Purpose: The purpose of this study was to compare meniscal lesions observed arthroscopically with magnetic resonance imaging (MRI) descriptions.

Material and methods: MRI were read by one operator blinded to the arthroscopic findings. The operator noted the presence or absence of lesions, the topography of the lesion, and the Trillat classification. 188 menisci were studied in 94 patients.

Results: Arthroscopically there were 90 healthy menisci and MRI described 89 healthy menisci, giving an arthroscopic specificity of 98.9%. There were 98 meniscal lesions arthroscopically and 95 at MRI, giving 96.6% sensitivity. The medial meniscus was damaged in 78 cases and the lateral meniscus in 20. Arthroscopy and MRI found the same type of lesion in 62 of 98 cases, identified on the medial meniscus in 47 out of 78 and the lateral meniscus for 15 out of 20. MRI recognised 25/29 horizontal lesions but only one radial lesion of the medial meniscus among the seven cases identified arthroscopically. The topography was concordant in 18/98 cases. MRI oversized the lesion in 54/98 cases.

Discussion: MRI remains the gold standard complementary examination for the diagnosis of meniscal lesions, with high sensitivity and specificity. The precise anatomic description of the lesion provided by the MRI corresponds less well with the arthroscopic findings. Certain lesions appear to be easier to identify, particularly horizontal lesions, while others, particularly radial lesions, are more difficult to demonstrate.