Since collagen type VI seems to play an important role in cartilage metabolism and is increased in osteoarthritis, the aim of this study was to investigate whether different stages of osteoarthritis can be characterised by the content of collagen type VI in human knee cartilage.
Collagen type VI was investigated in 148 histologically normal and 117 osteoarthritic cartilage samples from 18 different localisations of human knee joints. It was quantified in cartilage extracts using an inhibition-ELISA.
In normal cartilage the average content of collagen type VI was 0.48 per cent of total collagens. Interestingly, there was a high variability not only in osteoarthritic, but also in normal cartilage. The statistical analysis showed significant differences between normal femoral, tibial or retropatellar cartilage samples. Therefore, normal and osteoarthritic samples from different localizations had to be compared separately. A significant increase of collagen type VI was already found in early osteoarthritic lesions.
Inspite of a statistically significant increase of collagen type VI in osteoarthritic cartilage, the range of concentrations found in normal and osteoarthritic samples overlap. In view of the high interindividual variability, collagen type VI is not very precise in the diagnosis of early osteoarthritic lesions if used as the only marker.