Objectives of the study were to observe supraspinatus muscle thickness in patients with supraspinatus tendon pathology using ultrasound (US) and examining inter- and intra-rater reliability, and to compare muscle thickness with cross-sectional area (CSA) and occupation ratio measured by both US and magnetic resonance imaging (MRI). The investigation was designed as a prospective cohort study. Two groups of patients were included in the study: 43 patients with tendon rupture and 44 patients without tendon rupture as a control group. A written consent was obtained from all patients. In both groups, muscle thickness, CSA and occupation ratio were measured with US, and CSA and occupation ratio with MRI. Study results showed statistically significant between-group differences. The mean supraspinatus muscle thickness measured by US was 14.01 mm and 19.83 mm in patients with and without tendon rupture, respectively. CSA and occupation ratio measured by US and MRI also showed statistically significant between-group differences. Pearson correlation coefficient between supraspinatus thickness and occupation ratio and CSA measured by US and MRI showed strong to moderate correlation. US measurements showed moderate to strong intra- and inter-rater reliability. In conclusion, supraspinatus muscle thickness measurement by US is a reliable method for muscle atrophy evaluation and strongly correlates with other acknowledged methods.
Keywords: Magnetic Resonance Imaging; Muscular Atrophy; Rotator Cuff; Rotator Cuff Injuries; Tendon Injuries; Ultrasonography.