Hand Deformity in Rheumatoid Arthritis

Rheumatoid arthritis (RA) can cause hand deformities to develop, such as inverted appearing knockles. Over time, as the disease progresses, it can lead to disability as the pain and restricted range of motion make it difficult to function. When RA takes a toll on your hands, it can make common tasks like opening a jar, fastening buttons, tying your shoes, and twisting a doorknob painful, difficult, or even impossible.

With RA, a malfunctioning immune system attacks joints, causing pain, inflammation, fatigue, and weakness. The more than 25 joints in your hands and wrists are especially susceptible to the damaging effects of RA. Stiffness and swelling of the wrists and knuckles are often the very first signs of this chronic autoimmune disorder. And prolonged joint damage and inflammation can lead to the gradual deformity of the wrists, hands, and fingers.

How Hand Joints Are Affected

As with other joints in the body, the joints in your hand are surrounded by a thin, pliable membrane known as synovium. The synovium produces synovial fluid, which is a thin, viscous substance that helps lubricate the joint.

In untreated or inadequately treated RA, the immune system sends leukocytes, a type of white blood cell, to attack healthy joint tissue. RA usually develops symmetrically, generally affecting the joints on both sides at the same time. 

The synovium reacts to the immune attack by producing layer upon layer of new synovial cells, one on top of another. And as these layers accumulate, they crowd into the joint space, triggering the release of proteins that speed up the destruction of cartilage, erosion of bone, and damage to ligaments.

This can all affect the very architecture of your hand, distorting the tendons and pushing the bones and joints out of alignment. That leads to deformities that can get progressively worse over time.

Types and Signs of Hand Deformity

Many types of hand deformities are possible in rheumatoid arthritis, depending on what joints and other structures are damaged.

Boutonniere Deformity

In a Boutonniere deformity, the tendon on the back of a finger or thumb becomes weak or torn. That causes the proximal interphalangeal joint (in the middle of the finger) to bend toward the palm.

At the same time, the distal interphalangeal joint (near the fingertip) is pulled in the opposite direction, causing the upper portion of the finger to curve upward.

Swan-Neck Deformity

A swan-neck deformity is the opposite of the Boutonniere type: The tip of the finger is bent toward the palm while the middle joint is bent backward. It resembles the neck and head of a swan, hence the name.

This is caused by weakness in or damage to the ligament that surrounds the middle joint.

Trigger Finger

The medical term for trigger finger is stenosing flexor tenosynovitis, which causes both the proximal and distal interphalangeal joints (middle and tip) to bend inward toward the palm as if you're pulling the trigger of a gun.

Typically, your finger tendons glide through pulleys, which keep them close to the bone. With RA, these pulleys sometimes thicken, which prevents the tendon from gliding properly and, therefore, the finger from straightening. Doctors don't yet know why the pulleys thicken in RA.

Hitchhiker's Thumb

Similar to Boutonniere's, hitchhiker's thumb occurs when the knuckle of the thumb bends inward toward the palm. This is also called a duckbill thumb or Z-thumb because of its shape. Hitchhiker's thumb is due to the breakdown of bone and cartilage.

Rheumatoid Nodules

Firm bumps under the skin that occur in up to 40% of people with RA are called rheumatoid nodules. They can develop on your knuckles as well as many other places around the body.

These nodules not usually painful but can become tender during a symptom flare. The cause of rheumatoid nodules isn't yet understood, but experts suspect a genetic component.

Ulnar Drift/Deviation

One of the more recognizable signs of advanced rheumatoid arthritis is a condition known as an ulnar drift or ulnar deviation. This is where the fingers begin to lean toward the pinky due to the rupture of nearby tendons. At the same time, the wrist begins to shift toward the thumb side of the hand.

Contractures

A contracture is a shortening and/or hardening of your muscles and connective tissues that leads to deformed and rigid joints. It's caused by erosion of the cartilage and changes to your ligaments.

A contracture results in a limited range of motion, meaning you can have difficulty moving your hands or straightening your fingers. An affected hand may take on a claw-like shape.

Wrist Subluxation

Subluxation is a partial dislocation caused by joint instability due to severe damage to your cartilage, connective tissues, and bones. Full dislocation is also possible but less common. Subluxations cause a lot of pain and functional limitations.

Preventing Hand Deformities Due to RA

The best way to prevent hand deformities is to get early, aggressive, and targeted treatment for your RA. This strategy has helped make joint deformities less common and less severe than they used to be.

Early, aggressive treatment and a targeted approach are also tied to better overall outcomes as well as a lower risk of death from RA-related complications. Research shows that, with proper treatment, the average person with RA has only a 15% increased chance of premature death.

Treatment Options

Once a hand deformity occurs, it can't be reversed by medications. Splinting may be an option in some cases, but surgery to repair or replace the damaged joint is a common choice.

Surgery may help realign the hand and restore some function and range of motion, but these are not simple procedures, and they generally require an extended recovery time that includes physical therapy.

Here too, early treatment is the best course of action for limiting deformities. RA treatment varies by the stage of the disease:

• In early or mild rheumatoid arthritis, disease-modifying anti-rheumatic drugs (DMARDs) like Plaquenil (hydroxychloroquine) and Azulfidine (sulfasalazine) can often help.
• Moderate-to-severe rheumatoid arthritis typically requires more powerful DMARDs including methotrexate and Arava (leflunomide). Another class of drug, called TNF blockers, can help suppress the immune system by inhibiting an inflammatory protein known as tumor necrosis factor (TNF).