Comparison of a lightweight polypropylene mesh (Optilene® LP) and a large-pore knitted PTFE mesh (GORE® INFINIT® mesh)—Biocompatibility in a standardized endoscopic extraperitoneal hernia model

Biomaterial and biocompatibility evaluation of tunicate nanocellulose for tissue engineering

Extracellular matrix fibril components, such as collagen, are crucial for the structural properties of several tissues and organs. Tunicate-derived cellulose nanofibrils (TNC) combined with living cells could become the next gold standard for cartilage and soft-tissue repair, as TNC fibrils present similar dimensions to collagen, feasible industrial production, and chemically straightforward and cost-efficient extraction procedures. In this study, we characterized the physical properties of TNC derived from aquaculture production in Norwegian fjords and evaluated its biocompatibility regarding induction of an inflammatory response and foreign-body reactions in a Wistar rat model. Additionally, histologic and immunohistochemical analyses were performed for comparison with expanded polytetrafluoroethylene (ePTFE) as a control. The average length of the TNC as determined by atomic force microscopy was tunable from 3 μm to 2.4 μm via selection of a various number of passages through a microfluidizer, and rheologic analysis showed that the TNC hydrogels were highly shear-thinning and with a viscosity dependent on fibril length and concentration. As a bioink, TNC exhibited excellent rheological and printability properties, with constructs capable of being printed with high resolution and fidelity. We found that post-print cross-linking with alginate stabilized the construct shape and texture, which increased its ease of handling during surgery. Moreover, after 30 days in vivo, the constructs showed a highly-preserved shape and fidelity of the grid holes, with these characteristics preserved after 90 days and with no signs of necrosis, infection, acute inflammation, invasion of neutrophil granulocytes, or extensive fibrosis. Furthermore, we observed a moderate foreign-body reaction involving macrophages, lymphocytes, and giant cells in both the TNC constructs and PTFE controls, although TNC was considered a non-irritant biomaterial according to ISO 10993-6 as compared with ePTFE. These findings represent a milestone for future clinical application of TNC scaffolds for tissue repair. One sentence summary: In this study, the mechanical properties of tunicate nanocellulose are superior to nanocellulose extracted from other sources, and the biocompatibility is comparable to that of ePTFE.

Difficulties in Diagnosing Extraperitoneal Ureteroinguinal Hernias: A Review of the Literature and Clinical Experience of a Rare Encounter in Acute Surgical Care Settings

Although inguinal hernia repair is one of the most common surgical procedures, finding a retroperitoneal structure, such as the ureter, is a rather rare occurrence. Ureteroinguinal hernias may arise in the presence or absence of obstructive uropathy, the latter raising difficulties in diagnosis for the general surgeon performing a regular inguinal hernia surgery. This study aims to collect the relevant literature describing the diagnosis and management of ureteroinguinal hernias and update it with a case encountered in our clinic. The following study was reported following the SCARE guidelines. The relevant literature describes less than 150 cases of ureteroinguinal hernias overall, considering the 1.7% prevalence of inguinal hernias in the general population. With only 20% of these hernias being described as extraperitoneal, such an encounter becomes an extremely rare finding. Our clinical experience brings a case of a 75-year-old male with frequent urinary tract infections and a large irreducible inguinoscrotal hernia of about 20/12 cm located at the right scrotum. The patient underwent an open inguinal hernia repair technique under general anesthesia, incidentally finding an extraperitoneal ureteral herniation. Segmental ureterectomy was performed with uneventful recovery. Intraoperatively, finding an incidental ureteroinguinal hernia raises concerns about probable urinary tract complications during regular hernia repair surgery and whether the diagnosis is likely to happen prior to surgical intervention. Although imaging is rarely indicated in inguinal hernias, the case reports show that a pelvic CT scan with urography in symptomatic patients with urinary symptoms will provide accurate confirmation of the diagnosis. The relevant literature is limited due to the rarity of respective cases, thus making standardized management of such cases unlikely.

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.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Polytetrafluoroethylene versus polypropylene mesh during laparoscopic totally extraperitoneal (TEP) repair of inguinal hernia: short- and long-term results of a double-blind clinical randomized controlled trial

PURPOSE

Aim of the study is to compare macroporous (> 1 mm²) polytetrafluoroethylene mesh (LP-PTFE) versus microporous (< 1 mm²) polypropylene mesh (SP-PPL) in terms of postoperative acute and chronic discomfort and pain, difficulty in mesh handling and long-term recurrence rate.

METHODS

Fifty-two patients with bilateral hernia were enrolled in this double-blind randomized controlled trial (NCT02023203). Each hernia, in the same patient, was randomized to implant LP-PTFE or SP-PPL mesh during totally extraperitoneal laparoscopic hernia repair. Patients were followed at 7 days, 1, 3, 6, 12 and 60 months after surgery. Visual analog scale (VAS) score was employed to evaluate the outcomes. Student's t test was used in case of normally distributed continuous variables, while the nonparametric Mann-Whitney U test was used in case of not normally distributed variables. Chi square test was used for analysis of categorical variables.

RESULTS

Median VAS discomfort score with SP-PPL was significantly higher than LP-PTFE at 1 and 3 months after surgery (p = 0.003 in both cases). LP-PTFE showed significantly lower median score than SP-PPL at 7 days after surgery (p = 0.025) regarding pain at movement. Testicular pain was lower in case of LP-PTFE than SP-PPL at 7 days, 1 and 3 months after surgery (p = 0.005, p = 0.004 and p = 0.004, respectively). LP-PTFE was significantly more difficult to handle (p = 0.001). At 60 months, one recurrence was observed in the LP-PTFE group (p = 1.0000).

CONCLUSIONS

LP-PTFE has less postoperative discomfort and pain up to 3 months after surgery, without differences after that period, although it shows more difficulty in handling and recurrences occur even if not statistically significant.

In vitro analysis of biopolymer coating with glycidoxypropyltrimethoxysilane on hernia meshes

Certain coatings may improve the biocompatibility of hernia meshes. The coating with self-assembled monolayers, such as glycidoxypropyltrimethoxysilane (GOPS) can also improve the materials characteristics of implants. This approach was not yet explored in hernia meshes. It was the aim of this work to clarify if and how hernia meshes with their three-dimensional structure can be coated with GOPS and with which technique this coating can be best characterized. Commercially available meshes made from polypropylene (PP), polyester (PE), and expanded polytetrafluorethylene (ePTFE) have been coated with GOPS. The coatings were analyzed via X-ray photoelectron spectroscopy (XPS), confocal laser scanning microscopy (CLSM), and cell proliferation test (mouse fibroblasts). Cell viability and cytotoxicity were tested by MTT test. With the GOPS surface modification, the adherence of mouse fibroblasts on polyester meshes and the proliferation on ePTFE meshes were increased compared to noncoated meshes. Both XPS and CLSM are limited in their applicability and validity due to the three-dimensional mesh structure while CLSM was overall more suitable. In the MTT test, no negative effects of the GOPS coating on the cells were detected after 24 h. The present results show that GOPS coating of hernia meshes is feasible and effective. GOPS coating can be achieved in a fast and cost-efficient way. Further investigations are necessary with respect to coating quality and adverse effects before such a coating may be used in the clinical routine. In conclusion, GOPS is a promising material that warrants further research as coating of medical implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1083-1090, 2017.

Evaluation of diaphragmatic mobility following intra-abdominal sub-diaphragmatic fixation of a double-layered mesh in rats

PURPOSE

To evaluate the tissue integration of a double-sided mesh after fixation in diaphragm and to study the diaphragmatic mobility by ultrasound.

METHODS

Twenty male Wistar rats were used. The animals were assigned into two equal groups according to the day of euthanasia. The animals were anesthetized and a 1.5 x 1.5 cm of double-layer mesh was inserted between the diaphragm and the liver. For the evaluation of the diaphragm mobility a sonographic method was used. Measurements on specific breathing parameters were taking place. Pathological evaluation took place after the animal's euthanasia.

RESULTS

Extra-hepatic granuloma was not differentiated overtime, (χ2=0.04, p>0.05). Neither fibrosis was significantly differentiated, (χ2=0.04, p>0.05). Intra-hepatic granuloma was significantly differentiated overtime, (χ2=10.21, p<0.05). Concerning Te parameter, means were significantly differentiated over time, F (3, 30) = 5.12, (p<0.01). Ttot parameter, it was differentiated over time, F (3, 8)=4.79, (p<0.05). IR parameter was also longitudinally differentiated, F (3, 30)=3.73, (p<0.05).

CONCLUSION

The measurements suggest a transient malfunction of diaphragmatic mobility despite the fact that inflammatory reaction, fibrosis and extra-hepatic granuloma were not significantly differentiated with the passage of time.

Efficacy of Prophylactic Mesh in End-Colostomy Construction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Parastomal hernia is a very common complication after colostomy, especially end-colostomy. It is unclear whether prophylactic placement of mesh at the time of stoma formation could prevent parastomal hernia formation after surgery for rectal cancer. A systematic review and meta-analysis were conducted to evaluate the efficacy of prophylactic mesh in end-colostomy construction.

METHODS

PubMed, Embase, and the Cochrane Library were searched, covering records entered from their inception to September 2015. Randomized controlled trials (RCTs) comparing stoma with mesh to stoma without mesh after surgery for rectal cancer were included. The primary outcome was the incidence of parastomal hernia. Pooled risk ratios (RR) with 95 % confidence intervals (CI) were obtained using random effects models.

RESULTS

Six RCTs containing 309 patients were included. Parastomal hernia occurred in 24.4 % (38 of 156) of patients with mesh and 50.3 % (77 of 153) of patients without mesh. Meta-analysis showed a lower incidence of parastomal hernia (RR, 0.42; 95 % CI 0.22-0.82) and reoperation related to parastomal hernia (RR, 0.23; 95 % CI 0.06-0.89) in patients with mesh. Stoma-related morbidity was similar between mesh group and non-mesh group (RR, 0.65; 95 % CI 0.33-1.30).

CONCLUSIONS

Prophylactic placement of a mesh at the time of a stoma formation seems to be associated with a significant reduction in the incidence of parastomal hernia and reoperation related to parastomal hernia after surgery for rectal cancer, but not the rate of stoma-related morbidity. However, the results should be interpreted with caution because of the heterogeneity among the studies.

Laparoscopic Inguinal Hernia Repair With a Novel Hernia Mesh Incorporating a Nitinol Alloy Frame Compared With a Standard Lightweight Polypropylene Mesh

BACKGROUND

Numerous mesh materials are available for laparoscopic inguinal hernia repair. The role of fixation of mesh in laparoscopic inguinal hernia repair remains controversial. Mesh materials have been engineered to anatomically conform to the pelvis to potentially reduce or eliminate the need for fixation. This study evaluates the outcomes of laparoscopic inguinal hernia utilizing a device consisting of a lightweight polypropylene mesh with a nitinol frame (Rebound HRD) compared with repair with lightweight polypropylene mesh with permanent tack fixation.

METHODS

A prospective randomized trial evaluating the outcomes of laparoscopic inguinal hernia repair with a lightweight polypropylene mesh with a nitinol frame (N-LWM) compared with standard lightweight polypropylene mesh (LWM) was conducted. Randomization was performed at an N-LWM to LWM ratio of 2:1. Repairs were standardized to a laparoscopic extraperitoneal approach without fixation for N-LWM and titanium tack fixation for LWM repairs. Follow-up assessments were performed at 7 days, 6 months, and 1 year. Outcome measures include visual analog pain scale (VAS), Short Form 36 (SF-36), Carolinas Comfort Scale (CCS), operative details, complications, and recurrences.

RESULTS

There were 47 patients that underwent laparoscopic inguinal hernia repair and adhered to study protocol (31 N-LWM, 16 LWM). The groups did not differ significantly in age, body mass index, ethnicity, or employment. The N-LWM group had bilateral mesh placed in 51.6% and LWM 43.8% (P = .76). Operative duration was similar, 59.6 ± 23.1 minutes for LWM and 62.4 ± 26.7 minutes for N-LWM (P = .705) as was mesh handling time was 5.4 ± 3.1 minutes LWM versus 7.3 ± 3.9 minutes N-LWM (P = .053). VAS, CCS, and SF-36 survey results were similar between groups. There was one recurrence (0.03%) in the N-LWM group.

CONCLUSIONS

Nitinol-framed lightweight polypropylene mesh may be safely used during laparoscopic inguinal hernia repair with outcomes comparable to LWM at 1 year. N-LWM does not impact operating room time, mesh handling time, pain, recurrences, or complications.

Polypropylene, polyester or polytetrafluoroethylene-is there an ideal material for mesh augmentation at the esophageal hiatus? Results from an experimental study in a porcine model

PURPOSE

Knowledge about the influence of underlying biomaterial on behavior of surgical meshes at the esophageal hiatus is rare, but essential for safe and effective hiatal hernia surgery. This study aimed to characterize the influence of polymer material on mesh behavior at the hiatus.

METHODS

24 pigs in three groups of eight underwent implantation of either polypropylene (PP), polyester (PET) or polytetrafluoroethylene (PTFE) mesh placed circularly at the esophageal hiatus. After 8 weeks, necropsy and measurements were performed evaluating mesh deformation, adhesion formation, fixation of the esophagogastric junction and mesh position. Foreign body reaction was assessed by mononuclear cell count and immunostaining of Ki-67. Tissue integration was evaluated by immunostaining of type I and type III collagen fibers.

RESULTS

Mesh shrinkage was the highest for PTFE, lower for PP and the lowest for PET (34.9 vs. 19.8 vs. 12.1 %; p = 0.002). Mesh aperture for the esophagus showed an enlargement within all groups, which was highest for PTFE compared to PP and PET (100.8 vs. 47.0 vs. 35.9 %; p = 0.001). The adhesion score was highest for PP, lower for PTFE and the lowest for PET (11.0 vs. 9.5 vs. 5.0; p = 0.001) and correlated positively with the score of esophagogastric fixation (r s = 0.784, p < 0.001). No mesh migration, erosion or stenosis of the esophagus occurred. Evaluation of foreign body reaction and tissue integration showed no significant differences.

CONCLUSIONS

In this experimental setting, PP-meshes showed the most appropriate characteristics for augmentation at the hiatus. Due to solid fixation of the esophagogastric junction and low shrinkage tendency, PP-meshes may be effective in preventing hiatal hernia recurrence. The use of PTFE-mesh at the hiatus may be disadvantageous due to high shrinkage rates and correlating enlargement of the aperture for the esophagus.