A novel assessment of dynamic mechanical properties in different articular cartilage layers

Human articular cartilage, a nonlinear, viscoelastic solid-liquid biphasic tissue, has different mechanical properties and undertakes different functions in different layer. The compression deformation and fatigue damage mechanism of each layer of cartilage is also different when in injury. Compression properties of cartilage can predict cartilage integrity and the likelihood of osteoarthritis. Therefore, the confined and unconfined compression of cartilage is taken to systematically study the dynamic mechanical properties of each layer and reveal the relationship between the dynamic mechanical properties of each cartilage layer and the function of the corresponding cartilage layer. Under confined and unconfined compression conditions, the larger the cyclic loading rate, the greater the deformation rate of each layer. In addition, under the same cyclic loading rate, the superficial layer had the highest deformation rate, followed by the middle layer and the deep layer, which indicates that the deep layer mainly assumes the compression load. Furthermore, under the same loading displacement, the loading stress of cartilage and the deformation rate of each layer in confined compression were greater than those in unconfined compression. Simultaneously, with the increase in the number of loading cycles, the deformation rate in different layers increased first and then stabilized.