Table 1

Guide for MRI evaluation of meniscus tear based on International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine classification (modified original arthroscopy-based classification)

Criteria for meniscus tear identificationSignal hyperintensity disrupting the articular surface of the meniscus and/or abnormal morphology 
Tear types 
Horizontal tear Runs parallel to the tibial plateau, involves either one of the articular surfaces or the central free edge, dividing the meniscus into superior and inferior portions
Longitudinal tear Runs perpendicular to the tibial plateau and parallel to the long axis of the meniscus, dividing the meniscus into central and peripheral portions
Radial tear Runs perpendicular to both the tibial plateau and the long axis of the meniscus and extends from the free edge towards the periphery along the radial plane of the meniscus (helpful signs- truncated triangle, cleft, ghost, marching cleft)
Bucket-handle tear A longitudinal tear with central migration of the inner ‘handle’ fragment 
Horizontal-flap tear Has a displaced flap component of a predominantly horizontal tear 
Complex tear Encompasses two or more tear directions (patterns). 
Categories 
Tear depth Partial or complete, depending on the tear extending through one or both surfaces of the meniscus. 
Rim width Zone 1: <3 mm, zone 2: 3–5 mm, zone 3: >5 mm
Radial location Posterior, midbody or anterior in location
Central to popliteus hiatus Yes/no. A tear of the lateral meniscus that extends partially or completely in front of the popliteal hiatus should be graded as central to the popliteal hiatus. 
Tear pattern Tears should be graded as per the predominant tear pattern, described previously. Complex tears include two or more tear patterns. 
Quality of the tissue Degenerative characteristics include multiple tear patterns, diffusely increased signal and globular enlargement or irregular meniscal tissue with fibrillation/ fraying changes
Length of tear The distance the tear extends into the meniscus