Reliability of ultrasound measurement of glenohumeral instability

INTRODUCTION: Ultrasound (US) is an accessible and non-invasive method for assessing pathology in the musculoskeletal system. Its application may include assessment of glenohumeral (GH) instability. Whereas GH instability is typically assessed in symptomatic patients, US measurements of anterior-posterior (AP) GH translation have shown good to excellent reliability in healthy populations. The aim of this study was to test the intra- and interrater reliability of measurements of AP GH translation in a clinical setting. METHODS: Two clinicians performed measures of AP GH translation in patients with anterior shoulder instability. Measurements were conducted from both an anterior and a posterior view. The primary outcome was the intraclass correlation coefficient (ICC(2,1)). RESULTS: Twenty-three patients were included. The intrarater ICCs ranged from 0.70 to 0.76. The interrater ICCs ranged from 0.20 to 0.49. The most reliable test was a simulated "Load and Shift" test. The minimal detectable changes ranged from 2.16 to 3.42 mm for the same rater, and from 2.71 to 4.78 mm between raters. CONCLUSIONS: When performed in a clinical setting by raters with limited US experience, the US measurements of AP GH translation in patients with anterior shoulder instability demonstrated moderate to good intrarater reliability and poor interrater reliability. These findings suggest that while US may have potential for clinical use, its reliability may be limited when performed by novice raters. FUNDING: Amager and Hvidovre Hospitals Forskningspulje. CLINICALTRIALS: gov (ID: NCT05250388).