Assessment of the reliability of real time ultrasound scanning to measure the humeral head position in a number of glenohumeral joint positions

The aim of the current study is to assess the intra-rater and inter-rater reliability of real time ultrasound scanning in measuring static humeral head position. Real time ultrasound scanning, an experimental clinical measurement, was used to record measurements of the humeral head position in a sample of (20) healthy volunteers [9 male, 11 female]. While the participant was seated in a standardized chair, Hips and knees were positioned at 90 degrees of flexion. The humeral head position of each subject was imaged at three ultrasound view [anterior, posterior and superior] in a different arm positions; images were repeated three times for each position by the same examiner on the same day to assess Intra-rater reliability. The Images were then analysed by the researcher and a second investigator to assess inter-tester reliability. Intra-rater and inter-rater reliability were quantified by using the intraclass correlation coefficient and standard error of measurement, the smallest detectable difference values were calculated and were used to estimate the magnitude of change that is predictable to exceed measurement error. The intra-rater reliability for all positions was found to be excellent for all tests ranged from 0.83 to 0.99 respectively. Inter –rater reliability between examiners was found to be good to excellent for all test positions ranged from 0.66 to 0.98, and the standard error of measurement for all positions was less than the calculated mean. This study demonstrates that real time ultrasound scanning is a reliable method of assessing the location of the humeral head in a number of arm positions in healthy subjects when measured by the same examiner and this may suggest that RTUS could be used to assess the impact of rehabilitation programme or surgical interventions for shoulder pathology.