According to Medical News Today, RA causes the body’s immune system to attack the synovium, which lines the joints. The synovium produces a fluid that helps the joints move more smoothly.
When the immune system attacks the synovium, it often results in inflammation and swelling. Sometimes inflammation of the synovium membrane leads to swelling, other times too much synovial fluid in the joints causes the problem.
Sometimes, swelling can be severe. For example, a person’s hand can become so swollen that it looks like a boxing glove. Excessive swelling can cause a reduced range of motion.
Over time, the continued swelling and inflammation can also weaken ligaments in the joints. This weakening can lead to deformities of the feet and hands, such as claw toe or hammer toe. However, these are late symptoms of RA.
What areas does swelling affect?
Swelling caused by RA commonly affects joints in the following areas:
The swelling in RA usually occurs in joints on both sides of the body. This is different from osteoarthritis, which generally affects a single joint.
In 20 percent of cases, foot and ankle symptoms are the first to appear.