Purpose of this study was to show the efficacy and safety of the investigational product co.don chondrosphere® (ACT3D-S). ACT3D-S is a product for autologous chondrocyte transplantation that we used in an animal model, the merino land sheep. We compared the treatment of ACT3D-S (Group A: Investigational product) with an untreated control (Group B: Control Intervention) in a bilateral model, what means that by randomization one hind limb was chosen to be treated with ACT3D-S while the remaining hind limb was left without treatment.