When people get older, their cartilage slowly degenerates through tear and wear. This might lead to osteo-arthritis, which is disorder in the joints, characterised most bij pain and stiffness in the joints. You must not confuse this condition with osteoporosis, which is characterised by brittle bones of low mineral density. Glucosamine in its natural form exists in all of our joints and muscles. It's also important in the everyday mobility and smooth working of tendons, cartilage and ligaments. It's one of the most important building blocks of the structure of cartilage, which is formed by complex proteins.