Rheumatoid Arthritis of the Foot & Ankle
Rheumatoid arthritis is a chronic disease that attacks multiple joints throughout the body. It most often starts in the small joints of the hands and feet, and usually affects the same joints on both sides of the body.
More than 90% of people with rheumatoid arthritis (RA) develop symptoms in the foot and ankle over the course of the disease.
Rheumatoid arthritis 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.
How It Happens
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 an 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.
Cause & Symptoms
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.
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 (Heel Region of the Foot)
The main function of the hindfoot 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 (Top of the Foot)
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.
Forefoot (Toes and Ball of the Foot)
The changes that occur to the front of the foot are unique to patients with RA. These problems include bunions, claw toes, and pain under the ball of the foot (metatarsalgia). Although, each individual deformity is common, it is the combination of deformities that compounds the problem.
Medical History and Physical Examination
After listening to your symptoms and discussing your general health and medical history, your doctor will examine your foot and ankle.
Skin. The location of callouses indicate areas of abnormal pressure on the foot. The most common location is on the ball of the foot (the underside of the forefoot). If the middle of the foot is involved, there may be a large prominence on the inside and bottom of the foot. This can cause callouses.
Foot shape. Your doctor will look for specific deformities, such as bunions, claw toes, and flat feet.
Flexibility. In the early stages of RA, the joints will typically still have movement. As arthritis progresses and there is a total loss of cartilage, the joints become very stiff. Whether there is motion within the joints will influence treatment options.
Tenderness to pressure. Although applying pressure to an already sensitive foot can be very uncomfortable, it is critical that your doctor identify the areas of the foot and ankle that are causing the pain. By applying gentle pressure at specific joints your doctor can determine which joints have symptoms and need treatment. The areas on the x-ray that look abnormal are not always the same ones that are causing the pain.
Other tests that your doctor may order to help confirm your diagnosis include:
X-rays. This test creates images of dense structures, like bone. It will show your doctor the position of the bones. The x-rays can be used by your doctor to make measurements of the alignment of the bones and joint spaces, which will help your doctor determine what surgery would best.
Computerized tomography (CT) scan. When the deformity is severe, the shape of the foot can be abnormal enough to make it difficult to determine which joints have been affected and the extent of the disease. CT scans allow your doctor to more closely examine each joint for the presence of arthritis.
Magnetic resonance imaging (MRI) scan. An MRI scan will show the soft tissues, including the ligaments and tendons. Your doctor can assess whether the tendon is inflamed (tendonitis) or torn (ruptured).
Although there is no cure for RA, there are many treatment options available to help people manage pain, stay active, and live fulfilling lives.
Rheumatoid arthritis is often treated by a team of healthcare professionals. These professionals may include rheumatologists, physical and occupational therapists, social workers, rehabilitation specialists, and orthopaedic surgeons.
Although orthopaedic treatment may relieve symptoms, it will not stop the progression of the disease. Specific medicines called disease-modifying anti-rheumatic drugs are designed to stop the immune system from destroying the joints. The appropriate use of these medications is directed by a rheumatologist.
Orthopaedic treatment of RA depends on the location of the pain and the extent of cartilage damage. Many patients will have some symptom relief with appropriate nonsurgical treatment.
Limiting or stopping activities that make the pain worse is the first step in minimizing the pain. Biking, elliptical training machines, or swimming are exercise activities that allow patients to maintain their health without placing a large impact load on the foot.
Placing ice on the most painful area of the foot for 20 minutes is effective. This can be done 3 or 4 times a day. Ice application is best done right after you are done with a physical activity. Do not apply ice directly to your skin.
Nonsteroidal Anti-inflammatory Medication
Drugs, such as ibuprofen or naproxen, reduce pain and inflammation. In patients with RA, the use of these types of medications should be reviewed with your rheumatologist or medical doctor.
An orthotic (shoe insert) is a very effective tool to minimize the pressure from prominent bones in the foot. The orthotic will not be able to correct the shape of your foot. The primary goal is to minimize the pressure and decrease the pain and callous formation. This is more effective for deformity in the front and middle of the foot.
For people with RA, hard or rigid orthotics generally cause too much pressure on the bone prominences, creating more pain. A custom orthotic is generally made of softer material and relieves pressure on the foot.
A lace-up ankle brace can be an effective treatment for mild to moderate pain in the back of the foot and the ankle. The brace supports the joints of the back of the foot and ankle. In patients with a severe flatfoot or a very stiff arthritic ankle, a custom-molded plastic or leather brace is needed. The brace can be a very effective device for some patients, allowing them to avoid surgery.
An injection of cortisone into the affected joint can help in the early stages of the disease. In many cases, a rheumatologist or medical doctor may also perform these injections. The steroid helps to reduce inflammation within the joint. The steroid injection is normally a temporary measure and will not stop the progression of the disease.
Your doctor may recommend surgery depending upon the extent of cartilage damage and your response to nonsurgical options.
Fusion. Fusion of the affected joints is the most common type of surgery performed for RA. Fusion takes the two bones that form a joint and fuses them together to make one bone.
During the surgery, the joints are exposed and the remaining cartilage is removed. The two bones are then held together with screws or a combination of screws and plates. This prevents the bones from moving. During the healing process, the body grows new bone between the bones in these joints.
Because the joint is no longer intact, this surgery does limit joint motion. Limited joint motion may not be felt by the patient, depending on the joints fused. The midfoot joints often do not have much motion to begin with, and fusing them does not create increased stiffness. The ankle joint normally does have a lot of motion, and fusing it will be noticeable to the patient. By limiting motion, fusion reduces the pain.
Fusion can be a successful technique. However, because patients with RA also show damaged cartilage and loose ligaments, the success rate of this type of surgery is lower in patients with RA than in patients without RA. The use of newer generation medication can slow the progression of the disease and impact the type of surgeries that can be performed successfully.
Other surgeries. The front of the foot is where there are more surgical options for some patients. Surgeons can now perform joint sparing operations to correct the bunion and hammertoes in some patients. Your surgeon will review the most appropriate options for your case.