I think the importance of proteoglycan was understood.
Now why do some people have more proteoglycan and some people doesn't?
Proteoglycan increases or decreases due to the difference of the casual lifestyle.
The difference of the casual life style is if you bend and extend your knee in your daily life or not.
Bending and extending the knee increase the blood flow of the knee, and more oxygen with blood is brought to the knee. The cartridge cells are activated by the oxygen, making more proteoglycan.
3 conditions decrease Proteoglycan
1. Weight gain – The more your weight is, the more the risk to break down the cartridge increases because of more burden to the knee. Breakdown of the cartridge causes the loss of the function as sponge, the difficulty of absorbing oxygen and nutrition, and lowering the metabolism of the cartridge, resulting in being difficult to make proteoglycan.
2. Over 40 years old – degeneration of the cartridge of the knee progresses from 40s gradually, leading to being difficult to make proteoglycan.
3. Female –Female’s cartridge tends to degenerate twice as many as male’s. Estrogen that is a female hormone has a function to protect the cartridge. Decrease of estrogen due to menopause makes the cartridge easy to damage, resulting in being difficult to make proteoglycan.