Rheumatoid arthritis is an autoimmune disease in which the body’s defence mechanisms are triggered to attack its own joints, even though there is no apparent cause. The immune system attacks the synovial joints of an otherwise healthy person and sometimes even other parts of the body. Once started it usually occurs in a symmetrical pattern, and can affect the joints in the hands, knees, ankles, feet, hips, elbows, and shoulders. Osteoarthritis is where it causes the cartilage on the end of the bones to get rougher and thinner and they develop wear and tear.
Rheumatoid Arthritis in the Knee
Rheumatoid arthritis of the knee causes the joints to become tender, warm, and swollen. Although knee osteoarthritis causes pain and stiffness, joint pain with rheumatoid arthritis of the knee is more severe. The knee is formed by what is called a synovial joint, the term synovial refers to the tissue involved. Normally, this synovium lies between the two pieces of joint cartilage. It acts as a supportive cavity lined by a membrane. The synovial membrane secretes synovial fluid, which provides lubrication for the highly mobile joint. Cartilage is the material that covers the ends of joint bones and it this cartilage that keeps the bones from rubbing against each other during movement. The rheumatoid arthritis condition ends up destroying firstly the synovial part of the joint, resulting in there being no lubrication and the cartilage rubs together. Friction over a length of time will break down the cartilage resulting in the bone itself becoming worn, fractured and ultimately collapsing forming a single unit of bone. This is now called advanced osteoporosis and where joint extension is now impossible.
Rheumatoid Arthritis in the Finger Joints
The condition follows the same pattern as the knee in the finger joints, as the fingers are also synovial joints. The synovium membrane is attacked by the body’s own immune system, resulting in a swollen joint capsule, which is the cause of the external swelling, reduced synovial fluid and inflammation of the tendon sheath. This leads to the characteristic inflammation and pain in the hands especially the knuckles and second joints.