Microchemical studies on glycosaminoglycans and calcium in autologous costal cartilage transplanted to an osteochondral defect on the femoral head of adult rabbits.

Abstract

In adult rabbits, a transplant was made to an osteochondral defect on the femoral head measuring 3×4×3 mm of autologous costal cartilage which had first been implanted intramuscularly for 4–5 weeks and fresh autologous costal cartilage. After 6 different observation times between 2 and 52 weeks the animals were killed. The original material, the tissue in the transplant area on the articular surface and the articular cartilage above the “tidemark” were analysed in each individual animal, after microdissection of freeze-dried sections of these structures, by a quantitative microchemical technique for their content and composition of glycosaminoglycans and for their calcium content. The hexosamine content (% per organic dry weight) was generally higher in the transplants than in the articular cartilage at observation times of 2 and 6 weeks, after which time it was similar. The distribution of the different glycosaminoglycan fractions was different in the transplants compared with the articular cartilage. Thus the glycoprotein and/or keratan sulphate fraction was smaller in the transplant than in the articular cartilage, while the opposite held for the chondroitin sulphate. With increasing observation times, some resemblance became evident between the transplant and articular cartilage with respect to the relative size of these fractions. The solubility profiles of the chondroitin sulphate were similar. The calcium content was generally higher in the transplant than in the articular cartilage, after 12 weeks it showed a pronounced decrease in comparison with the original material. The chemical findings indicate that the cartilage in the transplant area did not undergo any marked degenerative changes.