TRANSPLANTATION OF AUTOLOGOUS COSTAL CARTILAGE TO AN OSTEOCHONDRAL DEFECT ON FEMORAL HEAD - HISTOLOGICAL AND AUTORADIOGRAPHICAL STUDIES IN ADULT RABBITS AFTER ADMINISTRATION OF 35S-SULPHATE AND 3H-THYMIDINE

(A) Autologous costal cartilage which had first been implanted intramuscularly for 4-5 weeks (18 animals) and (B) fresh autologous costal cartilage (17 animals) were transplanted to an osteochondral defect, measuring 3×4×3 mm, on the femoral head in adult rabbits. After 7 different observation times between 1 and 46 weeks the animals were killed. The femoral head was incubated in 35S-sulphate or 3H-thymidine in vitro and examined histologically and autoradiographically. In 34 of the 35 preparations from the two experimental groups, and at all observation times, the transplant area lay at a level with the remaining articular surface. Both histological and autoradiographical examination revealed union of the transplant with the articular cartilage via young hyaline cartilage, with a high 35S-sulphate uptake, at observation times from 4 weeks onwards, in 13 out of 14 cases in group A and in 12 out of 13 cases in group B. At observation times of 1 and 2 weeks, young mature cartilage was found between the transplant and articular cartilage in 2 out of 4 cases in group A and in no cases in group B. Immature cartilage occurred in 3 out 4 cases in group A and in 1 out of 4 in group B. The articular surface in the transplant area consisted to the greatest part of young mature cartilage in 16 of the 18 cases in group A (all observation times) and in 11 of the 17 cases in group B (at all observation times from 4 weeks onwards). This young cartilage showed a high 35S-sulphate uptake and contained 3H-thymidine labelled chondrocytes. At observation times from 8 weeks onwards the chondrocytes in this young cartilage in both experimental groups showed a tendency to a columnar arrangement oriented at right angles to the articular surface, and the layer of cells nearest to the articular surface were arranged tangentially to the joint cavity. The transplants probably contributed actively to the cartilaginous union between the transplant and the articular cartilage and to restitution of the articular surface in the defect area with viable hyaline cartilage. Local tissue from the subchondral bone area also appeared to have contributed to some extent. © 1969 Springer-Verlag.