MRI features of the radial meniscal tears

Abstract

Objective To access the ability of MRI for detecting the radial meniscal tears.Methods Arthroscopy of the knee was performed by a single orthopedic surgeon on 1085 patients. On the basis of the results of arthroscopy, 107(9.9%) knees had radial tears of menisci. Through interval sampling of the patients with meniscal tears but not radial tears, 100 patients were selected as a controlled group. All MR images were analyzed by two radiologists independently. Four radiological signs were used to detect radial tears: cleft and marching cleft sign, detached sign, ghost sign, and small meniscal sign. All the features of MRI were compared with the results of the arthroscopy. Results (1) The most frequent location of radial tears was the midbody of lateral meniscus (71/107, 66. 4%)followed by the boundary of anterior horn and midbody of the lateral meniscus (25/107, 23.4%). (2) One hundred and two of 107 patients were identified as radial tears on MRI. However, 11 of 100 patients with non-radial tears were misdiagnosed as radial tears by MRI. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI were 95.3% (102/107),89.0% (89/100),90.3% (102/113), and 94.7% (89/94),respectively. (3) The cleft sign (59/102, 57.8%) and detached sign (43/102, 42.2%) were the most frequent and important MRI signs. Conclusion The accuracy of MRI to identify the radial meniseal tears'is very high and MRI is the best imaging modality for patients suspected of radial meniscal tears. Key words: Menisci, Tibia; Lacerations; Magnetic resonance imaging; Arthroscopy