Role of the periosteal flap in chondrocyte transplantation: An experimental study in rabbits

To determine the role of the periosteal flap in chondrocyte transplantation for the treatment of articular cartilage defects, a cartilage defect was created on the patellar groove of the rabbit knee. The defect was filled with chondrocytes cultured in collagen gel, and was covered with a periosteal flap the cambial layer of which was facing the patella (P group), or facing down against the bone marrow (M group). The same defect was covered with a periosteal flap that was frozen and thawed three times (F group), and an artificial collagen film (C group). At 3 and 6 months, the defects were filled with reparative tissues that showed a smooth surface and resembled hyaline cartilage in the P, M, and F groups. There were no significant differences between the reparative tissues in the three groups histologically, immunohistochemically, biochemically, and biomechanically, although the collagen film fell down into the defect and the reparative tissue had a fibrous tissue-like appearance. These results showed that the periosteal flap does not have a beneficial Immoral or cellular effect on the formation of reparative tissue, suggesting that the periosteal flap might act as a mechanical barrier to prevent leakage of grafted chondrocytes.