Abstract: ［Abstract］ Objective〖HTSS〗〓To explore a more simple and easytooperate method for estimating knee joint effusion, by application of ultrasound to detect patients with knee joint effusion according to the effusion depth gauge effusion quantity.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓A total of 54 cases of patients with knee joint swelling were enrolled in this study. Application of ultrasound to exam 108 knee joints，81 of the knee joints have effusion. Firstly，61 of the knee joints with effusion were selected for semiquantitative ultrasonic classification. Secondly，the center of suprapatellar, medial and lateral of longitudinal section for measuring surface were selected，effusion depth were measured at fully nonpressurized condition. Finally punctured pumping effusion was guided by ultrasound to record each joint effusion quantity. According to the distribution of effusion， 61 knee joints were divided into three groups.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓There was a significant difference between suprapatellar effusion depth and the medial aspect by ultrasound(P＜005). The consistent grading has a statistically significant between ultrasonic semiquantitative classification and ultrasound guided puncture group，but the degree of consistency was not ideal. By ultrasonic measurement，when effusion volume was less than 20 mL, average depth of effusion was(4.693±1.831) mm，when effusion volume was at the range of 20-40 mL，average depth of effusion was(8.085±1.933) mm，when effusion volume was more than 40 mL， average depth of effusion was(11.027±1.831) mm.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓It is a simple and convenient method to measure the depth of knee joint effusion by ultrasound，which can provide a clinical reference value for estimating the effusion volume.

Key words: knee joint, hydrarthrosis, ultrasonography