In healthy individuals there exists a balance between cartilage proteoglycan synthesis and degradation. In arthrotic cartilage this metabolic balance is deteriorated in spite of a sometimes enhanced proteoglycan synthesis, since the catabolic rate exceeds the anabolic rate corresponding to the severity of the disease. The extracellular organic matrix of the cartilage is destroyed. With different experimental models it could be demonstrated, that the non steroidal anti-inflammatory drugs commonly used in the treatment of arthrosis inhibit the synthesis of mucopolysaccharides, intensify the already existing metabolic disorder, prevent a normalization of cartilage composition and thus impair the function of the cartilage. Glucosamine on the other hand increases in a dose-dependent way the ability of cartilage to synthesize both sulfated mucopolysaccharides and protein, thus restoring the catabolic-anabolic balance of the cartilage.