Influence of polyglecaprone 25 (Monocryl) supplementation on the biocompatibility of a polypropylene mesh for hernia repair

Mesh alone versus combined darn and mesh in primary inguinal hernia repair in adults: a randomized control trial

Despite the availability of laparoscopy, open surgery remains the most common practice for primary inguinal hernia repair in general surgery. This study aimed to evaluate the combined mesh and darn (CMD) repair compared to mesh alone (MA) repair in treating adult inguinal hernias regarding recurrence and postoperative complications. We conducted a prospective randomized study, including 330 patients with primary inguinal hernias who underwent primary inguinal hernia repair at our facilities between February 2015 and January 2018. Time spent in the hospital, time to resume regular activities, postoperative sequelae, and recurrence rates were assessed. Patients were randomly assigned to 2 groups: CMD repair was performed on 165 patients (Group 1), and MA repair was done on 165 patients (Group 2). Patients were monitored for three years. The average operation time for MA was 62.2 minutes, compared to 72.9 minutes for CMD. The average time to return to normal work was comparable for both groups at around 3 weeks. In Group 2, 12 (7.1%) patients experienced postoperative complications and 3 (1.7%) recurrences. In the CMD repair group, 13 (8.1%) patients had postoperative complications, but no recurrences were observed. Hospitalization duration and postoperative pain were similar between the two groups. At the three-year follow-up, the CMD repair demonstrated a lower recurrence rate than MA, while both groups had similar postoperative complications, hospital stays, and return to normal activities. The operative time was slightly longer for CMD repair compared to MA repair.

Phase estimation for investigating the optical and mechanical properties of Monocryl suture for soft tissue approximation and ligation

Monocryl is a bio-absorbable suture composed of a polyglycolide and poly-epsiloncaprolactone copolymer material and is considered a promising candidate for soft tissues approximation. Consequently, the physical, mechanical, and morphological properties are essential for the surgeons to select the suitable suture for their surgical perform. In this article, Mach Zehnder interferometer equipped with a mechanical drawing device are used for evaluating the mechanical properties and a better understanding of how the Monocryl suture reacts to loading. The two-dimensional fast Fourier transform is applied to extract the phase from the captured interference microinterferograms at different draw ratios. The extracted phase helps to determine some opto-mechanical and structural properties of Monocryle suture. Quantitative structure-activity relationships model is employed for investigating the biological activity of the tested suture. The stress-strain behavior of Monocryl suture has a J-shaped behavior which compatible with the behavior of the soft tissues. The molecular electrostatic potential maps showed that Monocryl model structure is proved to be electrophilic interplays.

Self-adhesive hydrogel meshes reduce tissue incorporation and mechanical behavior versus microgrips self-fixation: a preclinical study

Purpose

Atraumatic mesh fixation for abdominal hernia repair has been developed to avoid the disadvantages of classical fixation with sutures, which is considered a cause of chronic pain and discomfort. This study was designed to analyze, in the short and medium term, the biological and mechanical behavior of two self-fixing meshes compared to that of a polypropylene (PP) mesh fixed with a cyanoacrylate (CA) tissue adhesive.

Methods

Partial abdominal wall defects (6 × 4 cm) were created in New Zealand rabbits (n = 36) and repaired using a self-adhesive hydrogel mesh (Adhesix™), a self-gripping mesh (ProGrip™) or a PP mesh fixed with CA (Surgipro™ CA). After 14 and 90 days, the host tissue incorporation, macrophage response and biomechanical strength were examined.

Results

At 14 and 90 days, the ProGrip and Surgipro CA meshes showed good host tissue incorporation; however, the Adhesix implants presented poor integration, seroma formation and a higher degree of shrinkage. The Adhesix hydrogel was completely reabsorbed at 14 days, whereas ProGrip microhooks were observed at all study times. The macrophage response was higher in the ProGrip and Surgipro CA groups at 14 and 90 days, respectively, and decreased over time. At 90 days, the ProGrip implants showed the highest tensile strength values and the Adhesix implants showed the highest failure stretch.

Conclusion

Meshes with mechanical microgrip self-fixation (ProGrip) show better biological and mechanical behavior than those with adhesive hydrogel (Adhesix) in a preclinical model of abdominal hernia repair in rabbits.

Polymer Hernia Repair Materials: Adapting to Patient Needs and Surgical Techniques

Biomaterials and their applications are perhaps among the most dynamic areas of research within the field of biomedicine. Any advance in this topic translates to an improved quality of life for recipient patients. One application of a biomaterial is the repair of an abdominal wall defect whether congenital or acquired. In the great majority of cases requiring surgery, the defect takes the form of a hernia. Over the past few years, biomaterials designed with this purpose in mind have been gradually evolving in parallel with new developments in the different surgical techniques. In consequence, the classic polymer prosthetic materials have been the starting point for structural modifications or new prototypes that have always strived to accommodate patients’ needs. This evolving process has pursued both improvements in the wound repair process depending on the implant interface in the host and in the material’s mechanical properties at the repair site. This last factor is important considering that this site—the abdominal wall—is a dynamic structure subjected to considerable mechanical demands. This review aims to provide a narrative overview of the different biomaterials that have been gradually introduced over the years, along with their modifications as new surgical techniques have unfolded.

Rabbit as an animal model for the study of biological grafts in pelvic floor dysfunctions

The aims of this study were to evaluate the feasibility of the New Zealand White (NZW) rabbit for studying implanted biomaterials in pelvic reconstructive surgery; and to compare the occurrence of graft-related complications of a commercial polypropylene (PP) mesh and new developed human dermal matrix implanted at vaginal and abdominal level. 20 white female NZW rabbits were randomized into two groups, experimental group (human acellular dermal matrices-hADM-graft) and control group (commercial PP graft). In each animal, grafts were surgically implanted subcutaneously in the abdominal wall and in the vaginal submucosa layer for 180 days. The graft segments were then removed and the surgical and clinical results were analyzed. The main surgical challenges during graft implantation were: (a) an adequate vaginal exposure while maintaining the integrity of the vaginal mucosa layer; (b) to keep aseptic conditions; (c) to locate and dissect the breast vein abdominal surgery; and (d) to withdraw blood samples from the ear artery. The most abnormal findings during the explant surgery were found in the PP group (33% of vaginal mesh extrusion) in comparison with the hADM group (0% of vaginal graft extrusion), p = 0.015. Interestingly, macroscopic observation showed that the integration of the vaginal grafts was more common in the hADM group (40%) than in the PP group, in which the vaginal mesh was identified in 100% of the animals (p = 0.014). The NZW rabbit is a good model for assessing materials to be used as grafts for pelvic reconstructive surgery and vaginal surgery. Animals are easily managed during the procedures, including surgical intervention and vaginal mucosa approach. Additionally, hADM is associated with fewer clinical complications, as well as better macroscopic tissue integration, compared to PP mesh.

A predictive micromechanically-based model for damage and permanent deformations in copolymer sutures

An effective description of the mechanical behavior of biodegradable copolymers suture threads requires the analysis of their response under cyclic loading and the prediction of the fundamental damage and residual stretches effects. In this paper we propose a micromechanically-based model adopting a new form of Worm Like Chain free energy for the copolymer chains, which takes care of the insurgence of residual stretches on the basis of a rigorous statistical mechanics result. Under the affinity hypothesis we subsequently derive the macroscopic response of the material. The obtained model has a clear physical interpretation and depends on a small number of parameters, which can be fitted by a simple uniaxial test. The effectiveness of the theoretical results has then been verified by performing cyclic tests on Monocryl® monofilament sutures and showing the ability of the model in predicting with high accuracy the history dependence, the damage and permanent deformations in the obtained response.

Medium-term outcome of laparoscopic sacrocolpopexy using polivinylidene fluoride as compared to a hybrid polyglecaprone and polypropylene mesh: A matched control study

AIM

To compare 2-year outcomes of laparoscopic sacrocolpopexy (LSCP) either with polyvinylidene fluoride (PVDF) or hybrid polypropylene containing a resorbable polyglecaprone (PP+ PG) mesh.

MATERIALS AND METHODS

Retrospective audit on 105 consecutive patients undergoing LSCP a with PVDF-mesh (DynaMesh, FEG Textiltechniken), matched by prolapse stage and cervicopexy or vault suspension to 105 controls undergoing LSCP with a hybrid PP + PG-mesh (Ultrapro, Ethicon). Patients are part of an ongoing prospective study. The primary outcome measure was the Patient Global Impression of Change score (PGIC), the coprimary variable was failure rate at the vault (≤1 cm). Other outcomes were intraoperative and postoperative complications within 3 months categorized by the Clavien-Dindo classification, reinterventions, graft-related complications (GRCs) and functional outcomes. All assessments were performed by an independent assessor. Data are reported as median (interquartile range) number and percent as appropriate, the Mann-Whitney U, χ² , or Fisher exact were used for comparison.

RESULTS

Patient satisfaction in the PVDF group, as measured with the PGIC, was high (90.9% PGIC, ≥4) as well as was the anatomical success (97.3%) at a follow-up of 26 months. These outcomes were comparable to those of PP + PG-patients (84.8% PGIC, ≥4; 94.9% anatomical success). There were five patients (2.4%) with Dindo-III or higher complications and three patients had GRCs (1.5%), without differences between mesh type. Level-II posterior defects (Bp ≥ -1) were less likely in PVDF patients (34.1% vs 50% for PP + PG-patients; P = .003). Women in the PVDF group also were less bothered by prolapse (7.5% vs 26.4%; P = .001), yet they complained more of constipation (15.0% vs 9.0%; P = .01).

CONCLUSION

There were no differences in patient satisfaction and anatomical outcomes after LSCP either with PVDF or PP + PG mesh.

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.

Cross-Linked Cholecyst-Derived Extracellular Matrix for Abdominal Wall Repair

Abdominal wall repair frequently utilizes either nondegradable or biodegradable meshes, which are found to stimulate undesirable biological tissue responses or which possess suboptimal degradation rate. In this study, a biologic mesh prototype made from carbodiimide cross-linked cholecyst-derived extracellular matrix (EDCxCEM) was compared with small intestinal submucosa (Surgisis^®), cross-linked bovine pericardium (Peri-Guard^®), and polypropylene (Prolene^®) meshes in an in vivo rabbit model. The macroscopic appearance and stereological parameters of the meshes were evaluated. Tailoring the degradation of the EDCxCEM mesh prevents untimely degradation, while allowing cellular infiltration and mesh remodeling to take place in a slower but predictable manner. The results suggest that the cross-linked biodegradable cholecyst-derived biologic mesh results in no seroma formation, low adhesion, and moderate stretching of the mesh. In contrast to Surgisis, Peri-Guard, and Prolene meshes, the EDCxCEM mesh showed a statistically significant increase in the volume fraction (V_v) of collagen (from 34% to 52.1%) in the central fibrous tissue region at both day 28 and 56. The statistically high length density (L_v), of blood vessels for the EDCxCEM mesh at 28 days was reflected also by the higher cellular activity (high V_v of fibroblast and moderate V_v of nuclei) indicating remodeling of this region in the vicinity of a slowly degrading EDCxCEM mesh. The lack of mesh area stretching/shrinkage in the EDCxCEM mesh showed that the remodeled tissue was adequate to prevent hernia formation. The stereo-histological assays suggest that the EDCxCEM delayed degradation profile supports host wound healing processes including collagen formation, cellular infiltration, and angiogenesis. The use of cross-linked CEM for abdominal wall repair is promising.

* 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.

Outcomes of Minimally Invasive Inguinal Hernia Repair at the Time of Robotic Radical Prostatectomy

Abdominal straining associated with voiding dysfunction or constipation has traditionally been associated with the development of abdominal wall hernias. Thus, classic general surgery dictum recommends that any coexistent bladder outlet obstruction should be addressed by the urologist before patients undergo surgical repair of a hernia. While organ-confined prostate cancer is usually not associated with the development of lower urinary tract symptoms, a modest proportion of patients treated with radical prostatectomy may have coexisting benign prostatic hyperplasia with elevated symptom scores and hernias may be incidentally detected at the time of surgery. Furthermore, dissection of the space of Retzius during retropubic or minimally invasive prostatectomy may result exposure of abdominal wall defects which may have been present, but asymptomatic if plugged with preperitoneal fat. Herein we examine the literature regarding the incidence of postoperative inguinal hernias after prostatectomy, review potential risk factors which could aid in preoperative patient identification, and discuss the published experience regarding concurrent hernia repair at the time of open or minimally invasive radical prostatectomy.

Characteristics of the fibroplasia and collagen expression in the abdominal wall after implant of the polypropylene mesh and polypropylene/polyglecaprone mesh in rats

PURPOSE

To compare fibroplasia and the resistance of the abdominal wall when polypropylene meshes and polypropylene/poliglecaprone are used.

METHODS

Seventy-seven male Wistar rats were divided into three groups: Control Group (for resistance); Group E (polypropylene mesh); and Group U (polypropylene/poliglecaprone mesh). The animals in Groups E and U had a standard muscular and aponeurotic defect, with integral peritoneum, and correction with the mesh. Measurements were taken 4, 7, 14, 28 and 56 days after surgery. The resistance, and collagen density were studied.

RESULTS

Resistance on the 56th day was similar in both meshes. The gain in resistance described an ascending curve for the polypropylene mesh and was irregular in the case of the polypropylene/poliglecaprone. Fibroplasia showed a gain in type I and type III collagen in both groups (p<0.001). Collagen III stabilized in the 14th day and collagen I continued to ascend.

CONCLUSIONS

The gain in resistance of the polypropylene mesh is regular and ascending, whereas the polypropylene/poliglecaprone is not regular. The final resistance of both meshes is similar; the collagen density increases over time, and show the same inflammatory potential.

Formation of adhesion after intraperitoneal application of TiMesh: experimental study on a rodent model

BACKGROUND

After laparoscopic repair of an incisive hernia, intraperitoneal prosthetic mesh, as a foreign material, is a strong stimulus for the development of adhesion, which may be the cause of serious complications. This experimental study compared three different meshes and their ability to prevent the formation of adhesion and shrinkage.

METHODS

Ninety rats were divided randomly into three groups: in Group 1 Proceed mesh was implanted, in Group 2 Ultrapro mesh was implanted, and in Group 3 TiMesh was implanted. Mesh samples were fixed as an intraabdominal mesh in the upper part of the abdomen. Ten animals from each group were sacrificed on days 7, 28 and 60 post-surgery. After opening the abdomen, the formation of adhesion was assessed according to the Surgical Membrane Study Group (SMSG) score, the percentage of shrinkage of the mesh was established and inflammatory reaction scored.

RESULTS

The SMSG score for adhesion was statistically significantly higher on all the postoperative days in the Proceed and Ultrapro mesh groups than in the TiMesh group which caused milder inflammatory reaction on 60th day than others meshes. The size of the mesh after 7 days was statistically significantly smaller in the Proceed and Ultrapro groups than in the TiMesh group, but after 60 days it was statistically significantly larger than in the TiMesh group.

CONCLUSION

The least formation of adhesion was noted in the TiMesh group, in which the highest level of shrinkage was noticed after 28 and 60 days. TiMesh has advantages over the other meshes studied, but a larger size mesh may be recommended for intraperitoneal application.

Design Strategies and Applications of Biomaterials and Devices for Hernia Repair

Hernia repair is one of the most commonly performed surgical procedures worldwide, with a multi-billion dollar global market. Implant design remains a critical challenge for the successful repair and prevention of recurrent hernias, and despite significant progress, there is no ideal mesh for every surgery. This review summarizes the evolution of prostheses design toward successful hernia repair beginning with a description of the anatomy of the disease and the classifications of hernias. Next, the major milestones in implant design are discussed. Commonly encountered complications and strategies to minimize these adverse effects are described, followed by a thorough description of the implant characteristics necessary for successful repair. Finally, available implants are categorized and their advantages and limitations elucidated, including non-absorbable and absorbable (synthetic and biologically derived) prostheses, composite prostheses, and coated prostheses. This review not only summarizes the state of the art in hernia repair, but also suggests future research directions toward improved hernia repair utilizing novel materials and fabrication methods.

Experimental study of inflammatory response and collagen morphometry with different types of meshes

PURPOSE

To compare an inflammation score and collagen morphometry after incisional hernia repair with four different meshes at two time points.

METHODS

Four types of mesh were used to repair an abdominal wall incisional defect in Wistar rats: high-density polypropylene (HW/PP); low-density polypropylene (LW/PP); polypropylene mesh encapsulated with polydioxanone coated with oxidized cellulose (PP/CE); and expanded polytetrafluoroethylene (ePTFE). An inflammation score based on histological analysis and collagen morphometry was performed after 7 and 28 days after operation (POD).

RESULTS

Compared to LW/PP group at 7 POD, HW/PP group had lower (p = 0.014) and PP/CE group had higher inflammation scores (p = 0.001). At 28 POD, higher scores were seen in all the other groups compared to the LW/PP group (HW/PP, p = 0.046; PP/CE, p < 0.001; ePTFE, p = 0.027). Comparing groups individually at 7 and 28 PODs, all demonstrated lower inflammation score values at 28 POD (HW/PP, p < 0.001; LW/PP, p < 0.001; PP/CE, p = 0.002; ePTFE, p = 0.001). At 7 POD, higher amounts of collagen were detected in ePTFE compared to HW/PP (p < 0.001) and LW/PP (p = 0.004) and in PPCE group compared to HW/PP (p = 0.022). At 28 POD, no statistically significant difference was found. Comparing groups individually at 7 and 28 PODs, HW/PP and LW/PP showed larger amounts of collagen at the 28th POD, without any statistically significant differences for the PP/CE and ePTFE groups.

CONCLUSIONS

Inflammation scores decreased in all groups at 28 POD. Collagen deposition was higher for non-composite meshes at 28 POD.

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.

Preoperative International Prostate Symptom Score Predictive of Inguinal Hernia in Patients Undergoing Robotic Prostatectomy

PURPOSE

Studies have shown that encountering an inguinal hernia during robotic radical prostatectomy is not uncommon. We reviewed our experience with simultaneous robotic prostatectomy and mesh hernia repair to identify variables predictive of a hernia.

MATERIALS AND METHODS

Our cohort consisted of 693 consecutive men who underwent robotic radical prostatectomy as performed by 1 surgeon. Hernias were repaired with mesh composed of equal parts of absorbable polyglecaprone-25 and nonabsorbable polypropylene monofilament. Preoperative variables potentially predictive of an inguinal hernia were evaluated.

RESULTS

Inguinal hernias were encountered in 55 of 639 patients (8.6%), of which 22.3% were bilateral for a total of 68 hernia sides. Only 26 of 55 hernias (47.2%) were evident preoperatively. Men with a preoperative I-PSS (International Prostate Symptom Score) of 15 or greater had a 22.4% chance (30 of 134) of requiring a hernia repair compared with 5% in those without such a score (OR 5.54, 95% CI 3.13-9.81, p <0.0001). There were no differences between the hernia and nonhernia groups in prostate size, body mass index, age, blood loss, transfusions, operative time, length of stay or any Clavien grade II-V complication. In 47 patients there was 1 recurrence at a median followup of 27.9 months. There were no cases of mesh associated pain or erosion.

CONCLUSIONS

Independent of prostate size, men with preoperative lower urinary tract dysfunction were at 5 times the risk of a hernia at robotic radical prostatectomy (22.4% vs 5%). Given that half of the hernias were subclinical, patients with an I-PSS of 15 or greater should be counseled about the potential need for hernia repair at robotic radical prostatectomy.

Emerging Trends in Abdominal Wall Reinforcement: Bringing Bio-Functionality to Meshes

Abdominal wall hernia is a recurrent issue world-wide and requires the implantation of over 1 million meshes per year. Because permanent meshes such as polypropylene and polyester are not free of complications after implantation, many mesh modifications and new functionalities have been investigated over the last decade. Indeed, mesh optimization is the focus of intense development and the biomaterials utilized are now envisioned as being bioactive substrates that trigger various physiological processes in order to prevent complications and to promote tissue integration. In this context, it is of paramount interest to review the most relevant bio-functionalities being brought to new meshes and to open new avenues for the innovative development of the next generation of meshes with enhanced properties for functional abdominal wall hernia repair.

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

INTRODUCTION AND HYPOTHESIS

Our aim was to analyze the apparent contraction of meshes in vivo after abdominal wall reconstruction and evaluate histological and biomechanical properties after explantation.

METHODS

Nine New Zealand female rabbits underwent repair of two full-thickness 25 × 30-mm midline defects in the upper and lower parts of the abdomen. These were primarily overlaid by 35 × 40-mm implants of a polyvinylidene fluoride (PVDF) DynaMesh (n = 6) or polypropylene meshes Ultrapro (n = 6) and Marlex (n = 6). Edges of the meshes were secured with iron(II,III) oxide (Fe(3)O(4))-loaded PVDF sutures. Magnetic resonance images (MRIs) were taken at days 2, 30 and 90 after implantation. The perimeter of the mesh was traced using a 3D spline curve. The apparent surface area or the area within the PVDF sutures was compared with the initial size using the one-sample t test. A two-way repeat analysis of variance (ANOVA) was used to compare the apparent surface area over time and between groups.

RESULTS

PVDF meshes and sutures with Fe(3)O(4) could be well visualized on MRI. DynaMesh and Marlex each had a 17 % decrease in apparent surface area by day 2 (p < 0.001 and p = 0.001), respectively, which persisted after day 90. Whereas there was a decrease in apparent surface area in Ultrapro, it did not reach significance until day 90 (p = 0.01). Overall, the apparent surface area decreased 21 % in all meshes by day 90. No differences in histological or biomechanical properties were observed at day 90.

CONCLUSIONS

There was a reduction in the apparent surface area between implantation and day 2, indicating that most mesh deformation occurs prior to tissue in-growth.

Behaviour of a new composite mesh for the repair of full-thickness abdominal wall defects in a rabbit model

Introduction

Composite biomaterials designed for the repair of abdominal wall defects are composed of a mesh component and a laminar barrier in contact with the visceral peritoneum. This study assesses the behaviour of a new composite mesh by comparing it with two latest-generation composites currently used in clinical practice.

Methods

Defects (7x5cm) created in the anterior abdominal wall of New Zealand White rabbits were repaired using a polypropylene mesh and the composites: Physiomesh^TM; Ventralight^TM and a new composite mesh with a three-dimensional macroporous polyester structure and an oxidized collagen/chitosan barrier. Animals were sacrificed on days 14 and 90 postimplant. Specimens were processed to determine host tissue incorporation, gene/protein expression of neo-collagens (RT-PCR/immunofluorescence), macrophage response (RAM-11-immunolabelling) and biomechanical resistance. On postoperative days 7/14, each animal was examined laparoscopically to quantify adhesions between the visceral peritoneum and implant.

Results

The new composite mesh showed the lowest incidence of seroma in the short term. At each time point, the mesh surface covered with adhesions was greater in controls than composites. By day 14, the implants were fully infiltrated by a loose connective tissue that became denser over time. At 90 days, the peritoneal mesh surface was lined with a stable mesothelium. The new composite mesh induced more rapid tissue maturation than Physiomesh^TM, giving rise to a neoformed tissue containing more type I collagen. In Ventralight^TM the macrophage reaction was intense and significantly greater than the other composites at both follow-up times. Tensile strengths were similar for each biomaterial.

Conclusions

All composites showed optimal peritoneal behaviour, inducing good peritoneal regeneration and scarce postoperative adhesion formation. A greater foreign body reaction was observed for Ventralight^TM. All composites induced good collagen deposition accompanied by optimal tensile strength. The three-dimensional macroporous structure of the new composite mesh may promote rapid tissue regeneration within the mesh.

Sutureless fixation with fibrin glue of lightweight mesh in open inguinal hernia repair: effect on postoperative pain: a double-blind, randomized trial versus standard heavyweight mesh

BACKGROUND

Open inguinal hernia repair is associated with a low incidence of complications that can be influenced by the type of mesh and its method of fixation. Our aim was to investigate the frequency and severity of postoperative pain and other complications when lightweight, large-pore meshes, compared with heavyweight, small-pore meshes, are fixed with human fibrin glue (HFG) during open inguinal hernia repair.

METHODS

A cohort of 80 patients undergoing open inguinal repair were enrolled. Forty patients received a lightweight and large porous mesh and 40 a standard heavyweight mesh with small pores. In all patients, HFG was used for mesh fixation.

RESULTS

Patients who received lightweight, large-pore mesh reported less pain than those in the control group both postoperatively (2.8 ± 1.1 vs. 4.9 ± 1.1; P = .0003) and at 1-month follow-up (1.7 ± 1.0 vs. 3.1 ± 1.0; P = .0038), and took fewer analgesics. There was no difference in days off work/activity. No differences were observed concerning postoperative complications. After 6 months there was no difference in groin pain between groups.

CONCLUSION

Patients who underwent open inguinal hernia repair with lightweight, large-pore mesh fixed with HFG experienced less pain throughout the first month after operation compared with those receiving standard mesh.

Comparative study of the healing process when using Vicryl®, Vicryl Rapid®, Vicryl Plus®, and Monocryl® sutures in the rat dermal tissue

INTRODUCTION

Various types of sutures are available in the market with different constitutions. However, there is a lack of research to assess and quantify the behavior of these materials.

RESOURCES AND MATERIALS

This study comes benchmark wires polyglactin 910 (Vicryl®), irradiated polyglactin 910 (Vicryl Rapid®), polyglactin 910 treated with triclosan (Vicryl Plus®), and poliglecaprone 25 (Monocryl®). For this, we used 40 rats that were divided into two groups, underwent two skin incisions longitudinal 2-cm long. In Group A, simple interrupted sutures using irradiated polyglactin 910 on the right and left side of polyglactin 910, and in group B, polyglactin 910 with triclosan on the right and the left poliglecaprone 25 were made. At 2, 7, 14, and 28 days after surgery, the ten animals were killed per period, and the samples were processed for histomorphologic and histometric analysis.

CONCLUSIONS

The results demonstrated that the wire poliglecaprone 25 showed better biological response, with less inflammatory infiltrates and rapid organization of connective tissue.

Beneficial effects of fibrin glue (Quixil) versus Lichtenstein conventional technique in inguinal hernia repair: a randomized clinical trial

INTRODUCTION

In inguinal hernia repair, many complications are due to mesh fixation technique. Therefore, new types of atraumatic methods of fixation have been proposed. In this article, we present the results of a prospective multicentric parallel randomized controlled trial aiming to compare two mesh fixation techniques: fibrin sealant (QUIXIL(®), Omrix Biopharmaceuticals S.A., Belgium) and Lichtenstein technique.

METHOD

Adult patients with primary uncomplicated inguinal hernia were randomized in two groups: fibrin sealant group (FSG) and Lichtenstein group (LTG). The two groups underwent a follow-up of 15 months. Operative time is the primary outcome. Intraoperative and postoperative outcomes were analyzed. Moreover, a differential cost analysis was performed. Patients and evaluators (with exception of the surgeon who treated the patient) were blinded.

RESULTS

A total of 102 patients, 50 in FSG and 52 in LTG, were enrolled from January 2009 to June 2010, and two patients were lost to follow-up at the twelfth month. No significant differences in baseline and clinical characteristics were observed in the two groups. Operative time was longer in LTG (median/ interquartile range: 35 min/30-42.5 min vs. 31 min/28-35 min; effect size: 0.65/95% CI 0.50-0.91; p < 0.05). No differences in intraoperative complications were observed. No significant differences were observed in early complication rate (RR = 0.62; p > 0.05). Numbness rate was lower in the FSG at 1 week (RR = 0.43; p < 0.01) and at 1 month (RR = 0.17; p < 0.05). No significant differences were observed after 6 months. Postoperative pain was lower in the FSG at 1 week (0/0-1 vs. 1/0-2; p < 0.05) and at 1 month (0/0-0 vs. 0/0-1; p < 0.05). Pain disappeared in all patients after 6 months. Analgesic assumption rate was lower in the FSG (RR = 0.42; p < 0.05). Twenty per cent of FSG and 9.62% of LTG patients were discharged within 12 h; 78% of FSG and 90.38% of LTG patients were discharged within 24 h. The only one recurrence we observed was in FSG group. About costs, although fibrin sealant needed for one mesh fixation is about 10 times more costly than the needed sutures, the total costs of the two procedures did not change significantly. This was mainly due to reduction in operative time.

CONCLUSIONS

The use of fibrin sealant determined a significant reduction in short-term numbness rate and postoperative pain. There was no relevant difference in total costs per patient between the two procedures.

Inflammatory reaction and neotissue maturation in the early host tissue incorporation of polypropylene prostheses

PURPOSE

The use prosthetic materials for the surgical repair of abdominal wall defects has become almost standard practice. This study was designed to assess the expression of different growth factors (VEGF/TGF-β1) and macrophages during the early host tissue incorporation of several polypropylene lightweight (PP-LW)-including one partially absorbable-and heavyweight (PP-HW) prosthetic meshes.

METHODS

Ventral defects were created in the anterior abdominal wall of New Zealand rabbits and repaired by fixing PP-LW meshes of different pore size and a low porosity PP-HW mesh to the edges of the defect. Following killing 14 days after implant, specimens were taken to examine TGF-β1/VEGF gene and protein expression by qRT-PCR and immunohistochemistry. The macrophage response was also assessed.

RESULTS

All the materials showed good host tissue incorporation, with a more severe inflammatory reaction and greater numbers of macrophages recorded in the partially absorbable LW implants. Relative amounts of VEGF mRNA were significantly lower for the LW partially absorbable implants compared with the remaining LW meshes. Protein expression of VEGF showed undetectable or minimum staining in the different groups. TGF-β1 mRNA levels were also lower in the partially absorbable group compared with one of PP-LW type of mesh. Gene expression patterns were consistent with the TGF-β1 protein levels detected.

CONCLUSIONS

The results suggest that VEGF and TGF-β1 expression were independent of mesh pore size. The expression of both growth factors and the macrophage response were correlated with the presence of biodegradable material in the mesh. The presence of absorbable material in the LW mesh gave rise to a more intense inflammatory reaction and the reduced synthesis of growth factors known to contribute to neotissue maturation.

The long-term behavior of lightweight and heavyweight meshes used to repair abdominal wall defects is determined by the host tissue repair process provoked by the mesh

BACKGROUND

Although heavyweight (HW) or lightweight (LW) polypropylene (PP) meshes are widely used for hernia repair, other alternatives have recently appeared. They have the same large-pore structure yet are composed of polytetrafluoroethylene (PTFE). This study compares the long-term (3 and 6 months) behavior of meshes of different pore size (HW compared with LW) and composition (PP compared with PTFE).

METHODS

Partial defects were created in the lateral wall of the abdomen in New Zealand White rabbits and then repaired by the use of a HW or LW PP mesh or a new monofilament, large-pore PTFE mesh (Infinit). At 90 and 180 days after implantation, tissue incorporation, gene and protein expression of neocollagens (reverse transcription-polymerase chain reaction/immunofluorescence), macrophage response (immunohistochemistry), and biomechanical strength were determined. Shrinkage was measured at 90 days.

RESULTS

All three meshes induced good host tissue ingrowth, yet the macrophage response was significantly greater in the PTFE implants (P < .05). Collagen 1/3 mRNA levels failed to vary at 90 days yet in the longer term, the LW meshes showed the reduced genetic expression of both collagens (P < .05) accompanied by increased neocollagen deposition, indicating more efficient mRNA translation. After 90-180 days of implant, tensile strengths and elastic modulus values were similar for all 3 implants (P > .05).

CONCLUSION

Host collagen deposition is mesh pore size dependent whereas the macrophage response induced is composition dependent with a greater response shown by PTFE. In the long term, macroporous meshes show comparable biomechanical behavior regardless of their pore size or composition.

Polypropylene mesh and the host response

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

Comparative analysis of histopathologic effects of synthetic meshes based on material, weight, and pore size in mice

BACKGROUND

While synthetic prosthetics have essentially become mandatory for hernia repair, mesh-induced chronic inflammation and scarring can lead to chronic pain and limited mobility. Mesh propensity to induce such adverse effects is likely related to the prosthetic's material, weight, and/or pore size. We aimed to compare histopathologic responses to various synthetic meshes after short- and long-term implantations in mice.

MATERIAL AND METHODS

Samples of macroporous polyester (Parietex [PX]), heavyweight microporous polypropylene (Trelex[TX]), midweight microporous polypropylene (ProLite[PL]), lightweight macroporous polypropylene (Ultrapro[UP]), and expanded polytetrafluoroethylene (DualMesh[DM]) were implanted subcutaneously in mice. Four and 12 wk post-implantation, meshes were assessed for inflammation, foreign body reaction (FBR), and fibrosis.

RESULTS

All meshes induced varying levels of inflammatory responses. PX induced the greatest inflammatory response and marked FBR. DM induced moderate FBR and a strong fibrotic response with mesh encapsulation at 12 wk. UP and PL had the lowest FBR, however, UP induced a significant chronic inflammatory response. Although inflammation decreased slightly for TX, marked FBR was present throughout the study. Of the three polypropylene meshes, fibrosis was greatest for TX and slightly reduced for PL and UP. For UP and PL, there was limited fibrosis within each mesh pore.

CONCLUSION

Polyester mesh induced the greatest FBR and lasting chronic inflammatory response. Likewise, marked fibrosis and encapsulation was seen surrounding ePTFE. Heavier polypropylene meshes displayed greater early and persistent fibrosis; the reduced-weight polypropylene meshes were associated with the least amount of fibrosis. Mesh pore size was inversely proportional to bridging fibrosis. Moreover, reduced-weight polypropylene meshes demonstrated the smallest FBR throughout the study. Overall, we demonstrated that macroporous, reduced-weight polypropylene mesh exhibited the highest degree of biocompatibility at sites of mesh implantation.

Lysostaphin-Coated Mesh Prevents Staphylococcal Infection and Significantly Improves Survival in a Contaminated Surgical Field

Mesh and wound infections during hernia repair are predominantly caused by Staphylococcus aureus. Human acellular dermis (HAD) is known to lose its integrity in the face of large bacterial loads. The goal of this study was to determine if lysostaphin (LS), a naturally occurring anti-Staphylococcal protein, can protect HAD mesh from S. aureus infection. HAD samples, 3 cm X 3 cm, were implanted in the onlay fashion on the anterior abdominal wall of rats (n = 75). Subjects were grouped based on presence of antimicrobial bound to HAD (none or LS) and presence of S. aureus inoculum (sterile, 106, 108 CFU). At 60 days, meshes were explanted, and bacterial growth, histology, and mesh tensile strength were examined. None of the controls receiving bacterial inoculation without LS survived to 60 days. All LS-HAD sterile and LS-106 animals survived to explantation. The LS-HAD 108 group had a mortality rate of 50 per cent. All surviving LS-treated animals (n = 25) had negative wound and mesh cultures. Blinded gross and histologic evaluation and measured tensile strengths between all LS groups were comparable. Animals implanted with LS-HAD had a dramatically improved rate of survival. All animals surviving to 60 days had completely cleared S. aureus from their wounds with maintenance of mesh integrity and tensile strength. These findings strongly suggest the clinical use of LS-treated mesh in contaminated fields may translate into a more durable hernia repair.

Persistence of polypropylene mesh anisotropy after implantation: an experimental study

OBJECTIVE

To determine whether anisotropy persisted after incorporation into the host, using a standardised rabbit model for abdominal wall reconstruction.

DESIGN

Investigator-initiated prospective-controlled experimental study.

SETTING

Centre for Surgical Technologies, Medical Faculty KU-Leuven.

SAMPLE

Fifteen New Zealand White rabbits.

METHODS

In each rabbit, four full thickness primarily repaired abdominal wall defects were covered by a 4 × 5-cm Prolift+M implant (Johnson & Johnson, Norderstedt, Germany), either with the stiffest (n = 6 rabbits) or most elastic (n = 6) direction parallel to the body axis. Prolift+M contains 32 g/m² polypropylene, reinforced with polyglecaprone fibres. Harvesting was performed after 30, 60 and 120 days (n = 2 each time-point). The abdominal wall of three unoperated rabbits was used as negative control.

MAIN OUTCOME MEASURES

Contraction, compliance and maximal strain and stress determined by uniaxial tensiometry.

RESULTS

Anisotropy properties persist at lower, more physiological displacements, but not at higher displacements. The stiffness of a mesh-augmented repair in the lower strain range remains above that of native tissue. Eventual mesh contraction was limited to 4.3%.

CONCLUSIONS

Anisotropic properties of Prolift+M persist in vivo and shrinkage is minimal. Compliance of mesh-augmented repair remains less than that of native tissue. The functional consequences of this remain to be studied.

Influence of the Elasticity Module of Synthetic and Natural Polymeric Tissue Substitutes on the Mobility of the Diaphragm and Healing Process in a Rabbit Model

Mesh implants are frequently used in congenital diaphragmatic hernia. This experimental study aimed to examine the influence of different materials on the diaphragmatic movement over time as well as their mechanical qualities after 4 months. Ultrapro®, Surgisis®, and Proceed ® were implanted onto a diaphragmatic defect in growing rabbits. Diaphragmatic mobility was determined at three time points. At 4 months, defect shrinkage and mechanical properties were measured. The break strength decreased for Ultrapro® and Surgisis®, but did not change relevantly for Proceed®. Ultrapro® (32.46 N/cm) and Proceed® (31.75 N/cm) showed a four-fold higher resistance to tearing than Surgisis® (8.31 N/cm). The elasticity of Ultrapro® showed no significant difference compared to Surgisis® ( p = 0.75). Proceed®, on the other hand, was more than twice as elastic as Ultrapro® or Surgisis ® ( p = 0.015). Ultrapro® had a higher spring rate (6.48 N/mm) compared to Surgisis® (3.82 N/mm) or Proceed ® (5.23 N/mm). Observing the standardized movement rates of the diaphragm for each mesh group over time the only statistical differences were seen for the Proceed® group. On account of its material qualities Ultrapro® was found to be the most suitable mesh material for demanding locations in our model.

Impact of Heavy Polypropylene Mesh and Composite Light Polypropylene and Polyglactin 910 on the Inflammatory Response

The aim of the study was to analyze the acute inflammatory response after implantation of a heavyweight mesh of polypropylene (PP) compared with a composite mesh of light PP and polyglactin 910 (PG) in patients undergoing inguinal hernioplasty. A total of 30 male patients with inguinal hernia were included in the study and divided into 2 groups (PP and PP-PG) according to the mesh used. Changes of leukocytes, cytokines, growth factors, and acute phase proteins were evaluated in the sera. Leukocytes and acute phase proteins were significantly increased postoperatively in both groups, and the values were slightly higher in the PP group. Cytokine levels were significantly increased postoperatively in both groups; a slight increase was observed in the PP-PG group, especially for the proinflammatory cytokine. Growth factors decreased significantly in both groups immediately after surgery. The authors found that the use of the mesh is a stimulator of inflammatory response, and the 2 types of mesh induce a similar inflammatory response.

Open tension-free Lichtenstein repair of inguinal hernia: use of fibrin glue versus sutures for mesh fixation

PURPOSE

To investigate pain and other complications following inguinal hernioplasty performed by the Lichtenstein technique with mesh fixation by fibrin glue or sutures.

METHODS

Five hundred and twenty patients were enrolled in this 12-month observational multicenter study and received either sutures or fibrin glue (Tissucol(®)/Tisseel(®)) based on the preference of the surgeon. Pain, numbness, discomfort, recurrence, and other complications were assessed postoperatively and at 1, 3, 6, and 12 months. Pain intensity was assessed by a visual analog scale (VAS; 0 [no pain] to 10 [worst pain]).

RESULTS

One hundred and seventy-one patients received sutures and 349 received fibrin glue. During the early postoperative phase, 87.4% of patients in the fibrin glue group and 76.6% of patients in the sutures group were complication-free (P = 0.001). Patients who received fibrin glue were also less likely to experience hematoma/ecchymosis than those in the suture group (both P = 0.001). The mean pain score was significantly lower in the fibrin group than the sutures group (2.5 vs. 3.2, P < 0.001). At 1 month, significantly fewer patients in the fibrin glue group reported pain, numbness, and discomfort compared with patients in the sutures group (all P < 0.05). Fibrin glue patients also experienced less intense pain (0.6 vs. 1.2; P = 0.001). By 3 months, the between-group differences had disappeared, except for numbness, which was more prevalent in the sutures group. By 12 months, very few patients reported complications.

CONCLUSIONS

Tissucol fibrin glue for mesh fixation in the Lichtenstein repair of inguinal hernia shows advantages over sutures, including lower incidence of complications such as pain, numbness, and discomfort, and should be considered as a first-line option for mesh fixation in hernioplasty.

A randomised, multi-centre, prospective, double blind pilot-study to evaluate safety and efficacy of the non-absorbable Optilene Mesh Elastic versus the partly absorbable Ultrapro Mesh for incisional hernia repair

Background

Randomised controlled trials with a long term follow-up (3 to 10 years) have demonstrated that mesh repair is superior to suture closure of incisional hernia with lower recurrence rates (5 to 20% versus 20 to 63%). Yet, the ideal size and material of the mesh are not defined. So far, there are few prospective studies that evaluate the influence of the mesh texture on patient's satisfaction, recurrence and complication rate. The aim of this study is to evaluate, if a non-absorbable mesh (Optilene^® Mesh Elastic) will result in better health outcomes compared to a partly absorbable mesh (Ultrapro^® Mesh).

Methods/Design

In this prospective, randomised, double blind study, eighty patients with incisional hernia after a midline laparotomy will be included. Primary objective of this study is to investigate differences in the physical functioning score from the SF-36 questionnaire 21 days after mesh insertion. Secondary objectives include the evaluation of the patients' daily activity, pain, wound complication and other surgical complications (hematomas, seromas), and safety within six months after intervention.

Discussion

This study investigates mainly from the patient perspective differences between meshes for treatment of incisional hernias. Whether partly absorbable meshes improve quality of life better than non-absorbable meshes is unclear and therefore, this trial will generate further evidence for a better treatment of patients.

Trial registration

NCT00646334

Is biocompatibility affected by constant shear stress?--comparison of three commercially available meshes in a rabbit model

Mesh implants as standard treatment for tissue defects can be adapted to patient's needs by specific bioactive coatings. The biophysical interaction with the surrounding tissue must be understood to describe the influence of coatings qualitatively and quantitatively. This study investigates the use of meshes to repair diaphragmatic defects. The physical stress in this tissue is high in comparison to other applications. Therefore, knowledge gained from this experimental model can be applied to other locations. Meshes were implanted on surgically created diaphragmatic defects in growing rabbits. A standardized load model was used to investigate 33 rabbits. The commercial products Ultrapro®, Surgisis®, and Proceed® were implanted. The adhesive properties of the meshes as well as the defect size were determined macroscopically at explantation after 4 months. Sections of the explanted meshes and diaphragms were examined histologically and immunohistochemically. The median defect size for all mesh groups decreased from the initial size of 10 mm down to 4.5 mm at explantation. No statistically significant differences were seen between the three mesh groups. Surgisis® was found to be completely disintegrated after 4 months. Ultrapro® and Proceed® showed no macroscopic differences compared to their original appearance. Both sealed the original diaphragmatic defect as tightly as at time of implantation. Histological and immunohistochemical analyses showed significant differences between the three mesh groups. Proceed® caused stronger inflammatory reaction in the surrounding tissue and inferior connective tissue formation. Regarding the composition of the newly generated tissue within the defect area, Ultrapro® and Surgisis® were found superior. This can sufficiently be explained by the different gradient of inflammatory reaction in the surrounding tissue. Because Surgisis® offers no sufficiently lasting support for the diaphragmatic defect, our future main focus for mesh modification is laid on Ultrapro®.