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.     

Randomized clinical trial of laparoscopic hernia repair comparing titanium-coated lightweight mesh and medium-weight composite mesh

Background

The use of lightweight meshes in incisional hernia repair could have beneficial effects on quality of life. This study aimed to compare a new titanium-coated lightweight mesh with a standard composite mesh after laparoscopic incisional hernia repair.

Methods

A randomized controlled single-center clinical trial was designed using the basic principle of one unit, one surgeon, one technique (midline incisional hernia with a laparoscopic approach), and two meshes: a lightweight titanium-coated mesh (group 1) and a medium-weight collagen-polyester composite mesh (group 2) used in 102 patients. The primary end points were pain and recurrence. The secondary end points were morbidity and patient outcomes (analgesic consumption, return to everyday activities).

Results

The postoperative complication rates were similar for the two meshes. Pain was significantly less common in group 1 than in group 2 at 1 month (P = 0.029) but was similar for the two groups at 6 months and 1 year. There was a significant difference between the two groups in the average use of analgesics: 6.1 days in group 1 versus 1.6 days in group 2 (P < 0.001). The lightweight group returned to everyday activities after 6.9 days versus 9.7 days for the composite group (P < 0.001). The rate of recurrence did not differ between the two groups at the 2-year follow-up evaluation.

Conclusions

The light titanium-covered polypropylene mesh was associated with less postoperative pain in the short term, lower analgesic consumption, and a quicker return to everyday activities than the Parietex composite medium-weight mesh. The recurrence rates at 2 years showed no difference between the two groups.     

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.     

Mesh size in Lichtenstein repair: a systematic review and meta-analysis to determine the importance of mesh size

Purpose

Small mesh size has been recognized as one of the factors responsible for recurrence after Lichtenstein hernia repair due to insufficient coverage or mesh shrinkage. The Lichtenstein Hernia Institute recommends a 7 × 15 cm mesh that can be trimmed up to 2 cm from the lateral side. We performed a systematic review to determine surgeons’ mesh size preference for the Lichtenstein hernia repair and made a meta-analysis to determine the effect of mesh size, mesh type, and length of follow-up time on recurrence.

Methods

Two medical databases, PubMed and ISI Web of Science, were systematically searched using the key word “Lichtenstein repair.” All full text papers were selected. Publications mentioning mesh size were brought for further analysis. A mesh surface area of 90 cm² was accepted as the threshold for defining the mesh as small or large. Also, a subgroup analysis for recurrence pooled proportion according to the mesh size, mesh type, and follow-up period was done.

Results

In total, 514 papers were obtained. There were no prospective or retrospective clinical studies comparing mesh size and clinical outcome. A total of 141 papers were duplicated in both databases. As a result, 373 papers were obtained. The full text was available in over 95 % of papers. Only 41 (11.2 %) papers discussed mesh size. In 29 studies, a mesh larger than 90 cm² was used. The most frequently preferred commercial mesh size was 7.5 × 15 cm. No papers mentioned the size of the mesh after trimming. There was no information about the relationship between mesh size and patient BMI. The pooled proportion in recurrence for small meshes was 0.0019 (95 % confidence interval: 0.007–0.0036), favoring large meshes to decrease the chance of recurrence. Recurrence becomes more marked when follow-up period is longer than 1 year (p < 0.001). Heavy meshes also decreased recurrence (p = 0.015).

Conclusion

This systematic review demonstrates that the size of the mesh used in Lichtenstein hernia repair is rarely discussed in clinical studies. Papers that discuss mesh size appear to reflect a trend to comply with the latest recommendations to use larger mesh. Standard heavy meshes decrease the recurrence in hernia repair. Even though there is no evidence, it seems that large meshes decrease recurrence rates.     

Evaluation of a knitted polytetrafluoroethylene mesh placed intraperitoneally in a New Zealand white rabbit model

Background

The intraperitoneal application of surgical mesh remains a controversial issue because of possible complications, especially adhesion and fistula formation. This study aimed to assess the potential of a knitted polytetrafluoroethylene (PTFE) mesh for intraabdominal implantation.

Methods

Twenty-eight 5?×?5?cm samples of knitted macroporous PTFE mesh and light-weight polypropylene mesh (LW-PP) were implanted intraperitoneally in 14 New Zealand white rabbits in a randomized manner and fixed using eight polypropylene stitches. After 90?days, the adhesion formation, adhesion score, shrinkage, strength of fixation to the abdominal wall, and histologic biocompatibility were assessed.

Results

No intraoperative or anesthesia-related complications or mesh infection were recorded. The average area covered by adhesions was 4.7?±?7.2% for the PTFE and 36.4?±?36.1% for the LW-PP. The median adhesion score was 0 for the PTFE and 8 for the LW-PP. Shrinkage was 36.9?±?12.9% for the PTFE mesh and 12.6?±?8.72% for the LW-PP. The mesh-to-abdominal wall fixation strength was almost the same for both materials (PTFE 3.6?±?1.9 vs. LW-PP 3.6?±?2.9). The inflammatory cell count was almost the same for the two groups, with no statistically significant difference. The width of the inner granuloma was equal (PTFE 10.5?±?0.9 vs. LW-PP 11.1?±?0.9). The outer granuloma was reduced significantly in the PTFE group (PTFE 23.0?±?2.1 vs. LW-PP 33.6?±?7.9). One of the animals in the PTFE group died on postoperative day 12 because of ileus. The reason was an adhesion of the small intestine to the polypropylene fixation stitch, which caused small intestine strangulation.

Conclusions

The knitted PTFE mesh induces fewer intraperitoneal adhesions of lower density than the light-weight polypropylene mesh. The strength of the knitted PTFE mesh fixation to the abdominal wall is comparable with that of the light-weight polypropylene mesh, but the shrinkage is greater. The biocompatibility of the knitted PTFE mesh is comparable with that of the light-weight polypropylene implant.     

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.     

An experimental study exploring the relationship between the size of bacterial inoculum and bacterial adherence to prosthetic mesh

Background

Infection is a major concern with medical implants. Surgical meshes used for the repair of abdominal wall hernias are associated with wound infection rates ranging from 7 to 18 %. Although mesh infection is relatively rare, once a patient shows clinical signs of mesh infection, the surgeon may be required to remove the mesh, resulting in additional surgery, morbidity, and cost. The usual causative organisms associated with cases of mesh infection are Staphylococcus species. The first stage of implant infection is bacterial adherence to the biomaterial. An accurate assessment of adherent bacteria to medical prosthetics is therefore important in order to determine the infection risk associated with surgical implants.

Methods

This experimental study evaluated the relationship between the size of the bacterial inoculum and bacterial adherence to three commonly used hernia prosthetics (polypropylene, polyester, and ePTFE). Tenfold dilutions of S. epidermidis (Evans-ATCC 12228) and S. aureus (Rosenbach-ATCC 25923), created with phosphate-buffered saline, were used to inoculate each of the meshes in 3 ml of tryptone soya broth for 18 h at 37 °C, 95 % air/5 % CO₂. The number of viable bacteria in each dilution was calculated using a spot plate technique. The number of adherent bacteria to the meshes was counted using direct imaging analysis with scanning electron microscopy and expressed as a mean.

Results

One hundred eight mesh samples were analysed. The size of the bacterial inoculum of S. epidermidis significantly influenced the number of adherent bacteria to the mesh, and lower rates of adhesion were observed with smaller inoculums for all three meshes (polypropylene, p = 0.02; ePTFE p = 0.03; polyester p = 0.02). A similar, albeit less profound, pattern of results was observed with S. aureus. Bacterial adherence was observed with inoculum sizes as small as <10 bacteria.

Conclusions

The results demonstrate that even a very low number of bacterial inoculums can result in adherence to hernia biomaterials and that the level of adherence is directly related to the size of the inoculum. These in vitro results provide evidence that the size of the inoculum is important in the colonization of hernia biomaterials and demonstrate the importance of minimising the bacterial inoculum in the clinical setting.     

Myofibroblasts and colonic anastomosis healing in Wistar rats

Background

Mesh repair of incisional hernia is superior to the conventional technique. From all available materials for open surgery polypropylene (PP) is the most widely used. Development resulted in meshes with larger pore size, decreased mesh surface and lower weight. The aim of this retrospective non randomized study was to compare the quality of life in the long term follow up (> 72 month) after incisional hernia repair with "light weight"(LW) and "heavy weight"(HW) PP meshes.

Methods

12 patients who underwent midline open incisional hernia repair with a HW-PP mesh (Prolene^® 109 g/m² pore size 1.6 mm) between January 1996 and December 1997 were compared with 12 consecutive patients who underwent the same procedure with a LW-PP mesh (Vypro^® 54 g/m², pore size 4-5 mm) from January 1998. The standard technique was the sublay mesh-plasty with the retromuscular positioning of the mesh. The two groups were equal in BMI, age, gender and hernia size. Patients were routinely seen back in the clinic.

Results

In the long term run (mean follow up 112 ± 22 months) patients of the HW mesh group revealed no significant difference in the SF-36 Health Survey domains compared to the LW group (mean follow up 75 ± 16 months).

Conclusions

In this study the health related quality of life based on the SF 36 survey after open incisional hernia repair with light or heavy weight meshes is not related to the mesh type in the long term follow up.     

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 (Fe₃O₄)-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 Fe₃O₄ 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.     

Netzschrumpfung in der Hernienchirurgie

Objectives

According to an estimated mesh shrinkage following hernia repair of up to 40% a current dogma in hernia surgery requires a mesh overlap of 5 cm around the hernia. However, no valid data addressing this problem of mesh shrinkage are available at present.

Patients and methods

Within the framework of a prospective randomized double-blinded clinical trial, 50 patients were operated on for a ventral abdominal hernia with the open sublay technique using specially prepared radio-opaque polypropylene (PP) meshes. Of the patients 27 received a conventional heavyweight mesh (P group) and 23 a new lightweight mesh construction (NK group). Follow-up for at least 2 years after mesh repair included conventional abdominal x-rays after 7 days, 3 weeks and 4, 12 and 24 months, as well as computed tomography after 7 days and 4 and 12 months. Main criteria were mesh shrinkage, recurrence and complication rates and quality of life comparing groups P and NK.

Results

In 46 cases (92%) no mesh shrinkage could be detected and only 4 meshes (8%) showed a moderate shrinkage (1 of 22.2%, 2 of 8% and 1 of 3%) all from the P group. While no hernia recurrences were found, 2 surgical complications occurred with 1 seroma in the P group and 1 hematoma in the NK group. Quality of life showed a linear improvement over time up to the 2 year time point following mesh repair with advantages for the NK group. Pain and mobility scores reached standard values 12 months postoperatively without significant differences between the two groups.

Conclusions

In principle PP meshes following an uncomplicated ventral hernia repair do not shrink at all. A moderate shrinkage in isolated cases might occur following heavyweight mesh implantation. Under controlled conditions recurrence as well as complication rates are equal for heavyweight and lightweight PP meshes. Quality of life improves up to 2 years following mesh repair with a trend to a better outcome for lightweight meshes. Pain and mobility scores reached standard values 12 months postoperatively without significant differences between the lightweight and heavyweight meshes.     

Inadequate Cytology in Thyroid Nodules: Should We Repeat Aspiration or Follow-Up?

Background

To evaluate how to correctly manage thyroid nodules showing inadequate cytology after ultrasound (US)-guided fine-needle aspiration biopsy (US-FNAB).

Materials and Methods

A total of 393 thyroid nodules with inadequate cytology in 351 patients (M:F = 40:311, mean age: 49.3 years) with surgery or follow-up US-FNAB for at least 1 year were included in this study. Among them, 293 (74.6%) were benign and 100 (25.4%) were malignant on final reference results. Clinical characteristics and US features were reviewed and compared.

Results

Malignancy rates (39.5%) of nodules having suspicious US feature were significantly higher than those (10.9%) of nodules without any suspicious US feature (P < .001). Malignancy rates of solid nodules, mainly solid nodules, and mainly cystic nodules were 29.2, 16.7, and 9.5%, respectively, with significant differences (P = .016). Malignancy rates of nodules assessed as suspicious malignant to probably benign in composition are: 39.1–12.8% (P < .001) in solid nodules, 42.1–9.2% (P = .001) in mainly solid nodules, and 50.0–5.3% (P = .04) in mainly cystic nodules.

Conclusions

In nodules with inadequate cytology, follow-up US can be considered over repeat aspiration if there are no suspicious US features present, especially in mainly cystic nodules.     

Critical Assessment of Risk Factors for Complications After Cytoreductive Surgery and Perioperative Intraperitoneal Chemotherapy for Pseudomyxoma Peritonei

Background

Cytoreductive surgery (CRS) combined with perioperative intraperitoneal chemotherapy (PIC) has demonstrated improved survival in selected patients with pseudomyxoma peritonei (PMP). However, this aggressive treatment modality has been consistently associated with variable rates of perioperative mortality between 0% and 18% and morbidity between 30% and 70%. This study evaluates the clinical and treatment-related risk factors for perioperative morbidity and mortality in PMP patients who underwent CRS and PIC.

Materials and Methods

A total of 145 consecutive CRS and PIC procedures for PMP performed between January 1996 and March 2009 were evaluated. The association of 12 clinical and 20 treatment-related risk factors with grades III and IV/V morbidity were assessed by univariable and multivariable analysis.

Results

The mortality (grade V) rate was 3%. The morbidity rates of grades III and IV were 23% and 22%, respectively. Eight factors were associated with grade IV/V morbidity on univariable analysis: peritoneal cancer index ≥21 (P = .034), ASA score ≥3 (P = .003), operation duration ≥10 h (P < .001), left upper quadrant peritonectomy procedure (P = .037), colonic resection (P = .012), ostomy (P = .005), ileostomy (P = .012), and transfusion ≥6 units (p = 0.011). Multivariable analysis showed 2 significant risk factors for grade IV/V morbidity: ASA ≥ 3 (P = .006) and an operation length ≥10 h (P < .001).

Conclusions

CRS and PIC has an acceptable rate of perioperative mortality and morbidity in selected patients with PMP. Patients with bulky disease who undergo a long operation are at a particularly high risk of a severe adverse event.     

Postimplantation host tissue response and biodegradation of biologic versus polymer meshes implanted in an intraperitoneal position

Background

This study compared the in vitro and in vivo behaviors at the peritoneal interface of a new polymer material (Bio-A) and of two biologic non-cross-linked materials (Tutomesh [Tuto] and Strattice [St]), all biodegradable.

Methods

Omentum mesothelial cells from rabbits were seeded onto the three prosthetic materials tested. At 1, 4, 8, 16, and 24 h after implantation, mesothelial cover was performed using a scanning electron microscope (SEM). In the in vivo study, 3 × 3 cm mesh fragments were placed on the parietal peritoneum of the same rabbits and fixed at the four corners with individual stitches. The implants were randomized such that six fragments of each material were implanted in nine animals (2 per animal). Adhesion formation was quantified by sequential laparoscopy and image analysis 3, 7, and 14 days after implantation. The animals were killed at 90 days, and the meshes were subjected to microscopy and immunohistochemistry.

Results

The in vitro mesothelial cover was significantly greater for St than for Bio-A at each time point. The percentage of cover for St was also higher than for Tuto 16 and 24 h after seeding and higher for Tuto than for Bio-A at all time points. Compared with the biologic meshes, significantly higher adhesion percentages were recorded for Bio-A. At 90 days after implantation, differences in absorption measured as percentage of reduction in mesh thickness were detected among all the meshes. The least absorbed was St. The neoperitoneum thickness was significantly greater for the biologic meshes than for the polymer mesh, although this variable also differed significantly between St and Tuto. Macrophage counts were higher for Bio-A than for the biologic meshes.

Conclusions

Greater mesothelial cover was observed in vitro for St. In vivo, adhesion formation and the macrophage response induced by Bio-A were greater than those elicited by the biologic materials. Bio-A and Tuto showed substantial biodegradation compared with St.     

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.

     

An in vitro study assessing the effect of mesh morphology and suture fixation on bacterial adherence

Purpose

Prosthetic infections, although relatively uncommon in hernia surgery, are a source of considerable morbidity and cost. The aims of this experimental study were to assess the influence of the morphological properties of the mesh on bacterial adherence in vitro. The morphological properties assessed were the polymer type, filament type, filament diameter, mesh weight, mean pore size, and the addition of silver chlorhexidine and titanium coatings. In addition, the study assessed the effect on bacterial adherence of adding a commonly used suture to the mesh and compared adherence rates to self-gripping mesh that does not require suture fixation.

Methods

Eight commercially sourced flat hernia meshes with different material characteristics were included in the study. These were Prolene^® (Ethicon^®), DualMesh^® (Gore^®), DualMesh^® Plus (Gore^®), Parietex? ProGrip (Covidien?), TiMesh^® Light (GfE Medical), Bard^® Soft Mesh (Bard^®), Vypro^® (Ethicon^®), and Omyra^® (Braun^®). Individual meshes were inoculated with Staphylococcus epidermidis and Staphylococcus aureus with a bacterial inoculum of 10² bacteria. To assess the effect of suture material on bacterial adhesion, a sterile piece of commonly used monofilament suture material (2.0 Prolene^®, ZB370 Ethicon^®) was sutured to selected meshes (chosen to represent different commonly used polymers and/or the presence of an antibacterial coating). Inoculated meshes were incubated for 18 h in tryptone soy broth and then analysed using scanning electron microscopy. A previously validated method for enumeration of bacteria using automated stage movement electron microscopy was used for direct bacterial counting. The final fraction of the bacteria adherent to the mesh was compared between the meshes and for each morphological variable. One-way analysis of variance (ANOVA) was performed on the bacterial counts. Tukey’s test was used to determine the difference between the different biomaterials in the event the ANOVA was significant.

Results

Properties that significantly increased the mean bacterial adherence were the expanded polytetrafluoroethylene polymer (P < 0.001); multifilament meshes (P < 0.001); increased filament diameter (P < 0.001); increased mesh weight (P < 0.001); and smaller mean pore size (P < 0.001). In contrast, mesh coating with antibacterial silver chlorhexidine significantly reduced bacterial adhesion (S. epidermidis mean bacterial count 140.7 ± 19.1 SE with DualMesh^® vs. 2.3 ± 1.2 SE with DualMesh^® Plus, P < 0.001; S. aureus mean bacterial count 371.7 ± 22.7 SE with DualMesh^® vs. 19.3 ± 4.7 SE with DualMesh^® Plus, P = 0.002). The addition of 2.0 Prolene suture material significantly increased the mean number of adherent bacteria independent of the mesh polymer or mesh coating (P = 0.04 to <0.001).

Conclusion

The present study demonstrates the significant influence of the prosthetic load on bacterial adherence. In patients at increased risk of infection, low prosthetic load materials, i.e., lightweight meshes with large pores, may be beneficial. Furthermore self-fixing meshes, which avoid increasing the prosthetic load and antibacterial impregnated meshes, may have an advantage in this setting.     

Parastomal hernia repair with a 3-D mesh device and additional flat mesh repair of the abdominal wall

Purpose

Parastomal hernias (PSHs) have been a major clinical problem. The aim of this study was to evaluate a new method of PSH repair in combination with an additional flat mesh reinforcement of the abdominal wall.

Methods

In a pilot case series, seven patients suffering from complex PSHs (≥5 cm diameter and/or recurrence) underwent surgery and were treated by intraperitoneal onlay technique (IPOM) with a synthetic 3-D funnel-shaped mesh implant. The demographics, perioperative, and follow-up data are presented in this report.

Results

The surgical strategy varied between purely laparoscopic (n = 1), laparoscopically assisted (hybrid n = 3), or open techniques (n = 3) using original or suture-reconstructed mesh devices. The funnel mesh implantations in IPOM technique were combined with attached flat meshes in the appropriate position of the abdominal wall. No procedure-related complications occurred. The mean length of hospital stay was 12 days and the mean operating time was 171 min. No recurrence of PSH or incisional hernias was observed during a mean follow-up period of 12.3 months (range from 7 to 22).

Conclusion

The use of a 3-D mesh implant has so far shown to be a promising option in the treatment of primary and recurrent PSHs. Its use proved to be reasonable in both laparoscopic and open IPOM technique. PSHs were preferably repaired using the original, unmodified implant, but when we also found it safe to incise, place and then suture the mesh around the pre-existing ostomy.     

Highly purified collagen coating enhances tissue adherence and integration properties of monofilament polypropylene meshes

Introduction and hypothesis

Complications related to tissue integration of polypropylene implants used in the treatment of pelvic organ prolapse are relatively prevalent. Collagen, a biocompatible, less immunogenic material with modulating properties on the inflammatory process, may improve polypropylene integration. The objective was to study biomechanical and histological effects of monofilament polypropylene mesh coated with purified collagen gel.

Methods

Forty rats were implanted with two fragments of polypropylene mesh in their abdominal walls (one on each side of the linea alba). One of the fragments had a collagen gel coating (group I) while the other one did not (group II). The animals were euthanized at 7, 14, 90, and 180 days after implantation and their abdominal walls were excised for analysis.

Results

The biomechanical study showed that mesh adherence to neighboring tissue increased significantly in group II (p?<?0.05). Acute (p?<?0.001) and chronic (p?=?0.004) inflammatory responses as well as granulation tissue formation (p?=?0.001) were less intense in group II at 7 and 14 days. Granulomatous inflammation and foreign body reaction was less significant at 7 days in group II (p?=?0.029 and p?<?0.001). The birefringence analysis showed higher mean brightness density in the late phase of implantation in group II meshes (p?=?0.000).

Conclusion

Polypropylene mesh coated with purified collagen gel increases adherence to tissue, promotes a less intense and lasting inflammatory response and triggers a greater organization and packing arrangement of collagen fibers in the late phase of implantation.     

S100B Protein Expressions as an Independent Predictor of Early Relapse in UICC Stages II and III Colon Cancer Patients after Curative Resection

Background

S100 calcium-binding proteins such as S100B are elevated in primary malignant melanoma and are used as tumor markers for malignant melanoma and numerous other cancers. The purpose of this study was to identify the novel predictors of early relapse in UICC stages II and III colon cancer patients and thus to identify a subgroup of patients who are at high risk for postoperative early relapse.

Methods

Clinicopathological factors and S100B expression by immunohistochemical staining were retrospectively analyzed in 357 postoperative UICC stages II and III colon cancer patients to determine the predictors of early relapse.

Results

Of 357 patients, 114 patients developed postoperative relapse during the follow-up period. Among 114 relapsed colon cancer patients, postoperative early relapse and non-early relapse were found in 56 patients (49.1%) and 58 patients (50.9%), respectively. Multivariate Cox proportional hazards analysis revealed that the presence of vascular invasion (P = .025; hazard ratio [HR], 5.532; 95% confidence interval [95% CI], 1.985–14.729), high postoperative CEA levels (P = .019; HR, 6.845; 95% CI, 2.393–15.256), and S100B overexpression (P < .001; HR, 26.250; 95% CI, 7.463–96.804) were demonstrated to be independent predictors of postoperative early relapse. Furthermore, postoperative relapsed colon cancer patients with S100B overexpression were demonstrated to have significantly lower overall survival rates than those without S100B overexpression (P < .001).

Conclusions

This study suggests that S100B protein expression is a crucial predictor of early relapse in UICC stages II and III postoperative colon cancer patients and thus could help to define patients with this tumor entity who would benefit from enhanced follow-up and therapeutic program(s).