Introduction: Knee joint injection is a daily procedure in orthopedic outpatient visit. In order to obtain the maximum therapeutic benefit, it is necessary to perform the injection directly into the articular space and not into the adjacent structures. Objective: To establish the accuracy of the injection site into the knee joint in patients with grade II-III gonarthrosis. The portal approaches taken into consideration in this study were: Anterolateral (AL), Anteromedial (AM), Lateral Suprapatellar (LSP), Lateral mid-patellar (LMP), Medial mid-patellar (MMP) and Transtendinous (TT). Material and methods: A cross-sectional and descriptive study was conducted. A total of 123 knee joints were injected under fluoroscopy through the different approach portals. Variables: gender, positive arthrography at the first attempt, level of pain in patients during the procedure...