Fig. 2
From: The SP-ET index is a new index for assessing the vertical position of patella
The modified Noyes classification system of patellar cartilage lesions. a Grade 1—increased T2 signal intensity of morphologically normal cartilage; b grade 2A—superficial partial-thickness cartilage defect less than 50% of total articular surface thickness; c grade 2B—deep partial-thickness cartilage defect greater than 50% of the total articular surface thickness; d grade 3—full-thickness cartilage defect