The foot (along with the ankle) is both mechanically and structurally complex, containing over 20 bones and 30 joints, along with the many muscles, tendons, and ligaments that connect them and allow for movement and function. The foot is divided into 3 regions, including the forefoot, mid-foot, and rear- or hind-foot. When RA affects the joints of the foot, it can make a range of common activities, including basic ambulation (walking), difficult or impossible. This can lead to significant disability.
As is true with RA and joints throughout the body, the sooner diagnosis is made and treatment initiated, the greater the likelihood that joint damage can be minimized or prevented. The availability of disease-modifying anti-rheumatic drugs (DMARDs) and newer biologics that are effective at slowing or preventing structural damage to the joints means that the joints and other structures that make up the foot can often be preserved and function maintained.
How does RA affect the foot?
The feet, similar to the hands, are often affected in the early stages of RA. Approximately 13% of RA patients will have foot symptoms as the first signs of RA and 90% of patients will have foot involvement at some point in the course of RA.1
In RA, the top of the foot may become red and swollen. Joints at the base of the toes (between the phalanx and metatarsal bones) may become tender, making it painful to walk and causing the patient to shift weight to the heel and bend the toes upward while standing or walking. Joint erosion resulting from chronic inflammation may lead to migration or drift of toes towards the side of foot. Changes to the forefoot that are common in patients with RA include bunions, claw toes, “cock-up” deformity of the fifth toe (the small toe), and pain affecting the ball of the foot. In some patients, the heel may also become painful.2,3
How is RA-related foot involvement treated?
Treatment of RA symptoms affecting the foot depends on the severity of symptoms and the nature and extent of damage, as well as the patient’s goals and needs. Options include drug and non-drug treatments, and surgery.3
Drug treatments. The initial approach to treatment should involve medications to control inflammation and pain (including analgesics [NSAIDs], disease-modifying anti-rheumatic drugs [DMARDs], and glucocorticoid injection).3
Injection of glucocorticoids directly into affected joints in the foot may be useful in controlling acute inflammation. However, glucocorticoids will not prevent progression of the disease and structural damage to joints.3
Non-drug management approaches. Rest and/or restricted activity and application of cold (ice) for 20 to 30 minutes 3 to 4 times per day may be used to provide relief of acute pain. Application of cold may be most useful following physical activity. Do not apply ice directly to your skin.3
Use of custom orthotics made of soft, flexible material that insert into your shoe may provide relief from pressure and pain related to shifting of bones in your feet and formation of calluses, especially those affecting the forefoot and mid-foot.3 Consult with a podiatrist to have custom orthotics made specifically for your needs.
Use of a lace-up brace that provides support to the back of the foot and ankle may be effective in relieving pain in the back of the foot. A custom-made plastic molded or leather brace may be required in some patients.3
Surgery. If joint symptoms do not respond to medication or other management approaches, surgical interventions may be used. Surgical options include fusion of affected joints. This approach involves removal of the joint and fusion of two bones to one another. Other surgical options (mainly available for the front of the foot) include procedures that correct joint damage (eg. hammertoes) and spare joints.3
Hind-foot. Fusion of the joints of the hind-foot is designed to eliminate side-to-side movement, while sparing to some degree up-and-down movement. The number of joints that require fusion depends on how many are affected by RA-related inflammation.3
Mid-foot. Fusion of mid-foot joints can be used to restore the normal arch of the foot and decrease changes in the shape of the foot that have resulted from damage to joints. The goal is to reduce pain and allow the patient to wear normal shoes. Replacements are available for joints in the outside of the mid-foot and may be used to preserve some degree of mid-foot motion.3
Forefoot. Choice of surgical treatment for the toes and ball of the foot to correct deformities including bunion, claw toes, or hammer toes, depends on the nature and extent of joint damage. If damage is less severe, joint sparing procedures may be used that will preserve motion. For the big toe, fusion of joints may be used if there is significant cartilage damage. In cases of significant deformity, surgery involving fusion of selected joints, removal of bone, cutting of tendons, and insertion of implants or pins to straighten toes may be used to restore the normal shape of the foot.3