Tissue attachment strength of prosthetic meshes used in ventral and incisional hernia repair. A study in the New Zealand White rabbit adhesion model

Construction and properties of the silk fibroin and polypropylene composite biological mesh for abdominal incisional hernia repair

Background: In this study, a new composite biological mesh named SFP was prepared by combining silk fibroin with polypropylene mesh. The mechanism and clinical application value of the SFP composite mesh were explored.

Methods: The fibrous membrane was prepared by electrospinning of silk fibroin. The silk fibrous membrane was adhered to the polypropylene mesh by fibrin hydrogel to make a new composite mesh. The characterizations were verified by structural analysis and in vitro cell experiments. A total of 40 Sprague–Dawley rats were randomly divided into two groups, and 20 rats in each group were implanted with the SFP mesh and pure polypropylene mesh, respectively. The rats were sacrificed in batches on the 3rd, 7th, 14th, and 90th days after surgery. The adhesion degree and adhesion area on the mesh surface were compared, and a histopathological examination was carried out.

Results:In vitro cell function experiments confirmed that the SFP mesh had good cell viability. The control group had different degrees of adhesion on the 3rd, 7th, 14th, and 90th days after surgery. However, there was almost no intraperitoneal adhesions on the 3rd and 7th days after surgery, and some rats only had mild adhesions on the 14th and 90th days after surgery in the SFP group. There were statistically significant differences in the postoperative intraperitoneal adhesion area and adhesion degree between the two groups (p < 0.05). Histopathological examination confirmed that the mesenchymal cells were well arranged and continuous, and there were more new capillaries and adipocyte proliferation under the mesenchymal cells in the SFP group.

Conclusion: The SFP mesh shows good biocompatibility and biofunction in vitro and in vivo. It can promote the growth of peritoneal mesenchymal cells. The formation of a new mesenchymal cell layer can effectively reduce the extent and scope of adhesion between the mesh and abdominal organs. The SFP mesh will have a good application prospect in the field of abdominal wall hernia repair.

Comparison of ıncisional hernia models ın rats: an experimental study

PURPOSE

Incisional hernia repair is a frequently performed operation worldwide. In this experimental study, our aim is to present the incisional hernia model after creating midline laparotomy and several type of defects on abdominal wall of the rats. Thereby, the method determined here may be used in future experimental incisional hernia repair studies.

METHODS

After approval, 32 male rats were randomly seperated into 4 groups of 8 animals each, and were operated to form an incisional hernia; Sham group, 5 cm incision group, 5 cm incision plus capitonnage group, and 5 cm incision plus 2 × 4 cm muscle excision group, respectively. On the 28th postoperative day after killing, the abdominal anterior wall of rats were removed for histopathological and biomechanic examination.

RESULTS

The incisional hernia size was found to be statistically different in at least one group (p = 0.001). The incisional hernia size in Group 4 was found to be significantly higher than Group 2 (p = 0.001). When the tension and elongation values were examined, there was a difference in at least one group (p < 0.001 and p = 0.029, respectively). Histopathological examination shows that the degree of inflammation and fibrosis varies significantly (p = 0.001 and p = 0.002, respectively).

CONCLUSION

This study has lead us to believe that the rat model created by applying muscle excision from the midline of the abdomen is the ideal incisional hernia model that can be used in future experimental incisional hernia studies.

Comparison of coated meshes for intraperitoneal placement in animal studies: a systematic review and meta-analysis

PURPOSE

Laparoscopic intraperitoneal onlay mesh in hernia repair can result in adhesions leading to intestinal obstruction and fistulation. The aim of this systematic review is to compare the effects of mesh coatings reducing the tissue-to-mesh adhesion in animal studies.

METHODS

Pubmed and Embase were systematically searched. Animal experiments comparing intraperitoneally placed meshes with coatings were eligible for inclusion. Only studies with comparable follow-up, measurements, and species were included for data pooling and subsequent meta-analysis.

RESULTS

A total of 131 articles met inclusion criteria, with four studies integrated into one comparison and five studies integrated into another comparison. Compared to uncoated polypropylene (PP) mesh, PP mesh coated with hyaluronic acid/carboxymethyl cellulose (HA/CMC) showed significantly reduced adhesion formation at follow-up of 4 weeks measured with adhesion score of extent (random effects model, mean difference,-  0.96, 95% CI - 1.32 to - 0.61, P < 0.001, I² = 23%; fixed effects model, mean difference,- 0.94, 95% CI - 1.25 to - 0.63, P < 0.001, I² = 23%). Compared to PP mesh, polyester mesh coated with collagen (PC mesh) showed no significant difference at follow-up of 4 weeks regarding percentage of adhesion-area on a mesh, using random effects model (mean difference - 11.69, 95% CI - 44.14 to 20.76, P = 0.48, I² = 92%). However, this result differed using fixed effects model (mean difference - 25.55, 95% CI - 33.70 to - 7.40, P < 0.001, I² = 92%).

CONCLUSION

HA/CMC coating reduces adhesion formation to PP mesh effectively at a follow-up of 4 weeks, while the anti-adhesive properties of PC mesh are inclusive comparing all study data.

Use of surgical mesh of different compositions in the correction of the abdominal wall defect in rats

OBJECTIVE

To analyze the performance of two surgical meshes of different compositions during the defect healing process of the abdominal wall of rats.

METHODS

thirty-three adult Wistar rats were anesthetized and subjected to removal of an area of 1.5 cm x 2 cm of the anterior abdominal wall, except for the skin; 17 animals had the defect corrected by edge-to-edge surgical suture of a mesh made of polypropylene + poliglecaprone (Group U--UltraproTM); 16 animals had the defect corrected with a surgical mesh made of polypropylene + polidioxanone + cellulose (Group P--ProceedTM). Each group was divided into two subgroups, according to the euthanasia moment (seven days or 28 days after the operation). Parameters analyzed were macroscopic (adherence), microscopic (quantification of mature and immature collagen) and tensiometric (maximum tension and maximum rupture strength).

RESULTS

there was an increase in collagen type I in the ProceedTM group from seven to 28 days, p = 0.047. Also, there was an increase in the rupture tension on both groups when comparing the two periods. There was a lower rupture tension and tissue deformity with ProceedTM mesh in seven days, becoming equal at day 28.

CONCLUSION

the meshes retain similarities in the final result and more studies with larger numbers of animals must be carried for better assessment.

Inguinal hernia repair: can one identify the three main nerves of the region?

<sec><title>OBJECTIVE:</title><p> To identify the nerves in the groin during inguinal hernia repair by inguinotomy.</p></sec><sec><title>METHODS:</title><p> We conducted a prospective, sequenced, non-randomized study comprising 38 patients undergoing inguinal hernia repair with placement of polypropylene mesh.</p></sec><sec><title>RESULTS:</title><p> The male patients were 36 (94.7%), with a mean age and standard deviation of 43.1 ± 14.5, body mass index of 24.4 ± 2.8. Comorbidities were hypertension in two (5.2%), smoking in 12 (31.5%) and obesity in two (5.2%). The hernia was located only on the right in 21 (55.2%) patients, only on the left in 11 (28.9%), and was bilateral in six (15.7%) patients. Prior hernia repair was present in seven (18.4%) patients. The identification of the three nerves during operation was made in 20 (52.6%) patients, the ilioinguinal nerve and the iliohypogastric nerve were identified in 33 (86.8%), and the genital nerve branch of the genitofemoral nerve, in 20 (52.6%). Resection of at least one of the nerves was performed in seven (18.4%) cases, two iliohypogastric nerves and five ilioinguinal nerves. The average operating time was 70.8 ± 18.2 minutes. The hospital stay was 1.42 ± 1.18 days. Ten patients (26.3%) returned to physical activity around the first postoperative visit, and 37 (97.3%) in the last. The follow-up time was 95.6 ± 23.5 days. The inability to identify the ilioinguinal nerve was associated with previous repair (p = 0.035).</p></sec><sec><title>CONCLUSION:</title><p> The identification of the three nerves during inguinal hernia surgery has been described in more than half of the cases and prior repair interfered with the identification of ilioinguinal nerve.</p></sec>

Mechanical Response of the Herniated Human Abdomen to the Placement of Different Prostheses

This paper describes a method designed to model the repaired herniated human abdomen just after surgery and examine its static mechanical response to the maximum intra-abdominal pressure provoked by a physiological movement (standing cough). The model is based on the real geometry of the human abdomen bearing a large incisional hernia with several anatomical structures differentiated by MRI. To analyze the outcome of hernia repair, the surgical procedure was simulated by modeling a prosthesis placed over the hernia. Three surgical meshes with different mechanical properties were considered: an isotropic heavy-weight mesh (Surgipro®), a slightly anisotropic light-weight mesh (Optilene®), and a highly anisotropic medium-weight mesh (Infinit®). Our findings confirm that anisotropic implants need to be positioned such that the most compliant axis of the mesh coincides with the craneo-caudal direction of the body.

Evaluation of human acellular dermis versus porcine acellular dermis in an in vivo model for incisional hernia repair

Incisional hernias commonly occur following abdominal wall surgery. Human acellular dermal matrices (HADM) are widely used in abdominal wall defect repair. Xenograft acellular dermal matrices, particularly those made from porcine tissues (PADM), have recently experienced increased usage. The purpose of this study was to compare the effectiveness of HADM and PADM in the repair of incisional abdominal wall hernias in a rabbit model. A review from earlier work of differences between human allograft acellular dermal matrices (HADM) and porcine xenograft acellular dermal matrices (PADM) demonstrated significant differences (P < 0.05) in mechanical properties: Tensile strength 15.7 MPa vs. 7.7 MPa for HADM and PADM, respectively. Cellular (fibroblast) infiltration was significantly greater for HADM vs. PADM (Armour). The HADM exhibited a more natural, less degraded collagen by electrophoresis as compared to PADM. The rabbit model surgically established an incisional hernia, which was repaired with one of the two acellular dermal matrices 3 weeks after the creation of the abdominal hernia. The animals were euthanized at 4 and 20 weeks and the wounds evaluated. Tissue ingrowth into the implant was significantly faster for the HADM as compared to PADM, 54 vs. 16% at 4 weeks, and 58 vs. 20% for HADM and PADM, respectively at 20 weeks. The original, induced hernia defect (6 cm²) was healed to a greater extent for HADM vs. PADM: 2.7 cm² unremodeled area for PADM vs. 1.0 cm² for HADM at 20 weeks. The inherent uniformity of tissue ingrowth and remodeling over time was very different for the HADM relative to the PADM. No differences were observed at the 4-week end point. However, the 20-week data exhibited a statistically different level of variability in the remodeling rate with the mean standard deviation of 0.96 for HADM as contrasted to a mean standard deviation of 2.69 for PADM. This was significant with P < 0.05 using a one tail F test for the inherent variability of the standard deviation. No significant differences between the PADM and HADM for adhesion, inflammation, fibrous tissue or neovascularization were noted.

Use of negative pressure wound therapy in the management of infected abdominal wounds containing mesh: an analysis of outcomes

The purpose of this study was to examine the clinical outcomes of negative pressure wound therapy (NPWT) using reticulated open-cell foam (ROCF) in the adjunctive management of abdominal wounds with exposed and known infected synthetic mesh. A non randomised, retrospective review of medical records for 21 consecutive patients with infected abdominal wounds treated with NPWT was conducted. All abdominal wounds contained exposed synthetic mesh [composite, polypropylene (PP), or knitted polyglactin 910 (PG) mesh]. Demographic and bacteriological data, wound history, pre-NPWT and comparative post-NPWT, operative procedures and complications, hospital length of stay (LOS) and wound healing outcomes were all analysed. Primary endpoints measured were (1) hospital LOS prior to initiation of NPWT, (2) total time on NPWT, (3) hospital LOS from NPWT initiation to discharge and (4) wound closure status at discharge. A total of 21 patients with abdominal wounds with exposed, infected mesh were treated with NPWT. Aetiology of the wounds was ventral hernia repair (n = 11) and acute abdominal wall defect (n = 10). Prior to NPWT initiation, the mean hospital LOS for the composite, PP and PG meshes were 76 days (range: 21-171 days), 51 days (range: 32-62 days) and 19 days (range: 12-39 days), respectively. The mean hospital LOS following initiation of NPWT for wounds with exposed composite, PP and PG mesh were 28, 31 and 32 days, respectively. Eighteen of the 21 wounds (86%) reached full closure after a mean time of 26 days of NPWT and a mean hospital LOS of 30 days postinitiation of NPWT. Three wounds, all with composite mesh left in situ, did not reach full closure, although all exhibited decreased wound dimensions, granulating beds and decreased surface area exposure of mesh. During NPWT/ROCF, one hypoalbuminemic patient with exposed PP mesh developed an enterocutaneous fistula over a prior enterotomy site. This patient subsequently underwent total mesh extraction, takedown of the fistula and PP mesh replacement followed by reinstitution of NPWT and flap closure. In addition to appropriate systemic antibiotics and nutritional optimisation, the adjunctive use of NPWT resulted in successful closure of 86% of infected abdominal wounds with exposed prosthetic mesh. Patient hospital LOS (except those with PG mesh), operative procedures and readmissions were decreased during NPWT compared with treatment prior to NPWT. Future multi-site prospective, controlled studies would provide a strong evidence base from which treatment decisions could be made in the management of these challenging and costly cases.

Open versus laparoscopic incisional hernia repair: something different from a meta-analysis

BACKGROUND

Incisional hernias after laparotomy are a large financial burden for society as well as for the patients suffering from pain and limitations of activity over time. The introduction of alloplastic materials such as polypropylene seems to improve the results. The question of whether to apply open or laparoscopic implantation of the mesh is of ongoing interest. We compare the available alloplastic materials and try to clarify the question of whether the laparoscopic procedure is superior to the conventional (open) technique based on the available randomized studies.

METHODS

All available meshes for intraperitoneal and extraperitoneal implantation were described regarding their handling and their pros and cons. A database search (PubMed, Medline, Ovid, and in the secondary literature) was carried out to retrieve all randomized studies comparing laparoscopic and open hernia repair. Data were reviewed by two independent scientists for surgical and statistical design.

RESULTS

The ideal mesh for a laparoscopic maintenance of abdominal wall hernias as well as the optimal fixation of the mesh has not been found yet. Recent available literature shows no evidence demonstrating the superiority of one of these meshes. The available studies found a lower infection rate, but higher occurrence of seroma for the laparoscopic procedure. The value of the different studies is reduced due to deficiency in study design and power. Guidelines for further studies are discussed to avoid surgical and statistical pitfalls.

CONCLUSIONS

Laparoscopic incisional hernia repair shows, in some (randomized) studies as well as a large number of retrospective analyses and in case control studies, superiority compared to conventional hernia repair. Long-term results with a high level of evidence are not available. Additional well-designed randomized trials including long-term observation of patients are required in order to clarify a number of interesting questions.

Laparoscopic approach to recurrent incisional hernia repair: a 3-year experience

BACKGROUND

Incisional hernias are one of the most frequent complications of open abdominal surgery. The incidence of relapses after a conventional repair procedure is higher in recurrent than in primary cases (30%-50% vs. 11%-20%). The laparoscopic approach can prevent the complications associated with the conventional approach when dealing with recurrent incisional hernias. The aim of this study was to evaluate the efficacy of laparoscopic treatment in such cases.

MATERIALS AND METHODS

We prospectively analyzed data from 41 consecutive patients with recurrent incisional hernias, who submitted to a laparoscopic repair procedure with an expanded polytetrafluoroethylene Dual Mesh (Gore-Tex Dual Mesh Plus Biomaterial; W.L. Gore 8 Associates) from December 2001 to December 2004. All of the patients underwent clinical follow-up at 1, 6, and 12 months and then yearly. An ultrasound scan of the abdominal wall was performed at 6 and 12 months after the procedure. The parameters considered for the analysis were: mesh size, operating time, hospital stay, postoperative complications, and recurrences.

RESULTS

The defects were usually localized along midline laparotomies. The mean mesh size was 400 cm2, the mean operating time was 68 minutes, and the mean length of hospital stay was 2.7 days. Complications were encountered in 17% of patients. The mean follow-up was 38 months (range, 18-54). Recurrence was reported in 1 case only (2.4%), which occurred within the first 6 months after the operation.

CONCLUSIONS

The laparoscopic repair of recurrent incisional hernia seems to be an effective alternative to the conventional approach, as it can give lower recurrence and complication rates.

Choice of mesh for laparoscopic ventral hernia repair

BACKGROUND

Surgical treatment of ventral hernias has changed dramatically over the past decades by the introduction of laparoscopy and prosthetic biomaterials for reinforcement of the abdominal wall. There are many meshes available on the market for laparoscopic ventral hernia repair (LVHR), and new meshes are introduced regularly. Experimental and clinical documentation for safety and efficacy are, however, often not available for the clinician. The choice of mesh may therefore be difficult in clinical practice. We present a review of the current literature regarding safety measures such as adhesions, fistulas, and infections as well as the available data on pain, recurrence, mesh shrinkage, and seroma formation after LVHR.

METHODS

The literature was searched systematically using PubMed/MEDLINE and EMBASE for controlled studies, prospective descriptive series and retrospective case series.

RESULTS

The literature clearly points in the direction of very few mesh-related complications after LVHR. Experimental studies and theoretical considerations may argue for using a covered mesh, i.e., a composite mesh, or ePTFE for LVHR in humans, although it is important to stress that there are no human data at the moment to support this. Concerns about using pure polypropylene mesh in the intraperitoneal position may be re-evaluated with the experience of lightweight macropore meshes from open surgery in mind. There is a tendency towards greater shrinkage in ePTFE-based meshes but no differences seems to exist between different mesh materials in other relevant outcome parameters from clinical series.

CONCLUSIONS

The literature cannot give general recommendations for choice of mesh based on randomized controlled trials. The final choice of mesh for LVHR will therefore typically be based on surgeons' preference and cost while we await further data from randomized controlled clinical trials.

Bursting Strength Evaluation in an Experimental Model of Incisional Hernia

Incisional hernias occur in up to 11 per cent of patients undergoing abdominal surgery. Up to 50 per cent of these patients with hernias will require repeat operative procedures. Management of these hernias have focused primarily on tensile strength of the mesh material, have not addressed currently used materials, and have not compared the strength of these repairs with each other. Forty-nine adult Sprague–Dawley rats had an incisional hernia created by removing a portion of their abdominal wall that was then repaired primarily, using either a composite mesh, Dual mesh (Gore-Tex), or polypropylene mesh. Six weeks after the repair, the rats were euthanized. Hydrostatic distension of the abdominal cavity was performed to compare bursting strength of each repair. Wound tensile strength was assessed and compared. Tissue samples were also taken to compare repair types for incorporation of prosthetic materials. The gross weight of the animals subjected to hydrostatic distention was equivalent between groups, as was the volume required prior to failure of the repair. There was a trend toward improved tensile strength of the Prolene mesh repair, which had a lower average inflammatory and fibrosis score on histology. Overall, the type of mesh used for repair does not seem to impact significantly the strength of the repair when assessed 6 weeks postoperatively. Choice of prosthetic material to repair the hernia should be made based on economics and handling characteristics alone. Prolene mesh has satisfactory strength with the least amount of inflammation and fibrosis.

The Efficacy of Bilateral Lower Abdominal Free Flaps for Unilateral Breast Reconstruction

BACKGROUND

In large-breasted women, those with midline abdominal scars, or those with scant abdominal tissue, a unipedicled lower abdominal flap may be insufficient for breast reconstruction. In these circumstances, bipedicled flaps may best satisfy the reconstructive requirements, but outcomes with bilateral free flaps for unilateral breast reconstruction are generally lacking.

METHODS

A retrospective review of patients in whom two vascular pedicles/flaps were used to simultaneously reconstruct a single breast was used to assess operative outcomes.

RESULTS

Forty patients (80 flaps) for whom two free tissue transfers were used to simultaneously reconstruct a single breast were identified. The majority of patients had a native breast cup size of C or larger. The flaps used included the superficial inferior epigastric artery (SIEA) flap (n = 29; 36 percent), the transverse rectus abdominis musculocutaneous (TRAM) flap (n = 9; 11 percent), the muscle-sparing TRAM flap (n = 15; 19 percent), and the deep inferior epigastric perforator (DIEP) flap (n = 27; 34 percent). Flaps were paired in a variety of configurations, most commonly using a muscle-sparing TRAM flap in conjunction with a DIEP flap or an SIEA flap. Recipient vessels included a combination of the internal mammary and thoracodorsal vessels and the pedicles of combined flaps (turbocharged). There were no flap losses. Two flaps required reexploration for microsurgical anastomotic revision, and both were successfully salvaged. Isolated fat necrosis was encountered in only three of 80 flaps.

CONCLUSIONS

This study suggests that bilateral, bipedicled, abdominal free flaps for unilateral breast reconstruction can be used safely with a high degree of success. These combined flaps provide for enhanced vascular perfusion of the lower abdominal flap territory, allowing for harvest of larger volumes of tissue for reconstruction.

Sleeve gastrectomy with wrapping using polytetrafluoroethylene to prevent gastric enlargement in a porcine model

BACKGROUND

The safety and efficacy of laparoscopic sleeve gastrectomy followed by biliopancreatic diversion with duodenal switch for morbid obesity has been well established. We previously recommended 2-stage laparoscopic biliopancreatic diversion with duodenal switch for super-super obese patients. In the 2-stage version, these patients undergo laparoscopic sleeve gastrectomy as a first-stage procedure, followed by laparoscopic biliopancreatic diversion with duodenal switch as the second stage for more definitive treatment of their obesity. However, short-term weight regain may occur owing to gastric dilation after initial laparoscopic sleeve gastrectomy. The aim of this study was to prevent gastric dilation after sleeve gastrectomy. We designed a sleeve gastrectomy with wrapping using polytetrafluoroethylene dual mesh.

METHODS

Eleven Yorkshire pigs weighing 20-25 kg underwent sleeve gastrectomy with wrapping using polytetrafluoroethylene dual mesh (wrapping group) or sleeve gastrectomy only (control group) to compare the weight loss. The animals were weighed weekly postoperatively. Necropsy was performed 8 weeks postoperatively to confirm the wrapping by pathologic report.

RESULTS

Four pigs died because of staple line failure or strangulation; no perioperative complications occurred in the other pigs. The operative time for the control group was 198 +/- 60 minutes and for the wrapping group was 181 +/- 86 minutes (P = NS). The average weight of the removed stomach was 123.3 +/- 5.8 g in the control group and 140.3 +/- 69.9 g in the wrapping group (P = NS). The postoperative weight gain at 8 weeks was significantly slower in the wrapping group than in the control group (P <.0001). The pathologic necropsy report noted that the mesh was well attached to the stomach wall at 9 days postoperatively, with no unexpected deaths.

CONCLUSION

Sleeve gastrectomy with wrapping using polytetrafluoroethylene dual mesh is feasible, and weight gain was reduced in the porcine model.

Revision in Autologous Breast Reconstruction: Principles and Approach

As breast reconstruction has an aesthetic endpoint, secondary surgical intervention is an integral part of this process. This article examines revision in autologous breast reconstruction from the perspective of clinical priority. The authors examine challenges they may be faced in autologous breast reconstructions and suggest surgical approaches toward their resolution.

Strength of tissue attachment to mesh after ventral hernia repair with synthetic composite mesh in a porcine model

BACKGROUND

A prospective animal study involving 12 female swine aimed to measure the strength of tissue attachment to composite mesh at various time points after laparoscopic ventral hernia repair in a porcine model.

METHODS

Each animal had two 10 x 16-cm sheets of polypropylene/expanded polytetrafluoroethylene (ePTFE) composite mesh laparoscopically affixed to the abdominal wall with a helical tacking device. No transfascial sutures were used. The animals were euthanized 2, 4, 6, and 12 weeks after surgery, and abdominal walls were resected en bloc with the patches. Each patch was cut into 2 x 7-cm strips, and each strip was independently analyzed. The strength of the tissue attachment to the mesh was measured using a servohydraulic tensile testing frame. The abdominal wall was peeled from the mesh, and the transverse, or "lap-shear" force was recorded. Data are reported as mean force in pounds.

RESULTS

The mean lap-shear force was 0.83 +/- 0.06 lbs at 2 weeks, 1.06 +/- 0.07 lbs at 4 weeks, 0.88 +/- 0.08 lbs at 6 weeks, and 1.13 +/- 0.07 lbs at 12 weeks. The mean force was higher at 12 weeks than at 2 weeks (p < 0.05). No other periods were significantly different from any other.

CONCLUSIONS

The findings demonstrate that the majority of tissue ingrowth and strength has occurred by 2 weeks after laparoscopic placement of a composite hernia prosthesis. Strength very gradually increases until 12 weeks after surgery. This has clinical implications for human ventral hernia repair. Further study is needed to evaluate the necessity of transfascial sutures for securing polypropylene-based prostheses to the abdominal wall during ventral hernia repair.

Effects of different kinds of meshes on postoperative adhesion formation in the New Zealand White rabbit

The aim of this study was to compare the effect of different kinds of surgical meshes on postoperative adhesion formation. Forty-two New Zealand White rabbits were studied. The rabbits were grouped into six groups, according to the type of surgical meshes (Prolene, Mersilene, Vypro, polytetraflouroethylene (PTFE), Proceed and control group) implanted into the peritoneum cavity. Thirty days after the operation, the relaparotomies were carried out, and any adhesions observed between the implanted mesh and tissues were evaluated and graded. The mean adhesion degree was 9.2 in the Mersilene mesh group, 9.5 in the Prolene mesh group, 9.7 and in the Vypro mesh group (P > 0.05). The mean adhesion degree was 1 in the control group, 2.75 in the Proceed mesh group and 2.25 in the PTFE mesh group. There was a significant difference in adhesion degree between the control, Proceed and PTFE groups and the Prolene, Mersilene and Vypro mesh groups. The adhesion degree was significantly lower in the Proceed and PTFE mesh groups when comparing them with the Prolene, Mersilene and Vypro meshes.

Laparoscopic ventral hernia repair using expanded polytetrafluoroethylene-polyester mesh compound

BACKGROUND

Many biomaterials and composites have been used in clinical and experimental laparoscopic ventral hernia repair. The ideal prosthesis should allow firm binding to the abdominal wall without adhesion to the bowel.

METHODS

A compound prosthesis was made by circumferentially suturing a Gore-Tex mesh as visceral interface to a smaller polyester mesh as parietal interface, and it was used in 46 laparoscopic ventral hernia repairs between January 2000 and December 2004.

RESULTS

Average operative time was 65 min, with no intraoperative complications. Mean hospital stay was 2.2 days. Postoperative complications were five seromas, two hematomas, and one recurrence after a mean follow-up of 32.2 months.

CONCLUSION

The prosthesis used was made of two biomaterials that have been tested and tried over the years. The polyester layer is known to induce sufficient tissue ingrowth, whereas Gore-Tex minimizes adhesion formation. The memory of the compound was high enough to allow easy laparoscopic unrolling and handling.

Use of the omentum flap as additional soft-tissue cover for abdominal wall defects reconstructed with Gore-Tex

BACKGROUND

Use of alloplastic materials such as Gore-Tex and locoregional flaps for reconstruction of large abdominal wall defects has been well described. The purpose of this article is to present a novel technique of using the omentum as an interpositional flap to protect the Gore-Tex repair of the abdominal wall.

METHODS

Four patients with large abdominal wall defects underwent reconstruction with Gore-Tex and omentum flap. These defects resulted from tumor resection and recurrent incisional hernia. Their dimensions ranged from 15 x 10 cm to 25 x 27 cm. The Gore-Tex patch was inset using an underlay technique. The omentum was tunneled through a separate opening in the abdominal wall into the subcutaneous plane and used to cover the Gore-Tex. Skin coverage was accomplished by direct closure or myocutaneous flaps.

RESULTS

The mean follow-up was 17 months. All wounds healed, with no hernias. One patient developed a subcutaneous abscess 6 months postoperatively, and this was treated successfully by percutaneous drainage, as the omentum had walled-off the abscess.

CONCLUSION

The omentum flap served as an additional soft-tissue cover over the Gore-Tex repair to prevent exposure in the event of infection or flap breakdown. This technique is useful in situations in which delayed wound healing is anticipated or when large quantities of prosthetic material are used.

Evaluation of implant/host tissue interactions following intraperitoneal implantation of porcine dermal collagen prosthesis in the rat

An ideal prosthesis for ventral hernia repair should minimize development of postoperative adhesions. This study evaluates adhesion formation following intraperitoneal implantation of acellular porcine dermal collagen (PDC) and polypropylene (PP) mesh in 16 rats. Implant placement alternated left/right. Sacrifice (4 or 12 weeks) was randomized. Methods included adhesion grading (extent, severity, required dissection method) and histological evaluation. At 4 weeks, 7 of 8 PDC specimens and 0 of 8 PP implants were adhesion-free; results were identical at 12 weeks. Four-week adhesions were less developed than 12-week adhesions. Histology showed mononuclear cell foreign body reaction and disorganized collagen deposition for PPs compared to infiltration with neovascular channels and qualitatively less intense foreign body reaction for PDCs. PDC exhibits fewer adhesions and more favorable cellular response than PP in the rat.

Laparoscopic ventral hernia repair with the Goretex Dualmesh: long-term results and review of the literature

Since 1993 laparoscopy has become a popular technique of repair of ventral hernias. The authors review the long-term results of a systematic laparoscopic repair of ventral hernias and discuss the current problems compared to open repair. Between 1997 and 2003, 146 patients had a laparoscopic ventral hernia repair using an intraperitoneal Goretex Dualmesh with a 3-5-cm mesh overlap secured with a combination of nonabsorbable sutures and staples. A total of 155 attempts of laparoscopic repair was performed with four conversions. The 151 laparoscopic operations were completed in 105.8 min with a mesh implant being of 341 cm(2). There were two postoperative deaths and two patients had to be reoperated on. Mesh infection was diagnosed in two cases. Mean length of stay was 4.9 days. During a follow- up of 26.6 months eight patients (5.8%) developed a recurrence. Laparoscopic ventral hernia repair is a reproducible technique. Most of the comparative studies have shown an overall lower rate of complications after laparoscopic repair compared to open but with a 2-4% risk of bowel injury. The two other benefits of the laparoscopy are reduced postoperative pain and shorter hospital stay. The recurrence rate is usually between 2 and 7% but no difference has been found compared to open repair. Laparoscopic ventral hernia repair using the Goretex Dualmesh is a reliable operation with a low rate of conversion to open. Despite the risk of serious bowel injury, laparoscopy achieves as good results as the mesh open repair on the long term with the benefit of a decreased complication rate and a shorter hospital stay.

Incisional Hernia Repair: Laparoscopic Techniques

Repair of incisional hernias using the laparoscopic technique has continued to evolve since its inception in 1991. An analysis of the current literature has revealed that hernias as large as 1600 cm2 have been successfully repaired with this method. The average size appears to be about 105 cm2. Several choices of a biomaterial are available today, differing in the type of synthetic product or products that are used to manufacture them. Others incorporate an absorbable component. The goal of all of them is to prevent adhesion formation. The fixation devices that can be used are also varied. The results of laparoscopic incisional hernia repair are described. The conversion rate of these procedures is an impressive 2.4% with an enterotomy rate of 1.8%. These results affirm the low risk of this operation. The recurrence rate of 4.2% confirms the permanence of the repair. This procedure may become the standard of care in the near future.

Progressive fascial wound failure impairs subsequent abdominal wall repairs: a new animal model of incisional hernia formation

BACKGROUND

Fascial wound failure alters the phenotype of the abdominal wall. This study introduces a novel animal model of progressive failure of the ventral abdominal wall fascia, which generates large incisional hernias.

MATERIAL AND METHODS

A mechanistic model of incisional hernia was compared with a model of acute myofascial defect hernia repair. Using biological tissue repair markers, tensiometric measurements and recurrent hernia rate, we measured the mechanism by which incisional hernias regenerate abdominal wall structure and function after mesh and suture herniorrhaphy.

RESULTS

Recurrent incisional hernia formation was significantly increased after repairs of the hernia model, compared with the myofascial defect model (6/16 vs 0/16, P < .05). In the hernia model, there were significant decreases in the recovery of wound strength, energy, and extensibility before mechanical disruption, compared with the myofascial defect model. Unexpectedly, excision of fascial hernia wound edges did not significantly improve tissue repair outcomes in the hernia model group.

CONCLUSIONS

Clinically accurate animal modeling can recreate the wound pathology expressed in mature incisional hernias. Progressive fascial wound failure decreases the fidelity of subsequent incisional hernia repair, compared with identically sized acute abdominal wall defect repairs. The mechanism appears to include decreased fascial wound strength and decreased tissue compliance after herniorrhaphy.

A Grynfeltt hernia: Report of a case

Superior lumbar hernia (Grynfeltt hernia) is an uncommon variety of abdominal wall defect. There are three types of lumbar hernia: congenital, acquired, and incisional hernias. Diagnosis depends largely on the capacity for clinical suspicion, and confirmation is based on imaging tests. We report a case of an acquired lumbar hernia diagnosed by computed tomography (CT), which was treated successfully at our institution.

Burst strength of laparoscopic and open hernia repair

BACKGROUND

There are few reports of overall strength of laparoscopic and open incisional hernia repair.

METHODS

After anesthesia, a 2-inch circular defect was made in the abdominal wall of 28 female swine. Gore-Tex DualMesh Biomaterial (W. L. Gore & Associates, Flagstaff, AZ) was used for all repairs. Sixteen animals underwent open repair and 12 underwent laparoscopic repair. Burst strength was detected within 2 weeks and at 6 weeks by euthanizing the animals and insufflating the abdominal cavity with water while measuring the intraabdominal pressure until it could no longer be pressurized.

RESULTS

Three events occurred after insufflation: rupture around patch (R), dissection from insufflation or pressure monitoring sites (D), or rectal prolapse (P). Failure after open early repair occurred at 289 (range 219-388) mmHg with 7-R, 1-P and late 289 (196-343) mmHg with 1-R, 6-P. Failure after laparoscopic early repair occurred at 259 (191-388) mmHg with 4-R, 1-P, 1-D and late 291 (140-330) mmHg with 2-R, 1-P, 3-D. Late groups were less likely to rupture.

CONCLUSION

Both hernia repairs are durable at early and late periods. Tissue ingrowth adds to repair strength. We could not show that one repair was stronger than the other. Nonetheless, laparoscopic repair tended to degrade by dissection, which was our highest pressure event.

Comparison of Tissue Integration between Polyester and Polypropylene Prostheses in the Preperitoneal Space

Tissue integration and implant characteristics of various biomaterials commonly used for inguinal hernia repair have not been studied extensively. The aim of this study is to compare behavior and tissue response between two new polyester prostheses and a commonly used polypropylene (PP) mesh. The polyester prostheses utilized were polyester flat (PF) and polyester soft three-dimensional (PS); the PP mesh utilized was Marlex®. Eight randomly assigned 4 x 4-cm2 pieces of two different meshes were fixed in the preperitoneal space with a centrally placed single suture. Gross evaluation included shrinkage and stiffness. Histological evaluation included amount of fibrous and fat encapsulation, connective tissue, foreign-body reaction, neovascularization, hemorrhage, necrosis, and exudate. Evaluations were graded on a zero to four scale. The area and the area ratio were measured using a calibrated micrometer. PP mesh resulted in more fibrous encapsulation and stiffness than PF and PS prostheses. PP also resulted in less connective tissue formation and foreign-body reaction than PF and PS prostheses. There was no difference in fat encapsulation, necrosis, hemorrhage, or exudate between prostheses. Both polyester prostheses (PF and PS) have better tissue integration than the PP mesh, as evidenced by the higher amount of connective tissue and lower extent of fibrous encapsulation.