Osteoarthritis (OA) also known as degenerative arthritis, degenerative joint disease, or osteoarthrosis, is a type of joint disease that results from breakdown of joint cartilage and underlying bone. The most common symptoms are joint pain and stiffness. Initially, symptoms may occur only following exercise, but over time may become constant. Other symptoms may include joint swelling, decreased range of motion, and when the back is affected weakness or numbness of the arms and legs. The most commonly involved joints are those near the ends of the fingers, at the base of the thumb, neck, lower back, knees, and hips. Joints on one side of the body are often more affected than those on the other. Usually the problems come on over years. It can affect work and normal daily activities. Unlike other types of arthritis, only the joints are typically affected.

Causes include previous joint injury, abnormal joint or limb development, and inherited factors. Risk is greater in those who are overweight, have one leg of a different length, and have jobs that result in high levels of joint stress. Osteoarthritis is believed to be caused by mechanical stress on the joint and low grade inflammatory processes. It develops as cartilage is lost with eventually the underlying bone becoming affected. As pain may make it difficult to exercise, muscle loss may occur. Diagnosis is typically based on signs and symptoms with medical imaging and other tests occasionally used to either support or rule out other problems. Unlike in rheumatoid arthritis, which is primarily an inflammatory condition, the joints do not typically become hot or red.

Treatment includes exercise, efforts to decrease joint stress, support groups, and pain medications. Efforts to decrease joint stress include resting, the use of a cane, and braces. Weight loss may help in those who are overweight. Pain medications may include paracetamol (acetaminophen). If this does not work NSAIDs such as naproxen may be used, but these medications are associated with greater side effects. Opioids if used are generally only recommended short term due to the risk of addiction. If pain interferes with normal life despite other treatments, joint replacement surgery may help. An artificial joint, however, only lasts a limited amount of time. Outcomes for most people with osteoarthritis are good.

OA is the most common form of arthritis with disease of the knee and hip affecting about 3.8% of people as of 2010. Among those over 60 years old about 10% of males and 18% of females are affected. It is the cause of about 2% of years lived with disability. In Australia about 1.9 million people are affected, and in the United States about 27 million people are affected. Before 45 years of age it is more common in men, while after 45 years of age it is more common in women. It becomes more common in both sexes as people become older.

by wikipedia