A 55-year-old woman presents with bilateral knee pain that is worse after prolonged activity and relieved by rest. X-rays show joint space narrowing, subchondral sclerosis, osteophytes, and subchondral cysts. She has no morning stiffness beyond 20 minutes. The most likely diagnosis is:

• A Osteoarthritis ✓
• B Rheumatoid arthritis
• C Pseudogout (calcium pyrophosphate deposition)
• D Psoriatic arthritis

Explanation

Osteoarthritis is a degenerative joint disease characterised by cartilage loss, subchondral bone thickening, osteophyte formation, and subchondral cyst formation. Pain is mechanical — worsened by activity and relieved by rest — in contrast to the prolonged (>1 hour) morning stiffness of rheumatoid arthritis. The X-ray LOSS mnemonic (Loss of joint space, Osteophytes, Subchondral sclerosis, Subchondral cysts) defines the radiological features. Weight-bearing joints — hips and knees — are most commonly affected.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.