The "notch" sign: meniscal contour deformities as indicators of tear in MR imaging of the knee.

Conventional magnetic resonance (MR) criteria for meniscal tearing emphasize intrameniscal signal and its communication with the articular surface. In this retrospective study, the value of a focal contour deformity of the meniscal articular surface, termed a "notch," as an additional MR sign of meniscal tearing was assessed. One hundred fifty-four menisci were evaluated. Twenty-three of 24 notches correlated with the site of tear at arthroscopy. Seven notches improved the reading confidence from possible to definite tear; in eight notches, the diagnosis of tear would otherwise not have been considered. Five tears occurred without intrameniscal signal, four following recent trauma. The notch sign improved the sensitivity from 79.8 to 87.8%. Notches are useful additional signs of meniscal tearing, increasing the confidence of a reading when occurring near grade 1 or 2 meniscal signal, and are the only MR sign present in some tears.