What is rheumatoid arthritis? Rheumatoid arthritis (RA) is a chronic (long-lasting) disease that mostly affects joints, such as the wrist, hands, feet, spine, knees, and jaw. In joints, RA causes inflammation that leads to: Pain. Swelling Stiffness. Loss of function. Rheumatoid arthritis is an autoimmune disorder because the immune system attacks the healthy joint tissues. Normally, the immune system helps protect the body from infection and disease. RA may cause you to feel unusually tired, to have occasional fevers, and to have a loss of appetite. It also may cause other medical problems in the heart, lungs, blood, nerves, eyes

What is arthritis? "Arthritis" literally means joint inflammation. Although joint inflammation is a symptom or sign rather than a specific diagnosis, the term arthritis is often used to refer to any disorder that affects the joints. Joints are places where two bones meet, such as your elbow or knee. There are different types of arthritis. In some diseases in which arthritis occurs, other organs, such as your eyes, heart, or skin, can also be affected. Fortunately, current treatments allow most people with arthritis to lead active and productive lives.

What is osteonecrosis? Osteonecrosis is a bone disease. It results from the loss of blood supply to the bone. Without blood, the bone tissue dies. This causes the bone to collapse. It may also cause the joints that surround the bone to collapse. If you have osteonecrosis, you may have pain or be limited in your physical activity. Osteonecrosis can develop in any bone, most often in the: Thigh bone (femur). Upper arm bone (humerus). Knees. Shoulders. Ankles. It is also called: Avascular necrosis. Aseptic necrosis. Ischemic necrosis.

What is alopecia areata? Alopecia areata is a disease that attacks your hair follicles (the part of your skin that makes hair). In most cases, hair falls out in small, round patches about the size of a quarter. This causes only a few bare patches. Some people may lose more hair. In only a few people, the disease causes total loss of hair on the head or loss of all body hair. Your hair may grow back, even if you lose all of it. But it may fall out again. No one can tell you when it might fall out

What are heritable disorders of connective tissue? There are more than 200 heritable disorders of connective tissue that can affect the tissues between the cells of your body that give tissues form and strength. All of these diseases are directly related to problems in genes that are responsible for building connective tissues. The disorders are called “heritable,” because they are passed on from parent to child. Some heritable disorders of connective tissue change the look and growth of skin, bones, joints, heart, blood vessels, lungs, eyes, and ears. Others change how these tissues work. Many, but not all, are rare

What are sports injuries? Sports injuries are injuries that happen when playing sports or exercising. There are two kinds of sports injuries: Acute injuries occur suddenly when playing or exercising. For example: Sprained ankles. Strained backs. Broken bones. Chronic injuries happen after you play a sport or exercise for a long time.

What are sprains and strains? A sprain is an injury to a ligament (tissue that connects two or more bones at a joint). When a sprain happens, one or more ligaments is stretched or torn. A strain is an injury to a muscle or tendon (fibrous cords of tissue that connect muscle to bone). In a strain, a muscle or tendon is stretched or torn.

What is fibrous dysplasia? Fibrous dysplasia happens when abnormal fibrous (scar-like) tissue replaces healthy bone. The fibrous tissue weakens the bone over time, which can lead to: Broken bones. Bones that are misshapen (bowed or crooked). The disease can affect any bone in the body. Some people have no symptoms or only a few symptoms. Other people may have more symptoms. Although there is no cure for fibrous dysplasia, treatments may help to lessen pain, and physical therapy may help strengthen muscle and improve movement.

What is ankylosing spondylitis? Ankylosing spondylitis is a type of arthritis that causes inflammation in certain parts of the spine. Over time, this inflammation in the joints and tissues of the spine can cause stiffness. In severe cases, this may cause the bones in the spine to grow together, which can lead to a rigid spine that is difficult to bend. Many people with ankylosing spondylitis have mild episodes of back pain and stiffness that come and go. But others have severe, ongoing back pain and stiffness. Other symptoms also may develop if other areas of the body are affected

What is osteoporosis? Osteoporosis is a disease that causes bones to become weak and brittle. This increases your risk of broken bones (fractures). Osteoporosis is a “silent” disease because you may not have symptoms. You may not even know you have the disease until you break a bone. Breaks can occur in any bone but happen most often in: Hip bones. Vertebrae in the spine. Wrist. You can take steps to help prevent osteoporosis and broken bones by: Doing weight-bearing exercises, such as walking or dancing, and lifting weights. Not drinking too much alcohol. Quitting smoking, or not starting if

What are knee problems? Knee problems happen when you injure or develop disease in your knee and it can’t do its job. The knees provide stable support for the body. They also allow your legs to bend and straighten. Both flexibility and stability are needed to stand, walk, run, crouch, jump, and turn. Other parts of your body help the knees do their job. These are: Bones. Cartilage. Muscles. Ligaments. Tendons.