Making the human articular cartilage mechanical injury model. (a) Distal articular surface of femoral lateral condylar of the knee joint. (b) Osteochondral tissue consisting of the full-thickness cartilage with subchondral bone. (c) The osteochondral tissue is vertically cut into explants to produce mechanical injury model at the margin. (d) The lateral view of mechanical injury model on osteochondral explant.