Inflammatory Arthritis of the Knee

Inflammatory arthritis of the knee is a condition where the body’s immune system mistakenly attacks the joint, causing pain, swelling, and stiffness. Specifically, it usually causes thickening and inflammation of the joint lining known as synovial thickening (Figure 1). Unlike osteoarthritis, which is caused by wear and tear, inflammatory arthritis is due to ongoing inflammation inside the joint. There are different types of inflammatory arthritis, including rheumatoid arthritis (RA), psoriatic arthritis, and gout. Rheumatoid arthritis and psoriatic arthritis are autoimmune diseases, meaning the body’s defense system attacks its own joints, usually the joint lining. Psoriatic arthritis is linked to psoriasis, a skin condition, while gout happens when too much uric acid builds up in the joint. This condition can affect people of all ages but is more common in adults, especially those with a family history of autoimmune diseases.

How Is Inflammatory Arthritis of the Knee Diagnosed?

Doctors diagnose inflammatory arthritis of the knee by asking about symptoms, doing a physical exam, and using tests to confirm the condition. Blood tests can check for markers of inflammation and specific antibodies that suggest autoimmune diseases. For example, a rheumatoid factor (RF) or anti-CCP test can help diagnose rheumatoid arthritis. Sometimes, doctors remove fluid from the knee joint to check for uric acid crystals, which can confirm gout. Imaging tests like X-rays, ultrasounds, or MRIs help show joint damage and inflammation -including thickening of the joint lining (synovial thickening). These tests are important to determine the type and severity of the arthritis.

Conservative Treatment of Inflammatory Arthritis of the Knee

Treatment for inflammatory arthritis of the knee usually starts with medications to control inflammation and reduce pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can help with swelling and discomfort. Disease-modifying antirheumatic drugs (DMARDs), such as methotrexate, slow down the immune system’s attack on the joint. Biologic medications, which target specific parts of the immune system, can be used for more severe cases. Corticosteroids, either taken as pills or injected into the knee, can quickly reduce inflammation but are not a long-term solution. Physical therapy can also help improve movement and strengthen the muscles around the knee.

Surgical Options for Treating Inflammatory Arthritis of the Knee

If medications and therapy do not control the symptoms, surgery may be considered. A synovectomy is a procedure where the inflamed lining of the knee joint (the synovium) is removed to reduce pain and swelling. This can be helpful in early stages but does not stop the disease from progressing. When the arthritis becomes severe and the knee joint is badly damaged, a total knee replacement may be needed. In this procedure, the damaged joint is removed and replaced with an artificial knee. Surgery is usually considered when pain is constant, mobility is severely limited, and other treatments no longer help. A well-done knee replacement can last 15–20 years, but like any surgery, there are risks such as infection or implant loosening over time.

Edited by Amari Eubanks and Stephen Pinney MD July 5th, 2025