Noyes grading system:
Grade 0: Normal
Grade 1: Cartilage softening without surface abnormality
Grade 2: Erosions or fissures with depth not more than 50% of caartilage thickness
Grade 3: Erosions or fissures with depth more than 50% of caartilage thickness, but less than 100%
Grade 4: Cartilage lesion to subchondral bone
References:
1. Duc SR et al. Diagnosis of Articular Cartilage Abnormalities of the Knee: Prospective Clinical Evaluation of a 3D Water-Excitation True FISP Sequence. Radiology 2007;243:475-482
