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.[1] 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.[2]

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.[2][3] Osteoarthritis is believed to be caused by mechanical stress on the joint and low grade inflammatory processes.[4] It develops as cartilage is lost with eventually the underlying bone becoming affected.[2] As pain may make it difficult to exercise, muscle loss may occur.[3][5] Diagnosis is typically based on signs and symptom 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.[2]

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.[2] 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.[3] Outcomes for most people with osteoarthritis are good.[2]

OA is the most common form of arthritis with disease of the knee and hip affecting about 3.8% of people as of 2010.[2][6] Among those over 60 years old about 10% of males and 18% of females are affected.[3] It is the cause of about 2% of years lived with disability.[6] In Australia about 1.9 million people are affected,[7] and in the United States about 27 million people are affected.[2] 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.[2]

The main symptom is pain, causing loss of ability and often stiffness. "Pain" is generally described as a sharp ache or a burning sensation in the associated muscles and tendons. OA can cause a crackling noise (called "crepitus") when the affected joint is moved or touched and people may experience muscle spasms and contractions in the tendons. Occasionally, the joints may also be filled with fluid.[8] Some people report increased pain associated with cold temperature, high humidity, and/or a drop in barometric pressure, but studies have had mixed results.[9]

OA commonly affects the hands, feet, spine, and the large weight bearing joints, such as the hips and knees, although in theory, any joint in the body can be affected. As OA progresses, the affected joints appear larger, are stiff and painful, and usually feel better with gentle use but worse with excessive or prolonged use, thus distinguishing it from rheumatoid arthritis.

In smaller joints, such as at the fingers, hard bony enlargements, called Heberden's nodes (on the distal interphalangeal joints) and/or Bouchard's nodes (on the proximal interphalangeal joints), may form, and though they are not necessarily painful, they do limit the movement of the fingers significantly. OA at the toes leads to the formation of bunions, rendering them red or swollen. Some people notice these physical changes before they experience any pain.

OA is the most common cause of a joint effusion of the knee.[10]

Damage from mechanical stress with insufficient self repair by joints is believed to be the primary cause of osteoarthritis.[11] Sources of this stress may include misalignments of bones caused by congenital or pathogenic causes; mechanical injury; excess body weight; loss of strength in the muscles supporting a joint; and impairment of peripheral nerves, leading to sudden or uncoordinated movements.[11] However exercise, including running in the absence of injury, has not been found to increase the risk.[12] Nor has cracking one's knuckles been found to play a role.[13]

A number of studies have shown that there is a greater prevalence of the disease among siblings and especially identical twins, indicating a hereditary basis.[14] Although a single factor is not generally sufficient to cause the disease, about half of the variation in susceptibility has been assigned to genetic factors.[15]

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Osteoarthritis - Wikipedia, the free encyclopedia

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