Table 1. Chemical composition of aging cartilage versus osteoarthritic cartilage
Component Aging cartilage Osteoarthritic cartilage
Water [down arrow] [up arrow]
Glycosaminoglycans Normal or slightly [down arrow] [down arrow]
Keratan sulfate [up arrow] [down arrow]
Chondroitin sulfate [down arrow] -
Hyaluronic acid [up arrow] [down arrow]
Proteoglycans Decreased extractability, normal aggregation Increased extractability, decreased aggregation
Link protein Fragmented Normal

[up arrow], increased amount; [down arrow], decreased amount; -, no change.

Adapted from Sack (3).