L09- Common joint pathologies Flashcards
What are the articular surface of bones in synovial joints covered by?
Thin layer of hyaline cartilage
What is the function of the viscous synovial fluid?
- Lubrication
- Shock absorption
- Nutrient distribution
What are synovial joints surrounded by?
A fibrous capsule
- Capsule reinforced externally or internally (or both) by fibrous ligaments
What are bursae?
Fluid filled sacs that facilitate smooth movement between articulating structures
Which structures provide stability to the synovial joints?
- Muscles
- Ligaments
- Capsule
What’s the normal colour/ consistency of healthy synovial fluid?
- Viscous (less viscous may indicate inflammation)
- Clear and colourless or straw coloured
- Abnormal may be cloudy, opaque or coloured
What is infective (septic) arthritis?
- Inflammation of a joint caused by infection (usually bacterial)
- Can affect any age group, more common in children and elderly
- Erosions
- Loss of joint space
- New bone formation
What are the risk factors for infective (septic) arthritis?
- Breach of skin barrier
- Immunosuppression for any cause
- Extremes of age
- Underlying inflammatory arthritis
- Joint replacement
What are the different possible routes of infection?
- Via blood stream (haematogenous route)
- Directly into joints (wound/ needle)
- From a skin/ tissue infection
- From a bone infection
What are the possible consequences of untreated infection?
- Rapid joint destruction often with infection of surrounding bone (osteomyelitis - infection of bone)
- May drain to skin surface (sinus)
- Bacterial spread to blood stream (sepsis)
- Stimulation of excess bone formation leading to fusion of the joint –> loss of function
What is gout?
- Crystal induced arthritis in which the deposition of uric acid (monosodium urate) crystals in joints leads to inflammation
- Monoarticular or pauciarticular (asymmetrical at first)
- May become polyarticular and symmetrical later
What’s the incidence of gout like?
- More common in men (middle age onwards)
- Post-menopausal women
What is the primary aetiology of gout?
- Idiopathic (unknown cause)
- Usually due to impaired excretion of uric acid by kidney; may be family tendency
What is the secondary aetiology of gout?
- Inc prod of uric acid
- E.g. alcohol consumption or high purine intake in diet or high turnover of cells, e.g. treatment of leukaemia
- Impaired excretion by kidney, disease or drugs, e.g. diuretics
What are the pathological changes seen in gout?
- Cartilage degeneration
- Synovial hyperplasia (the enlargement of an organ or tissue caused by inc in reproduction rate of its cells)
- Erosion of bone
- Secondary degenerative change (osteoarthritis)
What is a tophus (tophaceous deposits)?
Deposit of monosodium urate crystals
What is osteoarthritis?
- Predominantly degenerative disease
- Dysregulation of normal tissue turnover and repair
What is the incidence of osteoarthritis like?
- Extremely common age-related disorder
- Major cause of disability and inability to work >50 years
- Increasingly common above 60 years
- Not always symptomatic
What is the primary aetiology of osteoarthritis?
- Idiopathic
- Wear and tear
- Ageing
- Water content of cartilage increases
- Protein makeup of cartilage degenerates
- Repetitive use of joins over years, damage the cartilage –> joint pain and swelling
What is the secondary aetiology of osteoarthritis?
- Complication of other joint disorders
- Mainly inflammatory joint disease
- Trauma to joints
- Congenital joint deformities
What are the pathological changes seen in osteoarthritis?
Changes to:
- Cartilage (progressive loss and destruction)
- Bone (thickening of subchondral bone - the layer of bone just below the cartilage in a joint)
- Synovium (variable degree of inflammation)
- Joint capsule (hypertrophy)
- Secondary effects on muscle due to disuse
- Degeneration of ligaments and menisci of knee
- Formation of osteophytes - a tiny pointed outgrowth of bone, assoc with the degeneration of cartilage at joints
What are the radiological features of osteoarthritis?
- Joint space narrowing
- Subchondral bone sclerosis (stiffening of a tissue) and cysts
- Marginal osteophyte formation
What is rheumatoid arthritis?
Chronic symmetrical inflammatory joint disease (poly-arthritis; involves 5 or more joints simultaneously)
What is the incidence of rheumatoid arthritis like?
- Affects about 1% of UK popn
- Female more than male by about 3:1
- Onset is typically between 35 and 45 years of age
What is the aetiology of rheumatoid arthritis?
Autoimmune disorder
- Exact aetiology uncertain
What are the pathological changes seen in rheumatoid arthritis?
- Synovial hyperplasia
- Inflammatory infiltration resulting in pannus formation; abnormal fibrovascular or granulation tissue growth caused by thickening of the synovium
- Invasion and destruction of articular cartilage
- Focal destruction of bone (erosions)
What are the clinical manifestations of rheumatoid arthritis?
- Symmetrical deforming polyarthritis
- Widespread small joint involvement (hands and feet)
- Medium and large joints also involved
- May be asssoc with non-articular disease
