Chronic gout is characterized by tophi, which are the collections of monosodium urate crystals and frequently located in subcutaneous and synovial tissues.1 Although the knee is the third most commonly involved joint and intra-articular and periarticular tophi deposition has been previously reported,2 internal derangement due to tophaceous gout is very unusual.3 Here we describe a patient with multiple tophi causing knee joint derangement shown by magnetic resonance imaging.A 53-year-old man presented with pain and locking sensation in the right knee particularly when he walked down stairs. He has intermittent acute monoarthritis for 10 years. He noticed that arthritis attacks were mostly related with the consumption of alcoholic beverages and shellfish. On physical examination, there was soft tissue swelling in both olecranon bursae (A) compatible with tophi. His right knee was both swollen and deformed, and range of movement was restricted. Anterior drawer test was positive in the right knee. Laboratory analysis showed a serum uric acid level of 10.2 mg/dL. Anteroposterior (B) and lateral (C) radiograph of the right knee showed narrowing of medial joint space, osteophytic new bone formation, and subchondral lu-cencies. On the posterior side of the joint, multiple rounded opacities were observed, suggesting synovial chondromatosis.
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