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

Abstract

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.

Keywords

pylon / additive manufacturing / prosthesis / polylactic acid

References

[1] Tavangarian F. The Need to Fabricate Lower Limb Prosthetic Devices by Additive Manufacturing. Biomed J Sci Tech Res. 2019; 15: 11662-73.

[2] Al-Thani H, Sathian B, El-Menyar A. Assessment of healthcare costs of amputation and prosthesis for upper and lower extremities in a Qatari healthcare institution: a retrospective cohort study. BMJ Open. 2019; 9: e024963.

[3] Van der Stelt M, Grobusch Martin P, Koroma Abdul R, Papenburg M, Kebbie I, Slump Cornelis H, et al. Pioneering Low-Cost 3D-Printed Transtibial Prosthetics to Serve a Rural Population in Sierra Leone - an Observational Cohort Study. E Clinical Medicine. 2021; 35: 100874.

[4] De Vivo Nicoloso LG, Pelz J, Barrack H, Kuester F. Towards 3D printing of a monocoque transtibial prosthesis using a bio-inspired design workflow. Rapid Prototyp J. 2021; 27: 67-80.

[5] Panesar A, Abdi M, Hickman D, Ashcroft I. Strategies for functionally graded lattice structures derived using topology optimisation for Additive Manufacturing. Addit Manuf. 2018; 19: 81-94.

[6] Rodgers GW, Van Houten EEW, Bianco RJ, Besset R, Woodfield TBF. Optimizing porous lattice structures for orthopaedic implants. Annu Int Conf IEEE Eng Med Biol Soc. 2015: 2450-3.

[7] Tahir MSAD, Kadhim FM. Design and Manufacturing of New Low (Weight and Cost) 3D Printed Pylon Prosthesis for Amputee. IOP Conf Ser Mat Sci Eng. 2021; 1094: 012144.

[8] Wang X, Xu S, Zhou S, Xu W, Leary M, Choong P, et al. Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review. Biomaterials. 2016; 83: 127-41.

[9] Kranz J, Herzog D, Emmelmann C. Design guidelines for laser additive manufacturing of lightweight structures in TiAl₆V₄ . J Laser Appl. 2014; 27: S14001.

[10] Mirzaali MJ, Moosabeiki V, Rajaai SM, Zhou J, Zadpoor AA. Additive Manufacturing of Biomaterials-Design Principles and Their Implementation. Materials (Basel). 2022; 15: 5457.

[11] Pitkin M. Design features of implants for direct skeletal attachment of limb prostheses. J Biomed Mater Res A. 2013; 101: 3339-48.

[12] Beck ON, Taboga P, Grabowski AM. Characterizing the Mechanical Properties of Running-Specific Prostheses. PLoS One. 2016; 11: e0168298.

[13] Tavangarian F, Proano C, Zolko C. Performance of Low-Cost 3D Printed Pylon in Lower Limb Prosthetic Device. In: The Minerals, Metals & Materials Series, editors. Proceedings of TMS 2019 148th Annual Meeting & Exhibition Supplemental. San Antonio, USA. Cham: Springer; 2019. pp. 1207-15.

[14] Inseemeesak B, Siripaiboon C, Somkeattikul K, Attasophonwattana P, Kiatiwat T, Punsuvon V, et al. Biocomposite Fabrication from Pilot-Scale Steam-Exploded Coconut Fiber and PLA/PBS with Mechanical and Thermal Characterizations. J Clean Prod. 2022; 379: 134517.

[15] Torabi AR, Shahbaz S, Ayatollahi MR. Tensile fracture prediction of 3D-printed V-notched PLA specimens: Application of VIMC-MEMC in conjunction with brittle fracture criteria. Eng Fract Mech. 2024; 310: 110497.

[16] Terzopoulou Z, Zamboulis A, Bikiaris ND, Xanthopoulou E, Ioannidis RO, Bikiaris DN. A decade of innovation: Synthesis, properties and applications of PLA copolymers. Progress Polym Sci. 2025; 167: 101991.

[17] Das M, Singh J, Santra S, Lalsangi S, Banerjee R. Breaking boundaries: Feasibility and flexibility of 3D printed polylactic acid composites in modern healthcare. Int J Biol Macromol. 2025; 320: 145804.

[18] Zhai M, Ahmed Mohamed ET, Locquet A, Schneider G, Kalmar R, Fendler M, et al. Diagnosis of Injection-Molded Weld Lines in ABS Thermoplastic by Polarized Terahertz Reflective Imaging. NDT E Int. 2021; 122: 102497.

[19] Peterson AM. Review of acrylonitrile butadiene styrene in fused filament fabrication: A plastics engineering-focused perspective. Addit Manuf. 2019; 27: 363-71.

[20] Tyler B, Gullotti D, Mangraviti A, Utsuki T, Brem H. Polylactic acid (PLA) controlled delivery carriers for biomedical applications. Adv Drug Deliv Rev. 2016; 107: 163-75.

[21] Naiyf AT, Kadhim FM, Hasan SF, Al-Din Tahir MS. Optimal design and manufacturing of 3D printable prosthesis pylon. Pollack Period. 2022; 17: 24-9.

[22] Gonabadi H, Yadav A, Bull SJ. The Effect of Processing Parameters on the Mechanical Characteristics of PLA Produced by a 3D FFF Printer. Int J Adv Manuf Technol. 2020; 111: 695-709.

[23] Tao Y, Kong F, Li Z, Zhang J, Zhao X, Yin Q, et al. A review on voids of 3D printed parts by fused filament fabrication. J Mater Res Tech. 2021; 15: 4860-79.

[24] Cuan-Urquizo E, Barocio E, Tejada-Ortigoza V, Pipes RB, Rodriguez CA, Roman-Flores A. Characterization of the Mechanical Properties of FFF Structures and Materials: A Review on the Experimental, Computational and Theoretical Approaches. Materials (Basel). 2019; 12: 895.

[25] Ziegler-Graham K, MacKenzie EJ, Ephraim PL, Travison TG, Brookmeyer R. Estimating the prevalence of limb loss in the United States: 2005 to 2050. Arch Phys Med Rehabil. 2008; 89: 422-9.

[26] Tavangarian F, Sadeghzade S, Davami K. A novel biomimetic design inspired by nested cylindrical structures of spicules. J Alloys Compd. 2021; 864: 158197.

[27] Sadeghzade S, Emadi R, Salehi M, Tavangarian F, Ramini A. Crack propagation and toughening mechanisms of bio-inspired artificial spicules fabricated by additive manufacturing technique. Theor Appl Fract Mech. 2020; 110: 102797.

[28] ISO 10328:2016 - Prosthetics - Structural Testing of Lower-Limb - Prostheses - Requirements and Test Methods [Internet]. ISO; [cited 2022 Dec 7]. Available from: https://www.iso.org/standard/70205.html

[29] Ortigao JAR, Sayao ASFJ. Handbook of Slope Stabilisation. Heidelberg: Springer Berlin; 2004.

[30] Mohd Khairul Nizam MAN, Ismail KI, Yap TC. The Effect of Printing Orientation on the Mechanical Properties of FDM 3D Printed Parts. In: Enabling Industry 4.0 through Advances in Manufacturing and Materials. Singapore: Springer; 2022. pp. 75-85.

[31] Jubinville D, Tzoganakis C, Mekonnen TH. Recycled PLA - Wood flour based biocomposites: Effect of wood flour surface modification, PLA recycling, and maleation. Constr Build Mater. 2022; 352: 129026.

[32] MR S, Nallamuthu I, Singsit D, Anand T. Toxicological evaluation of PLA/PVA-naringenin nanoparticles: In vitro and in vivo studies . OpenNano. 2022; 7: 100061.

[33] Bala A, Arfelis S, Oliver-Ortega H, Méndez JA. Life cycle assessment of PE and PP multi film compared with PLA and PLA reinforced with nanoclays film. J Clean Prod. 2022; 380: 134891.

[34] Barber JR. Intermediate Mechanics of Materials. 2nd ed. Dordrecht: Springer; 2010.

[35] Roche C, Sybilski D, Canestrari F, Piber H, Benedetto H, Bahia HU, et al. Advances in Interlaboratory Testing and Evaluation of Bituminous Materials. In: Partl MN, Bahia HU, Canestrari F, Roche C, Benedetto H, Piber H, et al., editors. Dordrecht: Springer; 2012.

[36] Shan Z, Leng Y. Fracture and fatigue behavior of sintered steel at elevated temperatures: Part I. Fracture toughness. Metall Mat Trans A. 1999; 30: 2885-93.

[37] Álvarez K, Lagos RF, Aizpun M. Investigating the influence of infill percentage on the mechanical properties of fused deposition modelled ABS parts. Ing Invest. 2016; 36: 110.

[38] Birosz MT, Ledenyák D, Andó M. Effect of FDM infill patterns on mechanical properties. Polym Test. 2022; 113: 107654.

[39] Johnson AD, Sherwin K. Foundations of Mechanical Engineering. CRC Press; 2017.

[40] El Magri A, Vanaei S, Vaudreuil S. An Overview on the Influence of Process Parameters through the Characteristic of 3D-Printed PEEK and PEI Parts. High Perform Polym. 2021; 33: 862-80.

[41] Baich L, Manogharan G, Marie H. Study of infill print design on production cost-time of 3D printed ABS parts. Inter J Rapid Manuf. 2015; 5: 308.

[42] How Much Does a Prosthetic Leg Cost? [Internet]. Proudly affiliated with the T2 Web Network, LLC; c2022 [cited 2025 Aug 1]. Available from: https://www.howmuchisit.org/prosthetic-leg-cost

[43] How Much Does a Prosthetic Leg Cost in 2025? [Internet]. PrimeCare LLC; c2025 [cited 2025 Aug 1]. Available from: https://primecareprosthetics.com/blog/how-much-does-a-prosthetic-leg-cost-in-albuquerque

[44] Hussain M, Maqsood Khan S, Shafiq M, Abbas N. A review on PLA-based biodegradable materials for biomedical applications. Giant. 2024; 18: 100261.

[45] Khouri NG, Bahú JO, Blanco-Llamer C, Severino P, Concha VOC, Souto EB. Polylactic acid (PLA): Properties, synthesis, and biomedical applications - A review of the literature. J Mol Struct. 2024; 1309: 138243.