Supra spinatous muscle atrophy

Supraspinatus muscle atrophy on MRI: Thomazeau classification
Thomazeau et al, Acta Orthop Scand, 67(3): 264-68, 1996









Stage 1: Normal/ slight atrophy   Occupation ratio(1.00-0.60)
Stage 2: Moderate atrophy       Occupation ratio(0.60-0.40)
Stage 3: Severe atrophy       Occupation ratio(<0.40)

Occupation ratio R = S1 / S2

S1= surface of supraspinatus muscle
S2= surface of entire supraspinatus fossa

Measurement on the scapular cut at level of medial border of spine of scapula