Figure 2

A schematic example of implantation of DN gel plugs and sheets. A; a 0.5-mm gel sheet was implanted at the bottom of the defect. B; a 1.0-mm gel sheet was implanted at the bottom of the defect. C; a 5.0-mm gel plug was implanted at the bottom of the defect. D; the control group has a defect left untreated. In each subgroup, the depth of the final vacant space in the defect with or without DN gel implantation became 2.0, 3.0, or 4.0 mm. For example, when the depth of the final vacant space was set at 2.0 mm in each Group, a defect was created with a depth of 2.5 mm in Group I, 3.0 mm in Group II, 7.0 mm in Group III, and 2.0 mm in Group IV using drill, and then the DN gel sheet or plug was implanted into the defect so that a vacant space having a 2-mm depth from the articular cartilage surface remained after surgery. Note that a vacant space (_*) having the same depth from the articular cartilage surface remained after surgery in the same sub-group.