Compare OA AND RA FOR MEDICINE MBBS
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Osteoarthritis (OA) vs Rheumatoid Arthritis (RA)
| Feature | Osteoarthritis (OA) | Rheumatoid arthritis (RA) |
|---|---|---|
| Basic pathology | Degenerative joint disease with progressive loss of articular cartilage and bony remodeling | Chronic systemic autoimmune inflammatory synovitis causing cartilage and bone destruction |
| Usual age | Usually older adults, often >50 years | Any age, commonly 30-50 years; females more affected |
| Risk factors | Age, obesity, prior injury, repetitive joint loading, malalignment | Female sex, family history, smoking, autoimmune predisposition |
| Onset | Insidious, slowly progressive | Insidious but may progress over weeks to months |
| Joint distribution | Often asymmetric; weight-bearing and mechanically stressed joints | Typically symmetric polyarthritis |
| Common joints | Knees, hips, cervical/lumbar spine, first CMC, DIP and PIP joints | MCP, PIP, wrists, MTP joints, cervical spine |
| DIP involvement | Common, with Heberden nodes | Usually spared |
| First CMC joint | Frequently affected | Usually spared |
| MCP joints | Usually spared | Characteristically involved |
| Hip involvement | Common | Less common than small-joint disease |
| Type of pain | Worse with activity/use; relieved by rest initially | Worse after rest or inactivity; improves with gentle movement |
| Morning stiffness | Brief, usually <30 minutes | Prolonged, typically >1 hour |
| Swelling | Hard, bony enlargement; little true synovitis | Soft, boggy, warm synovial swelling |
| Crepitus | Common | Not a prominent early feature |
| Systemic features | Absent | May have fatigue, low-grade fever, weight loss, anemia, extra-articular disease |
| Deformities | Bony enlargement, reduced movement; usually late | Ulnar deviation, swan-neck deformity, boutonniere deformity, Z-thumb, subluxation |
| Extra-articular manifestations | None | Rheumatoid nodules, interstitial lung disease, pleuritis, pericarditis, scleritis, vasculitis, neuropathy |
| Inflammatory markers | Usually normal | ESR and CRP often elevated |
| Rheumatoid factor | Negative | Often positive, but not diagnostic alone |
| Anti-CCP antibody | Negative | More specific for RA; predicts erosive disease |
| Synovial fluid | Non-inflammatory: usually <2,000 WBC/mm³ | Inflammatory: usually 2,000-50,000 WBC/mm³, predominantly neutrophils |
| X-ray findings | Non-uniform joint-space narrowing, osteophytes, subchondral sclerosis, subchondral cysts | Uniform joint-space narrowing, marginal erosions, periarticular osteopenia, soft-tissue swelling, deformity |
| Main treatment principle | Reduce pain, maintain function, address biomechanics and weight | Start early disease-modifying therapy to prevent irreversible erosions and disability |
| Drugs commonly used | Topical/oral NSAIDs if appropriate, paracetamol has limited benefit, intra-articular corticosteroid for selected joints | DMARDs such as methotrexate first-line, often with short-term glucocorticoid bridge; biologic/targeted DMARDs if needed |
| Role of surgery | Joint replacement for severe end-stage disease | Synovectomy or joint replacement for advanced damaged joints, after disease control |
Key exam points
- OA is mechanical and degenerative: pain increases with use, stiffness is short-lived, and X-ray shows osteophytes and subchondral sclerosis.
- RA is inflammatory and autoimmune: symmetric small-joint involvement, morning stiffness >1 hour, systemic manifestations, and X-ray shows marginal erosions and periarticular osteopenia.
- OA commonly affects DIP joints and first CMC. RA characteristically affects MCP, PIP, and wrist joints, while DIP joints are usually spared.
- RA needs early DMARD treatment, particularly methotrexate unless contraindicated. NSAIDs relieve symptoms but do not prevent erosions.
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