Intra-rater reliability of sonographic measurement of the supraspinatus muscle thickness in Empty can, Full can and Hug up tests

Sonography is used for measuring the muscle morphology including length, depth, cross-sectional area, bulk and pennation angle. The supraspinatus is the most common affected muscle among the rotator cuff muscles. There is no study about the reliability of sonographic measurement of supraspinatus thickness in the positions of empty can (EC), full can (FC) and hug up (HU) tests. The present study aims to investigate the intra-rater reliability of the measurement of sonographic thickness of supraspinatus muscle in the rest and positions of the EC, FC and HU tests.
The present study was a descriptive-analytic study which was carried out in a cross-sectional method on ten healthy women aged: 22.10±2.76 years without any tendon pathology. The study was carried out during four weeks (January to March in 2017). The supraspinatus thickness was scanned during rest and contracted states. The positions of measuring ultrasonic thickness of supraspinatus were as follow: position of EC test: the arm in 90-degree elevation in the scaption plane with the thumb-down, position of FC test: the arm in 90-degree elevation in the scaption plane with the thumb-up, position of HU test: the palm of hand was placed on the opposite shoulder with the elbow flexed using a 0.5-kg weight cuff. Intra-rater reliability of ultrasonic muscle thickness measurements were examined in one day.
All intra-rater reliability values were equal or more than 0.90: the value was 0.90 (95%CI: 0.65-0.97) in the rest position, while for the measurement of ultrasonic thickness of the supraspinatus was 0.96 (95%CI: 0.87-0.99) in the position of EC test, 0.97 (95%CI: 0.90-0.99) and 0.96 (95%CI: 0.86-0.99) in the positions of FC and HU tests, respectively.
Measurement of ultrasonic thickness of supraspinatus muscle is a reliable method in the rest and positions of EC, FC and HU tests. This method can be used to compare the muscle thickness changes in the positions of the above tests.