When cartilage in a joint deteriorates, osteoarthritis develops. In the early stages of the disease the surface of the cartilage becomes swollen and there is a loss of other tissue parts. Fissures and pits appear in the cartilage and as the disease progresses and more tissue is lost, the cartilage loses elasticity and becomes increasingly prone to damage due to repetitive use and injury. Eventually, large amounts of cartilage are destroyed, leaving portions of the bone or joint unprotected.