4. Arthritis Flashcards
Types of arthritis
- Osteoarthritis
- Rheumatoid arthritis
- Seronegative arthritis
- Crystalline joint disorders
Definition of osteoarthritis
Also known as degenerative joint disease; involves progressive erosion of articular cartilage of joints
Causes of osteoarthritis
i. Primary osteoarthritis (95% of cases, idiopathic)
ii. Secondary osteoarthritis (5% of cases)
1. Underlying joint disorders
- Previous septic arthritis
- Congenital dislocations
- Inflammatory arthritis
- Intra-articular fracture
- Abnormal stresses
- Malaligned joints
- Neuropathic joints (lack of sensation) - Metabolic/endocrine causes
- Gout
- Hemachromatosis
- Diabetes mellitus
- Marked obesity
Site of osteoarthritis
- Primary arthritis
- Typically a generalized process
- Involves distal & proximal interphalangeal joints of the hand (gives Heberden nodes, prominent osteophytes at the DIP, especially in women) - Secondary arthritis
- Typically a localized process
- Involves single large joints, typically knee or hip
Morphology of osteoarthritis
Grossly:
1. Alteration in shape & damage to articular cartilage
- Eburnation
- Smoothening of surface of subchondral bone plate exposed due to focal areas of complete loss of articular cartilage - Thickening of subchondral bone
- Subchondral cyst formation
- Cystic lesions representing intraosseous accumulation of synovial fluid leaked through gaps in exposed subchondral bone - Osteophyte formation
- Mushroom-shaped bony outgrowths at the margins of the articular surface
Clinical features of osteoarthritis
- Presentation:
- Deep achy pain that worsens with use
- Morning stiffness, limited range of movement
- Impingement of osteophytes on spinal foramina (in the case of osteoarthritis of intervertebral joints) may cause nerve root compressions, leading to pain, spasms & muscle atrophy - Xray findings:
- Narrowing of joint space
- Increased thickness of subchondral bone
- Subchondral cyst formation
- Osteophyte formation (large peripheral growths of bone & cartilage)
Definition of rheumatoid arthritis
Chronic systemic inflammatory disease that frequently involves the synovial lining of peripheral joints
Epidemiology & associations with rheumatoid arthritis
- Male : female= 1 : 3
- Often occurs in 4th to 6th decades of life
- Complex mode of inheritance under polygenic regulation
- Class II MHC molecules play an important role
- Strong association with HLA-DR4 - Rheumatoid factor (one of the many autoantibodies produced in rheumatoid arthritis)
- Not specific for rheumatoid arthritis though
- Seen in a number of no rheumatic diseases as well as
in healthy individuals
Pathogenesis of rheumatoid arthritis
- Inappropriate activation of CD4+ T-helper cells results in the activation of several inflammatory pathways:
- B cell activation to produce autoantibodies (rheumatoid factor) which results in immune complex deposition in synovial joint
- Macrophage activation which releases cytokines promoting fibroblast, chondrocytes & synovial cells to release collagenase, stromalysin, elastase etc
- Endothelial activation which upregulates adhesion molecule expression, promoting the recruitment of leukocytes & subsequent inflammation - These pathways converge upon a pannus formation
- Pannus = hypertrophied inflamed synovium which extends over the articular surface & destroys the underlying cartilage & bone
Morphology of rheumatoid arthritis
Histologically:
1. Synovial hyperplasia
- Accumulation of chronic inflammatory cells (plasma cells, lymphocytes, macrophages, giant cells)
- Subcutaneous rheumatoid nodules (seen in 25% of cases, irregularly shaped with a central zone of necrotic fibrinoid material surrounded by a palisade of histiocytes & some chronic inflammatory cells)
Clinical features of rheumatoid arthritis
Presentation:
- Generally symmetrical involvement of joints, progressing from small to large joints
- Hands & feet first, followed by elbows, knees, wrists, ankles, hips, spine & temporomandibular articulations
- Swan-neck/boutonniere fingers: characteristic radial deviation of wrist & ulnar deviation of fingers + flexion-hyperextension of fingers (due to damaged tendons, ligaments & joint capsule) - Involved joints are swollen, warm, painful & particularly stiff following inactivity & sleep
- Alleviation of symptoms occur with use of joint
- Extra-articular multisystemic manifestations:
- CVS: ischemic heart disease, atherosclerosis, vasculitis
- Rheumatoid nodules in soft tissue, lungs & viscera
- Lungs (interstitial lung fibrosis)
- Serosal inflammation (pericarditis, pleurisy)
- Microcytic hypochromic anemia
- Felty’s syndrome (less than 1% of patients develop splenomegaly & leucopenia)
- Ocular disease (keratoconjunctivitis sicca, scleritis, perforation of the globe)
Treatment:
- Methotrexate (first line treatment)
- Corticosteroids
- NSAIDs
- Anti-TNF agents
Definition of seronegative arthritis
Group of disease that develop in genetically predisposed individuals, initiated by ubiquitous environmental factors such as infectious agents; typically negative for rheumatoid factor, associated with HLA-B27 & display a predilection for young men
Types of seronegative arthritis
- Ankylosing spondylitis
- Reiter syndrome
- Psoriatic arthropathy
Ankylosing spondylitis
- Aka rheumatoid spondylitis or Marie-Strumpell disease
- Chronic synovitis that causes destruction of articular cartilage with resultant bony ankylosis
- Involves vertebral column & sacroiliac joints of young patients
- Eventual squaring & fusion of vertebral bodies & production of bony outgrowths result in severe spinal immobility
Complications & associated pathologies of ankylosing spondylitis
- Spine fracture
2. Aortitis, uveitis, amyloidosis
