USMSIT/NMUSIT Fundamental Guide on Diagnostic and Interventional Knee Ultrasonography.

Knee pain is one of the most prevalent musculoskeletal complaints and a leading cause of disability, particularly in middle-aged and older adults. Owing to the knee's complex anatomy and its essential role in weight bearing and locomotion, an accurate diagnosis of knee disorders remains challenging. Although radiography and magnetic resonance imaging are indispensable for structural evaluation, musculoskeletal ultrasound (US) has gained recognition as an effective first-line imaging modality because of its real-time visualization, dynamic assessment capability, absence of ionizing radiation, and cost-effectiveness. This guideline follows the EURO-MUSCULUS/USPRM framework to present a standardized, anatomy-based approach to knee ultrasonography, with emphasis on optimal patient positioning and systematic examination of the anterior, medial, lateral, and posterior compartments. Key anatomical structures - including the suprapatellar recess, quadriceps and patellar tendons, medial/lateral collateral ligaments, menisci, iliotibial band, posterior cruciate ligament, and the semimembranosus-gastrocnemius bursa - are detailed alongside their corresponding sonographic landmarks. Common knee pathologies, such as joint effusion, synovial hypertrophy, tendinopathy, ligament and meniscal tears, iliotibial band syndrome, and Baker's cysts, are illustrated with characteristic grayscale and Doppler US features. In addition, practical guidance on US-guided knee interventions, including suprapatellar joint injection, bursal injections, and Baker's cyst aspiration, is provided. By integrating standardized scanning protocols with interventional techniques, this guideline seeks to improve diagnostic reproducibility, enhance recognition of common knee pathologies, and promote the routine clinical adoption of musculoskeletal US in knee assessment.