Rheumatoid arthritis (RA) is an autoimmune condition, meaning the immune system mistakenly attacks healthy tissues. RA in the knees may severely affect a person’s mobility.

RA commonly affects the joints in the hands, wrists, and knees, causing the lining of the joints to become inflamed and damaged. RA is typically symmetrical, affecting both sides of the body equally.

There are around 1.5 million individuals in the United States with RA. They may have difficulty carrying out everyday activities, and if RA affects their knees, they may find walking, climbing stairs, and general mobility challenging.

If people do not seek treatment for RA, it can cause progressive inflammation, resulting in damage to the joints, ultimately leading to permanent disability.

This article examines how RA affects the knees and discusses the symptoms and treatment options.

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The knees are the largest and strongest joints in the body. The knee consists of the kneecap, the lower end of the thighbone, and the upper end of the shinbone. The ends of these bones form the knee joint.

Protective cartilage cushions the bone as the knee bends and straightens and covers the ends of the bones. A thin capsule of tissue called synovial membrane lines the joint. The role of this membrane is to release lubricating fluid that reduces friction and protects the cartilage and ligaments.

If RA affects the knees, the immune system mistakenly targets the synovial membrane. This reaction causes inflammation and painful swelling due to cell proliferation, or growth. The swollen synovial membrane then limits movement.

RA commonly affects the knees on both sides equally.

As the condition progresses, swelling damages cartilage and ligaments, which can no longer cushion against friction. This results in the cartilage wearing away, damaging the bones.

Untreated inflammation can also lead to bony erosions and joint deformities.

Occasionally, the bones can fuse, which doctors call ankylosis. Ankylosis affects around 0.8% of people with RA in small joints of the hand, such as the wrist.

Individuals can experience extensive damage from RA, which can leave them life changing symptoms.

Learn about arthritis of the knee here.

People with RA have times when their symptoms worsen, called flare-ups, or improve, called remission.

Typically, the knees gradually become more painful and inflamed. Some individuals, however, may experience sudden, intermittent symptoms.

If a person has RA in their knees, they may have symptoms such as:

  • stiff, swollen joints that are difficult to bend and straighten
  • pain and swelling, which may be worse after periods of rest
  • pain that increases with vigorous physical activity
  • sudden sticking or locking of joints during movement
  • creaking, clicking, snapping, or grinding sounds
  • a feeling of weakness or buckling of the knee

Other generalized symptoms of RA include:

  • fatigue or exhaustion
  • low grade fever
  • inflamed, dry eyes and dryness of the mouth
  • low blood cell count
  • nodules or lumps under the skin over bony areas

Learn more about RA symptoms here.

RA can potentially change someone’s life due to reduced mobility and physical weakness. Having stiff and painful knees can make it challenging to get up from bed, bathe, and dress.

Also, regular daily activities can become extremely difficult as the condition progresses and causes further damage. As a result, some individuals need support in every aspect of their lives.

The unpredictability of symptoms makes activities challenging to plan and can leave those with RA feeling like they have lost control of their lives. Because of this, many people with RA experience depression and anxiety.

Additionally, some people with RA experience extreme fatigue, leaving them feeling overwhelmingly tired. Fatigue increases the need for sleep and makes even simple activities overly demanding.

RA can change relationships, as individuals can no longer participate in their previous hobbies and interests. As people lose mobility and feel increasingly tired, they may shy away from partaking in tiring social activities and spending quality time with others.

Furthermore, RA can impact an individual’s employment, as they may no longer be able to function as they used to. A 2016 study looked at the employment status of 488 people with RA. Of these, around 74.6% were employed, 6.4% were looking for work, and 19.1% had left employment. Over half of those looking for work had lost their previous job due to RA.

Learn more about how RA affects the body here.

Doctors use a combination of medical history, physical examination, and laboratory tests to diagnose RA in the knees:

  • Medical history: A doctor will ask questions about joint symptoms, including when they began, how severe they are, what improves or worsens them, and whether any relatives have RA or other autoimmune conditions.
  • Physical examination: A doctor will look for signs of tenderness, swelling, heat, or limited movements in the knees and joints. They will also check for a low grade fever and bumps under the skin.
  • Blood tests: These tests can identify inflammatory markers, such as erythrocyte sedimentation rate and C-reactive protein. Tests also look for rheumatoid factor (RF), an antibody present in 80% of individuals with RA, or cyclic citrullinated peptide (CCP), which is present in 60–70% of people with this condition.
  • Imaging tests: Because RA can damage the joints, doctors can use X-rays, ultrasound scans, or MRI scans to identify bone and joint erosion. However, images may not help doctors diagnose RA in the early stages when there is minimal bone damage.

Learn more about how doctors diagnose RA here.

Over-the-counter (OTC) and prescription medications can help manage an individual’s RA symptoms.

Initially, a doctor may prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroids, such as prednisone, to calm the inflammation. After this, they will introduce disease-modifying antirheumatic drugs (DMARDs).

DMARDs are a class of medications that reduce inflammation and symptom severity and slow down RA progression. Doctors typically prescribe methotrexate, which is also a chemotherapy medication. Other options include hydroxychloroquine (Plaquenil), leflunomide (Arava), and sulfasalazine (Azulfidine).

If the medications do not help, a doctor may recommend biologics. Biologics, including abatacept (Orencia) and golimumab (Simponi), interrupt signals from the immune cells that increase the inflammatory process.

A doctor may recommend knee replacement surgery for individuals with extensive knee damage, bone-on-bone arthritis, or secondary arthritis. This can allow the person to return to their usual day-to-day activities.

Learn about the differences between DMARDs and biologics for RA.

A person should consult a doctor if they experience any pain, stiffness, or swelling in their knees or other joints. Likewise, people should seek advice if they experience any other symptoms of RA.

A doctor can provide an accurate diagnosis, rule out any other issues, and recommend suitable treatment.

The Centers for Disease Control and Prevention (CDC) recommend that people receive a diagnosis within 6 months of the onset of their symptoms. Doctors can sometimes make a diagnosis within 6 months of symptoms starting, and they call this early RA.

Treatment should start as soon as possible after diagnosis. This can minimize bone destruction and the impact of RA on the person’s life.

If an individual experiences pain and swelling in the knee joint alongside fever, shaking, and chills, they should seek immediate medical attention. These symptoms could indicate a severe infection, which requires emergency treatment.

Receiving a diagnosis of RA can result in people feeling overwhelmed and lonely. If possible, they should find emotional and physical support from family and friends as they learn to navigate life with a chronic condition.

Individuals may also find it valuable to reach out to others living with RA and learn from their experiences.

Many hospitals and nonprofit groups, such as the Arthritis Foundation, provide online and in-person support groups. At the meetings, people with RA can connect with others and share information and insights without pressure or embarrassment.

RA is an autoimmune condition that affects the joints, including the knees. It causes pain, stiffness, and swelling that can interfere with an individual’s life, making it difficult to walk or stand.

People should seek guidance from a doctor if they notice any signs of RA or experience knee symptoms. Individuals should begin treatment as early as possible to prevent damage to their knees and joints that can be disabling.