Fig. 2

Arthroscopic images after osteochondral autologous transfer (OAT), and macro and micro observation images of isolated tissue after total knee arthroplasty (TKA). A At 1.5 years after OAT, good prognosis of the transferred grafts was confirmed by arthroscopy (left side). The osteochondral tissue contained inserted plugs that were discarded during TKA. The surface of the tissue was almost smooth (right side). The yellow line indicates the section area of (B). B Histological images with safranin-O staining (upper; SO) and hematoxylin–eosin staining (lower; H–E) show that the cartilage surface was not smooth between the host and plug cartilage. There were some cracks in the regenerated fibrous cartilage that reached bone marrow region. Arrowhead indicates the site of transferred plugs. Asterisk indicates bone marrow edema. Arrows indicate subchondral bone cyst. The control tissue shows the smooth surface of cartilage and strong staining intensity of SO. Scale bars indicate 5 mm