Update on ultrasound in crystal arthropathies

Abstract

Crystal-induced arthropathies (CIAs), which include gout, calcium pyrophosphate deposition (CPPD) disease, and basic calcium phosphate deposition (BCPD) disease, are prevalent yet intricate conditions characterized by the deposition of specific crystal types in joints and periarticular tissues. While synovial fluid analysis using polarized light microscopy remains a cornerstone for diagnosis, musculoskeletal ultrasound (US) has emerged as a highly sensitive, non-invasive diagnostic modality for the evaluation of CIAs. The capability of ultrasound to produce real-time, high-resolution, and dynamic imaging positions it as an invaluable tool in the assessment and management of these disorders. In recent years, US has been rigorously studied and validated for its diagnostic accuracy and reliability, particularly in gout and CPPD. Its sensitivity in detecting features such as the double contour sign in gout and CPP aggregates in fibrocartilage and hyaline cartilage in case of CPPD has been well-documented. Conversely, while US is frequently utilized in BCPD for diagnostic purposes, monitoring disease progression, and guiding imaging-assisted procedures, a robust and comprehensive validation of its utility in this condition remains lacking. This review underscores the role of ultrasound in the diagnosis and management of CIAs, with a focus on its applications in gout, CPPD, and BCPD. It discusses its clinical benefits and the current evidence supporting its use. Additionally, the review highlights gaps in research, particularly for BCPD, and outlines future directions to enhance the integration of ultrasound in the diagnostic and therapeutic landscape of CIAs.