Arthritis, a disease that is characterized by the inflammation of joints, can often lead to other complications. Arthritis is composed of more than a 100 individual subtypes, with one of the most common and well-known one being rheumatoid arthritis.
While the primary symptom of any kind of arthritis arthritis, including rheumatoid arthritis, is joint inflammation and swelling, patients with rheumatoid arthritis can sometimes also develop joint deformities. Rheumatoid arthritis can cause severe damage to both the hands and feet, causing joints in those locations to become deformed. Fingers and toes can be bent in different, uncomfortable positions. Fortunately, these deformities are less common now thanks to the introduction of new, different medicines that prevent progression of the disease. Additionally, earlier diagnosis helps doctors initiate treatment more quickly, thereby preserving joint structure.
1. Cause of deformities in rheumatoid arthritis
When rheumatoid arthritis affects a joint, the cells of the immune system that cause inflammation, known as inflammatory cells, invade the synovium — the lining of the joint. Once there, they form a fibrous layer of pannus (abnormal tissue). The pannus, in turn, releases substances into the synovium that causes the bones to quickly erode, destroying a cushioning substance known as cartilage and doing damage to the surrounding tissue. Therefore, the joint that is affected can lose its shape, alignment and bone structure, leading to deformities. When a patient has severe deformities, that causes loss of joint function and a potential need to undergo joint replacement surgery.
2. Risk factors for deformities in arthritis
There are some risk factors that can help predict whether a patient with rheumatoid arthritis will go on to develop deformities in their joints:
- Increased levels of C-reactive protein (CRP), an inflammatory marker.
- High levels of rheumatoid factor, an antibody that is made by the immune system and is found in patients with rheumatoid arthritis (and some other autoimmune diseases).
3. Types of joint deformities seen in arthritis patients
Several different types of joint deformities can develop in patients with rheumatoid arthritis. These joint deformities predominantly affect the hands and the feet.
These are some of the common deformities that affect the hands:
- Boutonniere deformity. This is when the middle finger is positioned in a way where the joint bends towards the palm. The outer finger may bend in a way that is opposite to the direction of the palm.
- Swan-neck deformity. This is when the base of the finger and the outer joint bend. The middle joint is straightened.
- Hitchhiker’s thumb (also known as Z-shaped deformity of the thumb). This is similar to the classic “hitchhiker’s thumb” in that the thumb is flexed and hyperextends at the joint below your thumb nail.
- Ulnar drift. In this deformity, your fingers will lean away from your thumb and bend toward your pinky finger.
Deformities can affect the feet as well:
- Claw toe deformity. In claw toe deformities, the toe is bent in a way that faces upward from the joints that are located at the ball of the foot, down at the middle joint and down at the top toe joint. Patients also have a curl under the foot.
- Bunion. In this case of bunions, the base of your big toe (the area where your big toe attaches to the foot) gets bigger and sticks out. This causes your big toe to press against the second toe, which then forces it to overlap with the third.
4. Prevention: How do you avoid joint deformities?
Prevention of joint deformities mainly includes having an early diagnosis and early initiation of treatment. In particular, deformities are less common nowadays due to the use of disease modifying anti-rheumatic drugs (DMARDs) and biologic drugs. However, these need to be taken before the development of any bone loss or bony erosions. Importantly, the development of joint deformities while you are on arthritis medication is a sign that your disease is not under control.
5. Treatments: What can you do about joint deformities?
The most common treatments prescribed to patients with deformities are generally exercise (which can be done in conjunction with an occupational therapist) and splint (a medical device that keeps the deformed part of the body from moving to protect other parts from damage).
For hand deformities, the treatments depend on the severity of the joint deformity:
- For less severe finger deformities, the doctor may advise you to use specially designed rings that can be used as finger splints.
- For patients that develop severe hand deformities, you are advised to work with an occupational therapist to design an exercise program and splints that can help increase function and slow down progression and further deformity.
- For the the most severe finger deformities, the doctor may advise you to get finger joint replacement surgery, which involves replacing the finger joints with an artificial one. While this does not cure rheumatoid arthritis, it does help recover functionality of the joint.
Deformities of the feet can cause the toes to be misshapen and misaligned, which can make walking or wearing regular shoes hard. These deformities can be corrected by:
- For less severe deformities, the doctor will likely advise you to use orthotics, which are composed on cushioned insoles or custom-made casts of your feet.
- For more severe deformities, the doctor will advise correction of the deformity with surgery.