Rheumatoid Arthritis: Symptoms and Diagnosis

• Rheumatoid Arthritis (RA) is a systemic, chronic inflammatory disease.
• RA affects many tissues, primarily attacking the joints.
• RA leads to nonsuppurative proliferative synovitis.
• The synovitis often progresses to destroy articular cartilage and underlying bone.
• RA results in disabling arthritis.

Symmetric Arthritis

• RA typically presents as symmetric arthritis.
• It mainly affects the small joints of the hands and feet.
• Ankles, knees, wrists, elbows, and shoulders are also commonly affected.
• Proximal interphalangeal and metacarpophalangeal joints are usually involved.
• Distal interphalangeal joints are typically spared.

Axial and Hip Involvement

• Axial involvement in RA is limited to the upper cervical spine.
• Hip joint involvement is uncommon.

Radiographic Hallmarks

• Radiographic hallmarks include joint effusions.
• Juxta-articular osteopenia with erosions is a hallmark.
• There is narrowing of the joint space and loss of articular cartilage.

Joint Deformities

• Destruction of tendons, ligaments, and joint capsules leads to characteristic deformities.
• Radial deviation occurs at the wrist.
• Ulnar deviation appears in the fingers.
• Flexion-hyperextension abnormalities, such as swan-neck and boutonnière deformities, can occur in the fingers.

Rheumatoid Nodules

• Rheumatoid subcutaneous nodules develop in about one-fourth of RA patients.
• They are typically found along the extensor surface of the forearm or other areas.
• Nodules rarely form in the lungs, spleen, heart, aorta, and other viscera.

Pathogenesis

• Joint inflammation in RA is immunologically mediated.
• There is a genetic predisposition to RA.
• The disease is initiated by the activation of CD4+ helper T cells.
• T cells respond to an arthritogenic agent, possibly microbial or a self-antigen.
• Activated T cells produce cytokines that activate macrophages and other cells in the joint space.
• This leads to the release of degradative enzymes and other factors that produce inflammation.
• Activated T cells also activate B cells.
• B cell activation results in the production of antibodies directed against self-antigens in the joint.
• 80% of patients have serum IgM and, less frequently, IgG autoantibodies.
• These autoantibodies bind to the Fc portions of self IgG and are called rheumatoid factor (RF).

Pannus Formation

• Pannus is formed by proliferating synovial-lining cells.
• It is admixed with inflammatory cells, granulation tissue, and fibrous connective tissue.
• Pannus eventually fills the joint space.
• Subsequent fibrosis and calcification may cause permanent ankylosis.

Clinical Course

• RA presents as symmetric polyarticular arthritis.
• Constitutional symptoms include weakness, malaise, and low-grade fever.
• Vasculitic involvement of the extremities may cause Raynaud phenomenon and chronic leg ulcers.

Diagnosis

• Diagnosis includes characteristic radiographic findings.
• Sterile, turbid synovial fluid is present with decreased viscosity.
• Poor mucin clot formation occurs, with inclusion-bearing neutrophils.
• Rheumatoid Factor (RF) is present in 80% of patients.