3D printed pylon for lower limb prosthetic device inspired by spicule architecture

Aim: The high cost and weight of conventional metal pylons used in lower-limb prostheses limit accessibility and increase patient burden. This study evaluated whether a 3D-printed, polylactic acid (PLA) prosthetic pylon, incorporating a biomimetic lattice, meets ISO 10328 mechanical requirements and can serve as a lightweight, cost-effective alternative to metal pylons. Methods: A lattice shell inspired by the Euplectella aspergillum sponge architecture was designed to envelop a cylindrical core to mitigate failure under compression and torsion. Pylons were fabricated by fused deposition modeling (FDM) using PLA at 25% infill with a net pylon radius of 6.66 mm. Mechanical testing followed ISO 10328 protocols and included ultimate static compression, torsion, and cyclic compression (dynamic) tests. Performance metrics recorded included ultimate load capacity, cycle endurance, safety factors for compression and torsion, gross mass, and production material usage. Results: Optimized PLA pylons passed all ISO 10328 tests with no structural failure or visible defects. The pylons sustained a maximum static compression load of 7,901 N (ISO target: 4,480 N), completed > 3 million cycles under dynamic loading without failure, and achieved safety factors of 2.69 (compression) and 2.15 (torsion). The 3D-printed units weighed ~282 g, approximately 30% lighter than comparable metal pylons (~400 g), and material/geometry optimization reduced material use and manufacturing cost. Conclusions: PLA-based, 3D-printed pylons with a biomimetic lattice architecture demonstrate sufficient mechanical integrity to satisfy ISO 10328 requirements and offer a lightweight, lower-cost alternative to traditional metal pylons. These findings support further in-vitro and in-vivo validation and highlight the potential for additive manufacturing to expand prosthetic accessibility—particularly in resource-limited settings.