Osteoarthritis is a chronic condition that affects the joints and can cause pain, stiffness, and limited movement. While it is not a disease, it is a natural part of the aging process.

The causes of osteoarthritis are unknown. It may be due to a direct injury to the joint, or it may be the result of a systemic or metabolic disease. It may also be caused by a joint injury that is repeated or chronic.

The pain associated with osteoarthritis is often dull, intermittent, and worst after activity. It can be reduced by rest and physical therapy.

This is because the knee, for example, may feel good when flexed and the pain goes away when the leg is raised.