High frequency ultrasound imaging and ultrasound elastography in osteoarthritis assessment – current status and future perspectives

Osteoarthritis (OA) is a chronic, debilitating disease primarily affecting articular cartilage, leading to pain, stiffness, and structural joint alterations. In the early stages of OA, changes in cartilage mechanical properties have been observed. Therefore, early and accurate detection of cartilage degeneration is crucial for facilitating OA diagnoses and guiding effective treatment strategies, ultimately improving patient outcomes. Ultrasound (US), including high-frequency B-mode imaging, elastography, and Doppler has emerged as a promising non-invasive imaging technique for assessing OA-related changes in cartilage morphology, mechanical properties, and acoustic characteristics. Given the viscoelastic and complex nature of cartilage, various US elastography techniques have been explored to accurately characterize its mechanical properties. The quasi-static technique, which relies on strain information following compression, faces challenges due to cartilage's viscous nature and boundary conditions. Dynamic elastography has been extensively studied for estimating soft tissue stiffness by calculating displacement and shear wave speed. Recent advancements in this technique have improved its utility as a potential tool for assessing cartilage mechanical properties and aiding in the early detection of OA. However, ongoing developments are required, including enhanced high-resolution imaging and advanced signal processing, to overcome existing limitations. This review paper aims to (1) discuss the role of US in cartilage morphology, mechanical properties, and blood flow for OA diagnoses, (2) review the principles of US elastography techniques, focusing on dynamic method and their role in quantifying cartilage mechanical properties, aiding early diagnosis of OA, (3) analyze pre-clinical and clinical studies that have utilized US B-mode image and elastography to characterize OA disease as well as explore various experimental methods for assessing different grades of OA, and (4) discuss the technical and nontechnical challenges associated with characterizing cartilage stiffness. This review paves the way for future technological advancements in OA diagnosis and treatment by consolidating the current knowledge of US techniques in OA-related musculoskeletal disease.