Melt Electrowriting-Based Hybrid Fabrication of Biodegradable Cog Threads: Design and Mechanical Evaluation for Pelvic Floor Repair

Additive manufacturing (AM) offers new opportunities for biomedical device design; however, its translation to soft-tissue reinforcement remains challenging, particularly in pelvic organ prolapse (POP) applications requiring mechanical performance and tissue compatibility. In this study, a hybrid AM approach combining melt electrowriting (MEW) and controlled post-processing was developed to fabricate biodegradable poly(ε-caprolactone) (PCL) cog threads for minimally invasive pelvic reinforcement. This integrated fabrication workflow enables the precise deposition of microscale fibers via MEW followed by localized mechanical modification, offering a versatile platform for tailoring graft architecture and anchoring geometry. Smooth filaments were first produced via MEW and subsequently post-processed to introduce barbs for mechanical anchorage. The resulting structures were mechanically characterized through uniaxial tensile testing and evaluated as reinforcement elements in ex vivo sow vaginal tissue using ball burst testing. The MEW-fabricated cog threads increased the ultimate load of vaginal tissue from 83 ± 20 N (control) to 126 ± 15 N, corresponding to a 51.8% improvement (p = 0.0477). Compared with commercial PCL cog threads reported in the literature (177.0 ± 5.4 N), the reinforced specimens achieved approximately 71% of the benchmark load. Owing to their intermediate stiffness profile, the MEW-fabricated cog threads reduced mechanical mismatch with soft tissue compared to high-stiffness commercial alternatives. These findings demonstrate the feasibility of hybrid MEW-based additive manufacturing strategies for engineering mechanically compatible, application-driven soft-tissue reinforcement systems.