Calcium pyrophosphate deposition disease: points to be considered for quality assurance in clinical practice

Calcium pyrophosphate deposition disease is known as crowned dens syndrome or peripheral arthritis, especially of knees, hips and shoulders. The disease course is asymptomatic, with acute or chronic disease activity related to osteoarthritis, especially in the elderly. Other risk factors are joint injury, osteoarthritis and metabolic conditions such as primary hyperparathyroidism, hemochromatosis, hypophosphatasia and hypomagnesemia. Genetic background should be considered before the age of 55 years. Only recently was the value of signs and symptoms weighted, allowing the introduction of classification criteria. Biomarkers include compensated polarized light microscopy findings, laboratory values and imaging. Imaging evidence refers to calcification of the fibrocartilage or hyaline cartilage. Chondrocalcinosis defined as such cartilage calcification is most commonly due to calcium pyrophosphate deposition disease. Calcification of the synovial membrane, joint capsule, or tendon should not be scored. Ultrasonography detects calcium pyrophosphate deposits with more than 80% sensitivity rates, which is superior to conventional radiography. In the future, dual-energy computerized tomography and Raman spectroscopy are promising new techniques to assess disease activity. Currently, the primary therapeutic goal is controlling inflammatory reactions and preventing further episodes. However, only hydroxychloroquine and magnesium carbonate have shown some efficacy and reduction of pain intensity so far. As patients report more significant unmet treatment needs than patients with gout, education is an essential issue of care. The new classification criteria will allow the validation of standardized outcome parameters with the definition of remission and low disease activity for developing treat-to-target strategies to perform well-designed interventional trials evaluating new treatment options and strategies.