Use of a bioabsorbable mesh in midline laparotomy closure to prevent incisional hernia: randomized controlled trial.

INTRODUCTION: The objective was to assess the effectiveness and safety of a bioabsorbable mesh at the time of closure of a midline laparotomy for IH prevention. MATERIALS AND METHODS: A multicenter, randomized clinical trial including patients undergoing abdominal surgical procedures through a midline laparotomy incision was designed. In the group of mesh (n = 167) the incision was closed using a continuous polydioxanone suture (PDS) plus a bioabsorbable mesh. In the control group (n = 165) a continuous PDS single layer suture was only used. Patients were randomly assigned (1:1) to the two groups. The primary outcome was the incidence of IH at 6, 12 and 24 months. Assessment of IH was done using a CT scan. RESULTS: At 6 months, the rates of IH were 15.2% and 24.8% in the experimental and control groups, respectively (relative risk [RR] 0.66, 95% confidence interval [CI] 0.38-0.98, P = 0.042). At 12 months, the rate of IH continued to be significantly lower in the experimental group (21.4% vs. 33.1%, P = 0.033), but at 24 months, there were no significant differences between the study groups with a follow-up rate of only 37.5%. The number needed to treat (NNT) was 11 and 9 at 6 and 12 months, respectively. CONCLUSION: The bioabsorbable mesh significantly prevented IH during the first year. Not reliable conclusions can be drawn across the second year. This may suggest that the any of the closing technique assessed in this study would have a "palliative" transient effect for preventing IH in the long-term.

An ergonomic study of single-port versus multi-port laparoscopic mesh insertion for ventral hernia repair.

PURPOSE: To assess the mental effort and physical discomfort of placement of a prosthetic mesh into the abdominal cavity with single-incision laparoscopic surgery (SILS) or multi-port laparoscopic access for incisional ventral hernia repair. METHODS: A total of 10 surgeons with previous experience in conventional laparoscopic surgery performed four surgical tasks through a multi-port laparoscopic access and a SILS access in a porcine model during a first 4-hour working session and a second 2-hour working session. These tasks included (a) introduction of a prosthetic mesh for abdominal wall surgery, (b) manipulation of the mesh inside the abdomen, (c) manipulation of the laparoscopic instruments and (d) mesh insertion to the intraperitoneal abdominal wall and fixation with tackers. The level of mental effort was assessed with the Subjective Mental Effort Questionnaire (SMEQ) and physical discomfort with the Local Experienced Discomfort Scale (LED). RESULTS: Seventy percent were men, with a mean age of 45 years and a mean of 18 years of experience in practicing surgery. The SMEQ questionnaire showed a median physical effort of 24.4 (range 9-36.1) points for the multi-port laparoscopic access and 107.4 (range 74.7-128.4) for SILS (p < 0.01). Statistically significant differences between multi-port laparoscopic surgery and SILS were consistently demonstrated in all tasks as well as in both the 4-hour and 2-hour working sessions. The median (interquartile range) score of the LED scale was 12.5 (2-34.5) for tasks during multi-port laparoscopic surgery and 53.5 (29-89.2) for SILS (p < 0.001). All individual tasks were associated with a significantly higher physical effort for SILS than for conventional laparoscopic access, which were also independent of being performed during the 4-hour or 2-hour working periods. CONCLUSIONS: Placement and manipulation of a prosthetic mesh for incisional ventral hernia repair is more difficult with SILS than using multi-port laparoscopic access, independently of previous experience with standard laparoscopic techniques. This greater difficulty was observed both in terms of mental effort and physical discomfort. More experimental and clinical studies are needed to define specific training aspects and clinical advantages of incisional ventral hernia repair through SILS.

Improved surgical mesh integration into the rat abdominal wall with arginine administration.

Prosthetic meshes are used as the standard of care in abdominal wall hernia repair. However, hernia recurrences and side effects remain unsolved problems. The demand by health care providers for increasingly efficient and cost-effective surgery encourages the development of newer strategies to improve devices and outcomes. Here, we evaluated whether l-arginine administration was able to ameliorate long-term polypropylene prostheses incorporation into the abdominal wall of Sprague-Dawley rats. Meshes were placed on-lay and continuous l-arginine was administered. In vivo biocompatibility was studied at 7, 25 and 30 days post-implantation. Effectively, l-arginine administration in combination with mesh triggered subtle changes in ECM composition that impinged on critical biochemical and structural features. Lastly, tensile strength augmented and stiffness decreased over the control condition. This could help to restructure the mechanical load transfer from the implant to the brittle surrounding tissues, i.e., impact load and fatigue load associated with mechanical tensions could be distributed between the mesh and the restored tissue in a more balanced manner, and ultimately help to reduce the incidence of loosening, recurrences, and local wound complications. Since the newly formed tissue is more mechanically stable, this approach could eventually be introduced to human hernia repair.

Stress relaxation tests in polypropylene monofilament meshes used in the repair of abdominal walls.

The objective of this work has been to characterize stress relaxation in the polymer material on applying different levels of constant strain. The meshes were strained at values of 5.2%, 5.4% and 5.6% which are the values at which the mesh is strained in clinical use for the repair of abdominal walls. Laws have been obtained to model the viscoelastic behavior at different strains for this material. Finally, fracture studies were carried out by environmental scanning electron microscopy to determine the fracture mechanisms of these meshes. Besides, the implantation of the meshes was practised in two different layers of abdominal wall: the superficial or preaponeurotic layer and deep or preperitoneal layer, showing the neoformation of connective tissue on the mesh, which tended to be organized differently in each layer studied; more roughly and densely in the superficial layer than in the deep one.

Curcumin, a natural product present in turmeric, decreases tumor growth but does not behave as an anticachectic compound in a rat model.

Systemic administration of curcumin [1,7-bis(4-hydroxy-3-methoxyphenil)1,6-heptadiene-3,5-dione] (20 microg/kg body weight) for 6 consecutive days to rats bearing the highly cachectic Yoshida AH-130 ascites hepatoma resulted in an important inhibition of tumor growth (31% of total cell number). Interestingly, curcumin was also able to reduce (24%) in vitro tumor cell content at concentrations as low as 0.5 microM without promoting any apoptotic events. Although systemic administration of curcumin has previously been shown to facilitate muscle regeneration, administration of the compound to tumor-bearing rats did not result in any changes in muscle wasting, when compared with the non-treated tumor-bearing animals. Indeed, both the weight and protein content of the gastrocnemius muscle significantly decreased as a result of tumor growth and curcumin was unable to reverse this tendency. It is concluded that curcumin, in spite of having clear antitumoral effects, has little potential as an anticachectic drug in the tumor model used in the present study.

Early effects of exogenous arginine after the implantation of prosthetic material into the rat abdominal wall.

We have investigated the effects of high arginine (Arg) levels (7.5 mg/100 g body weight per hour) on the early integration of biocompatible mesh grafts into the rat abdominal wall. Studies were performed over implantation intervals of 6, 12, 24 or 48 hours (n=12, each). Arginine and related compounds were quantified in plasma, wound fluids and multiple tissues. Plasma nitric oxide (NO) production was studied. Strips were taken from the polypropylene fiber-host tissue interfaces (PTIs) for optical microscopic analysis and for immunohistochemical analysis using rat-specific antibodies against type I and type III collagens. Exogenous Arg was metabolized at the peripheral tissues but reliably reached the wound space. High amounts of Arg and ornithine (Orn) were detected in the specimens considered. No changes on citrulline (Ctr) or NO concentrations were observed, overall suggesting that, during the period studied, the arginase pathway predominated. The acute scarring response differed significantly in the two placements considered. The P-SS interface evidenced more extensive new tissue growth than the P-DS interface. Forty-eight hours after mesh implantation cellular infiltration, fibroblast proliferation, and mesh-surrounding angiogenesis were higher in the arginine-treated rats. Type III collagen staining was related to arginine treatment, being higher (++) in the study group. In conclusion, and independently of the site of mesh placement, supplemental Arg seemed to favorably affect early local collagen deposition. This could be potentially helpful to ameliorate the integration of biomaterials into the tissues and, consequently, to allow for the design of more selective therapeutic strategies to prevent hernia recurrence rates.