Rheumatoid Arthritis and the Knee: Symptoms and Treatment
Key takeaways
- Rheumatoid arthritis is an autoimmune disease in which the immune system attacks the joint lining, causing inflammation, pain, and swelling, often in both knees.
- Unlike osteoarthritis, it usually affects joints symmetrically and causes prolonged morning stiffness lasting well over 30 minutes.
- Modern medication, started early, can control the disease and protect the joints, so far fewer people now reach the point of needing surgery.
- When the knee is badly damaged despite treatment, a knee replacement can relieve the pain and restore movement.
- Around 90 to 95% of knee replacements are still in place at 10 years, though inflammatory arthritis needs careful timing around medication.
By Margaret Doyle | Medically reviewed by Mr Paul Henderson, FRCS (Tr&Orth)
Updated June 9, 2026 · 3 min read
Rheumatoid arthritis is an autoimmune disease in which the immune system attacks the lining of the joints, causing inflammation, pain, swelling, and stiffness, and the knees are commonly affected, usually on both sides. It is different from osteoarthritis, which is wear of the cartilage, and that difference matters because it changes the treatment. This surgeon-reviewed guide explains how rheumatoid arthritis affects the knee, how to tell it apart, and when a knee replacement comes into the picture.
My own knee problems came from osteoarthritis, not rheumatoid arthritis, but in the patient groups I have spent time in, the people with rheumatoid arthritis often had the hardest road: more joints involved, more fatigue, and more to juggle around their medication. This guide tries to do their situation justice. If your knee is already badly damaged, it may help to read the signs you may need a knee replacement.
What is rheumatoid arthritis in the knee?
Rheumatoid arthritis is a long-term autoimmune condition in which the immune system mistakenly attacks the synovium, the lining of the joint. In the knee this causes the lining to become inflamed and thickened, producing swelling, warmth, pain, and over time damage to the cartilage and bone. Because it is a disease of the immune system rather than simple wear, it typically affects several joints at once and on both sides of the body.
Rheumatoid arthritis affects around 1 in 100 people, and it is around two to three times more common in women than in men1. It often begins in the small joints of the hands and feet, but the knees are among the larger joints frequently involved.
How is it different from knee osteoarthritis?
The key difference is the cause: rheumatoid arthritis is the immune system attacking the joint, while osteoarthritis is the cartilage wearing down. That leads to several practical differences:
- Symmetry: rheumatoid arthritis usually affects both knees (and other joints) at once; osteoarthritis is often one-sided.
- Morning stiffness: rheumatoid stiffness lasts well over 30 minutes, often hours; osteoarthritis stiffness usually eases within about 30 minutes2.
- Whole-body symptoms: rheumatoid arthritis commonly brings fatigue and a general feeling of being unwell; osteoarthritis is confined to the joints.
- Age: rheumatoid arthritis can begin at any age, often between 30 and 60; osteoarthritis is more age-related.
What are the symptoms of rheumatoid arthritis in the knee?
The main symptoms are a warm, swollen, tender knee with prolonged morning stiffness, usually in both knees, often alongside fatigue and feeling unwell. Specifically, people notice:
- Swelling and warmth around the joint, which can come and go in flares.
- Prolonged morning stiffness, lasting well over 30 minutes.
- Pain that is present at rest, not only on use.
- Fatigue and a general feeling of being unwell, which can be as limiting as the joint pain.
- Reduced movement as the joint becomes damaged over time.
A single hot, swollen knee with fever needs urgent assessment to rule out joint infection, which is covered in when knee pain means you should see a doctor.
How is rheumatoid arthritis in the knee treated?
Treatment centres on disease-modifying anti-rheumatic drugs (DMARDs), started as early as possible to control the immune attack and protect the joints. NICE recommends starting DMARD treatment promptly after diagnosis, because early control prevents joint damage3. Around this, treatment includes:
- DMARDs and biologic medicines: the cornerstone, dampening the disease itself.
- Anti-inflammatory medication: for symptom control, at the lowest effective dose.
- Steroid treatment: short courses, or a corticosteroid injection into the knee, to settle a flare.
- Physiotherapy and exercise: to keep the joint moving and the muscles strong.
Because modern medication, started early, can control the disease so well, far fewer people now reach the point of needing joint surgery than in past decades.
When is a knee replacement needed for rheumatoid arthritis?
A knee replacement is considered when the knee is badly damaged and painful despite medical treatment, and the pain limits everyday life. The operation resurfaces the worn joint with metal and plastic components and can relieve the pain and restore movement effectively; around 90 to 95% of knee replacements are still in place at 10 years4.
For people with rheumatoid arthritis there is extra planning involved. Some disease-modifying and biologic medicines are paused around the operation to lower the infection risk, and the disease can affect bone quality and skin healing, so the surgical and rheumatology teams coordinate the timing carefully. The operation, the risks, and recovery are set out in our complete guide to knee replacement surgery, and the non-surgical options to try first are in the alternatives to knee replacement.
References
- Rheumatoid arthritis, Versus Arthritis. ↩
- Rheumatoid arthritis, NHS. ↩
- Rheumatoid arthritis in adults: management (NG100), NICE. ↩
- Inflammatory Arthritis of the Knee (OrthoInfo), American Academy of Orthopaedic Surgeons. ↩
Common questions
How is rheumatoid arthritis in the knee different from osteoarthritis?
Rheumatoid arthritis is an autoimmune disease in which the immune system attacks the joint lining, whereas osteoarthritis is wear of the cartilage. Rheumatoid arthritis usually affects joints on both sides of the body symmetrically, causes prolonged morning stiffness lasting well over 30 minutes, and often comes with fatigue and feeling unwell. Osteoarthritis stiffness typically eases within about 30 minutes.
Can rheumatoid arthritis affect just the knee?
Rheumatoid arthritis usually affects several joints, often the small joints of the hands and feet first, and typically on both sides of the body. The knees are commonly involved, but it would be unusual for the knee to be the only joint affected. If a single knee is hot and swollen, other causes such as infection or gout also need to be ruled out.
Does rheumatoid arthritis in the knee always need surgery?
No. Modern medication, started early, can control the disease and protect the joints, so far fewer people now need surgery than in the past. A knee replacement is considered only when the joint is badly damaged and painful despite medical treatment. When it is needed, it can relieve the pain and restore movement effectively.
What does rheumatoid arthritis in the knee feel like?
People describe a warm, swollen, tender knee with prolonged morning stiffness that lasts well over 30 minutes, often in both knees at once. There is frequently fatigue, a general feeling of being unwell, and flares where the symptoms worsen. The pattern of stiffness and swelling, rather than just pain on use, helps tell it apart from osteoarthritis.
Is a knee replacement different if you have rheumatoid arthritis?
The operation itself is similar, but it needs careful planning. Some disease-modifying and biologic medicines are paused around surgery to lower infection risk, and rheumatoid arthritis can affect the bone quality, skin healing, and other joints. Your surgical and rheumatology teams coordinate the timing. Outcomes are good, with around 90 to 95% of knee replacements still in place at 10 years.
What is the best treatment for rheumatoid arthritis in the knee?
The cornerstone is disease-modifying anti-rheumatic drugs (DMARDs), started as early as possible to control the immune attack and protect the joints, often alongside physiotherapy and short courses of anti-inflammatory medication or a steroid injection for flares. NICE recommends starting DMARD treatment promptly after diagnosis. Surgery is reserved for joints already badly damaged.
Written by Margaret Doyle. Medically reviewed by Mr Paul Henderson, FRCS (Tr&Orth).
Our guides are written from personal experience and reviewed by a qualified clinician for accuracy. Read our editorial policy.