BIOMECHANICS OF FASCIAL SYSTEMS IN DIFFERENT CLINICAL CONDITIONS

Fascial tissues envelop structures such as muscles, nerves, and viscera, connecting them throughout the body. Fascial tissues are part of a system (i.e., epidermis/dermis, superficial adipose tissue, superficial fascia, deep adipose tissue, deep fascia, epimysium, muscle) connected through retinacula cutis. The roles of the fascial tissues also include the transmission of forces, with potential implications in body function and the etiology of pain, such as low back pain (LBP). This thesis focuses on the implications of human fascial tissues in the musculoskeletal domain. Specifically, it aims to characterize the properties of the fascial tissues with a two-phase approach: ex vivo and in vivo. Considering the ex vivo approach, the biomechanical properties (e.g., non-linear, anisotropic, viscoelastic behavior) of fasciae are analyzed through uniaxial tensile tests (failure and stress-relaxation tests) on cadaveric samples, discussing their site-specificity both in terms of specific layer, superficial and deep fascia, and body regions. Constitutive modeling formulations are also included in the analysis. Considering the in vivo approach, quantities as the thickness of fascial tissues are manually measured in living subjects with non-specific LBP through magnetic resonance imaging. Finally, automated methods are proposed to quantify parameters such as fascial tissues thickness and movements using ultrasound imaging in living subjects, with the aim to contribute to the automatic evaluation of fascial tissues parameters and the definition of their potential roles as biomarkers for LBP. Overall, these findings support the definition of methodological and quantitative references for fascial tissues properties, and in the future the integration and correlation of multi-modal approaches to evaluate them. Moreover these results broaden the understanding of the implications of fascial tissues in the musculoskeletal domain, their different roles according to their variability, with direct applications in tissue engineering and clinical practice. The goal is to improve personalized, site-specific, and evidence-based care.