Microfractured cartilage defect (A) and macroscopic appearance of the specimens in groups 1 (B, D) and 2 (C, E). Gross appearance was shown at 4 (B, C) and 12 weeks (D, E). (B) The repair tissue covered more than 50% of the cartilage defect. (C) Little repair tissue was observed in the cartilage defect. (D) Repair tissue almost completely covered the defect in the experimental group, but the defect in the control group (E) was insufficiently repaired.