used in the structure of composite meshes used in hernia repair. Hemostatic and antibacterial properties of these substances are promising to create the ideal mesh.

Development of electrospun core-shell polymeric mat using poly (ethyl-2) cyanoacrylate/polyurethane to attenuate biological adhesion on polymeric mesh implants

Poly (ethyl-2) cyanoacrylate was used to create an adhesion-free biocompatible non-woven material reinforced by polyurethane core via a co-axial electrospinning set-up. The effect of relative humidity (RH) of (18, 30, 40, 60, and 68) % on the electrospinning process was examined, and found that in order to achieve well defined core-shell fiber structure, the optimal RH was 18%. If the RH is >18%, a phenomenon called Taylor cone cyclic destabilization occurs, which results in unfavorable surface and mechanical properties of the mat. The developed composite electrospun mat has the potential to be used in medical devices, such as repairing the viscera layer for intraperitoneal hernia mesh implants, which require the attenuation of biological elements, and adequate mechanical properties.

Biomaterial Implants in Abdominal Wall Hernia Repair: A Review on the Importance of the Peritoneal Interface

Biomaterials have long been used to repair defects in the clinical setting, which has led to the development of a wide variety of new materials tailored to specific therapeutic purposes. The efficiency in the repair of the defect and the safety of the different materials employed are determined not only by the nature and structure of their components, but also by the anatomical site where they will be located. Biomaterial implantation into the abdominal cavity in the form of a surgical mesh, such as in the case of abdominal hernia repair, involves the contact between the foreign material and the peritoneum. This review summarizes the different biomaterials currently available in hernia mesh repair and provides insights into a series of peculiarities that must be addressed when designing the optimal mesh to be used in this interface.

* The New Zealand White Rabbit as a Model for Preclinical Studies Addressing Tissue Repair at the Level of the Abdominal Wall

In this report, we review the use of the New Zealand White rabbit as the experimental animal for several models of abdominal wall repair. For the repair of an abdominal wall defect, such as a hernia in clinical practice, multiple types of prosthetic material exist. Before their marketing, each of these biomaterials needs to be tested in a preclinical setting to confirm its biocompatibility and appropriate behavior at the different tissue interfaces. For preclinical trials, we have always used the New Zealand White rabbit as the model owing to its ease of handling and suitable size. This size allows for laparoscopic studies designed to follow the behavior in real time of a biomaterial implanted at the peritoneal interface, a delicate interface that often gives rise to complications in human practice. The size of the rabbit also offers a sufficiently large number of implant samples to be harvested for a complete battery of tests at several time points postimplant. In this review, we first describe the models established and then provide the results obtained so far using these models to test the different types of biomaterial. We end our review with a discussion of the clinical implications of these results.

Evaluation of the ability of Acinetobacter baumannii to form biofilms on six different biomedical relevant surfaces

The human opportunistic pathogen, Acinetobacter baumannii, has the propensity to form biofilms and frequently cause medical device-related infections in hospitals. However, the physio-chemical properties of medical surfaces, in addition to bacterial surface properties, will affect colonization and biofilm development. The objective of this study was to compare the ability of A. baumannii to form biofilms on six different materials common to the hospital environment: glass, porcelain, stainless steel, rubber, polycarbonate plastic and polypropylene plastic. Biofilms were developed on material coupons in a CDC biofilm reactor. Biofilms were visualized and quantified using fluorescent staining and imaged using confocal laser scanning microscopy (CLSM) and by direct viable cell counts. Image analysis of CLSM stacks indicated that the mean biomass values for biofilms grown on glass, rubber, porcelain, polypropylene, stainless steel and polycarbonate were 0·04, 0·26, 0·62, 1·00, 2·08 and 2·70 μm(3) /μm(2) respectively. Polycarbonate developed statistically more biofilm mass than glass, rubber, porcelain and polypropylene. Viable cell counts data were in agreement with the CLSM-derived data. In conclusion, polycarbonate was the most accommodating surface for A. baumannii ATCC 17978 to form biofilms while glass was least favourable. Alternatives to polycarbonate for use in medical and dental devices may need to be considered.

SIGNIFICANCE AND IMPACT OF THE STUDY

In the hospital environment, Acinetobacter baumannii is one of the most persistent and difficult to control opportunistic pathogens. The persistence of A. baumannii is due, in part, to its ability to colonize surfaces and form biofilms. This study demonstrates that A. baumannii can form biofilms on a variety of different surfaces and develops substantial biofilms on polycarbonate - a thermoplastic material that is often used in the construction of medical devices. The findings highlight the need to further study the in vitro compatibility of medical materials that could be colonized by A. baumannii and allow it to persist in hospital settings.

Which mesh or graft? Prosthetic devices for abdominal wall reconstruction

This article reviews the ever-increasing number of prosthetic devices--both synthetic mesh and biologic grafts--now in use for abdominal wall reconstruction. It also introduces a novel hybrid synthetic/biologic graft (Zenapro) and suture passer device (Novapass).

In vivo response to polypropylene following implantation in animal models: a review of biocompatibility

INTRODUCTION AND HYPOTHESIS

Polypropylene is a material that is commonly used to treat pelvic floor conditions such as pelvic organ prolapse (POP) and stress urinary incontinence (SUI). Owing to the nature of complications experienced by some patients implanted with either incontinence or prolapse meshes, the biocompatibility of polypropylene has recently been questioned. This literature review considers the in vivo response to polypropylene following implantation in animal models. The specific areas explored in this review are material selection, impact of anatomical location, and the structure, weight and size of polypropylene mesh types.

METHODS

All relevant abstracts from original articles investigating the host response of mesh in vivo were reviewed. Papers were obtained and categorised into various mesh material types: polypropylene, polypropylene composites, and other synthetic and biologically derived mesh.

RESULTS

Polypropylene mesh fared well in comparison with other material types in terms of host response. It was found that a lightweight, large-pore mesh is the most appropriate structure.

CONCLUSION

The evidence reviewed shows that polypropylene evokes a less inflammatory or similar host response when compared with other materials used in mesh devices.

Comparative efficacy of Prolene and Prolene-Vicryl composite mesh for experimental ventral hernia repair in dogs

In this study, efficacy of two hernia mesh implants viz. conventional Prolene and a novel Prolene-Vicryl composite mesh was assessed for experimental ventral hernia repair in dogs. Twelve healthy mongrel dogs were selected and randomly divided into three groups, A, Band C (n=4). In all groups, an experimental laparotomy was performed; thereafter, the posterior rectus sheath and peritoneum were sutured together, while, a 5 × 5 cm defect was created in the rectus muscle belly and anterior rectus sheath. For sublay hernioplasty, the hernia mesh (Prolene: group A; Prolene-Vicryl composite mesh: group B), was implanted over the posterior rectus sheath. In group C (control), mesh was not implanted; instead the laparotomy incision was closed after a herniorrhaphy. Post-operative pain, mesh shrinkage and adhesion formation were assessed as short term complications. Post-operatively, pain at surgical site was significantly less (P<0.001) in group B (composite mesh); mesh shrinkage was also significantly less in group B (21.42%, P<0.05) than in group A (Prolene mesh shrinkage: 58.18%). Group B (composite mesh) also depicted less than 25% adhesions (Mean ± SE: 0.75 ± 0.50 scores, P≤0.013) when assessed on the basis of a Quantitative Modified Diamond scale; a Qualitative Adhesion Tenacity scale also depicted either no adhesions (n=2), or, only flimsy adhesions (n=2) in group B (composite mesh), in contrast to group A (Prolene), which manifested greater adhesion formation and presence of dense adhesions requiring blunt dissection. Conclusively, the Prolene-Vicryl composite mesh proved superior to the Prolene mesh regarding lesser mesh contraction, fewer adhesions and no short-term follow-up complications.

Pore size and pore shape--but not mesh density--alter the mechanical strength of tissue ingrowth and host tissue response to synthetic mesh materials in a porcine model of ventral hernia repair

BACKGROUND

Over 100 types of soft tissue repair materials are commercially available for hernia repair applications. These materials vary in characteristics such as mesh density, pore size, and pore shape. It is difficult to determine the impact of a single variable of interest due to other compounding variables in a particular design. Thus, the current study utilized prototype meshes designed to evaluate each of these mesh parameters individually.

METHODS

Five prototype meshes composed of planar, monofilament polyethylene terephthalate (PET) were evaluated in this study. The meshes were designed to focus on three key parameters, namely mesh density, pore size, and pore shape. The prototype meshes were implanted in the preperitoneal, retrorectus space in a porcine model of ventral incisional hernia repair, and tissue ingrowth characteristics were evaluated after 90 days. Mesh-tissue composite specimens were obtained from each repair site and evaluated via T-peel mechanical testing. Force-displacement data for each T-peel test were analyzed and five characteristics of tissue ingrowth reported: peak force (fp), critical force (fc), fracture energy (Γc), work (W), and work density (Wden). Hematoxylin and eosin (H&E) stained sections of explanted mesh-tissue composites were also assessed for characteristics of tissue response including cellular infiltration, cell types, inflammatory response, extracellular matrix deposition, neovascularization, and fibrosis, with a composite score assigned to represent overall tissue response.

RESULTS

The medium-weight, very large pore, hexagonal (MWVLH) mesh performed significantly better than the light-weight, medium pore, diamond (LWMD) mesh for all parameters evaluated (fp, fc, Γc, W, Wden) and trended toward better results than the medium-weight, medium pore, diamond (MWMD) mesh for the majority of the parameters evaluated. When the data for the five meshes was grouped to evaluate mesh density, pore size, and pore shape, differences were more pronounced. No significant differences were observed with respect to mesh density, however significant improvement in mechanical strength of tissue ingrowth occurred as pore size increased from medium to very large. In addition, the hexagonal pores resulted in the strongest tissue ingrowth, followed by the square pores, and finally the diamond pores. Scores for several histological parameters were significantly different for these prototype meshes. For example, the MWVLH mesh showed significantly greater tissue ingrowth by neovascularization histological score than MWMD and MWVLS meshes (p<0.05) and significantly less fibrosis than LWMD and MWVLS meshes (p<0.05).

CONCLUSION

Pore shape and pore size significantly altered the mechanical strength of tissue ingrowth and host-site integration in a porcine model of ventral hernia repair, while mesh density had no effect.

Outcomes of a prospective multi-center trial of a second-generation composite mesh for open ventral hernia repair

PURPOSE

Composite mesh prostheses incorporate properties of multiple materials for use in open ventral hernia repair (OVHR). This study examines clinical outcomes in patients who underwent OVHR with a polypropylene/expanded polytetrafluoroethylene (ePTFE) composite graft containing a novel polydioxanone (PDO) absorbable ring to facilitate placement and graft positioning.

METHODS

Data were prospectively collected on consecutive patients undergoing OVHR using a synthetic composite mesh. Seven centers enrolled patients during the study period. All patients underwent a standardized surgical procedure consisting of OVHR with sublay intraperitoneal placement of mesh. Mesh fixation was accomplished with peripheral tacks and transfascial sutures.

RESULTS

One hundred and nineteen patients underwent OVHR with the composite mesh. Average age was 55.8 years; there were 71 (59.7 %) females and 48 (40.3 %) males with mean BMI of 33.5 ± 7.1 kg/m(2). One hundred and two (85.7 %) patients presented with primary ventral hernias. Mean defect size was 13.6 cm(2), and mean mesh size was 113.6 cm(2). Most patients (67 %) were discharged the day of surgery. Twelve patients (10.1 %) experienced complications in the perioperative time period primarily consisting of seroma (4.2 %) and ileus (1.7 %). Two patients required reoperation and mesh removal in the early postoperative period for infection and herniorrhaphy site pain, respectively. There was a decline in pain and movement limitation scores between baseline and 1-year follow-up. Six-month (n = 109) and twelve-month (n = 99) follow-up revealed no hernia recurrences (95 % CI 0-3 %, and 0-4 %, respectively).

CONCLUSIONS

The use of this second-generation composite mesh was associated with no hernia recurrences and a low complication rate after open ventral hernia repair.