Abstract：Objective To investigate the MRI manifestations of meniscus lower surface tear (MLST) and the differences from those of meniscus tears classified by traditional methods. Methods Using “bucket-handle tear”, “horizontal tear” and “complex tear” as keywords, cases involving MRI of knees in the hospital picture archiving and communication system (PACS) were retrieved from June 2018 to June 2021. A total of 28 patients were included in the study based on the criteria of “defects on the lower surface, integrity on the upper surface, and displaced meniscus fragments that match the shape and size of the defects on the lower surface”. Direct signs of MRI (tear features, locations and directions of displacement) and indirect signs were observed. Results Twenty-eight cases had lower surface defects of the meniscus, 24 cases had upper surface integrity, 28 cases had horizontal combined with longitudinal tears, 12 cases had tears in the body of the meniscus and 7 cases had tears in the body combined with the posterior horn, 4 cases had tears confined to the “red zone” of the meniscus and 24 cases had tears in the “white zone”. Nineteen cases had posterior horn displacement of meniscus fragments, 14 cases had intercondylar fossa displacement, 18 cases had broken bow tie signs, 15 cases had posterior horn abnormal hypertrophy signs, 9 cases had flipped meniscus signs, 8 cases had lava flow signs, 6 cases had internal displaced fragments signs, 6 cases had abnormal circumferential meniscus signs, 5 cases had double anterior horn signs, 4 cases had double posterior cruciate signs and 3 cases had empty bow tie signs. Conclusion MLST have characteristic MRI manifestations, and it is of great significance to distinguish MLSTs from traditionally-classified meniscal tears.
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2022, Vol. 33 
