Osteoarthritis

Question 1

What is the definition of osteoarthritis?

Answer 1

Age-related degenerative synovial joint disease when cartilage destruction exceeds repair, causing pain and disability.

Question 2

What is the aetiology (1o and 2o) of osteoarthritis?

Answer 2

Primary aetiology - unknown. Likely to be multifactorial, “wear and tear” concept proposed in the past

Secondary aetiology - other diseases can cause altered joint architecture and stability. Commonly associated diseases include:

1. Developmental abnormalities (e.g. hip dysplasia, Perthes’ disease, slipped femoral epiphysis)
2. Trauma (e.g. previous fractures)
3. Inflammatory (e.g. rheumatoid arthritis, gout, septic arthritis)
4. Metabolic (e.g. alkaptonuria, haemochromatosis, acromegaly)

Question 3

What is the pathogenesis of osteoarthritis?

Answer 3

Synovial joint cartilage fissuring and fibrillation.

Eventually, there is loss of joint volume as a result of…

• altered chondrocyte activity,
• subchondral sclerosis,
• bone cysts,
• osteophyte formation,
• patchy chronic synovial inflammation
• and fibrotic thickening of joint capsules.

Question 4

How is osteoarthritis classified?

Answer 4

• Primary (idiopathic)
• Secondary

Question 5

What are the most commonly affected joints in osteoarthritis?

Answer 5

Mostly affects:

• hands,
• knee,
• hip,
• or foot (especially the first metatarsophalangeal)

Question 6

Name 2 knee deformities found in osteoarthritis.

Answer 6

genu varum (bow-legs)

genu valgum (knock-knees)

Question 7

How common is osteoarthritis?

Answer 7

Common

25% of those >60 have symptoms and 70% have radiological changes

More common in females, Caucasians and Asians

Question 8

What are the symptoms of arthritis?

Answer 8

• Joint pain or discomfort - use-related
• Stiffness or gelling after inactivity
• Difficulty with certain movement or feelings of instability
• Restriction walking, climbing stairs and manual tasks
• Systemic features are typically present

Question 9

What are the signs of osteoarthritis on examination?

Answer 9

• Local joint tenderness
• Bony swellings along joint margins e.g. Heberden’s nodes (at DIP joints)
• Bouchard’s nodes (at PIP joints)
• Crepitus and pain during joint movement
• Joint effusion
• Restriction of range of joint movement

Question 10

What investigations would you do for OA?

Answer 10

• Joint X Ray - shows 4 classic features.
• Serum CRP and ESR - exclude inflammatory arthritis
• Synovial fluid analysis - clear, viscous with los cell count and cartilage fragments.

Other:

• RF (rheumatoid factor) - negative
• anti-CCP (cyclic citrullinated peptide) - negative

Question 11

What are the 4 key signs of OA on X ray?

Answer 11

• Joint space narrowing (resulting from cartilage loss)
• Subchondral cysts
• Subchondral sclerosis
• Osteophytes

But severity of radiological changes is not a good indicator of symptom severity.