Rheumatoid arthritis vs Osteoarthritis
How to tell Rheumatoid arthritis and Osteoarthritis apart when a board question makes them look alike.
RA is inflammatory symmetric MCP/PIP disease with long stiffness; OA is degenerative use-related DIP/PIP or weight-bearing disease with brief stiffness.
Side by side
Rheumatoid arthritis causes symmetric inflammatory small-joint arthritis, prolonged morning stiffness, MCP/PIP involvement, erosions, nodules, and systemic autoimmune features.
Osteoarthritis causes degenerative joint pain worse with use, brief morning stiffness, DIP/PIP bony enlargement, crepitus, and asymmetric weight-bearing joint involvement.
Autoimmune synovitis with pannus formation erodes cartilage and bone.
Mechanical cartilage degeneration and subchondral bone remodeling produce osteophytes and joint-space narrowing.
Anti-CCP, rheumatoid factor, elevated inflammatory markers, marginal erosions, and ulnar deviation support RA.
Heberden nodes, Bouchard nodes, osteophytes, subchondral sclerosis, and joint-space narrowing support OA.
The trap
Both cause joint pain and hand findings, so inflammatory timing and joint distribution separate them.
Watch it explained
Test it nowThe repair move
For joint pain, ask inflammatory or mechanical first: (1) morning stiffness lasting over 60 minutes that improves with use plus symmetric small-joint involvement at MCP and PIP joints plus systemic features (fatigue, weight loss, rheumatoid nodules, low-grade fever, anemia) plus elevated CRP and ESR equals inflammatory arthritis (work up rheumatoid arthritis with anti-CCP and RF; anti-CCP is more specific; the DIP joints are usually spared, unlike osteoarthritis); (2) brief morning stiffness under 30 minutes that worsens with use plus asymmetric DIP and PIP involvement (Heberden and Bouchard nodes) plus weight-bearing joint involvement (knee, hip, lumbar spine) plus no systemic features equals mechanical osteoarthritis; (3) treat: RA needs DMARDs early (methotrexate is the anchor; add biologic TNF inhibitors, B-cell depletion with rituximab, or JAK inhibitors if inadequate response); OA gets weight loss, physical therapy, topical NSAIDs, intra-articular injections, and joint replacement when severe.
Try a free question
CoreA 42-year-old woman has 6 months of symmetric joint pain and 2 hours of morning stiffness in her hands. Exam shows tender, swollen MCP and PIP joints bilaterally. Labs: ESR 64 mm/hr, CRP 24 mg/L, anti-CCP positive, rheumatoid factor positive. Hand x-rays show periarticular osteopenia and early marginal erosions. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Rheumatoid arthritis. RA is symmetric inflammatory polyarthritis with prolonged morning stiffness, MCP/PIP involvement, anti-CCP and RF positivity, elevated inflammatory markers, and erosive disease on imaging.
Why the other choices are tempting
- B. Osteoarthritis involves DIP joints (Heberden nodes) and weight-bearing joints, with brief morning stiffness <30 min and no erosions.
- C. Psoriatic arthritis has psoriasis, nail pitting, and DIP/dactylitis patterns.
- D. SLE has multisystem involvement with rash, nephritis, and ANA/anti-dsDNA positivity.
- E. Gout is acute monoarticular with hyperuricemia and crystal-proven arthritis.
Flashcards
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What antibody is specific for RA?
Anti-CCP is relatively specific for rheumatoid arthritis.
What hand joints does RA often affect?
RA often affects MCP and PIP joints while sparing DIP joints.
Quick answers
What is the fastest way to tell Rheumatoid arthritis from Osteoarthritis?
RA is inflammatory symmetric MCP/PIP disease with long stiffness; OA is degenerative use-related DIP/PIP or weight-bearing disease with brief stiffness.
What is the key clue for Rheumatoid arthritis?
Rheumatoid arthritis causes symmetric inflammatory small-joint arthritis, prolonged morning stiffness, MCP/PIP involvement, erosions, nodules, and systemic autoimmune features.
What is the key clue for Osteoarthritis?
Osteoarthritis causes degenerative joint pain worse with use, brief morning stiffness, DIP/PIP bony enlargement, crepitus, and asymmetric weight-bearing joint involvement.
What is the common trap with Rheumatoid arthritis vs Osteoarthritis?
Both cause joint pain and hand findings, so inflammatory timing and joint distribution separate them.