Rheumatoid arthritis frequently affects the joints of the foot and ankle; commonly the joints that connect the toes to the foot (called the metatarsophalangeal joint or MTP joint). This is what we usually call the ball of the foot. And it can also affect the smaller joints of the toes. Similar to other joints, RA can cause synovitis in the MTP joints, causing pain, swelling and joint erosion and deformity eventually making it difficult to stand, walk and to wear shoes comfortably. Since the big toe and the fifth toe to tend to bear the most pressure, these joints are the most often affected. In children, RA in the joints of the foot causes similar pain, swelling and joint deformities that also affect the proper bone growth and development of the joints.
In fact, studies have shown that 90% of people with RA have painful feet or ankles at some point during the course of their disease. Other studies have varied about how many joints are affected and how severely. In the November issue of Arthritis & Rheumatism, researchers in the Netherlands recently published a study of the prevalence and course of foot impairments and walking disability in people in the first eight years of having RA. The study included 848 adults over 18 with recent onset RA from 1995 through the present. Overall, the study determined that the prevalence of pain, swelling and walking disability is initially high in early onset RA (about 70%). Then after about 2 years, the numbers of people reporting these problems stabilizes at 40-50%. Fifty-seven percent had walking disability in the first year of diagnosis. That number decreased to 40% after the first year. However, about 60% of the participants developed joint erosions in one or more joints over the eight year period and over time those erosions increased in severity.
It's important to note that biologic drugs weren't introduced until 2001; six years after this study began. The authors noted that more aggressive treatment with these drugs for participants in later years of the study may have affected the frequency of foot impairments and walking disability. They also cautioned that improvement in foot impairments doesn't necessarily result in an improvement in walking disability, since walking involves many more joints.
Treatment options for RA in the feet
As with treatment for RA overall, treatment for foot involvement generally begins with anti-inflammatory medications and/or biologic drugs to reduce pain and swelling and to attempt to slow down the progression of the disease. Injections of drugs like cortisone can offer temporary relief to a targeted joint.
For getting around everyday, it is helpful to find comfortable shoes or shoe inserts that reduce the pressure on the toes with cushioning or reducing the amount of bend in the toe during walking. Both brand-name (like Dansko clogs) and custom-made options offer a rocker type of sole or metal braces in the sole that absorb some of the force and reduce the amount the toes need to bend.
