Biomaterials used in orthopedic applications: advantages and disadvantages. - Tissue engineering may offer new treatment alternatives: scaffolds and cells. - Regenerative medicine: want to replace and repair lost or damaged tissues by stimulating the natural regeneration process. The gap between the damaged fragments has to be filled with functional materials that act as a substrate and as a physical three-dimensional microenvironment for inducing the migration and organization of cells from the native tissue. - Differentiation and maturation signals that positively promote osteogenesis or chondrogenesi