Regeneration of Articular Cartilage of the Knee: Basic Concepts.- Articular Cartilage Defects of the Knee: Diagnosis and Treatment.- Imaging Techniques of Articular Cartilage.- Refixation of Detached Fragments.-Debridement, Joint Lavage and Cartilage Shaving.- Drilling, Abrasion and Microfractures.- Osteochondral Transplantation and Mosaicplasty.- Autologous Chondrocyte Implantation.- Alignment Osteotomies.- Rehabilitation of Chondral Lesions of the Knee.- Medical Treatment: Intra-articular Injections of Hyaluronic Acid.