Reliability study of the sonographic measurement of the acromiohumeral distance in symptomatic patients

Background. The purpose of this study was to evaluate the inter‐ and intra‐observer reliability and accuracy of sonographic (US) acromiohumeral distance (AHD) measurement for both experienced and novice operators in US in patients suffering from subacromial impingement syndrome. Method. A total of 43 patients (50 shoulders) diagnosed with subacromial impingement syndrome were recruited from an orthopedic outpatient clinic. The US measurement of AHD was obtained consecutively in a neutral position and in a 60° abduction position. A total of 300 blinded measurements were taken. Result. In the neutral abduction group the intra‐ observer interclass correlation coefficient (ICC) was 0.94 for the experienced operator and 0.92 for the novice operator. The inter‐observer ICC was 0.70 and the accuracy was 1.1 mm. In the 60° abduction group, the intra‐observer ICC was 0.90 for the experienced operator and 0.87 for the novice operator. The inter‐observer ICC was 0.64 and the accuracy was 1.4 mm. All ICCs were significant at a level of p < 0.0001. Conclusion. The inaccuracy of the method was 1 mm regardless of the experience of the observer. US AHD measurement in patients with shoulder complaints is not as accurate as reported in healthy subjects. This may have important implications for the clinical use of this parameter. © 2010 Wiley Periodicals, Inc. J Clin Ultrasound, 2010