Microfracture: Earning small holes from the bone and bone marrow beneath the damaged cartilage, which stimulates the bone to repair by itself (by way of marrow cells), resulting in freshly formed cartilage situation.  (OCD), a affliction exactly where a chunk from the cartilage plus the layer of bone beneath have died. https://www.theorthopaedicandpainpractice.com/what-are-cartilage-lesions/