With 10 million or more people with arthritis, the majority of them will have degenerative arthritis. This arthritis is called Osteoarthritis. Degenerative arthritis occurs when joints are overworked, rub against each other, experience excess friction, and slowly degenerate.
Most joints rub against each other, but bone joints have a protective layer called cartilage. This cartilage has no blood vessels or nerves so it cannot receive nutrients directly. This cartilage serves as a cushion or pad between bones so that bones don't wear out and so you don't feel pain.