Differences between OA and RA

Question 1

Pathogenesis of OA

Answer 1

mechanical- wear and tear destroys articular cartilage (‘degenerative joint disease’)

Question 2

Pathogenesis of RA

Answer 2

autoimmune- inflammatory cytokines and cells induce panes (proliferative granulomatous tissue) formation, which erodes articular cartilage and bone

Question 3

Predisposing factors of OA

Answer 3

age, female, obesity, joint trauma

Question 4

Predisposing factors of RA

Answer 4

female, HLA-DR4, smoking, silica, RF+, ACPA+

Question 5

Presentation of OA

Answer 5

pain in weight-bearing joints after use (e.g. at the end of the day), improving with rest. Asymmetric join involvement. No systemic symptoms

Question 6

Presentation of RA

Answer 6

pain, swelling, and morning stiffness lasting 1+ hr that IMPROVES with use. Symmetric join involvement. Systemic symptoms (fatigue, weight loss, fever)

Question 7

Joint findings of OA

Answer 7

• Osteophytes (bone spurs)
• subchondral sclerosis and cysts
• NON-inflammatory synovial fluid (less than 2000/mm^3)
• Involves DIP (Heberden nodes) and PIP (Bouchard nodes), and 1st CMC; not MCP

Question 8

Joint findings of RA

Answer 8

• juxtaarticular osteopenia
• fingers with ulnar deviation, swan neck, etc.
• Inflammatory synovial fluid (2000+/mm^3)
• Involves MCP, PIP, wrist; not DIP or 1st CMC