OATS and mosaicplasty are the same surgical technique applied at different scales: OATS transfers a single cartilage plug for knee defects under 2 cm², mosaicplasty tiles smaller grafts across 2–4 cm² lesions.OATS and mosaicplasty are the same surgical technique applied at different scales: OATS transfers a single cartilage plug for knee defects under 2 cm², mosaicplasty tiles smaller grafts across 2–4 cm² lesions.