Objective    Taking arthroscopic diagnosis of meniscus injury as gold standard

to identify the different types of meniscus injury by MR imaging.     Methods    All patients who would receive arthroscopic surgery for meniscus injury or cruciate ligament injury underwent MRI in our unit from Oct. 2006 to Mar. 2007. MR diagnosis of meniscus injury was evaluated by the criteria of Crues et al

then verified by arthroscopic diagnosis.     Results    Totally 268 patients and 288 knees were included. A total of 269 knees of meniscus injury were described by MR diagnosis and 268 knees of meniscus injury were proven by arthroscopy. The sensitivity

specificity and accuracy of MR diagnosis of meniscus injury respectively were 98.5%

84.2% and 97.6%. The signal described as grade Ⅲ in the menisci was a reliable sign of complete meniscal tears.     Conclusion    MR imaging is reliable

highly accurate and noninvasive diagnostic technique for meniscus injury. It is a very important examination before arthroscopy for consummate surgery scheme and prognosis.