Rheumatoid arthritis (RA) is an autoimmune disease that has a host of debilitating symptoms, including fatigue, joint pain, swelling, and stiffness of affected joints. With RA, the immune system attacks the body's own joint tissues, resulting in inflammation, which can cause progressive damage to affected joints. The inflammation caused by RA usually affects specific joints and organs and sometimes causes skin and tendon problems. Two common areas affected by RA are the hands and feet, which can develop joint contractures and deformity over time. RA symptoms and effects on the body will vary from one person to the next -- some RA sufferers may develop joint problems to more of a degree than others.
Foot Problems That Can Occur with Rheumatoid Arthritis
- Joint Damage
When RA flares up, the fluid within a joint and the joint lining, known as the synovium, becomes acutely inflamed (synovitis). This inflammation is what causes the characteristic RA symptoms: a warm and swollen joint.
What distinguishes RA from the more common osteoarthritis (OA) is that multiple joints are usually affected at the same time with RA and the joint symptoms are generally symmetrical, occurring on both sides of the body equally. Another feature that distinguishes RA from OA is the tendency for RA to cause a longer period of morning stiffness. An RA sufferer will often experience stiffness in affected joints for 1-2 hours after awakening, compared with an OA sufferer, whose joint stiffness may diminish after a few minutes of stretching or motion in the morning.
When it come to the feet, RA typically affects the metatarsophalangeal (MTP) joints of the toes, resulting in a gradual deformity of the toes on both feet. Subsequent flares and chronic inflammation may cause progressive damage to joint structures, eroding cartilage and bone, which results in decreased range of motion and joint deformity. When RA persistently affects the MTP joints of the feet, a gradual outward (lateral) shift in the toes can occur. This causes both feet to develop bunions (hallux valgus). The shifting of the forefoot and loss of stability also causes toe contractures, such as hammertoes. Toe contractures and changes in toe joint flexibility will often lead to calluses and pain beneath the ball of the foot. All of these changes to a foot's structure and shape can make finding a comfortable shoe more difficult for an RA sufferer.
Other joints of the foot that can be affected by RA are the ankle joint and the talonavicular joint, which is part of the foot's arch. When the talonavicular joint is affected, the foot can become destabilized and flat feet (pes planus) can develop.
- Heel Pain
Heel pain is a common recurring problem for RA sufferers and can occur at the back of the heel or on the underside. Conditions associated with heel pain include plantar fasciitis (heel spur syndrome), Achilles tendonitis, and retrocalcaneal bursitis. Retrocalcaneal bursitis occurs when a fluid-filled sac (bursa) behind the heel bone becomes inflamed, causing pain and swelling.
- Nerve entrapments
RA causes inflammation of joint lining (synovitis) and fluid, which are present in joints and surround certain tendons. The swelling that occurs with synovitis can compress nerves, causing symptoms of a pinched nerve, also known as a nerve entrapment. One common nerve entrapment in the foot is called tarsal tunnel syndrome. Symptoms of tarsal tunnel syndrome include burning, tingling, or shooting pain in the area of the foot's arch and sole.
- Skin Problems
Some RA sufferers may develop rheumatoid nodules. A rheumatoid nodule appears as a lump beneath the skin, usually over a bony prominence or tendon. In the foot, a rheumatoid nodule may appear over the Achilles tendon or on the side of the big toe if a bunion (hallux valgus) is present.
The inflammation associated with RA can affect small blood vessels, which in turn can cause certain skin manifestations, including rashes or wounds on the lower legs. Another skin finding associated with RA is splinter hemorrhages, which are small areas of broken blood vessels that are usually seen on the sides of fingernails or toenails.
Dockery, DPM, Gary L. and Crawford, DPM, Mary Elizabeth (Ed.). Cutaneous Disorders of the Lower Extremity. Philadelphia: W.B. Saunders, 1997. 193-194.
Schumacher, Jr., MD, H. Ralph, Ed, Klippel, MD, John H., Assoc. Ed, and William J. Koopman, MD, Assoc. Ed. Primer on the Rheumatic Diseases. Tenth Ed. Atlanta: Arthritis Foundation, 1993; 209-215. 93-94.