Editorial Commentary: Thickened Meniscus, Extrusion, Truncation, Ghost Sign, Cleft Sign, and Bony Edema Indicate Medial Meniscus Root Tear On Magnetic Resonance Imaging

Abstract

Medial meniscal posterior root tears (MMPRTs) can be challenging to diagnose even on magnetic resonance imaging. Despite several “signs” for MMPRTs, such as the “ghost sign” on sagittal images, truncation or cleft sign on coronal images, bony edema at the tibial root attachment, and meniscal extrusion on coronal images, the finding of increased maximal thickness of the medial meniscus on coronal images provides a simple, intuitive, and reproducible measurement for knee surgeons to identify MMPRTs. With a cutoff of 10 mm providing a sensitivity of 0.771 and specific of 0.942, the thickened meniscus sign is a valuable addition to the MMPRT literature. Even if exact measurements are not used because of racial anatomical or age-related differences in baseline meniscal size, the identification of a thickened medial meniscus on coronal sequences still provides a clue to avoid missing MMPRTs, as well as differentiating them from other meniscal tear patterns, such as radial tears.