Final answer:
Osteoarthritis is a joint disease that occurs when joint cartilage and bone break down. It is characterized by symptoms like joint pain and stiffness. The condition is caused by mechanical stress on the joints and a lack of self-repair of cartilage.
Step-by-step explanation:
Osteoarthritis (OA) is a joint disease that results from the breakdown of joint cartilage and bone. The most common symptoms are joint pain and stiffness. OA is thought to be caused by mechanical stress on the joints with insufficient self-repair of cartilage, coupled with low-grade inflammation of the joints.