Osteoarthritis occurs when the cartilage that cushions the ends of bones in your joints gradually deteriorates. Cartilage is a firm, slippery tissue that enables nearly frictionless joint motion.
Eventually, if the cartilage wears down completely, bone will rub on bone. Osteoarthritis has often been referred to as a wear and tear disease. But besides the breakdown of cartilage, osteoarthritis affects the entire joint. It causes changes in the bone and deterioration of the connective tissues that hold the joint together and attach muscle to bone. It also causes inflammation of the joint lining.
Older age: The risk of osteoarthritis increases with age.
Obesity: Carrying extra body weight contributes to osteoarthritis in several ways, and the more you weigh, the greater your risk.
Joint injuries: Injuries, such as those that occur when playing sports or from an accident, can increase the risk of osteoarthritis.
Repeated stress on the joint: If your job or a sport you play places repetitive stress on a joint, that joint might eventually develop osteoarthritis.
Bone deformities: Some people are born with malformed joints or defective cartilage.
Certain metabolic diseases: These include diabetes and a condition in which your body has too much iron (hemochromatosis).
Courtesy: Mayo Clinic