Mechanical behaviour and structural characterization of human fascia lata.

Purpose: The fascia lata is a key structure determining the physiological functioning of knee and thigh muscles. At the same time it assures mechanical protection of the tissues situated beneath. This study aimed to clarify the comprehensive mechanical properties and microscopic structure of human fascia lata to understand its mechanical behaviour better. Methods: The pathologically unchanged fascia lata used in this study were collected post mortem from adult males of different age. The mechanical properties of the samples were determined under the uniaxial tensile test in two directions (longitudinal and transverse to collagen bundles arrangement). The structure observations were performed using a light and scanning electron microscope. Results: The mechanical tests have shown the anisotropic properties of the examined tissue. The values of the particular mechanical parameters were determined. The maximum failure force, stiffness coefficient, tensile strength and Young's modulus values were higher for longitudinal than transversal samples. Before the uniaxial tensile test, the collagen bundles within each layer of examined samples were aligned parallel to each other, showing a regular, wavy architecture (crisped pattern). The elastin fibres within these layers were much less numerous than collagen fibres. The applied mechanical forces disrupted the intact, regular collagen pattern, making the majority of collagen bundles loosely and irregularly oriented. Conclusions: Knowledge of the mechanical and structural properties of the human fascia lata is an important issue in the context of clinical applications, tissue engineering as well as numerical modelling.