Prevention of adhesions to polypropylene mesh

BACKGROUND: Polypropylene mesh used to repair abdominal wall hernias routinely induces dense adhesions if there is direct contact between the mesh and the viscera. Adhesions may lead later to difficult reoperation, intestinal obstruction, or enteric fistula. STUDY DESIGN: A 2.5-cm square defect was surgically created in the rat abdominal wall and replaced with: 1) polypropylene mesh, 2) Sepramesh (SM), or 3) SM plus Seprafilm. Each group included 20 animals. Adhesion area as a percent of the mesh surface was subjectively quantitated by means of laparoscopy and at sacrifice. Evaluations varied from 7 to 28 days after mesh placement. Tissues were harvested at intervals for scanning electron microscopy. RESULTS: Adhesions were complete by day 7, with no change in area thereafter. Adhesion-free mesh surfaces were found on scanning electron microscopy to be carpeted with mesothelial cells from day 5 on. Polypropylene mesh alone induced adhesions in all rats (20/20). The mean area involved was 92%. With SM, 9 of 20 were adhesion-free. The mean area was 15%. When Seprafilm was added to SM, minimal adhesions developed in 5 of 20 rats, the mean area being 2%. Four of the five were single point omental attachments. CONCLUSIONS: 1) Sepramesh alone reduces polypropylene mesh adhesions by roughly three-quarters. 2) Sepramesh plus Seprafilm nearly eliminates such visceral adhesions. 3) Mesothelial cell coverage of polypropylene mesh confers adhesion resistance.     

Evaluation of seprafilm and amniotic membrane as adhesion prophylaxis in mesh repair of abdominal wall hernia in rats

INTRODUCTION: Adhesion formation following abdominal wall hernia repair with prosthetic mesh may lead to intestinal obstruction and enterocutaneous fistula. Physical barriers, namely, human amniotic membrane (HAM) or Seprafilm (Genzyme, Cambridge, Mass., USA), a bio-absorbable, translucent membrane composed of carboxymethylcellulose and hyaluronic acid, have been reported to prevent postsurgical intra-abdominal adhesions. OBJECTIVE: Evaluating the effect of HAM and Seprafilm in preventing adhesion formation in the rat model of ventral hernia repair with polypropylene mesh (PPM). MATERIAL AND METHODS: Sixty female Sprague-Dawley rats were divided into three groups. A full-thickness abdominal wall defect was created in each animal. Control animals had the PPM sutured into the defect, whereas in the other two groups, either HAM or Seprafilm were laid over the abdominal viscera before the repair with PPM. Half of the animals in each group were sacrificed on the 21st postoperative day. The remaining rats of the same group were re-operated on the 42nd day for investigation and measurement of the adhesion area in relation to the graft area. RESULTS: Direct mesh repair showed 52.8 and 56% area adhesion formation 3 and 6 weeks postoperatively, respectively. The HAM barrier covered with mesh repair demonstrated 0 and 0.96% area adhesion formation, and the Seprafilm-covered mesh repair showed 0 and 0% area adhesion formation 3 and 6 weeks postoperatively, respectively. Uncovered mesh showed a significantly larger adhesion area than both covered mesh (p = 0.001 and 0.001). Both HAM and Seprafilm were equally effective in preventing postoperative adhesions. CONCLUSIONS: HAM and Seprafilm proved to be an effective antiadhesive barrier in PPM repair of abdominal wall hernia.     

Effects of seprafilm on peritoneal fibrinolytic system

BACKGROUND: There is a high incidence of adhesions after ventral hernia repair with polypropylene mesh. The purpose of the present study was to evaluate the efficacy of Seprafilm in the prevention of adhesion formation and effect on peritoneal fibrinolytic activity. METHODS: An incisional hernia model was created in rats. In the experimental group Seprafilm was placed between polypropylene mesh and abdominal organs. On the 14th day adhesions were evaluated and tissue plasminogen activator (tPA), urokinase plasminogen activator (uPA), plasminogen activator inhibitor (PAI) type 1 and 2 were measured in peritoneal biopsy specimens. Results: Adhesions were significantly reduced in the Seprafilm group (P = 0.002). Nevertheless, there were no difference between the two groups in levels of tPA, PAI-1 and PAI-2. However, the levels of uPA were significantly decreased in the Seprafilm group. CONCLUSIONS: The adhesion preventive effect of Seprafilm is not directly related in peritoneal fibrinolytic activity. Instead, the physical properties (barrier, hydroflotation and sliconizing effect) of the membrane are primarily responsible for adhesion prevention.     

Seprafilm reduces adhesions to polypropylene mesh and increases peritoneal hydroxyproline

Polypropylene mesh is an effective and widely used material in repairing abdominal wall defects, but it causes dense adhesions when in contact with abdominal viscera directly. As a consequence of this process intestinal obstruction and enterocutaneous fistula may develop. The purpose of the present study was to determine whether Seprafilm, a bioresorbable translucent membrane, reduces abdominal visceral adhesions to polypropylene mesh and whether Seprafilm has any effects on peritoneal tissue hydroxyproline levels. Twenty-six adult Wistar rats were used. A full-thickness abdominal wall defect was created and cecal abrasions were created to induce adhesion formation in each animal. All of the abdominal defects were repaired with polypropylene mesh. In addition a Seprafilm membrane was laid over the abdominal viscera in the Seprafilm group (n = 13). The abdominal cavity was evaluated for adhesion formation, and peritoneal biopsies were taken for the measurement of tissue hydroxyproline levels at the 14th day. The use of Seprafilm resulted in significant reduction in the adhesion formation (P = 0.002) and a significant increase in peritoneal hydroxyproline level (P < 0.0001). These findings demonstrate that the increase of peritoneal hydroxyproline levels caused by Seprafilm might play a role on the antiadhesive effects of Seprafilm.     

Prevention of adhesions to polypropylene mesh in a rabbit model

The purpose of this study was to develop a quantitative model for evaluating adhesion formation and to determine whether Seprafilm (HAL-F) bioresorbable membrane (Genzyme Corp., Cambridge, MA) is effective in preventing adhesions to polypropylene mesh (PPM). PPM has been shown to be an effective material for the repair of abdominal wall defects. One disadvantage of PPM is its tendency to form dense adhesions when in contact with abdominal viscera. HAL-F, a sodium hyaluronate/carboxymethylcellulose absorbable membrane, has been shown to prevent adhesion formation after midline closures. Its efficacy in preventing adhesions to PPM has not been examined previously. A 5 x 7-cm anterior abdominal wall defect was created in 24 New Zealand White rabbits. This defect was then repaired with PPM. In the experimental group, a 5 x 7-cm piece of HAL-F was placed between the mesh and the abdominal viscera. At 30 days, the animals were killed and adhesions were categorized and quantified using digital image analysis of inked specimens. The strength of mesh incorporation into surrounding tissues was also examined using an Instron tensiometer. The formation of adhesions between the viscera and mesh repair was significantly reduced by the use of HAL-F. The surface area involved for bowel adhesions was reduced 94 per cent (P = 0.00132). The strength of incorporation was not adversely affected. HAL-F is highly effective in preventing adhesions to PPM, without adversely effecting the strength of mesh incorporation.     

Prevention of adhesions to polypropylene mesh in a traumatized bowel model

BACKGROUND: Polypropylene mesh (PPM) is an effective material for the repair of abdominal wall defects, but has a tendency to induce dense adhesions when in contact with viscera. Seprafilm (Genzyme Corp, Cambridge, MA), a bioresorbable membrane, has been shown to reduce adhesion formation after midline closures in humans and to PPM in animals. Given the increased inflammatory response expected with surgical trauma, its efficacy under surgical conditions has been questioned. STUDY DESIGN: A prospective, randomized, blinded study was conducted using a rabbit model. Standardized abdominal wall defects were created in three groups of New Zealand white rabbits. The cecum was deserosalized to simulate the effects of trauma. The abdominal defect was then repaired with PPM. In the control group, no Seprafilm was used. In the first experimental group Seprafilm was placed between the mesh and the abdominal viscera. In the second experimental group Seprafilm was placed over the deserosalized area and between the mesh and abdominal viscera. Animals were sacrificed at 30 days and adhesions were categorized and quantified using digital image analysis of inked specimens. The strength of incorporation was also determined. RESULTS: The formation of adhesions between the viscera and mesh repair was dramatically reduced in both experimental groups compared with the control group. The incidence of visceral adhesions was reduced by 80% in the single film group (p = 0.0004) and 90% in the double film group (p = 0.00008). The reduction in surface area of adhesions was 96.4% in the single film group (p = 0.000019) and 99.4% in the double film group (p = 0.00002). Omental adhesions were reduced by 30% but this did not achieve statistical significance. Strength of incorporation was not adversely affected in either group. CONCLUSIONS: Seprafilm is highly effective in preventing adhesions to PPM. This effect was not diminished by the presence of visceral trauma and its resultant inflammatory response. The use of Seprafilm does not adversely affect tissue incorporation. Clinical trials are warranted to determine if the protective effects of Seprafilm demonstrated in this study are applicable in the clinical setting.     

Abdominal adhesions to prosthetic mesh evaluated by laparoscopy and electron microscopy

BACKGROUND: Most adhesion experiments involve observations at a single time point. We developed a method to evaluate abdominal adhesions to surgical mesh by sequential laparoscopy. STUDY DESIGN: An abdominal wall defect was created in rats and repaired with polypropylene mesh. Sequential laparoscopic evaluation of adhesion formation was performed in each animal. The percentage of mesh area involved was scored (0% to 100%). At various time intervals animals were sacrificed and samples were obtained for light and scanning electron microscopy. RESULTS: Adhesions were already present on day 1, increased by day 7, and did not progress thereafter. Mesh surfaces free of adhesions were covered with a confluent mesothelial cell layer, first seen by scanning electron microscopy on day 5 and complete by day 7. CONCLUSIONS: Intraabdominal adhesions are best studied by sequential laparoscopy. Adhesions develop within 1 day of prosthesis placement. Adhesion-free surfaces are carpeted with mesothelial cells by day 7 and remain free thereafter, for duration of study.     

Hyaluronic acid/carboxymethylcellulose membrane barrier versus taurolidine for the prevention of adhesions to polypropylene mesh

BACKGROUND: A hyaluronic acid/carboxymethylcellulose (HA/CMC) membrane is an effective measure to prevent polypropylene mesh induced adhesions. We hypothesized that taurolidine 2% solution might be a cost-effective alternative to decrease adhesion formation. MATERIALS AND METHODS: Twenty-four rats were randomized into three groups: mesh alone (group 1), mesh + taurolidine 2% (group 2), and mesh + HA/CMC (group 3). Polypropylene mesh (4 cm2) was used to repair surgically induced anterior abdominal wall defects. Taurolidine 2%or a HA/CMC membrane was used as an antiadhesive measure. The animals were sacrificed 6 weeks after the operation, and adhesions to the prosthetic material were evaluated with digital image analysis. RESULTS: Group 1 (mesh alone) had the highest adhesion ratio (58.5 +/- 4.8%) compared with groups 2 and 3 (p < 0.05). The differences between groups 2 (mesh + taurolidine 2%; adhesion ratio 42.9 +/- 1.6%) and 3 (mesh + HA/CMC; adhesion ratio 40.3 +/- 3.0%) were not significant (p > 0.05). CONCLUSIONS: The animals of both treatment groups (2 and 3) had lower adhesion ratios compared with the controls (group 1). In particular, the HA/CMC membrane did not present with a superior antiadhesive effect compared with taurolidine. Therefore, taurolidine is a cost-effective alternative to HA/CMC membranes when a polypropylene mesh is used in direct contact with the abdominal viscera.     

Prevention of adhesion to prosthetic mesh: comparison of different barriers using an incisional hernia model

OBJECTIVE: To assess whether use of antiadhesive liquids or coatings could prevent adhesion formation to prosthetic mesh. SUMMARY BACKGROUND DATA: Incisional hernia repair frequently involves the use of prosthetic mesh. However, concern exists about development of adhesions between viscera and the mesh, predisposing to intestinal obstruction or enterocutaneous fistulas. METHODS: In 91 rats, a defect in the muscular abdominal wall was created, and mesh was fixed intraperitoneally to cover the defect. Rats were divided in five groups: polypropylene mesh only (control group), addition of Sepracoat or Icodextrin solution to polypropylene mesh, Sepramesh (polypropylene mesh with Seprafilm coating), and Parietex composite mesh (polyester mesh with collagen coating). Seven and 30 days postoperatively, adhesions were assessed and wound healing was studied by microscopy. RESULTS: Intraperitoneal placement of polypropylene mesh was followed by bowel adhesions to the mesh in 50% of the cases. A mean of 74% of the mesh surface was covered by adhesions after 7 days, and 48% after 30 days. Administration of Sepracoat or Icodextrin solution had no influence on adhesion formation. Coated meshes (Sepramesh and Parietex composite mesh) had no bowel adhesions. Sepramesh was associated with a significant reduction of the mesh surface covered by adhesions after 7 and 30 days. Infection was more prevalent with Parietex composite mesh, with concurrent increased mesh surface covered by adhesions after 30 days (78%). CONCLUSIONS: Sepramesh significantly reduced mesh surface covered by adhesions and prevented bowel adhesion to the mesh. Parietex composite mesh prevented bowel adhesions as well but increased infection rates in the current model.     

Fewer Intraperitoneal Adhesions With Use of Hyaluronic Acid–Carboxymethylcellulose Membrane: A Randomized Clinical Trial

OBJECTIVE: To assess the effectiveness of bioresorbable Seprafilm membrane in preventing abdominal adhesions in a prospective clinical randomized multicenter trial. SUMMARY BACKGROUND DATA: Adhesions occur frequently after abdominal operations and are a common cause of bowel obstruction, chronic abdominal pain, and infertility. To reduce the formation of adhesions, a mechanical barrier composed of hyaluronic acid and carboxymethylcellulose was developed, preventing adherence of tissues after abdominal surgery. METHODS: Between April 1996 and September 1998, all patients requiring a Hartmann procedure for sigmoid diverticulitis or obstructed rectosigmoid were randomized to either intraperitoneal placement of the antiadhesions membrane under the midline during laparotomy and in the pelvis, or as a control. Direct visual evaluation of the incidence and severity of adhesions was performed laparoscopically at second-stage surgery for restoration of the continuity of the colon. RESULTS: A total of 71 patients were randomized; of these, 42 could be evaluated. The incidence of adhesions did not differ significantly between the two groups, but the severity of adhesions was significantly reduced in the Seprafilm group both for the midline incision and for the pelvic area. Complications occurred in similar numbers in both groups. CONCLUSIONS: Seprafilm antiadhesions membrane appears effective in reducing the severity of postoperative adhesions after major abdominal surgery, although the incidence of adhesions was not diminished. The authors recommend using Seprafilm when relaparotomy or second-look intervention is planned. Long-term studies are needed to assess the cost-effectiveness and value of Seprafilm in preventing bowel obstruction, chronic abdominal pain, and infertility.     

Effective prevention of adhesions with hyaluronate

HYPOTHESIS: Hyaluronate sodium in the form of a bioresorbant membrane reduces the development of intra-abdominal adhesions frequently found after implantation of synthetic mesh in the context of surgical hernia repair. DESIGN: The effect of hyaluronate on the formation of adhesions was evaluated when applied laparoscopically as a bioresorbant membrane to protect the peritoneal surface of a synthetic mesh. SETTING: Experimental animal model. INTERVENTIONS: A peritoneal defect 5 cm in diameter was bilaterally created in the abdominal wall of each of 9 pigs by laparoscopy. A polypropylene mesh was fixed with clips onto these defects on both sides. In each of the animals, only on one side, the synthetic mesh was also covered by a hyaluronate membrane. MAIN OUTCOME MEASURES: The incidence and severity of adhesions (grade 0-4, where 0 indicates no adhesion; 1, filmy avascular adhesions; 2, vascular adhesions; 3, cordlike fibrous adhesions; and 4, plain fibrous adhesions) were determined after 45 days, comparing treated and untreated sides by autopsy results and histological features. RESULTS: Adhesions, mainly grades 3 and 4, occurred in 7 of the 9 animals in those meshes not covered by hyaluronate; 2 untreated animals did not develop adhesions. On the other hand, only 1 of the 9 animals developed adhesions (grade 2) at the mesh concealed by the hyaluronate membrane. CONCLUSIONS: The bioresorbant hyaluronate membrane significantly reduced the formation of peritoneal adhesions (1-sided sign test, P<.05) induced by the insertion of a polypropylene mesh, when compared with the contralateral implants not protected by hyaluronate. Thus, hyaluronate membranes are efficient for reducing the incidence of peritoneal adhesions.     

Bioabsorbable membrane prevents adhesions to polypropylene mesh in rats

Summary Most of mesh materials used in the repair of ventral hernias lead to considerable adhesion formation. In this study we evaluated the effects of a bioabsorbable membrane composed of carboxymethylcellulose and hyaluronic acid (HA membrane) on adhesion formation in the presence of a polypropylene mesh used to repair an incisional hernia model in rats. We repaired the defects either primarily or by polypropylene mesh. The abdominal surface of the repairs were then covered by a piece of HA membrane in randomly selected groups. The presence and grade of adhesions to the repair or mesh were recorded on the 8th day. Tissue specimens were analyzed for the extent of mesothelial and collagenous tissue growth and the degree of inflammation. Dense adhesions developed on all of the defects repaired by polypropylene mesh alone. The HA membrane decreased adhesions significantly when used as a supplement over the mesh (p < 0.01). Histopathologically, the HA membrane further retarded mesothelial growth over the mesh, and decreased vascular proliferation, inflammatory cell infiltration (p < 0.01) and collagen content of the wound (p < 0.05). In our rat model, the HA membrane prevented most of the adhesions that would be expected to occur on the mesh. It decreased the local infiltration of white cells and neovascularization. The HA membrane seemed to be a suitable physical barrier in rats against adhesion formation without compromising the wound healing. However, these findings need to be confirmed in humans.     

Two experimental models for generating abdominal adhesions

PURPOSE: To develop dependable rat models for generating abdominal adhesions that allow for objective evaluation and quantification. METHODS: Two adhesion models were devised and compared with conventional side-wall models involving cecal abrasion and peritoneal excision or abrasion. model T (tissue): removal of a 2.5 by 2.5 cm segment of full-thickness abdominal wall with overlying skin closure, exposing the viscera to subcutaneous tissue; model M (mesh): removal of an identical segment, replacing the defect with a 2.5 by 2.5 cm polypropylene mesh sewn to the cut edges. This exposed the viscera directly to the mesh surface. Seven days after operation, the character and extent of the adhesions were assessed at autopsy. Results were expressed as the percent area of subcutaneous tissue involved (T) or of mesh surface involved (M). For model T the percent involvement of the circumference of the defect edge was also recorded. The extent of omental and intestinal adhesions were evaluated individually. RESULTS: The classical side-wall models showed inconsistent patterns of adhesion formation and were difficult to evaluate. Every animal from both models M and T developed extensive adhesions. The mean coverage of mesh surface (M) was 93% and subcutaneous surface (T) 82%. In model T the mean involvement of the defect cut edge was 80% of the circumference. All model T animals had both intestinal and omental adhesions whereas there were no intestinal attachments in model M. Tenacity of adhesions did not differ significantly between animals or models. CONCLUSIONS: Adhesion models M and T are consistent, predictable, and dependable. They each yield extensive adhesion coverage to a defined site, which allow for standardized measurement.     

聚L-乳酸修饰的聚丙烯疝补片的研制及动物实验研究

目的将聚L-乳酸修饰的聚丙烯补片应用于动物实验,进一步验证补片的防粘连效果。方法聚L-乳酸修饰的聚丙烯补片置入腹腔并覆盖腹腔缺损,同时与聚丙烯补片为对照组,通过腹腔内粘连面积、粘连程度、组织病理学改变等检查了解补片粘连情况。结果单纯聚丙烯组术后死亡率高,剖腹探查发现补片表面与腹腔脏器发生直接粘连,粘连面积广泛,粘连程度重。聚L-乳酸修饰的聚丙烯组补片表面亦有粘连,主要集中在补片边缘粘连面积、程度较轻。结论聚L-乳酸修饰的聚丙烯平片是可行的,动物实验表明聚L-乳酸修饰的聚丙烯补片可以减少动物的腹腔内粘连。     

Prevention of adhesion formation with use of sodium hyaluronate-based bioresorbable membrane in a rat model of ventral hernia repair with polypropylene mesh--a randomized, controlled study

BACKGROUND: There is a high incidence of adhesions after ventral hernia repair with polypropylene mesh. Hyaluronic acid (HA)-based membrane has been shown to reduce the incidence of adhesions in the absence of prosthetic mesh. The purpose of this study was to determine the effect of HA membrane on the quantity and grade of adhesions and its effect on strength of repair after abdominal wall repair with polypropylene mesh. METHODS: In 61 rats a full-thickness abdominal wall defect (excluding skin) was created, and a section of small bowel was abraded. The animals were randomized, receiving either HA membrane to cover the viscera or no membrane. The fascial defect was repaired with polypropylene mesh. Equal numbers of animals from each group were killed at 4 weeks and 8 weeks after surgery. Adhesion severity and percentage of mesh surface covered with adhesions were estimated. Tensile strength between mesh and muscle from each animal was measured. Sections of the mesh-muscle interface were examined histologically and measured for thickness and graded for inflammation and fibrosis. RESULTS: Fifty-five animals survived until the end point. Animals in the HA membrane group had a significant reduction in (1) grade of adhesions between small bowel and mesh at 4 weeks (P = .009) and 8 weeks (P = .000001), (2) grade of adhesions between colon and mesh at 8 weeks (P = .00003), and (3) percentage of mesh covered with adhesions at 4 weeks (P = .01) and 8 weeks (P = .0000002). There was no difference between the 2 groups in tensile strength of the repairs, tissue thickness, degree of inflammation, or degree of fibrosis. CONCLUSIONS: HA membrane reduces the quantity and grade of adhesions of both small and large bowel, to polypropylene mesh in a rat model of ventral hernia repair, without compromising strength of the repair.     

Evaluation of sepramesh biosurgical composite in a rabbit hernia repair model

BACKGROUND: In cases such as incisional hernia repair, polypropylene mesh (PPM) can be exposed to the underlying viscera and cause adhesions to the mesh. In this study, a composite prosthesis that was designed to be less susceptible to adhesion formation than PPM was evaluated in a rabbit incisional hernia repair model. MATERIALS AND METHODS: A 5 x 7-cm full-thickness defect was created in the abdominal wall of 30 female New Zealand White rabbits. Ten animals each were repaired with PPM, Bard Composix (PP/ePTFE), or Sepramesh biosurgical composite-a polypropylene mesh coated on one side with chemically modified sodium hyaluronate and carboxymethylcellulose (HA/CMC). The animals were sacrificed after 28 days and the overall performance, including adhesion formation and tissue integration by histology and mechanical testing, was evaluated. RESULTS: In the Sepramesh group, there was a significant reduction in the percentage of surface area covered by adhesions and a significant increase in the percentage of animals with no adhesions compared to standard materials. The tissue integration strength and overall cellular response were similar in all groups. A partially remesothelialized peritoneal surface was often apparent overlying the Sepramesh implant. CONCLUSIONS: Sepramesh biosurgical composite effectively repaired abdominal wall defects in rabbits and reduced adhesion development to the mesh compared to the use of a PPM and a PP/ePTFE composite.     

Carboxymethylcellulose coated on visceral face of polypropylene mesh prevents adhesion without impairing wound healing in incisional hernia model in rats

Adhesions between viscera and mesh may result in intestinal obstruction and fistulae formation. Fewer adhesions with sodium carboxymethylcellulose (SCMC)-coated polypropylene mesh (PM) has been reported, but impaired wound healing was the major concern. We investigated the adhesion-prevention effect of SCMC in different concentrations, as coating only on visceral face of PM and its effects on wound healing. A full-thickness abdominal wall defect was created in 28 rats, which were then divided into three groups. In Group I (control), the defect was repaired with PM only; in Group II and Group III, the defects were repaired with 1% and 1.6% SCMC-coated-PM, respectively. All animals were sacrificed at day 30, and histological evaluation and adhesion scoring were done. Animals in the group in which 1.6% SCMC-coated PM was used developed significantly fewer adhesions compared with other animals (P=0.04). Histological evaluation using a semiquantitative scoring system showed no difference between the groups in fibrosis and inflammation scores (P=0.9 and P=0.3, respectively), and thickness of fibrosis on mesh was also similar (P=0.5). SCMC in 1.6% concentration as coating only on the visceral face of PM reduced the incidence and severity of adhesions without impairing wound healing.     

Assessment of adhesion formation to intra-abdominal polypropylene mesh and polytetrafluoroethylene mesh

BACKGROUND: The development of intra-abdominal adhesions, bowel obstruction, and enterocutaneous fistulas are potentially severe complications related to the intraperitoneal placement of prosthetic biomaterials. The purpose of this study was to determine the natural history of adhesion formation to polypropylene mesh and two types of polytetrafluoroethylene (ePTFE) mesh when placed intraperitoneally in a rabbit model that simulates laparoscopic ventral hernia repair. MATERIALS AND METHODS: Thirty New Zealand white rabbits were used for this study. A 10-cm midline incision was performed for intra-abdominal access and a 2 cm x 2 cm piece of mesh (n = 60) was sewn to an intact peritoneum on each side of the midline. Two types of ePTFE mesh (Dual Mesh and modified Dual Mesh, W.L. Gore & Assoc., Flagstaff, AZ) and polypropylene mesh were compared. The rate of adhesion formation was evaluated by direct visualization using microlaparoscopy (2-mm endoscope/trocar) at 7 days, 3 weeks, 9 weeks, and 16 weeks after mesh implantation. Adhesions to the prosthetic mesh were scored for extent (%) using the Modified Diamond Scale (0 = 0%, 1 50%). At necropsy the mesh was excised en bloc with the anterior abdominal wall for histological evaluation of mesothelial layer growth. RESULTS: The mean adhesion score for the polypropylene mesh was significantly greater (P < 0.05) than Dual Mesh at 9 weeks and 16 weeks and modified Dual Mesh at 7 days, 9 weeks, and 16 weeks. Fifty-five percent (n = 11) of the polypropylene mesh had adhesions to small intestine or omentum at necropsy compared to 30% (n = 6) of the Dual Mesh and 20% (n = 4) of the modified Dual Mesh. There was a significantly greater percentage (P < 0.003) of ePTFE mesh mesothelialized at explant (modified Dual Mesh 44.2%; Dual Mesh 55.8%) compared to the polypropylene mesh (12.9%). CONCLUSIONS: Serial microlaparoscopic evaluation of intraperitoneally implanted polypropylene mesh and ePTFE mesh in a rabbit model revealed a progression of adhesions to polypropylene mesh over a 16 week period. The pore size of mesh is critical in the development and maintenance of abdominal adhesions and tissue ingrowth. The macroporous polypropylene mesh promoted adhesion formation, while the microporous nature of the visceral side of the ePTFE served as a barrier to adhesions.     

Prevention of adhesion to prosthetic mesh in incisional ventral hernias: comparison of different barriers in an experimental model

BACKGROUND: The purpose of this study was to compare the intra-abdominal adhesion formation following ventral hernia repair by using oxidized regenerated cellulose (ORC) as a barrier underneath polypropylene mesh (PPM), and sodium hyaluronate/carboxymethylcellulose (HA/CMC)-coated PPM. METHODS: A ventral abdominal defect was created in each of 30 male rats which were divided into three groups. In group 1 (control) the defect was repaired with PPM; in group 2 ORC was laid over the viscera and the defect was repaired with PPM, and in group 3 HA/CMC-coated PPM was used for the repairing procedure. On the 28th postoperative day all the rats were sacrificed and adhesions were evaluated by laparoscopic exploration followed by histopathological examination. RESULTS: Animals treated with ORC and PPM, and HA/CMC-coated PPM showed significantly less adhesions than the control group (p = 0.026) and the intra-abdominal adhesions of the rats in these two groups were significantly easier to release than in the control group (p = 0.001). There was no significant difference between the ORC and HA/CMC groups. CONCLUSIONS: ORC used together with PPM is as effective as HA/CMC-coated PPM and ORC can be used as an adhesion barrier in intra-abdominal hernia repair.     

Comparison of Prosthetic Materials in Incisional Hernia Repair

Purpose Incisional hernias are not uncommon after abdominal surgery, but their repair is associated with a high risk of complications, including adhesions and recurrence. Many different types of meshes and adhesion barriers have been developed in an attempt to overcome these problems, some of which we have assessed in a rat model.Methods We made a full-thickness 1.5 × 2.5-cm abdominal wall defect in 30 Sprague-Dawley rats, which were divided into three groups according to the materials used for repair: 2 × 3-cm polypropylene mesh (group 1); expanded polytetrafluoroethylene (PTFE) with double-layer polypropylene mesh (group 2); or polypropylene mesh with oxidized cellulose adhesion barriers (group 3). We assessed adhesion formation, tensile strength, and histopathologic findings.Results The mean adhesion scores were 3.3, 1.3, and 0.7, in groups 1, 2, and 3, respectively (P < 0.001). The area involved by adhesions was significantly greater in group 1 than in groups 2 or 3 (P < 0.01, P < 0.05), but there was no significant difference between groups 2 and 3 (P < 0.05). The tensile strength in group 2 was less than that in groups 1 or 3 (P < 0.01, P < 0.05), but there was no significant difference between groups 1 and 3 (P > 0.05).Conclusion Although there was less adhesion formation with PTFE and oxidized cellulose, PTFE not only impaired the tensile strength, but also induced fibrosis and inflammation. An oxidized cellulose adhesion barrier can be safely used in incisional hernia repair to prevent intra-abdominal adhesions.