Objective To discuss the diagnostic criteria for discoid meniscus of the knee,and the MRI classif ication and lesion characteristics of bilateral discoid meniscus.Methods We carried out a study of the discoid meniscus with a large sample,and discoid meniscus of the knee was screened out from Noverber 2009 to March 2013.For all the cases,we measured and analyzed the ratio of the width of meniscus to that of tibial plateau on coronal slice,and the thickest thickness of the meniscus posterior horn on butterf l...