L09- Common joint pathologies

Question 1

What are the articular surface of bones in synovial joints covered by?

Answer 1

Thin layer of hyaline cartilage

Question 2

What is the function of the viscous synovial fluid?

Answer 2

• Lubrication
• Shock absorption
• Nutrient distribution

Question 3

What are synovial joints surrounded by?

Answer 3

A fibrous capsule

- Capsule reinforced externally or internally (or both) by fibrous ligaments

Question 4

What are bursae?

Answer 4

Fluid filled sacs that facilitate smooth movement between articulating structures

Question 5

Which structures provide stability to the synovial joints?

Answer 5

• Muscles
• Ligaments
• Capsule

Question 6

What’s the normal colour/ consistency of healthy synovial fluid?

Answer 6

• Viscous (less viscous may indicate inflammation)
• Clear and colourless or straw coloured
• Abnormal may be cloudy, opaque or coloured

Question 7

What is infective (septic) arthritis?

Answer 7

• 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

Question 8

What are the risk factors for infective (septic) arthritis?

Answer 8

• Breach of skin barrier
• Immunosuppression for any cause
• Extremes of age
• Underlying inflammatory arthritis
• Joint replacement

Question 9

What are the different possible routes of infection?

Answer 9

• Via blood stream (haematogenous route)
• Directly into joints (wound/ needle)
• From a skin/ tissue infection
• From a bone infection

Question 10

What are the possible consequences of untreated infection?

Answer 10

• 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

Question 11

What is gout?

Answer 11

• 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

Question 12

What’s the incidence of gout like?

Answer 12

• More common in men (middle age onwards)

- Post-menopausal women

Question 13

What is the primary aetiology of gout?

Answer 13

• Idiopathic (unknown cause)

- Usually due to impaired excretion of uric acid by kidney; may be family tendency

Question 14

What is the secondary aetiology of gout?

Answer 14

• 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

Question 15

What are the pathological changes seen in gout?

Answer 15

• 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)

Question 16

What is a tophus (tophaceous deposits)?

Answer 16

Deposit of monosodium urate crystals

Question 17

What is osteoarthritis?

Answer 17

• Predominantly degenerative disease

- Dysregulation of normal tissue turnover and repair

Question 18

What is the incidence of osteoarthritis like?

Answer 18

• Extremely common age-related disorder
• Major cause of disability and inability to work >50 years
• Increasingly common above 60 years
• Not always symptomatic

Question 19

What is the primary aetiology of osteoarthritis?

Answer 19

• 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

Question 20

What is the secondary aetiology of osteoarthritis?

Answer 20

• Complication of other joint disorders
• Mainly inflammatory joint disease
• Trauma to joints
• Congenital joint deformities

Question 21

What are the pathological changes seen in osteoarthritis?

Answer 21

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

Question 22

What are the radiological features of osteoarthritis?

Answer 22

• Joint space narrowing
• Subchondral bone sclerosis (stiffening of a tissue) and cysts
• Marginal osteophyte formation

Question 23

What is rheumatoid arthritis?

Answer 23

Chronic symmetrical inflammatory joint disease (poly-arthritis; involves 5 or more joints simultaneously)

Question 24

What is the incidence of rheumatoid arthritis like?

Answer 24

• Affects about 1% of UK popn
• Female more than male by about 3:1
• Onset is typically between 35 and 45 years of age

Question 25

What is the aetiology of rheumatoid arthritis?

Answer 25

Autoimmune disorder

- Exact aetiology uncertain

Question 26

What are the pathological changes seen in rheumatoid arthritis?

Answer 26

• 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)

Question 27

What are the clinical manifestations of rheumatoid arthritis?

Answer 27

• Symmetrical deforming polyarthritis
• Widespread small joint involvement (hands and feet)
• Medium and large joints also involved
• May be asssoc with non-articular disease