09: Biomechanical properties of poly-4-hydroxybutyrate mesh compared to polypropylene mesh in a rabbit model: 3-month time point

To evaluate the biomechanical properties of an absorbable monofilament, poly-4-hydroxybutyrate (P4HB) mesh, as compared to a lightweight polypropylene (PP) mesh. After obtaining IACUC approval (2016-045), a total of eight female retired breeder New Zealand White rabbits were anesthetized, shaved, sterilely prepped, and draped. Mesh samples (Upsylon, Boston Scientific, and P4HB, Tepha) were implanted. Four 1.5 cm wide × 4.5 cm long pieces of mesh were secured to the anterior abdominal fascia using six interrupted sutures (4-0 polypropylene, Prolene, Ethicon). Vaginally, a subepithelial pocket was created by sharp and blunt dissection and a 0.5 cm wide × 1.5 cm long piece of mesh was secured into the pocket parallel to the vaginal canal and anchored with two interrupted sutures (4-0 polypropylene, Prolene, Ethicon), one at the distal and one at the proximal end of the mesh. Rabbits were euthanized 3 months post-implantation, gross necropsy was performed and the implants were harvested. Stiffness, elastic modulus, and tensile strength were measured. Tissue contraction was determined by subtracting the area of implanted mesh to area of mesh at time of sacrifice. Extension to failure biomechanical testing was performed using a material testing system (Instron #5566). Descriptive statistics were calculated. The biomechanical properties of PP compared to P4HB were calculated using the Mann-Whitney rank sum test. A P value of <0.05 was considered significant. There were zero abdominal mesh exposures 3 months after implantation, and the implants were integrated into the abdominal and vaginal tissues. There were 3/16 (18.75%) vaginal mesh exposures, all at the distal vagina along the suture line, 1 PP anterior vaginal wall and 2 P4HB posterior vaginal wall. There was no significant difference in tissue contraction for both PP and P4HB samples. Abdominal PP tissue contraction was 67% vs P4HB 58% (P = 0.21). Vaginal PP tissue contraction was 55% versus P4HB 77% (P = 0.29). Table 1 demonstrates the biomechanical properties. There were no significant differences between PP and P4HB in either the abdominal and vaginal groups. The biomechanical properties of P4HB and PP mesh at 3 months implanted in the rabbit model are similar. Further data including the histologic response and mechanical properties at longer implantation times will help determine the suitability of a P4HB mesh intended for urological and gynecological applications.