Reparative response of human articular cartilage in tissue culture. Comparison between a normal and an osteoarthritic knee of the same donor.

Some evidence is presented that the metabolism of visually intact cartilage taken from a knee with focal osteoarthritic lesions, may already be affected. Proteoglycan metabolism of articular cartilage from the macroscopically unaffected right knee and the osteoarthritic left knee of the same donor was assayed in long-term tissue culture. A good reparative response was found in the right knee with an increase in the relative amount of radiolabelled proteoglycan and proteoglycan aggregates, and in the total amount of labelled proteoglycan per mg dry tissue. No significant differences were found when the anteromedial, anterolateral and posterolateral areas were compared. Visually intact samples taken from the left knee, with a deep osteoarthritic cartilage erosion on the medial condyle, showed no accumulation of radiolabel into proteoglycan and proteoglycan aggregates for the enzymatically pretreated samples. This was interpreted as a repair failure.