P.097 Tensile properties of Polyvinyl Alcohol Cryogel (PVA-C) formulations and generation of a tissue mimicking artificial lumbar intervertebral disc prototype

Abstract

Background: Current lumbar intervertebral disc prostheses provide suboptimal symptom relief with little natural load-cushioning. PVA-C is a promising biocompatible material, however previous studies from our lab show that it does not have adequate elastic modulus to mimic the annulus fibrosus. Here we present a prototype of an artificial lumbar intervertebral disc. Methods: The tensile properties of pure (5-35% PVA-C) and particle-reinforced (15% PVA-C with 5% of either Sephadex or hydroxyapatite) composite PVA-C formulations were evaluated. Simple tension and tensile stress relaxation tests were performed. Woven Teflon mesh was embedded in PVA-C and tested under compression. Endplate pull-out tests were performed. Results: Tensile testing showed that all PVA-C formulations behaved linearly for physiologic levels of strain (<20%). Tensile elastic modulus is an order of magnitude lower than the annulus fibrosus. Teflon has similar elastic modulus as collagen and compression of the hybrid Teflon-PVA-C construct revealed good biomechanical mimicry with elastic modulus of 20-25MPa at 20% deformation, similar to human data. Bonding between PVA-C and porous titanium endplate is excellent. Conclusions: A fiber-reinforced PVA-C impregnated composite adequately mimics the annulus fibrosus. Our prototype of a tissue mimicking artificial intervertebral disc utilizes a woven Teflon fiber with 20% PVA-C (+Hydroxyapatite) annulus and 5% pure PVA-C nucleus bonded to porous titanium foam endplates.