In pseudogout, which joint is most commonly affected?

• A. First metatarsophalangeal joint
• B. Hip
• C. Knee
• D. Pubic symphysis

Answer: (C)

Pseudogout is caused by calcium pyrophosphate dihydrate crystals depositing in joints, provoking an acute inflammatory arthritis. The knee is the joint most commonly affected, typically presenting with sudden swelling, warmth, and pain that can be quite dramatic but may resolve over days to weeks. This preference for the knee reflects the large synovial space and cartilage surface in that joint, which readily become sites for crystal deposition and inflammatory response. Imaging often shows chondrocalcinosis in the knee, which supports the diagnosis. While other joints can be involved—such as wrists or shoulders—the first metatarsophalangeal joint is more characteristic of gout, not pseudogout, and the hip or pubic symphysis are less commonly affected in CPPD disease.