Inter-rater Reliability of Real-Time Ultrasound to Measure Acromiohumeral Distance

Background: Real-time ultrasound (RTUS) has been suggested as a reliable measure of acromiohumeral distance. However, to date, no vigorous assessment and reporting of inter-rater reliability of this method has been performed with the shoulder in a neutral position or with active and passive arm abduction. Objective: To assess intrasession inter-rater reliability of using RTUS to measure acromiohumeral distance with the shoulder in a neutral position and with 60 degrees active and passive abduction. Study Design: Inter-rater intrasession reliability of repeated measures. Setting: Human performance laboratory. Participants: Twenty persons (12 male and 8 female) with an average age of 29.86 years (standard deviation, 7.8). Method: In an inter-rater, intrasession study, RTUS was used to measure the acromiohumeral distance with the shoulder in a neutral position and with 60 degrees of both active and passive abduction. Main Outcome Measure: Acromiohumeral distance. Results: Intraclass correlation coefficient (ICC)(2.1) scores ranged between 0.65-0.88 (standard error of the mean =0.81-1.2 mm and minimal detectable differences with 95% confidence -2.2-2.3 mm) for inter-rater intrasession reliability. Conclusion: RTUS was found to have fair to good inter-rater reliability as a tool to measure acromiohumeral distance with the shoulder in a neutral position and with 60 degrees of both active and passive arm abduction.