Hand Deformity in Rheumatoid Arthritis

Your hands and wrists contain more than 25 joints, and they're all especially susceptible to the damaging effects of rheumatoid arthritis (RA). In fact, stiffness and swelling of the wrists and knuckles are often the very first signs of this chronic autoimmune disorder.

Rheumatoid arthritis is caused by the immune system malfunctioning and attacking your joints, causing pain, inflammation, fatigue, and weakness. Over time, as the disease progresses, it can lead to increased 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, doing up buttons, tying your shoes, and twisting a doorknob painful, difficult, or even impossible. Prolonged joint damage and inflammation can lead to the gradual deformity of your wrists, hands, and fingers.

Causes of Rheumatoid Hand Deformity

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 poorly treated rheumatoid arthritis, the immune system sends white blood cells called leukocytes to attack healthy joint tissue. The synovium responds to this assault by producing layer upon layer of new synovial cells, one on top of another.

As these layers accumulate, they crowd into the joint space. That triggers 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 get progressively worse over time.

Joints Affected

Rheumatoid arthritis usually develops symmetrically, meaning that it affects the joints on both sides at the same time. It typically appears in one or more of the following joints in the hand:

• Metacarpophalangeal joints: The large knuckles where the fingers and thumb meet the hand.
• Proximal interphalangeal joints: The middle knuckles.
• Joints of the wrist: The carpometacarpal joint, midcarpal joint, radiocarpal joint, and intercarpal joints.

Types 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 a Boutonniere: the tip of the finger is bent toward the palm while the middle joint is bent backward. It literally resembles the neck and head of a swan. This is caused by abnormal stress of the ligament that surrounds the middle joint.

Trigger Finger

The medical term for trigger finger is stenosing tenosynovitis, which causes both the proximal and distal interphalangeal joints (middle and tip) to bend inward toward the palm as if it's pulling the trigger of a gun. Typically, your finger tendons glide through pulleys, which keep them close to the bone. With RA, sometimes the pulleys thicken, which prevents the tendon from gliding through it and means you can't straighten the finger. 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 at the base of the thumb bends inward toward the palm while the other joint extends away from the joint. This is also called a duckbill thumb or Z-thumb because of its shape. It's 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. They're 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 ("drift") toward the pinky due to the rupture of nearby tendons. At the same time, the wrist will begin to shift toward the thumb side of your 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. It 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

The best way to prevent hand deformities is to treat your RA early and aggressively. This strategy has helped make joint deformities less common and less severe than they used to be.

Early, aggressive treatment is 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.

Treating Hand Deformity in Rheumatoid Arthritis

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 easy surgeries to perform, and they generally require an extended recovery time that includes physical therapy.

Again, early treatment is the best course of action for preventing or 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).