In Vivo Biomechanical Properties of Heavy Versus Light Weight Monofilament Polypropylene Meshes. Does the Knitting Pattern Matter?

Aims: This work evaluated the post-implant biomechanical properties of light-weight (LW) and heavy-weight (HW) monofilament polypropylene (PP) meshes with different knitting patterns in an animal model in vivo. Methods: Forty-five adult female Wistar rats were divided into three groups and randomly implanted with 32 x 32mmHW-PP (62gm(-2)) orLW-PP (16gm(-2)) in the lower abdomen. LW-PP was tested orthogonally (called LWL and LWT) to reproduce the longitudinal and transverse planes of the vaginal wall, respectively. Abdominal walls were removed at 7, 30, and 60 days, and then tested for tensile load (maximum load until avulsion from the tissue), deflection, and stiffness to maximum load. Explants were compared over time and between groups. Results: LW-PP meshes implanted in the LWT fashion (vaginal transverse plane) showed comparable maximum load and stiffness to HW-PP meshes, and LW-PP meshes implanted in the LWL fashion (vaginal longitudinal plane) presented lower maximum load and stiffness than the HW-PP meshes. There were no significant differences in the values of deflection at maximum load between the studied meshes as a function of time. Conclusions: The final mechanical behavior of PP mesh can be changed by its weight and knitting pattern. These properties may be useful in making more biocompatible prostheses for pelvic organ prolapse (POP) with less foreign material to maintain longitudinal vaginal elasticity and minimize sexual symptoms while maintaining transverse resistance (i.e., between vaginal fornixes) to prevent POP recurrence. (C) 2015 Wiley Periodicals, Inc.