To the Editor: Calcium pyrophosphate deposition (CPPD) disease is a metabolic arthropathy caused by the deposition of calcium pyrophosphate (CPP) crystals in and around joints, especially in hyaline and fibrous cartilage. CPPD disease is generally categorized into sporadic, familial, and secondary (metabolic) forms. Prevalence increases with age; indeed, radiographic evidence of CPPD is found in up to 40% of elderly subjects. The sporadic form is the most common. Secondary CPPD disease is an infrequent condition related to a variety of metabolic causes including hyperparathyroidism, hypomagnesemia, hypophosphatasia, and hemochromatosis. Familial CPPD disease is characterized by distinctive clinical and radiographic features, but its prevalence is unknown1,2,3,4. Diagnosis requires detection of CPP crystals in synovial fluid1; however, an increasing body of evidence indicates a role for ultrasound (US) as a bedside procedure to improve diagnostic accuracy and clinical decision making in routine rheumatological practice. US possesses some ideal features for assessing crystalline arthropathies. … Address correspondence to Dr. Di Geso; E-mail: lucadigeso{at}libero.it
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