Rheumatoid Arthritis of the Knee, Hands, and Feet: How the Joints Are Affected

Rheumatoid arthritis is not about "worn-out cartilage" but about an error in immune defense: it attacks the cells lining the joint from the inside. Below is how this error manifests in the knee, hands, and feet, what changes in the joints over time, and when a conversation with a rheumatologist stops being premature.

Which joints are affected by rheumatoid arthritis

The disease most often affects the hands, feet, and wrist joints, although it can attack any joint tissue. To keep the mechanism in mind, use one analogy throughout the article: a joint is a door on hinges, and the inner lining of the joint is the lubricant and the gasket in the hinge. In rheumatoid arthritis, immune cells mistake this gasket for a foreign body and destroy it. Imagine that a guard in a house has mistaken the residents for burglars and methodically breaks the door hinges: the door still opens, but each day a little worse.

Inflammation affects not only the joints — the eyes, skin, heart, nerves, blood, and lungs respond too. There can be general symptoms: fatigue, fever, loss of appetite, and sometimes firm nodules appear under the skin near the joints. Prevalence is 0.5–1% in developed countries (up to 5% in the elderly), with a mean age of onset of 40–50 years in women and somewhat higher in men; women account for 3–5 times more patients. The disease is usually symmetrical: if one hand or one knee is affected, so is the other.

• pain and stiffness that worsen in the morning and after rest;
• symmetry: usually the same joints on both sides are affected;
• swelling, redness, and local warmth.

Rheumatoid arthritis of the knee: how it manifests

The knee is a large joint, and its involvement is noticeable in daily life: swelling can make everyday actions difficult, such as bending the knees. In our analogy, the hinge swells: the door moves — more stiffly.

Rheumatoid arthritis of the fingers and hands

RA most often affects the wrist and fingers. The small joints of the fingers hurt, swell, and simple tasks such as combing hair or buttoning buttons take longer. A separate complication is carpal tunnel syndrome.

Joint deformity: what changes over time

Over time, inflammation can damage the joints, cartilage, and adjacent bone, causing the joints to work worse; this is how deformity develops. It is not wear and tear but a consequence of prolonged inflammation: the hinge is warped, and the door no longer closes evenly.

When to see a rheumatologist

There is no single test for rheumatoid arthritis: the diagnosis is built from the medical history, family history, examination of the joints, skin, and chest, blood tests (ESR, rheumatoid factor, anti-cyclic citrullinated peptide antibodies), and imaging — X-ray or ultrasound. Early diagnosis changes the prognosis: treatment is more effective while the joint is not yet destroyed. It makes sense to see a doctor for symptoms resembling rheumatoid arthritis: symmetrical swelling, morning stiffness, pain, or persistent limitation of movement in the hand, knee, or foot.

A flare-up of rheumatoid arthritis by itself is not a reason to call an ambulance. 103 or 112 — for life-threatening conditions, such as signs of a heart attack or stroke: in RA, the risk of heart attack and stroke is increased.

This material is for reference: it explains the mechanism but does not replace a doctor's consultation — a diagnosis is made at an appointment, not from an article.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer