Figure 3. Schematics of autologous chondrocyte implantation in a flexed knee viewed from a cranial perspective. A shows the articular aspect of the femoral condyle, a common site of cartilage ulceration. In the first stage of the procedure, the ulcer (red oval) is debrided arthroscopically. B provides a close-up of the ulcerated femoral condyle (FC) and the site of harvesting of healthy chondrocytes (lavender oval) in the non-weight-bearing surface of the joint (eg, intertrochanteric notch of the femur [F]). C and D represent the in vitro culture of harvested chondrocytes. E shows the second stage of the procedure, in which autologous periosteum (white oval) is harvested from the proximal tibia (T), a non-weight-bearing location that is commonly used as a harvest site. In F, the harvested periosteum is fashioned into a patch and sutured to the edges of the debrided ulcer. In G and H, cultured chondrocytes are injected beneath the periosteal patch. In I, the periosteal patch is securely fastened and sealed with fibrin glue.