Histological Evaluation of the Course of Healing of Canine Articular Cartilage Defects Treated with Cultured Autologous Chondrocytes

The orthopedic problem of restoring damaged articular joint surfaces remains unsolved. One technique aimed at cartilage regeneration, which has been introduced clinically, uses autologous chondrocytes grown in culture and periosteum to treat defects made to the depth of the calcified cartilage. In this study we applied a similar treatment to 34 adult dogs and analyzed the course of healing at five time points up to 18 months. Two sets of controls were included: (1) periosteum without cells and (2) empty defects. Histology showed healing generally to occur in three phases: (1) a proliferative phase (established by 1.5 months) in which reparative tissue was formed, (2) a phase of remodeling (found at 3 and 6 months) in which hyaline and articular cartilage were regenerated, and (3) a phase of degradation (observed predominantly at 12 and 18 months) in which the reparative tissue and surrounding cartilage appeared to become progressively damaged. Treated groups at 3 and 6 months contained more hyaline cartilage than untreated controls, but there was no evidence of a positive effect of periosteum or cultured autologous chondrocytes at 1 year and longer.