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.     

Laparoscopic transabdominal preperitoneal approach to place a polypropylene mesh on the abdominal wall: an experimental swine model of a technique that can be used for incisional hernia repair

Background The placement of intraabdominal polypropylene mesh entails risks of adhesions and fistulas that can be avoided by preperitoneal placement.Methods This comparative, open, experimental, prospective, randomized, and transversal study randomized pigs into two groups of 11 each for intraperitoneal (IPOM) or preperitoneal (TAPP) polypropylene mesh placement by laparoscopy. Diagnostic laparoscopy and tissue en-bloc resection was performed 28 days postoperatively for histopathologic analysis.Results The following data were observed for the two study groups: surgical time (IPOM: 35.73 ± 4.22 min; TAPP: 58.09 ± 6.28 min; p = <0.0001); adhesions (IPOM: 81.81%; TAPP: 27.27%; p = 0.032), grade III for IPOM and grade II for TAPP (p = 0.001); and interloop adhesions (IPOM: 81.81%; TAPP: 9.09%; p = 0.003). No fistulas were found in either group. The TAPP procedure showed better integration of mesh, without lesion to abdominal organs. Two complications, occurred with IPOM, and one with TAPP (p = 1.0, not significant).Conclusions The perperitoneal technique requires more time, but has fewer adhesions and less intraabdominal inflammatory response. It is a feasible technique that may diminish risks in the laparoscopic treatment of incisional hernias with polypropylene mesh.     

Major mesh-related complications following hernia repair

Mesh material affects complications following hernia repair. Medical device reports on the use of surgical mesh for hernia repair were reviewed from the Food and Drug Administration’s (FDA) Manufacturer User Facility Device Experience Database from January 1996 to September 2004. We analyzed 252 adverse event reports related to the use of surgical mesh for hernia repair. Adverse events included infection (42%, 107 reports), mechanical failure (18%, 46), pain (9%, 23), reaction (8%, 20), intestinal complications (7%, 18), adhesions (6%, 14), seroma (4%, 9), erosion (2%, 6), and other (4%, 9). Compared to all other mesh types, Sepra/polypropylene mesh had more mechanical failures (80 vs 14%, p < 0.05), biomaterial mesh had more reactions (57 vs 7%, p < 0.05), polytetrafluoroethylene (PTFE)/polypropylene mesh had more intestinal complications (14 vs 7%, p < 0.05), and PTFE mesh tended to have more infections (75 vs 41% all other, p = 0.07). Death occurred in 2% (5). We conclude that specific mesh materials are related to specific complications.     

Comparison of Adhesive Properties of Five Different Prosthetic Materials Used in Hernioplasty

This experimental study was designed to assess and to compare intra-abdominal adhesions following the use of five commercially available prosthetic mesh grafts in the repair if abdominal wall defects. Sixty Wistar albino rats were randomly divided into six groups (n = 10). A 2 × 1 cm defect at abdominal wall was created and defects were closed either primarily or with one of the following prosthetic mesh grafts: monofilament polypropylene, polytetrafluoroethylene, sodium hyaluronate/carboxymethylcellulose-coated polypropylene, polypropylene/polyglactin 910 composite, or resorbable hydrophilic collagen-coated multifiber polyester. The severity of adhesions was graded, tensile strengths of adhesions were measured, and histopathological grades of inflammation and fibrosis were evaluated. Polypropylene mesh resulted in more adhesion formation in comparison to primary repair and other grafts used in this study, except polypropylene/polyglactin 910 composite mesh. In addition, the highest tensile strength of omental adhesions was detected in the polypropylene group (χ² = 26.249; p =. 0001). Polyester composite mesh caused the least adhesion formation among the groups. Sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polyester composite meshes revealed the highest fibrosis scores (χ² = 50.776; p =. 0001). The highest inflammatory activity was detected in the polytetrafluoroethylene mesh group (χ² = 16.564; p =. 005). Thus, sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polytetrafluoroethylene meshes following polyester composite mesh were the minimal adhesion-forming grafts in this study. Disadvantages of the polytetrafluoroethylene mesh were lower fibrotic activity and higher inflammatory reaction to the graft.     

Cine magnetic resonance imaging vs high-resolution ultrasonography for detection of adhesions after laparoscopic and open incisional hernia repair: a matched pair pilot analysis

Background Intraabdominal adhesions represent nonspecific complications before or after laparoscopic or open incisional hernia repair. The objective of this matched control pilot study was to display long-term adhesions noninvasively by applying functional cine magnetic resonance (MR) imaging, as compared with applying high-resolution ultrasonography (US). Methods The study group, composed of 17 consecutive patients (12 men and 5 women; mean age, 52 years), underwent laparoscopic intraperitoneal onlay mesh repair using expanded polytetrafluoroethylene (ePTFE) mesh. Their mean body mass index was 30 kg/m², and the size of the hernia was 95 cm². Another group, matched for age, gender, and type of hernia, was subjected to open abdominal wall repair using the preperitoneal sublay technique with a large-pore, low-weight polypropylene mesh. For cine MR imaging (1.5 T), section-by-section dynamic depiction of induced visceral slide throughout the entire abdomen was achieved by applying transverse or sagittal true fast imaging with steady-state precession sequences. The location and type of adhesions were compared with high-resolution ultrasonography using nine segments of the abdominal map. Results The patients subjected to laparoscopic and open incisional hernia repair were examined 16 and 28 months after surgery. The findings showed functional cine MR imaging as superior to high-resolution ultrasonography for assessing the amount of intraabdominal adhesions (n = 53 vs n = 3; p < 0.01). Most frequently, adhesions were seen between small bowel loops and the abdominal wall (n = 22), followed by bowel-to-bowel adhesions (n = 19; p < 0.05). However, adhesions between small bowel loops and the abdominal wall occurred more frequently after open mesh repair (p < 0.05). Furthermore, a strong correlation was observed between patient complaints and findings with cine MR imaging (p < 0.05). Maximum pain correlated significantly with the region of the most distinctive adhesions (p < 0.05). Conclusions Functional cine MR imaging represents a reliable noninvasive technique for detecting long-term adhesions after open and laparoscopic incisional hernia repair. The study results suggest that this approach has distinct advantages over high-resolution ultrasonography.     

In vivo study of meshes implanted over the inguinal ring and external iliac vessels in uncastrated pigs

Background: The effects of placing a prosthesis directly on the internal inguinal ring and external iliac vessels in inguinal hernia repair are unknown. We compared tissue responses to five prostheses implanted in this position in uncastrated male pigs. Methods: Three types of polypropylene and two types of expanded polytetrafluoroethylene (ePTFE) mesh were implanted in 20 pigs (n= 8 for each prosthesis type). Specimens of the implants and surrounding tissue were obtained 30 and 90 days after implantation and assessed histologically. Results: The polypropylene implants had more adhesions, more surface area covered by adhesions, and more tenacious adhesions than did the ePTFE implants. Perivascular cuffing was observed in eight polypropylene and one ePTFE specimen; ossification, necrosis, and testicular venous congestion were seen in polypropylene specimens. Conclusions: Abnormal healing processes after implantation of polypropylene mesh may increase complications of the transabdominal preperitoneal and total extraperitoneal approaches in laparoscopic inguinal hernia repair, whereas the minimal response to ePTFE meshes may make them safer for use in the preperitoneal space. Received: 2 April 1997/Accepted: 8 August 1997     

Inhibition of Intra-Abdominal Adhesions: A Comparison of Hemaseel APR and Cryoprecipitate Fibrin Glue

Our previous studies demonstrated fibrin glue (FG) prepared from cryoprecipitate (cryo) inhibits intra-abdominal adhesions in rats. A new FG, Hemaseel APR, is Food and Drug Administration (FDA) approved for hemostasis during cardiac surgery and splenic trauma. This study was undertaken to determine if Hemaseel FG prevents intra-abdominal adhesions, and to compare it to cryo FG. Forty-five rats underwent laparotomy. Bilateral peritoneal-muscular defects were created. Polypropylene mesh was sewn into each defect with a running silk suture. The bowel was abraded with gauze. The rats were then randomized to mesh covered with Hemaseel FG, cryo FG, or control. On postoperative day 7, the severity of adhesions were graded by percentage of mesh covered by adhesion (0-100%) and degree of adhesion (0-3). The mean percentage of mesh covered by adhesion was 9% for Hemaseel FG, 43% for cryo FG (p = .005), and 65% for the controls (p &lt; .0001). The mean density adhesion score was 0.5 for Hemaseel FG, 1.2 for cryo FG (p = .04), and 2.1 for the controls (p &lt; .0001). In the Hemaseel FG group, 77% of patches had no adhesions, compared with 37% in the cryo FG group (p = .004) and 13% in the controls (p &lt; .0001). Thus, Hemaseel FG significantly decreases intra-abdominal adhesions, and is more effective than cryo FG.     

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.     

Mesh repair for postoperative wound dehiscence in the presence of infection: is absorbable mesh safer than non-absorbable mesh?

Objective In patients with postoperative wound dehiscence in the presence of infection, extensive visceral oedema often necessitates mechanical containment of bowel. Prosthetic mesh is often used for this purpose. The aim of the present study was to assess the safety of the use of non-absorbable and absorbable meshes for this purpose. Method All patients that had undergone mesh repair of abdominal wound dehiscence between January 1988 and January 1998 in the presence of intra-abdominal infection were included in a retrospective cohort study. All surviving patients had physical follow-up in February 2001. Result Eighteen patients were included in the study. Meshes consisted of polyglactin (n = 6), polypropylene (n = 8), polyester (n = 1), or a combination of a polypropylene mesh with a polyglactin mesh on the visceral side (n = 3). All patients developed complications, consisting mainly of mesh infection (77%), intra-abdominal abscess (17%), enterocutaneous fistula (17%), or mesh migration through the bowel (11%). Mesh removal was necessary in eight patients (44%). Within four months postoperatively, six patients (33%) had died because of progressive abdominal sepsis. The incidence of progressive abdominal sepsis was significantly higher in the group with absorbable polyglactin mesh than in the group with nonabsorbable mesh (67 vs. 11%, p = 0.02) After a mean follow-up of 49 months, 63% of the surviving patients had developed incisional hernia. Absorbable meshes did not yield better outcomes than nonabsorbable meshes in terms of complications and mortality rate. Conclusion Synthetic graft placement in the presence of intra-abdominal infection has a high risk of complications, regardless of whether absorbable (polyglactin) or non-absorbable mesh material (polypropylene or polyester) is used, and should be avoided if possible.     

Primary incisional hernia repair with or without polypropylene mesh: a report on 384 patients with 5-year follow-up

Background and aim Several studies have claimed that mesh repair of incisional hernia lowers recurrence rates when compared to suture repair. We investigated the relative effectiveness of mesh and suture repair in a large homogeneous cohort of patients with primary incisional hernia.Patients and methods In a retrospective single-centre cohort study, a total of 446 consecutive patients were identified, of whom 86% could be followed up. Mean length of follow-up was 5 years. In 79 patients (22%), we implanted a mesh, usually polypropylene (Prolene).Results Compared to suture repair, mesh repair prolonged operating time by over 30 min and caused seroma in 12.7% of the patients (p<0.001). Only 4 of the 79 patients with mesh repair developed recurrence, compared to 55 of the 305 patients with suture repair (5 vs 18%, p=0.02 by log-rank test). In multivariate Cox regression, recurrence rates were fourfold higher after suture than after mesh repair (p=0.02). Interestingly, old age was associated with a decreased susceptibility for recurrence (p=0.01).Conclusion Our data confirms the long-term effectiveness of mesh repair under routine conditions. Suture repair should be restricted to small hernias in patients free of known risk factors.     

A comparative study of adhesion formation and abdominal wall ingrowth after laparoscopic ventral hernia repair in a porcine model using multiple types of mesh

Background The ideal mesh for laparoscopic ventral hernia repair is not yet identified.Methods We laparoscopically placed polypropylene (PPM), expanded polytetrafluoroethylene (ePTFE), and polyester with antiadhesive collagen layer (PCO) in eight pigs using sutures and tacks for fixation. After 28-day survival, we compared adhesion formation, fibrous ingrowth, and shrinkage among the types of mesh.Results Mean area of adhesions to PCO (8.25%) was less than that to ePTFE (57.14%, p < 0.001) or PPM (79.38%, p < 0.001). Adhesions peel strength was less for PCO (2.3 N) than for PPM (16.1 N, p < 0.001) or ePTFE (8.8 N, p = 0.02). Peel strength of mesh from the abdominal wall was less for ePTFE (1.3 N/cm of mesh width) than for PCO (2.8 N/cm, p = 0.001) or PPM (2.1 N/cm, p = 0.05). ePTFE area (94.4 cm²) was less than that for PCO (118.6 cm², p < 0.001) or PPM (140.7 cm², p < 0.02).Conclusion PCO had fewer and less severe adhesions than ePTFE or PPM while facilitating excellent ingrowth of the adjacent parietal tissue.     

Open Rives-Stoppa ventral hernia repair made simple and successful but not for everyone

Background: The Rives-Stoppa (RS) repair of ventral incisional hernias (VIHR) is technically difficult. It involves the retromuscular placement of mesh anterior to the posterior fascia and the primary closure of the anterior fascia. Recurrence rates are 0–8%. We proposed that the operation could be done with equal success by placing the mesh in an intraperitoneal position and primarily closing the fascia anterior to the mesh. Methods: 81 patients who had undergone an open RS-VIHR with intraperitoneal mesh were evaluated for hernia recurrence and factors associated with recurrence. Results: 55 women and 26 men (mean BMI 38±9) underwent RS-VIHR (mean age 49±11 years). Of these patients, 44 (54%) had a prior VIHR, 30 (37%) had an incarcerated hernia and 34 (42%) had multiple fascial defects. PTFE was used in 83% and Prolene in 12%. Average LOS was 5.8±12 days. All received perioperative intravenous antibiotics and 28% were discharged on oral antibiotics. Follow-up averaged 30±24 months. Recurrent VIH developed in 12/81 (15%), with three occurring after removal of infected mesh and one after a laparotomy. Excluding these four, the recurrence rate was 10%. There was no correlation between hernia recurrence and age, BMI, hernia size, number of prior repairs, or LOS (t-test p>0.05). Hernia recurrence did not correlate with gender, prior peritoneal contamination, incarceration, multiple defects, adhesions, mesh type, oral antibiotics, cardiac disease, diabetes, tobacco use, or seroma (X² p>0.05). Those with a wound infection and/or abscess formation had a significantly higher recurrent hernia rate (60% vs. 8%, X² p<0.001). Patients with pulmonary disease had a significantly higher recurrence rate (50% vs. 12%, X² p=0.01). Conclusions: RS-VIHR with intraperitoneal mesh is a successful and less technically challenging method of repair than prior modifications. Aggressive efforts to identify infection and treat early may prevent abscess formation and subsequent recurrent hernia. Patients with chronic pulmonary disease have an unacceptably high recurrence rate and should not be considered as candidates for elective RS-VIHR.Presented at the Seventh Annual Scientific Meeting of the American Hernia Society, Orlando, FL, 24–28 February 2004     

Evaluation of adhesion formation, mesh fixation strength, and hydroxyproline content after intraabdominal placement of polytetrafluoroethylene mesh secured using titanium spiral tacks, nitinol anchors, and polypropylene suture or polyglactin 910 suture

Background The purpose of this study is to evaluate fixation methods for polytetrafluoroethylene (ePTFE) mesh with an in vivo model of laparoscopic ventral hernia repair.Methods In 40 New Zealand white rabbits, a 4 × 4-cm ePTFE mesh (n = 80, two per animal) was attached to an intact peritoneum with polyglactin 910 (PG 910) (n = 20) or polypropylene (PP) (n = 20) suture, titanium spiral tacks (TS) (n = 20), or nitinol anchors (NA) (n = 20). Mesh was harvested at 8 and 16 weeks for fixation strength testing, adhesion assessment, and collagen (hydroxyproline) content. Fixation strength on day 0 was determined with mesh attached to harvested abdominal wall. Statistical significance was determined as p < 0.05.Results There was no difference in fixation strength between PP (39.1 N) and PG 910 (40.0 N) sutures at time zero. At week 8, PP (25.7 N) was significantly stronger (p < 0.05) than PG 910 (11.4 N) suture, but not at week 16. The fixation strength of TS and NA (day 0, 15.4 vs 7.4 N; week 8, 17.5 vs 15.3 N; week 16, 19.1 vs 13.8 N) was not significantly different. Fixation with PP suture was significantly (p < 0.05) stronger than that with TS and NA at day 0 (39.1, 15.4, and 7.4 N, respectively) but not at weeks 8 or 16. The fixation strength of suture decreased significantly (p < 0.05) from day 0 to week 16 (PP: day 0 = 39.1 N, week 8 = 25.7 N, week 16 = 21.4 N; PG 910: day 0 = 40.0 N, week 8 = 11.4 N, week 16 = 12.8 N). The fixation strength of NA and TS did not change significantly (NA: day 0 = 7.4 N, week 8 = 15.3 N, week 16 = 13.8 N; TS: week 0 = 15.4 N, week 8 = 17.5 N, week 16 = 19.1 N). There were no differences in adhesion area based on fixation device used; however, there were more (p < 0.05) mesh samples using NA with adhesions compared to TS and adhesion tenacity was greater (p < 0.05) compared to that of TS, PP, and PG. Hydroxyproline content at weeks 8 and 16 was similar for all fixation devices.Conclusions The initial fixation strength for nonabsorbable suture is significantly greater than that of the metallic fixation devices, but after 8 weeks there is no difference. Laparoscopic ventral hernia repair without transabdominal suture fixation may be predisposed to acute failure. The metallic devices have similar fixation strength, although the incidence of adhesions and tenacity of adhesions appear to be greater with the nitinol anchors. Since these devices have similar fixation strengths and most likely provide adequate supplementation to transabdominal sutures for mesh fixation after laparoscopic ventral hernia repair, their use should be based on other factors, such as their propensity for adhesions, ease of application, and cost.Paper presented at the annual meeting of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), Denver, Colorado, USA, March 31–April 3, 2004     

Does Presoaking Synthetic Mesh in Antibiotic Solution Reduce Mesh Infections? An Experimental Study

Background

Prosthetic mesh infection is one of the most challenging complications after hernia repair. We evaluate the efficacy of soaking mesh in antibiotics to prevent prosthetic infection in an animal model of clean–contaminated ventral hernia repair (VHR).

Material and Methods

Rats underwent an acute VHR with one of four synthetic meshes (composite multifilament polyester (Parietex PCO), multifilament polyester (Parietex TET), composite monofilament polypropylene (Ventralight), or monofilament polypropylene (SoftMesh)). Prior to implantation, mesh was soaked in saline or 10 mg/ml of vancomycin for 15 min. Following implantation, meshes were contaminated with 10⁴ CFU of methicillin-resistant Staphylococcus aureus (MRSA) bacteria. Thirty days after implantation, mesh samples were cultured and evaluated under scanning electron microscope for biofilm formation.

Results

Presoaking meshes significantly improves bacterial clearance in composite meshes and multifilament polyester mesh. MRSA clearance was as follows for all meshes (saline-soaked vs. vanco-soaked): Parietex PCO (0 vs. 56 %, p?=?0.006), Parietex TET (0 vs. 50 %, p?=?0.01), Ventralight (20 vs. 78 %, p?=?0.012), and SoftMesh (70 vs. 80 %, p?=?0.6). MRSA biofilm formation was consistent with bacterial growth.

Conclusion

Presoaking multifilament and composite mesh in vancomycin solution reduces MRSA bacterial growth. Its implementation may reduce the risk of mesh infection in clean–contaminated cases, although further investigation with human trials should be performed.     

Comparison of two composite meshes using two fixation devices in a porcine laparoscopic ventral hernia repair model

Introduction Laparoscopic ventral hernia repair uses tacks to secure mesh. The mesh is designed to maximize tissue ingrowth while minimizing adhesions. We hypothesized: (1) a collagen-coated polyester mesh (PCO) will form fewer adhesions than an ePTFE-polypropylene composite (BC) and (2) absorbable tacks are equivalent to metal tacks.Methods In a porcine model of adhesion formation, three pieces of 10×15-cm mesh were placed on the anterior abdominal wall. PCO was secured with absorbable (PLA) or metal tacks (PT), BC with PT. At 28 days, adhesion formation, abdominal-wall adherence, and tissue ingrowth were analyzed.Results PCO induced fewer adhesions (14.5% vs 53.4%, P=0.007). On an adhesion scale (0–5), BC scored 3.6 vs 1.75 for PCO (P<0.03). There was no difference in adhesion strength, tack adhesions, or abdominal-wall peel force. Histology showed equal ingrowth.Conclusions PCO induces fewer adhesions than BC. There is no difference in the ingrowth of the two mesh types. The PLA achieves equivalent mesh incorporation to the PT.This work was presented at the meeting of the American Hernia Society, Orlando, Fla. USA, in February 2004     

Five-year outcome of laparoscopic and Lichtenstein hernioplasties

Background: Laparoscopic hernia repair has been proved superior to open repairs in terms of short-term results, but long-term results of laparoscopic and open mesh repairs have been lacking until recently. Methods: A total of 123 patients were randomly allocated to two treatment groups comparing laparoscopic and Lichtenstein hernioplasties in three separate trials. The first and second trials compared small and large mesh used in transabdominal preperitoneal repairs, and the third study compared totally extraperitoneal hernioplasty with the Lichtenstein operation. A 5-year follow-up visit was scheduled to assess recurrencies, symptoms, and patient satisfaction. Results: For the follow up evaluation, 121 (98.4%) of the patients were reached. There were five hernia recurrences in the laparoscopic group (small mesh) and two in the Lichtenstein group (difference, 5%; 95% confidence interval, –4–13%; p = 0.3). One patient who underwent the transabdominal preperitoneal polypropylene procedure underwent reoperation 3 years later because of dense small bowel adhesions at the inguinal surgical site. Chronic groin pain was more common after open operation (0 vs 4) patients (difference 7%; confidence interval, –0.4–16%; p = 0.04). Ten patients (16%) in the laparoscopic group and 12 (20%) in the open group reported discomfort or pain at the surgical site. Conclusions: Both laparoscopic and Lichtenstein hernioplasties have a low risk for hernia recurrence if proper mesh size is used. The patients who undergo hernioplasty with open mesh hernioplasty seem to experience chronic symptoms and pain more often than those managed with the laparoscopic procedure.     

Adhesion formation is reduced after laparoscopic surgery

Background: Adhesion formation after abdominal operations causes significant morbidity. Methods: Adhesion formation in pigs was compared after placement of prosthetic mesh during celiotomy (group 1), laparoscopy with large incision (group 2), and laparoscopy (group 3). After peritoneum was excised, polypropylene mesh was fixed to the abdominal wall, then to the opposite abdominal wall in the preperitoneal space followed by peritoneal closure. Adhesion area, grade, and vascularity were measured. Results: More adhesions (p < 0.02) covered intraperitoneal mesh (7.57 ± 1.89 cm²) than covered reperitonealized mesh (2.16 ± 1.13 cm²), and adhesion grade was significantly greater (p < 0.02). Adhesion areas were significantly greater in groups 1 and 2 than in group 3 (p= 0.001 and 0.03, respectively). Adhesion grade was significantly greater in groups 1 and 2 than in group 3 (p= 0.02 and p= 0.04, respectively). Groups 1 and 2 had more vascular adhesions than group 3 (p < 0.01 and p= 0.02, respectively) Conclusions: A foreign body within the peritoneum stimulates more numerous and denser adhesions. Tissue trauma distant from the site of adhesions increases their formation. A major advantage of laparoscopic surgery is decreased adhesion formation. Received: 23 January 1998/Accepted: 10 March 1998     

The susceptibility of prosthetic biomaterials to infection

Background Despite the use of a sterile technique and the administration of prophylactic antibiotics during surgical procedures, mesh infection continues to complicate the use of biomaterials. The purpose of this study was to compare the susceptibility to infection of prosthetic biomaterials in a live-animal model.Methods The following seven prosthetic mesh biomaterials were used in this study. Expanded polytetrafluoroethylene (ePTFE) with silver/chlorhexidine (DM+), ePTFE (DM), porcine intestinal submucosa (S), polypropylene (M), ePTFE/polypropylene (X), hyaluronate/carboxymethylcellulose/polypropylene (SM), and human acellular dermal matrix (A). Lewis rats (n = 108) underwent creation of a single ventral hernia; 105 of them were repaired with a different mesh (2-cm² piece). Twelve pieces of each mesh were inoculated at the time of hernia repair with 10⁸ Staphylococcus aureus (n = 84). Three pieces of each mesh were placed without bacterial inoculation (n = 21). In three animals, no mesh was placed; instead, the peritoneum of the hernia defect was inoculated (n = 3). After 5 days, the animals were killed and the mesh was explanted (peritoneum for the nonmesh control). The mesh was vortex-washed and incubated in tryptic soy broth. Bacterial counts were determined using serial dilutions and spot plates and quantified in colony-forming units (CFU) per square centimeter of mesh present in the vortex wash fluid (wash count) and the soy broth (broth count). Data are presented as the mean log₁₀, with analysis of variance (ANOVA) and Tukey’s test used to determine significance (p < 0.05).Results The DM+ material had no detectable live bacteria in the wash or broth counts in 10 of 12 tested samples (p = 0.05). Of the samples that showed bacterial growth, the peritoneum control group had a lower wash count than A (p = 0.05) and the lowest broth count of all the materials except for DM+ (p = 0.05). In addition, SM had a significantly lower wash count than A (p = 0.05), with no broth count difference. In regard to wash and broth counts, DM, M, X, SM, S, and A were no different (p = NS).Conclusions The DM+ material was the least susceptible to infection. Impregnation with silver/chlorhexidine killed the inoculated bacteria, preventing their proliferation on the mesh surface. Other than DM+, native peritoneal tissue appears to be the least susceptible to infection. Silver/chlorhexidine appears to be an effective bactericidal agent for use with mesh biomaterials.Presented at the annual meeting of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), Denver, CO, USA, 31 March-3 April 2004     

Omentum prevents intestinal adhesions to mesh graft in abdominal infections and serosal defects

Background Many studies have evaluated the use of grafts in the reconstruction of abdominal wall defects. In this study, the effects resulting from the presence or absence of the omentum were evaluated in the setting of infection or serosal defects in the formation of adhesions in abdominal closures using mesh grafts. Methods For this study, 60 Wistar albino rats were divided into six groups. A circular 3.79-cm² fascioperitoneal defect was created. After group-specific procedures, defects were reconstructed using polypropylene mesh grafts. In group C (control group), only a mesh graft recontruction was performed, whereas group O (O for omentectomy) underwent an omentectomy plus mesh closure. In group SD (serosal defect group), the cecum was abrased with a brush before mesh closure. Group SDO underwent cecal abrasion plus an omentectomy. In group I (infection group), the intraabdominal space was filled with 1 ml of solution containing 100,000 colony-forming units (CFUs) of Escherichia coli per milliliter. Group IO received the same same amount of E. coli solution plus an omentectomy before mesh closure. After 28 days, the groups were evaluated by intraabdominal and blood cultures, grading of intraabdominal adhesions, graft–organ adhesions, proportion of adhesions to graft size, and histopathologic studies. The results were statistically evaluated using one-way variant analysis and Scheffe’s and Fisher’s definite chi-square tests. Results For the groups in which the greater omentum was preserved, intestinal adhesions to the graft surface were less frequently observed, especially in cases with intraabdominal infections and serosal defects (p < 0.05). Conclusions Preservation of the greater omentum reduces the formation of intestinal adhesions, especially in cases with underlying infections and serosal defects in abdominal closures using mesh grafts. This could be beneficial in related clinical situations in lowering the rate of intestinal fistulas, erosions, and obstructions that can be attributed to the formation of adhesions.     

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.