Chronic degeneration, also known as degenerative joint disease, of the cartilage in the joint cavity leads to osteoarthritis, which primarily affects the knees, hips, hands, feet, and spine.
Cartilage provides a cushion between the bones at joint locations. As the cartilage wears down, bone may eventually rub against bone. When the cartilage deteriorates, the body attempts to repair the loss, often by creating new areas of bone along the edges of existing bone (bone spurs or osteophytes). Primary osteoarthritis is most common in the elderly. Secondary causes of osteoarthritis include repetitive stress injuries, trauma, chronic gout, and poor posture leading to misalignment of bones.