Morphological aging changes in human articular cartilage.

It is readily apparent from a large number of studies that the various organs and tissues of the human body show a non-uniform and asynchronous aging behavior. Therefore we decided to analyze the articular cartilage of the human caput femoris (F) and trochlea tali (T). Besides histochemical findings (reaction of the ground substance, metachromatism, and content of glycosaminoglycans), it has been observed that the percentage of chondrocytes relative to a constant area in newborn infants is 10.14 +/- 0.61% (F) and 14.07 +/- 0.85% (T). This percentage becomes gradually smaller in the following decades, decreasing from 8.27 +/- 3.49% (F) and 8.63 +/- 3.03% (T) in the first decennium to 5.15 +/- 1.17% (F) and 5.48 +/- 2.30% (T) in the second decennium, and from 4.94 +/- 0.58% (F) and 4.80 +/- 0.81% (T) in the third-sixth decennia to 2.36 +/- 0.28% (F) and 3.01 +/- 0.87% (T) in the eighth decennium. In both the F and T articular cartilages a major variation is observed in the number of chondrocytes relative to a constant area between birth and the third decennium; thereafter, only minor variations can be observed. The mean area of chondrocytes is 91.68 micrometers 2 (F) and 99.42 micrometers 2 (T) in neonates, 224.89 micrometers 2 (F) and 259.08 micrometers 2 (T) in the first decade of life, 259.52 micrometers 2 and 323.68 micrometers 2 (T) in the second decade, 366.89 micrometers 2 (F) and 339.35 micrometers 2 (T) in the third-sixth decades, and 229.48 micrometers 2 (F) and 173.85 micometers 2 (T) in the eighth decade. Summarizing, we note that there are only gradual rather than fundamental differences between the aging changes in the head of the femur and the trochlea of the talus.