[Cellular aspects of the aging of articular cartilage. I. Condylar cartilage with a normal surface sampled from...

The authors studied the cellular density of articular cartilage taken from the femoral condyles of 77 autopsy subjects at Hôpital Lariboisière in Paris. This study showed a decrease in the cellular density (number of chondrocytes per mm2) going from the superficial zone towards the calcified zone of the cartilage in all layers, as a function of the age of the subjects. The decrease in cellular density is in the order of about 50% of the total chondrocyte number when subjects younger than 40 are compared with those older than 80. The demonstration of a regular increase in the number of empty lacunae per mm2 with the age of the subjects, i.e. lacunae without chondrocytes, suggest that the cause of this decrease in cellular density of the cartilage with age could be a physiological necrosis due to "exhaustion" of the chondrocytes. The metabolic activity of the chondrocytes may also decrease with age, as suggested by the increasing proportion of alcianophobic cells, cells which are weakly or not at all labeled by radioactive sulfates which indicate the sites of biosynthesis of proteoglycans. These cellular modifications could play a role of senile fibrillation of articular cartilage and in arthrosis.