Osteoarthritis is the most common form of arthritis. It causes pain, swelling, and reduced motion in your joints. It can occur in any joint, but usually it affects your hands, knees, hips or spine.

Osteoarthritis breaks down the cartilage in your joints. Cartilage is the slippery tissue that covers the ends of bones in a joint. Healthy cartilage absorbs the shock of movement. When you lose cartilage, your bones rub together. Over time, this rubbing can permanently damage the joint.

Risk factors for osteoarthritis include

• Being overweight
• Getting older
• Injuring a joint

No single test can diagnose osteoarthritis. Most doctors use several methods, including medical history, a physical exam, x-rays, or lab tests.

Treatments include exercise, medicines, and sometimes surgery.

Rheumatoid arthritis (RA) is a form of arthritis that causes pain, swelling, stiffness and loss of function in your joints. It can affect any joint but is common in the wrist and fingers.

More women than men get rheumatoid arthritis. It often starts in middle age and is most common in older people. You might have the disease for only a short time, or symptoms might come and go. The severe form can last a lifetime.

Rheumatoid arthritis is different from osteoarthritis, the common arthritis that often comes with older age. RA can affect body parts besides joints, such as your eyes, mouth and lungs. RA is an autoimmune disease, which means the arthritis results from your immune system attacking your body’s own tissues.

No one knows what causes rheumatoid arthritis. Genes, environment, and hormones might contribute. Treatments include medicine, lifestyle changes, and surgery. These can slow or stop joint damage and reduce pain and swelling.

Juvenile arthritis (JA) is arthritis that happens in children. It causes joint swelling, pain, stiffness, and loss of motion. It can affect any joint, but is more common in the knees, hands, and feet. In some cases it can affect internal organs as well.

The most common type of JA that children get is juvenile idiopathic arthritis. There are several other forms of arthritis affecting children.

One early sign of JA may be limping in the morning. Symptoms can come and go. Some children have just one or two flare-ups. Others have symptoms that never go away. JA can cause growth problems and eye inflammation in some children.

No one knows exactly what causes JA. Most types are autoimmune disorders. This means that your immune system, which normally helps your body fight infection, attacks your body’s own tissues.

JA can be hard to diagnose. Your health care provider may do a physical exam, lab tests, and x-rays. A team of providers usually treats JA. Medicines and physical therapy can help maintain movement and reduce swelling and pain. They may also help prevent and treat complications.

Most kinds of arthritis cause pain and swelling in your joints. Joints are places where two bones meet, such as your elbow or knee. Infectious arthritis is an infection in the joint. The infection comes from a bacterial, viral, or fungal infection that spreads from another part of the body. Symptoms of infectious arthritis include

• Intense pain in the joint
• Joint redness and swelling
• Chills and fever
• Inability to move the area with the infected joint

One type of infectious arthritis is reactive arthritis. The reaction is to an infection somewhere else in your body. The joint is usually the knee, ankle, or toe. Sometimes, reactive arthritis is set off by an infection in the bladder, or in the urethra, which carries urine out of the body. In women, an infection in the vagina can cause the reaction. For both men and women, it can start with bacteria passed on during sex. Another form of reactive arthritis starts with eating food or handling something that has bacteria on it.

To diagnose infectious arthritis, your health care provider may do tests of your blood, urine, and joint fluid. Treatment includes medicines and sometimes surgery.

Psoriasis is a skin disease that causes itchy or sore patches of thick, red skin with silvery scales. You usually get them on your elbows, knees, scalp, back, face, palms and feet, but they can show up on other parts of your body.

Some people with psoriasis have psoriatic arthritis. It causes pain, stiffness, and swelling of the joints. It is often mild, but can sometimes be serious and affect many joints. The joint and skin problems don’t always happen at the same time.

Your doctor will do a physical exam and imaging tests to diagnose psoriatic arthritis. There is no cure, but medicines can help control inflammation and pain. In rare cases, you might need surgery to repair or replace damaged joints.

Gout is a common, painful form of arthritis. It causes swollen, red, hot and stiff joints.

Gout happens when uric acid builds up in your body. Uric acid comes from the breakdown of substances called purines. Purines are in your body’s tissues and in foods, such as liver, dried beans and peas, and anchovies. Normally, uric acid dissolves in the blood. It passes through the kidneys and out of the body in urine. But sometimes uric acid can build up and form needle-like crystals. When they form in your joints, it is very painful. The crystals can also cause kidney stones.

Often, gout first attacks your big toe. It can also attack ankles, heels, knees, wrists, fingers, and elbows. At first, gout attacks usually get better in days. Eventually, attacks last longer and happen more often.

You are more likely to get gout if you

• Are a man
• Have family member with gout
• Are overweight
• Drink alcohol
• Eat too many foods rich in purines

Gout can be hard to diagnose. Your doctor may take a sample of fluid from an inflamed joint to look for crystals. You can treat gout with medicines.

Pseudogout has similar symptoms and is sometimes confused with gout. However, it is caused by calcium phosphate, not uric acid.