Genicular nerves: ultrasound anatomy, scanning techniques, and clinical implications

The genicular nerves are sensory nerves that innervate the knee joint, playing a crucial role in pain transmission. Because of their small size, they are frequently underappreciated and overlooked during routine ultrasound examinations. With the advent of high-resolution ultrasound, these nerves can be visualized directly, facilitating targeted interventions. A detailed understanding of genicular nerve anatomy, ultrasound landmarks, and characteristic imaging appearances has significant clinical implications for managing knee pain. Given the high prevalence of chronic knee pain due to osteoarthritis and post-operative conditions, ultrasound-guided genicular nerve blocks and radiofrequency ablation are increasingly utilized. Traditionally, genicular nerve procedures, targeting three nerves (the superomedial, superolateral, and inferomedial genicular nerves), were performed under fluoroscopic guidance. However, ultrasound offers distinct advantages, including real-time visualization of soft tissues, the absence of radiation exposure, and precise targeting of anatomical locations using revised landmarks and Doppler signal. These advancements have enabled more comprehensive targeting of five nerves: the superomedial genicular nerve, superolateral genicular nerve, inferomedial genicular nerve, recurrent peroneal genicular nerve, and the infrapatellar branch of the saphenous nerve. Although ablation of the recurrent peroneal genicular nerve carries a risk of injury to the common peroneal nerve, potentially resulting in foot drop, precise localization through ultrasound-guidance may help mitigate this complication. This article provides a comprehensive review of genicular nerve anatomy, ultrasound techniques, and interventional approaches, emphasizing the clinical relevance of ultrasound-guided procedures for managing knee pain and diagnosing nerve pathologies.