Contractile property measurement of the torn supraspinatus muscle using real-time tissue elastography.

Hypothesis: In the restoration of shoulder abduction, decreased contractility of the torn rotator cuff muscle may be a cause of a poor result. The aim of this study was to investigate the relationship between the contractile property of the torn supraspinatus muscle measured by real-time tissue elastography and the Goutallier stage as modified by Fuchs et al. METHODS: The muscular hardness of the torn supraspinatus muscle was measured in 32 patients at rest and during isometric contraction with the shoulder abducted to 60° in the scapular plane. The muscular hardness was calculated as the strain ratio. Fatty degeneration was assessed according to the modified Goutallier stage. Because the activity value (defined as the difference between the strain ratio at rest and the strain ratio during isometric contraction) estimated the contractile property of the muscle, stepwise multiple regression analysis was used to compare the activity value with age, sex, side, time from injury onset to obtaining the measurements, and modified Goutallier stage.

Results: The mean activity value was 0.26 ± 0.16. Fatty degeneration of the supraspinatus muscle was grade 0 in 5 patients, grade 1 in 16, grade 2 in 10, and grade 3 in 1. The activity value was significantly correlated only with the modified Goutallier stage (r = -0.78, P < .001).

Conclusion: The contractile property of the supraspinatus muscles decreased with an increase in the modified Goutallier stage. Real-time tissue elastography can measure the contractile property of the muscles before surgery and thus may be a predictor for the resulting restoration of lost muscle function.