Muskuloskeletal - Osteoarthritis

Question 1

What is the aetiology of OA?

Answer 1

Wear and tear

Question 2

What is the pathophysiology of OA?

Answer 2

1. Cartilage degradation
   Risk factors ppt wear and tear of cartilage
   Triggers chondrocyte to produce less proteoglycans and switch from producing type II collagen –> type I collagen
   Type I collagen interacts differently w prosteoglycans –> weaker, less elastic cartilage
   Over time prosteoglycans cannot keep up –> apoptosis
   Weaker, softer, less elastic cartilage may form cracks on cleft (fibrillation) or cartilage shards
2. Synovial inflamm
   Inflamm macrophages and leukocyte recruited to site –> inflamm
   Disease progression mediated by proinflamm cytokines and damage associated molecular patterns (DAMPs)
   Inflamm causes damage to cartilage, exposes bone, causes friction to bone –> brittle
3. Bone remodelling & osteophyte formation
   Sclerosis= widening of bone below cartilage
   Osteophyte = formation of new bone to compensate ill-fitting bones

Question 3

What are the stages of OA pathophysiology?

Answer 3

Cartilage degradation
Synovial Inflamm
Bone remodelling & osteophyte formation

Question 4

What are the risk factors of OA?

Answer 4

• Age
• Changes in ECM: thinning, decreased hydration, increased brittleness
• Gender
• Occupation
• Obesity/heavy wt
• Physical or sports injuries
• Genetics
• Rare mutations in collagen types II, IX, XI, GDF-5)
• Anatomic factors (abnormalities)
• E.g. Varus alignment aka “bow-legged”, valgus alignment aka “knocked knee”
• Best to hv good alignment for locomotion - otherwise uneven wearing of joint cartilage

Question 5

Describe the epidemiology of OA

Answer 5

• Most common inflamm joint disorder
• Affects abt 12% of population
• <50y.o.: M > W
• > 70y.o.: W > M (esp OA in hands)

Question 6

What are the signs and symptoms of OA?

Answer 6

Signs:
Asymmetrical mono/polyarticular
Crepitus
Reduced range of motion
Transient joint effusion
Palpable warmth
Bone tenderness
Bone enlargement
Osteocytes
Increased ESR (>20mm/h)

Symptoms:
Worse on activity
Better w rest
Pain
Erythema
Warmth
Tenderness
Swelling
Stiffness on waking less than 30min
Anxiety, depression
Sleep disturbance