RecruitingPhase 3Biological interventionA Study of MACI in Patients Aged 17 to 65 Years With Symptomatic Chondral or Osteochondral Defects of the AnkleThe objective of this study is to demonstrate the superiority of MACI (autologous cultured chondrocytes on porcine collagen membrane) versus Bone Marrow Stimulation in the treatment of patients aged 17 to 65 years with symptomatic articular chondral or osteochondral defects of the talus.