2D and 3D PVA electrospun scaffold evaluation for ligament implant replacement: a mechanical testing, modelling and experimental biomechanics approach

Roldan Ciudad, Elisa ORCID: https://orcid.org/0000-0002-7793-7542, Reeves, Neil D ORCID: https://orcid.org/0000-0001-9213-4580, Cooper, Glen ORCID: https://orcid.org/0000-0002-9568-8973 and Andrews, Kirstie ORCID: https://orcid.org/0000-0002-0860-0604 (2024) 2D and 3D PVA electrospun scaffold evaluation for ligament implant replacement: a mechanical testing, modelling and experimental biomechanics approach. Materialia, 33. 102042. ISSN 2589-1529

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Abstract

The gold standard to characterise anterior cruciate ligament (ACL) implants is through the evaluation of mechanical properties such as Young's modulus or ultimate tensile stress. Currently, no studies have been performed to relate the in-vivo hyper-elastic behaviour of the ACL with the design of tissue engineered ligaments. The aim of this work is to determine the most comparable 2D/3D polyvinyl alcohol (PVA) electrospun structure to the in-vivo mechanical behaviour of the natural ligament. Biomechanics of 12 young participants were captured while daily and high impact activities were performed. A musculoskeletal knee model and kinematic data were used to estimate the in-vivo ACL length and strain. The in-vivo ACL tensile forces were determined with a non-linear force/strain relationship. 2D scaffolds, 1 twisted filament scaffolds, 3 twisted filaments scaffolds and 3 twisted/braided filaments scaffolds were fabricated using electrospinning and characterised morphologically and mechanically using scanning electron microscopy and tensile testing respectively. Cyclic tensile and shear tests were performed in dry and wet conditions to crosslinked and non-crosslinked samples. The hyper-elastic behaviour of our PVA scaffolds was characterised with the Mooney Rivlin model and a non-linear string-based model, and both models compared with the in-vivo mechanical behaviour of the native ACL. Crosslinked 3 twisted/braided filaments scaffolds faithfully mimicked the morphology and the hyper-elastic behaviour of the natural ACL, showed a good resistance to shear loading and remained undegraded in phosphate-buffer saline solution. This study demonstrated, for the first time, that 3 twisted/braided filaments PVA electrospun scaffolds have an excellent potential for ACL replacements.