Figure 4

Safranin-O/fast green staining of plug cartilage and the shaved area (original magnification 10×). (a, b) No abnormalities were observed at day 0. The plug (between the arrows) was inserted flush with the surrounding articular surface and the site of the shaved area (between the triangles) was clearly recognizable. There was a space between the plug and the surrounding tissue. (c, d) At 2 weeks postoperatively, the plug (between the arrows) had subsided a little and newly formed tissue covered half of the plug. No tissue was observed at the site of the shaved area (between the triangles). There was a slight space between the plug and the surrounding tissue. (e, f) The implanted osteochondral plug (between the arrows) had united in the subchondral bone area by 4 weeks postoperatively. The newly formed reparative tissue, which stained faintly with safranin-O, covered the plug cartilage and the plug cartilage was well stained. No tissue was observed at the site of the shaved area (between the triangles). Bony union was observed between the plug and the host.