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 that can ultimately lead to permanent disability.

In this article, we look at how RA affects the knees, and we discuss 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 that cushions the bone as the knee bends and straightens 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, allowing damage to the bones to occur.

Occasionally, the bones can fuse, which doctors call ankylosis. Ankylosis affects around 0.8% of people with RA.

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

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 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

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 feel depressed and anxious.

Additionally, a number of 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. For example, in a 2002 study, the researchers note that around 1 in 3 people with RA left their job within 5 years of an RA diagnosis.

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, and 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 bone damage is minimal.

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

Depending on the severity of RA in the knee joints, a person may only require OTC nonsteroidal anti-inflammatory drugs to help with the pain and inflammation. A doctor may also prescribe corticosteroids, such as prednisone.

Disease-modifying antirheumatic drugs are a class of medications that reduce inflammation and severity of symptoms and slow down RA progression. Doctors typically prescribe methotrexate, which is also a chemotherapy medication. Other options include hydroxychloroquine (Plaquenil) and sulfasalazine (Azulfidine).

If the medications do not help, a doctor may recommend biologics. Biologics, including abatacept (Orencia) and golimumab (Simponi), stop specific immune cells from overreacting, reducing inflammation.

For individuals with extensive knee damage, a doctor may recommend knee replacement surgery to allow them to return to their usual day-to-day activities.

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. This allows them to start a treatment regimen that minimizes bone destruction and the impact of RA on their lives.

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 render 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.