Overview of Inflammatory Arthritis

Inflammatory types of arthritis may involve multiple joints simultaneously. Often, an overactive or malfunctioning immune system is the cause of inflammation. The primary symptoms of inflammatory types of arthritis are pain and stiffness in the morning or after periods of rest or inactivity. In patients with inflammatory arthritis, the period of morning stiffness typically exceeds 60 minutes.

Swelling, redness, and warmth also are common in or around the affected joints. Inflammatory arthritis not only affects the joints — other body parts can be affected, including the skin or internal organs. Inflammatory arthritis can affect people of all ages, but often strike people in the prime of life.

Swelling does not always occur with inflammatory arthritis. While that may seem uncharacteristic, actually inflammatory arthritis patients may have pain without swelling, swelling without pain, or physical limitations without either pain or swelling.

The three most common types of chronic inflammatory arthritis are rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. But, there are others as well. In patients who exhibit musculoskeletal symptoms, inflammatory conditions that do not have joint involvement may include bursitis, tendinitis, or polymyalgia rheumatica. Patients who have one to 3 joints involved may have an acute inflammatory condition such as infectious arthritis, gout, pseudogout, Reactive arthritis, or Chlamydial arthritis — or a chronic inflammatory condition such as psoriatic arthritis, spondyloarthropathy, pauciarticular juvenile arthritis, or infectious arthritis that is slow to heal. Patients who have 4 or more joints involved may have acute inflammatory conditions such as viral arthritis, drug-induced arthritis, early connective tissue disease, rheumatic fever, palindromic rheumatism, or remitting seronegative symmetrical synovitis with pitting edema (RS3PE) — or chronic inflammatory conditions such as rheumatoid arthritis, undifferentiated polyarthritis, inflammatory osteoarthritis, mixed connective tissue disease, lupus, scleroderma, polyarticular juvenile arthritis, or adult Still's disease.

Elevation in acute phase reactants serves as indicators of inflammation. While the two most often utilized, CRP and sedimentation rate, are indicative of inflammation, they do not differentiate between rheumatoid arthritis and other inflammatory types of arthritis. Also, not all patients with inflammatory arthritis will have elevated CRP or sedimentation rate initially. Some patients may instead have elevated levels of ferritin, haptoglobin, ceruloplasmin, or complement. Other markers indicative of an inflammatory type of arthritis are anemia of chronic disease, elevated platelets, and elevated white cell count.

There are serologic tests to help pin down the diagnosis. Rheumatoid factor is commonly ordered when rheumatoid arthritis is suspected. But, not everyone with rheumatoid arthritis is positive for rheumatoid factor (seropositive). About 20% of patients diagnosed with rheumatoid arthritis are negative for rheumatoid factor (seronegative). In early arthritis (symptoms for less than a year) rheumatoid factor sensitivity is about 17-59%, according to Kelley's Textbook of Rheumatology. The specificity is also not good in early rheumatoid arthritis, since other conditions may be associated with a positive rheumatoid factor (e.g., lupus, Sjogren's syndrome). Even 4-5% of the general population is positive for rheumatoid factor. Other serologic tests, such as anti-CCP and ANA can provide more diagnostic information, in addition to CRP, sedimentation rate, and rheumatoid factor.

Testing for certain genetic markers can be helpful. For example, HLA-B27 positivity is strongly associated with ankylosing spondylitis. Also, synovial fluid analysis can provide information regarding inflammation — synovial fluid from an inflamed joint is typically yellow and turbulent, with white cell counts above 10,000 cells/mm, with the greatest percentage being neutrophils.

Imaging is also utilized as part of the diagnostic process for inflammatory arthritis. X-ray evidence of inflammatory arthritis may include soft tissue swelling, chondrocalcinosis, joint effusion, osteopenia near the joint, symmetric loss of cartilage, joint space narrowing, and bony erosions.