Ra pathology

• Synovial joint


  Joint cavity filled with lubricating fluid, allowing smooth movement and increased joint mobility. Bones connected by ligaments and articular cartilage.
• Types of synovial joints

  • Pivot
  • Hinge
  • Condyloid
  • Saddle
  • Plane
  • Ball-and-Socket
• Synovial joints - more details

  • Articular disc/meniscus - fibrocartilage structure providing structure or shock absorption
  • Bursa - thin connective tissue sac filled with lubricating liquid to prevent friction
• Bursitis


  Inflammation of a bursa near a joint, causing pain, swelling and joint stiffness
• Types of arthritis


  • Osteoarthritis
  • Gout (acute)
  • Rheumatoid arthritis (chronic)
  • Systemic lupus erythematosus (chronic)
• Osteoarthritis (OA)


  • Most common, associated with aging, damage to articular cartilage. Risks include age, gender, genetics, obesity, joint misalignment, injury.
• Cartilage function


  1. Change shape to bear weight, decrease friction

  2. Balance between metabolic and catabolic activity of chondrocytes

  3. Mechanical stimulation affects functioning of chondrocytes
• OA pathology


  Loss of matrix in cartilage, disruption of cartilage, swelling, fissures, subchondral bone changes, osteophytes
• Rheumatoid Arthritis (RA)


  Chronic systemic autoimmune condition, most often affecting fingers/wrists, inflammation of multiple peripheral joints, F>M, abnormal activation of immune cells, synovial inflammation and pannus formation leading to cartilage and bone degradation.
• RA autoimmune processes


  Autoantibodies (rheumatoid factor, anti-CCP) may be detected, role in initiating disease unclear, acute disease self-limiting, chronic disease reflects immune system 'remembering' antigens.
• RA pathogenesis


  Initiating antigen binds to APC, activates T cells, produces inflammatory cytokines (TNF-alpha, interleukins) which stimulate various inflammatory and immune processes.
• RA DMARDs


  • Methotrexate
  • Sulfasalazine
  • Antimalarials (e.g. hydroxychloroquine)
  • Leflunomide
• Gout


  Most common inflammatory arthritis, caused by deposition of monosodium urate crystals in cartilage, bone and joint space, associated with hyperuricaemia.
• Hyperuricaemia


  Causes include overproduction of uric acid (high purine intake, metabolic syndrome) or reduced renal excretion. Only 10% of people with hyperuricaemia develop gout.
• Gout treatment


  1. Acute attack treatment (e.g. colchicine)

  2. Reduction of plasma uric acid concentration for prophylaxis (e.g. xanthine oxidase inhibitors, uricosuric agents)
• Colchicine


  Interferes with inflammatory activity in gout by inhibiting microtubules, impairing immune cell migration and phagocytosis.