Intra-rater reliability of sonographic measurement of the upper trapezius, supraspinatus and deltoid muscles in women with frozen shoulder and healthy women

Background:  Some studies show that frozen shoulder is due to the pathologic changes in the muscles around the shoulder. Measurement of the ultrasonic thickness of a muscle is a method for measuring the muscle changes. There is no study about the reliability of measurement of the muscle’s ultrasonic thickness around the shoulder in patients with frozen shoulder. The present study aims to investigate the intra-rater reliability of the ultrasonic thickness measurement of the supraspinatus, deltoid and upper trapezius muscles in women with frozen shoulder and healthy women. Methods: This study was carried out during 4 months (June to October 2017). Twenty women consisted of 10 patients with frozen shoulder (mean age: 51.6±9.41 years) and 10 healthy subjects (mean age: 35.5±8.22 years) participated in this study. The patients from some clinics and hospitals in Tehran, and healthy subjects consisted of some personals and students in the School of Rehabilitation of Shahid Beheshti university of Medical Sciences participated in the present study. Measurements of ultrasonic thickness of the upper trapezius, supraspinatus and deltoid muscles in rest position carried out by the same rater two times in 48 hours. Ultrasonography instrument with linear probe (frequency: 7.5 MHz) were used for measurement of muscle thickness in millimeter. Results: Reliability of the ultrasonic measurements of the muscle thickness in patients and healthy subjects was respectively as follow: The upper trapezius muscle (0.81, 0.81), the supraspinatus muscle (0.90, 0.92) and the middle deltoid muscle (0.93, 0.96). The reliability of the ultrasonic measurements of the muscle thickness for the upper trapezius muscle and the supraspinatus muscle was higher in healthy subjects compared to the patients with frozen shoulder. The reliability of the ultrasonic measurements of the middle deltoid thickness for the patients and healthy subjects was similar. Conclusion: It seems that ultrasonography is a reliable method for measuring the thickness of the muscles around the shoulder in patients with frozen shoulder and healthy subjects.