Mechanical evaluation of synthetic biomaterials used in the correction of pelvic floor disorders—Experimental study in rabbits

Abstract 

Objective

To evaluate the biomechanical properties of the principal prosthetic materials currently used in genital prolapse surgery.

Study design

Based on an animal model of incisional abdominal hernia, 40 adult rabbits were implanted. Four 2.5cm×2.5cm parietal defects, were created in the abdominal fascia and muscles while respecting the peritoneum. For each rabbit, the defect was repaired by four different large pore size prostheses which varied according to the material used: two with monofilament of heavy (75g/m²) or low (38g/m²) weight polypropylene (PP), and two with multifilament of heavy (115g/m²) or low (59g/m²) weight polyethylene-terephthalate (PET). Animals were sacrificed in groups of 10 after 14, 30, 90 and 180 days to evaluate contraction, solidity and elasticity of the prostheses.

Results

PP and PET retracted, independently of their weight, in 81.25% and 20% respectively. Intensity of contraction was not predictable but median value of retracted surface was 14% with PP, none with PET. Contraction settled quickly after tissue integration and did not subsequently occur. Heavyweight PET was considered the most solid material (70Ncm⁻¹), low-weight PP the most fragile (20Ncm⁻¹). Heavy forms of PP or PET resisted better to the rupture than the light forms which were sometimes insufficient to resist the extreme values of the human abdominal pressure (16Ncm⁻¹). PP was more flexible than PET, but PET was the only form which was able to support extreme values of the abdominal pressure and remain in the elastic range. Duration of implantation did not modify solidity or elasticity of the prostheses.

Conclusion

In our abdominal rabbit model, as regards mechanical properties, heavyweight PET seems to be the optimal biomaterial.

Keywords: Biomechanical properties, Pelvic organ prolapse, Polyester prosthesis, Polypropylene prosthesis, Rabbit model