Healing of canine articular cartilage defects treated with microfracture, a type-II collagen matrix, or cultured autologous chondrocytes

The effects of three different treatments on the healing of articular carti lage defects were compared with use of a previously developed canine model. In the articular surface of the trochlear grooves of 12 adult mongrel dogs , two 4-mm-diameter defects were made to the depth of the tidemark. Four do gs were assigned to each treatment group: (a) microfracture treatment, (b) microfracture with a type-II collagen matrix placed in the defect, and (c) type-II matrix seeded with cultured autologous chondrocytes, After 15 weeks , the defects were studied histologically. Data quantified on histological cross sections included areal or linear percentages of specific tissue type s filling the defect, integration of reparative tissue with the calcified a nd the adjacent cartilage, and integrity of the subchondral plate. Total de fect filling (i.e., the percentage of the cross-sectional area or the origi nal defect filled with any type of reparative tissue) averaged 56-86%, with the greatest amount found in the clogs in the microfracture group implante d with a type-II collagen matrix. The profiles of tissue types for the dugs in each treatment group were similar: the tissue filling the defect was pr edominantly fibrocartilage, with the balance being fibrous tissue. There we re no significant differences in the percentages of the various tissue type s among dogs in the three groups.