Abstract: Objective To analyze the feature of joint osteochondral lesions under the magnetic resonance imaging (MRI). Methods The finding under MRI in the 68 focal osteochondral lesions were classified with the International Cartilage Repair Society (ICRS) classification, with the emphasis on articular cartilage and subchondral bone lesion.Results 58 lesions were classified as 4 grades: 2 focus of grade Ⅰ, 5 of grade Ⅱ, 14 of grade Ⅲ, 37 of grade Ⅳ. Other 10 focuses were grade Ⅰ of osteochondritis dissecans. MRI can discover subchondral bone lesion which couldn't be observed with arthroscopy. Conclusion MRI can accurately show the focal osteochondral lesions.

Key words: articular cartilage, osteochondral injury, magnetic resonance imaging (MRI)