With rheumatoid arthritis (RA), the immune system attacks healthy joints—and those in the feet don't escape the effects. Joint lining becomes inflamed, causing pain, swelling, and redness. And, over time, relentless inflammation can damage the cartilage and bones of the feet, leading to foot deformity.
An estimated 20% of people with RA first experience joint problems in the feet, and 90% of patients go on to develop foot and ankle problems over the course of their disease.1
Treating foot problems early can help prevent serious, permanent damage and thwart not only foot deformity, but disability. Foot Anatomy
The human foot is a complex marvel of bones and joints supported by muscles, tendons, and ligaments. Nearly one-fourth of the body’s bones are found in the feet providing the architecture for balance and mobility.3
Each foot has 26 bones. Bones of the foot include:3
Talus: The bone on top of the foot, it forms a joint with the tibia and fibula on the lower leg.
Calcaneus: Located beneath the talus, this is the heel bone, which is the largest bone of the foot.
Tarsals: These five irregularly shaped bones in the middle of the foot make up the arch and include the cuboid, navicular, medial, intermediate, and lateral cuneiforms.
Metatarsals: These are the five bones that make up the forefoot.
Phalanges: The bones in the toes, each toe has three phalanges, except the big toe, which has two.
Sesamoids: Two small, pea-shaped bones below the first metatarsal that make up the ball of the foot.
When two or more of these bones meet, they form a joint. The bone surfaces at the joints are covered with cartilage and the joints are enclosed in a fibrous capsule lined with a thin membrane known as synovium, which secretes a fluid that lubricates joints.3
The foot is divided into three regions that work interdependently:1
Hindfoot: The part of the foot that attaches the leg and includes the talus and calcaneus bones.
Midfoot: The middle of the foot that includes the tarsal bones that make up the arch.
Forefoot: The front of the foot which includes the toes and metatarsals.
As you walk or run, your foot goes through a cycle of pronation (foot rolls inward) and supination (foot rolls outward) which allows the foot to adjust to uneven surfaces and absorb shock, followed by propelling forward movement.
Skin abnormalities (corns and calluses)
RA involving the forefoot can lead to dislocation of the metatarsophalangeal (MTP) joints, clawing of the toes (hammertoes), and bunions (hallux valgus). Around the hindfoot, soft tissue problems such as plantar fasciitis, peroneal tendonitis, or bursitis. Rheumatoid nodules can form at the Achilles' tendon commonly occur
Rheumatoid nodules at the Achilles' tendon commonly occur.
If you have RA and are experiencing foot problems, see your doctor who can often diagnose problems with a visual and physical examination. Your doctor will observe your foot and ankle and palpate the area to check for swelling and tenderness.2
A visual examination in a standing position can identify abnormalities of the ankle, hindfoot, arch, and forefoot. A visible spreading of the toes indicates swollen metatarsophalangeal joints, which will also be tender to the touch.
An interior view while bearing weight can reveal arch problems such as a collapsed arch or flat foot (pes planus) or high arch (pes cavus). A view from behind can reveal a valgus deformity of the ankle and hindfoot, where the foot appears twisted outward.2
Your doctor will also check the range of motion of the ankle and hindfoot and palpate for swelling and tenderness around the ankle, Achilles tendon, and heel, which may indicate synovitis.
Imaging tests including X-rays, computed tomography (CT) scan, and magnetic resonance imaging (MRI) scans may be used to differentiate between rheumatoid arthritis and other causes.
Other types of arthritis that can cause foot pain include:4
Regardless of the specific type of foot pain you are experiencing, RA is treated with disease-modifying anti-rheumatic drugs (DMARDs), which address the underlying causes of inflammation, slow disease progression, and help to prevent future damage and deformity.5
In addition, RA foot problems are treated with a combination of pain relievers and steroids. Ice or heat may also be used to ease the pain. Soaking your feet in an Epsom salts bath may also help to relieve pain.
For some foot problems, physical therapy can help to relieve pain, strengthen muscles, and correct issues. Foot orthotics may help reduce pain and improve function in people with rheumatoid arthritis foot deformity.
The importance of appropriate footwear cannot be overstated. While therapeutic footwear can reduce pain and improve function, there is often poor compliance because of dissatisfaction with fit and style.
For severe cases, when conservative approaches that focus on footwear or orthotics fail, surgery may be an option. Forefoot resection and fusion are considered potentially satisfactory surgical options.