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Disease & Conditions

 
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Arthritis (Condition)

What is arthritis?

Arthritis and other rheumatic diseases are characterized by pain, swelling, and limited movement in joints and connective tissues in the body. According to the Centers for Disease Control and Prevention, nearly 47 million people in the US have some form of arthritis or chronic joint symptoms.

Arthritis, which literally means inflammation of a joint (where two or more bones meet), actually refers to more than 100 different diseases. Rheumatic diseases include any diseases that cause pain, stiffness, and swelling in joints or other supportive body structures, such as muscles, tendons, ligaments, and bones.

Arthritis and other rheumatic diseases are often mistakenly associated with old age, because osteoarthritis (the most common form of arthritis) occurs more often among elderly persons. However, arthritis and other rheumatic diseases affect people of all ages.

Arthritis is usually chronic, which means that it rarely changes, or it progresses slowly. Specific causes for most forms of arthritis are not yet known.

What are the parts of a joint?

Joints are the areas where two bones meet. Most joints are mobile, allowing the bones to move. Joints consist of the following:

    * cartilage - a type of tissue that covers the surface of a bone at a joint. Cartilage helps reduce the friction of movement within a joint.

     
    * synovial membrane - a tissue called the synovial membrane lines the joint. The synovial membrane secretes synovial fluid (a clear, sticky fluid) around the joint to lubricate it.

     
    * ligaments - strong ligaments (tough, elastic bands of connective tissue) surround the joint to give support and limit the joint's movement.

     
    * tendons - tendons (another type of tough connective tissue) on each side of a joint attach to muscles that control movement of the joint.

     
    * bursas - fluid-filled sacs, called bursas, between bones, ligaments, or other adjacent structures help cushion the friction in a joint.

     
    * femur - the thighbone.

     
    * tibia - the shin bone.

     
    * patella - the kneecap.

      
    *  meniscus - a curved part of cartilage in the knees and other joints.