Dynamic mechanical properties of the rat aged spinal cord tissue: Characterization of elasticity, viscoelasticity, and non-linearity

Abstract:

Ageing plays a pivotal role in spinal cord (SC)-related disorders, but the impact of ageing on the SC, especially with respect to its material properties, remains poorly understood. Prior investigations have primarily focused on static uniaxial testing, leaving dynamic mechanical assessment significantly unexplored. Addressing this research deficit, this investigation delivers an extensive examination of mechanical and viscoelastic characteristics in aged SC specimens utilizing rat models. Essential measurements encompassing elasticity and viscoelasticity, specifically peak force, moduli, and hysteresis, are documented. This investigation uniquely emphasizes the intricate aspects of aged tissue behavior, including frequency-dependent responses, non-linear properties, and conditioning phenomena. For the first time, this study emphasizes the complex characteristics of aged tissue response, such as frequency dependence, non-linearity, and conditioning effects. Furthermore, the influence of preconditioning and conditioning is examined, revealing regional dependencies. These results highlight the inadequacy of current models that assume isotropic, linear elasticity, and homogeneity in representing the SC. The findings establish fundamental material property data essential for subsequent research comparing normal and pathological SC mechanics, advancing computational modeling capabilities and deepening the comprehension of SC structure-function relationships.

Keywords:

Spinal cord biomechanics; Dynamic mechanical analysis; Spinal cord material properties; Indentation testing; Compression testing.