Grading of muscular fatty degeneration

Grading of muscular fatty degeneration was performed according to the classification by Goutallier et al. This classification is based on amount of fat in relation to amount of muscle. Stage 0 indicates no fatty degeneration; stage 1, some fatty streaks; stage 2, less fat than muscle; stage 3, as much fat as muscle; and stage 4, more fat than muscle. The Goutallier classification was initially described for CT and was later validated for MRI by Fuchs et al. If fatty degeneration was different in the superior and inferior parts of the subscapularis and infraspinatus muscles, the area with the highest stage was used for classification.