Rheumatoid arthritis (RA) is an autoimmune disease. This means that the immune system attacks its own tissues. In RA, the defenses that protect the body from infection instead damage normal tissue (such as cartilage and ligaments) and soften bone.
What Happens to Your Joints When You Have RA
The joints of your body are covered with a lining—called synovium—that lubricates the joint and makes it easier to move. Rheumatoid arthritis causes overactivity of this lining. It swells and becomes inflamed, destroying the joint, as well as the ligaments and other tissues that support it. Weakened ligaments can cause joint deformities—such as claw toe or hammer toe. Softening of the bone (osteopenia) can result in stress fractures and collapse of bone.
Rheumatoid arthritis is not an isolated disease of the bones and joints. It affects tissues throughout the body, causing damage to the blood vessels, nerves, and tendons. Deformities of the hands and feet are the more obvious signs of RA. In about 20% of patients, foot and ankle symptoms are the first signs of the disease.
Causes and Symptoms of Rheumatoid Arthritis
The exact cause of RA is not known. There may be a genetic reason—some people may be more likely to develop the disease because of family heredity. However, doctors suspect that it takes a chemical or environmental "trigger" to activate the disease in people who genetically inherit RA. The most common symptoms are pain, swelling, and stiffness. Unlike osteoarthritis, which typically affects one specific joint, symptoms of RA usually appear in both feet, affecting the same joints on each foot.
Your feet and ankles can be affected by RA in the following ways:
- Ankles. Difficulty with inclines (ramps) and stairs are the early signs of ankle involvement. As the disease progresses, simple walking and standing can become painful.
- Hindfoot. The main function of the hindfoot—or heel region of the foot—is to perform the side-to-side motion of the foot. Difficulty walking on uneven ground, grass, or gravel are the initial signs. Pain is common just beneath the fibula (the smaller lower leg bone) on the outside of the foot. As the disease progresses, the alignment of the foot may shift as the bones move out of their normal positions. This can result in a flatfoot deformity. Pain and discomfort may be felt along the posterior tibial tendon (main tendon that supports the arch) on the inside of the ankle, or on the outside of the ankle beneath the fibula.
- Midfoot. With RA, the ligaments that support the midfoot become weakened and the arch collapses. With loss of the arch, the foot commonly collapses and the front of the foot points outward. RA also damages the cartilage, causing arthritic pain that is present with or without shoes. Over time, the shape of the foot can change because the structures that support it degenerate. This can create a large bony prominence (bump) on the arch. All of these changes in the shape of the foot can make it very difficult to wear shoes.
Treatment From a Podiatrist for Foot & Ankle RA
Rheumatoid arthritis is a chronic condition. To ease pain and discomfort in your feet, your podiatrist will start by recommending rest, ice, nonsteroidal anti-inflammatory medication, orthotics, braces, and steroid injections. Your doctor may recommend surgery depending on the extent of cartilage damage and your response to nonsurgical options.