|
Research purposes. Establish animal models of medical polypropylene mesh abdominal subcutaneous tissue implanted in rabbits and observed for 30 days implantation of polypropylene mesh, 90 days and 180 days after polypropylene mesh - muscle tissue biomechanical behavior and polypropylene mesh shrink invariant. . Pathology research methods, biocompatibility evaluation in the light microscope observed for 30 days, 90 days and 180 days after polypropylene mesh signs of pathological changes caused by the body's inflammatory response and connective tissue deposition. By scanning electron microscopy to further observe the a polypropylene mesh surface and integration with connective tissue ultrastructure representation. Materials and Methods New Zealand female rabbits (clean) 8 random number table is divided into four groups, each with two rabbit abdominal midline divided into 12 regions, each side of the six regions. 10 regional surgical separation of skin, subcutaneous tissue, placed medical polypropylene the mesh (prolift material mesh), two sham surgery without placing polypropylene mesh as the control area. First, 10% chloral hydrate intraperitoneal anesthesia will cut 10mm × 40mm disinfection polypropylene mesh implanted in rabbit abdominal subcutaneous, each on each side of the abdominal subcutaneous implantation of a total of 10 implanted in five, four groups of plant into 80, and the other two control region separated only subcutaneous tissue, and a polypropylene mesh is not implanted, arranging sacrificed rabbits control area in each group of 16 sham-operation area, as a control group. The installments were sacrificed rabbits anatomical cut 30 days (B group), 90 days (C group) and 180 days (D) group polypropylene mesh and its surrounding muscles, subcutaneous tissue, and cut the muscles of the phases of the control group - subcutaneous tissue (A group). B group, C group, D group from each of the 15 polypropylene mesh - muscle tissue is trimmed to the size of 10mm × 40mm line polypropylene mesh contraction variable degrees of determination: to measure the the polypropylene mesh length and width of the different groups with a vernier caliper value to calculate the area of ??polypropylene mesh preoperative polypropylene mesh area (400mm2) as the base, the area shrinkage of the polypropylene mesh in the different periods of postoperative variable degree (%) were calculated. Area reduction becomes% = [(preoperative polypropylene mesh area - postoperative polypropylene mesh area mm2) / preoperative polypropylene mesh area mm2)] × 100%. Mechanical testing system followed by MTS respectively tensile, stress relaxation and creep experiment, and calculating the stress σ respectively 0.2MPa 0.3MPa when the modulus of elasticity, for statistical analysis, draw stress relaxation, creep normalized curve. Select group B, group C and group D polypropylene mesh in the same area - muscle tissue samples 5 each, divided into two parts, half made into paraffin-embedded specimens slice with an optical microscope for histopathological evaluation to scar board formation, inflammation and tissue network the hole situation of 1-4 (1 = normal tissue, 4 = severe inflammatory reaction) evaluation of results; another half using scanning electron microscopy of the tissue surrounding the mesh. All measurement data are used as mean ± standard deviation (x ± s), the application spss16.0 software for statistical analysis of the data, pairwise comparison between groups using one-way ANOVA test level of P = 0.05. Stress relaxation response polypropylene mesh - organizing force stress reduction. This study shows that the polypropylene mesh implanted in the body longer, the polypropylene mesh - muscle tissue by force remaining after the greater the stress. Groups sample force can quickly in a short period of time within Abatement stress, group B, group stress relaxation normalized curve is consistent, instant stress abatement rate than Group A, C group; groups A, B group, C group D group residual stress were 0.21 ± 0.05MPa and 0.22 ± 0.05MPa, 0.03MPa 0.15 ± 0.27 ± 0.02MPa difference between any two groups was statistically significant (P lt; 0.05), where D group residual stress maximum, and the other three groups the difference was statistically significant (P lt; 0.05), C minimum residual stress, compared with the other three groups the difference was statistically significant (P lt; 0.05), group A and B compared the difference was not statistically significance (P gt; 0.05). Creep represents the dimensional stability of the polypropylene mesh - Organization force. This study shows that the polypropylene mesh implanted in the body longer, the more stable the size polypropylene mesh - muscle tissue force. When the stress remain at 0.6MPa level, each set of samples the slow deformation (t gt; 50s), B group, C group, D group are basically the same creep curves, creep speed, the relative strain changes were less than A group, wherein the group D is least prone to creep. 3 elastic modulus on behalf of the polypropylene mesh - the elasticity of the tissue. This study suggests that the polypropylene mesh implanted in the body longer, polypropylene mesh - muscle tissue elastic at low stress level when the worse. Stress σ 0.2MPa level of group A, group B, group C, D group elastic modulus were 0.54 ± 0.20,0.76 ± 0.16, 1.28 ± 0.35,1.79 ± 0.59, group A and group B, the elastic modulus difference was not statistically significant (P gt; 0.05), group C and group D elastic modulus greater than in group A and group B, the difference was statistically significant (P lt; 0.05), but the contrast between the C and D group difference was not statistically significant (P gt; 0.05); stress σ 0.3MPa level of group A, group B, group C, D group elastic modulus were 0.61 ± 0.16,0.96 ± 0.20,1.59 ± 0.25,2.10 ± 0.59, Group D elastic modulus, and the differences were statistically significant (P lt; 0.05) compared to the other three groups, the C group elastic modulus compared with group A, group B, the difference had statistical significance (P lt; 0.05) The modulus of elasticity of the group B than group A, but the difference was not statistically significant (P gt; 0.05). 4 polypropylene mesh contraction invariant increases with time. Group B, group C, D group polypropylene mesh contraction invariant (4.5 ± 1.4)%, (5.0 ± 2.0)%, (6.7 ± 2.2)%. Group D reduced invariant, compared with group B, C group difference was statistically significant (P lt; 0.05), B group, C group compared to the difference between statistical significance (P gt; 0.05) 5. Organization Pathology showed: the rabbits in each group postoperative surgical site showed no swelling and other signs of infection, no significant erosion naked eye view rabbits exposed hematoma. Thinner scar plate thickness with time, after 90 days to stabilize, group B compared with group C, D group difference was statistically significant (P lt; 0.05); C group and D group compared with no statistically significant (P gt; 0.05); inflammatory response due to polypropylene mesh with time to extend mitigated, B group compared with the C group, D group differences were statistically significant (P lt; 0.05), group C and D group, the difference was not statistically significant (P gt; 0.05); each group showed no degeneration and atrophy of the the obvious muscle tissue Yihong. Scanning electron microscope, group B, C group, D group were seen in the connective tissue surrounding the mesh thinner fibrous capsule thickness with time, of various networking silk surface no cracks, wear and tear. Conclusion 1. Polypropylene mesh implanted in animals polypropylene mesh - muscle tissue has good dimensional stability and stable in the short-term tensile strength, its flexibility with time and decreased scar tissue ingrowth favor to maintain polypropylene mesh - muscle tissue, dimensional stability and tensile strength, but will reduce the flexibility, resulting in the organization is overly rigid, and not conducive to the recovery of function. Speculated that the mechanical properties of the polypropylene mesh body tissues incompatible caused by erosion, exposure and intercourse discomfort key factors. Minor medical polypropylene mesh film short term cause inflammation and rejection shows good biocompatibility, long-term biocompatibility change remains to be further studied. Polypropylene mesh contraction invariant with time and increased clinical concerned about the long-term reduction of the polypropylene mesh change due to the complications is more important.
|